Adhesive Wear Performance of CFRP Multilayered Polyester Composites Under Dry/wet Contact Conditions

Science.gov (United States)

Danaelan, D.; Yousif, B. F.

The tribo-performance of a new engineering composite material based on coconut fibers was investigated. In this work, coconut fibers reinforced polyester (CFRP) composites were developed. The tribo-experiments were conducted by using pin-on-disc machine under dry and wet sliding contact condition against smooth stainless steel counterface. Worn surfaces were observed using optical microscope. Friction coefficient and specific wear rate were presented as a function of sliding distance (0-0.6 km) at different sliding velocities (0.1-0.28 m/s). The effect of applied load and sliding velocity was evaluated. The results showed that all test parameters have significant influence on friction and wear characteristics of the composites. Moreover, friction coefficient increased as the normal load and speed increased, the values were about 0.7-0.9 under dry contact condition. Meanwhile, under wet contact condition, there was a great reduction in the friction coefficient, i.e. the values were about 0.1-0.2. Furthermore, the specific wear rates were found to be around 2-4 (10-3) mm3/Nm under dry contact condition and highly reduced under wet condition. In other words, the presence of water as cleaner and polisher assisted to enhance the adhesive wear performance of CFRP by about 10%. The images from optical microscope showed evidence of adhesive wear mode with transition to abrasive wear mode at higher sliding velocities due to third body abrasion. On the other hand, optical images for wet condition showed less adhesive wear and smooth surfaces.

Conductance enhancement in quantum-point-contact semiconductor-superconductor devices

DEFF Research Database (Denmark)

Mortensen, Asger; Jauho, Antti-Pekka; Flensberg, Karsten

1999-01-01

We present numerical calculations of the conductance of an interface between a phase-coherent two-dimensional electron gas and a superconductor with a quantum point contact in the normal region. Using a scattering matrix approach we reconsider the geometry of De Raedt, Michielsen, and Klapwijk...... [Phys. Rev. B 50, 631 (1994)] which was studied within the time-dependent Bogoliubov-de Gennes formalism. We find that the factor-of-2 enhancement of the conductance G(NS) compared to the normal state conductance GN for ideal interfaces may be suppressed for interfaces with a quantum point contact...

Shot Noise Suppression in a Quantum Point Contact with Short Channel Length

International Nuclear Information System (INIS)

Jeong, Heejun

2015-01-01

An experimental study on the current shot noise of a quantum point contact with short channel length is reported. The experimentally measured maximum energy level spacing between the ground and the first excited state of the device reached up to 7.5 meV, probably due to the hard wall confinement by using shallow electron gas and sharp point contact geometry. The two-dimensional non-equilibrium shot noise contour map shows noise suppression characteristics in a wide range of bias voltage. Fano factor analysis indicates spin-polarized transport through a short quantum point contact. (paper)

The Management of Refractory Dry Eye With Semi-Scleral Contact Lens.

Science.gov (United States)

Yuksel, Erdem; Bilgihan, Kamil; Novruzlu, Şahin; Yuksel, Nilay; Koksal, Murat

2016-05-19

We presented a case of refractory dry eye management with semi-scleral contact lens. Dry eye was associated with facial nerve (cranial nerve VII) palsy as a result of cerebellopontine angle tumor surgery. She was treated with several topical treatments and punctal plug. Despite the treatments, her symptoms still persisted. Her ophthalmic examination revealed scleral exposure because of lagophthalmos, conjunctival hyperemia, corneal debris, scar, and diffuse punctate epitheliopathy on her right eye. Lissamine green staining showed diffuse conjunctival and corneal staining. Therapeutic semi-scleral lenses were fitted. The corneal findings were resolved and the quality of patient life was improved with the aid of semi-scleral lens after 3 months.

Conductance histogram evolution of an EC-MCBJ fabricated Au atomic point contact

Energy Technology Data Exchange (ETDEWEB)

Yang Yang; Liu Junyang; Chen Zhaobin; Tian Jinghua; Jin Xi; Liu Bo; Yang Fangzu; Tian Zhongqun [State Key Laboratory of Physical Chemistry of Solid Surfaces and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Li Xiulan; Tao Nongjian [Center for Bioelectronics and Biosensors, Biodesign Institute, Department of Electrical Engineering, Arizona State University, Tempe, AZ 85287-6206 (United States); Luo Zhongzi; Lu Miao, E-mail: zqtian@xmu.edu.cn [Micro-Electro-Mechanical Systems Research Center, Pen-Tung Sah Micro-Nano Technology Institute, Xiamen University, Xiamen 361005 (China)

2011-07-08

This work presents a study of Au conductance quantization based on a combined electrochemical deposition and mechanically controllable break junction (MCBJ) method. We describe the microfabrication process and discuss improved features of our microchip structure compared to the previous one. The improved structure prolongs the available life of the microchip and also increases the success rate of the MCBJ experiment. Stepwise changes in the current were observed at the last stage of atomic point contact breakdown and conductance histograms were constructed. The evolution of 1G{sub 0} peak height in conductance histograms was used to investigate the probability of formation of an atomic point contact. It has been shown that the success rate in forming an atomic point contact can be improved by decreasing the stretching speed and the degree that the two electrodes are brought into contact. The repeated breakdown and formation over thousands of cycles led to a distinctive increase of 1G{sub 0} peak height in the conductance histograms, and this increased probability of forming a single atomic point contact is discussed.

Conductance histogram evolution of an EC-MCBJ fabricated Au atomic point contact

International Nuclear Information System (INIS)

Yang Yang; Liu Junyang; Chen Zhaobin; Tian Jinghua; Jin Xi; Liu Bo; Yang Fangzu; Tian Zhongqun; Li Xiulan; Tao Nongjian; Luo Zhongzi; Lu Miao

2011-01-01

This work presents a study of Au conductance quantization based on a combined electrochemical deposition and mechanically controllable break junction (MCBJ) method. We describe the microfabrication process and discuss improved features of our microchip structure compared to the previous one. The improved structure prolongs the available life of the microchip and also increases the success rate of the MCBJ experiment. Stepwise changes in the current were observed at the last stage of atomic point contact breakdown and conductance histograms were constructed. The evolution of 1G 0 peak height in conductance histograms was used to investigate the probability of formation of an atomic point contact. It has been shown that the success rate in forming an atomic point contact can be improved by decreasing the stretching speed and the degree that the two electrodes are brought into contact. The repeated breakdown and formation over thousands of cycles led to a distinctive increase of 1G 0 peak height in the conductance histograms, and this increased probability of forming a single atomic point contact is discussed.

Effect of the cut off frequency on rough point and flat surface contacts

International Nuclear Information System (INIS)

Meng, Fan Ming

2012-01-01

In the past years, contact between two bodies has been studied from various ways that do not consider the cut off frequency effect on the contact mechanism. This paper reports the correlation between rough point contact and flat surface contact at different cut off frequencies of filter. The similarity and difference between the two types of contact mechanisms are presented for materials with linear or elastic perfectly plastic deformation. The conjugate gradient method (CGM) is used for analysing the rough point contact, while the rough flat surface contact is studied with an improved CGM in which the influence coefficient for the elastic deformation of the rough flat surface is obtained with finite element method. Numerical results show that for the above two types of contacts, their von Mises stress and maximum shear stress are greatly affected by the cut-off frequency of a high pass filter. Moreover, a decrease in the cut-off frequency leads to an increase in the contact area and a decrease in the approach for the rough flat surface contact, while the opposite variations is for the point contact between rough bodies with the small radii

Design, Fabrication and Experimental Validation of a Novel Dry-Contact Sensor for Measuring Electroencephalography Signals without Skin Preparation

Directory of Open Access Journals (Sweden)

Chin-Teng Lin

2011-05-01

Full Text Available In the present study, novel dry-contact sensors for measuring electro-encephalography (EEG signals without any skin preparation are designed, fabricated by an injection molding manufacturing process and experimentally validated. Conventional wet electrodes are commonly used to measure EEG signals; they provide excellent EEG signals subject to proper skin preparation and conductive gel application. However, a series of skin preparation procedures for applying the wet electrodes is always required and usually creates trouble for users. To overcome these drawbacks, novel dry-contact EEG sensors were proposed for potential operation in the presence or absence of hair and without any skin preparation or conductive gel usage. The dry EEG sensors were designed to contact the scalp surface with 17 spring contact probes. Each probe was designed to include a probe head, plunger, spring, and barrel. The 17 probes were inserted into a flexible substrate using a one-time forming process via an established injection molding procedure. With these 17 spring contact probes, the flexible substrate allows for high geometric conformity between the sensor and the irregular scalp surface to maintain low skin-sensor interface impedance. Additionally, the flexible substrate also initiates a sensor buffer effect, eliminating pain when force is applied. The proposed dry EEG sensor was reliable in measuring EEG signals without any skin preparation or conductive gel usage, as compared with the conventional wet electrodes.

Effect of occlusal contact stability on the jaw closing point during tapping movements.

Science.gov (United States)

Nishigawa, Keisuke; Suzuki, Yoshitake; Ishikawa, Teruaki; Bando, Eiichi

2012-04-01

We studied the relationship between tapping point reproducibility and stability of occlusal contacts at maximum intercuspation. Tapping movements of 12 adult volunteers who had dentition with natural teeth were recorded, and distances between the tapping point (TP) and the intercuspal position (ICP) at the incisal point were calculated. Occlusal contacts at the ICP of individual subjects were also evaluated with black-colored silicone impression material. The correlation between TP-ICP distance and occlusal contact stability was studied. TP-ICP distance exhibited negative correlations with the total number of teeth showing occlusal contact at the ICP. Standard deviations of TP-ICP distance also negatively correlated with the extension of occlusal contact area over dentition. This finding indicates that occlusal contacts at the ICP affect the kinematic behavior of tapping movements. The results of this study also suggest that jaw movement data may provide useful clinical information for the evaluation of occlusal contact at ICP. Copyright © 2011 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

The features of ballistic electron transport in a suspended quantum point contact

International Nuclear Information System (INIS)

Shevyrin, A. A.; Budantsev, M. V.; Bakarov, A. K.; Toropov, A. I.; Pogosov, A. G.; Ishutkin, S. V.; Shesterikov, E. V.

2014-01-01

A suspended quantum point contact and the effects of the suspension are investigated by performing identical electrical measurements on the same experimental sample before and after the suspension. In both cases, the sample demonstrates conductance quantization. However, the suspended quantum point contact shows certain features not observed before the suspension, namely, plateaus at the conductance values being non-integer multiples of the conductance quantum, including the “0.7-anomaly.” These features can be attributed to the strengthening of electron-electron interaction because of the electric field confinement within the suspended membrane. Thus, the suspended quantum point contact represents a one-dimensional system with strong electron-electron interaction

Wear of Polished Steel Surfaces in Dry Friction Linear Contact on Polimer Composites with Glass Fibres

Directory of Open Access Journals (Sweden)

D. Rus

2013-12-01

Full Text Available It is generally known that the friction and wear between polymers and polished steel surfaces has a special character, the behaviour to friction and wear of a certain polymer might not be valid for a different polymer, moreover in dry friction conditions. In this paper, we study the reaction to wear of certain polymers with short glass fibres on different steel surfaces, considering the linear friction contact, observing the friction influence over the metallic surfaces wear. The paper includes also its analysis over the steel’s wear from different points of view: the reinforcement content influence and tribological parameters (load, contact pressure, sliding speed, contact temperature, etc.. Thus, we present our findings related to the fact that the abrasive component of the friction force is more significant than the adhesive component, which generally is specific to the polymers’ friction. Our detections also state that, in the case of the polyamide with 30% glass fibres, the steel surface linear wear rate order are of 10-4 mm/h, respectively the order of volumetric wear rate is of 10-6 cm3 /h. The resulting volumetric wear coefficients are of the order (10-11 – 10-12 cm3/cm and respectively linear wear coefficients of 10-9 mm/cm.

Corneal confocal microscopy and dry eye findings in contact lens discomfort patients.

Science.gov (United States)

Dogan, Aysun Sanal; Gurdal, Canan; Arslan, Nese

2018-02-01

To evaluate the corneal confocal microscopy and dry eye findings in patients with contact lens discomfort. The study included 3 groups of participants: Contact lens wearers using silicone hydrogel soft contact lenses who are symptomatic (CLD, n=15) or asymptomatic (ACL, n=11) and non-wearers as controls (n=14). Duration of contact lens wear, Ocular Surface Disease Index (OSDI) questionnaire responses, fluorescein tear break-uptime (FBUT), and corneal confocal microscopy findings were recorded. Mean age was 25.7±8.2 years and male/female ratio was 7/33. Demographic findings were similar regarding the groups. CLD patients had a longer lens use history than ACL (median 5 vs 2 years, pCLD group than ACL or controls (pCLD group, compared to controls and ACL (pCLD group compared to controls but similar to ACL (pCLD group than the ACL (p=0.014). Patients with CLD had been wearing contact lenses for longer than those without symptoms. OSDI and FBUT scores were worse in CLD patients. In contact lens discomfort patients, there were increased dendritiform cells, indicating intensified inflammatory status of the cornea. Copyright © 2017 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Droplet Drying Patterns on Solid Substrates: From Hydrophilic to Superhydrophobic Contact to Levitating Drops

Directory of Open Access Journals (Sweden)

Sujata Tarafdar

2018-01-01

Full Text Available This review is devoted to the simple process of drying a multicomponent droplet of a complex fluid which may contain salt or other inclusions. These processes provide a fascinating subject for study. The explanation of the rich variety of patterns formed is not only an academic challenge but also a problem of practical importance, as applications are growing in medical diagnosis and improvement of coating/printing technology. The fundamental scientific problem is the study of the mechanism of micro- and nanoparticle self-organization in open systems. The specific fundamental problems to be solved, related to this system, are the investigation of the mass transfer processes, the formation and evolution of phase fronts, and the identification of mechanisms of pattern formation. The drops of liquid containing dissolved substances and suspended particles are assumed to be drying on a horizontal solid insoluble smooth substrate. The chemical composition and macroscopic properties of the complex fluid, the concentration and nature of the salt, the surface energy of the substrate, and the interaction between the fluid and substrate which determines the wetting all affect the final morphology of the dried film. The range of our study encompasses the fully wetting case with zero contact angle between the fluid and substrate to the case where the drop is levitated in space, so there is no contact with a substrate and angle of contact can be considered as 180°.

Multiple contacts with diversion at the point of arrest.

Science.gov (United States)

Riordan, Sharon; Wix, Stuart; Haque, M Sayeed; Humphreys, Martin

2003-04-01

A diversion at the point of arrest (DAPA) scheme was set up in five police stations in South Birmingham in 1992. In a study of all referrals made over a four-year period a sub group of multiple contact individuals was identified. During that time four hundred and ninety-two contacts were recorded in total, of which 130 were made by 58 individuals. The latter group was generally no different from the single contact group but did have a tendency to be younger. This research highlights the need for a re-evaluation of service provision and associated education of police officers and relevant mental health care professionals.

Anomalous Integer Quantum Hall Effect in the Ballistic Regime with Quantum Point Contacts

NARCIS (Netherlands)

Wees, B.J. van; Willems, E.M.M.; Harmans, C.J.P.M.; Beenakker, C.W.J.; Houten, H. van; Williamson, J.G.; Foxon, C.T.; Harris, J.J.

1989-01-01

The Hall conductance of a wide two-dimensional electron gas has been measured in a geometry in which two quantum point contacts form controllable current and voltage probes, separated by less than the transport mean free path. Adjustable barriers in the point contacts allow selective population and

The Matrix Metalloproteinase 9 Point-of-Care Test in Dry Eye.

Science.gov (United States)

Lanza, Nicole L; Valenzuela, Felipe; Perez, Victor L; Galor, Anat

2016-04-01

Dry eye is a common, multifactorial disease currently diagnosed by a combination of symptoms and signs. However, the subjective symptoms of dry eye poorly correlate to the current gold standard for diagnostic tests, reflecting the need to develop better objective tests for the diagnosis of dry eye. This review considers the role of ocular surface matrix metalloproteinase 9 (MMP-9) in dry eye and the implications of a novel point-of-care test that measures MMP-9 levels, InflammaDry (RPS, Sarasota, FL) on choosing appropriate therapeutic treatments. Published by Elsevier Inc.

Water loss at normal enamel histological points during air drying at room temperature.

Science.gov (United States)

De Medeiros, R C G; De Lima, T A S; Gouveia, C R; De Sousa, F B

2013-06-01

This in vitro study aimed to quantify water loss at histological points in ground sections of normal enamel during air drying at room temperature (25°C) and relative humidity of 50%. From each of 10 ground sections of erupted permanent human normal enamel, three histological points (n = 30) located at 100, 300 and 500 μm from enamel surface and along a transversal following prisms paths were characterized regarding the mineral, organic and water volumes. Water loss during air drying was from 0 to 48 h. Drying occurred with both falling and constant-drying rates, and drying stabilization times (Teq ) ranged from 0.5 to 11 h with a mean 0.26 (±0.12)% weight loss. In some samples (n = 5; 15 points), Teq increased as a function of the distance from the enamel surface, and drying occurred at an apparent diffusion rate of 3.47 × 10⁻⁸ cm² s⁻¹. Our data provide evidence of air drying resulting in air replacing enamel's loosely bound water in prisms sheaths following a unidirectional water diffusion rate of 3.47 × 10⁻⁸ cm² s⁻¹ (from the original enamel surface inward), not necessarily resulting in water evaporating directly into air, with important implications for transport processes and optical and mechanical properties. © 2013 The Authors Journal of Microscopy © 2013 Royal Microscopical Society.

Cosmetic Cleansing Oil Absorption by Soft Contact Lenses in Dry and Wet Conditions.

Science.gov (United States)

Tsukiyama, Junko; Miyamoto, Yuko; Kodama, Aya; Fukuda, Masahiko; Shimomura, Yoshikazu

2017-09-01

Previous reports showed that cosmetic cleansing oil for removing makeup, which contains mineral oil and surfactant, can deform some silicone hydrogel contact lenses (SHCLs) when applied directly to the lenses, although plasma-coated SHCLs (lotrafilcon A and B) were not affected. In the present study, we investigated hydrogel lenses and SHCLs in both wet and dry conditions. Several brands of hydrogel and SHCLs were immersed in a cleansing oil solution containing Sudan Black B for 5 min under wet and dry conditions. The lenses under the wet condition were simply picked up from the saline, whereas those under the dry condition were blotted with paper wipes. After immersing, the excess solution remaining on the lenses was removed by finger rubbing with a multipurpose solution. The lenses were then examined using a stereomicroscope, and their mean brightness was measured and compared. The cosmetic cleansing oil was not absorbed by the hydrogel lenses under wet or dry conditions. However, four of seven brands of SHCLs absorbed the cosmetic cleansing oil under both conditions (dry and wet), whereas asmofilcon A absorbed it only under the dry condition. Lotrafilcon B and delefilcon A did not absorb cleansing oil even under the dry condition. Hydrogel lenses resist cosmetic cleansing oil. However, SHCLs have different degrees of resistance depending on the lens material. Some SHCLs absorbed cosmetic cleansing oil more under dry conditions than under wet conditions.

Contact point generation for convex polytopes in interactive rigid body dynamics

DEFF Research Database (Denmark)

Silcowitz-Hansen, Morten; Abel, Sarah Maria Niebe; Erleben, Kenny

When computing contact forces in rigid body dynamics systems, most state-of-the-art solutions use iterative methods such as the projected Gauss–Seidel (PGS) method. Methods such as the PGS method are preferred for their robustness. However, the time-critical nature of interactive applications...... combined with the linear convergence rates of such methods, will often result in visual artifacts in the final simulation. With this paper, we address an issue which is of major impact on the animation quality, when using methods such as the PGS method. The issue is robust generation of contact points...... for convex polytopes. A novel contact point generation method is presented, which is based on growth distances and Gauss maps. We demonstrate improvements when using our method in the context of interactive rigid body simulation...

Ultra-low contact resistance in graphene devices at the Dirac point

Science.gov (United States)

Anzi, Luca; Mansouri, Aida; Pedrinazzi, Paolo; Guerriero, Erica; Fiocco, Marco; Pesquera, Amaia; Centeno, Alba; Zurutuza, Amaia; Behnam, Ashkan; Carrion, Enrique A.; Pop, Eric; Sordan, Roman

2018-04-01

Contact resistance is one of the main factors limiting performance of short-channel graphene field-effect transistors (GFETs), preventing their use in low-voltage applications. Here we investigated the contact resistance between graphene grown by chemical vapor deposition (CVD) and different metals, and found that etching holes in graphene below the contacts consistently reduced the contact resistance, down to 23 Ω \\cdot μ m with Au contacts. This low contact resistance was obtained at the Dirac point of graphene, in contrast to previous studies where the lowest contact resistance was obtained at the highest carrier density in graphene (here 200 Ω \\cdot μ m was obtained under such conditions). The ‘holey’ Au contacts were implemented in GFETs which exhibited an average transconductance of 940 S m-1 at a drain bias of only 0.8 V and gate length of 500 nm, which out-perform GFETs with conventional Au contacts.

Elastic-plastic adhesive contact of rough surfaces using n-point asperity model

International Nuclear Information System (INIS)

Sahoo, Prasanta; Mitra, Anirban; Saha, Kashinath

2009-01-01

This study considers an analysis of the elastic-plastic contact of rough surfaces in the presence of adhesion using an n-point asperity model. The multiple-point asperity model, developed by Hariri et al (2006 Trans ASME: J. Tribol. 128 505-14) is integrated into the elastic-plastic adhesive contact model developed by Roy Chowdhury and Ghosh (1994 Wear 174 9-19). This n-point asperity model differs from the conventional Greenwood and Williamson model (1966 Proc. R. Soc. Lond. A 295 300-19) in considering the asperities not as fixed entities but as those that change through the contact process, and hence it represents the asperities in a more realistic manner. The newly defined adhesion index and plasticity index defined for the n-point asperity model are used to consider the different conditions that arise because of varying load, surface and material parameters. A comparison between the load-separation behaviour of the new model and the conventional one shows a significant difference between the two depending on combinations of mean separation, adhesion index and plasticity index.

Two-point concrete resistivity measurements: interfacial phenomena at the electrode–concrete contact zone

International Nuclear Information System (INIS)

McCarter, W J; Taha, H M; Suryanto, B; Starrs, G

2015-01-01

Ac impedance spectroscopy measurements are used to critically examine the end-to-end (two-point) testing technique employed in evaluating the bulk electrical resistivity of concrete. In particular, this paper focusses on the interfacial contact region between the electrode and specimen and the influence of contacting medium and measurement frequency on the impedance response. Two-point and four-point electrode configurations were compared and modelling of the impedance response was undertaken to identify and quantify the contribution of the electrode–specimen contact region on the measured impedance. Measurements are presented in both Bode and Nyquist formats to aid interpretation. Concretes mixes conforming to BSEN206-1 and BS8500-1 were investigated which included concretes containing the supplementary cementitious materials fly ash and ground granulated blast-furnace slag. A measurement protocol is presented for the end-to-end technique in terms of test frequency and electrode–specimen contacting medium in order to minimize electrode–specimen interfacial effect and ensure correct measurement of bulk resistivity. (paper)

Development of method for experimental determination of wheel–rail contact forces and contact point position by using instrumented wheelset

International Nuclear Information System (INIS)

Bižić, Milan B; Petrović, Dragan Z; Tomić, Miloš C; Djinović, Zoran V

2017-01-01

This paper presents the development of a unique method for experimental determination of wheel–rail contact forces and contact point position by using the instrumented wheelset (IWS). Solutions of key problems in the development of IWS are proposed, such as the determination of optimal locations, layout, number and way of connecting strain gauges as well as the development of an inverse identification algorithm (IIA). The base for the solution of these problems is the wheel model and results of FEM calculations, while IIA is based on the method of blind source separation using independent component analysis. In the first phase, the developed method was tested on a wheel model and a high accuracy was obtained (deviations of parameters obtained with IIA and really applied parameters in the model are less than 2%). In the second phase, experimental tests on the real object or IWS were carried out. The signal-to-noise ratio was identified as the main influential parameter on the measurement accuracy. Тhе obtained results have shown that the developed method enables measurement of vertical and lateral wheel–rail contact forces Q and Y and their ratio Y / Q with estimated errors of less than 10%, while the estimated measurement error of contact point position is less than 15%. At flange contact and higher values of ratio Y / Q or Y force, the measurement errors are reduced, which is extremely important for the reliability and quality of experimental tests of safety against derailment of railway vehicles according to the standards UIC 518 and EN 14363. The obtained results have shown that the proposed method can be successfully applied in solving the problem of high accuracy measurement of wheel–rail contact forces and contact point position using IWS. (paper)

A Study on the Effect of the Contact Point and the Contact Force of a Glass Fiber under End-Face Polishing Process

Directory of Open Access Journals (Sweden)

Ying-Chien Tsai

2015-01-01

Full Text Available The offset between the center lines of the polished end-face and the fiber core has a significant effect on coupling efficiency. The initial contact point and the contact force are two of the most important parameters that induce the offset. This study proposes an image assistant method to find the initial contact point and a mathematical model to estimate the contact force when fabricating the double-variable-curvature end-face of single mode glass fiber. The repeatability of finding the initial contact point via the vision assistant program is 0.3 μm. Based on the assumption of a large deflection, a mathematical model is developed to study the relationship between the contact force and the displacement of the lapping film. In order to verify the feasibility of the mathematical model, experiments, as well as DEFORM simulations, are carried out. The results show that the contact forces are alomst linearly proportional to the feed amounts of the lapping film and the errors are less than 9%. By using the method developed in this study, the offset between the grinding end-face and the center line of the fiber core is within 0.15 to 0.35 μm.

Superconducting Sweet-Spot in Microcrystalline Graphite Revealed by Point-Contact Spectroscopy

Science.gov (United States)

Arnold, F.; Nyéki, J.; Saunders, J.

2018-05-01

In this letter we describe the observation of a magnetic field dependent electronic gap, suggestive of local superconductivity, in the point-contact spectrum of micro-crystalline graphite. Magnetic field dependent point-contact spectroscopy was carried out at a temperature of 1.8K using an etched aluminium tip. At zero field a gap structure in the differential conductance is observed, showing a gap of Δ = 4.2 meV. On applying magnetic fields of up to 500mT, this gap gradually closes, following the theoretical prediction by Ginzburg and Landau for a fully flux-penetrated superconductor. By applying BCS-theory, we infer a critical superconducting temperature of 14K.

CDEX-1 1 kg point-contact germanium detector for low mass dark matter searches

International Nuclear Information System (INIS)

Kang Kejun; Yue Qian; Wu Yucheng

2013-01-01

The CDEX collaboration has been established for direct detection of light dark matter particles, using ultra-low energy threshold point-contact p-type germanium detectors, in China JinPing underground Laboratory (CJPL). The first 1 kg point-contact germanium detector with a sub-keV energy threshold has been tested in a passive shielding system located in CJPL. The outputs from both the point-contact P + electrode and the outside N + electrode make it possible to scan the lower energy range of less than 1 keV and at the same time to detect the higher energy range up to 3 MeV. The outputs from both P + and N + electrode may also provide a more powerful method for signal discrimination for dark matter experiment. Some key parameters, including energy resolution, dead time, decay times of internal X-rays, and system stability, have been tested and measured. The results show that the 1 kg point-contact germanium detector, together with its shielding system and electronics, can run smoothly with good performances. This detector system will be deployed for dark matter search experiments. (authors)

The Effect of Contact Angle on Dynamics of Dry Spots Spreading in a Horizontal Layer of Liquid at Local Heating

Directory of Open Access Journals (Sweden)

Zaitsev D.V.

2015-01-01

Full Text Available The effect of equilibrium contact angle on dynamics of dry spot spreading at disruption of a horizontal water layer heated locally from the substrate was studied using the high-speed Schlieren technique. Different methods of working surface processing were applied; this allowed variations of the equilibrium contact angle from 27±6° to 74±9° without a change in thermal properties of the system. It is found out that substrate wettability significantly affects the propagation velocity of dry spot and its final size. It is also found out that the velocity of contact line propagation is higher in the areas of substrate with a higher temperature.

Aluminum break-point contacts

NARCIS (Netherlands)

Heinemann, Martina; Groot, R.A. de

1997-01-01

Ab initio molecular dynamics is used to study the contribution of a single Al atom to an aluminum breakpoint contact during the final stages of breaking and the initial stages of the formation of such a contact. A hysteresis effect is found in excellent agreement with experiment and the form of the

Atlas of point contact spectra of electron-phonon interactions in metals

CERN Document Server

Khotkevich, A V

1995-01-01

The characteristics of electrical contacts have long attracted the attention of researchers since these contacts are used in every electrical and electronic device. Earlier studies generally considered electrical contacts of large dimensions, having regions of current concentration with diameters substantially larger than the characteristic dimensions of the material: the interatomic distance, the mean free path for electrons, the coherence length in the superconducting state, etc. [110]. The development of microelectronics presented to scientists and engineers the task of studying the characteristics of electrical contacts with ultra-small dimensions. Characteristics of point contacts such as mechanical stability under continuous current loads, the magnitudes of electrical fluctuations, inherent sensitivity in radio devices and nonlinear characteristics in connection with electromagnetic radiation can not be understood and altered in the required way without knowledge of the physical processes occurring in c...

Current-voltage curves of gold quantum point contacts revisited

DEFF Research Database (Denmark)

Hansen, K.; Nielsen, S K.; Brandbyge, Mads

2000-01-01

We present measurements of current-voltage (I-V) curves on gold quantum point contacts (QPCs) with a conductance up to 4 G(0) (G(0) = 2e(2)/h is the conductance quantum) and voltages up to 2 V. The QPCs are formed between the gold tip of a scanning tunneling microscope and a Au(110) surface under...

Point-contact spectroscopy of unsaturates oxides of transition metals and the problem of zero anomalies

International Nuclear Information System (INIS)

Tulina, N.A.

1985-01-01

A study was made of point-contact spectra of oxides WO 2 , ReO 3 , MoO 2 with metallic conductivity. It is shown that zero anomalies often observed in transition metal spectra are due to a higher-type oxide interlayer in the vicinity of a point contact. There are no zero anomalies in the point-contact spectra of heterocontacts Zn-MoO 2 (broken crystal) obtained directly in a helium cryostal. When studying such heterocontacts, major maxima of electron- phonon interaction in MoO 2 were determined on the energy scale hω sub(TA) approximately 28 MeV, hω sub(LA) approximately 41 MeV

A sliding point contact model for the finite element structures code EURDYN

International Nuclear Information System (INIS)

Smith, B.L.

1986-01-01

A method is developed by which sliding point contact between two moving deformable structures may be incorporated within a lumped mass finite element formulation based on displacements. The method relies on a simple mechanical interpretation of the contact constraint in terms of equivalent nodal forces and avoids the use of nodal connectivity via a master slave arrangement or pseudo contact element. The methodology has been iplemented into the EURDYN finite element program for the (2D axisymmetric) version coupled to the hydro code SEURBNUK. Sample calculations are presented illustrating the use of the model in various contact situations. Effects due to separation and impact of structures are also included. (author)

Effects of contact cap dimension on dry adhesion of bioinspired mushroom-shaped surfaces

Science.gov (United States)

Wang, Yue; Shao, Jinyou; Ding, Yucheng; Li, Xiangming; Tian, Hongmiao; Hu, Hong

2015-03-01

Dry adhesion observed in small creatures, such as spiders, insects, and geckos, has many great advantages such as repeatability and strong adhesiveness. In order to mimic these unique performances, fibrillar surface with a mushroom shaped end has drawn lots of attentions because of its advantage in efficiently enhancing adhesion compared with other sphere or simple flat ends. Here, in order to study the effects of contact cap dimension on adhesion strength, patterned surfaces of mushroom-shaped micropillars with differing cap diameters are fabricated based on the conventional photolithography and molding. The normal adhesion strength of these dry adhesives with varying cap diameters is measured with home-built equipment. The strength increases with the rise of cap diameter, and interestingly it becomes strongest when the mushroom caps join together.

Capacitance and conductance of mesoscopic systems connected by quantum point contacts

DEFF Research Database (Denmark)

Flensberg, Karsten

1993-01-01

We study the transport properties of quantum dots and quantum point contacts in the Coulomb blockade regime and in the limit where the quantum point contact has nearly fully transmitting channels. Using a transformation to a multichannel Tomonaga-Luttinger-type model, we find the scaling behavior...... of the junction close to pinchoff. It is shown that the junction scales to an insulating junction. We find a crossover between a low-temperature regime with Coulomb blockade to a high-temperature regime where the quantum charge fluctuations are dominant. The crossover temperature between these regimes is given...... by Tc∼U[1-G0/NGH]N/2, where U are the bare charging energy, G0 is the nominal conductance, N is the number of channels, and GH=e2/h....

Point-contact spectroscopy of unsaturated transition-metal oxides and the problem of zero-bias anomalies

International Nuclear Information System (INIS)

Tulina, N.A.

1985-01-01

The point-contact spectra of oxides with metallic conductivity WO 2 , ReO 3 , and MoO 2 are studied. It is shown that the zero-bias anomalies, which are often observed in the spectra of transition metals, are determined by the presence of an interlayer consisting of an oxide of the above type in the region of the point contact. Zero-bias anomalies do not occur in the point-contact spectra of Zn--MoO 2 -chip heterocontacts. In the studies of such heterocontacts the major maxima in the electron--phonon interaction of MoO 2 were determined at the energies hω/sub T/Aapprox.28 meV and hω/sub L/Aapprox.41 meV

Performance of mechanically shaken indirect contact atmospheric dryer in drying pastelike materials

Directory of Open Access Journals (Sweden)

K. P. Melo

2004-09-01

Full Text Available Pastelike materials are encountered in many technological processes in chemical, pharmaceutical, foodstuff and natural product industries. The most important factor in the drying of this type of materials is the nature of the moisture bonding that occurs. Because of the different characteristics of pastes, it is impossible to recommend a universal type of dryer for all of these materials. Some of the dryers available provide only indirect contact with the drying agent (heat and also maintain constant moisture with a system of rotating paddles. We evaluated the performance of this type by studying the dryer kinetics curves for ground coffee under a variety of operational conditions of moisture load of material, temperature of the heating plate, intensity of the mechanical mixing of the moisture material, and initial moisture. The effects of these parameters (except for moisture were studied using a 2³ factorial design. According the analyses of the kinetics drying curves, was observed that the increase in the temperature of the plate and rotation as well as the decrease in the load facilitates more effective removal of moisture. In statistical analysis was determined that the load of the material and the heating plate temperature influence the final moisture content of the material and plate temperature modifies the final temperature of the solid. Also, was suggested linear models from the factorial design to describe the process of drying coffee grounds satisfactorily.

Elastohydrodynamic lubrication in point contact on the surfaces of particle-reinforced composite

Science.gov (United States)

Chen, Keying; Zeng, Liangcai; Wu, Zhenpeng; Zheng, Feilong

2018-04-01

Appreciable friction and serious wear are common challenges in the operation of advanced manufacturing equipment, and friction pairs may be susceptible to damage even with oil lubrication when point contact exists. In this study, a type of particle-reinforced composite material is introduced for one of the components of a heavy-load contact pair, and the performance improvement of elastohydrodynamic lubrication (EHL) is analyzed considering the rheological properties of non-Newtonian fluids. The Ree-Eyring EHL model is used considering the surface of the particle-reinforced composite, in which the film thickness includes the particle-induced elastic deformation. The problem of inclusions with different eigenstrains is solved by using Galerkin vectors. The influences of particle properties, size, burial depth, and interparticle distance on point-contact EHL are investigated. Furthermore, using several cases, the structural parameters of the particles in the composites are optimized, and an appropriate parameter range is obtained with the goal of reducing friction. Finally, the results for the EHL traction coefficient demonstrate that appropriate particle properties, size, burial depth, and interparticle distance can effectively reduce the traction coefficient in heavy-load contact.

Pb induces superconductivity in Bi2Se3 analyzed by point contact spectroscopy

OpenAIRE

Arevalo-López, P.; López-Romero, R. E.; Escudero, R.

2015-01-01

Some topological insulators become superconducting when doped with Cu and Pd. Superconductivity in a non-superconductor may be induced by proximity effect: i.e. Contacting a non-superconductor with a superconductor. The superconducting macroscopic wave function will induce electronic pairing into the normal compound. In the simplest topological insulator, Bi$_2$Se$_3$, superconductivity may be induced with Pb. We studied with point contact junctions formed by contacting Bi$_2$Se$_3$ crystals ...

Nanostructural point-contact sensors for diagnostics of carcinogenic strains of Helicobacter pylori

Directory of Open Access Journals (Sweden)

Г. В. Камарчук

2017-12-01

Full Text Available Background: The problem of detecting the different strains of H. pylori has gained great importance today due to the worldwide prevalence of this bacterium and its role in the pathogenesis of a number of serious gastric and extragastric diseases. However, not all H. pylori strains are aggressive and require antibiotic treatment. Thus, the question arises about the necessity of differentiating these bacterium strains with respect to their virulence factors. In accordance with the IV Maastricht Consensus Report, among the variety of ways to diagnose H. pylori infection, non-invasive methods should be given preference. Most of them are based on the analysis of gas which is exhaled by a human. Mass spectrometry, gas chromatography, and IR spectroscopy are currently the mostly used ones. However, despite the obvious advantages, these techniques have a number of disadvantages that make them difficult to use in everyday medical practice. Modern sensor devices can become an inexpensive and easy to access alternative to these technologies. Objectives: The aim of the work is to develop a new type of sensor device for selective recognition of H. pylori strains which is based on analysis of a mixture of gases exhaled by human. Such a kind of device can be designed on the basis of a point-contact gas sensor. Materials and methods: Anion-radical salts of the organic conductor TCNQ were chosen as the sensitive material for point-contact sensors. The fundamental properties of point contacts which are used in the Yanson point-contact spectroscopy make it possible to create a point-contact mesoscopic matrix on the basis of this material, which is sensitive to small concentrations of components in complex gas media. The sensors were obtained by electrochemical deposition of salts from a solvent characterized by a high vapor pressure on a textolite substrate. Gas exhaled by a human served as the substance to be analyzed. The measurements were carried out following

Design and construction of a point-contact spectroscopy rig with lateral scanning capability

Energy Technology Data Exchange (ETDEWEB)

Tortello, M. [Dipartimento di Scienza Applicata e Tecnologia, Politecnico di Torino, Torino 10129 (Italy); Park, W. K., E-mail: wkpark@illinois.edu; Ascencio, C. O.; Saraf, P.; Greene, L. H. [Department of Physics and Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)

2016-06-15

The design and realization of a cryogenic rig for point-contact spectroscopy measurements in the needle-anvil configuration is presented. Thanks to the use of two piezoelectric nano-positioners, the tip can move along the vertical (z) and horizontal (x) direction and thus the rig is suitable to probe different regions of a sample in situ. Moreover, it can also form double point-contacts on different facets of a single crystal for achieving, e.g., an interferometer configuration for phase-sensitive measurements. For the later purpose, the sample holder can also host a Helmholtz coil for applying a small transverse magnetic field to the junction. A semi-rigid coaxial cable can be easily added for studying the behavior of Josephson junctions under microwave irradiation. The rig can be detached from the probe and thus used with different cryostats. The performance of this new probe has been tested in a Quantum Design PPMS system by conducting point-contact Andreev reflection measurements on Nb thin films over large areas as a function of temperature and magnetic field.

Dynamic nuclear polarization at high Landau levels in a quantum point contact

Science.gov (United States)

Fauzi, M. H.; Noorhidayati, A.; Sahdan, M. F.; Sato, K.; Nagase, K.; Hirayama, Y.

2018-05-01

We demonstrate a way to polarize and detect nuclear spin in a gate-defined quantum point contact operating at high Landau levels. Resistively detected nuclear magnetic resonance (RDNMR) can be achieved up to the fifth Landau level and at a magnetic field lower than 1 T. We are able to retain the RDNMR signals in a condition where the spin degeneracy of the first one-dimensional (1D) subband is still preserved. Furthermore, the effects of orbital motion on the first 1D subband can be made smaller than those due to electrostatic confinement. This developed RDNMR technique is a promising means to study electronic states in a quantum point contact near zero magnetic field.

Thermomechanical behavior of dry contacts in disc brake rotor with a grey cast iron composition

Directory of Open Access Journals (Sweden)

Belhocine Ali

2013-01-01

Full Text Available The main purpose of this study is to analysis the thermomechanical behavior of the dry contact between the brake disc and pads during the braking phase. The simulation strategy is based on the calculation code ANSYS11. The modeling of transient temperature in the disk is actually used to identify the factor of geometric design of the disk to install the ventilation system in vehicles. The thermal-structural analysis is then used coupling to determine the deformation established and the Von Mises stresses in the disk, the contact pressure distribution in pads. The results are satisfactory compared to those found in the literature.

Pecan drying with silica gel

Energy Technology Data Exchange (ETDEWEB)

Ghate, S.R.; Chhinnan, M.S.

1983-07-01

High moisture in-shell pecans were dried by keeping them in direct and indirect contact with silica gel to investigate their drying characteristics. In-shell pecans were also dried with ambient air from a controlled environment chamber and with air dehumidified by silica gel. Direct contact and dehumidified air drying seemed feasible approaches.

A novel in-vitro method for assessing contact lens surface dewetting: Non-invasive keratograph dry-up time (NIK-DUT).

Science.gov (United States)

Marx, Sebastian; Sickenberger, Wolfgang

2017-12-01

This study was designed to develop a novel technique called non-invasive keratograph dry-up time (NIK-DUT), which used an adapted corneal topographer, to analyse in-vitro contact lens surface dewetting and the effects of combinations of lenses and lens care solutions on dewetting. Variables were assessed to optimise sensitivity and reproducibility. To validate the method, in-vitro dewetting of silicone hydrogel contact lenses (balafilcon A, comfilcon A, lotrafilcon A, lotrafilcon B and senofilcon A) was tested. All lens types were soaked in OPTI-FREE ® PureMoist ® Multipurpose Disinfecting Solution (OFPM) and Sensitive Eyes ® Saline Solution. The mean NIK-DUT, defined as drying of 25% of the placido ring measurement segments (NIK-DUT_S25), was calculated for each lens/lens solution combination and a visual map constructed representing the time and location of the dry-up event. Optimal conditions for NIK-DUT measurement included mounting onto a glass stage with a surface geometry of r=8.5mm, e=0, and measuring with high intensity red or white illumination. This method detected significant differences in contact lens dewetting with different lens soaking solutions. NIK-DUT_S25 for all lenses was longer when pre-soaked in OFPM versus saline. Visual analysis showed that dewetting of contact lenses was not uniform across surfaces and differed between test solutions. NIK-DUT is suitable for detecting differences in dewetting among various contact lenses and lens-care combinations. NIK-DUT can quantify the dewetting of large areas of lens surfaces with little subjective influence. Lens care solutions containing surface-active wetting agents were found to delay surface dewetting of silicone hydrogel lenses. Copyright © 2017. Published by Elsevier Ltd.

Modular correction method of bending elastic modulus based on sliding behavior of contact point

International Nuclear Information System (INIS)

Ma, Zhichao; Zhao, Hongwei; Zhang, Qixun; Liu, Changyi

2015-01-01

During the three-point bending test, the sliding behavior of the contact point between the specimen and supports was observed, the sliding behavior was verified to affect the measurements of both deflection and span length, which directly affect the calculation of the bending elastic modulus. Based on the Hertz formula to calculate the elastic contact deformation and the theoretical calculation of the sliding behavior of the contact point, a theoretical model to precisely describe the deflection and span length as a function of bending load was established. Moreover, a modular correction method of bending elastic modulus was proposed, via the comparison between the corrected elastic modulus of three materials (H63 copper–zinc alloy, AZ31B magnesium alloy and 2026 aluminum alloy) and the standard modulus obtained from standard uniaxial tensile tests, the universal feasibility of the proposed correction method was verified. Also, the ratio of corrected to raw elastic modulus presented a monotonically decreasing tendency as the raw elastic modulus of materials increased. (technical note)

Design, simulation and fabrication of a novel contact-enhanced MEMS inertial switch with a movable contact point

International Nuclear Information System (INIS)

Cai Haogang; Ding Guifu; Yang Zhuoqing; Su Zhijuan; Zhou Jiansheng; Wang Hong

2008-01-01

A novel inertial switch based on a micro-electro-mechanical system (MEMS) was designed, which consists of three main parts: a proof mass as the movable electrode, a cross beam as the stationary electrode and a movable contact point to prolong the contact time. A MATLAB/Simulink model, which had been verified by comparison with ANSYS transient simulation, was built to simulate the dynamic response, based on which the contact-enhancing mechanism was confirmed and the dependence of threshold acceleration on the proof mass thickness was studied. The simulated dynamic responses under various accelerations exhibit satisfactory device behaviors: the switch-on time is prolonged under transient acceleration; the switch-on state is more continuous than the conventional design under long lasting acceleration. The inertial micro-switch was fabricated by multilayer electroplating technology and then tested by a drop hammer experiment. The test results indicate that the contact effect was improved significantly and a steady switch-on time of over 50 µs was observed under half-sine wave acceleration with 1 ms duration, in agreement with the dynamic simulation

Point contacts at the copper-indium-gallium-selenide interface—A theoretical outlook

Energy Technology Data Exchange (ETDEWEB)

Bercegol, Adrien, E-mail: adrien.bercegol@polytechnique.edu; Chacko, Binoy; Klenk, Reiner; Lauermann, Iver; Lux-Steiner, Martha Ch. [Helmholtz-Zentrum Berlin für Materialien und Energie, Albert Einstein Straße 15, 12489 Berlin (Germany); Liero, Matthias [Weierstraß-Institut für Angewandte Analysis und Stochastik, 10117 Berlin (Germany)

2016-04-21

For a long time, it has been assumed that recombination in the space-charge region of copper-indium-gallium-selenide (CIGS) is dominant, at least in high efficiency solar cells with low band gap. The recent developments like potassium fluoride post deposition treatment and point-contact junction may call this into question. In this work, a theoretical outlook is made using three-dimensional simulations to investigate the effect of point-contact openings through a passivation layer on CIGS solar cell performance. A large set of solar cells is modeled under different scenarios for the charged defect levels and density, radius of the openings, interface quality, and conduction band offset. The positive surface charge created by the passivation layer induces band bending and this influences the contact (CdS) properties, making it beneficial for the open circuit voltage and efficiency, and the effect is even more pronounced when coverage area is more than 95%, and also makes a positive impact on the device performance, even in the presence of a spike at CIGS/CdS heterojunction.

Pairwise contact energy statistical potentials can help to find probability of point mutations.

Science.gov (United States)

Saravanan, K M; Suvaithenamudhan, S; Parthasarathy, S; Selvaraj, S

2017-01-01

To adopt a particular fold, a protein requires several interactions between its amino acid residues. The energetic contribution of these residue-residue interactions can be approximated by extracting statistical potentials from known high resolution structures. Several methods based on statistical potentials extracted from unrelated proteins are found to make a better prediction of probability of point mutations. We postulate that the statistical potentials extracted from known structures of similar folds with varying sequence identity can be a powerful tool to examine probability of point mutation. By keeping this in mind, we have derived pairwise residue and atomic contact energy potentials for the different functional families that adopt the (α/β) 8 TIM-Barrel fold. We carried out computational point mutations at various conserved residue positions in yeast Triose phosphate isomerase enzyme for which experimental results are already reported. We have also performed molecular dynamics simulations on a subset of point mutants to make a comparative study. The difference in pairwise residue and atomic contact energy of wildtype and various point mutations reveals probability of mutations at a particular position. Interestingly, we found that our computational prediction agrees with the experimental studies of Silverman et al. (Proc Natl Acad Sci 2001;98:3092-3097) and perform better prediction than i Mutant and Cologne University Protein Stability Analysis Tool. The present work thus suggests deriving pairwise contact energy potentials and molecular dynamics simulations of functionally important folds could help us to predict probability of point mutations which may ultimately reduce the time and cost of mutation experiments. Proteins 2016; 85:54-64. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Inactivation of Escherichia coli O157:H7 in biofilm on food-contact surfaces by sequential treatments of aqueous chlorine dioxide and drying.

Science.gov (United States)

Bang, Jihyun; Hong, Ayoung; Kim, Hoikyung; Beuchat, Larry R; Rhee, Min Suk; Kim, Younghoon; Ryu, Jee-Hoon

2014-11-17

We investigated the efficacy of sequential treatments of aqueous chlorine and chlorine dioxide and drying in killing Escherichia coli O157:H7 in biofilms formed on stainless steel, glass, plastic, and wooden surfaces. Cells attached to and formed a biofilm on wooden surfaces at significantly (P ≤ 0.05) higher levels compared with other surface types. The lethal activities of sodium hypochlorite (NaOCl) and aqueous chlorine dioxide (ClO₂) against E. coli O157:H7 in a biofilm on various food-contact surfaces were compared. Chlorine dioxide generally showed greater lethal activity than NaOCl against E. coli O157:H7 in a biofilm on the same type of surface. The resistance of E. coli O157:H7 to both sanitizers increased in the order of wood>plastic>glass>stainless steel. The synergistic lethal effects of sequential ClO₂ and drying treatments on E. coli O157:H7 in a biofilm on wooden surfaces were evaluated. When wooden surfaces harboring E. coli O157:H7 biofilm were treated with ClO₂ (200 μg/ml, 10 min), rinsed with water, and subsequently dried at 43% relative humidity and 22 °C, the number of E. coli O157:H7 on the surface decreased by an additional 6.4 CFU/coupon within 6 h of drying. However, when the wooden surface was treated with water or NaOCl and dried under the same conditions, the pathogen decreased by only 0.4 or 1.0 log CFU/coupon, respectively, after 12 h of drying. This indicates that ClO₂ treatment of food-contact surfaces results in residual lethality to E. coli O157:H7 during the drying process. These observations will be useful when selecting an appropriate type of food-contact surfaces, determining a proper sanitizer for decontamination, and designing an effective sanitization program to eliminate E. coli O157:H7 on food-contact surfaces in food processing, distribution, and preparation environments. Copyright © 2014 Elsevier B.V. All rights reserved.

Peltier Coefficient and Photon-Assisted Tunnelling in Quantum Point Contact

International Nuclear Information System (INIS)

Arafa, H. Aly

2008-01-01

We present the Peltier coefficient and thermal transport in quantum point contact (QPC), under the influence of external fields and different temperatures. Also we obtain the oscillations of the Peltier coefficient in external fields. Numerical calculations of the Peltier coefficient are performed at different applied voltages, amplitudes and temperatures. The obtained results are consistent with the experimental data in the literature

Knee medial and lateral contact forces in a musculoskeletal model with subject-specific contact point trajectories.

Science.gov (United States)

Zeighami, A; Aissaoui, R; Dumas, R

2018-03-01

Contact point (CP) trajectory is a crucial parameter in estimating medial/lateral tibio-femoral contact forces from the musculoskeletal (MSK) models. The objective of the present study was to develop a method to incorporate the subject-specific CP trajectories into the MSK model. Ten healthy subjects performed 45 s treadmill gait trials. The subject-specific CP trajectories were constructed on the tibia and femur as a function of extension-flexion using low-dose bi-plane X-ray images during a quasi-static squat. At each extension-flexion position, the tibia and femur CPs were superimposed in the three directions on the medial side, and in the anterior-posterior and proximal-distal directions on the lateral side to form the five kinematic constraints of the knee joint. The Lagrange multipliers associated to these constraints directly yielded the medial/lateral contact forces. The results from the personalized CP trajectory model were compared against the linear CP trajectory and sphere-on-plane CP trajectory models which were adapted from the commonly used MSK models. Changing the CP trajectory had a remarkable impact on the knee kinematics and changed the medial and lateral contact forces by 1.03 BW and 0.65 BW respectively, in certain subjects. The direction and magnitude of the medial/lateral contact force were highly variable among the subjects and the medial-lateral shift of the CPs alone could not determine the increase/decrease pattern of the contact forces. The suggested kinematic constraints are adaptable to the CP trajectories derived from a variety of joint models and those experimentally measured from the 3D imaging techniques. Copyright © 2018 Elsevier Ltd. All rights reserved.

Data analysis strategies for the characterization of normal: superconductor point contacts by barrier strength parameter

Science.gov (United States)

Smith, Charles W.; Reinertson, Randal C.; Dolan, P. J., Jr.

1993-05-01

The theoretical description by Blonder, Tinkham, and Klapwijk [Phys. Rev. B 25, 4515 (1982)] of the I-V curves of normal: superconductor point contacts encompasses a broad range of experimental behavior, from the tunnel junction case, on the one hand, to the clean metallic microconstriction limit on the other. The theory characterizes point contacts in terms of a single parameter, the barrier strength. The differential conductance of a point contact, at zero bias, as a function of temperature, offers a direct experimental method by which the barrier strength parameter can be evaluated. In view of the full range of phenomena incorporated by this theory, we suggest several different strategies for the evaluation of the barrier strength parameter from data in the low and intermediate barrier strength regimes and for measurements in the low temperature (near T=0 K) and high temperature (near T=Tc) limits.

Superconducting energy gap of YB6 studied by point-contact spectroscopy

International Nuclear Information System (INIS)

Szabo, Pavol; Kacmarcik, Jozef; Samuely, Peter; Girovsky, Jan; Gabani, Slavomir; Flachbart, Karol; Mori, Takao

2007-01-01

Yttrium hexaboride has the second highest critical temperature, T c ∼ 8 K, among all borides. The presented paper deals with the experimental study of its superconducting energy gap established by the method of the point-contact spectroscopy. The temperature dependence of the energy gap and the strength of the superconducting coupling is presented

Subharmonic energy-gap structure and heating effects in superconducting niobium point contacts

DEFF Research Database (Denmark)

Flensberg, K.; Hansen, Jørn Bindslev

1989-01-01

We present experimental data of the temperature-dependent subharmonic energy-gap structure (SGS) in the current-voltage (I-V) curves of superconducting niobium point contacts. The observed SGS is modified by heating effects. We construct a model of the quasiparticle conductance of metallic...

New directions in point-contact spectroscopy based on scanning tunneling microscopy techniques (Review Article)

International Nuclear Information System (INIS)

Tartaglini, E.; Verhagen, T.G.A.; Galli, F.; Trouwborst, M.L.; Aarts, J.; Van-Ruitebbeek, J.M.; Muller, R.; Shiota, T.

2013-01-01

Igor Yanson showed 38 years ago for the first time a point-contact measurement where he probed the energy resolved spectroscopy of the electronic scattering inside the metal. Since this first measurement, the pointcontact spectroscopy (PCS) technique improved enormously. The application of the scanning probe microscopy (SPM) techniques in the late 1980s allowed achieving contacts with a diameter of a single atom. With the introduction of the mechanically controlled break junction technique, even spectroscopy on freely suspended chains of atoms could be performed. In this paper, we briefly review the current developments of PCS and show recent experiments in advanced scanning PCS based on SPM techniques. We describe some results obtained with both needle-anvil type of point contacts and scanning tunneling microscopy (STM). We also show our first attempt to lift up with a STM a chain of single gold atoms from a Au(110) surface.

Graphene-based superconducting quantum point contacts

International Nuclear Information System (INIS)

Moghaddam, A.G.; Zareyan, M.

2007-01-01

We investigate the Josephson effect in the graphene nanoribbons of length L smaller than the superconducting coherence length and an arbitrary width W. We find that in contrast to an ordinary superconducting quantum point contact (SQPC), the critical supercurrent I c is not quantized for the nanoribbons with smooth and armchair edges. For a low concentration of the carriers, I c decreases monotonically with lowering W/L and tends to a constant minimum for a narrow nanoribbon with W c is zero for the smooth edges but eΔ 0 /ℎ for the armchair edges. At higher concentrations of the carriers this monotonic variation acquires a series of peaks. Further analysis of the current-phase relation and the Josephson coupling strength I c R N in terms of W/L and the concentration of carriers revels significant differences with those of an ordinary SQPC. On the other hand for a zigzag nanoribbon, we find that, similar to an ordinary SQPC, I c is quantized but to the half-integer values (n+1/2)4eΔ 0 /ℎ. (orig.)

Contact angle change during evaporation of near-critical liquids

Science.gov (United States)

Nikolayev, Vadim; Hegseth, John; Beysens, Daniel

1998-11-01

An unexpected change of the dynamic contact angle was recently observed in a near-critical liquid-gas system in a space experiment. While the near-critical liquid completely wets a solid under equilibrium conditions, the apparent contact angle changed from 0^circ to about 120^circ during evaporation. We propose an explanation for this phenomenon by taking into account vapor recoil due to evaporation (motion of the vapor from the free liquid surface). This force is normal to the vapor-liquid interface and is directed towards the liquid. It increases sharply near the triple contact line. Near the critical point, where the surface tension force is very weak, the vapor recoil force can be important enough to change the apparent contact angle. A similar effect can also explain the drying of a heater during boiling at high heat flux. The drying greatly reduces the heat transfer to the liquid causing the heater to melt. This phenomenon is called ``boiling crisis", ``burnout" or ``Departure from Nuclear Boiling". We report the preliminary results of the numerical simulation of the liquid evaporation by the Boundary Element method.

32 CFR Appendix B to Part 290 - DCAA's FOIA Points of Contact

Science.gov (United States)

2010-07-01

... (CONTINUED) FREEDOM OF INFORMATION ACT PROGRAM DEFENSE CONTRACT AUDIT AGENCY (DCAA) FREEDOM OF INFORMATION ACT PROGRAM Pt. 290, App. B Appendix B to Part 290—DCAA's FOIA Points of Contact (Regional Offices.... Pacific Ocean and Asian Islands. Asia except the Middle East. Australia. Georgia DCAA Eastern Regional...

Search for Superconducting Energy Gap in UPt3 by Point-Contact Spectroscopy

International Nuclear Information System (INIS)

Gouchi, Jun; Sumiyama, Akihiko; Yamaguchi, Akira; Motoyama, Gaku; Kimura, Noriaki; Yamamoto, Etsuji; Haga, Yoshinori; Ōnuki, Yoshichika

2015-01-01

We have investigated the differential resistance of the point contacts between heavy-fermion superconductor UPt 3 and a normal metal Pt, which were fabricated using a commercial piezo-electric actuator, and retried the observation of the energy gap of UPt 3 . A V-shaped dip is observed in both normal and superconducting states and disappeared around T K ∼ 20 K, suggesting that it is related to the Kondo effect. Below the superconducting transition temperature, a shallow double-minimum structure, which indicates the energy gap, has been observed for the contacts on the faces perpendicular to the a-, b- and c-axes of UPt 3

The influence of shrinkage-cracking on the drying behaviour of White Portland cement using Single-Point Imaging (SPI).

Science.gov (United States)

Beyea, S D; Balcom, B J; Bremner, T W; Prado, P J; Cross, A R; Armstrong, R L; Grattan-Bellew, P E

1998-11-01

The removal of water from pores in hardened cement paste smaller than 50 nm results in cracking of the cement matrix due to the tensile stresses induced by drying shrinkage. Cracks in the matrix fundamentally alter the permeability of the material, and therefore directly affect the drying behaviour. Using Single-Point Imaging (SPI), we obtain one-dimensional moisture profiles of hydrated White Portland cement cylinders as a function of drying time. The drying behaviour of White Portland cement, is distinctly different from the drying behaviour of related concrete materials containing aggregates.

Evaluation of point-of-care test for elevated tear matrix metalloproteinase 9 in post-LASIK dry eyes.

Science.gov (United States)

Chan, Tommy C Y; Ye, Cong; Chan, Kwok Ping; Chu, Kai On; Jhanji, Vishal

2016-09-01

To evaluate the performance of a point-of-care test for detection of matrix metalloproteinase 9 (MMP-9) levels in post-laser-assisted in situ keratomileusis (LASIK) dry eyes. A comparative study between patients with mild to moderate post-LASIK dry eyes and age-matched normal subjects was conducted. Ocular surface disease index (OSDI), tear break-up time (TBUT), and tear film MMP-9 and total protein levels were compared between the two groups. A point-of-care test device (RPS InflammaDry, Sarasota, Florida, USA) was utilised to confirm elevated MMP-9 levels in tear film. Fourteen post-LASIK dry eyes and 34 normal eyes were included. There was no significant difference in age and gender between both groups (p>0.175). The OSDI was significantly higher (25.5±7.7 vs 7.4±2.5; pdry eye compared with normal subjects. The tear film MMP-9 levels were 52.7±32.5 ng/mL in dry eyes and 4.1±2.1 ng/mL in normal eyes (p40 ng/mL in 7/14 (50.0%) post-LASIK dry eyes. The InflammaDry was positive in 8/14 (57.1%) post-LASIK eyes. All positive cases had tear film MMP-9 levels ≥38.03 ng/mL. Agreement between InflammaDry and MMP-9 was excellent with Cohen κ value of 0.857 in post-LASIK dry eyes. Only half of post-LASIK dry eyes were found to have significant inflammation associated with elevated MMP-9. The OSDI is useful to non-specifically identify patients with symptomatic dry eye while the InflammaDry determined which patients with dry eye were associated with significant inflammation that may guide therapeutic management decisions. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

What Is Dry Eye?

Medline Plus

Full Text Available ... Eye Health A-Z Symptoms Glasses & Contacts Tips & Prevention News Ask an Ophthalmologist Patient Stories Español Eye ... Eye Symptoms Causes of Dry Eye Dry Eye Treatment What Is Dry Eye? Leer en Español: ¿Qué ...

Lighting system with thermal management system having point contact synthetic jets

Science.gov (United States)

Arik, Mehmet; Weaver, Stanton Earl; Kuenzler, Glenn Howard; Wolfe, Jr., Charles Franklin; Sharma, Rajdeep

2013-12-10

Lighting system having unique configurations are provided. For instance, the lighting system may include a light source, a thermal management system and driver electronics, each contained within a housing structure. The light source is configured to provide illumination visible through an opening in the housing structure. The thermal management system includes a plurality of synthetic jets. The synthetic jets are arranged within the lighting system such that they are secured at contact points.

QUANTUM ELECTRONIC DEVICES: Superconducting Nb3Sn point contact in the submillimeter range of electromagnetic radiation

Science.gov (United States)

Belenov, É. M.; Danileĭko, M. V.; Derkach, V. E.; Romanenko, V. I.; Uskov, A. V.

1988-05-01

An investigation was made of the influence of submillimeter radiation emitted by an HCN laser operating at a frequency νl = 891 GHz on a superconducting point contact made of Nb3Sn. Three steps of the electric current were recorded. The experimental results indicated that such a contact could be used for frequency multiplication up to 3 THz.

Coherent electron focusing with quantum point contacts in a two-dimensional electron gas

NARCIS (Netherlands)

Houten, H. van; Beenakker, C.W.J.; Williamson, J.G.; Broekaart, M.E.I.; Loosdrecht, P.H.M. van; Wees, B.J. van; Mooij, J.E.; Foxon, C.T.; Harris, J.J.

1989-01-01

Transverse electron focusing in a two-dimensional electron gas is investigated experimentally and theoretically for the first time. A split Schottky gate on top of a GaAs-AlxGa1–xAs heterostructure defines two point contacts of variable width, which are used as injector and collector of ballistic

Carrier accumulation and depletion in point-contact capacitance-voltage measurements

Science.gov (United States)

Naitou, Yuichi

2017-11-01

Scanning capacitance microscopy (SCM) is a variation of atomic force microscopy in which a conductive probe tip detects the bias modulated capacitance for the purpose of measuring the nanoscale semiconductor carrier concentration. SCM can be regarded as a point-contact capacitance-voltage system, and its capacitance-voltage properties are different from those of a conventional parallel-plate capacitor. In this study, the charge accumulation and depletion behavior of a semiconductor sample were closely investigated by SCM. By analyzing the tip-sample approach curve, the effective probe tip area and charge depletion depth could be quantitatively determined.

Conjunctival impression cytology evaluation of patients with dry eye disease using scleral contact lenses.

Science.gov (United States)

Weber, Sarah La Porta; Hazarbassanov, Rossen Mihaylov; Nasaré, Alex; Gomes, José Álvaro Pereira; Hofling-Lima, Ana Luisa

2017-06-01

To evaluate conjunctival impression cytology and HLADR expression changes after wearing scleral contact lenses (ScCLs) for moderate to severe dry eye disease (DED). Prospective interventional case series. Forty-one eyes from 25 patients with moderate to severe DED were evaluated for Esclera ScCL treatment. Best-corrected visual acuity (BCVA) and slit-lamp findings were assessed. Impression cytology specimens were obtained from DED patients at the baseline and after wearing ScCLs for 12 months. The impression cytology specimens were analyzed using morphological results score, and HLA-DR positive cells were detected and quantified. The values were compared to assess the IC changes after wearing ScCLs. Forty-one eyes from 25 patients were fitted with ScCLs to manage DED. The underlying diseases were Stevens-Johnson syndrome (22 eyes), Sjogren's syndrome (11 eyes), graft-versus-host disease (2 eyes), dry eye after keratomileusis (2 eyes) and undifferentiated ocular surface disease (4 eyes). The HE-PAS impression cytology score did not differ significantly before and after wearing ScCLs for 12 months in DED patients (p>0.05). The percentage of eyes expressing the HLA-DR antigen in the temporal conjunctiva after wearing ScCL for 12 months significantly increased in patients with Sjogren's syndrome (11.11% to 66.66%; p=0.0498). In groups with Stevens Johnson syndrome and other ocular surface disorders, we did not observe statistically significant differences (p>0.05). The ScCLs did not change the parameters used to evaluate inflammatory processes, which were measured using conjunctival impression cytology and HLA-DR expression, except in Sjogren syndrome, in which there was an unexpected increase in HLA expression. Copyright © 2016 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Development of Bioclimatic Design Tool for Oman Using Dry Bulb and Dew Point Temperatures Open Database

Directory of Open Access Journals (Sweden)

Nasser Al-Azri

2017-06-01

Full Text Available Bioclimatic charts are used by engineers and architects in implementing passive cooling systems and architectural optimization with respect to natural air conditioning. Conventionally, the development of these charts is based on the availability of typical meteorological year which requires a record of meteorological data that are rarely available in sufficient amounts. Bioclimatic charts in Oman were developed earlier by the authors for limited locations based on the available typical meteorological years. Using dry bulb and dew point temperatures only, bioclimatic charts are developed for Adam, Buraimi, Ibra, Muscat, Nizwa, Rustaq, Saiq, Salalah, Suhar and Sur. These charts are better representative of bioclimatic trends since their development is mainly based on the relevant parameters, namely dry bulb temperature and dew point.

Point contact tunneling spectroscopy apparatus for large scale mapping of surface superconducting properties

Energy Technology Data Exchange (ETDEWEB)

Groll, Nickolas; Pellin, Michael J. [Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439 (United States); Zasadzinksi, John F. [Illinois Institute of Technology, Chicago, Illinois 60616 (United States); Proslier, Thomas, E-mail: prolier@anl.gov [Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439 (United States); High Energy Physics Division, Argonne National Laboratory, Lemont, Illinois 60439 (United States)

2015-09-15

We describe the design and testing of a point contact tunneling spectroscopy device that can measure material surface superconducting properties (i.e., the superconducting gap Δ and the critical temperature T{sub C}) and density of states over large surface areas with size up to mm{sup 2}. The tip lateral (X,Y) motion, mounted on a (X,Y,Z) piezo-stage, was calibrated on a patterned substrate consisting of Nb lines sputtered on a gold film using both normal (Al) and superconducting (PbSn) tips at 1.5 K. The tip vertical (Z) motion control enables some adjustment of the tip-sample junction resistance that can be measured over 7 orders of magnitudes from a quasi-ohmic regime (few hundred Ω) to the tunnel regime (from tens of kΩ up to few GΩ). The low noise electronic and LabVIEW program interface are also presented. The point contact regime and the large-scale motion capabilities are of particular interest for mapping and testing the superconducting properties of macroscopic scale superconductor-based devices.

Measurement Back-Action in Quantum Point-Contact Charge Sensing

Directory of Open Access Journals (Sweden)

Bruno Küng

2010-06-01

Full Text Available Charge sensing with quantum point-contacts (QPCs is a technique widely used in semiconductor quantum-dot research. Understanding the physics of this measurement process, as well as finding ways of suppressing unwanted measurement back-action, are therefore both desirable. In this article, we present experimental studies targeting these two goals. Firstly, we measure the effect of a QPC on electron tunneling between two InAs quantum dots, and show that a model based on the QPC’s shot-noise can account for it. Secondly, we discuss the possibility of lowering the measurement current (and thus the back-action used for charge sensing by correlating the signals of two independent measurement channels. The performance of this method is tested in a typical experimental setup.

Safety and efficacy of topical azithromycin ophthalmic solution 1.0% in the treatment of contact lens-related dry eye.

Science.gov (United States)

Nichols, Jason J; Bickle, Katherine M; Zink, Richard C; Schiewe, Michael D; Haque, Reza M; Nichols, Kelly K

2012-03-01

The purpose of this pilot study was to evaluate the safety and efficacy of azithromycin ophthalmic solution 1% in patients with contact lens-related dry eye (CLDE). This was a 4-week, single-center, open-label clinical trial in patients diagnosed with CLDE using the Contact Lens Dry Eye Questionnaire (CLDEQ). Fifty patients were enrolled in this study. The patients were randomized to 1 of 2 treatment groups: azithromycin ophthalmic solution administered bid on days 1 and 2 and on days 3 to 29±1 or Visine for Contacts rewetting drops administered qid on days 1 to 29±1. The patient diaries were used daily to collect data on comfortable and total contact lens wear time and ocular dryness throughout the treatment period. Tear osmolarity, fluorescein corneal staining, and visual acuity were also assessed during clinic visits. Fifty patients were enrolled, and 44 completed the study. One patient discontinued in the azithromycin group, and five patients discontinued in the rewetting drops group because of adverse events. A statistically significant increase in mean comfortable contact lens wear time from baseline was observed for the subjects treated with azithromycin ophthalmic solution as compared with the subjects treated with rewetting drops at week 4 (P=0.004; primary endpoint), in addition to weeks 2 and 3. The improvement in the mean comfortable wear time for the patients in the azithromycin treatment group exceeded 2 hrs throughout the treatment period (weeks 1-4). No significant differences were observed between the groups for total wear time, low contrast visual acuity, or tear osmolarity. Subject-rated ocular dryness (PM time assessments) was significantly improved from baseline in the subjects treated with azithromycin ophthalmic solution as compared with those treated with rewetting drops at weeks 2 and 3 endpoints (P=0.015 for each week). Additionally, a statistical difference was observed in favor of the azithromycin treatment group at week 2 for the

Dry adhesives with sensing features

International Nuclear Information System (INIS)

Krahn, J; Menon, C

2013-01-01

Geckos are capable of detecting detachment of their feet. Inspired by this basic observation, a novel functional dry adhesive is proposed, which can be used to measure the instantaneous forces and torques acting on an adhesive pad. Such a novel sensing dry adhesive could potentially be used by climbing robots to quickly realize and respond appropriately to catastrophic detachment conditions. The proposed torque and force sensing dry adhesive was fabricated by mixing Carbon Black (CB) and Polydimethylsiloxane (PDMS) to form a functionalized adhesive with mushroom caps. The addition of CB to PDMS resulted in conductive PDMS which, when under compression, tension or torque, resulted in a change in the resistance across the adhesive patch terminals. The proposed design of the functionalized dry adhesive enables distinguishing an applied torque from a compressive force in a single adhesive pad. A model based on beam theory was used to predict the change in resistance across the terminals as either a torque or compressive force was applied to the adhesive patch. Under a compressive force, the sensing dry adhesive was capable of measuring compression stresses from 0.11 Pa to 20.9 kPa. The torque measured by the adhesive patch ranged from 2.6 to 10 mN m, at which point the dry adhesives became detached. The adhesive strength was 1.75 kPa under an applied preload of 1.65 kPa for an adhesive patch with an adhesive contact area of 7.07 cm 2 . (paper)

Dry adhesives with sensing features

Science.gov (United States)

Krahn, J.; Menon, C.

2013-08-01

Geckos are capable of detecting detachment of their feet. Inspired by this basic observation, a novel functional dry adhesive is proposed, which can be used to measure the instantaneous forces and torques acting on an adhesive pad. Such a novel sensing dry adhesive could potentially be used by climbing robots to quickly realize and respond appropriately to catastrophic detachment conditions. The proposed torque and force sensing dry adhesive was fabricated by mixing Carbon Black (CB) and Polydimethylsiloxane (PDMS) to form a functionalized adhesive with mushroom caps. The addition of CB to PDMS resulted in conductive PDMS which, when under compression, tension or torque, resulted in a change in the resistance across the adhesive patch terminals. The proposed design of the functionalized dry adhesive enables distinguishing an applied torque from a compressive force in a single adhesive pad. A model based on beam theory was used to predict the change in resistance across the terminals as either a torque or compressive force was applied to the adhesive patch. Under a compressive force, the sensing dry adhesive was capable of measuring compression stresses from 0.11 Pa to 20.9 kPa. The torque measured by the adhesive patch ranged from 2.6 to 10 mN m, at which point the dry adhesives became detached. The adhesive strength was 1.75 kPa under an applied preload of 1.65 kPa for an adhesive patch with an adhesive contact area of 7.07 cm2.

Feedback cooling of cantilever motion using a quantum point contact transducer

International Nuclear Information System (INIS)

Montinaro, M.; Mehlin, A.; Solanki, H. S.; Peddibhotla, P.; Poggio, M.; Mack, S.; Awschalom, D. D.

2012-01-01

We use a quantum point contact (QPC) as a displacement transducer to measure and control the low-temperature thermal motion of a nearby micromechanical cantilever. The QPC is included in an active feedback loop designed to cool the cantilever's fundamental mechanical mode, achieving a squashing of the QPC noise at high gain. The minimum achieved effective mode temperature of 0.2 K and the displacement resolution of 10 -11 m/√(Hz) are limited by the performance of the QPC as a one-dimensional conductor and by the cantilever-QPC capacitive coupling.

Pipeline drying using dehumidified air with low dew point temperature

Energy Technology Data Exchange (ETDEWEB)

Ahmed, Syed Younus; Gandhidasan, P.; Al-Farayedhi, A.A. [King Fahd Univ. of Petroleum and Minerals, Mechanical Engineering Dept., Dhahran (Saudi Arabia)

1998-05-01

The presence of humidity may be detrimental to the operation of pipelines transporting natural gas or other petroleum products. In particular conditions water solidifies or reacts chemically with hydrocarbons, forming hydrates. Such crystalline substances may cause obstruction of the lines and damage the equipment of the relevant facilities. A procedure for predicting the performance of drying a pipeline using dehumidified air with a low dew point is described in this paper. The mathematical model estimates the time required for the complete removal of moisture in the pipeline for the given operating conditions with simplified assumptions. The governing equations are solved analytically as well as numerically and the results are briefly discussed in the paper. (Author)

A frictional contact problem for an electro-viscoelastic body

Directory of Open Access Journals (Sweden)

Mircea Sofonea

2007-12-01

Full Text Available A mathematical model which describes the quasistatic frictional contact between a piezoelectric body and a deformable conductive foundation is studied. A nonlinear electro-viscoelastic constitutive law is used to model the piezoelectric material. Contact is described with the normal compliance condition, a version of Coulomb's law of dry friction, and a regularized electrical conductivity condition. A variational formulation of the model, in the form of a coupled system for the displacements and the electric potential, is derived. The existence of a unique weak solution of the model is established under a smallness assumption on the surface conductance. The proof is based on arguments of evolutionary variational inequalities and fixed points of operators.

Current-voltage characteristics of quantum-point contacts in the closed-channel regime: Transforming the bias voltage into an energy scale

DEFF Research Database (Denmark)

Gloos, K.; Utko, P.; Aagesen, M.

2006-01-01

We investigate the I(V) characteristics (current versus bias voltage) of side-gated quantum-point contacts, defined in GaAs/AlxGa1-xAs heterostructures. These point contacts are operated in the closed-channel regime, that is, at fixed gate voltages below zero-bias pinch-off for conductance. Our....... Such a built-in energy-voltage calibration allows us to distinguish between the different contributions to the electron transport across the pinched-off contact due to thermal activation or quantum tunneling. The first involves the height of the barrier, and the latter also its length. In the model that we...

Fingerprints of bosonic symmetry protected topological state in a quantum point contact

OpenAIRE

Zhang, Rui-Xing; Liu, Chao-Xing

2016-01-01

In this work, we study the transport through a quantum point contact for bosonic helical liquid that exists at the edge of a bilayer graphene under a strong magnetic field. We identify "smoking gun" transport signatures to distinguish bosonic symmetry protected topological (BSPT) state from fermionic two-channel quantum spin Hall (QSH) state in this system. In particular, a novel charge insulator/spin conductor phase is found for BSPT state, while either charge insulator/spin insulator or cha...

Effect of microwave freeze drying on quality and energy supply in drying of barley grass.

Science.gov (United States)

Cao, Xiaohuang; Zhang, Min; Mujumdar, Arun S; Zhong, Qifeng; Wang, Zhushang

2018-03-01

Young barley grass leaves are well-known for containing the antioxidant substances flavonoid and chlorophyll. However, low product quality and energy efficiency exist with respect to the dehydration of barley grass leaves. To improve energy supply and the quality of barley grass, microwave heating instead of contact heat was applied for the freeze drying of barley grass at a pilot scale at 1, 1.5 and 2 W g -1 , respectively; After drying, energy supply and quality parameters of color, moisture content, chlorophyll, flavonoids, odors of dried barley grass were determined to evaluate the feasibility of the study. Microwave freeze drying (MFD) allowed a low energy supply and high contents of chlorophyll and flavonoids. A lightness value of 60.0, a green value of -11.5 and an energy supply of 0.61 kW h -1  g -1 were observed in 1.5 W g -1 MFD; whereas drying time (7 h) decreased by 42% compared to contact heating. Maximum content of flavonoid and chlorophyll was 11.7 and 12.8 g kg -1 barley grass. Microwave heating leads to an odor change larger than that for contact heating observed for the freeze drying of barley grass. MFD retains chlorophyll and flavonoids, as well as colors and odors of samples, and also decreases energy consumption in the freeze drying of barley grass. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

An effective means for damage detection of bridges using the contact-point response of a moving test vehicle

Science.gov (United States)

Zhang, Bin; Qian, Yao; Wu, Yuntian; Yang, Y. B.

2018-04-01

To further the technique of indirect measurement, the contact-point response of a moving test vehicle is adopted for the damage detection of bridges. First, the contact-point response of the vehicle moving over the bridge is derived both analytically and in central difference form (for field use). Then, the instantaneous amplitude squared (IAS) of the driving component of the contact-point response is calculated by the Hilbert transform, making use of its narrow-band feature. The IAS peaks serve as the key parameter for damage detection. In the numerical simulation, a damage (crack) is modeled by a hinge-spring unit. The feasibility of the proposed method to detect the location and severity of a damage or multi damages of the bridge is verified. Also, the effects of surface roughness, vehicle speed, measurement noise and random traffic are studied. In the presence of ongoing traffic, the damages of the bridge are identified from the repeated or invariant IAS peaks generated for different traffic flows by the same test vehicle over the bridge.

Direct Laser Writing of Nanophotonic Structures on Contact Lenses.

Science.gov (United States)

AlQattan, Bader; Yetisen, Ali K; Butt, Haider

2018-04-24

Contact lenses are ubiquitous biomedical devices used for vision correction and cosmetic purposes. Their application as quantitative analytical devices is highly promising for point-of-care diagnostics. However, it is a challenge to integrate nanoscale features into commercial contact lenses for application in low-cost biosensors. A neodymium-doped yttrium aluminum garnet (Nd:YAG) laser (1064 nm, 3 ns pulse, 240 mJ) in holographic interference patterning mode was utilized to produce optical nanostructures over the surface of a hydrogel contact lens. One-dimensional (925 nm) and two-dimensional (925 nm × 925 nm) nanostructures were produced on contact lenses and analyzed by spectroscopy and angle-resolve measurements. The holographic properties of these nanostructures were tested in ambient moisture, fully hydrated, and artificial tear conditions. The measurements showed a rapid tuning of optical diffraction from these nanostructures from 41 to 48°. The nanostructures were patterned near the edges of the contact lens to avoid any interference and obstruction to the human vision. The formation of 2D nanostructures on lenses increased the diffraction efficiency by more than 10%. The versatility of the holographic laser ablation method was demonstrated by producing four different 2D nanopattern geometries on contact lenses. Hydrophobicity of the contact lens was characterized by contact angle measurements, which increased from 59.0° at pristine condition to 62.5° at post-nanofabrication. The holographic nanostructures on the contact lens were used to sense the concentration of Na + ions. Artificial tear solution was used to simulate the conditions in dry eye syndrome, and nanostructures on the contact lenses were used to detect the electrolyte concentration changes (±47 mmol L -1 ). Nanopatterns on a contact lens may be used to sense other ocular diseases in early stages at point-of-care settings.

Cellulose-Pectin Spatial Contacts Are Inherent to Never-Dried Arabidopsis Primary Cell Walls: Evidence from Solid-State Nuclear Magnetic Resonance1[OPEN

Science.gov (United States)

Wang, Tuo; Park, Yong Bum; Hong, Mei

2015-01-01

The structural role of pectins in plant primary cell walls is not yet well understood because of the complex and disordered nature of the cell wall polymers. We recently introduced multidimensional solid-state nuclear magnetic resonance spectroscopy to characterize the spatial proximities of wall polysaccharides. The data showed extensive cross peaks between pectins and cellulose in the primary wall of Arabidopsis (Arabidopsis thaliana), indicating subnanometer contacts between the two polysaccharides. This result was unexpected because stable pectin-cellulose interactions are not predicted by in vitro binding assays and prevailing cell wall models. To investigate whether the spatial contacts that give rise to the cross peaks are artifacts of sample preparation, we now compare never-dried Arabidopsis primary walls with dehydrated and rehydrated samples. One-dimensional 13C spectra, two-dimensional 13C-13C correlation spectra, water-polysaccharide correlation spectra, and dynamics data all indicate that the structure, mobility, and intermolecular contacts of the polysaccharides are indistinguishable between never-dried and rehydrated walls. Moreover, a partially depectinated cell wall in which 40% of homogalacturonan is extracted retains cellulose-pectin cross peaks, indicating that the cellulose-pectin contacts are not due to molecular crowding. The cross peaks are observed both at −20°C and at ambient temperature, thus ruling out freezing as a cause of spatial contacts. These results indicate that rhamnogalacturonan I and a portion of homogalacturonan have significant interactions with cellulose microfibrils in the native primary wall. This pectin-cellulose association may be formed during wall biosynthesis and may involve pectin entrapment in or between cellulose microfibrils, which cannot be mimicked by in vitro binding assays. PMID:26036615

Temperature evolution of subharmonic gap structures in MgB{sub 2}/Nb point-contacts

Energy Technology Data Exchange (ETDEWEB)

Giubileo, F. [CNR-INFM Laboratorio Regionale SUPERMAT e Dipartimento di Fisica ' E.R. Caianiello' , Universita degli Studi di Salerno, via Salvador Allende, 84081 Baronissi (Italy)], E-mail: giubileo@sa.infn.it; Bobba, F.; Scarfato, A.; Piano, S. [CNR-INFM Laboratorio Regionale SUPERMAT e Dipartimento di Fisica ' E.R. Caianiello' , Universita degli Studi di Salerno, via Salvador Allende, 84081 Baronissi (Italy); Aprili, M. [Laboratoire de Spectroscopie en Lumiere Polarisee, ESPCI, 10 rue Vauquelin, 75005 Paris (France); CSNSM-CNRS, Bat. 108 Universite Paris-Sud, 91405 Orsay (France); Cucolo, A.M. [CNR-INFM Laboratorio Regionale SUPERMAT e Dipartimento di Fisica ' E.R. Caianiello' , Universita degli Studi di Salerno, via Salvador Allende, 84081 Baronissi (Italy)

2007-09-01

We have performed point-contact spectroscopy experiments on superconducting micro-constrictions between Nb tips and high quality MgB{sub 2} pellets. We measured the temperature evolution (between 4.2 K and 300 K) of the current-voltage (I-V) and of the dynamical conductance (dI/dV-V) characteristics. Above the Nb critical temperature T{sub C}{sup Nb}, the conductance of the constrictions behaves as predicted by the BTK model for S/N contacts being Nb in its normal state below T{sub C}{sup Nb}, the contacts show Josephson current and subharmonic gap structures, due to multiple Andreev reflections. These observations clearly indicate the coupling of the MgB{sub 2} 3D {pi}-band with the Nb superconducting order parameter. We found {delta}{sub {pi}} = 2.4 {+-} 0.2 meV for the three-dimensional gap of MgB{sub 2}.

Contact angles of water-repellent porous media inferred by tensiometer - TDR probe measurement under controlled wetting and drying cycles

DEFF Research Database (Denmark)

Subedi, Shaphal; Kawamoto, Ken; Komatsu, Toshiko

2013-01-01

with water, eventually allowing water imbibition. However, the effect of the reduction in CA with soil-water contact time on the water retention function of hydrophobic media is not yet fully understood. In this study, water retention characteristics were measured using a hanging water column apparatus...... retention curves. For both water-repellent VAS and hydrophobized sand samples, the calculated CA–SWRC increased with increasing WR. This was determined from both the water drop penetration time and the initial contact angle (CAi) by the sessile drop method. Calculated CA–SWRC values ranged from 20° to 48......-filled pore distributions under controlled wetting and drying cycles was found on calculating the soil water capacity and pore size density as a function of water potential....

Point-contact spectroscopic studies on normal and superconducting AFe2As2-type iron pnictide single crystals

International Nuclear Information System (INIS)

Lu Xin; Park, W K; Greene, L H; Yuan, H Q; Chen, G F; Luo, G L; Wang, N L; Sefat, A S; McGuire, M A; Jin, R; Sales, B C; Mandrus, D; Gillett, J; Sebastian, Suchitra E

2010-01-01

Point-contact Andreev reflection spectroscopy is applied to investigate the gap structure in iron pnictide single-crystal superconductors of the AFe 2 As 2 (A = Ba, Sr) family ('Fe-122'). The observed point-contact junction conductance curves, G(V), can be divided into two categories: one where Andreev reflection is present for both (Ba 0.6 K 0.4 )Fe 2 As 2 and Ba(Fe 0.9 Co 0.1 ) 2 As 2 , and the other with a V 2/3 background conductance universally observed, extending even up to 100 meV for Sr 0.6 Na 0.4 Fe 2 As 2 and Sr(Fe 0.9 Co 0.1 ) 2 As 2 . The latter is also observed in point-contact junctions on the nonsuperconducting parent compound BaFe 2 As 2 and superconducting (Ba 0.6 K 0.4 )Fe 2 As 2 crystals. Mesoscopic phase-separated coexistence of magnetic and superconducting orders is considered to explain distinct behaviors in the superconducting samples. For Ba 0.6 K 0.4 Fe 2 As 2 , double peaks due to Andreev reflection with a strongly sloping background are frequently observed for point contacts on freshly cleaved c-axis surfaces. If normalized using a background baseline and analyzed using the Blonder-Tinkham-Klapwijk model, the data show a gap size of ∼ 3.0-4.0 meV with 2Δ 0 /k B T c ∼ 2.0-2.6, consistent with the smaller gap size reported for the LnFeAsO family ('Fe-1111'). For the Ba(Fe 0.9 Co 0.1 ) 2 As 2 , the G(V) curves typically display a zero-bias conductance peak.

Biomechanical analysis of the contact phase in drop jumps performed in water and on dry land

Directory of Open Access Journals (Sweden)

Caroline Ruschel

2016-03-01

Full Text Available DOI: http://dx.doi.org/10.5007/1980-0037.2016v18n1p41   Plyometric training in the aquatic environment has been used as way of reducing loads through the action of buoyancy. However, little is known about the biomechanical characteristics of plyometric exercises in water, which can assist in the prescription of training in this environment. This study aimed to analyze the vertical component of the ground reaction force and contact duration of drop jumps (DJ performed on land and at hip level water immersion. Participants were 22 male athletes (19.1 ± 3.7 years, who performed three maximum DJs in water and on dry land. Peak force and duration of braking and propulsion sub-phases of the DJ contact were analyzed with the use of two underwater force platforms, a 2-D waterproofed electrogoniometer, acquisition systems ADS2000-IP and TeleMyo 2400TG2, and a signal synchronizer. The effect of immersion was investigated through comparison tests for dependent samples (p <0.05. In water, the following results were observed: (a reduction of 41.8% (p <0.001, d = 2.24 and 23.8% (p <0.001, d = 1.50 of peak forces during braking and propulsion sub-phases respectively; and (b increase of 41.8% in the braking (p <0.001, d = 1.41 and 12.3% in the propulsion contact times (p = 0.006, d = 0.75. The aquatic environment can be an alternative when one aims to reduce the load during the DJ contact; however, the longer duration increasing of contact sub-phases in water at hip immersion may compromise the proper functioning of the stretch-shortening cycle in water.

The Use of the Esclera Scleral Contact Lens in the Treatment of Moderate to Severe Dry Eye Disease.

Science.gov (United States)

La Porta Weber, Sarah; Becco de Souza, Rodrigo; Gomes, José Álvaro Pereira; Hofling-Lima, Ana Luisa

2016-03-01

To evaluate the efficacy of the Esclera scleral contact lens (SCL) treatment and its impact on clinical testing for moderate to severe dry eye disease (DED). Prospective interventional case series. A total of 41 eyes from 25 patients with moderate to severe DED were evaluated for the Esclera SCL treatment. Best-corrected visual acuity (BCVA), tear osmolarity, the Schirmer I test, tear film breakup time (TBUT), corneal and conjunctival staining, meibomian grading, and Ocular Surface Disease Index and SF-36v2 questionnaires were assessed before and after the SCL treatment. These values were compared to assess the real benefit of using SCL as a treatment for DED. Forty-one eyes from 25 patients were fitted with SCL for management of DED. The underlying diseases were Stevens-Johnson syndrome (22 eyes), Sjogren syndrome (11 eyes), graft-vs-host disease (2 eyes), dry eye after keratomileusis in situ (2 eyes), and undifferentiated ocular surface disease (4 eyes). BCVA improved from 0.703 ± 0.55 logMAR with habitual correction to 0.406 ± 0.43 logMAR with SCL (P dry eye symptoms and quality of life as assessed by the OSDI and SF-36v2 questionnaires (both with P dry eye symptoms, and quality of life. Copyright © 2016 Elsevier Inc. All rights reserved.

Temperature Dependence and Magnetic Field Dependence of Quantum Point Contacts in Si-Inversion Layers

NARCIS (Netherlands)

Wang, S.L.; Son, P.C. van; Wees, B.J. van; Klapwijk, T.M.

1992-01-01

The conductance of ballistic point contacts in high-mobility Si-inversion layers has been studied at several temperatures between 75 and 600 mK both without and in a magnetic field (up to 12T). When the width of constriction is varied in zero magnetic field, step-like features at multiples of 4e2/h

Spreading of blood drops over dry porous substrate: complete wetting case.

Science.gov (United States)

Chao, Tzu Chieh; Arjmandi-Tash, Omid; Das, Diganta B; Starov, Victor M

2015-05-15

The process of dried blood spot sampling involves simultaneous spreading and penetration of blood into a porous filter paper with subsequent evaporation and drying. Spreading of small drops of blood, which is a non-Newtonian liquid, over a dry porous layer is investigated from both theoretical and experimental points of view. A system of two differential equations is derived, which describes the time evolution of radii of both the drop base and the wetted region inside the porous medium. The system of equations does not include any fitting parameters. The predicted time evolutions of both radii are compared with experimental data published earlier. For a given power law dependency of viscosity of blood with different hematocrit level, radii of both drop base and wetted region, and contact angle fell on three universal curves if appropriate scales are used with a plot of the dimensionless radii of the drop base and the wetted region inside the porous layer and dynamic contact angle on dimensionless time. The predicted theoretical relationships are three universal curves accounting satisfactorily for the experimental data. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Superconductor (Nb)-charge density wave (NbSe sub 3) point-contact spectroscopy

CERN Document Server

Sinchenko, A A

2003-01-01

Measurements of differential current-voltage (I-V) characteristics of point contacts between Nb and the charge density wave (CDW) conductor NbSe sub 3 formed along the conducting chain direction are reported. Below the superconducting transition of Nb, we have clearly observed Andreev reflection of the gapless electrons of NbSe sub 3. Analysis of the spectra obtained indicates that when the energy of injected particles exceeds the superconducting energy gap, the superconductivity near the S-CDW interface is suppressed because of non-equilibrium effects.

The Effect of Dry Needling Compared With Ischemic Pressure on Pain Intensity on Active Trigger Point in Upper Trapezius Muscle

Directory of Open Access Journals (Sweden)

Maryam Ziaeifar

2013-07-01

Full Text Available Objective: Myofascial trigger point is one of the most common causes of musculoskeletal pain and disorders. Myofascial trigger point in upper trapezius has been reported as a frequent symptom in patients with neck and thoracic pain. The purpose of this study was to investigate the effect of dry needling compared with ischemic pressure on active trigger point in upper trapezius muscle. Materials & Methods: 32 women with active myofascial trigger point in upper trapezius muscle participated in this randomized clinical trial (RCT study. The subjects were randomly assigned into two groups: dry needling (N=15 and ischemic pressure (N=17. The visual analogue scale (VAS was used to assess the pain intensity before and after treatment in both groups. Paired t-test was used to determine any significant difference in pain intensity after treatment sessions compared with pre-treatment score in control and experimental group. Analysis of Covariance (ANCOVA was calculated to determine the significance of differences between the control and experimental groups in post-test scores, with pre-treatment scores used as covariates in the analysis. Results: Statistical analysis (paired t-test revealed significant decrease in pain intensity after treatment sessions in control and experimental group (P=0.00 compared with pre-treatment score. In the ANCOVA, controlling for pre-test scores, no significant difference was found between the two groups (P=0.8. Conclusion: It seems that that both dry needling and ischemic pressure are effective in improvement in the pain intensity in subjects with myofascial trigger points. However, dry needling can be used by clinicians and therapist in physiotherapy clinics.

Josephson effect in point contacts between 'f-wave' superconductors

International Nuclear Information System (INIS)

Mahmoodi, R.; Shevchenko, S.N.; Kolesnichenko, Yu.A

2002-01-01

A stationary Josephson effect in point contacts between triplet superconductors is analyzed theoretically for most probable models of the order parameter in UPt 3 and Sr 2 RuO 4 . The consequence of misorientation of crystals in the superconducting banks on this effect is considered. We show that different models for the order parameter lead to quit different current-phase relations. For certain angles of misorientation a boundary between superconductors can generate a spontaneous current parallel to the surface. In a number of cases the state with a zero Josephson current and minimum of the free energy corresponds to a spontaneous phase difference. This phase difference depends on the misorientation angle and may possess any value. We conclude that experimental investigations of the current-phase relations of small junctions can be used for determination of the order parameter symmetry in the superconductors mentioned above

Soft-contact-lenses-induced complications

Directory of Open Access Journals (Sweden)

Suvajac Gordana

2008-01-01

Full Text Available Background/Aim. Soft contact lenses occupy significant place in ophthalmology, both in the correction of refraction anomalies and in the treatment of many eye diseases. The number of patients that wear soft contact lenses for the purpose of correcting ametropia is constantly increasing. Due to the increasing number of wearers, the percentage of complications that can lead to serious eye damage and serious vision loss is also increasing. The aim of this study was to point out the most common complications related to soft contact lens use. Methods. In the period from 1995−2004 this prospective study included 510 patients wearing soft contact lenses for correcting ametropia. None of the patients wore contact lenses before and none suffered from any system or local diseases that could affected the development of eventual complications. The study took seven years with the patients who wore conventional lenses and three years with those who wore replacement contact lenses. All the necessary ophthalmologic examinations were done (visual acuity, refractokeratometry, the quantity of tear film, biomicroscopic examination of anterior eye segment. All the complications were filmed by video camera. Results. Of all the patients, 19 had blepharitis, 73 suffered from “dry eye”, 57 had conjunctival hyperemia, 12 had conjunctivitis, 34 had gigantopapillary conjunctivitis (GPC, 93 had punctiform epitheliopathy, 20 had corneal infiltration, one patient had keratitis, 91 had corneal vascularisation, and 95 patients had corneal deposits. Conclusion. Both the type and frequency of complications related to soft contact lens use in our group of patients, proved to be significant. Some of this complications (keratitis can significantly damage vision and lead to loss of vision and sometimes can require operative treatment.

76 FR 4408 - Service Contract Inventory and Corresponding Point of Contact Information Per Section 703 of...

Science.gov (United States)

2011-01-25

... SOCIAL SECURITY ADMINISTRATION [Docket No. SSA-2011-0009] Service Contract Inventory and... providing the Web site address (URL) for the Service Contract Inventory and the corresponding point of... Law 111-117. FOR FURTHER INFORMATION CONTACT: Dennis Wilhite, Director, Office of Budget Execution and...

Evaluation of the leap motion controller as a new contact-free pointing device.

Science.gov (United States)

Bachmann, Daniel; Weichert, Frank; Rinkenauer, Gerhard

2014-12-24

This paper presents a Fitts' law-based analysis of the user's performance in selection tasks with the Leap Motion Controller compared with a standard mouse device. The Leap Motion Controller (LMC) is a new contact-free input system for gesture-based human-computer interaction with declared sub-millimeter accuracy. Up to this point, there has hardly been any systematic evaluation of this new system available. With an error rate of 7.8% for the LMC and 2.8% for the mouse device, movement times twice as large as for a mouse device and high overall effort ratings, the Leap Motion Controller's performance as an input device for everyday generic computer pointing tasks is rather limited, at least with regard to the selection recognition provided by the LMC.

Freeze-dried plasma at the point of injury: from concept to doctrine.

Science.gov (United States)

Glassberg, Elon; Nadler, Roy; Gendler, Sami; Abramovich, Amir; Spinella, Philip C; Gerhardt, Robert T; Holcomb, John B; Kreiss, Yitshak

2013-12-01

While early plasma transfusion for the treatment of patients with ongoing major hemorrhage is widely accepted as part of the standard of care in the hospital setting, logistic constraints have limited its use in the out-of-hospital setting. Freeze-dried plasma (FDP), which can be stored at ambient temperatures, enables early treatment in the out-of-hospital setting. Point-of-injury plasma transfusion entails several significant advantages over currently used resuscitation fluids, including the avoidance of dilutional coagulopathy, by minimizing the need for crystalloid infusion, beneficial effects on endothelial function, physiological pH level, and better maintenance of intravascular volume compared with crystalloid-based solutions. The Israel Defense Forces Medical Corps policy is that plasma is the resuscitation fluid of choice for selected, severely wounded patients and has thus included FDP as part of its armamentarium for use at the point of injury by advanced life savers, across the entire military. We describe the clinical rationale behind the use of FDP at the point-of-injury, the drafting of the administration protocol now being used by Israel Defense Forces advanced life support providers, the process of procurement and distribution, and preliminary data describing the first casualties treated with FDP at the point of injury. It is our hope that others will be able to learn from our experience, thus improving trauma casualty care around the world.

Modeling A.C. Electronic Transport through a Two-Dimensional Quantum Point Contact

International Nuclear Information System (INIS)

Aronov, I.E.; Beletskii, N.N.; Berman, G.P.; Campbell, D.K.; Doolen, G.D.; Dudiy, S.V.

1998-01-01

We present the results on the a.c. transport of electrons moving through a two-dimensional (2D) semiconductor quantum point contact (QPC). We concentrate our attention on the characteristic properties of the high frequency admittance (ωapproximately0 - 50 GHz), and on the oscillations of the admittance in the vicinity of the separatrix (when a channel opens or closes), in presence of the relaxation effects. The experimental verification of such oscillations in the admittance would be a strong confirmation of the semi-classical approach to the a.c. transport in a QPC, in the separatrix region

The Correlation between Daily Lens Wear Duration and Dry Eye Syndrome.

Science.gov (United States)

Lubis, Rodiah Rahmawaty; Gultom, Monica Tumiar Hanna

2018-05-20

To analyze the correlation between the daily lens wear duration and dry eye syndrome. This study was an analytic cross sectional study using consecutive sampling conducted among the students in Economy and Bussiness Faculty and Faculty of Humanities in University of Sumatera Utara aged between 17 to 23 that wore contact lens continously for at least a year and 5 days a week. The symptoms were assessed using Contact Lens Dry Eye Questionnaire-8 (CLDEQ-8) and interview about their contact lens comfort; eye drops usage, contact lens washing habit, daily circumstances, places to buy contact lens and personal experince in wearing contact lens. The questionnaire was completed by 53 students. All of them were female and wore softlens wearers. The mean duration of daily wear was 8.19 ± 2.20 hours. The most common symptom experienced was dry eye and the least symptom experienced was removing lens. The most frequent symptom experienced was closing eyes and the least frequent symptom experienced was removing lenses. This study used Exact Test as analysis statistic method. The result was p > 0.05 which means there is no correlation between daily lens wear duration and dry eye syndrome. This study showed that dry eye syndrome was not correlated with daily lens wear duration, but affected by many factors such as contact lens, lens care solution, eye drops usage and environment.

Evaluation of the Leap Motion Controller as a New Contact-Free Pointing Device

Directory of Open Access Journals (Sweden)

Daniel Bachmann

2014-12-01

Full Text Available This paper presents a Fitts’ law-based analysis of the user’s performance in selection tasks with the Leap Motion Controller compared with a standard mouse device. The Leap Motion Controller (LMC is a new contact-free input system for gesture-based human-computer interaction with declared sub-millimeter accuracy. Up to this point, there has hardly been any systematic evaluation of this new system available. With an error rate of 7.8% for the LMC and 2.8% for the mouse device, movement times twice as large as for a mouse device and high overall effort ratings, the Leap Motion Controller’s performance as an input device for everyday generic computer pointing tasks is rather limited, at least with regard to the selection recognition provided by the LMC.

Simulation Results: Optimization of Contact Ratio for Interdigitated Back-Contact Solar Cells

Directory of Open Access Journals (Sweden)

Vinay Budhraja

2017-01-01

Full Text Available In the fabrication of interdigitated back contact (IBC solar cells, it is very important to choose the right size of contact to achieve the maximum efficiency. Line contacts and point contacts are the two possibilities, which are being chosen for IBC structure. It is expected that the point contacts would give better results because of the reduced recombination rate. In this work, we are simulating the effect of contact size on the performance of IBC solar cells. Simulations were done in three dimension using Quokka, which numerically solves the charge carrier transport. Our simulation results show that around 10% of contact ratio is able to achieve optimum cell efficiency.

Proper balance of omega-3 and omega-6 fatty acid supplements with topical cyclosporine attenuated contact lens-related dry eye syndrome.

Science.gov (United States)

Wang, Ling; Chen, Xi; Hao, Jingfang; Yang, Lu

2016-12-01

Essential fatty acids had been applied in the treatment of dry eye syndrome (DES), but the effects of different combinations of fatty acids have not been investigated. 360 long-term contact lens wearers were included in this double-blinded study. Omega-3 and omega-6 fatty acids were combined in different ratios and supplied to the participants that were randomly divided into six groups, and the effects of different essential fatty acids mixture on DES with or without topical cyclosporine were investigated. More than half of long-term contact lens wearers suffered from DES, which were found to be attenuated by oral supplement of properly balanced O3FA and O6FA fatty acid. The topical cyclosporine treatment considerably inhibited the production of cytokines compared to the cyclosporine negative groups, which further relieved DES. Proper balance of omega-3 and omega-6 fatty acid combination significantly alleviated contact lens-related DES.

Fragmentation of molten metal drop with instantaneous contact temperature below the boiling point of Na

International Nuclear Information System (INIS)

Inukai, S.; Sugiyama, K.; Nishimura, S.; Kinoshita, I.

2001-01-01

The consequence of the core disruptive accidents in metallic-fueled Na-cooled reactors is strongly affected by the feedback reactivity originating in the boiling of Na and the dispersion of molten fuel due to fuel-coolant interactions. The design of the core configuration to promote the dispersion of molten fuel is therefore very important for social acceptance. It has been recognized in this context that metallic fuel has a potentiality to make liquefied fuel with fuel pin tube even in the temperature range below the boiling point of Na. If the liquefied fuel solidified without fuel-coolant interactions in the core region, this event leads the core condition to a pessimistic scenario of re-criticality. As a basic study related to this problem, the present experimental study investigates the possibility of fragmentation of metal drop with instantaneous contact temperature below the boiling point of Na (883 C). The molten Al drop, which has a melting point of 660 C above the operational temperature range of core, was selected as a simulant of liquefied fuel in the present study. Al particles of 5 g or 0.56 g were heated up to the initial temperature ranging from 850 C to 1113 C in a crucible by using an electric heater. The molten Al drop was dropped into a sodium pool adjusted the temperature from 280 C to 499 C. The Al drop at initial temperature sufficiently higher that the boiling point of Na was observed to fragment into pieces under the condition of instantaneous contact temperature below the boiling point of Na. It is confirmed that the fragmentation is caused due to the thermal interactions between the molten Al and the Na entrapped into the drop. (author)

Fragmentation of molten metal drop with instantaneous contact temperature below the boiling point of Na

Energy Technology Data Exchange (ETDEWEB)

Inukai, S.; Sugiyama, K. [Hokkaido Univ., Dept. of Nuclear Engineering, Sapporo (Japan); Nishimura, S.; Kinoshita, I. [Central Research Institute of Electric Power Industry, Tokyo (Japan)

2001-07-01

The consequence of the core disruptive accidents in metallic-fueled Na-cooled reactors is strongly affected by the feedback reactivity originating in the boiling of Na and the dispersion of molten fuel due to fuel-coolant interactions. The design of the core configuration to promote the dispersion of molten fuel is therefore very important for social acceptance. It has been recognized in this context that metallic fuel has a potentiality to make liquefied fuel with fuel pin tube even in the temperature range below the boiling point of Na. If the liquefied fuel solidified without fuel-coolant interactions in the core region, this event leads the core condition to a pessimistic scenario of re-criticality. As a basic study related to this problem, the present experimental study investigates the possibility of fragmentation of metal drop with instantaneous contact temperature below the boiling point of Na (883 C). The molten Al drop, which has a melting point of 660 C above the operational temperature range of core, was selected as a simulant of liquefied fuel in the present study. Al particles of 5 g or 0.56 g were heated up to the initial temperature ranging from 850 C to 1113 C in a crucible by using an electric heater. The molten Al drop was dropped into a sodium pool adjusted the temperature from 280 C to 499 C. The Al drop at initial temperature sufficiently higher that the boiling point of Na was observed to fragment into pieces under the condition of instantaneous contact temperature below the boiling point of Na. It is confirmed that the fragmentation is caused due to the thermal interactions between the molten Al and the Na entrapped into the drop. (author)

Evaluation of the Leap Motion Controller as a New Contact-Free Pointing Device

OpenAIRE

Bachmann, Daniel; Weichert, Frank; Rinkenauer, Gerhard

2014-01-01

This paper presents a Fitts' law-based analysis of the user's performance in selection tasks with the Leap Motion Controller compared with a standard mouse device. The Leap Motion Controller (LMC) is a new contact-free input system for gesture-based human-computer interaction with declared sub-millimeter accuracy. Up to this point, there has hardly been any systematic evaluation of this new system available. With an error rate of 7.8 % for the LMC and 2.8% for the mouse device, movement times...

Talking points for 8. meeting of Points of Contact for Recruitment of Women, 11 March 2010, Vienna, Austria

International Nuclear Information System (INIS)

Amano, Y.

2010-01-01

Full text: Ladies and Gentlemen, Dear Colleagues, This is my first opportunity as Director General to share with you my views on the representation of women in the Secretariat. For many years, the proportion of Professional women at the Agency was among the lowest in the UN system - about 18%. This partially reflected the traditionally low number of women in the nuclear sciences. We can take some pride in the progress that we have made in recent years. Women now account for around 23% of Professional staff. But this is still too low. The progress seen to date is a result of joint efforts by you, the Member States, and the Secretariat. The creation of this group - the Member States Points of Contact - has been key. Sixty Member States have designated Points of Contact. This means, however, that a surprisingly large number of countries, including some Board members, have not yet joined. I encourage them to sign up today. As Director General, I would like to see more women in senior positions and I want Agency staff to be recruited from as broad a geographical distribution as possible. In my first few months in office, I have already made special efforts to recruit women to Professional positions, with some success. My first concern is naturally to recruit the best qualified person. However, in selection processes I will always give prominent consideration to the need to proactively increase the number of women working in the Secretariat. More and more women are now working in the nuclear industry as engineers, managers, inspectors, chemists, physicists and environmentalists. But I must tell you honestly: while it is difficult to find well-qualified women for P-positions in the Agency, it is particularly difficult to find suitable female candidates for more senior posts. We very much need your help in getting the message out to highly-qualified women with long experience of the nuclear sector that the Agency is a great place to work. Change will not happen overnight

Experimental quantification of contact forces with impact, friction and uncertainty analysis

DEFF Research Database (Denmark)

Lahriri, Said; Santos, Ilmar

2013-01-01

and whirl motions in rotor-stator contact investigations. Dry friction coefficient is therefore estimated using two different experimental setups: (a) standard pin-on-disk tests and (b) rotor impact test rig fully instrumented. The findings in both setups indicate that the dry friction coefficient for brass......During rotor-stator contact dry friction plays a significant role in terms of reversing the rotor precession. The frictional force causes an increase in the rotor's tangential velocity in the direction opposite to that of the angular velocity. This effect is crucial for defining ranges of dry whip......-aluminum configuration significantly varies in a range of 0.16-0.83. The rotor enters a full annular contact mode shortly after two impacts with a contact duration of approximately 0.004 s at each location. It is experimentally demonstrated that the friction force is not present when the rotor enters a full annular...

Ferromagnetic Spin Coupling as the Origin of 0.7 Anomaly in Quantum Point Contacts

OpenAIRE

Aryanpour, K.; Han, J. E.

2008-01-01

We study one-dimensional itinerant electron models with ferromagnetic coupling to investigate the origin of 0.7 anomaly in quantum point contacts. Linear conductance calculations from the quantum Monte Carlo technique for spin interactions of different spatial range suggest that $0.7(2e^{2}/h)$ anomaly results from a strong interaction of low-density conduction electrons to ferromagnetic fluctuations formed across the potential barrier. The conductance plateau appears due to the strong incohe...

Contact Lens Related Corneal Ulcer

OpenAIRE

Loh, KY; Agarwal, P

2010-01-01

A corneal ulcer caused by infection is one of the major causes of blindness worldwide. One of the recent health concerns is the increasing incidence of corneal ulcers associated with contact lens user especially if the users fail to follow specific instruction in using their contact lenses. Risk factors associated with increased risk of contact lens related corneal ulcers are: overnight wear, long duration of continuous wear, lower socio-economic classes, smoking, dry eye and poor hygiene. Th...

Microscopic origin of the 1.3 G0 conductance observed in oxygen-doped silver quantum point contacts

KAUST Repository

Tu, Xingchen; Wang, Minglang; Sanvito, Stefano; Hou, Shimin

2014-01-01

© 2014 AIP Publishing LLC. Besides the peak at one conductance quantum, G0, two additional features at ∼0.4 G0 and ∼1.3 G0 have been observed in the conductance histograms of silver quantum point contacts at room temperature in ambient conditions

Evaluation of Heat Flux Measurement as a New Process Analytical Technology Monitoring Tool in Freeze Drying.

Science.gov (United States)

Vollrath, Ilona; Pauli, Victoria; Friess, Wolfgang; Freitag, Angelika; Hawe, Andrea; Winter, Gerhard

2017-05-01

This study investigates the suitability of heat flux measurement as a new technique for monitoring product temperature and critical end points during freeze drying. The heat flux sensor is tightly mounted on the shelf and measures non-invasively (no contact with the product) the heat transferred from shelf to vial. Heat flux data were compared to comparative pressure measurement, thermocouple readings, and Karl Fischer titration as current state of the art monitoring techniques. The whole freeze drying process including freezing (both by ramp freezing and controlled nucleation) and primary and secondary drying was considered. We found that direct measurement of the transferred heat enables more insights into thermodynamics of the freezing process. Furthermore, a vial heat transfer coefficient can be calculated from heat flux data, which ultimately provides a non-invasive method to monitor product temperature throughout primary drying. The end point of primary drying determined by heat flux measurements was in accordance with the one defined by thermocouples. During secondary drying, heat flux measurements could not indicate the progress of drying as monitoring the residual moisture content. In conclusion, heat flux measurements are a promising new non-invasive tool for lyophilization process monitoring and development using energy transfer as a control parameter. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

A RANDOMIZED TRIAL TO STUDY THE COMPARISON OF TRIGGER POINT DRY NEEDLING VERSUS KINESIO TAPING TECHNIQUE IN MYOFASCIAL PAIN SYNDROME DURING A 3-MONTH FOLLOW UP

Directory of Open Access Journals (Sweden)

Emrullah Hayta

2016-10-01

Full Text Available Background: Managemen of myofascial pain syndrome (MPS is a current research subject since there is a small number of randomized studies comparing different management techniques. Multiple studies attempted to assess various treatment options including trigger point dry needling and kinesiotaping. We compared the effects of trigger point dry needling and kinesiotaping in the management of myofascial pain syndome during a 3-month follow-up period. Methods: In this prospective randomized studyin MPS patients with upper trapezius muscle trigger points, the effects of dry needling (n=28 and kinesiotaping (n=27 was compared with regard to the visual analog scale (VAS, neck disability index (NDI, and Nottingham health profile (NHP scores measured at the weeks 0, 4, and 12. Results: Both dry needling and kinesiotaping comparably reduced VAS scores measured at the weeks 4 and 12 and their efficacies were more remarkable at the week 12 (p<0.05. These interventions significantly reduced the NDI and NHP score and their effects were also more remarkable at the week 12; however, dry needling was found more effective (p<0.05. Conclusion: Overall, in current clinical settings, during the management of MPS, pain can be reduced comparably by both dry needling and kinesiotaping; however, restriction in the range of motionin neck region and quality of life are more remarkably reduced by dry needling. Both dry needling and kinesiotaping can provide an increasing effectiveness up to 12 weeks.

Observation of conductance doubling in an Andreev quantum point contact

Science.gov (United States)

Kjaergaard, M.; Nichele, F.; Suominen, H.; Nowak, M.; Wimmer, M.; Akhmerov, A.; Folk, J.; Flensberg, K.; Shabani, J.; Palmstrom, C.; Marcus, C.

One route to study the non-Abelian nature of excitations in topological superconductors is to realise gateable two dimensional (2D) semiconducting systems, with spin-orbit coupling in proximity to an s-wave superconductor. Previous work on coupling 2D electron gases (2DEG) with superconductors has been hindered by a non-ideal interface and unstable gateability. We report measurements on a gateable 2DEG coupled to superconductors through a pristine interface, and use aluminum grown in situ epitaxially on an InGaAs/InAs electron gas. We demonstrate quantization in units of 4e2 / h in a quantum point contact (QPC) in such hybrid systems. Operating the QPC as a tunnel probe, we observe a hard superconducting gap, overcoming the soft-gap problem in 2D superconductor/semiconductor systems. Our work paves way for a new and highly scalable system in which to pursue topological quantum information processing. Research supported by Microsoft Project Q and the Danish National Research Foundation.

Topographic and Electrochemical Ti6Al4V Alloy Surface Characterization in Dry and Wet Reciprocating Sliding

Directory of Open Access Journals (Sweden)

Z. Doni

2013-09-01

Full Text Available This present paper shows the behavior of functional integrity of the state Ti6Al4V alloy under reciprocating sliding wear conditions in acomparative way for two different counter materials, steel and ceramicballs in dry and corrosive environment (3.5% NaCl. The surface integrity analysis of the dry reciprocating wear tests was based on the evolution of The roughness parameters with the applied load. In the case of reciprocating wear tests in corrosive environment the surface integrity analysis was based on electrochemical parameters. Comparative analysis of the evolution of the roughness parameters with the applied load shows a higher stability of the Ti6Al4V/Al2O3 contact pair, while from the point of view of the electrochemical parameters the Tribological properties are worse than Ti6Al4V/steel ball contact pair.

Properties of a tunnel point contact between aluminum and the superconducting amorphous alloy NiZr2

International Nuclear Information System (INIS)

Gantmakher, V.F.; Golubov, A.A.; Osherov, M.V.

1989-01-01

The I-V characteristics of a tunnel point contact between aluminum and an amorphous ribbon resembling NiZr 2 in composition differ qualitatively from those of ordinary tunnel junctions between a superconductor and a normal metal. It is demonstrated that the observed curve shapes cannot be explained by accounting solely for one-particle tunneling in conditions of the proximity effect. This is followed by a qualitative discussion of a model in which the current rise at the potential eV equal to the gap width Δ (T) is generated by two-particle electron tunneling through the intermediate state which is manifested as a Cooper pair on the Fermi-level in the thin superconducting layer produced in the aluminum by the proximity effect. The current flowing through the contact will cause a breakdown of superconductivity in the vicinity of the contact at voltages exceeding the gap width. Smallness of the junction plays a decisive role both in inducing superconductivity for eV Δ

Calculation of point-contact spectra for a simple heavy-fermion Hamiltonian by two approaches. Comparison of results

International Nuclear Information System (INIS)

Kupka, M.; Farkasovsky, P.C.

1992-01-01

Point-contact spectra have been calculated for normal metal -heavy-fermion metal system (described by means of a simplified model Hamiltonian). Two approaches are used: one of them states that the differential conductance reflects an energy-dependent quasi-particle density of states, and 2. one drives the differential conductance are compared

Adaptation Tipping Points of a Wetland under a Drying Climate

Directory of Open Access Journals (Sweden)

Amar Nanda

2018-02-01

Full Text Available Wetlands experience considerable alteration to their hydrology, which typically contributes to a decline in their overall ecological integrity. Wetland management strategies aim to repair wetland hydrology and attenuate wetland loss that is associated with climate change. However, decision makers often lack the data needed to support complex social environmental systems models, making it difficult to assess the effectiveness of current or past practices. Adaptation Tipping Points (ATPs is a policy-oriented method that can be useful in these situations. Here, a modified ATP framework is presented to assess the suitability of ecosystem management when rigorous ecological data are lacking. We define the effectiveness of the wetland management strategy by its ability to maintain sustainable minimum water levels that are required to support ecological processes. These minimum water requirements are defined in water management and environmental policy of the wetland. Here, we trial the method on Forrestdale Lake, a wetland in a region experiencing a markedly drying climate. ATPs were defined by linking key ecological objectives identified by policy documents to threshold values for water depth. We then used long-term hydrologic data (1978–2012 to assess if and when thresholds were breached. We found that from the mid-1990s, declining wetland water depth breached ATPs for the majority of the wetland objectives. We conclude that the wetland management strategy has been ineffective from the mid-1990s, when the region’s climate dried markedly. The extent of legislation, policies, and management authorities across different scales and levels of governance need to be understood to adapt ecosystem management strategies. Empirical verification of the ATP assessment is required to validate the suitability of the method. However, in general we consider ATPs to be a useful desktop method to assess the suitability of management when rigorous ecological data

Irritant Contact Dermatitis : Diagnosis and Risk Factors

NARCIS (Netherlands)

Schuttelaar, Maria; Johansen, Jeanne Duus; Lepoittevin, Jean-Pierre; Thyssen, Jacob P.

2016-01-01

Irritant contact dermatitis is frequent and is induced by direct and repeated contact with skin irritants such as detergents, abrasives, solvents and physical factors such as dry air and occlusion (by wearing gloves) but also water. When dermatitis has developed, even a minimal skin irritation, like

Non-contact assessment of electrical performance for rapidly sintered nanoparticle silver coatings through colorimetry

Energy Technology Data Exchange (ETDEWEB)

Cherrington, M.; Claypole, T.C.; Gethin, D.T. [Welsh Centre for Printing and Coating, College of Engineering, Swansea University, Singleton Park, Swansea, SA2 8PP (United Kingdom); Worsley, D.A. [SPECIFIC, College of Engineering, Swansea University, Baglan Bay Innovation Centre, Central Avenue, Baglan Energy Park, Port Talbot, SA12 7AX (United Kingdom); Deganello, D., E-mail: d.deganello@swansea.ac.uk [Welsh Centre for Printing and Coating, College of Engineering, Swansea University, Singleton Park, Swansea, SA2 8PP (United Kingdom)

2012-11-01

The color change during the ultrafast near-infrared sintering process of a nanoparticle silver ink has been correlated to its electrical performance through colorimetry using the CIELAB industry standard. Nanoparticle silver ink films, deposited over a flexible polyethylene terephthalate substrate, presented significant shifting in the a* and b* color coordinates during sintering, exhibiting the best conductivity with an a* coordinate of approximately 0 and a b* coordinate of approximately + 10. This color change has been associated with the Lorenz-Mie theory of electromagnetic scattering. This indirect measurement technique is potentially a breakthrough technology for fast in-line non-contact characterization of the drying and sintering process of nanoparticle conductive inks for use in large area roll-to-roll processing of printed electronics. - Highlights: Black-Right-Pointing-Pointer Color change of a nanoparticle silver coating was measured during sintering Black-Right-Pointing-Pointer Color change was correlated to the electrical performance of the coating. Black-Right-Pointing-Pointer Potential in-line non-contact measurement method for roll-to-roll printed electronics.

Al-Si alloy point contact formation and rear surface passivation for silicon solar cells using double layer porous silicon

International Nuclear Information System (INIS)

Moumni, Besma; Ben Jaballah, Abdelkader; Bessais, Brahim

2012-01-01

Lowering the rear surface recombination velocities by a dielectric layer has fascinating advantages compared with the standard fully covered Al back-contact silicon solar cells. In this work the passivation effect by double layer porous silicon (PS) (wide band gap) and the formation of Al-Si alloy in narrow p-type Si point contact areas for rear passivated solar cells are analysed. As revealed by Fourier transform infrared spectroscopy, we found that a thin passivating aluminum oxide (Al 2 O 3 ) layer is formed. Scanning electron microscopy analysis performed in cross sections shows that with bilayer PS, liquid Al penetrates into the openings, alloying with the Si substrate at depth and decreasing the contact resistivity. At the solar cell level, the reduction in the contact area and resistivity leads to a minimization of the fill factor losses.

Ferromagnetic spin coupling as the origin of 0.7 anomaly in quantum point contacts.

Science.gov (United States)

Aryanpour, K; Han, J E

2009-02-06

We study one-dimensional itinerant electron models with ferromagnetic coupling to investigate the origin of the 0.7 anomaly in quantum point contacts. Linear conductance calculations from the quantum Monte Carlo technique for spin interactions of different spatial range suggest that 0.7(2e;{2}/h) anomaly results from a strong interaction of low-density conduction electrons to ferromagnetic fluctuations formed across the potential barrier. The conductance plateau appears due to the strong incoherent scattering at high temperature when the electron traversal time matches the time scale of dynamic ferromagnetic excitations.

Point-contact electron tunneling into the high-Tc superconductor Y-Ba-Cu-O

Science.gov (United States)

Kirk, M. D.; Smith, D. P. E.; Mitzi, D. B.; Sun, J. Z.; Webb, D. J.

1987-06-01

Results are reported from a study of electron tunneling into bulk samples of the new high-Tc superconductor Y-Ba-Cu-O using point-contact tunneling. Based on a superconductive tunneling interpretation, the results show exceptionally large energy gaps in these materials (roughly 2Delta = 100 MeV), implying 2Delta/kBTc = about 13. Similar values were found for La-Sr-Cu-O. The structure in the I-V curves is also similar to that seen in La-Sr-Cu-O. From the asymmetries observed in the I-V characteristics, it is inferred that the natural tunneling barrier on this material is of the Schottky type.

Effect of direct contact with iron on gas evolution behavior of aluminum

International Nuclear Information System (INIS)

Hashizume, Shuji; Matsumoto, Junko; Banba, Tsunetaka

1998-01-01

Dry Low-Level Radioactive Waste (LLW), incombustible solid LLW, generated from nuclear power stations is planed to be solidified with cement backfill in drums. The solidified dry LLW will be buried to shallow underground at Rokkasyo LLW Disposal Center. It is well known that corrosion of aluminum and hydrogen gas evolution occur in high pH environments such as mortar. Gas evolution from aluminum is likely to effect the leachability of solidified dry LLW with mortar. Though aluminum removal from dry LLW is planed, a small amount of aluminum will be actually included in dry LLW. Large effects of pH and temperature on corrosion rate of aluminum and gas evolution were recognized in our previous study. It was also found that 1.5 mole hydrogen gas evolves while 1 mole aluminum corrodes under 60degC. Actually aluminum in drums is likely to contact with carbon steel of which main element is iron. The gas evolution behavior of aluminum is expected to be affected by its direct contact with iron. Therefore, effect of direct contact with iron on gas evolution behavior of aluminum was studied. The corrosion rate of aluminum increased by contacting it with iron in simulating mortar environments. The amount of gas evolution from aluminum was reduced by contacting with iron. The reduction in gas evolution was considered to result from the change of cathode reaction from hydrogen evolution to oxygen reduction. When aluminum contacts with iron, the corrosion and gas evolution behavior of aluminum is significantly affected oxygen in environment. (author)

Possible origin of the 0.5 plateau in the ballistic conductance of quantum point contacts

OpenAIRE

Wan, J.; Cahay, M.; Debray, P.; Newrock, R.

2009-01-01

A non-equilibrium Green function formalism (NEGF) is used to study the conductance of a side-gated quantum point contact (QPC) in the presence of lateral spin-orbit coupling (LSOC). A small difference of bias voltage between the two side gates (SGs) leads to an inversion asymmetry in the LSOC between the opposite edges of the channel. In single electron modeling of transport, this triggers a spontaneous but insignificant spin polarization in the QPC. However, the spin polarization of the QPC ...

Drop rebound after impact: the role of the receding contact angle.

Science.gov (United States)

Antonini, C; Villa, F; Bernagozzi, I; Amirfazli, A; Marengo, M

2013-12-31

Data from the literature suggest that the rebound of a drop from a surface can be achieved when the wettability is low, i.e., when contact angles, measured at the triple line (solid-liquid-air), are high. However, no clear criterion exists to predict when a drop will rebound from a surface and which is the key wetting parameter to govern drop rebound (e.g., the "equilibrium" contact angle, θeq, the advancing and the receding contact angles, θA and θR, respectively, the contact angle hysteresis, Δθ, or any combination of these parameters). To clarify the conditions for drop rebound, we conducted experimental tests on different dry solid surfaces with variable wettability, from hydrophobic to superhydrophobic surfaces, with advancing contact angles 108° contact angles 89° contact angle is the key wetting parameter that influences drop rebound, along with surface hydrophobicity: for the investigated impact conditions (drop diameter 2.4 contact angles higher than 100°. Also, the drop rebound time decreased by increasing the receding contact angle. It was also shown that in general care must be taken when using statically defined wetting parameters (such as advancing and receding contact angles) to predict the dynamic behavior of a liquid on a solid surface because the dynamics of the phenomenon may affect surface wetting close to the impact point (e.g., as a result of the transition from the Cassie-Baxter to Wenzel state in the case of the so-called superhydrophobic surfaces) and thus affect the drop rebound.

Fingerprints of bosonic symmetry protected topological state in a quantum point contact

Science.gov (United States)

Zhang, Rui-Xing; Liu, Chao-Xing

In this work, we study the transport through a quantum point contact for two-channel interacting helical liquids that exist at the edge of a bilayer graphene under a strong magnetic field. We identify ``smoking gun'' transport signatures to distinguish bosonic symmetry protected topological (BSPT) state from fermionic two-channel quantum spin Hall (QSH) state in this system. In particular, a novel charge insulator/spin conductor phase is found for a weak repulsive interaction in the BSPT state, while either charge insulator/spin insulator or charge conductor/spin conductor phase is expected for the two-channel QSH state. In the strong interaction limit, shot noise measurement for the BSPT state is expect to reveal charge-2e instanton tunneling, in comparison with the charge-e tunneling in the two-channel QSH phase.

Dried fruit and its functional properties from a consumer's point of view

NARCIS (Netherlands)

Jesionkowska, K.; Sijtsema, S.J.; Konopacka, D.; Symoneaux, R.

2009-01-01

Modern drying technology provides the opportunity to obtain dried fruits with high concentrations of bioactive compounds. Such products may also be fortified with functional ingredients. The adoption of dried fruit as a carrier of functional ingredients for consumers is indispensable to launch this

Quantum qubit measurement by a quantum point contact with a quantum Langevin equation approach

International Nuclear Information System (INIS)

Dong, Bing; Lei, X.L.; Horing, N.J.M.; Cui, H.L.

2007-01-01

We employ a microscopic quantum Heisenberg-Langevin equation approach to establish a set of quantum Bloch equations for a two-level system (coupled quantum dots) capacitively coupled to a quantum point contact (QPC). The resulting Bloch equations facilitate our analysis of qubit relaxation and decoherence in coupled quantum dots induced by measurement processes at arbitrary bias-voltage and temperature. We also examine the noise spectrum of the meter output current for a symmetric qubit. These results help resolve a recent debate about a quantum oscillation peak in the noise spectrum. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

On the estimation of the spherical contact distribution Hs(y) for spatial point processes

International Nuclear Information System (INIS)

Doguwa, S.I.

1990-08-01

RIPLEY (1977, Journal of the Royal Statistical Society, B39 172-212) proposed an estimator for the spherical contact distribution H s (s), of a spatial point process observed in a bounded planar region. However, this estimator is not defined for some distances of interest, in this bounded region. A new estimator for H s (y), is proposed for use with regular grid of sampling locations. This new estimator is defined for all distances of interest. It also appears to have a smaller bias and a smaller mean squared error than the previously suggested alternative. (author). 11 refs, 4 figs, 1 tab

Fingerprints of a Bosonic Symmetry-Protected Topological State in a Quantum Point Contact

Science.gov (United States)

Zhang, Rui-Xing; Liu, Chao-Xing

2017-05-01

In this work, we study the transport through a quantum point contact for bosonic helical liquid that exists at the edge of a bilayer graphene under a strong magnetic field. We identify "smoking gun" transport signatures to distinguish a bosonic symmetry-protected topological (BSPT) state from a fermionic two-channel quantum spin Hall (QSH) state in this system. In particular, a novel charge-insulator-spin-conductor phase is found for the BSPT state, while either the charge-insulator-spin-insulator or the charge-conductor-spin-conductor phase is expected for the two-channel QSH state. Consequently, a simple transport measurement will reveal the fingerprint of bosonic topological physics in bilayer graphene systems.

Scanning electron microscope autoradiography of critical point dried biological samples

International Nuclear Information System (INIS)

Weiss, R.L.

1980-01-01

A technique has been developed for the localization of isotopes in the scanning electron microscope. Autoradiographic studies have been performed using a model system and a unicellular biflagellate alga. One requirement of this technique is that all manipulations be carried out on samples that are maintained in a liquid state. Observations of a source of radiation ( 125 I-ferritin) show that the nuclear emulsion used to detect radiation is active under these conditions. Efficiency measurement performed using 125 I-ferritin indicate that 125 I-SEM autoradiography is an efficient process that exhibits a 'dose dependent' response. Two types of labeling methods were used with cells, surface labeling with 125 I and internal labeling with 3 H. Silver grains appeared on labeled cells after autoradiography, removal of residual gelatin and critical point drying. The location of grains was examined on a flagellated green alga (Chlamydomonas reinhardi) capable of undergoing cell fusion. Fusion experiments using labeled and unlabeled cells indicate that 1. Labeling is specific for incorporated radioactivity; 2. Cell surface structure is preserved in SEM autoradiographs and 3. The technique appears to produce reliable autoradiographs. Thus scanning electron microscope autoradiography should provide a new and useful experimental approach

Macro-mechanics controls quantum mechanics: mechanically controllable quantum conductance switching of an electrochemically fabricated atomic-scale point contact.

Science.gov (United States)

Staiger, Torben; Wertz, Florian; Xie, Fangqing; Heinze, Marcel; Schmieder, Philipp; Lutzweiler, Christian; Schimmel, Thomas

2018-01-12

Here, we present a silver atomic-scale device fabricated and operated by a combined technique of electrochemical control (EC) and mechanically controllable break junction (MCBJ). With this EC-MCBJ technique, we can perform mechanically controllable bistable quantum conductance switching of a silver quantum point contact (QPC) in an electrochemical environment at room temperature. Furthermore, the silver QPC of the device can be controlled both mechanically and electrochemically, and the operating mode can be changed from 'electrochemical' to 'mechanical', which expands the operating mode for controlling QPCs. These experimental results offer the perspective that a silver QPC may be used as a contact for a nanoelectromechanical relay.

Macro-mechanics controls quantum mechanics: mechanically controllable quantum conductance switching of an electrochemically fabricated atomic-scale point contact

Science.gov (United States)

Staiger, Torben; Wertz, Florian; Xie, Fangqing; Heinze, Marcel; Schmieder, Philipp; Lutzweiler, Christian; Schimmel, Thomas

2018-01-01

Here, we present a silver atomic-scale device fabricated and operated by a combined technique of electrochemical control (EC) and mechanically controllable break junction (MCBJ). With this EC-MCBJ technique, we can perform mechanically controllable bistable quantum conductance switching of a silver quantum point contact (QPC) in an electrochemical environment at room temperature. Furthermore, the silver QPC of the device can be controlled both mechanically and electrochemically, and the operating mode can be changed from ‘electrochemical’ to ‘mechanical’, which expands the operating mode for controlling QPCs. These experimental results offer the perspective that a silver QPC may be used as a contact for a nanoelectromechanical relay.

Probing dopants in wide semiconductor quantum point contacts

International Nuclear Information System (INIS)

Yakimenko, I I; Berggren, K-F

2016-01-01

Effects of randomly distributed impurities on conductance, spin polarization and electron localization in realistic gated semiconductor quantum point contacts (QPCs) have been simulated numerically. To this end density functional theory in the local spin-density approximation has been used. In the case when the donor layer is embedded far from the two-dimensional electron gas (2DEG) the electrostatic confinement potential exhibits the conventional parabolic form, and thus the usual ballistic transport phenomena take place both in the devices with split gates alone and with an additional metallic gate on the top. In the opposite case, i.e. when the randomly distributed donors are placed not far away from the 2DEG layer, there are drastic changes like the localization of electrons in the vicinity of confinement potential minima which give rise to fluctuations in conductance and resonances. The conductance as a function of the voltage applied to the top gate for asymmetrically charged split gates has been calculated. In this case resonances in conductance caused by randomly distributed donors are shifted and decrease in amplitude while the anomalies caused by interaction effects remain unmodified. It has been also shown that for a wide QPC the polarization can appear in the form of stripes. The importance of partial ionization of the random donors and the possibility of short range order among the ionized donors are emphasized. The motivation for this work is to critically evaluate the nature of impurities and how to guide the design of high-mobility devices. (paper)

Scalable and continuous fabrication of bio-inspired dry adhesives with a thermosetting polymer.

Science.gov (United States)

Lee, Sung Ho; Kim, Sung Woo; Kang, Bong Su; Chang, Pahn-Shick; Kwak, Moon Kyu

2018-04-04

Many research groups have developed unique micro/nano-structured dry adhesives by mimicking the foot of the gecko with the use of molding methods. Through these previous works, polydimethylsiloxane (PDMS) has been developed and become the most commonly used material for making artificial dry adhesives. The material properties of PDMS are well suited for making dry adhesives, such as conformal contacts with almost zero preload, low elastic moduli for stickiness, and easy cleaning with low surface energy. From a performance point of view, dry adhesives made with PDMS can be highly advantageous but are limited by its low productivity, as production takes an average of approximately two hours. Given the low productivity of PDMS, some research groups have developed dry adhesives using UV-curable materials, which are capable of continuous roll-to-roll production processes. However, UV-curable materials were too rigid to produce good adhesion. Thus, we established a PDMS continuous-production system to achieve good productivity and adhesion performance. We designed a thermal roll-imprinting lithography (TRL) system for the continuous production of PDMS microstructures by shortening the curing time by controlling the curing temperature (the production speed is up to 150 mm min-1). Dry adhesives composed of PDMS were fabricated continuously via the TRL system.

Effectiveness of trigger point dry needling for plantar heel pain: study protocol for a randomised controlled trial

Directory of Open Access Journals (Sweden)

Landorf Karl B

2011-01-01

be reported in accordance with the Consolidated Standards of Reporting Trials and the Standards for Reporting Interventions in Clinical Trials of Acupuncture guidelines. The findings from this trial will provide evidence for the effectiveness of trigger point dry needling for plantar heel pain. Trial registration Australian New Zealand 'Clinical Trials Registry'. ACTRN12610000611022.

Blades Couple Dry Friction Connection

Czech Academy of Sciences Publication Activity Database

Půst, Ladislav; Pešek, Luděk; Radolfová, Alena

2015-01-01

Roč. 9, č. 1 (2015), s. 31-40 ISSN 1802-680X Institutional support: RVO:61388998 Keywords : stick-slip dry friction * 3D friction characteristic * tangential contact stiffness * hysterezis loop * response curves Subject RIV: BI - Acoustics

Review of laboratory programs for women Points-of-Contact Committee

Energy Technology Data Exchange (ETDEWEB)

Duke, D.; Magrini, K. [comps.] [National Renewable Energy Lab., Golden, CO (United States); McLane, V. [comp.] [Brookhaven National Lab., Upton, NY (United States); Wieda, K. [comp.] [Pacific Northwest Lab., Richland, WA (United States)

1995-06-01

The mission of the DOE Review of Laboratory Programs for Women is to: provide DOE and its Laboratories with effective strategies, targeting women, for establishing aggressive outreach programs which improve the access of women to careers in science, engineering, and mathematics. Ensure that the Department and its Laboratories are exemplary places of employment by providing programs which enhance opportunity, remove barriers, and assist women in achieving full professional development. A survey of the DOE facilities was undertaken by the Points-of-Contact for the DOE Review of Laboratory Programs for Women in order to gather data to be used as a baseline against which to measure future progress. We plan to look at current programs already in place and evaluate them with a view to deciding which programs are most effective, and selecting model programs suitable for implementation at other facilities. The survey focused on four areas: statistical data, laboratory policy, formal and informal programs which affect the quality of life in the work environment, and career development and advancement, and educational programs. Although this report focuses on women, the problems discussed affect all DOE facility employees.

Search for Pauli exclusion principle violating atomic transitions and electron decay with a p-type point contact germanium detector

Energy Technology Data Exchange (ETDEWEB)

Abgrall, N.; Bradley, A.W.; Chan, Y.D.; Mertens, S.; Poon, A.W.P. [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Arnquist, I.J.; Hoppe, E.W.; Kouzes, R.T.; LaFerriere, B.D.; Orrell, J.L. [Pacific Northwest National Laboratory, Richland, WA (United States); Avignone, F.T. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); University of South Carolina, Department of Physics and Astronomy, Columbia, SC (United States); Barabash, A.S.; Konovalov, S.I.; Yumatov, V. [National Research Center ' ' Kurchatov Institute' ' Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Bertrand, F.E.; Galindo-Uribarri, A.; Radford, D.C.; Varner, R.L.; White, B.R.; Yu, C.H. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); Brudanin, V.; Shirchenko, M.; Vasilyev, S.; Yakushev, E.; Zhitnikov, I. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Busch, M. [Duke University, Department of Physics, Durham, NC (United States); Triangle Universities Nuclear Laboratory, Durham, NC (United States); Buuck, M.; Cuesta, C.; Detwiler, J.A.; Gruszko, J.; Guinn, I.S.; Leon, J.; Robertson, R.G.H. [University of Washington, Department of Physics, Center for Experimental Nuclear Physics and Astrophysics, Seattle, WA (United States); Caldwell, A.S.; Christofferson, C.D.; Dunagan, C.; Howard, S.; Suriano, A.M. [South Dakota School of Mines and Technology, Rapid City, SD (United States); Chu, P.H.; Elliott, S.R.; Goett, J.; Massarczyk, R.; Rielage, K. [Los Alamos National Laboratory, Los Alamos, NM (United States); Efremenko, Yu. [University of Tennessee, Department of Physics and Astronomy, Knoxville, TN (United States); Ejiri, H. [Osaka University, Research Center for Nuclear Physics, Ibaraki, Osaka (Japan); Finnerty, P.S.; Gilliss, T.; Giovanetti, G.K.; Henning, R.; Howe, M.A.; MacMullin, J.; Meijer, S.J.; O' Shaughnessy, C.; Rager, J.; Shanks, B.; Trimble, J.E.; Vorren, K.; Xu, W. [Triangle Universities Nuclear Laboratory, Durham, NC (United States); University of North Carolina, Department of Physics and Astronomy, Chapel Hill, NC (United States); Green, M.P. [North Carolina State University, Department of Physics, Raleigh, NC (United States); Oak Ridge National Laboratory, Oak Ridge, TN (United States); Triangle Universities Nuclear Laboratory, Durham, NC (United States); Guiseppe, V.E.; Tedeschi, D.; Wiseman, C. [University of South Carolina, Department of Physics and Astronomy, Columbia, SC (United States); Jasinski, B.R. [University of South Dakota, Department of Physics, Vermillion, SD (United States); Keeter, K.J. [Black Hills State University, Department of Physics, Spearfish, SD (United States); Kidd, M.F. [Tennessee Tech University, Cookeville, TN (United States); Martin, R.D. [Queen' s University, Department of Physics, Engineering Physics and Astronomy, Kingston, ON (Canada); Romero-Romero, E. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); University of Tennessee, Department of Physics and Astronomy, Knoxville, TN (United States); Vetter, K. [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA (United States); University of California, Department of Nuclear Engineering, Berkeley, CA (United States); Wilkerson, J.F. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); Triangle Universities Nuclear Laboratory, Durham, NC (United States); University of North Carolina, Department of Physics and Astronomy, Chapel Hill, NC (United States)

2016-11-15

A search for Pauli-exclusion-principle-violating K{sub α} electron transitions was performed using 89.5 kg-d of data collected with a p-type point contact high-purity germanium detector operated at the Kimballton Underground Research Facility. A lower limit on the transition lifetime of 5.8 x 10{sup 30} s at 90% C.L. was set by looking for a peak at 10.6 keV resulting from the X-ray and Auger electrons present following the transition. A similar analysis was done to look for the decay of atomic K-shell electrons into neutrinos, resulting in a lower limit of 6.8 x 10{sup 30} s at 90% C.L. It is estimated that the Majorana Demonstrator, a 44 kg array of p-type point contact detectors that will search for the neutrinoless double-beta decay of {sup 76}Ge, could improve upon these exclusion limits by an order of magnitude after three years of operation. (orig.)

Multi-valued logic gates based on ballistic transport in quantum point contacts.

Science.gov (United States)

Seo, M; Hong, C; Lee, S-Y; Choi, H K; Kim, N; Chung, Y; Umansky, V; Mahalu, D

2014-01-22

Multi-valued logic gates, which can handle quaternary numbers as inputs, are developed by exploiting the ballistic transport properties of quantum point contacts in series. The principle of a logic gate that finds the minimum of two quaternary number inputs is demonstrated. The device is scalable to allow multiple inputs, which makes it possible to find the minimum of multiple inputs in a single gate operation. Also, the principle of a half-adder for quaternary number inputs is demonstrated. First, an adder that adds up two quaternary numbers and outputs the sum of inputs is demonstrated. Second, a device to express the sum of the adder into two quaternary digits [Carry (first digit) and Sum (second digit)] is demonstrated. All the logic gates presented in this paper can in principle be extended to allow decimal number inputs with high quality QPCs.

Multi-Valued Logic Gates based on Ballistic Transport in Quantum Point Contacts

Science.gov (United States)

Seo, M.; Hong, C.; Lee, S.-Y.; Choi, H. K.; Kim, N.; Chung, Y.; Umansky, V.; Mahalu, D.

2014-01-01

Multi-valued logic gates, which can handle quaternary numbers as inputs, are developed by exploiting the ballistic transport properties of quantum point contacts in series. The principle of a logic gate that finds the minimum of two quaternary number inputs is demonstrated. The device is scalable to allow multiple inputs, which makes it possible to find the minimum of multiple inputs in a single gate operation. Also, the principle of a half-adder for quaternary number inputs is demonstrated. First, an adder that adds up two quaternary numbers and outputs the sum of inputs is demonstrated. Second, a device to express the sum of the adder into two quaternary digits [Carry (first digit) and Sum (second digit)] is demonstrated. All the logic gates presented in this paper can in principle be extended to allow decimal number inputs with high quality QPCs.

Onset of Spin Polarization in Four-Gate Quantum Point Contacts

Science.gov (United States)

Jones, Alex

A series of simulations which utilize a Non-equilibrium Green's function (NEGF) formalism is suggested which can provide indirect evidence of the fine and non-local electrostatic tuning of the onset of spin polarization in two closely spaced quantum point contacts (QPCs) that experience a phenomenon known as lateral spin-orbit coupling (LSOC). Each of the QPCs that create the device also has its own pair of side gates (SGs) which are in-plane with the device channel. Numerical simulations of the conductance of the two closely spaced QPCs or four-gate QPC are carried out for different biasing conditions applied to two leftmost and rightmost SGs. Conductance plots are then calculated as a function of the variable, Vsweep, which is the common sweep voltage applied to the QPC. When Vsweep is only applied to two of the four side gates, the plots show several conductance anomalies, i.e., below G0 = 2e2/h, characterized by intrinsic bistability, i.e., hysteresis loops due to a difference in the conductance curves for forward and reverse common voltage sweep simulations. The appearance of hysteresis loops is attributed to the co-existence of multistable spin textures in the narrow channel of the four-gate QPC. The shape, location, and number of hysteresis loops are very sensitive to the biasing conditions on the four SGs. The shape and size of the conductance anomalies and hysteresis loops are shown to change when the biasing conditions on the leftmost and rightmost SGs are swapped, a rectifying behavior providing an additional indirect evidence for the onset of spontaneous spin polarization in nanoscale devices made of QPCs. The results of the simulations reveal that the occurrence and fine tuning of conductance anomalies in QPC structures are highly sensitive to the non-local action of closely spaced SGs. It is therefore imperative to take into account this proximity effect in the design of all electrical spin valves making use of middle gates to fine tune the spin

Therapeutic efficiency of sodium hyaluronate eye drops on dry eye in juvenile with myopia wearing rigid gas permeable contact lens

Directory of Open Access Journals (Sweden)

Bin Zhang

2016-03-01

Full Text Available AIM:To investigate the therapeutic efficiency of preservative-free sodium hyaluronate eye drops on dry eye in juvenile myopia wearing rigid gas permeable contact lens(RGP.METHODS:Ninety cases with dry eye related to wearing RGP in juvenile with myopia from January to May 2015 were selected. The patients aged 12.75±4.15 years old,with diopter of -3.50±1.50D as spherical equivalent and received normalized RGP. They were divided into 3 groups randomly,each group of 30 cases(60 eyes:group A used rewetting drops,1 drop each time,4 times per day; group B used preservative-free sodium hyaluronate eye drops(1g/L,1 drop each time,4 times per day; group C used rewetting drops at first, then sodium hyaluronate eye drops was used 15 minutes later.All cases had been detected and evaluated by subjective symptoms of dry eye,Schirmer I test(SⅠt,break-up time(BUTand corneal fluorescent staining,at pre-therapy and 1, 2, 4wk of post-therapy.RESULTS:The subjective symptoms of dry eye,corneal fluorescent staining and BUT of three groups had been obviously improved at 1wk after therapies than those before therapies(PP>0.05.Every index of the three groups measured at 2 and 4wk after treatments had no significant differences compared to those measured at 1wk(P>0.05.There was no significant difference on subjective symptoms,SⅠt and BUT between group A and B(P>0.05,except on corneal fluorescent staining, on which group B was superior to group A and on which the difference was significant(PPPCONCLUSION:Preservative-free sodium hyaluronate eye drops(1g/Lcan stabilize the tear film and promote the repair of corneal epithelial defects and significantly improve dry eye symptoms and signs in juvenile myopia wearing RGP,so it has certain clinical application value.

Assessment of methods for computing the closest point projection, penetration, and gap functions in contact searching problems

Czech Academy of Sciences Publication Activity Database

Kopačka, Ján; Gabriel, Dušan; Plešek, Jiří; Ulbin, M.

2016-01-01

Roč. 105, č. 11 (2016), s. 803-833 ISSN 0029-5981 R&D Projects: GA ČR(CZ) GAP101/12/2315; GA MŠk(CZ) ME10114 Institutional support: RVO:61388998 Keywords : closest point projection * local contact search * quadratic elements * Newtons methods * geometric iteration methods * simplex method Subject RIV: JC - Computer Hardware ; Software Impact factor: 2.162, year: 2016 http://onlinelibrary.wiley.com/doi/10.1002/nme.4994/abstract

Friction and wear behavior of nitrogen-doped ZnO thin films deposited via MOCVD under dry contact

Directory of Open Access Journals (Sweden)

U.S. Mbamara

2016-06-01

Full Text Available Most researches on doped ZnO thin films are tilted toward their applications in optoelectronics and semiconductor devices. Research on their tribological properties is still unfolding. In this work, nitrogen-doped ZnO thin films were deposited on 304 L stainless steel substrate from a combination of zinc acetate and ammonium acetate precursor by MOCVD technique. Compositional and structural studies of the films were done using Rutherford Backscattering Spectroscopy (RBS and X-ray Diffraction (XRD. The frictional behavior of the thin film coatings was evaluated using a ball-on-flat configuration in reciprocating sliding under dry contact condition. After friction test, the flat and ball counter-face surfaces were examined to assess the wear dimension and failure mechanism. Both friction behavior and wear (in the ball counter-face were observed to be dependent on the crystallinity and thickness of the thin film coatings.

CONTACT ANGLE OF YUCCA MOUNTAIN WELDED TUFF WITH WATER AND BRINES

International Nuclear Information System (INIS)

H. Kalia

2006-01-01

A number of tests were performed to acquire contact angles between Yucca Mountain welded tuff from Topopah Springs Lower Lithophysal geologic unit and various brine solutions. The tests were performed on core disks received from Sample Management Facility (SMF), oven dried to a constant weight and the core disks vacuum saturated in: distilled water, J-13 water, calcium chloride brine and sodium chloride brine to constant weight. The contact angles were acquired from eight points on the surface of the core disks, four on rough surface, and four on polished surface. The contact angle was measured by placing a droplet of the test fluid, distilled water, J-13 water, calcium chloride brine and sodium chloride brine on the core disks. The objective of this test was to acquire contact angles as a potential input to estimating capillary forces in accumulated dust on the waste packages and drip shields slated for the proposed High-Level Radioactive Waste Repository at Yucca Mountain, Nevada. It was noted that once the droplet contacts the test surface, it continues to spread hence the contact angle continues to decrease with elapsed time. The maximum observed angle was at time 0 or when the drop contacted the rock surface. The measured contact angle, in all cases has significant scatter. In general, the time zero contact angles for core disks saturated in sodium chloride brine were smaller than those saturated in calcium chloride brine, distilled water, and J-13 water. The contact angles for samples saturated in distilled water, J-13 water and calcium chloride brine at time zero were similar. There was slight difference between the observed contact angles for smooth and rough surface of the test samples. The contact angles for smooth surfaces were smaller than for the rough surfaces

Rapid, semi-automatic fracture and contact mapping for point clouds, images and geophysical data

Science.gov (United States)

Thiele, Samuel T.; Grose, Lachlan; Samsu, Anindita; Micklethwaite, Steven; Vollgger, Stefan A.; Cruden, Alexander R.

2017-12-01

The advent of large digital datasets from unmanned aerial vehicle (UAV) and satellite platforms now challenges our ability to extract information across multiple scales in a timely manner, often meaning that the full value of the data is not realised. Here we adapt a least-cost-path solver and specially tailored cost functions to rapidly interpolate structural features between manually defined control points in point cloud and raster datasets. We implement the method in the geographic information system QGIS and the point cloud and mesh processing software CloudCompare. Using these implementations, the method can be applied to a variety of three-dimensional (3-D) and two-dimensional (2-D) datasets, including high-resolution aerial imagery, digital outcrop models, digital elevation models (DEMs) and geophysical grids. We demonstrate the algorithm with four diverse applications in which we extract (1) joint and contact patterns in high-resolution orthophotographs, (2) fracture patterns in a dense 3-D point cloud, (3) earthquake surface ruptures of the Greendale Fault associated with the Mw7.1 Darfield earthquake (New Zealand) from high-resolution light detection and ranging (lidar) data, and (4) oceanic fracture zones from bathymetric data of the North Atlantic. The approach improves the consistency of the interpretation process while retaining expert guidance and achieves significant improvements (35-65 %) in digitisation time compared to traditional methods. Furthermore, it opens up new possibilities for data synthesis and can quantify the agreement between datasets and an interpretation.

Experience with a contact point (CP) for psychological and medical care after an NPP accident or another R/N disaster situation in Switzerland

International Nuclear Information System (INIS)

Baggenstos, M.A.; Frey, P.E.; Schmid, A.

2006-01-01

Mission The Swiss Federal Concept for Emergency Protection in the Vicinity of Nuclear Power Plants requires the preparation of a 'Contact Point' (C.P.) for psychological and medical care of the affected public in case of an accident in a nuclear power plant. Purpose The central questions, which during a release of radioactivity could cause anxiety within the population, are: - Have I come into contact with radioactive substances? - If so, what are the short-term and long-term radiological consequences? - How dangerous is the dose I have received? These questions are answered with the following procedures: - Examination of all persons arriving at the contact point with respect to radioactive contamination and, if necessary decontamination (showers). - Screening of the thyroid for the purpose of checking for incorporation of radioactive iodine and dose measurement in case screening is positive. - Answering of personal questions related to radioactivity and radiological consequences. - Information and advisory service concerning impact of radiation and possibilities of protective measures. Experience The Paper will discusses the experience from an exercise taken place 18./19. november 2005. In this exercise 100 players will be involved. The background of the exercise is a scenario taken from a federal exercise with a NPP. In addition to the direct support at the contact point a telephone hot line will be exercised. We expect lessons learned in man y areas of the management of psychological and medical care. (authors)

Contact Estimation in Robot Interaction

Directory of Open Access Journals (Sweden)

Filippo D'Ippolito

2014-07-01

Full Text Available In the paper, safety issues are examined in a scenario in which a robot manipulator and a human perform the same task in the same workspace. During the task execution, the human should be able to physically interact with the robot, and in this case an estimation algorithm for both interaction forces and a contact point is proposed in order to guarantee safety conditions. The method, starting from residual joint torque estimation, allows both direct and adaptive computation of the contact point and force, based on a principle of equivalence of the contact forces. At the same time, all the unintended contacts must be avoided, and a suitable post-collision strategy is considered to move the robot away from the collision area or else to reduce impact effects. Proper experimental tests have demonstrated the applicability in practice of both the post-impact strategy and the estimation algorithms; furthermore, experiments demonstrate the different behaviour resulting from the adaptation of the contact point as opposed to direct calculation.

Perspectives on setting limits for RF contact currents: a commentary.

Science.gov (United States)

Tell, Richard A; Tell, Christopher A

2018-01-15

Limits for exposure to radiofrequency (RF) contact currents are specified in the two dominant RF safety standards and guidelines developed by the Institute of Electrical and Electronics Engineers (IEEE) and the International Commission on Non-Ionizing Radiation Protection (ICNIRP). These limits are intended to prevent RF burns when contacting RF energized objects caused by high local tissue current densities. We explain what contact currents are and review some history of the relevant limits with an emphasis on so-called "touch" contacts, i.e., contact between a person and a contact current source during touch via a very small contact area. Contact current limits were originally set on the basis of controlling the specific absorption rate resulting from the current flowing through regions of small conductive cross section within the body, such as the wrist or ankle. More recently, contact currents have been based on thresholds of perceived heating. In the latest standard from the IEEE developed for NATO, contact currents have been based on two research studies in which thresholds for perception of thermal warmth or thermal pain have been measured. Importantly, these studies maximized conductive contact between the subject and the contact current source. This factor was found to dominate the response to heating wherein high resistance contact, such as from dry skin, can result in local heating many times that from a highly conductive contact. Other factors such as electrode size and shape, frequency of the current and the physical force associated with contact are found to introduce uncertainty in threshold values when comparing data across multiple studies. Relying on studies in which the contact current is minimized for a given threshold does not result in conservative protection limits. Future efforts to develop limits on contact currents should include consideration of (1) the basis for the limits (perception, pain, tissue damage); (2) understanding of the

Colored Contact Lens Dangers

Medline Plus

Full Text Available ... One Use Facts About Colored Contacts and Halloween Safety Colored Contact Lens Facts Over-the-Counter Costume ... new application of artificial intelligence shows whether a patient’s eyes point to high blood pressure or risk ...

Contact with turf algae alters the coral microbiome: contact versus systemic impacts

Science.gov (United States)

Pratte, Zoe A.; Longo, Guilherme O.; Burns, Andrew S.; Hay, Mark E.; Stewart, Frank J.

2018-03-01

Coral reefs are degrading to algae-dominated reefs worldwide, with alterations of coral microbiomes commonly co-occurring with reef demise. The severe thermal anomaly during the 2016 El Niño event in the South Pacific killed many corals and stressed others. We examined the microbiome of turf algae and of the coral Porites sp. in contact with turf during this thermal event to investigate algal turf effects on the coral microbiome during a period of environmental stress. The microbial composition of turf did not differ between coral-contacted and non-contacted turfs. However, microbiomes of corals in direct contact with turf were similar to those of the turf microbiome, but differed significantly from coral portions 5 cm from the point of turf/coral contact and from portions of the coral that looked most healthy, regardless of location. Although the majority of significant differences occurred in coral samples at the point of contact, a small subset of microbial taxa was enriched in coral tissues taken 5 cm from turf contact compared to all other sample types, including samples from areas of the coral that appeared most healthy. These results suggest that the coral microbiome is susceptible to colonization by microbes from turf, but not vice versa. Results also suggest that algal contact elicits a subtle shift in the coral microbiome just beyond the contact site. The combination of turf microbiome stability and coral microbiome vulnerability at areas of contact may contribute to the continued decline in coral cover and increase in algal cover associated with coral-algae phase shifts.

Contact and Non-contact Measurements of Grinding Pins

Directory of Open Access Journals (Sweden)

Magdziak Marek

2015-01-01

Full Text Available The paper presents the results of contact and non-contact measurements of external profiles of selected grinding pins. The measurements were conducted in order to choose the appropriate measuring technique in the case of the considered measurement task. In the case of contact measurements the coordinate measuring machine ACCURA II was applied. The used coordinate measuring machine was equipped with the contact scanning probe VAST XT and the Calypso inspection software. Contact coordinate measurements were performed by using of different measurement strategies. The applied strategies included different scanning velocities and distances between measured points. Non-contact measurements were conducted by means of the tool presetter produced by the Mahr company. On the basis of gained results the guidelines concerning measurements of grinding pins were formulated. The measurements of analyzed grinding pins performed by means of the non-contact measuring system are characterized by higher reproducibility than the contact measurements. The low reproducibility of contact measurements may be connected with the inaccuracy of the selected coordinate measuring machine and the measuring probe, the measurement parameters and environmental conditions in the laboratory where the coordinate measuring machine is located. Moreover, the paper presents the possible application of results of conducted investigations. The results of non-contact measurements can be used in the simulation studies of grinding processes. The simulations may reduce the costs of machining processes.

Sustaining dry surfaces under water

DEFF Research Database (Denmark)

Jones, Paul R.; Hao, Xiuqing; Cruz-Chu, Eduardo R.

2015-01-01

Rough surfaces immersed under water remain practically dry if the liquid-solid contact is on roughness peaks, while the roughness valleys are filled with gas. Mechanisms that prevent water from invading the valleys are well studied. However, to remain practically dry under water, additional...... mechanisms need consideration. This is because trapped gas (e.g. air) in the roughness valleys can dissolve into the water pool, leading to invasion. Additionally, water vapor can also occupy the roughness valleys of immersed surfaces. If water vapor condenses, that too leads to invasion. These effects have...... not been investigated, and are critically important to maintain surfaces dry under water.In this work, we identify the critical roughness scale, below which it is possible to sustain the vapor phase of water and/or trapped gases in roughness valleys – thus keeping the immersed surface dry. Theoretical...

Contact conditions in skin-pass rolling

DEFF Research Database (Denmark)

Kijima, Hideo; Bay, Niels

2007-01-01

The special contact conditions in skin-pass rolling of steel strip is analysed by studying plane strain upsetting of thin sheet with low reduction applying long narrow tools and dry friction conditions. An extended sticking region is estimated by an elasto-plastic FEM analysis of the plane strain...... upsetting. This sticking region causes a highly inhomogeneous elasto-plastic deformation with large influence of work-hardening and friction. A numerical analysis of skin-pass rolling shows the same contact conditions, i.e. an extended sticking region around the center of the contact zone. The calculated...... size of the sticking region with varying contact length and pressure/reduction is experimentally verified by plane strain upsetting tests measuring the local surface deformation of the work pieces after unloading....

Critical Points of Contact

DEFF Research Database (Denmark)

Jensen, Ole B.; Wind, Simon; Lanng, Ditte Bendix

2012-01-01

In this brief article, we shall illustrate the application of the analytical and interventionist concept of ‘Critical Points of Contact’ (CPC) through a number of urban design studios. The notion of CPC has been developed over a span of the last three to four years and is reported in more detail...... elsewhere (Jensen & Morelli 2011). In this article, we will only discuss the conceptual and theoretical framing superficially, since our real interest is to show and discuss the concept's application value to spatial design in a number of urban design studios. The 'data' or the projects presented are seven...... in urban design at Aalborg University, where urban design consists of both an analytical and an interventionist field of operation. Furthermore, the content of the CPC concept links to research in mobilities, the network city, and urban design. These are among the core pillars of both the masters programme...

Microscopic origin of the 1.3 G0 conductance observed in oxygen-doped silver quantum point contacts

KAUST Repository

Tu, Xingchen

2014-11-21

© 2014 AIP Publishing LLC. Besides the peak at one conductance quantum, G0, two additional features at ∼0.4 G0 and ∼1.3 G0 have been observed in the conductance histograms of silver quantum point contacts at room temperature in ambient conditions. In order to understand such feature, here we investigate the electronic transport and mechanical properties of clean and oxygen-doped silver atomic contacts by employing the non-equilibrium Green\\'s function formalism combined with density functional theory. Our calculations show that, unlike clean Ag single-atom contacts showing a conductance of 1 G0, the low-bias conductance of oxygen-doped Ag atomic contacts depends on the number of oxygen impurities and their binding configuration. When one oxygen atom binds to an Ag monatomic chain sandwiched between two Ag electrodes, the low-bias conductance of the junction always decreases. In contrast, when the number of oxygen impurities is two and the O-O axis is perpendicular to the Ag-Ag axis, the transmission coefficients at the Fermi level are, respectively, calculated to be 1.44 for the junction with Ag(111) electrodes and 1.24 for that with Ag(100) electrodes, both in good agreement with the measured value of ∼1.3 G0. The calculated rupture force (1.60 nN for the junction with Ag(111) electrodes) is also consistent with the experimental value (1.66 ± 0.09 nN), confirming that the measured ∼1.3 G0 conductance should originate from Ag single-atom contacts doped with two oxygen atoms in a perpendicular configuration.

New approach for dry formulation techniques for rhizobacteria

Science.gov (United States)

Elchin, A. A.; Mashinistova, A. V.; Gorbunova, N. V.; Muratov, V. S.; Kydralieva, K. A.; Jorobekova, Sh. J.

2009-04-01

Two beneficial Pseudomonas isolates selected from rhizosphere of abundant weed - couch-grass Elytrigia repens L. Nevski have been found to have biocontrol activity. An adequate biocontrol effect requires high yield and long stability of the bacterial preparation [1], which could be achieved by an effective and stable formulation. This study was aimed to test various approaches to dry formulation techniques for Pseudomonas- based preparations. To reach this goal, two drying formulation techniques have been tested: the first one, spray drying and the second, low-temperature contact-convective drying in fluidized bed. The optimal temperature parameters for each technique were estimated. Main merits of the selected approach to dry technique are high yield, moderate specific energy expenditures per 1 kg of evaporated moisture, minimal time of contact of the drying product with drying agent. The technological process for dry formulation included the following stages: the obtaining of cell liquids, the low-temperature concentrating and the subsequent drying of a concentrate. The preliminary technological stages consist in cultivation of the rhizobacteria cultures and concentrating the cell liquids. The following requirements for cultivation regime in laboratory conditions were proposed: optimal temperatures are 26-28°С in 3 days, concentration of viable cells in cell liquid makes 1010-1011 cell/g of absolutely dry substance (ADS). For concentrating the cell liquids the method of a vacuum evaporation, which preserves both rhizobacteria cells and the secondary metabolites of cell liquid, has been used. The process of concentrating was conducted at the minimum possible temperature, i.e. not above 30-33°С. In this case the concentration of viable cells has decreased up to 109-1010 cell/g of ADS. For spray drying the laboratory up-dated drier BUCHI 190, intended for the drying of thermolabile products, was used. The temperatures of an in- and outcoming air did not exceed

Multi-point probe for testing electrical properties and a method of producing a multi-point probe

DEFF Research Database (Denmark)

2011-01-01

A multi-point probe for testing electrical properties of a number of specific locations of a test sample comprises a supporting body defining a first surface, a first multitude of conductive probe arms (101-101'''), each of the probe arms defining a proximal end and a distal end. The probe arms...... of contact with the supporting body, and a maximum thickness perpendicular to its perpendicular bisector and its line of contact with the supporting body. Each of the probe arms has a specific area or point of contact (111-111''') at its distal end for contacting a specific location among the number...... of specific locations of the test sample. At least one of the probe arms has an extension defining a pointing distal end providing its specific area or point of contact located offset relative to its perpendicular bisector....

Original Article Effect of Soft Contact Lens Materials on Tear Film ...

African Journals Online (AJOL)

problems, results in intolerance of contact lens wear and damage (Foulks, ... reported that contact lens-related dry eye may be ... eliminating or modifying the refractive error ..... risk of eye infection, easier handling due to ... Adv Exp Med Biol.

Electrode-Skin contact impedance: In vivo measurements on an ovine model

International Nuclear Information System (INIS)

Nguyen, D T; Kosobrodov, R; Jin, C; McEwan, A; Barry, M A; Chik, W; Thiagalingam, A; Oh, T I

2013-01-01

The problem of electrical impedance between the skin and the electrode is an on-going challenge in bio-electronics. This is particularly true in the case of Electrical Impedance Tomography (EIT), which uses a large number of skin-contact electrodes and is very sensitive to noise. In the present article, contact impedance is measured and compared for a range of electrodes placed on the thorax of an ovine model. The study has been approved by the Westmead Hospital Animal Ethics Committee. The electrode models that were employed in the research are Ag/AgCl electrodes (E1), commonly used for ECG and EIT measurements in both humans and animal models, stainless steel crocodile clips (E2), typically used on animal models, and novel multi-point dry electrodes in two modifications: bronze plated (E3) and nickel plated (E4). Further, since the contact impedance is mostly attributed to the acellular outer layer of the skin, in our experiment, we attempted to study the effect of this layer by comparing the results when the skin is intact and when electrodes are introduced underneath the skin through small cuts. This boundary effect was assessed by comparison of measurements obtained during E2 skin surface contact, and sub-cutaneous contact (E5). Twelve gauge intradermal needles were also tested as an electrode (E6). The full impedance spectrum, from 500 Hz to 300 kHz, was recorded, analysed and compared. As expected, the contact impedance in the more invasive cases, i.e the electrodes under the skin, is significantly lower than in the non-invasive cases. At the frequency of 50 kHz which is commonly used in lung EIT acquisition, electrodes E3, E4 and E6 demonstrated contact impedance of less than 200 Ω, compared to more than 400 Ω measured for electrodes E1, E2 and E5. In conclusion, the novel multipoint electrodes proved to be best suited for EIT purposes, because they are non-invasive and have lower contact impedance than Ag/AgCl and crocodile clips, in both invasive and

Determination of Pesticide Dermal Transfer to Operators & Agricultural Workers through Contact with Sprayed Hard Surfaces.

Science.gov (United States)

Tsakirakis, Angelos N; Kasiotis, Konstantinos M; Anastasiadou, Pelagia; Charistou, Agathi N; Gerritsen-Ebben, Rianda; Glass, C Richard; Machera, Kyriaki

2018-05-20

In the present study, the dermal transfer rate of pesticides to agricultural workers occurring via contact with sprayed hard surfaces was investigated. Cotton gloves were used as dosimeters to collect residues from hard surfaces contaminated by pesticides in greenhouses. Dosimeters, either dry or moistened, were in contact with wood, metal and plastic surfaces previously sprayed. The experimental approach applied mimicked the typical hand contact. Moistened cotton gloves were used to simulate hand moisture from dew/condensation or rainfall. The effect of total duration of contact on the final hand exposure via transfer was investigated. The higher duration contact tested (50-sec) resulted in the higher transfer rates for metal and plastic surfaces; no such effect was noted in case of the wood surface. The pesticide amount transferred from the metal and plastic surfaces to wet gloves was greater than the one transferred to dry gloves. Such trend was not observed for the wood surface. Transfer rates varied from 0.46-77.62% and 0.17-16.90% for wet and dry samples, respectively. The current study has generated new data to quantify the proportion of pesticide deposits dislodged from three different non-crop surfaces when in contact with dry or wet gloves. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Biologically-inspired synthetic dry adhesives for wall-climbing robots

Science.gov (United States)

Murphy, Michael P.

Animals such as insects, spiders, and lizards are capable of clinging to and climbing on a variety of surfaces, from rough stone to smooth silicon. Hairy microscale arrays of structures on their feet conform to surface roughness to create millions of points of contact, creating a large overall contact area. Weak intermolecular forces (van der Waals forces) between each fiber tip and the surface sum to large overall forces due to the high number of contacts. In this work we present the fabrication, characterization, and demonstration of synthetic polyurethane fibrillar adhesives inspired by these animals. Angled polymer micro-fiber arrays are fabricated and characterized. A tip modification technique is presented which enables fabrication of fibers with flat mushroom shaped tips which greatly increase the adhesion of the fibers, up to 5N/cm 2 (normal direction), and with a magnitude within the range of geckos (10 N/cm2) in the shear direction on smooth surfaces. We present a fabrication technique to create fibers with angled flat mushroom-shaped tips which replicate the directional characteristics of geckos, gripping in one direction (within the range of gecko adhesion) and releasing easily in the other. Multilevel hierarchical structures with specialized tips for roughness adaptation are also presented. Fiber hierarchies from the millimeter scale to the sub-micron scale are demonstrated, including three-level fiber fabrication with specialized tips. Hierarchical structures demonstrate up to 5 times the adhesion of an unstructured sample, and requiring up to 10 times the detachment energy. Finally, an agile, wireless, palm-sized wall climbing robot which uses the synthetic fibrillar dry adhesives to climb is presented. Waalbot , named after the van der Waals forces it uses to climb, exploits the attachment and detachment characteristics of the developed dry adhesives, capabilities include climbing smooth surfaces such as glass in any orientation on any surface slope

Method of drying passivated micromachines by dewetting from a liquid-based process

Science.gov (United States)

Houston, Michael R.; Howe, Roger T.; Maboudian, Roya; Srinivasan, Uthara

2000-01-01

A method of fabricating a micromachine includes the step of constructing a low surface energy film on the micromachine. The micromachine is then rinsed with a rinse liquid that has a high surface energy, relative to the low surface energy film, to produce a contact angle of greater than 90.degree. between the low surface energy film and the rinse liquid. This relatively large contact angle causes any rinse liquid on the micromachine to be displaced from the micromachine when the micromachine is removed from the rinse liquid. In other words, the micromachine is dried by dewetting from a liquid-based process. Thus, a separate evaporative drying step is not required, as the micromachine is removed from the liquid-based process in a dry state. The relatively large contact angle also operates to prevent attractive capillary forces between micromachine components, thereby preventing contact and adhesion between adjacent microstructure surfaces. The low surface energy film may be constructed with a fluorinated self-assembled monolayer film. The processing of the invention avoids the use of environmentally harmful, health-hazardous chemicals.

Investigation of subsurface fatigue crack in PEEK shaft under one-point rolling contact by using 2.5D layer observation method

Directory of Open Access Journals (Sweden)

KOIKE Hitonobu

2017-01-01

Full Text Available Subsurface fatigue cracks under rolling contact area of the PEEK shaft against an alumina bearing’s ball were investigated for application of frictional part in mechanical element in special situations such as chemical environments. In order to explore the flaking process of the PEEK shaft, the rolling contact fatigue tests were carried out by using a one-point radial loading rolling contact machine. The flaking occurred on the rolling track of the PEEK shaft at approximate 4⨉105 fatigue cycles. The subsurface fatigue crack propagation was investigated by using 2.5-Dimension layer observation method. The flaking was caused by the propagations of surface cracks and subsurface shear cracks, and the flaking shape was half-ellipse. Moreover, beach marks as fatigue crack propagation in the flaking were observed.

Normal Contacts of Lubricated Fractal Rough Surfaces at the Atomic Scale

NARCIS (Netherlands)

Solhjoo, Soheil; Vakis, Antonis I.

The friction of contacting interfaces is a function of surface roughness and applied normal load. Under boundary lubrication, this frictional behavior changes as a function of lubricant wettability, viscosity, and density, by practically decreasing the possibility of dry contact. Many studies on

Bacterial Killing by Dry Metallic Copper Surfaces▿

OpenAIRE

Santo, Christophe Espírito; Lam, Ee Wen; Elowsky, Christian G.; Quaranta, Davide; Domaille, Dylan W.; Chang, Christopher J.; Grass, Gregor

2010-01-01

Metallic copper surfaces rapidly and efficiently kill bacteria. Cells exposed to copper surfaces accumulated large amounts of copper ions, and this copper uptake was faster from dry copper than from moist copper. Cells suffered extensive membrane damage within minutes of exposure to dry copper. Further, cells removed from copper showed loss of cell integrity. Acute contact with metallic copper surfaces did not result in increased mutation rates or DNA lesions. These findings are important fir...

Nonlinear electric reaction arising in dry bone subjected to 4-point bending

Science.gov (United States)

Murasawa, Go; Cho, Hideo; Ogawa, Kazuma

2007-04-01

Bone is a smart, self-adaptive and also partly self-repairing tissue. In recent years, many researchers seek to find how to give the effective mechanical stimulation to bone, because it is the predominant loading that determines the bone shape and macroscopic structure. However, the trial of regeneration of bone is still under way. On the other hand, it has been known that electrical potential generates from bone by mechanical stimulation (Yasuda, 1977; Williams, 1982; Starkebaum, 1979; Cochran, 1968; Lanyon, 1977; Salzstein, 1987a,b; Friedenberg, 1966). This is called "stress-generated potential (SGP)". The process of information transfer between "strain" and "cells" is not still clear. But, there is some possibility that SGP has something to do with the process of information transfer. If the electrical potential is more clear under some mechanical loadings, we will be able to regenerate bone artificially and freely. Therefore, it is important to investigate SGP in detail. The aim of present study is to investigate the electric reaction arising in dry bone subjected to mechanical loadings at high amplitude and low frequency strain. Firstly, specimen is fabricated from femur of cow. Next, the speeds of wave propagation in bone are tried to measure by laser ultra sonic technique and wavelet transform, because these have relationship with bone density. Secondary, 4-point bending test is conducted up to fracture. Then, electric reaction arising in bone is measured during loading. Finally, cyclic 4-point bending tests are conducted to investigate the electric reaction arising in bone at low frequency strain.

Dry coupling for whole-body small-animal photoacoustic computed tomography

OpenAIRE

Yeh, Chenghung; Li, Lei; Zhu, Liren; Xia, Jun; Li, Chiye; Chen, Wanyi; Garcia-Uribe, Alejandro; Maslov, Konstantin I.; Wang, Lihong V.

2017-01-01

We have enhanced photoacoustic computed tomography with dry acoustic coupling that eliminates water immersion anxiety and wrinkling of the animal and facilitates incorporating complementary modalities and procedures. The dry acoustic coupler is made of a tubular elastic membrane enclosed by a closed transparent water tank. The tubular membrane ensures water-free contact with the animal, and the closed water tank allows pressurization for animal stabilization. The dry coupler was tested using ...

Two gap superconductivity in Ba0.55K0.45Fe2As2 single crystals studied by the directional point-contact Andreev reflection spectroscopy

International Nuclear Information System (INIS)

Szabo, P.; Pribulova, Z.; Pristas, G.; Bud'ko, S.L.; Canfield, P.C.; Samuely, P.

2009-01-01

First directional point-contact Andreev reflection spectroscopy on the Ba 0.55 K 0.45 Fe 2 As 2 single crystals is presented. The spectra show significant differences when measured in the ab plane in comparison with those measured in the c direction. In the latter case no traces of superconducting energy gap could be found, just a reduced point-contact conductance persisting up to about 100 K and indicating reduced density of states. On the other hand within the ab plane two nodeless superconducting energy gaps Δ S ∼2-5 meV and Δ L ∼9-11 meV are detected.

[Sport injuries in full contact and semi-contact karate].

Science.gov (United States)

Greier, K; Riechelmann, H; Ziemska, J

2014-03-01

Karate enjoys great popularity both in professional and recreational sports and can be classified into full, half and low contact styles. The aim of this study was the analysis of sports injuries in Kyokushinkai (full contact) and traditional Karate (semi-contact). In a retrospective study design, 215 active amateur karateka (114 full contact, 101 semi-contact) were interviewed by means of a standardised questionnaire regarding typical sport injuries during the last 36 months. Injuries were categorised into severity grade I (not requiring medical treatment), grade II (single medical treatment), grade III (several outpatient medical treatments) and grade IV (requiring hospitalisation). In total, 217 injuries were reported in detail. 125 injuries (58%) occurred in full contact and 92 (42%) in semi-contact karate. The time related injury rate of full contact karateka was 1.9/1000 h compared to 1.3/1000 h of semi-contact karateka (p injuries were musculoskeletal contusions (33% full contact, 20% semi-contact), followed by articular sprains with 19% and 16%. The lower extremity was affected twice as often in full contact (40%) as in semi-contact (20%) karate. Training injuries were reported by 80% of the full contact and 77% of the semi-contact karateka. Most injuries, both in training and competition, occurred in kumite. 75% of the reported injuries of full contact and 70% of semi-contact karateka were classified as low grade (I or II). The high rate of injuries during training and kumite (sparring) points to specific prevention goals. The emphasis should be put on proprioceptive training and consistent warm-up. In the actual competition the referees play a vital role regarding prevention. © Georg Thieme Verlag KG Stuttgart · New York.

Contact allergy and allergic contact dermatitis in adolescents: prevalence measures and associations

DEFF Research Database (Denmark)

Mørtz, Charlotte G; Lauritsen, Jens Martin; Bindslev-Jensen, Carsten

2002-01-01

The aims of this cross-sectional study were to establish the prevalence measures of contact allergy and allergic contact dermatitis in 8th grade schoolchildren (aged 12-16 years) in Odense, Denmark, and to examine the associations with atopic dermatitis, inhalant allergy and hand eczema. Contact...... allergy to a standard series allergen was found in 15.2% of schoolchildren. The point prevalence of allergic contact dermatitis was 0.7% and the lifetime prevalence 7.2%, predominantly in girls. The most common contact allergens were nickel (8.6%) and fragrance mix (1.8%). Nickel allergy was clinically...... relevant in 69% and fragrance allergy in 29% of cases. A significant association was found between contact allergy and hand eczema while no association was found between contact allergy and atopic dermatitis or inhalant allergy. In the future this cohort of schoolchildren will be followed with regard...

CONTACT LENS RELATED CORNEAL ULCER

Directory of Open Access Journals (Sweden)

AGARWAL P

2010-01-01

Full Text Available A corneal ulcer caused by infection is one of the major causes of blindness worldwide. One of the recent health concerns is the increasing incidence of corneal ulcers associated with contact lens user especially if the users fail to follow specific instruction in using their contact lenses. Risk factors associated with increased risk of contact lens related corneal ulcers are:overnight wear, long duration of continuous wear, lower socio-economic classes, smoking, dry eye and poor hygiene. The presenting symptoms of contact lens related corneal ulcers include eye discomfort, foreign body sensation and lacrimation. More serious symptoms are redness (especially circum-corneal injection, severe pain, photophobia, eye discharge and blurring of vision. The diagnosis is established by a thorough slit lamp microscopic examination with fluorescein staining and corneal scraping for Gram stain and culture of the infective organism. Delay in diagnosing and treatment can cause permanent blindness, therefore an early referral to ophthalmologist and commencing of antimicrobial therapy can prevent visual loss.

Model Stickiness in Spray Drying

DEFF Research Database (Denmark)

Petersen, Thomas

only slightly and then typically moved slightly away before either stopping with contact (sticky) or bouncing with no contact (non-sticky). Sticky particles had a large apparent contact angle, similar to what would be expected for a liquid with poor wetting properties. The velocity did not seem...... to change this much, although slight deformation was seen when the impact velocity was at the highest used values. The phenomenon did not appear to change noticeable when the droplet was dried in a high relative humidity environment. The qualitative difference observable between Teon and stainless steel...... was very limited. On Stainless steel the droplet seemed to wet slightly more after the initial impact while the contact area was constant for Teon. Modelling work was carried out to help understand the phenomenon, but also to investigate how the impact scaled for particle size. This was done using...

Point-contact electron tunneling into the high-T/sub c/ superconductor Y-Ba-Cu-O

International Nuclear Information System (INIS)

Kirk, M.D.; Smith, D.P.E.; Mitzi, D.B.

1987-01-01

We report results of a study of electron tunneling into bulk samples of the new high-T/sub c/ superconductor Y-Ba-Cu-O using point-contact tunneling. Based on a superconductive tunneling interpretation, the results show exceptionally large energy gaps in these materials (roughly 2Δ = 100 meV), implying 2Δ/k/sub C/T/sub c/--13. Similar values were found previously by us for La-Sr-Cu-O. We also see Structure in the I-V curves similar to that seen in La-Sr-Cu-O. On the basis of the asymmetries observed in the I-V characteristics, we believe that the natural tunneling barrier on this material is of the Schottky type

Universality in dynamic wetting dominated by contact-line friction.

Science.gov (United States)

Carlson, Andreas; Bellani, Gabriele; Amberg, Gustav

2012-04-01

We report experiments on the rapid contact-line motion present in the early stages of capillary-driven spreading of drops on dry solid substrates. The spreading data fail to follow a conventional viscous or inertial scaling. By integrating experiments and simulations, we quantify a contact-line friction μ(f) which is seen to limit the speed of the rapid dynamic wetting. A scaling based on this contact-line friction is shown to yield a universal curve for the evolution of the contact-line radius as a function of time, for a range of fluid viscosities, drop sizes, and surface wettabilities.

Blade couple connected by damping element with dry friction contacts

Czech Academy of Sciences Publication Activity Database

Pešek, Luděk; Půst, Ladislav

2014-01-01

Roč. 52, č. 3 (2014), s. 815-826 ISSN 1429-2955 R&D Projects: GA ČR GA101/09/1166 Institutional support: RVO:61388998 Keywords : dry friction * three masses system * damping of vibrations * irregular vibrations Subject RIV: BI - Acoustics Impact factor: 0.636, year: 2014 http://www.ptmts.org.pl/article.xsl?vol=52&no=3&page=815

Thermoelectric voltage at a nanometer-scale heated tip point contact

Science.gov (United States)

Fletcher, Patrick C.; Lee, Byeonghee; King, William P.

2012-01-01

We report thermoelectric voltage measurements between the platinum-coated tip of a heated atomic force microscope (AFM) cantilever and a gold-coated substrate. The cantilevers have an integrated heater-thermometer element made from doped single crystal silicon, and a platinum tip. The voltage can be measured at the tip, independent from the cantilever heating. We used the thermocouple junction between the platinum tip and the gold substrate to measure thermoelectric voltage during heating. Experiments used either sample-side or tip-side heating, over the temperature range 25-275 °C. The tip-substrate contact is ˜4 nm in diameter and its average measured Seebeck coefficient is 3.4 μV K-1. The thermoelectric voltage is used to determine tip-substrate interface temperature when the substrate is either glass or quartz. When the non-dimensional cantilever heater temperature is 1, the tip-substrate interface temperature is 0.593 on glass and 0.125 on quartz. Thermal contact resistance between the tip and the substrate heavily influences the tip-substrate interface temperature. Measurements agree well with modeling when the tip-substrate interface contact resistance is 108 K W-1.

Thermoelectric voltage at a nanometer-scale heated tip point contact

International Nuclear Information System (INIS)

Fletcher, Patrick C; Lee, Byeonghee; King, William P

2012-01-01

We report thermoelectric voltage measurements between the platinum-coated tip of a heated atomic force microscope (AFM) cantilever and a gold-coated substrate. The cantilevers have an integrated heater–thermometer element made from doped single crystal silicon, and a platinum tip. The voltage can be measured at the tip, independent from the cantilever heating. We used the thermocouple junction between the platinum tip and the gold substrate to measure thermoelectric voltage during heating. Experiments used either sample-side or tip-side heating, over the temperature range 25–275 °C. The tip–substrate contact is ∼4 nm in diameter and its average measured Seebeck coefficient is 3.4 μV K −1 . The thermoelectric voltage is used to determine tip–substrate interface temperature when the substrate is either glass or quartz. When the non-dimensional cantilever heater temperature is 1, the tip–substrate interface temperature is 0.593 on glass and 0.125 on quartz. Thermal contact resistance between the tip and the substrate heavily influences the tip–substrate interface temperature. Measurements agree well with modeling when the tip–substrate interface contact resistance is 10 8 K W −1 . (paper)

Establishing an upper bound on contact resistivity of ohmic contacts to n-GaN nanowires

International Nuclear Information System (INIS)

Blanchard, Paul; Bertness, Kris A; Harvey, Todd; Sanford, Norman

2014-01-01

Contact resistivity ρ c is an important figure of merit in evaluating and improving the performance of electronic and optoelectronic devices. Due to the small size, unique morphology, and uncertain transport properties of semiconductor nanowires (NWs), measuring ρ c of contacts to NWs can be particularly challenging. In this work, Si-doped n-GaN NWs were grown by molecular beam epitaxy. Four-contact structures with 20 nm Ti/200 nm Al contacts were fabricated on individual NWs by photolithography, and the contacts were annealed to achieve ohmic behavior. Two-point resistances R 23  and four-point collinear resistances R 23collinear  were measured between the middle two contacts on each NW. These resistances were then modeled by taking into account the non-uniform distribution of current flow along the length of each contact. Contrary to the assumption that the resistance difference R 23 −R 23collinear  is equal to the total contact resistance R c , the distributed-current-flow contact model shows that R 23 −R 23collinear  ≪ R c when ρ c is sufficiently small. Indeed, the measured R 23 −R 23collinear  was so small in these devices that it was within the measurement uncertainty, meaning that it was not possible to directly calculate ρ c from these data. However, it was possible to calculate an upper bound on ρ c for each device based on the largest possible value of R 23 −R 23collinear . In addition, we took into account the large uncertainties in the NW transport properties by numerically maximizing ρ c with respect to the uncertainty range of each measured and assumed parameter in the contact model. The resulting upper limits on ρ c ranged from 4.2 × 10 −6  to 7.6 × 10 −6  Ω cm 2 , indicating that 20 nm Ti/200 nm Al is a good choice of ohmic contact for moderately-doped n-GaN NWs. The measurement and numerical analysis demonstrated here offer a general approach to modeling ohmic contact resistivity via NW four-point

Contact dermatitis due to xanthium strumarium

Directory of Open Access Journals (Sweden)

J S Pasricha

1990-01-01

Full Text Available A 50-year-old mining engineer at Dhanbad was having air bome contact Dermatitis suspected to be caused by Xanthium strumarium. Patch tests with a 15% aqueous extract of air dried leaves showed a severe positive reaction, but the patient also had positive patch tests with Parthenium hysterphorus and a few other weeds and trees known to cause air-borne contact dermatitis. The titre of contact hypersensitivity with the extract of Xanthium struma′rium was more than 1:100,000 and for Parthenium hysterophrous it was 1:10 indicating a high degree of hypersensitivity to Xanthium strumarium. Further tests in 14 other patients revealed a high prevalence of cross sensitivity between these two plants both of which belong to the compositae family.

Nanoparticle motion on the surface of drying droplets

Science.gov (United States)

Zhao, Mingfei; Yong, Xin

2018-03-01

Advances in solution-based printing and surface patterning techniques for additive manufacturing demand a clear understanding of particle dynamics in drying colloidal droplets and its relationship with deposit structure. Although the evaporation-driven deposition has been studied thoroughly for the particles dispersed in the bulk of the droplet, few investigations have focused on the particles strongly adsorbed to the droplet surface. We modeled the assembly and deposition of the surface-active particles in a drying sessile droplet with a pinned contact line by the multiphase lattice Boltzmann-Brownian dynamics method. The particle trajectory and its area density profile characterize the assembly dynamics and deposition pattern development during evaporation. While the bulk-dispersed particles continuously move to the contact line, forming the typical "coffee-ring" deposit, the interface-bound particles migrate first toward the apex and then to the contact line as the droplet dries out. To understand this unexpected behavior, we resolve the droplet velocity field both in the bulk and within the interfacial region. The simulation results agree well with the analytical solution for the Stokes flow inside an evaporating droplet. At different stages of evaporation, our study reveals that the competition between the tangential surface flow and the downward motion of the evaporating liquid-vapor interface governs the dynamics of the interface-bound particles. In particular, the interface displacement contributes to the particle motion toward the droplet apex in a short phase, while the outward advective flow prevails at the late stage of drying and carries the particles to the contact line. The final deposit of the surface-adsorbed particles exhibits a density enhancement at the center, in addition to a coffee ring. Despite its small influence on the final deposit in the present study, the distinct dynamics of surface-active particles due to the interfacial confinement

Comparative Evaluation of Silicone Hydrogel Contact Lenses and Autologous Serum for Management of Sjögren Syndrome-Associated Dry Eye.

Science.gov (United States)

Li, Jinyang; Zhang, Xiahua; Zheng, Qinxiang; Zhu, Yirui; Wang, Hui; Ma, Huixiang; Jhanji, Vishal; Chen, Wei

2015-09-01

To comparatively evaluate the efficacy of a bandage contact lens (BCL) and autologous serum (AS) eye drops in the management of severe dry eye caused by Sjögren syndrome (SS). In this prospective randomized study, 40 patients with SS were enrolled. Patients were divided into 2 treatment groups: BCL and AS. A total of 37 patients were included, 18 patients (35 eyes) in the AS group and 19 patients (36 eyes) in the BCL group. At the end of 6 weeks, the best-corrected visual acuity improved significantly in the BCL group (0.5 ± 0.3 vs. 0.3 ± 0.2, P = 0.003) but not in the AS group (0.4 ± 0.3 vs. 0.3 ± 0.3, P = 0.11). The best-corrected visual acuity remained stable up to 6 weeks after discontinuation of the BCL (0.5 ± 0.3 vs. 0.4 ± 0.2, P = 0.03). Although the Ocular Surface Disease Index scores decreased significantly after treatment in both groups, patients in the BCL group had lower Ocular Surface Disease Index scores than those in the AS group (53.4 vs. 41.8 at week 3, 47.1 vs. 31.0 at week 6, 52.7 vs. 32.0 at week 12; P = 0.014, dry eye. Clinical Trial Registration—URL: http://www.clinicaltrials.gov. Unique identifier: NCT02147509.

Detection and Control of Spin-Orbit Interactions in a GaAs Hole Quantum Point Contact

Science.gov (United States)

Srinivasan, A.; Miserev, D. S.; Hudson, K. L.; Klochan, O.; Muraki, K.; Hirayama, Y.; Reuter, D.; Wieck, A. D.; Sushkov, O. P.; Hamilton, A. R.

2017-04-01

We investigate the relationship between the Zeeman interaction and the inversion-asymmetry-induced spin-orbit interactions (Rashba and Dresselhaus SOIs) in GaAs hole quantum point contacts. The presence of a strong SOI results in the crossing and anticrossing of adjacent spin-split hole subbands in a magnetic field. We demonstrate theoretically and experimentally that the anticrossing energy gap depends on the interplay between the SOI terms and the highly anisotropic hole g tensor and that this interplay can be tuned by selecting the crystal axis along which the current and magnetic field are aligned. Our results constitute the independent detection and control of the Dresselhaus and Rashba SOIs in hole systems, which could be of importance for spintronics and quantum information applications.

Highly efficient secondary dewatering of dewatered sewage sludge using low boiling point solvents.

Science.gov (United States)

He, Chao; Chena, Chia-Lung; Xu, Zhirong; Wang, Jing-Yuan

2014-01-01

Secondary dewatering of dewatered sludge is imperative to make conventional drying and incineration of sludge more economically feasible. In this study, a secondary dewatering of dewatered sludge with selected solvents (i.e. acetone and ethanol) followed by vacuum filtration and nature drying was investigated to achieve in-depth dewatering. After the entire secondary dewatering process, the sludge was shown to be odourless and the organic matter content was greatly retained. Increased mean particle size of sludge after solvent contact improved solid-liquid separation. With an acetone/sludge ratio of 3:1 (mL:g) in solvent contact and subsequent nature drying at ambient temperature after 24 h, the moisture content of sludge can be reduced to a level less than 20%. It is found that the polysaccharides were mainly precipitated by acetone, whereas the release ratios of protein and DNA were increased significantly as the added acetone volumes were elevated. During nature drying, accumulated evaporation rates of the sludge after solvent contact were 5-6 times higher than original dewatered sludge. Furthermore, sludge after acetone contact had better nature drying performance than ethanol. The two-stage dewatering involves solvent contact dewatering and solvent enhanced evaporation dewatering. Through selecting an appropriate solvent/sludge ratio as well as economical solvents and minimizing the solvent loss in a closed-pilot system, this dewatering process can be competitive in industrial applications. Therefore, this solvent-aided secondary dewatering is an energy-saving technology for effective in-depth dewatering of dewatered sludge and subsequent sludge utilization.

An earth system model for evaluation of dry deposition

Energy Technology Data Exchange (ETDEWEB)

Arritt, R.W. [Iowa State Univ., Ames, IA (United States)

1994-12-31

A coupled model of atmosphere, soil, and vegetation showed that interactions among the various components can have important effects on dry deposition of SO{sub 2}. In particular, dry soil (near or below the wilting point) leads to an increase of stomatal resistance and a decrease in deposition. Once the soil moisture is at least twice the wilting point, the model results indicate that additional moisture has little effect on the accumulated daytime dry deposition.

Giant Andreev Backscattering through a Quantum Point Contact Coupled via a Disordered Two-Dimensional Electron Gas to Superconductors

International Nuclear Information System (INIS)

den Hartog, S.G.; van Wees, B.J.; Klapwijk, T.M.; Nazarov, Y.V.; Borghs, G.

1997-01-01

We have investigated the superconducting-phase-modulated reduction in the resistance of a ballistic quantum point contact (QPC) connected via a disordered two-dimensional electron gas (2DEG) to superconductors. We show that this reduction is caused by coherent Andreev backscattering of holes through the QPC, which increases monotonically by reducing the bias voltage to zero. In contrast, the magnitude of the phase-dependent resistance of the disordered 2DEG displays a nonmonotonic reentrant behavior versus bias voltage. copyright 1997 The American Physical Society

Dry coupling for whole-body small-animal photoacoustic computed tomography

Science.gov (United States)

Yeh, Chenghung; Li, Lei; Zhu, Liren; Xia, Jun; Li, Chiye; Chen, Wanyi; Garcia-Uribe, Alejandro; Maslov, Konstantin I.; Wang, Lihong V.

2017-04-01

We have enhanced photoacoustic computed tomography with dry acoustic coupling that eliminates water immersion anxiety and wrinkling of the animal and facilitates incorporating complementary modalities and procedures. The dry acoustic coupler is made of a tubular elastic membrane enclosed by a closed transparent water tank. The tubular membrane ensures water-free contact with the animal, and the closed water tank allows pressurization for animal stabilization. The dry coupler was tested using a whole-body small-animal ring-shaped photoacoustic computed tomography system. Dry coupling was found to provide image quality comparable to that of conventional water coupling.

Point contacts and localization in generic helical liquids

Science.gov (United States)

Orth, Christoph P.; Strübi, Grégory; Schmidt, Thomas L.

2013-10-01

We consider two helical liquids on opposite edges of a two-dimensional topological insulator, which are connected by one or several local tunnel junctions. In the presence of spatially inhomogeneous Rashba spin-orbit coupling, the spin of the helical edge states is momentum dependent, and this spin texture can be different on opposite edges. We demonstrate that this has a strong impact on the electron transport between the edges. In particular, in the case of many random tunnel contacts, the localization length depends strongly on the spin textures of the edge states.

The influence of device geometry on many-body effects in quantum point contacts : Signatures of the 0.7 anomaly, exchange and kondo

NARCIS (Netherlands)

Koop, E. J.; Lerescu, A. I.; Liu, J.; van Wees, B. J.; Reuter, D.; Wieck, A. D.; van der Wal, C. H.

The conductance of a quantum point contact (QPC) shows several features that result from many-body electron interactions. The spin degeneracy in zero magnetic field appears to be spontaneously lifted due to the so-called 0.7 anomaly. Further, the g-factor for electrons in the QPC is enhanced, and a

The superconducting gaps of C-substituted and Al-substituted MgB2 single crystals by point-contact spectroscopy

International Nuclear Information System (INIS)

Daghero, D.; Gonnelli, R.S.; Ummarino, G.A.; Calzolari, A.; Dellarocca, Valeria; Stepanov, V.A.; Zhigadlo, N.; Kazakov, S.M.; Karpinski, J.

2005-01-01

We studied the effects of carbon and aluminum substitutions on the gaps of the two-band superconductor MgB 2 by means of point-contact measurements in Mg(B 1-x C x ) 2 and Mg 1-y Al y B 2 single crystals with 0≤x≤0.132 and 0≤y≤0.21. The gap amplitudes, Δ ω and Δ π , were determined by fitting the conductance curves of the point contacts with the standard Blonder-Tinkham-Klapwijk (BTK) model generalized to the two-band case. Whenever possible, their values were confirmed by the independent fit (with a single-band BTK model) of the partial contribution of the two bands to the conductance, separated by means of a suitable magnetic field B*. In C-substituted crystals, the two gaps remain clearly distinct up to x∝0.10, but at x=0.132 we observed for the first time their merging into a single gap Δ≅3 meV with a gap ratio 2Δ=k B T c close to the standard BCS value. In Al-substituted crystals, we found no evidence of this gap merging. Instead, Δ π reaches the value 0.4 meV at y=0.21, where Δ π saturates at about 4 meV. These results are compared with other recent experimental findings in polycrystals and with the predictions of the models for multiband superconductivity. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

A noise-resistant ADSA-PH algorithm for superhydrophobic surface’s static contact angle evaluation

OpenAIRE

Z. N. Xu

2017-01-01

The blur around the contact points significantly decreases the evaluated static contact angle for superhydrophobic surface which is clearly presented in the paper. To improve the accuracy in the evaluated static contact angle for superhydrophobic surface, an accurate static contact angle algorithm, namely ADSA-PH (axisymmetric drop shape analysis-profile and height), is proposed. It discards the extracted drop edge points close to the contact points and makes use of the residual points and th...

Contact lenses and the rate of evaporation measured in vitro; the influence of wear, squalene and wax.

Science.gov (United States)

Vishnubhatla, Sravya; Borchman, Douglas; Foulks, Gary N

2012-12-01

Accelerated evaporation of tears may contribute to dry eye symptoms. It is not clear whether contact lenses decrease or increase the rate of evaporation of tears. In this study, the rates of evaporation through contact lenses (ERTCL) were measured in vitro to gain insight to this question. Contact lenses were equilibrated with various solutions to determine if they influenced ERTCL in vitro. ERTCL was measured gravimetrically. ERTCL measured in vitro for used contact lenses was about 20% faster than for buffer alone suggesting that natural tear components bound to the lenses changed the ERTCL. One natural tear component that binds to contact lenses is waxes. Equilibration of contact lenses with wax increased the ERTCL by about 30% suggesting that waxes might potentially increase ERTCL in vivo. Squalene, found in sebum and possibly meibum was infused into the contact lenses as a step toward decreasing the ERTCL. Squalene decreased ERTCL by over 60% in vitro. Soaking a contact lens in DuraSite(®) with benzalkonium chloride (BAK) did not alter the ERTCL. ERTCL were about 40% higher than the evaporation rate of DuraSite(®) alone or without BAK. In addition to lowering the ERTCL, the squalene in contact lenses could be a source of terpenoids to replace the terpenoids deficient in patients with MGD. If the ERTCL could be minimized in vivo, contact lenses could potentially be used to relieve dry eye symptoms in patients with evaporative dry eye. Copyright © 2012 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Multivariate analysis and extraction of parameters in resistive RAMs using the Quantum Point Contact model

Science.gov (United States)

Roldán, J. B.; Miranda, E.; González-Cordero, G.; García-Fernández, P.; Romero-Zaliz, R.; González-Rodelas, P.; Aguilera, A. M.; González, M. B.; Jiménez-Molinos, F.

2018-01-01

A multivariate analysis of the parameters that characterize the reset process in Resistive Random Access Memory (RRAM) has been performed. The different correlations obtained can help to shed light on the current components that contribute in the Low Resistance State (LRS) of the technology considered. In addition, a screening method for the Quantum Point Contact (QPC) current component is presented. For this purpose, the second derivative of the current has been obtained using a novel numerical method which allows determining the QPC model parameters. Once the procedure is completed, a whole Resistive Switching (RS) series of thousands of curves is studied by means of a genetic algorithm. The extracted QPC parameter distributions are characterized in depth to get information about the filamentary pathways associated with LRS in the low voltage conduction regime.

A low energy muon spin rotation and point contact tunneling study of niobium films prepared for superconducting cavities

Science.gov (United States)

Junginger, Tobias; Calatroni, S.; Sublet, A.; Terenziani, G.; Prokscha, T.; Salman, Z.; Suter, A.; Proslier, T.; Zasadzinski, J.

2017-12-01

Point contact tunneling and low energy muon spin rotation are used to probe, on the same samples, the surface superconducting properties of micrometer thick niobium films deposited onto copper substrates using different sputtering techniques: diode, dc magnetron and HIPIMS. The combined results are compared to radio-frequency tests performances of RF cavities made with the same processes. Degraded surface superconducting properties are found to correlate to lower quality factors and stronger Q-slope. In addition, both techniques find evidence for surface paramagnetism on all samples and particularly on Nb films prepared by HIPIMS.

A contact angle hysteresis model based on the fractal structure of contact line.

Science.gov (United States)

Wu, Shuai; Ma, Ming

2017-11-01

Contact angle is one of the most popular concept used in fields such as wetting, transport and microfludics. In practice, different contact angles such as equilibrium, receding and advancing contact angles are observed due to hysteresis. The connection among these contact angles is important in revealing the chemical and physical properties of surfaces related to wetting. Inspired by the fractal structure of contact line, we propose a single parameter model depicting the connection of the three angles. This parameter is decided by the fractal structure of the contact line. The results of this model agree with experimental observations. In certain cases, it can be reduced to other existing models. It also provides a new point of view in understanding the physical nature of the contact angle hysteresis. Interestingly, some counter-intuitive phenomena, such as the binary receding angles, are indicated in this model, which are waited to be validated by experiments. Copyright © 2017 Elsevier Inc. All rights reserved.

Energy gap in La/sub 1. 85/Sr/sub 0. 15/CuO/sub 4-//sub y/ from point-contact tunneling

Energy Technology Data Exchange (ETDEWEB)

Hawley, M.E.; Gray, K.E.; Capone II, D.W.; Hinks, D.G.

1987-05-01

Point-contact tunneling into the high-T/sub c/ superconductor La/sub 1.85/Sr/sub 0.15/CuO/sub 4-//sub y/ reveals the first direct measure of the energy gap. Values range from 8 to 14 meV with the variation perhaps due to impurity phases, pressure-induced changes, or anisotropy. Even the minimum value indicates a strong-coupling superconductor.

Phenome data - Air-drying stress - DGBY | LSDB Archive [Life Science Database Archive metadata

Lifescience Database Archive (English)

Full Text Available List Contact us DGBY Phenome data - Air-drying stress Data detail Data name Phenome data - Air-drying stress... DOI 10.18908/lsdba.nbdc00953-007 Description of data contents Yeasts used in bread making are exposed to air-dryin...g stress during dried yeast production processes. To clarify the genes required for air-drying tolera...tion of diploid Saccharomyces cerevisiae . The screening identified 278 gene deletions responsible for air-dryin...heir gene products. The results showed that the genes required for air-drying tol

Utilization of lime-dried sludge for eco-cement clinker production: effects of different feeding points.

Science.gov (United States)

Cao, Haihua; Liu, Wei; Xu, Jingcheng; Liu, Jia; Huang, Juwen; Huang, Xiangfeng; Li, Guangming

2018-02-01

Co-processing lime-dried sludge (LDS) in cement kilns is an appropriate technique to solve the problem of LDS disposal and promote the sustainable development for cement industry. However, there were limited studies that investigated the effects of feeding points on product quality and cement kiln emissions. In this study, simulated experiments were conducted by dividing the feeding points into high-temperature zones (HTZs) and raw mill (RM). Cement quality and major cement kiln emission characteristics were comprehensively investigated. The results showed that in terms of burnability, compressive strength and microstructure, the optimum co-processing amount of LDS were 9 wt% when feeding at RM, while 6% when feeding at HTZs. Meanwhile, the organic emissions of RM samples were mainly low environmental risk compounds of amides and nitrogenous heterocyclic compounds. Inorganic gaseous pollutions of NO X and SO 2 , respectively, were 8.11 mg/g DS and 12.89 mg/g DS, compared with 7.61 mg/g DS and 4.44 mg/g DS for HTZs. However, all the cement kiln emissions concentration were still much lower than standard requirements. Overall, RM had a bigger LDS co-processing capacity and higher, but acceptable, cement kiln emissions. Feeding LDS via RM could dispose larger amounts of sludge and provide more alternative materials for cement manufacturing.

A substitute model of two-dimensional dry friction exposed to dither generated by rolling contact of wheel and rail

Science.gov (United States)

Piotrowski, Jerzy

2012-10-01

Dither generated by rolling contact of wheel and rail smoothes dry friction damping provided by the primary suspension dampers of freight wagons and it should be taken into account in numerical simulations. But numerically the problem is non-smooth and this leads to long execution time during simulation, especially when the vehicle with friction dampers is modelled in the environment of an multi-body system simulation program, whose solver has to cope with many strong non-linearities. The other difficulty is the necessity of handling within the code a number of big volume files of recorded dither sampled with high frequency. To avoid these difficulties, a substitute model of two-dimensional dry friction exposed to dither is proposed that does not need application of dither during simulation, but it behaves as if dither were applied. Due to this property of the model, the excitation of the vehicle model by track irregularities may be supplied as low-frequency input, which allows fast execution and, the necessity of handling high-volume files of recorded dither is avoided. The substitute model is numerically effective. To identify parameters of the substitute model, a pre-processing employing a sample of the realistic dither is carried-out on a simple two-degrees-of-freedom system. The substitute model is anisotropic, describing anisotropic properties of the two-dimensional friction arising in the presence of one-dimensional dither. The model may be applied in other branches of engineering, for example, in mechatronics and robotics, where application of dither may improve the accuracy of positioning devices.

75 FR 45673 - Compliance Assistance Resources and Points of Contact Available to Small Businesses

Science.gov (United States)

2010-08-03

.../business-law/contacts/federal/ FOR FURTHER INFORMATION CONTACT: Wendy Liberante, Office of Information and... businesses. This list is available today on the following Web site: http://www.business.gov/business-law....business.gov/business-law/contacts/federal/ . OMB and SBA have chosen to implement this statutory...

Soil aggregate formation: the role of wetting-drying cycles in the genesis of interparticle bonding

Science.gov (United States)

Albalasmeh, Ammar; Ghezzehei, Teamrat

2013-04-01

Soil structure influences many soil properties including aeration, water retention, drainage, bulk density, and resistance to erosion and indirectly influences most biological and chemical processes that occur in and around soil. In nature, soil is continually exposed to wetting (e.g., rainfall and diffusive flow) and drying (e.g., evaporation, diffusive flow and plant uptake). These natural wetting and drying cycles of soils are physical events that profoundly affect the development of soil structure, aggregate stability, carbon (C) flux and mineralization. We hypothesize that drying of capillary water transports suspended and/or dissolved cementing agents toward inter-particle contacts and eventually deposits part of the colloidal mass forming inter-particle bonds. Here, we will show the role of wetting and drying cycles on soil aggregation and stabilization and how these cycles transport and deposit organic cementing agents at the inter-particle contact. We found that aggregates of sand and silt particles can be formed by subjecting loose particles to wetting-drying cycles in the presence of dilute solutions of organic matter that mimic root or microbial exudates. Moreover, majority of the organic matter was deposited in the contact region between the sand particles, where the water accumulates during drying. The model predictions and aggregate stability measurements are supported by scanning electron micrographs that clearly show the process of aggregate formation.

An overview of the formulation, existence and uniqueness issues for the initial value problem raised by the dynamics of discrete systems with unilateral contact and dry friction

Science.gov (United States)

Ballard, Patrick; Charles, Alexandre

2018-03-01

In the end of the seventies, Schatzman and Moreau undertook to revisit the venerable dynamics of rigid bodies with contact and dry friction in the light of more recent mathematics. One claimed objective was to reach, for the first time, a mathematically consistent formulation of an initial value problem associated with the dynamics. The purpose of this article is to make a review of the today state-of-art concerning not only the formulation, but also the issues of existence and uniqueness of solution. xml:lang="fr"

Developing a framework to model the primary drying step of a continuous freeze-drying process based on infrared radiation

DEFF Research Database (Denmark)

Van Bockstal, Pieter-Jan; Corver, Jos; Mortier, Séverine Thérèse F.C.

2018-01-01

. These results assist in the selection of proper materials which could serve as IR window in the continuous freeze-drying prototype. The modelling framework presented in this paper fits the model-based design approach used for the development of this prototype and shows the potential benefits of this design...... requires the fundamental mechanistic modelling of each individual process step. Therefore, a framework is presented for the modelling and control of the continuous primary drying step based on non-contact IR radiation. The IR radiation emitted by the radiator filaments passes through various materials...

Contact angle measurement with a smartphone.

Science.gov (United States)

Chen, H; Muros-Cobos, Jesus L; Amirfazli, A

2018-03-01

In this study, a smartphone-based contact angle measurement instrument was developed. Compared with the traditional measurement instruments, this instrument has the advantage of simplicity, compact size, and portability. An automatic contact point detection algorithm was developed to allow the instrument to correctly detect the drop contact points. Two different contact angle calculation methods, Young-Laplace and polynomial fitting methods, were implemented in this instrument. The performance of this instrument was tested first with ideal synthetic drop profiles. It was shown that the accuracy of the new system with ideal synthetic drop profiles can reach 0.01% with both Young-Laplace and polynomial fitting methods. Conducting experiments to measure both static and dynamic (advancing and receding) contact angles with the developed instrument, we found that the smartphone-based instrument can provide accurate and practical measurement results as the traditional commercial instruments. The successful demonstration of use of a smartphone (mobile phone) to conduct contact angle measurement is a significant advancement in the field as it breaks the dominate mold of use of a computer and a bench bound setup for such systems since their appearance in 1980s.

Contact angle measurement with a smartphone

Science.gov (United States)

Chen, H.; Muros-Cobos, Jesus L.; Amirfazli, A.

2018-03-01

In this study, a smartphone-based contact angle measurement instrument was developed. Compared with the traditional measurement instruments, this instrument has the advantage of simplicity, compact size, and portability. An automatic contact point detection algorithm was developed to allow the instrument to correctly detect the drop contact points. Two different contact angle calculation methods, Young-Laplace and polynomial fitting methods, were implemented in this instrument. The performance of this instrument was tested first with ideal synthetic drop profiles. It was shown that the accuracy of the new system with ideal synthetic drop profiles can reach 0.01% with both Young-Laplace and polynomial fitting methods. Conducting experiments to measure both static and dynamic (advancing and receding) contact angles with the developed instrument, we found that the smartphone-based instrument can provide accurate and practical measurement results as the traditional commercial instruments. The successful demonstration of use of a smartphone (mobile phone) to conduct contact angle measurement is a significant advancement in the field as it breaks the dominate mold of use of a computer and a bench bound setup for such systems since their appearance in 1980s.

Terahertz time domain interferometry of a SIS tunnel junction and a quantum point contact

Energy Technology Data Exchange (ETDEWEB)

Karadi, Chandu [Univ. of California, Berkeley, CA (United States). Dept. of Physics

1995-09-01

The author has applied the Terahertz Time Domain Interferometric (THz-TDI) technique to probe the ultrafast dynamic response of a Superconducting-Insulating-Superconducting (SIS) tunnel junction and a Quantum Point Contact (QPC). The THz-TDI technique involves monitoring changes in the dc current induced by interfering two picosecond electrical pulses on the junction as a function of time delay between them. Measurements of the response of the Nb/AlO_xNb SIS tunnel junction from 75--200 GHz are in full agreement with the linear theory for photon-assisted tunneling. Likewise, measurements of the induced current in a QPC as a function of source-drain voltage, gate voltage, frequency, and magnetic field also show strong evidence for photon-assisted transport. These experiments together demonstrate the general applicability of the THz-TDI technique to the characterization of the dynamic response of any micron or nanometer scale device that exhibits a non-linear I-V characteristic.

Lateral-electric-field-induced spin polarization in a suspended GaAs quantum point contact

Science.gov (United States)

Pokhabov, D. A.; Pogosov, A. G.; Zhdanov, E. Yu.; Shevyrin, A. A.; Bakarov, A. K.; Shklyaev, A. A.

2018-02-01

The conductance of a GaAs-based suspended quantum point contact (QPC) equipped with lateral side gates has been experimentally studied in the absence of the external magnetic field. The half-integer conductance plateau ( 0.5 ×2 e2/h ) has been observed when an asymmetric voltage between the side gates is applied. The appearance of this plateau has been attributed to the spin degeneracy lifting caused by the spin-orbit coupling associated with the lateral electric field in the asymmetrically biased QPC. We have experimentally demonstrated that, despite the relatively small g-factor in GaAs, the observation of the spin polarization in the GaAs-based QPC became possible after the suspension due to the enhancement of the electron-electron interaction and the effect of the electric field guiding. These features are caused by a partial confinement of the electric field lines within a suspended semiconductor layer with a high dielectric constant.

Terahertz time domain interferometry of a SIS tunnel junction and a quantum point contact

International Nuclear Information System (INIS)

Karadi, C.; Lawrence Berkeley Lab., CA

1995-09-01

The author has applied the Terahertz Time Domain Interferometric (THz-TDI) technique to probe the ultrafast dynamic response of a Superconducting-Insulating-Superconducting (SIS) tunnel junction and a Quantum Point Contact (QPC). The THz-TDI technique involves monitoring changes in the dc current induced by interfering two picosecond electrical pulses on the junction as a function of time delay between them. Measurements of the response of the Nb/AlO x /Nb SIS tunnel junction from 75--200 GHz are in full agreement with the linear theory for photon-assisted tunneling. Likewise, measurements of the induced current in a QPC as a function of source-drain voltage, gate voltage, frequency, and magnetic field also show strong evidence for photon-assisted transport. These experiments together demonstrate the general applicability of the THz-TDI technique to the characterization of the dynamic response of any micron or nanometer scale device that exhibits a non-linear I-V characteristic. 133 refs., 49 figs

Selective dry cow treatment in dairy cows

OpenAIRE

Scherpenzeel, C.G.M.

2017-01-01

In the dairy industry, udder health is associated with mastitis management, of which blanket dry cow treatment has been an important part for decades. To prevent the udder from new intramammary infections during the dry period, the use of blanket dry cow treatment has been advocated for more than 50 years as part of the five-point mastitis prevention program. The goal of dry cow treatment is to reduce the prevalence of intramammary infections by eliminating infections already present at dryin...

Development of a contact heat exchanger for a constructable radiator system

Science.gov (United States)

Howell, H. R.

1983-01-01

A development program for a contact heat exchanger to be used to transfer heat from a spacecraft coolant loop to a heat pipe radiator is described. The contact heat exchanger provides for a connectable/disconnectable joint which allows for on-orbit assembly of the radiator system and replacement or exchange of radiator panels for repair and maintenance. The contact heat exchanger does not require the transfer of fluid across the joint; the spacecraft coolant loop remains contained in an all welded system with no static or dynamic fluid seals. The contact interface is also "dry' with no conductive grease or interstitial material required.

Contact detection for nanomanipulation in a scanning electron microscope

Energy Technology Data Exchange (ETDEWEB)

Ru, Changhai, E-mail: rchhai@gmail.com [Automation College, Harbin Engineering University, Harbin 150001 (China); Robotics and Microsystems Center, Soochow University, Jiangsu 215021 (China); To, Steve, E-mail: Steve.to@utoronto.ca [Department of Mechanical and Industry Engineering, University of Toronto, Ontario, Canada M5S3G8 (Canada)

2012-07-15

Nanomanipulation systems require accurate knowledge of the end-effector position in all three spatial coordinates, XYZ, for reliable manipulation of nanostructures. Although the images acquired by a scanning electron microscope (SEM) provide high resolution XY information, the lack of depth information in the Z-direction makes 3D nanomanipulation time-consuming. Existing approaches for contact detection of end-effectors inside SEM typically utilize fragile touch sensors that are difficult to integrate into a nanomanipulation system. This paper presents a method for determining the contact between an end-effector and a target surface during nanomanipulation inside SEM, purely based on the processing of SEM images. A depth-from-focus method is used in the fast approach of the end-effector to the substrate, followed by fine contact detection. Experimental results demonstrate that the contact detection approach is capable of achieving an accuracy of 21.5 nm at 50,000 Multiplication-Sign magnification while inducing little end-effector damage. -- Highlights: Black-Right-Pointing-Pointer We presents a simple method for obtaining the depth information in SEM-based nanomanipulation. Black-Right-Pointing-Pointer Detecting contact between an end-effector and a target surface using SEM as a vision sensor. Black-Right-Pointing-Pointer Additional touch/force sensors or specialized hardware need not be added. Black-Right-Pointing-Pointer Achieved high repeatability and accuracy. Black-Right-Pointing-Pointer Complete automatic contact detection within typically 60 s.

Contact Line Dynamics

Science.gov (United States)

Kreiss, Gunilla; Holmgren, Hanna; Kronbichler, Martin; Ge, Anthony; Brant, Luca

2017-11-01

The conventional no-slip boundary condition leads to a non-integrable stress singularity at a moving contact line. This makes numerical simulations of two-phase flow challenging, especially when capillarity of the contact point is essential for the dynamics of the flow. We will describe a modeling methodology, which is suitable for numerical simulations, and present results from numerical computations. The methodology is based on combining a relation between the apparent contact angle and the contact line velocity, with the similarity solution for Stokes flow at a planar interface. The relation between angle and velocity can be determined by theoretical arguments, or from simulations using a more detailed model. In our approach we have used results from phase field simulations in a small domain, but using a molecular dynamics model should also be possible. In both cases more physics is included and the stress singularity is removed.

Impact of recess etching and surface treatments on ohmic contacts regrown by molecular-beam epitaxy for AlGaN/GaN high electron mobility transistors

Energy Technology Data Exchange (ETDEWEB)

Joglekar, S.; Azize, M.; Palacios, T. [Microsystems Technology Laboratories, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139 (United States); Beeler, M.; Monroy, E. [Université Grenoble-Alpes, 38000 Grenoble (France); CEA Grenoble, INAC-PHELIQS, 38000 Grenoble (France)

2016-07-25

Ohmic contacts fabricated by regrowth of n{sup +} GaN are favorable alternatives to metal-stack-based alloyed contacts in GaN-based high electron mobility transistors. In this paper, the influence of reactive ion dry etching prior to regrowth on the contact resistance in AlGaN/GaN devices is discussed. We demonstrate that the dry etch conditions modify the surface band bending, dangling bond density, and the sidewall depletion width, which influences the contact resistance of regrown contacts. The impact of chemical surface treatments performed prior to regrowth is also investigated. The sensitivity of the contact resistance to the surface treatments is found to depend upon the dangling bond density of the sidewall facets exposed after dry etching. A theoretical model has been developed in order to explain the observed trends.

Biliary peritonitis caused by a leaking T-tube fistula disconnected at the point of contact with the anterior abdominal wall: a case report

Directory of Open Access Journals (Sweden)

Nikolić Marko

2008-09-01

Full Text Available Abstract Introduction Operations on the common bile duct may lead to potentially serious complications such as biliary peritonitis. T-tube insertion is performed to reduce the risk of this occurring postoperatively. Biliary leakage at the point of insertion into the common bile duct, or along the fistula, can sometimes occur after T-tube removal and this has been reported extensively in the literature. We report a case where the site at which the T-tube fistula leaked proved to be the point of contact between the fistula and the anterior abdominal wall, a previously unreported complication. Case presentation A 36-year-old sub-Saharan African woman presented with gallstone-induced pancreatitis and, once her symptoms settled, laparoscopic cholecystectomy was performed, common bile duct stones were removed and a T-tube was inserted. Three weeks later, T-tube removal led to biliary peritonitis due to the disconnection of the T-tube fistula which was recannulated laparoscopically using a Latex drain. Conclusion This case highlights a previously unreported mechanism for bile leak following T-tube removal caused by detachment of a fistula tract at its contact point with the anterior abdominal wall. Hepatobiliary surgeons should be aware of this mechanism of biliary leakage and the use of laparoscopy to recannulate the fistula.

CONTACT RESISTANCE MODELING

Directory of Open Access Journals (Sweden)

S. V. LOSKUTOV

2018-05-01

Full Text Available Purpose. To determine the contribution of the real contact spots distribution in the total conductivity of the conductors contact. Methodology. The electrical contact resistance research was carried out on models. The experimental part of this work was done on paper with a graphite layer with membranes (the first type and conductive liquids with discrete partitions (the second type. Findings. It is shown that the contact electrical resistance is mainly determined by the real area of metal contact. The experimental dependence of the electrical resistance of the second type model on the distance between the electrodes and the potential distribution along the sample surface for the first type model were obtained. The theoretical model based on the principle of electric field superposition was considered. The dependences obtained experimentally and calculated by using the theoretical model are in good agreement. Originality. The regularity of the electrical contact resistance formation on a large number of membranes was researched for the first time. A new model of discrete electrical contact based on the liquid as the conducting environment with nuclear membrane partitions was developed. The conclusions of the additivity of contact and bulk electrical resistance were done. Practical value. Based on these researches, a new experimental method of kinetic macroidentation that as a parameter of the metal surface layer deformation uses the real contact area was developed. This method allows to determine the value of average contact stresses, yield point, change of the stress on the depth of deformation depending on the surface treatment.

Dielectric spectroscopy for evaluating dry matter content of potato tubers

DEFF Research Database (Denmark)

Nielsen, Glenn G. B.; Kjaer, Anders; Klösgen, Beate

2016-01-01

The present study investigated the application of dielectric spectroscopy as a method for evaluating the dry matter content of potato tubers. Sample specific factors determining the precision of this application were investigated by studying the prediction of the dry material content in agar gel...... of the predicted dry matter content was observed in chemically and spatially uniform systems, with a root mean square error (RMSE) of the predicted dry-matter content of 0.64 percentage points observed in agar gels containing refined potato starch. A marked decrease in precision is observed in model systems which...... include chemical variations between potato tuber samples. The added dry material content was predicted with a RMSE of 0.94 percentage points in agar gels with added dried material extracted from separate potato tubers. The local dry matter content from a region within 2 cm of the center location...

Contact angles of wetting and water stability of soil structure

Science.gov (United States)

Kholodov, V. A.; Yaroslavtseva, N. V.; Yashin, M. A.; Frid, A. S.; Lazarev, V. I.; Tyugai, Z. N.; Milanovskiy, E. Yu.

2015-06-01

From the soddy-podzolic soils and typical chernozems of different texture and land use, dry 3-1 mm aggregates were isolated and sieved in water. As a result, water-stable aggregates and water-unstable particles composing dry 3-1 mm aggregates were obtained. These preparations were ground, and contact angles of wetting were determined by the static sessile drop method. The angles varied from 11° to 85°. In most cases, the values of the angles for the water-stable aggregates significantly exceeded those for the water-unstable components. In terms of carbon content in structural units, there was no correlation between these parameters. When analyzing the soil varieties separately, the significant positive correlation between the carbon content and contact angle of aggregates was revealed only for the loamy-clayey typical chernozem. Based on the multivariate analysis of variance, the value of contact wetting angle was shown to be determined by the structural units belonging to water-stable or water-unstable components of macroaggregates and by the land use type. In addition, along with these parameters, the texture has an indirect effect.

Evidence of multiband superconductivity in the quaternary borocarbide superconductor YNi2B2C using directional point-contact spectroscopy

International Nuclear Information System (INIS)

Raychaudhuri, Pratap; Sheet, Goutam; Mukhopadhyay, Sourin; Takeya, H.

2007-01-01

In this paper, we review our recent investigations on the gap anisotropy of the quaternary borocarbide superconductor YNi 2 B 2 C using directional point-contact spectroscopy. Through a detailed study of the temperature and magnetic field dependence of the superconducting energy gaps we show that the gap anisotropy in this material originates from electrons on different Fermi sheets having very different Fermi velocities. The gap anisotropy in this material is therefore well explained through a multiband scenario where electrons in different k-directions have very different electron-phonon coupling strength

Drying of liquid food droplets : enzyme inactivation and multicomponent diffusion

NARCIS (Netherlands)

Meerdink, G.

1993-01-01

In this thesis the drying of liquid food droplets is studied from three different points of view: drying kinetics, enzyme inactivation and multicomponent diffusion. Mathematical models are developed and validated experimentally.

Drying experiments are performed with suspended

Feasibility on Ultrasonic Velocity using Contact and Non-Contact Nondestructive Techniques for Carbon/Carbon Composites

Science.gov (United States)

Im, K. H.; Chang, M.; Hsu, D. K.; Song, S. J.; Cho, H.; Park, J. W.; Kweon, Y. S.; Sim, J. K.; Yang, I. Y.

2007-03-01

Advanced materials are to be required to have specific functions associated with extremely environments. One of them is carbon/carbon(C/C) composite material, which has obvious advantages over conventional materials. The C/Cs have become to be utilized as parts of aerospace applications and its low density, high thermal conductivity and excellent mechanical properties at elevated temperatures make it an ideal material for aircraft brake disks. Because of permeation of coupling medium such as water, it is desirable to perform contact-less nondestructive evaluation to assess material properties and part homogeneity. In this work, a C/C composite material was characterized with non-contact and contact ultrasonic methods using a scanner with automatic-data acquisition function. Also through transmission mode was performed because of the main limitation for air-coupled transducers, which is the acoustic impedance mismatch between most materials and air. Especially ultrasonic images and velocities for C/C composite disk brake were compared and found to be consistent to some degree with the non-contact and contact ultrasonic measurement methods. Low frequency through-transmission scans based on both amplitude of the ultrasonic pulse was used for mapping out the material property inhomogeneity. Measured results were compared with those obtained by the dry-coupling ultrasonic UT system and through transmission method in immersion. Finally, feasibility has been found to measure and compare ultrasonic velocities of C/C composites with using the contact/noncontact peak-delay measurement method based on the pulse overlap method.

Contact spectroscopy of high-temperature superconductors. Review

International Nuclear Information System (INIS)

Yanson, I.K.

1991-01-01

We have attempted to systematize the research of high temperature superconductors by means of tunneling and point-contact spectroscopy. The theoretical grounds of the methods are briefly described. The deviations of current-voltage characteristics from ordinary superconductors are considered. The properties of point contacts with direct energy gap measurfements and the fine structure of derivatives of i(v) curves at the overlap energies are reviewed for the high-T c La 2-x Sr x CuO 4 materials

Effect of gamma radiation on graphite - PTFE dry lubrication system

Science.gov (United States)

Singh, Sachin; Tyagi, Mukti; Seshadri, Geetha; Tyagi, Ajay Kumar; Varshney, Lalit

2017-12-01

An effect of gamma radiation on lubrication behavior of graphite -PTFE dry lubrication system has been studied using (TR-TW-30L) tribometer with thrust washer attachment in plane contact. Different compositions of graphite and PTFE were prepared and irradiated by gamma rays. Gamma radiation exposure significantly improves the tribological properties indicated by decrease in coefficient of friction and wear properties of graphite -PTFE dry lubrication system. SEM and XRD analysis confirm the physico-chemical modification of graphite-PTFE on gamma radiation exposure leading to a novel dry lubrication system with good slip and anti friction properties.

Experimental Investigation of Solar Drying for Orange Peels by Forced convection

International Nuclear Information System (INIS)

Ben Slama, Romdhane; Mechlouch, Fethi; Ben Daoud, Houcine

2009-01-01

Solar drier does not degrade any more the dried products with the manner of the products dried at the natural sun. The drying unit is composed mainly of a solar air collector and an enclosure of drying. The transformation of the solar radiation into heat is done thanks to the solar collector whose effectiveness is increased by the addition of suitable baffles in the mobile air vein. The efficiency of the collector reaches then 80. The hot air on the outlet side of the collector arrives in the enclosure of drying where the heat transfer with the product to be dried is done by convection. The kinetics drying study shows that in addition to the dependence of the temperature and air velocity of drying, the speed of drying also depends on fragmentation on the product to dry, and mainly, of the product surface in contact with the drying air. Thus, the hygrometry is reduced from 76 to 13 pour cent in one day.. The total efficiency of the drier reached 28 pour cent

Contact angle of unset elastomeric impression materials.

Science.gov (United States)

Menees, Timothy S; Radhakrishnan, Rashmi; Ramp, Lance C; Burgess, John O; Lawson, Nathaniel C

2015-10-01

Some elastomeric impression materials are hydrophobic, and it is often necessary to take definitive impressions of teeth coated with some saliva. New hydrophilic materials have been developed. The purpose of this in vitro study was to compare contact angles of water and saliva on 7 unset elastomeric impression materials at 5 time points from the start of mixing. Two traditional polyvinyl siloxane (PVS) (Aquasil, Take 1), 2 modified PVS (Imprint 4, Panasil), a polyether (Impregum), and 2 hybrid (Identium, EXA'lence) materials were compared. Each material was flattened to 2 mm and a 5 μL drop of distilled water or saliva was dropped on the surface at 25 seconds (t0) after the start of mix. Contact angle measurements were made with a digital microscope at initial contact (t0), t1=2 seconds, t2=5 seconds, t3=50% working time, and t4=95% working time. Data were analyzed with a generalized linear mixed model analysis, and individual 1-way ANOVA and Tukey HSD post hoc tests (α=.05). For water, materials grouped into 3 categories at all time-points: the modified PVS and one hybrid material (Identium) produced the lowest contact angles, the polyether material was intermediate, and the traditional PVS materials and the other hybrid (EXA'lence) produced the highest contact angles. For saliva, Identium, Impregum, and Imprint 4 were in the group with the lowest contact angle at most time points. Modified PVS materials and one of the hybrid materials are more hydrophilic than traditional PVS materials when measured with water. Saliva behaves differently than water in contact angle measurement on unset impression material and produces a lower contact angle on polyether based materials. Copyright © 2015 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Effect of skin hydration on the dynamics of fingertip gripping contact.

Science.gov (United States)

André, T; Lévesque, V; Hayward, V; Lefèvre, P; Thonnard, J-L

2011-11-07

The dynamics of fingertip contact manifest themselves in the complex skin movements observed during the transition from a stuck state to a fully developed slip. While investigating this transition, we found that it depended on skin hydration. To quantify this dependency, we asked subjects to slide their index fingertip on a glass surface while keeping the normal component of the interaction force constant with the help of visual feedback. Skin deformation inside the contact region was imaged with an optical apparatus that allowed us to quantify the relative sizes of the slipping and sticking regions. The ratio of the stuck skin area to the total contact area decreased linearly from 1 to 0 when the tangential force component increased from 0 to a maximum. The slope of this relationship was inversely correlated to the normal force component. The skin hydration level dramatically affected the dynamics of the contact encapsulated in the course of evolution from sticking to slipping. The specific effect was to reduce the tendency of a contact to slip, regardless of the variations of the coefficient of friction. Since grips were more unstable under dry skin conditions, our results suggest that the nervous system responds to dry skin by exaggerated grip forces that cannot be simply explained by a change in the coefficient of friction.

[Eyelid hygiene for contact lens wearers with blepharitis. Comparative investigation of treatment with baby shampoo versus phospholipid solution].

Science.gov (United States)

Khaireddin, R; Hueber, A

2013-02-01

Blepharitis due to Meibom gland dysfunction (MGD) is presumed to be one of the main reasons for dry eye symptoms which occur in up to 50% of contact lens users. Thus, MGD presumably plays an important role in dry eye in contact lens wearers. In the present prospective, randomized and double blind trial the efficacy of two established treatment options for MGD and blepharitis was evaluated in symptomatic contact lens wearers. In this prospective, randomized 2-centre trial 53 symptomatic contact lens wearers suffering from blepharitis were included. Patients were randomly selected for two treatment groups: group A performed lid margin hygiene using the commonly recommended mild baby shampoo (Bübchen Kinder Shampoo-extra augenmild, Bübchen Werk Ewald Hermes Pharmazeutische Fabrik GmbH, Soest, Germany) and group B performed lid margin hygiene using a phospholipid-liposome solution specially designed for lid hygiene (Blepha Cura, Optima, Moosburg/Wang, Germany), each for 4 weeks. Before as well as 4 weeks after initiation of this study the following tests were performed: standardized subjective assessment using the ocular surface disease index, non-invasive break-up time (NIBUT) and objective evaluation of lid-parallel conjunctival folds (LIPCOF) and further lid margin criteria by double blinded evaluation of slit lamp photographs. Of the 53 symptomatic contact lens wearers suffering from blepharitis 21 (39,6%) were randomly selected for treatment group A and 32 (60.4%) for group B. In both treatment groups there was objective and subjective improvement of symptoms of dry eye in contact lens wearers. Interestingly, there was a significantly greater improvement, subjective as well as objective, in treatment group B which used the phospholipidliposome solution for lid margin hygiene compared to group A using baby shampoo. Although both therapies improved symptoms of dry eye due to blepharitis in symptomatic contact lens wearers, patients using phospholipid

Two gap superconductivity in Ba{sub 0.55}K{sub 0.45}Fe{sub 2}As{sub 2} single crystals studied by the directional point-contact Andreev reflection spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Szabo, P.; Pribulova, Z. [Centre of Low Temperature Physics, IEP Slovak Academy of Sciences and P.J.Safarik University, Watsonova 47, SK-04001 Kosice (Slovakia); Pristas, G.; Bud' ko, S.L.; Canfield, P.C. [Ames Laboratory and Iowa State University, Ames, IA 50011 (United States); Samuely, P., E-mail: samuely@saske.s [Centre of Low Temperature Physics, IEP Slovak Academy of Sciences and P.J.Safarik University, Watsonova 47, SK-04001 Kosice (Slovakia)

2009-10-15

First directional point-contact Andreev reflection spectroscopy on the Ba{sub 0.55}K{sub 0.45}Fe{sub 2}As{sub 2} single crystals is presented. The spectra show significant differences when measured in the ab plane in comparison with those measured in the c direction. In the latter case no traces of superconducting energy gap could be found, just a reduced point-contact conductance persisting up to about 100 K and indicating reduced density of states. On the other hand within the ab plane two nodeless superconducting energy gaps DELTA{sub S}approx2-5 meV and DELTA{sub L}approx9-11 meV are detected.

Influence of product thickness, chamber pressure and heating conditions on production rate of freeze-dried yoghurt

Energy Technology Data Exchange (ETDEWEB)

Sharma, N.K. [G.B. Pant Univ., of Agriculture and Technology (India). Dept. of Mechanical Engineering; Arora, C.P. [Indian Inst. of Tech., New Delhi (India)

1995-06-01

The effects of product thickness, chamber pressure and heating conditions on product temperature profiles and production rate of freeze-dried yoghurt were investigated experimentally. Three sample thicknesses - 3.8 mm, 6.2 mm and 9.4 mm - were tested at chamber pressures of 0.01 and 0.5 mmHg. The production rate increased by decreasing product thickness in contact heating through the bottom of the frozen layer, whereas no significant change was observed in radiant heating. A reduction in chamber pressure from 0.50 to 0.01 mmHg increased the drying time in radiant heating. Maximum production rate was obtained when the thickness of dried product was 6.2 mm, when heat was transferred simultaneously through the frozen and dried layers, and the chamber pressure was at 0.01 mmHg. Use of the product tray developed in this study prevents the growth of dry layers at the contact surfaces. (Author)

Contact conductance between graphene and quantum wires

International Nuclear Information System (INIS)

Li Haidong; Zheng Yisong

2009-01-01

The contact conductance between graphene and two quantum wires which serve as the leads to connect graphene and electron reservoirs is theoretically studied. Our investigation indicates that the contact conductance depends sensitively on the graphene-lead coupling configuration. When each quantum wire couples solely to one carbon atom, the contact conductance vanishes at the Dirac point if the two carbon atoms coupling to the two leads belong to the same sublattice of graphene. We find that such a feature arises from the chirality of the Dirac electron in graphene. Such a chirality associated with conductance zero disappears when a quantum wire couples to multiple carbon atoms. The general result irrelevant to the coupling configuration is that the contact conductance decays rapidly with the increase of the distance between the two leads. In addition, in the weak graphene-lead coupling limit, when the distance between the two leads is much larger than the size of the graphene-lead contact areas and the incident electron energy is close to the Dirac point, the contact conductance is proportional to the square of the product of the two graphene-lead contact areas, and inversely proportional to the square of the distance between the two leads

Contact and contagion: Probability of transmission given contact varies with demographic state in bighorn sheep.

Science.gov (United States)

Manlove, Kezia R; Cassirer, E Frances; Plowright, Raina K; Cross, Paul C; Hudson, Peter J

2017-07-01

Understanding both contact and probability of transmission given contact are key to managing wildlife disease. However, wildlife disease research tends to focus on contact heterogeneity, in part because the probability of transmission given contact is notoriously difficult to measure. Here, we present a first step towards empirically investigating the probability of transmission given contact in free-ranging wildlife. We used measured contact networks to test whether bighorn sheep demographic states vary systematically in infectiousness or susceptibility to Mycoplasma ovipneumoniae, an agent responsible for bighorn sheep pneumonia. We built covariates using contact network metrics, demographic information and infection status, and used logistic regression to relate those covariates to lamb survival. The covariate set contained degree, a classic network metric describing node centrality, but also included covariates breaking the network metrics into subsets that differentiated between contacts with yearlings, ewes with lambs, and ewes without lambs, and animals with and without active infections. Yearlings, ewes with lambs, and ewes without lambs showed similar group membership patterns, but direct interactions involving touch occurred at a rate two orders of magnitude higher between lambs and reproductive ewes than between any classes of adults or yearlings, and one order of magnitude higher than direct interactions between multiple lambs. Although yearlings and non-reproductive bighorn ewes regularly carried M. ovipneumoniae, our models suggest that a contact with an infected reproductive ewe had approximately five times the odds of producing a lamb mortality event of an identical contact with an infected dry ewe or yearling. Consequently, management actions targeting infected animals might lead to unnecessary removal of young animals that carry pathogens but rarely transmit. This analysis demonstrates a simple logistic regression approach for testing a priori

Effect of hot-air drying on the physicochemical properties of kaffir lime leaves (Citrus hystrix)

OpenAIRE

Juhari, Nurul Hanisah Binti; Lasekan, Ola; Muhammad, Kharidah; Karim, Shahrim

2013-01-01

The effect of hot-air drying namely drying time (3-15 h), drying temperature (40-80°C) and loading capacity (0.5-2.0 kg/m2 ) on the physicochemical characteristics of kaffir lime leaves was optimized using Response Surface Methodology. Twenty treatments were assigned based on the second- order CCD including 6 center points, 6 axial points and 8 factorial points. The quality of dried kaffir lime leaves was evaluated by determining moisture content, water activity, texture (brittleness) and Hun...

Existence for viscoplastic contact with Coulomb friction problems

Directory of Open Access Journals (Sweden)

Amina Amassad

2002-01-01

frictional contact between an elastic-viscoplastic body and a rigid obstacle. We model the frictional contact both by a Tresca's friction law and a regularized Coulomb's law. We assume, in a first part, that the contact is bilateral and that no separation takes place. In a second part, we consider the Signorini unilateral contact conditions. Proofs are based on a time-discretization method, Banach and Schauder fixed point theorems.

Automatic quantification of tibio-femoral contact area and congruity

DEFF Research Database (Denmark)

Tummala, Sudhakar; Nielsen, Mads; Lillholm, Martin

2012-01-01

We present methods to quantify the medial tibio- femoral (MTF) joint contact area (CA) and congruity index (CI) from low-field magnetic resonance imaging (MRI). Firstly, based on the segmented MTF cartilage compartments, we computed the contact area using the Euclidian distance transformation....... The CA was defined as the area of the tibial superior surface and the femoral inferior surface that are less than a voxel width apart. Furthermore, the CI is computed point-by-point by assessing the first- and second-order general surface features over the contact area. Mathematically, it is the inverse...

Department of Energy Review of Laboratory Programs for Women Points-of-Contact Committee: Comparative Report, June 1995

Energy Technology Data Exchange (ETDEWEB)

McLane, V.; Layne, A.

1995-06-01

A survey of the DOE facilities was undertaken by the Points-of-Contact for the DOE Review of Laboratory Programs for Women in order to gather data to be used as a baseline against which to measure future progress. We plan to look at current programs already in place and evaluate them with a view to deciding which programs are most effective, and selecting model programs suitable for implementation at other facilities. The survey focused on four areas: 1) statistical data, 2) laboratory policy, 3) formal and informal programs which affect the quality of life in the work environment, and career development and advancement, and 4) educational programs. Although this report focuses on women, the problems discussed affect all DOE facility employees.

A superellipsoid-plane model for simulating foot-ground contact during human gait.

Science.gov (United States)

Lopes, D S; Neptune, R R; Ambrósio, J A; Silva, M T

2016-01-01

Musculoskeletal models and forward dynamics simulations of human movement often include foot-ground interactions, with the foot-ground contact forces often determined using a constitutive model that depends on material properties and contact kinematics. When using soft constraints to model the foot-ground interactions, the kinematics of the minimum distance between the foot and planar ground needs to be computed. Due to their geometric simplicity, a considerable number of studies have used point-plane elements to represent these interacting bodies, but few studies have provided comparisons between point contact elements and other geometrically based analytical solutions. The objective of this work was to develop a more general-purpose superellipsoid-plane contact model that can be used to determine the three-dimensional foot-ground contact forces. As an example application, the model was used in a forward dynamics simulation of human walking. Simulation results and execution times were compared with a point-like viscoelastic contact model. Both models produced realistic ground reaction forces and kinematics with similar computational efficiency. However, solving the equations of motion with the surface contact model was found to be more efficient (~18% faster), and on average numerically ~37% less stiff. The superellipsoid-plane elements are also more versatile than point-like elements in that they allow for volumetric contact during three-dimensional motions (e.g. rotating, rolling, and sliding). In addition, the superellipsoid-plane element is geometrically accurate and easily integrated within multibody simulation code. These advantages make the use of superellipsoid-plane contact models in musculoskeletal simulations an appealing alternative to point-like elements.

Static or breakloose friction for lubricated contacts: the role of surface roughness and dewetting

International Nuclear Information System (INIS)

Lorenz, B; Persson, B N J; Krick, B A; Sawyer, W G; Rodriguez, N; Mangiagalli, P

2013-01-01

We present experimental data for the static or breakloose friction for lubricated elastomer contacts, as a function of the time of stationary contact. Due to fluid squeeze-out from the asperity contact regions, the breakloose friction force increases continuously with the time of stationary contact. We consider three different cases: (a) PDMS rubber balls against flat smooth glass surfaces, (b) PDMS cylinder ribs against different substrates (glass, smooth and rough PMMA and an inert polymer) and (c) application to syringes. Due to differences in the surface roughness and contact pressures the three systems exhibit very different time dependences of the breakloose friction. In case (a) for rough surfaces the dry contact area A is a small fraction of the nominal contact area A 0 , and the fluid squeeze-out is fast. In case (b) the dry contact area is close to the nominal contact area, A/A 0 ≈ 1, and fluid squeeze-out is very slow due to percolation of the contact area. In this case, remarkably, different fluids with very different viscosities, ranging from 0.005 Pa s (water–glycerol mixture) to 1.48 Pa s (glycerol), give very similar breakloose friction forces as a function of the time of stationary contact. In case (c) the contact pressure and the surface roughness are larger than in case (b), and the squeeze-out is very slow so that even after a very long time the area of real contact is below the percolation threshold. For all cases (a)–(c), the increase in the breakloose friction is mainly due to the increase in the area of real contact with increasing time, because of the fluid squeeze-out and dewetting. (paper)

Static or breakloose friction for lubricated contacts: the role of surface roughness and dewetting.

Science.gov (United States)

Lorenz, B; Krick, B A; Rodriguez, N; Sawyer, W G; Mangiagalli, P; Persson, B N J

2013-11-06

We present experimental data for the static or breakloose friction for lubricated elastomer contacts, as a function of the time of stationary contact. Due to fluid squeeze-out from the asperity contact regions, the breakloose friction force increases continuously with the time of stationary contact. We consider three different cases: (a) PDMS rubber balls against flat smooth glass surfaces, (b) PDMS cylinder ribs against different substrates (glass, smooth and rough PMMA and an inert polymer) and (c) application to syringes. Due to differences in the surface roughness and contact pressures the three systems exhibit very different time dependences of the breakloose friction. In case (a) for rough surfaces the dry contact area A is a small fraction of the nominal contact area A0, and the fluid squeeze-out is fast. In case (b) the dry contact area is close to the nominal contact area, A/A0 ≈ 1, and fluid squeeze-out is very slow due to percolation of the contact area. In this case, remarkably, different fluids with very different viscosities, ranging from 0.005 Pa s (water–glycerol mixture) to 1.48 Pa s (glycerol), give very similar breakloose friction forces as a function of the time of stationary contact. In case (c) the contact pressure and the surface roughness are larger than in case (b), and the squeeze-out is very slow so that even after a very long time the area of real contact is below the percolation threshold. For all cases (a)–(c), the increase in the breakloose friction is mainly due to the increase in the area of real contact with increasing time, because of the fluid squeeze-out and dewetting.

Effect of gamma radiation on graphite – PTFE dry lubrication system

International Nuclear Information System (INIS)

Singh, Sachin; Tyagi, Mukti; Seshadri, Geetha; Tyagi, Ajay Kumar; Varshney, Lalit

2017-01-01

An effect of gamma radiation on lubrication behavior of graphite -PTFE dry lubrication system has been studied using (TR-TW-30L) tribometer with thrust washer attachment in plane contact. Different compositions of graphite and PTFE were prepared and irradiated by gamma rays. Gamma radiation exposure significantly improves the tribological properties indicated by decrease in coefficient of friction and wear properties of graphite -PTFE dry lubrication system. SEM and XRD analysis confirm the physico-chemical modification of graphite-PTFE on gamma radiation exposure leading to a novel dry lubrication system with good slip and anti friction properties. - Highlights: • Novel dry lubrication system of graphite -PTFE using gamma radiation. • Gamma radiation processing. • Reduction in coefficient of friction, frictional torque and wear loss of developed dry lubrication system.

Multigap superconductivity and strong electron-boson coupling in Fe-based superconductors: a point-contact Andreev-reflection study of Ba(Fe(1-x)Co(x))2As2 single crystals.

Science.gov (United States)

Tortello, M; Daghero, D; Ummarino, G A; Stepanov, V A; Jiang, J; Weiss, J D; Hellstrom, E E; Gonnelli, R S

2010-12-03

Directional point-contact Andreev-reflection measurements in Ba(Fe(1-x)Co(x))2As2 single crystals (T(c) = 24.5 K) indicate the presence of two superconducting gaps with no line nodes on the Fermi surface. The point-contact Andreev-reflection spectra also feature additional structures related to the electron-boson interaction, from which the characteristic boson energy Ω(b)(T) is obtained, very similar to the spin-resonance energy observed in neutron scattering experiments. Both the gaps and the additional structures can be reproduced within a three-band s ± Eliashberg model by using an electron-boson spectral function peaked at Ω(0) = 12 meV ≃ Ω(b)(0).

The Occurrence of Anomalous Conductance Plateaus and Spin Textures in Quantum Point Contacts

Science.gov (United States)

Wan, J.; Cahay, M.; Debray, P.; Newrock, R.

2010-03-01

Recently, we used a NEGF formalism [1] to provide a theoretical explanation for the experimentally observed 0.5G0 (G0=2e^2/h) plateau in the conductance of side-gated quantum point contacts (QPCs) in the presence of lateral spin-orbit coupling (LSOC) [2]. We showed that the 0.5G0 plateau appears in the QPCs without any external magnetic field as a result of three ingredients: an asymmetric lateral confinement, a LSOC, and a strong electron-electron (e-e) interaction. In this report, we present the results of simulations for a wide range of QPC dimensions and biasing parameters showing that the same physics predicts the appearance of other anomalous plateaus at non-integer values of G0, including the well-known 0.7G0 anomaly. These features are related to a plethora of spin textures in the QPC that depend sensitively on material, device, biasing parameters, temperature, and the strength of the e-e interaction. [1] J. Wan, M. Cahay, P. Debray, and R.S. Newrock, Phys. Rev. B 80, 155440 (2009). [2] P. Debray, S.M. Rahman, J. Wan, R.S. Newrock, M. Cahay, A.T. Ngo, S.E. Ulloa, S.T. Herbert, M. Muhammad, and M. Johnson, Nature Nanotech. 4, 759 (2009).

Chemical composition, antioxidant capacity, and sensory quality of dried jujube fruits as affected by cultivar and drying method.

Science.gov (United States)

Wojdyło, Aneta; Figiel, Adam; Legua, Pilar; Lech, Krzysztof; Carbonell-Barrachina, Ángel A; Hernández, Francisca

2016-09-15

The aim of this study was to determine the effect of different dying methods, such as convective drying (CD: 50, 60, 70 °C), vacuum-microwave drying (VMD: 120, 480, 480-120 W), a combination of convective pre-drying and vacuum-microwave finish drying [(CPD (60 °C)-VMFD (480-120 W)], and freeze-drying (FD) on key quality parameters of dried jujube fruits (cv. "GAL", "MSI", and "PSI"). The parameters studied included bioactive compounds (flavan-3-ols and flavonols, identified by LC-PDA-MS, and vitamin C), antioxidant capacity (ABTS and FRAP), and sensory attributes (e.g. hardness, jujube-ID, and sweetness). The best quality of the dried product (high contents of bioactive compounds and high intensity of key sensory attributes) was found in fruits treated by FD and VMD 480-120 W. The best cultivars were "PSI" and "GAL" from the point of view of bioactive content and sensory quality, respectively. Copyright © 2016 Elsevier Ltd. All rights reserved.

Implementation of hazard analysis and critical control point (HACCP) in dried anchovy production process

Science.gov (United States)

Citraresmi, A. D. P.; Wahyuni, E. E.

2018-03-01

The aim of this study was to inspect the implementation of Hazard Analysis and Critical Control Point (HACCP) for identification and prevention of potential hazards in the production process of dried anchovy at PT. Kelola Mina Laut (KML), Lobuk unit, Sumenep. Cold storage process is needed in each anchovy processing step in order to maintain its physical and chemical condition. In addition, the implementation of quality assurance system should be undertaken to maintain product quality. The research was conducted using a survey method, by following the whole process of making anchovy from the receiving raw materials to the packaging of final product. The method of data analysis used was descriptive analysis method. Implementation of HACCP at PT. KML, Lobuk unit, Sumenep was conducted by applying Pre Requisite Programs (PRP) and preparation stage consisting of 5 initial stages and 7 principles of HACCP. The results showed that CCP was found in boiling process flow with significant hazard of Listeria monocytogenesis bacteria and final sorting process with significant hazard of foreign material contamination in the product. Actions taken were controlling boiling temperature of 100 – 105°C for 3 - 5 minutes and training for sorting process employees.

The response of an individual vortex to local mechanical contact

Science.gov (United States)

Kremen, Anna; Wissberg, Shai; Shperber, Yishai; Kalisky, Beena

2016-05-01

Recently we reported a new way to manipulate vortices in thin superconducting films by local mechanical contact without magnetic field, current or altering the pinning landscape [1]. We use scanning superconducting interference device (SQUID) microscopy to image the vortices, and a piezo element to push the tip of a silicon chip into contact with the sample. As a result of the stress applied at the contact point, vortices in the proximity of the contact point change their location. Here we study the characteristics of this vortex manipulation, by following the response of individual vortices to single contact events. Mechanical manipulation of vortices provides local view of the interaction between strain and nanomagnetic objects, as well as controllable, effective, localized, and reproducible manipulation technique.

Mathematical Modeling of Contact Problems of Elasticity Theory with Unilateral Discrete Contact

Directory of Open Access Journals (Sweden)

I. V. Stankevich

2015-01-01

Full Text Available Development and operation of modern machinery and latest technology require reliable estimates of the strength characteristics of the critical elements of structures and technological equipment under the impact of high-intensity thermomechanical loading, accompanied, as a rule, by complex contact interaction. Mathematical modeling of stress-strain state of such parts and components in the contact area, based on adequate mathematical models, modern numerical methods and efficient algorithms that implement the direct determination of displacement fields, strains and stresses, is the main tool that allows fast acquisition of data required for the calculations of strength and durability. The paper considers an algorithm for constructing the numerical solution of the contact problem of elasticity theory in relation to the body, which has an obvious one-sided discrete contact interaction with an elastic half-space. The proposed algorithm is specially designed to have a correction of the tangential forces at discrete contact points, allowing us to achieve sufficiently accurate implementation of the adopted law of friction. The algorithm is embedded in a general finite element technology, with which the application code is generated. Numerical study of discrete unilateral contact interaction of an elastic plate and a rigid half-space showed a high efficiency of the developed algorithm and the application code that implements it.

Microwave-Osmotic/Microwave-Vacuum Drying of Whole Cranberries: Comparison with Other Methods.

Science.gov (United States)

Wray, Derek; Ramaswamy, Hosahalli S

2015-12-01

A novel drying method for frozen-thawed whole cranberries was developed by combining microwave osmotic dehydration under continuous flow medium spray (MWODS) conditions with microwave vacuum finish-drying. A central composite rotatable design was used to vary temperature (33 to 67 °C), osmotic solution concentration (33 to 67 °B), contact time (5 to 55 min), and flow rate (2.1 to 4.1 L/min) in order to the determine the effects of MWODS input parameters on quality of the dried berry. Quality indices monitored included colorimetric and textural data in addition to anthocyanin retention and cellular structure. Overall it was found that the MWODS-MWV process was able to produce dried cranberries with quality comparable to freeze dried samples in much shorter time. Additionally, cranberries dried via the novel process exhibited much higher quality than those dried via either vacuum or convective air drying in terms of color, anthocyanin content, and cellular structure. © 2015 Institute of Food Technologists®

The Troy Microneedle: A Rapidly Separating, Dissolving Microneedle Formed by Cyclic Contact and Drying on the Pillar (CCDP).

Science.gov (United States)

Kim, Miroo; Yang, Huisuk; Kim, Suyong; Lee, Chisong; Jung, Hyungil

2015-01-01

In dissolving microneedle (DMN)-mediated therapy, complete and rapid delivery of DMNs is critical for the desired efficacy. Traditional patch-based DMN delivery, however, may fail due to incomplete delivery from insufficient skin insertion or rapid separation of microneedles due to their strong bond to the backing film. Here, we introduce the Troy microneedle, which was created by cyclic contact and drying on the pillar (CCDP), and which enabled simultaneous complete and rapid delivery of DMN. This CCDP process could be flexibly repeated to achieve a specific desired drug dose in a DMN. We evaluated DMN separation using agarose gel, and the Troy microneedle achieved more complete and rapid separation than other, more deeply dipped DMN, primarily because of the Troy's minimal junction between the DMN and pillar. When Troy microneedles were applied to pig cadaver skin, it took only 15 s for over 90% of encapsulated rhodamine B to be delivered, compared to 2 h with application of a traditional DMN patch. In vivo skin penetration studies demonstrated rapid DMN-separation of Troy microneedles still in solid form before dissolution. The Troy microneedle overcomes critical issues associated with the low penetration efficiency of flat patch-based DMN and provides an innovative route for DMN-mediated therapy, combining patient convenience with the desire drug efficacy.

48 CFR 15.604 - Agency points of contact.

Science.gov (United States)

2010-10-01

... agency: upcoming solicitations; Broad Agency Announcements; Small Business Innovation Research programs; Small Business Technology Transfer Research programs; Program Research and Development Announcements; or... CONTRACTING METHODS AND CONTRACT TYPES CONTRACTING BY NEGOTIATION Unsolicited Proposals 15.604 Agency points...

A preliminary investigation into the effects of ocular lubricants on higher order aberrations in normal and dry eye subjects.

Science.gov (United States)

McGinnigle, Samantha; Eperjesi, Frank; Naroo, Shehzad A

2014-04-01

To study the effects of ocular lubricants on higher order aberrations in normal and self-diagnosed dry eyes. Unpreserved hypromellose drops, Tears Again™ liposome spray and a combination of both were administered to the right eye of 24 normal and 24 dry eye subjects following classification according to a 5 point questionnaire. Total ocular higher order aberrations, coma, spherical aberration and Strehl ratios for higher order aberrations were measured using the Nidek OPD-Scan III (Nidek Technologies, Gamagori, Japan) at baseline, immediately after application and after 60 min. The aberration data were analyzed over a 5mm natural pupil using Zernike polynomials. Each intervention was assessed on a separate day and comfort levels were recorded before and after application. Corneal staining was assessed and product preference recorded after the final measurement for each intervention. Hypromellose drops caused an increase in total higher order aberrations (p=dry eyes) and a reduction in Strehl ratio (normal eyes: p=dry eyes p=0.01) immediately after instillation. There were no significant differences between normal and self-diagnosed dry eyes for response to intervention and no improvement in visual quality or reduction in higher order aberrations after 60 min. Differences in comfort levels failed to reach statistical significance. Combining treatments does not offer any benefit over individual treatments in self-diagnosed dry eyes and no individual intervention reached statistical significance. Symptomatic subjects with dry eye and no corneal staining reported an improvement in comfort after using lubricants. Copyright © 2013 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Response function of a moving contact line

Science.gov (United States)

Perrin, H.; Belardinelli, D.; Sbragaglia, M.; Andreotti, B.

2018-04-01

The hydrodynamics of a liquid-vapor interface in contact with a heterogeneous surface is largely impacted by the presence of defects at the smaller scales. Such defects introduce morphological disturbances on the contact line and ultimately determine the force exerted on the wedge of liquid in contact with the surface. From the mathematical point of view, defects introduce perturbation modes, whose space-time evolution is governed by the interfacial hydrodynamic equations of the contact line. In this paper we derive the response function of the contact line to such generic perturbations. The contact line response may be used to design simplified one-dimensional time-dependent models accounting for the complexity of interfacial flows coupled to nanoscale defects, yet offering a more tractable mathematical framework to explore contact line motion through a disordered energy landscape.

Quantum Point Contacts as Spin Injectors and Detectors for Studying Rasha Spin Precession in Semiconductor Quantum Wires

Science.gov (United States)

Debray, Philippe; Shorubalko, Ivan; Xu, Hongqi

2007-03-01

We have studied polarized spin transport in a device consisting of three quantum point contacts (QPCs) in series made on InGaAs/InP quantum-well (QW) structures. The QPCs were created by independent pairs of side gates, each pair for one QPC. By adjusting the bias voltages of the side gates, the widths of the QPCs are independently tuned to have transport in the fundamental mode. An external magnetic field of a few T causes spin splitting of the lowest one-dimensional (1D) subbands. The widths of the end QPCs are adjusted to position the Fermi level in the spin-split energy gap, while that of the central QPC is kept wide enough to populate both spin-split bands. Measurement of the conductance of the end QPCs at low temperatures (spinFET.

Dynamics of the Molten Contact Line

Science.gov (United States)

Sonin, Ain A.; Duthaler, Gregg; Liu, Michael; Torresola, Javier; Qiu, Taiqing

1999-01-01

The purpose of this program is to develop a basic understanding of how a molten material front spreads over a solid that is below its melting point, arrests, and freezes. Our hope is that the work will contribute toward a scientific knowledge base for certain new applications involving molten droplet deposition, including the "printing" of arbitrary three-dimensional objects by precise deposition of individual molten microdrops that solidify after impact. Little information is available at this time on the capillarity-driven motion and arrest of molten contact line regions. Schiaffino and Sonin investigated the arrest of the contact line of a molten microcrystalline wax spreading over a subcooled solid "target" of the same material. They found that contact line arrest takes place at an apparent liquid contact angle that depends primarily on the Stefan number S=c(T(sub f) -T(sub t)/L based on the temperature difference between the fusion point and the target temperature, and proposed that contact line arrest occurs when the liquid's dynamic contact angle approaches the angle of attack of the solidification front just behind the contact line. They also showed, however, that the conventional continuum equations and boundary conditions have no meaningful solution for this angle. The solidification front angle is determined by the heat flux just behind the contact line, and the heat flux is singular at that point. By comparing experiments with numerical computations, Schiaffino and Sonin estimated that the conventional solidification model must break down within a distance of order 0.1 - 1 microns of the contact line. The physical mechanism for this breakdown is as yet undetermined, and no first-principles theory exists for the contact angle at arrest. Schiaffino and Sonin also presented a framework for understanding how to moderate Weber number molten droplet deposition in terms of similarity laws and experimentation. The study is based on experiments with three molten

Gas turbine applications in the drying industry

Energy Technology Data Exchange (ETDEWEB)

Tapper, R.C.

2000-07-01

The purpose of this report is to determine if it is feasible to utilize the hot exhaust gas discharged from gas turbines in direct applications. This report illustrates the technical feasibility and economic viability of using gas turbines in drying applications. The size of turbines in this investigation ranges from 2 MW to 10 MW. In addition, an implementation strategy has been developed to employ this new system. The method used to structure the scope of this undertaking is as follows: Step 1. Collecting information by contacting dryer manufacturer and companies drying different products. Information was also gathered by literature studies and the internet. Thomas register is a great tool when it comes to company and market searches. Step 2. Looking into if it is technically possible to use the exhaust gas directly into dryers. The parameters needed for these calculations were gathered in step 1, and some of the more important are temperature, mass flow, heat demand, and information about how the dryer works. The computer program Gatecycle is a great help when it comes to finding the right turbine for a dryer. Step 3. When it was obvious that it would work for some drying applications, the profitability was tested with the help of some spreadsheets. Step 4. The market was also evaluated as a last step. Market analysis was performed with the help of Porter's (Porter is one of the most famous strategy gurus) different models. The point of this is to find ways to be unique so that competitors will have a harder time copying the new system. It is shown in the report that for the right kind of projects, this new application for turbines is profitable. It is important to realize that this new system is not profitable for every drying plant. This is a general study with general input parameters. Every plant has its' own in-parameters and has to be evaluated individually. The most important factors determining if it is profitable or not are: Local electricity

Clinical measurement of the height of the interproximal contact area in maxillary anterior teeth.

Science.gov (United States)

Sghaireen, Mohd G; Al-Zarea, Bader K; Al-Shorman, Hisham M; Al-Omiri, Mahmoud K

2013-11-01

To clinically quantify the apicoincisal height of interproximal areas directly in patients' mouths. Thirty participants (11 females and 9 males, mean age=26±1.5 years) were recruited into this study. Measurement of interproximal contact areas was carried out directly in patients' mouths using digital caliper (TERENSA, USA) with measuring accuracy of 0.01 mm. The interproximal contact areas that were measured are: central incisor to central incisor, central incisor to lateral incisor, lateral incisor to canine, and canine to first premolar on both sides of the jaw. Statistical significance was based on probability values less than 0.05 (pcontact point was the one present between central incisors and it ranged from 2.9 to 6.5 mm. On the other hand, the contact point between canine and first premolar was the smallest on both sides of the arch and ranged from 0.6 to 2.5 mm. The dimensions of the contact points declined as we move from anterior area backwards. Statistical analysis using t-test showed that there were significant differences between the measurements of interproximal points of each tooth (Pcontact point decreased as we moved from anterior to posterior teeth. The contact area between the central incisors was largest and the one between canine and premolar was the smallest. This study is the first to report direct intra-oral clinical measurement of contact points. Clinical evaluation of contact point dimensions using digital caliber is a viable, quick and accurate method to use.

Heat transfer characteristics of a direct contact heat exchanger

International Nuclear Information System (INIS)

Kinoshita, I.; Nishi, Y.

1993-01-01

As a first step for development of a direct contact steam generator for FBRs, fundamental heat transfer characteristics of a liquid-liquid contact heat exchanger were evaluated by heat transfer experiment with low melting point alloy and water. Distinctive characteristics of direct contact heat transfer with liquid metal and water was obtained. (author)

Energy-saving drying and its application

Science.gov (United States)

Kovbasyuk, V. I.

2015-09-01

Superheated steam is efficiently applied as a coolant for the intensification of drying, which is an important component of many up-to-date technologies. However, traditional drying is extremely energy consuming, and many drying apparatus are environmentally unfriendly. Thus, it is important to implement the proposed drying technique using superheated steam under pressure significantly higher than the atmospheric one with subsequent steam transfer for use in a turbine for electric power generation as a compensation of energy costs for drying. This paper includes a brief thermodynamic analysis of such a technique, its environmental advantages, and possible benefits of the use of wet wastes and obtaining high-quality fuels from wet raw materials. A scheme is developed for the turbine protection from impurities that can occur in the steam at drying. Potential advantage of the technique are also the absence of heating surfaces that are in contact with wet media, the absence of the emissions to the atmosphere, and the use of low potential heat for desalination and the purification of water. The new drying technique can play an extremely important part in the implementation in the field of thermal destruction of anthropogenic wastes. In spite of the promotion of waste sorting to obtain valuable secondary raw materials, the main problem of big cities is nonutilizable waste, which makes not less than 85% of the starting quantity of waste. This can only be totally solved by combustion, which even more relates to the sewage sludge utilization. The wastes can be safely and efficiently combusted only provided that they are free of moisture. Combustion temperature optimization makes possible full destruction of dioxins and their toxic analogues.

The Effect of Dry Needling of the Trigger Points of Shoulder Muscles on Pain and Grip Strength in Patients with Lateral Epicondylitis: A Pilot Study

Directory of Open Access Journals (Sweden)

Alireza Kheradmandi

2015-09-01

Full Text Available Background: Lateral epicondylitis, also known as tennis elbow, is the most common overuse syndrome of the elbow. The severity of pain may not be directly caused by tendinopathy of wrist extensors since trigger points of the shoulder muscles have a referral zone in the arm and elbow. Therefore the aim of this study was to evaluate the effect of dry needling of shoulder myofascial trigger points on wrist extensors muscles pain and function. Methods: Fourteen female patients with tennis elbow (aged 20 - 45 years old were recruited after primary evaluation by an orthopedist. They entered the study if they had pain in the lateral aspect of elbow of the dominant hand for more than 3 months along with the presence of myofascial trigger points in any muscles of supra spinatus, infra spinatus, sub scapularis or scalenes. Pain pressure threshold, maximal grip force and pain intensity of the hand extensors on lateral epicondyle of elbow were measured before and after treatment. Pain intensity was measured on a one to ten scale of visual analogue scale (VAS. A hand dynamometer used to measure the maximal grip force value of the affected hand in 0˚shoulder flexion/ abduction, 90˚ elbow extension and mid-poison of forearm in sitting position. A pressure algometer was applied on hand extensor muscles to define their trigger point sensitivity. For the control group, treatment regimens consisted of routine physical therapy of tennis elbow. This regime was accompanied by dry needling of mentioned muscles for the intervention group. Wilcoxon and Mann-Whitney non-parametric tests were used for statistical analysis. Results: Comparison of the results after intervention showed that the patients’ pain significantly decreased in both groups (P<0.001; but the patient’s PPT and grip force significantly increased solely in the intervention group (P<0.05. Mann Whitney test showed significant pain differences in both groups (P=0.001. The comparison of differences

Drying of plasterboard - some quality aspects

Energy Technology Data Exchange (ETDEWEB)

Naesman, L. (University of Lund (Sweden)); Wimmerstedt, R. (University of Lund (Sweden))

1993-06-01

The manufacture process, especially the drying operation, of plasterboard was studied. The purpose was to measure physical properties, which can be used for the optimization of the process with respect to energy and quality. The cardboard was found to be hygroscopic whereas the gypsum was not. It was determined that the chloride content in the gypsum raw material should not exceed 75 ppm. The starch was found to migrate towards the surface of the gypsum core during the drying process (air temperture 140 C, dew-point of air 30 C and air velocity 10 m/s). The drying of different qualitites of plasterboard was also investigated. It was found that the cardboard is a very important parameter whereas the gypsum core has little effect on the drying rate and core temperature. (orig.)

Intraoral versus extraoral measurement of the height of the interproximal contact area in maxillary anterior teeth.

Science.gov (United States)

Sghaireen, Mohd G; Albhiran, Heyam Mobark; Alzoubi, Ibrahim A; Lynch, Edward; Al-Omiri, Mahmoud K

2015-01-01

This study aimed to clinically quantify the apicoincisal height of the upper interproximal areas directly in patients' mouths compared to measurements on stone models. One hundred and fifty participants (75 females and 75 males, age range 20-45 years) were recruited for this study. A digital caliper was used to measure the anterior maxillary interproximal contact areas directly in patients' mouths and on stone models. The digital caliper accuracy was up to 0.01. The Statistical Package for Social Sciences software (SPSS, version 19.0, Chicago, Ill., USA) was used for statistical analysis. Statistical significance was based on probability values contacts as well as the measurement on stone models showed that the dimensions of interproximal contacts on both sides of each tooth were significantly different (p contact point was larger than that of the distal contact point of each tooth. The largest contact point was the one between the central incisors (direct intraoral measurement = 2.9-6.49 mm; model measurement = 3.31-6.91 mm). On the other hand, the contact point between the canine and first premolar was the smallest on both sides of the arch (0.63-2.52 mm intraorally, 0.98-2.88 mm on models). The intraoral measurement of contact points was more accurate than model measurements, and the differences were statistically significant (p contact point dimensions using a digital caliper was more precise than measuring contact points on stone models; hence, it is a viable, quick and adequate method to be used routinely. © 2015 S. Karger AG, Basel.

Key composition optimization of meat processed protein source by vacuum freeze-drying technology.

Science.gov (United States)

Ma, Yan; Wu, Xingzhuang; Zhang, Qi; Giovanni, Vigna; Meng, Xianjun

2018-05-01

Vacuum freeze-drying technology is a high technology content, a wide range of knowledge of technology in the field of drying technology is involved, it is also a method of the most complex drying equipment, the largest energy consumption, the highest cost of drying method, but due to the particularity of its dry goods: the freeze-drying food has the advantages of complex water performance is good, cooler and luster of freezing and drying food to maintain good products, less nutrient loss, light weight, easy to carry transportation, easy to long-term preservation, and on the quality is far superior to the obvious advantages of other dried food, making it become the forefront of drying technology research and development. The freeze-drying process of Chinese style ham and western Germany fruit tree tenderloin is studied in this paper, their eutectic point, melting point and collapse temperature, freeze-drying curve and its heat and mass transfer characteristics are got, then the precool temperature and the highest limiting temperature of sublimation interface are determined. The effect of system pressure on freeze-dried rate in freeze-drying process is discussed, and the method of regulating pressure circularly is determined.

Hydrodynamics study on drying of pepper in swirling fluidized bed dryer (SFBD)

Science.gov (United States)

Syaif Haron, Nazrul; Hazri Zakaria, Jamal; Faizal Mohideen Batcha, Mohd

2017-08-01

Malaysia is one of the pepper producer with exports quantity reaching more than 90000 tonnes between 2010 until 2016. Drying of pepper is mandatory before their export and at present, pepper was dried by sun drying to reduce cost. This conventional drying method was time consuming and may take four days during rainy season, which retards the production of pepper. This paper proposes the swirling fluidized bed drying (SFBD) method, which was known to have high mixing ability and improved solid-gas contact to shorten the drying time of products. A lab scale SFBD system was constructed to carry out this study. Hydrodynamic study was conducted for three beds loadings of 1.0 kg, 1.4 kg at a drying temperature of 90°C. The SFBD has shown excellent potential to dry the pepper with a relatively short drying time compared to the conventional method. Batch drying for the bed loads studied only took 3 hours of drying time only. It was found that bed higher bed loading of wet pepper requires longer drying time due to higher amount of moisture content in the bed. Four distinct regimes of operation were found during drying in the SFBD and these regimes offer flexibility of operation. The total bed pressure drop was relatively low during drying.

Micro and macro contact mechanics for interacting asperities

Indian Academy of Sciences (India)

assigned to one surface making the other surface perfectly flat an assumption .... pressure at the middle of contact and 2a being the contact length. p0 and a are related by ... Since this third eye is found to be an isotropic point under hydrostatic.

Dry eye syndrome. Etiological and therapeutic aspects.

Science.gov (United States)

Apostol, Silvia; Filip, M; Dragne, Carmen; Filip, A

2003-01-01

"Dry eye syndrome" is a common disorder of the tear film that results from inadequate tear production, excessive tear evaporation or abnormality in mucin or lipid components of the tear film. A number of 53 patients suffering from dry eye syndrome were followed up for a period of 18 months. The study group was heterogeneous, including a lot of conditions accompanied by dry eye syndrome: Syogren's syndrome, lupus erythematous, ocular rosacea, patients with systemic treatments with antidepressants, betablockers, diuretics, oral contraceptives, glaucomatous patients with topical beta-blockers, postmenopausal women, aging people, computer users and long-term contact lens wearers. The therapeutical options were dictated by the severity of the syndrome: substitution therapy, treatment of the underlying eyelid diseases, modifying of the environmental conditions and treatment of the complications in the most severe cases. The new pathological approach is innovative and it may provide a real therapeutical measure for this condition: topical A Cyclosporine and androgen drops.

Friction behavior of glass and metals in contact with glass in various environments

Science.gov (United States)

Buckley, D. H.

1973-01-01

Sliding friction experiments have been conducted for heat-resistant glass and metals in contact with glass. These experiments were conducted in various environments including vacuum, moist air, dry air, octane, and stearic acid in hexadecane. Glass exhibited a higher friction force in moist air than it did in vacuum when in sliding contact with itself. The metals, aluminum, iron, and gold, all exhibited the same friction coefficient when sliding on glass in vacuum as glass sliding on glass. Gold-to-glass contacts were extremely sensitive to the environment despite the relative chemical inertness of gold.

Rigid Bodies in Contact

DEFF Research Database (Denmark)

Niebe, Sarah Maria

. A contact point determination method, based on boolean surface maps, is developed to handle collisions between tetrahedral meshes. The novel nonsmooth nonlinear conjugate gradient (NNCG) method is presented. The NNCG method is comparable in terms of accuracy to the state-of-the-art method, projected Gauss...

A Hygroscopic Sensor Electrode for Fast Stabilized Non-Contact ECG Signal Acquisition.

Science.gov (United States)

Fong, Ee-May; Chung, Wan-Young

2015-08-05

A capacitive electrocardiography (cECG) technique using a non-invasive ECG measuring technology that does not require direct contact between the sensor and the skin has attracted much interest. The system encounters several challenges when the sensor electrode and subject's skin are weakly coupled. Because there is no direct physical contact between the subject and any grounding point, there is no discharge path for the built-up electrostatic charge. Subsequently, the electrostatic charge build-up can temporarily contaminate the ECG signal from being clearly visible; a stabilization period (3-15 min) is required for the measurement of a clean, stable ECG signal at low humidity levels (below 55% relative humidity). Therefore, to obtain a clear ECG signal without noise and to reduce the ECG signal stabilization time to within 2 min in a dry ambient environment, we have developed a fabric electrode with embedded polymer (FEEP). The designed hygroscopic FEEP has an embedded superabsorbent polymer layer. The principle of FEEP as a conductive electrode is to provide humidity to the capacitive coupling to ensure strong coupling and to allow for the measurement of a stable, clear biomedical signal. The evaluation results show that hygroscopic FEEP is capable of rapidly measuring high-accuracy ECG signals with a higher SNR ratio.

The mechanical properties of dry, electrospun fibrinogen fibers

Energy Technology Data Exchange (ETDEWEB)

Baker, Stephen; Sigley, Justin; Helms, Christine C. [Department of Physics, Wake Forest University, Winston-Salem, NC 27109 (United States); Stitzel, Joel [Department of Biomedical Engineering, Wake Forest University Health Sciences, Winston-Salem, NC, 27157 (United States); Berry, Joel; Bonin, Keith [Department of Physics, Wake Forest University, Winston-Salem, NC 27109 (United States); Guthold, Martin, E-mail: gutholdm@wfu.edu [Department of Physics, Wake Forest University, Winston-Salem, NC 27109 (United States)

2012-02-01

Due to their low immunogenicity, biodegradability and native cell-binding domains, fibrinogen fibers may be good candidates for tissue engineering scaffolds, drug delivery vehicles and other medical devices. We used a combined atomic force microscope (AFM)/optical microscope technique to study the mechanical properties of individual, electrospun fibrinogen fibers in dry, ambient conditions. The AFM was used to stretch individual fibers suspended over 13.5 {mu}m wide grooves in a transparent substrate. The optical microscope, located below the sample, was used to monitor the stretching process. Electrospun fibrinogen fibers (diameter, 30-200 nm) can stretch to 74% beyond their original length before rupturing at a stress of 2.1 GPa. They can stretch elastically up to 15% beyond their original length. Using incremental stress-strain curves the viscoelastic behavior of these fibers was determined. The total stretch modulus was 4.2 GPa while the relaxed elastic modulus was 3.7 GPa. When held at constant strain, fibrinogen fibers display stress relaxation with a fast and slow relaxation time of 1.2 s and 11 s. In comparison to native and electrospun collagen fibers, dry electrospun fibrinogen fibers are significantly more extensible and elastic. In comparison to wet electrospun fibrinogen fibers, dry fibers are about 1000 times stiffer. - Highlights: Black-Right-Pointing-Pointer Fabricated dry, electrospun, fibrinogen fibers; average diameter, D{sub avg.} = 95 nm. Black-Right-Pointing-Pointer Determined mechanical properties with combined atomic force/optical microscope. Black-Right-Pointing-Pointer Fibers are very extensible ({epsilon}{sub max} = 74%) and elastic ({epsilon}{sub elastic} = 15%). Black-Right-Pointing-Pointer Fiber total modulus, E{sub tot.} = 4.2 GPa; elastic modulus, E{sub el.} = 3.7 GPa. Black-Right-Pointing-Pointer Fiber stress relaxation times: {tau}{sub 1} = 1.2 s and {tau}{sub 2} = 11 s.

Quantum Point Contact Single-Nucleotide Conductance for DNA and RNA Sequence Identification.

Science.gov (United States)

Afsari, Sepideh; Korshoj, Lee E; Abel, Gary R; Khan, Sajida; Chatterjee, Anushree; Nagpal, Prashant

2017-11-28

Several nanoscale electronic methods have been proposed for high-throughput single-molecule nucleic acid sequence identification. While many studies display a large ensemble of measurements as "electronic fingerprints" with some promise for distinguishing the DNA and RNA nucleobases (adenine, guanine, cytosine, thymine, and uracil), important metrics such as accuracy and confidence of base calling fall well below the current genomic methods. Issues such as unreliable metal-molecule junction formation, variation of nucleotide conformations, insufficient differences between the molecular orbitals responsible for single-nucleotide conduction, and lack of rigorous base calling algorithms lead to overlapping nanoelectronic measurements and poor nucleotide discrimination, especially at low coverage on single molecules. Here, we demonstrate a technique for reproducible conductance measurements on conformation-constrained single nucleotides and an advanced algorithmic approach for distinguishing the nucleobases. Our quantum point contact single-nucleotide conductance sequencing (QPICS) method uses combed and electrostatically bound single DNA and RNA nucleotides on a self-assembled monolayer of cysteamine molecules. We demonstrate that by varying the applied bias and pH conditions, molecular conductance can be switched ON and OFF, leading to reversible nucleotide perturbation for electronic recognition (NPER). We utilize NPER as a method to achieve >99.7% accuracy for DNA and RNA base calling at low molecular coverage (∼12×) using unbiased single measurements on DNA/RNA nucleotides, which represents a significant advance compared to existing sequencing methods. These results demonstrate the potential for utilizing simple surface modifications and existing biochemical moieties in individual nucleobases for a reliable, direct, single-molecule, nanoelectronic DNA and RNA nucleotide identification method for sequencing.

Conceptual Modeling of the Influence of Wetting and Drying Cycles on Soil Aggregation and Stabilization

Science.gov (United States)

Albalasmeh, A. A.; Ghezzehei, T.

2011-12-01

Soil structure directly determines important soil physical properties including porosity, hydraulic conductivity, water retention, and mechanical strength and indirectly influences most biological and chemical processes that occur in and around soil. The interaction of environmental and biotic agents influences the physical condition of the soil, particularly through soil structural evolution. Wetting and drying cycles are important environmental processes known to enhance aggregation, while clay minerals, sesquioxides and soil organic matter (SOM) are the soil solids most involved in soil structural development. We hypothesize that drying of capillary water transports suspended and/or dissolved cementing agents toward inter-particle contacts and eventually deposits part of the colloidal mass forming inter-particle bonds. Here, we will show the role of wetting and drying cycles on soil aggregation and stabilization and how these cycles transport and deposit organic cementing agents at the inter-particle contact. We will present results of the effect of particle size, number of wetting and drying cycles, viscosity, molecule length and concentration of suspended and/or dissolved cementing agents on soil aggregation and stabilization.

A model of mechanical contacts in hearing aids for uncertainty analysis

DEFF Research Database (Denmark)

Creixell Mediante, Ester; Brunskog, Jonas; Jensen, Jakob Søndergaard

2015-01-01

Modelling the contact between assembled parts is a key point in the design of complex structures. Uncertainties at the joint parameters arise as a result of randomness in physical properties such as contact surface, load distribution or geometric details. This is a challenge of concern in the hea......Modelling the contact between assembled parts is a key point in the design of complex structures. Uncertainties at the joint parameters arise as a result of randomness in physical properties such as contact surface, load distribution or geometric details. This is a challenge of concern...... in the hearing aid field, where the small lightweight structures present vibration modes at frequencies within the hearing range. To approach this issue, a model of contacts based on lumped elements is suggested. The joint parameters are the stiffness of a series of spring elements placed along the contact...

Key composition optimization of meat processed protein source by vacuum freeze-drying technology

Directory of Open Access Journals (Sweden)

Yan Ma

2018-05-01

Full Text Available Vacuum freeze-drying technology is a high technology content, a wide range of knowledge of technology in the field of drying technology is involved, it is also a method of the most complex drying equipment, the largest energy consumption, the highest cost of drying method, but due to the particularity of its dry goods: the freeze-drying food has the advantages of complex water performance is good, cooler and luster of freezing and drying food to maintain good products, less nutrient loss, light weight, easy to carry transportation, easy to long-term preservation, and on the quality is far superior to the obvious advantages of other dried food, making it become the forefront of drying technology research and development. The freeze-drying process of Chinese style ham and western Germany fruit tree tenderloin is studied in this paper, their eutectic point, melting point and collapse temperature, freeze-drying curve and its heat and mass transfer characteristics are got, then the precool temperature and the highest limiting temperature of sublimation interface are determined. The effect of system pressure on freeze-dried rate in freeze-drying process is discussed, and the method of regulating pressure circularly is determined. Keywords: Ham, Tenderloin, Vacuum freeze-dry, Processing, Optimization

Freeze-drying wet digital prints: An option for salvage?

International Nuclear Information System (INIS)

Juergens, M C; Schempp, N

2010-01-01

On the occasion of the collapse of the Historical Archive of the City of Cologne in March 2009 and the ensuing salvage effort, questions were raised about the use of freeze-drying for soaked digital prints, a technique that has not yet been evaluated for these materials. This study examines the effects of immersion, air-drying, drying in a blotter stack, freezing and freeze-drying on 35 samples of major digital printing processes. The samples were examined visually before, during and after testing; evaluation of the results was qualitative. Results show that some prints were already damaged by immersion alone (e.g. bleeding inks and soluble coatings) to the extent that the subsequent choice of drying method made no significant difference any more. For those samples that did survive immersion, air-drying proved to be crucial for water-sensitive prints, since any contact with the wet surface caused serious damage. Less water-sensitive prints showed no damage throughout the entire procedure, regardless of drying method. Some prints on coated media suffered from minor surface disruption up to total delamination of the surface coating due to the formation of ice crystals during shock-freezing. With few exceptions, freeze-drying did not cause additional damage to any of the prints that hadn't already been damaged by freezing. It became clear that an understanding of the process and materials is important for choosing an appropriate drying method.

Method for making low-resistivity contacts to high T/sub c/ superconductors

International Nuclear Information System (INIS)

Ekin, J.W.; Panson, A.J.; Blankenship, B.A.

1988-01-01

A method for making low-resistivity contacts to high T/sub c/ superconductors has been developed, which has achieved contact surface resistivities less than 10 μΩ cm 2 at 76 K and does not require sample heating above ∼150 0 C. This is an upper limit for the contact resistivity obtained at high current densities up to 10 2 --10 3 A/cm 2 across the contact interface. At lower measuring current densities the contact resistivities were lower and the voltage-current curve was nonlinear, having a superconducting transition character. On cooling from 295 to 76 K, the contact resistivity decreased several times, in contrast to indium solder contacts where the resistivity increased on cooling. The contacts showed consistently low resistivity and little degradation when exposed to dry air over a four-month period and when repeatedly cycled between room temperature and 76 K. The contacts are formed by sputter depositing a layer of a noble metal-silver and gold were used-on a clean superconductor surface to protect the surface and serve as a contact pad. External connections to the contact pads have been made using both solder and wire-bonding techniques

Development towards compact nitrocellulose interferometric biochips for dry eye diagnosis based on MMP9, S100A6 and CST4 biomarkers using a Point-of-Care device

Science.gov (United States)

Santamaría, Beatriz; Laguna, María. Fe; López-Romero, David; López-Hernandez, A.; Sanza, F. J.; Lavín, A.; Casquel, R.; Maigler, M.; Holgado, M.

2018-02-01

A novel compact optical biochip based on a thin layer-sensing BICELL surface of nitrocellulose is used for in-situ labelfree detection of dry eye disease (DED). In this work the development of a compact biosensor that allows obtaining quantitative diagnosis with a limited volume of sample is reported. The designed sensors can be analyzed with an optical integrated Point-of-Care read-out system based on the "Increase Relative Optical Power" principle which enhances the performance and Limit of Detection. Several proteins involved with dry eye dysfunction have been validated as biomarkers. Presented biochip analyzes three of those biomarkers: MMP9, S100A6 and CST4. BICELLs based on nitrocellulose permit to immobilize antibodies for each biomarker recognition. The optical response obtained from the biosensor through the readout platform is capable to recognize specifically the desired proteins in the concentrations range for control eye (CE) and dry eye syndrome (DES). Preliminary results obtained will allow the development of a dry eye detection device useful in the area of ophthalmology and applicable to other possible diseases related to the eye dysfunction.

The Troy Microneedle: A Rapidly Separating, Dissolving Microneedle Formed by Cyclic Contact and Drying on the Pillar (CCDP.

Directory of Open Access Journals (Sweden)

Miroo Kim

Full Text Available In dissolving microneedle (DMN-mediated therapy, complete and rapid delivery of DMNs is critical for the desired efficacy. Traditional patch-based DMN delivery, however, may fail due to incomplete delivery from insufficient skin insertion or rapid separation of microneedles due to their strong bond to the backing film. Here, we introduce the Troy microneedle, which was created by cyclic contact and drying on the pillar (CCDP, and which enabled simultaneous complete and rapid delivery of DMN. This CCDP process could be flexibly repeated to achieve a specific desired drug dose in a DMN. We evaluated DMN separation using agarose gel, and the Troy microneedle achieved more complete and rapid separation than other, more deeply dipped DMN, primarily because of the Troy's minimal junction between the DMN and pillar. When Troy microneedles were applied to pig cadaver skin, it took only 15 s for over 90% of encapsulated rhodamine B to be delivered, compared to 2 h with application of a traditional DMN patch. In vivo skin penetration studies demonstrated rapid DMN-separation of Troy microneedles still in solid form before dissolution. The Troy microneedle overcomes critical issues associated with the low penetration efficiency of flat patch-based DMN and provides an innovative route for DMN-mediated therapy, combining patient convenience with the desire drug efficacy.

Graphene as a protective coating and superior lubricant for electrical contacts

Science.gov (United States)

Berman, Diana; Erdemir, Ali; Sumant, Anirudha V.

2014-12-01

Potential for graphene to be used as a lubricant for sliding electrical contacts has been evaluated. Graphene, being deposited as a sporadic flakes on the gold substrate sliding against titanium nitride ball shows not only significant improvement in tribological behavior by reducing both friction (by factor of 2-3) and wear (by 2 orders) but also, even more importantly, demonstrates stable and low electrical resistance at the sliding contacts undergoing thousands of sliding passes regardless of the test environment (i.e., both in humid and dry conditions).

Influence of Stress Shape Function on Analysis of Contact Problem Using Hybrid Photoelasticity

International Nuclear Information System (INIS)

Shin, Dongchul; Hawong, Jaisug

2013-01-01

In this research, a study on stress shape functions was conducted to analyze the contact stress problem by using a hybrid photoelasticity. Because the contact stress problem is generally solved as a half-plane problem, the relationship between two analytical stress functions, which are compositions of the Airy stress function, was similar to one of the crack problem. However, this relationship in itself could not be used to solve the contact stress problem (especially one with singular points). Therefore, to analyze the contact stress problem more correctly, stress shape functions based on the condition of two contact end points had to be considered in the form of these two analytical stress functions. The four types of stress shape functions were related to the stress singularities at the two contact end points. Among them, the primary two types used for the analysis of an O-ring were selected, and their validities were verified in this work

Effect of heterogenous and homogenous air gaps on dry heat loss through the garment

Science.gov (United States)

Mert, Emel; Psikuta, Agnes; Bueno, Marie-Ange; Rossi, René M.

2015-11-01

In real life conditions, the trapped air between the human body and the garment has uneven shape and vary over the body parts as a consequence of the complex geometry of the human body. However, the existing clothing models assume uniform air layer between the human body and the garment or its full contact, which may cause large error in the output of simulations. Therefore, the aim of this study was to investigate the effect of a heterogeneous vertical air gap with different configuration of folds (size and frequency) on dry heat loss using a heated cylinder (Torso). It was found that the presence of folds in the garment led to an increased heat loss from the body in comparison to a homogeneous air gap of comparable size. Interestingly, the size of folds did not have an influence on the dry heat loss. Additionally, the effect of the contact area on dry heat loss became important when exceeding a threshold of about 42 %. The results from this study are useful for modelling of a realistic dry heat loss through the clothing and contribute to the improvement of design of protective and active sport garments.

A HOSPITAL-BASED STUDY ON THE PREVALENCE OF DRY EYES IN A TERTIARY CARE HOSPITAL

Directory of Open Access Journals (Sweden)

Prashant V. Solanke

2017-06-01

Full Text Available BACKGROUND Dry eye syndrome is a common eye disease. Dry Eye Syndrome (DES, also known as Keratoconjunctivitis Sicca (KCS, is the condition of having dry eyes. Other associated symptoms include irritation, redness, discharge and easily fatigued eyes. Blurred vision may also occur. The symptoms can range from mild and occasional to severe and continuous. Scarring of the cornea may occur in some cases without treatment. Dry eye occurs when either the eye does not produce enough tears or when the tears evaporate too quickly. Tobacco smoke exposure or infection may also lead to the condition. Diagnosis is mostly based on the symptoms, though a number of other tests may be used. Prevalence of dry eyes are commoner in females than males. There is a positive relationship between glaucoma and ocular dryness as well as diabetic retinopathy and ocular dryness. Dry eye is a multifactorial disease of the tears and ocular surface. Ocular symptoms such as pain, irritation and poor vision can result from dry eye. The aim of the study is to study the prevalence, symptomatology and distribution of dry eyes. MATERIALS AND METHODS A cross-sectional study was conducted during July 2016 to March 2017. Study place was Outpatient Department of Ophthalmology at Sree Mookambika Institute of Medical Sciences, Kulasekharam. Sample size was calculated by 4PQ/d², which was 132. Systemic random sampling was used for the study. RESULTS Prevalence of dry eyes - 17.8%. Dry eyes in males - 16.8% and in females - 24.6%. Dry eyes in age 40 yrs. - 21.8%. Prevalence of dry eyes in contact lens wearers - 36.5%. Prevalence of dry eyes in glaucoma cases - 38.2%. Prevalence of dry eyes in farmers - 27.3%, in smokers - 36.7%. Dry eyes in emmetropes - 12.8% in myopes - 17.2% in hypermetropes - 28.6%. CONCLUSION Dry eyes prevalence obtained was 17.8%. Dry eyes were seen more in females. As age increases, prevalence of dry eyes increases. Ocular surface dryness was observed more in contact

On the Rotor to Stator Contact Dynamics with Impacts and Friction - Theoretical and Experimental Study

DEFF Research Database (Denmark)

Lahriri, Said

The contact between a rotor and its stator can in some cases be considered as a serious malfunction that may lead to catastrophic failure. This major threat arises normally from full annular dry friction backward whirl and whip motion where the rotor runs and rubs at a high frequency on the inner...... of the friction coefficient behavior.......The contact between a rotor and its stator can in some cases be considered as a serious malfunction that may lead to catastrophic failure. This major threat arises normally from full annular dry friction backward whirl and whip motion where the rotor runs and rubs at a high frequency on the inner...... surface of the stator, and thereby traversing the full extent of the clearance. Normal and friction forces are exerted on the rotor at each impact and rubs. These particular forces can sustain the rotor in a persistent backward dry whirl or whip motion. In that case, the friction force plays a significant...

Enhanced superconductivity at the interface of W/Sr2RuO4 point contact

Science.gov (United States)

Wei, Jian; Wang, He; Lou, Weijian; Luo, Jiawei; Liu, Ying; Ortmann, J. E.; Mao, Z. Q.

Differential resistance measurements are conducted for point contacts (PCs) between the Sr2RuO4 (SRO) single crystal and the tungsten tip. Since the tungsten tip is hard enough to penetrate through the surface layer, consistent superconducting features are observed. Firstly, with the tip pushed towards the crystal, the zero bias conductance peak (ZBCP) due to Andreev reflection at the normal-superconducting interface increases from 3% to more than 20%, much larger than previously reported, and extends to temperature higher than the bulk transition temperature. Reproducible ZBCP within 0.2 mV may also help determine the gap value of SRO, on which no consensus has been reached. Secondly, the logarithmic background can be fitted with the Altshuler-Aronov theory of electron-electron interaction for tunneling into quasi two dimensional electron system. Feasibility of such fitting confirms that spectroscopic information like density of states is probed, and electronic temperature retrieved from such fitting can be important to analyse the PC spectra. Third, at bias much higher than 0.2 mV there are conductance dips due to the critical current effect and these dips persist up to 6.2 K. For more details see. National Basic Research Program of China (973 Program) through Grant No. 2011CBA00106 and No. 2012CB927400.

Energy stability of droplets and dry spots in a thin film model of hanging drops

Science.gov (United States)

Cheung, Ka-Luen; Chou, Kai-Seng

2017-10-01

The 2-D thin film equation describing the evolution of hang drops is studied. All radially symmetric steady states are classified, and their energy stability is determined. It is shown that the droplet with zero contact angle is the only global energy minimizer and the dry spot with zero contact angle is a strict local energy minimizer.

Drying tests conducted on Three Mile Island fuel canisters containing simulated debris

International Nuclear Information System (INIS)

Palmer, A.J.

1995-01-01

Drying tests were conducted on TMI-2 fuel canisters filled with simulated core debris. During these tests, canisters were dried by heating externally by a heating blanket while simultaneously purging the canisters' interior with hot, dry nitrogen. Canister drying was found to be dominated by moisture retention properties of a concrete filler material (LICON) used for geometry control. This material extends the drying process 10 days or more beyond what would be required were it not there. The LICON resides in a nonpurgeable chamber separate from the core debris, and because of this configuration, dew point measurements on the exhaust stream do not provide a good indication of the dew point in the canisters. If the canisters are not dried, but rather just dewatered, 140-240 lb of water (not including the LICON water of hydration) will remain in each canister, approximately 50-110 lb of which is pore water in the LICON and the remainder unbound water

21 CFR 872.3830 - Endodontic paper point.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Endodontic paper point. 872.3830 Section 872.3830...) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3830 Endodontic paper point. (a) Identification. An endodontic paper point is a device made of paper intended for use during endodontic therapy to dry...

Method of drying long-distance pipelines in sections

Energy Technology Data Exchange (ETDEWEB)

Steinhaus, H.; Meiners, D.

1989-04-11

This invention provides a method of drying long distance pipelines using a vacuum, and provides high-quality drying over the whole length of the pipeline in a manageable and easily followed process. Evacuation of the pipeline is effected by means of a vacuum pump located at least at one point of the section of pipeline. The section is subsequently scavenged or flooded with scavenging gas. After a predetermined reduced pressure is reached, and while the vacuum pump continues to draw off, a scavenging is effected from the end or ends remote from the evacuation point with a molar flow rate of the stream of scavenging gas that is equal to or less than the evacuation stream in throughput, at least initially. The scavenging is effected not from the evacuation point, but from a remote point, and is also effected with a feed speed or feed amount that is throttled at least initially. This ensures that no condensation occurs even in the inner walls of the pipeline.

The Contact Dynamics method: A nonsmooth story

Science.gov (United States)

Dubois, Frédéric; Acary, Vincent; Jean, Michel

2018-03-01

When velocity jumps are occurring, the dynamics is said to be nonsmooth. For instance, in collections of contacting rigid bodies, jumps are caused by shocks and dry friction. Without compliance at the interface, contact laws are not only non-differentiable in the usual sense but also multi-valued. Modeling contacting bodies is of interest in order to understand the behavior of numerous mechanical systems such as flexible multi-body systems, granular materials or masonry. These granular materials behave puzzlingly either like a solid or a fluid and a description in the frame of classical continuous mechanics would be welcome though far to be satisfactory nowadays. Jean-Jacques Moreau greatly contributed to convex analysis, functions of bounded variations, differential measure theory, sweeping process theory, definitive mathematical tools to deal with nonsmooth dynamics. He converted all these underlying theoretical ideas into an original nonsmooth implicit numerical method called Contact Dynamics (CD); a robust and efficient method to simulate large collections of bodies with frictional contacts and impacts. The CD method offers a very interesting complementary alternative to the family of smoothed explicit numerical methods, often called Distinct Elements Method (DEM). In this paper developments and improvements of the CD method are presented together with a critical comparative review of advantages and drawbacks of both approaches. xml:lang="fr"

Contact mechanics: contact area and interfacial separation from small contact to full contact

International Nuclear Information System (INIS)

Yang, C; Persson, B N J

2008-01-01

We present a molecular dynamics study of the contact between a rigid solid with a randomly rough surface and an elastic block with a flat surface. The numerical calculations mainly focus on the contact area and the interfacial separation from small contact (low load) to full contact (high load). For a small load the contact area varies linearly with the load and the interfacial separation depends logarithmically on the load. For a high load the contact area approaches the nominal contact area (i.e. complete contact), and the interfacial separation approaches zero. The numerical results have been compared with analytical theory and experimental results. They are in good agreement with each other. The present findings may be very important for soft solids, e.g. rubber, or for very smooth surfaces, where complete contact can be reached at moderately high loads without plastic deformation of the solids

Comparison of drying characteristic and uniformity of banana cubes dried by pulse-spouted microwave vacuum drying, freeze drying and microwave freeze drying.

Science.gov (United States)

Jiang, Hao; Zhang, Min; Mujumdar, Arun S; Lim, Rui-Xin

2014-07-01

To overcome the flaws of high energy consumption of freeze drying (FD) and the non-uniform drying of microwave freeze drying (MFD), pulse-spouted microwave vacuum drying (PSMVD) was developed. The results showed that the drying time can be dramatically shortened if microwave was used as the heating source. In this experiment, both MFD and PSMVD could shorten drying time by 50% as compared to the FD process. Depending on the heating method, MFD and PSMVD dried banana cubes showed trends of expansion while FD dried samples demonstrated trends of shrinkage. Shrinkage also brought intensive structure and highest fracturability of all three samples dried by different methods. The residual ascorbic acid content of PSMVD dried samples can be as high as in FD dried samples, which were superior to MFD dried samples. The tests confirmed that PSMVD could bring about better drying uniformity than MFD. Besides, compared with traditional MFD, PSMVD can provide better extrinsic feature, and can bring about improved nutritional features because of the higher residual ascorbic acid content. © 2013 Society of Chemical Industry.

Analysis of maizena drying system using temperature control based fuzzy logic method

Science.gov (United States)

Arief, Ulfah Mediaty; Nugroho, Fajar; Purbawanto, Sugeng; Setyaningsih, Dyah Nurani; Suryono

2018-03-01

Corn is one of the rice subtitution food that has good potential. Corn can be processed to be a maizena, and it can be used to make type of food that has been made from maizena, viz. Brownies cake, egg roll, and other cookies. Generally, maizena obtained by drying process carried out 2-3 days under the sun. However, drying process not possible during the rainy season. This drying process can be done using an automatic drying tool. This study was to analyze the design result and manufacture of maizena drying system with temperature control based fuzzylogic method. The result show that temperature of drying system with set point 40°C - 60°C work in suitable condition. The level of water content in 15% (BSN) and temperatureat 50°C included in good drying process. Time required to reach the set point of temperature in 50°C is 7.05 minutes. Drying time for 500 gr samples with temperature 50°C and power capacity 127.6 watt was 1 hour. Based on the result, drying process using temperature control based fuzzy logic method can improve energy efficiency than the conventional method of drying using a direct sunlight source with a temperature that cannot be directly controlled by human being causing the quality of drying result of flour is erratic.

Mechanical performance and thermal stability of glass fiber reinforced silica aerogel composites based on co-precursor method by freeze drying

Science.gov (United States)

Zhou, Ting; Cheng, Xudong; Pan, Yuelei; Li, Congcong; Gong, Lunlun; Zhang, Heping

2018-04-01

In order to maintain the integrity, glass fiber (GF) reinforced silica aerogel composites were synthesized using methltrimethoxysilane (MTMS) and water glass co-precursor by freeze drying method. The composites were characterized by scanning electron microscopy, Brunauer-Emmett-Teller analysis, uniaxial compressive test, three-point bending test, thermal conductivity analysis, contact angle test, TG-DSC analysis. It was found that the molar ratio of MTMS/water glass could significantly affect the properties of composites. The bulk density and thermal conductivity first decreased and then increased with the increasing molar ratio. The composites showed remarkable mechanical strength and flexibility compared with pure silica aerogel. Moreover, when the molar ratio is 1.8, the composites showed high specific surface area (870.9 m2/g), high contact angle (150°), great thermal stability (560 °C) and low thermal conductivity (0.0248 W/m·K). These outstanding properties indicate that GF/aerogels have broad prospects in the field of thermal insulation.

Sound propagation in dry granular materials : discrete element simulations, theory, and experiments

NARCIS (Netherlands)

Mouraille, O.J.P.

2009-01-01

In this study sound wave propagation through different types of dry confined granular systems is studied. With three-dimensional discrete element simulations, theory and experiments, the influence of several micro-scale properties: friction, dissipation, particle rotation, and contact disorder, on

Solar drying of rose (Rosa sp.) petals

Energy Technology Data Exchange (ETDEWEB)

Balladin, D.A.; Headley, Oliver [University of the West Indies, Center for Resource Management and Environmental Studies, St. Michael (Barbados)

1999-10-01

The rose (Rosa sp.) petals can be dried after 2 days at about 30degC reaching an equilibrium moisture content after 16 h using the solar wire basket dryer. The initial moisture content (wet wt basis) and final moisture content (dry wt basis), determined by the Dean-Stark toluene were 65.7 and 25.2% respectively. The intensity of the rose red coloured pigment (pelargonidin) decreased by a factor of 2.5 after drying. The pelargonidin ethanoic extract as an acid-base indicator, has a K{sub 4} value of 1 x 10{sup -4} mol 1{sup -1} and pH of end point 4 and imbibed on filter paper and allowed to air dry for 5 min showed excellent properties as acid-based test tapes. (Author)

Pressure regulation in the dry-boxes. Argon purification

International Nuclear Information System (INIS)

Pascard, R.; Fabre, R.

1958-01-01

Each dry-box is equipped with an autonomous installation for circulation and purification of argon and for pressure regulation. This installation consists essentially of a ballast tank, a compressor and two valves electromagnetically controlled by a contact manometer. The compressor and the valves are enclosed in the tank to form a system as compact as possible. The argon is purified by passing it over a furnace filled with titanium-zirconium turnings brought to about 800 deg. C, branching off the main system. With this set-up as well as the automatic maintenance of a constant depression in the box, a quality of argon is obtained whose oxygen contact is undetectable by the manganous hydroxide method. (author) [fr

Characterization of spray dried bioadhesive metformin microparticles for oromucosal administration

DEFF Research Database (Denmark)

Sander, Camilla; Madsen, Katrine Dragsbæk; Hyrup, Birgitte

2013-01-01

delivery systems are considered a promising approach as they facilitate a close contact between the drug and the oral mucosa. In this study, bioadhesive chitosan-based microparticles of metformin hydrochloride were prepared by spray drying aqueous dispersions with different chitosan:metformin ratios...... be prepared and analyzed using the ex vivo retention model. We observed an increase in metformin retention on porcine mucosa with increasing chitosan:metformin ratios, while no effect of increasing the chitosan molecular weight was found. Rheological characterization of feeds for spray drying was performed...... and chitosan grades with increasing molecular weights. A recently developed ex vivo flow retention model with porcine buccal mucosa was used to evaluate the bioadhesive properties of spray dried microparticles. An important outcome of this study was that microparticles with the desired metformin content could...

Acupuncture for dry eye: a randomised controlled trial protocol

Directory of Open Access Journals (Sweden)

Kim Ae-Ran

2009-12-01

Full Text Available Abstract Background Dry eye is usually managed by conventional medical interventions such as artificial tears, anti-inflammatory drugs and surgical treatment. However, since dry eye is one of the most frequent ophthalmologic disorders, safer and more effective methods for its treatment are necessary, especially for vulnerable patients. Acupuncture has been widely used to treat patients with dry eye. Our aim is to evaluate the effectiveness and safety of acupuncture for this condition. Methods/Design A randomised, patient-assessor blinded, sham (non-acupuncture point, shallow acupuncture controlled study was established. Participants allocated to verum acupuncture and sham acupuncture groups will be treated three times weekly for three weeks for a total of nine sessions per participant. Seventeen points (GV23; bilateral BL2, GB4, TE23, Ex1 (Taiyang, ST1 and GB20; and left SP3, LU9, LU10 and HT8 for men, right for women have been selected for the verum acupuncture; for the sham acupuncture, points have been selected that do not coincide with a classical acupuncture point and that are located close to the verum points, except in the case of the rim of the eye. Ocular surface disease index, tear film breakup time, the Schirmer I test, medication quantification scale and general assessment of improvement will be used as outcome variables for evaluating the effectiveness of acupuncture. Safety will also be assessed at every visit. Primary and secondary outcomes will be assessed four weeks after screening. All statistical analyses will be performed using analysis of covariance. Discussion The results of this trial will be used as a basis for clarifying the efficacy of acupuncture for dry eye. Trial registration ClinicalTrials.gov NCT00969280.

Pickering dry storage - commissioning and initial operation

International Nuclear Information System (INIS)

Jonjev, S.

1996-01-01

Having commissioned all individual conventional and nuclear systems, the first Dry Storage Container (DSC) was loaded with four modules of 17 year cooled irradiated fuel (366 bundles) in the Auxiliary Irradiated Fuel Bay (AIFB) on November 29, 1995. After decontamination of the outer surface, and draining of water, the DSC was transported to the Used Fuel Dry Storage Facility (UFDSF) workshop, where it was vacuum dried, and then the lid was welded on. Following successful radiography test of the lid weld, the DSC was vacuum dried again and backfilled with Helium to a pressure of 930 mbar(a). The Helium leak test showed zero leakage (allowable leak rate is 1x10 -5 cc/sec). Finally, after loose contamination checks were performed and permanent safeguards seals were applied, the DSC was placed in the UFDSF storage area on January 23, 1996. Radiation fields at contact with the DSC surface were < 0.6 mrem/hr, and at the exterior surface of the storage building wall only 33 micro-rem/hr (far below the target of 250 micro-rem/hr). Therefore, the actual dose rates to general public (at the exclusion zone boundary) will be well below the design target of 1 % of the regulatory limit. (author). 3 refs., 2 tabs., 5 figs

Pickering dry storage - commissioning and initial operation

Energy Technology Data Exchange (ETDEWEB)

Jonjev, S [Ontario Hydro, Pickering, ON (Canada). Pickering Generating Station

1997-12-31

Having commissioned all individual conventional and nuclear systems, the first Dry Storage Container (DSC) was loaded with four modules of 17 year cooled irradiated fuel (366 bundles) in the Auxiliary Irradiated Fuel Bay (AIFB) on November 29, 1995. After decontamination of the outer surface, and draining of water, the DSC was transported to the Used Fuel Dry Storage Facility (UFDSF) workshop, where it was vacuum dried, and then the lid was welded on. Following successful radiography test of the lid weld, the DSC was vacuum dried again and backfilled with Helium to a pressure of 930 mbar(a). The Helium leak test showed zero leakage (allowable leak rate is 1x10{sup -5} cc/sec). Finally, after loose contamination checks were performed and permanent safeguards seals were applied, the DSC was placed in the UFDSF storage area on January 23, 1996. Radiation fields at contact with the DSC surface were < 0.6 mrem/hr, and at the exterior surface of the storage building wall only 33 micro-rem/hr (far below the target of 250 micro-rem/hr). Therefore, the actual dose rates to general public (at the exclusion zone boundary) will be well below the design target of 1 % of the regulatory limit. (author). 3 refs., 2 tabs., 5 figs.

Effectiveness of trigger point dry needling for plantar heel pain: a meta-analysis of seven randomized controlled trials

Directory of Open Access Journals (Sweden)

He C

2017-08-01

Full Text Available Chunhui He,1,* Hua Ma2,* 1Internal Medicine of Traditional Chinese Medicine, 2Medical Image Center, The First Affiliated Hospital of Xinjiang Medical University, Wulumuqi, People’s Republic of China *These authors contributed equally to this work Background: Plantar heel pain can be managed with dry needling of myofascial trigger points (MTrPs; however, whether MTrP needling is effective remains controversial. Thus, we conducted this meta-analysis to evaluate the effect of MTrP needling in patients with plantar heel pain. Materials and methods: PubMed, Embase, Web of Science, SinoMed (Chinese BioMedical Literature Service System, People’s Republic of China, and CNKI (National Knowledge Infrastructure, People’s Republic of China databases were systematically reviewed for randomized controlled trials (RCTs that assessed the effects of MTrP needling. Pooled weighted mean difference (WMD with 95% CIs were calculated for change in visual analog scale (VAS score, and pooled risk ratio (RR with 95% CIs were calculated for success rate for pain and incidence of adverse events. A fixed-effects model or random-effects model was used to pool the estimates, depending on the heterogeneity among the included studies. Results: Extensive literature search yielded 1,941 articles, of which only seven RCTs met the inclusion criteria and were included in this meta-analysis. The pooled results showed that MTrP needling significantly reduced the VAS score (WMD =–15.50, 95% CI: –19.48, –11.53; P<0.001 compared with control, but it had a similar success rate for pain with control (risk ratio [RR] =1.15, 95% CI: 0.87, 1.51; P=0.320. Moreover, MTrP needling was associated with a similar incidence of adverse events with control (RR =1.89, 95% CI: 0.38, 9.39; P=0.438. Conclusion: MTrP needling effectively reduced the heel pain due to plantar fasciitis. However, considering the potential limitations in this study, more large-scale, adequately powered, good

Electronic transport at semiconductor surfaces - from point-contact transistor to micro-four-point probes

DEFF Research Database (Denmark)

Hasegawa, S.; Grey, Francois

2002-01-01

show that this type of conduction is measurable using new types of experimental probes, such as the multi-tip scanning tunnelling microscope and the micro-four-point probe. The resulting electronic transport properties are intriguing, and suggest that semiconductor surfaces should be considered...

Multipoint contact modeling of nanoparticle manipulation on rough surface

Energy Technology Data Exchange (ETDEWEB)

Zakeri, M., E-mail: m.zakeri@tabrizu.ac.ir; Faraji, J.; Kharazmi, M. [University of Tabriz, School of Engineering Emerging Technologies (Iran, Islamic Republic of)

2016-12-15

In this paper, the atomic force microscopy (AFM)-based 2-D pushing of nano/microparticles investigated on rough substrate by assuming a multipoint contact model. First, a new contact model was extracted and presented based on the geometrical profiles of Rumpf, Rabinovich and George models and the contact mechanics theories of JKR and Schwartz, to model the adhesion forces and the deformations in the multipoint contact of rough surfaces. The geometry of a rough surface was defined by two main parameters of asperity height (size of roughness) and asperity wavelength (compactness of asperities distribution). Then, the dynamic behaviors of nano/microparticles with radiuses in range of 50–500 nm studied during their pushing on rough substrate with a hexagonal or square arrangement of asperities. Dynamic behavior of particles were simulated and compared by assuming multipoint and single-point contact schemes. The simulation results show that the assumption of multipoint contact has a considerable influence on determining the critical manipulation force. Additionally, the assumption of smooth surfaces or single-point contact leads to large error in the obtained results. According to the results of previous research, it anticipated that a particles with the radius less than about 550 nm start to slide on smooth substrate; but by using multipoint contact model, the predicted behavior changed, and particles with radii of smaller than 400 nm begin to slide on rough substrate for different height of asperities, at first.

Impedance response of carbon nanotube-titania electrodes dried under modified gravity

International Nuclear Information System (INIS)

Ordenana-Martinez, A.S.; Rincon, M.E.; Vargas, M.; Ramos, E.

2011-01-01

The synthesis and impregnation of porous titania films by commercial multiwalled carbon nanotubes and nanotube rich carbon soot are reported. The samples were dried under terrestrial gravity g and in a centrifuge accelerated at 13 g. X-Ray Diffraction data and Scanning Electron Microscopy images indicated differences in the crystal structure and tendency to agglomeration in both carbon types, providing different microstructures of functionally graded electrodes. Drying the samples in a centrifuge helps to the distribution of carbon nanoparticles and to the decrement of the impedance at the contact interfaces. The presence of titania weakens the differences observed in both drying protocols, but not the differences due to the carbon source. Superior capacitance and network conductivity were observed in electrodes based on commercial carbon nanotubes.

Bilateral contact problem with adhesion and damage

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Adel Aissaoui

2014-05-01

Full Text Available We study a mathematical problem describing the frictionless adhesive contact between a viscoelastic material with damage and a foundation. The adhesion process is modeled by a bonding field on the contact surface. The contact is bilateral and the tangential shear due to the bonding field is included. We establish a variational formulation for the problem and prove the existence and uniqueness of the solution. The existence of a unique weak solution for the problem is established using arguments of nonlinear evolution equations with monotone operators, a classical existence and uniqueness result for parabolic inequalities, and Banach's fixed point theorem.

Research of selection seeds drying in dense layer

Directory of Open Access Journals (Sweden)

S. A. Pavlov

2018-01-01

Full Text Available At the choice of the mode of safe drying of grain mass it is necessary to consider its heterogeneity on moisture content. It is an undesirable factor of which it is necessary to get rid. When increase in moisture inconstant the stability of grain mass at storage decreases, there is a danger of emergence of heating, the overall performance of dryers and other processing equipment decreases, energy costs for seeds production rise. To eliminate this shortcoming located in a grain layer or grain stream the dried-up product should be mixed carefully for the best uniformity. However not uniformity on individual moisture content of separate grains will remain. For its decrease combination of lying with material concitation is used. Researches were conducted in batch-operated laboratory machine. The humidified seeds of sugar beet were blowed-through with the drying agent speed of 0.5 m/s and temperature of 45 degrees Celsius. Moisture removal between concitations did not exceed 2.5 percent for selection seeds and 3.0 percent for ordinary ones. Duration of the periods between concitations can be determined in the analytical way. Thickness of a layer of seeds allowing drying without concitation decreases on square dependence on increase in moisture content. A contact moisture exchange between the damp and dried caryopsides for 30 min and more make it possibledrop-off in the unevenness of drying up to 0.5 percent.

Characteristics of Timbers Dried Using Kiln Drying and Radio Frequency-Vacuum Drying Systems

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Rabidin Zairul Amin

2017-01-01

Full Text Available Heavy hardwoods are difficult-to-dry timbers as they are prone to checking and internal stresses when dried using a conventional kiln drying system. These timbers are usually dried naturally to reach 15% to 19% moisture content with an acceptable defects. Besides long drying time, timbers at these moisture contents are not suitable for indoor applications since they will further dry and causing, for example, jointing and lamination failures. Drying to a lower moisture content could only be achieved in artificial drying kilns such as conventional kiln, dehumidification kiln, solar kiln, radio frequency-vacuum, etc. The objective of this study was to evaluate the characteristics of 30 mm and 50 mm thick kekatong (Cynometra spp. timber dried using kiln drying (KD and radio frequency-vacuum drying (RFV system. The investigation involved drying time, moisture content (MC variations between and within boards, drying defects, shrinkage, and drying stress. Drying defects include checks (surface, end, and internal checks and warping (bowing, cuping, spring, and twisting. The results showed that RFV drying time was reduced to 50% compared to the KD. RFV dried boards demonstrated a more uniform MC between and within boards. Shrinkage in width and thickness, as well as tangential/radial and volumetric shrinkages were substantially less in RFV boards. The amount of cupping, bowing and spring were very low and negligible in all drying runs. There was no twisting observed in all drying methods. The number of stress-free RFV board was higher than KD. With proper procedure, the RFV technology could be used for drying heavy hardwoods which are difficult to dry in conventional kilns due to excessive drying times and degradation.

A Procedure for 3-D Contact Stress Analysis of Spiral Bevel Gears

Science.gov (United States)

Kumar, A.; Bibel, G.

1994-01-01

Contact stress distribution of spiral bevel gears using nonlinear finite element static analysis is presented. Procedures have been developed to solve the nonlinear equations that identify the gear and pinion surface coordinates based on the kinematics of the cutting process and orientate the pinion and the gear in space to mesh with each other. Contact is simulated by connecting GAP elements along the intersection of a line from each pinion point (parallel to the normal at the contact point) with the gear surface. A three dimensional model with four gear teeth and three pinion teeth is used to determine the contact stresses at two different contact positions in a spiral bevel gearset. A summary of the elliptical contact stress distribution is given. This information will be helpful to helicopter and aircraft transmission designers who need to minimize weight of the transmission and maximize reliability.

Spin splitting generated in a Y-shaped semiconductor nanostructure with a quantum point contact

International Nuclear Information System (INIS)

Wójcik, P.; Adamowski, J.; Wołoszyn, M.; Spisak, B. J.

2015-01-01

We have studied the spin splitting of the current in the Y-shaped semiconductor nanostructure with a quantum point contact (QPC) in a perpendicular magnetic field. Our calculations show that the appropriate tuning of the QPC potential and the external magnetic field leads to an almost perfect separation of the spin-polarized currents: electrons with opposite spins flow out through different output branches. The spin splitting results from the joint effect of the QPC, the spin Zeeman splitting, and the electron transport through the edge states formed in the nanowire at the sufficiently high magnetic field. The Y-shaped nanostructure can be used to split the unpolarized current into two spin currents with opposite spins as well as to detect the flow of the spin current. We have found that the separation of the spin currents is only slightly affected by the Rashba spin-orbit coupling. The spin-splitter device is an analogue of the optical device—the birefractive crystal that splits the unpolarized light into two beams with perpendicular polarizations. In the magnetic-field range, in which the current is carried through the edges states, the spin splitting is robust against the spin-independent scattering. This feature opens up a possibility of the application of the Y-shaped nanostructure as a non-ballistic spin-splitter device in spintronics

Spin splitting generated in a Y-shaped semiconductor nanostructure with a quantum point contact

Science.gov (United States)

Wójcik, P.; Adamowski, J.; Wołoszyn, M.; Spisak, B. J.

2015-07-01

We have studied the spin splitting of the current in the Y-shaped semiconductor nanostructure with a quantum point contact (QPC) in a perpendicular magnetic field. Our calculations show that the appropriate tuning of the QPC potential and the external magnetic field leads to an almost perfect separation of the spin-polarized currents: electrons with opposite spins flow out through different output branches. The spin splitting results from the joint effect of the QPC, the spin Zeeman splitting, and the electron transport through the edge states formed in the nanowire at the sufficiently high magnetic field. The Y-shaped nanostructure can be used to split the unpolarized current into two spin currents with opposite spins as well as to detect the flow of the spin current. We have found that the separation of the spin currents is only slightly affected by the Rashba spin-orbit coupling. The spin-splitter device is an analogue of the optical device—the birefractive crystal that splits the unpolarized light into two beams with perpendicular polarizations. In the magnetic-field range, in which the current is carried through the edges states, the spin splitting is robust against the spin-independent scattering. This feature opens up a possibility of the application of the Y-shaped nanostructure as a non-ballistic spin-splitter device in spintronics.

40 CFR 405.120 - Applicability; description of the dry whey subcategory.

Science.gov (United States)

2010-07-01

... whey subcategory. 405.120 Section 405.120 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS DAIRY PRODUCTS PROCESSING POINT SOURCE CATEGORY Dry Whey Subcategory § 405.120 Applicability; description of the dry whey subcategory. The provisions of this subpart...

The Josephson effect in atomic contacts; Effect Josephson dans les contacts atomiques

Energy Technology Data Exchange (ETDEWEB)

Chauvin, M

2005-11-15

The Josephson effect appears when a weak-link establishes phase coherence between two superconductors. A unifying theory of this effect emerged in the 90's within the framework of mesoscopic physics. Based on two cornerstone concepts, conduction channels and Andreev reflection, it predicts the current-phase relation for the most basic weak-link: a single conduction channel of arbitrary transmission. This thesis illustrates this mesoscopic point of view with experiments on superconducting atomic size contacts. In particular, we have focused on the supercurrent peak around zero voltage, put into evidence the ac Josephson currents in a contact under constant bias voltage (Shapiro resonances and photon assisted multiple Andreev reflections), and performed direct measurements of the current-phase relation. (author)

Direct Contact Membrane Distillation of Dairy Process Streams

Directory of Open Access Journals (Sweden)

Mike Weeks

2011-01-01

Full Text Available Membrane distillation (MD was applied for the concentration of a range of dairy streams, such as whole milk, skim milk and whey. MD of a pure lactose solution was also investigated. Direct contact MD (DCMD mode experiments were carried out in continuous concentration mode, keeping the warm feed/retentate and cold permeate stream temperatures at 54 °C and 5 °C respectively. Performance in terms of flux and retention was assessed. The flux was found to decrease with an increase of dry-matter concentration in the feed. Retention of dissolved solids was found to be close to 100% and independent of the dry-matter concentration in the feed. Fourier Transform Infrared Spectroscopy (FTIR of the fouled membranes confirms organics being present in the fouling layer.

Contact parameter identification for vibrational response variability prediction

DEFF Research Database (Denmark)

Creixell Mediante, Ester; Brunskog, Jonas; Jensen, Jakob Søndergaard

2018-01-01

industry, where the vibrational behavior of the structures within the hearing frequency range is critical for the performance of the devices. A procedure to localize the most probable contact areas and determine the most sensitive contact points with respect to variations in the modes of vibration......Variability in the dynamic response of assembled structures can arise due to variations in the contact conditions between the parts that conform them. Contact conditions are difficult to model accurately due to randomness in physical properties such as contact surface, load distribution...... or geometric details. Those properties can vary for a given structure due to the assembly and disassembly process, and also across nominally equal items that are produced in series. This work focuses on modeling the contact between small light-weight plastic pieces such as those used in the hearing aid...

Fabrication of biomimetic dry-adhesion structures through nanosphere lithography

Science.gov (United States)

Kuo, P. C.; Chang, N. W.; Suen, Y.; Yang, S. Y.

2018-03-01

Components with surface nanostructures suitable for biomimetic dry adhesion have a great potential in applications such as gecko tape, climbing robots, and skin patches. In this study, a nanosphere lithography technique with self-assembly nanospheres was developed to achieve effective and efficient fabrication of dry-adhesion structures. Self-assembled monolayer nanospheres with high regularity were obtained through tilted dip-coating. Reactive-ion etching of the self-assembled nanospheres was used to fabricate nanostructures of different shapes and aspect ratios by varying the etching time. Thereafter, nickel molds with inverse nanostructures were replicated using the electroforming process. Polydimethylsiloxane (PDMS) nanostructures were fabricated through a gas-assisted hot-embossing method. The pulling test was performed to measure the shear adhesion on the glass substrate of a sample, and the static contact angle was measured to verify the hydrophobic property of the structure. The enhancement of the structure indicates that the adhesion force increased from 1.2 to 4.05 N/cm2 and the contact angle increased from 118.6° to 135.2°. This columnar structure can effectively enhance the adhesion ability of PDMS, demonstrating the potential of using nanosphere lithography for the fabrication of adhesive structures.

TECHNIQUE OF TESTING ON FRETTING AT THE SPHERE-TO-PLANE CONTACT

Directory of Open Access Journals (Sweden)

А. Khimko

2012-12-01

Full Text Available  The methodology of conducting tests on fretting at the sphere-to-plane contact was developed for the wing mechanization unit, namely for screw-nut pair with intermediate balls. Wearability tests were conducted on a modified installation МФК-1, the feature of which is the designed holder that allows testing with real balls. It was found that at the dry contact of ШХ-15 and 30Х2НВФA materials, surface microcracks are formed due to welding of microasperities areas and their rupture under the influence of vibration.

Porcelain tiles by the dry route

International Nuclear Information System (INIS)

Melchiades, F. G.; Daros, M. T.; Boschi, A. O.

2010-01-01

In Brazil, the second largest tile producer of the world, at present, 70% of the tiles are produced by the dry route. One of the main reasons that lead to this development is the fact that the dry route uses approximately 30% less thermal energy them the traditional wet route. The increasing world concern with the environment and the recognition of the central role played by the water also has pointed towards privileging dry processes. In this context the objective of the present work is to study the feasibility of producing high quality porcelain tiles by the dry route. A brief comparison of the dry and wet route, in standard conditions industrially used today to produce tiles that are not porcelain tiles, shows that there are two major differences: the particle sizes obtained by the wet route are usually considerably finer and the capability of mixing the different minerals, the intimacy of the mixture, is also usually better in the wet route. The present work studied the relative importance of these differences and looked for raw materials and operational conditions that would result in better performance and glazed porcelain tiles of good quality. (Author) 7 refs.

40 CFR 417.150 - Applicability; description of the manufacture of spray dried detergents subcategory.

Science.gov (United States)

2010-07-01

... detergents, including but not limited to assembly and storage of raw materials, crutching, spray drying... manufacture of spray dried detergents subcategory. 417.150 Section 417.150 Protection of Environment... POINT SOURCE CATEGORY Manufacture of Spray Dried Detergents Subcategory § 417.150 Applicability...

On contact modelling in isogeometric analysis

Science.gov (United States)

Cardoso, R. P. R.; Adetoro, O. B.

2017-11-01

IsoGeometric Analysis (IGA) has proved to be a reliable numerical tool for the simulation of structural behaviour and fluid mechanics. The main reasons for this popularity are essentially due to: (i) the possibility of using higher order polynomials for the basis functions; (ii) the high convergence rates possible to achieve; (iii) the possibility to operate directly on CAD geometry without the need to resort to a mesh of elements. The major drawback of IGA is the non-interpolatory characteristic of the basis functions, which adds a difficulty in handling essential boundary conditions and makes it particularly challenging for contact analysis. In this work, the IGA is expanded to include frictionless contact procedures for sheet metal forming analyses. Non-Uniform Rational B-Splines (NURBS) are going to be used for the modelling of rigid tools as well as for the modelling of the deformable blank sheet. The contact methods developed are based on a two-step contact search scheme, where during the first step a global search algorithm is used for the allocation of contact knots into potential contact faces and a second (local) contact search scheme where point inversion techniques are used for the calculation of the contact penetration gap. For completeness, elastoplastic procedures are also included for a proper description of the entire IGA of sheet metal forming processes.

Fourier transform infrared spectra of drying oils treated by irradiation.

Science.gov (United States)

Wang, Yi; Wang, Qin; Artz, William E; Padua, Graciela W

2008-05-14

Drying oils, such as linseed oil and tung oil, have the potential as coating materials to improve barrier properties of biobased packaging films. Oil drying is a chemical reaction in which polyunsaturated fatty acids undergo autoxidation. During drying, oils polymerize and form water-resistant films. However, drying rates tend to be too slow for practical applications. Metal driers are used in the paint industry to accelerate drying, but often driers are not safe for food contact. The objective of this work was to investigate the effect of ionizing radiation on the oxidation or drying rate of drying oils. The effect of irradiation dose on the drying rate of linseed and tung oils was monitored by FTIR spectroscopy. The peak at 3010 cm (-1) was found to be a useful index of oxidation rate. The decrease in peak intensity with time was fitted with exponential functions of the form Abs = Abs 0 exp (- t/ k), where Abs 0 is the initial absorbance and 1/ k is the rate constant for the oxidation process. Values for k were 9.91 ( R (2) = 0.98), 6.59 ( R (2) = 0.95)n and 6.44 ( R (2) = 0.97) for radiation levels of 0, 50, and 100 kGy, respectively. The k values suggested that the oxidation rate increased as the radiation dose increased from 0 to 50 kGy. A further increase to 100 kGy had only a limited effect.

Computation of wheel-rail contact force for non-mapping wheel-rail profile of Translohr tram

Science.gov (United States)

Ji, Yuanjin; Ren, Lihui; Zhou, Jinsong

2017-09-01

Translohr tram has steel wheels, in V-like arrangements, as guide wheels. These operate over the guide rails in inverted-V arrangements. However, the horizontal and vertical coordinates of the guide wheels and guide rails are not always mapped one-to-one. In this study, a simplified elastic method is proposed in order to calculate the contact points between the wheels and the rails. By transforming the coordinates, the non-mapping geometric relationship between wheel and rail is converted into a mapping relationship. Considering the Translohr tram's multi-point contact between the guide wheel and the guide rail, the elastic-contact hypothesis take into account the existence of contact patches between the bodies, and the location of the contact points is calculated using a simplified elastic method. In order to speed up the calculation, a multi-dimensional contact table is generated, enabling the use of simulation for Translohr tram running on curvatures with different radii.

Electrostatic and Quantum Transport Simulations of Quantum Point Contacts in the Integer Quantum Hall Regime

Science.gov (United States)

Sahasrabudhe, Harshad; Fallahi, Saeed; Nakamura, James; Povolotskyi, Michael; Novakovic, Bozidar; Rahman, Rajib; Manfra, Michael; Klimeck, Gerhard

Quantum Point Contacts (QPCs) are extensively used in semiconductor devices for charge sensing, tunneling and interference experiments. Fabry-Pérot interferometers containing 2 QPCs have applications in quantum computing, in which electrons/quasi-particles undergo interference due to back-scattering from the QPCs. Such experiments have turned out to be difficult because of the complex structure of edge states near the QPC boundary. We present realistic simulations of the edge states in QPCs based on GaAs/AlGaAs heterostructures, which can be used to predict conductance and edge state velocities. Conduction band profile is obtained by solving decoupled effective mass Schrödinger and Poisson equations self-consistently on a finite element mesh of a realistic geometry. In the integer quantum Hall regime, we obtain compressible and in-compressible regions near the edges. We then use the recursive Green`s function algorithm to solve Schrödinger equation with open boundary conditions for calculating transmission and local current density in the QPCs. Impurities are treated by inserting bumps in the potential with a Gaussian distribution. We compare observables with experiments for fitting some adjustable parameters. The authors would like to thank Purdue Research Foundation and Purdue Center for Topological Materials for their support.

VASCo: computation and visualization of annotated protein surface contacts

Directory of Open Access Journals (Sweden)

Thallinger Gerhard G

2009-01-01

Full Text Available Abstract Background Structural data from crystallographic analyses contain a vast amount of information on protein-protein contacts. Knowledge on protein-protein interactions is essential for understanding many processes in living cells. The methods to investigate these interactions range from genetics to biophysics, crystallography, bioinformatics and computer modeling. Also crystal contact information can be useful to understand biologically relevant protein oligomerisation as they rely in principle on the same physico-chemical interaction forces. Visualization of crystal and biological contact data including different surface properties can help to analyse protein-protein interactions. Results VASCo is a program package for the calculation of protein surface properties and the visualization of annotated surfaces. Special emphasis is laid on protein-protein interactions, which are calculated based on surface point distances. The same approach is used to compare surfaces of two aligned molecules. Molecular properties such as electrostatic potential or hydrophobicity are mapped onto these surface points. Molecular surfaces and the corresponding properties are calculated using well established programs integrated into the package, as well as using custom developed programs. The modular package can easily be extended to include new properties for annotation. The output of the program is most conveniently displayed in PyMOL using a custom-made plug-in. Conclusion VASCo supplements other available protein contact visualisation tools and provides additional information on biological interactions as well as on crystal contacts. The tool provides a unique feature to compare surfaces of two aligned molecules based on point distances and thereby facilitates the visualization and analysis of surface differences.

Investigation of pre-drying lignite in an existing Greek power plant

Directory of Open Access Journals (Sweden)

Agraniotis Michalis

2012-01-01

Full Text Available The application of lignite pre-drying technologies in next generation of lignite power plants by utilizing low pressure steam as a drying medium instead of hot recirculated flue gas - combined with thermal utilization of the vaporized coal moisture - is expected to bring efficiency increase of 2-4 percentage points in future lignite power plants compared with today’s state of the art. The pre-drying concept is of particular importance in Greek boilers firing lignite with a high water and ash content. The combustion of Greek predried lignite has been investigated experimentally and via numerical simulations in our previous research. This study focuses on the potential integration of a lignite pre-drying system in an existing Greek power plant with dry lignite co-firing thermal share of up to 30%. The radiative and convective heat fluxes to the boiler and the overall boiler heat balance is calculated for reference and dry lignite co-firing conditions by an in-house calculation code. The overall plant’s thermal cycle is then simulated using commercial thermal cycle calculation software. The net plant efficiency is in this way determined for reference and dry coal co-firing conditions. According to the simulation results the integration of a pre-drying system and the implementation of dry lignite co-firing may bring an efficiency increase of about 1.5 percentage points in existing Greek boilers. It is therefore considered as an important measure towards improving plant efficiency and reducing specific CO2 emissions in existing plants.

Time-dependent contact behavior between diamond and a CNT turf

International Nuclear Information System (INIS)

Qiu, A; Bahr, D F; Fowler, S P; Jiao, J; Kiener, D

2011-01-01

The elastic and adhesive properties of nominally vertically aligned carbon nanotube (CNT) turfs have been measured using nanoindentation. The perceived stiffness of a CNT turf is dependent on the unloading rate, which decreases at slower unloading rates. Depth-controlled nanoindentation was used to examine adhesion effects. Adhesive loads between the turf and the probe tip increased as the time the tip is in contact with the turf increased. As these effects could be from either more tubes coming into contact with the tip due to relaxation and motion of CNTs relative to one another or each tube in contact increasing its adhesive behavior and sub-contact stiffness due to tube-tube interactions within the turf, electrical resistance measurements during nanoindentation were carried out. When the tip is held at a fixed nominal depth, the current remains constant while the contact load decreases, suggesting the number of tubes in contact with the tip stays constant with time while the relaxation mechanisms in the turf occur at positions lower than the contact surface. These observations, in conjunction with in situ TEM compression test of CNT arrays, are used to describe the relative effects the various length and time scales may have on the perceived properties measured during experiments, including elastic modulus and adhesion for gecko-like dry adhesives.

Time-dependent contact behavior between diamond and a CNT turf

Energy Technology Data Exchange (ETDEWEB)

Qiu, A; Bahr, D F [School of Mechanical and Materials Engineering, Washington State University, 99164-2920 WA (United States); Fowler, S P; Jiao, J [Department of Physics, Portland State University, Portland, 97207-0751 OR (United States); Kiener, D, E-mail: anqi_qiu@wsu.edu, E-mail: dbahr@wsu.edu [Department of Materials Physics, University of Leoben, A-8700 Leoben (Austria)

2011-07-22

The elastic and adhesive properties of nominally vertically aligned carbon nanotube (CNT) turfs have been measured using nanoindentation. The perceived stiffness of a CNT turf is dependent on the unloading rate, which decreases at slower unloading rates. Depth-controlled nanoindentation was used to examine adhesion effects. Adhesive loads between the turf and the probe tip increased as the time the tip is in contact with the turf increased. As these effects could be from either more tubes coming into contact with the tip due to relaxation and motion of CNTs relative to one another or each tube in contact increasing its adhesive behavior and sub-contact stiffness due to tube-tube interactions within the turf, electrical resistance measurements during nanoindentation were carried out. When the tip is held at a fixed nominal depth, the current remains constant while the contact load decreases, suggesting the number of tubes in contact with the tip stays constant with time while the relaxation mechanisms in the turf occur at positions lower than the contact surface. These observations, in conjunction with in situ TEM compression test of CNT arrays, are used to describe the relative effects the various length and time scales may have on the perceived properties measured during experiments, including elastic modulus and adhesion for gecko-like dry adhesives.

Time domain contact model for tyre/road interaction including nonlinear contact stiffness due to small-scale roughness

Science.gov (United States)

Andersson, P. B. U.; Kropp, W.

2008-11-01

Rolling resistance, traction, wear, excitation of vibrations, and noise generation are all attributes to consider in optimisation of the interaction between automotive tyres and wearing courses of roads. The key to understand and describe the interaction is to include a wide range of length scales in the description of the contact geometry. This means including scales on the order of micrometres that have been neglected in previous tyre/road interaction models. A time domain contact model for the tyre/road interaction that includes interfacial details is presented. The contact geometry is discretised into multiple elements forming pairs of matching points. The dynamic response of the tyre is calculated by convolving the contact forces with pre-calculated Green's functions. The smaller-length scales are included by using constitutive interfacial relations, i.e. by using nonlinear contact springs, for each pair of contact elements. The method is presented for normal (out-of-plane) contact and a method for assessing the stiffness of the nonlinear springs based on detailed geometry and elastic data of the tread is suggested. The governing equations of the nonlinear contact problem are solved with the Newton-Raphson iterative scheme. Relations between force, indentation, and contact stiffness are calculated for a single tread block in contact with a road surface. The calculated results have the same character as results from measurements found in literature. Comparison to traditional contact formulations shows that the effect of the small-scale roughness is large; the contact stiffness is only up to half of the stiffness that would result if contact is made over the whole element directly to the bulk of the tread. It is concluded that the suggested contact formulation is a suitable model to include more details of the contact interface. Further, the presented result for the tread block in contact with the road is a suitable input for a global tyre/road interaction model

Defining a procedure for predicting the duration of the approximately isothermal segments within the proposed drying regime as a function of the drying air parameters

Science.gov (United States)

Vasić, M.; Radojević, Z.

2017-08-01

One of the main disadvantages of the recently reported method, for setting up the drying regime based on the theory of moisture migration during drying, lies in a fact that it is based on a large number of isothermal experiments. In addition each isothermal experiment requires the use of different drying air parameters. The main goal of this paper was to find a way how to reduce the number of isothermal experiments without affecting the quality of the previously proposed calculation method. The first task was to define the lower and upper inputs as well as the output of the “black box” which will be used in the Box-Wilkinson’s orthogonal multi-factorial experimental design. Three inputs (drying air temperature, humidity and velocity) were used within the experimental design. The output parameter of the model represents the time interval between any two chosen characteristic points presented on the Deff - t. The second task was to calculate the output parameter for each planed experiments. The final output of the model is the equation which can predict the time interval between any two chosen characteristic points as a function of the drying air parameters. This equation is valid for any value of the drying air parameters which are within the defined area designated with lower and upper limiting values.

Diquafosol ophthalmic solution 3 %: a review of its use in dry eye.

Science.gov (United States)

Keating, Gillian M

2015-05-01

Diquafosol ophthalmic solution 3 % (Diquas(®)) is a P2Y2 receptor agonist that promotes tear fluid and mucin secretion and is currently approved in Japan and South Korea for the treatment of dry eye. In randomized, double-blind, multicentre trials in patients with dry eye, significantly greater improvements in fluorescein and rose bengal staining scores were seen with diquafosol ophthalmic solution 3 % than with placebo, and diquafosol ophthalmic solution 3 % was noninferior to sodium hyaluronate ophthalmic solution 0.1 % in terms of the improvement in the fluorescein staining score and more effective than sodium hyaluronate ophthalmic solution 0.1 % in terms of the improvement in the rose bengal staining score. The efficacy of diquafosol ophthalmic solution 3 % in the treatment of dry eye was maintained in the longer term, with improvements also seen in subjective dry eye symptoms, and was also shown in a real-world setting. Diquafosol ophthalmic solution 3 % also demonstrated efficacy in various specific dry eye disorders, including aqueous-deficient dry eye, short tear film break-up time dry eye, obstructive meibomian gland dysfunction, dry eye following laser in situ keratomileusis surgery and dry eye following cataract surgery, as well as in contact lens wearers and visual display terminal users. Diquafosol ophthalmic solution 3 % was generally well tolerated in patients with dry eye, with eye irritation the most commonly reported adverse event. In conclusion, diquafosol ophthalmic solution 3 % is a useful option for the treatment of dry eye.

Minimum heat flux (MHF) point in pool and external-flow boiling

International Nuclear Information System (INIS)

Nishio, Shigefumi

1983-01-01

As for the boiling phenomena near a minimum heat flux (MHF) point to which attention has been paid recently concerning the safety analysis of LWR cores, the results of research have not been put in order sufficiently. Therefore in this explanation, the object is limited to pool boiling and external flow boiling, and it is attempted to rearrange the present knowledge on the phenomena near a MHF point from the viewpoint of the relation to the state of solid-liquid contact, the effect of various factors on a MHF point and the modeling of a MHF point. The heat transfer characteristics in boiling phenomena are represented by a curve with one maximum and one minimum points. The MHF point is called also minimum film boiling point. In a heat flux-controlled heating surface, temperature jump arises when heat flux is decreased at a MHF point. The phenomena near a MHF point and the technological background when a MHF point becomes a problem are explained. Near a MHF point, only partial, intermittent solid-liquid contact is maintained. The effects of solid-liquid contact mode, the geometry of a heating surface, pressure and others on a MHF point are discussed. (Kako, I.)

Highly durable and unidirectionally stooped polymeric nanohairs for gecko-like dry adhesive

International Nuclear Information System (INIS)

Im, Hyeon Seong; Kwon, Ki Yoon; Kim, Jong Uk; Kim, Tae-il; Kim, Kwang Su; Yi, Hoon; Jeong, Hoon Eui; Yoo, Pil J; Pang, Changhyun

2015-01-01

Gecko-like dry adhesive using high aspect ratio polymeric nanohairs has insuperable limitations, although it has huge potential in many applications. Repeated harsh contacts on a target substrate lead to physical collapse of nanohairs and significant degradation of the adhesion property, because the polymeric nanohairs are quite fragile due to poor mechanical robustness. Herein, we demonstrate a highly robust gecko-like dry adhesive with unidirectionally stooped polymeric nanohairs (diameter 100 nm) with a high aspect ratio (∼9) using an ultrathin metal coating. 100 cycles of repeated adhesion tests with 1 N preloading force did not significantly degrade adhesion or cause collapse of nanohairs. We believe that this approach allows gecko-like dry adhesive to be utilized in many related applications and diverse industry interests. (paper)

Characteristics of Timbers Dried Using Kiln Drying and Radio Frequency-Vacuum Drying Systems

OpenAIRE

Rabidin Zairul Amin; Seng Gan Kee; Wahab Mohd Jamil Abdul

2017-01-01

Heavy hardwoods are difficult-to-dry timbers as they are prone to checking and internal stresses when dried using a conventional kiln drying system. These timbers are usually dried naturally to reach 15% to 19% moisture content with an acceptable defects. Besides long drying time, timbers at these moisture contents are not suitable for indoor applications since they will further dry and causing, for example, jointing and lamination failures. Drying to a lower moisture content could only be ac...

Wax solidification of drying agents containing tritiated water

International Nuclear Information System (INIS)

Mishikawa, M.; Kido, H.

1984-01-01

It is necessary to immobilize the tritium not to give any impact on the environmental biosphere because tritium may give profound effects in the metabolic pathway. One of the most probable methods of immobilizing tritium would be incorporation of tritiated water in solid forms. Any drying or dehydration technique would be effective in a tritium cleanup system for off-gas streams containing tritium or tritiated water. Commonly used drying agents such as activated alumina, silica gel, molecular sieves and calcium sulfate are of value for removal of water vapour from air or other gases. For long term tritium storage, however, these adsorptive materials should be enveloped to prevent contact with water or water vapour because the rate of leaching, evaporation or diffusion of tritium from these porous materials is so large. The beeswax solidification method of the packed bed of drying agents adsorbing tritiated water is developed in this study, where the wax solidification procedure is performed by pouring the melt of wax into the void space of the packed bed of the drying agents and successive gradual cooling. The observed values of diffusivity or permeability of tritium in the wax solidified materials are about one-thousandth of those obtained for the cement block. Effect of coating on the rate of leaching is also discussed

Spray drying test of simulated borated waste solutions

International Nuclear Information System (INIS)

An Hongxiang; Zhou Lianquan; Fan Zhiwen; Sun Qi; Lin Xiaolong

2007-01-01

Performance and the effecting factors of spray drying of simulated borated waste solutions is studied for three contaeting methods between the atomized beads and the heated air, in which boron concentration is around 21000 ppm. The contacting modes are centrifugal atomizing co-current flow, pneumatic atomizing co-current flow and mixed flow. The results show that a free-flowing product in all these tests when the temperature of the solutions is between 62 degree C and 64 degree C, the inlet temperature of the spray drying chamber is between 210 degree C and 220 degree C, the temperature of the outlet of the spray drying chamber is between 110 and 120 degree C, the flow rate of the pressure air is 8.0 m 3 /h, the rotational speed of the centrifugal atomizer is 73.0 m/s. The diameters of the powder product which account for 95% of the feed range from 0.356 mm to 0.061 mm. The production capacity and water content in the powder increase in the order of pneumatic atomizing co-current flow, mixed flow and centrifugal atomizing co-current flow. The volume reduction coeffecient of spray drying is in the ranged of 0.22 and 0.27. (authors)

Probing chiral superconductivity in Sr_2RuO_4 underneath the surface by point contact measurements

International Nuclear Information System (INIS)

Wang, He; Luo, Jiawei; Lou, Weijian

2017-01-01

Sr2RuO4 (SRO) is the prime candidate for a chiral p-wave superconductor with critical temperature T_c(SRO)∼1.5 K. Chiral domains with opposite chiralities p_x±ip_y have been proposed, but are yet to be confirmed. We measure the field dependence of the point contact (PC) resistance between a tungsten tip and an SRO–Ru eutectic crystal, where micrometer-sized Ru inclusions are embedded in SRO with an atomically sharp interface. Ruthenium is an s-wave superconductor with T_c(Ru)∼0.5 K; flux pinned near the Ru inclusions can suppress its superconductivity, as reflected in the PC resistance and spectra. This flux pinning effect originates from SRO underneath the surface and is very strong once flux is introduced. To fully remove flux pinning, one needs to thermally cycle the sample above T_c(SRO) or apply alternating fields with decreasing amplitude. With alternating fields, the observed hysteresis in magnetoresistance can be explained by domain dynamics, providing support for the existence of chiral domains. The origin of the strong pinning could be the chiral domains themselves.

Nontrivial transition of transmission in a highly open quantum point contact in the quantum Hall regime

Science.gov (United States)

Hong, Changki; Park, Jinhong; Chung, Yunchul; Choi, Hyungkook; Umansky, Vladimir

2017-11-01

Transmission through a quantum point contact (QPC) in the quantum Hall regime usually exhibits multiple resonances as a function of gate voltage and high nonlinearity in bias. Such behavior is unpredictable and changes sample by sample. Here, we report the observation of a sharp transition of the transmission through an open QPC at finite bias, which was observed consistently for all the tested QPCs. It is found that the bias dependence of the transition can be fitted to the Fermi-Dirac distribution function through universal scaling. The fitted temperature matches quite nicely to the electron temperature measured via shot-noise thermometry. While the origin of the transition is unclear, we propose a phenomenological model based on our experimental results that may help to understand such a sharp transition. Similar transitions are observed in the fractional quantum Hall regime, and it is found that the temperature of the system can be measured by rescaling the quasiparticle energy with the effective charge (e*=e /3 ). We believe that the observed phenomena can be exploited as a tool for measuring the electron temperature of the system and for studying the quasiparticle charges of the fractional quantum Hall states.

Probing into frictional contact dynamics by ultrasound and electrical simulations

Directory of Open Access Journals (Sweden)

Changshan Jin

2014-12-01

Full Text Available Friction arises in the interface of friction pair, and therefore, it is difficult to detect it. Ultrasonic means, as a NDT, is the correct alternative. This paper introduces a means of detecting dynamic contact and an interpretation of behaviors of dry friction. It has been determined that frictional surfaces have a specific property of dynamic response hardening (DRH. Dynamic response forces and oscillation arise during static–kinetic transition process. While the contact zone of sliding surfaces appears “hard” in motion, it appears “soft” at rest. Consequently, a separation of the surfaces occurs and the real area of contact is decreased as sliding velocity increases. This is the cause of F–v descent phenomenon. When the friction comes to a rest, the remaining process of DRH and micro-oscillation do not disappear instantaneously, instead they gradually return to their original static position. The contact area, therefore, is increased by rest period (F–T ascent characteristics. Based on analogies between a solid unit (η–m–k and an R-L-C circuit, the DRH is demonstrated by electrical simulations.

Automatic detection of measurement points for non-contact vibrometer-based diagnosis of cardiac arrhythmias

Science.gov (United States)

Metzler, Jürgen; Kroschel, Kristian; Willersinn, Dieter

2017-03-01

Monitoring of the heart rhythm is the cornerstone of the diagnosis of cardiac arrhythmias. It is done by means of electrocardiography which relies on electrodes attached to the skin of the patient. We present a new system approach based on the so-called vibrocardiogram that allows an automatic non-contact registration of the heart rhythm. Because of the contactless principle, the technique offers potential application advantages in medical fields like emergency medicine (burn patient) or premature baby care where adhesive electrodes are not easily applicable. A laser-based, mobile, contactless vibrometer for on-site diagnostics that works with the principle of laser Doppler vibrometry allows the acquisition of vital functions in form of a vibrocardiogram. Preliminary clinical studies at the Klinikum Karlsruhe have shown that the region around the carotid artery and the chest region are appropriate therefore. However, the challenge is to find a suitable measurement point in these parts of the body that differs from person to person due to e. g. physiological properties of the skin. Therefore, we propose a new Microsoft Kinect-based approach. When a suitable measurement area on the appropriate parts of the body are detected by processing the Kinect data, the vibrometer is automatically aligned on an initial location within this area. Then, vibrocardiograms on different locations within this area are successively acquired until a sufficient measuring quality is achieved. This optimal location is found by exploiting the autocorrelation function.

A fast nonlinear conjugate gradient based method for 3D concentrated frictional contact problems

NARCIS (Netherlands)

J. Zhao (Jing); E.A.H. Vollebregt (Edwin); C.W. Oosterlee (Cornelis)

2015-01-01

htmlabstractThis paper presents a fast numerical solver for a nonlinear constrained optimization problem, arising from 3D concentrated frictional shift and rolling contact problems with dry Coulomb friction. The solver combines an active set strategy with a nonlinear conjugate gradient method. One

Effects of junction resistance and counterelectrode material on point-contact tunneling into single- and polycrystalline YBa/sub 2/Cu/sub 3/O/sub 7-y/

Energy Technology Data Exchange (ETDEWEB)

Moog, E.R.; Hawley, M.E.; Gray, K.E.; Liu, J.Z.; Hinks, D.G.; Capone, D.W. II; Downey, J.

1988-06-01

The effects of junction resistance and counterelectrode material on the results of point-contact tunneling studies into single- and polycrystalline YBa/sub 2/Cu/sub 3/O/sub 7-y/ are illustrated. Although reasonably symmetric I(V) curves predominantly indicate energy gap values /Delta/ /approx/ 20 meV, large asymmetries are often found for high-resistance junctions. Very low-resistance junctions show the expected behavior of pure metallic bridge and indicate /Delta/ /approx/ 25-30 meV.

A Mathematical and Numerically Integrable Modeling of 3D Object Grasping under Rolling Contacts between Smooth Surfaces

Directory of Open Access Journals (Sweden)

Suguru Arimoto

2011-01-01

Full Text Available A computable model of grasping and manipulation of a 3D rigid object with arbitrary smooth surfaces by multiple robot fingers with smooth fingertip surfaces is derived under rolling contact constraints between surfaces. Geometrical conditions of pure rolling contacts are described through the moving-frame coordinates at each rolling contact point under the postulates: (1 two surfaces share a common single contact point without any mutual penetration and a common tangent plane at the contact point and (2 each path length of running of the contact point on the robot fingertip surface and the object surface is equal. It is shown that a set of Euler-Lagrange equations of motion of the fingers-object system can be derived by introducing Lagrange multipliers corresponding to geometric conditions of contacts. A set of 1st-order differential equations governing rotational motions of each fingertip and the object and updating arc-length parameters should be accompanied with the Euler-Lagrange equations. Further more, nonholonomic constraints arising from twisting between the two normal axes to each tangent plane are rewritten into a set of Frenet-Serre equations with a geometrically given normal curvature and a motion-induced geodesic curvature.

Investigating the lubricity and electrical insulation caused by sanding in dry wheel–rail contacts

NARCIS (Netherlands)

Arias-Cuevas, O.; Li, Z.; Lewis, R.

2009-01-01

The adhesion (or available friction) in the wheel–rail contact is the most important parameter for the braking and traction operation of rail vehicles. Since the beginning of railway transportation, sanding from the locomotive has been a common practice to enhance the wheel–rail adhesion. In recent

Allergic contact dermatitis in children and adolescents

DEFF Research Database (Denmark)

Mørtz, Charlotte G; Andersen, Klaus Ejner

1999-01-01

From a clinical point of view, the prevalence of allergic contact dermatitis (ACD) among children and adolescents seems to be low. However, many children have dermatitis, most often atopic dermatitis. In selected cases, ACD is suspected, and the child is tested. The question remains, whether...... the prevalence of ACD in children really is low or whether the possibility of ACD is not sufficiently considered. During the last decade, reports have appeared on series of children and adolescents with contact allergy and ACD. Few cases have been reported in infants, but the development of contact allergy...... and ACD increases with age. Most studies include selected groups of children and adolescents with suspected ACD. Few studies have examined unselected populations, and most consider only the prevalence of contact allergy without evaluating the clinical relevance, e.g., the prevalence of ACD. Furthermore...

Low noise multi-channel biopotential wireless data acquisition system for dry electrodes

Science.gov (United States)

Pandian, P. S.; Whitchurch, Ashwin K.; Abraham, Jose K.; Bhusan Baskey, Himanshu; Radhakrishnan, J. K.; Varadan, Vijay K.; Padaki, V. C.; Bhasker Rao, K. U.; Harbaugh, R. E.

2008-03-01

The bioelectrical potentials generated within the human body are the result of electrochemical activity in the excitable cells of the nervous, muscular or glandular tissues. The ionic potentials are measured using biopotential electrodes which convert ionic potentials to electronic potentials. The commonly monitored biopotential signals are Electrocardiogram (ECG), Electroencephalogram (EEG) and Electromyogram (EMG). The electrodes used to monitor biopotential signals are Ag-AgCl and gold, which require skin preparation by means of scrubbing to remove the dead cells and application of electrolytic gel to reduce the skin contact resistance. The gels used in biopotential recordings dry out when used for longer durations and add noise to the signals and also prolonged use of gels cause irritations and rashes to skin. Also noises such as motion artifact and baseline wander are added to the biopotential signals as the electrode floats over the electrolytic gel during monitoring. To overcome these drawbacks, dry electrodes are used, where the electrodes are held against the skin surface to establish contact with the skin without the need for electrolytic fluids or gels. The major drawback associated with the dry electrodes is the high skin-electrode impedance in the low frequency range between 0.1-120 Hz, which makes it difficult to acquire clean and noise free biopotential signals. The paper presents the design and development of biopotential data acquisition and processing system to acquire biopotential signals from dry electrodes. The electrode-skin-electrode- impedance (ESEI) measurements was carried out for the dry electrodes by impedance spectroscopy. The biopotential signals are processed using an instrumentation amplifier with high CMRR and high input impedance achieved by boot strapping the input terminals. The signals are band limited by means of a second order Butterworth band pass filters to eliminate noise. The processed biopotential signals are digitized

Laser cutting eliminates nucleic acid cross-contamination in dried-blood-spot processing.

Science.gov (United States)

Murphy, Sean C; Daza, Glenda; Chang, Ming; Coombs, Robert

2012-12-01

Dried blood spots (DBS) are useful for molecular assays but are prone to false positives from cross-contamination. In our malaria DBS assay, cross-contamination was encountered despite cleaning techniques suitable for HIV-1. We therefore developed a contact-free laser cutting system that effectively eliminated cross-contamination during DBS processing.

Microbial analysis and survey test of gamma-irradiated freeze-dried fruits for patient's food

Science.gov (United States)

Park, Jae-Nam; Sung, Nak-Yun; Byun, Eui-Hong; Byun, Eui-Baek; Song, Beom-Seok; Kim, Jae-Hun; Lee, Kyung-A.; Son, Eun-Joo; Lyu, Eun-Soon

2015-06-01

This study examined the microbiological and organoleptic qualities of gamma-irradiated freeze-dried apples, pears, strawberries, pineapples, and grapes, and evaluated the organoleptic acceptability of the sterilized freeze-dried fruits for hospitalized patients. The freeze-dried fruits were gamma-irradiated at 0, 1, 2, 3, 4, 5, 10, 12, and 15 kGy, and their quality was evaluated. Microorganisms were not detected in apples after 1 kGy, in strawberries and pears after 4 kGy, in pineapples after 5 kGy, and in grapes after 12 kGy of gamma irradiation. The overall acceptance score, of the irradiated freeze-dried fruits on a 7-point scale at the sterilization doses was 5.5, 4.2, 4.0, 4.1, and 5.1 points for apples, strawberries, pears, pineapples, and grapes, respectively. The sensory survey of the hospitalized cancer patients (N=102) resulted in scores of 3.8, 3.7, 3.9, 3.9, and 3.7 on a 5-point scale for the gamma-irradiated freeze-dried apples, strawberries, pears, pineapples, and grapes, respectively. The results suggest that freeze-dried fruits can be sterilized with a dose of 5 kGy, except for grapes, which require a dose of 12 kGy, and that the organoleptic quality of the fruits is acceptable to immuno-compromised patients. However, to clarify the microbiological quality and safety of freeze-dried fruits should be verified by plating for both aerobic and anaerobic microorganisms.

How Does a Liquid Wet a Solid? Hydrodynamics of Dynamic Contact Angles

Science.gov (United States)

Rame, Enrique

2001-01-01

A contact line is defined at the intersection of a solid surface with the interface between two immiscible fluids. When one fluid displaces another immiscible fluid along a solid surface, the process is called dynamic wetting and a "moving" contact line (one whose position relative to the solid changes in time) often appears. The physics of dynamic wetting controls such natural and industrial processes as spraying of paints and insecticides, dishwashing, film formation and rupture in the eye and in the alveoli, application of coatings, printing, drying and imbibition of fibrous materials, oil recovery from porous rocks, and microfluidics.

Rapid formation of phase-clean 110 K (Bi-2223) powders derived via freeze-drying process

Science.gov (United States)

Balachandran, U.

1996-06-04

A process for the preparation of amorphous precursor powders for Pb-doped Bi{sub 2}Sr{sub 2} Ca{sub 2}Cu{sub 3}O{sub x} (2223) includes a freeze-drying process incorporating a splat-freezing step. The process generally includes splat freezing a nitrate solution of Bi, Pb, Sr, Ca, and Cu to form flakes of the solution without any phase separation; grinding the frozen flakes to form a powder; freeze-drying the frozen powder; heating the dried powder to form a dry green precursor powders; denitrating the green-powders; heating the denitrated powders to form phase-clean Bi-2223 powders. The grain boundaries of the 2223 grains appear to be clean, leading to good intergrain contact between 2223 grains. 11 figs.

40 CFR 406.20 - Applicability; description of the corn dry milling subcategory.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 28 2010-07-01 2010-07-01 true Applicability; description of the corn dry milling subcategory. 406.20 Section 406.20 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS GRAIN MILLS POINT SOURCE CATEGORY Corn Dry Milling...

Staying sticky: contact self-cleaning of gecko-inspired adhesives.

Science.gov (United States)

Mengüç, Yigit; Röhrig, Michael; Abusomwan, Uyiosa; Hölscher, Hendrik; Sitti, Metin

2014-05-06

The exceptionally adhesive foot of the gecko remains clean in dirty environments by shedding contaminants with each step. Synthetic gecko-inspired adhesives have achieved similar attachment strengths to the gecko on smooth surfaces, but the process of contact self-cleaning has yet to be effectively demonstrated. Here, we present the first gecko-inspired adhesive that has matched both the attachment strength and the contact self-cleaning performance of the gecko's foot on a smooth surface. Contact self-cleaning experiments were performed with three different sizes of mushroom-shaped elastomer microfibres and five different sizes of spherical silica contaminants. Using a load-drag-unload dry contact cleaning process similar to the loads acting on the gecko foot during locomotion, our fully contaminated synthetic gecko adhesives could recover lost adhesion at a rate comparable to that of the gecko. We observed that the relative size of contaminants to the characteristic size of the microfibres in the synthetic adhesive strongly determined how and to what degree the adhesive recovered from contamination. Our approximate model and experimental results show that the dominant mechanism of contact self-cleaning is particle rolling during the drag process. Embedding of particles between adjacent fibres was observed for particles with diameter smaller than the fibre tips, and further studied as a temporary cleaning mechanism. By incorporating contact self-cleaning capabilities, real-world applications of synthetic gecko adhesives, such as reusable tapes, clothing closures and medical adhesives, would become feasible.

Graphical assessment of the linear contact steel on composite material at high temperature and pressure

Science.gov (United States)

Rus, Dorin; Florescu, Virgil; Bausic, Florin; Ursache, Robert; Sasu, Anca

2018-01-01

In this article we have tried to present a graphical assessment of the dry linear contact for composite materials reinforced with glass fibers as well as of the influence of the sliding speed, load and friction coefficient. Perpendicular loads, the contact temperature and the wear of the metal surface were recorded. The wear volume was calculated using the Archard relationship. Using the Archard relationship, the width of trace can be calculated in 3 locations. Numerous experimental trials were performed in connection to the wear of the metal surface, the contact temperature and the value of the friction coefficient. A connection between the evolution of the wear process and the dependency on the contact temperature and friction coefficient can be observed.

Stabilization of Live Attenuated Influenza Vaccines by Freeze Drying, Spray Drying, and Foam Drying.

Science.gov (United States)

Lovalenti, Phillip M; Anderl, Jeff; Yee, Luisa; Nguyen, Van; Ghavami, Behnaz; Ohtake, Satoshi; Saxena, Atul; Voss, Thomas; Truong-Le, Vu

2016-05-01

The goal of this research is to develop stable formulations for live attenuated influenza vaccines (LAIV) by employing the drying methods freeze drying, spray drying, and foam drying. Formulated live attenuated Type-A H1N1 and B-strain influenza vaccines with a variety of excipient combinations were dried using one of the three drying methods. Process and storage stability at 4, 25 and 37°C of the LAIV in these formulations was monitored using a TCID50 potency assay. Their immunogenicity was also evaluated in a ferret model. The thermal stability of H1N1 vaccine was significantly enhanced through application of unique formulation combinations and drying processes. Foam dried formulations were as much as an order of magnitude more stable than either spray dried or freeze dried formulations, while exhibiting low process loss and full retention of immunogenicity. Based on long-term stability data, foam dried formulations exhibited a shelf life at 4, 25 and 37°C of >2, 1.5 years and 4.5 months, respectively. Foam dried LAIV Type-B manufactured using the same formulation and process parameters as H1N1 were imparted with a similar level of stability. Foam drying processing methods with appropriate selection of formulation components can produce an order of magnitude improvement in LAIV stability over other drying methods.

On the zero-bias anomaly and Kondo physics in quantum point contacts near pinch-off.

Science.gov (United States)

Xiang, S; Xiao, S; Fuji, K; Shibuya, K; Endo, T; Yumoto, N; Morimoto, T; Aoki, N; Bird, J P; Ochiai, Y

2014-03-26

We investigate the linear and non-linear conductance of quantum point contacts (QPCs), in the region near pinch-off where Kondo physics has previously been connected to the appearance of the 0.7 feature. In studies of seven different QPCs, fabricated in the same high-mobility GaAs/AlGaAs heterojunction, the linear conductance is widely found to show the presence of the 0.7 feature. The differential conductance, on the other hand, does not generally exhibit the zero-bias anomaly (ZBA) that has been proposed to indicate the Kondo effect. Indeed, even in the small subset of QPCs found to exhibit such an anomaly, the linear conductance does not always follow the universal temperature-dependent scaling behavior expected for the Kondo effect. Taken collectively, our observations demonstrate that, unlike the 0.7 feature, the ZBA is not a generic feature of low-temperature QPC conduction. We furthermore conclude that the mere observation of the ZBA alone is insufficient evidence for concluding that Kondo physics is active. While we do not rule out the possibility that the Kondo effect may occur in QPCs, our results appear to indicate that its observation requires a very strict set of conditions to be satisfied. This should be contrasted with the case of the 0.7 feature, which has been apparent since the earliest experimental investigations of QPC transport.

An Internally Heated Shape Memory Polymer Dry Adhesive

Directory of Open Access Journals (Sweden)

Jeffrey Eisenhaure

2014-08-01

Full Text Available A conductive epoxy-based shape memory polymer (SMP is demonstrated using carbon black (CB as a dopant for the purpose of creating an SMP dry adhesive system which can internally generate the heat required for activation. The electrical and mechanical properties of the CB/SMP blends for varying dopant concentrations are characterized. A composite adhesive is created to minimize surface contact resistance to conductive tape acting as electrodes, while maintaining bulk resistivity required for heat generation due to current flow. The final adhesive can function on flat or curved surfaces. As a demonstration, a 25 mm wide by 45 mm long dry adhesive strip is shown to heat evenly from an applied voltage, and can easily hold a mass in excess of 6 kg when bonded to a spherical concave glass surface using light pressure at 75 °C.

Modeling and calculation of impact friction caused by corner contact in gear transmission

Science.gov (United States)

Zhou, Changjiang; Chen, Siyu

2014-09-01

Corner contact in gear pair causes vibration and noise, which has attracted many attentions. However, teeth errors and deformation make it difficulty to determine the point situated at corner contact and study the mechanism of teeth impact friction in the current researches. Based on the mechanism of corner contact, the process of corner contact is divided into two stages of impact and scratch, and the calculation model including gear equivalent error—combined deformation is established along the line of action. According to the distributive law, gear equivalent error is synthesized by base pitch error, normal backlash and tooth profile modification on the line of action. The combined tooth compliance of the first point lying in corner contact before the normal path is inversed along the line of action, on basis of the theory of engagement and the curve of tooth synthetic compliance & load-history. Combined secondarily the equivalent error with the combined deflection, the position standard of the point situated at corner contact is probed. Then the impact positions and forces, from the beginning to the end during corner contact before the normal path, are calculated accurately. Due to the above results, the lash model during corner contact is founded, and the impact force and frictional coefficient are quantified. A numerical example is performed and the averaged impact friction coefficient based on the presented calculation method is validated. This research obtains the results which could be referenced to understand the complex mechanism of teeth impact friction and quantitative calculation of the friction force and coefficient, and to gear exact design for tribology.

Contact toxicities of anuran skin alkaloids against the fire ant ( Solenopsis invicta)

Science.gov (United States)

Weldon, Paul J.; Cardoza, Yasmin J.; Vander Meer, Robert K.; Hoffmann, W. Clint; Daly, John W.; Spande, Thomas F.

2013-02-01

Nearly 500 alkaloids, representing over 20 structural classes, have been identified from the skin of neotropical poison frogs (Dendrobatidae). These cutaneous compounds, which are derived from arthropod prey of the frogs, generally are believed to deter predators. We tested the red imported fire ant ( Solenopsis invicta) for toxicosis following contact with 20 alkaloids (12 structural classes) identified from dendrobatids or other anurans. Individual ants forced to contact the dried residues of 13 compounds exhibited convulsions and/or reduced ambulation. We estimated the cutaneous concentrations of several compounds based on their reported recoveries from skin extracts of free-ranging frogs and our measurements of the skin surface areas of museum specimens. Pumiliotoxin 251D exhibited contact toxicity below its estimated cutaneous concentration in the Ecuadorian frog, Epipedobates anthonyi, an observation consistent with the hypothesized role of this compound in anuran chemical defense. Our results and those of a previous study of mosquitoes indicate that some anuran skin compounds function defensively as contact toxins against arthropods, permeating their exoskeleton.

Surgical outcome in headache due to mucosal contact

International Nuclear Information System (INIS)

Goto, Fumiyuki; Yabe, Haruna; Ogawa, Kaoru

2010-01-01

Headaches is classified as primary and secondary, with secondary originating in head and neck conditions, the most important etiology being acute sinusitis. Headache due to mucosal contact, rarely encountered by otorhinolaryngologists, is an important secondary headache, whose criteria are defined by the International Classification of Headache Disorders to include intermittent pain localized in the periorbital and medial canthal or temporozygomatic regions, evidence that pain is attributable to mucosal contact and the presence of mucosal contact in the absence of acute rhinosinusitis, obtained using clinical examinations, nasal endoscopy, and/or computed tomography (CT). After mucosal contact is surgically corrected pain usually disappears permanently within 7 days. We reviewed mucosal contact headaches in 63 subjects undergoing nasal or paranasal surgery from April 2007 to March 2008. Of those 7 were diagnosed with headaches due to contact points in nasal mucosa, ranging from canthal to the temporozygomatic. The most common contact, between the middle turbinate and nasal septum, was seen in 6 of the 7. Surgery eliminated symptoms in 4 and ameliorated them in 3 indicating effective headache management. Subjects with severe headaches or localized periorbital and medial canthal pain regions, mucosal contact involvement is ruled out when CT allows no lesions. When mucosal contact headache is suspected, however surgery should be considered as a last resort. (author)

Clinical efficacy of pranoprofen and sodium hyaluronate for dry eye

Directory of Open Access Journals (Sweden)

Hong-Chao Hou

2016-01-01

Full Text Available AIM:To observe the clinical efficacy of pranoprofen and sodium hyaluronate for dry eye, and to provide the reference for clinical treatment of dry eye. METHODS: From January 2012 to January 2015 inour hospital, 106 patients with dry eye were tested and observed. In accordance with the number table, patients were divided into observation group and control group, 53 patients in the control group using conventional treatment plus single sodium hyaluronate eye drops, observation group using pranoprofen combined sodium hyaluronate eye drops, besides conventional treatment. Clinical outcomes between the two groups before and after treatments, dry eye score, fluorescein staining score, Schirmer I test and tear film break up time(BUTwere observed and analyzed. RESULTS:The effective rates of the two groups were 94.3%(50/53and 84.9%(45/53. Dry eye score of observation group before and after treatment were 3.24±0.52 and 0.32±0.06points, those of the control group were 3.26±0.48 and 0.75±0.24points. BUT of the experimental group before and after treatments were 5.67±3.052 and 12.95±2.865s, those of the control group were 6.23±2.985 and 9.85±2.714s.The differences between the two groups on the indicators above were statistically significant(PCONCLUSION: The combination of pranoprofen and sodium hyaluronate for the treatment of dry eye is effective, with high security and water holding capacity, which can improve the symptoms of dry eye and the patients' life quality.

Fluorophotometry as a diagnostic tool for the evaluation of dry eye disease

Directory of Open Access Journals (Sweden)

Fan Vincent C

2006-05-01

Full Text Available Abstract Background Dry eye disease is a common debilitating ocular disease. Current diagnostic tests used in dry eye disease are often neither sensitive nor reproducible, making it difficult to accurately diagnose and determine end points for clinical trials, or evaluate the usefulness of different medications in the treatment of dry eye disease. The recently developed fluorophotometer can objectively detect changes in the corneal epithelium by quantitatively measuring its barrier function or permeability. The purpose of the study is to investigate the use of corneal fluorescein penetration measured by the fluorophotometer as a diagnostic tool in the evaluation of dry eye patients. Methods Dry eye patients (16 eyes, who presented with a chief complaint of ocular irritation corresponding with dry eye, low Schirmer's one test ( Results Ten minutes after fluorescein installition, patients with dry eye disease averaged a five-fold increase in corneal tissue fluorescein concentration (mean = 375.26 ± 202.67 ng/ml compared with that of normal subjects (mean = 128.19 ± 85.84 ng/ml. Sixty minutes after dye installation, patients with dry eye disease still revealed higher corneal tissue fluorescein concentration (mean = 112.87 ± 52.83 ng/ml compared with that of controls (mean = 40.64 ± 7.96 ng/ml, averaging a three-fold increase. Conclusion Patients with dry eye disease demonstrated an increased corneal permeability and a slower rate of elimination to topically administered fluorescein when measured by the fluorophotometer. This suggests that fluorophotometry may serve as a valuable quantitative and objective tool for the diagnosis of dry eye disease, and in following patients' response to new treatment modalities. Fluorophotometry may serve as an objective non-invasive tool for end-point analysis in clinical trials of new treatments for dry eye disease.

A new technique for direct traceability of contact thermometry Co-C eutectic cells to the ITS-90

Energy Technology Data Exchange (ETDEWEB)

Failleau, G.; Deuzé, T.; Bourson, F.; Briaudeau, S.; Sadli, M. [Laboratoire Commun de Métrologie LNE-Cnam, 61 rue du Landy 93210 La Plaine Saint Denis (France)

2013-09-11

The eutectic Co-C melting point is a promising system to serve as a thermometric fixed-point in the temperature range above 1084.62 °C (copper freezing point). During the last decade, LNE-Cnam has developed and characterized some fixed-point devices, based on eutectic Co-C alloy, for applications to contact and radiation thermometry. Above 962 °C, the ITS-90 is realized by radiation thermometry by the extrapolation from a Ag, Au or Cu fixed point using the Planck law for radiation. So the only way for assigning a temperature in the scale to a Co-C cell (∼1324 °C) is by radiation thermometry. An indirect method is commonly used to assign a temperature to a high-temperature fixed point (HTFP) cell designed for contact thermometry is to fill a pyrometric cell with the same mixture as the contact thermometry cell. In this case, the temperature assigned to the pyrometric cell is attributed to the contact cell. This paper describes a direct method allowing the determination of the melting temperature realized by a 'contact thermometry' Co-C cell by comparison to a 'radiation thermometry' Co-C cell whose melting temperature was assigned in accordance to the scale by extrapolation from the Cu point. In addition, the same Co-C cell is studied with a standard Pt/Pd thermocouple.

The Relationship Between Microscopic Grain Surface Structure and the Dynamic Capillary-Driven Advance of Water Films over Individual Dry Natural Sand Grains

Science.gov (United States)

Kibbey, T. C. G.; Adegbule, A.; Yan, S.

2017-12-01

The movement of nonvolatile solutes in unsaturated porous media at low water contents depends on transport in surface-associated water films. The focus of the work described here was on studying solute movement in water films advancing by capillary forces over initially-dry grain surfaces, to understand how microscopic surface roughness features influence the initial velocity of water film advance. For this work, water containing a non-adsorbing conservative tracer was used to track the movement of advancing water films. A stainless steel capillary tube connected to an external reservoir a fixed distance below the grain surface was used to transmit solution to the grain surface under negative pressure (positive capillary pressure), consistent with conditions that might be expected in the unsaturated zone. The small internal diameter of the capillary prevents solution from draining out of the capillary back into the reservoir. When the capillary is contacted with a grain surface, capillary forces that result from contact between the fluid and the rough grain surface cause water films to wick across the grain surface. Multiple experiments were conducted on the same grain, rotating the grain and varying the capillary contact point around the circumference of the grain. Imaging was conducted at fixed intervals using an automated Extended Depth of Field (EDF) imaging system, and images were analyzed to determine initial velocity. Grain surfaces were then characterized through scanning electron microscope (SEM) imaging, using a hybrid stereoscopic reconstruction method designed to extract maximum detail in creating elevation maps of geologic surfaces from tilted pairs of SEM images. The resulting elevation maps were used to relate surface roughness profiles around the grain with initial velocities. Results suggest that velocity varies significant with contact point around an individual grain, and correlates quantitatively with the local grain surface structure

Enhanced quantum yield of photoluminescent porous silicon prepared by supercritical drying

Energy Technology Data Exchange (ETDEWEB)

Joo, Jinmyoung [Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093 (United States); Biomedical Engineering Research Center, Asan Institute for Life Sciences, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505 (Korea, Republic of); Defforge, Thomas; Gautier, Gael, E-mail: msailor@ucsd.edu, E-mail: gael.gautier@univ-tours.fr, E-mail: lcanham@psivida.com [Universite Francois Rabelais de Tours, CNRS CEA, INSA-CVL, GREMAN UMR 7347, 37071 Tours Cedex 2 (France); Loni, Armando [pSiMedica Ltd., Malvern Hills Science Park, Geraldine Road, Malvern, Worcestershire WR14 3SZ (United Kingdom); Kim, Dokyoung; Sailor, Michael J., E-mail: msailor@ucsd.edu, E-mail: gael.gautier@univ-tours.fr, E-mail: lcanham@psivida.com [Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093 (United States); Li, Z. Y. [Nanoscale Physics Research Laboratory, School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Canham, Leigh T., E-mail: msailor@ucsd.edu, E-mail: gael.gautier@univ-tours.fr, E-mail: lcanham@psivida.com [pSiMedica Ltd., Malvern Hills Science Park, Geraldine Road, Malvern, Worcestershire WR14 3SZ (United Kingdom); Nanoscale Physics Research Laboratory, School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)

2016-04-11

The effect of supercritical drying (SCD) on the preparation of porous silicon (pSi) powders has been investigated in terms of photoluminescence (PL) efficiency. Since the pSi contains closely spaced and possibly interconnected Si nanocrystals (<5 nm), pore collapse and morphological changes within the nanocrystalline structure after common drying processes can affect PL efficiency. We report the highly beneficial effects of using SCD for preparation of photoluminescent pSi powders. Significantly higher surface areas and pore volumes have been realized by utilizing SCD (with CO{sub 2} solvent) instead of air-drying. Correspondingly, the pSi powders better retain the porous structure and the nano-sized silicon grains, thus minimizing the formation of non-radiative defects during liquid evaporation (air drying). The SCD process also minimizes capillary-stress induced contact of neighboring nanocrystals, resulting in lower exciton migration levels within the network. A significant enhancement of the PL quantum yield (>32% at room temperature) has been achieved, prompting the need for further detailed studies to establish the dominant causes of such an improvement.

The INCAS Project: An Innovative Contact-Less Angular Sensor

Science.gov (United States)

Ghislanzoni, L.; Di Cintio, A.; Solimando, M.; Parzianello, G.

2013-09-01

Angular Positions sensors are widely used in all spacecrafts, including re-entry vehicles and launchers, where mechanisms and pointing-scanning devices are required. The main applications are on mechanisms for TeleMeasure (TM) related to the release and deployment of devices, or on rotary mechanisms such as Solar Array Drive Mechanism (SADM) and Antenna Pointing Mechanism (APM). Longer lifetime (up to 7- 10 years) is becoming a new driver for the coming missions and contact technology sensors often incur in limitations due to the wear of the contacting parts [1].A Self-Compensating Absolute Angular Encoder was developed and tested in the frame of an ESA's ARTES 5.2 project, named INCAS (INnovative Contact-less Angular Sensor). More in particular, the INCAS sensor addresses a market need for contactless angular sensors aimed at replacing the more conventional rotary potentiometers, while featuring the same level of accuracy performances and extending the expected lifetime.

Meibomian gland dropout in patients with dry eye disease in China.

Science.gov (United States)

Feng, Yun; Gao, Ziqing; Feng, Kang; Qu, Hongqiang; Hong, Jing

2014-10-01

To examine the morphological changes in the meibomian glands of eyes of patients with dry eye disease using the non-contact infrared meibography system and to assess their relationship with meibomian dropout, signs, and tear-film function. Subjects included 264 randomly selected patients (528 eyes) suffering from dry eye disease (95 males, 169 females; age range, 7-85 years; mean male age, 39.83 ± 19.17 years; mean female age, 46.16 ± 17.38 years). Tear-film break-up time (BUT) was measured and tear-film production was evaluated by the Schirmer test I (SIT). Subjective symptoms were also scored. The upper and lower eyelids were turned over, and the meibomian glands were observed using the non-contact meibography system. Partial or complete loss of the meibomian glands (meibomian dropout) was scored for each eyelid from grade 0 (no loss) through grade 3 (lost area was >2/3 of the total meibomian gland area). The average SIT result was 6.71 ± 6.13 mm (range 0-30 mm) and that for BUT was 3.13 ± 2.39 s (range 0-10 s). The average fluorescein staining score was 4.25 ± 4.05 (range 0-12). In addition, the mean meibomian gland photographic score was 4.35 ± 1.39. The correlation between the meibomian gland photographic scores and various ocular surface examinations were evaluated using Kendall's correlation. SIT and BUT were significantly negatively correlated with the meibomian gland photographic score, whereas corneal fluorescein staining was positively correlated. The results suggest a large proportion of meibomian dropout cases among patients with dry eye disease, indicating that treatment targeted at the meibomian gland will become an important direction for treating dry eye disease. Meibography is recommended as a routine test for dry eye disease.

Controlled delivery of pirfenidone through vitamin E-loaded contact lens ameliorates corneal inflammation.

Science.gov (United States)

Dixon, Phillip; Ghosh, Tanushri; Mondal, Kalyani; Konar, Aditya; Chauhan, Anuj; Hazra, Sarbani

2018-06-01

Chemical injury by alkali burn is a major cause of corneal blindness in the clinical setting. Current management advocates multiple therapies aimed to prevent inflammation, initiate quick re-epithelialization, arrest the fibrosis, and avoid dry eye and pain by using bandage contact lenses. We hypothesized sustained delivery of the anti-inflammatory, antifibrotic drug pirfenidone through vitamin E-loaded contact lenses as a logical single approach to counter the pathology involved. Vitamin E particles were created in situ in commercial silicon hydrogel contact lenses by soaking the lenses in a vitamin E-ethanol solution. The vitamin E-laden lenses were then placed into pirfenidone-saline solution to load the drug into the lens. The contact lenses were evaluated by both in vitro and in vivo means. For in vitro, lenses were placed into 3 mL of saline solution. The concentration of pirfenidone released was measured by UV-vis spectrophotometry. The contact lenses were implanted in rabbit eyes following the alkali burn; the drug availability in the aqueous humor was evaluated by HPLC at various time points 10 min, 30 min, 2 h, and 3 h; and gene expression of inflammatory cytokines IL-1β, TNF-α, and TGF-β1 was evaluated in the cornea at the end of the study period. In another group of rabbits inflicted with alkali injury, the corneas were graded after 7 days of contact lens implantation with and without pirfenidone. A mathematical model was developed for delivery of the drug to the cornea and aqueous humor after a contact lens is inserted in the eye. The model was validated with experimental data and used to determine the bioavailability both for contact lenses and eye drops. In vitro release of unmodified commercial contact lenses saw a release time of approximately 20 min, with a partition coefficient of 2.68 ± 0.06. The release of pirfenidone from 20% vitamin E-loaded lenses saw a release time of approximately 80 min, with a partition coefficient of 4

UO{sub 2} oxidation under dry storage conditions: From data gaps to research needs

Energy Technology Data Exchange (ETDEWEB)

Feria, F.; Herranz, L. E. [CIEMAT, Andalucia (Spain)

2008-10-15

Dry interim storage is becoming a major activity of today's fuel cycle. The potential contact between no grossly damaged fuel rods (i.e., rods containing tiny defects like pinhole leaks and hairline cracks) and an oxidizing atmosphere during the cask water removal might lead to unacceptable consequences. One way to prevent it is to determine the time to propagation of a defect at given conditions. This paper compiles and critically reviews the existing database concerning time at temperature profile of fuel rods containing tiny defects that are exposed to oxidizing atmospheres. This review has pointed out significant drawbacks and limitations that would hinder its reliable application to assess the potential for defect propagation of current LWR fuels to be loaded in dry storage casks. Those weaknesses come essentially from data scarcity and lack of tests representativity. Based on this study, three main areas of work are recommended to fill the existing knowledge gaps: sound characterization of fuel rod responses in the low burnup range (<30 GWd/tU), extension of the database to high burnups characteristic of current discharged LWR fuels (<60GWd/tU), assessment of availability (i.e., amount and nature) of oxidizing agents. The result of the work suggested would result in a more complete and extensive database that would strongly support the potential use of 'time at temperature' curves.

Multi-contact Variable-Compliance Manipulation in Extreme Clutter

Science.gov (United States)

2014-06-16

house to find eggs and young. (b) When noodling , people find catfish holes from which to pull fish out. (c)-(d) A person makes contact along his...Figure 7: Haptic Map of detected rigid contacts. by mapping all the rigid taxels at every time- instant . For visualizing the haptic map, we use point...the environment while reaching into clutter. (a) A raccoon reaches into a bird house to find eggs and young. (b) When noodling , people find catfish

Dry and Semi-Dry Tropical Cyclones

Science.gov (United States)

Cronin, T.; Chavas, D. R.

2017-12-01

Our understanding of dynamics in our real moist atmosphere is strongly informed by idealized dry models. It is widely believed that tropical cyclones (TCs) are an intrinsically moist phenomenon - relying fundamentally on evaporation and latent heat release - yet recent numerical modeling work has found formation of dry axisymmetric tropical cyclones from a state of dry radiative-convective equilibrium. What can such "dry hurricanes" teach us about intensity, structure, and size of real moist tropical cyclones in nature? Are dry TCs even stable in 3D? What about surfaces that are nearly dry but have some latent heat flux - can they also support TCs? To address these questions, we use the SAM cloud-system resolving model to simulate radiative-convective equilibrium on a rapidly rotating f-plane, subject to constant tropospheric radiative cooling. We use a homogeneous surface with fixed temperature and with surface saturation vapor pressure scaled by a factor 0-1 relative to that over pure water - allowing for continuous variation between moist and dry limits. We also explore cases with surface enthalpy fluxes that are uniform in space and time, where partitioning between latent and sensible heat fluxes is specified directly. We find that a completely moist surface yields a TC-world where multiple vortices form spontaneously and persist for tens of days. A completely dry surface can also yield a parallel dry TC-world with many vortices that are even more stable and persistent. Spontaneous cyclogenesis, however, is impeded for a range of low to intermediate surface wetness values, and by the combination of large rotation rates and a dry surface. We discuss whether these constraints on spontaneous cyclogenesis might arise from: 1) rain evaporation in the subcloud layer limiting the range of viable surface wetness values, and 2) a natural convective Rossby number limiting the range of viable rotation rates. Finally, we discuss simulations with uniform surface enthalpy

Piercing the water surface with a blade: Singularities of the contact line

Energy Technology Data Exchange (ETDEWEB)

Alimov, Mars M. [Kazan Federal University, Kazan 420008 (Russian Federation); Kornev, Konstantin G. [Department of Materials Science & Engineering, Clemson University, Clemson, South Carolina 29634 (United States)

2016-01-15

An external meniscus on a narrow blade with a slit-like cross section is studied using the hodograph formulation of the Laplace nonlinear equation of capillarity. On narrow blades, the menisci are mostly shaped by the wetting and capillary forces; gravity plays a secondary role. To describe a meniscus in this asymptotic case, the model of Alimov and Kornev [“Meniscus on a shaped fibre: Singularities and hodograph formulation,” Proc. R. Soc. A 470, 20140113 (2014)] has been employed. It is shown that at the sharp edges of the blade, the contact line makes a jump. In the wetting case, the contact line sitting at each side of the blade is lifted above the points where the meniscus first meets the blade edges. In the non-wetting case, the contact line is lowered below these points. The contours of the constant height emanating from the blade edges generate unusual singularities with infinite curvatures at some points at the blade edges. The meniscus forms a unique surface made of two mirror-symmetric sheets fused together. Each sheet is supported by the contact line sitting at each side of the blade.

Piercing the water surface with a blade: Singularities of the contact line

International Nuclear Information System (INIS)

Alimov, Mars M.; Kornev, Konstantin G.

2016-01-01

An external meniscus on a narrow blade with a slit-like cross section is studied using the hodograph formulation of the Laplace nonlinear equation of capillarity. On narrow blades, the menisci are mostly shaped by the wetting and capillary forces; gravity plays a secondary role. To describe a meniscus in this asymptotic case, the model of Alimov and Kornev [“Meniscus on a shaped fibre: Singularities and hodograph formulation,” Proc. R. Soc. A 470, 20140113 (2014)] has been employed. It is shown that at the sharp edges of the blade, the contact line makes a jump. In the wetting case, the contact line sitting at each side of the blade is lifted above the points where the meniscus first meets the blade edges. In the non-wetting case, the contact line is lowered below these points. The contours of the constant height emanating from the blade edges generate unusual singularities with infinite curvatures at some points at the blade edges. The meniscus forms a unique surface made of two mirror-symmetric sheets fused together. Each sheet is supported by the contact line sitting at each side of the blade

Effect of spherical Au nanoparticles on nanofriction and wear reduction in dry and liquid environments

Science.gov (United States)

Maharaj, Dave

2012-01-01

Summary Nano-object additives are used in tribological applications as well as in various applications in liquids requiring controlled manipulation and targeting. On the macroscale, nanoparticles in solids and liquids have been shown to reduce friction and wear. On the nanoscale, atomic force microscopy (AFM) studies have been performed in single- and multiple-nanoparticle contact, in dry environments, to characterize friction forces and wear. However, limited studies in submerged liquid environments have been performed and further studies are needed. In this paper, spherical Au nanoparticles were studied for their effect on friction and wear under dry conditions and submerged in water. In single-nanoparticle contact, individual nanoparticles, deposited on silicon, were manipulated with a sharp tip and the friction force was determined. Multiple-nanoparticle contact sliding experiments were performed on nanoparticle-coated silicon with a glass sphere. Wear tests were performed on the nanoscale with AFM as well as on the macroscale by using a ball-on-flat tribometer to relate friction and wear reduction on the nanoscale and macroscale. Results indicate that the addition of Au nanoparticles reduces friction and wear. PMID:23213639

Effect of spherical Au nanoparticles on nanofriction and wear reduction in dry and liquid environments

Directory of Open Access Journals (Sweden)

Dave Maharaj

2012-11-01

Full Text Available Nano-object additives are used in tribological applications as well as in various applications in liquids requiring controlled manipulation and targeting. On the macroscale, nanoparticles in solids and liquids have been shown to reduce friction and wear. On the nanoscale, atomic force microscopy (AFM studies have been performed in single- and multiple-nanoparticle contact, in dry environments, to characterize friction forces and wear. However, limited studies in submerged liquid environments have been performed and further studies are needed. In this paper, spherical Au nanoparticles were studied for their effect on friction and wear under dry conditions and submerged in water. In single-nanoparticle contact, individual nanoparticles, deposited on silicon, were manipulated with a sharp tip and the friction force was determined. Multiple-nanoparticle contact sliding experiments were performed on nanoparticle-coated silicon with a glass sphere. Wear tests were performed on the nanoscale with AFM as well as on the macroscale by using a ball-on-flat tribometer to relate friction and wear reduction on the nanoscale and macroscale. Results indicate that the addition of Au nanoparticles reduces friction and wear.

Control of Nanofilament Structure and Observations of Quantum Point Contact Behavior in Ni/NiO Nanowire Junctions

Science.gov (United States)

Oliver, Sean; Fairfield, Jessamyn; Lee, Sunghun; Bellew, Allen; Stone, Iris; Ruppalt, Laura; Boland, John; Vora, Patrick

Resistive switching is ideal for use in non-volatile memory where information is stored in a metallic or insulating state. Nanowire junctions formed at the intersection of two Ni/NiO core/shell nanowires have emerged as a leading candidate structure where resistive switching occurs due to the formation and destruction of conducting filaments. However, significant knowledge gaps remain regarding the conduction mechanisms as measurements are typically only performed at room temperature. Here, we combine temperature-dependent current-voltage (IV) measurements from 15 - 300 K with magnetoresistance studies and achieve new insight into the nature of the conducting filaments. We identify a novel semiconducting state that behaves as a quantum point contact and find evidence for a possible electric-field driven phase transition. The insulating state exhibits unexpectedly complex IV characteristics that highlight the disordered nature of the ruptured filament while we find clear signs of anisotropic magnetoresistance in the metallic state. Our results expose previously unobserved behaviors in nanowire resistive switching devices and pave the way for future applications where both electrical and magnetic switching can be achieved in a single device. This work was supported by ONR Grant N-00014-15-1-2357.

Prevalence and risk factors of contact dermatitis among clothing manufacturing employees in Beijing

Science.gov (United States)

Chen, Yu-Xin; Cheng, Hai-Yan; Li, Lin-Feng

2017-01-01

Abstract Little is known about the epidemiology of contact dermatitis (CD) in the Chinese clothing industry. This study aimed to investigate the prevalence and some risk factors of contact dermatitis among clothing manufacturing employees in Beijing. This cross-sectional study was conducted by interview using self-administered questionnaires and skin examination between May and August in 2016. Five-hundred twenty-nine employees who had worked at sewing, ironing, and as managers at 12 clothing manufacturing factories were studied. The overall 1-year prevalence of CD among the clothing employees was 28.5% (151/529 employees), with significantly higher prevalence among ironing workers (50%) and sewers (31.7%) compared with managers (12.7%; P garment materials (leather and feather), dry skin, allergic rhinitis, age, and smoking. Among employees in Chinese clothing industry, sewers and ironing workers had a higher 1-year prevalence of CD than managers. It is noteworthy that exposure to leather and feather materials and the types of manual work are associated with CD, as well as dry skin and allergic rhinitis. PMID:28328819

Critical Point Dryer: Tousimis 916B Series C

Data.gov (United States)

Federal Laboratory Consortium — Description:CORAL Name: Critical Point DryerThis system utilizes CO 2to dry fragile suspended and floating structures Specifications / Capabilities:Wafer size up to...

Surface-sensitive conductivity measurement using a micro multi-point probe approach

DEFF Research Database (Denmark)

Perkins, Edward; Barreto, Lucas; Wells, Justin

2013-01-01

An instrument for microscale electrical transport measurements in ultra-high vacuum is presented. The setup is constructed around collinear lithographically-created multi-point probes with a contact spacing down to 500 nm. Most commonly, twelve-point probes are used. These probes are approached...... measurements with an equidistant four-point probe for a wide range of contact spacings. In this way, it is possible to distinguish between bulk-like and surface-like conduction. The paper describes the design of the instrument and the approach to data and error analysis. Application examples are given...

Characterizations of contact and sheet resistances of vertically aligned carbon nanotube forests with intrinsic bottom contacts

Energy Technology Data Exchange (ETDEWEB)

Jiang Yingqi; Wang Pengbo; Lin Liwei, E-mail: jiangyq99@gmail.com, E-mail: lwlin@me.berkeley.edu [Mechanical Engineering Department, University of California at Berkeley (United States)

2011-09-07

Comprehensive studies on the sheet and contact resistances of vertically aligned carbon nanotube (CNT) forests with as-grown bottom contacts to the metal layer have been conducted. Using microfabrication and four distinct methods: (1) the transfer length method (TLM), (2) the contact chain method, (3) the Kelvin method, and (4) the four point probe method, we have designed multiple testing devices to characterize the resistances of CNT-forest-based devices. Experimental results show that devices based on stripe-shaped CNT forests 100 {mu}m in height and 100 {mu}m in width have a sheet resistance of approximately 100{Omega}/{open_square}. The corresponding specific contact resistance to the molybdenum layer is roughly 5 x 10{sup 4} {Omega} {mu}m{sup 2}. Consistency of the results from the four different methods validates the study. After two months of storage of the CNT forest samples in open air, less than 0.9% deviations in the resistance values were observed. We further demonstrated one application of CNT forests as an NH{sub 3} gas sensor and measured 0.5 ppm of sensing resolution with a detection response time of 1 min.

Systemic contact dermatitis after oral exposure to nickel

DEFF Research Database (Denmark)

Jensen, Christian Stab; Menné, Torkil; Johansen, Jeanne Duus

2006-01-01

Systemic contact dermatitis can be elicited experimentally in nickel-sensitive individuals by oral nickel exposure. A crucial point interpreting such experiments has been the relevance of nickel exposure from drinking water and diet. The aim of this meta-analysis study on former nickel......-exposure investigations was to provide the best possible estimation of threshold values of nickel doses that may cause systemic contact dermatitis in nickel-sensitive patients. 17 relevant investigations were identified, and statistical analyses were performed in a stepwise procedure. 9 studies were included in the final...... of the doses that, theoretically, would cause systemic contact dermatitis in exposed nickel-sensitive patients. The results from the 2 most sensitive groups show that 1% of these individuals may react with systemic contact dermatitis at normal daily nickel exposure from drinking water and diet, i.e. 0...

Copolymers for soft hydrophilic contact lenses: development and investigations

International Nuclear Information System (INIS)

Schwach, G.W.

1978-05-01

Low esters of methacrylic acid which may be polymerized by different methods are used predominantly for producing soft hydrophilic contact lenses. Compounds of the vinyl-type often are added to improve the optical and mechanical qualities. Composition as well as possibilities of polymerization by irradiation were tested so long until copolymers were found which finally allowed the production of soft hydrophilic contact lenses. Swelling characteristics and permeability of the different elastomeres are to be investigated in order to guarantee sufficient compatibility of contact lenses. Contamination of the lens materials by microorganisms is also a point of special interest. The effects on the hydrophilic contact lens-copolymers by different substances used for cleaning and storage solutions have been investigated as well. (author)

Analysis of Tire Contact Parameters Using Visual Processing

Directory of Open Access Journals (Sweden)

Valentin Ivanov

2010-01-01

The first part of this paper presents the results of experimental estimation of the contact patch area depending on the normal wheel load and inflation pressure for different car tires. The data were obtained for test bench conditions on the basis of the visual processing of tread footprint. Further, the contact length in the cohesion area during wheel rolling for single points on the tire profile has been chosen as a benchmark criterion. This paper has analyzed the influence of the wheel normal load and tire inflation pressure on the contact length with small rolling velocities. The results of the investigations are given for winter and racing tires with different grades of wear.

Microbial analysis and survey test of gamma-irradiated freeze-dried fruits for patient's food

International Nuclear Information System (INIS)

Park, Jae-Nam; Sung, Nak-Yun; Byun, Eui-Hong; Byun, Eui-Baek; Song, Beom-Seok; Kim, Jae-Hun; Lee, Kyung-A; Son, Eun-Joo; Lyu, Eun-Soon

2015-01-01

This study examined the microbiological and organoleptic qualities of gamma-irradiated freeze-dried apples, pears, strawberries, pineapples, and grapes, and evaluated the organoleptic acceptability of the sterilized freeze-dried fruits for hospitalized patients. The freeze-dried fruits were gamma-irradiated at 0, 1, 2, 3, 4, 5, 10, 12, and 15 kGy, and their quality was evaluated. Microorganisms were not detected in apples after 1 kGy, in strawberries and pears after 4 kGy, in pineapples after 5 kGy, and in grapes after 12 kGy of gamma irradiation. The overall acceptance score, of the irradiated freeze-dried fruits on a 7-point scale at the sterilization doses was 5.5, 4.2, 4.0, 4.1, and 5.1 points for apples, strawberries, pears, pineapples, and grapes, respectively. The sensory survey of the hospitalized cancer patients (N=102) resulted in scores of 3.8, 3.7, 3.9, 3.9, and 3.7 on a 5-point scale for the gamma-irradiated freeze-dried apples, strawberries, pears, pineapples, and grapes, respectively. The results suggest that freeze-dried fruits can be sterilized with a dose of 5 kGy, except for grapes, which require a dose of 12 kGy, and that the organoleptic quality of the fruits is acceptable to immuno-compromised patients. However, to clarify the microbiological quality and safety of freeze-dried fruits should be verified by plating for both aerobic and anaerobic microorganisms. - Highlights: • Dried fruits can be sterilized with a dose of 12 kGy. • Sensory survey of the hospitalized cancer patients (N=102). • Sensory quality of dried fruits is acceptable to cancer patients

Frictional Compliant Haptic Contact and Deformation of Soft Objects

Directory of Open Access Journals (Sweden)

Naci Zafer

2016-05-01

Full Text Available This paper is concerned with compliant haptic contact and deformation of soft objects. A human soft fingertip model is considered to act as the haptic interface and is brought into contact with and deforms a discrete surface. A nonlinear constitutive law is developed in predicting normal forces and, for the haptic display of surface texture, motions along the surface are also resisted at various rates by accounting for dynamic Lund-Grenoble (LuGre frictional forces. For the soft fingertip to apply forces over an area larger than a point, normal and frictional forces are distributed around the soft fingertip contact location on the deforming surface. The distribution is realized based on a kernel smoothing function and by a nonlinear spring-damper net around the contact point. Experiments conducted demonstrate the accuracy and effectiveness of our approach in real-time haptic rendering of a kidney surface. The resistive (interaction forces are applied at the user fingertip bone edge. A 3-DoF parallel robotic manipulator equipped with a constraint based controller is used for the implementation. By rendering forces both in lateral and normal directions, the designed haptic interface system allows the user to realistically feel both the geometrical and mechanical (nonlinear properties of the deforming kidney.

Existence and uniqueness for a two-point interface boundary value problem

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Rakhim Aitbayev

2013-10-01

Full Text Available We obtain sufficient conditions, easily verifiable, for the existence and uniqueness of piecewise smooth solutions of a linear two-point boundary-value problem with general interface conditions. The coefficients of the differential equation may have jump discontinuities at the interface point. As an example, the conditions obtained are applied to a problem with typical interface such as perfect contact, non-perfect contact, and flux jump conditions.

Application of High Power Ultrasound in Drying of Fruits and Vegetables

Directory of Open Access Journals (Sweden)

Werner, Z.

2010-04-01

deteriorating alterations and nutritive loss of compounds in fruits and vegetables.In this paper, the basic theory of ultrasound has been described. In the figures, the range of sound by frequency is described, as is the amplitude of ultrasound and its effect on the material also l, the wavelength and attenuation coefficient have been explained. The most common usage of power ultrasound as probe type of high intensity ultrasound set system with piezoelectric transducer have been introduced as a system for ultrasound drying. When the ultrasound wave passes through material the basic effect occurs. It is called cavitation and is divided generally in two types: stable and transient cavitation. Also, when imploding cavitation bubble causes elevated temperatures and pressures several chemical reactions can happen. In the figure one can see the visualisation of sonochemical reactions that occur around the decomposed bubble. Several reactions of decomposition, polymerisations, formation of aggregates, breaking of aggregates, bonding,breaking of bonds, formation of radicals, hydroxyl radicals etc. The main aim of this paper was to introduce the new non-thermal pre-treatment or direct treatment of ultrasound probe, or set of probes in the drying of vegetables and fruits. The basic target of the paper was to improve the knowledge of experts in the food industry and technologists in the chemical and other industries to learn of the possibility of implementing new techniques in their facilities. One can observe the modern scheme of the system for drying of materials with direct contact and also the example of the ultrasound treatment of fruits, water diffusivity in fruit and total processing time of applying ultrasound. The most important thing is to conduct the drying process in the best way to reduce treatment time, and to optimize the system. The most commonly used mathematical models for determination of drying kinetics have been pointed out. The lack of information is about energy

Drying of α-amylase by spray drying and freeze-drying - a comparative study

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S. S. de Jesus

2014-09-01

Full Text Available This study is aimed at comparing two traditional methods of drying of enzymes and at verifying the efficiency of each one and their advantages and disadvantages. The experiments were performed with a laboratory spray dryer and freeze-dryer using α-amylase as the model enzyme. An experimental design in star revealed that spray drying is mainly influenced by the inlet air temperature and feed flow rate, which were considered to be the main factors influencing the enzymatic activity and water activity; the long period of material exposure to high temperatures causes a partial activity loss. In the experiments of freeze drying, three methods of freezing were used (freezer, acetone and dry ice, and liquid nitrogen and samples subsequently freeze-dried for times ranging between 0-24 hours. The product obtained from the two techniques showed high enzymatic activity and low water activity. For the drying of heat-resistant enzymes, in which the product to be obtained does not have high added value, spray drying may be more economically viable because, in the freeze drying process, the process time can be considered as a limiting factor when choosing a technique.

Trehalose and sorbitol alter the kinetic pattern of inactivation of glutamate dehydrogenase during drying in levitated microdroplets.

Science.gov (United States)

Lorenzen, Elke; Lee, Geoffrey

2013-12-01

A single-droplet acoustic levitator was used to determine the drying rate and the kinetics of inactivation of glutamate dehydrogenase in the presence of added trehalose or sorbitol. The solution was also spray dried under the same process condition of drying gas temperature on a bench-top machine. Both trehalose and sorbitol delay the point of onset of enzyme inactivation which lies after the critical point of drying. Both carbohydrates also reduce the apparent rate constant of inactivation calculated during the subsequent inactivation phase. The carbohydrates stabilise, therefore, the enzyme during droplet drying and particle formation mainly during the falling rate drying period. There is no difference between the stabilising effects of the two carbohydrates when examined as levitated single droplets. This suggests the importance of water replacement as a stabilising mechanism in the levitated droplets/particles. On spray drying, the trehalose stabilises the enzyme better than does the sorbitol at a drying gas (outlet) temperature of 60°C. This suggests glass formation with the trehalose but not the sorbitol during the very rapid drying process of small-atomised droplets in the spray dryer. © 2013 Wiley Periodicals, Inc. and the American Pharmacists Association.

Occupational contact urticaria and protein contact dermatitis.

Science.gov (United States)

Doutre, Marie-Sylvie

2005-01-01

Irritant dermatitis and eczema are the most prevalent occupational skin diseases. Less common are immediate contact reactions such as contact urticaria and protein contact dermatitis. Occupational contact urticaria can be subdivided into two categories, immunological and non immunological. However, some agents can induce these two types of reactions. Contact urticaria to natural rubber latex is particularly frequent among health care personnel, but contact urticaria to a wide variety of other substances occurs in many other occupations. Among those at risk are cooks, bakers, butchers, restaurant personnel, veterinarians, hairdressers, florists, gardeners, and forestry workers. Protein contact dermatitis in some of these occupations is caused principally by proteins of animal or plant origin, especially among individuals with a history of atopic dermatitis. Diagnosis requires careful interrogation, clinical examination and skin tests (open tests and prick tests with immediate lecture) to identify a particular contact allergen.

Supercurrent through a spin-split quasi-ballistic point contact in an InAs nanowire

DEFF Research Database (Denmark)

Saldaña, J. C. Estrada; Žitko, R.; Cleuziou, J. P.

2018-01-01

We study the superconducting proximity effect in an InAs nanowire contacted by Ta-based superconducting electrodes. Using local bottom gates, we control the potential landscape along the nanowire, tuning its conductance to a quasi-ballistic regime. At high magnetic field ($B$), we observe...

Computational Contact Mechanics Geometrically Exact Theory for Arbitrary Shaped Bodies

CERN Document Server

Konyukhov, Alexander

2013-01-01

This book contains a systematical analysis of geometrical situations  leading to  contact pairs -- point-to-surface, surface-to-surface, point-to-curve, curve-to-curve and curve-to-surface.  Each contact pair  is inherited with a special coordinate system based on its geometrical properties such as a Gaussian surface coordinate system or a Serret-Frenet curve coordinate system.  The formulation in a covariant form allows in a straightforward fashion to consider various constitutive relations for a  certain pair such as anisotropy for both frictional and structural parts. Then standard methods well known in computational contact mechanics such as penalty, Lagrange multiplier methods, combination of both and others  are formulated in these coordinate systems. Such formulations require then the powerful apparatus of differential geometry of surfaces and curves as well as of convex analysis. The final goals of such transformations are  then ready-for-implementation numerical algorithms within the finite e...

Three-dimensional frictionless contact between layered elastic bodies and incorporating sharp edges

Science.gov (United States)

Tordesillas, A. A.; Hill, J. M.

1991-07-01

The roller coating system used in industry to apply paint to sheet metal involves two contacting rolling cylinders, one of which is rubber covered and through which the sheet metal travels. Of particular concern in the industry is the effect of high pressures upon the flow of paint at the ends of the rollers. In an elastohydrodynamic-lubrication analysis of the paint flow, it is the corresponding “dry-contact pressure” which is of major concern. In this paper we present a numerical solution to the three-dimensional contact problem for both smooth profiled layered bodies and those which involve sharp edges but in both cases ignoring the effects of curvature. The procedure adopted is based on one previously developed by a number of authors for homogeneous bodies. An understanding of the consequences of changing the operating variables is of prime importance in an industrial scenario. The numerical scheme described here provides complete measurements of both the deformation and the contact pressure distribution for given operating variables, which are the elastic properties and dimensions of both rolls and the total applied force.

Correlations between deformations, surface state and leak rate in metal to metal contact; Correlations entre deformations, etat de surface et debit de fuite au contact metal-metal

Energy Technology Data Exchange (ETDEWEB)

Armand, G; Lapujoulade, J; Paigne, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1963-07-01

The study of metal to metal contact from the stand-point of the leak rate has been carried on a copper ring located between two hard-steel flanges. The analysis of the results confirms the hysteresis phenomenon already seen. Some curves (leak rate versus force and leak rate versus true deformation) in semi-logarithmic coordinates are straight lines. Likewise some curves (electrical contact resistance versus force) in bi-logarithmic coordinates are straight lines. All these results can be understood by looking at the conductance introduced by the deformations of the micro-geometry of the surfaces in contact. Some tests carried out in rising the temperature confirm these hypothesis. (authors) [French] L'etude du contact metal-metal du point de vue debit de fuite a ete poursuivie en utilisant un anneau de cuivre place entre brides d'acier dur. L'analyse des resultats confirme le phenomene d'hysteresis deja constate, montre l'influence de l'etat de surface des brides et du joint. Certaines courbes (debit de fuite/force et debit de fuite/deformation rationnelle), en coordonnees semi-logarithmiques, sont des droites. De meme, certaines courbes (resistance de contact/force) en coordonnees bi-logarithmiques, sont des droites. Ces resultats s'interpretent en considerant la conductance produite par la deformation des microgeometries des surfaces en contact. Quelques essais d'elevation de temperature confirment ces resultats. (auteurs)

Fabrication of robot head module using contact resistance force sensor for human robot interaction and its evaluation

Energy Technology Data Exchange (ETDEWEB)

Kim, Dong Ki; Kim, Jong Ho [Korea Reserch Institute of Standards and Science, Daejeon (Korea, Republic of); Kwon, Hyun Joon [Univ. of Maryland, Maryland (United States); Kwon, Young Ha [Kyung Hee Univ., Gyunggi Do (Korea, Republic of)

2012-10-15

This paper presents a design of a robot head module with touch sensing algorithms that can simultaneously detect contact force and location. The module is constructed with a hemisphere and three sensor units that are fabricated using contact resistance force sensors. The surface part is designed with the hemisphere that measures 300 mm in diameter and 150 mm in height. Placed at the bottom of the robot head module are three sensor units fabricated using a simple screen printing technique. The contact force and the location of the model are evaluated through the calibration setup. The experiment showed that the calculated contact positions almost coincided with the applied load points as the contact location changed with a location error of about {+-}8.67 mm. The force responses of the module were evaluated at two points under loading and unloading conditions from 0 N to 5 N. The robot head module showed almost the same force responses at the two points.

The Josephson effect in atomic contacts

International Nuclear Information System (INIS)

Chauvin, M.

2005-11-01

The Josephson effect appears when a weak-link establishes phase coherence between two superconductors. A unifying theory of this effect emerged in the 90's within the framework of mesoscopic physics. Based on two cornerstone concepts, conduction channels and Andreev reflection, it predicts the current-phase relation for the most basic weak-link: a single conduction channel of arbitrary transmission. This thesis illustrates this mesoscopic point of view with experiments on superconducting atomic size contacts. In particular, we have focused on the supercurrent peak around zero voltage, put into evidence the ac Josephson currents in a contact under constant bias voltage (Shapiro resonances and photon assisted multiple Andreev reflections), and performed direct measurements of the current-phase relation. (author)

PREFACE: Non-contact AFM Non-contact AFM

Science.gov (United States)

Giessibl, Franz J.; Morita, Seizo

2012-02-01

This special issue is focussed on high resolution non-contact atomic force microscopy (AFM). Non-contact atomic force microscopy was established approximately 15 years ago as a tool to image conducting and insulating surfaces with atomic resolution. Since 1998, an annual international conference has taken place, and although the proceedings of these conferences are a useful source of information, several key developments warrant devoting a special issue to this subject. In the theoretic field, the possibility of supplementing established techniques such as scanning tunneling microscopy (STM) and Kelvin probe microscopy with atomically resolved force micrsoscopy poses many challenges in the calculation of contrast and contrast reversal. The surface science of insulators, self-assembled monolayers and adsorbates on insulators is a fruitful field for the application of non-contact AFM: several articles in this issue are devoted to these subjects. Atomic imaging and manipulation have been pioneered using STM, but because AFM allows the measurement of forces, AFM has had a profound impact in this field as well. Three-dimensional force spectroscopy has allowed many important insights into surface science. In this issue a combined 3D tunneling and force microscopy is introduced. Non-contact AFM typically uses frequency modulation to measure force gradients and was initially used mainly in a vacuum. As can be seen in this issue, frequency modulation is now also used in ambient conditions, allowing better spatial and force resolution. We thank all of the contributors for their time and efforts in making this special issue possible. We are also very grateful to the staff of IOP Publishing for handling the administrative aspects and for steering the refereeing process. Non-contact AFM contents Relation between the chemical force and the tunnelling current in atomic point contacts: a simple model Pavel Jelínek, Martin Ondrácek and Fernando Flores Theoretical simulation of

Effect of Drying Pretreatment on the Acetylation of Nanofibrillated Cellulose

Directory of Open Access Journals (Sweden)

Vesna Zepič

2015-10-01

Full Text Available The aim of this study was to evaluate the effect of different morphologies of solvent-exchanged (NFCSE, spray-dried (NFCSD, and freeze-dried (NFCFD nano-fibrillated cellulose on the susceptibility to surface modification with the acetic anhydride/pyridine system. The degree of substitution (DS, morphology, degree of crystallinity (Icr, hydrophobicity, and thermal stability of acetylated products were examined. Acetylated NFCSD and NFCFD had higher DS than acetylated NFCSE, suggesting that drying pre-treatment increased the susceptibility of NFC for acetylation. The morphology of acetylated NFCFD and NFCSD with higher DS was different from unmodified samples, while that of NFCSE was not affected by acetylation. Microspheres of acetylated NFCSD started to dissolve when the highest DS was reached. As opposed to unmodified NFCFD, the nanofibrillar units of acetylated NFCFD became individualised at lower DS. Acetylated samples had lower Icr than the unmodified samples. A significant increase in the contact angle was observed at higher DS of acetylated NFC samples. Acetylation markedly elevated the thermal stability of the acetylated NFC samples.

Effectiveness and relevant factors of 2% rebamipide ophthalmic suspension treatment in dry eye.

Science.gov (United States)

Ueda, Kaori; Matsumiya, Wataru; Otsuka, Keiko; Maeda, Yoshifumi; Nagai, Takayuki; Nakamura, Makoto

2015-06-06

Rebamipide with mucin secretagogue activity was recently approved for the treatment of dry eye. The efficacy and safety in the treatment of rebamipide were shown in two pivotal clinical trials. It was the aim of this study to evaluate the effect of 2% rebamipide ophthalmic suspension in patients with dry eye and analyze relevant factors for favorable effects of rebamipide in clinical practice. This was a retrospective cohort study of 48 eyes from 24 patients with dry eye treated with 2% rebamipide ophthalmic suspension. Dry eye-related symptom score, tear film break-up time (TBUT), fluorescein ocular surface staining score (FOS) and the Schirmer test were used to collect the data from patients at baseline, and at 2, 4, 8, and 12 week visits. To determine the relevant factors, multiple regression analyses were then performed. Mean dry eye-related symptom score showed a significant improvement from the baseline (14.5 points) at 2, 4, 8 and 12 weeks (9.80, 7.04, 7.04 and 7.83 points, corrected P value treatment. For ocular symptoms, three parameters (foreign body sensation, dry eye sensation and ocular discomfort) showed significant improvements at all visits. The multiple regression analyses showed that the fluorescein conjunctiva staining score was significantly correlated with the changes of dry eye-related symptom score at 12 weeks (P value = 0.017) and dry eye-related symptom score was significantly correlated with independent variables for the changes of FOS at 12 weeks (P value = 0.0097). Two percent rebamipide ophthalmic suspension was an effective therapy for dry eye patients. Moreover the fluorescein conjunctiva staining score and dry eye-related symptom score might be good relevant factors for favorable effects of rebamipide.

Refinements to calandria tube - liquid injection nozzle (CT-LIN) contact assessments

International Nuclear Information System (INIS)

Sedran, P.J.

2012-01-01

In recent years, the issue of CT-LIN contact, which first gained attention in 1989, has been addressed through CT-LIN gap measurements, followed by analytical predictions of time-to-contact. CT-LIN time-to-contact predictions have been preformed independently by CPUS Limited for Point Lepreau and Gentilly-2 and by AECL Sheridan Park (now Candu Energy Inc.) for Bruce Power and Gentilly-2. Both companies used the CDEPTH code in combination with CT-LIN gap measurements. Subsequent to the assessments for Point Lepreau and Gentilly-2, a recommended approach for future assessments was presented at the 2008 CANDU maintenance conference. Since that time, a number of refinements to the overall strategy for predicting CT-LIN time-to-contact have been developed and are outlined in this paper. The refinements include: 1. The use of ultrasonic LIN elevation measurements to confirm LIN creep sag behaviour 2. The development of a non-linear empirical CT Creep Sag Model 3. The development of a rationale for discrepancies observed in repeated optical CT-LIN gap measurements and a discussion of alternative CT-LIN gap measurements With these refinements, more accurate CT-LIN time-to-contact predictions can be obtained. For stations that plan to refurbish by 210,000 EFPH, the improvement in time-to-contact predictions resulting from the fore mentioned refinements will not be of any real benefit.. However, for stations that are planning life extensions in order to operate beyond 210,000 EFPH, CT-LIN contact will be an issue. For these stations, improvements in CT-LIN contact time predictions would be beneficial. This paper presents a summary of the proposed refinements and demonstrates how they would impact CT-LIN time-to-contact predictions. (author)

Effect of paddy drying depth using open-sun drying on drying time ...

African Journals Online (AJOL)

The smallholder rice farmers in the Uganda dry their paddy using open-sun drying method. In most cases the paddy is badly dried and has very high fissure levels. Such paddy on milling contributes to low levels of mill recovery and whole grain in the milled rice. This study was therefore done to find a recommendable ...

A review on the effects of different parameters on contact heat transfer

Science.gov (United States)

Abdollahi, H.; Shahraki, S.; Motahari-Nezhad, M.

2017-07-01

In this paper, a complete literature review for thermal contact between fixed and periodic contacting surfaces and also thermal contact between exhaust valve and its seat in internal combustion engines is presented. Furthermore, the effects of some parameters such as contact pressure, contact frequency, the contacting surfaces topography and roughness, curvature radius of surfaces, loading-unloading cycles, gas gap conductance and properties, interface interstitial material properties, surfaces coatings and surfaces temperature on thermal contact conductance are investigated according to the papers presented in this field. The reviewed papers and studies included theoretical/ analytical/experimental and numerical studies on thermal contact conductance. In studying the thermal contact between exhaust valve and its seat, most of the experimental studies include two axial rods as the exhaust valve, and seat and the one ends of both rods are considered at constant and different temperatures. In the experimental methods, the temperatures of multi-points on rods are measured in different conditions, and thermal contact conductance is estimated using them.

Experimental Tests on Bending Behavior of Profiled Steel Sheeting Dry Board Composite Floor with Geopolymer Concrete Infill

Directory of Open Access Journals (Sweden)

Mohd Isa Jaffar

Full Text Available Abstract Profiled Steel Sheet Dry Board (PSSDB system is a lightweight composite structure comprises Profiled Steel Sheeting and Dry Board connected by self-drilling and self-tapping screws. This study introduced geopolymer concrete, an eco-friendly material without cement content as an infill material in the PSSDB floor system to highlight its effect onto the PSSDB (with full and half-size dry boards floor system's stiffness and strength. Experimental tests on various full scale PSSDB floor specimens were conducted under uniformly distributed transverse loads. Results illustrate that the rigidity of the panel with geopolymer concrete infill with half-size dry board (HBGPC increases by 43% relative to that of the panel with normal concrete infill with full-size dry board (FBNC. The developed finite-element modeling (FEM successfully predicts the behavior of FBGPC model with 94.8% accuracy. Geopolymer concrete infill and dry board size influence the strength panel, infill contact stiffness, and mid-span deflection of the profiled steel sheeting/dry board (PSSDB flooring system.

Transport and solubility of Hetero-disperse dry deposition particulate matter subject to urban source area rainfall-runoff processes

Science.gov (United States)

Ying, G.; Sansalone, J.

2010-03-01

SummaryWith respect to hydrologic processes, the impervious pavement interface significantly alters relationships between rainfall and runoff. Commensurate with alteration of hydrologic processes the pavement also facilitates transport and solubility of dry deposition particulate matter (PM) in runoff. This study examines dry depositional flux rates, granulometric modification by runoff transport, as well as generation of total dissolved solids (TDS), alkalinity and conductivity in source area runoff resulting from PM solubility. PM is collected from a paved source area transportation corridor (I-10) in Baton Rouge, Louisiana encompassing 17 dry deposition and 8 runoff events. The mass-based granulometric particle size distribution (PSD) is measured and modeled through a cumulative gamma function, while PM surface area distributions across the PSD follow a log-normal distribution. Dry deposition flux rates are modeled as separate first-order exponential functions of previous dry hours (PDH) for PM and suspended, settleable and sediment fractions. When trans-located from dry deposition into runoff, PSDs are modified, with a d50m decreasing from 331 to 14 μm after transport and 60 min of settling. Solubility experiments as a function of pH, contact time and particle size using source area rainfall generate constitutive models to reproduce pH, alkalinity, TDS and alkalinity for historical events. Equilibrium pH, alkalinity and TDS are strongly influenced by particle size and contact times. The constitutive leaching models are combined with measured PSDs from a series of rainfall-runoff events to demonstrate that the model results replicate alkalinity and TDS in runoff from the subject watershed. Results illustrate the granulometry of dry deposition PM, modification of PSDs along the drainage pathway, and the role of PM solubility for generation of TDS, alkalinity and conductivity in urban source area rainfall-runoff.

Three-way flexible cantilever probes for static contact

DEFF Research Database (Denmark)

Wang, Fei; Petersen, Dirch Hjorth; Jensen, Helle Vendelbo

2011-01-01

In micro four-point probe measurements, three-way flexible L-shaped cantilever probes show significant advantages over conventional straight cantilever probes. The L-shaped cantilever allows static contact to the sample surface which reduces the frictional wear of the cantilever tips. We analyze...

Design of solar drying-plant for bulk material drying

Directory of Open Access Journals (Sweden)

Peter Horbaj

2008-11-01

Full Text Available A generally well-known high energy requirement for technological processes of drying and the fact that the world’s supplyof the conventional energy sources has considerably decreased are the decisive factors forcing us to look for some new, if possible,renewable energy sources for this process by emphasising their environmental reliability. One of the possibilities how to replace, atleast partly, the conventional energy sources – heat in a drying process is solar energy.Air-drying of bulk materials usually has a series of disadvantages such as time expenditure, drying defects in the bulk materialand inadequate final moisture content. A method that obviates or reduces the disadvantages of air-drying and, at the same time, reducesthe costs of kiln drying, is drying with solar heat. Solar energy can replace a large part of this depletable energy since solar energy cansupply heat at the temperatures most often used to dry bulk material. Solar drying-plant offer an attractive solution.

Onset of frictional sliding of rubber-glass contact under dry and lubricated conditions.

Science.gov (United States)

Tuononen, Ari J

2016-06-13

Rubber friction is critical in many applications ranging from automotive tyres to cylinder seals. The process where a static rubber sample transitions to frictional sliding is particularly poorly understood. The experimental and simulation results in this paper show a completely different detachment process from the static situation to sliding motion under dry and lubricated conditions. The results underline the contribution of the rubber bulk properties to the static friction force. In fact, simple Amontons' law is sufficient as a local friction law to produce the correct detachment pattern when the rubber material and loading conditions are modelled properly. Simulations show that micro-sliding due to vertical loading can release initial shear stresses and lead to a high static/dynamic friction coefficient ratio, as observed in the measurements.

The contact area and sliding friction in nanotribological systems

International Nuclear Information System (INIS)

Wolloch, M.

2014-01-01

� cut to the vacuum, resulting in surface atoms of finite size. In our proposed method the parameter ρ cut is calculated by allowing contact only after the 'jump to contact', or a similar discontinuity, has taken place, which can be clearly observed in our DFT simulations. We demonstrate the method by lowering a ten atom tungsten pyramid, which serves as a model of an AFM tip, onto a smooth surface. Two systems are examined, the first being moiré graphene on iridium (111), the second a clean copper (111) surface. Although the surfaces are very different, a similiar cutoff parameter ρ cut of about 5 x 10 -2 electrons per Å 3 is computed in both cases. The calculated area of contact is found to increase linearly with lowering of the tip support while increasing exponentially with the true relaxed distance between the tip apex atom and the surface atom below it. Although there exist a number of models that tackle the problem of calculating friction forces on the atomic level, providing a completely parameter-free approach remains a challenge. To examine the direction dependence of dry sliding friction we developed a quasi-static grid method with a mechanism to allow dissipative sliding, which relies on atomic relaxations. We define two different ways of calculating the mean nanofriction force, both leading to an exponential friction-versus-load behavior for all sliding directions. Since our approach does not impose any limits on lengths and directions of the sliding paths, we investigate arbitrary sliding directions for several metal interfaces and detect two periodic paths which form the upper and lower bound of nanofriction in all cases. For long aperiodic paths the friction force convergences to a value in between these limits. For low loads we retrieve the Derjaguin generalization of the Amontons-Coulomb kinetic friction law which appears to be valid all the way down to the nanoscale. We observe a non-vanishing Derjaguin-offset even for atomically flat

Rubber contact mechanics: adhesion, friction and leakage of seals.

Science.gov (United States)

Tiwari, A; Dorogin, L; Tahir, M; Stöckelhuber, K W; Heinrich, G; Espallargas, N; Persson, B N J

2017-12-13

We study the adhesion, friction and leak rate of seals for four different elastomers: Acrylonitrile Butadiene Rubber (NBR), Ethylene Propylene Diene (EPDM), Polyepichlorohydrin (GECO) and Polydimethylsiloxane (PDMS). Adhesion between smooth clean glass balls and all the elastomers is studied both in the dry state and in water. In water, adhesion is observed for the NBR and PDMS elastomers, but not for the EPDM and GECO elastomers, which we attribute to the differences in surface energy and dewetting. The leakage of water is studied with rubber square-ring seals squeezed against sandblasted glass surfaces. Here we observe a strongly non-linear dependence of the leak rate on the water pressure ΔP for the elastomers exhibiting adhesion in water, while the leak rate depends nearly linearly on ΔP for the other elastomers. We attribute the non-linearity to some adhesion-related phenomena, such as dewetting or the (time-dependent) formation of gas bubbles, which blocks fluid flow channels. Finally, rubber friction is studied at low sliding speeds using smooth glass and sandblasted glass as substrates, both in the dry state and in water. The measured friction coefficients are compared to theory, and the origin of the frictional shear stress acting in the area of real contact is discussed. The NBR rubber, which exhibits the strongest adhesion both in the dry state and in water, also shows the highest friction both in the dry state and in water.

Corrosion failure analysis of hearing aid battery-spring contacts

DEFF Research Database (Denmark)

Gudla, Visweswara Chakravarthy; Ambat, Rajan

2017-01-01

the susceptibility of these systems to galvanic corrosion. In this study, traditional behind the ear (BTE) hearing aid systems, which failed during service were analysed. Failure analysis was performed on the dome type battery-spring contact systems. The morphology of the contact areas was observed using scanning......Reliability of low power electrical contacts such as those in hearing aid battery-spring systems is a very critical aspect for the overall performance of the device. These systems are exposed to certain harsh environments like high humidity and elevated temperatures, and often in combination...... electron microscopy, and the compositional analysis of the corrosion products and contaminants was performed using energy dispersive X-ray spectroscopy. Wear track morphology was observed on the contact points, and the top coating on the dome was worn out exposing the substrate spring material...

Heat transfer modelling in a spent-fuel dry storage system

International Nuclear Information System (INIS)

Ritz, J.B.; Le Bonhomme, S.

2001-01-01

The purpose of this paper is to present a numerical modelling of heat transfers in a Spent-Fuel horizontal dry storage. The horizontal dry storage is an interesting issue to momentary store spent fuel containers before the final storage. From a thermal point of view, the cooling of spent fuel container by natural convection is a suitable and inexpensive process but it necessitates to well define the dimensions of the concept due to the difficulty to control the thermal environment. (author)

Effects of Evaporation/Condensation on Spreading and Contact Angle of a Volatile Liquid Drop

Science.gov (United States)

Zhang, Nengli; Chao, David F.; Singh, Bhim S. (Technical Monitor)

2000-01-01

Effects of evaporation/condensation on spreading and contact angle were experimentally studied. A sessile drop of R-113 was tested at different vapor environments to determine the effects of evaporation/condensation on the evolution of contact diameter and contact angle of the drop. Condensation on the drop surface occurs at both the saturated and a nonsaturated vapor environments and promotes the spreading. When the drop is placed in the saturated vapor environment it tends to completely wetting and spreads rapidly. In a nonsaturated vapor environment, the evolution of the sessile drop is divided three stages: condensation-spreading stage, evaporation-retracting stage and rapid contracting stage. In the first stage the drop behaves as in the saturated environment. In the evaporation -retracting stage, the competition between spreading and evaporation of the drop determines the evolution characteristics of the contact diameter and the contact angle. A lower evaporation rate struggles against the spreading power to turn the drop from spreading to retracting with a continuous increase of the contact angle. The drop placed in open air has a much higher evaporation rate. The strong evaporation suppresses the spreading and accelerates the retraction of the drop with a linear decrease of the contact diameter. The contraction of the evaporating drops is gradually accelerated when the contact diameter decreases to 3 min and less till drying up, though the evaporation rate is gradually slowing down.

[Ocular and visual alterations in computer workers contact lens wearers: scoping review].

Science.gov (United States)

Tauste Francés, Ana; Ronda-Pérez, Elena; Seguí Crespo, María del Mar

2014-01-01

The high number of computer workers wearing contact lenses raises the question whether the sum of these two risk factors for eye health may cause a worsening of Computer Vision Syndrome. The aim of this review is to synthesize the knowledge about ocular and visual alterations related with computer use in contact lens wearers. International review of scientific papers (2003-2013) in Spanish and English, using Scoping Review method, in Medline through PubMed and in Scopus. The initial search provided 114 references, after applying inclusion/exclusion criteria six of them were included. All of them reveal that symptoms when using computer are more prevalent in contact lens wearers, with values of symptoms presentation prevalence ranging from 95.0% to 16.9% in wearers and from 57.5% to 9.9% in non-wearers, and four times more likely to develop dry eye [OR: 4.07 (95% CI: 3.52 to 4.71)]. Computer workers suffer more ocular and visual disturbances if they also are contact lens users, but studies are few and non conclusive. Likewise, further research regarding contact lens type and their conditions of use, both in symptoms and tear quality and ocular surface are needed. Silicone hydrogel lenses are associated with more comfort.

Direct observation of contact and channel resistance in pentacene four-terminal thin-film transistor patterned by laser ablation method

International Nuclear Information System (INIS)

Yagi, Iwao; Tsukagoshi, Kazuhito; Aoyagi, Yoshinobu

2004-01-01

We established a dry-etching patterning process for the channel formation of pentacene thin-film transistor, and fabricated a four-terminal device equipped with a gate electrode. The four-terminal device enabled us to divide two-terminal source-drain resistance into two components of contact resistance and pentacene channel resistance. We obtained direct evidence of a gate-voltagedependent contact resistance change: the gate-induced charge significantly reduced the contact resistance and increased source-drain current. Furthermore, the temperature dependence of the device clearly indicated that the contact resistance was much higher than the channel resistance and was dominated in the two-terminal total resistance of the device below 120 K. An observed activation energy of 80 meV for contact resistance was higher than that of 42 meV for pentacene channel resistance

Influence of Aggregate Wettability with Different Lithology Aggregates on Concrete Drying Shrinkage

Directory of Open Access Journals (Sweden)

Yuanchen Guo

2015-01-01

Full Text Available The correlation of the wettability of different lithology aggregates and the drying shrinkage of concrete materials is studied, and some influential factors such as wettability and wetting angle are analyzed. A mercury porosimeter is used to measure the porosities of different lithology aggregates accurately, and the pore size ranges that significantly affect the drying shrinkage of different lithology aggregate concretes are confirmed. The pore distribution curve of the different coarse aggregates is also measured through a statistical method, and the contact angle of different coarse aggregates and concrete is calculated according to the linear fitting relationship. Research shows that concrete strength is determined by aggregate strength. Aggregate wettability is not directly correlated with concrete strength, but wettability significantly affects concrete drying shrinkage. In all types’ pores, the greatest impacts on wettability are capillary pores and gel pores, especially for the pores of the size locating 2.5–50 nm and 50–100 nm two ranges.

Use of a soft sensor for the fast estimation of dried cake resistance during a freeze-drying cycle.

Science.gov (United States)

Bosca, Serena; Barresi, Antonello A; Fissore, Davide

2013-07-15

This paper deals with the determination of dried cake resistance in a freeze-drying process using the Smart Soft Sensor, a process analytical technology recently proposed by the authors to monitor the primary drying stage of a freeze-drying process. This sensor uses the measurement of product temperature, a mathematical model of the process, and the Kalman filter algorithm to estimate the residual amount of ice in the vial as a function of time, as well as the coefficient of heat transfer between the shelf and the product and the resistance of the dried cake to vapor flow. It does not require expensive (additional) hardware in a freeze-dryer, provided that thermocouples are available. At first, the effect of the insertion of the thermocouple in a vial on the structure of the product is investigated by means of experimental tests, comparing both sublimation rate and cake structure in vials with and without thermocouple. This is required to assess that the temperature measured by the thermocouple is the same of the product in the non-monitored vials, at least in a non-GMP environment, or when controlled nucleation methods are used. Then, results about cake resistance obtained in an extended experimental campaign with aqueous solutions containing different excipients (sucrose, mannitol and polyvinylpyrrolidone), processed in various operating conditions, are presented, with the goal to point out the accuracy of the proposed methodology. Copyright © 2013 Elsevier B.V. All rights reserved.

An Investigation of the Relation Between Contact Thermometry and Dew-Point Temperature Realization

Science.gov (United States)

Benyon, R.; Böse, N.; Mitter, H.; Mutter, D.; Vicente, T.

2012-09-01

Precision optical dew-point hygrometers are the most commonly used transfer standards for the comparison of dew-point temperature realizations at National Metrology Institutes (NMIs) and for disseminating traceability to calibration laboratories. These instruments have been shown to be highly reproducible when properly used. In order to obtain the best performance, the resistance of the platinum resistance thermometer (PRT) embedded in the mirror is usually measured with an external, traceable resistance bridge or digital multimeter. The relation between the conventional calibration of miniature PRTs, prior to their assembly in the mirrors of state-of-the-art optical dew-point hygrometers and their subsequent calibration as dew-point temperature measurement devices, has been investigated. Standard humidity generators of three NMIs were used to calibrate hygrometers of different designs, covering the dew-point temperature range from -75 °C to + 95 °C. The results span more than a decade, during which time successive improvements and modifications were implemented by the manufacturer. The findings are presented and discussed in the context of enabling the optimum use of these transfer standards and as a basis for determining contributions to the uncertainty in their calibration.

A case of contact dermatitis to dimethylfumarate in shoes identified in Italy

Directory of Open Access Journals (Sweden)

Franca Davanzo

2010-12-01

Full Text Available The present paper describes a case of shoe contact dermatitis from DMF identified by the Poison Control Centre of Milan (PCCM, Italy, in 2009. A 35 year old woman was affected by irritant reactions while wearing shoes contaminated with DMF. Exposure to these shoes was limited to a 8 hour period and was not repeated. In the following days the patient suffered feet blistering and swelling limited to the area in contact with shoe vamp. Topical application of cortisone did not prevent development of bullous eczema. After 20 days from exposure, the lesions were healed but the skin remained red, dry and very sensitive. Chemical analyses of shoes quantified an average concentration of DMF of 383 mg/kg. The patient refused to be patch tested. The observation here reported confirm that DMF should be considered a possible causal agent in shoe contact dermatitis. Documentation of cases exposed to this chemical provide a relevant support to characterize clinical manifestations and to identifying contaminated articles.

Liquid-liquid contact in vapor explosion

International Nuclear Information System (INIS)

Segev, A.

1978-08-01

The contact of two liquid materials, one of which is at a temperature substantially above the boiling point of the other, can lead to fast energy conversion and a subsequent shock wave. This phenomenon is called a vapor explosion. One method of producing intimate, liquid-liquid contact (which is known to be a necessary condition for vapor explosion) is a shock tube configuration. Such experiments in which water was impacted upon molten aluminum showed that very high pressures, even larger than the thermodynamic critical pressure, could occur. The mechanism by which such sharp pressure pulses are generated is not yet clear. The report describes experiments in which cold liquids (Freon-11, Freon-22, water, or butanol) were impacted upon various hot materials

Points of Contact, Points of Distance

DEFF Research Database (Denmark)

Nielsen, Jakob Isak

2016-01-01

of co-production set-ups by discussing two recent cases that involve American co-production partners, namely HBO and Netflix. The article highlights tension and resistance at media systemic, organisational and narrative/aesthetic levels prohibiting or undermining the ‘transnational dialogues’ between DR...... and TV2 on one hand, and HBO and Netflix on the other....

Point-contact properties of cubic YbCu .sub.5./sub. prepared by melt spinning technique

Czech Academy of Sciences Publication Activity Database

Reiffers, M.; Idzikowski, B.; Ilkovič, S.; Zorkovská, A.; Šebek, Josef; Müller, K. H.

272-276, - (2004), s. 209-210 ISSN 0304-8853 Institutional research plan: CEZ:AV0Z1010914 Keywords : heavy-fermion * pont-contact * YbCu 5 Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.031, year: 2004

Molecular dynamics study of contact mechanics: contact area and interfacial separation from small to full contact

OpenAIRE

Yang, C.; Persson, B. N. J.

2007-01-01

We report a molecular dynamics study of the contact between a rigid solid with a randomly rough surface and an elastic block with a flat surface. We study the contact area and the interfacial separation from small contact (low load) to full contact (high load). For small load the contact area varies linearly with the load and the interfacial separation depends logarithmically on the load. For high load the contact area approaches to the nominal contact area (i.e., complete contact), and the i...

Optimal contact definition for reconstruction of Contact Maps

Directory of Open Access Journals (Sweden)

Stehr Henning

2010-05-01

Full Text Available Abstract Background Contact maps have been extensively used as a simplified representation of protein structures. They capture most important features of a protein's fold, being preferred by a number of researchers for the description and study of protein structures. Inspired by the model's simplicity many groups have dedicated a considerable amount of effort towards contact prediction as a proxy for protein structure prediction. However a contact map's biological interest is subject to the availability of reliable methods for the 3-dimensional reconstruction of the structure. Results We use an implementation of the well-known distance geometry protocol to build realistic protein 3-dimensional models from contact maps, performing an extensive exploration of many of the parameters involved in the reconstruction process. We try to address the questions: a to what accuracy does a contact map represent its corresponding 3D structure, b what is the best contact map representation with regard to reconstructability and c what is the effect of partial or inaccurate contact information on the 3D structure recovery. Our results suggest that contact maps derived from the application of a distance cutoff of 9 to 11Å around the Cβ atoms constitute the most accurate representation of the 3D structure. The reconstruction process does not provide a single solution to the problem but rather an ensemble of conformations that are within 2Å RMSD of the crystal structure and with lower values for the pairwise average ensemble RMSD. Interestingly it is still possible to recover a structure with partial contact information, although wrong contacts can lead to dramatic loss in reconstruction fidelity. Conclusions Thus contact maps represent a valid approximation to the structures with an accuracy comparable to that of experimental methods. The optimal contact definitions constitute key guidelines for methods based on contact maps such as structure prediction through