Sample records for rapid initial drop

  1. Rapid determination of caffeine in one drop of beverages and foods using drop-to-drop solvent microextraction with gas chromatography/mass spectrometry. (United States)

    Shrivas, Kamlesh; Wu, Hui-Fen


    A simple and rapid sample cleanup and preconcentration method for the quantitative determination of caffeine in one drop of beverages and foods by gas chromatography/mass spectrometry (GC/MS) has been proposed using drop-to-drop solvent microextraction (DDSME). The best optimum experimental conditions for DDSME were: chloroform as the extraction solvent, 5 min extraction time, 0.5 microL exposure volume of the extraction phase and no salt addition at room temperature. The optimized methodology exhibited good linearity between 0.05 and 5.0 microg/mL with correlation coefficient of 0.980. The relative standard deviation (RSD) and limits of detection (LOD) of the DDSME/GC/MS method were 4.4% and 4.0 ng/mL, respectively. Relative recovery of caffeine in beverages and foods were found to be 96.6-101%, which showing good reliability of this method. This DDSME excludes the major disadvantages of conventional method of caffeine extraction, like large amount of organic solvent and sample consumption and long sample pre-treatment process. So, this approach proves that the DDSME/GC/MS technique can be applied as a simple, fast and feasible diagnosis tool for environmental, food and biological application for extremely small amount of real sample analysis.

  2. Internal rupture and rapid bouncing of impacting drops induced by submillimeter-scale textures (United States)

    Zhang, Rui; Zhang, Xiwen; Hao, Pengfei; He, Feng


    We demonstrate an internal breakup mechanism for high Weber number drop impact on superhydrophobic surfaces uniformly patterned with submillimeter-scale textures, in which the liquid film ruptures from both interior and rim. The employment of submillimeter-scale posts could help decrease the critical Weber number of internal rupture, due to the small solid fraction and the large dimension ratio between primary structures and droplets. The internal rupture is found to promote more rapid drop bouncing than conventional rebound and rim breakup on superhydrophobic surfaces with small roughness, with a 10%-50% reduction of contact time. The internal rupture results from the film instability inside and the jet instability outside.

  3. Internal rupture and rapid bouncing of impacting drops induced by submillimeter-scale textures. (United States)

    Zhang, Rui; Zhang, Xiwen; Hao, Pengfei; He, Feng


    We demonstrate an internal breakup mechanism for high Weber number drop impact on superhydrophobic surfaces uniformly patterned with submillimeter-scale textures, in which the liquid film ruptures from both interior and rim. The employment of submillimeter-scale posts could help decrease the critical Weber number of internal rupture, due to the small solid fraction and the large dimension ratio between primary structures and droplets. The internal rupture is found to promote more rapid drop bouncing than conventional rebound and rim breakup on superhydrophobic surfaces with small roughness, with a 10%-50% reduction of contact time. The internal rupture results from the film instability inside and the jet instability outside.

  4. Rapidly solidified Ag-Cu eutectics: A comparative study using drop-tube and melt fluxing techniques (United States)

    Yu, Y.; Mullis, A. M.; Cochrane, R. F.


    A comparative study of rapid solidification of Ag-Cu eutectic alloy processed via melt fluxing and drop-tube techniques is presented. A computational model is used to estimate the cooling rate and undercooling of the free fall droplets as this cannot be determined directly. SEM micrographs show that both materials consist of lamellar and anomalous eutectic structures. However, below the critical undercooling the morphologies of each are different in respect of the distribution and volume of anomalous eutectic. The anomalous eutectic in flux- undercooled samples preferentially forms at cell boundaries around the lamellar eutectic in the cell body. In drop-tube processed samples it tends to distribute randomly inside the droplets and at much smaller volume fractions. That the formation of the anomalous eutectic can, at least in part, be suppressed in the drop-tube is strongly suggestive that the formation of anomalous eutectic occurs via remelting process, which is suppressed by rapid cooling during solidification.

  5. Shapes and Fissility of Highly Charged and Rapidly Rotating Levitated Liquid Drops (United States)

    Liao, L.; Hill, R. J. A.


    We use diamagnetic levitation to investigate the shapes and the stability of free electrically charged and spinning liquid drops of volume ˜1 ml. In addition to binary fission and Taylor cone-jet fission modes observed at low and high charge density, respectively, we also observe an unusual mode which appears to be a hybrid of the two. Measurements of the angular momentum required to fission a charged drop show that nonrotating drops become unstable to fission at the amount of charge predicted by Lord Rayleigh. This result is in contrast to the observations of most previous experiments on fissioning charged drops, which typically exhibit fission well below Rayleigh's limit.

  6. Specimen design and instrumentation for monitoring fatigue crack growth initiating at ply drops

    DEFF Research Database (Denmark)

    Goutianos, Stergios; Di Crescenzo, Leonardo; McGugan, Malcolm

    Unpredictable and excessive loads, for example caused by aerodynamic interaction between different turbines, can accelerate fatigue damage in wind turbine blades (Ghosal et. al (2000)). Fatigue damage can also initiate in the early service life of a wind turbine blade in regions of stress...... concentration, such as those caused by ply drops (Cairns et al. (1999)). Due to these issues, the design philosophy is based on conservative analysis methods and inspections at certain time intervals are required to assess the damage in the wind blades. An alternative approach is to use damage tolerant...... materials and a structural health monitoring system (McGugan et al. (2015)). In this approach, a distribution of damage types within the blades is accepted as long as they can be detected by structural health monitoring techniques and their severity evaluated by material damage models. The present work aims...

  7. Transport of Substances on Different Stages of Processes Initiated by Free Fallen Drop Impact on Surface of Quiescent Water (United States)

    Ilyinykh, A. Yu.


    Collision of a free fallen drop with a surface of quiescent layer of water initiates a sequence of processes including initial shock, formation of cavern and crown with a chevron edge emitted small water drops, wide central trough surrounding by a train of running surface circular capillary waves, splash, secondary cavern collapsing with a streamer discharge and gradual decal of all disturbances. Fine structure of the drop splashes and transport of substances carrying by the drop inside accepting target fluid are studied by methods of direct registering of flow images by fast video- and photo cameras. Different directions of observations were realized that are side, top and bottom view of flow patterns. Flow patterns produced by clean and coloured water, alcohol (changing the surface tension) and oil drops were investigated. Attention was concentrated on small scale processes dynamics studying which produce fast variations of water surface shapes with sharp local irregularities. Shapes and textures of craters and surrounding rim surfaces as well as coloured filaments of a drop substance inside the fluid body were registered and analyzed. Two groups of flows with relatively large scales defined by the drop diameter and very fine scales were identified. It is supposed that short living and fast changing flow components are result of strong short-acting forces impact. Their manifestations depend on surface tension on the boundaries fluid-fluid and fluid-air. Effects of surface tension gradients on the drop dye propagation pattern are also demonstrated and discussed. Experiments were performed on set-up USU "HPC IPMec RAS" under support of Ministry of Education and Science RF (Goscontract No. 16.518.11.7059).


    Directory of Open Access Journals (Sweden)



    Full Text Available The flow phenomena occurring around a rotating shaft are extremely complex and are a common feature in turbomachinery such as the bearing chambers of aero engines. As the liquid jet impinges onto the shaft, circumferential streams of lubricating liquid droplets centrifuge away from the rotor surface and impinge onto the inner circumference of the stationary case. A further break-up of drops occurred whilst rotating around the shaft before impacting on to the casing surface. Non-intrusive laser techniques have been employed to aid the visualisation processes and the analysis of the flow phenomena occurring within the rotating annular enclosure. Results reveal that, the liquid flow conditions and the shaft rotation regimes, along with the aerodynamic movement of the air circulating around the shaft influence the dynamics of the droplets and consequently the lubrication processes within the bearing chambers.

  9. Study of Hot Salt Stress Corrosion Crack Initiation of Alloy IMI 834 by using DC Potential Drop Method

    Energy Technology Data Exchange (ETDEWEB)

    Pustode, Mangesh D. [Bharat Forge Ltd., Pune (India); Dewangan, Bhupendra [Tata Steel, Jamshedpur (India); Raja, V. S. [Indian Institute of Technology Bombay, Mumbai (India); Paulose, Neeta; Babu, Narendra [Gas Turbine Research Establishment (GTRE), Bangalore (India)


    DC potential drop technique was employed during the slow strain rate tests to study the hot salt stress corrosion crack (HSSCC) initiation at 300 and 400 ℃. Threshold stresses for HSSCC initiation were found to about 88 % of the yield strength at both temperatures, but the time from crack initiation to final failure (Δtscc) decreased significantly with temperature, which reflects larger tendency for brittle fracture and secondary cracking. The brittle fracture features consisted of transgranular cracking through the primary α grain and discontinuous faceted cracking through the transformed β grains.

  10. Rapid intracranial pressure drop as a cause for posterior reversible encephalopathy syndrome: Two case reports. (United States)

    Niwa, Ryoko; Oya, Soichi; Nakamura, Takumi; Hana, Taijun; Matsui, Toru


    Posterior reversible encephalopathy syndrome (PRES) is characterized by reversible edematous lesions on radiological examinations as well as symptoms of altered consciousness and seizures. To date, the underlying mechanism remains largely unknown. Case 1 is a 72-year-old man with a history of hypertension presented with a subarachnoid hemorrhage. Fourteen days after the successful clipping of a ruptured aneurysm; he experienced inadvertent overdrainage via the intraventricular drain. Nine hours later, he started to have seizures followed by disturbances in consciousness. An emergency magnetic resonance imaging showed multiple high-intensity lesions in the frontal, temporal, parietal, and occipital lobes, basal ganglia, brainstem, and cerebellar hemispheres bilaterally, which are compatible with typical magnetic resonance findings in PRES patients. He was treated conservatively and recovered well. Case 2 is a 68-year-old woman with a mild history of hypertension and a ventriculo-peritoneal shunt for obstructive hydrocephalus, who underwent a cysto-peritoneal shunt placement because of an enlarging symptomatic arachnoid cyst. Immediately following surgery, she experienced disturbances in consciousness and developed status epilepticus. Radiological examinations revealed remarkable shrinkage of the arachnoid cyst and multiple edematous lesions, which led us to strongly suspect PRES. With conservative treatment, her symptoms and the radiological abnormalities disappeared. Based on the previous literature and our cases, we believe that the association between rapid reduction of intracranial pressure (ICP) and the development of PRES should be recognized because most neurosurgical procedures such as craniotomy or cerebrospinal fluid diversion present a potential risk of rapid reduction of ICP.

  11. The Wallops Flight Facility Rapid Response Range Operations Initiative (United States)

    Underwood, Bruce E.; Kremer, Steven E.


    becomes how can a launch site provide acceptably responsive mission services to a particular customer without dedicating extensive resources and while continuing to serve other projects? NASA's Wallops Flight Facility (WFF) is pursuing solutions to exactly this challenge. NASA, in partnership with the Virginia Commercial Space Flight Authority, has initiated the Rapid Response Range Operations Initiative (R3Ops). R3Ops is a multi-phased effort to incrementally establish and demonstrate increasingly responsive launch operations, with an ultimate goal of providing ELV-class services in a maximum of 7-10 days from initial notification routinely, and shorter schedules possible with committed resources. This target will be pursued within the reality of simultaneous concurrent programs, and ideally, largely independent of specialized flight system configurations. WFF has recently completed Phase 1 of R3Ops, an in-depth collection (through extensive expert interviews) and software modeling of individual steps by various range disciplines. This modeling is now being used to identify existing inefficiencies in current procedures, to identify bottlenecks, and show interdependencies. Existing practices are being tracked to provide a baseline to benchmark against as new procedures are implemented. This paper will describe in detail the philosophies behind WFF's R3Ops, the data collected and modeled in Phase 1, and strategies for meeting responsive launch requirements in a multi-user range environment planned for subsequent phases of this initiative.


    Directory of Open Access Journals (Sweden)

    Santosh Bhattarai


    Full Text Available Minimizing the thermal cracks in mass concrete at an early age can be achieved by removing the hydration heat as quickly as possible within initial cooling period before the next lift is placed. Recognizing the time needed to remove hydration heat within initial cooling period helps to take an effective and efficient decision on temperature control plan in advance. Thermal properties of concrete, water cooling parameters and construction parameter are the most influencing factors involved in the process and the relationship between these parameters are non-linear in a pattern, complicated and not understood well. Some attempts had been made to understand and formulate the relationship taking account of thermal properties of concrete and cooling water parameters. Thus, in this study, an effort have been made to formulate the relationship for the same taking account of thermal properties of concrete, water cooling parameters and construction parameter, with the help of two soft computing techniques namely: Genetic programming (GP software “Eureqa” and Artificial Neural Network (ANN. Relationships were developed from the data available from recently constructed high concrete double curvature arch dam. The value of R for the relationship between the predicted and real cooling time from GP and ANN model is 0.8822 and 0.9146 respectively. Relative impact on target parameter due to input parameters was evaluated through sensitivity analysis and the results reveal that, construction parameter influence the target parameter significantly. Furthermore, during the testing phase of proposed models with an independent set of data, the absolute and relative errors were significantly low, which indicates the prediction power of the employed soft computing techniques deemed satisfactory as compared to the measured data.

  13. A drop in the pond: the effect of rapid mass-loss on the dynamics and interaction rate of collisionless particles (United States)

    Penoyre, Zephyr; Haiman, Zoltán


    In symmetric gravitating systems experiencing rapid mass-loss, particle orbits change almost instantaneously, which can lead to the development of a sharply contoured density profile, including singular caustics for collisionless systems. This framework can be used to model a variety of dynamical systems, such as accretion discs following a massive black hole merger and dwarf galaxies following violent early star formation feedback. Particle interactions in the high-density peaks seem a promising source of observable signatures of these mass-loss events (i.e. a possible EM counterpart for black hole mergers or strong gamma-ray emission from dark matter annihilation around young galaxies), because the interaction rate depends on the square of the density. We study post-mass-loss density profiles, both analytic and numerical, in idealized cases and present arguments and methods to extend to any general system. An analytic derivation is presented for particles on Keplerian orbits responding to a drop in the central mass. We argue that this case, with initially circular orbits, gives the most sharply contoured profile possible. We find that despite the presence of a set of singular caustics, the total particle interaction rate is reduced compared to the unperturbed system; this is a result of the overall expansion of the system dominating over the steep caustics. Finally, we argue that this result holds more generally, and the loss of central mass decreases the particle interaction rate in any physical system.

  14. First aid to Cultural Heritage. Training initiatives on rapid documentation (United States)

    Almagro Vidal, A.; Tandon, A.; Eppich, R.


    Recent dramatic events have brought to the forefront the debate on how to protect, safeguard and document Cultural Heritage in conflict areas. Heritage places have become battlefields, sources of illicit trafficking and even deliberate targets of destruction because of the politicisation to further conflict ideologies as well as misinterpretation of the values they represent. Is it possible to protect Cultural Heritage under such circumstances? If yes, when is the right time to intervene and who can help in this task? How can documentation and training assist? The International Course on First Aid to Cultural Heritage in Times of Crisis promoted by ICCROM (The International Centre for the Study of the Preservation and Restoration of Cultural Property) in collaboration with various partners focuses specifically on ways to help in such difficult and stressful situations. This paper explores the methodological approach and highlights the special circumstances that surround rapid documentation and preliminary condition assessment in conflict areas, and in cases of complex emergencies such as an earthquake striking a conflict area. The paper identifies international actors that might play a special and crucial role in the first steps of such a situation and recognizes the need for training activities to strengthen capacities for disaster response to cultural heritage at national and regional levels.

  15. First aid to Cultural Heritage. Training initiatives on rapid documentation

    Directory of Open Access Journals (Sweden)

    A. Almagro Vidal


    Full Text Available Recent dramatic events have brought to the forefront the debate on how to protect, safeguard and document Cultural Heritage in conflict areas. Heritage places have become battlefields, sources of illicit trafficking and even deliberate targets of destruction because of the politicisation to further conflict ideologies as well as misinterpretation of the values they represent. Is it possible to protect Cultural Heritage under such circumstances? If yes, when is the right time to intervene and who can help in this task? How can documentation and training assist? The International Course on First Aid to Cultural Heritage in Times of Crisis promoted by ICCROM (The International Centre for the Study of the Preservation and Restoration of Cultural Property in collaboration with various partners focuses specifically on ways to help in such difficult and stressful situations. This paper explores the methodological approach and highlights the special circumstances that surround rapid documentation and preliminary condition assessment in conflict areas, and in cases of complex emergencies such as an earthquake striking a conflict area. The paper identifies international actors that might play a special and crucial role in the first steps of such a situation and recognizes the need for training activities to strengthen capacities for disaster response to cultural heritage at national and regional levels.

  16. An Empirical Method Permitting Rapid Determination of the Area, Rate and Distribution of Water-Drop Impingement on an Airfoil of Arbitrary Section at Subsonic Speeds (United States)

    Bergrun, N. R.


    An empirical method for the determination of the area, rate, and distribution of water-drop impingement on airfoils of arbitrary section is presented. The procedure represents an initial step toward the development of a method which is generally applicable in the design of thermal ice-prevention equipment for airplane wing and tail surfaces. Results given by the proposed empirical method are expected to be sufficiently accurate for the purpose of heated-wing design, and can be obtained from a few numerical computations once the velocity distribution over the airfoil has been determined. The empirical method presented for incompressible flow is based on results of extensive water-drop. trajectory computations for five airfoil cases which consisted of 15-percent-thick airfoils encompassing a moderate lift-coefficient range. The differential equations pertaining to the paths of the drops were solved by a differential analyzer. The method developed for incompressible flow is extended to the calculation of area and rate of impingement on straight wings in subsonic compressible flow to indicate the probable effects of compressibility for airfoils at low subsonic Mach numbers.

  17. Gait assessment during the initial fitting of customized selective laser sintering ankle foot orthoses in subjects with drop foot. (United States)

    Creylman, Veerle; Muraru, Luiza; Pallari, Jari; Vertommen, Helga; Peeraer, Louis


    Recently, additive fabrication has been proposed as a feasible engineering method for manufacturing of customized ankle foot orthoses (AFOs). Consequently, studies on safety, comfort and effectiveness are now carried out to assess the performance of such devices. Evaluate the clinical performance of customized (selective laser sintering) SLS-AFOs on eight subjects with unilateral drop foot gait and compare to clinically accepted (polypropylene) PP-AFOs. Active control trial. For each subject two customized AFOs were fabricated: one SLS-AFO manufactured following an additive fabrication framework and one thermoplastic PP-AFO manufactured according to the traditional handcraft method. Clinical performance of both AFOs was evaluated during gait analysis. A significant beneficial effect of both custom-moulded PP-AFO and customized SLS-AFO in terms of spatial temporal gait parameters and ankle kinematic parameters compared to barefoot gait of adults with drop foot gait are observed. No statistically significant difference between the effect of PP-AFO and of SLS-AFO was found in terms of spatial temporal gait parameters and ankle kinematic parameters. AFOs manufactured through the SLS technique show performances that are at least equivalent to the handcrafted PP-AFOs commonly prescribed in current clinical practice. Clinical relevance Manufacturing personalized AFOs with selective laser sintering (SLS) in an automated production process results in decreased production time and guarantees the consistency of shape and functional characteristics over different production time points compared to the traditional manufacturing process. Moreover, it reduces the dependency of the appliance on the experience and craftsmanship of the orthopaedic technician.

  18. Rapid label-free identification of Klebsiella pneumoniae antibiotic resistant strains by the drop-coating deposition surface-enhanced Raman scattering method (United States)

    Cheong, Youjin; Kim, Young Jin; Kang, Heeyoon; Choi, Samjin; Lee, Hee Joo


    Although many methodologies have been developed to identify unknown bacteria, bacterial identification in clinical microbiology remains a complex and time-consuming procedure. To address this problem, we developed a label-free method for rapidly identifying clinically relevant multilocus sequencing typing-verified quinolone-resistant Klebsiella pneumoniae strains. We also applied the method to identify three strains from colony samples, ATCC70063 (control), ST11 and ST15; these are the prevalent quinolone-resistant K. pneumoniae strains in East Asia. The colonies were identified using a drop-coating deposition surface-enhanced Raman scattering (DCD-SERS) procedure coupled with a multivariate statistical method. Our workflow exhibited an enhancement factor of 11.3 × 106 to Raman intensities, high reproducibility (relative standard deviation of 7.4%), and a sensitive limit of detection (100 pM rhodamine 6G), with a correlation coefficient of 0.98. All quinolone-resistant K. pneumoniae strains showed similar spectral Raman shifts (high correlations) regardless of bacterial type, as well as different Raman vibrational modes compared to Escherichia coli strains. Our proposed DCD-SERS procedure coupled with the multivariate statistics-based identification method achieved excellent performance in discriminating similar microbes from one another and also in subtyping of K. pneumoniae strains. Therefore, our label-free DCD-SERS procedure coupled with the computational decision supporting method is a potentially useful method for the rapid identification of clinically relevant K. pneumoniae strains.

  19. Ionic-liquid-assisted microwave distillation coupled with headspace single-drop microextraction followed by GC-MS for the rapid analysis of essential oil in Dryopteris fragrans. (United States)

    Jiao, Jiao; Gai, Qing-Yan; Wang, Wei; Luo, Meng; Zhao, Chun-Jian; Fu, Yu-Jie; Ma, Wei


    A rapid, green and effective miniaturized sample preparation technique, ionic-liquid-assisted microwave distillation coupled with headspace single-drop microextraction was developed for the extraction of essential oil from dried Dryopteris fragrans. 1-Ethyl-3-methylimidazolium acetate was the optimal ionic liquid as the destruction agent of plant cell walls and microwave absorption was medium. n-Heptadecane (2.0 μL) was adopted as the suspended microdrop solvent in the headspace for the extraction and concentration of essential oil. The optimal parameters of the proposed method were an irradiation power of 300 W, sample mass of 0.9 g, mass ratio of ionic liquids to sample of 2.8, extraction temperature of 79°C, and extraction time of 3.6 min. In comparison to the previous reports, the proposed technique could equally monitor all the essential oil components with no significant differences in a simple way, which was more rapid and required a much lower amount of sample. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Foot Drop (United States)

    ... Seizures Information Page Fibromuscular Dysplasia Information Page Foot Drop Information Page Friedreich's Ataxia Information Page Gaucher Disease Information Page Generalized Gangliosidoses Information Page Gerstmann's Syndrome ...

  1. Rapid analysis of Fructus forsythiae essential oil by ionic liquids-assisted microwave distillation coupled with headspace single-drop microextraction followed by gas chromatography-mass spectrometry. (United States)

    Jiao, Jiao; Ma, Dan-Hui; Gai, Qing-Yan; Wang, Wei; Luo, Meng; Fu, Yu-Jie; Ma, Wei


    A rapid, green and effective miniaturized sample preparation and analytical technique, i.e. ionic liquids-assisted microwave distillation coupled with headspace single-drop microextraction (ILAMD-HS-SDME) followed by gas chromatography-mass spectrometry (GC-MS) was developed for the analysis of essential oil (EO) in Fructus forsythiae. In this work, ionic liquids (ILs) were not only used as the absorption medium of microwave irradiation but also as the destruction agent of plant cell walls. 1-Ethyl-3-methylimidazolium acetate ([C2mim]OAc) was chosen as the optimal ILs. Moreover, n-heptadecane (2.0 μL) was selected as the appropriate suspended solvent for the extraction and concentration of EO. Extraction conditions of the proposed method were optimized using the relative peak area of EO constituents as the index, and the optimal operational parameters were obtained as follows: irradiation power (300 W), sample mass (0.7 g), mass ratio of ILs to sample (2.4), temperature (78°C) and time (3.4 min). In comparison to previous reports, the proposed method was faster and required smaller sample amount but could equally monitor all EO constituents with no significant differences. Copyright © 2013 Elsevier B.V. All rights reserved.

  2. Early initiation of postpartum contraception: does it decrease rapid repeat pregnancy in adolescents? (United States)

    Damle, Lauren F; Gohari, Amir C; McEvoy, Anna K; Desale, Sameer Y; Gomez-Lobo, Veronica


    Rapid repeat adolescent pregnancy is a significant public health concern. An effective and practical means of decreasing unintended second adolescent pregnancies needs to be identified. The objective of this study is to determine if early initiation of contraception, and in particular long acting reversible contraception (LARC), decreases rapid repeat pregnancy among first time adolescent mothers. Retrospective cohort study. Urban teaching hospital. 340 first-time adolescent mothers age ≤ 19. None, study was retrospective. Repeat pregnancy within 2 years. 340 first time adolescent mothers with a documented follow-up time of 2 years had a repeat pregnancy rate of 35%. Average time from delivery to repeat pregnancy was 9.9 ± 6.4 months. Logistic regression analysis comparing adolescents with and without repeat pregnancy revealed that leaving the hospital postpartum without initiating any contraception was associated with significant increase risk of repeat pregnancy (OR = 2.447, 95% CI 1.326-4.515). Follow-up within 8 weeks postpartum was associated with lower chance of repeat pregnancy (OR = 0.322, 95% CI 0.172-0.603). Initiation of a LARC method (either an intrauterine device or etonogestrel subdermal implant) by 8 weeks postpartum was also associated with decreased chance of rapid repeat pregnancy (OR = 0.118, 95% CI 0.035-0.397). Adolescent mothers who initiate a LARC method within 8 weeks of delivery are less likely to have a repeat pregnancy within 2 years than those who choose other methods or no method. First time adolescent mothers should be counseled about this advantage of using LARC. Copyright © 2015 North American Society for Pediatric and Adolescent Gynecology. Published by Elsevier Inc. All rights reserved.

  3. Rapid extraction and determination of amphetamines in human urine samples using dispersive liquid-liquid microextraction and solidification of floating organic drop followed by high performance liquid chromatography. (United States)

    Ahmadi-Jouibari, Toraj; Fattahi, Nazir; Shamsipur, Mojtaba


    A novel, rapid, simple and sensitive dispersive liquid-liquid microextraction method based on the solidification of floating organic drop (DLLME-SFO) combined with high-performance liquid chromatography-ultraviolet detection (HPLC-UV) was used to determine amphetamine and methamphetamine in urine samples. The factors affecting the extraction efficiency of DLLME-SFO such as the kind and volume of the extraction and the disperser solvents, effect of concentration of K2CO3 and extraction time were investigated and the optimal extraction conditions were established. Under the optimum conditions (extraction solvent: 30.0μl 1-undecanol; disperser solvent: 300μl acetonitrile; buffer concentration: 2% (w/v) K2CO3 and extraction time: 1min), calibration curves are linear in the range of 10-3000μgl(-1) and limit of detections (LODs) are in the range of 2-8μgl(-1). The relative standard deviations (RSDs) for 100μgl(-1) of amphetamine and methamphetamine in diluted urine are in the range of 6.2-7.8% (n=7). The method was successfully applied for the determination of amphetamine and methamphetamine in the actual urine samples. The relative recoveries of urine samples spiked with amphetamine and methamphetamine are 87.8-113.2%. The obtained results show that DLLME-SFO combined with HPLC-UV is a fast and simple method for the determination of amphetamine and methamphetamine in urine. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Outcomes of acutely HIV-1-infected individuals following rapid antiretroviral therapy initiation. (United States)

    Girometti, Nicolò; Nwokolo, Nneka; McOwan, Alan; Whitlock, Gary


    Few data exist on the benefits and acceptability of rapid initiation of antiretroviral treatment in acute HIV infection (AHI). We analysed a large cohort of acutely infected HIV patients starting antiretroviral therapy (ART) to determine uptake, linkage into care and time to achieve viral suppression. Case notes of all individuals diagnosed with AHI between May 2014 and October 2015 at 56 Dean Street, a sexual health clinic in London, UK were reviewed. AHI was defined through documentation of plasma HIV RNA positivity only, plasma HIV RNA and p24 antigen positivity with a negative HIV enzyme immunoassay (EIA) test or HIV EIA test switching from negative to positive within 6 weeks. Between-group comparisons of time to viral suppression according to ART chosen were performed using the log-rank test. We identified 113 individuals with AHI. Linkage to care was 95%. 77% of patients started ART at first medical appointment: all men who have sex with men, median age 35 years, median viral load (VL) log10 6.45, median CD4+ T-cell count 483 cells/mm3. Median time from diagnosis to ART initiation was 20 days. At 24 weeks, no patients had discontinued ART; 99% of patients achieved viral suppression by 24 weeks, with a median time to documented VL suppression of 74 days. Viral suppression was more rapid with integrase inhibitors compared with other regimens (median 41 versus 88.5 days, PHIV infection, individuals demonstrated high ART uptake and rapid VL suppression suggesting that early treatment with antiretrovirals is acceptable and efficacious.

  5. Initial Accuracy of HIV Rapid Test Kits Stored in Suboptimal Conditions and Validity of Delayed Reading of Oral Fluid Tests. (United States)

    Choko, Augustine T; Taegtmeyer, Miriam; MacPherson, Peter; Cocker, Derek; Khundi, McEwen; Thindwa, Deus; Sambakunsi, Rodrick S; Kumwenda, Moses K; Chiumya, Kondwani; Malema, Owen; Makombe, Simon D; Webb, Emily L; Corbett, Elizabeth L


    To evaluate the effect of storing commonly used rapid diagnostic tests above manufacturer-recommended temperature (at 37°C), and the accuracy of delayed reading of oral fluid kits with relevance to HIV self-testing programmes. A quality assurance study of OraQuick (OraSure), Determine HIV 1/2™ (Alere) and Uni-Gold™ (Recombigen®). Consecutive adults (≥18y) attending Ndirande Health Centre in urban Blantyre, Malawi in January to April 2012 underwent HIV testing with two of each of the three rapid diagnostic test kits stored for 28 days at either 18°C (optimally-stored) or at 37°C (pre-incubated). Used OraQuick test kits were stored in a laboratory for delayed day 1 and subsequent monthly re-reading was undertaken for one year. Of 378 individuals who underwent parallel testing, 5 (1.3%) were dropped from the final analysis due to discordant or missing reference standard results (optimally-stored Determine and Uni-Gold). Compared to the diagnostic reference standard, OraQuick had a sensitivity of 97.2% (95% CI: 93.6-99.6). There were 7 false negative results among all test kits stored at 37°C and three false negatives among optimally stored kits. Excellent agreement between pre-incubated tests and optimally-stored tests with Kappa values of 1.00 for Determine and Uni-Gold; and 0.97 (95% CI: 0.95; 1.00) for OraQuick were observed. There was high visual stability on re-reading of OraQuick, with only 1/375 pre-incubated and 1/371 optimally-stored OraQuick kits changing from the initial result over 12 months. Erroneous results observed during HIV testing in low income settings are likely to be due to factors other than suboptimal storage conditions. Re-reading returned OraQuick kits may offer a convenient and accurate quality assurance approach, including in HIV self-testing programmes.

  6. Condition Help: A Patient- and Family-Initiated Rapid Response System. (United States)

    Eden, Elizabeth L; Rack, Laurie L; Chen, Ling-Wan; Bump, Gregory M


    Rapid response teams (RRTs) help in delivering safe, timely care. Typically they are activated by clinicians using specific parameters. Allowing patients and families to activate RRTs is a novel intervention. The University of Pittsburgh Medical Center developed and implemented a patient- and family-initiated rapid response system called Condition Help (CH). When the CH system is activated, a patient care liaison or an on-duty administrator meets bedside with the unit charge nurse to address the patient's concerns. In this study, we collected demographic data, call reasons, call designations (safety or nonsafety), and outcome information for all CH calls made during the period January 2012 through June 2015. Two hundred forty patients/family members made 367 CH calls during the study period. Most calls were made by patients (76.8%) rather than family members (21.8%). Of the 240 patients, 43 (18%) made multiple calls; their calls accounted for 46.3% of all calls (170/367). Inadequate pain control was the reason for the call in most cases (48.2%), followed by dissatisfaction with staff (12.5%). The majority of calls involved nonsafety issues (83.4%) rather than safety issues (11.4%). In 41.4% of cases, a change in care was made. Patient- and family-initiated RRTs are designed to engage patients and families in providing safer care. In the CH system, safety issues are identified, but the majority of calls involve nonsafety issues. Journal of Hospital Medicine 2017;12:157-161.

  7. Rapid fore-arc extension and detachment-mode spreading following subduction initiation (United States)

    Morris, Antony; Anderson, Mark W.; Omer, Ahmed; Maffione, Marco; van Hinsbergen, Douwe J. J.


    Most ophiolites have geochemical signatures that indicate formation by suprasubduction seafloor spreading above newly initiated subduction zones, and hence they record fore-arc processes operating following subduction initiation. They are frequently underlain by a metamorphic sole formed at the top of the downgoing plate and accreted below the overlying suprasubduction zone lithosphere immediately following ophiolite formation. Paleomagnetic analyses of ophiolites can provide important insights into the enigmatic geodynamic processes operating in this setting via identification of tectonic rotations related to upper plate extension. Here we present net tectonic rotation results from the Late Cretaceous Mersin ophiolite of southern Turkey that document rapid and progressive rotation of ophiolitic rocks and their associated metamorphic sole. Specifically, we demonstrate that lower crustal cumulate rocks and early dykes intruded into the underlying mantle section have undergone extreme rotation around ridge-parallel, shallowly-plunging axes, consistent with oceanic detachment faulting during spreading. Importantly, later dykes cutting the metamorphic sole experienced rotation around the same axis but with a lower magnitude. We show that these rotations occurred via a common mechanism in a pre-obduction, fore-arc setting, and are best explained by combining (hyper)extension resulting from detachment-mode, amagmatic suprasubduction zone spreading in a fore-arc environment with a recently proposed mechanism for exhumation of metamorphic soles driven by upper plate extension. Available age constraints demonstrate that extreme rotation of these units was accommodated rapidly by these processes over a time period of <∼3 Myr, comparable with rates of rotation seen in oceanic core complexes in the modern oceans.

  8. Systemic and rapidly progressive light-chain deposition disease initially presenting as tubulointerstitial nephritis. (United States)

    Takahashi, Satoko; Soma, Jun; Nakaya, Izaya; Yahata, Mayumi; Sakuma, Tsutomu; Yaegashi, Hiroshi; Sato, Akiyoshi; Wano, Masaharu; Sato, Hiroshi


    A 42-year-old woman was admitted to a hospital after first-time detection of proteinuria and hematuria during a routine medical check-up. Because her serum creatinine level had rapidly increased from 0.9 to 3.2 mg/dl since measurement 3 months earlier, she was referred to our hospital. Renal biopsy revealed extensive tubular atrophy and interstitial fibrosis with mild leukocyte infiltration. Glomeruli showed minimal changes, and no immunoglobulin or complement deposition was observed by immunofluorescence. Oral prednisolone was commenced under the diagnosis of chronic tubulointerstitial nephritis, and she discharged once. However, its effects were transient; her renal function deteriorated rapidly and hemodialysis was initiated 5 months after her initial check-up. On readmission, urinary Bence-Jones protein κ-type was detected, and examination of bone marrow led to a diagnosis of Bence-Jones κ-type multiple myeloma. Light-chain staining using a renal biopsy specimen obtained 2 months earlier showed κ-light-chain deposition on tubular basement membranes but not glomeruli. Despite undergoing chemotherapy with vincristine, doxirubicin, and dexamethasone, the patient died suddenly from a cardiac arrhythmia. Autopsy showed κ-light-chain deposition in the heart, thyroid, liver, lungs, spleen, and ovaries. Congo red staining yielded negative results. Typical light-chain deposition disease (LCDD) characterized by nodular glomerulosclerosis was observed in the kidneys. This case demonstrates that tubulointerstitial nephritis can be an early pathological variant of LCDD, which may be followed by accelerated and massive light-chain deposition in glomeruli.

  9. Constraints on rapidity-dependent initial conditions from charged-particle pseudorapidity densities and two-particle correlations (United States)

    Ke, Weiyao; Moreland, J. Scott; Bernhard, Jonah E.; Bass, Steffen A.


    We study the initial three-dimensional spatial configuration of the quark-gluon plasma (QGP) produced in relativistic heavy-ion collisions using centrality and pseudorapidity-dependent measurements of the medium's charged particle density and two-particle correlations. A cumulant-generating function is first used to parametrize the rapidity dependence of local entropy deposition and extend arbitrary boost-invariant initial conditions to nonzero beam rapidities. The model is then compared to p +Pb and Pb + Pb charged-particle pseudorapidity densities and two-particle pseudorapidity correlations and systematically optimized using Bayesian parameter estimation to extract high-probability initial condition parameters. The optimized initial conditions are then compared to a number of experimental observables including the pseudorapidity-dependent anisotropic flows, event-plane decorrelations, and flow correlations. We find that the form of the initial local longitudinal entropy profile is well constrained by these experimental measurements.

  10. Drop coalescence through a liquid/liquid interface (United States)

    Mohamed-Kassim, Zulfaa; Longmire, Ellen K.


    Particle image velocimetry (PIV) experiments were conducted to study the coalescence of single drops through planar liquid/liquid interfaces. Sequences of velocity vector fields were obtained with a high-speed video camera and subsequent PIV analysis. Two ambient liquids with different viscosity but similar density were examined resulting in Reynolds numbers based on a surface tension velocity of 10 and 26. Prior to rupture, the drops rested on a thin film of ambient liquid above an underlying interface. After rupture, which was typically off-axis, the free edge of the thin film receded rapidly allowing the drop fluid to sink into the bulk liquid below. Vorticity generated in the collapsing fluid developed into a vortex ring straddling the upper drop surface. The ring core traveled radially inward with a ring-shaped capillary wave effectively pinching the upper drop surface and increasing the drop collapse speed. The inertia of the collapse deflected the interface downward before it rebounded upward. During this time, the vortex core split so that part of its initial vorticity moved inside the drop fluid while part remained in the ambient fluid above it. A second ring-shaped capillary wave formed along the interface outside of the drop and propagated radially outward during the collapse. Changing the ambient fluid viscosity resulted in several effects. First, the velocity of the receding free edge was smaller for higher ambient viscosity. Second, the pinching of the upper drop surface caused by the shrinking capillary ring wave was stronger when the ambient viscosity was lower, and this resulted in a higher maximum collapse speed and higher vorticity values in the dominant vortex ring.

  11. Drop spreading with random viscosity

    CERN Document Server

    Xu, Feng


    We examine theoretically the spreading of a viscous liquid drop over a thin film of uniform thickness, assuming the liquid's viscosity is regulated by the concentration of a solute that is carried passively by the spreading flow. The solute is assumed to be initially heterogeneous, having a spatial distribution with prescribed statistical features. To examine how this variability influences the drop's motion, we investigate spreading in a planar geometry using lubrication theory, combining numerical simulations with asymptotic analysis. We assume diffusion is sufficient to suppress solute concentration gradients across but not along the film. The solute field beneath the bulk of the drop is stretched by the spreading flow, such that the initial solute concentration immediately behind the drop's effective contact lines has a long-lived influence on the spreading rate. Over long periods, solute swept up from the precursor film accumulates in a short region behind the contact line, allowing patches of elevated v...

  12. Rapid fore-arc extension and detachment-mode spreading following subduction initiation

    NARCIS (Netherlands)

    Morris, Antony; Anderson, Mark W.; Omer, Ahmed; Maffione, Marco; van Hinsbergen, Douwe J.J.|info:eu-repo/dai/nl/269263624


    Most ophiolites have geochemical signatures that indicate formation by suprasubduction seafloor spreading above newly initiated subduction zones, and hence they record fore-arc processes operating following subduction initiation. They are frequently underlain by a metamorphic sole formed at the top

  13. Dilating Eye Drops (United States)

    ... Frequently Asked Questions Español Condiciones Chinese Conditions Dilating Eye Drops En Español Read in Chinese What are dilating eye drops? Dilating eye drops contain medication to enlarge ( ...

  14. Initiation of a Multidisciplinary, Rapid Response Team to Massive and Submassive Pulmonary Embolism. (United States)

    Carroll, Brett J; Pemberton, Heather; Bauer, Kenneth A; Chu, Louis M; Weinstein, Jeffrey L; Levarge, Barbara L; Pinto, Duane S


    Pulmonary embolism (PE) can result in rapid clinical decompensation in many patients. With increasing patient complexity and advanced treatment options for PE, multidisciplinary, rapid response teams can optimize risk stratification and expedite management strategies. The Massive And Submassive Clot On-call Team (MASCOT) was created at our institution, which comprised specialists from cardiology, pulmonology, hematology, interventional radiology, and cardiac surgery. MASCOT offers rapid consultation 24 hours a day with a web-based conference call to review patient data and discuss management of patients with high-risk PE. We reviewed patient data collected from MASCOT's registry to analyze patient clinical characteristics and outcomes and describe the composition and operation of the team. Between August 2015 and September 2016, MASCOT evaluated 72 patients. Seventy of the 72 patients were admitted to our institution, accounting for 32% of all patients discharged with a primary diagnosis of PE. Average age was 62 ± 17 years with a female predominance (63%). Active malignancy (31%), recent surgery or trauma (21%), and recent hospitalization (24%) were common. PE clinical severity was massive in 16% and submassive in 83%. Patients were managed with anticoagulation alone in 65% (n = 46), systemic fibrinolysis in 11% (n = 8), catheter-directed therapy in 18% (n = 13), extracorporeal membrane oxygenation in 3% (n = 2), and an inferior vena cava filter was placed in 15% (n = 11). Thirteen percent (n = 9) experienced a major bleed with no intracranial hemorrhage. Survival to discharge was 89% (64% with massive PE and 93% with submassive PE). In conclusion, multidisciplinary, rapid response PE teams offer a unique coordinated approach to patient care. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Rapid Antiretroviral Therapy Initiation for Women in an HIV-1 Prevention Clinical Trial Experiencing Primary HIV-1 Infection during Pregnancy or Breastfeeding. (United States)

    Morrison, Susan; John-Stewart, Grace; Egessa, John J; Mubezi, Sezi; Kusemererwa, Sylvia; Bii, Dennis K; Bulya, Nulu; Mugume, Francis; Campbell, James D; Wangisi, Jonathan; Bukusi, Elizabeth A; Celum, Connie; Baeten, Jared M


    During an HIV-1 prevention clinical trial in East Africa, we observed 16 cases of primary HIV-1 infection in women coincident with pregnancy or breastfeeding. Nine of eleven pregnant women initiated rapid combination antiretroviral therapy (ART), despite having CD4 counts exceeding national criteria for ART initiation; breastfeeding women initiated ART or replacement feeding. Rapid ART initiation during primary HIV-1 infection during pregnancy and breastfeeding is feasible in this setting.

  16. Rapid Antiretroviral Therapy Initiation for Women in an HIV-1 Prevention Clinical Trial Experiencing Primary HIV-1 Infection during Pregnancy or Breastfeeding.

    Directory of Open Access Journals (Sweden)

    Susan Morrison

    Full Text Available During an HIV-1 prevention clinical trial in East Africa, we observed 16 cases of primary HIV-1 infection in women coincident with pregnancy or breastfeeding. Nine of eleven pregnant women initiated rapid combination antiretroviral therapy (ART, despite having CD4 counts exceeding national criteria for ART initiation; breastfeeding women initiated ART or replacement feeding. Rapid ART initiation during primary HIV-1 infection during pregnancy and breastfeeding is feasible in this setting.

  17. Rapidly Progressive Encephalopathy: Initial Diagnosis of Creutzfeldt Jakob Disease in an Intensive Care Unit

    Directory of Open Access Journals (Sweden)

    Patrícia Afonso Mendes


    Full Text Available Creutzfeldt-Jakob disease (CJD is a rare, incurable and fatal condition that can only be confirmed through neuropathological investigation, such as brain biopsy or post-mortem study. However, a probable diagnosis can be made using clinical criteria. CJD manifests as rapidly progressive dementia with myoclonus and to a lesser extent visual impairment and cerebellar and pyramidal/extrapyramidal signs. We report the case of a previously independent adult male that met all the clinical criteria. Taken together, the investigation results suggested probable CJD.

  18. Sewage sludge as an initial fertility driver for rapid improvement of mudflat salt-soils. (United States)

    Bai, Yanchao; Zang, Caiyun; Gu, Minjing; Gu, Chuanhui; Shao, Hongbo; Guan, Yongxiang; Wang, Xukui; Zhou, Xiaojian; Shan, Yuhua; Feng, Ke


    Sewage sludge is by-product in the process of centralized wastewater treatment. Land application of sewage sludge is one of the important disposal alternatives. Mudflats in the interaction zone between land and sea can be important alternative sources for arable lands if amended by large amount of organic fertilizers. Rich in organic matter and other nutrients, sewage sludge has been considered as the economic choice for an initial fertility driver. However, sewage sludge amendment has been greatly hampered due to availability of potential toxic metals. Using sewage sludge in compliance with the national standards for agricultural usage could avoid the accumulation of heavy metals. Nevertheless, it is not clear whether massive input of sewage sludge would increase heavy metals concentration in crops. The objective of this study was to investigate impact of sewage sludge amendment (SSA) as an initial fertility driver by one-time input, with the rates of 0, 30, 75, 150, and 300tha -1 , on biomass of green manures, soil chemical properties, and growth and heavy metals uptake of maize (Zea mays L.) grown in mudflat soil. Results showed that one-time sewage sludge amendment promoted an initial fertility for infertile mudflat soil, supported growth of ryegrass as the first season green manure. By tilled ryegrass, it modified the chemical properties of mudflat soil by increasing soil organic carbon, total and available N and P, and decreasing soil salinity and pH, which promoted subsequent growth of two green manures for sesbania and ryegrass. The sewage sludge as an initial fertility driver combined with planting and tilling green manures, increased dry matter of the aerial part and grain yield of maize grown in mudflat soil. Cd and Ni concentrations in grain of maize were positively correlated with sewage sludge amendment rates. Importantly, heavy metal concentrations in grain of maize at all SSA rates did not exceed the safety standard for food in China (GB 2762


    Energy Technology Data Exchange (ETDEWEB)

    Raskin, Cody; Owen, J. Michael [Lawrence Livermore National Laboratory, P.O. Box 808, L-038, Livermore, CA 94550 (United States)


    Creating spherical initial conditions in smoothed particle hydrodynamics simulations that are spherically conformal is a difficult task. Here, we describe two algorithmic methods for evenly distributing points on surfaces that when paired can be used to build three-dimensional spherical objects with optimal equipartition of volume between particles, commensurate with an arbitrary radial density function. We demonstrate the efficacy of our method against stretched lattice arrangements on the metrics of hydrodynamic stability, spherical conformity, and the harmonic power distribution of gravitational settling oscillations. We further demonstrate how our method is highly optimized for simulating multi-material spheres, such as planets with core–mantle boundaries.

  20. NIAAA's Rapid Response to College Drinking Problems Initiative: Reinforcing the Use of Evidence-Based Approaches in College Alcohol Prevention* (United States)

    DeJong, William; Larimer, Mary E.; Wood, Mark D.; Hartman, Roger


    Objective: The National Institute on Alcohol Abuse and Alcoholism (NIAAA) created the Rapid Response to College Drinking Problems initiative so that senior college administrators facing an alcohol-related crisis could get assistance from well-established alcohol researchers and NIAAA staff. Method: Based on a competitive grant process, NIAAA selected five teams of research scientists with expertise in college drinking research. NIAAA then invited college administrators to propose interventions to address a recently experienced alcohol-related problem. Between September 2004 and September 2005, NIAAA selected 15 sites and paired each recipient college with a scientific team. Together, each program development/evaluation team, working closely with NIAAA scientific staff, jointly designed, implemented, and evaluated a Rapid Response project. Results: This supplement reports the results of several Rapid Response projects, plus other findings of interest that emerged from that research. Eight articles present evaluation findings for prevention and treatment interventions, which can be grouped by the individual, group/interpersonal, institutional, and community levels of the social ecological framework. Additional studies provide further insights that can inform prevention and treatment programs designed to reduce alcohol-related problems among college students. This article provides an overview of these findings, placing them in the context of the college drinking intervention literature. Conclusions: College drinking remains a daunting problem on many campuses, but evidence-based strategies—such as those described in this supplement—provide hope that more effective solutions can be found. The Rapid Response initiative has helped solidify the necessary link between research and practice in college alcohol prevention and treatment. PMID:19538907

  1. Overcoming challenges to initiating cell therapy clinical trials in rapidly developing countries: India as a model. (United States)

    Viswanathan, Sowmya; Rao, Mahendra; Keating, Armand; Srivastava, Alok


    Increasingly, a number of rapidly developing countries, including India, China, Brazil, and others, are becoming global hot spots for the development of regenerative medicine applications, including stem cell-based therapies. Identifying and overcoming regulatory and translational research challenges and promoting scientific and ethical clinical trials with cells will help curb the growth of stem cell tourism for unproven therapies. It will also enable academic investigators, local regulators, and national and international biotechnology and biopharmaceutical companies to accelerate stem cell-based clinical research that could lead to effective innovative treatments in these regions. Using India as a model system and obtaining input from regulators, clinicians, academics, and industry representatives across the stem cell field in India, we reviewed the role of key agencies and processes involved in this field. We have identified areas that need attention and here provide solutions from other established and functioning models in the world to streamline and unify the regulatory and ethics approval processes for cell-based therapies. We also make recommendations to check the growth and functioning of clinics offering unproven treatments. Addressing these issues will remove considerable hurdles to both local and international investigators, accelerate the pace of research and development, and create a quality environment for reliable products to emerge. By doing so, these countries would have taken one important step to move to the forefront of stem cell-based therapeutics.

  2. A simulation study of the electromyographic volley at initiation of rapid isometric contractions in the first dorsal interosseous muscle. (United States)

    Yamazaki, Y; Suzuki, M; Ohkuwa, T; Itoh, H


    Monopolar surface electromyograms (EMGs) of rapid isometric abduction of the first dorsal interosseous muscle (FDI) were initiated from an EMG volley that was characterized by a negative potential lasting over several tens of milliseconds. An EMG model was developed to study how the EMG volley was generated. EMGs were defined as the linear summations of surface-recorded action potential trains originating from single motor units (MUs). All action potential trains had the same discharge pattern but different recruitment thresholds, depending on the potential amplitude. Real action potentials in single MUs in FDI were recorded with a monopolar surface electrode, one of which was used as a prototype wave in simulation. The model predicted an initial negative potential comparable to that of the EMG volley observed in rapid contractions of FDI. Results from our simulation studies suggest that the EMG volley is caused by at least two independent factors: (1) the negative phase of the action potential is greater in area than the positive one, in which the effect is enhanced by the high discharge rate of many MUs; (2) many MUs are recruited within a short time in an orderly fashion starting from those with small action potentials to those with large ones.

  3. Eye Drop Tips (United States)

    ... Involved News About Us Donate In This Section Eye Drop Tips en Español email Send this article ... the reach of children. Steps For Putting In Eye Drops: Start by tilting your head backward while ...

  4. Probing the nanoscale: the first contact of an impacting drop

    KAUST Repository

    Li, Erqiang


    When a drop impacts onto a solid surface, the lubrication pressure in the air deforms its bottom into a dimple. This makes the initial contact with the substrate occur not at a point but along a ring, thereby entrapping a central disc of air. We use ultra-high-speed imaging, with 200 ns time resolution, to observe the structure of this first contact between the liquid and a smooth solid surface. For a water drop impacting onto regular glass we observe a ring of microbubbles, due to multiple initial contacts just before the formation of the fully wetted outer section. These contacts are spaced by a few microns and quickly grow in size until they meet, thereby leaving behind a ring of microbubbles marking the original air-disc diameter. On the other hand, no microbubbles are left behind when the drop impacts onto molecularly smooth mica sheets. We thereby conclude that the localized contacts are due to nanometric roughness of the glass surface, and the presence of the microbubbles can therefore distinguish between glass with 10 nm roughness and perfectly smooth glass. We contrast this entrapment topology with the initial contact of a drop impacting onto a film of extremely viscous immiscible liquid, where the initial contact appears to be continuous along the ring. Here, an azimuthal instability occurs during the rapid contraction at the triple line, also leaving behind microbubbles. For low impact velocities the nature of the initial contact changes to one initiated by ruptures of a thin lubricating air film.

  5. Studies of Drop/Drop and Drop/Interface Impact (United States)

    Lowengrub, John; Cristini, Vittorio; Kim, Jun-Seok; Zheng, Xiaoming; Mohammed-Kassim, Zulfaa; Longmire, Ellen


    In this talk, we will study the impact and coalescence of liquid drops using a physically-based numerical model that allows seamless transitions in interface topologies combined with adaptive mesh refinement. By using a mesh size that is adaptive to the length scales associated to the lubrication pressure generated by interfaces in near contact, we accurately describe the near contact motion and recover the predictions of asymptotic analyses. We compare simulation results to recent experiments performed by Mohamed-Kassim and Longmire. The effects of multiple drops, van der Waal forces and surfactants will also be considered.

  6. Rapid analysis of the essential oil components of dried Zanthoxylum bungeanum Maxim by Fe2O3-magnetic-microsphere-assisted microwave distillation and simultaneous headspace single-drop microextraction followed by GC-MS. (United States)

    Ye, Qing


    In this work, microwave distillation assisted by Fe2 O3 magnetic microspheres (FMMS) and headspace single-drop microextraction were combined, and developed for determination of essential oil compounds in dried Zanthoxylum bungeanum Maxim (ZBM). The FMMS were used as microwave absorption solid medium for dry distillation of dried ZBM. Using the proposed method, isolation, extraction, and concentration of essential oil compounds can be carried out in a single step. The experimental parameters including extraction solvent, solvent volume, microwave power, irradiation time, and the amount of added FMMS, were studied. The optimal analytical conditions were: 2.0 μL decane as the extraction solvent, microwave power of 300 W, irradiation time of 2 min, and the addition of 0.1 g FMMS to ZBM. The method precision was from 4 to 10%. A total of 52 compounds were identified by the proposed method. The conventional steam distillation method was also used for the analysis of essential oil in dried ZBM and only 31 compounds were identified by steam distillation method. It was found that the proposed method is a simple, rapid, reliable, and solvent-free technique for the determination of volatile compounds in Chinese herbs. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Drop Spreading with Random Viscosity (United States)

    Xu, Feng; Jensen, Oliver


    Airway mucus acts as a barrier to protect the lung. However as a biological material, its physical properties are known imperfectly and can be spatially heterogeneous. In this study we assess the impact of these uncertainties on the rate of spreading of a drop (representing an inhaled aerosol) over a mucus film. We model the film as Newtonian, having a viscosity that depends linearly on the concentration of a passive solute (a crude proxy for mucin proteins). Given an initial random solute (and hence viscosity) distribution, described as a Gaussian random field with a given correlation structure, we seek to quantify the uncertainties in outcomes as the drop spreads. Using lubrication theory, we describe the spreading of the drop in terms of a system of coupled nonlinear PDEs governing the evolution of film height and the vertically-averaged solute concentration. We perform Monte Carlo simulations to predict the variability in the drop centre location and width (1D) or area (2D). We show how simulation results are well described (at much lower computational cost) by a low-order model using a weak disorder expansion. Our results show for example how variability in the drop location is a non-monotonic function of the solute correlation length increases. Engineering and Physical Sciences Research Council.


    Energy Technology Data Exchange (ETDEWEB)

    Smith, M.; Sullivan, M.; D’Andrea, C. B.; Castander, F. J.; Casas, R.; Prajs, S.; Papadopoulos, A.; Nichol, R. C.; Karpenka, N. V.; Bernard, S. R.; Brown, P.; Cartier, R.; Cooke, J.; Curtin, C.; Davis, T. M.; Finley, D. A.; Foley, R. J.; Gal-Yam, A.; Goldstein, D. A.; González-Gaitán, S.; Gupta, R. R.; Howell, D. A.; Inserra, C.; Kessler, R.; Lidman, C.; Marriner, J.; Nugent, P.; Pritchard, T. A.; Sako, M.; Smartt, S.; Smith, R. C.; Spinka, H.; Thomas, R. C.; Wolf, R. C.; Zenteno, A.; Abbott, T. M. C.; Benoit-Lévy, A.; Bertin, E.; Brooks, D.; Buckley-Geer, E.; Rosell, A. Carnero; Kind, M. Carrasco; Carretero, J.; Crocce, M.; Cunha, C. E.; Costa, L. N. da; Desai, S.; Diehl, H. T.; Doel, P.; Estrada, J.; Evrard, A. E.; Flaugher, B.; Fosalba, P.; Frieman, J.; Gerdes, D. W.; Gruen, D.; Gruendl, R. A.; James, D. J.; Kuehn, K.; Kuropatkin, N.; Lahav, O.; Li, T. S.; Marshall, J. L.; Martini, P.; Miller, C. J.; Miquel, R.; Nord, B.; Ogando, R.; Plazas, A. A.; Reil, K.; Romer, A. K.; Roodman, A.; Rykoff, E. S.; Sanchez, E.; Scarpine, V.; Schubnell, M.; Sevilla-Noarbe, I.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Walker, A. R.; Wester, W.


    We present DES14X3taz, a new hydrogen-poor superluminous supernova (SLSN-I) discovered by the Dark Energy Survey (DES) supernova program, with additional photometric data provided by the Survey Using DECam for Superluminous Supernovae. Spectra obtained using Optical System for Imaging and low-Intermediate-Resolution Integrated Spectroscopy on the Gran Telescopio CANARIAS show DES14X3taz is an SLSN-I at z = 0.608. Multi-color photometry reveals a double-peaked light curve: a blue and relatively bright initial peak that fades rapidly prior to the slower rise of the main light curve. Our multi-color photometry allows us, for the first time, to show that the initial peak cools from 22,000 to 8000 K over 15 rest-frame days, and is faster and brighter than any published core-collapse supernova, reaching 30% of the bolometric luminosity of the main peak. No physical Ni-56-powered model can fit this initial peak. We show that a shock-cooling model followed by a magnetar driving the second phase of the light curve can adequately explain the entire light curve of DES14X3taz. Models involving the shock-cooling of extended circumstellar material at a distance of similar or equal to 400 R-circle dot are preferred over the cooling of shock-heated surface layers of a stellar envelope. We compare DES14X3taz to the few double-peaked SLSN-I events in the literature. Although the rise. times and characteristics of these initial peaks differ, there exists the tantalizing possibility that they can be explained by one physical interpretation

  9. Rapid turnover of DnaA at replication origin regions contributes to initiation control of DNA replication. (United States)

    Schenk, Katrin; Hervás, Ana B; Rösch, Thomas C; Eisemann, Marc; Schmitt, Bernhard A; Dahlke, Stephan; Kleine-Borgmann, Luise; Murray, Seán M; Graumann, Peter L


    DnaA is a conserved key regulator of replication initiation in bacteria, and is homologous to ORC proteins in archaea and in eukaryotic cells. The ATPase binds to several high affinity binding sites at the origin region and upon an unknown molecular trigger, spreads to several adjacent sites, inducing the formation of a helical super structure leading to initiation of replication. Using FRAP analysis of a functional YFP-DnaA allele in Bacillus subtilis, we show that DnaA is bound to oriC with a half-time of 2.5 seconds. DnaA shows similarly high turnover at the replication machinery, where DnaA is bound to DNA polymerase via YabA. The absence of YabA increases the half time binding of DnaA at oriC, showing that YabA plays a dual role in the regulation of DnaA, as a tether at the replication forks, and as a chaser at origin regions. Likewise, a deletion of soj (encoding a ParA protein) leads to an increase in residence time and to overinitiation, while a mutation in DnaA that leads to lowered initiation frequency, due to a reduced ATPase activity, shows a decreased residence time on binding sites. Finally, our single molecule tracking experiments show that DnaA rapidly moves between chromosomal binding sites, and does not arrest for more than few hundreds of milliseconds. In Escherichia coli, DnaA also shows low residence times in the range of 200 ms and oscillates between spatially opposite chromosome regions in a time frame of one to two seconds, independently of ongoing transcription. Thus, DnaA shows extremely rapid binding turnover on the chromosome including oriC regions in two bacterial species, which is influenced by Soj and YabA proteins in B. subtilis, and is crucial for balanced initiation control, likely preventing fatal premature multimerization and strand opening of DnaA at oriC.

  10. Characteristics of Unequal Size Drop Collisions (United States)

    Kim, Jungyong; Longmire, Ellen; Kim, Man Sik


    Pairs of water/glycerin drops were injected into silicone oil and traveled on downward trajectories before colliding. Unequal size drop collisions with drop size ratios (Ds/DL) of 0.7 and 0.5 were investigated. Simultaneous dual-field PIV measurements were obtained to characterize coalescence and rebounding behavior. The initial injection angle and tube height were adjusted to access appropriate impact parameters. In the current study, the collision angle of the large drop was, in general, shallower than that of the small drop, and a range of velocity ratios and impact parameters was examined. Coalescence occurs above We* = 11 similar to collision outcomes for equal size drops. As drop size ratio decreases, the intervening film deforms more. If the velocity ratio uL/us 1, the interface flattens before coalescence. The rupture location varies due to the asymmetry of the drops. As collision offset increases (B > 0), the film rupture time is shortened and mixing of the fluid within the drops is enhanced after coalescence. These results will be compared with the behavior observed previously for equal size drop collisions.

  11. Rapid screening test for gestational diabetes: public health need, market requirement, initial product design, and experimental results (United States)

    Weigl, Bernhard H.; Zwisler, Greg; Peck, Roger; Abu-Haydar, Elizabeth


    Gestational diabetes is a global epidemic where many urban areas in Southeast Asia have found prevalence rates as high as 20%, exceeding the highest prevalence rates in the developed world. It can have serious and life-threatening consequences for mothers and babies. We are developing two variants of a new, simple, low-cost rapid test for screening for gestational diabetes mellitus for use primarily in low-resource settings. The pair of assays, both semiquantitative rapid diagnostic strip tests for glycated albumin, require neither fasting nor an oral glucose challenge test. One variant is an extremely simple strip test to estimate the level of total glycated albumin in blood. The other, which is slightly more complex and expensive, is a test that determines the ratio of glycated albumin to total albumin. The screening results can be used to refer women to receive additional care during delivery to avoid birth complications as well as counseling on diet and exercise during and after pregnancy. Results with the latter test may also be used to start treatment with glucose-lowering drugs. Both assays will be read visually. We present initial results of a preliminary cost-performance comparison model evaluating the proposed test versus existing alternatives. We also evaluated user needs and schematic paper microfluidics-based designs aimed at overcoming the challenge of visualizing relatively narrow differences between normal and elevated levels of glycated albumin in blood.

  12. Scanning drop sensor (United States)

    Jin, Jian; Xiang, Chengxiang; Gregoire, John M.; Shinde, Aniketa A.; Guevarra, Dan W.; Jones, Ryan J.; Marcin, Martin R.; Mitrovic, Slobodan


    Electrochemical or electrochemical and photochemical experiments are performed on a collection of samples by suspending a drop of electrolyte solution between an electrochemical experiment probe and one of the samples that serves as a test sample. During the electrochemical experiment, the electrolyte solution is added to the drop and an output solution is removed from the drop. The probe and collection of samples can be moved relative to one another so the probe can be scanned across the samples.

  13. Bubble and drop interfaces

    CERN Document Server



    The book aims at describing the most important experimental methods for characterizing liquid interfaces, such as drop profile analysis, bubble pressure and drop volume tensiometry, capillary pressure technique, and oscillating drops and bubbles. Besides the details of experimental set ups, also the underlying theoretical basis is presented in detail. In addition, a number of applications based on drops and bubbles is discussed, such as rising bubbles and the very complex process of flotation. Also wetting, characterized by the dynamics of advancing contact angles is discussed critically. Spec

  14. Investigation of drop coalescence using tomographic PIV (United States)

    Ortiz-Duenas, Cecilia; Kim, Jungyong; Longmire, Ellen


    High-speed tomographic PIV was used to obtain evolving volumetric velocity fields of the coalescence of single drops and two side-by-side drops through liquid/liquid interfaces. Reynolds numbers (Re=ρsUσD/μs) based on surface tension velocity (Uσ=D/tσ) and surrounding ambient fluid were 8-10, and the viscosity ratio between the fluid drop and surrounding fluid was 0.14. The coalescence process investigated is driven by gravity and thus the initial drops are non-spherical and the interface is deformed by the drops. Previously, Mohamed-Kassim & Longmire (2004) showed that under these conditions, the film rupture typically occurs off-axis, and therefore the flow is three-dimensional. For a single drop, volumetric velocity vector fields are used to characterize the asymmetric film rupture occurring for 0drop into a vortex ring are relatively axisymmetric. For two side-by-side drops, the first drop to coalesce ruptures off-axis on the side closest to the second drop. The volumetric velocity and vorticity fields indicate an asymmetric collapse of the drop for 0.1drop while the capillary waves are axisymmetric.

  15. Dynamics of deforming drops

    NARCIS (Netherlands)

    Bouwhuis, W.


    Liquid drops play a dominant role in numerous industrial applications, such as spray coating, spray painting, inkjet printing, lithography processes, and spraying/sprinkling in agriculture or gardening. In all of these examples, the generation, flight, impact, and spreading of drops are separate

  16. Lambda-dropping

    DEFF Research Database (Denmark)

    Danvy, Olivier; Schultz, Ulrik Pagh


    Lambda-lifting a functional program transforms it into a set of recursive equations. We present the symmetric transformation: lambda-dropping. Lambda-dropping a set of recursive equations restores block structure and lexical scope.For lack of scope, recursive equations must carry around all...... to float (for lambda-lifting) or to sink (for lambda-dropping) along the vertices of the scope tree.We believe lambda-lifting and lambda-dropping are interesting per se, both in principle and in practice, but our prime application is partial evaluation: except for Malmkjær and Ø...... with dozens of parameters, which most compilers do not handle efficiently. Lambda-dropping in a post-processing phase restores their block structure and lexical scope thereby significantly reducing both the compile time and the run time of residual programs....

  17. Dancing drops over vibrating substrates (United States)

    Borcia, Rodica; Borcia, Ion Dan; Helbig, Markus; Meier, Martin; Egbers, Christoph; Bestehorn, Michael


    We study the motion of a liquid drop on a solid plate simultaneously submitted to horizontal and vertical harmonic vibrations. The investigation is done via a phase field model earlier developed for describing static and dynamic contact angles. The density field is nearly constant in every bulk region (ρ = 1 in the liquid phase, ρ ≈ 0 in the vapor phase) and varies continuously from one phase to the other with a rapid but smooth variation across the interfaces. Complicated explicit boundary conditions along the interface are avoided and captured implicitly by gradient terms of ρ in the hydrodynamic basic equations. The contact angle θ is controlled through the density at the solid substrate ρ S , a free parameter varying between 0 and 1 [R. Borcia, I.D. Borcia, M. Bestehorn, Phys. Rev. E 78, 066307 (2008)]. We emphasize the swaying and the spreading modes, earlier theoretically identified by Benilov and Billingham via a shallow-water model for drops climbing uphill along an inclined plane oscillating vertically [E.S. Benilov, J. Billingham, J. Fluid Mech. 674, 93 (2011)]. The numerical phase field simulations will be completed by experiments. Some ways to prevent the release of the dancing drops along a hydrophobic surface into the gas atmosphere are also discussed in this paper.

  18. Long-term installations of the DC-potential drop method in four nuclear power plants and the accuracies thereby obtained for monitoring of crack initiation and crack growth

    Energy Technology Data Exchange (ETDEWEB)

    Oppermann, W.; Hofstoetter, P.; Keller, H.P. [TUEV Rheinland Anlagentechnik GmbH, Koeln (Germany)


    After a total monitored operational timescale of almost five years on long-term installations, both in the laboratory and in four nuclear power plants, evidence can be put forward that the DC-potential drop method is now, at its current stage of development, suitable for inspecting and monitoring material regions such as, e.g. weld seams in pipework, for crack initiation and crack growth at power plant temperatures. This function can be performed with reliability and high sensitivity. The inspection and monitoring of cracks on the internal surface of the pipework can also be carried out from the external surface. The studies have shown that the method is basically able to monitor the growth of cracks found at discontinuous intervals using permanently installed potential probes, i.e. from plant inspection to plant inspection, while a transition to continuous monitoring is possible at any time. Thus a measure of redundancy can be provided for conventional ultrasonic and radiographic inspection, in particular for difficult to check austenitic weld seams. The method can also be seen as an alternative to the conventional techniques. When necessary, the cracks found can be measured more accurately than was previously possible with conventional ultrasonic and radiographic inspections. The total exposure to radiation can be reduced in comparison to other methods of inspection. (orig.) 5 refs.

  19. Micro-splashing by drop impacts

    KAUST Repository

    Thoroddsen, Sigurdur T.


    We use ultra-high-speed video imaging to observe directly the earliest onset of prompt splashing when a drop impacts onto a smooth solid surface. We capture the start of the ejecta sheet travelling along the solid substrate and show how it breaks up immediately upon emergence from the underneath the drop. The resulting micro-droplets are much smaller and faster than previously reported and may have gone unobserved owing to their very small size and rapid ejection velocities, which approach 100 m s-1, for typical impact conditions of large rain drops. We propose a phenomenological mechanism which predicts the velocity and size distribution of the resulting microdroplets. We also observe azimuthal undulations which may help promote the earliest breakup of the ejecta. This instability occurs in the cusp in the free surface where the drop surface meets the radially ejected liquid sheet. © 2012 Cambridge University Press.

  20. Skating on a Film of Air: Drops Impacting on a Surface

    CERN Document Server

    Kolinski, John M; Mandre, Shreyas; Brenner, Michael P; Weitz, David A; Mahadevan, L


    Drops impacting on a surface are ubiquitous in our everyday experience. This impact is understood within a commonly accepted hydrodynamic picture: it is initiated by a rapid shock and a subsequent ejection of a sheet leading to beautiful splashing patterns. However, this picture ignores the essential role of the air that is trapped between the impacting drop and the surface. Here we describe a new imaging modality that is sensitive to the behavior right at the surface. We show that a very thin film of air, only a few tens of nanometers thick, remains trapped between the falling drop and the surface as the drop spreads. The thin film of air serves to lubricate the drop enabling the fluid to skate on the air film laterally outward at surprisingly high velocities, consistent with theoretical predictions. Eventually this thin film of air must break down as the fluid wets the surface. We suggest that this occurs in a spinodal-like fashion, and causes a very rapid spreading of a wetting front outwards; simultaneous...

  1. Drag and drop display & builder

    Energy Technology Data Exchange (ETDEWEB)

    Bolshakov, Timofei B.; Petrov, Andrey D.; /Fermilab


    The Drag and Drop (DnD) Display & Builder is a component-oriented system that allows users to create visual representations of data received from data acquisition systems. It is an upgrade of a Synoptic Display mechanism used at Fermilab since 2002. Components can be graphically arranged and logically interconnected in the web-startable Project Builder. Projects can be either lightweight AJAX- and SVG-based web pages, or they can be started as Java applications. The new version was initiated as a response to discussions between the LHC Controls Group and Fermilab.

  2. Drop impact splashing and air entrapment

    KAUST Repository

    Thoraval, Marie-Jean


    Drop impact is a canonical problem in fluid mechanics, with numerous applications in industrial as well as natural phenomena. The extremely simple initial configuration of the experiment can produce a very large variety of fast and complex dynamics. Scientific progress was made in parallel with major improvements in imaging and computational technologies. Most recently, high-speed imaging video cameras have opened the exploration of new phenomena occurring at the micro-second scale, and parallel computing allowed realistic direct numerical simulations of drop impacts. We combine these tools to bring a new understanding of two fundamental aspects of drop impacts: splashing and air entrapment. The early dynamics of a drop impacting on a liquid pool at high velocity produces an ejecta sheet, emerging horizontally in the neck between the drop and the pool. We show how the interaction of this thin liquid sheet with the air, the drop or the pool, can produce micro-droplets and bubble rings. Then we detail how the breakup of the air film stretched between the drop and the pool for lower impact velocities can produce a myriad of micro-bubbles.

  3. Impact of granular drops

    KAUST Repository

    Marston, J. O.


    We investigate the spreading and splashing of granular drops during impact with a solid target. The granular drops are formed from roughly spherical balls of sand mixed with water, which is used as a binder to hold the ball together during free-fall. We measure the instantaneous spread diameter for different impact speeds and find that the normalized spread diameter d/D grows as (tV/D)1/2. The speeds of the grains ejected during the “splash” are measured and they rarely exceed twice that of the impact speed.

  4. Microvolume turbidimetry for rapid and sensitive determination of the acid labile sulfide fraction in waters after headspace single-drop microextraction with in situ generation of volatile hydrogen sulfide. (United States)

    Lavilla, I; Pena-Pereira, F; Gil, S; Costas, M; Bendicho, C


    In this work, we demonstrate the feasibility of applying headspace single-drop microextraction with in-drop precipitation for the quantitative determination of the acid labile sulfide fraction (H2S, HS-, and S2- (free sulfide), amorphous FeS and some metal sulfide complexes-clusters as ZnS) in aqueous samples by microvolume turbidimetry. The methodology lies in the in situ hydrogen sulfide generation and subsequent sequestration into an alkaline microdrop containing ZnO(2)(2-) and exposed to the headspace above the stirred aqueous sample. The ZnS formed in the drop was then determined by microvolume turbidimetry. The optimum experimental conditions of the proposed method were: 2 microL of a microdrop containing 750 mg L(-1) Zn(II) in 1 mol L(-1) NaOH exposed to the headspace of a 20-mL aqueous sample stirred at 1600 rpm during 80 s after derivatization with 1 mL of 6 mol L(-1) HCl. An enrichment factor of 1710 was achieved in only 80 s. The calibration graph was linear in the range of 5-100 microg L(-1) with a detection limit of 0.5 microg L(-1). The repeatability, expressed as relative standard deviation, was 5.8% (N = 9). Finally, the proposed methodology was successfully applied to the determination of the acid labile sulfide fraction in different natural water samples.

  5. Effect of neighboring particles on drop coalescence at an interface (United States)

    Bordoloi, Ankur; Adhikari, Deepak; Longmire, Ellen


    The coalescence of a liquid drop in the presence of an adjacent solid particle or liquid drop is studied using high-speed visualization and Tomographic PIV. A drop of water/glycerin (W/G), surrounded by silicone oil of matched refractive index, is released onto an underlying W/G interface. A nylon sphere, neutrally buoyant with respect to the drop liquid, is placed adjacent to the drop. Three initial conditions are considered: the particle is wetted in W/G so that the interface maintains an angle of contact with the particle, the particle is wetted in oil so that it rests above the interface, and the particle is placed so that it maintains an angle of contact with the drop already resting above the interface. These cases are compared with that of two neighboring W/G drops. Off-axis rupture near the solid particle was found to be dominant in cases where the particle was wetted with W/G. However, when the particle was wetted with oil, the point of rupture occurred closer to the drop-axis. The film rupture in the drop is followed by retraction of the film and finally collapse of the drop. Both visualization and PIV results show that the trajectory of the collapsing drop depends on the initial contact condition as well as the rupture location.

  6. The Drop Tower Bremen -An Overview (United States)

    von Kampen, Peter; Könemann, Thorben; Rath, Hans J.

    Hz) demonstrates a perfect experimental environment for unperturbed investigations of scientific phenomena. Motivated by these prospects many national and international groups have initialized research programs taking advantage of this drop tower facility. In respect thereof the spectrum of research fields and technologies in space-related conditions can be continuously enhanced at ZARM. In the first of our two talks we will give you an overview about the inner structure of ZARM, as well as the service and the operation offered by the ZARM Drop Tower Operation and Service Company (ZARM FAB mbH). The ZARM FAB mbH owned by the State Government of Bremen is a public company maintaining the drop tower facility and supporting experimentalists in scientific and technical questions before, during and after their drop or catapult campaigns. In detail, we will present you important technical drop tower informations, our support and the idea, how you can proceed with your microgravity-related experiment including all your requirements to successfully accomplish an entire drop or catapult campaign. In summary, we will illustrate the complete procedure, how to drop or to catapult an experiment capsule at the Drop Tower Bremen.

  7. Electromagnetic radiation due to nonlinear oscillations of a charged drop (United States)

    Shiryaeva, S. O.; Grigor'ev, A. N.; Kolbneva, N. Yu.


    The nonlinear oscillations of a spherical charged drop are asymptotically analyzed under the conditions of a multimode initial deformation of its equilibrium shape. It is found that if the spectrum of initially excited modes contains two adjacent modes, the translation mode of oscillations is excited among others. In this case, the center of the drop's charge oscillates about the equilibrium position, generating a dipole electromagnetic radiation. It is shown that the intensity of this radiation is many orders of magnitude higher than the intensity of the drop's radiation, which arises in calculations of the first order of smallness and is related to the drop's charged surface oscillations.

  8. Drop Performance Test of CRDMs for JRTR

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Myoung-Hwan; Cho, Yeong-Garp; Chung, Jong-Ha [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Kim, Jung-Hyun [POSCO Plandtec Co. Ltd, Ulsan (Korea, Republic of); Lee, Kwan-Hee [RIST, Pohang (Korea, Republic of)


    The drop test results of CRDMs with AC-type electromagnet show that the initial delay times are not satisfied with the requirement, 0.15 seconds. After the replacement of the electromagnet from AC-type to DCtype, the drop times of CARs and accelerations due to the impact of moving parts are satisfied with all requirements. As a result, it is found that four CRDMs to be installed at site have a good drop performance, and meet all performance requirements. A control rod drive mechanism (CRDM) is a device to control the position of a control absorber rod (CAR) in the core by using a stepping motor which is commanded by the reactor regulating system (RRS) to control the reactivity during the normal operation of the reactor. The top-mounted CRDM driven by the stepping motor for Jordan Research and Training Reactor (JRTR) has been developed in KAERI. The CRDM for JRTR has been optimized by the design improvement based on that of the HANARO. It is necessary to verify the performances such as the stepping, drop, endurance, vibration, seismic and structural integrity for active components. Especially, the CAR drop curves are important data for the safety analysis. This paper describes the test results to demonstrate the drop performances of a prototype and 4 CRDMs to be installed at site. The tests are carried out at a test rig simulating the actual reactor's conditions.

  9. Drop Tower Facility at Queensland University of Technology (United States)

    Plagens, Owen; Castillo, Martin; Steinberg, Theodore; Ong, Teng-Cheong

    The Queensland University of Technology (QUT) Drop Tower Facility is a {raise.17exscriptstyle˜}2.1 second, 21.3 m fall, dual capsule drop tower system. The dual capsule comprises of an uncoupled exterior hollow drag shield that experiences drag by the ambient atmosphere with the experimental capsule falling within the drag shield. The dual capsule system is lifted to the top of the drop tower via a mechanical crane and the dropping process is initiated by the cutting of a wire coupling the experimental package and suspending the drag shield. The internal experimental capsule reaches the bottom of the drag shield floor just prior to the deceleration stage at the air bag and during this time experience gravity levels of {raise.17exscriptstyle˜}10textsuperscript{-6} g. The deceleration system utilizes an inflatable airbag where experimental packages can be designed to experience a maximum deceleration of {raise.17exscriptstyle˜}10textsuperscript{18} g for {raise.17exscriptstyle˜}0.1 seconds. The drag shield can house experimental packages with a maximum diameter of 0.8 m and height of 0.9 m. The drag shield can also be used in foam mode, where the walls are lined with foam and small experiments can be dropped completely untethered. This mode is generally used for the study of microsatellite manipulation. Payloads can be powered by on-board power systems with power delivered to the experiment until free fall occurs. Experimental data that can be collected includes but is not limited to video, temperature, pressure, voltage/current from the power supply, and triggering mechanisms outputs which are simultaneously collected via data logging systems and high speed video recording systems. Academic and commercial projects are currently under investigation at the QUT Drop Tower Facility and collaboration is openly welcome at this facility. Current research includes the study of heterogeneously burning metals in oxygen which is aimed at fire safety applications and

  10. Drop tube technical tasks (United States)

    Workman, G. L.


    Criteria, using fundamental thermochemical dynamics, were developed to assist a scientist using the Drop Tube Facility in designing a good experiment. The types of parameters involved in designing the experiments include the type of furnace, the type of atmosphere, and in general which materials are better behaved than others as determined by past experience in the facility. One of the major advantages of the facility lies in its ability to provide large undercoolings in the cooling curve during the drops. A beginning was to consider the effect of oxygen and other gases upon the amount of undercooling observed. The starting point of the thermochemistry was given by Ellingham and later transformed into what is known as the Richardson Chart. The effect of surface oxidations upon the nucleation phenomena can be observed in each specimen.

  11. Dropped object protection analyses


    Nilsen, Ingve


    Master's thesis in Offshore structural engineering Impact from dropped object is a typical accident action (NOKSOK N-004, 2013). Hence, the DOP structure is to be analyzed in an accidental limit state (ALS) design practice, which means that a non-linear finite element analysis can be applied. The DOP structure will be based on a typical DOP structure. Several FEM analyses are performed for the DOP structure. Different shapes size and weights and various impact positions are used for si...

  12. Effect of neighboring perturbations on drop coalescence at an interface (United States)

    Bordoloi, Ankur Deep; Longmire, Ellen K.


    Coalescence at a quiescent silicone oil/water glycerine interface was investigated for water/glycerine drops with Bond number ˜7 and Ohnesorge number = 0.01 using high-speed imaging and time-resolved tomographic particle image velocimetry. In addition to a single drop case, three perturbation cases were considered corresponding with a second drop, a solid particle wetted in oil, and a solid particle wetted in water/glycerine placed adjacent to the coalescing drop. Each perturbing object caused an initial tilting of the drop, influencing its rupture location and eventual collapse behavior. Once tilted, drops typically ruptured near their lowest vertical position which was located either toward or away from the perturbing object depending on the case. The initial retraction speed of the ruptured film was higher for drops initially tilted at significant angles, and the local variations in retraction speed correlated well with the expected variations in local film thickness. The drop fluid always collapsed away from the drop axis in the direction of the rupture location in all unperturbed or perturbed cases. In the case of a drop next to a particle wetted in water/glycerine, the collapsing fluid travelled away from the particle, and the downward propagating vortex ring which developed was similar to that resulting from an unperturbed drop rupture. By contrast, the drop fluid collapsed toward either a second drop or a particle wetted in oil. The resulting vortex rings were more asymmetric, and viscous interaction between the particle and collapsing fluid hindered the downward motion of the associated ring.

  13. Investigation of liquid-liquid drop coalescence using tomographic PIV (United States)

    Ortiz-Dueñas, Cecilia; Kim, Jungyong; Longmire, Ellen K.


    High-speed tomographic PIV was used to investigate the coalescence of drops placed on a liquid/liquid interface; the coalescence of a single drop and of a drop in the presence of an adjacent drop (side-by-side drops) was investigated. The viscosity ratio between the drop and surrounding fluids was 0.14, the Ohnesorge number (Oh = μd/(ρdσD)1/2) was 0.011, and Bond numbers (Bo = ( ρ d - ρ s ) gD 2/ σ) were 3.1-7.5. Evolving volumetric velocity fields of the full coalescence process allowed for quantification of the velocity scales occurring over different time scales. For both single and side-by-side drops, the coalescence initiates with an off-axis film rupture and film retraction speeds an order of magnitude larger than the collapse speed of the drop fluid. This is followed by the formation and propagation of an outward surface wave along the coalescing interface with wavelength of approximately 2D. For side-by-side drops, the collapse of the first drop is asymmetric due to the presence of the second drop and associated interface deformation. Overall, tomographic PIV provides insight into the flow physics and inherent three-dimensionalities in the coalescence process that would not be achievable with flow visualization or planar PIV only.

  14. Problematic stabilizing films in petroleum emulsions: shear rheological response of viscoelastic asphaltene films and the effect on drop coalescence. (United States)

    Harbottle, David; Chen, Qian; Moorthy, Krishna; Wang, Louxiang; Xu, Shengming; Liu, Qingxia; Sjoblom, Johan; Xu, Zhenghe


    Adsorption of asphaltenes at the water-oil interface contributes to the stability of petroleum emulsions by forming a networked film that can hinder drop-drop coalescence. The interfacial microstructure can either be liquid-like or solid-like, depending on (i) initial bulk concentration of asphaltenes, (ii) interfacial aging time, and (iii) solvent aromaticity. Two techniques--interfacial shear rheology and integrated thin film drainage apparatus--provided equivalent interface aging conditions, enabling direct correlation of the interfacial rheology and droplet stability. The shear rheological properties of the asphaltene film were found to be critical to the stability of contacting drops. With a viscous dominant interfacial microstructure, the coalescence time for two drops in intimate contact was rapid, on the order of seconds. However, as the elastic contribution develops and the film microstructure begins to be dominated by elasticity, the two drops in contact do not coalescence. Such step-change transition in coalescence is thought to be related to the high shear yield stress (~10(4) Pa), which is a function of the film shear yield point and the film thickness (as measured by quartz crystal microbalance), and the increased elastic stiffness of the film that prevents mobility and rupture of the asphaltene film, which when in a solid-like state provides an energy barrier against drop coalescence.

  15. Drop impact entrapment of bubble rings

    KAUST Repository

    Thoraval, M.-J.


    We use ultra-high-speed video imaging to look at the initial contact of a drop impacting on a liquid layer. We observe experimentally the vortex street and the bubble-ring entrapments predicted numerically, for high impact velocities, by Thoraval et al. (Phys. Rev. Lett., vol. 108, 2012, article 264506). These dynamics mainly occur within 50 -s after the first contact, requiring imaging at 1 million f.p.s. For a water drop impacting on a thin layer of water, the entrapment of isolated bubbles starts through azimuthal instability, which forms at low impact velocities, in the neck connecting the drop and pool. For Reynolds number Re above -12 000, up to 10 partial bubble rings have been observed at the base of the ejecta, starting when the contact is -20% of the drop size. More regular bubble rings are observed for a pool of ethanol or methanol. The video imaging shows rotation around some of these air cylinders, which can temporarily delay their breakup into micro-bubbles. The different refractive index in the pool liquid reveals the destabilization of the vortices and the formation of streamwise vortices and intricate vortex tangles. Fine-scale axisymmetry is thereby destroyed. We show also that the shape of the drop has a strong influence on these dynamics. 2013 Cambridge University Press.

  16. Drop splash on a smooth, dry surface (United States)

    Riboux, Guillaume; Gordillo, Jose Manuel; Korobkin, Alexander


    It is our purpose here to determine the conditions under which a drop of a given liquid with a known radius R impacting against a smooth impermeable surface at a velocity V, will either spread axisymmetrically onto the substrate or will create a splash, giving rise to usually undesired star-shaped patterns. In our experimental setup, drops are generated injecting low viscosity liquids falling under the action of gravity from a stainless steel hypodermic needle. The experimental observations using two high speed cameras operating simultaneously and placed perpendicularly to each other reveal that, initially, the drop deforms axisymmetrically, with A (T) the radius of the wetted area. For high enough values of the drop impact velocity, a thin sheet of liquid starts to be ejected from A (T) at a velocity Vjet > V for instants of time such that T >=Tc . If Vjet is above a certain threshold, which depends on the solid wetting properties as well as on the material properties of both the liquid and the atmospheric gas, the rim of the lamella dewets the solid to finally break into drops. Using Wagner's theory we demonstrate that A (T) =√{ 3 RVT } and our results also reveal that Tc We - 1 / 2 =(ρV2 R / σ) - 1 / 2 and Vjet We 1 / 4 .

  17. Drop jumping. II. The influence of dropping height on the biomechanics of drop jumping

    NARCIS (Netherlands)

    Bobbert, M F; Huijing, P A; van Ingen Schenau, G J

    In the literature, athletes preparing for explosive activities are recommended to include drop jumping in their training programs. For the execution of drop jumps, different techniques and different dropping heights can be used. This study was designed to investigate for the performance of bounce

  18. Imaging of acute pulmonary embolism using a dual energy CT system with rapid kVp switching: Initial results

    Energy Technology Data Exchange (ETDEWEB)

    Geyer, Lucas L., E-mail: [Department of Clinical Radiology, Medical Center of the University of Munich, Nussbaumstraße 20, 80336 Munich (Germany); Scherr, Michael, E-mail: [Department of Clinical Radiology, Medical Center of the University of Munich, Nussbaumstraße 20, 80336 Munich (Germany); Körner, Markus, E-mail: [Department of Clinical Radiology, Medical Center of the University of Munich, Nussbaumstraße 20, 80336 Munich (Germany); Wirth, Stefan, E-mail: [Department of Clinical Radiology, Medical Center of the University of Munich, Nussbaumstraße 20, 80336 Munich (Germany); Deak, Paul, E-mail: [GE Healthcare, Oskar-Schlemmer-Straße 11, 80807 Munich (Germany); Reiser, Maximilian F., E-mail: [Department of Clinical Radiology, Medical Center of the University of Munich, Nussbaumstraße 20, 80336 Munich (Germany); Linsenmaier, Ulrich, E-mail: [Department of Clinical Radiology, Medical Center of the University of Munich, Nussbaumstraße 20, 80336 Munich (Germany)


    Purpose: Computed tomography pulmonary angiography (CTPA) is considered as clinical gold standard for diagnosing pulmonary embolism (PE). Whereas conventional CTPA only offers anatomic information, dual energy CT (DECT) provides functional information on blood volume as surrogate of perfusion by assessing the pulmonary iodine distribution. The purpose of this study was to evaluate the feasibility of lung perfusion imaging using a single-tube DECT scanner with rapid kVp switching. Materials and methods: Fourteen patients with suspicion of acute PE underwent DECT. Two experienced radiologists assessed the CTPA images and lung perfusion maps regarding the presence of PE. The image quality was rated using a semi-quantitative 5-point scale: 1 (=excellent) to 5 (=non-diagnostic). Iodine concentrations were quantified by a ROI analysis. Results: Seventy perfusion defects were identified in 266 lung segments: 13 (19%) were rated as consistent with PE. Five patients had signs of PE at CTPA. All patients with occlusive clots were correctly identified by DECT perfusion maps. On a per patient basis the sensitivity and specificity were 80.0% and 88.9%, respectively, while on a per segment basis it was 40.0% and 97.6%, respectively. None of the patients with a homogeneous perfusion map had an abnormal CTPA. The overall image quality of the perfusion maps was rated with a mean score of 2.6 ± 0.6. There was a significant ventrodorsal gradient of the median iodine concentrations (1.1 mg/cm{sup 3} vs. 1.7 mg/cm{sup 3}). Conclusion: Lung perfusion imaging on a DE CT-system with fast kVp-switching is feasible. DECT might be a helpful adjunct to assess the clinical severity of PE.

  19. Rapid "one-pot" preparation of polymeric monolith via photo-initiated thiol-acrylate polymerization for capillary liquid chromatography. (United States)

    Bai, Jingyao; Wang, Hongwei; Ou, Junjie; Liu, Zhongshan; Shen, Yehua; Zou, Hanfa


    A facile approach was exploited for fast preparation of polymer-based monoliths in UV-transparent fused-silica capillaries via "one-pot" photo-initiated thiol-acrylate polymerization reaction of dipentaerythritolpenta-/hexaacrylate (DPEPA) and 1-octadecanethiol (ODT) in the presence of porogenic solvents (1-butanol and ethylene glycol). Due to relative insensitivity of oxygen inhibition in thiol-ene free-radical polymerization, the polymerization could be performed within 5 min. The effects of composition of prepolymerization solution on the morphology and permeability of poly(ODT-co-DPEPA) monoliths were investigated in detail by adjusting the content of monomer and binary porogen ratio. The physical properties of poly(ODT-co-DPEPA) monoliths were characterized by Fourier transform infrared spectroscopy (FT-IR), mercury intrusion porosimetry (MIP) and nitrogen adsorption/desorption measurement. The evaluation of chromatographic performance was carried out by capillary liquid chromatography (cLC). The results indicated that the poly(ODT-co-DPEPA) monolith was homogeneous and permeable, and also possessed a typical reversed-phase retention mechanism in cLC with high efficiency (∼75,000 N m(-1)) for separation of alkylbenzenes. Eventually, the further separation of tryptic digest of proteins by cLC tandem mass spectrometry (cLC-MS/MS) demonstrated its potential in the analysis of biological samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Turbulent transport of a passive contaminant in an initially anisotropic turbulence subjected to rapid rotation: an analytical study using linear theory (United States)

    El Bach, A.; Salhi, A.; Cambon, Claude


    The linear effect of rapid rotation is studied on the transport by homogeneous turbulence of a passive scalar with vertical mean scalar gradient. Connection with one-particle diffusion studied by Cambon et al. [C. Cambon, F.S. Godeferd, F. Nicolleau, J.C. Vassilicos, Turbulent diffusion in rapidly rotating turbulence with and without stable stratification, J. Fluid Mech. 499 (2004) 231-255] is discussed. The input of the initial anisotropy of the velocity field is then investigated in the axisymmetric case, using a general and systematic way to construct axisymmetric initial data: a classical expansion in terms of scalar spherical harmonics for the 3D spectral density of kinetic energy and a modified expansion for the polarization anisotropy. The scalar variance exhibits a quadratic evolution (∝t) for short times and a linear one (∝t) for larger times. The long-time behaviour looks similar to the classical 'Brownian' evolution but it has a very different origin: a linear impact of dispersive inertial waves via phase-mixing instead of a nonlinearly-induced random walk. It is shown that this trend is not altered by the polarization anisotropy. The vertical scalar flux varies linearly with time for short times and tends to a plateau for larger times. To cite this article: A. El Bach et al., C. R. Mecanique 336 (2008).

  1. High-Speed Interferometry Under Impacting Drops

    KAUST Repository

    Langley, Kenneth R.


    Over the last decade the rapid advances in high-speed video technology, have opened up to study many multi-phase fluid phenomena, which tend to occur most rapidly on the smallest length-scales. One of these is the entrapment of a small bubble under a drop impacting onto a solid surface. Here we have gone from simply observing the presence of the bubble to detailed imaging of the formation of a lubricating air-disc under the drop center and its subsequent contraction into the bubble. Imaging the full shape-evolution of the air-disc has required μm and sub-μs space and time resolutions. Time-resolved 200 ns interferometry with monochromatic light, has allowed us to follow individual fringes to obtain absolute air-layer thicknesses, based on the eventual contact with the solid. We can follow the evolution of the dimple shape as well as the compression of the gas. The improved imaging has also revealed new levels of detail, like the nature of the first contact which produces a ring of micro-bubbles, highlighting the influence of nanometric surface roughness. Finally, for impacts of ultra-viscous drops we see gliding on ~100 nm thick rarified gas layers, followed by extreme wetting at numerous random spots.

  2. Investigations of levitated helium drops (United States)

    Whitaker, Dwight Lawrence


    We report on the development of two systems capable of levitating drops of liquid helium. Helium drops of ˜20 mum have been levitated with the radiation pressure from two counter-propagating Nd:YAG laser beams. Drops are produced with a submerged piezoelectric transducer, and could be held for up to three minutes in our optical trap. Calculations show that Brillouin and Raman scattering of the laser light in the liquid helium produces a negligible rate of evaporation of the drop. Evaporation caused by the enhanced vapor pressure of the curved drop surfaces appears to be a significant effect limiting the drop lifetimes. Helium drops as large as 2 cm in diameter have been suspended in the earth's gravitational field with a magnetic field. A commercial superconducting solenoid provides the necessary field, field-gradient product required to levitate the drops. Drops are cooled to 0.5 K with a helium-3 refrigerator, and can be held in the trap indefinitely. We have found that when two or more drops are levitated in the same magnetic trap, the drops often remain in a state of apparent contact without coalescing. This effect is a result of the evaporation of liquid from between the two drops, and is found to occur only for normal fluid drops. We can induce shape oscillations in charged, levitated drops with an applied ac electric field. We have measured the resonance frequencies and damping rates for the l = 2 mode of oscillation as function of temperature. We have also developed a theory to describe the small amplitude shape oscillations of a He II drop surrounded by its saturated vapor. In our theory, we have considered two sets of boundary conditions---one where the drop does not evaporate and another in which the liquid and vapor are in thermodynamic equilibrium. We have found that both solutions give a frequency that agrees well with experiment, but that the data for the damping rate agree better with the solution without evaporation.

  3. Chaos in a Water Drop. (United States)

    Schneider, Scott Dudley

    Nature is chaotic. It appears to be more disorderly and random than orderly and regular. The path of a leaf in a rocky stream can appear as complex as the smoke from a cigarette or the outline of a cloud. In trying to model the path of a leaf in a rocky stream, the dynamical equations become rapidly complicated. A branch of scientific analysis know as Chaos has sprung up in the last few decades with techniques that can be applied to most of the physical sciences in an attempt to describe or categorize the various non-linear phenomena found in Nature. The aim of this paper is to provide an introduction to the study of chaotic behavior, with an emphasis on the potential teaching possibilities contained in some of the analysis. An appropriate beginning would be motion that is regular and "easy" to understand--stable motion. Along the way, various graphical representations will be developed that enable a clear viewing of the motion of the system under study. Next, the Logistic model will be used to gain an understanding of the nature of chaos; it is very comprehensive in representing the characteristics of chaos that will be studied in other systems. Another system studied is the three-dimensional Rossler model. In the study of the "dripping faucet", a time series of the periods between drips of water is recorded. Various techniques (collected from the introductory systems) are applied in an attempt to model the mechanism behind the water drops, or at least to characterize the graphical "animals" that we find. The water drop "attractor" is found to be chaotic, exhibiting many of the chaotic characteristics seen in other models. It is hoped that this work can be used as a primer for those students beginning a journey into Chaos, or as a reference tool for those already familiar with the topics enclosed. Many areas in this work were touched lightly; there is a rich un-tapped complexity still waiting future study. The waters here have only begun to be charted.

  4. Time-resolved imaging of a compressible air disc under a drop impacting on a solid surface

    KAUST Repository

    Li, Erqiang


    When a drop impacts on a solid surface, its rapid deceleration is cushioned by a thin layer of air, which leads to the entrapment of a bubble under its centre. For large impact velocities the lubrication pressure in this air layer becomes large enough to compress the air. Herein we use high-speed interferometry, with 200 ns time-resolution, to directly observe the thickness evolution of the air layer during the entire bubble entrapment process. The initial disc radius and thickness shows excellent agreement with available theoretical models, based on adiabatic compression. For the largest impact velocities the air is compressed by as much as a factor of 14. Immediately following the contact, the air disc shows rapid vertical expansion. The radial speed of the surface minima just before contact, can reach 50 times the impact velocity of the drop.

  5. Measuring and Improving Value of Care in Oncology Practices: ASCO Programs from Quality Oncology Practice Initiative to the Rapid Learning System. (United States)

    Jacobson, Joseph O; Neuss, Michael N; Hauser, Robert


    Rising cancer care costs are no longer sustainable. Medical oncologists must focus on providing the maximum value to their patients; improving short-term, intermediate and long-term outcomes; and managing overall costs. Accurate measurement of outcomes and overall cost is essential to informing providers and institutions and in the quest for continuous improvement in value. The ASCO Quality Oncology Practice Initiative (QOPI) is an excellent tool for sampling processes of care in medical oncology practices. To achieve the larger goal of improving the value of cancer care, ASCO is investing in the development of a Rapid Learning System, which will leverage emerging information technologies to more accurately measure outcomes (including those reported by the patient) and costs, resulting in highly efficient, effective, and safe cancer care.

  6. Rapid, non-destructive and non-contact inspection of solid foods by means of photothermal radiometry; thermal effusivity and initial heating coefficient (United States)

    Gijsbertsen, A.; Bicanic, D.; Gielen, J. L. W.; Chirtoc, M.


    CO 2-laser photothermal radiometry (PTR) was demonstrated to be suitable for the non-destructive and non-contact characterization (both optical and thermal) of solid phase agricultural commodities (fresh vegetables, fruits) and confectionery products (candy). Proper interpretation of PTR signals enable one to calculate two parameters, i.e. the well known thermal effusivity e ( e= λρc p, where λ and ρcp are the thermal conductivity and the volume specific heat, respectively) and a newly introduced physical quantity termed 'initial heating coefficient' chi ( χ= β/( ρcp), β is the absorption coefficient). Obtained values for e are in a good agreement with data reported in the literature. PTR enables one to rapidly determine e via a single measurement. As opposed to this, the knowledge of two out of three thermophysical parameters (thermal diffusivity, thermal conductivity and volume specific heat) is a condition sine qua non for determining effusivity in the conventional manner.

  7. Pressure drop in contraction flow

    DEFF Research Database (Denmark)

    Rasmussen, Henrik Koblitz

    This note is a supplement to Dynamic of Polymeric Liquids (DPL) page 178. DPL gives an equation for the pressure drop in a tapered (and circular) contraction, valid only at low angles. Here the general definition of contraction flow (the Bagley correction) and a more general method to find...... the pressure drop in a contraction are given....

  8. Laser impact on a drop

    CERN Document Server

    Klein, Alexander L; Bouwhuis, Wilco; Lhuissier, Henri; Sun, Chao; Snoeijer, Jacco H; Villermaux, Emmanuel; Lohse, Detlef; Gelderblom, Hanneke


    The impact of a laser pulse on a highly absorbing liquid drop can lead to a violent response: the drop is accelerated, strongly deforms, and eventually fragments. Shock waves, the ejection of matter, and even plasma formation can accompany this process ...

  9. Gas Pressure-Drop Experiment (United States)

    Luyben, William L.; Tuzla, Kemal


    Most chemical engineering undergraduate laboratories have fluid mechanics experiments in which pressure drops through pipes are measured over a range of Reynolds numbers. The standard fluid is liquid water, which is essentially incompressible. Since density is constant, pressure drop does not depend on the pressure in the pipe. In addition, flow…

  10. Development of a Rapid Cartilage Damage Quantification Method for the Lateral Tibiofemoral Compartment Using Magnetic Resonance Images: Data from the Osteoarthritis Initiative

    Directory of Open Access Journals (Sweden)

    Ming Zhang


    Full Text Available The purpose of this study was to expand and validate the cartilage damage index (CDI to detect cartilage damage in the lateral tibiofemoral compartment. We used an iterative 3-step process to develop and validate the lateral CDI: development (100 knees, testing (80 knees, and validation (100 knees. The validation set included 100 knees from the Osteoarthritis Initiative that was enriched to include all grades of lateral joint space narrowing (JSN, 0–3. Measurement of the CDI was rapid at 7.4 (s.d. 0.73 minutes per knee pair (baseline and follow-up of one knee. The intratester reliability is good (intraclass correlation coefficient (3, 1 model = 0.86 to 0.98. At baseline, knees with greater KL grade and lateral JSN had a lower mean CDI (i.e., greater cartilage damage. Baseline lateral CDI is associated with both lateral JSW (r=0.81 to 0.85, p<0.01 and HKA (r=-0.30 to −0.33, p<0.05. The SRM is good (lateral femur SRM = −0.76; lateral tibia SRM = −0.73; lateral tibiofemoral total SRM = −0.87. The lateral tibiofemoral CDI quantification allows for rapid evaluation and is reliable and responsive, with good construct validity. It may be an efficient method to measure lateral tibiofemoral articular cartilage in large clinical and epidemiologic studies.

  11. Drop by drop scattering properties of a radar bin : a numerical experiment (United States)

    Gires, Auguste; Tchiguirinskaia, Ioulia; Schertzer, Daniel


    This paper presents the development and initial results of a numerical simulation of pseudo-radar observations computed as the sum of the electric field backscattered by each drop. Simulations are carried out for three successive radar bins with a gate length of 30 m and beam width of 1°. The first step is the simulation of a 100 m x 100 m x 100 m volume with all its drops. The 3D raindrop generator relies on the findings on the rainfall field very small scales (mm to few tens of m) spatio-temporal structure, of the HYDROP experiment and a recent analysis of 2D video disdrometer data in a Multifractal framework. More precisely: (i) The Liquid Water Content (LWC) distribution is represented with the help a multiplicative cascade down to 0.5 m, below which it is considered as homogeneous. (ii) Within each 0.5 x 0.5 x 0.5 m3 patch, liquid water is distributed into drops according to a pre-defined Drop Size Distribution (DSD) and located randomly uniformly. (iii) Such configuration is compared with the one consisting of the same drops uniformly distributed over the 50 x 50 x 50 m3 volume. Then the backscattered field by the drops located within a radar bin are computed as the sum a individual contribution. Antenna beam weighing is taken into account Due to the fact that the radar wave length is much smaller than the "patches" size for rainfall, it appears that as theoretically expected we retrieved an exponential distribution for potential measure horizontal reflectivity. A much lower dispersion is noticed for differential reflectivity. We show that a simple ballistic assumption for drop velocities does not enable to reproduce radar observations, and turbulence must be taken into account. Finally the sensitivity of these outputs to the various model parameters is quantified.

  12. A drop in uniaxial and biaxial nonlinear extensional flows (United States)

    Favelukis, M.


    In this theoretical report, we explore small deformations of an initially spherical drop subjected to uniaxial or biaxial nonlinear extensional creeping flows. The problem is governed by the capillary number (Ca), the viscosity ratio (λ), and the nonlinear intensity of the flow (E). When the extensional flow is linear (E = 0), the familiar internal circulations are obtained and the same is true with E > 0, except that the external and internal flow rates increase with increasing E. If E 0) and oblate spheroidal drops for biaxial flows (Ca 0, the drop is more elongated than the linear case, while E 0 tends to facilitate drop breakup, while E < 0 makes drop breakup more difficult.

  13. Drop interaction with solid boundaries in liquid/liquid systems (United States)

    Bordoloi, Ankur Deep

    The present experimental work was motivated primarily by the CO 2 sequestration process. In a possible scenario during this process, gravity driven CO2 bubbles coalesce at an interface near the rock surface. In another scenario, trapped CO2 fluid may escape from a porous matrix overcoming interfacial force inside a pore. Based on these potential scenarios, the current research was divided into two broad experimental studies. In the first part, coalescence at a quiescent interface of two analogous fluids (silicone oil and water/glycerin mixture) was investigated for water/glycerin drops with Bond number (Bo) ~7 and Ohnesorge number ~ 0.01 using high-speed imaging and time-resolved tomographic PIV. Two perturbation cases with a solid particle wetted in oil and water/glycerin placed adjacent to the coalescing drop were considered. The results were compared with coalescence of a single drop and that of a drop neighBored by a second drop of equivalent size. Each perturbing object caused an initial tilting of the drop, influencing its rupture location, subsequent film retraction and eventual collapse behavior. Once tilted, drops typically ruptured near their lowest vertical position which was located either toward or away from the perturbing object depending on the case. The trends in local retraction speed of the ruptured film and the overall dynamics of the collapsing drops were discussed in detail. In the second part, the motion of gravity driven drops (B o~0.8-11) through a confining orifice d/Dglycerin, surrounded by silicone oil, fall toward and encounter the orifice plate after reaching terminal speed. The effects of surface wettability were investigated for Both round-edged and sharp-edged orifices. For the round-edged case, a thin film of surrounding oil prevented the drop fluid from contacting the orifice surface, such that the flow outcomes of the drops were independent of surface wettability. For d/D<0.8, the Boundary between drop capture and release depended

  14. Pressure drop increase by biofilm accumulation in spiral wound RO and NF membrane systems: role of substrate concentration, flow velocity, substrate load and flow direction. (United States)

    Vrouwenvelder, J S; Hinrichs, C; Van der Meer, W G J; Van Loosdrecht, M C M; Kruithof, J C


    In an earlier study, it was shown that biofouling predominantly is a feed spacer channel problem. In this article, pressure drop development and biofilm accumulation in membrane fouling simulators have been studied without permeate production as a function of the process parameters substrate concentration, linear flow velocity, substrate load and flow direction. At the applied substrate concentration range, 100-400 microg l(-1) as acetate carbon, a higher concentration caused a faster and greater pressure drop increase and a greater accumulation of biomass. Within the range of linear flow velocities as applied in practice, a higher linear flow velocity resulted in a higher initial pressure drop in addition to a more rapid and greater pressure drop increase and biomass accumulation. Reduction of the linear flow velocity resulted in an instantaneous reduction of the pressure drop caused by the accumulated biomass, without changing the biofilm concentration. A higher substrate load (product of substrate concentration and flow velocity) was related to biomass accumulation. The effect of the same amount of accumulated biomass on the pressure drop increase was related to the linear flow velocity. A decrease of substrate load caused a gradual decline in time of both biomass concentration and pressure drop increase. It was concluded that the pressure drop increase over spiral wound reverse osmosis (RO) and nanofiltration (NF) membrane systems can be reduced by lowering both substrate load and linear flow velocity. There is a need for RO and NF systems with a low pressure drop increase irrespective of the biomass formation. Current efforts to control biofouling of spiral wound membranes focus in addition to pretreatment on membrane improvement. According to these authors, adaptation of the hydrodynamics, spacers and pressure vessel configuration offer promising alternatives. Additional approaches may be replacing heavily biofouled elements and flow direction reversal.

  15. Creeping motion of long bubbles and drops in capillary tubes

    DEFF Research Database (Denmark)

    Westborg, Henrik; Hassager, Ole


    at high capillary numbers. Furthermore the flow of a viscous drop through a doughnut shaped constriction in a capillary tube has been simulated. The simulations show that snap-off may be initiated by a sudden drop in the flow rate after the drops have protruded for some distance beyond the throat...... and the snap-off time increases with increasing capillary number. Snap-off without a sudden decrease of the flow rate does not seem to occur in constrictions of circular cross section....

  16. Economic and clinical effects of evaluating rapid viral response to peginterferon alfa-2b plus ribavirin for the initial treatment of chronic hepatitis C. (United States)

    Wong, John B; Davis, Gary L; McHutchison, John G; Manns, Michael P; Albrecht, Janice K


    Evaluation of 12-wk viral response to initial antiviral therapy for chronic hepatitis C has been recommended to minimize antiviral-associated morbidity and costs. The aim of this study was to examine the economic and clinical effects of evaluating rapid viral response during antiviral therapy for treatment naive chronic hepatitis C patients. We applied viral response and drug dosage from an international randomized clinical trial of ribavirin plus peginterferon alfa-2b or ribavirin plus interferon alfa-2b to a previously published computer cohort simulation to project lifelong clinical and economic outcomes. Natural history and economic estimates were based on published literature, expert panel estimates, and actual variable and reimbursement cost data. The assessment of 12-wk rapid viral response reduced antiviral treatment duration by 40-44% and antiviral costs by 44-45% (savings of $15,116-16,268 for peginterferon plus ribavirin and $8300 for interferon plus ribavirin) compared to full 48-wk dosing. With the 12-wk evaluation, the marginal cost-effectiveness of peginterferon plus ribavirin versus interferon plus ribavirin was $13,600-22,800 compared with $14,600-25,000 per discounted quality adjusted life-year gained with the 24-wk evaluation. For genotype 1, hepatitis C infected patients, 12-wk testing for peginterferon plus ribavirin remaining preferred and cost-effective compared with interferon plus ribavirin. For genotype 2 or 3, hepatitis C infected patients, 12-wk testing yielded similar results to those of 24-wk treatment. Assessment of 12-wk viral response in genotype 1, hepatitis C infected patients should reduce peginterferon plus ribavirin morbidity and costs and improve its cost-effectiveness; however, for genotype 2 and 3, hepatitis C infected patients, 12-wk testing and 24-wk treatment have similar outcomes. Decisions regarding continuation of antiviral treatment should also consider the variability in the accuracy of quantitative viral assays as

  17. 45-FOOT HIGH DROP TOWER (United States)

    Federal Laboratory Consortium — The Drop Tower is used to simulate and measure the impact shocks that are exerted on parachute loads when they hit the ground. It is also used for HSL static lift to...

  18. Assimilation of GOES satellite-based convective initiation and cloud growth observations into the Rapid Refresh and HRRR systems to improve aviation forecast guidance (United States)

    Mecikalski, John; Smith, Tracy; Weygandt, Stephen


    Latent heating profiles derived from GOES satellite-based cloud-top cooling rates are being assimilated into a retrospective version of the Rapid Refresh system (RAP) being run at the Global Systems Division. Assimilation of these data may help reduce the time lag for convection initiation (CI) in both the RAP model forecasts and in 3-km High Resolution Rapid Refresh (HRRR) model runs that are initialized off of the RAP model grids. These data may also improve both the location and organization of developing convective storm clusters, especially in the nested HRRR runs. These types of improvements are critical for providing better convective storm guidance around busy hub airports and aviation corridor routes, especially in the highly congested Ohio Valley - Northeast - Mid-Atlantic region. Additional work is focusing on assimilating GOES-R CI algorithm cloud-top cooling-based latent heating profiles directly into the HRRR model. Because of the small-scale nature of the convective phenomena depicted in the cloud-top cooling rate data (on the order of 1-4 km scale), direct assimilation of these data in the HRRR may be more effective than assimilation in the RAP. The RAP is an hourly assimilation system developed at NOAA/ESRL and was implemented at NCEP as a NOAA operational model in May 2012. The 3-km HRRR runs hourly out to 15 hours as a nest within the ESRL real-time experimental RAP. The RAP and HRRR both use the WRF ARW model core, and the Gridpoint Statistical Interpolation (GSI) is used within an hourly cycle to assimilate a wide variety of observations (including radar data) to initialize the RAP. Within this modeling framework, the cloud-top cooling rate-based latent heating profiles are applied as prescribed heating during the diabatic forward model integration part of the RAP digital filter initialization (DFI). No digital filtering is applied on the 3-km HRRR grid, but similar forward model integration with prescribed heating is used to assimilate

  19. Towards Elimination of Mother-to-Child Transmission of HIV: The Impact of a Rapid Results Initiative in Nyanza Province, Kenya

    Directory of Open Access Journals (Sweden)

    Lisa L. Dillabaugh


    Full Text Available Many HIV-positive pregnant women and infants are still not receiving optimal services, preventing the goal of eliminating mother-to-child transmission (MTCT and improving maternal child health overall. A Rapid Results Initiative (RRI approach was utilized to address key challenges in delivery of prevention of MTCT (PMTCT services including highly active antiretroviral therapy (HAART uptake for women and infants. The RRI was conducted between April and June 2011 at 119 health facilities in five districts in Nyanza Province, Kenya. Aggregated site-level data were compared at baseline before the RRI (Oct 2010–Jan 2011, during the RRI, and post-RRI (Jul–Sep 2011 using pre-post cohort analysis. HAART uptake amongst all HIV-positive pregnant women increased by 40% (RR 1.4, 95% CI 1.2–1.7 and continued to improve post-RRI (RR 1.6, 95% CI 1.4–1.8. HAART uptake in HIV-positive infants remained stable (RR 1.1, 95% CI 0.9–1.4 during the RRI and improved by 30% (RR 1.3, 95% CI 1.0–1.6 post-RRI. Significant improvement in PMTCT services can be achieved through introduction of an RRI, which appears to lead to sustained benefits for pregnant HIV-infected women and their infants.

  20. Fast H-DROP: A thirty times accelerated version of H-DROP for interactive SVM-based prediction of helical domain linkers (United States)

    Richa, Tambi; Ide, Soichiro; Suzuki, Ryosuke; Ebina, Teppei; Kuroda, Yutaka


    Efficient and rapid prediction of domain regions from amino acid sequence information alone is often required for swift structural and functional characterization of large multi-domain proteins. Here we introduce Fast H-DROP, a thirty times accelerated version of our previously reported H-DROP (Helical Domain linker pRediction using OPtimal features), which is unique in specifically predicting helical domain linkers (boundaries). Fast H-DROP, analogously to H-DROP, uses optimum features selected from a set of 3000 ones by combining a random forest and a stepwise feature selection protocol. We reduced the computational time from 8.5 min per sequence in H-DROP to 14 s per sequence in Fast H-DROP on an 8 Xeon processor Linux server by using SWISS-PROT instead of Genbank non-redundant (nr) database for generating the PSSMs. The sensitivity and precision of Fast H-DROP assessed by cross-validation were 33.7 and 36.2%, which were merely 2% lower than that of H-DROP. The reduced computational time of Fast H-DROP, without affecting prediction performances, makes it more interactive and user-friendly. Fast H-DROP and H-DROP are freely available from

  1. VTrans Small Culvert Inventory - Drop Inlets (United States)

    Vermont Center for Geographic Information — Vermont Agency of Transportation Small Culvert Inventory: Drop Inlets. This data contains drop inlets locations along VTrans maintained roadways. The data was...

  2. Characteristics of patients in an eating disorder sample who dropped out: 2-year follow-up. (United States)

    Gómez Del Barrio, Andrés; Vellisca Gonzalez, María Yolanda; González Gómez, Jana; Latorre Marín, José Ignacio; Carral-Fernández, Laura; Orejudo Hernandez, Santos; Madrazo Río-Hortega, Inés; Moreno Malfaz, Laura


    This manuscript explores the characteristics of individuals diagnosed with an eating disorder who dropped out of treatment, compared with those who completed it. The participants were 196 patients diagnosed with eating disorders (according to DSM-IV-TR criteria) who consecutively began treatment for the first time in an eating disorders unit. They were assessed at baseline with a set of questionnaires evaluating eating habits, temperament, and general psychopathology. During the follow-up period, patients who dropped out were re-assessed via a telephone interview. In the course of a 2-year follow-up, a total of 80 (40.8%) patients were labeled as dropouts, and 116 (59.2%) remaining subjects were considered completers. High TCI scores in the character dimensions of Disorderliness (NS4) (p < .01) and total Novelty Seeking (NST), along with low scores in Dependency (RD4), were significantly associated with dropout in the course of 2 years. Once the results were submitted to logistic regression analysis, dropout only remained associated with high scores in Disorderliness (NS4) and, inversely, with an initial Anorexia Nervosa (AN) diagnosis (p < .05). Reasons for dropout stated by the patients included logistic difficulties, subjective improvement of their condition, and lack of motivation. Clinicians should handle the first therapeutic intervention with particular care in order to enhance their understanding of clients and their ability to rapidly identify those who are at risk of dropping out of treatment. Level III: Cohort Study.

  3. Inverse Leidenfrost effect: self-propelling drops on a bath (United States)

    Gauthier, Anais; van der Meer, Devaraj; Lohse, Detlef; Physics of Fluids Team


    When deposited on very hot solid, volatile drops can levitate over a cushion of vapor, in the so-called Leidenfrost state. This phenomenon can also be observed on a hot bath and similarly to the solid case, drops are very mobile due to the absence of contact with the substrate that sustains them. We discuss here a situation of ``inverse Leidenfrost effect'' where room-temperature drops levitate on a liquid nitrogen pool - the vapor is generated here by the bath sustaining the relatively hot drop. We show that the drop's movement is not random: the liquid goes across the bath in straight lines, a pattern only disrupted by elastic bouncing on the edges. In addition, the drops are initially self-propelled; first at rest, they accelerate for a few seconds and reach velocities of the order of a few cm/s, before slowing down. We investigate experimentally the parameters that affect their successive acceleration and deceleration, such as the size and nature of the drops and we discuss the origin of this pattern.

  4. Clustering of particles and pathogens within evaporating drops (United States)

    Park, Jaebum; Kim, Ho-Young


    The evaporation of sessile suspension drops leads to accumulation of the particles around the pinned contact line, which is widely termed the coffee ring effect. However, the evaporation behavior of a liquid drop containing a small number of particles with the size comparable to the host drop is unclear yet. Thus, here we investigate the motion and spatial distribution of large particles within a sessile drop. The spherical particles cluster only when their initial distance is below a critical value, which is a function of the diameter and wettability of particle as well as the surface tension and size of the host drop. We rationalize such a critical distance for self-assembly based on the balance of the capillary force and the frictional resistance to sliding and rolling of the particles on a solid substrate. We further discuss the physical significance of this drop-mediated ``Cheerios effect'' in connection with the fate of pathogens residing in drops as a result of sneezing and coughing.

  5. Partial coalescence from bubbles to drops

    KAUST Repository

    Zhang, F. H.


    The coalescence of drops is a fundamental process in the coarsening of emulsions. However, counter-intuitively, this coalescence process can produce a satellite, approximately half the size of the original drop, which is detrimental to the overall coarsening. This also occurs during the coalescence of bubbles, while the resulting satellite is much smaller, approximately 10 %. To understand this difference, we have conducted a set of coalescence experiments using xenon bubbles inside a pressure chamber, where we can continuously raise the pressure from 1 up to 85 atm and thereby vary the density ratio between the inner and outer fluid, from 0.005 up to unity. Using high-speed video imaging, we observe a continuous increase in satellite size as the inner density is varied from the bubble to emulsion-droplet conditions, with the most rapid changes occurring as the bubble density grows up to 15 % of that of the surrounding liquid. We propose a model that successfully relates the satellite size to the capillary wave mode responsible for its pinch-off and the overall deformations from the drainage. The wavelength of the primary wave changes during its travel to the apex, with the instantaneous speed adjusting to the local wavelength. By estimating the travel time of this wave mode on the bubble surface, we also show that the model is consistent with the experiments. This wavenumber is determined by both the global drainage as well as the interface shapes during the rapid coalescence in the neck connecting the two drops or bubbles. The rate of drainage is shown to scale with the density of the inner fluid. Empirically, we find that the pinch-off occurs when 60 % of the bubble fluid has drained from it. Numerical simulations using the volume-of-fluid method with dynamic adaptive grid refinement can reproduce these dynamics, as well as show the associated vortical structure and stirring of the coalescing fluid masses. Enhanced stirring is observed for cases with second

  6. Drops, contact lines, and electrowetting

    NARCIS (Netherlands)

    't Mannetje, Dieter


    In this work, we study the behaviour of drops and contact lines under the influence of electric fields, and how these can answer fundamental and industrial questions. Our focus is on studying the varying balance of the electric field, hysteresis forces and inertia as the speed of a contact line

  7. Rapid elimination kinetics of free PSA or human kallikrein-related peptidase 2 after initiation of gonadotropin-releasing hormone-antagonist treatment of prostate cancer

    DEFF Research Database (Denmark)

    Ulmert, David; Vickers, Andrew J; Scher, Howard I


    The utility of conventional prostate-specific antigen (PSA) measurements in blood for monitoring rapid responses to treatment for prostate cancer is limited because of its slow elimination rate. Prior studies have shown that free PSA (fPSA), intact PSA (iPSA) and human kallikrein-related peptidase...... of tPSA, fPSA, iPSA and hK2 after rapid induction of castration with degarelix (Firmagon(®)), a novel GnRH antagonist....

  8. The breakup of levitating water drops observed with a high speed camera

    Directory of Open Access Journals (Sweden)

    C. Emersic


    Full Text Available Collision-induced water drop breakup in a vertical wind tunnel was observed using a high speed camera for interactions between larger drop sizes (up to 7 mm diameter than have previously been experimentally observed. Three distinct collisional breakup types were observed and the drop size distributions from each were analysed for comparison with predictions of fragment distributions from larger drops by two sets of established breakup parameterisations. The observations showed some similarities with both parameterisations but also some marked differences for the breakup types that could be compared, particularly for fragments 1 mm and smaller. Modifications to the parameterisations are suggested and examined. Presented is also currently the largest dataset of bag breakup distributions observed. Differences between this and other experimental research studies and modelling parameterisations, and the associated implications for interpreting results are discussed. Additionally, the stochastic coalescence and breakup equation was solved computationally using a breakup parameterisation, and the evolving drop-size distribution for a range of initial conditions was examined. Initial cloud liquid water content was found to have the greatest influence on the resulting distribution, whereas initial drop number was found to have relatively little influence. This may have implications when considering the effect of aerosol on cloud evolution, raindrop formation and resulting drop size distributions. Calculations presented show that, using an ideal initial cloud drop-size distribution, ~1–3% of the total fragments are contributed from collisional breakup between drops of 4 and 6 mm.

  9. Experimental investigation of picoliter liquid drops evaporation on a heated solid surface (United States)

    Kirichenko, D. P.; Zaitsev, D. V.; Kabov, O. A.


    This paper presents a study of the evaporation of sessile picoliter liquid drops on a heated solid surface. It has been shown that during evaporation diameter of the drop is almost constant (the contact line is pinned) and starts to decrease only at the final moment of drop life. It has been shown that the specific evaporation rate of a droplet (droplet weight loss per unit time per unit droplet surface area) is not constant over time: it gradually grows with time up to a maximum, but at the final stage, when the height of the drop becomes on the order of 1 μm, it decreases rapidly.

  10. Experimental Research on Thermocapillary-Buoyancy Migration Interaction of Axisymmetric Two Drops by Using Digital Holographic Interferometry (United States)

    Zhang, Shuoting; Duan, Li; Kang, Qi


    The migration and interaction of axisymmetric two drops in a vertical temperature gradient is investigated experimentally on the ground. A silicon oil is used as the continuous phase, and a water-ethanol mixture is used as the drop phase, respectively. The migration and interaction of two drops, under the combined effects of buoyancy and thermocapillary, is recorded by a digital holographic interferometry measurement in the experiment to analyse the velocities and temperature distribution of the drops. As a result, when two drops migrate together, the drop affects the other drop by perturbing the temperature field around itself. For the leading drop, the velocity is faster than the one of the isolated drop, and the maximum of the interfacial temperature distribution is larger than the one of the isolated drop. For the trailing drop, the velocity is slower than the one of the isolated drop, and the maximum of the interfacial temperature distribution is less than the one of the isolated drop. The influence of the dimensionless initial distance between the drop centres to the drop migration is discussed in detail in this study.

  11. Influence of droplet geometry on the coalescence of low viscosity drops. (United States)

    Eddi, A; Winkels, K G; Snoeijer, J H


    The coalescence of water drops on a substrate is studied experimentally. We focus on the rapid growth of the bridge connecting the two drops, which very quickly after contact ensues from a balance of surface tension and liquid inertia. For drops with contact angles below 90°, we find that the bridge grows with a self-similar dynamics that is characterized by a height h~t(2/3). By contrast, the geometry of coalescence changes dramatically for contact angles at 90°, for which we observe h~t(1/2), just as for freely suspended spherical drops in the inertial regime. We present a geometric model that quantitatively captures the transition from 2/3 to 1/2 exponent, and unifies the inertial coalescence of sessile drops and freely suspended drops.

  12. Acoustically levitated dancing drops: Self-excited oscillation to chaotic shedding (United States)

    Lin, Po-Cheng; I, Lin


    We experimentally demonstrate self-excited oscillation and shedding of millimeter-sized water drops, acoustically levitated in a single-node standing waves cavity, by decreasing the steady acoustic wave intensity below a threshold. The perturbation of the acoustic field by drop motion is a possible source for providing an effective negative damping for sustaining the growing amplitude of the self-excited motion. Its further interplay with surface tension, drop inertia, gravity and acoustic intensities, select various self-excited modes for different size of drops and acoustic intensity. The large drop exhibits quasiperiodic motion from a vertical mode and a zonal mode with growing coupling, as oscillation amplitudes grow, until falling on the floor. For small drops, chaotic oscillations constituted by several broadened sectorial modes and corresponding zonal modes are self-excited. The growing oscillation amplitude leads to droplet shedding from the edges of highly stretched lobes, where surface tension no longer holds the rapid expanding flow.

  13. Crack formation and prevention in colloidal drops (United States)

    Kim, Jin Young; Cho, Kun; Ryu, Seul-A.; Kim, So Youn; Weon, Byung Mook


    Crack formation is a frequent result of residual stress release from colloidal films made by the evaporation of colloidal droplets containing nanoparticles. Crack prevention is a significant task in industrial applications such as painting and inkjet printing with colloidal nanoparticles. Here, we illustrate how colloidal drops evaporate and how crack generation is dependent on the particle size and initial volume fraction, through direct visualization of the individual colloids with confocal laser microscopy. To prevent crack formation, we suggest use of a versatile method to control the colloid-polymer interactions by mixing a nonadsorbing polymer with the colloidal suspension, which is known to drive gelation of the particles with short-range attraction. Gelation-driven crack prevention is a feasible and simple method to obtain crack-free, uniform coatings through drying-mediated assembly of colloidal nanoparticles.

  14. Drop Impact on a Solid Surface

    KAUST Repository

    Josserand, C.


    © Copyright 2016 by Annual Reviews. All rights reserved. A drop hitting a solid surface can deposit, bounce, or splash. Splashing arises from the breakup of a fine liquid sheet that is ejected radially along the substrate. Bouncing and deposition depend crucially on the wetting properties of the substrate. In this review, we focus on recent experimental and theoretical studies, which aim at unraveling the underlying physics, characterized by the delicate interplay of not only liquid inertia, viscosity, and surface tension, but also the surrounding gas. The gas cushions the initial contact; it is entrapped in a central microbubble on the substrate; and it promotes the so-called corona splash, by lifting the lamella away from the solid. Particular attention is paid to the influence of surface roughness, natural or engineered to enhance repellency, relevant in many applications.

  15. The IFSI Experimental Gravitation Group drop tower (United States)

    Iafolla, Valerio; Fiorenza, Emiliano; Lefevre, Carlo; Nozzoli, Sergio; Peron, Roberto; Reale, Andrea; Santoli, Francesco

    The Experimental Gravitation Group of Istituto di Fisica dello Spazio Interplanetario (IFSI-INAF) has recently completed the development of a drop tower in its laboratories. This new facility is used in the context of the wide range of activities of the Group, in particular for testing high-sensitivity accelerometers and gradiometers. These instruments will be mainly operated in free fall conditions and this facility will be used for simulating these conditions. The tower has an height of 10 m (7-8 m effective fall height). Its capabilities include a magnetic release mechanism, a (variable acceleration) recovery system and will include a telemetry system. Following a description of the facility, the main foreseen uses will be discussed, among them: tests of accelerometer working position stability, release transient effects, capability of test mass initial attitude and angular velocity control, repeatability.

  16. Crack formation and prevention in colloidal drops. (United States)

    Kim, Jin Young; Cho, Kun; Ryu, Seul-A; Kim, So Youn; Weon, Byung Mook


    Crack formation is a frequent result of residual stress release from colloidal films made by the evaporation of colloidal droplets containing nanoparticles. Crack prevention is a significant task in industrial applications such as painting and inkjet printing with colloidal nanoparticles. Here, we illustrate how colloidal drops evaporate and how crack generation is dependent on the particle size and initial volume fraction, through direct visualization of the individual colloids with confocal laser microscopy. To prevent crack formation, we suggest use of a versatile method to control the colloid-polymer interactions by mixing a nonadsorbing polymer with the colloidal suspension, which is known to drive gelation of the particles with short-range attraction. Gelation-driven crack prevention is a feasible and simple method to obtain crack-free, uniform coatings through drying-mediated assembly of colloidal nanoparticles.

  17. Impact of ultra-viscous drops: air-film gliding and extreme wetting

    KAUST Repository

    Langley, Kenneth


    A drop impacting on a solid surface must push away the intervening gas layer before making contact. This entails a large lubricating air pressure which can deform the bottom of the drop, thus entrapping a bubble under its centre. For a millimetric water drop, the viscous-dominated flow in the thin air layer counteracts the inertia of the drop liquid. For highly viscous drops the viscous stresses within the liquid also affect the interplay between the drop and the gas. Here the drop also forms a central dimple, but its outer edge is surrounded by an extended thin air film, without contacting the solid. This is in sharp contrast with impacts of lower-viscosity drops where a kink in the drop surface forms at the edge of the central disc and makes a circular contact with the solid. Larger drop viscosities make the central air dimple thinner. The thin outer air film subsequently ruptures at numerous random locations around the periphery, when it reaches below 150 nm thickness. This thickness we measure using high-speed two-colour interferometry. The wetted circular contacts expand rapidly, at orders of magnitude larger velocities than would be predicted by a capillary-viscous balance. The spreading velocity of the wetting spots is independent of the liquid viscosity. This may suggest enhanced slip of the contact line, assisted by rarefied-gas effects, or van der Waals forces in what we call extreme wetting. Myriads of micro-bubbles are captured between the local wetting spots.

  18. Mapping coalescence of micron-sized drops and bubbles. (United States)

    Berry, Joseph D; Dagastine, Raymond R


    Emulsion formulation, solvent extraction and multiphase microfluidics are all examples of processes that require precise control of drop or bubble collision stability. We use a previously validated numerical model to map the exact conditions under which micron-sized drops or bubbles undergo coalescence in the presence of colloidal forces and hydrodynamic effects relevant to Brownian motion and low Reynolds number flows. We demonstrate that detailed understanding of how the equilibrium surface forces vary with film thickness can be applied to make accurate predictions of the outcome of a drop or bubble collision when hydrodynamic effects are negligible. In addition, we illuminate the parameter space (i.e. interaction velocity, drop deformation, interfacial tension, etc.) at which hydrodynamic effects can stabilise collisions that are unstable at equilibrium. Further, we determine conditions for which drop or bubble collisions become unstable upon separation, caused by negative hydrodynamic pressure in the film. Lastly, we show that scaling analyses are not applicable for constant force collisions where the approach timescale is comparable to the coalescence timescale, and demonstrate that initial conditions under these circumstances cannot be ignored. Copyright © 2016 Elsevier Inc. All rights reserved.

  19. Optic neuritis and rapidly progressive necrotizing retinitis as the initial signs of subacute sclerosing panencephalitis: a case report with clinical and histopathologic findings. (United States)

    Oray, Merih; Tuncer, Samuray; Kir, Nur; Karacorlu, Murat; Tugal-Tutkun, Ilknur


    We report a case of subacute sclerosing panencephalitis (SSPE) presenting first with optic neuritis and rapidly progressive necrotizing retinitis at the posterior pole. We reviewed the clinical, laboratory, photographic, angiographic, and histopathologic records of a patient with SSPE. A 15-year-old girl was referred after rapid loss of vision due to optic neuritis and macular necrosis in the right eye. She had a history of cardiac valve surgery, but had no systemic symptoms and extensive work-up was unrewarding. Contralateral involvement with rapidly progressive optic neuritis and macular necrotizing retinitis prompted retinochoroidal biopsy of the right eye, which revealed necrosis of inner retinal layers and perivascular lymphoplasmocytic infiltration with intact choroid and outer retina without any findings of inclusion bodies, microorganisms, or atypical cells. The diagnosis was based on histopathologic findings consistent with SSPE, and detection of elevated measles antibody titers in cerebrospinal fluid and serum. It was further confirmed by development of typical electroencephalography pattern at 6 months and neurological symptoms at 4-year follow-up. Clinicians need to be aware that optic neuritis and necrotizing retinitis at the posterior pole may be the presenting features of SSPE.

  20. Drop shaping by laser-pulse impact

    CERN Document Server

    Klein, Alexander L; Visser, Claas Willem; Lhuissier, Henri; Sun, Chao; Snoeijer, Jacco H; Villermaux, Emmanuel; Lohse, Detlef; Gelderblom, Hanneke


    We study the hydrodynamic response of a falling drop hit by a laser pulse. Combining high-speed with stroboscopic imaging we report that a millimeter-sized dyed water drop hit by a milli-Joule nanosecond laser-pulse deforms and propels forward at several meters per second, until it eventually fragments. We show that the drop motion results from the recoil momentum imparted at the drop surface by water vaporization. We measure the propulsion speed and the time-deformation law of the drop, complemented by boundary integral simulations. We explain the drop propulsion and shaping in terms of the laser pulse energy and drop surface tension. These findings are crucial for the generation of extreme ultraviolet (EUV) light in lithography machines.

  1. Viscous drops bounce faster: prompt tumbling-rebound from a sublimating slope (United States)

    Antonini, Carlo; Jung, Stefan; Wetzel, Andreas; Heer, Emmanuel; Schoch, Philippe; Mazloomi, M. Ali; Chikatamarla, Shyam S.; Karlin, Ilya; Marengo, Marco; Poulikakos, Dimos


    We discovered a new drop rebound regime, characteristic of highly viscous liquids impacting onto tilted sublimating surfaces. By focusing on non-axisymmetric impact conditions at increasing viscosity, we demonstrate that low viscous drops show a ``slide, spread, recoil and rebound'' behavior, whereas viscous drops exhibit a ``prompt tumbling-rebound'' behavior. As such, viscous glycerol drops surprisingly rebound faster than three orders of magnitude less viscous water drops. This is made possible by a small conversion of translational to rotational kinetic energy, at non-axisymmetric impact conditions, as also confirmed by additional Lattice Boltzmann simulations: a rapid transition of the internal angular velocity prior to rebound to a constant value, as in a tumbling solid body, promotes a rapid rebound of more viscous drops, which are capable to rebound without recoiling. By studying drop impact dynamics, we explore the drop behavior in contactless and frictionless conditions, and identify the Ohnesorge number as the primary parameter to predict the transition between different impact regimes on tilted sublimating slopes, with tumbling observed for Ohnesorge numbers higher than unity.

  2. HIV Patients Drop Out in Indonesia: Associated Factors and Potential Productivity Loss. (United States)

    Siregar, Adiatma Ym; Pitriyan, Pipit; Wisaksana, Rudi


    this study reported various factors associated with a higher probability of HIV patients drop out, and potential productivity loss due to HIV patients drop out. we analyzed data of 658 HIV patients from a database in a main referral hospital in Bandung city, West Java, Indonesia from 2007 to 2013. First, we utilized probit regression analysis and included, among others, the following variables: patients' status (active or drop out), CD4 cell count, TB and opportunistic infection (OI), work status, sex, history of injecting drugs, and support from family and peers. Second, we used the drop out data from our database and CD 4 cell count decline rate from another study to estimate the productivity loss due to HIV patients drop out. lower CD4 cell count was associated with a higher probability of drop out. Support from family/peers, living with family, and diagnosed with TB were associated with lower probability of drop out. The productivity loss at national level due to treatment drop out (consequently, due to CD4 cell count decline) can reach US$365 million (using average wage). first, as lower CD 4 cell count was associated with higher probability of drop out, we recommend (to optimize) early ARV initiation at a higher CD 4 cell count, involving scaling up HIV service at the community level. Second, family/peer support should be further emphasized to further ensure treatment success. Third, dropping out from ART will result in a relatively large productivity loss.

  3. Shrinky-Dink Hanging Drops: A Simple Way to Form and Culture Embryoid Bodies (United States)

    Chen, Chi-Shuo; Pegan, Jonathan; Luna, Jesus; Xia, Bing; McCloskey, Kara; Chin, Wei-chun; Khine, Michelle


    Embryoid bodies (EB) are aggregates of embryonic stem cells. The most common way of creating these aggregates is the hanging drop method, a laborious approach of pipetting an arbitrary number of cells into well plates. The interactions between the stem cells forced into close proximity of one another promotes the generation of the EBs. Because the media in each of the wells has to be manually exchanged every day, this approach is manually intensive. Moreover, because environmental parameters including cell-cell, cell-soluble factor interactions, pH, and oxygen availability can be functions of EB size, cell populations obtained from traditional hanging drops can vary dramatically even when cultured under identical conditions. Recent studies have indeed shown that the initial number of cells forming the aggregate can have significant effects on stem cell differentiation. We have developed a simple, rapid, and scalable culture method to load pre-defined numbers of cells into microfabricated wells and maintain them for embryoid body development. Finally, these cells are easily accessible for further analysis and experimentation. This method is amenable to any lab and requires no dedicated equipment. We demonstrate this method by creating embryoid bodies using a red fluorescent mouse cell line (129S6B6-F1). PMID:19066572

  4. Controls on valley spacing in landscapes subject to rapid base-level fall (United States)

    McGuire, Luke; Pelletier, John D.


    What controls the architecture of drainage networks is a fundamental question in geomorphology. Recent work has elucidated the mechanisms of drainage network development in steadily uplifting landscapes, but the controls on drainage-network morphology in transient landscapes are relatively unknown. In this paper we exploit natural experiments in drainage network development in incised Plio-Quaternary alluvial fan surfaces in order to understand and quantify drainage network development in highly transient landscapes, i.e. initially unincised low-relief surfaces that experience a pulse of rapid base-level drop followed by relative base-level stasis. Parallel drainage networks formed on incised alluvial-fan surfaces tend to have a drainage spacing that is approximately proportional to the magnitude of the base-level drop. Numerical experiments suggest that this observed relationship between the magnitude of base-level drop and mean drainage spacing is the result of feedbacks among the depth of valley incision, mass wasting and nonlinear increases in the rate of colluvial sediment transport with slope gradient on steep valley side slopes that lead to increasingly wide valleys in cases of larger base-level drop. We identify a threshold magnitude of base-level drop above which side slopes lengthen sufficiently to promote increases in contributing area and fluvial incision rates that lead to branching and encourage drainage networks to transition from systems of first-order valleys to systems of higher-order, branching valleys. The headward growth of these branching tributaries prevents the development of adjacent, ephemeral drainages and promotes a higher mean valley spacing relative to cases in which tributaries do not form. Model results offer additional insights into the response of initially unincised landscapes to rapid base-level drop and provide a preliminary basis for understanding how varying amounts of base-level change influence valley network morphology.

  5. Micro-explosion of compound drops (United States)

    Chen, Chun-Kuei; Lin, Ta-Hui


    Introducing water into spray combustion systems, by either water-in-oil emulsification or supplementary water injection, is one of the major techniques for combustion improvement and NOx reduction. Plentiful researches are available on combustion of water-in-oil emulsion fuel drops. The emulsified liquid is a heterogeneous mixture of immiscible liquids. One component forms the continuous phase and the other component forms the discrete phase. The discrete phase consists of globules of the one fluid that are suspended in the continuous phase fluid. Water-in-oil emulsions are commonly considered for combustion applications because emulsions can result in micro-explosion, thereby reducing the average drop diameter to enhance liquid vaporization, and suppressing the formation of soot and NOx. However, the water addition generally does not exceed about 20% for smooth engine operations[!, 21. The combustion characteristics and micro-explosion of emulsion drop were studied by many researchers. The micro-explosion of water in fuel emulsion drops was caused by very fast growth of superheated water vapor bubbles, its superheat limits must be lower than the boiling point temperature of the fuel. These bubbles were primarily governed by the pressure difference between the superheated vapor and the liquid, and by the inertia imparted to the liquid by the motion of the bubble surface[3 6 In this study, we used a coaxial nozzle to generation the multi-component drop. The different type of water-in-oil fuel drops called the compound drops. Unlike an emulsion drop, a compound drop consists of a water core and a fuel shell, which can originate from the phase separation of emulsion[7, 81 or a water drop colliding with a fuel drop[9, 101 Burning and micro-explosion of compound drops have been found to be distinct from those of emulsion drops[9-111 Wang et al.[9 , 101 studied the combustion characteristics of collision merged alkane-water drops. The merged drops appeared in adhesive

  6. Planar Microfluidic Drop Splitting and Merging (United States)

    Collignon, Sean; Friend, James; Yeo, Leslie; MAD-LAB Team


    Open drop microfluidic platforms offer attractive alternatives to closed microchannel devices, however, to be effective they require efficient schemes for planar drop transport and manipulation. While there are many methods that have been reported for drop transport, it is far more difficult to carry out drop operations of dispensing, merging and splitting. In this work, we introduce a novel alternative to merge and split drops using laterally-offset modulated surface acoustic waves (SAWs). To do so, the energy delivery into the drop is modulated to induce drop stretching. Upon removal of the SAW energy, capillary forces at the center of the elongated drop drain the capillary bridge region towards both ends, resulting in its collapse and consequential splitting of the drop. This occurs only below a critical Ohnesorge number, a balance between the viscous forces that retard the drainage and the sufficiently large capillary forces that cause the liquid bridge to pinch. By this scheme we show the possibility of both reliable symettric splitting of a drop with an average deviation in droplet volumes of only around 4%, and no greater than 10%, as well as asymmetric splitting, by tuning the input energy to the device--thus presenting a comparable alternative to electrowetting.

  7. Footprint Geometry and Sessile Drop Resonance (United States)

    Chang, Chun-Ti; Daniel, Susan; Steen, Paul H.


    How does a sessile drop resonate if its footprint is square (square drop)? In this talk, we discuss the two distinct families of observed modes in our experiments. One family (spherical modes) is identified with the natural modes of capillary spherical caps, and the other (grid modes) with Faraday waves on a square bath (square Faraday waves). A square drop exhibits grid or spherical modes depending on its volume, and the two families of modes arise depending on how wavenumber selection of footprint geometry and capillarity compete. For square drops, a dominant effect of footprint constraint leads to grid modes which are constrained response; otherwise the drops exhibit spherical modes, the characteristic of sessile drops on flat plates. Chun-Ti Chang takes his new position at National Taiwan University on Aug. 15th, 2016. Until then, Chun-Ti Chang is affiliated with Technical University Dortmund, Germany.

  8. Large bubble entrainment in drop impact (United States)

    Thoraval, Marie-Jean; Li, Yangfan; Thoroddsen, Sigurdur T.


    A drop impacting on a pool of the same liquid can entrap air bubbles in many different ways. A peculiar entrapment was observed by Pumphrey and Elmore (1990) and remained unexplained until now. For a small range of parameters, the cavity produced by the impacting drop spreads radially in a dish-shape and then closes to entrap a bubble larger than the drop. We demonstrate that the large bubble is caused by a vortex ring produced in the liquid during the impact of the drop. We combine experiments and numerical simulations to show that the vortex ring pulls on the interface on the side of the cavity to stretch it radially, explaining the shape of the cavity. Only prolate drops are able to generate large bubbles. This is due to the self-destruction of the vortex earlier during the impact for flatter drops.

  9. Star-shaped oscillations of Leidenfrost drops (United States)

    Ma, Xiaolei; Liétor-Santos, Juan-José; Burton, Justin C.


    We experimentally investigate the self-sustained, star-shaped oscillations of Leidenfrost drops. The drops levitate on a cushion of evaporated vapor over a heated, curved surface. We observe modes with n =2 -13 lobes around the drop periphery. We find that the wavelength of the oscillations depends only on the capillary length of the liquid and is independent of the drop radius and substrate temperature. However, the number of observed modes depends sensitively on the liquid viscosity. The dominant frequency of pressure variations in the vapor layer is approximately twice the drop oscillation frequency, consistent with a parametric forcing mechanism. Our results show that the star-shaped oscillations are driven by capillary waves of a characteristic wavelength beneath the drop and that the waves are generated by a large shear stress at the liquid-vapor interface.

  10. Drops moving along and across a filament (United States)

    Sahu, Rakesh P.; Sinha-Ray, Suman; Yarin, Alexander; Pourdeyhimi, Behnam


    The present work is devoted to the experimental study of oil drop motion both along and across a filament due to the air jet blowing. In case of drop moving along the filament, phenomena such as drop stick-slip motion, shape oscillations, shedding of a tail along the filament, the tail capillary instability and drop recoil motion were observed which were rationalized in the framework of simplified models. Experiments with cross-flow of the surrounding gas relative to the filament with an oil drop on it were conducted, with air velocity in the range of 7.23 to 22.7 m s-1. The Weber number varied from 2 to 40 and the Ohnesorge number varied from 0.07 to 0.8. The lower and upper critical Weber numbers were introduced to distinguish between the beginning of the drop blowing off the filament and the onset of the bag-stamen breakup. The range of the Weber number between these two critical values is filled with three types of vibrational breakup: V1 (a balloon-like drop being blown off), V2 (a drop on a single stamen being blown off), and V3 (a drop on a double stamen being blown off). The Weber number/Ohnesorge number plane was delineated into domains of different breakup regimes. The work is supported by the Nonwovens Cooperative Research Center (NCRC).

  11. Cooperative breakups induced by drop-to-drop interactions in one-dimensional flows of drops against micro-obstacles. (United States)

    Schmit, Alexandre; Salkin, Louis; Courbin, Laurent; Panizza, Pascal


    Depending on the capillary number at play and the parameters of the flow geometry, a drop may or may not break when colliding with an obstacle in a microdevice. Modeling the flow of one-dimensional trains of monodisperse drops impacting a micro-obstacle, we show numerically that complex dynamics may arise through drop-to-drop hydrodynamic interactions: we observe sequences of breakup events in which the size of the daughter drops created upon breaking mother ones becomes a periodic function of time. We demonstrate the existence of numerous bifurcations between periodic breakup regimes and we establish diagrams mapping the possible breakup dynamics as a function of the governing (physicochemical, hydrodynamic, and geometric) parameters. Microfluidic experiments validate our model as they concur very well with predictions.

  12. Dislodging a sessile drop by a high-Reynolds-number shear flow at subfreezing temperatures. (United States)

    Roisman, Ilia V; Criscione, Antonio; Tropea, Cameron; Mandal, Deepak Kumar; Amirfazli, Alidad


    The drop, exposed to an air flow parallel to the substrate, starts to dislodge when the air velocity reaches some threshold value, which depends on the substrate wetting properties and drop volume. In this study the critical air velocity is measured for different drop volumes, on substrates of various wettabilities. The substrate initial temperatures varied between the normal room temperature (24.5∘C) and subfreezing temperatures (-5∘C and -1∘C). The physics of the drop did not change at the subfreezing temperatures of the substrates, which clearly indicates that the drop does not freeze and remains liquid for a relatively long time. During this time solidification is not initiated, neither by the air flow nor by mechanical disturbances. An approximate theoretical model is proposed that allows estimation of the aerodynamic forces acting on the sessile drop. The model is valid for the case when the drop height is of the same order as the thickness of the viscous boundary in the airflow, but the inertial effects are still dominant. Such a situation, relevant to many practical applications, was never modeled before. The theoretical predictions for the critical velocity of drop dislodging agree well with the experimental data for both room temperature and lower temperatures of the substrates.

  13. Dislodging a sessile drop by a high-Reynolds-number shear flow at subfreezing temperatures (United States)

    Roisman, Ilia V.; Criscione, Antonio; Tropea, Cameron; Mandal, Deepak Kumar; Amirfazli, Alidad


    The drop, exposed to an air flow parallel to the substrate, starts to dislodge when the air velocity reaches some threshold value, which depends on the substrate wetting properties and drop volume. In this study the critical air velocity is measured for different drop volumes, on substrates of various wettabilities. The substrate initial temperatures varied between the normal room temperature (24 .5∘C ) and subfreezing temperatures (-5∘C and -1∘C ). The physics of the drop did not change at the subfreezing temperatures of the substrates, which clearly indicates that the drop does not freeze and remains liquid for a relatively long time. During this time solidification is not initiated, neither by the air flow nor by mechanical disturbances. An approximate theoretical model is proposed that allows estimation of the aerodynamic forces acting on the sessile drop. The model is valid for the case when the drop height is of the same order as the thickness of the viscous boundary in the airflow, but the inertial effects are still dominant. Such a situation, relevant to many practical applications, was never modeled before. The theoretical predictions for the critical velocity of drop dislodging agree well with the experimental data for both room temperature and lower temperatures of the substrates.

  14. The dynamics of drops coating the underside of a flexible wall (United States)

    Richard, Craster; Wray, Alex; Papageorgiou, Demetrios; Matar, Omar


    Lister et al., 2009, showed that a thin fluid coating the underside of a ceiling (a model which extends in particular the works of Hammond, 1983, and Lister et al., 2005) can give rise to pendent drops. If these are fixed in place by boundary conditions, they drain to give drops of constant pressure surrounded by annular trenches. These authors also showed that, on larger domains starting from an initial perturbation, these drops will undergo a self-induced quasi-steady translation. This is driven by the release of gravitational potential energy as the fluid in the film falls into the drop. The speed and growth of these drops is accessible to analytical computation by the self-similar study of the thin trenches surrounding them, and matching to far external conditions. The subsequent dynamics are intricate, allowing for coalescence (not seen in 1 dimension) as well as complex drop-drop interactions. We extend this model to allow for the ceiling to be a flexible substrate, and also to account for inertial effects in the drops. We then investigate the effect this has on the dynamics of the drops. EPSRC DTA.

  15. Monosegment ALPPS: A new variant of the techniques for rapid hepatic regeneration. Critical review of the initial results of our series. (United States)

    Montalvá Orón, Eva María; Maupoey Ibáñez, Javier; Bañuelos Carrillo, Rómulo; Boscà Robledo, Andrea; Orbis Castellanos, Juan Francisco; Moya Herraiz, Ángel; Ballester Vallés, Carmen; Pérez Rojas, Judith; Aparicio Urtasun, Jorge; López-Andújar, Rafael


    Associating Liver Partition and Portal vein ligation for Staged hepatectomy (ALPPS) is a novel surgical technique that provides fast and effective growth of liver remnant volume, allowing surgical resection of hepatic lesions initially considered unresectable. Short and long-term results and the convenience of carrying out this technique are issues that still remain under debate while waiting for the final outcomes of the multicenter registries with larger number of cases. The aim of this paper is to describe, from a critical point of view, the outcomes of the cases performed at our center (n=8). On the other hand, it is possible to leave only one hepatic segment as a liver remnant and we illustrate this new surgical procedure (ALPPS monosegment) performed in one patient. Copyright © 2014 AEC. Publicado por Elsevier España, S.L.U. All rights reserved.

  16. Many Drops Make a Lake

    Directory of Open Access Journals (Sweden)

    Chaitanya S. Mudgal


    greater knowledge, better skills and disseminate this knowledge through this journal to influence as many physicians and their patients as possible. They have taken the knowledge of their teachers, recognized their giants and are now poised to see further than ever before. My grandmother often used to quote to me a proverb from India, which when translated literally means “Many drops make a lake”. I cannot help but be amazed by the striking similarities between the words of Newton and this Indian saying. Therefore, while it may seem intuitive, I think it must be stated that it is vital for the betterment of all our patients that we recognize our own personal lakes to put our drops of knowledge into. More important is that we recognize that it is incumbent upon each and every one of us to contribute to our collective lakes of knowledge such as ABJS. And finally and perhaps most importantly we need to be utterly cognizant of never letting such lakes of knowledge run dry.... ever.

  17. On the spreading of impacting drops

    CERN Document Server

    Wildeman, Sander; Sun, Chao; Lohse, Detlef


    The energy budget and dissipation mechanisms during droplet impact on solid surfaces are studied numerically and theoretically. We find that for high impact velocities and negligible surface friction, about one half of the initial kinetic energy is transformed into surface energy, independent of the impact parameters and the detailed energy loss mechanism(s). We argue that this seemingly universal rule is related to the deformation mode of the droplet and is reminiscent of pipe flow undergoing a sudden expansion, for which the head loss can be calculated by multiplying the kinetic energy of the incoming flow by a geometrical factor. For impacts on a no-slip surface also dissipation in the shear boundary layer at the solid surface is important. In this case the head loss acts as a lower bound on the total dissipation for small viscosities. This new view on the impact problem allows for simple analytical estimates of the maximum spreading diameter of impacting drops as a function of the impact parameters and th...

  18. Head-dropping mechanism in traffic control (United States)

    Liu, Xintong; Yang, Oliver W.


    In this paper, we investigate the application of the head dropping policy as a partial solution to the problem of queue oscillation encountered by RED and its variants. With this method, instead of the tail dropping, which is currently used by RED and many other AQM schemes, the TCP source can be informed of the congestion occurring in the bottleneck router a time period earlier. Specifically, that is a time period of the queuing delay. We have compared DH-RED (drop head RED) and DH-BLUE (drop head BLUE) with the current RED and BLUE in a variety of situations and found that the performances such as the queue size stability as well as packet drop rate can be greatly improved.

  19. Ferrofluid drops in rotating magnetic fields

    CERN Document Server

    Lebedev, A V; Morozov, K I; Bauke, H


    Drops of a ferrofluid floating in a non-magnetic liquid of the same density and spun by a rotating magnetic field are investigated experimentally and theoretically. The parameters for the experiment are chosen such that different stationary drop shapes including non-axis-symmetric configurations could be observed. Within an approximate theoretical analysis the character of the occurring shape bifurcations, the different stationary drop forms, as well as the slow rotational motion of the drop is investigated. The results are in qualitative, and often quantitative agreement, with the experimental findings. It is also shown that a small eccentricity of the rotating field may have a substantial impact on the rotational motion of the drop.

  20. Axisymmetric Drop Shape Analysis (ADSA): An Outline. (United States)

    Saad, Sameh M I; Neumann, A Wilhelm


    Drop shape techniques for the measurement of interfacial tension are powerful, versatile and flexible. The shape of the drop/bubble depends on the balance between surface tension and external forces, e.g. gravity. This balance is reflected mathematically in the Laplace equation of capillarity. Axisymmetric Drop Shape Analysis (ADSA) is a commonly used drop shape technique. A streamlined version of the development of ADSA over the past several decades is presented to illustrate its validity and range of utility. Several configurations of interest will be considered and presented systematically. Shape and surface tension will be linked to a shape parameter based on proper concepts of differential geometry. The resulting shape parameter will be shown to allow determination of the range of applicability of such a drop shape method. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Total sleep time severely drops during adolescence.

    Directory of Open Access Journals (Sweden)

    Damien Leger

    Full Text Available UNLABELLED: Restricted sleep duration among young adults and adolescents has been shown to increase the risk of morbidities such as obesity, diabetes or accidents. However there are few epidemiological studies on normal total sleep time (TST in representative groups of teen-agers which allow to get normative data. PURPOSE: To explore perceived total sleep time on schooldays (TSTS and non schooldays (TSTN and the prevalence of sleep initiating insomnia among a nationally representative sample of teenagers. METHODS: Data from 9,251 children aged 11 to 15 years-old, 50.7% of which were boys, as part of the cross-national study 2011 HBSC were analyzed. Self-completion questionnaires were administered in classrooms. An estimate of TSTS and TSTN (week-ends and vacations was calculated based on specifically designed sleep habits report. Sleep deprivation was estimated by a TSTN - TSTS difference >2 hours. Sleep initiating nsomnia was assessed according to International classification of sleep disorders (ICSD 2. Children who reported sleeping 7 hours or less per night were considered as short sleepers. RESULTS: A serious drop of TST was observed between 11 yo and 15 yo, both during the schooldays (9 hours 26 minutes vs. 7 h 55 min.; p<0.001 and at a lesser extent during week-ends (10 h 17 min. vs. 9 h 44 min.; p<0.001. Sleep deprivation concerned 16.0% of chidren aged of 11 yo vs. 40.5% of those of 15 yo (p<0.001. Too short sleep was reported by 2.6% of the 11 yo vs. 24.6% of the 15 yo (p<0.001. CONCLUSION: Despite the obvious need for sleep in adolescence, TST drastically decreases with age among children from 11 to 15 yo which creates significant sleep debt increasing with age.

  2. Dynamics of sessile and pendant drop excited by surface acoustic waves: gravity effects and correlation between oscillatory and translational motions

    CERN Document Server

    Bussonière, Adrien; Brunet, Philippe; Matar, Olivier Bou


    When sessile droplets are excited by ultrasonic traveling surface acoustic waves (SAWs), they undergo complex dynamics with both oscillations and translational motion. While the nature of the Rayleigh-Lamb quadrupolar drop oscillations has been identified, their origin and their influence on the drop mobility remains unexplained. Indeed the physics behind this peculiar dynamics is complex with nonlinearities involved both at the excitation level (acoustic streaming and radiation pressure) and in the droplet response (nonlinear oscillations and contact line dynamics). In this paper, we investigate the dynamics of sessile and pendant drops excited by SAWs. For pendant drops, so-far unreported dynamics are observed close to the drop detachment threshold with the suppression of the translational motion. Away from this threshold, the comparison between pendant and sessile drop dynamics allows us to identify the role played by gravity or more generally by an initial or dynamically induced stretching of the drop. In...

  3. Kinetic asymmetries between forward and drop jump landing tasks

    Directory of Open Access Journals (Sweden)

    Morgana Alves de Britto


    Full Text Available Landing asymmetry is a risk factor for knee anterior cruciate ligament injury. The aim of this study was to identify kinetic asymmetries in healthy recreational athletes performing different jump-landing techniques. Twelve recreational athletes engaged in regular training underwent kinetic evaluation using two 3D force plates and were analyzed for: (a three-dimensional peak forces, (b time to peak vertical force, and (c initial phase asymmetries. All data were collected during performance of unilateral and bilateral trials of forward and drop jump tasks. Forward jump-landing tasks elicited greater kinetic asymmetry than drop-landing tasks. Regardless of jump-landing technique, the preferred leg experienced higher forces than the non-preferred leg. The initial landing phase showed more kinetic asymmetries than the later phase when peak vertical forces occur. It was concluded that when screening athletes for kinetic asymmetries that may predispose them to injury, forward jump-landing tasks and the early landing phase might show more kinetic asymmetries than drop jump-landing tasks and the late landing phase, respectively.

  4. Kinetic asymmetries between forward and drop jump landing tasks

    Directory of Open Access Journals (Sweden)

    Morgana Alves de Britto


    Full Text Available DOI:   Landing asymmetry is a risk factor for knee anterior cruciate ligament injury. The aim of this study was to identify kinetic asymmetries in healthy recreational athletes performing different jump-landing techniques. Twelve recreational athletes engaged in regular training underwent kinetic evaluation using two 3D force plates and were analyzed for: (a three-dimensional peak forces, (b time to peak vertical force, and (c initial phase asymmetries. All data were collected during performance of unilateral and bilateral trials of forward and drop jump tasks. Forward jump-landing tasks elicited greater kinetic asymmetry than drop-landing tasks. Regardless of jump-landing technique, the preferred leg experienced higher forces than the non-preferred leg. The initial landing phase showed more kinetic asymmetries than the later phase when peak vertical forces occur. It was concluded that when screening athletes for kinetic asymmetries that may predispose them to injury, forward jump-landing tasks and the early landing phase might show more kinetic asymmetries than drop jump-landing tasks and the late landing phase, respectively.

  5. Investigation of drop motion through circular orifices (United States)

    Bordoloi, Ankur; Longmire, Ellen; Kong, Xiangzhao; Saar, Martin


    The motion of drops though porous media occurs in numerous science and engineering fields including multiphase fluid flow in the subsurface during groundwater flow, geothermal energy recovery, and geologic carbon dioxide sequestration. Here, we simplify the porous medium to a thin plate with an orifice to study the interactions between the drop and the solid medium. Drops of water/glycerin with diameter, D, are released in a tank of silicone oil with matched refractive index and allowed to fall downward by gravity. After reaching terminal speed, the drops encounter a thin plate with orifice diameter, d, placed horizontally within the surrounding tank. Drop deformation, contact with the orifice, and breakage are investigated using high-speed imaging, and velocity fields are determined by particle image velocimetry (PIV). Effects of diameter ratio d/D, drop Reynolds number, and drop offset with respect to the orifice center are examined. The experimental results are compared to results from numerical simulations using an immiscible, two-color BGK lattice-Boltzmann method performed under similar test conditions. Supported by DOE (DOE EERE-PMC-10EE0002764).

  6. Staffing Up and Dropping Out

    Directory of Open Access Journals (Sweden)

    Mark Fetler


    Full Text Available Growing public school enrollment and the need to maintain or improve service to students has increased the demand for teachers, perhaps more rapidly than existing sources can accommodate. While some schools recruit well qualified teachers by offering higher salaries or better working conditions, others may satisfy their need for staff by relaxing hiring standards or assigning novice teachers to difficult classrooms. Schools' hiring policies have consequences for student success. Dropout rates tend to be higher where faculties include a greater percentage of minimally educated teachers or teachers with little experience. The relationship between dropout rate and teacher qualifications is independent of student poverty, school size, and location. A proposed strategy to reduce dropout rates is to encourage higher preparation and employment standards, and to provide appropriate classroom assignments, mentoring, and support for new teachers.

  7. "Self-Shaping" of Multicomponent Drops. (United States)

    Cholakova, Diana; Valkova, Zhulieta; Tcholakova, Slavka; Denkov, Nikolai; Smoukov, Stoyan K


    In our recent study we showed that single-component emulsion drops, stabilized by proper surfactants, can spontaneously break symmetry and transform into various polygonal shapes during cooling [ Denkov Nature 2015 , 528 , 392 - 395 ]. This process involves the formation of a plastic rotator phase of self-assembled oil molecules beneath the drop surface. The plastic phase spontaneously forms a frame of plastic rods at the oil drop perimeter which supports the polygonal shapes. However, most of the common substances used in industry appear as mixtures of molecules rather than pure substances. Here we present a systematic study of the ability of multicomponent emulsion drops to deform upon cooling. The observed trends can be summarized as follows: (1) The general drop-shape evolution for multicomponent drops during cooling is the same as with single-component drops; however, some additional shapes are observed. (2) Preservation of the particle shape upon freezing is possible for alkane mixtures with chain length difference Δn ≤ 4; for greater Δn, phase separation within the droplet is observed. (3) Multicomponent particles prepared from alkanes with Δn ≤ 4 plastify upon cooling due to the formation of a bulk rotator phase within the particles. (4) If a compound, which cannot induce self-shaping when pure, is mixed with a certain amount of a compound which induces self-shaping, then drops prepared from this mixture can also self-shape upon cooling. (5) Self-emulsification phenomena are also observed for multicomponent drops. In addition to the three recently reported mechanisms of self-emulsification [ Tcholakova Nat. Commun. 2017 , ( 8 ), 15012 ], a new (fourth) mechanism is observed upon freezing for alkane mixtures with Δn > 4. It involves disintegration of the particles due to a phase separation of alkanes upon freezing.

  8. The Evaporation of Liquid Micro-Drops on the Heated Substrate

    Directory of Open Access Journals (Sweden)

    Semenov Andrey


    Full Text Available Evaporation of a heated sessile water micro-drop was studied experimentally at the substrate temperature and surrounding atmosphere from 30 to 50 °C. The studies were performed on the float glass substrate with aluminum nanocoating of optical quality. The research has shown that the specific rate of evaporation (mass loss per unit of the drop surface area increases with the decrease in droplet volume and at the last stage several times exceeds the initial value.

  9. Blood drop patterns: Formation and applications. (United States)

    Chen, Ruoyang; Zhang, Liyuan; Zang, Duyang; Shen, Wei


    The drying of a drop of blood or plasma on a solid substrate leads to the formation of interesting and complex patterns. Inter- and intra-cellular and macromolecular interactions in the drying plasma or blood drop are responsible for the final morphologies of the dried patterns. Changes in these cellular and macromolecular components in blood caused by diseases have been suspected to cause changes in the dried drop patterns of plasma and whole blood, which could be used as simple diagnostic tools to identify the health of humans and livestock. However, complex physicochemical driving forces involved in the pattern formation are not fully understood. This review focuses on the scientific development in microscopic observations and pattern interpretation of dried plasma and whole blood samples, as well as the diagnostic applications of pattern analysis. Dried drop patterns of plasma consist of intricate visible cracks in the outer region and fine structures in the central region, which are mainly influenced by the presence and concentration of inorganic salts and proteins during drying. The shrinkage of macromolecular gel and its adhesion to the substrate surface have been thought to be responsible for the formation of the cracks. Dried drop patterns of whole blood have three characteristic zones; their formation as functions of drying time has been reported in the literature. Some research works have applied engineering treatment to the evaporation process of whole blood samples. The sensitivities of the resultant patterns to the relative humidity of the environment, the wettability of the substrates, and the size of the drop have been reported. These research works shed light on the mechanisms of spreading, evaporation, gelation, and crack formation of the blood drops on solid substrates, as well as on the potential applications of dried drop patterns of plasma and whole blood in diagnosis. Crown Copyright © 2016. Published by Elsevier B.V. All rights reserved.

  10. Integrity Evaluation of Control Rod Assembly for Sodium-Cooled Fast Reactor due to Drop Impact

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyun Seung; Yoon, Kyung Ho; Kim, Hyung Kyu; Cheon, Jin Sik; Lee, Chan Bock [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)


    The CA (Control Assembly) of an SFR has a CRA(Control Rod Assembly) with an inner duct and control rod. During an emergency situation, the CRA falls into the duct of the CA for a rapid shut-down. The drop time and impact velocity of the CRA are important parameters with respect to the reactivity insertion time and the structural integrity of the CRA. The objective of this study was to investigate the dynamic behavior and integrity of the CRA owing to a drop impact. The impact analysis of the CRA under normal/abnormal drop conditions was carried out using the commercial FEM code LS-DYNA. Results of the drop impact analysis demonstrated that the CRA maintained structural integrity, and could be safely inserted into the flow hole of the damper under abnormal conditions.

  11. The Rapid Field Initiative Business Analysis

    National Research Council Canada - National Science Library

    Goerger, Simon R; Crino, Scott T; McCarthy, Daniel J; Griffin, Gregory


    .... It is a process that costs the Army time money and a great deal of effort to execute. This case study examines the RFI supply chain and makes recommendations to improve the current inventory management system (IMS...

  12. The Drop Tower Bremen -Experiment Operation (United States)

    Könemann, Thorben; von Kampen, Peter; Rath, Hans J.

    The idea behind the drop tower facility of the Center of Applied Space Technology and Micro-gravity (ZARM) in Bremen is to provide an inimitable technical opportunity of a daily access to short-term weightlessness on earth. In this way ZARM`s european unique ground-based microgravity laboratory displays an excellent economic alternative for research in space-related conditions at low costs comparable to orbital platforms. Many national and international ex-perimentalists motivated by these prospects decide to benefit from the high-quality and easy accessible microgravity environment only provided by the Drop Tower Bremen. Corresponding experiments in reduced gravity could open new perspectives of investigation methods and give scientists an impressive potential for a future technology and multidisciplinary applications on different research fields like Fundamental Physics, Astrophysics, Fluid Dynamics, Combus-tion, Material Science, Chemistry and Biology. Generally, realizing microgravity experiments at ZARM`s drop tower facility meet new requirements of the experimental hardware and may lead to some technical constraints in the setups. In any case the ZARM Drop Tower Operation and Service Company (ZARM FAB mbH) maintaining the drop tower facility is prepared to as-sist experimentalists by offering own air-conditioned laboratories, clean rooms, workshops and consulting engineers, as well as scientific personal. Furthermore, ZARM`s on-site apartment can be used for accommodations during the experiment campaigns. In terms of approaching drop tower experimenting, consulting of experimentalists is mandatory to successfully accomplish the pursued drop or catapult capsule experiment. For this purpose there will be a lot of expertise and help given by ZARM FAB mbH in strong cooperation to-gether with the experimentalists. However, in comparison to standard laboratory setups the drop or catapult capsule setup seems to be completely different at first view. While defining a

  13. Viscous Effect of Drop Impacting on Liquid Film (United States)

    Tang, Xiaoyu; Saha, Abhishek; Law, Chung K.; Sun, Chao


    Drop impacting a liquid film is commonly observed in many processes including inkjet printing and thermal sprays. The accumulation and growth of the film depend on the outcome of subsequent drop impact on the initially formed film. In our recent study (Tang, et al. Soft Matter 2016), we have proposed a regime diagram based on the Weber number We (ratio of impact inertia and surface tension) and the film thickness, characterizing non-monotonic transitions between the bouncing and merging outcomes and providing scaling analysis for the boundaries for a single liquid (n-tetradecane). Since liquid viscosity fundamentally affects the impact outcome, through its influence on the flow field and dissipation of the kinetic energy, here we extend the study for a number of alkanes and silicone oils, covering a wide range of viscosity, to evaluate its effect on the regime diagram. We will show that while the regime diagram maintains its general structure, the merging regime becomes smaller for more viscous liquids and eventually the non-monotonicity disappears. We will model the viscous effects and present a modified scaling. This new scaling attempts to unify all liquids and provides a useful tool to manipulate the outcome of drop impact on liquid film. The work at Princeton University is supported by the Army Research Office and the Xerox Corporation.

  14. [Optimize dropping process of Ginkgo biloba dropping pills by using design space approach]. (United States)

    Shen, Ji-Chen; Wang, Qing-Qing; Chen, An; Pan, Fang-Lai; Gong, Xing-Chu; Qu, Hai-Bin


    In this paper, a design space approach was applied to optimize the dropping process of Ginkgo biloba dropping pills. Firstly, potential critical process parameters and potential process critical quality attributes were determined through literature research and pre-experiments. Secondly, experiments were carried out according to Box-Behnken design. Then the critical process parameters and critical quality attributes were determined based on the experimental results. Thirdly, second-order polynomial models were used to describe the quantitative relationships between critical process parameters and critical quality attributes. Finally, a probability-based design space was calculated and verified. The verification results showed that efficient production of Ginkgo biloba dropping pills can be guaranteed by operating within the design space parameters. The recommended operation ranges for the critical dropping process parameters of Ginkgo biloba dropping pills were as follows: dropping distance of 5.5-6.7 cm, and dropping speed of 59-60 drops per minute, providing a reference for industrial production of Ginkgo biloba dropping pills. Copyright© by the Chinese Pharmaceutical Association.

  15. Dropping out of School among ELL Students: Implications to Schools and Teacher Education (United States)

    Sheng, Zhaohui; Sheng, Yanyan; Anderson, Christine J.


    English language learners (ELLs) are the most rapidly growing student population in U.S. elementary and secondary schools, and this growth rate will continue throughout the next few decades. Indirect evidence has suggested that the youth population that grows the fastest has the highest risk of dropping out of school. This article reviews the…

  16. Cavity optomechanics in a levitated helium drop (United States)

    Childress, L.; Schmidt, M. P.; Kashkanova, A. D.; Brown, C. D.; Harris, G. I.; Aiello, A.; Marquardt, F.; Harris, J. G. E.


    We describe a proposal for a type of optomechanical system based on a drop of liquid helium that is magnetically levitated in vacuum. In the proposed device, the drop would serve three roles: its optical whispering-gallery modes would provide the optical cavity, its surface vibrations would constitute the mechanical element, and evaporation of He atoms from its surface would provide continuous refrigeration. We analyze the feasibility of such a system in light of previous experimental demonstrations of its essential components: magnetic levitation of mm-scale and cm-scale drops of liquid He , evaporative cooling of He droplets in vacuum, and coupling to high-quality optical whispering-gallery modes in a wide range of liquids. We find that the combination of these features could result in a device that approaches the single-photon strong-coupling regime, due to the high optical quality factors attainable at low temperatures. Moreover, the system offers a unique opportunity to use optical techniques to study the motion of a superfluid that is freely levitating in vacuum (in the case of 4He). Alternatively, for a normal fluid drop of 3He, we propose to exploit the coupling between the drop's rotations and vibrations to perform quantum nondemolition measurements of angular momentum.

  17. Drop Testing Representative Multi-Canister Overpacks

    Energy Technology Data Exchange (ETDEWEB)

    Snow, Spencer D. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Morton, Dana K. [Idaho National Lab. (INL), Idaho Falls, ID (United States)


    The objective of the work reported herein was to determine the ability of the Multi- Canister Overpack (MCO) canister design to maintain its containment boundary after an accidental drop event. Two test MCO canisters were assembled at Hanford, prepared for testing at the Idaho National Engineering and Environmental Laboratory (INEEL), drop tested at Sandia National Laboratories, and evaluated back at the INEEL. In addition to the actual testing efforts, finite element plastic analysis techniques were used to make both pre-test and post-test predictions of the test MCOs structural deformations. The completed effort has demonstrated that the canister design is capable of maintaining a 50 psig pressure boundary after drop testing. Based on helium leak testing methods, one test MCO was determined to have a leakage rate not greater than 1x10-5 std cc/sec (prior internal helium presence prevented a more rigorous test) and the remaining test MCO had a measured leakage rate less than 1x10-7 std cc/sec (i.e., a leaktight containment) after the drop test. The effort has also demonstrated the capability of finite element methods using plastic analysis techniques to accurately predict the structural deformations of canisters subjected to an accidental drop event.

  18. Drop impact on inclined superhydrophobic surfaces (United States)

    Choi, Wonjae; Leclear, Sani; Leclear, Johnathon; Abhijeet, .; Park, Kyoo-Chul

    We report an empirical study and dimensional analysis on the impact patterns of water drops on inclined superhydrophobic surfaces. While the classic Weber number determines the spreading and recoiling dynamics of a water drop on a horizontal / smooth surface, for a superhydrophobic surface, the dynamics depends on two distinct Weber numbers, each calculated using the length scale of the drop or of the pores on the surface. Impact on an inclined superhydrophobic surface is even more complicated, as the velocity that determines the Weber number is not necessarily the absolute speed of the drop but the velocity components normal and tangential to the surface. We define six different Weber numbers, using three different velocities (absolute, normal and tangential velocities) and two different length scales (size of the drop and of the texture). We investigate the impact patterns on inclined superhydrophobic surfaces with three different types of surface texture: (i) posts, (ii) ridges aligned with and (iii) ridges perpendicular to the impact direction. Results suggest that all six Weber numbers matter, but affect different parts of the impact dynamics, ranging from the Cassie-Wenzel transition, maximum spreading, to anisotropic deformation. We acknowledge financial support from the Office of Naval Research (ONR) through Contract 3002453812.

  19. Drop impact on spherical soft surfaces (United States)

    Chen, Simeng; Bertola, Volfango


    The impact of water drops on spherical soft surfaces is investigated experimentally through high-speed imaging. The effect of a convex compliant surface on the dynamics of impacting drops is relevant to various applications, such as 3D ink-jet printing, where drops of fresh material impact on partially cured soft substrates with arbitrary shape. Several quantities which characterize the morphology of impacting drops are measured through image-processing, including the maximum and minimum spreading angles, length of the wetted curve, and dynamic contact angle. In particular, the dynamic contact angle is measured using a novel digital image-processing scheme based on a goniometric mask, which does not require edge fitting. It is shown that the surface with a higher curvature enhances the retraction of the spreading drop; this effect may be due to the difference of energy dissipation induced by the curvature of the surface. In addition, the impact parameters (elastic modulus, diameter ratio, and Weber number) are observed to significantly affect the dynamic contact angle during impact. A quantitative estimation of the deformation energy shows that it is significantly smaller than viscous dissipation.

  20. Surface characterization through shape oscillations of drops in microgravity and 1-g (United States)

    Apfel, Robert E.; Holt, R. Glynn; Tian, Yuren; Shi, Tao; Zheng, Xiao-Yu


    The goal of these experiments is to determine the rheological properties of liquid drops of single or multiple components in the presence or absence of surface active materials by exciting drops into their quadrupole resonance and observing their free decay. The resulting data coupled with appropriate theory should give a better description of the physics of the underlying phenomena, providing a better foundation than earlier empirical results could. The space environment makes an idealized geometry available (spherical drops) so that theory and experiment can be properly compared, and allows a 'clean' environment, by which is meant an environment in which no solid surfaces come in contact with the drops during the test period. Moreover, by considering the oscillations of intentionally deformed drops in microgravity, a baseline is established for interpreting surface characterization experiments done on the ground by other groups and ours. Experiments performed on the United States Microgravity Laboratory Laboratory (USML-1) demonstrated that shape oscillation experiments could be performed over a wide parameter range, and with a variety of surfactant materials. Results, however, were compromised by an unexpected, slow drop tumbling, some problems with droplet injection, and the presence of bubbles in the drop samples. Nevertheless, initial data suggests that the space environment will be useful in providing baseline data that can serve to validate theory and permit quantitative materials characterization at 1-g.

  1. Self-Propulsion and Shape Restoration of Aqueous Drops on Sulfobetaine Silane Surfaces. (United States)

    Singh, Vickramjeet; Wu, Cyuan-Jhang; Sheng, Yu-Jane; Tsao, Heng-Kwong


    The motion of droplets on typical surfaces is generally halted by contact line pinning associated with contact angle hysteresis. In this study, it was shown that, on a zwitterionic sulfobetaine silane (SBSi)-coated surface, aqueous drops with appropriate solutes can demonstrate hysteresis-free behavior, whereas a pure water drop shows spontaneous spreading. By adding solutes such as polyethylene glycol, 2(2-butoxy ethoxy) ethanol, or sodium n-dodecyl sulfate, an aqueous drop with a small contact angle (disappearance of spontaneous spreading) was formed on SBSi surfaces. The initial drop shape was readily relaxed back to a circular shape (hysteresis-free behavior), even upon severe disturbances. Moreover, it was interesting to observe the self-propulsion of such a drop on horizontal SBSi surfaces in the absence of externally provided stimuli. The self-propelled drop tends to follow a random trajectory, and the continuous movement can last for at least 10 min. This self-propelled random motion can be attributed to the combined effects of the hysteresis-free surface and the Marangoni stress. The former comes from the total wetting property of the surface, while the latter originates from surface tension gradient due to fluctuating evaporation rates along the drop border.

  2. Nonreciprocal photonic crystal add-drop filter

    Energy Technology Data Exchange (ETDEWEB)

    Tao, Keyu [THz Technical Research Center of Shenzhen University, Shenzhen 518067 (China); Shenzhen Key Laboratory of Micro-Nano Photonic Information Technology, Shenzhen 518067 (China); College of Electronic Science and Technology, Shenzhen University, Shenzhen 518067 (China); Department of Mechanical Engineering, University of Colorado Boulder, Boulder, Colorado 80309 (United States); Xiao, Jun-Jun [College of Electronic and Information Engineering, Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen 518055 (China); Yin, Xiaobo, E-mail: Xiaobo.Yin@Colorado.Edu [Department of Mechanical Engineering, University of Colorado Boulder, Boulder, Colorado 80309 (United States); Materials Science and Engineering Program, University of Colorado Boulder, Boulder, Colorado 80309 (United States)


    We present a versatile add-drop integrated photonic filter (ADF) consisting of nonreciprocal waveguides in which the propagation of light is restricted in one predetermined direction. With the bus and add/drop waveguides symmetrically coupled through a cavity, the four-port device allows each individual port to add and/or drop a signal of the same frequency. The scheme is general and we demonstrate the nonreciprocal ADF with magneto-optical photonic crystals. The filter is immune to waveguide defects, allowing straightforward implementation of multi-channel ADFs by cascading the four-port designs. The results should find applications in wavelength-division multiplexing and related integrated photonic techniques.

  3. Drop impact on porous superhydrophobic polymer surfaces. (United States)

    Rioboo, R; Voué, M; Vaillant, A; De Coninck, J


    Water drop impacts are performed on porous-like superhydrophobic surfaces. We investigate the influence of the drop size and of the impact velocity on the event. The Cassie-Baxter/Wenzel transition is observed to be a function of the drop size, as well as the outcomes of the impact or deposition process, which can be deposition, rebound, sticking, or fragmentation. A quantitative analysis on the experimental conditions required to observe rebound is provided. Our analysis shows that the wettability hysteresis controls the limit between deposition and rebound events. This limit corresponds to a constant Weber number. A survey of literature results on impact over patterned superhydrophobic surfaces is provided as a comparison.

  4. Liquid toroidal drop under uniform electric field (United States)

    Zabarankin, Michael


    The problem of a stationary liquid toroidal drop freely suspended in another fluid and subjected to an electric field uniform at infinity is addressed analytically. Taylor's discriminating function implies that, when the phases have equal viscosities and are assumed to be slightly conducting (leaky dielectrics), a spherical drop is stationary when Q=(2R2+3R+2)/(7R2), where R and Q are ratios of the phases' electric conductivities and dielectric constants, respectively. This condition holds for any electric capillary number, CaE, that defines the ratio of electric stress to surface tension. Pairam and Fernández-Nieves showed experimentally that, in the absence of external forces (CaE=0), a toroidal drop shrinks towards its centre, and, consequently, the drop can be stationary only for some CaE>0. This work finds Q and CaE such that, under the presence of an electric field and with equal viscosities of the phases, a toroidal drop having major radius ρ and volume 4π/3 is qualitatively stationary-the normal velocity of the drop's interface is minute and the interface coincides visually with a streamline. The found Q and CaE depend on R and ρ, and for large ρ, e.g. ρ≥3, they have simple approximations: Q˜(R2+R+1)/(3R2) and CaE∼3 √{3 π ρ / 2 } (6 ln ⁡ρ +2 ln ⁡[96 π ]-9 )/ (12 ln ⁡ρ +4 ln ⁡[96 π ]-17 ) (R+1 ) 2/ (R-1 ) 2.

  5. Water Drops Dancing on Ice: How Sublimation Leads to Drop Rebound (United States)

    Antonini, C.; Bernagozzi, I.; Jung, S.; Poulikakos, D.; Marengo, M.


    Drop rebound is a spectacular event that appears after impact on hydrophobic or superhydrophobic surfaces but can also be induced through the so-called Leidenfrost effect. Here we demonstrate that drop rebound can also originate from another physical phenomenon, the solid substrate sublimation. Through drop impact experiments on a superhydrophobic surfaces, a hot plate, and solid carbon dioxide (commonly known as dry ice), we compare drop rebound based on three different physical mechanisms, which apparently share nothing in common (superhydrophobicity, evaporation, and sublimation), but lead to the same rebound phenomenon in an extremely wide temperature range, from 300°C down to even below -79°C. The formation and unprecedented visualization of an air vortex ring around an impacting drop are also reported.

  6. Internal flow and deformation of a liquid CO2 drop rising through water (United States)

    Steytler, Louis L.; Pearlstein, Arne J.


    We report computations of the steady axisymmetric flow in and around a deformable liquid drop of CO2 ascending through a water column under the action of buoyancy, a problem relevant to risk assessment for sub-seabed carbon sequestration and storage. In these initial computations, we consider several drop densities, corresponding to different depths in the ocean, and neglect dissolution of CO2 into the surrounding water and formation of a hydrate film at the drop/water interface. The results, which extend our previous work (Bozzi et al., J. Fluid Mech. 336, 1-32, 1997) to the case in which the dynamic viscosities of the dispersed and continuous phases are unequal, show that the degree of deformation and internal circulation depend strongly on drop size. Supported by the International Institute for Carbon-Neutral Energy Research, sponsored by the Japanese Ministry of Education, Culture, Sports, Science and Technology.

  7. Transformation of the bridge during drop separation (United States)

    Chashechkin, Yu. D.; Prokhorov, V. E.


    The geometry of flows during separation of pendant drops of liquids with significantly different physical properties (alcohol, water, glycerin, oil) has been studied by high-speed video recording. The dynamics of the processes involving the formation of bridges of two characteristic shapes—slightly nonuniform in thickness and with thinning of the upper and lower ends—has been investigated. It has been shown that the shape change of the separated bridge has a number of stages determined by the properties of the liquid. As a result, the bridge is transformed into a small drop—a satellite drop.

  8. Shuttlecock Velocity of a Badminton Drop Shot

    Directory of Open Access Journals (Sweden)

    Ampharin Ongvises


    Full Text Available In a badminton ‘drop shot’, the shuttlecock is struck by a non-rotating racquet at low speed. In this investigation, a shuttlecock was hit by a badminton racquet in a linear collision, simulating a drop shot. The collision was recorded with high-speed video and the velocities of the racquet and shuttlecock determined. The relationship between the impact velocity of the racquet and the velocity of the shuttlecock as it leaves the badminton racquet after collision was found to be proportional over the range tested.

  9. Shuttlecock Velocity of a Badminton Drop Shot

    Directory of Open Access Journals (Sweden)

    Ampharin Ongvises


    Full Text Available In a badminton ‘drop shot’, the shuttlecock is struck by a non-rotating racquet at low speed. In this investigation, a shuttlecock was hit by a badminton racquet in a linear collision, simulating a drop shot. The collision was recorded with high-speed video and the velocities of the racquet and shuttlecock determined. The relationship between the impact velocity of the racquet and the velocity of the shuttlecock as it leaves the badminton racquet after collision was found to be proportional over the range tested.

  10. Drop Impact on Oblique Superhydrophobic Surfaces with Two-Tier Roughness. (United States)

    Zhang, Rui; Hao, Pengfei; He, Feng


    This paper investigates the complex physical phenomenon of oblique drop impact on superhydrophobic substrates with two-tier roughness (patterned with varied submillimeter-scale posts and coated with nanoparticles). Experimental results show that the impact Weber number of drops and the solid fraction of the submillimeter-scale post structures are crucial for the outcomes of oblique drop collisions. Water droplets with 10 surface solid fraction decreases, four possible bouncing patterns occur in sequence: sliding rebound, stretched rebound, penetration rebound, and breakup rebound. We demonstrate that the stretched rebound, in which the drops bounce off the surface rapidly in an elongated shape without tangential retraction, allows a 10%∼30% reduction of contact time compared with conventional sliding rebound on oblique surfaces. Three types of stretched rebound are observed on substrates with moderate solid fraction (0.1 patterns. These findings are believed to provide valuable guidance to the design of self-cleaning and anti-icing surfaces under oblique liquid impacts where rapid drop shedding is profitable.

  11. Reduction in drop size of ophthalmic topical drop preparations and the impact of treatment

    Directory of Open Access Journals (Sweden)

    Shiva Kumar


    Full Text Available In this work we devised a method to create smaller eye drops of the glaucoma medication timolol maleate by altering the dropper tip design and changing the physical properties of the formulation. Most ocular diseases are treated with topical application of eye drops. After instillation of an eye drop, typically, less than 5% of the applied drug penetrates the cornea and reaches the intraocular tissues; the major fraction of the instilled drug is absorbed and enters the systemic circulation. Ophthalmic solutions are available in multidose or single-dose glass/plastic dropper bottles that deliver drops with a volume that ranges from 25 μL to 70 μL (average 40 μL. Because of the low capacity of the precorneal area, the optimal drop volume is about 20 μL; with larger volumes there is the risk of adverse systemic effects due to absorption of the drug via the nasal mucosa. Thus, both from the biopharmaceutical and economic point of view, drops of only 5-15 mL volume should be instilled into the eye. In this present work we devised a method to reduce the size of the drop by inserting a glass capillary tube into the dropper tip and by changing the physical properties of the formulation (by altering the concentration of Tween 80™, i.e., 0.05% and 0.1% of Tween 80™. We measured the drop sizes of the different timolol eye drop formulations available in the market and estimated the yearly cost of the medications. Our timolol maleate formulation with 0.1% concentration of Tween 80™ delivered through the dropper tip with the inserted glass capillary was shown to be better than the other formulations available in the market in terms of ability to deliver smaller drops, meaning that each bottle would last longer and that the yearly cost of treatment would be lower.

  12. Dropped head congenital muscular dystrophy caused by de novo mutations in LMNA. (United States)

    Karaoglu, Pakize; Quizon, Nicolas; Pergande, Matthias; Wang, Haicui; Polat, Ayşe Ipek; Ersen, Ayca; Özer, Erdener; Willkomm, Lena; Hiz Kurul, Semra; Heredia, Raúl; Yis, Uluç; Selcen, Duygu; Çirak, Sebahattin


    Dropped head syndrome is an easily recognizable clinical presentation of Lamin A/C-related congenital muscular dystrophy. Patients usually present in the first year of life with profound neck muscle weakness, dropped head, and elevated serum creatine kinase. Two patients exhibited head drop during infancy although they were able to sit independently. Later they developed progressive axial and limb-girdle weakness. Creatine kinase levels were elevated and muscle biopsies of both patients showed severe dystrophic changes. The distinctive clinical hallmark of the dropped head led us to the diagnosis of Lamin A/C-related congenital muscular dystrophy, with a pathogenic de novo mutation p.Glu31del in the head domain of the Lamin A/C gene in both patients. Remarkably, one patient also had a central involvement with white matter changes on brain magnetic resonance imaging. Lamin A/C-related dropped-head syndrome is a rapidly progressive congenital muscular dystrophy and may lead to loss of ambulation, respiratory insufficiency, and cardiac complications. Thus, the genetic diagnosis of dropped-head syndrome as L-CMD and the implicated clinical care protocols are of vital importance for these patients. This disease may be underdiagnosed, as only a few genetically confirmed cases have been reported. Copyright © 2016 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.

  13. Drop spreading and penetration into pre-wetted powders

    KAUST Repository

    Marston, Jeremy


    We present results from an experimental study of the impact of liquid drops onto powder beds which are pre-wetted with the impacting liquid. Using high-speed video imaging, we study both the dynamics of the initial spreading regime and drainage times once the drop has reached its maximum spread on the surface. During the initial spreading stage, we compare our experimental data to a previously developed model which incorporates imbibition into the spreading dynamics and observe reasonable agreement. We find that the maximum spread is a strong function of the moisture content in the powder bed and that the total time from impact to complete drainage is always shorter than that for dry powder. Our results indicate that there is an optimum moisture content (or saturation) which leads to the fastest penetration. We use simple scaling arguments which also identify an optimum moisture content for fastest penetration, which agrees very well with the experimental result. © 2013 Elsevier B.V.

  14. Pleural "drop metastases" 21 years after resection of a thymoma. (United States)

    Chiang, Chia-Chun; Parsons, Angela M; Kriegshauser, J Scott; Paripati, Harshita R; Zarka, Matthew A; Leis, A Arturo


    We describe an unusual case of pleural drop metastases 21 years after complete resection of an encapsulated thymoma in a Southeast Asian patient with myasthenia gravis (MG). This investigation includes a case report and brief review of the literature. The patient presented in 2015 with generalized weakness, fatigue, and shortness of breath, but no diplopia, ptosis, dysphagia, or dysarthria. Because these symptoms were atypical for an MG exacerbation, a de-novo work-up was performed. Chest computed tomography (CT) showed numerous pleural nodules ("drop metastases"), and CT-guided biopsy revealed metastatic thymoma. The average disease-free interval for thymoma ranges from 68 to 86 months. Pleural and mediastinal recurrence are more common than distant hematogenous recurrence. Adverse prognostic factors include an initial higher Masaoka stage, incomplete resection, older age, and pleural or pericardial involvement. Despite apparent complete resection of thymoma, clinicians should remain vigilant for recurrence for as long as 20 years after initial management. Long-term follow-up with radiologic surveillance is recommended. Muscle Nerve 56: 171-175, 2017. © 2016 Wiley Periodicals, Inc.

  15. Modeling merging behavior at lane drops. (United States)


    In work-zone configurations where lane drops are present, merging of traffic at the taper presents an operational concern. In : addition, as flow through the work zone is reduced, the relative traffic safety of the work zone is also reduced. Improvin...

  16. 49 CFR 178.603 - Drop test. (United States)


    ... of anti-freeze. Water/anti-freeze solutions with a minimum specific gravity of 0.95 for testing at... than flat drops, the center of gravity of the test packaging must be vertically over the point of... is performed with water: (i) Where the materials to be carried have a specific gravity not exceeding...

  17. Goose droppings as food for reindeer

    NARCIS (Netherlands)

    van der Wal, R; Loonen, MJJE

    Feeding conditions for Svalbard reindeer, Rangifer tarandus platyrhynchus, on Spitsbergen are generally poor, owing to low availability of forage. We report on coprophagy: the use of goose faeces as an alternative food source for reindeer. Fresh droppings from Barnacle Geese, Branta leucopsis,


    African Journals Online (AJOL)


    ABSTRACT. A study of inorganic complexation of lead using drop amalgam voltammetry is described. The study has been carried out in simulated salt lake water and at ionic strength of. 7.35 M, the predetermined ionic strength of Lake Katwe. The complexation of lead with the simple ligands (Cl-, CO3. 2-) created anodic ...

  19. Spontaneous evaporation of the acetone drop (United States)

    Dunin, S. Z.; Nagornov, O. V.


    The exact solution of the problem on evaporation of the acetone sessile drop at solid substrate is derived. The solution allows us to analyze the temperature field behavior at various thermodynamic parameters. The Marangoni forces are calculated in explicit form. The solution can be used to check numerical approaches for similar problems.

  20. An evaporation model of multicomponent solution drops (United States)

    Sartori, Silvana; Liñán, Amable; Lasheras, Juan C.


    Solutions of polymers are widely used in the pharmaceutical industry as tablets coatings. These allow controlling the rate at which the drug is delivered, taste or appearance. The coating is performed by spraying and drying the tablets at moderate temperatures. The wetting of the coating solution on the pill's surface depends on the droplet Webber and Re numbers, angle of impact and on the rheological properties of the droplet. We present a model for the evaporation of multicomponent solutions droplets in a hot air environment with temperatures substantially lower than the boiling temperature of the solvent. As the liquid vaporizes from the surface the fluid in the drop increases in concentration, until reaching its saturation point. After saturation, precipitation occurs uniformly within the drop. As the surface regresses, a compacting front formed by the precipitate at its maximum packing density advances into the drop, while the solute continues precipitating uniformly. This porous shell grows fast due to the double effect of surface regression and precipitation. The evaporation rate is determined by the rates at which heat is transported to the droplet surface and at which liquid vapor diffuses away from it. When the drop is fully compacted, the evaporation is drastically reduced.

  1. Utah Drop-Out Drug Use Questionnaire. (United States)

    Governor's Citizen Advisory Committee on Drugs, Salt Lake City, UT.

    This questionnaire assesses drug use practices in high school drop-outs. The 79 items (multiple choice or apply/not apply) are concerned with demographic data and use, use history, reasons for use/nonuse, attitudes toward drugs, availability of drugs, and drug information with respect to narcotics, amphetamines, LSD, Marijuana, and barbiturates.…

  2. 49 CFR 178.965 - Drop test. (United States)


    ... Large Packaging design types and performed periodically as specified in § 178.955(e) of this subpart. (b...) Conditioning. Rigid plastic Large Packagings and Large Packagings with plastic inner receptacles must be... § 178.960(d). (d) Test method. (1) Samples of all Large Packaging design types must be dropped onto a...

  3. 49 CFR 178.810 - Drop test. (United States)


    ..., DEPARTMENT OF TRANSPORTATION HAZARDOUS MATERIALS REGULATIONS SPECIFICATIONS FOR PACKAGINGS Testing of IBCs... design types and performed periodically as specified in § 178.801(e) of this subpart. (b) Special preparation for the drop test. (1) Metal, rigid plastic, and composite IBCs intended to contain solids must be...

  4. Check valves with drop-shaped disk

    Energy Technology Data Exchange (ETDEWEB)


    This report discusses improvements possible with drop check valves. Up to the time of the report, the most important improvements had been: (1) lightening of the drop by hollowing it out, (2) reducing lift to reduce impact, (3) increasing clearance in the guide to minimize the danger of it getting stuck, (4) drilling of a safety hole which would indicate excessive wear of the housing by a leak. Other possibilities for the above improvements had produced the following conclusions: (1) a further lightening of the drop was found possible by milling out the halves with a milling cutter, by welding them together and thus eliminating the threaded portion, or by having the drop open on the bottom; (2) further reduction in lift was not found possible in most sizes, but for reduction of the impact effect by a cushion of oil or paste, the seating surface was widened as much as possible; (3) sticking of certain check valves caused by ferrous sulfide deposits could be solved by use of a certain bushing in the housing; (4) some plants favored and some disfavored the safety hole, but in general, plants were to service check valves and change them at such regular intervals as experience dictated; (5) the seat plate was no longer solid steel, but a welded piece.

  5. Lightweight, Economical Device Alleviates Drop Foot (United States)

    Deis, B. C.


    Corrective apparatus alleviates difficulties in walking for victims of drop foot. Elastic line attached to legband provides flexible support to toe of shoe. Device used with flat (heelless) shoes, sneakers, crepe-soled shoes, canvas shoes, and many other types of shoes not usable with short leg brace.

  6. Biomechanical analysis of drop and countermovement jumps

    NARCIS (Netherlands)

    Bobbert, M. F.; Mackay, M.T.; Schinkelshoek, D.; Huijing, P. A.; van Ingen Schenau, G. J.

    For 13 subjects the performance of drop jumps from a height of 40 cm (DJ) and of countermovement jumps (CMJ) was analysed and compared. From force plate and cine data biomechanical variables including forces, moments, power output and amount of work done were calculated for hip, knee and ankle

  7. A bilateral foot drop due to neuroschistosomiasis.

    NARCIS (Netherlands)

    Wilbers, J.; Idema, A.J.S.; Gijtenbeek, A.


    Schistosomiasis is a parasitic disease, uncommon in Europe and the USA. We present an unusual case of intracerebral schistosomiasis, presenting with a bilateral foot drop. We describe unique magnetic resonance spectroscopy characteristics that can contribute to diagnosis and follow up of a

  8. Alternative method for determining the original drop volume of bloodstains on knit fabrics. (United States)

    Li, Jingyao; Li, Xingyu; Michielsen, Stephen


    Bloodstains are often observed at violent crime scenes and on the skin and clothing of persons involved. The diameters of the blood drops that created these stains are related to the force or energy that caused these drops to become airborne. This has resulted in several attempts to determine the diameter of the original drops, beginning with the methods reported in the pioneering work of Henry Lee [6]. However, his methods destroyed the bloodstain during the measurement. Other methods described in the literature cannot be applied to bloodstains on textiles. A new, rapid, reliable, non-destructive method for determining the diameter of the original drop of blood that results in a stain has been developed for bloodstains on cotton single jersey knit (tee-shirt) fabrics, which is one of the most common fabrics analyzed for BPA both at crime scenes and in forensic laboratories. In this method, a drop of known volume of an appropriate artificial blood substitute is applied to a region similar to the stained region but in an area away from any stains/areas of interest. The areas of the original stain and the artificial blood substitute stain are determined, from which the original drop diameter can be calculated. Errors in the drop diameters, the Reynolds numbers and the Weber numbers resulting from this procedure are less than approximately 6%. This procedure has only been verified on cotton single jersey knit fabrics with 30μL≤drop volume≤80μL. It should not be applied to other materials. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  9. Thermal and ignition type steam explosions of single drops of molten aluminum

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, L.S. [Sandia National Labs., Albuquerque, NM (United States); Duda, P.M.; Hyndman, D.A. [Ktech Corp., Albuquerque, NM (United States); Allison, D.K.; Hyder, M.L. [Westinghouse Savannah River Co., Aiken, SC (United States)


    Seventeen steam explosion experiments were performed with 2 to 10 g drops of molten, high-purity Al. Seven were successfully initiated with underwater exploding bridgewires. At melt release temperatures up to 1400{degrees}C (1673 K) only moderate thermal-type explosions occurred that produced bubbles with volumes up to approximately 1 L. Bubble growth intensified in the melt temperature range 1400-1525{degrees}C (1673--1798 K) as threshold ignition of Al set in. In this range, one of the explosions emitted a flash of light and generated a bubble that grew very rapidly to approximately 14 L, broke through the water surface, and destroyed the test chamber. We attribute the behavior of this latter bubble, which grew as fast as one produced by the underwater firing of a 0.6 g explosive detonator, to an ignition-type steam explosion. Aluminum oxides could not be detected visually in the debris recovered from either typical thermal-type or the ignition-type explosions, and only traces could be detected by X-ray diffraction. In the ignition-type explosion, it is possible however that some oxidic material, probably the smaller particles, was lost during the flooding that occurred as the chamber failed. Both bubble analyses and the absence of appreciable oxide in the debris suggest that the ignition-type steam explosion was not very efficient, probably involving the combustion of only a small fraction of the original molten aluminum globule.

  10. Artificial tektites: an experimental technique for capturing the shapes of spinning drops (United States)

    Baldwin, K. A.


    Tektites are small stones formed from rapidly cooling drops of molten rock ejected from high velocity asteroid impacts with the Earth, that freeze into a myriad of shapes during flight. Many splash-form tektites have an elongated or dumb-bell shape owing to their rotation prior to solidification[1]. Here we present a novel method for creating 'artificial tektites' from spinning drops of molten wax, using diamagnetic levitation to suspend the drops[2]. We find that the solid wax models produced this way are the stable equilibrium shapes of a spinning liquid droplet held together by surface tension. In addition to the geophysical interest in tektite formation, the stable equilibrium shapes of liquid drops have implications for many physical phenomena, covering a wide range of length scales, from nuclear physics (e.g. in studies of rapidly rotating atomic nuclei), to astrophysics (e.g. in studies of the shapes of astronomical bodies such as asteroids, rapidly rotating stars and event horizons of rotating black holes). For liquid drops bound by surface tension, analytical and numerical methods predict a series of stable equilibrium shapes with increasing angular momentum. Slowly spinning drops have an oblate-like shape. With increasing angular momentum these shapes become secularly unstable to a series of triaxial pseudo-ellipsoids that then evolve into a family of two-lobed 'dumb-bell' shapes as the angular momentum is increased still further. Our experimental method allows accurate measurements of the drops to be taken, which are useful to validate numerical models. This method has provided a means for observing tektite formation, and has additionally confirmed experimentally the stable equilibrium shapes of liquid drops, distinct from the equivalent shapes of rotating astronomical bodies. Potentially, this technique could be applied to observe the non-equilibrium dynamic processes that are also important in real tektite formation, involving, e.g. viscoelastic

  11. Aerodynamic and engineering design of a 1.5 s high quality microgravity drop tower facility (United States)

    Belser, Valentin; Breuninger, Jakob; Reilly, Matthew; Laufer, René; Dropmann, Michael; Herdrich, Georg; Hyde, Truell; Röser, Hans-Peter; Fasoulas, Stefanos


    complex system with many interdependencies between all of the components, several engineering challenges had to be addressed. For example, initial disturbances that are caused by the release mechanism are a common issue that arises at drop tower facilities. These vibrations may decrease the quality of microgravity during the initial segment of free fall. Because this would reduce the free fall time experiencing high quality microgravity, a mechanism has been developed to provide a soft release. Challenges and proposed solutions for all components are highlighted in this paper.

  12. Pressure drop of He II flow through a porous media (United States)

    Maddocks, J. R.; van Sciver, S. W.

    The paper reports on measurements of He II pressure drop across two porous SiO2 ceramic filter materials. These materials vary only in porosity, having values of 0.94 and 0.96. The average fiber diameter in both cases is approximately 5 microns. The experiment consists of a glass tube containing a piece of this sponge in one end. The tube is rapidly displaced downward in a bath of helium and the liquid levels are allowed to equilibrate over time producing variable velocities up to 10 cm/sec. The results are compared with those previously obtained using fine mesh screens. Good qualitative agreement is observed for turbulent flow; however, the behavior in the laminar flow regime is not fully understood.

  13. Molecular initiating events of the intersex phenotype: Low-dose exposure to 17α-ethinylestradiol rapidly regulates molecular networks associated with gonad differentiation in the adult fathead minnow testis

    Energy Technology Data Exchange (ETDEWEB)

    Feswick, April; Loughery, Jennifer R.; Isaacs, Meghan A.; Munkittrick, Kelly R.; Martyniuk, Christopher J., E-mail:


    testis, despite the fact that dmrt1 itself was not different in expression from control males. Transcriptional networks involving forkhead box L2 (foxl2) (transcript involved in ovarian follicle development) were increased in expression in the testis. Noteworthy was that a gene network associated to granulosa cell development was increased over 100%, suggesting that this transcriptome network may be important for monitoring estrogenic exposures. Other cell processes rapidly downregulated by EE2 at the transcript level included glucose homeostasis, response to heavy metal, amino acid catabolism, and the cyclooxygenase pathway. Conversely, lymphocyte chemotaxis, intermediate filament polymerization, glucocorticoid metabolism, carbohydrate utilization, and anterior/posterior axis specification were increased. These data provide new insight into the transcriptional responses that are perturbed prior to gonadal remodeling and intersex following exposure to estrogens. These data demonstrate that low concentrations of EE2 (1) rapidly suppresses male hormone production, (2) down-regulate molecular networks related to male sex differentiation, and (3) induce transcriptional networks related to granulosa cell development in the adult testis. These responses are hypothesized to be key molecular initiating events that occur prior to the development of the intersex phenotype following estrogenic exposures.

  14. Coalescence collision of liquid drops II: Off-center collisions of unequal-size drops

    Directory of Open Access Journals (Sweden)

    Alejandro Acevedo-Malavé


    Full Text Available We applied the Smoothed Particle Hydrodynamics method to simulate for first time in the three-dimensional space the hydrodynamic off-center collisions of unequal-size liquid drops in a vacuum environment. The Weber number for several conditions of the droplets dynamics is determined. Also the velocity vector fields inside the drops are shown in the collision process. The evolution of the kinetic and internal energy is shown for the permanent coalescence case. The resulting drops tend to deform, and depending of the Weber number two possible outcomes for the collision of droplets arise: either permanent coalescence or flocculation. In the permanent coalescence of the drops a fragmentation case is modeled, yielding the formation of little satellite droplets.

  15. Coalescence collision of liquid drops I: Off-center collisions of equal-size drops

    Directory of Open Access Journals (Sweden)

    Alejandro Acevedo-Malavé


    Full Text Available The Smoothed Particle Hydrodynamics method (SPH is used here to model off-center collisions of equal-size liquid drops in a three-dimensional space. In this study the Weber number is calculated for several conditions of the droplets dynamics and the velocity vector fields formed inside the drops during the collision process are shown. For the permanent coalescence the evolution of the kinetic and internal energy is shown and also the approaching to equilibrium of the resulting drop. Depending of the Weber number three possible outcomes for the collision of droplets is obtained: permanent coalescence, flocculation and fragmentation. The fragmentation phenomena are modeled and the formation of small satellite drops can be seen. The ligament that is formed follows the “end pinching” mechanism and it is transformed into a flat structure.

  16. On the evolution and breakup of slender drops in an extensional flow (United States)

    Favelukis, M.; Lavrenteva, O. M.; Nir, A.


    The evolution of the shape of an elongated drop embedded in an extensional flow is studied in the framework of slender body theory. The external flow has a weak but not neglected inertia. The problem is governed by three dimensionless parameters: the capillary number, the external Reynolds number, and the viscosity ratio between the drop and the external fluid, and exhibits a multiplicity of stationary shapes with only one being stable. Evolution of the drop surface from initial shapes was studied when the flow intensity was either kept constant or subjected to a sudden change. It was shown that the dynamics of the shape evolution can lead to a breakup of the drop or to a stable stationary shape. Two modes of breakup are revealed: an indefinite elongation and a center pinching mode. The former appears when the viscous forces dominate the inertia effects, with the typical case being that of a creeping flow. The latter breakup mode takes over in the presence of inertia when the drop viscosity diminishes with the extreme example being that of an inviscid drop.

  17. Head-on collision of drops: A numerical investigation (United States)

    Nobari, M. R.; Jan, Y.-J.; Tryggvason, G.


    The head-on collision of equal sized drops is studied by full numerical simulations. The Navier-Stokes equations are solved for fluid motion both inside and outside the drops using a front tracking/finite difference technique. The drops are accelerated toward each other by a body force that is turned off before the drops collide. When the drops collide, the fluid between them is pushed outward leaving a thin later bounded by the drop surface. This layer gets progressively thinner as the drops continue to deform and in several of the calculations this double layer is artificially removed once it is thin enough, thus modeling rupture. If no rupture takes place, the drops always rebound, but if the film is ruptured the drops may coalesce permanently or coalesce temporarily and then split again.

  18. Max Launch Abort System (MLAS) Landing Parachute Demonstrator (LPD) Drop Test (United States)

    Shreves, Christopher M.


    The Landing Parachute Demonstrator (LPD) was conceived as a low-cost, rapidly-developed means of providing soft landing for the Max Launch Abort System (MLAS) crew module (CM). Its experimental main parachute cluster deployment technique and off-the-shelf hardware necessitated a full-scale drop test prior to the MLAS mission in order to reduce overall mission risk. This test was successfully conducted at Wallops Flight Facility on March 6, 2009, with all vehicle and parachute systems functioning as planned. The results of the drop test successfully qualified the LPD system for the MLAS flight test. This document captures the design, concept of operations and results of the drop test.

  19. D.R.O.P. The Durable Reconnaissance and Observation Platform (United States)

    McKenzie, Clifford; Parness, Aaron


    The Durable Reconnaissance and Observation Platform (DROP) is a prototype robotic platform with the ability to climb concrete surfaces up to 85deg at a rate of 25cm/s, make rapid horizontal to vertical transitions, carry an audio/visual reconnaissance payload, and survive impacts from 3 meters. DROP is manufactured using a combination of selective laser sintering (SLS) and shape deposition manufacturing (SDM) techniques. The platform uses a two-wheel, two-motor design that delivers high mobility with low complexity. DROP extends microspine climbing technology from linear to rotary applications, providing improved transition ability, increased speeds, and simpler body mechanics while maintaining microspines ability to opportunistically grip rough surfaces. Various aspects of prototype design and performance are discussed, including the climbing mechanism, body design, and impact survival.

  20. Dynamic response characteristics analysis of the doubly-fed wind power system under grid voltage drop (United States)

    Chen, Y.; Wang, J.; Wang, H. H.; Yang, L.; Chen, W.; Xu, Y. T.


    Double-fed induction generator (DFIG) is sensitive to the disturbances of grid, so the security and stability of the grid and the DFIG itself are under threat with the rapid increase of DFIG. Therefore, it is important to study dynamic response of the DFIG when voltage drop failure is happened in power system. In this paper, firstly, mathematical models and the control strategy about mechanical and electrical response processes is respectively introduced. Then through the analysis of response process, it is concluded that the dynamic response characteristics are related to voltage drop level, operating status of DFIG and control strategy adapted to rotor side. Last, the correctness of conclusion is validated by the simulation about mechanical and electrical response processes in different voltage levels drop and different DFIG output levels under DIgSILENT/PowerFactory software platform.

  1. Negative Pressures and Spallation in Water Drops Subjected to Nanosecond Shock Waves. (United States)

    Stan, Claudiu A; Willmott, Philip R; Stone, Howard A; Koglin, Jason E; Liang, Mengning; Aquila, Andrew L; Robinson, Joseph S; Gumerlock, Karl L; Blaj, Gabriel; Sierra, Raymond G; Boutet, Sébastien; Guillet, Serge A H; Curtis, Robin H; Vetter, Sharon L; Loos, Henrik; Turner, James L; Decker, Franz-Josef


    Most experimental studies of cavitation in liquid water at negative pressures reported cavitation at tensions significantly smaller than those expected for homogeneous nucleation, suggesting that achievable tensions are limited by heterogeneous cavitation. We generated tension pulses with nanosecond rise times in water by reflecting cylindrical shock waves, produced by X-ray laser pulses, at the internal surface of drops of water. Depending on the X-ray pulse energy, a range of cavitation phenomena occurred, including the rupture and detachment, or spallation, of thin liquid layers at the surface of the drop. When spallation occurred, we evaluated that negative pressures below -100 MPa were reached in the drops. We model the negative pressures from shock reflection experiments using a nucleation-and-growth model that explains how rapid decompression could outrun heterogeneous cavitation in water, and enable the study of stretched water close to homogeneous cavitation pressures.

  2. Cracks formation during blood drop evaporation (United States)

    Sobac, Benjamin; Brutin, David; Université de Provence Team


    We firstly presented the pattern formation occurring when drops of whole blood desiccate in a recent publication. The phenomena presented evidence to involve lots of physical field such as surface chemistry, haematolology, fluid mechanics, heat transfer, colloids science... All these mechanisms are acting together and produce an axisymetric and reproducible pattern. Dried cellular components are segregated and deposited by a capillary flow. During the evaporation, the system is slowly drying and cracks when stresses are too important leading to the final pattern observed. In this presentation, we will present the mechanisms involved in the formation of crack patterns. The phenomenon presented here with red blood cells as the main colloids involved is very similar to the drying of drop of nanoparticules. We will explain the common point and the differences encountered.

  3. DROP: Durable Reconnaissance and Observation Platform (United States)

    Parness, Aaron; McKenzie, Clifford F.


    Robots have been a valuable tool for providing a remote presence in areas that are either inaccessible or too dangerous for humans. Having a robot with a high degree of adaptability becomes crucial during such events. The adaptability that comes from high mobility and high durability greatly increases the potential uses of a robot in these situations, and therefore greatly increases its usefulness to humans. DROP is a lightweight robot that addresses these challenges with the capability to survive large impacts, carry a usable payload, and traverse a variety of surfaces, including climbing vertical surfaces like wood, stone, and concrete. The platform is crash-proof, allowing it to be deployed in ways including being dropped from an unmanned aerial vehicle or thrown from a large MSL-class (Mars Science Laboratory) rover.

  4. Drop interactions on a viscous film (United States)

    Costalonga, Maxime; Hack, Michiel; Snoeijer, Jacco


    Every morning at their breakfast, cereal eaters can see that floating objects on a liquid bath attracts to form clusters: this is the so-called Cheerios effect. It has been shown recently that droplets on elastic substrates also interact, either attracting or repelling each other depending on the local slope of the substrate where they lie. Here we present an experiment extending these results to the interaction of droplets deposited on a thin viscous film. By measuring independently the velocity of the droplets and the surface topography of the film, we identify non-monotonic interactions that are due to waves appearing on the film. The drag force exerted onto the droplets is also investigated. We show that the thickness of the film below the drop is intrinsically selected by the velocity of the drop, by a mechanism similar to Bretherton's bubble rising in a confining tube.

  5. Semisupervised Community Detection by Voltage Drops

    Directory of Open Access Journals (Sweden)

    Min Ji


    Full Text Available Many applications show that semisupervised community detection is one of the important topics and has attracted considerable attention in the study of complex network. In this paper, based on notion of voltage drops and discrete potential theory, a simple and fast semisupervised community detection algorithm is proposed. The label propagation through discrete potential transmission is accomplished by using voltage drops. The complexity of the proposal is OV+E for the sparse network with V vertices and E edges. The obtained voltage value of a vertex can be reflected clearly in the relationship between the vertex and community. The experimental results on four real networks and three benchmarks indicate that the proposed algorithm is effective and flexible. Furthermore, this algorithm is easily applied to graph-based machine learning methods.

  6. A pressure drop model for PWR grids

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Dong Seok; In, Wang Ki; Bang, Je Geon; Jung, Youn Ho; Chun, Tae Hyun [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)


    A pressure drop model for the PWR grids with and without mixing device is proposed at single phase based on the fluid mechanistic approach. Total pressure loss is expressed in additive way for form and frictional losses. The general friction factor correlations and form drag coefficients available in the open literatures are used to the model. As the results, the model shows better predictions than the existing ones for the non-mixing grids, and reasonable agreements with the available experimental data for mixing grids. Therefore it is concluded that the proposed model for pressure drop can provide sufficiently good approximation for grid optimization and design calculation in advanced grid development. 7 refs., 3 figs., 3 tabs. (Author)

  7. Measuring Pressure Drop Under Non Ideal Conditions

    Directory of Open Access Journals (Sweden)

    Austin M


    Full Text Available The method of measurement of the pressure drop (PD of cigarette filter rods and the draw resistance of cigarettes is defined in ISO 6565-2002 (1. This standard defines the calibration and use of a transfer standard to calibrate the measuring instrument and also defines the measurement procedure for cigarette and filter samples. The procedure described in the standard assumes that the measurement conditions are constant and that the sample is in equilibrium with the measurement environment.

  8. Impact of water drops on small targets (United States)

    Rozhkov, A.; Prunet-Foch, B.; Vignes-Adler, M.


    The collision of water drops against small targets was studied experimentally by means of a high-speed photography technique. The drop impact velocity was about 3.5 m/s. Drop diameters were in the range of 2.8-4.0 mm. The target was a stainless steel disk of 3.9 mm diameter. The drop spread beyond the target like a central cap surrounded by a thin, slightly conical lamella bounded by a thicker rim. By mounting a small obstacle near the target, surface-tension driven Mach waves in the flowing lamella were generated, which are formally equivalent to the familiar compressibility driven Mach waves in gas dynamics. From the measurement of the Mach angle, the values of some flow parameters could be obtained as functions of time, which provided insight into the flow structure. The liquid flowed from the central cap to the liquid rim through the thin lamella at constant momentum flux. At a certain stage of the process, most of the liquid accumulated in the rim and the internal part of the lamella became metastable. In this situation, a rupture wave propagating through the metastable internal part of the lamella caused the rim to retract while forming outwardly directed secondary jets. The jets disintegrated into secondary droplets due to the Savart-Plateau-Rayleigh instability. Prior to the end of the retraction, an internal circular wave of rupture was formed. It originated at the target and then it propagated to meet the retracting rim. Their meeting resulted in a crown of tiny droplets. A theoretical analysis of the ejection process is proposed.

  9. Drag and Drop API v HTML5


    BARABÁŠ, Vít


    The work (the bachelor´s thesis) deals with a new way of web application management via the "drag and drop" technique in the HTML5 programming language. The work is divided into two parts. The first part consists of DND API description in HTML5. The support analysis within common web browsers is included as a part of this description. The second, practical part of the thesis focuses on a concept and the following realisation of a photogallery using DND API.

  10. Syntactic Cues for Inferences about Causality in Language Acquisition: Evidence from an Argument-Drop Language (United States)

    Suzuki, Takaaki; Kobayashi, Tessei


    Syntactic bootstrapping facilitates children's initial learning of verb meanings based on syntactic information. A challenging case is the argument-drop languages, where the number of argument NPs is not a reliable cue for distinguishing between transitive and intransitive verbs. Despite this fact, the availability of syntactic bootstrapping in…

  11. Drop impacts on electrospun nanofiber membranes (United States)

    Sahu, Rakesh P.; Sinha-Ray, Suman; Yarin, Alexander; Pourdeyhimi, Behnam


    This work reports a study of drop impacts of polar and non-polar liquids onto electrospun nanofiber membranes (of 8-10 mm thickness and pore sizes of 3-6 nm) with an increasing degree of hydrophobicity. The nanofibers used were electrospun from polyacrylonitrile (PAN), nylon 6/6, polycaprolactone (PCL) and Teflon. It was found that for any liquid/fiber pair there exists a threshold impact velocity (1.5 to 3 m/s) above which water penetrates membranes irrespective of their wettability. The low surface tension liquid left the rear side of sufficiently thin membranes as a millipede-like system of tiny jets protruding through a number of pores. For such a high surface tension liquid as water, jets immediately merged into a single bigger jet, which formed secondary drops due to capillary instability. An especially non-trivial result is that superhydrophobicity of the porous nano-textured Teflon skeleton with the interconnected pores is incapable of preventing water penetration due to drop impact, even at relatively low impact velocities close to 3.46 m/s. A theoretical estimate of the critical membrane thickness sufficient for complete viscous dissipation of the kinetic energy of penetrating liquid corroborates with the experimental data. The current work is supported by the Nonwovens Cooperative Research Center (NCRC).

  12. Experimental study of liquid drop impact onto a powder surface

    KAUST Repository

    Marston, Jeremy


    The initial dynamics of liquid drop impact onto powder surfaces is studied experimentally using high-speed photography. For a range of bed packing fractions, φ, liquid physical properties and impact velocities, ui, we observe a variety of phenomena that can be representative of a hydrophobic surface, a rough surface or a porous medium. The solids packing fraction in the bed, 0.38≤φ≤0.65, and the impact Weber number, 3.5≤We=ρDui 2/φ≤750, (where ρ, D and φ are the drop density, diameter and surface tension respectively) are shown to be the critical parameters governing the outcome of an impact. For high packing fractions, φ≳0.5, we show that the observed spreading, rebound and splashing can be broadly characterised in terms of the Weber number while for looser packing fractions, φ≲0.5, we observe powder ejectas and provide a qualitative description of the granule nucleation at the centre of the impact sites. © 2010 Elsevier B.V.

  13. Corneal sensitivity after topical bromfenac sodium eye-drop instillation

    Directory of Open Access Journals (Sweden)

    Yanai K


    Full Text Available Kaori Yanai,1 Jane Huang,1 Kazuaki Kadonosono,2 Eiichi Uchio1 1Department of Ophthalmology, Fukuoka University School of Medicine, Fukuoka, Japan; 2Department of Ophthalmology, Yokohama City University Medical Center, Yokohama, Japan Purpose: To evaluate the safety of bromfenac sodium eye drops from the standpoint of corneal sensitivity and tear secretion in healthy controls following instillation for 1 month. Methods: A prospective single-blind parallel clinical study was conducted in 20 eyes of ten healthy volunteers with no history of ocular or systemic allergic disease, dry eye, contact lens wear, or ocular surgery. Participants were instructed to instill either bromfenac sodium or artificial tears in each eye twice daily for 28 days. Corneal sensitivity tested using a Cochet–Bonnet esthesiometer was evaluated before and immediately after instillation at 7, 14, and 28 days after the initiation of treatment. Tear secretion was also evaluated by Schirmer's eye test before and at 28 days. Results: No significant difference in mean corneal sensitivity and tear-secretion rate was observed between the bromfenac and artificial-tear treatment groups at any time. Conclusion: These results indicate that bromfenac sodium eye drops are safe with respect to corneal sensitivity and tear secretion in subjects with a normal ocular surface condition. Further evaluation is still necessary to determine whether bromfenac is safe in pathological conditions, such as inflammatory disorders and postsurgical cases. Keywords: bromfenac sodium, cornea, sensitivity, tear, nonsteroidal anti-inflammatory drug

  14. Laplacian drop shapes and effect of random perturbations on accuracy of surface tension measurement for different drop constellations. (United States)

    Saad, Sameh M I; Neumann, A Wilhelm


    Theoretical drop shapes are calculated for three drop constellations: pendant drops, constrained sessile drops, and unconstrained sessile drops. Based on total Gaussian curvature, shape parameter and critical shape parameter are discussed as a function of different drop sizes and surface tensions. The shape parameter is linked to physical parameters for every drop constellation. The as yet unavailable detailed dimensional analysis for the unconstrained sessile drop is presented. Results show that the unconstrained sessile drop shape depends on a dimensionless volume term and the contact angle. Random perturbations are introduced and the accuracy of surface tension measurement is assessed for precise and perturbed profiles of the three drop constellations. It is concluded that pendant drops are the best method for accurate surface tension measurement, followed by constrained sessile drops. The unconstrained sessile drops come last because they tend to be more spherical at low and moderate contact angles. Of course, unconstrained sessile drops are the only option if contact angles are to be measured. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Development of a constant surface pressure penetration langmuir balance based on axisymmetric drop shape analysis. (United States)

    Wege, H A; Holgado-Terriza, J A; Cabrerizo-Vílchez, M A


    A new constant pressure pendant-drop penetration surface balance has been developed combining a pendant-drop surface balance, a rapid-subphase-exchange technique, and a fuzzy logic control algorithm. Beside the determination of insoluble monolayer compression-expansion isotherms, it allows performance of noninvasive kinetic studies of the adsorption of surfactants added to the new subphase onto the free surface and of the adsorption/penetration/reaction of the former onto/into/with surface layers, respectively. The interfacial pressure pi is a fundamental parameter in these studies: by working at constant pi one controls the height of the energy barrier to adsorption/penetration and can select different regimes and steps of the adsorption/penetration process. In our device a solution drop is formed at the tip of a coaxial double capillary, connected to a double microinjector. Drop profiles are extracted from digital drop micrographs and fitted to the equation of capillarity, yielding pi, the drop volume V, and the interfacial area A. pi is varied changing V (and hence A) with the microinjector. Control is based on a case-adaptable modulated fuzzy-logic PID algorithm able to maintain constant pi (or A) under a wide range of experimental conditions. The drop subphase liquid can be exchanged quantitatively by the coaxial capillaries. The adsorption/penetration/reaction kinetics at constant pi are then studied monitoring A(t), i.e., determining the relative area change necessary at each instant to compensate the pressure variation due to the interaction of the surfactant in the subsurface with the surface layer. A fully Windows-integrated program manages the whole setup. Examples of experimental protein adsorption and monolayer penetration kinetics are presented.

  16. Effect of chamfer geometry on the pressure drop of perforated plates with thin orifices

    Energy Technology Data Exchange (ETDEWEB)

    Barros Filho, José A., E-mail: [Centro de Desenvolvimento da Tecnologia Nuclear, Comissão Nacional de Energia Nuclear, Av. Pres. Antônio Carlos, 6627, 30270-901 Belo Horizonte, MG (Brazil); Santos, André A.C., E-mail: [Centro de Desenvolvimento da Tecnologia Nuclear, Comissão Nacional de Energia Nuclear, Av. Pres. Antônio Carlos, 6627, 30270-901 Belo Horizonte, MG (Brazil); Navarro, Moysés A., E-mail: [Centro de Desenvolvimento da Tecnologia Nuclear, Comissão Nacional de Energia Nuclear, Av. Pres. Antônio Carlos, 6627, 30270-901 Belo Horizonte, MG (Brazil); Jordão, Elizabete, E-mail: [Faculdade de Engenharia Química, Universidade Estadual de Campinas – UNICAMP, Av. Albert Einstein, 500, 13.083-852 Campinas, SP (Brazil)


    Highlights: • CFD estimation of pressure drop of perforated plates with chamfered thin orifices. • Different chamfer geometric features evaluated. • Calculation validated against reduced scale experiments. - Abstract: Perforated plates with thin orifices is one of the options under considerations to be used in the debris filtering bottom end pieces for the next generation of fuel assemblies for the Brazilian nuclear plants. The increase in pressure drop can be drastically reduced by optimizing the chamfer geometries. This paper describes the development and validation of a procedure devised to use Computational Fluid Dynamics (CFD) to accurately estimate the pressure drop of water flow through perforated plates with chamfered thin orifices. The procedure comprises a scaled down calculation domain, grid configuration and a set of numerical solution parameters. The validation was performed against experiments with a set of plates with different chamfer geometric features like position (inlet, outlet and both sides), angles and sizes. Three turbulence models were evaluated with the standard k–ε giving the best result. For the range of parameters evaluated here the pressure drop decrease of a two sided chamfer plate can be estimated as a sum of both inlet and outlet chamfers individually. In both cases the pressure drop decreases rapidly for small chamfers and more slowly for larger chamfers. In the flat regions the chamfer angle has little influence at the inlet and is more important at outlet.

  17. Surfactant Facilitated Spreading of Aqueous Drops on Hydrophobic Surfaces (United States)

    Kumar, Nitin; Couzis, Alex; Maldareili, Charles; Singh, Bhim (Technical Monitor)


    removes a significant amount of the surface water. In this presentation, we report the results of measurements of the molecular packing and rates of kinetic exchange of the trisiloxane surfactants at the air/water interface in order to confirm our picture of trisiloxane packing, and provide additional insight into the superspreading process. We used the pendant bubble technique as a Langmuir trough to measure the trisiloxane equation of state which relates the tension to the surface concentration. From these measurements we obtain accurate values for the maximum packing density. We find that trisiloxanes with 4 and 8 ethoxylate groups have the same maximum packing concentration, indicating that the maximum packing is controlled by the cross section of the head group. For trisiloxanes with larger than eight ethoxylates, the maximum packing increases with ethoxylate number, indicating that the disposition of the ethoxylate chain (i.e., its effective size) is controlling. This supports our picture of superspreading: The superspreading ability of trisiloxanes decreases considerably for trisiloxanes with larger than eight ethoxylates; the packing measurements indicate that for the higher ethoxylate number trisiloxanes, the compact nonpolar head groups are pushed apart by the ethoxylate chain. They leave spaces of surface water on adsorption and do not lower the solid tension as much as their lower chain analogues. Finally the report measurements of the dynamic tension reduction accompanying the adsorption of trisiloxanes onto an initially clean interface using the pendant bubble technique, and we obtain from these relaxations, the equation of state and a mass transfer model, the rate constants for kinetic exchange. We find that the rate constants for desorption of trisiloxanes are generally much slower than for analogous aliphatic polyethoxylate surfactants with identical ethoxylate chain lengths. When an aqueous drop of a superspreader solution is placed on a hydrophobic

  18. Simplified procedure for determining of drop and stilling basin

    Directory of Open Access Journals (Sweden)

    Ali R. Vatankhah


    Full Text Available Drops are used to effectively dissipate the surplus energy of the water flow. A closed conduit drop conveys water and stills it at its downstream. I-type pipe drop is one kind of the closed conduit drops which is used in irrigation networks as a typical hydraulic structure. Sump elevation is an important design parameter for I-type pipe drop. Similarly, in supercritical flow structures, such as open channel chutes, determination of stilling basin invert elevation is very important. At present, these key design parameters are determined by the momentum and energy equations using tedious trial-and-error procedure. In this study, square conduit drop, pipe drop, and rectangular stilling basin are considered, and three explicit equations have been developed by (multiple nonlinear regression technique to determine the sump and stilling basin invert elevations. Being very simple and accurate, these equations can be easily used to design the closed conduit drops and stilling basins by hydraulic engineers.

  19. Reducing pressure drop in a baghouse using flow distributors

    Energy Technology Data Exchange (ETDEWEB)

    Chen, C. [Tajen Institute of Technology, Ping-Tung Hsien (Taiwan). Dept. of Environmental Engineering and Health


    The pressure drop of ladder vanes in a baghouse could be reduced by decreasing the vane number and adjusting the inclined angle of the vane. Two types of flow distributors were utilized to test pressure drop caused by the structure of a baghouse. The pressure drops were measured by an inclined manometer under various filtration velocities. The purpose of this study is to understand the improvement effect of pressure drop saving on traditional ladder vanes. 14 refs., 6 figs.

  20. Cerebral infarction presenting with unilateral isolated foot drop. (United States)

    Kim, Ki-Wan; Park, Jung-Soo; Koh, Eun-Jeong; Lee, Jong-Myong


    Weakness of the dorsiflexor muscles of the ankle or toe, referred to as foot drop, is a relatively common presentation. In most cases, foot drop is caused by a lower motor neuron disease such as peroneal peripheral neuropathy, L4-5 radiculopathic sciatic neuropathy, or polyneuropathy. Although upper motor neuron lesions can present as foot drop, the incidence is very rare. Here, we report an extremely rare case in which foot drop was the only presenting symptom of cerebral infarction.

  1. Cerebral Infarction Presenting with Unilateral Isolated Foot Drop


    Kim, Ki-Wan; Park, Jung-Soo; Koh, Eun-Jeong; Lee, Jong-Myong


    Weakness of the dorsiflexor muscles of the ankle or toe, referred to as foot drop, is a relatively common presentation. In most cases, foot drop is caused by a lower motor neuron disease such as peroneal peripheral neuropathy, L4-5 radiculopathic sciatic neuropathy, or polyneuropathy. Although upper motor neuron lesions can present as foot drop, the incidence is very rare. Here, we report an extremely rare case in which foot drop was the only presenting symptom of cerebral infarction.

  2. Uncertainty Analysis of the Results of Potential Cask Drops in the K West Basin South Loadout Pit

    Energy Technology Data Exchange (ETDEWEB)

    LEW, B.S.


    If a cask and Multi-Canister Overpack (MCO) were to be dropped, the analysis established possible initial volumetric flow rates. The results of the uncertainty analysis demonstrated that even if a cask and MCO were to be dropped the possible initial volumetric flow rate through the opened floor/wall joint would be small. There is a 95% confidence (probability of 0.95) that the initial volumetric flow rate would be smaller than 411 gpm and a 99% confidence (probability of 0.99) that it would be smaller than 916 gpm.

  3. Electrowetting-enhanced microfluidic device for drop generation

    NARCIS (Netherlands)

    Gu, H.; Malloggi, F.G.J.; Vanapalli, Srinivas; Vanapalli Veera, V.S.A.R.; Mugele, Friedrich Gunther


    We integrated electrowetting into a microfluidic flow focusing device to study drop generation under the influence of electric fields. Using both the dispersed phase inlet pressure and the applied voltage as control parameters, we find that the range of drop sizes and the drop generation rate can be

  4. How microstructures affect air film dynamics prior to drop impact

    NARCIS (Netherlands)

    van der Veen, Roeland; Hendrix, M.H.W.; Tran, Tuan; Sun, Chao; Tsai, Peichun Amy; Lohse, Detlef


    When a drop impacts a surface, a dimple can be formed due to the increased air pressure beneath the drop before it wets the surface. We employ a high-speed color interferometry technique to measure the evolution of the air layer profiles under millimeter-sized drops impacting hydrophobic

  5. Preparation and Stability of Voriconazole Eye Drop Solution▿


    Dupuis, Antoine; Tournier, Nicolas; Le Moal, Gwenaël; Venisse, Nicolas


    The combined systemic and topical administration of voriconazole has successfully been used to treat keratomycosis. Because no voriconazole eye drop product is commercially available, we prepared a sterile eye drop solution (10 mg/ml). Voriconazole remains stable over 30 days, providing an eye drop solution suitable for use for the topical treatment of fungal keratitis.

  6. Coalescence, evaporation and particle deposition of consecutively printed colloidal drops (United States)

    Chhasatia, Viral; Yang, Xin; Shah, Jaymeen; Sun, Ying


    In applications such as inkjet printing and spray deposition, colloid drops are often used as building blocks for line and pattern printing where their interactions play important roles in determining the deposition morphology and properties. In this study, the particle deposition dynamics of two consecutively printed evaporating colloidal drops is examined using a fluorescence microscope and a synchronized side-view camera. The results show that the relaxation time of the water-air interface of the merged drop is shorter than that of a single drop impacting on a dry surface. It is also found that both morphology and particle distribution uniformity of the deposit change significantly with varying jetting delay and spatial spacing between two drops. As the drop spacing increases while keeping jetting delay constant, the circularity of the coalesced drop reduces. For the regime where the time scale for drop evaporation is comparable with the relaxation time scale for two drops to completely coalesce, the capillary flow induced by the local curvature variation of the air-water interface redistributes particles inside a merged drop, causing suppression of the coffee-ring effect for the case of a high jetting frequency while resulting in a region of particle accumulation in the middle of the merged drop at a low jetting frequency. By tuning the interplay of wetting, evaporation, capillary relaxation, and particle assembly, the deposition morphology of consecutively printed colloidal drops can be controlled.

  7. Drops on hydrophobic surfaces & vibrated fluid surfaces

    DEFF Research Database (Denmark)

    Wind-Willassen, Øistein

    in the literature. Furthermore, we quantify the energy associated with center of mass translation and internal fluid motion. The model predicts trajectories for tracer particles deposited inside the drop, and satisfactorily describes the sliding motion of steadily accelerating droplets. The model can be used...... numerically, and the results are compared to experiments. We provide, again, the most detailed regime diagram of the possible orbits depending on the forcing and the rotation rate of the fluid bath. We highlight each class of orbit, and analyze in depth the wobbling state, precessing orbits, wobble......-leap dynamics, exotic trajectories and the emergence of statistical behavior when the forcing is near the Faraday threshold....

  8. Stability analysis applied to the early stages of viscous drop breakup by a high-speed gas stream (United States)

    Padrino, Juan C.; Longmire, Ellen K.


    The instability of a liquid drop suddenly exposed to a high-speed gas stream behind a shock wave is studied by considering the gas-liquid motion at the drop interface. The discontinuous velocity profile given by the uniform, parallel flow of an inviscid, compressible gas over a viscous liquid is considered, and drop acceleration is included. Our analysis considers compressibility effects not only in the base flow, but also in the equations of motion for the perturbations. Recently published high-resolution images of the process of drop breakup by a passing shock have provided experimental evidence supporting the idea that a critical gas dynamic pressure can be found above which drop piercing by the growth of acceleration-driven instabilities gives way to drop breakup by liquid entrainment resulting from the gas shearing action. For a set of experimental runs from the literature, results show that, for shock Mach numbers >= 2, a band of rapidly growing waves forms in the region well upstream of the drop's equator at the location where the base flow passes from subsonic to supersonic, in agreement with experimental images. Also, the maximum growth rate can be used to predict the transition of the breakup mode from Rayleigh-Taylor piercing to shear-induced entrainment. The authors acknowledge support of the NSF (DMS-0908561).

  9. Spontaneous self-coating of a water drop by flaky copper powders: critical role of the particle shape. (United States)

    Chang, Cheng-Chung; Wu, Cyuan-Jhang; Sheng, Yu-Jane; Tsao, Heng-Kwong


    The self-coating process of solid particles over a liquid drop is important for the formation of a liquid marble. Generally, some external forces such as rolling or flipping are used to cover a drop by small particles. In this work, it is observed that flaky copper powders can spontaneously spread over the planar water surface and form a dense flat cluster with a fractal dimension of 2. Moreover, flaky copper powders can cover the water pendant and sessile drops spontaneously and rapidly. This powder-coated drop can roll on an inclined plane at a relatively high speed. However, spontaneous self-coating disappears for spheroidal copper powders. To explain our observations, the shape factors of particles are introduced into the spreading coefficient S for powders on the liquid surface. The flaky powders have the lowest shape factors and therefore spontaneous self-coating formation, with S > 0.

  10. Drop drying on surfaces determines chemical reactivity - the specific case of immobilization of oligonucleotides on microarrays (United States)


    Background Drop drying is a key factor in a wide range of technical applications, including spotted microarrays. The applied nL liquid volume provides specific reaction conditions for the immobilization of probe molecules to a chemically modified surface. Results We investigated the influence of nL and μL liquid drop volumes on the process of probe immobilization and compare the results obtained to the situation in liquid solution. In our data, we observe a strong relationship between drop drying effects on immobilization and surface chemistry. In this work, we present results on the immobilization of dye labeled 20mer oligonucleotides with and without an activating 5′-aminoheptyl linker onto a 2D epoxysilane and a 3D NHS activated hydrogel surface. Conclusions Our experiments identified two basic processes determining immobilization. First, the rate of drop drying that depends on the drop volume and the ambient relative humidity. Oligonucleotides in a dried spot react unspecifically with the surface and long reaction times are needed. 3D hydrogel surfaces allow for immobilization in a liquid environment under diffusive conditions. Here, oligonucleotide immobilization is much faster and a specific reaction with the reactive linker group is observed. Second, the effect of increasing probe concentration as a result of drop drying. On a 3D hydrogel, the increasing concentration of probe molecules in nL spotting volumes accelerates immobilization dramatically. In case of μL volumes, immobilization depends on whether the drop is allowed to dry completely. At non-drying conditions, very limited immobilization is observed due to the low oligonucleotide concentration used in microarray spotting solutions. The results of our study provide a general guideline for microarray assay development. They allow for the initial definition and further optimization of reaction conditions for the immobilization of oligonucleotides and other probe molecule classes to different

  11. Rapid Prototyping (United States)


    Javelin, a Lone Peak Engineering Inc. Company has introduced the SteamRoller(TM) System as a commercial product. The system was designed by Javelin during a Phase II NASA funded small commercial product. The purpose of the invention was to allow automated-feed of flexible ceramic tapes to the Laminated Object Manufacturing rapid prototyping equipment. The ceramic material that Javelin was working with during the Phase II project is silicon nitride. This engineered ceramic material is of interest for space-based component.

  12. Equilibrium drop surface profiles in electric fields (United States)

    Mugele, F.; Buehrle, J.


    Electrowetting is becoming a more and more frequently used tool to manipulate liquids in various microfluidic applications. On the scale of the entire drop, the effect of electrowetting is to reduce the apparent contact angle of partially wetting conductive liquids upon application of an external voltage. Microscopically, however, strong electric fields in the vicinity of the three phase contact line give rise to local deformations of the drop surface. We determined the equilibrium surface profile using a combined numerical, analytical, and experimental approach. We find that the local contact angle in electrowetting is equal to Young's angle independent of the applied voltage. Only on the scale of the thickness of the insulator and beyond does the surface slope assume a value consistent with the voltage-dependent apparent contact angle. This behaviour is verified experimentally by determining equilibrium surface profiles for insulators of various thicknesses between 10 and 250 µm. Numerically and analytically, we find that the local surface curvature diverges algebraically upon approaching the contact line with an exponent -1<μ<0. We discuss the relevance of the local surface properties for dynamic aspects of the contact line motion.

  13. Impact Dynamics of Oxidized Liquid Metal Drops

    CERN Document Server

    Xu, Qin; Jaeger, Heinrich M


    With exposure to air, many liquid metals spontaneously generate an oxide layer on their surface. In oscillatory rheological tests, this skin is found to introduce a yield stress that typically dominates the elastic response but can be tuned by exposing the metal to hydrochloric acid solutions of different concentration. We systematically studied the normal impact of eutectic gallium-indium (eGaIn) drops under different oxidation conditions and show how this leads to two different dynamical regimes. At low impact velocity (or low Weber number), eGaIn droplets display strong recoil and rebound from the impacted surface when the oxide layer is removed. In addition, the degree of drop deformation or spreading during the impact is controlled by the oxide skin. We show that the scaling law known from ordinary liquids for the maximum spreading radius as a function of impact velocity can still be applied to the case of oxidized eGaIn if an effective Weber number $We^{\\star}$ is employed that uses an effective surface...

  14. Rapid appearance of resolvin precursors in inflammatory exudates: novel mechanisms in resolution. (United States)

    Kasuga, Kie; Yang, Rong; Porter, Timothy F; Agrawal, Nitin; Petasis, Nicos A; Irimia, Daniel; Toner, Mehmet; Serhan, Charles N


    Resolution of inflammation is essential. Although supplementation of omega-3 fatty acids is widely used, their availability at sites of inflammation is not known. To this end, a multidisciplinary approach was taken to determine the relationship of circulating omega-3 to inflammatory exudates and the generation of resolution signals. In this study, we monitored resolvin precursors in evolving exudates, which initially paralleled increases in edema and infiltrating neutrophils. We also prepared novel microfluidic chambers to capture neutrophils from a drop of blood within minutes that permitted single-cell monitoring. In these, docosahexaenoic acid-derived resolvin D1 rapidly stopped neutrophil migration, whereas precursor docosahexaenoic acid did not. In second organ injury via ischemia-reperfusion, resolvin metabolically stable analogues were potent organ protectors reducing neutrophils. Together, these results indicate that circulating omega-3 fatty acids rapidly appear in inflammatory sites that require conversion to resolvins that control excessive neutrophil infiltration, protect organs, and foster resolution.

  15. Sound Wave Energy Resulting from the Impact of Water Drops on the Soil Surface.

    Directory of Open Access Journals (Sweden)

    Magdalena Ryżak

    Full Text Available The splashing of water drops on a soil surface is the first step of water erosion. There have been many investigations into splashing-most are based on recording and analysing images taken with high-speed cameras, or measuring the mass of the soil moved by splashing. Here, we present a new aspect of the splash phenomenon's characterization the measurement of the sound pressure level and the sound energy of the wave that propagates in the air. The measurements were carried out for 10 consecutive water drop impacts on the soil surface. Three soils were tested (Endogleyic Umbrisol, Fluvic Endogleyic Cambisol and Haplic Chernozem with four initial moisture levels (pressure heads: 0.1 kPa, 1 kPa, 3.16 kPa and 16 kPa. We found that the values of the sound pressure and sound wave energy were dependent on the particle size distribution of the soil, less dependent on the initial pressure head, and practically the same for subsequent water drops (from the first to the tenth drop. The highest sound pressure level (and the greatest variability was for Endogleyic Umbrisol, which had the highest sand fraction content. The sound pressure for this soil increased from 29 dB to 42 dB with the next incidence of drops falling on the sample The smallest (and the lowest variability was for Fluvic Endogleyic Cambisol which had the highest clay fraction. For all experiments the sound pressure level ranged from ~27 to ~42 dB and the energy emitted in the form of sound waves was within the range of 0.14 μJ to 5.26 μJ. This was from 0.03 to 1.07% of the energy of the incident drops.

  16. Sound Wave Energy Resulting from the Impact of Water Drops on the Soil Surface. (United States)

    Ryżak, Magdalena; Bieganowski, Andrzej; Korbiel, Tomasz


    The splashing of water drops on a soil surface is the first step of water erosion. There have been many investigations into splashing-most are based on recording and analysing images taken with high-speed cameras, or measuring the mass of the soil moved by splashing. Here, we present a new aspect of the splash phenomenon's characterization the measurement of the sound pressure level and the sound energy of the wave that propagates in the air. The measurements were carried out for 10 consecutive water drop impacts on the soil surface. Three soils were tested (Endogleyic Umbrisol, Fluvic Endogleyic Cambisol and Haplic Chernozem) with four initial moisture levels (pressure heads: 0.1 kPa, 1 kPa, 3.16 kPa and 16 kPa). We found that the values of the sound pressure and sound wave energy were dependent on the particle size distribution of the soil, less dependent on the initial pressure head, and practically the same for subsequent water drops (from the first to the tenth drop). The highest sound pressure level (and the greatest variability) was for Endogleyic Umbrisol, which had the highest sand fraction content. The sound pressure for this soil increased from 29 dB to 42 dB with the next incidence of drops falling on the sample The smallest (and the lowest variability) was for Fluvic Endogleyic Cambisol which had the highest clay fraction. For all experiments the sound pressure level ranged from ~27 to ~42 dB and the energy emitted in the form of sound waves was within the range of 0.14 μJ to 5.26 μJ. This was from 0.03 to 1.07% of the energy of the incident drops.

  17. Deformed liquid marbles: Freezing drop oscillations with powders

    KAUST Repository

    Marston, Jeremy


    In this work we show that when a liquid drop impacts onto a fine-grained hydrophobic powder, the final form of the drop can be very different from the spherical form with which it impacts. In all cases, the drop rebounds due to the hydrophobic nature of the powder. However, we find that above a critical impact speed, the drop undergoes a permanent deformation to a highly non-spherical shape with a near-complete coverage of powder, which then freezes the drop oscillations during rebound. © 2012 Elsevier B.V.

  18. Time-varying droplet configuration determines break-up probability of drops within a concentrated emulsion (United States)

    Khor, Jian Wei; Kim, Minkyu; Schütz, Simon S.; Schneider, Tobias M.; Tang, Sindy K. Y.


    This paper aims to identify the origin of the probability of break-up of drops within a concentrated emulsion flowing as a 2D monolayer through a tapered microchannel into a constriction. Although the concentrated emulsion is complex involving many-body interactions, all break-up events occur between two drops pinching each other as they enter the constriction under the conditions tested. Whether break-up occurs or not depends strongly on the relative position between the two drops at the entrance of the constriction. There exist a critical offset between the initial positions of the two drops below which break-up always occurs and another critical offset above which no break-up occurs. In between these two critical offsets, there is a narrow bistable region where both break-up and non-break-up events are observed. For a flowing concentrated emulsion, the relative position between two droplets entering the constriction varies stochastically. The frequency of occurrence of drop pairs having specific offsets, together with the critical offset values for break-up, determines the break-up probability in the flowing emulsion.

  19. Changes in center of pressure displacement with the use of a foot drop stimulator in individuals with stroke. (United States)

    Nolan, Karen J; Yarossi, Mathew; Mclaughlin, Patrick


    Center of pressure measured during gait can provide information about underlying control mechanisms and the efficacy of a foot drop stimulator. This investigation evaluated changes in center of pressure displacement in individuals with stroke with and without a foot drop stimulator. Individuals with stroke-related foot drop (n=11) using a foot drop stimulator and healthy controls (n=11). Walking speed and bilateral center of pressure variables: 1) net displacement; 2) position and maximum displacement; and 3) mean velocity during walking. On the affected limb with the foot drop stimulator as compared to the affected limb without the foot drop stimulator: 1) increased anterior/posterior maximum center of pressure excursion 8% during stance; 2) center of pressure at initial contact was 6% more posterior; 3) medial/lateral mean, maximum and minimum center of pressure position during stance all significantly decreased; 4) anterior/posterior net displacement increased during stance and single support; and 5) anterior/posterior velocity of the center of pressure increased during stance. Individuals with stroke using a foot drop stimulator contacted the ground more posterior at initial contact and utilized more of the anterior/posterior plantar surface of the foot on the affected limb during stance. With the foot drop stimulator there was a shift in center of pressure toward the medial side possibly indicating an improvement in equinovarus gait where there is a tendency to load the lateral foot throughout stance. For individuals with stroke a foot drop stimulator can improve displacement of the center of pressure which indicates improved forward progression and stability during walking. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Dropping macadamia nuts-in-shell reduces kernel roasting quality. (United States)

    Walton, David A; Wallace, Helen M


    Macadamia nuts ('nuts-in-shell') are subjected to many impacts from dropping during postharvest handling, resulting in damage to the raw kernel. The effect of dropping on roasted kernel quality is unknown. Macadamia nuts-in-shell were dropped in various combinations of moisture content, number of drops and receiving surface in three experiments. After dropping, samples from each treatment and undropped controls were dry oven-roasted for 20 min at 130 °C, and kernels were assessed for colour, mottled colour and surface damage. Dropping nuts-in-shell onto a bed of nuts-in-shell at 3% moisture content or 20% moisture content increased the percentage of dark roasted kernels. Kernels from nuts dropped first at 20%, then 10% moisture content, onto a metal plate had increased mottled colour. Dropping nuts-in-shell at 3% moisture content onto nuts-in-shell significantly increased surface damage. Similarly, surface damage increased for kernels dropped onto a metal plate at 20%, then at 10% moisture content. Postharvest dropping of macadamia nuts-in-shell causes concealed cellular damage to kernels, the effects not evident until roasting. This damage provides the reagents needed for non-enzymatic browning reactions. Improvements in handling, such as reducing the number of drops and improving handling equipment, will reduce cellular damage and after-roast darkening. Copyright © 2010 Society of Chemical Industry.

  1. Controlling the Mobility of the Fluid Interface of Moving Gas Bubbles or Liquid Drops by Using Micellar Solutions of Surfactants (United States)

    Maldarelli, Charles; Papageorgiou, Demetrios


    Microgravity processes must rely on mechanisms other than buoyancy to move bubbles or droplets from one region to another in a continuous liquid phase. One suggested method is thermocapillary migration in which a temperature gradient is applied to the continuous phase. A significant and as yet unresolved impediment to the use of thermocapillary migration to direct bubble or drop motion is that these migrations can be significantly retarded by the adsorption onto the fluid particle surface of surface active impurities unavoidably present in the continuous or (if the particle is a liquid) droplet phases. The focus of our research was to develop a theory for remobilizing fluid particle interfaces retarded by a surfactant impurity in an effort to make more viable the use of thermocapillary migrations for the management of bubbles and drops in microgravity. We postulated that a surfactant at high bulk concentration which kinetically exchanges rapidly with the surface can restore interface mobility. The scaling arguments along with a discussion of the previous literature is reviewed in the context of the scaling framework. The specific objectives of the research were twofold. The first was to prove the remobilization theory by studying a model problem. As the mechanism for remobilization is independent of the force which drives the particle, the fluid particle shape and the presence of fluid inertia, we chose the simplest model consisting of a spherical bubble rising steadily by buoyancy in creeping flow. We solved the hydrodynamic and surfactant transport equations for rapid kinetic exchange to demonstrate that as the concentration increases, the Marangoni retardation at first increases (the low k behavior) and then decreases (the high k behavior). The second objective was to develop a method to determine the kinetic rate constants of a surfactant molecule, since this information is necessary to select surfactants which will exchange rapidly enough relative to the

  2. Emulsion Design. Analysis of Drop Deformations in Mixed Flows

    DEFF Research Database (Denmark)

    Egholm, Runi Ditlev


    does not rely on numerical flow field calculations. The results from this analysis indicate that there is a relationship between the average drop deformation and the apparent shear rate. In the second method the experimentally obtained particle track is used together with numerical calculations...... the drop deformation and drop position a twin camera system is applied. In the subsequent data analysis the recorded movies are analysed using an automated image analysis procedure which leads to the deformation history of the drop and the drop trajectory in the device. However, due to the geometric...... by the drop in the rotor-stator device is emulated in the computational box used for carrying out drop shape simulations. Comparison of simulated and experimentally obtained deformations show that in general the agreement is acceptable on a qualitative level. However, the simulations predict deformations...

  3. Electrowetting-driven spreading and jumping of drops in oil (United States)

    Hong, Jiwoo; Lee, Sang Joon


    Electrowetting-based practical applications include digital microfluidics, liquid lenses, and reflective displays. Most of them are performed in water/oil system, because oil medium reduces the contact-angle hysteresis and prevents drop evaporation. In this study, the effects of drop volume, oil viscosity, and applied voltage on the dynamic behaviors of spreading drops, such as transition of spreading pattern and response time, are investigated. Interestingly, jumping phenomena of drops are observed in oil when the applied voltage is turned off after reaching the electrowetted equilibrium radius of drops. A numerical model to predict the transient behavior of jumping drops is formulated based on the phase-field method. The numerical results for the transient deformation of jumping drops show quantitative agreement with the experimental results.

  4. Asymmetry of Drop Impacts on Patterned Hydrophobic Microstructures (United States)

    Willmott, Geoff; Robson, Simon; Broom, Matheu


    When a water drop falls on to a flat solid surface, asymmetries in the geometry of the spreading drop can be specifically determined by patterned surface microstructures. For hydrophobic (or superhydrophobic) micropillar arrays, the most important asymmetric mechanisms appear to be the surface energy of contact lines, and pathways for gas escaping from penetrated microstructure. In this presentation, static wetting and drop impact experiments will be discussed in relation to drop asymmetries. In addition to micropillar arrays, natural superhydrophobic surfaces (leaves) have been studied, and may suggest possibilities for controlling drop impacts in applications. Some of the clearest large scale drop asymmetries on leaves, which are similar to those associated with low drop impact contact times on synthetic surfaces, appear to be caused by features which generate high contact angle hysteresis, and are therefore indicative of poor superhydrophocity.

  5. Drop Pinch-Off for Discrete Flows from a Capillary

    Directory of Open Access Journals (Sweden)

    Wilson M.C.T.


    Full Text Available The problem of drop formation and pinch-off from a capillary tube under the influence of gravity has been extensively studied when the internal capillary pressure gradient is constant. This ensures a continuous time independent flow field inside the capillary tube typically of the Poiseuille flow type. Characteristic drop ejection behaviour includes: periodic drop ejection, drop ejection with associated satellite production, complex dripping, chaotic behaviour and jetting. It is well known that this characteristic behaviour is governed by the Weber (We and Ohnesorge (Oh numbers (for a given Bond number and may be delineated in a We verses Oh operability diagram. An in-depth physical understanding of drop ejection is also of great importance to industry where the tight control of drop size and ejection velocity are of critical importance in industrial processes such as sealants used in electronics assembly and inkjet printing. However, the use of such a continuous flow approach for drop ejection in industry is often impractical since such flows cannot be operator controlled. For this reason it is important to investigate so-called discrete pipe flows where the flow can be turned on and off at will. This means the flow inside the pipe is now time-dependent being controlled in a step-wise fashion. As a first stage in the investigation of drop pinch-off behaviour in discrete pipe flows this paper will study the critical pinch-off time required for drop ejection starting from a pendant drop. This is the discrete amount of time the pipe flow is turned on for in order for a drop to be ejected from the capillary. A Newtonian incompressible free-surface CFD flow code developed at the University of Leeds is used to investigate the critical pinch-off time for a range of internal pipe velocities (the central flow maximum in Poiseuille flow. It is found that the time required for drop ejection to occur decreases exponentially with internal pipe velocity

  6. Foot Drop: Looking Beyond Common Peroneal Nerve Palsy – A Neurophysiology Centre Experience

    LENUS (Irish Health Repository)

    Yap, SM


    Foot drop is a complex symptom with a considerable range in aetiology, severity and prognosis. We aim to characterise the aetiologies of foot drop and assess the diagnostic contribution of neurophysiologic testing (NCS\\/EMG). Retrospective review of consecutive referrals of foot drop to the Neurophysiology Department in Cork University Hospital was performed over a two year period (January 2012 to December 2013). Of a total of 59 referrals, common peroneal nerve (CPN) palsy comprised only slightly more than half of cases; 3(5%) have central origin; 3(5%) have motor neuron disease. Six (10%) have diabetes; 7(12%) have cancer; 5(8%) were bilateral. NCS\\/EMG altered initial working diagnosis in 14 out of 52 (27%) cases whereby initial diagnosis was provided. However one-third of all cases revealed additional coexistent pathology in an anatomic location remote to that of the primary diagnosis. Foot drop with central and proximal localisations are important and under recognised. NCS\\/EMG is valuable and also reveals additional pathology which warrants investigation

  7. Drop Impact on to Moving Liquid Pools (United States)

    Muñoz-Sánchez, Beatriz Natividad; Castrejón-Pita, José Rafael; Castrejón-Pita, Alfonso Arturo; Hutchings, Ian M.


    The deposition of droplets on to moving liquid substrates is an omnipresent situation both in nature and industry. A diverse spectrum of phenomena emerges from this simple process. In this work we present a parametric experimental study that discerns the dynamics of the impact in terms of the physical properties of the fluid and the relative velocity between the impacting drop and the moving liquid pool. The behaviour ranges from smooth coalescence (characterized by little mixing) to violent splashing (generation of multiple satellite droplets and interfacial vorticity). In addition, transitional regimes such as bouncing and surfing are also found. We classify the system dynamics and show a parametric diagram for the conditions of each regime. This work was supported by the EPSRC (Grant EP/H018913/1), the Royal Society, Becas Santander Universidades and the International Relationships Office of the University of Extremadura.

  8. Capture of cenospheres by evaporating drops (United States)

    Leong, K. H.; Ochs, Harry T.; Beard, K. V.

    The capture efficiency of evaporating cloud drops between 60 and 100 μm radius has been measured for 2 μm radius lithium carbonate hollow particles (cenospheres). Since the effective particle density is low compared to a 2-μm solid particle the cenospheres have reduced sedimentation speeds and a negligible inertial capture efficiency. The particles are sufficiently large ( Kn = 0.03) so that the phoretic theory in the slip regime ( Kn < 0.1) should apply. The measured capture efficiencies are significantly above the theoretical computations. There is some evidence to suggest that thermophoresis may be underestimated in the computations. This assessment is contigent on attributing the discrepancy between theory and experiment to the theoretical description of phoresis or its application to our experiment.

  9. Effect of Bilineaster Drop on Neonatal Hyperbilirubinemia

    Directory of Open Access Journals (Sweden)

    Zahra Ameli


    Full Text Available Background: Hyperbilirubinemia is considered one of the most prevalent problems in newborns. Phototherapy, exchange transfusion, and herbal medicine are common therapeutic approaches for preventing any neurologic damage in infants with neonatal jaundice. However, herbal medicine is less commonly used. Aim: This study aimed to investigate the effect of bilineaster drop on neonatal hyperbilirubinemia. Method: This study was a randomized clinical trial conducted on 98 term neonates (aged 2-14 days with neonatal jaundice admitted to Ghaem Hospital of Mashhad, Iran, during 2015. These newborns were randomly assigned into intervention (phototherapy and bilineaster drop and control (only phototherapy groups. Total and direct serum bilirubin levels were measured at the time of admission and then 12, 24, 36, and 48 h after treatment. Data were analyzed using independent t-test and repeated measures ANOVA through Stata software (Version 12. Results: The mean ages of the newborns at the time of admission were 6.2 ±2.5 and 6.04 ±2.4 days in the intervention and control groups, respectively. The intervention group showed higher reduction in mean duration of hospital stay, readmission rate, and bilirubin levels 12 and 24 h after the intervention, compared to the control group (P>0.001. However, the two groups demonstrated no statistically significant difference 36 h and 48 h after the intervention (P=0.06, P=0.22, respectively. Repeated measures ANOVA indicated that the intervention had no significant effect on the reduction trend of bilirubin levels (P=0.10 [total], P=0.06 [indirect] in both groups. Nonetheless, bilirubin levels significantly diminished in both groups over time (P

  10. Rapid transitions

    Energy Technology Data Exchange (ETDEWEB)

    Hamrin, J.G.


    Solar energy programs are entering a critical transitional period as we move from the initial marketing of solar technologies into a phase of widespread commercialization. We face the dual challenge of trying to get enough solar systems in place fast enough to prove solar is a viable alternative, while trying to ensure the systems are designed and installed properly, proving the energy savings as promised. This is a period of both great opportunity and high risk as the field becomes crowded with new solar cheerleaders and supporters but seldom enough competent players. The status of existing and proposed programs for the accelerated commercialization of solar energy in California is described.

  11. Evaluation of the in vitro ocular toxicity of the fortified antibiotic eye drops prepared at the Hospital Pharmacy Departments

    Directory of Open Access Journals (Sweden)

    Anxo Fernández-Ferreiro


    Full Text Available The use of parenteral antibiotic eye drop formulations with non-marketed compositions or concentrations, commonly called fortified antibiotic eye drops, is a common practice in Ophthalmology in the hospital setting. The aim of this study was to evaluate the in vitro ocular toxicity of the main fortified antibiotic eye drops prepared in the Hospital Pharmacy Departments. We have conducted an in vitro experimental study in order to test the toxicity of gentamicin, amikacin, cefazolin, ceftazidime, vancomycin, colistimethate sodium and imipenem-cilastatin eye drops; their cytotoxicity and acute tissue irritation have been evaluated. Cell-based assays were performed on human stromal keratocytes, using a cell-based impedance biosensor system [xCELLigence Real-Time System Cell Analyzer (RTCA], and the Hen’s Egg Test for the ocular irritation tests. All the eye drops, except for vancomycin and imipenem, have shown a cytotoxic effect dependent on concentration and time; higher concentrations and longer exposure times will cause a steeper decline in the population of stromal keratocytes. Vancomycin showed a major initial cytotoxic effect, which was reverted over time; and imipenem appeared as a non-toxic compound for stromal cells. The eye drops with the highest irritating effect on the ocular surface were gentamicin and vancomycin. Those antibiotic eye drops prepared at the Hospital Pharmacy Departments included in this study were considered as compounds potentially cytotoxic for the ocular surface; this toxicity was dependent on the concentration used

  12. Drop impact on a liquid-liquid interface (United States)

    Mohamed-Kassim, Zulfaa; Longmire, Ellen K.


    The effects of Reynolds number (Re) on the gravity-driven impact of a single drop onto a liquid-liquid interface were studied experimentally using the particle image velocimetry method. The liquid beneath the interface was identical to the drop liquid. Two liquids with different viscosities were used as the ambient above the interface resulting in viscosity ratios (drop to ambient) of 0.14 and 0.33. Index matching and a slight camera inclination were employed to eliminate optical distortion. Image planes were captured at a rate of 500 Hz, and velocity fields were determined from consecutive images. The flow Reynolds numbers based on drop impact velocity and ambient viscosity were 20 and 68 for the lower and higher viscosity ratios, respectively. During the approach toward the interface, the drop shape was more oblate for the higher Re case. At the same time, viscous stresses generated a vortex ring inside each drop and a wake behind it. Each wake contained a detached ring of similar sign to the ring inside the drop. The subsequent deformation of the drop and the interface due to impact was observed to be more radical in the higher Re case. The impingement and shearing of the trailing wake on the upper surface of each drop played a significant role in dissipating the vorticity inside both drops, and the vorticity dissipated faster for lower Re.

  13. Surface wetting effects on drop passage through a confining orifice (United States)

    Bordoloi, Ankur; Longmire, Ellen


    The motion of gravity-driven drops (Bo ~ 2-10) through a sharp-edged confining orifice is studied in a liquid/liquid system for both hydrophobic (HPB) and hydrophilic (HPL) orifice surfaces. The drop interface is tracked by high-speed imaging, and fluid velocity fields are obtained by PIV. When a drop impacts the leading edge of the orifice, the drop fluid contacts the solid surface immediately, and the resulting interfacial contact lines begin propagating away from the edge. The final drop outcome (capture, release or break-up) is influenced by the motion of the contact lines as well as the contact force between the drop fluid and the orifice surface. In the HPB case, the contact line motion is limited, and the contact force acting against drop passage is weak. In the HPL case, the contact line motion strongly inhibits drop passage by spreading fluid across the upper surface of the orifice plate. For drops that break into multiple volumes, the wettability influences both the break-up location and fractional volume of the resulting satellite drop. Supported by DOE (DOE EERE-PMC-10EE0002764).

  14. [Objective evaluation of applying eye drops by elderly patients]. (United States)

    Colomé-Campos, J; Martínez-Salcedo, I; Martorell-Hallado, M C; Romero-Aroca, P


    To objectively evaluate the ability and skills of patients older than 65 years to successfully administer a topical ocular eye drop. A prospective study was conducted on a group of 25 patients with a diagnosis of dry eye or glaucoma, undergoing daily treatment with eye drops for at least one year. The procedure was recorded with a video camera at the time of the application. Of the total, 64% were diagnosed with glaucoma and 36% with dry eye. Almost half (44%) needed a single attempt to apply the drop, and 56% required 2 attempts. In terms of the number of eye drops applied, 52% managed with a single drop, 16% 2 drops, a 12% 3 drops, and 20% 4 or more eye drops. Areas where the eye drop was deposited in the first attempt was, 32% into the conjunctival sac, 32% on the outer corner of the eye, 8% in the inner angle, 8% in the nose, 12% on the cheek, 8% in other areas. Self-administration of eye drops by the elderly is a complex activity that can have an effect on the expected results. Copyright © 2013 Sociedad Española de Oftalmología. Published by Elsevier Espana. All rights reserved.

  15. The Influence of Concentrace Mineral Drops on Performance Broiler

    Directory of Open Access Journals (Sweden)

    Sigit Mugiyono


    Full Text Available A research has been conducted in Experimental Farm Faculty of Animal Husbandry Unsoed from July 1 st until August 15 th, 1996. The purpose want to study the influence of CMD supplementation in drinking water consists of M0 = control; M1 = 0.5 drops/1000 cc, M2 = 1 drops/1000 cc; M3 = 1.5 drops/1000 cc and M4 = 2 drops/1000cc. The performance observed were growth, body weight, feed consumption, feed conversion, drinking water consumption; and income over feed and mineral cost (IOFMC. The research involved 100 broiler chickens divided that CMD supplementation until 2 drops/1000cc did not significantly affect on the performance of broiler chickens except in income over feed and mineral cost (P<0.05. (Animal Production 1(2: 56-62 (1999 Key Words: broiler, concentrace mineral drops, performance.

  16. Drop Impact on Textile Material: Effect of Fabric Properties

    Directory of Open Access Journals (Sweden)

    Romdhani Zouhaier


    Full Text Available This paper presents an experimental study of impact of water drop on a surface in a spreading regime with no splashing. Three surfaces were studied: virgin glass, coating film and woven cotton fabric at different construction parameters. All experiments were carried out using water drop with the same free fall high. Digidrop with high-resolution camera is used to measure the different parameters characterising this phenomenon. Results show an important effect of the height of the free fall on the drop profile and the spreading behaviour. An important drop deformation at the surface impact was observed. Then, fabric construction as the weft count deeply affects the drop impact. For plain weave, an increase of weft count causes a decrease in penetration and increase in the spreading rate. The same result was obtained for coated fabric. Therefore, the impact energy was modified and the drop shape was affected, which directly influenced the spreading rate.

  17. Low stress drops observed for aftershocks of the 2011 Mw 5.7 Prague, Oklahoma, earthquake (United States)

    Sumy, Danielle F.; Neighbors, Corrie J.; Cochran, Elizabeth S.; Keranen, Katie M.


    In November 2011, three Mw ≥ 4.8 earthquakes and thousands of aftershocks occurred along the structurally complex Wilzetta fault system near Prague, Oklahoma. Previous studies suggest that wastewater injection induced a Mw 4.8 foreshock, which subsequently triggered a Mw 5.7 mainshock. We examine source properties of aftershocks with a standard Brune-type spectral model and jointly solve for seismic moment (M0), corner frequency (f0), and kappa (κ) with an iterative Gauss-Newton global downhill optimization method. We examine 934 earthquakes with initial moment magnitudes (Mw) between 0.33 and 4.99 based on the pseudospectral acceleration and recover reasonable M0, f0, and κ for 87 earthquakes with Mw 1.83–3.51 determined by spectral fit. We use M0 and f0 to estimate the Brune-type stress drop, assuming a circular fault and shear-wave velocity at the hypocentral depth of the event. Our observations suggest that stress drops range between 0.005 and 4.8 MPa with a median of 0.2 MPa (0.03–26.4 MPa with a median of 1.1 MPa for Madariaga-type), which is significantly lower than typical eastern United States intraplate events (>10 MPa). We find that stress drops correlate weakly with hypocentral depth and magnitude. Additionally, we find the stress drops increase with time after the mainshock, although temporal variation in stress drop is difficult to separate from spatial heterogeneity and changing event locations. The overall low median stress drop suggests that the fault segments may have been primed to fail as a result of high pore fluid pressures, likely related to nearby wastewater injection.

  18. Mechanisms and Control of Self-Emulsification upon Freezing and Melting of Dispersed Alkane Drops. (United States)

    Valkova, Zhulieta; Cholakova, Diana; Tcholakova, Slavka; Denkov, Nikolai; Smoukov, Stoyan K


    Emulsification requires drop breakage and creation of a large interfacial area between immiscible liquid phases. Usually, high-shear or high-pressure emulsification devices that generate heat and increase the emulsion temperature are used to obtain emulsions with micrometer and submicrometer droplets. Recently, we reported a new, efficient procedure of self-emulsification (Tcholakova et al. Nat. Commun. 2017, 8, 15012), which consists of one to several cycles of freezing and melting of predispersed alkane drops in a coarse oil-in-water emulsion. Within these freeze-thaw cycles of the dispersed drops, the latter burst spontaneously into hundreds and thousands of smaller droplets without using any mechanical agitation. Here, we clarify the main factors and mechanisms, which drive this self-emulsification process, by exploring systematically the effects of the oil and surfactant types, the cooling rate, and the initial drop size. We show that the typical size of the droplets, generated by this method, is controlled by the size of the structural domains formed in the cooling-freezing stage of the procedure. Depending on the leading mechanism, these could be the diameter of the fibers formed upon drop self-shaping or the size of the crystal domains formed at the moment of drop-freezing. Generally, surfactant tails that are 0-2 carbon atoms longer than the oil molecules are most appropriate to observe efficient self-emulsification. The specific requirements for the realization of different mechanisms are clarified and discussed. The relative efficiencies of the three different mechanisms, as a function of the droplet size and cooling procedure, are compared in controlled experiments to provide guidance for understanding and further optimization and scale-up of this self-emulsification process.

  19. DROpS: an object of learning in computer simulation of discrete events

    Directory of Open Access Journals (Sweden)

    Hugo Alves Silva Ribeiro


    Full Text Available This work presents the “Realistic Dynamics Of Simulated Operations” (DROpS, the name given to the dynamics using the “dropper” device as an object of teaching and learning. The objective is to present alternatives for professors teaching content related to simulation of discrete events to graduate students in production engineering. The aim is to enable students to develop skills related to data collection, modeling, statistical analysis, and interpretation of results. This dynamic has been developed and applied to the students by placing them in a situation analogous to a real industry, where various concepts related to computer simulation were discussed, allowing the students to put these concepts into practice in an interactive manner, thus facilitating learning

  20. Drop Characteristics of non-Newtonian Impinging Jets at High Generalized Bird-Carreau Jet Reynolds Numbers (United States)

    Sojka, Paul E.; Rodrigues, Neil S.


    The current study investigates the drop characteristics of three Carboxymethylcellulose (CMC) sprays produced by the impingement of two liquid jets. The three water-based solutions used in this work (0.5 wt.-% CMC-7MF, 0.8 wt.-% CMC-7MF, and 1.4 wt.-% CMC-7MF) exhibited strong shear-thinning, non-Newtonian behavior - characterized by the Bird-Carreau rheological model. A generalized Bird-Carreau jet Reynolds number was used as the primary parameter to characterize the drop size and the drop velocity, which were measured using Phase Doppler Anemometry (PDA). PDA optical configuration enabled a drop size measurement range of approximately 2.3 to 116.2 μm. 50,000 drops were measured at each test condition to ensure statistical significance. The arithmetic mean diameter (D10) , Sauter mean diameter (D32) , and mass median diameter (MMD) were used as representative diameters to characterize drop size. The mean axial drop velocity Uz -mean along with its root-mean square Uz -rms were used to characterize drop velocity. Incredibly, measurements for all three CMC liquids and reference DI water sprays seemed to follow a single curve for D32 and MMD drop diameters in the high generalized Bird-Carreau jet Reynolds number range considered in this work (9.21E +03 Initiative Grant Number W911NF-08-1-0171.

  1. Student Drop Tower Competitions: Dropping In a Microgravity Environment (DIME) and What If No Gravity? (WING) (United States)

    Hall, Nancy R.; Stocker, Dennis P.; DeLombard, Richard


    This paper describes two student competition programs that allow student teams to conceive a science or engineering experiment for a microgravity environment. Selected teams design and build their experimental hardware, conduct baseline tests, and ship their experiment to NASA where it is operated in the 2.2 Second Drop Tower. The hardware and acquired data is provided to the teams after the tests are conducted so that the teams can prepare their final reports about their findings.

  2. Drop impact and rebound dynamics on an inclined superhydrophobic surface. (United States)

    Yeong, Yong Han; Burton, James; Loth, Eric; Bayer, Ilker S


    Due to its potential in water-repelling applications, the impact and rebound dynamics of a water drop impinging perpendicular to a horizontal superhydrophobic surface have undergone extensive study. However, drops tend to strike a surface at an angle in applications. In such cases, the physics governing the effects of oblique impact are not well studied or understood. Therefore, the objective of this study was to conduct an experiment to investigate the impact and rebound dynamics of a drop at various liquid viscosities, in an isothermal environment, and on a nanocomposite superhydrophobic surface at normal and oblique impact conditions (tilted at 15°, 30°, 45°, and 60°). This study considered drops falling from various heights to create normal impact Weber numbers ranging from 6 to 110. In addition, drop viscosity was varied by decreasing the temperature for water drops and by utilizing water-glycerol mixtures, which have similar surface tension to water but higher viscosities. Results revealed that oblique and normal drop impact behaved similarly (in terms of maximum drop spread as well as rebound dynamics) at low normal Weber numbers. However, at higher Weber numbers, normal and oblique impact results diverged in terms of maximum spread, which could be related to asymmetry and more complex outcomes. These asymmetry effects became more pronounced as the inclination angle increased, to the point where they dominated the drop impact and rebound characteristics when the surface was inclined at 60°. The drop rebound characteristics on inclined surfaces could be classified into eight different outcomes driven primarily by normal Weber number and drop Ohnesorge numbers. However, it was found that these outcomes were also a function of the receding contact angle, whereby reduced receding angles yielded tail-like structures. Nevertheless, the contact times of the drops with the coating were found to be generally independent of surface inclination.

  3. Studying the field induced breakup of acoustically levitated drops (United States)

    Warschat, C.; Riedel, J.


    Coulomb fission of charged droplets (The terms drop and droplet are often used synonymous. Throughout this manuscript, to avoid confusion, the terms drop and droplet will be used for liquid spheres with radii in the millimeter range and the micrometer range, respectively. In our experiments, the first correspond to the parent drop while the latter describes the ejected progeny droplets.) is a well-studied natural phenomenon. Controlled droplet fission is already successfully employed in several technological applications. Still, since the occurring surface rupture relies on the exact understanding and description of the liquid gas boundary, some details are still under debate. Most empirical systematic studies observe falling micrometer droplets passing through the electric field inside a plate capacitor. This approach, although easily applicable and reliable, limits the experimental degrees of freedom regarding the observable time and the maximum size of the drops and can only be performed in consecutive individual observations of different subsequent drops. Here we present a novel setup to study the field induced breakup of acoustically levitated drops. The design does not bear any restrictions towards the temporal window of observation, and allows handling of drops of a tunable radius ranging from 10 μm to several millimeters and a real-time monitoring of one single drop. Our comprehensive study includes a time resolved visual inspection, laser shadowgraphy, laser induced fluorescence imaging, and ambient mass spectrometric interrogation of the nascent Taylor cone. The results shown for a millimeter sized drop, previously inaccessible for Coulomb fission experiments, are mostly comparable with previous results for smaller drops. The major difference is the time scale and the threshold potential of the drop rupture. Both values, however, resemble theoretically extrapolations to the larger radius. The technique allows for a systematic study of breakup behavior of

  4. Drop-out from a psychodynamic group psychotherapy outpatient unit. (United States)

    Jensen, Hans Henrik; Mortensen, Erik Lykke; Lotz, Martin


    BACKGROUND. Drop-out from psychotherapy is common and represents a considerable problem in clinical practice and research. Aim. To explore pre-treatment predictors of early and late drop-out from psychodynamic group therapy in a public outpatient unit for non-psychotic disorders in Denmark. Methods. Naturalistic design including 329 patients, the majority with mood, neurotic and personality disorders referred to 39-session group therapy. Predictors were socio-demographic and clinical variables, self-reported symptoms (Symptom Check List-90-Revised) and personality style (Millon Clinical Multiaxial Inventory-II). Drop-out was classified into early and late premature termination excluding patients who dropped out for external reasons. Results. Drop-out comprised 20.6% (68 patients) of the sample. Logistic regression revealed social functioning, vocational training, alcohol problems and antisocial behavior to be related to drop-out. However, early drop-outs had prominent agoraphobic symptoms, lower interpersonal sensitivity and compulsive personality features, and late drop-outs cognitive and somatic anxiety symptoms and antisocial personality features. Clinical and psychological variables accounted for the major part of variance in predictions of drop-out, which ranged from 15.6% to 19.5% (Nagelkerke Pseudo R-Square). Conclusion. Social functioning was consistently associated with drop-out, but personality characteristics and anxiety symptoms differentiated between early and late drop-out. Failure to discriminate between stages of premature termination may explain some of the inconsistencies in the drop-out literature. Clinical implications. Before selection of patients to time-limited psychodynamic groups, self-reported symptoms should be thoroughly considered. Patients with agoraphobic symptoms should be offered alternative treatment. Awareness of and motivation to work with interpersonal issues may be essential for compliance with group therapy.

  5. Electrowetting-enhanced microfluidic device for drop generation (United States)

    Gu, Hao; Malloggi, Florent; Vanapalli, Siva A.; Mugele, Frieder


    We integrated electrowetting into a microfluidic flow focusing device to study drop generation under the influence of electric fields. Using both the dispersed phase inlet pressure and the applied voltage as control parameters, we find that the range of drop sizes and the drop generation rate can be controlled in a much finer way than with hydrodynamics alone. In particular a "conical spray" regime occurring at a voltage of O(50 V) allows for continuous tuning of the (highly monodisperse) drop diameter from ≈5 to 50 μm at a fixed continuous flow rate.

  6. Reducing pressure drop in a baghouse using flow distributors. (United States)

    Chen, C J


    The pressure drop of ladder vanes in a baghouse could be reduced by decreasing the vane number and adjusting the inclined angle of the vane. Two types of flow distributors were utilized to test pressure drop caused by the structure of a baghouse. The pressure drops were measured by an inclined manometer under various filtration velocities. The purpose of this study is to understand the improvement effect of pressure drop saving for the traditional ladder vanes. Experimental results showed that the pressure drop of the Vane 3-1 configuration (flow distributor with three vanes perpendicular to the inlet flow) was higher than that of the Empty configuration (without flow distributors). The Vane 3-1 configuration could not reduce the pressure drop because of the barrier effect. By reducing the number and adjusting the angle of the vanes, the barrier effect was decreased, and the pressure drop of the Vane 2-1 configuration was much lower than that of the Vane 3-1 configuration. The largest difference in pressure drop between Vane 2-1 and Vane 3-1 was 1.702 cm w.g. at a filtration velocity of 4.17 cm/sec and, in terms of percentage, is 18.52% corresponding to a filtration velocity of 2.25 cm/sec. The improvement effect on the pressure drop saving for Vane 3-1 was significant.

  7. Substrate constraint modifies the Rayleigh spectrum of vibrating sessile drops. (United States)

    Chang, Chun-Ti; Bostwick, Joshua B; Steen, Paul H; Daniel, Susan


    In this work, we study the resonance behavior of mechanically oscillated, sessile water drops. By mechanically oscillating sessile drops vertically and within prescribed ranges of frequencies and amplitudes, a rich collection of resonance modes are observed and their dynamics subsequently investigated. We first present our method of identifying each mode uniquely, through association with spherical harmonics and according to their geometric patterns. Next, we compare our measured resonance frequencies of drops to theoretical predictions using both the classical theory of Lord Rayleigh and Lamb for free, oscillating drops, and a prediction by Bostwick and Steen that explicitly considers the effect of the solid substrate on drop dynamics. Finally, we report observations and analysis of drop mode mixing, or the simultaneous coexistence of multiple mode shapes within the resonating sessile drop driven by one sinusoidal signal of a single frequency. The dynamic response of a deformable liquid drop constrained by the substrate it is in contact with is of interest in a number of applications, such as drop atomization and ink jet printing, switchable electronically controlled capillary adhesion, optical microlens devices, as well as digital microfluidic applications where control of droplet motion is induced by means of a harmonically driven substrate.

  8. Pearls in running drops on an inclined glass substrate excited by Lamb waves. (United States)

    Liang, Wei; Tietze, Sabrina


    We demonstrate that pearling droplets will be released from droplets as they sliding down a partially wetting glass plate excited by Lamb waves. During the movement, we find that the transitions at generating pearling are independent of the drop size and depend only on a critical capillary number Ca. Further up, the position of the pearls must be at or around the droplet's advancing or receding end of the initial state.

  9. Clinical analysis of diclofenac sodium eye drops combined with sodium hyaluronate eye drops for dry eye after ophthalmic surgery

    Directory of Open Access Journals (Sweden)

    Li-Ping Liu


    Full Text Available AIM: To study and analyze the clinical efficacy of diclofenac sodium eye drops combined with sodium hyaluronate eye drops in treating dry eyes after ophthalmic surgery. METHODS: Totally 94 eyes from 94 patients with dry eyes were slected, and they were randomly divided into orbervation group and control group. Fouty-seven patients in the control group using conventional treatment combined with sodium hyaluronate eye drops. Other 47 patients in orbervation group were treated with diclofenac sodium eye drops on the basis of control group. We compared symptoms, fluorescein station, tear film break time, Schirmer Ⅰ test between the two groups.RESULTS: Compared with before treatment, patients of both groups with sympotom, fluorescein station score, BUT, and Schirmer Ⅰ test were significantly improved(PPPCONCLUSION: Diclofenac sodium eye drops combined with sodium hyaluronate eye drops have significant efficacy in treatment of dry eyes after ophthalmic surgery, which can effectively relieve clinical symptoms, improve BUT and Schirmer Ⅰ test.

  10. That's one small drop for Mankind...

    CERN Multimedia

    Anaïs Schaeffer


    In August, the members of an ISOLDE project called LOI88 successfully employed a new technique to study the interaction of metal ions in a liquid. It’s the first time that specific ions have been studied in a liquid medium - a technical achievement that opens promising doors for biochemistry.   In the heart of the LOI88 experiment: this is the point where the metal ions (from the left) enter the drop.  “More than half of the proteins in the human body contain metal ions such as magnesium, zinc and copper,” explains Monika Stachura, a biophysicist at the University of Copenhagen and the LOI88 project leader. “We know that these elements are crucial to a protein’s structure and function but their behaviour and interactions are not known in detail.” Detecting these ions directly in  a body-like environment is problematic as their closed atomic shells make them invisible to most spectroscopic techniques. However, using ...

  11. Career drop outs of young elite athletes

    Directory of Open Access Journals (Sweden)

    Petra Fišer


    Full Text Available The main problem of the study was to examine the characteristics of sports career drop outs of young elite sportswomen and their adaptation to the post-sport life. The sample included 20 ex-young elite sportswomen, who had brought their successful sport careers to an end before the age of 19. We used a modified interview about sports career termination (Cecić Erpič, 1998 for the investigation of the characteristics of their sports careers. To examine the caracteristics of sport careers we used frequency analysis and cluster analysis. The results showed that the participants mostly stated more than one reason for the termination of their career. The most common reasons for career termination were: lack of motivation, bad relations with trainers or co-competitors and dedication to school or education. After the end of a sports career most of the young sportswomen stayed actively in touch with sport, either as trainers, judges, or they remained engaged in sports for recreation.


    Dwyer, Rachel E; Hodson, Randy; McLoud, Laura


    For many young Americans, access to credit has become critical to completing a college education and embarking on a successful career path. Young people increasingly face the trade-off of taking on debt to complete college or foregoing college and taking their chances in the labor market without a college degree. These trade-offs are gendered by differences in college preparation and support and by the different labor market opportunities women and men face that affect the value of a college degree and future difficulties they may face in repaying college debt. We examine these new realities by studying gender differences in the role of debt in the pivotal event of graduating from college using the 1997 cohort of the national longitudinal Survey of youth. In this article, we find that women and men both experience slowing and even diminishing probabilities of graduating when carrying high levels of debt, but that men drop out at lower levels of debt than do women. We conclude by theorizing that high levels of debt are one of the mechanisms that sort women and men into different positions in the social stratification system.

  13. Assessment of eye drop instillation technique in glaucoma patients

    Directory of Open Access Journals (Sweden)

    Beatriz Fiuza Gomes

    Full Text Available ABSTRACT Purpose: To study the technique of eye drop instillation in glaucoma patients and identify independent factors that may influence their performance. Methods: In this cross-sectional study, 71 consecutive patients with glaucoma or ocular hypertension, self-administering topical anti-glaucoma medications for ≥6 months were evaluated. All patients instilled a tear substitute into the eye with the worst eyesight using the technique normally used at home. The following parameters were evaluated: age, number of years receiving treatment with ocular hypotensive eye drops, time spent to instill the first drop, number of drops instilled, correct location of the eye drops, contact of the bottle with the eye, closing of the eyelids or occlusion of the tear punctum, and asepsis of the hands. Results: The mean age of the patients was 66 ± 10.8 years, and patients were on ocular hypotensive drugs for 11.3 ± 7.3 (range, 2-35 years. Only 28% of the patients were able to correctly instill the eye drops (squeeze out 1 drop and instill it into the conjunctival sac without bottle tip contact. Touching the tip of the bottle to the globe or periocular tissue occurred in 62% of the patients. In 49% of the patients, the eye drops fell on the eyelids or cheek. Two or more drops were squeezed by 27% of the patients. Conclusions: The majority of glaucoma patients were unable to correctly instill eye drops. Age was an independent factor associated with eye drop instillation performance.

  14. Combining core drop policy and edge determinant threshold in TCP over OBS networks with retransmission (United States)

    Peng, Shuping; Li, Zhengbin; He, Yongqi; Xu, Anshi


    We proposed a novel drop policy in the core nodes which is combined with the determinant strategy in the ingress edge nodes. The proposed drop policy is based on the field of Hop Number (HN) taken by the burst control packets, which is introduced to determine which burst should be dropped when the contention happened in the core nodes. In the drop policy, the long-hop traffic is given the high priority, and most of the retransmitted traffic is left to be short-hop traffic. Therefore, there is a trade-off between the short-hop traffic and the long-hop traffic. The determinant strategy in the edge nodes is an initialized threshold, Retransmission Number Threshold (RNT), which is introduced to determine whether to start a retransmission operation when NAK is received. The unnecessary retransmissions in the network are limited, and the burst loss rate is reduced. The mechanism also takes the upper layer, TCP layer, into account. When the network has already been in the state of real congestion, the retransmission will only deteriorate the network performance. In the case, the combined mechanism leaves the retransmission process to the TCP layer. It can improve the network performance cost-effectively.

  15. Direct Numerical Study of a Molten Metal Drop Solidifying on a Cold Plate with Different Wettability

    Directory of Open Access Journals (Sweden)

    Truong V. Vu


    Full Text Available This paper presents a direct numerical simulation of solidification of a molten metal drop on a cold plate with various wettability by an axisymmetric front-tracking method. Because of the plate kept at a temperature below the fusion value of the melt, a thin solid layer forms at the plate and evolves upwards. The numerical results show that the solidifying front is almost flat except near the triple point with a high solidification rate at the beginning and final stages of solidification. Two solid-to-liquid density ratios ρsl = 0.9 (volume change and 1.0 (no change in volume, with two growth angles φ0 = 0° and 12° are considered. The presence of volume change and a non-zero growth angle results in a solidified drop with a conical shape at the top. The focusing issue is the effects of the wettability of the plate in terms of the contact angle φ0. Increasing the contact angle in the range of 45° to 120° increases time for completing solidification, i.e., solidification time. However, it has a minor effect on the conical angle at the top of the solidified drop and the difference between the initial liquid and final solidified heights of the drop. The effects of the density ratio and growth angle are also presented.

  16. Electrowetting-driven oscillating drops sandwiched between two substrates

    NARCIS (Netherlands)

    Mampallil Augustine, Dileep; Eral, Burak; Staicu, A.D.; Mugele, Friedrich Gunther; van den Ende, Henricus T.M.


    Drops sandwiched between two substrates are often found in lab-on-chip devices based on digital microfluidics. We excite azimuthal oscillations of such drops by periodically modulating the contact line via ac electrowetting. By tuning the frequency of the applied voltage, several shape modes can be

  17. Vortex Shedding and Depinning of Wind-Forced Liquid Drops (United States)

    Simon, Roger; White, Edward


    Water drops adhere to solid substrates but can depin when wind forcing exceeds the adhesion force provided by surface tension. Schmucker and White (2012.DFD.M4.6) measured critical wind forcing limits for high-Reynolds-number airflow forcing and found a critical constant Weber number, Wecrit = 8.0 , for a range of drop Bond numbers. This work seeks to identify what behavior is associated with Wecrit = 8.0 and why wind-forced drops depin when they do. One hypothesis suggests that, at high Reynolds numbers, drops depin when their interface natural frequency matches the frequency of air vortex shedding in the separated drop wake. We investigate whether a resonance between vortex shedding and drop interface oscillations is involved with depinning. We measure the shedding frequencies behind solid protuberances of the same size as typical drops and, separately, water-drop interface frequencies. We compare our measured values under different flow conditions to establish whether shedding and interface resonance are related to depinning. 1Supported by the National Science Foundation through Grant CBET-1605947.

  18. Liquid-gas mass transfer at drop structures. (United States)

    Matias, Natércia; Nielsen, Asbjørn Haaning; Vollertsen, Jes; Ferreira, Filipa; Matos, José Saldanha


    Over the last decades, considerable progress has been made in the understanding of the sulfur cycle in sewer systems. In spite of a wealth of experimental and field studies that have addressed the release of hydrogen sulfide from free surface flows in gravity sewers and the corresponding air-water mass transfer, little is known about hydrogen sulfide emission under highly turbulent conditions (e.g., drop structures, hydraulic jumps). In this study, experimental work was carried out to analyze the influence of characteristics of drops on reaeration. Physical models were built, mimicking typical sewer drop structures and allowing different types of drops, drop heights, tailwater depths and flow rates. In total, 125 tests were performed. Based on their results, empirical expressions translating the relationship between the mass transfer of oxygen and physical parameters of drop structures were established. Then, by applying the two-film theory with two-reference substances, the relation to hydrogen sulfide release was defined. The experiments confirmed that the choice of the type of drop structure is critical to determine the uptake/emission rates. By quantifying the air-water mass transfer rates between free-fall and backdrop types of drop, the latter resulted in considerably lower oxygen uptake rates.

  19. Cathode potential drop in the channel of a magnetoplasma compressor

    Energy Technology Data Exchange (ETDEWEB)

    Shubin, A.P.


    Calculations are carried out for the dissipationless plasma flow in the channel of a magnetoplasma compressor when there is a potential drop near the cathode. This drop appears when the current is carried by ions as the result of the disappearance of ions at the cathode.

  20. Maximal air bubble entrainment at liquid-drop impact

    NARCIS (Netherlands)

    Bouwhuis, W.; van der Veen, Roeland; Tran, Tuan; Keij, D.L.; Winkels, K.G.; Peters, I.R.; van der Meer, Roger M.; Sun, Chao; Snoeijer, Jacobus Hendrikus; Lohse, Detlef


    At impact of a liquid drop on a solid surface, an air bubble can be entrapped. Here, we show that two competing effects minimize the (relative) size of this entrained air bubble: for large drop impact velocity and large droplets, the inertia of the liquid flattens the entrained bubble, whereas for

  1. Oscillating and star-shaped drops levitated by an airflow

    NARCIS (Netherlands)

    Bouwhuis, W.; Winkels, K.G.; Peters, I.R.; Brunet, P.; van der Meer, Roger M.; Snoeijer, Jacobus Hendrikus


    We investigate the spontaneous oscillations of drops levitated above an air cushion, eventually inducing a breaking of axisymmetry and the appearance of “star drops”. This is strongly reminiscent of the Leidenfrost stars that are observed for drops floating above a hot substrate. The key advantage

  2. Electrowetting-driven oscillating drops sandwiched between two substrates (United States)

    Mampallil, Dileep; Burak Eral, H.; Staicu, Adrian; Mugele, Frieder; van den Ende, Dirk


    Drops sandwiched between two substrates are often found in lab-on-chip devices based on digital microfluidics. We excite azimuthal oscillations of such drops by periodically modulating the contact line via ac electrowetting. By tuning the frequency of the applied voltage, several shape modes can be selected one by one. The frequency of the oscillations is half the frequency of the contact angle modulation by electrowetting, indicating a parametric excitation. The drop response to sinusoidal driving deviates substantially from sinusoidal behavior in a “stop and go” fashion. Although our simple theoretical model describes the observed behavior qualitatively, the resonances appear at lower frequencies than expected. Moreover, the oscillations produce a nonperiodic fluid transport within the drop with a typical velocity of 1 mm/s. In digital microfluidic devices, where the typical drop size is less than 1 mm, this flow can result in very fast mixing on the spot.

  3. Tunable transport of drops on a vibrating inclined fiber

    CERN Document Server

    Bick, Alison; Sauret, Alban; Stone, Howard A


    Transport of liquid drops in fibrous media occurs in various engineering systems such as fog harvesting or cleaning of textiles. The ability to tune or to control liquid movement can increase the system efficiency and enable new engineering applications. In this Letter, we experimentally investigate how partially wetting drops on a single fiber can be manipulated by vibrating the fiber. We show that a sliding motion along the fiber or a dripping of the drop can be triggered by standing waves. We identify the conditions on the drop volume, the fiber tilt angle and the amplitude and frequency of oscillations to observe these different behaviors. Finally, we experimentally illustrate that vibrations can be used to control the transport and the collection of water drops along a fiber using a combination of the sliding and dripping transitions.

  4. Silicon wavelength-selective partial-drop broadcast filter bank. (United States)

    Su, Zhan; Cherchi, Matteo; Timurdogan, Erman; Sun, Jie; Moresco, Michele; Leake, Gerald; Coolbaugh, Douglas; Watts, Michael R


    We propose an approach to a wavelength-selective 1×N port optical broadcast network demonstrating the approach in a 1×8 port parallel optical drop filter bank utilizing adiabatic micro-ring tunable filters. The micro-ring filters exhibit first-order 92.7±3.7 GHz full width at half-maximum bandwidths with a 36.2 nm free spectral range, low-drop power variation (0.11 dB), and aggregate excess loss of only 1.1 dB in all drop ports. Error-free operation at a 10 Gbit/s data rate is achieved for all eight drop ports with less than a 0.5 dB power penalty among the ports. This wavelength-selective parallel-drop approach serves as a building block for on-chip all-to-all communication networks.

  5. Capillary-inertial colloidal catapults upon drop coalescence (United States)

    Chavez, Roger L.; Liu, Fangjie; Feng, James J.; Chen, Chuan-Hua


    Surface energy released upon drop coalescence is known to power the self-propelled jumping of liquid droplets on superhydrophobic solid surfaces, and the jumping droplets can additionally carry colloidal payloads toward self-cleaning. Here, we show that drop coalescence on a spherical particle leads to self-propelled launching of the particle from virtually any solid surface. The main prerequisite is an intermediate wettability of the particle, such that the momentum from the capillary-inertial drop coalescence process can be transferred to the particle. By momentum conservation, the launching velocity of the particle-drop complex is proportional to the capillary-inertial velocity based on the drop radius and to the fraction of the liquid mass in the total mass. The capillary-inertial catapult is not only an alternative mechanism for removing colloidal contaminants, but also a useful model system for studying ballistospore launching.

  6. Building micro-soccer-balls with evaporating colloidal fakir drops (United States)

    Gelderblom, Hanneke; Marín, Álvaro G.; Susarrey-Arce, Arturo; van Housselt, Arie; Lefferts, Leon; Gardeniers, Han; Lohse, Detlef; Snoeijer, Jacco H.


    Drop evaporation can be used to self-assemble particles into three-dimensional microstructures on a scale where direct manipulation is impossible. We present a unique method to create highly-ordered colloidal microstructures in which we can control the amount of particles and their packing fraction. To this end, we evaporate colloidal dispersion drops from a special type of superhydrophobic microstructured surface, on which the drop remains in Cassie-Baxter state during the entire evaporative process. The remainders of the drop consist of a massive spherical cluster of the microspheres, with diameters ranging from a few tens up to several hundreds of microns. We present scaling arguments to show how the final particle packing fraction of these balls depends on the drop evaporation dynamics, particle size, and number of particles in the system.

  7. Coalescence and noncoalescence of sessile drops: impact of surface forces. (United States)

    Karpitschka, Stefan; Hanske, Christoph; Fery, Andreas; Riegler, Hans


    Due to capillarity, sessile droplets of identical liquids will instantaneously fuse when they come in contact at their three-phase lines. However, with drops of different, completely miscible liquids, instantaneous coalescence can be suppressed. Instead, the drops remain in a state of noncoalescence for some time, with the two drop bodies connected only by a thin neck. The reason for this noncoalescence is the surface tension difference, Δγ, between the liquids. If Δγ is sufficiently large, then it induces a sufficiently strong Marangoni flow, which keeps the main drop bodies temporarily separated. Studies with spreading drops have revealed that the boundary between instantaneous coalescence and noncoalescence is sharp (Karpitschka, S.; Riegler, H. J. Fluid. Mech. 2014, 743, R1). The boundary is a function of two parameters only: Δγ and Θ(a), the arithmetic mean of the contact angles in the moment of drop-drop contact. It appears plausible that surface forces (the disjoining pressure) could also influence the coalescence behavior. However, in experiments with spreading drops, surface forces always promote coalescence and their influence might be obscured. Therefore, we present here coalescence experiments with partially wetting liquids and compare the results to the spreading case. We adjust different equilibrium contact angles (i.e., different surface forces) with different substrate surface coatings. As for spreading drops, we observe a sharp boundary between regimes of coalescence and noncoalescence. The boundary follows the same power law relation for both partially and completely wetting cases. Therefore, we conclude that surface forces have no significant, explicit influence on the coalescence behavior of sessile drops from different miscible liquids.

  8. Extension of in-situ stress test analysis to rapid hole evacuation at Yucca Mountain due to a network of open conduits

    Energy Technology Data Exchange (ETDEWEB)

    Davies, J.B.


    Yucca Mountain is underlain by tuffaceous rocks that are highly fractured and jointed. During drilling of bore-holes at Yucca Mountain there were numerous occurrences of lost circulation when whole mud was taken by the formation. This evidence suggests that parts of Yucca Mountain are controlled hydrologicaly by a network of open conduits along the existing joints and fractures. Also at Yucca Mountain, stress tests have been performed in-situ by charging a small section along the boreholes with an excess pressure head of water. For many of these tests, the initial drop in water head was so rapid that within seconds up to hundreds of meters of fall had occurred. The opening of fractures as the excess head increases has previously been proposed as an important factor in explaining the shape of the stress test curves at lower pressures. We propose that such induced hydraulic fractures, under increasing water heads, can grow to a length sufficient to intersect the existing network of open joints and fractures. We extend our previous model to incorporate flow out along these open conduits and examine the initial rapid drop in terms of these extended models. We show that this rapid evacuation model fits the observed data from many slug tests in wells in the vicinity of Yucca Mountain. This result is confirmation of the drilling evidence that a network of open conduits exists at various depths below the water table and over a large geographic region around Yucca Mountain.

  9. IR optical fiber-based noncontact pyrometer for drop tube instrumentation (United States)

    May, R. G.; Moneyhun, S.; Saleh, W.; Sudeora, S.; Claus, R. O.; Buoncristiani, A. M.


    The design of a two color pyrometer with infrared optical fiber bundles for collection of the infrared radiation is described. The pyrometer design is engineered to facilitate its use for measurement of the temperature of small, falling samples in a microgravity materials processing experiment using a 100 meter long drop tube. Because the samples are small and move rapidly through the field of view of the pyrometer, the optical power budget of the detection system is severly limited. Strategies for overcoming this limitation are discussed.

  10. Novel plasminogen and hyaluronate sodium eye drop formulation for a patient with ligneous conjunctivitis. (United States)

    Conforti, Franca Manganelli; Di Felice, Giovina; Bernaschi, Paola; Bartuli, Andrea; Bianco, Giuseppe; Simonetti, Alessandra; Buzzonetti, Luca; Valente, Paola; Corsetti, Tiziana


    The development, analysis, and first clinical use of a novel eye drop formulation of plasminogen and hyaluronate sodium for the treatment of a patient with ligneous conjunctivitis (LC) are described. LC is a chronic inflammatory disorder of the eye that can in rare cases lead to corneal involvement and subsequent blindness. Topically administered plasminogen is an effective treatment for LC; however, the lack of a specific and validated formulation of plasminogen for topical treatment can constitute a gap in the quality of care. A novel formulation of plasminogen and hyaluronate sodium for the treatment of LC was developed by combining commercially available products. Through a series of tests, including microbiological, viscosity, and pH analyses, the novel eye drop formulation was demonstrated to have constant activity (3.3 IU/mL or greater), to be microbiologically stable (i.e., sterile), and to be safe enough for daily administration. The first clinical application of the novel eye drop formulation was in the case of a nine-year-old girl with LC affecting both eyes. Initially, the girl's parents administered two drops every three hours to the left eye each day while the girl was awake. On examination after 30 days of daily use of the eye drop formulation, the patient was found to have a clear cornea and no membrane development on the conjunctiva; the formulation was subsequently administered in both eyes, with positive results. A new formulation of plasminogen plus hyaluronate sodium was developed, tested, and used successfully in a girl with LC. Copyright © 2016 by the American Society of Health-System Pharmacists, Inc. All rights reserved.

  11. Efficacy of an eye drop mixture for pupillary dilatation: A randomized comparative study. (United States)

    Bhurayanontachai, Patama; Saengkaew, Suwapat; Apiromruck, Penjamaporn

    Pupillary dilatation with three types of eye drops is used regularly in the clinic; however, a mixture of these drops in a single bottle may be more beneficial in reducing workloads and resources. This study compared the efficacy in pupillary dilatation between two protocols of dilating drop instillation. This prospective, randomized, comparative study included 30 eligible Thai patients. The patients randomly received preoperative pupillary dilatations by either the conventional protocol (1% tropicamide (T), 10% phenylephrine (P) and 0.1% diclofenac (D) in three separate bottles) or the fixed combination (TPD) protocol which had the three types of eye drops mixed in a single bottle in a ratio of 4:3:3. The chi-square test and independent t-test were used to analyze the data. The conventional protocol group and TPD protocol group each had 15 patients. Sixty minutes after the initial instillation, all patients in the TPD protocol and 13 patients (86.7%) in conventional protocol achieved at least 6mm in the shortest diameter. The mydriatic rate between protocols showed no difference. In patients who received the TPD protocol, the systemic effects on the mean arterial blood pressure and pulse rate decreased over time. The mixture of tropicamide, phenylephrine and diclofenac had a comparable efficacy for a pupillary dilatation to the conventional dilating drops in separate bottles. The systemic complications on blood pressure and arterial pulse of the TPD mixture were less than the conventional protocol. TCTR20130325001. Copyright © 2016 Spanish General Council of Optometry. Published by Elsevier España, S.L.U. All rights reserved.

  12. The mechanism of pollination drop withdrawal in Ginkgo biloba L.

    Directory of Open Access Journals (Sweden)

    Jin Biao


    Full Text Available Abstract Background The pollination drop (PD is a characteristic feature of many wind-pollinated gymnosperms. Although accumulating evidence shows that the PD plays a critical role in the pollination process, the mechanism of PD withdrawal is still unclear. Here, we carefully observed the PD withdrawal process and investigated the underlying mechanism of PD withdrawal, which will aid the understanding of wind-pollination efficiency in gymnosperms. Results In Ginkgo biloba, PDs were secreted on the micropyle during the pollination period and persisted for about 240 h when not pollinated under laboratory conditions. The withdrawal of an isolated PD required only 1 h for evaporation, much less than a PD on the living ovule, which required 100 h. When pollinated with viable pollen, PDs withdrew rapidly within 4 h. In contrast, nonviable pollen and acetone-treated pollen did not cause PD withdrawal. Although 100% relative humidity significantly inhibited PD withdrawal, pollinated PDs still could withdraw completely within 48 h. Pollen grains of Cycas revoluta, which are similar to those of G. biloba, could induce PD withdrawal more rapidly than those of two distantly related gymnosperms (Pinus thunbergii and Abies firma or two angiosperms (Paeonia suffruticosa and Orychophragmus violaceus. Furthermore, pollen of G. biloba and C. revoluta submerged immediately when encountering the PD, then sank to the bottom and entered the micropyle. The saccate pollen of P. thunbergii and A. firma submerged into the PD, but remained floating at the top and finally accumulated on the micropyle after PD withdrawal. In contrast, pollen of the angiosperms P. suffruticosa, Salix babylonica, and O. violaceus did not submerge, instead remaining clustered at the edge without entering the PD. Conclusions We conclude that PD withdrawal is primarily determined by the dynamic balance between evaporation and ovule secretion, of which pollen is a critical stimulator

  13. The mechanism of pollination drop withdrawal in Ginkgo biloba L. (United States)

    Jin, Biao; Zhang, Lei; Lu, Yan; Wang, Di; Jiang, Xiao X; Zhang, Min; Wang, Li


    The pollination drop (PD) is a characteristic feature of many wind-pollinated gymnosperms. Although accumulating evidence shows that the PD plays a critical role in the pollination process, the mechanism of PD withdrawal is still unclear. Here, we carefully observed the PD withdrawal process and investigated the underlying mechanism of PD withdrawal, which will aid the understanding of wind-pollination efficiency in gymnosperms. In Ginkgo biloba, PDs were secreted on the micropyle during the pollination period and persisted for about 240 h when not pollinated under laboratory conditions. The withdrawal of an isolated PD required only 1 h for evaporation, much less than a PD on the living ovule, which required 100 h. When pollinated with viable pollen, PDs withdrew rapidly within 4 h. In contrast, nonviable pollen and acetone-treated pollen did not cause PD withdrawal. Although 100% relative humidity significantly inhibited PD withdrawal, pollinated PDs still could withdraw completely within 48 h. Pollen grains of Cycas revoluta, which are similar to those of G. biloba, could induce PD withdrawal more rapidly than those of two distantly related gymnosperms (Pinus thunbergii and Abies firma) or two angiosperms (Paeonia suffruticosa and Orychophragmus violaceus). Furthermore, pollen of G. biloba and C. revoluta submerged immediately when encountering the PD, then sank to the bottom and entered the micropyle. The saccate pollen of P. thunbergii and A. firma submerged into the PD, but remained floating at the top and finally accumulated on the micropyle after PD withdrawal. In contrast, pollen of the angiosperms P. suffruticosa, Salix babylonica, and O. violaceus did not submerge, instead remaining clustered at the edge without entering the PD. We conclude that PD withdrawal is primarily determined by the dynamic balance between evaporation and ovule secretion, of which pollen is a critical stimulator. When conspecific pollen grains were submerged in the PD, ovule

  14. Shedding of Water Drops from a Surface under Icing Conditions. (United States)

    Mandal, Deepak Kumar; Criscione, Antonio; Tropea, C; Amirfazli, A


    A sessile water drop exposed to an air flow will shed if the adhesion is overcome by the external aerodynamic forces on the drop. In this study, shedding of water drops were investigated under icing conditions, on surfaces with different wettabilities, from hydrophilic to superhydrophobic. A wind tunnel was used for experiments in a temperature range between -8 and 24.5 °C. Results indicate that the temperature has a major influence on the incipient motion of drop shedding. The critical air velocity (U(c)) at which a drop first starts to shed generally increases under icing conditions, indicating an increase in the adhesion force. The contact angle hysteresis (CAH) and the drop base length (L(b)) are found to be the controlling factors for adhesion. A correlation was also developed to deduce the drag coefficient, C(D) for the drop. It was found that C(D) can decrease under icing conditions. In general, a lower C(D) and higher adhesion together lead to a higher critical air velocity. However, there are systems such as water on Teflon for which the critical air velocity remains practically unaffected by temperature because of similar adhesion and C(D) values, at all temperatures tested.

  15. Application of Proteomics to the Study of Pollination Drops

    Directory of Open Access Journals (Sweden)

    Natalie Prior


    Full Text Available Premise of the study: Pollination drops are a formative component in gymnosperm pollen-ovule interactions. Proteomics offers a direct method for the discovery of proteins associated with this early stage of sexual reproduction. Methods: Pollination drops were sampled from eight gymnosperm species: Chamaecyparis lawsoniana (Port Orford cedar, Ephedra monosperma, Ginkgo biloba, Juniperus oxycedrus (prickly juniper, Larix ×marschlinsii, Pseudotsuga menziesii (Douglas-fir, Taxus ×media, and Welwitschia mirabilis. Drops were collected by micropipette using techniques focused on preventing sample contamination. Drop proteins were separated using both gel and gel-free methods. Tandem mass spectrometric methods were used including a triple quadrupole and an Orbitrap. Results: Proteins are present in all pollination drops. Consistency in the protein complement over time was shown in L. ×marschlinsii. Representative mass spectra from W. mirabilis chitinase peptide and E. monosperma serine carboxypeptidase peptide demonstrated high quality results. We provide a summary of gymnosperm pollination drop proteins that have been discovered to date via proteomics. Discussion: Using proteomic methods, a dozen classes of proteins have been identified to date. Proteomics presents a way forward in deepening our understanding of the biological function of pollination drops.

  16. Modeling drop impacts on inclined flowing soap films (United States)

    Basu, Saikat; Yawar, Ali; Concha, Andres; Bandi, Mahesh


    Small drops impinging on soap films flowing at an angle primarily exhibit three fundamental regimes of post-impact dynamics: (a) the drop bounces off the film surface, (b) it coalesces with the downstream flow, and (c) it pierces through the film. During impact, the drop deforms along with a simultaneous, almost elastic deformation of the film transverse to the stream direction. Hence, the governing dynamics for this interaction present the rare opportunity to explore the in-tandem effects of elasticity and hydrodynamics alike. In this talk, we outline the analytical framework to study the drop impact dynamics. The model assumes a deformable drop and a deformable three-dimensional soap film and invokes a parametric study to qualify the three mentioned impact types. The physical parameters include the impact angle, drop impact speed, and the diameters of the drop prior to and during impact when it deforms and spreads out. Our model system offers a path towards optimization of interactions between a spray and a flowing liquid.

  17. Pupil dilation using drops vs gel: a comparative study (United States)

    Moisseiev, E; Loberman, D; Zunz, E; Kesler, A; Loewenstein, A; Mandelblum, J


    Purpose To compare the efficacy in pupil dilation and degree of discomfort between topical instillation of mydriatic drops and gel. Methods The study included 60 patients with no previous ocular history of trauma and surgery. One eye was dilated with two drops (tropicamide 0.5% and phenylephrine 10%), and the other with one drop of gel (tropicamide 0.5%+phenylephrine 5%). Pupil size was measured by a Colvard pupillometer at baseline and 5, 15, 30, and 45 min following instillation. Pain upon instillation was measured by visual analog scale (VAS). Results There was no difference in pupil size at baseline. Use of the gel achieved greater mydriasis than drops (P=0.01), and was also associated with lower pain scores (P=0.003). In diabetic patients, pupil size was smaller at baseline and following instillation of drops and gel. Use of the gel achieved an even greater degree of pupil dilation in this subset of patients than drops (P=0.019). Conclusions Gel formulation achieved significantly greater pupil dilation than drops, despite a lower concentration of phenylephrine, and was also associated with significantly lower patient discomfort. This study is the first report of improved mydriatic efficacy in diabetic patients. PMID:25857606

  18. Sound wave energy emitted by water drop during the splash on the soil surface (United States)

    Bieganowski, Andrzej; Ryżak, Magdalena; Korbiel, Tomasz


    A drop of rain falling on the surface of bare soil not only moisturizes but also can cause splash or compaction, depending on the energy of incident drops and the condition of the surface on which it falls. The splash phenomenon can be characterized by the weight of detached soil material (using splash cups) as well as the number and trajectory of splashed particles (using high-speed cameras). The study presents a new aspect of the analysis of the splash phenomenon by measurement of the sound pressure level and the sound energy of the wave that propagates in the air. The measurements were carried out in an anechoic chamber. Three soils (Endogleyic Umbrisol, Fluvic Endogleyic Cambisol, and Haplic Chernozem) with four initial moisture levels (pressure heads: 0.1 kPa, 1 kPa, 3.16 kPa, and 16 kPa) were tested. Drops of 4.2 mm diameter were falling from a height of 1.5m. The sound pressure level was recorded after 10 consecutive water drop impacts using a special set of microphones. In all measuring conditions with 1m distance, the sound pressure level ranged from 27 to 42dB. The impact of water drops on the ground created sound pulses, which were recalculated to the energy emitted in the form of sound waves. For all soil samples, the sound wave energy was within the range of 0.14 μJ to 5.26 μJ, which corresponds to 0.03-1.07% of the energy of the incident drops (Ryżak et al., 2016). This work was partly financed from the National Science Centre, Poland; project no. 2014/14/E/ST10/00851. References Ryżak M., Bieganowski A., Korbiel T.: Sound wave Energy resulting from the impact of water drops on the soil surface. PLoS One 11(7):e0158472. doi:10.1371/journal.pone.0158472, 2016

  19. The role of aerosols in cloud drop parameterizations and its applications in global climate models

    Energy Technology Data Exchange (ETDEWEB)

    Chuang, C.C.; Penner, J.E. [Lawrence Livermore National Lab., CA (United States)


    The characteristics of the cloud drop size distribution near cloud base are initially determined by aerosols that serve as cloud condensation nuclei and the updraft velocity. We have developed parameterizations relating cloud drop number concentration to aerosol number and sulfate mass concentrations and used them in a coupled global aerosol/general circulation model (GCM) to estimate the indirect aerosol forcing. The global aerosol model made use of our detailed emissions inventories for the amount of particulate matter from biomass burning sources and from fossil fuel sources as well as emissions inventories of the gas-phase anthropogenic SO{sub 2}. This work is aimed at validating the coupled model with the Atmospheric Radiation Measurement (ARM) Program measurements and assessing the possible magnitude of the aerosol-induced cloud effects on climate.

  20. Liquid film dynamics in horizontal and tilted tubes: Dry spots and sliding drops (United States)

    King, A. A.; Cummings, L. J.; Naire, S.; Jensen, O. E.


    Using a model derived from lubrication theory, we consider the evolution of a thin viscous film coating the interior or exterior of a cylindrical tube. The flow is driven by surface tension and gravity and the liquid is assumed to wet the cylinder perfectly. When the tube is horizontal, we use large-time simulations to describe the bifurcation structure of the capillary equilibria appearing at low Bond number. We identify a new film configuration in which an isolated dry patch appears at the top of the tube and demonstrate hysteresis in the transition between rivulets and annular collars as the tube length is varied. For a tube tilted to the vertical, we show how a long initially uniform rivulet can break up first into isolated drops and then annular collars, which subsequently merge. We also show that the speed at which a localized drop moves down the base of a tilted tube is nonmonotonic in tilt angle.

  1. Effect of drop size on the impact thermodynamics for supercooled large droplet in aircraft icing

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Chen [School of Aeronautics and Astronautics, Shanghai Jiaotong University, Shanghai 200240 (China); Liu, Hong, E-mail: [J. C. Wu Center of Aerodynamics, Shanghai Jiaotong University, Shanghai 200240 (China)


    Supercooled large droplet (SLD), which can cause abnormal icing, is a well-known issue in aerospace engineering. Although efforts have been exerted to understand large droplet impact dynamics and the supercooled feature in the film/substrate interface, respectively, the thermodynamic effect during the SLD impact process has not received sufficient attention. This work conducts experimental studies to determine the effects of drop size on the thermodynamics for supercooled large droplet impingement. Through phenomenological reproduction, the rapid-freezing characteristics are observed in diameters of 400, 800, and 1300 μm. The experimental analysis provides information on the maximum spreading rate and the shrinkage rate of the drop, the supercooled diffusive rate, and the freezing time. A physical explanation of this unsteady heat transfer process is proposed theoretically, which indicates that the drop size is a critical factor influencing the supercooled heat exchange and effective heat transfer duration between the film/substrate interface. On the basis of the present experimental data and theoretical analysis, an impinging heating model is developed and applied to typical SLD cases. The model behaves as anticipated, which underlines the wide applicability to SLD icing problems in related fields.


    Directory of Open Access Journals (Sweden)

    Martunus Martunus


    Full Text Available Perpindahan massa dari satu fase cair ke fase cair lainnya di dalam kolom ekstraksi cair-cair ditentukan dengan luas perpindahan antara kedua fase. Luas perpindahan ini dapat dinyatakan dengan drop size yang merupakan faktor yang sangat penting dalam perancangan kolom ekstraksi cair-cair berpengaduk (Rotating Disc Contactor, RDC. Tiga model yang berhubungan dengan drop size dikembangkan untuk variabel operasi kolom yang didasarkan pada kecepatan putaran yaitu yaitu model untuk ekstraksi tanpa pengadukan atau pengadukan dengan putaran sangat rendah, model dengan kecepatan pengadukan medium, dan model pengadukan dengan putaran tinggi. Artikel ini berisi pembahasan persamaan drop size yang sudah dipublikasikan menyangkut ketiga kondisi operasi tersebut.

  3. Intelligent water drops for aerospace and defense applications (United States)

    Straub, Jeremy


    A modified version of the intelligent water drop algorithm for performing planning for air and ground robots based on telemetry provided by satellites has been created. The IWD algorithm works by simulating the flow of water drops in a stream-network, dynamically adapting drop and network characteristics. This paper presents the base IWD algorithm, a simplified version of the algorithm (SIWD) and a derivative of this simplified version that has been adapted and applied to planning air and ground robot paths based upon orbital (for aerial) and aerial (for ground) imagery. An analysis of the performance of the algorithm is presented.

  4. Partial coalescence of sessile drops with different liquids (United States)

    Borcia, Rodica; Bestehorn, Michael


    We examine numerically the interaction between two deformable drops consisting of two perfectly miscible liquids sitting on a solid substrate under a given contact angle. Driven by solutal Marangoni forces, several distinct coalescence regimes are achieved after the droplets collision. Phase diagrams for different control parameters are emphasized, which give predictions about drop behavior along the solid substrates, control of various interfacial effects, manipulations of tiny droplets in micro- and nano-fluidic devices without power supply, design of droplets or cleaning surfaces. This work was partially supported by Deutsche Forschungsgemeinschaft (DFG) under the project ``Dynamics of interfaces between drops with miscible liquids''.

  5. Analysis of an Electrostatic MEMS Squeeze-film Drop Ejector

    Directory of Open Access Journals (Sweden)

    Edward P. Furlani


    Full Text Available We present an analysis of an electrostatic drop-on-demand MEMS fluid ejector. The ejector consists of a microfluidic chamber with a piston that is suspended a few microns beneath a nozzle plate. A drop is ejected when a voltage is applied between the orifice plate and the piston. This produces an electrostatic force that moves the piston towards the nozzle. The moving piston generates a squeeze-film pressure distribution that causes drop ejection. We discuss the operating physics of the ejector and present a lumped-element model for predicting its performance. We calibrate the model using coupled structural-fluidic CFD analysis.

  6. Ready-made allogeneic ABO-specific serum eye drops

    DEFF Research Database (Denmark)

    Harritshøj, Lene Holm; Nielsen, Connie; Ullum, Henrik


    PURPOSE: To overcome problems and delays of the preparation of autologous serum eye drops, a production line of ABO-specific allogeneic serum eye drops from male blood donors was set up in a blood bank. Feasibility, clinical routine, safety and efficacy were evaluated in a cohort of patients...... serum treatment. CONCLUSION: Ready-made ABO-identical allogeneic serum eye drops were straightforwardly produced, quality-assured and registered as a safe standard blood product for the treatment of certain cases of severe dry eye disease. Therapeutic efficacy was comparable to previous reports...

  7. Update on the Purdue University 2-second Drop Tower (United States)

    Collicott, Steven

    A small drop tower of approximately one second drop duration was built in the School of Aero-nautics and Astronautics at Purdue University beginning in 1998 and operated until summer 2007. This inexpensive tower in an old airplane hanger, was built largely by Yongkang Chen, now a Research Professor at Portland State University in Oregon, USA. In about 7 years of operations, the tower generated sufficient science results for Chen's PhD thesis[1] (summarized in three AIAA Journal papers[2-4]), Fitzpatrick's MS thesis[5], two industry projects for since-canceled advanced rodent habitats for ISS, and one project for NASA Marshall. In addition to the science use, Purdue undergraduate students designed, built, and performed simpler fluids experiments for their own career advancement, including a novel investigation of the impact of imperfect repeatability of initial conditions on a zero-g fluids experiment. The tower was also used for outreach to school children. It is most satisfying that Chen's PhD research in this small tower, and subsequent discussions and interactions, helped Weislogel to propose the two Vane Gap tests in his highly successful Capillary Fluids Experiment (CFE) in the International Space Station in 2006 and 2007[6]. Chen as been involved in the remodeling of these two Vane Gap cylinders for subsequent re-launch to ISS for a second round of experiments expected in 2010 and 2011. In August 2007 the School of Aeronautics and Astronautics at Purdue University moved into the new Neil Armstrong Hall of Engineering and construction on a new 2-second drop tower began. A vertical shaft of nearly 23 meters was designed into the building. An approximately 80 m2 general-use fluids lab is at the top level, and a small access room of approximately 9 m2 is at the bottom. However, construction of the new $57M building created only the space for the science facility, not the science facility itself. The science facility is under construction and this paper presents

  8. Experimental Study of Cloud Formation from Rapidly Opened Containers

    Energy Technology Data Exchange (ETDEWEB)

    Wooldridge, C.E. [Stanford Research Institute; Amaro, A.J. [Stanford Research Institute; Kier, R.J. [Stanford Research Institute


    This report presents the results of an experimental study of droplet size emanating from a rapidly-opened container of volatile liquid, of the internal dynamics of the cavitation process inside such a container, & of the evaporation time of propane drops.

  9. Handling test of eye drop dispenser--comparison of unit-dose pipettes with conventional eye drop bottles. (United States)

    Parkkari, Minna; Latvala, Terho; Ropo, Auli


    The aims of this study were to investigate how elderly people handle single-use eye drop dispensers (unit-dose pipettes) and to compare the performance with conventional eye drop bottles. In this open-label study, the handling of unit-dose pipettes and conventional eye drop bottles was compared in 41 elderly people who had little or no prior regular use of eye drop dispensers. The participants tested both types of dispenser once, and the following 7 variables were studied: ease/difficulty of opening the dispenser; influence of the size for handling of the dispenser; influence of the shape for handling of the dispenser; observation of the contents in the dispenser; the feeling of the dispenser in the hand; ease/difficulty of drop instillation on the eye from the dispenser; and overall performance of the eye drop dispenser. The dispensers contained isotonic saline, and a visual analog scale was used for assessment of each of the above variables. The mean age of the participants was 73 years. A statistically significant difference in favor of the unit-dose pipettes was found with respect to observation of the contents in the dispenser, ease of administration, and the overall performance. Women regarded the unit-dose pipettes generally better than the bottles, but such a difference was not seen in men. The study participants managed the unit-dose pipettes at least as well as the conventional eye drop bottles. If anything, the unit-dose pipettes appeared to be easier to use.

  10. Method and apparatus for producing drops using a drop-on-demand dispenser (United States)

    Chen, Alvin U.; Basaran, Osman A.


    A method and apparatus for dispensing fluid from a drop-on-demand (DOD) fluid dispenser. The method involves withdrawing fluid in the dispenser for a first duration of time, followed by a second duration of time during which the fluid is propelled toward the orifice of the dispenser. Following the period during which the fluid is propelled, there is a second withdrawing of the fluid into the dispenser. The duration of the propelling period is shorter than the duration of either the first withdrawing or the second withdrawing. The propelling of the fluid results in the extension of a small tongue of fluid from the meniscus of the fluid. The second withdrawing of the fluid results in a retraction of the meniscus into the passageway such that only the small tongue of fluid separates and is ejected from the dispenser.

  11. Liquid Drop Pinning on Micro-patterned Surfaces (United States)

    Soliman, Ahmed; Kalinin, Yevgeniy; Baur, Robin; Thorne, Robert


    Pinning of liquid drops on surfaces is important in many areas of biotechnology. Micro-patterned surfaces provide a way to control drop pinning, and to investigate the mechanisms of pinning on real (rough) surfaces. Continuous circular rings on silicon wafers produced by etching the interior and surrounding silicon are shown to dramatically increase contact line pinning. The critical apparent contact angles and liquid drop volumes are measured and correlated with parameters that describe the ring geometry, such as ring-wall height and width, as well as with ring surface energy (hydrophilicity / hydrophobicity). Micro-patterning of surfaces in this way can be used to improve drop pinning, shape reproducibility and imaging in high-throughput protein crystallization.

  12. Queues with Dropping Functions and General Arrival Processes. (United States)

    Chydzinski, Andrzej; Mrozowski, Pawel


    In a queueing system with the dropping function the arriving customer can be denied service (dropped) with the probability that is a function of the queue length at the time of arrival of this customer. The potential applicability of such mechanism is very wide due to the fact that by choosing the shape of this function one can easily manipulate several performance characteristics of the queueing system. In this paper we carry out analysis of the queueing system with the dropping function and a very general model of arrival process--the model which includes batch arrivals and the interarrival time autocorrelation, and allows for fitting the actual shape of the interarrival time distribution and its moments. For such a system we obtain formulas for the distribution of the queue length and the overall customer loss ratio. The analytical results are accompanied with numerical examples computed for several dropping functions.

  13. Bird nesting and droppings control on highway structures. (United States)


    This report provides a comprehensive literature survey of permanent and temporary deterrents to nesting and roosting, a : discussion of risks to human health and safety from exposure to bird nests and droppings and recommended protective measures, : ...

  14. Critical look at South Africa’s Green Drop Programme

    CSIR Research Space (South Africa)

    Ntombela, Cebile


    Full Text Available itself in. Challenges facing the Green Drop Programme and the municipalities implementing the programme include: lack of human resource capacity to prepare effective corrective action plans and/or wastewater risk abatement plans; lack of finances...

  15. The effect of dropping impact on bruising pomegranate fruit

    Directory of Open Access Journals (Sweden)

    M Mohammad Shafie


    Full Text Available Introduction: The pomegranate journey from orchard to supermarket is very complex and pomegranates are subjected to the variety of static and dynamic loads that could result in this damage and bruise occurring. Bruise area and bruise volume are the most important parameters to evaluate fruit damage occurred in harvest and postharvest stages. The bruising is defined as damage to fruit flesh usually with no abrasion of the peel. The two different types of dynamic loading which can physically cause fruit bruising are impact and vibration. The impact and vibration loadings may occur during picking or sorting as the pomegranates are dropped into storage bins and during transportation. The focus of this work was on the impact loading as this appeared to be the most prevalent. In view of the limitations of conventional testing methods (ASTM D3332 Standard Test Methods for Mechanical Shock Fragility of Products, the method and procedure for determining dropping bruise boundary of fruit were also established by adapting free-fall dropping tests. Materials and Methods: After the ‘Malas-e-Saveh’ pomegranates had been selected, they were numbered, and the weight and dimension of each sample were measured and recorded. Firmness in cheek region of each fruit was also measured. Fruit firmness was determined by measuring the maximum force during perforating the sample to a depth of 10 mm at a velocity of 100 mm min-1 with an 8 mm diameter cylindrical penetrometer mounted onto a STM-5 Universal Testing Machine (SANTAM, Design CO. LTD., England. Free-fall dropping tests with a series of drop heights (6, 7, 10, 15, 30 and 60 cm were conducted on fresh ‘Malas-e-Saveh’ pomegranates. Three samples were used for each dropping height, and each sample was subjected to impact on two different positions. Before the test was started, it was necessary to control the sample's drop position. The cheek of sample was placed on the fruit holder. An aluminum plate mounted

  16. Drop motion in a rotating immiscible liquid body (United States)

    Annamalai, P.; Cole, R.


    The interaction of liquids is an important part of many processes and is often used for such purposes as causing a separation of solution components by mass transfer between phases, allowing a chemical reaction between liquids or their components, providing direct contact heating or cooling, or creating emulsions. Containerless space processing may well involve the interaction of liquids in the form of drops. For example it may be desirable to form an alloy in space by merger of two or more drops. Encapsulation of a volatile liquid by a second less volatile and immiscible liquid might be a means for avoiding volatilization. Rotation of such systems would enhance mixing where desirable and/or provide means for drop management. In this study, single drop behavior in rotating liquid bodies is studied experimentally.

  17. Satellite Formation during Coalescence of Unequal Size Drops

    KAUST Repository

    Zhang, F. H.


    The coalescence of a drop with a flat liquid surface pinches off a satellite from its top, in the well-known coalescence cascade, whereas the coalescence of two equally sized drops does not appear to leave such a satellite. Herein we perform experiments to identify the critical diameter ratio of two drops, above which a satellite is produced during their coalescence. We find that the critical parent ratio is as small as 1.55, but grows monotonically with the Ohnesorge number. The daughter size is typically about 50% of the mother drop. However, we have identified novel pinch-off dynamics close to the critical size ratio, where the satellite does not fully separate, but rather goes directly into a second stage of the coalescence cascade, thus generating a much smaller satellite droplet.

  18. Multiscale liquid drop impact on wettable and textured surfaces (United States)

    Zhang, Rui; Farokhirad, Samaneh; Lee, Taehun; Koplik, Joel


    The impact of microscopic liquid drops on solids with a variety of surface characteristics is studied using numerical simulations. The focus is on relatively low impact velocities leading to bouncing or spreading drops, and the effects of wettability. Molecular dynamics and lattice Boltzmann simulation methods are used for nanometer-sized and continuum drops, respectively, and the results of the two methods are compared in terms of scaled variables. We consider surfaces which are flat, curved or pillared, with either homogeneous interactions or cross-shaped patterns of wettability. In most situations we observe similar drop behavior at both length scales; the two methods agree best at low impact velocities on wettable surfaces while discrepancies are most pronounced for strongly hydrophobic surfaces and for higher velocities.

  19. Modeling merging behavior at lane drops : [tech transfer summary]. (United States)


    A better understanding of the merging behavior of drivers will lead : to the development of better lane-drop traffic-control plans and : strategies, which will provide better guidance to drivers for safer : merging.

  20. Rapid solidification of Nb-base alloys (United States)

    Gokhale, A. B.; Javed, K. R.; Abbaschian, G. J.; Lewis, R. E.


    New Nb-base alloys are of interest for aerospace structural applications at high temperatures, viz, 800 to 1650 C. Fundamental information regarding the effects of rapid solidification in achieving greatly refined microstructures, extended solid solubility, suppression of embrittling equilibrium phases, and formation of new phases is desired in a number of Nb-X alloys. The microstructures and selected properties of Nb-Si and other Nb-base alloys are presented for materials both rapidly quenched from the equilibrium liquidus and rapidly solidified following deep supercooling. Electromagnetic levitation was used to achieve melting and supercooling in a containerless inert gas environment. A variety of solidification conditions were employed including splatting or drop casting of supercooled samples. The morphology and composition of phases formed are discussed in terms of both solidification history and bulk composition.

  1. What explains Rwanda's drop in fertility between 2005 and 2010 ?


    Bundervoet, Tom


    Following a decade-and-a-half stall, fertility in Rwanda dropped sharply between 2005 and 2010. Using a hierarchical age-period-cohort model, this paper finds that the drop in fertility is largely driven by cohort effects, with younger cohorts having substantially fewer children than older cohorts observed at the same age. An Oaxaca-Blinder decomposition is applied on two successive rounds...

  2. Nectar and pollination drops: how different are they? (United States)

    Nepi, Massimo; von Aderkas, Patrick; Wagner, Rebecca; Mugnaini, Serena; Coulter, Andrea; Pacini, Ettore


    Pollination drops and nectars (floral nectars) are secretions related to plant reproduction. The pollination drop is the landing site for the majority of gymnosperm pollen, whereas nectar of angiosperm flowers represents a common nutritional resource for a large variety of pollinators. Extrafloral nectars also are known from all vascular plants, although among the gymnosperms they are restricted to the Gnetales. Extrafloral nectars are not generally involved in reproduction but serve as 'reward' for ants defending plants against herbivores (indirect defence). Although very different in their task, nectars and pollination drops share some features, e.g. basic chemical composition and eventual consumption by animals. This has led some authors to call these secretions collectively nectar. Modern techniques that permit chemical analysis and protein characterization have very recently added important information about these sugary secretions that appear to be much more than a 'reward' for pollinating (floral nectar) and defending animals (extrafloral nectar) or a landing site for pollen (pollination drop). Nectar and pollination drops contain sugars as the main components, but the total concentration and the relative proportions are different. They also contain amino acids, of which proline is frequently the most abundant. Proteomic studies have revealed the presence of common functional classes of proteins such as invertases and defence-related proteins in nectar (floral and extrafloral) and pollination drops. Invertases allow for dynamic rearrangement of sugar composition following secretion. Defence-related proteins provide protection from invasion by fungi and bacteria. Currently, only few species have been studied in any depth. The chemical composition of the pollination drop must be investigated in a larger number of species if eventual phylogenetic relationships are to be revealed. Much more information can be provided from further proteomic studies of both

  3. Refrigeration. Two-Phase Flow. Flow Regimes and Pressure Drop

    DEFF Research Database (Denmark)

    Knudsen, Hans-Jørgen Høgaard


    The note gives the basic definitions used in two-phase flow. Flow regimes and flow regimes map are introduced. The different contributions to the pressure drop are stated together with an imperical correlation from the litterature.......The note gives the basic definitions used in two-phase flow. Flow regimes and flow regimes map are introduced. The different contributions to the pressure drop are stated together with an imperical correlation from the litterature....

  4. Drop formation of black liquor spraying; Mustalipeaen pisaroituminen

    Energy Technology Data Exchange (ETDEWEB)

    Fogelholm, C.J.; Kankkunen, A.; Nieminen, K.; Laine, J.; Miikkulainen, P. [Helsinki Univ. of Technology, Otaniemi (Finland): Lab. of Energy Technology and Environmental Protection


    Black liquor is a spent liquor of the pulp and paper industry. It is burned in kraft recovery boilers for chemical and energy recovery. The high dry solids content and viscosity of black liquor require a high spraying temperature. This affects the performance of the boiler. Kraft recovery boiler deposit formation, emissions and chemical recovery are strongly affected by the drop size and the velocity of the black liquor spray formed by a splashplate nozzle. The sheet breakup mechanism is studied with a system based on a video and image-analysis. The drop size of mill-scale nozzles was measured also with an image-analysis-system. Measurements were carried out in a spray test chamber. The sheet breakup mechanism and drop size tests were carried out both below and over the boiling point of black liquor. Special attention was paid to the effect of flashing on drop formation. Temperature increase normally decreases drop size. In the temperature where the wavy-sheet disintegration changes to perforated-sheet disintegration the drop size increases. Spray velocity rises when the temperature is increased above the boiling point. (orig.)

  5. Wetting of sessile water drop under an external electrical field (United States)

    Vancauwenberghe, Valerie; di Marco, Paolo; Brutin, David; Amu Collaboration; Unipi Collaboration


    The enhancement of heat and mass transfer using a static electric field is an interesting process for industrial applications, due to its low energy consumption and potentially high level of evaporation rate enhancement. However, to date, this phenomenon is still not understood in the context of the evaporation of sessile drops. We previously synthesized the state of the art concerning the effect of an electric field on sessile drops with a focus on the change of contact angle and shape and the influence of the evaporation rate [1]. We present here the preliminary results of an new experiment set-up. The novelty of the set-up is the drop injection from the bottom that allows to generate safety the droplet under the electrostatic field. The evaporation at room temperature of water drops having three different volumes has been investigated under an electric field up to 10.5 kV/cm. The time evolutions of the contact angles, volumes and diameters have been analysed. As reported in the literature, the drop elongate along the direction of the electric field. Despite the hysteresis effect of the contact angle, the receding contact angle increases with the strength of the electric field. This is clearly observable for the small drops for which the gravity effect can be neglected.

  6. Vortex-ring-induced large bubble entrainment during drop impact (United States)

    Thoraval, Marie-Jean; Li, Yangfan; Thoroddsen, Sigurdur T.


    For a limited set of impact conditions, a drop impacting onto a pool can entrap an air bubble as large as its own size. The subsequent rise and rupture of this large bubble plays an important role in aerosol formation and gas transport at the air-sea interface. The large bubble is formed when the impact crater closes up near the pool surface and is known to occur only for drops that are prolate at impact. Herein we use experiments and numerical simulations to show that a concentrated vortex ring, produced in the neck between the drop and the pool, controls the crater deformations and pinchoff. However, it is not the strongest vortex rings that are responsible for the large bubbles, as they interact too strongly with the pool surface and self-destruct. Rather, it is somewhat weaker vortices that can deform the deeper craters, which manage to pinch off the large bubbles. These observations also explain why the strongest and most penetrating vortex rings emerging from drop impacts are not produced by oblate drops but by more prolate drop shapes, as had been observed in previous experiments.

  7. [Preparation of Shuxiong pulsatile controlled-release dropping pill]. (United States)

    Chen, Hui; Chen, Yan-Zhong; Xie, Qing-Chun; Lin, Shi-Yuan; Lin, Jia-Cheng; Jianc, Wei-Ning


    To prepare Shuxiong pulsatile controlled-release dropping pill and study the influencing factors in vitro. Dropping pills with suitable size (10 - 15 mg) were coated with swelling layer containing croscarmellose sodium and controlled-release layer containing ethylcellulos aqueous dispersion respectively to prepare Shuxiong pulsatile controlled-release dropping pill. The effects of the materials of swelling layer, the weight of swelling layer and controlled-release layer on the release of drugs were investigated to optimize the process technology and validate formula. The release behavior was influenced strikingly by the types and weight of coating layer. The optimal formula was as follows: Shuxiong pulsatile controlled-release dropping pills were prepared using croscarmellose sodium as inner layer with 15% (weight) coating level and ethylcellulose aqueous dispersion (Surelease) as outer controlled-release layer with 7% (weight) coating level. The lag time of prepared pulsatile controlled-release dropping pills was about 4 h and accumulative release rate reached 80% within 4 h. The drug release of Shuxiong pulsatile controlled-release dropping pill is shown in pulsatile way in vitro.

  8. Afterlife of a Drop Impacting a Liquid Pool (United States)

    Saha, Abhishek; Wei, Yanju; Tang, Xiaoyu; Law, Chung K.


    Drop impact on liquid pool is ubiquitous in industrial processes, such as inkjet printing and spray coating. While merging of drop with the impacted liquid surface is essential to facilitate the printing and coating processes, it is the afterlife of this merged drop and associated mixing which control the quality of the printed or coated surface. In this talk we will report an experimental study on the structural evolution of the merged droplet inside the liquid pool. First, we will analyze the depth of the crater created on the pool surface by the impacted drop for a range of impact inertia, and we will derive a scaling relation and the associated characteristic time-scale. Next, we will focus on the toroidal vortex formed by the moving drop inside the liquid pool and assess the characteristic time and length scales of the penetration process. The geometry of the vortex structure which qualitatively indicates the degree of mixedness will also be discussed. Finally, we will present the results from experiments with various viscosities to demonstrate the role of viscous dissipation on the geometry and structure formed by the drop. This work is supported by the Army Research Office and the Xerox Corporation.

  9. Numerical simulations of drop impact on superhydrophobic structured surfaces (United States)

    Guzzetti, Davide; Larentis, Stefano; Pugno, Nicola


    During the last decade drop impact dynamics on superhydrophobic surfaces has been intensively investigated because of the incredible properties of water repellency exhibited by this kind of surfaces, mostly inspired by biological examples such as Lotus leave. Thanks to the recent progress in micro-fabrication technology is possible to tailor surfaces wettability defining specific pillar-like structured surfaces. In this work, the behavior of impinging drops on these pillar-like surfaces is simulated, characterizing temporal evolution of droplets contact radius and drop maximal deformation dependence on Weber number. Numerical simulations results are compared with theoretical and experimental results guaranteeing simulation reliability. Fingering patterns obtained from drop impact has been studied obtaining a correlation between number of fingers and Weber number. Drop fragmentation pattern obtained from simulations supports the proposed correlation. Different drop impact outcomes (e.g. rebound, fragmentation) on structured superhydrophobic surfaces are simulated, focusing on the influence of micro-structured surface geometrical pattern. This investigation is relevant in order to define design rules for possible reliable non wettable surfaces. Financial support by Alta Scuola Politecnica.

  10. Capillary-Inertial Colloidal Catapult upon Drop Coalescence (United States)

    Chavez, Roger; Liu, Fangjie; Feng, James; Chen, Chuan-Hua


    To discharge micron-sized particles such as colloidal contaminants and biological spores, an enormous power density is needed to compete against the strong adhesive forces between the small particles and the supporting surface as well as the significant air friction exerted on the particles. Here, we demonstrate a colloidal catapult that achieves such a high power density by extracting surface energy released upon drop coalescence within an extremely short time period, which is governed by the capillary-inertial process converting the released surface energy into the bulk inertia of the merged drop. When two drops coalesce on top of a spherical particle, the resulting capillary-inertial oscillation is perturbed by the solid particle, giving rise to a net momentum eventually propelling the particle to launch from the supporting surface. The measured launching velocity follows a scaling law that accounts for the redistribution of the momentum of the merged drop onto the particle-drop complex, and is therefore proportional to the capillary-inertial velocity characterizing the coalescing drops. The interfacial flow process associated with the colloidal catapult is elucidated with both high-speed imaging and phase-field simulations.

  11. A measurement of a control rod drop using an LVDT (United States)

    Choi, Myoung-Hwan; Kim, Ji-Ho; Huh, Hyung; Yu, Je-Yong; Sohn, Dong-Seong


    A control element drive mechanism is a reactor regulating system, which is to insert, withdraw, or maintain a control rod containing neutron-absorbing material within a reactor core to control the reactivity of the reactor. The ball-screw type CEDM for the small and medium research reactor has a spring-hydraulic damper to reduce the impact force due to the free drop of the CEDM. This paper describes the experimental results to obtain the drop characteristics of the CEDM. The tests are performed by using a full-scale structure except the control element assembly, and a drop time and displacement after an impact are measured by using an LVDT. The influences of the rod weight and the drop height on the drop behavior are also estimated on the basis of test results. In case of the longest stroke, the drop time of the control rod is within 4.5 seconds to meet the design requirement. The behavior after the impact shows a general damping motion of the spring-damper system, and the maximum displacement is measured as 15.6 mm.

  12. Short Duration Reduced Gravity Drop Tower Design and Development (United States)

    Osborne, B.; Welch, C.

    The industrial and commercial development of space-related activities is intimately linked to the ability to conduct reduced gravity research. Reduced gravity experimentation is important to many diverse fields of research in the understanding of fundamental and applied aspects of physical phenomena. Both terrestrial and extra-terrestrial experimental facilities are currently available to allow researchers access to reduced gravity environments. This paper discusses two drop tower designs, a 2.0 second facility built in Australia and a proposed 2.2 second facility in the United Kingdom. Both drop towers utilise a drag shield for isolating the falling experiment from the drag forces of the air during the test. The design and development of The University of Queensland's (Australia) 2.0 second drop tower, including its specifications and operational procedures is discussed first. Sensitive aspects of the design process are examined. Future plans are then presented for a new short duration (2.2 sec) ground-based reduced gravity drop tower. The new drop tower has been designed for Kingston University (United Kingdom) to support teaching and research in the field of reduced gravity physics. The design has been informed by the previous UQ drop tower design process and utilises a catapult mechanism to increase test time and also incorporates features to allow participants for a variety of backgrounds (from high school students through to university researchers) to learn and experiment in reduced gravity. Operational performance expectations for this new facility are also discussed.

  13. Vortex-ring-induced large bubble entrainment during drop impact

    KAUST Repository

    Thoraval, Marie-Jean


    For a limited set of impact conditions, a drop impacting onto a pool can entrap an air bubble as large as its own size. The subsequent rise and rupture of this large bubble plays an important role in aerosol formation and gas transport at the air-sea interface. The large bubble is formed when the impact crater closes up near the pool surface and is known to occur only for drops that are prolate at impact. Herein we use experiments and numerical simulations to show that a concentrated vortex ring, produced in the neck between the drop and the pool, controls the crater deformations and pinchoff. However, it is not the strongest vortex rings that are responsible for the large bubbles, as they interact too strongly with the pool surface and self-destruct. Rather, it is somewhat weaker vortices that can deform the deeper craters, which manage to pinch off the large bubbles. These observations also explain why the strongest and most penetrating vortex rings emerging from drop impacts are not produced by oblate drops but by more prolate drop shapes, as had been observed in previous experiments.

  14. Nerve growth factor eye drops improve visual acuity and electrofunctional activity in age-related macular degeneration: a case report

    Directory of Open Access Journals (Sweden)

    Alessandro Lambiase


    Full Text Available Age-related macular degeneration (ARMD is a severe disease affecting visual function in the elderly. Currently available surgical and medical options do not guarantee a significant impact on the outcome of the disease. We describe the effects of nerve growth factor eye drop treatment in a 94 years old female with ARMD, whose visual acuity was progressively worsening in spite of previous surgical and medical treatments. NGF eye drops improved visual acuity and electrofunctional parameters as early as 3 months after initiation of treatment. These results are in line with previous reports on a neuroprotective effect of NGF on retinal cells and on NGF eye drops bioavailability in the retina and optic nerve. No side effects were observed after five years of follow-up, suggesting that topical NGF treatment may be a safe and effective therapy for ARMD.

  15. Exchange flows of two immiscible Newtonian liquids in a vertical tube: From falling drops to falling slugs (United States)

    Varges, P. R.; Fonseca, B. S.; Naccache, M. F.; de Souza Mendes, P. R.


    We present an experimental study of buoyancy-driven flows of two immiscible Newtonian liquids in a vertical tube where initially the heavier and more viscous one is placed on the top of the lighter one. Flow visualization was performed using a digital camera, and inversion velocities were determined through image analysis. The influence of the governing parameters on the speed and flow regime was examined for pairs of liquids with small density differences. Two different flow regimes were observed, namely, falling drops and falling slugs. In the first regime, spherical and ellipsoidal drops are obtained, depending on the ratio between the drop and tube diameters. The falling slug regime is a core-annular flow pattern above a critical value of interfacial tension, while no flow is noticed below this critical value. The experimental results are in good agreement with model predictions from the literature. Indeed, the results showed that terminal velocity can be estimated by empirical correlations for falling spheres.

  16. Composites by rapid prototyping technology

    CSIR Research Space (South Africa)

    Kumar, S


    Full Text Available powder is a fiber, problems of manufacturing occur. The method has also been used to make Metal Matrix Composite (MMC), e.g Fe and graphite [17], WC-Co [18,19], WC-Co and Cu [20,21], Fe, Ni and TiC [22] etc and Ceramic Matrix Composite (CMC) e.g. Si... of various materials used. Key words: : Rapid Prototyping (RP), Laser, Composites 1 Introduction Rapid Prototyping (RP) initially focussed on polymers. These were later re- placed/supplemented by ceramics, metals and composites. Composites are used in RP...

  17. Efficacy and comparative analysis of consumer qualities of the Desmopressin intranasal drops in patients with central diabetes insipidus

    Directory of Open Access Journals (Sweden)

    Ekaterina Aleksamdrovna Pigarova


    Full Text Available Objective: To evaluate the effectiveness and conduct a comparative analysis of consumer qualities of desmopressin intranasal drops 0.01% 5ml ("Biopharm", Georgia in patients with central diabetes insipidus (CDI. Materials and Methods: The study included 9 patients (3 men and 6 women, mean age 44 ± 12 years diagnosed with CDI. Patients for 7 days were switched to desmopressin intranasal drops 0.01% (JSC "Biopharm" Georgia from there basal desmopressin preparations by means of recalculating daily dose by proposed formular: 10 mg (2 drops of desmopressin intranasal drops = 0.2 mg of desmopressin tableted = 10 micrograms (one dose of intranasal spray metered desmopressin = 120 mcg sublingual tablets of desmopressin. Safety biochemical parameters, efficiency to control of the main manifestations of CDI, increase in urine specific gravity, quality of life, basic consumer properties of different desmopressin preparation were evaluates at baseline and after treatment period. Results: Desmopressin nasal drops 0.01% showed to be an effective drug for the treatment of patients with CDI. Dose calculation algorithm daily was adequate in most patients. Hyponatremia was detected in 2 out of 9 patients during the study period but has been related to study drug alone in one case. The investigational drug was marked convenient to use by less than 25% of patients which may be associated with the pharmacological form of the drug as intranasal drops with special storage conditions (refrigerator. Conclusions: The drug desmopressin intranasal drops can be recommended as a second line (reserve therapy in the treatment of patients CDI. Sodium levels should be checked during initiation of therapy.

  18. Many Drops Interactions I: Simulation of Coalescence, Flocculation and Fragmentation of Multiple Colliding Drops with Smoothed Particle Hydrodynamics

    Directory of Open Access Journals (Sweden)

    Alejandro Acevedo-Malavé


    Full Text Available Smoothed Particle Hydrodynamics (SPH is a Lagrangian mesh-free formalism and has been useful to model continuous fluid. This formalism is employed to solve the Navier-Stokes equations by replacing the fluid with a set of particles. These particles are interpolation points from which properties of the fluid can be determined. In this study, the SPH method is applied to simulate the hydrodynamics interaction of many drops, showing some settings for the coalescence, fragmentation and flocculation problem of equally sized liquid drops in three-dimensional spaces. For small velocities the drops interact only through their deformed surfaces and the flocculation of the droplets arises. This result is very different if the collision velocity is large enough for the fragmentation of droplets takes place. We observe that for velocities around 15 mm/ms the coalescence of droplets occurs. The velocity vector fields formed inside the drops during the collision process are shown.

  19. Definitive foot drop deformity repair with tensor fascia latae myocutaneous flap. (United States)

    Karagöz, Hüseyin; Öksüz, Sinan; Ülkür, Ersin; Sever, Celalettin; Şahin, Cihan; Külahçi, Yalçin


    Tensor fascia latae (TFL) myocutaneous flap, utilized as a novel approach for the successful functional repair of the foot drop deformity is presented in this case report. A 21-year-old male patient was subjected to a close-range high-velocity gunshot injury and sustained comminuted Gustillo-type IIIB open fracture of his left tibia. A composite skin and soft tissue defect including tibialis anterior and extansor hallucis longus tendons was determined. The injury was managed in two stages. In the first stage, the immediate reconstruction of the open tibia fracture was provided by using a reverse flow sural flap and external fixation of the fracture. The functional restoration was achieved by vascular fascia latae in the second stage, 6 months after the initial skin, soft tissue, and bone defect repair. The functional recovery was successful, and the foot drop gait was almost totally ameliorated. Reconstruction with TFL flap should be retained in the armamentarium for the functional repair of the foot drop deformity, caused by composite skin and soft tissue defects of the pretibial region. Copyright © 2012 Wiley Periodicals, Inc.

  20. Theoretical study of flashing and water hammer in a supercritical water cycle during pressure drop

    Energy Technology Data Exchange (ETDEWEB)

    Imre, A.R., E-mail: imre@aeki.kfki.h [Simulator Laboratory, MTA KFKI Atomic Energy Research Institute, Budapest, POB 49, H-1525 (Hungary); Barna, I.F.; Ezsoel, G. [Thermohydraulics Laboratory, MTA KFKI Atomic Energy Research Institute, Budapest, POB 49, H-1525 (Hungary); Hazi, G. [Simulator Laboratory, MTA KFKI Atomic Energy Research Institute, Budapest, POB 49, H-1525 (Hungary); Kraska, T. [Institute for Physical Chemistry, University of Cologne, Luxemburger Str. 116, D-50939 Koeln (Germany)


    During a loss of coolant accident (LOCA) the pressure of the coolant can drop significantly in the vicinity of the leak. It will be shown that unlike in pressurized water reactors (PWRs) where this pressure drop can cause only sudden vaporization - also called flashing - in supercritical water cooled reactors (SCWRs) it can cause sudden condensation (condensation-induced water hammer), too. The reason is that from supercritical state the system can go to metastable liquid as well as to metastable vapour state after LOCA. Relaxation from metastable fluid states is a fast process, followed by a local positive or negative pressure-jump, which might increase the damage around the leak. Conservative estimation will be given for the magnitude of these pressure jumps caused by the flashing or water hammer by assuming various initial pressure losses. In our calculations, three different equations of state are used: the simple van der Waals EoS; the Redlich-Kwong as an empirical development; and the more sophisticated non-cubic Deiters equation of state. These equations are able to describe metastable states qualitatively but with different accuracy. These calculations can help us to map the local immediate effect of any sudden pressure drop and therefore it can help to design better safety protocols.

  1. Changes in drop-jump landing biomechanics during prolonged intermittent exercise. (United States)

    Schmitz, Randy J; Cone, John C; Tritsch, Amanda J; Pye, Michele L; Montgomery, Melissa M; Henson, Robert A; Shultz, Sandra J


    As injury rates rise in the later stages of sporting activities, a better understanding of lower extremity biomechanics in the later phases of gamelike situations may improve training and injury prevention programs. Lower extremity biomechanics of a drop-jump task (extracted from a principal components analysis) would reveal factors associated with risk of anterior cruciate ligament injury during a 90-minute individualized intermittent exercise protocol (IEP) and for 1 hour following the IEP. Controlled laboratory study. Level 4. Fifty-nine athletes (29 women, 30 men) completed 3 sessions. The first session assessed fitness for an IEP designed to simulate the demands of a soccer match. An experimental session assessed drop-jump biomechanics, after a dynamic warm-up, every 15 minutes during the 90-minute IEP, and for 1 hour following the IEP. A control session with no exercise assessed drop-jump performance at the same intervals. Two biomechanical factors early in the first half (hip flexion at initial contact and hip loading; ankle loading and knee shear force) decreased at the end of the IEP and into the 60-minute recovery period, while a third factor (knee loading) decreased only during the recovery period (P ≤ 0.05). The individualized sport-specific IEP may have more subtle effects on landing biomechanics when compared with short-term, exhaustive fatigue protocols. Potentially injurious landing biomechanics may not occur until the later stages of soccer activity.

  2. Sodium chloride crystallization from thin liquid sheets, thick layers, and sessile drops in microgravity (United States)

    Fontana, Pietro; Pettit, Donald; Cristoforetti, Samantha


    Crystallization from aqueous sodium chloride solutions as thin liquid sheets, 0.2-0.7 mm thick, with two free surfaces supported by a wire frame, thick liquid layers, 4-6 mm thick, with two free surfaces supported by metal frame, and hemispherical sessile drops, 20-32 mm diameter, supported by a flat polycarbonate surface or an initially flat gelatin film, were carried out under microgravity on the International Space Station (ISS). Different crystal morphologies resulted based on the fluid geometry: tabular hoppers, hopper cubes, circular [111]-oriented crystals, and dendrites. The addition of polyethylene glycol (PEG-3350) inhibited the hopper growth resulting in flat-faced surfaces. In sessile drops, 1-4 mm tabular hopper crystals formed on the free surface and moved to the fixed contact line at the support (polycarbonate or gelatin) self-assembling into a shell. Ring formation created by sessile drop evaporation to dryness was observed but with crystals 100 times larger than particles in terrestrially formed coffee rings. No hopper pyramids formed. By choosing solution geometries offered by microgravity, we found it was possible to selectively grow crystals of preferred morphologies.

  3. Correlates of pre-treatment drop-out among persons with marijuana dependence. (United States)

    Vendetti, Janice; McRee, Bonnie; Miller, Michael; Christiansen, Kenneth; Herrell, James


    Our objective was to identify client characteristics and other factors associated with pre-treatment drop-out by people with marijuana dependence. Data from the Marijuana Treatment Project's screening assessment were used to examine correlates of pre-treatment drop-out. Information from all eligible study participants (n = 813) (i.e. those who were interested in receiving treatment for their marijuana dependence and were determined to be eligible for the randomized treatment efficacy trial) was used to examine differences between the 450 participants who initiated treatment (by enrolling in the trial) and the 363 individuals who declined enrollment. The study was conducted at three community-based outpatient treatment facilities in Farmington, CT, Seattle, WA and Miami, FL. The information gathered in the screening interview included demographic characteristics, residential stability variables, employment and education history and referral source. Substance use variables included the number of days and the number of times per day marijuana was used, self-perceived dependence on marijuana, alcohol or other drugs, other drug use history and current treatment (i.e. substance abuse, medical, psychiatric) situation. Stepwise logistic regression was conducted to confirm variables associated with treatment initiation in bivariate analyses. Pre-treatment drop-out was associated with being younger, unmarried, unemployed, less educated and Asian American or Native American. It was also associated with self-perceived dependence on marijuana and use of other drugs. By recognizing demographic and substance use factors that may serve as barriers for individuals accessing treatment for marijuana dependence, clinicians may target clients with these characteristics proactively to encourage treatment initiation and subsequent attendance.

  4. Drop-On-Drop Multimaterial 3D Bioprinting Realized by Peroxidase-Mediated Cross-Linking. (United States)

    Sakai, Shinji; Ueda, Kohei; Gantumur, Enkhtuul; Taya, Masahito; Nakamura, Makoto


    A cytocompatible inkjet bioprinting approach that enables the use of a variety of bioinks to produce hydrogels with a wide range of characteristics is developed. Stabilization of bioinks is caused by horseradish peroxidase (HRP)-catalyzed cross-linking consuming hydrogen peroxide (H2 O2 ). 3D cell-laden hydrogels are fabricated by the sequential dropping of a bioink containing polymer(s) cross-linkable through the enzymatic reaction and H2 O2 onto droplets of another bioink containing the polymer, HRP, and cells. The ≈95% viability of enclosed mouse fibroblasts and subsequent elongation of the cells in a bioprinted hydrogel consisting of gelatin and hyaluronic acid derivatives suggest the high cytocompatibility of the developed printing approach. The existence of numerous polymers, including derivatives of polysaccharides, proteins, and synthetic polymers, cross-linkable through the HRP-catalyzed reaction, means the current approach shows great promise for biofabrication of functional and structurally complex tissues. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. The effect of surfactant on headspace single drop microextraction for the determination of some volatile aroma compounds in citronella grass and lemongrass leaves by gas chromatography (United States)

    A rapid method for the determination of some volatile aromatic compounds (VACs), including citronellal, citronellol, neral, geranial, geraniol, and eugenol in citronella grass and lemongrass leaves, was developed using surfactant as a surface tension modifier while performing headspace single drop m...

  6. Initial Study

    DEFF Research Database (Denmark)

    Torp, Kristian


    increased. In the initial study presented here, the time it takes to pass an intersection is studied in details. Two major signal-controlled four-way intersections in the center of the city Aalborg are studied in details to estimate the congestion levels in these intersections, based on the time it takes...

  7. Vaporization response of evaporating drops with finite thermal conductivity (United States)

    Agosta, V. D.; Hammer, S. S.


    A numerical computing procedure was developed for calculating vaporization histories of evaporating drops in a combustor in which travelling transverse oscillations occurred. The liquid drop was assumed to have a finite thermal conductivity. The system of equations was solved by using a finite difference method programmed for solution on a high speed digital computer. Oscillations in the ratio of vaporization of an array of repetitivity injected drops in the combustor were obtained from summation of individual drop histories. A nonlinear in-phase frequency response factor for the entire vaporization process to oscillations in pressure was evaluated. A nonlinear out-of-phase response factor, in-phase and out-of-phase harmonic response factors, and a Princeton type 'n' and 'tau' were determined. The resulting data was correlated and is presented in graphical format. Qualitative agreement with the open literature is obtained in the behavior of the in-phase response factor. Quantitatively the results of the present finite conductivity spray analysis do not correlate with the results of a single drop model.

  8. Underwater sound produced by individual drop impacts and rainfall

    DEFF Research Database (Denmark)

    Pumphrey, Hugh C.; Crum, L. A.; Jensen, Leif Bjørnø


    in the frequency range 14–16 kHz. These peaks have been observed by several scientists during measurements of real rain. Our findings provide evidence for the theory that the 14- to 16-kHz spectral peak is caused by the ringing of bubbles entrained in the water by the drop impact process.......An experimental study of the underwater sound produced by water drop impacts on the surface is described. It is found that sound may be produced in two ways: first when the drop strikes the surface and, second, when a bubble is created in the water. The first process occurs for every drop......; the second occurs for some impacts but not others. A range of conditions is described in which a bubble is produced for every drop impact, and it is shown that these conditions are likely to be met by a significant fraction of the raindrops in a typical shower. Underwater sound produced by artificial as well...

  9. Vertical Drop Test of a YS-11 Fuselage Section (United States)

    Minegishi, Masakatsu; Kumakura, Ikuo; Iwasaki, Kazuo; Shoji, Hirokazu; Yoshimoto, Norio; Terada, Hiroyuki; Sashikuma, Hirofumi; Isoe, Akira; Yamaoka, Toshihiro; Katayama, Noriaki; Hayashi, Toru; Akaso, Tetsuya

    The Structures and Materials Research Center of the National Aerospace Laboratory of Japan (NAL) and Kawasaki Heavy Industories, Ltd. (KHI) conducted a vertical drop test of a fuselage section cut from a NAMIC YS-11 transport airplane at NAL vertical drop test facility in December 2001. The main objectives of this program were to obtain background data for aircraft cabin safety by drop test of a full-scale fuselage section and to develop computational method for crash simulation. The test article including seats and anthropomorphic test dummies was dropped to a rigid impact surface at a velocity of 6.1 m/s (20 ft/s). The test condition and result were considered to be severe but potentially survivable. A finite element model of this test article was also developed using the explicit nonlinear transient-dynamic analysis code, LS-DYNA3D. An outline of analytical method and comparison of analysis result with drop test data are presented in this paper.

  10. Dynamics of viscous drops confined in a rough medium (United States)

    Keiser, Ludovic; Gas, Armelle; Jaafar, Khalil; Bico, Jose; Reyssat, Etienne


    We focus on the dynamics of viscous and non-wetting ``pancake'' droplets of oil conned in a vertical Hele-Shaw cell filled with a less viscous surfactant solution. These dense drops settle at constant velocity driven by gravity. The surfactant solution completely wets the walls, and a thin lubrication film separates the drops from the walls. With smooth walls, two main dynamical regimes are characterized as the gap between the walls is varied. Viscous dissipation is found to dominate either in the droplet or in the lubrication film, depending on the ratio of viscosities and length scales. A sharp transition between both regimes is observed and successfully captured by asymptotic models. With rough walls, that transition is dramatically altered. Drops are generally much slower in a rough Hele-Shaw cell, in comparison with a similar smooth cell. Building up on the seminal works of Seiwert et al. (J.F.M. 2011) on film deposition by dip coating on a rough surface, we shed light on the non-trivial friction processes resulting from the interplay of viscous dissipation at the front of the drop, in the lubrication film and in the bulk of the drop. We acknowledge funding from Total S.A.

  11. Drop fragmentation by laser-induced cavitation bubbles (United States)

    Gonzalez-A, S. Roberto; Kerssens, Pjotr; Ohl, Claus-Dieter


    The fragmentation of water droplets by a short laser pulse has received significant attention since the 70's. The fundamental understanding of droplet vaporization/fragmentation is of interest in laser beam propagation in the atmosphere, in situ analysis of combustion products -a great concern due to its ecological implications- and more recently driven by a better understanding of the drop shaping by a laser pulse which is of interest in the development of extreme ultraviolet (EUV) machines. In this presentation we discuss about the incipient events that lead to the fragmentation of a drop produced by a cavitation bubble. When the bubble expands, it stretches the drop into a thin liquid film; this liquid film is eventually ruptured and a shockwave and small droplets are ejected as fast as 4 times the speed of sound in air. Interestingly, we also observe bubbles on the surface of the stretched film. Numerical simulations of a shock wave propagating inside a droplet show that cavitation bubbles appear when counter propagating shock waves that rebound from the walls of the drop meet. We also show different fragmentation scenarios recorded with high-speed video, one of them being a jelly fish like liquid film that eventually fragments into smaller drops.

  12. A PIV Study of Drop-interface Coalescence with Surfactants (United States)

    Weheliye, Weheliye Hashi; Dong, Teng; Angeli, Panagiota


    In this work, the coalescence of a drop with an aqueous-organic interface was studied by Particle Image Velocimetry (PIV). The effect of surfactants on the drop surface evolution, the vorticity field and the kinetic energy distribution in the drop during coalescence were investigated. The coalescence took place in an acrylic rectangular box with 79% glycerol solution at the bottom and Exxsol D80 oil above. The glycerol solution drop was generated through a nozzle fixed at 2cm above the aqueous/oil interface and was seeded with Rhodamine particles. The whole process was captured by a high-speed camera. Different mass ratios of non-ionic surfactant Span80 to oil were studied. The increase of surfactant concentration promoted deformation of the interface before the rupture of the trapped oil film. At the early stages after film rupture, two counter-rotating vortices appeared at the bottom of the drop which then travelled to the upper part. The propagation rates, as well as the intensities of the vortices decreased at high surfactant concentrations. At early stages, the kinetic energy was mainly distributed near the bottom part of the droplet, while at later stages it was distributed near the upper part of the droplet. Programme Grant MEMPHIS, Chinese Scholarship Council (CSC).

  13. Experimental study of drop impacts on soap films (United States)

    Yawar, Ali; Basu, Saikat; Concha, Andres; Bandi, Mahesh


    Impinging drops on flowing and static soap films demonstrate at least three distinct types of impact regimes: (a) the drop bounces off the film surface, (b) it coalesces with the downstream flow for a moving film and for static films it gets assimilated within the film, and (c) it pierces through the film. The interaction presents a unique opportunity to explore the impact of a quasi one-dimensional object on a two-dimensional fluid, much like a comet impacting on a thin atmosphere. We present a detailed experimental study of droplet impacts on soap film flow, for a number of film inclination angles and falling heights of the drop. Imaging techniques employed include sodium lamp interferometry to measure film thickness fluctuations and particle tracking velocimetry to measure the velocity field. Film thickness measures approximately 10 microns and the drop diameter is 1 mm. We mostly observe the bouncing-off regime for smaller inclination angles. However, at higher impact angles, puncturing of the film becomes a more common occurrence. We show that when the drop bounces off the film, there is a momentum transfer leading to vortex dipole shedding, along with the generation of capillary waves; an impulsive regime that may share correspondence with the locomotion of water striders.

  14. A Novel Virus Causes Scale Drop Disease in Lates calcarifer. (United States)

    de Groof, Ad; Guelen, Lars; Deijs, Martin; van der Wal, Yorick; Miyata, Masato; Ng, Kah Sing; van Grinsven, Lotte; Simmelink, Bartjan; Biermann, Yvonne; Grisez, Luc; van Lent, Jan; de Ronde, Anthony; Chang, Siow Foong; Schrier, Carla; van der Hoek, Lia


    From 1992 onwards, outbreaks of a previously unknown illness have been reported in Asian seabass (Lates calcarifer) kept in maricultures in Southeast Asia. The most striking symptom of this emerging disease is the loss of scales. It was referred to as scale drop syndrome, but the etiology remained enigmatic. By using a next-generation virus discovery technique, VIDISCA-454, sequences of an unknown virus were detected in serum of diseased fish. The near complete genome sequence of the virus was determined, which shows a unique genome organization, and low levels of identity to known members of the Iridoviridae. Based on homology of a series of putatively encoded proteins, the virus is a novel member of the Megalocytivirus genus of the Iridoviridae family. The virus was isolated and propagated in cell culture, where it caused a cytopathogenic effect in infected Asian seabass kidney and brain cells. Electron microscopy revealed icosahedral virions of about 140 nm, characteristic for the Iridoviridae. In vitro cultured virus induced scale drop syndrome in Asian seabass in vivo and the virus could be reisolated from these infected fish. These findings show that the virus is the causative agent for the scale drop syndrome, as each of Koch's postulates is fulfilled. We have named the virus Scale Drop Disease Virus. Vaccines prepared from BEI- and formalin inactivated virus, as well as from E. coli produced major capsid protein provide efficacious protection against scale drop disease.

  15. Handling Test of Eye Drop Dispenser—Comparison of Unit-Dose Pipettes with Conventional Eye Drop Bottles (United States)

    Latvala, Terho; Ropo, Auli


    Abstract Purpose The aims of this study were to investigate how elderly people handle single-use eye drop dispensers (unit-dose pipettes) and to compare the performance with conventional eye drop bottles. Methods In this open-label study, the handling of unit-dose pipettes and conventional eye drop bottles was compared in 41 elderly people who had little or no prior regular use of eye drop dispensers. The participants tested both types of dispenser once, and the following 7 variables were studied: ease/difficulty of opening the dispenser; influence of the size for handling of the dispenser; influence of the shape for handling of the dispenser; observation of the contents in the dispenser; the feeling of the dispenser in the hand; ease/difficulty of drop instillation on the eye from the dispenser; and overall performance of the eye drop dispenser. The dispensers contained isotonic saline, and a visual analog scale was used for assessment of each of the above variables. Results The mean age of the participants was 73 years. A statistically significant difference in favor of the unit-dose pipettes was found with respect to observation of the contents in the dispenser, ease of administration, and the overall performance. Women regarded the unit-dose pipettes generally better than the bottles, but such a difference was not seen in men. Conclusions The study participants managed the unit-dose pipettes at least as well as the conventional eye drop bottles. If anything, the unit-dose pipettes appeared to be easier to use. PMID:20565314

  16. Rapid maxillary expansion (RME) for pediatric obstructive sleep apnea: a 12-year follow-up. (United States)

    Pirelli, Paola; Saponara, Maurizio; Guilleminault, Christian


    The objective of this study was to prospectively evaluate the long-term efficacy of rapid maxillary expansion (RME) in a group of children with obstructive sleep apnea (OSA). Thirty-one children diagnosed with OSA were involved in the study. These children had isolated maxillary narrowing and absence of enlarged adenotonsils at baseline. Twenty-three individuals (73% of the initial group) were followed up annually over a mean of 12 years after the completion of orthodontic treatment at a mean age of 8.68 years. Eight children dropped out over time due to either moving out of the area (n = 6) or refusal to submit to regular follow-up (n = 2). Subjects underwent clinical reevaluation over time and repeat polysomnography (PSG) in the late teenage years or in their early 20s. During the follow-up period, eight children dropped out and 23 individuals (including 10 girls) underwent a final clinical investigation with PSG (mean age of 20.9 years). The final evaluation also included computerized tomographic (CT) imaging that was compared with pre- and post-initial treatment findings. Yearly clinical evaluations, including orthodontic and otolaryngological examinations and questionnaire scores, were consistently normal over time, and PSG findings remained normal at the 12-year follow-up period. The stability and maintenance of the expansion over time was demonstrated by the maxillary base width and the distance of the pterygoid processes measured using CT imaging. A subgroup of OSA children with isolated maxillary narrowing initially and followed up into adulthood present stable, long-term results post RME treatment for pediatric OSA. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. A rapid molecular approach for chromosomal phasing.

    Directory of Open Access Journals (Sweden)

    John F Regan

    Full Text Available Determining the chromosomal phase of pairs of sequence variants - the arrangement of specific alleles as haplotypes - is a routine challenge in molecular genetics. Here we describe Drop-Phase, a molecular method for quickly ascertaining the phase of pairs of DNA sequence variants (separated by 1-200 kb without cloning or manual single-molecule dilution. In each Drop-Phase reaction, genomic DNA segments are isolated in tens of thousands of nanoliter-sized droplets together with allele-specific fluorescence probes, in a single reaction well. Physically linked alleles partition into the same droplets, revealing their chromosomal phase in the co-distribution of fluorophores across droplets. We demonstrated the accuracy of this method by phasing members of trios (revealing 100% concordance with inheritance information, and demonstrate a common clinical application by phasing CFTR alleles at genomic distances of 11-116 kb in the genomes of cystic fibrosis patients. Drop-Phase is rapid (requiring less than 4 hours, scalable (to hundreds of samples, and effective at long genomic distances (200 kb.

  18. Criteria for drop generation in multiphase microfluidic devices. (United States)

    Buttacci, Joseph D; Loewenberg, Michael; Roberts, Christine C; Nemer, Martin B; Rao, Rekha R


    A theory is presented for the transition between the coflowing and the drop-generation regimes observed in microfluidic channels with a rectangular cross section. This transition is characterized by a critical ratio of the dispersed- to continuous-phase volume flow rates. At flow-rate ratios higher than this critical value, drop generation is suppressed. The critical ratio corresponds to the fluid cross section where the dispersed-phase fluid is just tangent to the channel walls. The transition criterion is a function of the ratio of the fluid viscosities, the three-phase contact angle formed between the fluid phases and the channel walls, and the aspect ratio of the channel cross section; the transition is independent of interfacial tension. Hysteretic behavior of drop generation with respect to the flow-rate ratio is predicted for partially wetting dispersed-phase fluids. Experimental data are consistent with this theory.

  19. Interfacial Dynamics of Thin Viscoelastic Films and Drops

    CERN Document Server

    Barra, Valeria; Kondic, Lou


    We present a computational investigation of thin viscoelastic films and drops on a solid substrate subject to the van der Waals interaction force. The governing equations are obtained within a long-wave approximation of the Navier-Stokes equations with Jeffreys model for viscoelastic stresses. We investigate the effects of viscoelasticity, Newtonian viscosity, and the substrate slippage on the dynamics of thin viscoelastic films. We also study the effects of viscoelasticity on drops that spread or recede on a prewetted substrate. For dewetting films, the numerical results show the presence of multiple secondary droplets for higher values of elasticity, consistently with experimental findings. For drops, we find that elastic effects lead to deviations from the Cox-Voinov law for partially wetting fluids. In general, elastic effects enhance spreading, and suppress retraction, compared to Newtonian ones.

  20. Viscosity Measurement via Drop Coalescence: A Space Station Experiment (United States)

    Antar, Basil; Ethridge, Edwin C.


    The concept of using low gravity experimental data together with CFD simulations for measuring the viscosity of highly viscous liquids was recently validated on onboard the International Space Station (ISS). A series of microgravity tests were conducted for this purpose on the ISS in July, 2004 and in May of 2005. In these experiments two liquid drops were brought manually together until they touched and were allowed to coalesce under the action of the capillary force alone. The coalescence process was recorded photographically from which the contact radius speed of the merging drops was measured. The liquid viscosity was determined by fitting the measured data with accurate numerical simulation of the coalescence process. Several liquids were tested and for each liquid several drop diameters were employed. Experimental and numerical results will be presented in which the viscosity of several highly viscous liquids were determined using this technique.

  1. Green chemistry and nanofabrication in a levitated Leidenfrost drop (United States)

    Abdelaziz, Ramzy; Disci-Zayed, Duygu; Hedayati, Mehdi Keshavarz; Pöhls, Jan-Hendrik; Zillohu, Ahnaf Usman; Erkartal, Burak; Chakravadhanula, Venkata Sai Kiran; Duppel, Viola; Kienle, Lorenz; Elbahri, Mady


    Green nanotechnology focuses on the development of new and sustainable methods of creating nanoparticles, their localized assembly and integration into useful systems and devices in a cost-effective, simple and eco-friendly manner. Here we present our experimental findings on the use of the Leidenfrost drop as an overheated and charged green chemical reactor. Employing a droplet of aqueous solution on hot substrates, this method is capable of fabricating nanoparticles, creating nanoscale coatings on complex objects and designing porous metal in suspension and foam form, all in a levitated Leidenfrost drop. As examples of the potential applications of the Leidenfrost drop, fabrication of nanoporous black gold as a plasmonic wideband superabsorber, and synthesis of superhydrophilic and thermal resistive metal-polymer hybrid foams are demonstrated. We believe that the presented nanofabrication method may be a promising strategy towards the sustainable production of functional nanomaterials.

  2. Investigating Call Drops with Field Measurements on Commercial Mobile Phones

    DEFF Research Database (Denmark)

    Messina, Alessandro; Caragea, Gabriel; Compta, Pol Torres


    One of the biggest problems nowadays for network operators are occurring call drops. This problem has been increasing in the last years specially since the advent of 3G. The investigation in the operator's network is very time intensive and due to the highly priced hardware only a few measurements...... can be done per day. In this paper we present a new methodology to investigate call drops by using mobile phones to do the measurements following the concept of citizen sensing. Therefore, a mobile application for Android is made that collects all necessary data and dumps the measurement results...... in a centralized database where the measurements are evaluated and represented on Google Maps. With a post analysis of the measurements, a classification of the call drops results is made. The collected data is also used to show some statistics related to the battery level and the received signal strength between...

  3. Frictionally induced ignition processes in drop and skid tests

    Energy Technology Data Exchange (ETDEWEB)

    Dickson, Peter [Los Alamos National Laboratory; Parker, Gary [Los Alamos National Laboratory; Novak, Alan [Los Alamos National Laboratory


    The standard LANL/Pantex drop and skid tests rely on subjective assessment of reaction violence to quantify the response of the charge, and completely miss nonpropagating hot-spot ignition sites. Additionally, large variations in test results have been observed, which we propose is due to a misunderstanding of the basic physical processes that lead to threshold ignition in these tests. The tests have been redesigned to provide control of these mechanisms and to permit direct observation of hot spots at the impact site, allowing us to follow the progression of the outcome as the drop height and ignition source density are varied. The results confirm that frictional interactions between high-melting-point solids are the dominant ignition mechanism, not just at the threshold, but in fact at all realistic drop heights.

  4. Structural concerns in dynamic drop loads on transfer lock mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Pfeiffer, P.A.; Moran, T.J.; Kulak, R.F. [Argonne National Lab., IL (United States). Reactor Engineering Div.


    Drop loads are usually low probability events that can generate substantial loading to the impacted structures. When the impacted structure contains slender elements, the concern about dynamic buckling must be addressed. The problem of interest here is a structure is also under significant preload, which must be taken into account in the transient analysis. For complex structures, numerical simulations are the only viable option for assessing the transient response to short duration impactive loads. this paper addresses several analysis issues of preloaded structures with slender members subjected to drop loads. A three-dimensional beam element is validated for use in dynamic buckling analysis. the numerical algorithm used to solve the transient response of preloaded structures is discussed. The methodology is applied to an inter-compartment lock that is under significant preloads, and subjected to a drop load.

  5. Estimation of pressure drop in gasket plate heat exchangers

    Directory of Open Access Journals (Sweden)

    Neagu Anisoara Arleziana


    Full Text Available In this paper, we present comparatively different methods of pressure drop calculation in the gasket plate heat exchangers (PHEs, using correlations recommended in literature on industrial data collected from a vegetable oil refinery. The goal of this study was to compare the results obtained with these correlations, in order to choose one or two for practical purpose of pumping power calculations. We concluded that pressure drop values calculated with Mulley relationship and Buonopane & Troupe correlation were close and also Bond’s equation gave results pretty close to these but the pressure drop is slightly underestimated. Kumar correlation gave results far from all the others and its application will lead to oversize. In conclusion, for further calculations we will chose either the Mulley relationship or the Buonopane & Troupe correlation.

  6. Hemolymph drop impact outcomes on surfaces with varying wettability (United States)

    Milionis, Athanasios; Ghokulla Krishnan, K.; Loth, Eric


    Insect fouling from coagulated hemolymph and exoskeleton parts is a major challenge in the aerospace industry for the next generation of aerodynamic surfaces, which will employ laminar flow that requires extremely smooth surfaces. However, the wetting physics and dynamics of hemolymph (insect blood) on surfaces are not well understood. The present study seeks to gain a fundamental insight on the effect of surface wetting characteristics and dynamics resulting from a hemolymph drop impact, the first such study. In particular, hemolymph drops extracted from Acheta domesticus were dispensed from a range of heights to vary the kinetic impact on surfaces, which had widely varying water wetting behavior (from superhydrophilic to superhydrophobic). The impact dynamics were investigated with high-speed imaging while the dried residues were studied with optical microscopy. It was found that a superhydrophobic surface (based on thermoplastic with silica nano-particles) was able to significantly reduce hemolymph drop spreading, and even provide complete rebound when impacting on inclined surfaces.

  7. Karakteristik Penderita Drop out Pengobatan Tuberkulosis Paru di Garut

    Directory of Open Access Journals (Sweden)

    Nevi Nurkomarasari


    Full Text Available Abstrak Tuberkulosis masih menjadi masalah penyakit infeksi di dunia termasuk di Indonesia. Walaupun penggunaan Directly Observed Treatment Shortcourse Chemotherapy (DOTS sebagai terapi yang direkomendasikan World Helath Organization (WHO dipergunakan, kasus drop out masih cukup tinggi. Penelitian ini dilakukan untuk menggambarkan faktor yang mempengaruhi kejadian drop out di Puskesmas Sukamerang, Garut selama tahun 2011. Penelitian ini menggunakan metode cross sectional dengan instrument penelitian berupa kuesioner yang didasarkan pada petunjuk perawatan TB yang diterbitkan oleh Kementrian Kesehatan. Subjek adalah semua penderita TB yang drop out selama pengobatan di Puskesmas Sukamerang, Garut sejumlah 30 orang. Analisis data dilakukan menggunakan statistical programme for social sciense (SPSS versi 17. Hasil penelitian menunjukkan bahwa pasien TB drop out adalah laki-laki dengan usia < 35 tahun, pendidikan tamat SMP, pendapatan di bawah upah minimum regional dan bekerja sebagai buruh. Tingkat pengetahuan tentang TB paru penderita drop out pengobatan TB paru dan sikap mereka termasuk kurang baik walaupun peran pengawas menelan obat (PMO telah cukup baik. Masalah tersebut ditambah dengan sulitnya akses menuju pelayanan kesehatan. Upaya penting dalam penanganan kasus TB adalah bagaimana memotivasi penderita agar mereka mau menyelesaikan pengobatan sesuai dengan program  yang ditetapkan. Untuk mewujudkan upaya tersebut, diharapkan program penanggulangan TB paru  dapat meningkatkan upaya penjaringan penderita TB paru dan meningkatkan strategi pelaksanaan pengobatan TB paru melalui penyebaran informasi tentang pengobatan TB paru dan peningkatan peranan PMO. Kata kunci: Drop out, pengetahuan dan sikap, tuberkulosis (TB   Characteristics of Drop Out Patients During Treatment of Pulmonary Tuberculosis in Garut Abstract Tuberculosis is still one of the major infectious disease in the world including Indonesia. Although the therapy using Directly

  8. Tear fluid-eye drops compatibility assessment using surface tension. (United States)

    Hotujac Grgurević, Martina; Juretić, Marina; Hafner, Anita; Lovrić, Jasmina; Pepić, Ivan


    To evaluate the compatibility of commercially available eye drop surface tension with the tear film physiological range and to characterize commonly used ophthalmic excipients in terms of their surface activity under eye-biorelevant conditions. There are a number of quality requirements for the eye drops (e.g. tonicity, pH, viscosity, refractive index) that needs to comply with the physiological parameters of the eye surface. However, the adjustment of surface tension properties of the eye drops to the normal range of surface tension at the air/tear fluid interface (40-46 mN/m) has received rather less attention thus far. Yet, the surface tension at the air/tear fluid interface is of vital importance for the normal function of the eye surface. The surface tension compatibility of the isotonic aqueous solutions of commonly used ophthalmic excipients as well as 18 approved eye drops with the tear fluid have been evaluated using surface tension method. Each ophthalmic ingredient including the preservatives, solubilizing agents and thickening agents can influence the surface tension of the final formulation. In case of complex ophthalmic formulations one should also consider the possible interactions among excipients and consequent impact on overall surface activity. Out of 18 evaluated eye drops, three samples were within, 12 samples were below and three samples were above the physiological range of the tear fluid surface tension. Our results provide a rationale for clinical studies aiming to assess the correlation between the eye drops surface tension and the tear film (in)stability.

  9. Drop-out probabilities of IrisPlex SNP alleles

    DEFF Research Database (Denmark)

    Andersen, Jeppe Dyrberg; Tvedebrink, Torben; Mogensen, Helle Smidt


    In certain crime cases, information about a perpetrator's phenotype, including eye colour, may be a valuable tool if no DNA profile of any suspect or individual in the DNA database matches the DNA profile found at the crime scene. Often, the available DNA material is sparse and allelic drop......-out when the amount of DNA was greater than 125 pg for 29 cycles of PCR and greater than 62 pg for 30 cycles of PCR. With the use of a logistic regression model, we estimated the allele specific probability of drop-out in heterozygote systems based on the signal strength of the observed allele...

  10. Drop and Recovery of Sensor Nodes Using UAVs


    Voldsund, Vegard


    The goal of this project is to make a system able of executing drop and recovery of sensor nodes at sea by the use of UAVs.The sensor node will be a lightweight packet that can contain different sensors depending on the mission. These sensor nodes will be dropped into the sea where they will float on the surface. Examples of use for the sensor nodes can be to log temperature, currents, salinity or water quality. Hence they can be very useful in for instance climate research or for detectingoi...

  11. Drops and bubbles in contact with solid surfaces

    CERN Document Server

    Ferrari, Michele


    The third volume in a series dedicated to colloids and interfaces, Drops and Bubbles in Contact with Solid Surfaces presents an up-to-date overview of the fundamentals and applications of drops and bubbles and their interaction with solid surfaces. The chapters cover the theoretical and experimental aspects of wetting and wettability, liquid-solid interfacial properties, and spreading dynamics on different surfaces, including a special section on polymers. The book examines issues related to interpretation of contact angle from nano to macro systems. Expert contributors discuss interesting pec

  12. Medium carbon vanadium micro alloyed steels for drop forging

    Energy Technology Data Exchange (ETDEWEB)

    Jeszensky, Gabor; Plaut, Ronald Lesley


    Growing competitiveness of alternative manufacturing routes requires cost minimization in the production of drop forged components. The authors analyse the potential of medium carbon, vanadium microalloyed steels for drop forging. Laboratory and industrial experiments have been carried out emphasizing deformation and temperature cycles, strain rates and dwell times showing a typical processing path, associated mechanical properties and corresponding microstructures. The steels the required levels of mechanical properties on cooling after forging, eliminating subsequent heat treatment. The machinability of V-microalloyed steels is also improved when compared with plain medium carbon steels. (author) 17 refs., 19 figs., 5 tabs.

  13. Zero-Gravity Research Facility Drop Test (2/4) (United States)


    An experiment vehicle plunges into the deceleration pit at the end of a 5.18-second drop in the Zero-Gravity Research Facility at NASA's Glenn Research Center. The Zero-Gravity Research Facility was developed to support microgravity research and development programs that investigate various physical sciences, materials, fluid physcis, and combustion and processing systems. Payloads up to 1 meter in diameter and 455 kg in weight can be accommodated. The facility has a 145-meter evacuated shaft to ensure a disturbance-free drop. This is No. 2 of a sequence of 4 images. (Credit: NASA/Glenn Research Center)

  14. Zero-Gravity Research Facility Drop Test (3/4) (United States)


    An experiment vehicle plunges into the deceleration at the end of a 5.18-second drop in the Zero-Gravity Research Facility at NASA's Glenn Research Center. The Zero-Gravity Research Facility was developed to support microgravity research and development programs that investigate various physical sciences, materials, fluid physics, and combustion and processing systems. Payloads up to one-meter in diameter and 455 kg in weight can be accommodated. The facility has a 145-meter evacuated shaft to ensure a disturbance-free drop. This is No. 3 of a sequence of 4 images. (Credit: NASA/Glenn Research Center)

  15. Zero-Gravity Research Facility Drop Test (1/4) (United States)


    An experiment vehicle plunges into the deceleration pit at the end of a 5.18-second drop in the Zero-Gravity Research Facility at NASA's Glenn Research Center. The Zero-Gravity Research Facility was developed to support microgravity research and development programs that investigate various physical sciences, materials, fluid physics, and combustion and processing systems. Payloads up to 1 meter in diameter and 455 kg in weight can be accommodated. The facility has a 145-meter evacuated shaft to ensure a disturbance-free drop. This is No.1 of a sequence of 4 images. (Credit: NASA/Glenn Research Center)

  16. Zero-Gravity Research Facility Drop Test (4/4) (United States)


    An experiment vehicle plunges into the deceleration pit at the end of a 5.18-second drop in the Zero-Gravity Research Facility at NASA's Glenn Research Center. The Zero-Gravity Research Facility was developed to support microgravity research and development programs that investigate various physical sciences, materials, fluid physics, and combustion and processing systems. Payloads up to one meter in diameter and 455 kg in weight can be accommodated. The facility has a 145-meter evacuated shaft to ensure a disturbance-free drop. This is No. 4 of a sequence of 4 images. (Credit: NASA/Glenn Research Center)

  17. Topical Coenzyme Q10 Eye Drops as an Adjuvant Treatment in Challenging Refractory Corneal Ulcers: A Case Series and Literature Review. (United States)

    Gumus, Koray


    The management of nonhealing corneal ulcers, particularly in patients with neurotrophic corneas, remains a challenging problem today. Some patients may fail to respond to conventional therapy, making new alternative agents necessary to treat these resistant cases. In this article, we aim to present six challenging cases of refractory corneal ulcers that revealed healing response to the adjuvant treatment with coenzyme Q10 (CoQ10) eye drops and to review the literature examining of new therapeutic agents. Our study was designed as a descriptive case series demonstrating the use of novel coenzyme Q10 eye drops in refractory corneal ulcers. In our case series, CoQ10 eye drops were added to the existing therapies as an adjuvant agent in six cases: three cases with neurotrophic corneal ulcers, two cases with postinfectious corneal ulcers (one unknown etiology+one Acanthamoeba keratitis), and 1 case with Stevens-Johnson syndrome. All cases were monitored regularly and corneal images were taken at all visits. All nonhealing corneas with conventional therapy revealed recovery after the addition of CoQ10 eye drops. Except for two cases that responded to the CoQ10 eye drops more rapidly (within 1 to 2 weeks), complete corneal healing was observed in four cases between weeks 4 and 8. No adverse events were reported in these cases throughout the follow-up period. Coenzyme Q10 eye drops can be considered as an important adjuvant therapeutic agent promoting corneal epithelial wound healing in challenging cases.

  18. Many Drops Interactions II: Simulation of Coalescence, Flocculation and Fragmentation of Multiple Colliding Drops with Smoothed Particle Hydrodynamics

    Directory of Open Access Journals (Sweden)

    Alejandro Acevedo-Malavé


    Full Text Available In this study, the SPH method is applied to simulate for the first time the multiple hydrodynamics collisions and the formation of clusters of equally sized liquid drops in three-dimensional space. Smoothed Particle Hydrodynamics is a Lagrangian mesh-free formalism and has been useful to model continuous fluid. This formalism is employed to solve the Navier-Stokes equations by replacing the fluid with a set of particles. These particles are interpolation points from which properties of the fluid can be determined. We observe that when the velocity of collision varies between 0.2 mm/ms and 30.0 mm/ms different results may arise, such as: coalescence, fragmentation and formation of clusters of liquid drops. The velocity vector fields formed inside the drops during the collision process are shown.

  19. Effect of recombinant human epidermal growth factor eye drops and deproteinized calf blood extract eye drops on corneal edema after phacoemulsification

    National Research Council Canada - National Science Library

    Jia Wang


    AIM:To compare the effect of recombinant human epidermal growth factor eye drops and deproteinized calf blood extract eye drops on corneal edema after phacoemulsification. METHODS:Totally 72 cases(72 eyes...

  20. Investigation of drop geometry at free-falling process depending on volume of dozing

    Directory of Open Access Journals (Sweden)

    Batischeva Ksenia A.


    Full Text Available Present work performs experimental investigation of the changes in the geometric shape of the drop in terms of its free-falling, depending on the conditions of drop formation on dispenser. It was found that volume and velocity of drop formation on dispenser are the factors affecting the geometric shape of the drop in terms of its free-falling.

  1. Corneal staining reductions observed after treatment with Systane Lubricant Eye Drops. (United States)

    Christensen, Mike T


    Because of the added emphasis on ocular surface damage included in the Dry Eye Workshop's revised definition of dry eye, an evaluation of corneal staining reductions was conducted for propylene glycol/polyethylene glycol 400-based artificial tear drops (Systane Lubricant Eye Drops; Alcon Laboratories, Fort Worth, TX, USA). An analysis was conducted on the percent change from baseline in mean corneal staining scores as reported in two previously published, randomized, double-masked, 6-week clinical studies of Systane. A descriptive comparison was also made between the outcome of the composite analysis and data obtained for Optivetrade mark Lubricant Eye Drops (Allergan, Inc., Irvine, CA, USA). Finally, results were reviewed for an open-label study that investigated corneal staining over a 5-week period after patients discontinued Systane therapy. The composite analysis included 107 Systane-treated patients. The results showed that Systane consistently reduced corneal staining at each visit; the percent change from baseline to day 42 (exit) was 47.1% (P<0.0001). After discontinuing Systane, immediate and significant increases in corneal staining were reported by 20 patients, with an overall increase from baseline to day 35 (exit) of 195.0% (P<0.0001). Evaluations of sum corneal ocular staining scores provide clinically meaningful evidence of dry eye severity, and are an important indicator of dry eye disease progression. The results of the composite analysis of two peer-reviewed studies indicate that Systane significantly reduced corneal staining (P<0.0001), indicating a reduction in the severity of dry eye. Finally, discontinuation of Systane results in a rapid increase in corneal staining that further confirms Systane's ability to maintain ocular surface health.

  2. Drop-in Security for Distributed and Portable Computing Elements. (United States)

    Prevelakis, Vassilis; Keromytis, Angelos


    Proposes the use of a special purpose drop-in firewall/VPN gateway called Sieve, that can be inserted between the mobile workstation and the network to provide individualized security services for that particular station. Discusses features and advantages of the system and demonstrates how Sieve was used in various application areas such as at…

  3. Electrowetting: a versatile tool for drop manipulation, generation, and characterization. (United States)

    Mugele, Frieder; Duits, Michel; van den Ende, Dirk


    Electrowetting is arguably the most flexible tool to control and vary the wettability of solid surfaces by an external control parameter. In this article we briefly discuss the physical origin of the electrowetting effect and subsequently present a number of approaches for selected novel applications. Specifically, we will discuss the use of EW as a tool to extract materials properties such as interfacial tensions and elastic properties of drops. We will describe some modifications of the EW equation that apply at finite AC voltage for low conductivity fluids when the electric field can partially penetrate into the drops. We will discuss two examples where finite conductivity effects have important consequences, namely electrowetting of topographically structured surfaces as well as the generation of drops in AC electric fields. Finally, we review recent attempts to incorporate electrowetting into conventional channel-based microfluidic devices in order to enhance the flexibility of controlling the generation of drops. Copyright © 2009 Elsevier B.V. All rights reserved.

  4. Analysis of Drop Call Probability in Well Established Cellular ...

    African Journals Online (AJOL)

    Technology in Africa has increased over the past decade. The increase in modern cellular networks requires stringent quality of service (QoS). Drop call probability is one of the most important indices of QoS evaluation in a large scale well-established cellular network. In this work we started from an accurate statistical ...

  5. Clinical utility of voriconazole eye drops in ophthalmic fungal keratitis (United States)

    Al-Badriyeh, Daoud; Neoh, Chin Fen; Stewart, Kay; Kong, David CM


    Fungal keratitis is one of the major causes of ophthalmic mycosis and is difficult to treat. The range of common antifungal agents available for fungal keratitis remains inadequate and is generally associated with poor clinical outcomes. Voriconazole is a new generation triazole antifungal agent. Only marketed in systemic formulation and, with broad-spectrum activity and high intraocular penetration, voriconazole has demonstrated effectiveness against fungal keratitis. Systemic voriconazole, however, is not without side effects and is costly. Voriconazole eye drops have been prepared extemporaneously and used for the treatment of ophthalmic fungal keratitis. The current article sought to review the literature for evidence related to the effectiveness and safety of topical voriconazole and its corneal penetration into the aqueous humor of the eye. The voriconazole eye drops used are typically of 1% concentration, well tolerated by the eye, and are stable. Despite existing evidence to suggest that the eye drops are effective in the treatment of fungal keratitis, more studies are needed, especially in relation to using the eye drops as first-line and stand-alone treatment, preparation of higher concentrations, and optimal dosing frequency. PMID:20463910

  6. Measurement of surface and interfacial tension using pendant drop tensiometry. (United States)

    Berry, Joseph D; Neeson, Michael J; Dagastine, Raymond R; Chan, Derek Y C; Tabor, Rico F


    Pendant drop tensiometry offers a simple and elegant solution to determining surface and interfacial tension - a central parameter in many colloidal systems including emulsions, foams and wetting phenomena. The technique involves the acquisition of a silhouette of an axisymmetric fluid droplet, and iterative fitting of the Young-Laplace equation that balances gravitational deformation of the drop with the restorative interfacial tension. Since the advent of high-quality digital cameras and desktop computers, this process has been automated with high speed and precision. However, despite its beguiling simplicity, there are complications and limitations that accompany pendant drop tensiometry connected with both Bond number (the balance between interfacial tension and gravitational forces) and drop volume. Here, we discuss the process involved with going from a captured experimental image to a fitted interfacial tension value, highlighting pertinent features and limitations along the way. We introduce a new parameter, the Worthington number, Wo, to characterise the measurement precision. A fully functional, open-source acquisition and fitting software is provided to enable the reader to test and develop the technique further. Crown Copyright © 2015. Published by Elsevier Inc. All rights reserved.

  7. Drop morphologies on flexible fibers: influence of elastocapillary effects. (United States)

    Sauret, Alban; Boulogne, François; Somszor, Katarzyna; Dressaire, Emilie; Stone, Howard A


    Various materials are made of long thin fibers that are randomly oriented to form a complex network in which drops of wetting liquid tend to accumulate at the nodes. The capillary force exerted by the liquid can bend flexible fibers, which in turn influences the morphology adopted by the liquid. In this paper, we investigate through a model situation the role of the fiber flexibility on the shape of a small volume of liquid on a pair of crossed flexible fibers. We characterize the liquid morphologies as we vary the volume of liquid, the angle between the fibers, and the length of the fibers. The drop morphologies previously reported for rigid crossed fibers, i.e., a drop, a column and a mixed morphology, are also observed on flexible crossed fibers with modified domains of existence. In addition, at small tilt angles between the fibers, a new behavior is observed: the fibers bend and collapse. Depending on the volume of liquid, a thin column with or without a drop is reported on the collapsed fibers. Our study suggests that the fiber flexibility adds a rich variety of behaviors that may be important for some applications.

  8. Using Single Drop Microextraction for Headspace Analysis with Gas Chromatography (United States)

    Riccio, Daniel; Wood, Derrick C.; Miller, James M.


    Headspace (HS) gas chromatography (GC) is commonly used to analyze samples that contain non-volatiles. In 1996, a new sampling technique called single drop microextraction, SDME, was introduced, and in 2001 it was applied to HS analysis. It is a simple technique that uses equipment normally found in the undergraduate laboratory, making it ideal…

  9. Structure Irregularity Impedes Drop Roll-Off at Superhydrophobic Surfaces

    DEFF Research Database (Denmark)

    Larsen, Simon Tylsgaard; Andersen, Nis Korsgaard; Søgaard, Emil


    -off angles is found to be caused by a decrease of the receding contact angle, which in turn is caused by an increase of the triple phase contact line of the drops for those more irregular surfaces. To understand the observation, we propose to treat the microdrops as rigid bodies and apply a torque balance...

  10. Physiological and biochemical changes during banana ripening and finger drop

    NARCIS (Netherlands)

    Imsabai, W.; Ketsa, S.; Doorn, van W.G.


    Fruit drop of banana is due to breaking at the junction of the pedicel and pulp, and we found no true abscission zone. The breakage seems therefore due to weakening of the peel. We investigated pectin hydrolysis and some properties at the rupture zone, using `Hom Thong` (Musa acuminata, AAA Group)

  11. Effects of relative humidity on banana fruit drop

    NARCIS (Netherlands)

    Saengpook, C.; Ketsa, S.; Doorn, van W.G.


    Commercial ripening of banana fruit occurs at high relative humidity (RH), which prevents browning of damaged skin areas. In experiments with ripening at high RH (94 ± 1%) the individual fruit (fingers) of `Sucrier¿ (Musa acuminata, AA Group) banana exhibited a high rate of drop. The falling off of

  12. Reducing cyclone pressure drop with evasés (United States)

    Cyclones are widely used to separate particles from gas flows and as air emissions control devices. Their cost of operation is proportional to the fan energy required to overcome their pressure drop. Evasés or exit diffusers potentially could reduce exit pressure losses without affecting collection...

  13. Allelic drop-out probabilities estimated by logistic regression

    DEFF Research Database (Denmark)

    Tvedebrink, Torben; Eriksen, Poul Svante; Asplund, Maria


    We discuss the model for estimating drop-out probabilities presented by Tvedebrink et al. [7] and the concerns, that have been raised. The criticism of the model has demonstrated that the model is not perfect. However, the model is very useful for advanced forensic genetic work, where allelic dro...

  14. Drop amalgam voltammetric study of lead complexation by natural ...

    African Journals Online (AJOL)

    A study of inorganic complexation of lead using drop amalgam voltammetry is described. The study has been carried out in simulated salt lake water and at ionic strength of 7.35 M, the predetermined ionic strength of Lake Katwe. The complexation of lead with the simple ligands (Cl-, CO32-) created anodic waves and the ...

  15. Personality disorders and treatment drop out in the homeless

    National Research Council Canada - National Science Library

    Salavera, Carlos; Tricás, José M; Lucha, Orosia


    ... the situation, and their inertia, determines treatment abandonment, with higher levels than in other populations. (8-10) Studies on withdrawal from treatment in people under addiction treatment have been done (11-16) and these have analyzed the comorbidity between dropping out and personality disorders. (17) The reviewed literature concludes t...

  16. Capillarity and wetting phenomena drops, bubbles, pearls, waves

    CERN Document Server

    Gennes, Pierre-Gilles; Quéré, David


    As I glance out my window in the early morning, I can see beads of droplets gracing a spider web. The film of dew that has settled on the threads is unstable and breaks up spontaneously into droplets. This phenomenon has implications for the treatment of textile fibers (the process known as "oiling"), glass, and carbon. It is no less important when applying mascara! I take my morning shower. The moment I step out, I dry off by way of evaporation (which makes me feel cold) and by dewetting (the process by which dry areas form spontaneously and expand on my skin). As I rush into my car under a pelting rain, my attention is caught by small drops stuck on my windshield. I also notice larger drops rolling down and others larger still that, like snails, leave behind them a trail of water. I ask myself what the difference is between these rolling drops and grains of sand tumbling down an incline. I wonder why the smallest drops remain stuck. The answers to such questions do help car manufacturers treat the surface o...

  17. Leidenfrost drops cooling surfaces: theory and interferometric measurement

    NARCIS (Netherlands)

    Van Limbeek, Michiel A. J.; Klein Schaarsberg, Martin H.; Sobac, Benjamin; Rednikov, Alexey; Sun, Chao; Colinet, Pierre; Lohse, Detlef


    When a liquid drop is placed on a highly superheated surface, it can be levitated by its own vapour. This remarkable phenomenon is referred to as the Leidenfrost effect. The thermally insulating vapour film results in a severe reduction of the heat transfer rate compared to experiments at lower

  18. La Gotita de Agua (The Little Drop of Water). (United States)

    Palandra, Maria; Puigdollers, Carmen

    This Spanish reader for children in kindergarten and first grade is about a drop of water that comes to life in a trip through the water cycle of evaporation, condensation, and subsequent return to a drier part of the earth's surface environment. The story is suitable for reading aloud or independent reading. The text is entirely in Spanish.…

  19. Playing with Water Drops: From Wetting to Optics through Electrostatics (United States)

    Domps, A.; Roques-Carmes, T.


    We present a consistent series of activities, including experiments and basic computational studies, investigating the shape and optical properties of water drops in connection with novel technological devices. Most of the work can be carried out with simple teaching equipment and is well suited to undergraduate students. Firstly, we show how the…

  20. Mathematics Anxiety and the Affective Drop in Performance (United States)

    Ashcraft, Mark H.; Moore, Alex M.


    The authors provide a brief review of the history and assessment of math anxiety, its relationship to personal and educational consequences, and its important impact on measures of performance. Overall, math anxiety causes an "affective drop," a decline in performance when math is performed under timed, high-stakes conditions, both in laboratory…

  1. Water drop impact onto oil covered solid surfaces (United States)

    Chen, Ningli; Chen, Huanchen; Amirfazli, Alidad


    Droplet impact onto an oily surface can be encountered routinely in industrial applications; e.g., in spray cooling. It is not clear from literature what impact an oil film may have on the impact process. In this work, water drop impact onto both hydrophobic (glass) and hydrophilic (OTS) substrates which were covered by oil films (silicone) of different thickness (5um-50um) and viscosity (5cst-100cst) were performed. The effects of drop impact velocity, film thickness, and viscosity of the oil film and wettability of the substrate were studied. Our results show that when the film viscosity and impact velocity is low, the water drop deformed into the usual disk shape after impact, and rebounded from the surface. Such rebound phenomena disappears, when the viscosity of oil becomes very large. With the increase of the impact velocity, crown and splashing appears in the spreading phase. The crown and splashing behavior appears more easily with the increase of film thickness and decrease of its viscosity. It was also found that the substrate wettability can only affect the impact process in cases which drop has a large Webber number (We = 594), and the film's viscosity and thickness are small. This work was support by National Natural Science Foundation of China and the Project Number is 51506084.

  2. The evaporation of the charged and uncharged water drops ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    assumed to be the temperature of adiabatic satura- tion. Their analysis also suffered from inaccuracies in determining the values of water vapour diffu- sivity and terminal ..... its evaporation. This heat-mass transfer process causes a temperature difference between the drop and its environment. The time required for a venti-.

  3. School drop out in Bangladesh: Insights using panel data (United States)

    Sabates, R.; Hossain, A.; Lewin, K.M.


    This paper examines the relative strength of different factors associated with school drop out using data collected between 2007 and 2009 in Bangladesh. A sample of 9046 children, aged 4-15, was selected across six districts for a household survey focusing on children's school access and experiences. Two groups of children were identified: those…

  4. Drop Impact upon Micro- and Nanostructured Superhydrophobic Surfaces

    NARCIS (Netherlands)

    Tsai, Peichun Amy; Pacheco Benito, Sergio; Pirat, C.; Lefferts, Leonardus; Lohse, Detlef


    We experimentally investigate drop impact dynamics onto different superhydrophobic surfaces, consisting of regular polymeric micropatterns and rough carbon nanofibers, with similar static contact angles. The main control parameters are the Weber number We and the roughness of the surface. At small

  5. The evaporation of the charged and uncharged water drops ...

    Indian Academy of Sciences (India)

    A laboratory experiment has been performed to study the effect of ventilation on the rate of evaporation of the millimeter sized charged and uncharged water drops suspended in a vertical wind tunnel. The linear relationship, = 0.907 + 0.282 , observed between the mean ventilation coefficient, , and a ...

  6. Hydrocarbon Degradation In Poultry Droppings And Cassava Peels ...

    African Journals Online (AJOL)

    This greenhouse study was aimed at determining the potentials of poultry droppings (PD) and cassava peels (CP) for nutrient-enhanced biodegradation of petroleum hydrocarbon (THC) in a well drained Typic Paleustults using the THC levels and degradation duration as remediation indices. The performance of the organic ...

  7. Vapor condensation onto a non-volatile liquid drop (United States)

    Inci, Levent; Bowles, Richard K.


    Molecular dynamics simulations of miscible and partially miscible binary Lennard-Jones mixtures are used to study the dynamics and thermodynamics of vapor condensation onto a non-volatile liquid drop in the canonical ensemble. When the system volume is large, the driving force for condensation is low and only a submonolayer of the solvent is adsorbed onto the liquid drop. A small degree of mixing of the solvent phase into the core of the particles occurs for the miscible system. At smaller volumes, complete film formation is observed and the dynamics of film growth are dominated by cluster-cluster coalescence. Mixing into the core of the droplet is also observed for partially miscible systems below an onset volume suggesting the presence of a solubility transition. We also develop a non-volatile liquid drop model, based on the capillarity approximations, that exhibits a solubility transition between small and large drops for partially miscible mixtures and has a hysteresis loop similar to the one observed in the deliquescence of small soluble salt particles. The properties of the model are compared to our simulation results and the model is used to study the formulation of classical nucleation theory for systems with low free energy barriers.

  8. Vapor condensation onto a non-volatile liquid drop

    Energy Technology Data Exchange (ETDEWEB)

    Inci, Levent; Bowles, Richard K., E-mail: [Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5C9 (Canada)


    Molecular dynamics simulations of miscible and partially miscible binary Lennard–Jones mixtures are used to study the dynamics and thermodynamics of vapor condensation onto a non-volatile liquid drop in the canonical ensemble. When the system volume is large, the driving force for condensation is low and only a submonolayer of the solvent is adsorbed onto the liquid drop. A small degree of mixing of the solvent phase into the core of the particles occurs for the miscible system. At smaller volumes, complete film formation is observed and the dynamics of film growth are dominated by cluster-cluster coalescence. Mixing into the core of the droplet is also observed for partially miscible systems below an onset volume suggesting the presence of a solubility transition. We also develop a non-volatile liquid drop model, based on the capillarity approximations, that exhibits a solubility transition between small and large drops for partially miscible mixtures and has a hysteresis loop similar to the one observed in the deliquescence of small soluble salt particles. The properties of the model are compared to our simulation results and the model is used to study the formulation of classical nucleation theory for systems with low free energy barriers.

  9. Millikan's Oil-Drop Experiment as a Remotely Controlled Laboratory (United States)

    Eckert, Bodo; Grober, Sebastian; Vetter, Martin; Jodl, Hans-Jorg


    The Millikan oil-drop experiment, to determine the elementary electrical charge e and the quantization of charge Q = n [middle dot] e, is an essential experiment in physics teaching but it is hardly performed in class for several reasons. Therefore, we offer this experiment as a remotely controlled laboratory (RCL). We describe the interactivity…

  10. Mesophilic Co-Digestion of Cattle Paunch with Poultry Droppings ...

    African Journals Online (AJOL)

    Cattle paunch and poultry droppings are wastes that have posed environmental hazards due to poor management and disposal strategies in most municipal abattoirs and livestock farms in Nigeria. Utilization of these wastes for energy production at small and/or large scale requires assessment to ascertain the optimal mix.

  11. Effects of fertilizer phosphorus and poultry droppings treatments on ...

    African Journals Online (AJOL)

    Abstract. The effect of five phosphrous levels (0, 25, 50, 75, 100 and 125 kg/ha) and five poultry dropping (0, 100, 200, 300, 400 and 500 kg/ha) levels on the growth, growth yield, yield components, nutrients concentration and food values of pepper (Capsicum annuum L) were observed from 2002 to 2003 raining seasons.

  12. Don’t drop the patient: teamwork for cataract surgery

    Directory of Open Access Journals (Sweden)

    Daksha Patel


    Full Text Available The purpose of a team is to work together towards a common goal. On an athletics track, relay race teams run with a baton that is passed from one team member to another, without breaking the pace. If the baton is dropped, the team is disqualified.

  13. Effect of drop jump technique on the reactive strength index

    Directory of Open Access Journals (Sweden)

    Struzik Artur


    Full Text Available The basic drill of plyometric training aimed at improving lower limb power and jump height is a drop jump. This exercise can be performed using different techniques, which substantially affects jump variables. Therefore, the aim of this study was to compare the values of the reactive strength index (RSI for countermovement drop jumps (CDJs and bounce drop jumps (BDJs. The study was carried out in a group of 8 male youth basketball players. The tests were conducted using the AMTI BP600900 force plate to measure ground reaction forces and the Noraxon MyoMotion system to record kinematic data. Each player performed two CDJs and two BDJs from the height of 15, 30, 45 and 60 cm. The RSI was calculated as a ratio of jump height and contact time. Moreover, the RSI was determined for the amortization and take-off phases separately. Significant differences (p < 0.05 between RSI values for CDJs and BDJs were recorded for jumps from 30, 45 and 60 cm. Differences in RSI values for jumps from 15 cm were not significant. Furthermore, CDJ height values were significantly higher (p < 0.05 than the values recorded for BDJs. Times of contact, amortization and take-off during BDJs were significantly shorter (p < 0.05 than the respective values obtained for CDJs. Therefore, the use of the RSI to monitor plyometric training should be based on the drop jump technique that is commonly performed by basketball players.

  14. Drop Jumping as a Training Method for Jumping Ability

    NARCIS (Netherlands)

    Bobbert, Maarten F.


    Vertical jumping ability is of importance for good performance in sports such as basketball and volleyball. Coaches are in need of exercises that consume only little time and still help to improve their players’ jumping ability, without involving a high risk of injury. Drop jumping is assumed to

  15. A Novel Virus Causes Scale Drop Disease in Lates calcarifer

    NARCIS (Netherlands)

    Groof, A.; Guelen, L.; Deijs, M.; Wal, van der Y.; Miyata, M.; Ng, K.S.; Grinsven, van L.; Simmelink, B.; Biermann, Y.; Grisez, L.; Lent, van J.W.M.; Ronde, de A.; Chang, S.F.; Schrier, C.; Hoek, L.


    From 1992 onwards, outbreaks of a previously unknown illness have been reported in Asian seabass (Lates calcarifer) kept in maricultures in Southeast Asia. The most striking symptom of this emerging disease is the loss of scales. It was referred to as scale drop syndrome, but the etiology remained

  16. Detection of bubble nucleation event in superheated drop detector ...

    Indian Academy of Sciences (India)

    The present work demonstrates the detection of bubble nucleation events by using the pressure sensor. The associated circuits for the measurement are described in this article. The detection of events is verified by measuring the events with the acoustic sensor. The measurement was done using drops of various sizes to ...

  17. Determination of pressure drop across activated carbon fiber respirator cartridges. (United States)

    Balanay, Jo Anne G; Lungu, Claudiu T


    Activated carbon fiber (ACF) is considered as an alternative adsorbent to granular activated carbon (GAC) for the development of thinner, lighter, and efficient respirators because of their larger surface area and adsorption capacities, thinner critical bed depth, lighter weight, and fabric form. This study aims to measure the pressure drop across different types of commercially available ACFs in respirator cartridges to determine the ACF composition and density that will result in acceptably breathable respirators. Seven ACF types in cloth (ACFC) and felt (ACFF) forms were tested. ACFs in cartridges were challenged with pre-conditioned constant air flow (43 LPM, 23°C, 50% RH) at different compositions (single- or combination-ACF type) in a test chamber. Pressure drop across ACF cartridges were obtained using a micromanometer, and compared among different cartridge configurations, to those of the GAC cartridge, and to the NIOSH breathing resistance requirements for respirator cartridges. Single-ACF type cartridges filled with any ACFF had pressure drop measurements (23.71-39.93 mmH2O) within the NIOSH inhalation resistance requirement of 40 mmH2O, while those of the ACFC cartridges (85.47±3.67 mmH2O) exceeded twice the limit due possibly to the denser weaving of ACFC fibers. All single ACFF-type cartridges had higher pressure drop compared to the GAC cartridge (23.13±1.14 mmH2O). Certain ACF combinations (2 ACFF or ACFC/ACFF types) resulted to pressure drop (26.39-32.81 mmH2O) below the NIOSH limit. All single-ACFF type and all combination-ACF type cartridges with acceptable pressure drop had much lower adsorbent weights than GAC (≤15.2% of GAC weight), showing potential for light-weight respirator cartridges. 100% ACFC in cartridges may result to respirators with high breathing resistance and, thus, is not recommended. The more dense ACFF and ACFC types may still be possibly used in respirators by combining them with less dense ACFF materials and/or by

  18. Xylazine Hydrochloride (Rompun and the new retractable-barbed dart ("drop-out" dart for the capture of some nervous and aggressive antelope species

    Directory of Open Access Journals (Sweden)

    G.L. Smuts


    Full Text Available he successful capture and restraint of gemsbok, eland and kudu using the potent sedative, Xylazine hydrochloride (Rompun, Bayer and the new retractable-barbed dart ("drop-out" dart is described. These species were rapidly immobilized and rendered 100 per cent tractable by Etorphine/Rompun or Fentanyl/Rompun drug combinations. The drop-out dart proved to be invaluable for the capture of timid species as flight distances were greatly reduced and the chances of capture myopathy (overstraining disease subsequently obviated.

  19. Ultra-sensitive determination of cadmium in rice and water by UV-vis spectrophotometry after single drop microextraction. (United States)

    Wen, Xiaodong; Deng, Qingwen; Guo, Jie; Yang, Shengchun


    In this work, a new method based on single drop microextraction (SDME) preconcentration using tetrachloromethane (CCl(4)) as extraction solvent was proposed for the spectrophotometric determination of cadmium in rice and water samples. The influence factors relevant to SDME, such as type and volume of extractant, stirring rate and time, dithizone concentration, pH, drop volume and instrumental conditions were studied systematically. Under the optimal conditions, the limit of detection (LOD) was 0.5 ng L(-1), with sensitivity enhancement factor (EF) of 128. The different maximum absorption wavelength caused by the different extraction acidity compared with some conventional works and the enhancement effect of acetone (dilution solvent) for the spectrophotometric determination were the two key factors of the high EF and sensitivity. The proposed method was applied to the determination of rice and water samples with satisfactory analytical results. The proposed method was simple, rapid, cost-efficient and sensitive. Copyright © 2011 Elsevier B.V. All rights reserved.

  20. Inhibition of Condensation Frosting by Arrays of Hygroscopic Antifreeze Drops. (United States)

    Sun, Xiaoda; Damle, Viraj G; Uppal, Aastha; Linder, Rubin; Chandrashekar, Sriram; Mohan, Ajay R; Rykaczewski, Konrad


    The formation of frost and ice can have negative impacts on travel and a variety of industrial processes and is typically addressed by dispensing antifreeze substances such as salts and glycols. Despite the popularity of this anti-icing approach, some of the intricate underlying physical mechanisms are just being unraveled. For example, recent studies have shown that in addition to suppressing ice formation within its own volume, an individual salt saturated water microdroplet forms a region of inhibited condensation and condensation frosting (RIC) in its surrounding area. This occurs because salt saturated water, like most antifreeze substances, is hygroscopic and has water vapor pressure at its surface lower than water saturation pressure at the substrate. Here, we demonstrate that for macroscopic drops of propylene glycol and salt saturated water, the absolute RIC size can remain essentially unchanged for several hours. Utilizing this observation, we demonstrate that frost formation can be completely inhibited in-between microscopic and macroscopic arrays of propylene glycol and salt saturated water drops with spacing (S) smaller than twice the radius of the RIC (δ). Furthermore, by characterizing condensation frosting dynamics around various hygroscopic drop arrays, we demonstrate that they can delay complete frosting over of the samples 1.6 to 10 times longer than films of the liquids with equivalent volume. The significant delay in onset of ice nucleation achieved by dispensing propylene glycol in drops rather than in films is likely due to uniform dilution of the drops driven by thermocapillary flow. This transport mode is absent in the films, leading to faster dilution, and with that facilitated homogeneous nucleation, near the liquid-air interface.

  1. Efficacy and safety of azithromycin 1.5% eye drops in paediatric population with purulent bacterial conjunctivitis. (United States)

    Bremond-Gignac, Dominique; Nezzar, Hachemi; Bianchi, Paolo Emilio; Messaoud, Riadh; Lazreg, Sihem; Voinea, Liliana; Speeg-Schatz, Claude; Hartani, Dahbia; Kaercher, Thomas; Kocyla-Karczmarewicz, Beata; Murta, Joaquim; Delval, Laurent; Renault, Didier; Chiambaretta, Frédéric


    To determine the efficacy and safety of azithromycin 1.5% eye drops in a paediatric population with purulent bacterial conjunctivitis. This was a multicentre, international, randomised, investigator-masked study in 286 children with purulent discharge and bulbar conjunctival injection. Patients received either azithromycin 1.5% eye drops (twice daily for 3 days) or tobramycin 0.3% eye drops (every 2 h for 2 days, then four times daily for 5 days). Clinical signs were evaluated on day (D) 0, 3 and 7, and cultures on D0 and D7. The primary variable was the clinical cure (absence of bulbar conjunctival injection and discharge) on D3 in the worse eye for patients with positive cultures on D0. 286 patients (mean age 3.2 years; range 1 day-17 years) were included; 203 had positive cultures on D0. Azithromycin was superior to tobramycin in clinical cure rate on D3 (47.1% vs 28.7%, p=0.013) and was non-inferior to tobramycin on D7 (89.2% vs 78.2%, respectively). Azithromycin treatment eradicated causative pathogens, including resistant species, with a similar resolution rate to tobramycin (89.8% vs 87.2%, respectively). These results were confirmed in a subgroup of patients younger than 24 months old. Azithromycin 1.5% eye drops provided a more rapid clinical cure than tobramycin 0.3% eye drops in the treatment of purulent bacterial conjunctivitis in children, with a more convenient twice-a-day dosing regimen. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to

  2. Synaptic Plasticity and Translation Initiation (United States)

    Klann, Eric; Antion, Marcia D.; Banko, Jessica L.; Hou, Lingfei


    It is widely accepted that protein synthesis, including local protein synthesis at synapses, is required for several forms of synaptic plasticity. Local protein synthesis enables synapses to control synaptic strength independent of the cell body via rapid protein production from pre-existing mRNA. Therefore, regulation of translation initiation is…

  3. Design of a reconfigurable optical add/drop multiplexer based on tunable Fabry-Perot array (United States)

    Ye, Jiansen; Wang, Xin; Li, Zhuo; Yang, Yang; Xu, Rui; Shi, Rui


    With the development of optical fiber communication, dense wavelength division multiplexing (DWDM) system is important for the rapid management of multi-wavelength in the core node of the optical transmission network. In this paper, a reconfigurable optical add-drop multiplexer (ROADM) based on the tunable Fabry-Perot (F-P) array is proposed. An optical switch with high isolation and low crosstalk is designed by using the characteristics of filtering and tuning for the F-P array. The principle, structure, and function of the tunable F-P array are introduced. The characteristics of filtering and tuning for the F-P filter are also calculated, and the factor for the isolation, crosstalk, response time and insertion loss are analyzed. A single physical channel ROADM with 16 signal channels, which operates in C-band, is designed and optimized by simulation.

  4. Micro-bubble morphologies following drop impacts onto a pool surface

    KAUST Repository

    Thoroddsen, Sigurdur T.


    When a drop impacts at low velocity onto a pool surface, a hemispheric air layer cushions and can delay direct contact. Herein we use ultra-high-speed video to study the rupture of this layer, to explain the resulting variety of observed distribution of bubbles. The size and distribution of micro-bubbles is determined by the number and location of the primary punctures. Isolated holes lead to the formation of bubble necklaces when the edges of two growing holes meet, whereas bubble nets are produced by regular shedding of micro-bubbles from a sawtooth edge instability. For the most viscous liquids the air film contracts more rapidly than the capillary-viscous velocity through repeated spontaneous ruptures of the edge. From the speed of hole opening and the total volume of micro-bubbles we conclude that the air sheet ruptures when its thickness approaches ?100.

  5. Single-drop microextraction followed by in-drop derivatization for the analysis of organic compounds by gas chromatography

    Directory of Open Access Journals (Sweden)

    Constantine Stalikas


    Full Text Available Microextraction has become a buzz word in the recent years in the scientific area of analytical chemistry. Over the last decade, newer miniaturised approaches to liquid extraction have emerged, resulting in solvent and sample savings and less time consuming analysis. Single-drop microextraction (SDME has been developed as a viable and easy-to-use method based on the partitioning between sample matrix and organic droplet phase. However, there are numerous examples where analytical derivatizations are required to enhance sensitivity, selectivity, extraction efficiency and overall quality of the data. Improvements resulting from derivatization in instrumental methods are well known. The absence of data in chemical reaction accompanied by mass-transfer in liquid-liquid and gas-liquid microextraction, calls for a meticulous treatment of SDME in-drop derivatization for the purpose of analytical implementation. Leveraging the inherent characteristics of an organic microdrop as a tiny reactor, a threefold aim is set out in order: Ι. to develop a theoretical approximation to the in-drop derivatization SDME using phenolic compounds for liquid-liquid and two aldehydes for gas-liquid, as model compounds, II. to gauge the significance of mass-transfer and chemical reaction in an organic drop viewed as an analytical reactor and III. to underscore the importance of the a priori knowledge of the characteristics of such a system related to its analytical aspects.

  6. Expression responses of five cold tolerant related genes to two temperature dropping treatments in sea cucumber Apostichopus japonicus (United States)

    Li, Chengze; Chang, Yaqing; Pang, Zhenguo; Ding, Jun; Ji, Nanjing


    Environmental conditions, including ambient temperature, play important roles in survival, growth development, and reproduction of the Japanese sea cucumber, Apostichopus japonicus. Low temperatures result in slowed growth and skin ulceration disease. In a previous study, we investigated the effect of low temperature on gene expression profiles in A. japonicus by suppression subtractive hybridization (SSH). Genes encoding Ferritin, Lysozyme, Hsp70, gp96, and AjToll were selected from a subtracted cDNA library of A. japonicus under acute cold stress. The transcriptional expression profiles of these genes were investigated in different tissues (coelomocyte, respiratory tree, intestine, longitudinal muscle) after exposure to acute and mild temperature dropping treatments. The results show that (1) the five cold-tolerance-related genes were found in all four tissues and the highest mRNA levels were observed in coelomocyte and respiratory tree; (2) under the temperature dropping treatments, three types of transcriptional regulation patterns were observed: primary suppression followed by up-regulation at -2°C, suppressed expression throughout the two treatments, and more rarely an initial stimulation followed by suppression; and (3) gene expression suppression was more severe under acute temperature dropping than under mild temperature dropping treatment. The five cold-tolerance-related genes that were distributed mainly in coelomocyte and respiratory tissues were generally down-regulated by low temperature stress but an inverse up-regulation event was found at the extreme temperature (-2°C).

  7. Developmental evolution facilitates rapid adaptation. (United States)

    Lin, Hui; Kazlauskas, Romas J; Travisano, Michael


    Developmental evolution has frequently been identified as a mode for rapid adaptation, but direct observations of the selective benefits and associated mechanisms of developmental evolution are necessarily challenging to obtain. Here we show rapid evolution of greatly increased rates of dispersal by developmental changes when populations experience stringent selection. Replicate populations of the filamentous fungus Trichoderma citrinoviride underwent 85 serial transfers, under conditions initially favoring growth but not dispersal. T. citrinoviride populations shifted away from multicellular growth toward increased dispersal by producing one thousand times more single-celled asexual conidial spores, three times sooner than the ancestral genotype. Conidia of selected lines also germinated fifty percent faster. Gene expression changed substantially between the ancestral and selected fungi, especially for spore production and growth, demonstrating rapid evolution of tight regulatory control for down-regulation of growth and up-regulation of conidia production between 18 and 24 hours of growth. These changes involved both developmentally fixed and plastic changes in gene expression, showing that complex developmental changes can serve as a mechanism for rapid adaptation.

  8. Portable Diagnostics and Rapid Germination

    Energy Technology Data Exchange (ETDEWEB)

    Dunn, Zachary Spencer [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)


    In the Bioenergy and Defense Department of Sandia National Laboratories, characterization of the BaDx (Bacillus anthracis diagnostic cartridge) was performed and rapid germination chemistry was investigated. BaDx was tested with complex sample matrixes inoculated with Bacillus anthracis, and the trials proved that BaDx will detect Bacillus anthracis in a variety of the medium, such as dirt, serum, blood, milk, and horse fluids. The dimensions of the device were altered to accommodate an E. coli or Listeria lateral flow immunoassay, and using a laser printer, BaDx devices were manufactured to identify E. coli and Listeria. Initial testing with E. coli versions of BaDx indicate that the device will be viable as a portable diagnostic cartridge. The device would be more effective with faster bacteria germination; hence studies were performed the use of rapid germination chemistry. Trials with calcium dipicolinic acid displayed increased cell germination, as shown by control studies using a microplate reader. Upon lyophilization the rapid germination chemistry failed to change growth patterns, indicating that the calcium dipicolinic acid was not solubilized under the conditions tested. Although incompatible with the portable diagnostic device, the experiments proved that the rapid germination chemistry was effective in increasing cell germination.

  9. Therapeutic Effect of 0.1% Tacrolimus Eye Drops in the Tarsal Form of Vernal Keratoconjunctivitis. (United States)

    Wan, Qi; Tang, Jing; Han, Yu; Wang, Dan; Ye, Hongquan


    The purpose of this study was to evaluate the efficacy and safety of 0.1% tacrolimus eye drops in the tarsal form of vernal keratoconjunctivitis (VKC) and to survey the changes of dendritic cells at the palpebral conjunctiva in patients with VKC by in vivo confocal microscopy. A total of 17 patients (34 eyes) with the tarsal form of VKC were enrolled in this prospective, nonrandomized case series. They were treated with 0.1% tacrolimus eye drops twice daily after discontinuation of all other topical medications. Subjective ocular symptoms and objective ocular signs were scored on a 4-point scale by one ophthalmologist and the characteristics of the dendritic cells in each right eye at the palpebral conjunctiva were evaluated by in vivo confocal microscopy before treatment and at the 1st, 2th, 4th, and 8th weeks after treatment. After 1 week of treatment with 0.1% tacrolimus eye drops, the score for each symptom in all patients showed a significant (p < 0.001) improvement, and 13 patients (76%) experienced dramatic relief of symptoms. In addition, there was a significantly (p < 0.001) decreased clinical sign score (except for giant papillae) after 4 weeks, and a significant (p < 0.001) improvement in the score of giant papillae after 8 weeks of treatment. The characteristics of dendritic cells (including cell count, total area, average size, perimeter, and diameter) showed a significant (p < 0.05) decrease after 2 weeks of treatment. During the follow-up, no other topical medications were required and no significant changes in visual acuity were documented. No cataracts or elevation of intraocular pressures were detected. Only 5 patients (29%) had a tingling or burning sensation or discomfort. Tacrolimus 0.1% eye drops are an effective and safe treatment for the tarsal form of VKC, and can rapidly inhibit the activity of dendritic cells, improve symptoms, reduce papillary hyperplasia, and reverse damage at the palpebral conjunctiva. The side effects could affect the

  10. Openness initiative

    Energy Technology Data Exchange (ETDEWEB)

    Duncan, S.S. [Los Alamos National Lab., NM (United States)


    Although antinuclear campaigns seem to be effective, public communication and education efforts on low-level radioactive waste have mixed results. Attempts at public information programs on low-level radioactive waste still focus on influencing public opinion. A question then is: {open_quotes}Is it preferable to have a program focus on public education that will empower individuals to make informed decisions rather than trying to influence them in their decisions?{close_quotes} To address this question, a case study with both quantitative and qualitative data will be used. The Ohio Low-Level Radioactive Waste Education Program has a goal to provide people with information they want/need to make their own decisions. The program initiated its efforts by conducting a statewide survey to determine information needed by people and where they turned for that information. This presentation reports data from the survey and then explores the program development process in which programs were designed and presented using the information. Pre and post data from the programs reveal attitude and knowledge shifts.

  11. Four-point potential drop measurements for materials characterization (United States)

    Bowler, Nicola


    The technique of measuring the voltage difference (potential drop) between two of the four electrodes of a four-point probe, in order to determine conductivity or surface resistivity of a test piece, is well established in the direct-current (dc) or quasi-dc regime. The technique finds wide usage in the semiconductor industry for the purpose of measuring surface resistivity of semiconductors, and also in the measurement of conductivity of metals, particularly of ferromagnetic metals for which conductivity cannot be easily measured using eddy-current nondestructive evaluation (NDE). In these applications, the conductivity of the test piece is deduced from an analytic formula that depends on the geometry of the probe and test piece. Such a formula requires, as an input, the measured value of the potential drop. Several analytical expressions exist for a variety of test-piece geometries and probe arrangements. Recently, it has been shown that broadband measurements of the potential drop, known as 'alternating current potential drop' (ac PD) measurements, can be used not only to obtain the conductivity of a test piece, but also its linear permeability μ. The beauty of this measurement is that the two parameters are completely decoupled in the quasi-static regime. In fact, μ does not appear in the quasi-static expression for σ. Hence, σ may be obtained from low-frequency ac PD measurements and then μ may be deduced as the frequency increases beyond the quasi-static regime, once σ is known. In this review, both dc and ac solutions that are useful in determining the conductivity of metals and semiconductors, and the permeability of ferromagnetic conductors, are summarized. In particular, flat test pieces with arbitrary thickness are considered. At the next level of complexity, a solution for a half-space coated with a surface layer is given, along with a discussion of the use of the four-point potential drop method for determining thickness of a surface layer, such

  12. Antioxidant and inflammatory cytokine in tears of patients with dry eye syndrome treated with preservative-free versus preserved eye drops. (United States)

    Jee, Donghyun; Park, Sang Hee; Kim, Man Soo; Kim, Eun Chul


    To compare the antioxidant and inflammatory cytokine activities in tears of patients with dry eye syndrome treated with preservative-free versus preserved eye drops. A total of 100 patients with moderate to severe dry eye syndrome were randomly divided into two groups. Fifty patients (group 1) were treated four times with preservative-free 0.1% sodium hyaluronate and 0.1% fluorometholone eye drops in the first month and with preservative-free 0.1% sodium hyaluronate and 0.05% cyclosporine eye drops in the second and third months. Another 50 patients (group 2) were treated with preserved eye drops on the same schedule. Ocular Surface Disease Index, corneal fluorescein staining, Schirmer I test, tear film breakup time, impression cytology, and antioxidant and inflammatory cytokine activities in tears were evaluated. Treatment with preservative-free eye drops led to significant improvements in symptoms, tear film breakup time, Schirmer I score, and impression cytologic findings compared to treatment with preserved eye drops (P tears in the preservative-free group at 1, 2, and 3 months compared to initial values, respectively (P ocular inflammation and in increasing antioxidant contents in tears of patients with dry eye syndrome. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

  13. Microwave-assisted headspace single-drop microextration of chlorobenzenes from water samples

    Energy Technology Data Exchange (ETDEWEB)

    Vidal, Lorena [Departamento de Quimica Analitica, Nutricion y Bromatologia, Universidad de Alicante, P.O. Box 99, E-03080 Alicante (Spain); Domini, Claudia E. [Departamento de Quimica Analitica, Nutricion y Bromatologia, Universidad de Alicante, P.O. Box 99, E-03080 Alicante (Spain); Grane, Nuria [Departamento de Quimica Analitica, Nutricion y Bromatologia, Universidad de Alicante, P.O. Box 99, E-03080 Alicante (Spain); Psillakis, Elefteria [Department of Environmental Engineering, Technical University of Crete, Polytechneioupolis, GR-73100 Chania, Crete (Greece); Canals, Antonio [Departamento de Quimica Analitica, Nutricion y Bromatologia, Universidad de Alicante, P.O. Box 99, E-03080 Alicante (Spain)]. E-mail:


    A one-step and in-situ sample preparation method used for quantifying chlorobenzene compounds in water samples has been developed, coupling microwave and headspace single-drop microextraction (MW-HS-SDME). The chlorobenzenes in water samples were extracted directly onto an ionic liquid single-drop in headspace mode under the aid of microwave radiation. For optimization, a Plackett-Burman screening design was initially used, followed by a mixed-level factorial design. The factors considered were: drop volume, aqueous sample volume, stirring speed, ionic strength, extraction time, ionic liquid type, microwave power and length of the Y-shaped glass-tube. The optimum experimental conditions found from this statistical evaluation were: a 5 {mu}L microdrop of 1-hexyl-3-methylimidazolium hexafluorophosphate exposed for 20 min to the headspace of a 30 mL aqueous sample, irradiated by microwaves at 200 W and placed in a 50 mL spherical flask connected to a 25 cm Y-shaped glass-tube. Under the optimised experimental conditions, the response of a high performance liquid chromatographic system was found to be linear over the range studied and with correlation coefficients ranging between 0.9995 and 0.9999. The method showed a good level of repeatability, with relative standard deviations varying between 2.3 and 8.3% (n = 5). Detection limits were found in the low {mu}g L{sup -1} range varying between 0.016 and 0.039 {mu}g L{sup -1}. Overall, the performance of the proposed method demonstrated the favourable effect of microwave sample irradiation upon HS-SDME. Finally, recovery studies from different types of environmental water samples revealed that matrix had little effect upon extraction.

  14. Fluorimetric quantification of brimonidine tartrate in eye drops. (United States)

    Sunitha, G; Bhagirath, R; Alapati, V R; Ramakrishna, K; Subrahmanyam, C V S; Anumolu, P D


    A simple and sensitive spectrofluorimetric method has been developed for the estimation of brimonidine tartrate in pure and eye drops. Linearity was obeyed in the range of 0.2-3.0 ΅g/ml in dimethyl formamide as solvent at an emission wavelength (λem) of 530 nm after excitation wavelength (λex) of 389 nm with good correlation coefficient of 0.998. The limit of detection and limit of quantification for this method were 22.0 and 72.0 ng/ml, respectively. The developed method was statistically validated as per International Conference on Harmonisation guidelines. The percentage relative standard deviation values were found to be less than 2 for accuracy and precision studies. The results obtained were in good agreement with the labelled amounts of the marketed formulations. The proposed method was effectively applied to routine quality control analysis of brimonidine tartrate in their eye drops.

  15. Dynamics of sessile drops. Part 3. Theory of forced oscillations

    CERN Document Server

    Bostwick, Joshua B


    A partially-wetting sessile drop is driven by a sinusoidal pressure field that produces capillary waves on the liquid/gas interface. The analysis presented in Part 1 of this series (Bostwick & Steen 2014) is extended by computing response diagrams and phase shifts for the viscous droplet, whose three phase contact-line moves with contact-angle that is a smooth function of the contact line speed. Viscous dissipation is incorporated through the viscous potential flow approximation and the critical Ohnesorge number bounding regions beyond which a given mode becomes over-damped is computed. Davis dissipation originating from the contact-line speed condition leads to damped oscillations for drops with finite contact-line mobility, even for inviscid fluids. The critical mobility and associated driving frequency to generate the largest Davis dissipation is computed. Lastly, regions of modal coexistence where two modes can be simultaneously excited by a single forcing frequency are identified. Predictions compare...

  16. Development of Active Learning Curriculum for CASPER's Microgravity Drop Tower (United States)

    Carmona-Reyes, Jorge; Wang, Li; York, Judy; Matthews, Lorin; Laufer, Rene; Cook, Mike; Schmoke, Jimmy; Hyde, Truell


    As CASPER's new drop tower comes on line, plans for correlated educational research curricula are underway. CASPER's educational research team is working on developing curricula specific to the CASPER drop tower, modeled on a contest currently in use by (BEST) Robotics Inc. within central Texas independent school districts. The curricula integrates age specific use of computer programming software packages such as ``Scratch'' with industry standard communication protocols and augmented reality applications. Content is constructed around an earth and space science framework, covering subjects such as stars and galaxies, matter and energy, fusion and fission at a middle school level. CASPER faculty are partnering with the Region 12 Service Center; this combination provides a wide range of expertise that includes professional development, pedagogical methods, computational thinking in addition to microgravity and space science research expertise. The details of this work will be presented and samples of the manner in which it is impacting the CASPER research and educational outreach partnership will be discussed.

  17. Influence of gravity on the solidification of a drop

    Energy Technology Data Exchange (ETDEWEB)

    Sanz, A.; Meseguer, J.; Mayo, L.


    In this paper the influence of gravity on the solidification of a drop formed at the end of a rod is analyzed. Although similar studies (but ignoring gravity effects) already exist, a theoretical analysis including gravity effects allows one to improve the experimental procedure to measure on Earth relevant properties of crystals (mainly the receding contact angle phi/sub i/) which are of importance in shaped crystal growth processes. One of the main results here obtained are the shapes of the solidified drops, which are strongly dependent on the value of phi/sub i/. Therefore, fitting theoretical shapes to experimental ones is a way to perform accurate measurements of phi/sub i/.

  18. Virtual prototyping of drop test using explicit analysis (United States)

    Todorov, Georgi; Kamberov, Konstantin


    Increased requirements for reliability and safety, included in contemporary standards and norms, has high impact over new product development. New numerical techniques based on virtual prototyping technology, facilitates imrpoving product development cycle, resutling in reduced time/money spent for this stage as well as increased knowledge about certain failure mechanism. So called "drop test" became nearly a "must" step in development of any human operated product. This study aims to demonstrate dynamic behaviour assessment of a structure under impact loads, based on virtual prototyping using a typical nonlinear analysis - explicit dynamics. An example is presneted, based on a plastic container that is used as cartridge for a dispenser machine exposed to various work conditions. Different drop orientations were analyzed and critical load cases and design weaknesses have been found. Several design modifications have been proposed, based on detailed analyses results review.

  19. Surgical outcome for foot drop in lumbar degenerative disease. (United States)

    Bhargava, Deepti; Sinha, Priyank; Odak, Saurabh; Tyagi, Atul; Towns, Gerry; Pal, Debasish


    Controversy exists regarding the timing and outcome of surgery for lumbar degenerative disease (LDD) associated with foot drop. In this work, we report the results of a retrospective observational study from our center. We had a sample size of 26 patients with a minimum follow-up of 6 months. Of the 26 patients, 88% improved, with complete recovery observed in 61%. Thus, our data support the view that there is good recovery from operative management of foot drop secondary to LDD. Adjusting for preoperative strength, preoperative duration of weakness was a significant predictor of extent of recovery (odds ratio = 0.93; 95% confidence interval 0.88 to 0.98; p = 0.019). The model explained 50% of the variance in outcome in this study.

  20. Hanging drop cultures of human testis and testis cancer samples

    DEFF Research Database (Denmark)

    Jørgensen, Anne; Young, J; Nielsen, J E


    limited by the lack of experimental models. The aim of this study was to establish an experimental tissue culture model to maintain normal and malignant germ cells within their niche and allow investigation of treatment effects. METHODS: Human testis and testis cancer specimens from orchidectomies were...... cultured in 'hanging drops' and effects of activin A and follistatin treatment were investigated in seminoma cultures. RESULTS: Testis fragments with normal spermatogenesis or CIS cells were cultured for 14 days with sustained proliferation of germ cells and CIS cells and without increased apoptosis....... Seminoma cultures survived 7 days, with proliferating cells detectable during the first 5 days. Activin A treatment significantly reduced KIT transcript and protein levels in seminoma cultures, thereby demonstrating a specific treatment response. CONCLUSIONS: Hanging drop cultures of human testis...

  1. Assessment of the relative error in the automation task by sessile drop method

    Directory of Open Access Journals (Sweden)

    T. О. Levitskaya


    Full Text Available Assessment of the relative error in the sessile drop method automation. Further development of the sessile drop method is directly related to the development of new techniques and specially developed algorithms enabling automatic computer calculation of surface properties. The sessile drop method mathematical apparatus improvement, drop circuit equation transformation to a form suitable for working, the drop surface calculation method automation, analysis of relative errors in the calculation of surface tension are relevant and are important in experimental determinations. The surface tension measurement relative error, as well as the error caused by the drop ellipsoidness in the plan were determined in the task of the sessile drop automation. It should be noted that if the drop maximum diameter (l is big or if the ratio of l to the drop height above the equatorial diameter(h is big, the relative error in the measurement of surface tension by sessile drop method does not depend much on the equatorial diameter of the drop and ellipsoidness of the drop. In this case, the accuracy of determination of the surface tension varies from 1,0 to 0,5%. At lower values the drop ellipsoidness begins to affect the relative error of surface tension (from 1,2 to 0,8%, but in this case the drop ellipsoidness is less. Therefore, in subsequent experiments, we used larger drops. On the basis of the assessment of the relative error in determining the liquid surface tension by sessile drop method caused by drop ellipsoidness in the plan, the tables showing the limits of the drop parameters (h and l measurement necessary accuracy to get the overall relative error have been made up. Previously, the surface tension used to be calculated with the relative error in the range of 2-3%

  2. Fundamental Studies of Jumping-Drop Thermal Diodes (United States)


    injection and vacuum pumping (visible in Figure 2a inset). The opposing superhydrophilic surface (Figure 2b) consisted of copper wick sintered to a...sectional area as the diode (76 mm x 76 mm). The backside of the heater was wrapped with insulating rubber foam to minimize heat leakage. The cooling was...and heated, so there would be no jumping drops. Note that the heater plate and the insulating foam were removed from the images in Figure 4 (a) and

  3. How to Make a Microgravity Drop Tower for Your Classroom (United States)

    DeLombard, Richard; Hall, Nancy R.


    Microgravity is quite often seen as exotic and special as astronauts float around in the International Space Station, eating MM's in mid-air, and performing science experiments, all done seemingly without gravity being present. Surprisingly enough, up on the ISS there is about 90 of the same gravity that holds you to the floor in your classroom or museum exhibit hall. Participate in this session and you will understand that and more. You can use simple devices to demonstrate microgravity conditions in your classroom or museum exhibit hall. This will be the same microgravity condition that astronauts experience on the ISS, just for a much shorter period of time. Contrary to popular opinion of some people, microgravity is NOT caused by zero gravity up there. Microgravity on the ISS is due to free fall within the Earth's gravitational field. That means you can drop an item in free fall in your classroom and museum exhibit hall and that item will experience microgravity. In this session, a short theory segment will explain and reinforce these concepts so that you may explain to others. The session will concentrate on showing the session participants how to make an effective, but inexpensive, drop tower for use in the classroom. Such a drop tower may be used to reinforce classroom instruction in physics and forces motion as well as serve as a platform for student investigations, classroom competitions, and student science or technology fair entries. Session participants will build their own simple microgravity experiment and operate them in a drop tower, compare results, and modify their experiment based on results. This material is also useful for public demonstrations at school open houses, travelling museum exhibits, fixed museum exhibits, and independent student projects or experiments. These free fall concepts also connect terrestrial demonstrations with planetary moon motion, comet trajectory, and more.

  4. Topical dobesilate eye drops for ophthalmic primary pterygium. (United States)

    Cuevas, Pedro; Outeiriño, Luis A; Angulo, Javier; Giménez-Gallego, Guillermo


    Selective inhibition of fibroblast growth factor and vascular endothelial growth factor signalling pathways is effective in causing regression of pterygia. Prompt regression of fibrovascular mass and conjunctival angiogenesis was documented 2 weeks after topical administration of dobesilate eye drops twice daily. At 3-month follow-up, no recurrence was seen and no ocular irritation and burning were noted. The authors believe that this is the first known successful use of topical dobesilate in primary pterygium.

  5. Topical dobesilate eye drops for ophthalmic primary pterygium


    Cuevas, Pedro; Outeiriño, Luis A; Angulo, Javier; Giménez-Gallego, Guillermo


    Selective inhibition of fibroblast growth factor and vascular endothelial growth factor signalling pathways is effective in causing regression of pterygia. Prompt regression of fibrovascular mass and conjunctival angiogenesis was documented 2 weeks after topical administration of dobesilate eye drops twice daily. At 3-month follow-up, no recurrence was seen and no ocular irritation and burning were noted. The authors believe that this is the first known successful use of topical dobesilate in...

  6. Vertical Drop Test of a Transport Fuselage Section


    熊倉, 郁夫; KUMAKURA, Ikuo


    The NAL Structures and Materials Research Center conducted a vertical drop test of a fuselage section from a YS-11A transport airplane in December 2001. This test program is part of research into the structural crashworthiness of transport aircraft in the event of a crash accident, one of the subjects of Aviation Safety and Environmental Compatibility Technology Research(ASET) at NAL. Cooperative research related to this test program has also been carried out by NAL and Kawasaki Heavy Industr...

  7. Drop impact upon micro- and nanostructured superhydrophobic surfaces


    Tsai, Peichun; Pacheco, Sergio; Pirat, Christophe; Lefferts, Leon; Lohse, Detlef


    We experimentally investigate drop impact dynamics onto different superhydrophobic surfaces, consisting of regular polymeric micropatterns and rough carbon nanofibers, with similar static contact angles. The main control parameters are the Weber number \\We and the roughness of the surface. At small \\We, i.e. small impact velocity, the impact evolutions are similar for both types of substrates, exhibiting Fakir state, complete bouncing, partial rebouncing, trapping of an air bubble, jetting, a...

  8. Spinal shrinkage in unloaded and loaded drop-jumping. (United States)

    Fowler, N E; Lees, A; Reilly, T


    Plyometric activities, engaging the muscle in a stretch-shortening cycle, are widely used in athletic training. One such plyometric exercise is drop-jumping, where the athlete drops from a raised platform and immediately on landing performs a maximal vertical jump. These actions are also performed with the athlete externally loaded by the addition of weights to provide greater resistance. Exercises which involve repeated impacts have been shown to give rise to a loss of stature (shrinkage) which can be measured by means of a sensitive stadiometer. This study examined the shrinkage induced by unloaded and loaded drop-jumping from a height of 26 cm. Eight male subjects, aged 20-24 years, performed the test protocol three times, at the same time of day on each occasion. Fifty drop-jumps from a height of 26 cm were performed with no additional load and with a load of 8.5 kg carried in a weighted vest. The third condition was a standing trial where the subject stood for 10 min (the time taken to perform the jumps) wearing the weighted vest. Stature was measured before exercise, immediately after exercise and after a 20 min standing recovery. On a separate occasion the regimen was performed and the vertical reaction force was measured using a Kistler force platform. The mean change in stature for the two jump conditions showed shrinkages of 0.62 (+/- 0.43) mm for unloaded and 2.14 (+/- 1.56) mm for the loaded (p < 0.05). The variance in shrinkage was greater in the loaded case compared to the unloaded condition (p < 0.05) indicating a wider range of jumping strategies.(ABSTRACT TRUNCATED AT 250 WORDS)

  9. Surface tension of spherical drops from surface of tension

    Energy Technology Data Exchange (ETDEWEB)

    Homman, A.-A.; Bourasseau, E. [CEA/DAM DIF, F-91297 Arpajon Cedex (France); Stoltz, G. [Université Paris-Est, CERMICS (ENPC), INRIA, F-77455 Marne-la-Vallée (France); Malfreyt, P. [Institut de Chimie de Clermont-Ferrand, Université Blaise Pascal, UMR CNRS 6296, ICCF, BP 10448, F-63000 Clermont-Ferrand (France); Strafella, L.; Ghoufi, A., E-mail: [Institut de Physique de Rennes, Université de Rennes 1 UMR 6251 CNRS, 263 avenue Général Leclerc, 35042 Rennes (France)


    The determination of surface tension of curved interfaces is a topic that raised many controversies during the last century. Explicit liquid-vapor interface modelling (ELVI) was unable up to now to reproduce interfacial behaviors in drops due to ambiguities in the mechanical definition of the surface tension. In this work, we propose a thermodynamic approach based on the location of surface of tension and its use in the Laplace equation to extract the surface tension of spherical interfaces from ELVI modelling.

  10. Personality disorders and treatment drop out in the homeless


    Salavera C; Tricás JM; Lucha O


    Carlos Salavera,1 José M Tricás,2 Orosia Lucha21Faculty of Education, University of Zaragoza, Zaragoza, Spain; 2Physiotherapy Research Unit, University of Zaragoza, Zaragoza, SpainAbstract: The homeless drop out of treatment relatively frequently. Also, prevalence rates of personality disorders are much higher in the homeless group than in the general population. We hypothesize that when both variables coexist – homelessness and personality disorders &ndash...

  11. Comparison of 1D PDA sampling methods to obtain drop size and velocity distributions inside a spray cone of agricultural nozzles

    NARCIS (Netherlands)

    Holterman, H.J.


    In agriculture, spray drift research is carried out in field experiments and by computer simulation. Regarding the latter approach, accurate knowledge of the initial spray is required. Not only is the overall drop size distribution of the spray an important factor in the spraying process, but also

  12. Rapid Prototyping Laboratory (United States)

    Federal Laboratory Consortium — The ARDEC Rapid Prototyping (RP) Laboratory was established in December 1992 to provide low cost RP capabilities to the ARDEC engineering community. The Stratasys,...

  13. Application of Hanging Drop Technique for Kidney Tissue Culture. (United States)

    Wang, Shaohui; Wang, Ximing; Boone, Jasmine; Wie, Jin; Yip, Kay-Pong; Zhang, Jie; Wang, Lei; Liu, Ruisheng


    The hanging drop technique is a well-established method used in culture of animal tissues. However, this method has not been used in adult kidney tissue culture yet. This study was to explore the feasibility of using this technique for culturing adult kidney cortex to study the time course of RNA viability in the tubules and vasculature, as well as the tissue structural integrity. In each Petri dish with the plate covered with sterile buffer, a section of mouse renal cortex was cultured within a drop of DMEM culture medium on the inner surface of the lip facing downward. The tissue were then harvested at each specific time points for Real-time PCR analysis and histological studies. The results showed that the mRNA level of most Na+ related transporters and cotransporters were stably maintained within 6 hours in culture, and that the mRNA level of most receptors found in the vasculature and glomeruli were stably maintained for up to 9 days in culture. Paraffin sections of the cultured renal cortex indicated that the tubules began to lose tubular integrity after 6 hours, but the glomeruli and vasculatures were still recognizable up to 9 days in culture. We concluded that adult kidney tissue culture by hanging drop method can be used to study gene expressions in vasculature and glomeruli. © 2017 The Author(s). Published by S. Karger AG, Basel.

  14. Drop weld thermal injuries to the middle ear.

    LENUS (Irish Health Repository)

    Keogh, I J


    Drop weld injuries to the tympanic membrane and middle ear caused by hot sparks or molten slag are a rare but significant injury. Steel workers and welders who are regularly exposed to flying sparks and molten metal slag are predisposed. This type of transtympanic thermal injury occurs when the slag literally drops into the external auditory canal and burns through the tympanic membrane. A spectrum of severity of injury occurs which includes chronic tympanic membrane perforation, chronic otorrhoea, facial nerve injury and deafness. Chronic tympanic membrane perforation is the most common sequelae and is perhaps one of the most challenging of all perforations to repair The combination of direct thermal injury and foreign body reaction results in continuing or recurrent suppuration. The foreign body reaction is due to the embedding of metal slag in the promontorial mucosa. We present a case of drop weld injury to the left tympanic membrane, resulting in chronic middle ear inflammation, otorrhoea and tympanic perforation. CAT scan clearly demonstrated a metallic promontorial foreign body with localised bone erosion. We emphasise the importance of removing these foreign bodies and recommend a cartilage reinforced underlay tympanoplasty technique to repair these perforations. Transtympanic thermal trauma is a preventable occupational injury, which is best, avoided by earplugs and increased awareness.

  15. Coalescence of liquid drops: Different models versus experiment

    KAUST Repository

    Sprittles, J. E.


    The process of coalescence of two identical liquid drops is simulated numerically in the framework of two essentially different mathematical models, and the results are compared with experimental data on the very early stages of the coalescence process reported recently. The first model tested is the "conventional" one, where it is assumed that coalescence as the formation of a single body of fluid occurs by an instant appearance of a liquid bridge smoothly connecting the two drops, and the subsequent process is the evolution of this single body of fluid driven by capillary forces. The second model under investigation considers coalescence as a process where a section of the free surface becomes trapped between the bulk phases as the drops are pressed against each other, and it is the gradual disappearance of this "internal interface" that leads to the formation of a single body of fluid and the conventional model taking over. Using the full numerical solution of the problem in the framework of each of the two models, we show that the recently reported electrical measurements probing the very early stages of the process are better described by the interface formation/disappearance model. New theory-guided experiments are suggested that would help to further elucidate the details of the coalescence phenomenon. As a by-product of our research, the range of validity of different "scaling laws" advanced as approximate solutions to the problem formulated using the conventional model is established. © 2012 American Institute of Physics.

  16. Modeling axisymmetric flows dynamics of films, jets, and drops

    CERN Document Server

    Middleman, Stanley


    This concise book is intended to fulfill two purposes: to provide an important supplement to classic texts by carrying fluid dynamics students on into the realm of free boundary flows; and to demonstrate the art of mathematical modeling based on knowledge, intuition, and observation. In the authors words, the overall goal is make the complex simple, without losing the essence--the virtue--of the complexity.Modeling Axisymmetric Flows: Dynamics of Films, Jets, and Drops is the first book to cover the topics of axisymmetric laminar flows; free-boundary flows; and dynamics of drops, jets, and films. The text also features comparisons of models to experiments, and it includes a large selection of problems at the end of each chapter.Key Features* Contains problems at the end of each chapter* Compares real-world experimental data to theory* Provides one of the first comprehensive examinations of axisymmetric laminar flows, free-boundary flows, and dynamics of drops, jets, and films* Includes development of basic eq...

  17. Electromagnetic radiation from linearly and nonlinearly oscillating charge drops (United States)

    Grigor'ev, A. I.; Shiryaeva, S. O.


    It has been shown that analytic calculations of the intensity of electromagnetic radiation from an oscillating charged drop in the approximation linear in the oscillation amplitude (small parameter is on the order of 0.1) give only the quadrupole component of the total radiation. The dipole component can only be obtained in calculations using higher-order approximations. Nevertheless, the intensity of the dipole radiation turns out to be substantially higher (by 14-15 orders of magnitude). This is because the decomposition of radiation from a system of charges into multipole components (differing even in the rates of decrease in the potential with the distance) is carried out using the expansion in a substantially smaller parameter, viz., the ratio of the size of the emitting system (in our case, a drop of radius 10 μm) to the distance to the point of observation in the wave zone of the emission of radiation (emitted wavelength) of 100-1000 m. As a result, this second small parameter is on the order of 10-7 to 10-8. On the other hand, in accordance with the field theory, the ratio of intensities of quadrupole and dipole radiations is proportional to the squared ratio of the hydrodynamic velocity of the oscillating surface of a charged drop to the velocity of propagation of an electromagnetic signal in vacuum (velocity of light), which yields a ratio of 10-14 to 10-15.

  18. Seismic II over I Drop Test Program results and interpretation

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, B.


    The consequences of non-seismically qualified (Category 2) objects falling and striking essential seismically qualified (Category 1) objects has always been a significant, yet analytically difficult problem, particularly in evaluating the potential damage to equipment that may result from earthquakes. Analytical solutions for impact problems are conservative and available for mostly simple configurations. In a nuclear facility, the {open_quotes}sources{close_quotes} and {open_quotes}targets{close_quotes} requiring evaluation are frequently irregular in shape and configuration, making calculations and computer modeling difficult. Few industry or regulatory rules are available on this topic even though it is a source of considerable construction upgrade costs. A drop test program was recently conducted to develop a more accurate understanding of the consequences of seismic interactions. The resulting data can be used as a means to improve the judgment of seismic qualification engineers performing interaction evaluations and to develop realistic design criteria for seismic interactions. Impact tests on various combinations of sources and targets commonly found in one Savannah River Site (SRS) nuclear facility were performed by dropping the sources from various heights onto the targets. This report summarizes results of the Drop Test Program. Force and acceleration time history data are presented as well as general observations on the overall ruggedness of various targets when subjected to impacts from different types of sources.

  19. Seismic II over I Drop Test Program results and interpretation

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, B.


    The consequences of non-seismically qualified (Category 2) objects falling and striking essential seismically qualified (Category 1) objects has always been a significant, yet analytically difficult problem, particularly in evaluating the potential damage to equipment that may result from earthquakes. Analytical solutions for impact problems are conservative and available for mostly simple configurations. In a nuclear facility, the [open quotes]sources[close quotes] and [open quotes]targets[close quotes] requiring evaluation are frequently irregular in shape and configuration, making calculations and computer modeling difficult. Few industry or regulatory rules are available on this topic even though it is a source of considerable construction upgrade costs. A drop test program was recently conducted to develop a more accurate understanding of the consequences of seismic interactions. The resulting data can be used as a means to improve the judgment of seismic qualification engineers performing interaction evaluations and to develop realistic design criteria for seismic interactions. Impact tests on various combinations of sources and targets commonly found in one Savannah River Site (SRS) nuclear facility were performed by dropping the sources from various heights onto the targets. This report summarizes results of the Drop Test Program. Force and acceleration time history data are presented as well as general observations on the overall ruggedness of various targets when subjected to impacts from different types of sources.

  20. Personality disorders and treatment drop out in the homeless

    Directory of Open Access Journals (Sweden)

    Salavera C


    Full Text Available Carlos Salavera,1 José M Tricás,2 Orosia Lucha21Faculty of Education, University of Zaragoza, Zaragoza, Spain; 2Physiotherapy Research Unit, University of Zaragoza, Zaragoza, SpainAbstract: The homeless drop out of treatment relatively frequently. Also, prevalence rates of personality disorders are much higher in the homeless group than in the general population. We hypothesize that when both variables coexist – homelessness and personality disorders – the possibility of treatment drop out grows. The aim of this study was to analyze the hypotheses, that is, to study how the existence of personality disorders affects the evolution of and permanence in treatment. One sample of homeless people in a therapeutic community (N = 89 was studied. The structured clinical interview for the diagnostic and statistical manual of mental disorders (DSM-IV-TR was administered and participants were asked to complete the Millon Clinical Multiaxial Inventory-II (MCMI-II. Cluster B personality disorders (antisocial, borderline, and narcissistic avoided permanence in the treatment process while cluster C disorders, as dependent, favored adhesion to the treatment and improved the prognosis. Knowledge of these personality characteristics should be used to advocate for better services to support homeless people and prevent their dropping out before completing treatment.Keywords: MCMI-II, abandonment, personality disorder, homeless

  1. Pinning of a drop by a junction on an incline (United States)

    De Coninck, Joël; Fernández Toledano, Juan Carlos; Dunlop, François; Huillet, Thierry


    The shape of a drop pinned on an inclined substrate is a long-standing problem where the complexity of real surfaces, with heterogeneities and hysteresis, makes it complicated to understand the mechanisms behind the phenomena. Here we consider the simple case of a drop pinned on an incline at the junction between a hydrophilic half plane (the top half) and a hydrophobic one (the bottom half). Relying on the equilibrium equations deriving from the balance of forces, we exhibit three scenarios depending on the way the contact line of the drop on the substrate either simply leans against the junction or overfills (partly or fully) into the hydrophobic side. We draw some conclusions on the geometry of the overlap and the stability of these tentative equilibrium states. In the corresponding retention force factor, we find that a major role is played by the wetted length of the junction line, in the spirit of Furmidge's observations. The predictions of the theory are compared with extensive molecular dynamics simulations.

  2. [Preservative-containing eye drops and adherence in ophthalmological practice]. (United States)

    Lanzl, I; Kaercher, T


    Chronic eye diseases, such as glaucoma or dry eye syndrome, require long-term drug application to the eyes. Good adherence is required to achieve the therapeutic goal and patient needs and requirements have to be taken into account. This distinguishes adherence to drug therapy from the former compliance which implies only following medical instructions. Adherence is influenced by socioeconomic, health system-related, disease-related, treatment-related and patient-related factors. It can be measured by tedious procedures, such as electronic monitoring, self-assessment, drop counting and laboratory findings of systemic drug levels. Non-adherence is a growing medical problem worldwide. An increase in adherence means an increased degree of therapeutic safety for the patient and long-term cost savings for the individual as well as society. Non-adherence in chronic diseases, such as glaucoma and dry eye syndrome is increased by eye drops that cause side effects. Often these side effects are caused by agents such as the preservative benzalkonium chloride. To achieve a good adherence preservative-free eye drops are advised.

  3. Treatment of allergic conjunctivitis with olopatadine hydrochloride eye drops

    Directory of Open Access Journals (Sweden)

    Eiichi Uchio


    Full Text Available Eiichi UchioDepartment of Ophthalmology, Fukuoka University School of Medicine, Fukuoka, JapanAbstract: Olopatadine hydrochloride exerts a wide range of pharmacological actions such as histamine H1 receptor antagonist action, chemical mediator suppressive action, and eosinophil infiltration suppressive action. Olopatadine hydrochloride 0.1% ophthalmic solution (Patanol® was introduced to the market in Japan in October 2006. In a conjunctival allergen challenge (CAC test, olopatadine hydrochloride 0.1% ophthalmic solution significantly suppressed ocular itching and hyperemia compared with levocabastine hydrochloride 0.05% ophthalmic solution, and the number of patients who complained of ocular discomfort was lower in the olopatadine group than in the levocabastine group. Conjunctival cell membrane disruption was observed in vitro in the ketotifen fumarate group, epinastine hydrochloride group, and azelastine hydrochloride group, but not in the olopatadine hydrochloride 0.1% ophthalmic solution group, which may potentially explain the lower discomfort felt by patients on instillation. Many other studies in humans have revealed the superiority of olopatadine 0.1% hydrochloride eye drops to several other anti-allergic eye drops. Overseas, olopatadine hydrochloride 0.2% ophthalmic solution for a once-daily regimen has been marketed under the brand name of Pataday®. It is expected that olopatadine hydrochloride ophthalmic solutions may be used in patients with a more severe spectrum of allergic conjunctival diseases, such as vernal keratoconjunctivitis or atopic keratoconjunctivitis, in the near future.Keywords: olopatadine, eye drop, allergic conjunctivitis, anti-histaminergic

  4. Effect of drop jump technique on the reactive strength index. (United States)

    Struzik, Artur; Juras, Grzegorz; Pietraszewski, Bogdan; Rokita, Andrzej


    The basic drill of plyometric training aimed at improving lower limb power and jump height is a drop jump. This exercise can be performed using different techniques, which substantially affects jump variables. Therefore, the aim of this study was to compare the values of the reactive strength index (RSI) for countermovement drop jumps (CDJs) and bounce drop jumps (BDJs). The study was carried out in a group of 8 male youth basketball players. The tests were conducted using the AMTI BP600900 force plate to measure ground reaction forces and the Noraxon MyoMotion system to record kinematic data. Each player performed two CDJs and two BDJs from the height of 15, 30, 45 and 60 cm. The RSI was calculated as a ratio of jump height and contact time. Moreover, the RSI was determined for the amortization and take-off phases separately. Significant differences (p jumps from 30, 45 and 60 cm. Differences in RSI values for jumps from 15 cm were not significant. Furthermore, CDJ height values were significantly higher (p jump technique that is commonly performed by basketball players.

  5. The Pain Response to Mydriatic Eye Drops in Preterm Infants (United States)

    Cohen, Amy M.; Cook, Noah; Harris, Mary Catherine; Ying, Gui-shuang; Binenbaum, Gil


    Objective Evaluate physiologic and behavioral pain responses of premature infants following instillation of mydriatic eye drops for ROP examinations. While burning and stinging occurs in older patients, the infant pain response is not well characterized. Study Design Vital sign and video monitor recorded infant responses before, during, and after mydriatic (tropicamide 1%, phenylephrine 2.5%) administration upon first ROP exam. Two masked observers graded Premature Infant Pain Profile (PIPP) scores immediately prior and following eye drop administration. Scores 12 severe. Results Twenty infants had mean pre-mydriatic PIPP score 3.6 (SD 1.6), mean post-mydriatic score 5.7 (SD 3.4), mean change 2.1 (SD 3.4)(p=0.01). One (5%) had pre-mydriatic PIPP score ≥7, seven (35%) post scores ≥7 (p=0.07) with one >12. Conclusions Mydriatic drops cause a clinically significant pain response in one third of infants. Non-pharmacologic supportive measures are recommended for all infants until predictive factors are defined. PMID:23238569

  6. Impact and Penetration of Nanoparticle Suspension Drops into Porous Membranes (United States)

    Sahu, Rakesh; Yarin, Alexander; Pourdeyhimi, Behnam


    The impacts and dynamic penetration of drops with suspended nanoparticles into porous membranes are studied experimentally and theoretically. This type of penetration is radically different from the wettability-driven imbibition. Two types of membranes are used in the experiments: (i) glass fiber filter membrane (wettable) and (ii) PTFE depth filter (non-wettable). The nanoparticle entrainment and deposition inside the membrane bulk is used to mostly visualize the ultimate penetration fronts of the carrier fluid by observing the cut cross-sections of the filter membranes, albeit also provides an insight into potentially new applications like circuit printing on nonwovens. The experimental results demonstrate that during the dynamic focusing responsible for water penetration into micro- and nanopores, water can penetrate into a non-wettable porous medium (PTFE). Water also penetrates by the same focusing mechanism into the wettable glass fiber membrane, where it additionally spreads on a much longer time scale due to the wettability-driven flow. A theory explaining dynamic penetration of liquid into porous medium after drop impact is proposed. It is used to explain and predict water penetration into the non-wettable media after drop impact, and the results are compared with the experimental data. The work was supported by the Nonwovens Cooperative Research Center (NCRC).

  7. Personality disorders and treatment drop out in the homeless. (United States)

    Salavera, Carlos; Tricás, José M; Lucha, Orosia


    The homeless drop out of treatment relatively frequently. Also, prevalence rates of personality disorders are much higher in the homeless group than in the general population. We hypothesize that when both variables coexist - homelessness and personality disorders - the possibility of treatment drop out grows. The aim of this study was to analyze the hypotheses, that is, to study how the existence of personality disorders affects the evolution of and permanence in treatment. One sample of homeless people in a therapeutic community (N = 89) was studied. The structured clinical interview for the diagnostic and statistical manual of mental disorders (DSM-IV-TR) was administered and participants were asked to complete the Millon Clinical Multiaxial Inventory-II (MCMI-II). Cluster B personality disorders (antisocial, borderline, and narcissistic) avoided permanence in the treatment process while cluster C disorders, as dependent, favored adhesion to the treatment and improved the prognosis. Knowledge of these personality characteristics should be used to advocate for better services to support homeless people and prevent their dropping out before completing treatment.

  8. Microdrill Initiative - Initial Market Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Spears & Associates, Inc


    The U.S. Department of Energy (DOE) is launching a major research and development initiative to create a small, fast, inexpensive and environmentally friendly rig for drilling 5000 feet boreholes to investigate potential oil and gas reservoirs. DOE wishes to get input from petroleum industry operators, service companies and equipment suppliers on the operation and application of this coiled-tubing-based drilling unit. To that end, DOE has asked Spears & Associates, Inc. (SAI) to prepare a special state-of-the-market report and assist during a DOE-sponsored project-scoping workshop in Albuquerque near the end of April 2003. The scope of the project is four-fold: (1) Evaluate the history, status and future of demand for very small bore-hole drilling; (2) Measure the market for coiled tubing drilling and describe the state-of-the-art; (3) Identify companies and individuals who should have an interest in micro drilling and invite them to the DOE workshop; and (4) Participate in 3 concurrent workshop sessions, record and evaluate participant comments and report workshop conclusions.

  9. Family-friendly research and workplace initiative announced (United States)

    Showstack, Randy


    A new U.S. National Science Foundation (NSF) initiative aims to increase the participation of women and girls in the fields of science, technology, engineering, and math (STEM) over the next 10 years by providing more flexible research policies, promoting flexible workplace options, and supporting STEM careers for women, Obama administration officials announced on 26 September. Currently, women earn about 41% of STEM doctoral degrees awarded by U.S. educational institutions but make up only about 28% of tenure-track faculty in U.S. colleges and universities, the officials said. "Unfortunately, too many young women drop out of promising careers in science, engineering, and math because of conflicts between their desire to start families and the need to rapidly ramp up their careers," said John Holdren, director of the White House Office of Science and Technology Policy (OSTP). "The way to help women stay in the STEM jobs pipeline is to create and support more flexible workplace policies that allow a women's career—or a man's, for that matter, but as we know, it's more common for women to give up STEM careers for family reasons—to thrive even as time is allowed for important family responsibilities."

  10. Using a Projector to Control BZ Drops: Attractor Selection by Pattern Entrainment (United States)

    Tompkins, Nathan; Gonzalez Ochoa, Hector; Epstein, Irving; Fraden, Seth


    An emulsion consisting of drops in the 100 μ m diameter range containing the Belousov-Zhabotinsky (BZ) oscillatory chemicals can interact via diffusive inhibition and can be thought of as coupled phase oscillators. For weak coupling, a 2-D hexagonal lattice of these drops naturally develop regions of attractor states of sequential oscillations with phase differences of plus/minus 2 π / 3 much like the 2D anti-ferromagnetic Heisenberg spin model. An untrained system of these oscillators will develop unstable regions of both attractors that grow and compete. We use photo-initiated inhibition to optically entrain the system with a projected + 2 π / 3 pattern in an attempt to force the system into the + 2 π / 3 attractor state. However, both the left and right handed variants of the 2 π / 3 attractor are present in the entrained system. Defining an order parameter e i 3 ϕ allows for a quantitation of the purity of the 2 π / 3 attractor state in the final system.

  11. Drops and waves on a viscous film coating a vertical fiber (United States)

    Duprat, Camille; Giorgiutti-Dauphine, Frederique


    We consider the nonlinear dynamics of a liquid viscous film flowing down a vertical fiber. The initially flat film spontaneously breaks up into a regular wavetrain due to the Rayleigh-Plateau instability. The characteristics of the fully developed structures then depend on the dominant mechanisms. When the advection of the waves by the flow dominates over the instability, we observe moderate amplitude waves that propagate without carrying mass. When surface tension is strong, the film breaks up into large amplitude drops exhibiting a recirculation region. The transition between drops and waves regimes and the corresponding structures have been characterized experimentally and numerically. When both surface tension and viscosity effects are strong, the system can be seen has a paradigm for active (unstable), dissipative and dispersive media. The particular shape of the resulting structures gives rise to complex interactions (attraction and repulsion) leading to the formation of bound states. The system then appears to select a finite number of preferred specific distances in agreement with a weak interaction theory developed by D. Tseluiko, S. Saprykin and S. Kalliadasis (Imperial College London).

  12. Maximum spreading of liquid drop on various substrates with different wettabilities (United States)

    Choudhury, Raihan; Choi, Junho; Yang, Sangsun; Kim, Yong-Jin; Lee, Donggeun


    This paper describes a novel model developed for a priori prediction of the maximal spread of a liquid drop on a surface. As a first step, a series of experiments were conducted under precise control of the initial drop diameter, its falling height, roughness, and wettability of dry surfaces. The transient liquid spreading was recorded by a high-speed camera to obtain its maximum spreading under various conditions. Eight preexisting models were tested for accurate prediction of the maximum spread; however, most of the model predictions were not satisfactory except one, in comparison with our experimental data. A comparative scaling analysis of the literature models was conducted to elucidate the condition-dependent prediction characteristics of the models. The conditioned bias in the predictions was mainly attributed to the inappropriate formulations of viscous dissipation or interfacial energy of liquid on the surface. Hence, a novel model based on energy balance during liquid impact was developed to overcome the limitations of the previous models. As a result, the present model was quite successful in predicting the liquid spread in all the conditions.

  13. Impact of mydriatic eye drops on neonatal cerebral blood flow

    Directory of Open Access Journals (Sweden)

    Atef Alshafei


    Full Text Available Retinopathy of prematurity (ROP screening is a common routine procedure carried out on preterm infants in neonatal intensive care units (NICUs. Mydriatic eye drops containing phenylephrine hydrochloride 2.5% (a sympathomimetic agent and tropicamide 0.5% (a cycloplegic medication are readily absorbed from the conjunctiva and produce systemic responses in various organs. To our knowledge, no studies have investigated the direct effects of these medications on cerebral blood flow velocities (CBFVs in preterm infants. To evaluate the systemic effects of locally instilled mydriatic eye drops (phenylephrine hydrochloride 2.5% and tropicamide 0.5% used for ROP screening, on cerebral blood flow velocity in preterm infants, a prospective observational study was conducted among preterm infants with gestational age (GA < 31 weeks admitted to the NICU at Dubai Hospital between February 20, 2017 and June 20, 2017. The infants (at a post-menstrual age of 31-34 weeks underwent duplex ultrasound evaluation of CBFV before and after mydriatic eye drops administration.Pulsed-wave Doppler ultrasound studies were performed 1 h before and 1 h after eye mydriasis. We measured peak systolic velocity (PSV and end diastolic velocity (EDV for both the anterior cerebral artery (ACA and middle cerebral artery (MCA and calculated the resistive index (RI, defined as PSV – EDV/PSV. Mean arterial blood pressure (MAP, heart rate, oxygen saturation and pain score were assessed before and 1 h after ROP examination.A paired t-test and McNemar’s test were used to assess the statistical significance of the difference between pairs of means and the qualitative variables measured twice for the same study group.Among the 42 eligible preterm infants, the mean (SD GA was 27 (2.68 weeks (range, 24-31 weeks. The mean (SD RI of ACA before and 1 h after eye drops administration was 0.84 (0.06 and 0.83 (0.07 respectively (p = 0.453. The mean (SD RIs of MCA before and then 1 h after

  14. 3D FEM Simulations of Drop Test Reliability on 3D-WLP: Effects of Solder Reflow Residual Stress and Molding Resin Parameters (United States)

    Belhenini, Soufyane; Tougui, Abdellah; Bouchou, Abdelhake; Mohan, Ranganathan; Dosseul, Franck


    Numerous three-dimensional (3D) packaging technologies are currently used for 3D integration. 3D-wafer level package (3D-WLP) appears to be a way to keep increasing the density of the microelectronic components. The reliability of 3D components has to be evaluated on mechanical demonstrators with daisy chains before real production. Numerical modeling is acknowledged as a very efficient tool for design optimization. In this paper, 3D finite-elements calculations are carried out to analyze the effects of molding resin's mechanical properties and thickness on the 3D component's dynamic response under drop loading conditions. Residual stress generated by solder reflow is also discussed. The influences of residual stresses on the numerical estimation of the component behavior during drop loading are studied. Solder reflow residual stresses have an impact on solder plastic strain and die equivalent stress calculations. We have compared the result of two numerical drop test models. Stress-free initial conduction is introduced for the first model. Solder reflow residual stresses are considered as the initial condition for the second drop test model. Quantitative and qualitative comparisons are carried out to show the effect of residual stress in drop test calculations. For the effect of molding resin thickness on the component behavior under drop loading, the stress-free initial condition is considered. The effect of the molding resin's thickness on critical area location is discussed. The solder bump maximum plastic shear strain and the silicon die maximum equivalent stress are used as reliability criteria. Numerical submodeling techniques are used to increase calculation accuracy. Numerical results have contributed to the design optimization of the 3D-WLP component.

  15. Syracuse Univesity Test Report On Uptake Factor Resulting From A Dropped Storage Container - Phase II

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Zhi; Zhang, Jianshun S.


    Under certain circumstances, powder from an accidently dropped container can become airborne and inhaled by people nearby such as those who are moving the containers. The inhaled fine particles can deposit on respiratory tracts and lungs, causing asthma, lung cancer, and other acute respiratory illnesses and chronic symptoms. The objective of this study was to develop a standard procedure to measure the airborne concentrations of different size particles within the vicinity of a dropped container where a significant portion of the contained powder is ejected. Tungsten oxide (WO{sub 3}) was selected in this study to represent relatively heavy powders (7.16 g/cm3 specific gravity for WO{sub 3}). A typical can with the outer dimensions of 4.25” diameter and 4.875” tall was used as the container. The powder was dropped in two different configurations: 1) contained within a can covered by a lid that has a 0.25” diameter hole, and 2) contained within a can without a lid. The packing volume of the powder was 51.4 in3 (842.7 cm{sup 3}) and the target mass was 1936 g. The tests were carried out in a full-scale stainless steel environmental chamber with an interior volume of 852 ft3 (24.1 m3). The chamber system includes an internal recirculation loop with a rectangular air diffuser and 10 variable frequency drive fans to provide a typical room air recirculation flow pattern. Two air filters were installed in the chamber air supply duct and return duct to achieve the required low background particle concentration. The initial chamber air conditions were set at 70°F (± 5°F) and 50% (± 10%) RH. A supporting frame and releasing device were designed and built to trigger consistently the dropping of the can. The particle sampling inlet was placed 5 ft above the floor and 6 inches laterally away from the can’s falling path. Concentrations of particles between 0.5 μm and 20 μm were recorded in units of mass and number of particles per unit volume. The data acquisition

  16. Syracuse University Test Report On Uptake Factor Resulting From A Dropped Storage Container

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Z; Zhang, J S


    Under certain circumstances, powder from an accidently dropped container can become airborne and inhaled by people nearby such as those who are moving the containers. The inhaled fine particles can deposit on respiratory tracts and lungs, causing asthma, lung cancer, and other acute respiratory illnesses and chronic symptoms. The objective of this study was to develop a standard procedure to measure the airborne concentrations of different size particles within the vicinity of a dropped container where a significant portion of the contained powder is ejected. Tungsten oxide (WO{sub 3}) was selected in this study to represent relatively heavy powders (7.16 g/cm3 specific gravity for WO{sub 3}). A typical can with the outer dimensions of 4.25” diameter and 4.875” tall was used as the container. The powder was dropped in two different configurations: 1) contained within a can covered by a lid that has a 0.25” diameter hole, and 2) contained within a can without a lid. The packing volume of the powder was 51.4 in{sup 3} (842.7 cm{sup 3}) and the target mass was 1936 g. The tests were carried out in a full-scale stainless steel environmental chamber with an interior volume of 852 ft{sup 3} (24.1 m{sup 3}). The chamber system includes an internal recirculation loop with a rectangular air diffuser and 10 variable frequency drive fans to provide a typical room air recirculation flow pattern. Two air filters were installed in the chamber air supply duct and return duct to achieve the required low background particle concentration. The initial chamber air conditions were set at 70°F (± 5°F) and 50% (± 10%) RH. A supporting frame and releasing device were designed and built to trigger consistently the dropping of the can at a height of 8 feet from the bottom of the can to the impacting surface. The particle sampling inlet was placed 5 ft above the floor and 6 inches laterally away from the can’s falling path. Concentrations of particles between 0.5 μm and 20

  17. Applying fluvial geomorphological riffle-pool sequences concept when rebuilding the existing drop hydraulic structure

    Directory of Open Access Journals (Sweden)



    Full Text Available The paper deals with the problem of  rebuilding  the existing water straight drop  structure in Brenna on the Brennica river (Polish Carpathian mountains, which was changed into the rapid hydraulic structure. The technical project was set up in 1988 and finished in the same year. The structure was rebuilt in the field in the early autumn of 1990. One of the concepts of applied fluvial geomorphological solution was used to improve the river channel bed condition. In that case it was found that the existing hydraulic structure reducing river slope and stabilizing river bed can be changed without any harm in to semi-natural riffle structure which could be tolerated by river and organisms living in.  Artificial roughness of the slope plate of the rapid hydraulic structure was obtained by placing cobbles along all the slope apron of the structure. The diameter of cobbles was calculated applying various methods, and the optimum value for that dimension was chosen. The cobbles, used for rebuilding purposes, were taken directly from the riverbed, so that the structure is environmentally similar to the site. All work was done due to European Framework Directive for Rivers.

  18. Materials Genome Initiative (United States)

    Vickers, John


    The Materials Genome Initiative (MGI) project element is a cross-Center effort that is focused on the integration of computational tools to simulate manufacturing processes and materials behavior. These computational simulations will be utilized to gain understanding of processes and materials behavior to accelerate process development and certification to more efficiently integrate new materials in existing NASA projects and to lead to the design of new materials for improved performance. This NASA effort looks to collaborate with efforts at other government agencies and universities working under the national MGI. MGI plans to develop integrated computational/experimental/ processing methodologies for accelerating discovery and insertion of materials to satisfy NASA's unique mission demands. The challenges include validated design tools that incorporate materials properties, processes, and design requirements; and materials process control to rapidly mature emerging manufacturing methods and develop certified manufacturing processes

  19. Rapidly Developing Toxic Epidermal Necrolysis

    Directory of Open Access Journals (Sweden)

    Viktoria Oline Barrios Poulsen


    Full Text Available Severe cutaneous reactions with potentially fatal outcomes can have many different causes. The Stevens-Johnson syndrome (SJS and toxic epidermal necrolysis (TEN are rare. They are characterized by a low incidence but high mortality, and drugs are most commonly implicated. Urgent active therapy is required. Prompt recognition and withdrawal of suspect drug and rapid intervention can result in favourable outcome. No further international guidelines for treatment exist, and much of the treatment relies on old or experimental concepts with no scientific evidence. We report on a 54-year-old man experiencing rapidly developing drug-induced severe TEN and presented multiorgan failure involving the respiratory and circulatory system, coagulopathy, and renal insufficiency. Detachment counted 30% of total body surface area (TBSA. SCORTEN = 5, indicating a mortality rate >90%. The patient was sedated and mechanically ventilated, supported with fluids and inotropes to maintain a stable circulation. Component therapy was guided by thromboelastography (TEG. The patient received plasmapheresis, and shock reversal treatment was initiated. He was transferred to a specialized intensive care burn unit within 24 hours from admittance. The initial care was continued, and hemodialysis was started. Pulmonary, circulatory, and renal sequelae resolved with intensive care, and re-epithelialization progressed slowly. The patient was discharged home on hospital day 19.

  20. Statin-induced bilateral foot drop in a case of hypothyroidism (United States)

    Chaudhary, Neera; Duggal, Ashish Kumar; Makhija, Prashant; Puri, Vinod; Khwaja, Geeta Anjum


    Muscle involvement is a common manifestation of both clinical and subclinical hypothyroidism, with serum creatine kinase (CK) elevation being probably the most common manifestation, and is seen in up to 90% of patients, but is usually mild (less than 10 times the upper limit of normal). Rhabdomyolysis is a distinctively uncommon presentation of hypothyroidism described usually in the setting of precipitating events such as strenuous exercise, alcohol, or statin use. Rarely rhabdomyolysis and myoedema seen in hypothyroidism can be complicated by the development of anterior compartment syndrome leading to neurovascular compression. We describe a case of a patient with hypothyroidism who developed acute onset bilateral foot drop on initiation of statins. This case highlights the need for cautious use of statins in patients at risk for rhabdomyolysis. PMID:26425013

  1. Statin-induced bilateral foot drop in a case of hypothyroidism

    Directory of Open Access Journals (Sweden)

    Neera Chaudhary


    Full Text Available Muscle involvement is a common manifestation of both clinical and subclinical hypothyroidism, with serum creatine kinase (CK elevation being probably the most common manifestation, and is seen in up to 90% of patients, but is usually mild (less than 10 times the upper limit of normal. Rhabdomyolysis is a distinctively uncommon presentation of hypothyroidism described usually in the setting of precipitating events such as strenuous exercise, alcohol, or statin use. Rarely rhabdomyolysis and myoedema seen in hypothyroidism can be complicated by the development of anterior compartment syndrome leading to neurovascular compression. We describe a case of a patient with hypothyroidism who developed acute onset bilateral foot drop on initiation of statins. This case highlights the need for cautious use of statins in patients at risk for rhabdomyolysis.


    Directory of Open Access Journals (Sweden)

    Bi-yang Tuo


    Full Text Available The inferences of burden metallization rate on softening-melting dropping properties were investigated through softening-melting dropping test of three kinds of metalized burden pressure drop. The results indicated that the softeningmelting temperature interval of pre-reduction mixed burden is bigger than primeval mixed burden, the melting interval narrow with the rise of metallization rate of ferric burden as well as dropping temperature interval. The average pressure drop, maximum pressure drop and softening-melting dropping properties eigenvalue decrease with the rise of metallization rate of ferric burden. Besides, the dropping temperature of burden reduces with the rise of carbon content of molten iron. The combination high metalized burden and higher carbon content of molten iron is benefit to decreasing thickness of cohesive zone and improve permeability of cohesive zone.

  3. Oblique impacts of water drops onto hydrophobic and superhydrophobic surfaces: outcomes, timing, and rebound maps (United States)

    Antonini, C.; Villa, F.; Marengo, M.


    This paper presents an experimental study on water drop oblique impacts onto hydrophobic and superhydrophobic tilted surfaces, with the objective of understanding drop impact dynamics and the conditions for drop rebound on low wetting surfaces. Drop impact experiments were performed with millimetric water drops with Weber numbers in the range 25 definition of six different impact regimes: deposition, rivulet, sliding, rolling, partial rebound, and rebound. For superhydrophobic surfaces, surface tilting generally enhanced drop rebound and shedding from the surface, either by reducing drop rebound time up to 40 % or by allowing drop rebound even when impalement occurred in the vicinity of the impact region. On hydrophobic surfaces, rebound was never observed for tilt angles higher than 45°.

  4. Effect of recombinant human epidermal growth factor eye drops and deproteinized calf blood extract eye drops on corneal edema after phacoemulsification


    Jia Wang


    AIM:To compare the effect of recombinant human epidermal growth factor eye drops and deproteinized calf blood extract eye drops on corneal edema after phacoemulsification. METHODS:Totally 72 cases(72 eyes)of patients undergoing phacoemulsification were selected and divided into the observation group and the control group by random number table method. After surgery, the observation group were treated with deproteinized calf blood extract eye drops while the control group were treated with rec...

  5. Efficacy of atropine and anisodamine eye drops for adolescent pseudomyopia

    Directory of Open Access Journals (Sweden)

    Hui-Jie Wang


    Full Text Available AIM:To investigate the effect and local influence of atropine and anisodamine eye drops on adolescent pseudomyopia. METHODS:Totally 110 cases of juvenile pseudomyopia were randomly divided into two groups, the control group was given 10g/L atropine sulfate eye gel, and the observation group was treated with 5g/L raceanisodamine eye drops. The efficacy of two methods, the changes of axial length and intraocular pressure before and after treatment, and the incidence of adverse reactions were compared. RESULTS: There was no significant difference in cure rate between the two groups(χ2=0.533, P=0.465, but the effective rate of observation group was significantly better than the control group(χ2=3.907, P=0.048. Compared with the same group before treatment, the length of the axial length of the two groups increased in different degrees,and the increase value of the observation group was significantly higher than that of the control group, the difference was statistically significant(PP>0.05. The intraocular pressure of the two groups was significantly lower than that of the same group before treatment, and the difference between the two groups after treatments was not statistically significant(P >0.05. The incidence of adverse reactions in the observation group was significantly lower than that in the control group(χ2=18.939, PCONCLUSION: Anisodamine eye drops in the treatment of juvenile pseudomyopia has obvious curative effect, its efficacy and safety are better than atropine eye gel.

  6. Drop Tower Experiments concerning Fluid Management under Microgravity (United States)

    Gaulke, Diana; Dreyer, Michael


    Transport and positioning of liquid under microgravity is done utilizing capillary forces. Therefore, capillary transport processes have to be understood for a wide variety of space applications, ranging from propellant management in tanks of space transportation systems to eating and drinking devices for astronauts. There are two types of liquid transportation in microgravity using capillary forces. First, the driven liquid flow in open channels where the capillary forces at free surfaces ensure a gas and vapor free flow. Here it is important to know the limiting flow rate through such an open channel before the free surface collapses and gas is sucked into the channel. A number of different experiments at the drop tower Bremen, on sounding rockets and at the ISS have been conducted to analyse this phenomenon within different geometries. As result a geometry dependent theory for calculating the maximum flow rate has been found. On the other hand liquid positioning and transportation requires the capillary pressure of curved surfaces to achieve a liquid flow to a desired area. Especially for space applications the weight of structure has to be taken into account for development. For example liquid positioning in tanks can be achieved via a complicated set of structure filling the whole tank resulting in heavy devices not reasonable in space applications. Astrium developed in cooperation with ZARM a propellant management device much smaller than the tank volume and ensuring a gas and vapour free supply of propellant to the propulsion system. In the drop tower Bremen a model of this device was tested concerning different microgravity scenarios. To further decrease weight and ensure functionality within different scenarios structure elements are designed as perforated geometries. Capillary transport between perforated plates has been analyzed concerning the influence of geometrical pattern of perforations. The conducted experiments at the drop tower Bremen show the

  7. Rapid Airplane Parametric Input Design (RAPID) (United States)

    Smith, Robert E.


    RAPID is a methodology and software system to define a class of airplane configurations and directly evaluate surface grids, volume grids, and grid sensitivity on and about the configurations. A distinguishing characteristic which separates RAPID from other airplane surface modellers is that the output grids and grid sensitivity are directly applicable in CFD analysis. A small set of design parameters and grid control parameters govern the process which is incorporated into interactive software for 'real time' visual analysis and into batch software for the application of optimization technology. The computed surface grids and volume grids are suitable for a wide range of Computational Fluid Dynamics (CFD) simulation. The general airplane configuration has wing, fuselage, horizontal tail, and vertical tail components. The double-delta wing and tail components are manifested by solving a fourth order partial differential equation (PDE) subject to Dirichlet and Neumann boundary conditions. The design parameters are incorporated into the boundary conditions and therefore govern the shapes of the surfaces. The PDE solution yields a smooth transition between boundaries. Surface grids suitable for CFD calculation are created by establishing an H-type topology about the configuration and incorporating grid spacing functions in the PDE equation for the lifting components and the fuselage definition equations. User specified grid parameters govern the location and degree of grid concentration. A two-block volume grid about a configuration is calculated using the Control Point Form (CPF) technique. The interactive software, which runs on Silicon Graphics IRIS workstations, allows design parameters to be continuously varied and the resulting surface grid to be observed in real time. The batch software computes both the surface and volume grids and also computes the sensitivity of the output grid with respect to the input design parameters by applying the precompiler tool

  8. Assessment of the quality of drop size measurements using a non-dedicated present weather sensor

    NARCIS (Netherlands)

    Leijnse, H.; Uijlenhoet, R.


    Drop size data from a present weather sensor have been compared to drop size data collected using a nearly co-located dedicated disdrometer. In a rainfall event that lasted more than 9 hours, with rainfall intensities up to 25 mm h-1 drop size distributions (DSDs) estimated by the two different

  9. The bifurcation diagram of drops in a sphere/plane geometry: influence of contact angle hysteresis

    NARCIS (Netherlands)

    de Ruiter, Riëlle; van Gorcum, M.; Semprebon, C.; Duits, Michael H.G.; Brinkmann, M.; Mugele, Friedrich Gunther


    We study liquid drops that are present in a generic geometry, namely the gap in between a sphere and a plane. For the ideal system without contact angle hysteresis, the drop position is solely dependent on the contact angle, drop volume, and sphere/ plane separation distance. Performing a geometric

  10. Determining fluid level in a translucent eye-drop bottle: transillumination by penlight. (United States)

    Kayikcioğlu, O; Akkin, C; Ates, H

    We describe an easy way to determine eye-drop contents in translucent bottles. Transillumination of eye-drop bottles from behind or the bottom by using a penlight clearly defines the fluid levels. The described procedure may prevent disposal of eye-drop bottles containing useful amounts of medication and prevent Ophthalmologists and Patients unexpectedly coming across an empty bottle.

  11. An improved technique of eye drop self-administration for patients with limited vision. (United States)

    Ritch, Robert; Jamal, Karim N; Gürses-Ozden, Rabia; Liebmann, Jeffrey M


    To describe a new, highly accurate, tactile technique to increase accuracy in the self-administration of eye drops. Interventional case series. Ten adult patients with loss of fixation (bottle, and location of the drops' landing points on the face or eye were recorded. The patients were then instructed in a new technique for instillation, guided through the procedure once, and allowed to practice until comfortable with it. All measurements were then repeated. In patients with loss of fixation in one eye, an additional 3.2 +/- 4.1 seconds were required to instill a drop using the new technique (P <.0001, paired t test; range, -7-18 seconds). The mean number of drops dispensed decreased by 0.1 +/- 0.6 drops (P =.60, paired t test; range, -2-1 drop). The accuracy of drop placement increased from 80.0% to 82.5% (P =.32, paired t test). In subjects with loss of fixation in both eyes, using the new technique increased the time needed to instill a drop by 3.8 +/- 3.8 seconds (P <.0001, paired t test; range, -3-13 seconds). The average number of drops dispensed decreased by 0.1 +/- 0.6 drops (P =.25, paired t test; range, -2-1 drop). The accuracy of placement increased from 63.0% to 85.0% (P =.001, paired t test). This technique of drop instillation may be beneficial for patients with significant visual impairment in both eyes.

  12. Is Drop-Out from University Dependent on National Culture and Policy? The Case of Denmark (United States)

    Troelsen, Rie; Laursen, Per F.


    National cultures are known to influence educational institutions and practices in many ways. It therefore seems reasonable to assume that drop-out from university is also influenced by differences in national cultures. In this article, we compare drop-out from Danish universities with drop-out from European universities. Based on Danish national…

  13. Drop shape analysis for determination of dynamic contact angles by double sided elliptical fitting method

    DEFF Research Database (Denmark)

    Andersen, Nis Korsgaard; Taboryski, Rafael J.


    fitted to a drop profile derived from the Young-Laplace equation. When measuring the wetting behaviour by tilting experiments this is not possible since it involves moving drops that are not in equilibrium. Here we present a fitting technique capable of determining the contact angle of asymmetric drops...

  14. 33 CFR 401.49 - Dropping anchor or tying to canal bank. (United States)


    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Dropping anchor or tying to canal bank. 401.49 Section 401.49 Navigation and Navigable Waters SAINT LAWRENCE SEAWAY DEVELOPMENT... Dropping anchor or tying to canal bank. Except in an emergency, no vessel shall drop anchor in any canal or...

  15. Tracking Drop-out Students in Palestinian Refugee Camps in Lebanon (United States)

    Al-Hroub, Anies


    This research paper examines the perceptions of students on the school drop-out problem in Palestinian refugee camps in Lebanon regarding (a) the social and economic causes associated with the phenomenon of school drop-out; (b) the educational policies and practices used in UNRWA schools and their relationship to student drop-out; and (c) the role…

  16. A novel Caulimovirus associated with a complete fruit drop symptom in ‘Bluecrop’ blueberry (United States)

    Here we describe the nucleotide sequence and genome organization of a novel virus in the family Caulimoviridae from ‘Bluecrop’ blueberry plants that exhibited fruit drop symptoms. The virus is tentatively named Blueberry fruit drop associated virus (BFDaV). Blueberry fruit drop disease (BFDD) was fi...

  17. Adaptive simulations of drop/interface impact and rupture (United States)

    Zheng, Xiaoming; Lowengrub, John; Longmire, Ellen; Cristini, Vittorio


    We present an algorithm for simulations of topology transitions (e.g., breakup and coalescence) in complex multiphase fluids. The algorithm is based on a finite element unstructured triangulated mesh, and on a diffuse-interface representation of the interfaces. During a simulation, the computational mesh is automatically adapted to describe accurately the complex morphology associated to the topology transitions and the narrow lubrication gaps between the interfaces. We apply this algorithm to study the impact and coalescence of viscous drops on solid and fluid-fluid interfaces. We compare our simulations to experimental results.

  18. Pressure Drop in Vertical Core-Annular Flow


    Prada,José Walter Vanegas; Bannwart,Antonio Carlos


    An experimental apparatus for the study of core annular flows of heavy oil and water at room temperature has been set up and tested at laboratory scale. The test section consists of a 2.75 cm ID galvanized steel pipe. Tap water and a heavy oil (17.6 Pa.s; 963 kg/m³) were used. Pressure drop in a vertical upward test section was accurately measured for oil flow rates in the range 0.297 - 1.045 l/s and water flow rates ranging from 0.063 to 0.315 l/s. The oil-water input ratio was in the range ...

  19. Simple Model For Pressure Drop In Horizontal Core Annular Flow


    Bannwart A.C.


    Based upon experimental data for heavy oil-water flow inside steel (26.7 mm ID) and cemented (23.9 mm ID) horizontal tubes, a very simple model for pressure drop in the core annular flow pattern was developed. The experiments were run at room temperature and the fluids used were a fuel oil (μ = 2.7 Pa.s, ρ = 989 kg/m3) and tap water, both drawn from a separator tank. First, it is shown that for both tubes the so-called 'perfect core annular flow' approach (shortly PCAF) poorly correlates the ...

  20. Optimization of fall height setting for drop weight tested polypropylene

    Directory of Open Access Journals (Sweden)

    Hylova Lenka


    Full Text Available This study deals with polypropylene (PP which was subjected the drop-weight test. PP is a semicrystalline thermoplastic polymer which is commonly used in many indoor applications and also in the automotive industry in the car interiors. The injection moulded PP samples were subjected the penetration test at different fall heights and the results were subsequently evaluated and discussed. It was found out that the fall heights from 100 to 230 J are suitable for PP penetration, but the optimal one is 100 J. Higher heights are not needed because of increasing power consumption of the test device.