Science.gov

Sample records for reverse schreinemakers method

  1. A composite phase diagram of structure H hydrates using Schreinemakers' geometric approach

    USGS Publications Warehouse

    Mehta, A.P.; Makogon, T.Y.; Burruss, R.C.; Wendlandt, R.F.; Sloan, E.D.

    1996-01-01

    A composite phase diagram is presented for Structure H (sH) clathrate hydrates. In this work, we derived the reactions occurring among the various phases along each four-phase (Ice/Liquid water, liquid hydrocarbon, vapor, and hydrate) equilibrium line. A powerful method (though seldom used in chemical engineering) for multicomponent equilibria developed by Schreinemakers is applied to determine the relative location of all quadruple (four-phase) lines emanating from three quintuple (five-phase) points. Experimental evidence validating the approximate phase diagram is also provided. The use of Schreinemakers' rules for the development of the phase diagram is novel for hydrates, but these rules may be extended to resolve the phase space of other more complex systems commonly encountered in chemical engineering.

  2. [Historical survey of modern reversible contraceptive methods].

    PubMed

    Mbabajende, V

    1986-04-01

    were flexible and capable of returning to their original shape after insertion. The Lippes loop was the 1st highly successful IUD. Bioactive IUDs containing copper were developed in the 1970s. Research is underway to develop IUDs which will resist expulsion, reduce bleeding, be more appropriate for multiparas, and last longer. IUDs are used to treat intrauterine adhesions as well as for contraception. A gummy substance used to block the cervix was described in Egypt in 1850 BC. Japanese and Chinese prostitutes of antiquity placed oiled bamboo paper at the cervical opening for contraception. Diaphragms and cervical caps were developed in the 19th century in Germany. Large scale production became possible after 1880 with the development of better, more durable, and cheaper rubber. An Egyptian writing in 3500 BC began the study of spermicides. Numerous substances such as lemon juice and honey have been placed in the vagina to avoid pregnancy. Such substances are available to all women and some were reasonably effective. Current research is directed toward development of spermicides which will also prevent sexually transmitted diseases. The 1st condoms were made of animal skins by an English physician to prevent transmission of venereal diseases. Rubber condoms appeared in the early 20th century and are widely utilized in some family planning programs. Pregnancy vaccines and a reversible hormonal method for men are among methods under development. PMID:12268230

  3. Method for distinguishing multiple targets using time-reversal acoustics

    DOEpatents

    Berryman, James G.

    2004-06-29

    A method for distinguishing multiple targets using time-reversal acoustics. Time-reversal acoustics uses an iterative process to determine the optimum signal for locating a strongly reflecting target in a cluttered environment. An acoustic array sends a signal into a medium, and then receives the returned/reflected signal. This returned/reflected signal is then time-reversed and sent back into the medium again, and again, until the signal being sent and received is no longer changing. At that point, the array has isolated the largest eigenvalue/eigenvector combination and has effectively determined the location of a single target in the medium (the one that is most strongly reflecting). After the largest eigenvalue/eigenvector combination has been determined, to determine the location of other targets, instead of sending back the same signals, the method sends back these time reversed signals, but half of them will also be reversed in sign. There are various possibilities for choosing which half to do sign reversal. The most obvious choice is to reverse every other one in a linear array, or as in a checkerboard pattern in 2D. Then, a new send/receive, send-time reversed/receive iteration can proceed. Often, the first iteration in this sequence will be close to the desired signal from a second target. In some cases, orthogonalization procedures must be implemented to assure the returned signals are in fact orthogonal to the first eigenvector found.

  4. Acceleration of reverse analysis method using hyperbolic activation function

    NASA Astrophysics Data System (ADS)

    Pwasong, Augustine; Sathasivam, Saratha

    2015-10-01

    Hyperbolic activation function is examined for its ability to accelerate the performance of doing data mining by using a technique named as Reverse Analysis method. In this paper, we describe how Hopfield network perform better with hyperbolic activation function and able to induce logical rules from large database by using reverse analysis method: given the values of the connections of a network, we can hope to know what logical rules are entrenched in the database. We limit our analysis to Horn clauses.

  5. Reverse radiance: a fast accurate method for determining luminance

    NASA Astrophysics Data System (ADS)

    Moore, Kenneth E.; Rykowski, Ronald F.; Gangadhara, Sanjay

    2012-10-01

    Reverse ray tracing from a region of interest backward to the source has long been proposed as an efficient method of determining luminous flux. The idea is to trace rays only from where the final flux needs to be known back to the source, rather than tracing in the forward direction from the source outward to see where the light goes. Once the reverse ray reaches the source, the radiance the equivalent forward ray would have represented is determined and the resulting flux computed. Although reverse ray tracing is conceptually simple, the method critically depends upon an accurate source model in both the near and far field. An overly simplified source model, such as an ideal Lambertian surface substantially detracts from the accuracy and thus benefit of the method. This paper will introduce an improved method of reverse ray tracing that we call Reverse Radiance that avoids assumptions about the source properties. The new method uses measured data from a Source Imaging Goniometer (SIG) that simultaneously measures near and far field luminous data. Incorporating this data into a fast reverse ray tracing integration method yields fast, accurate data for a wide variety of illumination problems.

  6. Time Reversal Method for Pipe Inspection with Guided Wave

    NASA Astrophysics Data System (ADS)

    Deng, Fei; He, Cunfu; Wu, Bin

    2008-02-01

    The temporal-spatial focusing effect of the time reversal method on the guided wave inspection in pipes is investigated. A steel pipe model with outer diameter of 70 mm and wall thickness of 3.5 mm is numerically built to analyse the reflection coefficient of L(0,2) mode when the time reversal method is applied in the model. According to the calculated results, it is shown that a synthetic time reversal array method is effective to improve the signal-to-noise ratio of a guided wave inspection system. As an intercepting window is widened, more energy can be included in a re-emitted signal, which leads to a large reflection coefficient of L(0,2) mode. It is also shown that when a time reversed signal is reapplied in the pipe model, by analysing the motion of the time reversed wave propagating along the pipe model, a defect can be identified. Therefore, it is demonstrated that the time reversal method can be used to locate the circumferential position of a defect in a pipe. Finally, through an experiment corresponding with the pipe model, the experimental result shows that the above-mentioned method can be valid in the inspection of a pipe.

  7. Acoustic imaging with time reversal methods: From medicine to NDT

    NASA Astrophysics Data System (ADS)

    Fink, Mathias

    2015-03-01

    This talk will present an overview of the research conducted on ultrasonic time-reversal methods applied to biomedical imaging and to non-destructive testing. We will first describe iterative time-reversal techniques that allow both focusing ultrasonic waves on reflectors in tissues (kidney stones, micro-calcifications, contrast agents) or on flaws in solid materials. We will also show that time-reversal focusing does not need the presence of bright reflectors but it can be achieved only from the speckle noise generated by random distributions of non-resolved scatterers. We will describe the applications of this concept to correct distortions and aberrations in ultrasonic imaging and in NDT. In the second part of the talk we will describe the concept of time-reversal processors to get ultrafast ultrasonic images with typical frame rates of order of 10.000 F/s. It is the field of ultrafast ultrasonic imaging that has plenty medical applications and can be of great interest in NDT. We will describe some applications in the biomedical domain: Quantitative Elasticity imaging of tissues by following shear wave propagation to improve cancer detection and Ultrafast Doppler imaging that allows ultrasonic functional imaging.

  8. Optimization of reversed-phase chromatography methods for peptide analytics.

    PubMed

    Khalaf, Rushd; Baur, Daniel; Pfister, David

    2015-12-18

    The analytical description and quantification of peptide solutions is an essential part in the quality control of peptide production processes and in peptide mapping techniques. Traditionally, an important tool is analytical reversed phase liquid chromatography. In this work, we develop a model-based tool to find optimal analytical conditions in a clear, efficient and robust manner. The model, based on the Van't Hoff equation, the linear solvent strength correlation, and an analytical solution of the mass balance on a chromatographic column describing peptide retention in gradient conditions is used to optimize the analytical scale separation between components in a peptide mixture. The proposed tool is then applied in the design of analytical reversed phase liquid chromatography methods of five different peptide mixtures. PMID:26620597

  9. Reverse optimization reconstruction method in non-null aspheric interferometry

    NASA Astrophysics Data System (ADS)

    Zhang, Lei; Liu, Dong; Shi, Tu; Yang, Yongying; Chong, Shiyao; Shen, Yibing; Bai, Jian

    2015-10-01

    Aspheric non-null test achieves more flexible measurements than the null test. However, the precision calibration for retrace error has always been difficult. A reverse optimization reconstruction (ROR) method is proposed for the retrace error calibration as well as the aspheric figure error extraction based on system modeling. An optimization function is set up with system model, in which the wavefront data from experiment is inserted as the optimization objective while the figure error under test in the model as the optimization variable. The optimization is executed by the reverse ray tracing in the system model until the test wavefront in the model is consistent with the one in experiment. At this point, the surface figure error in the model is considered to be consistent with the one in experiment. With the Zernike fitting, the aspheric surface figure error is then reconstructed in the form of Zernike polynomials. Numerical simulations verifying the high accuracy of the ROR method are presented with error considerations. A set of experiments are carried out to demonstrate the validity and repeatability of ROR method. Compared with the results of Zygo interferometer (null test), the measurement error by the ROR method achieves better than 1/10λ.

  10. Methods of torque ripple reduction for flux reversal motor

    NASA Astrophysics Data System (ADS)

    Vakil, Gaurang; Sheth, N. K.; Miller, David

    2009-04-01

    This paper presents two-dimensional finite element based results for various methods of torque ripple reduction in flux-reversal motors. The effects of variation in magnet and rotor pole heights, rotor pole skewing, and multiple teeth per rotor pole on the cogging torque, developed torque, torque ripple, and phase inductance and also an optimum value of the magnet and rotor pole heights, skew angle, and choice of teeth per rotor pole with the teeth depth resulting in torque ripple reduction are presented.

  11. Integration of Boltzmann machine and reverse analysis method

    NASA Astrophysics Data System (ADS)

    Mamuda, Mamman; Sathasivam, Saratha

    2015-10-01

    Reverse analysis method is actually a data mining technique to unearth relationships between data. By knowing the connection strengths by using Hopfield network, we can extract the relationships in data sets. Hopfield networks have recognized that some relaxation schemes have a joined cost function and the states of the network converge to local minima of this function. It had performed optimization of a well-defined function. However, there is no guarantee to find the best minimum in the network. Thus, Boltzmann machine has been introduced to overcome this problem. In this paper, we integrate both approaches to enhance data mining. We limit our work to Horn clauses.

  12. On the orthogonalised reverse path method for nonlinear system identification

    NASA Astrophysics Data System (ADS)

    Muhamad, P.; Sims, N. D.; Worden, K.

    2012-09-01

    The problem of obtaining the underlying linear dynamic compliance matrix in the presence of nonlinearities in a general multi-degree-of-freedom (MDOF) system can be solved using the conditioned reverse path (CRP) method introduced by Richards and Singh (1998 Journal of Sound and Vibration, 213(4): pp. 673-708). The CRP method also provides a means of identifying the coefficients of any nonlinear terms which can be specified a priori in the candidate equations of motion. Although the CRP has proved extremely useful in the context of nonlinear system identification, it has a number of small issues associated with it. One of these issues is the fact that the nonlinear coefficients are actually returned in the form of spectra which need to be averaged over frequency in order to generate parameter estimates. The parameter spectra are typically polluted by artefacts from the identification of the underlying linear system which manifest themselves at the resonance and anti-resonance frequencies. A further problem is associated with the fact that the parameter estimates are extracted in a recursive fashion which leads to an accumulation of errors. The first minor objective of this paper is to suggest ways to alleviate these problems without major modification to the algorithm. The results are demonstrated on numerically-simulated responses from MDOF systems. In the second part of the paper, a more radical suggestion is made, to replace the conditioned spectral analysis (which is the basis of the CRP method) with an alternative time domain decorrelation method. The suggested approach - the orthogonalised reverse path (ORP) method - is illustrated here using data from simulated single-degree-of-freedom (SDOF) and MDOF systems.

  13. Methods of Forming Visual Hydrogen Detector with Variable Reversibility

    NASA Technical Reports Server (NTRS)

    Muradov, Nazim Z. (Inventor)

    2014-01-01

    Methods, processes and compositions are provided for a visual or chemochromic hydrogen-detector with variable or tunable reversible color change. The working temperature range for the hydrogen detector is from minus 100 C to plus 500 C. A hydrogen-sensitive pigment, including, but not limited to, oxides, hydroxides and polyoxo-compounds of tungsten, molybdenum, vanadium, chromium and combinations thereof, is combined with nano-sized metal activator particles and preferably, coated on a porous or woven substrate. In the presence of hydrogen, the composition rapidly changes its color from white or light-gray or light-tan to dark gray, navy-blue or black depending on the exposure time and hydrogen concentration in the medium. After hydrogen exposure ceases, the original color of the hydrogen-sensitive pigment is restored, and the visual hydrogen detector can be used repeatedly. By changing the composition of the hydrogen-sensitive pigment, the time required for its complete regeneration is varied from a few seconds to several days.

  14. Reversible rigid coupling apparatus and method for borehole seismic transducers

    DOEpatents

    Owen, Thomas E.; Parra, Jorge O.

    1992-01-01

    An apparatus and method of high resolution reverse vertical seismic profile (VSP) measurements is shown. By encapsulating the seismic detector and heaters in a meltable substance (such as wax), the seismic detector can be removably secured in a borehole in a manner capable of measuring high resolution signals in the 100 to 1000 hertz range and higher. The meltable substance is selected to match the overall density of the detector package with the underground formation, yet still have relatively low melting point and rigid enough to transmit vibrations to accelerometers in the seismic detector. To minimize voids in the meltable substance upon solidification, the meltable substance is selected for minimum shrinkage, yet still having the other desirable characteristics. Heaters are arranged in the meltable substance in such a manner to allow the lowermost portion of the meltable substance to cool and solidify first. Solidification continues upwards from bottom-to-top until the top of the meltable substance is solidified and the seismic detector is ready for use. To remove, the heaters melt the meltable substance and the detector package is pulled from the borehole.

  15. An alternate and reversible method for flight restraint of cranes.

    PubMed

    Zhang, Sen Lin; Yang, Shu Hui; Li, Bing; Xu, Yan Chun; Ma, Jian Hua; Xu, Jian Feng; Zhang, Xian Guang

    2011-01-01

    Flight restraint is important for zoos, safaris, and breeding centers for large birds. Currently used techniques for flight restraint include both surgical and non-surgical approaches. Surgical approaches usually cause permanent change to or removal of tendon, patagial membrane, or wing bones, and can cause pain and inflammation. Non-surgical approaches such as clipping or trimming feathers often alter the bird's appearance, and can damage growing blood feathers in fledglings or cause joint stiffness. We observed microstructure of primary feathers of the red-crowned crane (Grus japonensis) and found that the width of barbs is a determinative factor influencing vane stiffness and geometric parameters. We hypothesized that partial longitudinal excision of barbs on the ventral surface of the primary feathers would reduce the stiffness of the vane and render the feathers unable to support the crane's body weight during flight. Furthermore, we hypothesized that this modification of barbs would also change the aerodynamic performance of feathers such that they could not generate sufficient lift and thrust during flapping to enable the bird to fly. We tested this hypothesis on a red-crowned crane that had normal flight capability by excising the ventral margin of barbs on all 10 primaries on the left wing. The bird was unable to take off until the modified feathers were replaced by new ones. Removal of barbs proved to be a simple, non-invasive, low-cost and reversible method for flight restraint. It is potentially applicable to other large birds with similar structural characteristics of primary feathers. PMID:21538502

  16. Reversible geling co-polymer and method of making

    DOEpatents

    Gutowska, Anna

    2005-12-27

    The present invention is a thereapeutic agent carrier having a thermally reversible gel or geling copolymer that is a linear random copolymer of an [meth-]acrylamide derivative and a hydrophilic comonomer, wherein the linear random copolymer is in the form of a plurality of linear chains having a plurality of molecular weights greater than or equal to a minimum geling molecular weight cutoff and a therapeutic agent.

  17. Committee Opinion No 672 Summary Clinical Challenges of Long-Acting Reversible Contraceptive Methods.

    PubMed

    2016-09-01

    Long-acting reversible contraceptive methods are the most effective reversible contraceptives and have an excellent safety record. Although uncommon, possible long-acting reversible contraceptive complications should be included in the informed consent process. Obstetrician-gynecologists and other gynecologic care providers should understand the diagnosis and management of common clinical challenges. The American College of Obstetricians and Gynecologists recommends the algorithms included in this document for management of the most common clinical challenges. PMID:27548551

  18. Committee Opinion No 672: Clinical Challenges of Long-Acting Reversible Contraceptive Methods.

    PubMed

    2016-09-01

    Long-acting reversible contraceptive methods are the most effective reversible contraceptives and have an excellent safety record. Although uncommon, possible long-acting reversible contraceptive complications should be included in the informed consent process. Obstetrician-gynecologists and other gynecologic care providers should understand the diagnosis and management of common clinical challenges. The American College of Obstetricians and Gynecologists recommends the algorithms included in this document for management of the most common clinical challenges. PMID:27548557

  19. Reversible rigid coupling apparatus and method for borehole seismic transducers

    SciTech Connect

    Owen, T.E.; Parra, J.O.

    1992-01-14

    This patent describes a seismic detector for high resolution reverse vertical seismic profile measurements when placed in a shallow borehole in a geological formation of interest that contains a seismic source and connected to a seismograph. It comprises a framework; accelerometer sensors for X, Y, and Z axis, means for electrically connecting the accelerometers to the seismograph to record seismic waves received by the accelerometer sensors form the seismic source; heating elements secured to, but electrically insulated from, the framework; power means for supplying power to the heating elements; and meltable substance encapsulating the seismic detector.

  20. Health monitoring of bolted joints using the time reversal method and piezoelectric transducers

    NASA Astrophysics Data System (ADS)

    Tao, Wang; Shaopeng, Liu; Junhua, Shao; Yourong, Li

    2016-02-01

    In this paper, the time reversal method based on piezoelectric active sensing is investigated for health monitoring of bolted joints. Experiments are conducted on bolted joints to study the relationship between the time reversal focused signal peak amplitudes and the bolt preload. Two piezoelectric patches are bonded on two different sides of a bolted joint. Any one of the piezoelectric patches can be used as an actuator to generate an ultrasonic wave, and the other one can be used as a sensor to detect the propagated wave. With the time reversal method, the received response signal is reversed in the time domain and then is re-emitted as an excitation signal to acquire the time reversal focused signals. The experimental results show that the time reversal focused signal peak amplitudes increase with the increasing bolt preload until reaching saturation, and when the bolt preload increases to a certain value, the focused signal peak amplitudes will remain unchanged. Experiments show that the surface roughness of the bolted joint impacts the saturation value. A higher surface roughness value corresponds to a higher saturation value. In addition, the proposed method has a high signal to noise ratio benefiting from the time reversal method time and space focusing ability.

  1. Reverse and direct methods for solving the characteristic equation

    NASA Astrophysics Data System (ADS)

    Lozhkin, Alexander; Bozek, Pavol; Lyalin, Vadim; Tarasov, Vladimir; Tothova, Maria; Sultanov, Ravil

    2016-06-01

    Fundamentals of information-linguistic interpretation of the geometry presented shortly. The method of solving the characteristic equation based on Euler's formula is described. The separation of the characteristic equation for several disassembled for Jordan curves. Applications of the theory for problems of mechatronics outlined briefly.

  2. Use of the FDTD method for time reversal: application to microwave breast cancer detection

    NASA Astrophysics Data System (ADS)

    Kosmas, Panagiotis; Rappaport, Carey

    2004-05-01

    The feasibility of microwave breast cancer detection with a time reversal algorithm is examined. This time reversal algorithm, based on the finite difference time domain method (FDTD), time reverses not only the recorded field, but also the medium. It compensates for the wave decay and therefore is suitable for lossy media. We present two-dimensional (2D) breast models and geometries, and assume knowledge of the system's response in the absence of tumor (distorted wave Born approximation). Our results illustrate the system's detection and localization abilities, and its robustness to dispersion and measurement noise. Good performance using a simple time reversal mirror shows that this method is a promising technique for microwave imaging, and encourages us to further examine its applicability to microwave breast cancer detection.

  3. Reconstructed imaging of acoustic cloak using time-lapse reversal method

    NASA Astrophysics Data System (ADS)

    Zhou, Chen; Cheng, Ying; Xu, Jian-yi; Li, Bo; Liu, Xiao-jun

    2014-08-01

    We proposed and investigated a solution to the inverse acoustic cloak problem, an anti-stealth technology to make cloaks visible, using the time-lapse reversal (TLR) method. The TLR method reconstructs the image of an unknown acoustic cloak by utilizing scattered acoustic waves. Compared to previous anti-stealth methods, the TLR method can determine not only the existence of a cloak but also its exact geometric information like definite shape, size, and position. Here, we present the process for TLR reconstruction based on time reversal invariance. This technology may have potential applications in detecting various types of cloaks with different geometric parameters.

  4. Combustion-engine Temperatures by the Sodium Line-reversal Method

    NASA Technical Reports Server (NTRS)

    Brevoort, Maurice J

    1936-01-01

    The sodium line-reversal method has been used in some preliminary measurements of flame temperature. Improvements in the method involving a photographic recorder and a means of correcting for the dirtiness of the windows are described. The temperatures so obtained are compared with those calculated from pressure diagrams.

  5. Time Reversed Electromagnetics as a Novel Method for Wireless Power Transfer

    NASA Astrophysics Data System (ADS)

    Challa, Anu; Anlage, Steven M.; Tesla Team

    Taking advantage of ray-chaotic enclosures, time reversal has been shown to securely transmit information via short-wavelength waves between two points, yielding noise at all other sites. In this presentation, we propose a method to adapt the signal-focusing technique to electromagnetic signals in order to transmit energy to portable devices. Relying only on the time-reversal invariance properties of waves, the technique is unencumbered by the inversely-proportional-to-distance path loss or precise orientation requirements of its predecessors, making it attractive for power transfer applications. We inject a short microwave pulse into a complex, wave-chaotic chamber and collect the resulting long time-domain signal at a designated transceiver. The signal is then time reversed and emitted from the collection site, collapsing as a time-reversed replica of the initial pulse at the injection site. When amplified, this reconstruction is robust, as measured through metrics of peak-to-peak voltage and energy transfer ratio. We experimentally demonstrate that time reversed collapse can be made on a moving target, and propose a way to selectively target devices through nonlinear time-reversal. University of Maryland Gemstone Team TESLA: Frank Cangialosi, Anu Challa, Tim Furman, Tyler Grover, Patrick Healey, Ben Philip, Brett Potter, Scott Roman, Andrew Simon, Liangcheng Tao, Alex Tabatabai.

  6. A generalized reverse projection method for fan beam geometry under partially coherent illumination

    NASA Astrophysics Data System (ADS)

    Wu, Z.; Wang, Z. L.; Gao, K.; Zhang, K.; Ge, X.; Wang, D. J.; Wang, S. H.; Chen, J.; Pan, Z. Y.; Zhu, P. P.; Wu, Z. Y.

    2014-02-01

    In this paper, a generalized reverse projection (RP) method for grating-based fan beam phase contrast imaging is presented. Compared to the original RP method, rays rather than projection images are taken into account during the information extraction process. We also discuss the influence of partial coherence on the extracted information. Theoretical derivations and numerical simulations are performed to confirm the validity of the method.

  7. Time Reversal Imaging of Seismic Sources by the Spectral Element Method.

    NASA Astrophysics Data System (ADS)

    Larmat, C.; Montagner, J.; Fink, M.; Capdeville, Y.; Clevede, E.; Tourin, A.

    2005-12-01

    The increasing power of computers and numerical methods (such as spectral elements methods) makes it possible to simulate more and more accurately the propagation of seismic waves in heterogeneous media and even to conceive new applications such as time reversal experiments within the three--dimensional Earth. These latter use the time reversal invariance and the spatial reciprocity of the wave equation. The idea is to construct a reverse movie of the propagation by sending the time--reversed recorded signals back from the receivers. The energy refocuses back at the location and the time of the original source. The concept of time-reversal has previously been successfully applied for acoustic waves in many fields such as medical imaging, oceanography and non destructive testing. For simulating the propagation of waves in the Earth as well as their time-reversed propagation, we used 2 different techniques, the normal mode summation technique (Gilbert and Dziewonski, 1975) and the spectral element method coupled with the modal solution (Capdeville et al., 2003). The first method is very accurate for 1D-earth models such as PREM whereas the second method is required for general heterogeneous 3D-models. For the first time, we have performed several synthetic and real data time-reversal experiments for seismic waves until the time of focalisation at the source. These tests show that sources are successfully localized in time and in space (though less accurately at depth), especially at very long period (> 200s) where the seismic properties of the Earth are well constrained. The corresponding movies are visible at the following address: http://www.gps.caltech.edu/~carene. We collect and send back the seismograms of the Global network of broadband seismic stations of the Federation of Digital Seismic Network (FDSN). We first consider a moderately large earthquake which can be considered as a point source in both time and space (Peru, June 23, 2001, Mw = 8.4). The

  8. A centrifugal method for the evaluation of polymer membranes for reverse osmosis

    NASA Technical Reports Server (NTRS)

    Hollahan, J. R.; Wydeven, T.; Mccullough, R. P.

    1973-01-01

    A rapid and simple method employing the laboratory centrifuge shows promise for evaluation of membrane performance during reverse osmosis. Results are presented for cellulose acetate membranes for rejection of salt and urea dissolved solids. Implications of the study are to rapid screening of membrane performance, use in laboratories with limited facilities, and possible space waste water purification.

  9. Multiple line arrays for the characterization of aeroacoustic sources using a time-reversal method.

    PubMed

    Mimani, A; Doolan, C J; Medwell, P R

    2013-10-01

    This letter investigates the use of multiple line arrays (LAs) in a Time-Reversal Mirror for localizing and characterizing multipole aeroacoustic sources in a uniform subsonic mean flow using a numerical Time-Reversal (TR) method. Regardless of the original source characteristics, accuracy of predicting the source location can be significantly improved using at least two LAs. Furthermore, it is impossible to determine the source characteristics using a single LA, rather a minimum of two are required to establish either the monopole or dipole source nature, while four LAs (fully surrounding the source) are required for characterizing a lateral quadrupole source. PMID:24116538

  10. Method of electric field flow fractionation wherein the polarity of the electric field is periodically reversed

    DOEpatents

    Stevens, Fred J.

    1992-01-01

    A novel method of electric field flow fractionation for separating solute molecules from a carrier solution is disclosed. The method of the invention utilizes an electric field that is periodically reversed in polarity, in a time-dependent, wave-like manner. The parameters of the waveform, including amplitude, frequency and wave shape may be varied to optimize separation of solute species. The waveform may further include discontinuities to enhance separation.

  11. A test method to measure the response of composite materials under reversed cyclic loads

    NASA Technical Reports Server (NTRS)

    Bakis, Charles E.; Simonds, Robert A.; Stinchcomb, Wayne W.

    1989-01-01

    A test method to measure the response of composite materials under reversed cyclic loads is described. The method approximates the long-term response of a component by permitting the composite specimen to respond to the imposed loads and fail in an unconstrained mode rather than in a constrained mode. The method has been successfully used for the reversed cyclic loading of unnotched and notched graphite/epoxy and graphite/PEEK laminates of various stacking sequences. Included in the paper are monotonic tensile and compressive stiffness and strength data at several points in the fatigue lifetime, and damage development information obtained via X-ray radiography for quasi-isotropic T300/5208 and AS4/PEEK laminates with unloaded circular holes.

  12. Application of Carbonate Reservoir using waveform inversion and reverse-time migration methods

    NASA Astrophysics Data System (ADS)

    Kim, W.; Kim, H.; Min, D.; Keehm, Y.

    2011-12-01

    Recent exploration targets of oil and gas resources are deeper and more complicated subsurface structures, and carbonate reservoirs have become one of the attractive and challenging targets in seismic exploration. To increase the rate of success in oil and gas exploration, it is required to delineate detailed subsurface structures. Accordingly, migration method is more important factor in seismic data processing for the delineation. Seismic migration method has a long history, and there have been developed lots of migration techniques. Among them, reverse-time migration is promising, because it can provide reliable images for the complicated model even in the case of significant velocity contrasts in the model. The reliability of seismic migration images is dependent on the subsurface velocity models, which can be extracted in several ways. These days, geophysicists try to obtain velocity models through seismic full waveform inversion. Since Lailly (1983) and Tarantola (1984) proposed that the adjoint state of wave equations can be used in waveform inversion, the back-propagation techniques used in reverse-time migration have been used in waveform inversion, which accelerated the development of waveform inversion. In this study, we applied acoustic waveform inversion and reverse-time migration methods to carbonate reservoir models with various reservoir thicknesses to examine the feasibility of the methods in delineating carbonate reservoir models. We first extracted subsurface material properties from acoustic waveform inversion, and then applied reverse-time migration using the inverted velocities as a background model. The waveform inversion in this study used back-propagation technique, and conjugate gradient method was used in optimization. The inversion was performed using the frequency-selection strategy. Finally waveform inversion results showed that carbonate reservoir models are clearly inverted by waveform inversion and migration images based on the

  13. Reversed-phase high-performance liquid chromatographic method for the assay of oxytetracycline.

    PubMed

    Barnes, W N; Ray, A; Bates, L J

    1985-10-25

    The British Pharmacopoeia monograph for oxytetracycline calcium describes an high-performance liquid chromatographic (HPLC) assay which requires packing of the column by the analyst. Presented in this report is an HPLC method for the assay of oxytetracycline which employs a commercially available reversed-phase column and a solvent system which gives improved separation of the antibiotic from common impurities. Results obtained using this method for both bulk and dosage forms of oxytetracycline are in accord with the results of the microbiological assays. PMID:4086631

  14. Distortion Correction in EPI Using an Extended PSF Method with a Reversed Phase Gradient Approach

    PubMed Central

    In, Myung-Ho; Posnansky, Oleg; Beall, Erik B.; Lowe, Mark J.; Speck, Oliver

    2015-01-01

    In echo-planar imaging (EPI), such as commonly used for functional MRI (fMRI) and diffusion-tensor imaging (DTI), compressed distortion is a more difficult challenge than local stretching as spatial information can be lost in strongly compressed areas. In addition, the effects are more severe at ultra-high field (UHF) such as 7T due to increased field inhomogeneity. To resolve this problem, two EPIs with opposite phase-encoding (PE) polarity were acquired and combined after distortion correction. For distortion correction, a point spread function (PSF) mapping method was chosen due to its high correction accuracy and extended to perform distortion correction of both EPIs with opposite PE polarity thus reducing the PSF reference scan time. Because the amount of spatial information differs between the opposite PE datasets, the method was further extended to incorporate a weighted combination of the two distortion-corrected images to maximize the spatial information content of a final corrected image. The correction accuracy of the proposed method was evaluated in distortion-corrected data using both forward and reverse phase-encoded PSF reference data and compared with the reversed gradient approaches suggested previously. Further we demonstrate that the extended PSF method with an improved weighted combination can recover local distortions and spatial information loss and be applied successfully not only to spin-echo EPI, but also to gradient-echo EPIs acquired with both PE directions to perform geometrically accurate image reconstruction. PMID:25707006

  15. Wideband nonlinear time reversal seismo-acoustic method for landmine detection.

    PubMed

    Sutin, Alexander; Libbey, Brad; Fillinger, Laurent; Sarvazyan, Armen

    2009-04-01

    Acoustic and seismic waves provide a method to localize compliant mines by vibrating the top plate and a thin soil layer above the mine. This vibration is mostly linear, but also includes a small nonlinear deviation. The main goal of this paper is to introduce a method of processing that uses phase-inversion to observe nonlinear effects in a wide frequency band. The method extracts a nonlinear part of surface velocity from two similar broadcast signals of opposite sign by summing and cancelling the linear components and leaving the nonlinear components. This phase-inversion method is combined with time reversal focusing to provide increased seismic vibration and enhance the nonlinear effect. The experiments used six loudspeakers in a wood box placed over sand in which inert landmines were buried. The nonlinear surface velocity of the sand with a mine compared to the sand without a mine was greater as compared to a linear technique. PMID:19354365

  16. Method for the preparation of thin-skinned asymmetric reverse osmosis membranes and products thereof

    NASA Technical Reports Server (NTRS)

    Wydeven, T. J. (Inventor); Katz, M. G.

    1984-01-01

    A method for preparing water insoluble asymmetric membranes from water soluble polymers is discussed. The process involves casting a film of the polymer, partially drying it, and then contacting it with a concentrated solution of a transition metal salt. The transition metal ions render the polymer insoluable and are believed to form a complex with it. Optionally, the polymer is crosslinked with heat or radiation. The most preferred polymer is poly(vinyl alcohol). The most preferred complexing salt is copper sulfate. The process and the metal ion linked membranes are discussed. The membranes are reverse osmosis membranes.

  17. Acceptance of long-acting reversible contraceptive methods by adolescent participants in the Contraceptive CHOICE Project

    PubMed Central

    Mestad, Renee; Secura, Gina; Allsworth, Jenifer E; Madden, Tessa; Zhao, Qiuhong; Peipert, Jeffrey F

    2012-01-01

    Background Adolescent women have a high risk of unintended pregnancy. Currently, there are little data about their choice to initiate long-acting reversible contraception (LARC). Study Design We evaluated the association of age and preference for a LARC vs. a non-LARC method among adolescent participants in the Contraceptive CHOICE Project, comparing those aged 14–17 years to adolescents aged 18–20 years. We then analyzed the association between age and choice of the implant vs. the intrauterine device (IUD) among adolescents. Results Of the 5086 women enrolled, 70% (n=3557) of participants chose a LARC method. Among adolescents aged 14–20 years, 69% of 14–17-year-olds chose LARC, while 61% of 18–20-year-olds chose LARC (relative risk 1.16, 95% confidence interval 1.03–1.30). Among adolescents choosing a LARC method, 63% (n=93/148) of the 14–17-year-olds chose the implant, whereas 71% (n=364/510) of the 18–20-year-olds chose the IUD. Conclusion Long-acting reversible contraception use is clearly acceptable and common among adolescents enrolled in the Contraceptive CHOICE Project, with the younger group being most interested in the implant. PMID:22018123

  18. Fast reversible single-step method for enhanced band contrast of polyacrylamide gels for automated detection.

    PubMed

    Ling, Wei-Li; Lua, Wai-Heng; Gan, Samuel Ken-En

    2015-05-01

    Staining SDS-PAGE is commonly used in protein analysis for many downstream characterization processes. Although staining and destaining protocols can be adjusted, they can be laborious, and faint bands often become false negatives. Similarly, these faint bands hinder automated software band detections that are necessary for quantitative analyses. To overcome these problems, we describe a single-step rapid and reversible method to increase (up to 500%) band contrast in stained gels. Through the use of alcohols, we improved band detection and facilitated gel storage by drying the gels into compact white sheets. This method is suitable for all stained SDS-PAGE gels, including gradient gels and is shown to improve automated band detection by enhanced band contrast. PMID:25782090

  19. Fast reversible single-step method for enhanced band contrast of polyacrylamide gels for automated detection

    PubMed Central

    Ling, Wei-Li; Lua, Wai-Heng; Gan, Samuel Ken-En

    2015-01-01

    Staining SDS-PAGE is commonly used in protein analysis for many downstream characterization processes. Although staining and destaining protocols can be adjusted, they can be laborious, and faint bands often become false negatives. Similarly, these faint bands hinder automated software band detections that are necessary for quantitative analyses. To overcome these problems, we describe a single-step rapid and reversible method to increase (up to 500%) band contrast in stained gels. Through the use of alcohols, we improved band detection and facilitated gel storage by drying the gels into compact white sheets. This method is suitable for all stained SDS-PAGE gels, including gradient gels and is shown to improve automated band detection by enhanced band contrast. PMID:25782090

  20. Digital Sequences and a Time Reversal-Based Impact Region Imaging and Localization Method

    PubMed Central

    Qiu, Lei; Yuan, Shenfang; Mei, Hanfei; Qian, Weifeng

    2013-01-01

    To reduce time and cost of damage inspection, on-line impact monitoring of aircraft composite structures is needed. A digital monitor based on an array of piezoelectric transducers (PZTs) is developed to record the impact region of impacts on-line. It is small in size, lightweight and has low power consumption, but there are two problems with the impact alarm region localization method of the digital monitor at the current stage. The first one is that the accuracy rate of the impact alarm region localization is low, especially on complex composite structures. The second problem is that the area of impact alarm region is large when a large scale structure is monitored and the number of PZTs is limited which increases the time and cost of damage inspections. To solve the two problems, an impact alarm region imaging and localization method based on digital sequences and time reversal is proposed. In this method, the frequency band of impact response signals is estimated based on the digital sequences first. Then, characteristic signals of impact response signals are constructed by sinusoidal modulation signals. Finally, the phase synthesis time reversal impact imaging method is adopted to obtain the impact region image. Depending on the image, an error ellipse is generated to give out the final impact alarm region. A validation experiment is implemented on a complex composite wing box of a real aircraft. The validation results show that the accuracy rate of impact alarm region localization is approximately 100%. The area of impact alarm region can be reduced and the number of PZTs needed to cover the same impact monitoring region is reduced by more than a half. PMID:24084123

  1. Digital sequences and a time reversal-based impact region imaging and localization method.

    PubMed

    Qiu, Lei; Yuan, Shenfang; Mei, Hanfei; Qian, Weifeng

    2013-01-01

    To reduce time and cost of damage inspection, on-line impact monitoring of aircraft composite structures is needed. A digital monitor based on an array of piezoelectric transducers (PZTs) is developed to record the impact region of impacts on-line. It is small in size, lightweight and has low power consumption, but there are two problems with the impact alarm region localization method of the digital monitor at the current stage. The first one is that the accuracy rate of the impact alarm region localization is low, especially on complex composite structures. The second problem is that the area of impact alarm region is large when a large scale structure is monitored and the number of PZTs is limited which increases the time and cost of damage inspections. To solve the two problems, an impact alarm region imaging and localization method based on digital sequences and time reversal is proposed. In this method, the frequency band of impact response signals is estimated based on the digital sequences first. Then, characteristic signals of impact response signals are constructed by sinusoidal modulation signals. Finally, the phase synthesis time reversal impact imaging method is adopted to obtain the impact region image. Depending on the image, an error ellipse is generated to give out the final impact alarm region. A validation experiment is implemented on a complex composite wing box of a real aircraft. The validation results show that the accuracy rate of impact alarm region localization is approximately 100%. The area of impact alarm region can be reduced and the number of PZTs needed to cover the same impact monitoring region is reduced by more than a half. PMID:24084123

  2. High sensitive method detection of plant RNA viruses by electrochemiluminescence reverse transcription PCR

    NASA Astrophysics Data System (ADS)

    Tang, Ya-bing; Xing, Da; Zhu, De-bin; Zhou, Xiao-ming

    2007-05-01

    It is well known that plant and animal viruses had widely spread the whole of world, and made a big loss in farming and husbandry. It is necessary that a highly efficient and accurate virus's detection method was developed. This research combines reverse transcription polymerase chain reaction (RT-PCR) technique with electrochemiluminescence method, to detect plant RNA viruses for the first time. Biotin-probe hybridizes with PCR product to specific select the target for detection, thus can avoid pseudo-positive result. TBR-probe hybridizes with PCR product to emit light for ECL detection. Specific nucleic acid sequences (20bp) were added to 5' terminal all of the primers, which can improve the chance of hybridization between TBR-probe and PCR product. At the same time, one of the PCR product chain can hybridize two Ru-probes, the ECL signal is intensified. The method was used to detect Odntoglossum ringspot virus ORSV, Sugarcane mosaic virus ScMV, Sorghum mosaic virus SrMV, and Maize dwarf mosaic virus MDMV, the experiment results show that this method could reliably identity virus infected plant samples. In a word, this method has higher sensitivity and lower cost than others. It can effectively detect the plant viruses with simplicity, stability, and high sensitivity.

  3. Reversible Electro-Optic Device Employing Aprotic Molten Salts And Method

    DOEpatents

    Warner, Benjamin P.; McCleskey, T. Mark; Burrell, Anthony K.; Hall, Simon B.

    2005-03-01

    A single-compartment reversible mirror device having a solution of aprotic molten salt, at least one soluble metal-containing species comprising metal capable of being electrodeposited, and at least one anodic compound capable of being oxidized was prepared. The aprotic molten salt is liquid at room temperature and includes lithium and/or quaternary ammonium cations, and anions selected from trifluoromethylsulfonate (CF.sub.3 SO.sub.3.sup.-), bis(trifluoromethylsulfonyl)imide ((CF.sub.3 SO.sub.2).sub.2 N.sup.-), bis(perfluoroethylsulfonyl)imide ((CF.sub.3 CF.sub.2 SO.sub.2).sub.2 N.sup.-) and tris(trifluoromethylsulfonyl)methide ((CF.sub.3 SO.sub.2).sub.3 C.sup.-). A method for preparing substantially pure molten salts is also described.

  4. Reversible electro-optic device employing aprotic molten salts and method

    DOEpatents

    Warner, Benjamin P.; McCleskey, T. Mark; Burrell, Anthony K.; Hall, Simon B.

    2008-01-08

    A single-compartment reversible mirror device having a solution of aprotic molten salt, at least one soluble metal-containing species comprising metal capable of being electrodeposited, and at least one anodic compound capable of being oxidized was prepared. The aprotic molten salt is liquid at room temperature and includes lithium and/or quaternary ammonium cations, and anions selected from trifluoromethylsulfonate (CF.sub.3SO.sub.3.sup.-), bis(trifluoromethylsulfonyl)imide ((CF.sub.3SO.sub.2).sub.2N.sup.-), bis(perfluoroethylsulfonyl)imide ((CF.sub.3CF.sub.2SO.sub.2).sub.2N.sup.-) and tris(trifluoromethylsulfonyl)methide ((CF.sub.3SO.sub.2).sub.3C.sup.-). A method for preparing substantially pure molten salts is also described.

  5. Synthesis and characterization of Fe-Co catalyst prepared via reverse microemulsion method

    NASA Astrophysics Data System (ADS)

    Mohd Zabidi, Noor Asmawati; Abdul Aziz, Muhammad Nur Azizi; Ali, Sardar; Taha, Mohd Faisal

    2012-09-01

    This paper reports the characterization of bimetallic catalyst systems comprising cobalt and iron on CNTs support prepared via reverse microemulsion method. The properties of the bimetallic catalyst were characterized using TEM, FESEM and N2 adsorption. Based on TEM analyses, the calculated average particle sizes ranged from 4.6 nm to 5.2 nm for the various catalyst compositions. The performance of the Co-based catalyst in a Fischer-Tropsch reaction was evaluated in a fixed-bed reactor at 220°C, 1 atm and H2/CO v/v ratio of 2:1 v/v and space velocity of 12 L/g.h. Amongst the catalysts tested, the 90Co10Fe/CNTs resulted in the highest CO conversion of 14.1% whereas the 100Co/CNTs resulted in the highest C5+ hydrocarbon selectivity.

  6. Interferometric measurement method for Z2 invariants of time-reversal invariant topological insulators

    NASA Astrophysics Data System (ADS)

    Grusdt, Fabian; Abanin, Dmitry; Demler, Eugene

    2013-05-01

    Recently experiments with ultracold atoms started to explore topological phases in 1D optical lattices. While transport measurements are challenging in these systems, ways to directly measure topological quantum numbers using a combination of Bloch oscillations and Ramsey interferometry have been explored (Atala et al., arXiv:1212.0572). In this talk I will present ways to measure the Z2 topological quantum numbers of two and three dimensional time-reversal invariant (TR) topological insulators. In this case non-Abelian Bloch oscillations can be combined with Ramsey interferometry to map out the topological properties of a given band-structure. Our method is very general and works even in the presence of accidental degeneracies. The applicability of the scheme is discussed for different theoretically proposed implementations of TR topological insulators using ultracold atoms. F. G. is grateful to Harvard University for hospitality and acknowledges financial support from Graduate School Materials Science in Mainz (MAINZ).

  7. System and method for manipulating domain pinning and reversal in ferromagnetic materials

    SciTech Connect

    Silevitch, Daniel M.; Rosenbaum, Thomas F.; Aeppli, Gabriel

    2013-10-15

    A method for manipulating domain pinning and reversal in a ferromagnetic material comprises applying an external magnetic field to a uniaxial ferromagnetic material comprising a plurality of magnetic domains, where each domain has an easy axis oriented along a predetermined direction. The external magnetic field is applied transverse to the predetermined direction and at a predetermined temperature. The strength of the magnetic field is varied at the predetermined temperature, thereby isothermally regulating pinning of the domains. A magnetic storage device for controlling domain dynamics includes a magnetic hard disk comprising a uniaxial ferromagnetic material, a magnetic recording head including a first magnet, and a second magnet. The ferromagnetic material includes a plurality of magnetic domains each having an easy axis oriented along a predetermined direction. The second magnet is positioned adjacent to the magnetic hard disk and is configured to apply a magnetic field transverse to the predetermined direction.

  8. Synthesis of nanosilver particles by reverse micelle method and study of their bactericidal properties

    NASA Astrophysics Data System (ADS)

    Dung, Tran Thi Ngoc; Buu, Ngo Quoc; Viet Quang, Dang; Thi Ha, Huynh; Bang, Le Anh; Hoai Chau, Nguyen; Thi Ly, Nguyen; Trung, Nguyen Vu

    2009-09-01

    Nanosilver particles have been synthesized by the reverse micelle method, where AgNO3 was used as a silver ions source, NaBH4 and quercetin - as reducing agents, CTAB, SDOSS and AOT- as surfactants, while the stabilizer was Vietnamese chitosan. Studying the factors influencing the process of nanosilver particle formation, it was shown that the particle size of the nanosilver products depends on the concentration of the reaction components and their stoichiometric ratio. It was also shown that the reaction system using AOT surfactant is capable of producing nanosilver particles with smallest nanoparticles (phiav ~ 5 nm) and good particle-size distribution. The study on bactericidal activity of the nanosilver products indicated that the disinfecting solution with a nanosilver concentration of 3 ppm was able to inhibit all E.coli and Coliforms, TPC and fungi at 15 ppm, while Vibrio cholerae cells were inactivated completely with 0.5 ppm of nanosilver after 30 minutes exposition.

  9. Development of the simple and sensitive method for lipoxygenase assay in AOT/isooctane reversed micelles.

    PubMed

    Park, Kyung Min; Kim, Yu Na; Choi, Seung Jun; Chang, Pahn-Shick

    2013-06-01

    In this study, we investigated the possibility of reversed micelles, widely used as an enzyme reactor for lipases, for the determination of lipoxygenase activity. Although it is rapid and simple, reversed micelles have some limitations, such as interference by UV-absorbing materials and surfactant. Lipoxygenase activity in the reversed micelles was determined by reading the absorbance of the lipid hydroperoxidation product (conjugated diene) at 234 nm. Among surfactants and organic media, AOT and isooctane were most effective for the dioxygenation of linoleic acid in reversed micelles. The strong absorbance of AOT in the UV region is a major obstacle for the direct application of the AOT/isooctane reversed micelles to lipoxygenase activity determination. To prevent interference by AOT, we added an AOT removal step in the procedure for lipoxygenase activity determination in reversed micelles. The lipoxygenase activity was dependent on water content, and maximum activity was obtained at an R-value of 10. PMID:23411168

  10. A nodal discontinuous Galerkin method for reverse-time migration on GPU clusters

    NASA Astrophysics Data System (ADS)

    Modave, A.; St-Cyr, A.; Mulder, W. A.; Warburton, T.

    2015-11-01

    Improving both accuracy and computational performance of numerical tools is a major challenge for seismic imaging and generally requires specialized implementations to make full use of modern parallel architectures. We present a computational strategy for reverse-time migration (RTM) with accelerator-aided clusters. A new imaging condition computed from the pressure and velocity fields is introduced. The model solver is based on a high-order discontinuous Galerkin time-domain (DGTD) method for the pressure-velocity system with unstructured meshes and multirate local time stepping. We adopted the MPI+X approach for distributed programming where X is a threaded programming model. In this work we chose OCCA, a unified framework that makes use of major multithreading languages (e.g. CUDA and OpenCL) and offers the flexibility to run on several hardware architectures. DGTD schemes are suitable for efficient computations with accelerators thanks to localized element-to-element coupling and the dense algebraic operations required for each element. Moreover, compared to high-order finite-difference schemes, the thin halo inherent to DGTD method reduces the amount of data to be exchanged between MPI processes and storage requirements for RTM procedures. The amount of data to be recorded during simulation is reduced by storing only boundary values in memory rather than on disk and recreating the forward wavefields. Computational results are presented that indicate that these methods are strong scalable up to at least 32 GPUs for a three-dimensional RTM case.

  11. A Time-Reversed Reciprocal Method for Detecting High-frequency events in Civil Structures

    NASA Astrophysics Data System (ADS)

    Kohler, M. D.; Heaton, T. H.

    2007-12-01

    A new method that uses the properties of wave propagation reciprocity and time-reversed reciprocal Green's functions is presented for identifying high-frequency events that occur within engineered structures. Wave propagation properties of a seismic source in an elastic medium are directly applicable to structural waveform data. The number of structures with dense seismic networks embedded in them is increasing, making it possible to develop new approaches to identifying failure events such as fracturing welds that take advantage of the large number of recordings. The event identification method is based on the hypothesis that a database can be compiled of pre-event, source-receiver Green's functions using experimental sources. For buildings it is assumed that the source-time excitation is a delta function, proportional to the displacement produced at the receiver site. In theory, if all the Green's functions for a structure are known for a complete set of potential failure event locations, forward modeling can be used to compute a range of displacements to identify the correct Green's functions, locations, and source times from the suite of displacements that recorded actual events. The method is applied to a 17-story, steel, moment-frame building using experimentally applied impulse-force hammer sources. The building has an embedded, 72-channel, accelerometer array that is continuously recorded by 24-bit data loggers at 100 and 500 sps. The focus of this particular application is the identification of brittle- fractured welds of beam-column connections.

  12. Detecting a subsurface cylinder by a Time Reversal MUSIC like method

    NASA Astrophysics Data System (ADS)

    Solimene, Raffaele; Dell'Aversano, Angela; Leone, Giovanni

    2014-05-01

    In this contribution the problem of imaging a buried homogeneous circular cylinder is dealt with for a two-dimensional scalar geometry. Though the addressed geometry is extremely simple as compared to real world scenarios, it can be considered of interest for a classical GPR civil engineering applicative context: that is the subsurface prospecting of urban area in order to detect and locate buried utilities. A large body of methods for subsurface imaging have been presented in literature [1], ranging from migration algorithms to non-linear inverse scattering approaches. More recently, also spectral estimation methods, which benefit from sub-array data arrangement, have been proposed and compared in [2].Here a Time Reversal MUSIC (TRM) like method is employed. TRM has been initially conceived to detect point-like scatterers and then generalized to the case of extended scatterers [3]. In the latter case, no a priori information about the scatterers is exploited. However, utilities often can be schematized as circular cylinders. Here, we develop a TRM variant which use this information to properly tailor the steering vector while implementing TRM. Accordingly, instead of a spatial map [3], the imaging procedure returns the scatterer's parameters such as its center position, radius and dielectric permittivity. The study is developed by numerical simulations. First the free-space case is considered in order to more easily introduce the idea and the problem mathematical structure. Then the analysis is extended to the half-space case. In both situations a FDTD forward solver is used to generate the synthetic data. As usual in TRM, a multi-view/multi-static single-frequency configuration is considered and emphasis is put on the role played by the number of available sensors. Acknowledgement This work benefited from networking activities carried out within the EU funded COST Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar." [1] A. Randazzo and R

  13. Kinetic Analysis of Parallel-Consecutive First-Order Reactions with a Reversible Step: Concentration-Time Integrals Method

    ERIC Educational Resources Information Center

    Mucientes, A. E.; de la Pena, M. A.

    2009-01-01

    The concentration-time integrals method has been used to solve kinetic equations of parallel-consecutive first-order reactions with a reversible step. This method involves the determination of the area under the curve for the concentration of a given species against time. Computer techniques are used to integrate experimental curves and the method…

  14. An efficient higher-order PML in WLP-FDTD method for time reversed wave simulation

    NASA Astrophysics Data System (ADS)

    Wei, Xiao-Kun; Shao, Wei; Ou, Haiyan; Wang, Bing-Zhong

    2016-09-01

    Derived from a stretched coordinate formulation, a higher-order complex frequency shifted (CFS) perfectly matched layer (PML) is proposed for the unconditionally stable finite-difference time-domain (FDTD) method based on weighted Laguerre polynomials (WLPs). The higher-order PML is implemented with an auxiliary differential equation (ADE) approach. In order to further improve absorbing performance, the parameter values of stretching functions in the higher-order PML are optimized by the multi-objective genetic algorithm (MOGA). The optimal solutions can be chosen from the Pareto front for trading-off between two independent objectives. It is shown in a numerical test that the higher-order PML is efficient in terms of attenuating propagating waves and reducing late time reflections. Moreover, the higher-order PML can be placed very close to the wall when analyzing the channel characteristics of time reversal (TR) waves in a multipath indoor environment. Numerical examples of TR wave propagation demonstrate the availability of the proposed method.

  15. Bubbler---A Novel Ultra High Power Density Energy Harvesting Method Based on Reverse Electrowetting

    NASA Astrophysics Data System (ADS)

    Hsu, Tsung-Hsing

    A novel approach to direct conversion of mechanical energy into electrical energy has been proposed and experimentally and theoretically investigated. The method combines previously demonstrated reverse electrowetting on dielectric (REWOD) phenomenon with the fast self-oscillating process of bubble growth and collapse inside a conductive liquid placed in contact with a dielectric-covered electrode. Fast bubble dynamics, used in conjunction with REWOD, can enable extremely high power densities, in excess of 10 kW/m2. The method can be scaled in power from microwatts to tens of watts, and can enable direct coupling to a wide range of mechanical energy sources, which make it particularly attractive for energy harvesting applications. We believe that this approach can enable extraction of useful energy from various non-traditional sources including thermal expansion of buildings, human motion, and vehicle and machinery movement. Also, this makes the fabrication of small light-weight energy harvesting devices capable of producing a wide range of power outputs feasible.

  16. Bubbler: A Novel Ultra-High Power Density Energy Harvesting Method Based on Reverse Electrowetting

    NASA Astrophysics Data System (ADS)

    Hsu, Tsung-Hsing; Manakasettharn, Supone; Taylor, J. Ashley; Krupenkin, Tom

    2015-11-01

    We have proposed and successfully demonstrated a novel approach to direct conversion of mechanical energy into electrical energy using microfluidics. The method combines previously demonstrated reverse electrowetting on dielectric (REWOD) phenomenon with the fast self-oscillating process of bubble growth and collapse. Fast bubble dynamics, used in conjunction with REWOD, provides a possibility to increase the generated power density by over an order of magnitude, as compared to the REWOD alone. This energy conversion approach is particularly well suited for energy harvesting applications and can enable effective coupling to a broad array of mechanical systems including such ubiquitous but difficult to utilize low-frequency energy sources as human and machine motion. The method can be scaled from a single micro cell with 10-6 W output to power cell arrays with a total power output in excess of 10 W. This makes the fabrication of small light-weight energy harvesting devices capable of producing a wide range of power outputs feasible.

  17. Bubbler: A Novel Ultra-High Power Density Energy Harvesting Method Based on Reverse Electrowetting

    PubMed Central

    Hsu, Tsung-Hsing; Manakasettharn, Supone; Taylor, J. Ashley; Krupenkin, Tom

    2015-01-01

    We have proposed and successfully demonstrated a novel approach to direct conversion of mechanical energy into electrical energy using microfluidics. The method combines previously demonstrated reverse electrowetting on dielectric (REWOD) phenomenon with the fast self-oscillating process of bubble growth and collapse. Fast bubble dynamics, used in conjunction with REWOD, provides a possibility to increase the generated power density by over an order of magnitude, as compared to the REWOD alone. This energy conversion approach is particularly well suited for energy harvesting applications and can enable effective coupling to a broad array of mechanical systems including such ubiquitous but difficult to utilize low-frequency energy sources as human and machine motion. The method can be scaled from a single micro cell with 10−6 W output to power cell arrays with a total power output in excess of 10 W. This makes the fabrication of small light-weight energy harvesting devices capable of producing a wide range of power outputs feasible. PMID:26567850

  18. Reverse-phase HPLC method for measuring polarity distributions of natural organic matter.

    PubMed

    Namjesnik-Dejanovic, Ksenija; Cabaniss, Stephen E

    2004-02-15

    A reverse-phase high-pressure liquid chromatography (RP-HPLC) method was developed to measure the polarity distribution of natural organic matter (NOM) samples. The polarity distribution is obtained by calibrating an octadecyl bonded silica phase column and polar eluent with compounds of known octanol-water partition coefficient (Kow) and using this calibration curve to transform NOM retention times into an equivalent Kow. Polarity distributions treat the NOM samples as a complex mixture rather than summarizing the polarity in a single number. The method is sensitive, with UV detection allowing quantitation of samples with <5 mg of C/L. Individual chromatograms are acquired in <20 min, allowing much faster analysis on smaller samples than XAD resin separation or 13C NMR. Polarity distributions of 10 representative NOM isolates and 2 whole water samples indicate that NOM is generally hydrophilic in nature (log Kow < 2), although XAD-8 isolates are more hydrophobic than RO isolates from the same source. Hydrophilicity, as indicated by recovery from the HPLC column, is correlated to the elemental oxygen/carbon ratio but does not correlate strongly with molecular weight or 13C NMR aromaticity. PMID:14998025

  19. A rapid and reversible skull optical clearing method for monitoring cortical blood flow

    NASA Astrophysics Data System (ADS)

    Zhang, Chao; Zhao, Yanjie; Shi, Rui; Zhu, Dan

    2016-03-01

    In vivo cortex optical imaging is of great important for revealing both structural and functional architecture of brain with high temporal-spatial resolution. To reduce the limitation of turbid skull, researchers had to establish various skull windows or directly expose cortex through craniotomy. Here we developed a skull optical clearing method to make skull transparent. Laser speckle contrast imaging technique was used to monitor the cortical blood flow after topical treatment with the optical clearing agents. The results indicated that the image contrast increased gradually, and then maintained at a high level after 15 min for adult mice, which made the image quality and resolution of micro-vessels nearly approximate to those of exposed cortex. Both the cortical blood flow velocity almost kept constant after skull became transparent. Besides, the treatment of physiological saline on the skull could make skull return to the initial state again and the skull could become transparent again when SOCS retreated it. Thus, we could conclude that the skull optical clearing method was rapid, valid, reversible and safe, which provided us available approach for performing the cortical structural and functional imaging at high temporal-spatial resolution.

  20. Health monitoring of cuplok scaffold joint connection using piezoceramic transducers and time reversal method

    NASA Astrophysics Data System (ADS)

    Zhang, Liuyu; Wang, Chenyu; Huo, Linsheng; Song, Gangbing

    2016-03-01

    Cuplok scaffolds are widely used to form temporary supporting structures when constructing bridges and other structures all over the world. The safety and stability of cuplok scaffolds are important issues during construction. Cuplok scaffolds are subjected to various types of vibrations, which may loosen the cuplok connection, negatively impacting the stability of the structure and even leading to severe accidents. In this paper, the authors propose a time reversal (TR) method to monitor the looseness status of the cuplok connection by using stress wave-based active sensing. Lead zirconate titanate (PZT), a commonly used piezoceramic material with a strong piezoelectric effect, is employed. In the proposed approach, PZT patches are used as sensors and actuators to monitor the cuplok joint looseness. One PZT patch is bonded to the vertical bar and two PZT patches are bonded to the cross bars of the cuplok scaffold. The PZT patch on the vertical bar is used as an actuator to generate a stress wave and the other two PZT patches are used as sensors to detect the propagated waves through the cuplok connection, the looseness of which will directly impact the stress wave propagation. The TR method is used to analyse the transmitted signal between the PZT patches through the cuplok connection. By comparing the peak values of the TR focused signal, it can be found that the peak value increases as the tightness of the cuplok connection increases. Therefore, the peak value of the TR focused signal can be used to monitor the tightness of the cuplok connection. In addition, the experimental results demonstrated that the TR method is superior to the energy method in consistency, sensitivity and anti-noise properties.

  1. Comparison of the Posterior Capsule Rupture Rates Associated with Conventional (Start to Finish) Versus Reverse Methods of Teaching Phacoemulsification

    PubMed Central

    Suryawanshi, Milind; Gogate, Parikshit; Kulkarni, Anil N.; Biradar, Archana; Bhomaj, Pooja

    2016-01-01

    Purpose: Comparison of the rates of posterior capsule rupture (PCR) associated with conventional versus a reverse method of teaching phacoemulsification. Methods: Trainees were taught conventional (start-to-finish) phacoemulsification beginning with an incision (tunnel construction) to capsulorhexis, sculpting, nucleus cracking, segment removal, cortex aspiration, intraocular lens implantation, and viscoelastic removal. In the reverse method, after incision and capsulorhexis, the trainees were progressively taught viscoelastic wash, cortex aspiration, segment removal, nucleus cracking, sculpting, and intraocular lens implantation. Trainees from a Tertiary Eye Care Centre were classified as beginners, for their first 30 cases and then trainees for their next 70 surgeries. Data were collected on posterior capsular rent and vitreous loss during each step of training. Results: Thirty-two ophthalmic surgeons learning phacoemulsification surgery on 609 cataracts cases were supervised by 3 trainers. Fifteen beginners performed 287 surgeries using the conventional method, and 17 beginners performed 322 surgeries with the reverse method. The incidence of PCR was 18/287 (6.2%) with the conventional method and 15/322 (4.6%) with the reverse method (P = 0.38). PCR occurred during cortex aspiration (8/287, 2.8%) and segment removal (5/287, 1.7%) in the conventional method. PCR occurred during nucleus cracking, segment removal, and cortex aspiration (4/322 surgeries for each step, 1.2%). In the follow, 70 cases (trainees) there was no difference in PCR with either method (4.7% vs. 4.3%, P = 0.705). Conclusion: Conventional and reverse method for training phacoemulsification were both safe in a supervised setting. PMID:27162446

  2. A Reverse Tracking Method to Analyze the 1867 Keelung Tsunami Event

    NASA Astrophysics Data System (ADS)

    Lee, C.; Wu, T.; Tsai, Y.; KO, L.; Chuang, M.

    2013-12-01

    The 1867 Keelung tsunami is the only tsunami event verified by Taiwan government. This event caused serious damage and hundreds death toll in northern Taiwan, including the Keelung city, Jinshan and Patoutzu areas (Fig. 1). This event is not only recorded in many literatures, but also unveiled by sedimentary evidence. In addition, this event also indicates that the three nuclear power plants nearby are prone to tsunami attacks (Fig. 1). The previous studies consider that this tsunami might be generated by a Mw 7.0 earthquake which might occur along the Shanchiao Fault (Zheng et al, 2011). However, there is no evidence showing the relationship between these geological activities and the tsunami event. In this study, we intend to find the potential tsunami source through numerical analysis. We conducted series of numerical experiments by using sets of fault parameters from Mw 7.0 to Mw 8.0. However, none of them was able to explain the 7 m tsunami height observed in history and the sedimentary evidence found on the Hoping Island. Considering the steep bathymetry and intense volcanic activity along the Keelung coast, one reasonable hypothesis is that the earthquake or volcanic eruption triggered a submarine landslide which increased the tsunami height dramatically. In order to confirm this scenario, we performed the Reverse Tracking Method (RTM), based on the linear hypothesis of tsunami wave propagation, to find the possible locations of the tsunami sources (Fig. 1). The Cornell Multi-grid Coupled Tsunami Model (COMCOT) was then used to perform the tsunami simulations. We followed the Mw 7.0 earthquake proposed by Lin et al. (2006) and added the landslide disturbance (Watts et al., 2005). The source-scaling relationship proposed by Yen and Ma (2011) was used to determine the fault parameters. In addition to the Shanchiao Fault, five submarine volcanos and three submarine canyons were considered as the potential tsunami sources. The result shows that the 1867 tsunami

  3. Global trends in use of long-acting reversible and permanent methods of contraception: Seeking a balance.

    PubMed

    Joshi, Ritu; Khadilkar, Suvarna; Patel, Madhuri

    2015-10-01

    The global trend shows that the use of permanent contraception to prevent unintended pregnancy is high. Although the trend also shows a rise in the use of long-acting reversible methods, these are still underutilized despite having contraceptive as well as non-contraceptive benefits. Lack of knowledge among women, dependence on the provider for information, and provider bias for permanent contraception are cited as reasons for this reduced uptake. Training of healthcare providers and increased patient awareness about the effectiveness of long-acting reversible contraceptive methods will increase their uptake and help prevent unintended pregnancies. PMID:26433510

  4. PSRna: Prediction of small RNA secondary structures based on reverse complementary folding method.

    PubMed

    Li, Jin; Xu, Chengzhen; Wang, Lei; Liang, Hong; Feng, Weixing; Cai, Zhongxi; Wang, Ying; Cong, Wang; Liu, Yunlong

    2016-08-01

    Prediction of RNA secondary structures is an important problem in computational biology and bioinformatics, since RNA secondary structures are fundamental for functional analysis of RNA molecules. However, small RNA secondary structures are scarce and few algorithms have been specifically designed for predicting the secondary structures of small RNAs. Here we propose an algorithm named "PSRna" for predicting small-RNA secondary structures using reverse complementary folding and characteristic hairpin loops of small RNAs. Unlike traditional algorithms that usually generate multi-branch loops and 5[Formula: see text] end self-folding, PSRna first estimated the maximum number of base pairs of RNA secondary structures based on the dynamic programming algorithm and a path matrix is constructed at the same time. Second, the backtracking paths are extracted from the path matrix based on backtracking algorithm, and each backtracking path represents a secondary structure. To improve accuracy, the predicted RNA secondary structures are filtered based on their free energy, where only the secondary structure with the minimum free energy was identified as the candidate secondary structure. Our experiments on real data show that the proposed algorithm is superior to two popular methods, RNAfold and RNAstructure, in terms of sensitivity, specificity and Matthews correlation coefficient (MCC). PMID:27045556

  5. IR imaging simulation and analysis for aeroengine exhaust system based on reverse Monte Carlo method

    NASA Astrophysics Data System (ADS)

    Chen, Shiguo; Chen, Lihai; Mo, Dongla; Shi, Jingcheng

    2014-11-01

    The IR radiation characteristics of aeroengine are the important basis for IR stealth design and anti-stealth detection of aircraft. With the development of IR imaging sensor technology, the importance of aircraft IR stealth increases. An effort is presented to explore target IR radiation imaging simulation based on Reverse Monte Carlo Method (RMCM), which combined with the commercial CFD software. Flow and IR radiation characteristics of an aeroengine exhaust system are investigated, which developing a full size geometry model based on the actual parameters, using a flow-IR integration structured mesh, obtaining the engine performance parameters as the inlet boundary conditions of mixer section, and constructing a numerical simulation model of engine exhaust system of IR radiation characteristics based on RMCM. With the above models, IR radiation characteristics of aeroengine exhaust system is given, and focuses on the typical detecting band of IR spectral radiance imaging at azimuth 20°. The result shows that: (1) in small azimuth angle, the IR radiation is mainly from the center cone of all hot parts; near the azimuth 15°, mixer has the biggest radiation contribution, while center cone, turbine and flame stabilizer equivalent; (2) the main radiation components and space distribution in different spectrum is different, CO2 at 4.18, 4.33 and 4.45 micron absorption and emission obviously, H2O at 3.0 and 5.0 micron absorption and emission obviously.

  6. A facile photopolymerization method for fabrication of pH and light dual reversible stimuli-responsive surfaces.

    PubMed

    Wu, Shaopeng; Zhu, Xiaoqun; Yang, Jinliang; Nie, Jun

    2015-04-01

    Dual reversible surfaces with pH and light responsive properties were prepared via two-stage photopolymerization by grafting dimethylaminoethyl methacrylate (DMAEMA) and 2-methyl-4-phenylazo acrylate (MPA-Azo) on a substrate. The wettability of the modified surface could be reversibly controlled because of the protonation and deprotonation of DMAEMA at different pH values and the photoisomerization of MPA-Azo under UV irradiation at different wavelengths. This facile two-stage photopolymerization method has potential applications in fabrication of various external stimuli-responsive surfaces in the future. PMID:25715052

  7. The savory method can not green deserts or reverse climate change

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mr. Allan Savory addressed one of the major environmental challenges of our time – rapidly increasing atmospheric CO2 concentrations and climate warming - in a video presentation entitled, "How to green the world's deserts and reverse climate change" that was presented at the 2013 TED (Technology, E...

  8. Reverse transcription strand invasion based amplification (RT-SIBA): a method for rapid detection of influenza A and B.

    PubMed

    Eboigbodin, Kevin; Filén, Sanna; Ojalehto, Tuomas; Brummer, Mirko; Elf, Sonja; Pousi, Kirsi; Hoser, Mark

    2016-06-01

    Rapid and accurate diagnosis of influenza viruses plays an important role in infection control, as well as in preventing the misuse of antibiotics. Isothermal nucleic acid amplification methods offer significant advantages over the polymerase chain reaction (PCR), since they are more rapid and do not require the sophisticated instruments needed for thermal cycling. We previously described a novel isothermal nucleic acid amplification method, 'Strand Invasion Based Amplification' (SIBA®), with high analytical sensitivity and specificity, for the detection of DNA. In this study, we describe the development of a variant of the SIBA method, namely, reverse transcription SIBA (RT-SIBA), for the rapid detection of viral RNA targets. The RT-SIBA method includes a reverse transcriptase enzyme that allows one-step reverse transcription of RNA to complementary DNA (cDNA) and simultaneous amplification and detection of the cDNA by SIBA under isothermal reaction conditions. The RT-SIBA method was found to be more sensitive than PCR for the detection of influenza A and B and could detect 100 copies of influenza RNA within 15 min. The development of RT-SIBA will enable rapid and accurate diagnosis of viral RNA targets within point-of-care or central laboratory settings. PMID:27063012

  9. Paleointensity determinations during the Akaroa polarity reversal, New Zealand: New input from the multispecimen parallel differential pTRM method

    NASA Astrophysics Data System (ADS)

    Camps, P.; Fanjat, G.; Poidras, T.; Hoffman, K. A.; Carvallo, C.; kennedy, B.

    2011-12-01

    We resampled two polarity reversals of late Miocene age (~ 9 Ma) recorded successively in the Akaroa volcano (Hoffman, 1986, Nature). Our main objective was to check old paleointensity determinations (Sherwood & Shaw, 1986, J. Geomag. Geoelec.) that yielded stronger values during the transitional period than during stable periods that preceded and followed the reversals. This observation is opposite to what is generally observed. An increase in intensity during the reversal would provide an extreme example of increasing secular variation. However, the experimental method used for determining the paleointensity, method of Shaw, is strongly questioned by the scientific community. A check of these data by the conventional Thellier method was required. Unfortunately, among the 72 sampled flows, only 4 yielded rock magnetic properties well suited for Thellier determinations. In most of the flows, the presence of large Multi-Domain grains of Ti-magnetite, which are frequently associated with Ti-maghemite, precludes any Thellier paleointensity determinations. We implement the domain-state independent paleointensity method (the multispecimen parallel differential pTRM, Dekkers & Bohnel, 2006, EPSL; Fabian & Leonhardt, 2010, EPSL) for 16 lava flows in which the MD Ti-magnetite are not oxidized. Thellier paleointensities obtained do not confirm the Sherwood results but show more scattered values of the intensity even during the stable periods of the field. To complete the data, multispecimen mesearements are being to be done.

  10. Reverse current pulse method to restore uniform concentration profiles in ion-selective membranes. Part I: Galvanostatic pulse methods with decreased cycle time

    PubMed Central

    Zook, Justin M.; Lindner, Ernő

    2009-01-01

    The applications of ion-selective electrodes (ISEs) have been broadened through the introduction of galvanostatic current pulse methods in potentiometric analysis. An important requirement in these applications is the restoration of the uniform equilibrium concentration profiles in the ISE membrane between each measurement. The simplest restoration method is zero current relaxation, in which the membrane relaxes under open-circuit conditions in a diffusion-controlled process. This paper presents a novel restoration method using a reverse current pulse. An analytic model for this restoration method is derived to predict the concentration profiles inside ISE membranes following galvanostatic current pulses. This model allows the calculation of the voltage transients as the membrane voltage relaxes back towards its zero-current equilibrium value. The predicted concentration profiles and voltage transients are confirmed using spectroelectrochemical microscopy (SpECM). The reverse current restoration method described in this paper reduces the voltage drift and voltage error by 10 to 100 times compared to the zero current restoration method. Therefore, this new method provides faster and more reproducible voltage measurements in most chronopotentiometric ISE applications, such as improving the detection limit and determining concentrations and diffusion coefficients of membrane species. One limitation of the reverse current restoration method is that it cannot be used in a few applications that require background electrolyte loaded membranes without excess of lipophilic cation exchanger. PMID:19459603

  11. A reliable and reproducible method for the lipase assay in an AOT/isooctane reversed micellar system: modification of the copper-soap colorimetric method.

    PubMed

    Kwon, Chang Woo; Park, Kyung-Min; Choi, Seung Jun; Chang, Pahn-Shick

    2015-09-01

    The copper-soap method, which is based on the absorbance of a fatty acid-copper complex at 715 nm, is a widely used colorimetric assay to determine the lipase activity in reversed micellar system. However, the absorbance of the bis(2-ethylhexyl) sodium sulfosuccinate (AOT)-copper complex prevents the use of an AOT/isooctane reversed micellar system. An extraction step was added to the original procedure to remove AOT and eliminate interference from the AOT-copper complex. Among the solvents tested, acetonitrile was determined to be the most suitable because it allows for the generation of a reproducible calibration curve with oleic acid that is independent of the AOT concentrations. Based on the validation data, the modified method, which does not experience interference from the AOT-copper complex, could be a useful method with enhanced accuracy and reproducibility for the lipase assay. PMID:25842332

  12. Synthesis and characterization of α-NaYF4: Yb, Er nanoparticles by reverse microemulsion method

    NASA Astrophysics Data System (ADS)

    Gunaseelan, M.; Senthilselvan, J.

    2016-05-01

    A simple and cost effective reverse microemulsion system was newly designed to synthesis NaYF4:20%Yb,2%Er upconverting luminescent nanoparticles. XRD results confirms the cubic structure of NaYF4 nanophosphor in the as prepared condition without any other impurity phases. The as-prepared sample itself having highly crystalline nanoparticle with well dispersed uniform morphology is the advantage of this reverse microemulsion process. HRTEM images of as prepared and calcined samples revealed spherical nanoclusters morphology with size of ~210 nm and ~245 nm respectively. The characteristic absorption wavelength that occurs at 980 nm due to transition of energy levels 2F5/2 to 2F7/2 for Yb3+ rare earth ion in as prepared and calcined upconversion nanoparticle confirms the presence of Yb3+ by UV-Visible spectroscopy which can act as a sensitizer for photonic upconversion. Therefore the absorption at NIR region and emission spectrum at visible region suggests that NaYF4:20%Yb,2%Er is suitable for upcoversion process, due to its optical property and chemical stability this material also be useful for bio imaging applications.

  13. Implementation of the forward-reverse method for calculating the potential of mean force using a dynamic restraining protocol.

    PubMed

    Nategholeslam, Mostafa; Gray, C G; Tomberli, Bruno

    2014-12-11

    We present a new sampling and analysis scheme for calculating the potential of mean force (PMF) of systems studied by steered molecular dynamics simulations. This scheme, which we call the bin-passing method, is based on the forward-reverse (FR) method (due to I. Kosztin and co-workers, Kosztin et al. J. Chem. Phys. 2006, 124(6), 064106) and arguments based on the second law of thermodynamics. Applying the bin-passing method results in enhanced sampling, better separation of the reversible and irreversible work distributions, and faster convergence to the underlying PMF of the system under study. Post-simulation analysis is performed using a purpose-built software that we have made publicly available at https://github.com/1particle/bin-passing_analyzer under the terms of the GNU General Public License (version 3). Three examples are provided, for systems of varying sizes and complexities, to demonstrate the efficiency of this method and the quality of the results: for the dissociation PMF of NaCl in water, the bin-passing method obtains PMFs in excellent agreement with that obtained for the same system and using the same force-field through static (equilibrium) methods. The bin-passing method gives a very symmetric PMF for passage of a single water molecule through a DPPC bilayer, and the resultant PMF leads to permeability values in better agreement with experiments than those obtained through previous simulation studies. Finally, we consider the interaction of the antimicrobial peptide HHC-36 with two model membranes and employ the bin-passing method to obtain the PMFs for peptide adsorption to the membranes. The characteristics of these PMFs are consistent with the qualities established for the HHC-36 peptide through in vivo and in vitro experiments, as a non-toxic strong antimicrobial agent. PMID:25372312

  14. Low resource screening method of pre-cancerous lesions and its reversal by Triphala in teen-age Indian population

    PubMed Central

    Deshpande, Anshula; Tandon, Shobha; Deshpande, Neeraj

    2014-01-01

    Background: Cancer screening is the main weapon for early detection at a pre-invasive or premalignant stage. It has been reported that over 12 million people use some form of tobacco, which is one of the high risk factors and has hence become an alarming world-wide problem. Aim: To evaluate the effective diagnostic screening of disease in its early stage by inexpensive method and also to evaluate the effect of indigenous mouthrinse on reversal of pre-cancerous lesions. Materials and Methods: The screening for teenagers belonging to low socio-economic status was carried out. Suspected subjects were evaluated for the reversal of the lesions by use of Ayurvedic preparation as a mouthwash. From 13 to19 years working-child population of North India was selected for the study. Screening was performed by new method-visual inspection with acetic acid. The positive subjects were further investigated by pap smear and biopsy was done as a confirmatory histopathological report. In second phase, the subjects showing positive lesions were advised indigenous anti-cancer mouth rinse and its effect was evaluated after 6 month and 9 month of prescribing the rinse. Results: The total 1095 children were screened (831 boys and 264 girls). Out of total 34 teenager boys were diagnosed, as acetowhite positive lesion. All the acetowhite positive lesions were found exclusively in males. Histological findings after 9 month use of Triphala mouth rinse revealed no changes in cells in 23 (85.2%), hyperkeratinization in 2 (7.4%), hyperkeratinization and spongiosis was evident in 1 (3.7%), mild pleomorphism in 1 (3.7%) patient. Comparative evaluation from 0-9 month showed statistically highly significant test (P < 0.01). Conclusion: Use of different forms of tobacco and betel nut showed convincing relationship between developments of oral pre-cancerous lesions. Triphala was found to have great potential for reversal of these lesions. PMID:25558161

  15. Reversible Semiconductor-To-Metal Transition Of VOx Thin Films Prepared By The Sol-Gel Method

    NASA Astrophysics Data System (ADS)

    Hou, Lisong; Lu, Song W.; Gan, Fuxi

    1989-12-01

    Using VO(i-0C3H7)3 as the starting material VOx thin films have been prepared on silica glass substrates by the Sol-Gel dip-coating method and the subsequent heat treatment under vacuum conditions. These thin films show a reversible semiconductor-to-metal phase transition at 67°C. The change of transmittance in the near IR region due to the phase transition is as high as 50%. Infrared spectra show that the value of x is close to 2.

  16. A reversed-phase high performance liquid chromatography method for quantification of methotrexate in cancer patients serum.

    PubMed

    Li, Yuan-dong; Li, Yan; Liang, Ning-sheng; Yang, Fan; Kuang, Zhi-peng

    2015-10-01

    A simple, rapid and sensitive reversed-phase high performance liquid chromatography (HPLC) method has been developed for the determination of methotrexate in human serum. After deproteinization of the serum with 40% silver nitrate solution, methotrexate and internal standard (IS) were separated on a reversed-phase column with a mobile phase consisting of 10mM sodium phosphate buffer (pH6.40)-methanol (78:22%, v/v) and ultraviolet detection at 310nm. The linearity is evaluated by a calibration curve in the concentration range of 0.05-10.0μg/mL and presented a correlation coefficient of 0.9995. The absolute recoveries were 97.52±3.9% and 96.87±3.7% for methotrexate and ferulic acid (internal standard), respectively. The intra- and inter-day precision were less 6.19 and 5.89%, respectively (n=6). The limit of quantitation was 0.02μg/mL and the limit of detection was 0.006μg/mL. The complete analysis was achieved less than 10min with no interference from endogenous components or 22 examined drugs. This method was validated by using serum samples from high-dose methotrexate treated patients with osteosarcoma, breast cancer, acute leukemia and lymphoma. The method was demonstrated to be a simple, rapid and reliable approach in quantification of methotrexate in serum samples from patients with high-dose methotrexate therapy. PMID:26319303

  17. Reversible Thermoset Adhesives

    NASA Technical Reports Server (NTRS)

    Mac Murray, Benjamin C. (Inventor); Tong, Tat H. (Inventor); Hreha, Richard D. (Inventor)

    2016-01-01

    Embodiments of a reversible thermoset adhesive formed by incorporating thermally-reversible cross-linking units and a method for making the reversible thermoset adhesive are provided. One approach to formulating reversible thermoset adhesives includes incorporating dienes, such as furans, and dienophiles, such as maleimides, into a polymer network as reversible covalent cross-links using Diels Alder cross-link formation between the diene and dienophile. The chemical components may be selected based on their compatibility with adhesive chemistry as well as their ability to undergo controlled, reversible cross-linking chemistry.

  18. Simple method for the analysis of food dyes on reversed-phase thin-layer plates.

    PubMed

    Oka, H; Ikai, Y; Kawamura, N; Yamada, M; Inoue, H; Ohno, T; Inagaki, K; Kuno, A; Yamamoto, N

    1987-12-18

    A technique for the determination of food dyes using reversed-phase thin-layer chromatography on octadecyl-modified silica is described. A solvent system containing 5.0% aqueous sodium sulphate solution enables good separation of the food dyes. Their separation is dependent on the pH of the solvent system, good separation among all dyes being obtained between pH 6.0 and 7.0. The determination of thirteen dyes can be achieved by a combination of methanol-acetonitrile-5.0% aqueous sodium sulphate solution (3:3:10) (solvent system A) and methanol-methyl ethyl ketone-5.0% aqueous sodium sulphate solution (1:1:1) (solvent system B). Solvent system A was used for the determination of Tartrazine, Amaranth, Indigo Carmine, New Coccine, Sunset Yellow FCF, Allura Red AC, Fast Green FCF and Brilliant Blue FCF and for the screening of Acid Red (R-106), Eosin (R-103), Erythrosin (R-3), Rose Bengale (R-105) and Phloxine (R-104). When the spots of R-3, R-103, R-104, R-105 and R-106 appear on the plate, their determination can be achieved by using solvent system B. Each calibration graph was linear between 0.2 and 1.0 micrograms. PMID:3443633

  19. Click-Based Libraries of SFTI-1 Peptides: New Methods Using Reversed-Phase Silica.

    PubMed

    Cistrone, Philip A; Dawson, Philip E

    2016-03-14

    Performing sequential reactions for the orthogonal derivatization of peptides in solution often requires intermediate handling and purification steps. To solve these problems, we have exploited the distinct adsorption kinetics of peptides toward particulate reversed-phase (RP) C18 silica material, enabling consecutive reactions to be performed without intermediate elution. To illustrate this approach, sequential CuAAC/click reactions were used to modify an analog of the bicyclic peptide sunflower trypsin inhibitor 1 (SFTI-1), a potent scaffold for trypsin and chymotrypsin-like enzyme inhibitors. The SFTI-1 scaffold was synthesized containing both β-azido alanine and propargyl glycine residues. Despite the mutual reactivity of these groups, site isolation on RP silica enabled consecutive click reactions and associated washing steps to be performed while the peptide remained immobilized. Importantly, this approach eliminated side products that could form between two peptides or within a single peptide. These studies suggest a broad utility for RP silica in solving both peptide handling problems and in improving synthetic workflows. PMID:26914614

  20. Advanced feedback control methods in EXTRAP T2R reversed field pinch

    SciTech Connect

    Yadikin, D.; Brunsell, P. R.; Paccagnella, R.

    2006-07-15

    Previous experiments in the EXTRAP T2R reversed field pinch device have shown the possibility of suppression of multiple resistive wall modes (RWM). A feedback system has been installed in EXTRAP T2R having 100% coverage of the toroidal surface by the active coil array. Predictions based on theory and the previous experimental results show that the number of active coils should be sufficient for independent stabilization of all unstable RWMs in the EXTRAP T2R. Experiments using different feedback schemes are performed, comparing the intelligent shell, the fake rotating shell, and the mode control with complex feedback gains. Stabilization of all unstable RWMs throughout the discharge duration of t{sub d}{approx_equal}10{tau}{sub w} is seen using the intelligent shell feedback scheme. Mode rotation and the control of selected Fourier harmonics is obtained simultaneously using the mode control scheme with complex gains. Different sensor signals are studied. A feedback system with toroidal magnetic field sensors could have an advantage of lower feedback gain needed for the RWM suppression compared to the system with radial magnetic field sensors. In this study, RWM suppression is demonstrated, using also the toroidal field component as a sensor signal in the feedback system.

  1. Ultrasound imaging of extended targets using a windowed time-reversal MUSIC method

    NASA Astrophysics Data System (ADS)

    Labyed, Yassin; Huang, Lianjie

    2012-03-01

    Time-reversal with Multiple Signal Classification (TR-MUSIC) is an ultrasound imaging algorithm for detecting small targets embedded in a medium. This technique can produce images with subwavelength resolution when the targets are pointlike, and when the number of targets is fewer than the number of transducer elements used to image the medium. In this experimental study, we evaluate the performance of the TR-MUSIC algorithm when the interrogated medium contains extended targets that cannot be considered as point scatterers. We construct tissue-mimicking phantoms embedded with distributed glass spheres. We show that the quality of the phantom images obtained using the TR-MUSIC algorithm decreases with increasing sphere size. However, significant improvement is achieved when the image plane is divided into sub-regions, where each sub-region is imaged separately. The windowed TR-MUSIC algorithm accurately locates the spheres (extended targets), but the images do not provide quantitative information about the shape and reflectivity of the spheres.

  2. Advanced feedback control methods in EXTRAP T2R reversed field pinch

    NASA Astrophysics Data System (ADS)

    Yadikin, D.; Brunsell, P. R.; Paccagnella, R.

    2006-07-01

    Previous experiments in the EXTRAP T2R reversed field pinch device have shown the possibility of suppression of multiple resistive wall modes (RWM). A feedback system has been installed in EXTRAP T2R having 100% coverage of the toroidal surface by the active coil array. Predictions based on theory and the previous experimental results show that the number of active coils should be sufficient for independent stabilization of all unstable RWMs in the EXTRAP T2R. Experiments using different feedback schemes are performed, comparing the intelligent shell, the fake rotating shell, and the mode control with complex feedback gains. Stabilization of all unstable RWMs throughout the discharge duration of td≈10τw is seen using the intelligent shell feedback scheme. Mode rotation and the control of selected Fourier harmonics is obtained simultaneously using the mode control scheme with complex gains. Different sensor signals are studied. A feedback system with toroidal magnetic field sensors could have an advantage of lower feedback gain needed for the RWM suppression compared to the system with radial magnetic field sensors. In this study, RWM suppression is demonstrated, using also the toroidal field component as a sensor signal in the feedback system.

  3. `Reverse Chemical Evolution': A New Method to Search for Thermally Stable Biopolymers

    NASA Astrophysics Data System (ADS)

    Mitsuzawa, Shigenobu; Yukawa, Tetsuyuki

    2003-04-01

    The primitive sea on Earth may have had high-temperature and high-pressure conditions similar to those in present-day hydrothermal environments. If life originated in the hot sea, thermal stability of the constituent molecules would have been necessary. Thus far, however, it has been reported that biopolymers hydrolyze too rapidly to support life at temperatures of more than 200 °C. We herein propose a novel approach, called reverse chemical evolution, to search for biopolymers notably more stable against thermal decomposition than previously reported. The essence of the approach is that hydrolysis of a protein or functional RNA (m-, t-, r-RNA) at high temperature and high pressure simulating the ancient sea environment may yield thermally stable peptides or RNAs at higher concentrations than other peptides or RNAs. An experimental test hydrolyzing bovine ribonuclease A in aqueous solution at 205 °C and 25 MPa yielded three prominently stable molecules weighing 859, 1030 and 695 Da. They are thermally some tens or hundreds times more stable than a polyglycine of comparable mass. Sequence analyses of the 859- and 1030-Da molecules revealed that they are a heptapeptide and its homologue, respectively, elongated by two amino acids at the N-terminal region, originally embedded as residues 112-120 in the protein. They consist mainly of hydrophobic amino acids.

  4. Simultaneous analysis method for polar and non-polar ginsenosides in red ginseng by reversed-phase HPLC-PAD.

    PubMed

    Lee, Sa-Im; Kwon, Ha-Jeong; Lee, Yong-Moon; Lee, Je-Hyun; Hong, Seon-Pyo

    2012-02-23

    The paper describes the development of a simultaneous determination method for polar and non-polar ginsenosides in red ginseng with a reversed-phase high-performance liquid chromatography-pulsed amperometric detection method. This method could be applied directly without any pretreatment steps and enabled the performance of highly sensitive analysis within 1h. The detection (S/N=3) and quantification (S/N=10) limits for the ginsenosides ranged 0.02-0.10 ng and 0.1-0.3 ng, respectively. The linear regression coefficients ranged 0.9975-0.9998. Intra- and inter-day precisions were <9.91%. The mean recoveries ranged 98.08-103.06%. The total amount of ginsenosides in the hairy root of red ginseng was higher than that in the main root. PMID:22119615

  5. A reverse Monte Carlo method for deriving optical constants of solids from reflection electron energy-loss spectroscopy spectra

    SciTech Connect

    Da, B.; Sun, Y.; Ding, Z. J.; Mao, S. F.; Zhang, Z. M.; Jin, H.; Yoshikawa, H.; Tanuma, S.

    2013-06-07

    A reverse Monte Carlo (RMC) method is developed to obtain the energy loss function (ELF) and optical constants from a measured reflection electron energy-loss spectroscopy (REELS) spectrum by an iterative Monte Carlo (MC) simulation procedure. The method combines the simulated annealing method, i.e., a Markov chain Monte Carlo (MCMC) sampling of oscillator parameters, surface and bulk excitation weighting factors, and band gap energy, with a conventional MC simulation of electron interaction with solids, which acts as a single step of MCMC sampling in this RMC method. To examine the reliability of this method, we have verified that the output data of the dielectric function are essentially independent of the initial values of the trial parameters, which is a basic property of a MCMC method. The optical constants derived for SiO{sub 2} in the energy loss range of 8-90 eV are in good agreement with other available data, and relevant bulk ELFs are checked by oscillator strength-sum and perfect-screening-sum rules. Our results show that the dielectric function can be obtained by the RMC method even with a wide range of initial trial parameters. The RMC method is thus a general and effective method for determining the optical properties of solids from REELS measurements.

  6. Preparation of Nonionic Vesicles Using the Supercritical Carbon Dioxide Reverse Phase Evaporation Method and Analysis of Their Solution Properties.

    PubMed

    Yamaguchi, Shunsuke; Tsuchiya, Koji; Sakai, Kenichi; Abe, Masahiko; Sakai, Hideki

    2016-01-01

    We have previously reported a new preparation method for liposomes using supercritical carbon dioxide (scCO2) as a solvent, referred to as the supercritical carbon dioxide reverse phase evaporation (scRPE) method. In our previous work, addition of ethanol to scCO2 as a co-solvent was needed, because lipid molecules had to be dissolved in scCO2 to form liposomes. In this new study, niosomes (nonionic surfactant vesicles) were prepared from various nonionic surfactants using the scRPE method. Among the nonionic surfactants tested were polyoxyethylene (6) stearylether (C18EO6), polyoxyethylene (5) phytosterolether (BPS-5), polyoxyethylene (6) sorbitan stearylester (TS-106V), and polyoxyethylene (4) sorbitan stearylester (Tween 61). All these surfactants have hydrophilic-lipophilic balance values (HLBs) around 9.5 to 9.9, and they can all form niosomes using the scRPE method even in the absence of ethanol. The high solubility of these surfactants in scCO2 was shown to be an important factor in yielding niosomes without ethanol addition. The niosomes prepared with the scRPE method had higher trapping efficiencies than those prepared using the conventional Bangham method, since the scRPE method gives a large number of unilamellar vesicles while the Bangham method gives multilamellar vesicles. Polyoxyethylene-type nonionic surfactants with HLB values from 9.5 to 9.9 were shown to be optimal for the preparation of niosomes with the scRPE method. PMID:26666274

  7. A METHOD TO REMOVE ENVIRONMENTAL INHIBITORS PRIOR TO THE DETECTION OF WATERBORNE ENTERIC VIRUSES BY REVERSE TRANSCRIPTION-POLYMERASE CHAIN REACTION

    EPA Science Inventory

    A method was developed to remove environmental inhibitors from sample concentrates prior to detection of human enteric viruses using the reverse transcription-polymerase chain reaction (RT-PCR).Environmental inhibitors, concentrated along with viruses during water sample processi...

  8. Optical properties of CdS and CdS/ZnS quantum dots synthesized by reverse micelle method

    NASA Astrophysics Data System (ADS)

    Lien, Vu Thi Kim; Viet Ha, Chu; Tien Ha, Le; Nhu Dat, Nguyen

    2009-09-01

    The CdS and CdS/ZnS semiconductor quantum dots have been synthesized by reverse micelle method using sodium bis (2-ethylhexyl) sulfosuccinate (AOT) surfactant agent. The quantum dot diameter is about 2.5 to 4 nm depending on the concentration of the surfactant agent. It is interesting that, in contrast to other colloidal methods, the size of quantum dots does not depend on the growth time. The absorption spectra of CdS quantum dots show the narrow size distribution. The photoluminescence (PL) spectra include two bands, the intrinsic emission of CdS nanocrystals and the emission of surface states. There is noticeable increase of the PL intensity and subsequent photostability of CdS/ZnS core-shell quantum dots in comparison with CdS quantum dots without the ZnS shell.

  9. Variable grid-size and time-step finite difference method for seismic forward modeling and reverse-time migration

    NASA Astrophysics Data System (ADS)

    Wang, Yue

    A new variable grid-size and time-step finite-difference (FD) method is developed and applied to three different geophysical problems: simulation of tube waves in boreholes, three-dimensional (3-D) ground-motion simulation in sedimentary basin models, and reverse-time migration of multicomponent data. Unlike the conventional FD method, which uses a fixed grid-size and time-step for the entire model region, spatially variable grid-sizes and time-steps are used to achieve the optimal computational efficiency. For tube wave simulations, a fine grid-spacing is used for simulation inside the borehole region, while a coarse grid is used in the exterior region. While the stability condition requires a very fine time step for the fine grid, a variable time-step method provides coarse time steps for simulation in the coarse grid. Variable grid-size and time-step changes are used to achieve both accuracy and efficiency in the simulations. Numerical tests are performed for the Bayou Choctaw salt-flank model with different borehole models. The results show the important borehole effects on the seismic wavefield for a realistic source bandwidth. The combination of variable grid-size and time-step methods reduces computational costs by several orders of magnitude for the borehole models. Viscoelastic 3-D simulations are performed for a three-layer Salt Lake basin model. The near-surface unconsolidated layer is modeled with a fine grid, and the deep part of the model is modeled by a coarse grid. Simulation results show that the 3-D basin features and the shallow layer significantly affect the amplitude and duration time of the ground motion. In the elastic case, the approximation by 2-D modeling is insufficient to simulate the 3-D ground motion response. A basin model without a shallow low-velocity layer underestimates the ground motion duration and cumulative kinetic energy by 50% or more. The simulation of a Bingham Mine blast suggests that a lower S-velocity should be used to

  10. Statistical methods and software for the analysis of highthroughput reverse genetic assays using flow cytometry readouts

    PubMed Central

    Hahne, Florian; Arlt, Dorit; Sauermann, Mamatha; Majety, Meher; Poustka, Annemarie; Wiemann, Stefan; Huber, Wolfgang

    2006-01-01

    Highthroughput cell-based assays with flow cytometric readout provide a powerful technique for identifying components of biologic pathways and their interactors. Interpretation of these large datasets requires effective computational methods. We present a new approach that includes data pre-processing, visualization, quality assessment, and statistical inference. The software is freely available in the Bioconductor package prada. The method permits analysis of large screens to detect the effects of molecular interventions in cellular systems. PMID:16916453

  11. A validated reversed phase HPLC method for the determination of process-related impurities in almotriptan malate API.

    PubMed

    Kumar, A Phani; Ganesh, V R L; Rao, D V Subba; Anil, C; Rao, B Venugopala; Hariharakrishnan, V S; Suneetha, A; Sundar, B Syama

    2008-03-13

    An isocratic reversed phase liquid chromatographic (RP-LC) method has been developed and subsequently validated for the determination of almotriptan malate and its process-related impurities. Separation was achieved with a Phenomenex, Gemini, C-18 column and sodium phosphate buffer (pH adjusted to 7.6): acetonitrile (80:20, v/v) as eluent, at a flow rate of 1.5 mL/min. UV detection was performed at 227 nm. The method is simple, rapid, selective, accurate and stability indicating. The described method is linear over a range of LOQ, 1.5 ug/mL (150% of the specification limit) for all the process-related impurities. The method precision for the determination of related compounds was below 1.0% R.S.D. The accuracy of the method demonstrated at 4 levels in the range of 25-150% of the specification limit and the recovery of impurities were found to be in the range of 96-102%. The method is useful in the quality control of bulk manufacturing. PMID:18191357

  12. Vasectomy reversal.

    PubMed

    Belker, A M

    1987-02-01

    A vasovasostomy may be performed on an outpatient basis with local anesthesia, but also may be performed on an outpatient basis with epidural or general anesthesia. Local anesthesia is preferred by most of my patients, the majority of whom choose this technique. With proper preoperative and intraoperative sedation, patients sleep lightly through most of the procedure. Because of the length of time often required for bilateral microsurgical vasoepididymostomy, epidural or general anesthesia and overnight hospitalization are usually necessary. Factors influencing the preoperative choice for vasovasostomy or vasoepididymostomy in patients undergoing vasectomy reversal are considered. The preoperative planned choice of vasovasostomy or vasoepididymostomy for patients having vasectomy reversal described herein does not have the support of all urologists who regularly perform these procedures. My present approach has evolved as the data reported in Tables 1 and 2 have become available, but it may change as new information is evaluated. However, it offers a logical method for planning choices of anesthesia and inpatient or outpatient status for patients undergoing vasectomy reversal procedures. PMID:3811050

  13. Reversing adhesion with light: a general method for functionalized bead release from cells.

    PubMed

    Goulet-Hanssens, Alexis; Magdesian, Margaret H; Lopez-Ayon, G Monserratt; Grutter, Peter; Barrett, Christopher J

    2016-07-19

    Coated beads retain great importance in the study of cell adhesion and intracellular communication; we present a generally applicable method permitting spatiotemporal control of bead adhesion from cells. Herein we demonstrate in vitro release of a poly-d-lysine (PDL) layer from anionic polystyrene beads, allowing complete bead release from rat cortical neurons post-adhesion. PMID:27165466

  14. Method and apparatus for remote sensing of molecular species at nanoscale utilizing a reverse photoacoustic effect

    SciTech Connect

    Su, Ming; Thundat, Thomas G; Hedden, David

    2010-02-23

    A method and apparatus for identifying a sample, involves illuminating the sample with light of varying wavelengths, transmitting an acoustic signal against the sample from one portion and receiving a resulting acoustic signal on another portion, detecting a change of phase in the acoustic signal corresponding to the light of varying wavelengths, and analyzing the change of phase in the acoustic signal for the varying wavelengths of illumination to identify the sample. The apparatus has a controlled source for illuminating the sample with light of varying wavelengths, a transmitter for transmitting an acoustic wave, a receiver for receiving the acoustic wave and converting the acoustic wave to an electronic signal, and an electronic circuit for detecting a change of phase in the acoustic wave corresponding to respective ones of the varying wavelengths and outputting the change of phase for the varying wavelengths to allow identification of the sample. The method and apparatus can be used to detect chemical composition or visual features. A transmission mode and a reflection mode of operation are disclosed. The method and apparatus can be applied at nanoscale to detect molecules in a biological sample.

  15. A novel reverse phase high-performance liquid chromatography method for standardization of Orthosiphon stamineus leaf extracts

    PubMed Central

    Saidan, Noor Hafizoh; Aisha, Abdalrahim F.A.; Hamil, Mohd Shahrul Ridzuan; Majid, Amin Malik Shah Abdul; Ismail, Zhari

    2015-01-01

    Background: Orthosiphon stamineus Benth. (Lamiaceae) is a traditional medicinal plant which has been used in treating various ailments such as kidney diseases, bladder inflammation, arthritis and diabetes. The leaves contain high concentration of phenolic compounds, thus, rosmarinic acid (RA), 3’-hydroxy-5, 6, 7, 4’-tetramethoxyflavone (TMF), sinensetin (SIN) and eupatorin (EUP) were chosen as a marker compounds for standardization of various O. stamineus leaf extracts. Objective: The aim was to develop and validate a new high-performance liquid chromatography (HPLC) method for quantification of 4 marker compounds (RA, TMF, SIN, EUP) in various O. stamineus leaf extracts. Materials and Methods: The method was developed and validated using RP-HPLC-diode-array detection at 320 nm for accuracy, precision and limits of detection and was applied for quantification of it markers in five different extracts prepared in solvents with increasing polarity, using a gradient mobile phase 0.1% formic acid: Acetonitrile at a flow rate of 1 ml/min on reverse phase acclaim polar advantage II C18 column (3 μm, 3 × 150 mm) with 18 min separation time. Results: The developed method provided satisfactory precision, and the accuracy of this method was in the range of 90.2% to 105.5%. All of 4 compounds showed good linearity at R2 > 0.999. Conclusion: The developed method is a simple, cost effective with shorter run time (18 min) in comparison to previous methods (30 min) and utilization of environmental-friendly solvents system. Therefore, this method has the potential to replace currently used methods in the routine standardization work of O. stamineus extracts, raw materials and its commercial products. PMID:25598631

  16. Synthesis and characterization of nanophase zirconia : reverse micelle method and neutron scattering study.

    SciTech Connect

    Li, X.

    1998-11-23

    Zirconia is an important transition-metal oxide for catalytic applications. It has been widely used in automotive exhaust treatment, methanol synthesis, isomerization, alkylation, etc. [1]. Nanophase materials have unique physiochemical properties such as quantum size effects, high surface area, uniform morphology, narrow size distribution, and improvement of sintering rates[2]. Microemulsion method provides the means for controlling the microenvironment under which specific chemical reactions may occur in favoring the formation of homogeneous, nanometer-size particles. In this paper, we report the synthesis of nanophase zirconia and the characterization of the microemulsions as well as the powders by small- and wide-angle neutron scattering techniques.

  17. Determination of Cefadroxil in Tablet/Capsule formulations by a validated Reverse Phase High Performance Liquid Chromatographic method.

    PubMed

    Rahim, Najia; Naqvi, Syed Baqir-Shyum; Shakeel, Sadia; Iffat, Wajiha; Muhammad, Iyad Naeem

    2015-07-01

    An innovative, selective and rapid reversed phase High Performance Liquid Chromatographic (RP-HPLC) method for the analysis of cefadroxil in bulk material and oral solid dosage forms has been developed and validated. The chromatographic system consisted of Sil-20A auto sampler, LC-20A pump and SPD-20A UV/visible detector. The separation was achieved by C18 column at ambient temperature with a mobile phase consisting of methanol: Phosphate buffer (10: 90) at a flow rate of 1.5 ml/min. The method is reproducible, repeatable (%RSD for intra-day and inter-day ranged between 1.75-5.33% and 0.58-2.69%) and linear (R2=0.9935). The LOD and LOQ of the method were 0.5 and 1.0 μg/ml, respectively. The present RP-HPLC method was found to be sensitive, accurate, precise, rapid and cost effective that can be efficiently used in QC/QA laboratories for routine analysis of the raw materials as well as oral dosage formulations of cefadroxil. PMID:26142506

  18. An Evaluation of Active Learning Causal Discovery Methods for Reverse-Engineering Local Causal Pathways of Gene Regulation

    PubMed Central

    Ma, Sisi; Kemmeren, Patrick; Aliferis, Constantin F.; Statnikov, Alexander

    2016-01-01

    Reverse-engineering of causal pathways that implicate diseases and vital cellular functions is a fundamental problem in biomedicine. Discovery of the local causal pathway of a target variable (that consists of its direct causes and direct effects) is essential for effective intervention and can facilitate accurate diagnosis and prognosis. Recent research has provided several active learning methods that can leverage passively observed high-throughput data to draft causal pathways and then refine the inferred relations with a limited number of experiments. The current study provides a comprehensive evaluation of the performance of active learning methods for local causal pathway discovery in real biological data. Specifically, 54 active learning methods/variants from 3 families of algorithms were applied for local causal pathways reconstruction of gene regulation for 5 transcription factors in S. cerevisiae. Four aspects of the methods’ performance were assessed, including adjacency discovery quality, edge orientation accuracy, complete pathway discovery quality, and experimental cost. The results of this study show that some methods provide significant performance benefits over others and therefore should be routinely used for local causal pathway discovery tasks. This study also demonstrates the feasibility of local causal pathway reconstruction in real biological systems with significant quality and low experimental cost. PMID:26939894

  19. A New Long-Term Reversible Contraception Method: Sexual and Metabolic Impact

    PubMed Central

    Visconti, F; Zullo, F; Marra, M.L; De Masellis, G; Caiazza, M; Cibarelli, F; Buonomo, B; Guida, M.

    2012-01-01

    Background Data relating to the influence of hormonal contraception on sexual life are conflicting and mostly they refer to oral contraceptives. In this study we evaluated the effect of a long-acting contraceptive on sexual function, metabolism and bleeding pattern variations. Methods: 23 women with a permanent partner and an active sexual life completed a specific questionnaire at the start of the study and after cycles 3 and 6 of contraceptive use; a blood sample was performed or metabolic evaluation and a “bleeding calendar” was compiled by the patients. Conclusion: There is an increase of quality and frequency of sexual function after 6 month of contraception; there aren’t significant change in metabolic parameters and is detectable a modification of bleeding patterns. PMID:23905067

  20. Inferring Regulatory Networks from Experimental Morphological Phenotypes: A Computational Method Reverse-Engineers Planarian Regeneration

    PubMed Central

    Lobo, Daniel; Levin, Michael

    2015-01-01

    Transformative applications in biomedicine require the discovery of complex regulatory networks that explain the development and regeneration of anatomical structures, and reveal what external signals will trigger desired changes of large-scale pattern. Despite recent advances in bioinformatics, extracting mechanistic pathway models from experimental morphological data is a key open challenge that has resisted automation. The fundamental difficulty of manually predicting emergent behavior of even simple networks has limited the models invented by human scientists to pathway diagrams that show necessary subunit interactions but do not reveal the dynamics that are sufficient for complex, self-regulating pattern to emerge. To finally bridge the gap between high-resolution genetic data and the ability to understand and control patterning, it is critical to develop computational tools to efficiently extract regulatory pathways from the resultant experimental shape phenotypes. For example, planarian regeneration has been studied for over a century, but despite increasing insight into the pathways that control its stem cells, no constructive, mechanistic model has yet been found by human scientists that explains more than one or two key features of its remarkable ability to regenerate its correct anatomical pattern after drastic perturbations. We present a method to infer the molecular products, topology, and spatial and temporal non-linear dynamics of regulatory networks recapitulating in silico the rich dataset of morphological phenotypes resulting from genetic, surgical, and pharmacological experiments. We demonstrated our approach by inferring complete regulatory networks explaining the outcomes of the main functional regeneration experiments in the planarian literature; By analyzing all the datasets together, our system inferred the first systems-biology comprehensive dynamical model explaining patterning in planarian regeneration. This method provides an automated

  1. Inferring regulatory networks from experimental morphological phenotypes: a computational method reverse-engineers planarian regeneration.

    PubMed

    Lobo, Daniel; Levin, Michael

    2015-06-01

    Transformative applications in biomedicine require the discovery of complex regulatory networks that explain the development and regeneration of anatomical structures, and reveal what external signals will trigger desired changes of large-scale pattern. Despite recent advances in bioinformatics, extracting mechanistic pathway models from experimental morphological data is a key open challenge that has resisted automation. The fundamental difficulty of manually predicting emergent behavior of even simple networks has limited the models invented by human scientists to pathway diagrams that show necessary subunit interactions but do not reveal the dynamics that are sufficient for complex, self-regulating pattern to emerge. To finally bridge the gap between high-resolution genetic data and the ability to understand and control patterning, it is critical to develop computational tools to efficiently extract regulatory pathways from the resultant experimental shape phenotypes. For example, planarian regeneration has been studied for over a century, but despite increasing insight into the pathways that control its stem cells, no constructive, mechanistic model has yet been found by human scientists that explains more than one or two key features of its remarkable ability to regenerate its correct anatomical pattern after drastic perturbations. We present a method to infer the molecular products, topology, and spatial and temporal non-linear dynamics of regulatory networks recapitulating in silico the rich dataset of morphological phenotypes resulting from genetic, surgical, and pharmacological experiments. We demonstrated our approach by inferring complete regulatory networks explaining the outcomes of the main functional regeneration experiments in the planarian literature; By analyzing all the datasets together, our system inferred the first systems-biology comprehensive dynamical model explaining patterning in planarian regeneration. This method provides an automated

  2. Paleointensity study of the Brunhes-Matuyama reversal recorded in lavas on Tahiti Island by the LTD-DHT Shaw method

    NASA Astrophysics Data System (ADS)

    Mochizuki, N.; Oda, H.; Tsunakawa, H.; Ishizuka, O.; Yamazaki, T.; Uto, K.

    2007-12-01

    We have been investigating the Brunhes-Matuyama (B-M) polarity reversal recorded in lavas of the northern side of the Punaruu Valley, Tahiti Island. The lavas were sampled successively as possible as we can and in total 34 sites were located. From the bottom to the top of the sampled lavas, the directional data show a reversed (R) polarity, intermediate-normal-reversed (I-N-R) change and subsequently normal (N) period. These directional changes suggest that these lavas are considered to record the paleomagnetic field variation from the Matuyama chron to the whole stage of the B-M reversal. Paleointensity determinations were made by the LTD-DHT Shaw method (Tsunakawa and Shaw, 1994; Yamamoto et al., 2003; Mochizuki et al., 2004). For the directionally unstable period (I-N-R), the paleomagnetic field intensity was weak (4.7 μT). For the Matuyama reversed period prior to the directional reversal, the paleointensity results suggest that the field intensity varied in oscillation-like manner between 2 and 43 μT. It is noted that the virtual dipole moments (VDMs) in the oscillation-like change show a clear correlation with the VGP latitudes change, suggesting one of the important processes in the geodynamo for the polarity reversal.

  3. Determination of nitrate and nitrite in Hanford defense waste(HDW) by reverse polarity capillary zone electrophoresis (RPCE)method

    SciTech Connect

    Metcalf, S.G.

    1998-06-10

    This paper describes the first application of reverse polarity capillary zone electrophoresis (RPCE) for rapid and accurate determination of nitrate and nitrite in Hanford Defense Waste (HDW). The method development was carried out by using Synthetic Hanford Waste (SHW), followed by the analysis of 4 real HDW samples. Hexamethonium bromide (HMB) was used as electroosmotic flow modifier in borate buffer at pH 9.2 to decrease the electroosmotic flow (EOF) in order to enhance the speed of analysis and the resolution of nitrate and nitrite in high ionic strength HDW samples. The application of this capillary zone electrophoresis method, when compared with ion chromatography for two major components of HDW, nitrate and nitrite slightly reduced analysis time, eliminated most pre-analysis handling of the highly radioactive sample, and cut analysis wastes by more than 2 orders of magnitude. The analysis of real HDW samples that were validated by using sample spikes showed a concentration range of 1.03 to 1.42 M for both nitrate. The migration times of the real HDW and the spiked HDW samples were within a precision of less than 3% relative standard deviation. The selectivity ratio test used for peak confirmation of the spiked samples was within 96% of the real sample. Method reliability was tested by spiking the matrix with 72.4 mM nitrate and nitrite. Recoveries for these spiked samples were 93-103%.

  4. Comparison of reversible-jump Markov-chain-Monte-Carlo learning approach with other methods for missing enzyme identification.

    PubMed

    Geng, Bo; Zhou, Xiaobo; Zhu, Jinmin; Hung, Y S; Wong, Stephen T C

    2008-04-01

    Computational identification of missing enzymes plays a significant role in accurate and complete reconstruction of metabolic network for both newly sequenced and well-studied organisms. For a metabolic reaction, given a set of candidate enzymes identified according to certain biological evidences, a powerful mathematical model is required to predict the actual enzyme(s) catalyzing the reactions. In this study, several plausible predictive methods are considered for the classification problem in missing enzyme identification, and comparisons are performed with an aim to identify a method with better performance than the Bayesian model used in previous work. In particular, a regression model consisting of a linear term and a nonlinear term is proposed to apply to the problem, in which the reversible jump Markov-chain-Monte-Carlo (MCMC) learning technique (developed in [Andrieu C, Freitas Nando de, Doucet A. Robust full Bayesian learning for radial basis networks 2001;13:2359-407.]) is adopted to estimate the model order and the parameters. We evaluated the models using known reactions in Escherichia coli, Mycobacterium tuberculosis, Vibrio cholerae and Caulobacter cresentus bacteria, as well as one eukaryotic organism, Saccharomyces Cerevisiae. Although support vector regression also exhibits comparable performance in this application, it was demonstrated that the proposed model achieves favorable prediction performance, particularly sensitivity, compared with the Bayesian method. PMID:17950040

  5. Reversed-phase ion-pair liquid chromatography method for purification of duplex DNA with single base pair resolution

    PubMed Central

    Wysoczynski, Christina L.; Roemer, Sarah C.; Dostal, Vishantie; Barkley, Robert M.; Churchill, Mair E. A.; Malarkey, Christopher S.

    2013-01-01

    Obtaining quantities of highly pure duplex DNA is a bottleneck in the biophysical analysis of protein–DNA complexes. In traditional DNA purification methods, the individual cognate DNA strands are purified separately before annealing to form DNA duplexes. This approach works well for palindromic sequences, in which top and bottom strands are identical and duplex formation is typically complete. However, in cases where the DNA is non-palindromic, excess of single-stranded DNA must be removed through additional purification steps to prevent it from interfering in further experiments. Here we describe and apply a novel reversed-phase ion-pair liquid chromatography purification method for double-stranded DNA ranging in lengths from 17 to 51 bp. Both palindromic and non-palindromic DNA can be readily purified. This method has the unique ability to separate blunt double-stranded DNA from pre-attenuated (n-1, n-2, etc) synthesis products, and from DNA duplexes with single base pair overhangs. Additionally, palindromic DNA sequences with only minor differences in the central spacer sequence of the DNA can be separated, and the purified DNA is suitable for co-crystallization of protein–DNA complexes. Thus, double-stranded ion-pair liquid chromatography is a useful approach for duplex DNA purification for many applications. PMID:24013567

  6. Reverse osmosis pretreatment method for toxicity assessment of domestic wastewater using Vibrio qinghaiensis sp.-Q67.

    PubMed

    Ma, Xiaoyan Y; Wang, Xiaochang C; Hao Ngo, Huu; Guo, Wenshan; Wu, Maoni N; Wang, Na

    2013-11-01

    Luminescent bacterial test is a fast and sensitive method for acute toxicity assessment of water and wastewater. In this study, an improved toxicity testing method was developed using the freshwater luminescent bacteria Vibrio qinghaiensis sp.-Q67 that involved pretreatment of water samples with reverse osmosis (RO) to eliminate the interferences caused by nutrients in concentrated samples and to improve the reliability and sensitivity of the analysis. Because water samples contain low concentrations of several target toxic substances, rapid acute toxicity testing method that is commonly employed does not achieve enough sensitivity. The proposed RO pretreatment could effectively enrich organic and inorganic substances in water samples to enable a more effective and sensitive toxicity evaluation. The kinetic characteristics of toxicity of raw sewage and secondary effluent were evaluated based on the relative luminescence unit (RLU) curves and time-concentration-effect surfaces. It was observed that when the exposure time was prolonged to 8-h or longer, the bacteria reached the logarithmic growth stage. Hence, the stimulating effects of the coexisting ions (such as Na(+), K(+), NO3(-)) in the concentrated samples could be well eliminated. A 10-h exposure time in proposed Q67 test was found to quantitatively evaluate the toxicity of the organic and inorganic pollutants in the RO-concentrated samples. PMID:23988093

  7. Sea-going hardware for the cloud albedo method of reversing global warming.

    PubMed

    Salter, Stephen; Sortino, Graham; Latham, John

    2008-11-13

    Following the review by Latham et al. (Latham et al. 2008 Phil. Trans. R. Soc. A 366) of a strategy to reduce insolation by exploiting the Twomey effect, the present paper describes in outline the rationale and underlying engineering hardware that may bring the strategy from concept to operation. Wind-driven spray vessels will sail back and forth perpendicular to the local prevailing wind and release micron-sized drops of seawater into the turbulent boundary layer beneath marine stratocumulus clouds. The combination of wind and vessel movements will treat a large area of sky. When residues left after drop evaporation reach cloud level they will provide many new cloud condensation nuclei giving more but smaller drops and so will increase the cloud albedo to reflect solar energy back out to space. If the possible power increase of 3.7W m-2 from double pre-industrial CO2 is divided by the 24-hour solar input of 340W m-2, a global albedo increase of only 1.1 per cent will produce a sufficient offset. The method is not intended to make new clouds. It will just make existing clouds whiter. This paper describes the design of 300 tonne ships powered by Flettner rotors rather than conventional sails. The vessels will drag turbines resembling oversized propellers through the water to provide the means for generating electrical energy. Some will be used for rotor spin, but most will be used to create spray by pumping 30 kgs-1 of carefully filtered water through banks of filters and then to micro-nozzles with piezoelectric excitation to vary drop diameter. The rotors offer a convenient housing for spray nozzles with fan assistance to help initial dispersion. The ratio of solar energy reflected by a drop at the top of a cloud to the energy needed to make the surface area of the nucleus on which it has grown is many orders of magnitude and so the spray quantities needed to achieve sufficient global cooling are technically feasible. PMID:18757273

  8. A Novel Multi-Sensor Environmental Perception Method Using Low-Rank Representation and a Particle Filter for Vehicle Reversing Safety.

    PubMed

    Zhang, Zutao; Li, Yanjun; Wang, Fubing; Meng, Guanjun; Salman, Waleed; Saleem, Layth; Zhang, Xiaoliang; Wang, Chunbai; Hu, Guangdi; Liu, Yugang

    2016-01-01

    Environmental perception and information processing are two key steps of active safety for vehicle reversing. Single-sensor environmental perception cannot meet the need for vehicle reversing safety due to its low reliability. In this paper, we present a novel multi-sensor environmental perception method using low-rank representation and a particle filter for vehicle reversing safety. The proposed system consists of four main steps, namely multi-sensor environmental perception, information fusion, target recognition and tracking using low-rank representation and a particle filter, and vehicle reversing speed control modules. First of all, the multi-sensor environmental perception module, based on a binocular-camera system and ultrasonic range finders, obtains the distance data for obstacles behind the vehicle when the vehicle is reversing. Secondly, the information fusion algorithm using an adaptive Kalman filter is used to process the data obtained with the multi-sensor environmental perception module, which greatly improves the robustness of the sensors. Then the framework of a particle filter and low-rank representation is used to track the main obstacles. The low-rank representation is used to optimize an objective particle template that has the smallest L-1 norm. Finally, the electronic throttle opening and automatic braking is under control of the proposed vehicle reversing control strategy prior to any potential collisions, making the reversing control safer and more reliable. The final system simulation and practical testing results demonstrate the validity of the proposed multi-sensor environmental perception method using low-rank representation and a particle filter for vehicle reversing safety. PMID:27294931

  9. A Novel Multi-Sensor Environmental Perception Method Using Low-Rank Representation and a Particle Filter for Vehicle Reversing Safety

    PubMed Central

    Zhang, Zutao; Li, Yanjun; Wang, Fubing; Meng, Guanjun; Salman, Waleed; Saleem, Layth; Zhang, Xiaoliang; Wang, Chunbai; Hu, Guangdi; Liu, Yugang

    2016-01-01

    Environmental perception and information processing are two key steps of active safety for vehicle reversing. Single-sensor environmental perception cannot meet the need for vehicle reversing safety due to its low reliability. In this paper, we present a novel multi-sensor environmental perception method using low-rank representation and a particle filter for vehicle reversing safety. The proposed system consists of four main steps, namely multi-sensor environmental perception, information fusion, target recognition and tracking using low-rank representation and a particle filter, and vehicle reversing speed control modules. First of all, the multi-sensor environmental perception module, based on a binocular-camera system and ultrasonic range finders, obtains the distance data for obstacles behind the vehicle when the vehicle is reversing. Secondly, the information fusion algorithm using an adaptive Kalman filter is used to process the data obtained with the multi-sensor environmental perception module, which greatly improves the robustness of the sensors. Then the framework of a particle filter and low-rank representation is used to track the main obstacles. The low-rank representation is used to optimize an objective particle template that has the smallest L-1 norm. Finally, the electronic throttle opening and automatic braking is under control of the proposed vehicle reversing control strategy prior to any potential collisions, making the reversing control safer and more reliable. The final system simulation and practical testing results demonstrate the validity of the proposed multi-sensor environmental perception method using low-rank representation and a particle filter for vehicle reversing safety. PMID:27294931

  10. Association of Short-term Bleeding and Cramping Patterns with Long-Acting Reversible Contraceptive Method Satisfaction

    PubMed Central

    Diedrich, Justin T.; Desai, Sanyukta; Zhao, Qiuhong; Secura, Gina; Madden, Tessa; Peipert, Jeffrey F.

    2014-01-01

    Objectives To examine the short-term (3 and 6-month), self-reported bleeding and cramping patterns with intrauterine devices (IUDs) and the contraceptive implant, and the association of these symptoms with method satisfaction. Study Design We analyzed 3 and 6-month survey data from IUD and implant users in the Contraceptive CHOICE Project, a prospective cohort study. Participants who received a long-acting reversible contraceptive (LARC) method (levonorgestrel intrauterine system (LNG-IUS), copper IUD, or the etonogestrel implant) and completed their 3- and 6-month surveys were included. Univariable and multivariable analyses were performed to examine the association of bleeding and cramping patterns with short-term satisfaction. Results Our analytic sample included 5,011 CHOICE participants: 3001 LNG-IUS users, 826 copper IUD users, and 1184 implant users. At 3 months, over 65% of LNG-IUS and implant users reported no change or decreased cramping, while 63% of copper IUD users reported increased menstrual cramping. Lighter bleeding was reported by 67% of LNG-IUS users, 58% of implant users, and 8% of copper IUD users. Satisfaction of all LARC methods was high (≥90%) and significantly higher than non-LARC methods (p<0.001). LARC users with increased menstrual cramping (HR 0.96, 95% CI 0.92 – 0.99), heavier bleeding (HR 0.91, 95% CI 0.87 – 0.96), and increased bleeding frequency (HR 0.92, 95% CI 0.89 – 0.96) were less likely to report being very satisfied at 6 months. Conclusion Regardless of the LARC method, satisfaction at 3 and 6 months is very high. Changes in self-reported bleeding and cramping are associated with short-term LARC satisfaction. PMID:25046805

  11. A reversed-phase HPLC method for measurement of 5-hydroxymethyl furfuraldehyde and furfuraldehyde in processed juices.

    PubMed

    Roig, M G; Bello, J F; Kennedy, J F; Rivera, Z S; Lloyd, L L

    1992-01-01

    An HPLC method using a reversed-phase macroreticular PLRP-S column and phosphate buffer as eluent is described for the analysis of L-ascorbic acid degradation products, 5-hydroxymethyl furfuraldehyde and furfuraldehyde, in processed fruit juices. Measurement of the levels of 5-HMF and furfuraldehyde in citrus juices against time showed the presence of 5-HMF (0.45 mg l-1) even at zero time. An assessment on the effect of the additives on the formation of 5-HMF of reconstituted single-strength orange juice showed virtually the same results for all the samples stored at 4 degrees C and 20 degrees C, irrespective of the additive. For citrus juice samples which had been subjected to accelerated degradation, those that showed the highest decomposition of L-ascorbic acid, produced the highest level of 5-HMF. The presence of furfuraldehyde in any of the samples was not detected, probably due to the fact that furfuraldehyde was formed in such small amounts which are below the minimum detectability limit of the method (0.050 mg l-1). PMID:1369241

  12. Investigation of noise properties in grating-based x-ray phase tomography with reverse projection method

    NASA Astrophysics Data System (ADS)

    Bao, Yuan; Wang, Yan; Gao, Kun; Wang, Zhi-Li; Zhu, Pei-Ping; Wu, Zi-Yu

    2015-10-01

    The relationship between noise variance and spatial resolution in grating-based x-ray phase computed tomography (PCT) imaging is investigated with reverse projection extraction method, and the noise variances of the reconstructed absorption coefficient and refractive index decrement are compared. For the differential phase contrast method, the noise variance in the differential projection images follows the same inverse-square law with spatial resolution as in conventional absorption-based x-ray imaging projections. However, both theoretical analysis and simulations demonstrate that in PCT the noise variance of the reconstructed refractive index decrement scales with spatial resolution follows an inverse linear relationship at fixed slice thickness, while the noise variance of the reconstructed absorption coefficient conforms with the inverse cubic law. The results indicate that, for the same noise variance level, PCT imaging may enable higher spatial resolution than conventional absorption computed tomography (ACT), while ACT benefits more from degraded spatial resolution. This could be a useful guidance in imaging the inner structure of the sample in higher spatial resolution. Project supported by the National Basic Research Program of China (Grant No. 2012CB825800), the Science Fund for Creative Research Groups, the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant Nos. KJCX2-YW-N42 and Y4545320Y2), the National Natural Science Foundation of China (Grant Nos. 11475170, 11205157, 11305173, 11205189, 11375225, 11321503, 11179004, and U1332109).

  13. In situ growth of manganese oxide on 3D graphene by a reverse microemulsion method for supercapacitors

    NASA Astrophysics Data System (ADS)

    Wei, Bing; Wang, Lidong; Wang, Yang; Yuan, Yinan; Miao, Qinghua; Yang, Ziyue; Fei, Weidong

    2016-03-01

    In this study, a new, effective strategy is reported for the fabrication of composites using manganese oxide (MnO2) grown in situ on three-dimensional (3D) graphene by the reverse microemulsion (water-in-oil) method. A uniform coating of nanoscale MnO2 layers can be observed on the internal surface of 3D graphene, which could benefit rapid ionic and electronic transport. The electrochemical performance of the MnO2/3D graphene composites is optimized by the control of the composite structure and mass loading of MnO2. The MnO2/3D graphene composite thus prepared exhibits a significantly high specific capacitance of 659.7 F g-1 at 0.3 A g-1 and an excellent retention life of 106% after 1000 cycles. The facile synthesis and excellent electrochemical performance of the MnO2/3D graphene composites indicate that the developed method demonstrates potential applications for the fabrication of novel electrode materials for use in energy storage devices.

  14. Regioselective deprotection of the monosaccharide-bearing thiocyanomethyl group at the anomeric position monitored by reversed-phase HPLC method.

    PubMed

    Abualassal, Qais; Al Azzam, Khaldun M; Jilani, Jamal A

    2016-09-01

    In the current work, the investigation and development of a chemo-enzymatic approach for the synthesis of neo-glycoproteins have been studied. This strategy is based on the regioselective enzymatic hydrolysis of peracetylated monosaccharide, functionalized at the anomeric position (C1) as 1-thio-(S-cyanomethyl) group, a precursor of the 2- iminomethoxyethyl thioglycosides-linker for protein glycosylation, catalyzed by immobilized enzymes to obtain selectively monodeprotected compounds. The use of this activation in C1 is the most frequently used strategy for glycoprotein preparation. The selected biocatalysts are the lipase from Candida rugosa and the acetyl xylan esterase from Bacillus pumilus. A reversed-phase high-performance liquid-chromatographic (HPLC) method for monitoring the regioselective deprotection reaction has been developed. The developed HPLC method was used as a fingerprint to follow the hydrolysis of substrate 1 to substrate 1a and to determine its purity and yield. Moreover, the obtained compound was further purified by flash chromatography. The obtained compound 1a was further characterized using (1) H, (13) C NMR, correlation spectroscopy (COSY) and heteronuclear multiple bond correlation. The resulting product can be used as an intermediate for the preparation of di- and more complex oligosaccharides aimed at protein conjugation. Copyright © 2016 John Wiley & Sons, Ltd. PMID:26864255

  15. Time reversal optical tomography and decomposition methods for detection and localization of targets in highly scattering turbid media

    NASA Astrophysics Data System (ADS)

    Wu, Binlin

    New near-infrared (NIR) diffuse optical tomography (DOT) approaches were developed to detect, locate, and image small targets embedded in highly scattering turbid media. The first approach, referred to as time reversal optical tomography (TROT), is based on time reversal (TR) imaging and multiple signal classification (MUSIC). The second approach uses decomposition methods of non-negative matrix factorization (NMF) and principal component analysis (PCA) commonly used in blind source separation (BSS) problems, and compare the outcomes with that of optical imaging using independent component analysis (OPTICA). The goal is to develop a safe, affordable, noninvasive imaging modality for detection and characterization of breast tumors in early growth stages when those are more amenable to treatment. The efficacy of the approaches was tested using simulated data, and experiments involving model media and absorptive, scattering, and fluorescent targets, as well as, "realistic human breast model" composed of ex vivo breast tissues with embedded tumors. The experimental arrangements realized continuous wave (CW) multi-source probing of samples and multi-detector acquisition of diffusely transmitted signal in rectangular slab geometry. A data matrix was generated using the perturbation in the transmitted light intensity distribution due to the presence of absorptive or scattering targets. For fluorescent targets the data matrix was generated using the diffusely transmitted fluorescence signal distribution from the targets. The data matrix was analyzed using different approaches to detect and characterize the targets. The salient features of the approaches include ability to: (a) detect small targets; (b) provide three-dimensional location of the targets with high accuracy (~within a millimeter or 2); and (c) assess optical strength of the targets. The approaches are less computation intensive and consequently are faster than other inverse image reconstruction methods that

  16. NormaCurve: A SuperCurve-Based Method That Simultaneously Quantifies and Normalizes Reverse Phase Protein Array Data

    PubMed Central

    Troncale, Sylvie; Barbet, Aurélie; Coulibaly, Lamine; Henry, Emilie; He, Beilei; Barillot, Emmanuel; Dubois, Thierry; Hupé, Philippe; de Koning, Leanne

    2012-01-01

    Motivation Reverse phase protein array (RPPA) is a powerful dot-blot technology that allows studying protein expression levels as well as post-translational modifications in a large number of samples simultaneously. Yet, correct interpretation of RPPA data has remained a major challenge for its broad-scale application and its translation into clinical research. Satisfying quantification tools are available to assess a relative protein expression level from a serial dilution curve. However, appropriate tools allowing the normalization of the data for external sources of variation are currently missing. Results Here we propose a new method, called NormaCurve, that allows simultaneous quantification and normalization of RPPA data. For this, we modified the quantification method SuperCurve in order to include normalization for (i) background fluorescence, (ii) variation in the total amount of spotted protein and (iii) spatial bias on the arrays. Using a spike-in design with a purified protein, we test the capacity of different models to properly estimate normalized relative expression levels. The best performing model, NormaCurve, takes into account a negative control array without primary antibody, an array stained with a total protein stain and spatial covariates. We show that this normalization is reproducible and we discuss the number of serial dilutions and the number of replicates that are required to obtain robust data. We thus provide a ready-to-use method for reliable and reproducible normalization of RPPA data, which should facilitate the interpretation and the development of this promising technology. Availability The raw data, the scripts and the NormaCurve package are available at the following web site: http://microarrays.curie.fr. PMID:22761696

  17. Identification of Staphylococcus species and subspecies by the chaperonin 60 gene identification method and reverse checkerboard hybridization.

    PubMed Central

    Goh, S H; Santucci, Z; Kloos, W E; Faltyn, M; George, C G; Driedger, D; Hemmingsen, S M

    1997-01-01

    A previous study (S. H. Goh et al., J. Clin. Microbiol. 34:818-823, 1996) demonstrated that a 600-bp region of the chaperonin 60 (Cpn60) genes from various bacterial isolates could be amplified by PCR with a pair of degenerate primers and that the products could be used as species-specific probes for Staphylococcus aureus, S. epidermidis, S. haemolyticus, S. lugdunensis, S. saprophyticus, and S. schleiferi. To further validate the utility of bacterial Cpn60 genes as universal targets for bacterial identification (ID), reverse checkerboard chemiluminescent hybridization experiments were performed with DNA probes from 34 different Staphylococcus species and subspecies. With the exception of probes from the Cpn60 genes of S. intermedius and S. delphini, which cross hybridized, all were species specific. Two subspecies of both S. capitis and S. cohnii were differentiated from one another, while DNAs from the two S. schleiferi subspecies cross hybridized. When 40 known Staphylococcus isolates were tested in a blind experiment by the Cpn60 gene method, 36 strains, representing six species and one subspecies (S. sciuri, S. caseolyticus, S. hominis, S. warneri, S. hyicus, S. haemolyticus, and S. capitis subsp. ureolyticus), were correctly identified. DNA from the four remaining isolates, known to be S. hyicus bovine strains, failed to hybridize to DNA from the S. hyicus target strain or any other Staphylococcus species. However, DNAs from these S. hyicus isolates did cross hybridize with each other. New DNA sequence data and evidence from previous studies suggest some genetic divergence between the two groups of S. hyicus isolates. Our results demonstrate that this Cpn60 gene-based ID method has the potential to be a basic method for bacterial ID. Studies are in progress to further validate the utility of this Cpn60 gene system for ID of Staphylococcus and other genera, including those of slow-growing microorganisms. PMID:9399505

  18. The design of flexible ciprofloxacin-loaded PLGA implants using a reversed phase separation/coacervation method.

    PubMed

    Park, Peter In Pyo; Makoid, Michael; Jonnalagadda, Sriramakamal

    2011-02-01

    The purpose of this research is to design and characterize flexible PLGA-based implants for the controlled release of ciprofloxacin hydrochloride for up to 6 weeks in vitro. This research uses a reversed phase separation/coacervation method to fabricate flexible PLA and PLGA: excipient implants with dichloromethane/mineral oil as solvent/non-solvent. Physical characterization was performed using thermal and mechanical analyses. Drug loading and release studies were performed with ciprofloxacin HCl as the model drug. Release kinetics was modeled to elucidate possible mechanisms of drug release. Four polymer-excipient combinations with glass transition temperatures less than 20°C and representing a wide range of Young's moduli were shown to entrap up to 8% of ciprofloxacin HCl that could be released at a controlled rate for 65 days in vitro. The release rate could consistently fit a ternary Gaussian pattern with an R(2)>0.99. It was postulated that these release patterns could be related to ciprofloxacin that was loosely or poorly bound (burst release), trapped within the polymer matrix, or encapsulated by the polymer. These studies show that flexible implants can be fabricated from PLGA-based polymers for the controlled release of ciprofloxacin hydrochloride for up to 6 weeks in vitro. PMID:21145965

  19. Method and apparatus for cold gas reinjection in through-flow and reverse-flow wave rotors

    NASA Technical Reports Server (NTRS)

    Nalim, M. Razi (Inventor); Paxson, Daniel E. (Inventor)

    1999-01-01

    A method and apparatus for cold gas reinjection in through-flow and reverse-flow wave rotors having a plurality of channels formed around a periphery thereof. A first port injects a supply of cool air into the channels. A second port allows the supply of cool air to exit the channels and flow to a combustor. A third port injects a supply of hot gas from the combustor into the channels. A fourth port allows the supply of hot gas to exit the channels and flow to a turbine. A diverting port and a reinjection port are connected to the second and third ports, respectively. The diverting port diverts a portion of the cool air exiting through the second port as reinjection air. The diverting port is fluidly connected to the reinjection port which reinjects the reinjection air back into the channels. The reinjection air evacuates the channels of the hot gas resident therein and cools the channel walls, a pair of end walls of the rotor, ducts communicating with the rotor and subsequent downstream components. In a second embodiment, the second port receives all of the cool air exiting the channels and the diverting port diverts a portion of the cool air just prior to the cool air flowing to the combustor.

  20. New method for simultaneous species-specific identification of equine strongyles (nematoda, strongylida) by reverse line blot hybridization.

    PubMed

    Traversa, Donato; Iorio, Raffaella; Klei, Thomas R; Kharchenko, Vitaliy A; Gawor, Jakub; Otranto, Domenico; Sparagano, Olivier A E

    2007-09-01

    The ability of a reverse line blot (RLB) assay to identify 13 common species of equine small strongyles (cyathostomins) and to discriminate them from three Strongylus spp. (large strongyles) was demonstrated. The assay relied on the specific hybridization of PCR-amplified intergenic spacer DNA fragments of the nuclear ribosomal DNA to membrane-bound species-specific probes. All cyathostomins examined were unequivocally identified and simultaneously discriminated from each other and from three large strongyles (Strongylus edentatus, Strongylus equinus, and Strongylus vulgaris). This assay will enable the accurate and rapid identification of equine cyathostomins irrespective of their life cycle stage, opening important avenues for a better understanding of their biology and epidemiology and of the pathogenesis of cyathostomin-associated disease. In particular, this RLB method promises to be a powerful diagnostic tool to determine the roles of individual species in the pathogenesis of mixed infections and to elucidate some aspects of cyathostominosis. Also, it could represent a basic step toward the development of a rapid and simple molecular test for the early detection of drug-resistant genotypes of horse strongyle species. PMID:17626168

  1. New Method for Simultaneous Species-Specific Identification of Equine Strongyles (Nematoda, Strongylida) by Reverse Line Blot Hybridization▿

    PubMed Central

    Traversa, Donato; Iorio, Raffaella; Klei, Thomas R.; Kharchenko, Vitaliy A.; Gawor, Jakub; Otranto, Domenico; Sparagano, Olivier A. E.

    2007-01-01

    The ability of a reverse line blot (RLB) assay to identify 13 common species of equine small strongyles (cyathostomins) and to discriminate them from three Strongylus spp. (large strongyles) was demonstrated. The assay relied on the specific hybridization of PCR-amplified intergenic spacer DNA fragments of the nuclear ribosomal DNA to membrane-bound species-specific probes. All cyathostomins examined were unequivocally identified and simultaneously discriminated from each other and from three large strongyles (Strongylus edentatus, Strongylus equinus, and Strongylus vulgaris). This assay will enable the accurate and rapid identification of equine cyathostomins irrespective of their life cycle stage, opening important avenues for a better understanding of their biology and epidemiology and of the pathogenesis of cyathostomin-associated disease. In particular, this RLB method promises to be a powerful diagnostic tool to determine the roles of individual species in the pathogenesis of mixed infections and to elucidate some aspects of cyathostominosis. Also, it could represent a basic step toward the development of a rapid and simple molecular test for the early detection of drug-resistant genotypes of horse strongyle species. PMID:17626168

  2. ReCLIP (Reversible Cross-Link Immuno-Precipitation): An Efficient Method for Interrogation of Labile Protein Complexes

    PubMed Central

    Smith, Andrew L.; Friedman, David B.; Yu, Huapeng; Carnahan, Robert H.; Reynolds, Albert B.

    2011-01-01

    The difficulty of maintaining intact protein complexes while minimizing non-specific background remains a significant limitation in proteomic studies. Labile interactions, such as the interaction between p120-catenin and the E-cadherin complex, are particularly challenging. Using the cadherin complex as a model-system, we have developed a procedure for efficient recovery of otherwise labile protein-protein interactions. We have named the procedure “ReCLIP” (Reversible Cross-Link Immuno-Precipitation) to reflect the primary elements of the method. Using cell-permeable, thiol-cleavable crosslinkers, normally labile interactions (i.e. p120 and E-cadherin) are stabilized in situ prior to isolation. After immunoprecipitation, crosslinked binding partners are selectively released and all other components of the procedure (i.e. beads, antibody, and p120 itself) are discarded. The end result is extremely efficient recovery with exceptionally low background. ReCLIP therefore appears to provide an excellent alternative to currently available affinity-purification approaches, particularly for studies of labile complexes. PMID:21283770

  3. Magnetic properties of iron-based soft magnetic composites with SiO2 coating obtained by reverse microemulsion method

    NASA Astrophysics Data System (ADS)

    Wu, Shen; Sun, Aizhi; Lu, Zhenwen; Cheng, Chuan; Gao, Xuexu

    2015-05-01

    In this work, iron-based soft magnetic composites coated with the amorphous SiO2 layer have been fabricated by utilizing tetraethoxysilane in the reverse microemulsion method, and then the effects of addition amount of SiO2 and annealing temperature on the magnetic properties were investigated. The results show that the surface of iron powders contains a thin amorphous SiO2 insulation layer, which effectively decreases the magnetic loss of synthesized magnets. The magnetic loss of coated samples decreased by 87.8% as compared with that of uncoated samples at 150 kHz. Magnetic measurements show that the sample with 1.25 wt% SiO2 has an acceptable real part and minimum imaginary part of permeability in comparison with other samples. Also, the annealing treatment increased the initial permeability, the maximum permeability and the magnetic induction and decreased the coercivity with increasing temperature in the range 300-600 °C. The results of the loss separation imply that the annealed SMCs have a higher hysteresis loss coefficient (k2) and lower eddy current loss coefficient (k3) as compared with the pure iron compacts after the same heat treatment due to the preservation of the SiO2 layer.

  4. Assembly and electroanalytical performance of Prussian blue/polypyrrole composite nanoparticles synthesized by the reverse micelle method

    NASA Astrophysics Data System (ADS)

    Miao, Yuqing; Liu, Jiwei

    2009-04-01

    We report on the characterization, assembly and electroanalytical performance of Prussian blue/polypyrrole (PBPPy) composite nanoparticles synthesized by the reverse micelle method. Scanning electron microscopy suggests the formation of nanosized PBPPy particles with diameters between 40 and 50 nm. Optical absorption confirms that the particles are composed of Prussian blue (PB) and polypyrrole. PB and PBPPy nanoparticles were anchored onto the surface of cysteine-modified Au electrodes. Cyclic voltammetry experiments show that PB- or PBPPy-modified electrodes exhibit intrinsic electrochemical properties and a high electrocatalytic activity towards H2O2. PBPPy-modified electrodes exhibit a higher sensitivity to H2O2 than PB-modified electrodes. A linear calibration curve in the concentration range 0.99 μM-8.26 mM H2O2 is constructed with a detection limit of 0.23 μM at a signal-to-noise ratio of 3. Excellent stability is observed for PBPPy-composite-nanoparticle-modified electrodes even in a pH 6 phosphate buffer solution with a high H2O2 concentration (0.99 mM). Glutaraldehyde and Nafion^{\\tiny{\\textregistered}} were also employed to immobilize glucose oxidase for the development of PBPPy-based biosensors. The results show that PBPPy composite nanoparticles can be used to develop oxidase-based biosensors.

  5. Rapid detection of Grapevine leafroll-associated virus type 3 using a reverse transcription loop-mediated amplification method.

    PubMed

    Walsh, Helen Ann; Pietersen, Gerhard

    2013-12-01

    Grapevine leafroll disease (GLD) is the most important disease of Grapevines in South Africa. Grapevine leafroll-associated virus type 3 (GLRaV-3) has a close association with the disease and is prevalent in South African vineyards. GLD can be controlled using a combination of virus-free planting material, systemic insecticides to control vector populations and removal of infected vines by roguing. Infected vines are identified each autumn using either symptom display (in red cultivars) or ELISA (in white cultivars). While ELISA is a simple, reliable means of testing for GLRaV-3, it is time consuming, laborious and insensitive and a quicker, more sensitive method of detecting GLRaV-3 in the field is needed. A single-tube one-step reverse transcription (RT) loop-mediated isothermal amplification (LAMP) assay combined with a simple RNA extraction protocol was developed for the rapid and easy detection of GLRaV-3. Hydroxy napthol blue was included as an indicator and under isothermal conditions at 60 °C the target viral gene could be amplified in under 2h and positive results could be easily seen by examining the colour change from violet to sky blue. Using this method, 50 samples could be also pooled together with a single positive sample still being detected. A direct comparison of ELISA, nested PCR and RT-LAMP showed that RT-LAMP is as sensitive as nested PCR and could be performed in a much shorter time with less equipment. This assay is may be a possible alternative to ELISA for the detection of GLRaV-3 in the field. PMID:24025344

  6. Removal of Gangue Minerals Containing Major Elements from Karlıova-Derinçay (Bingöl) Lignite Using a Reverse Flotation Method

    NASA Astrophysics Data System (ADS)

    Temel, Halime Abakay

    2015-12-01

    The removal of gangue minerals containing major elements was investigated using a reverse flotation method. Experiments were conducted on lignite samples, with high-ash and low-sulphur contents taken from a lignite field in Karlıova-Derinçay (Bingöl), Turkey. Predominant gangue minerals in the samples were found to be quartz, gypsum, feldspar minerals, mica minerals, and clays (smectite group). Preliminary flotation studies showed that gangue materials are more buoyant than the lignite sample. Some parameters that markedly influence the effectiveness of reverse flotation, such as grinding time, pH, collector type and volume, frother type and volume, and salt, were investigated. Quartz was found to cause a major problem in terms of reverse flotation. Flotation measurements showed that anionic collectors in an acidic medium result in the following element reduction order: sulphur trioxide > ferric oxide > magnesium oxide > calcium oxide > silicon dioxide > aluminium oxide.

  7. Advanced solid-state NMR characterization of marine dissolved organic matter isolated using the coupled reverse osmosis/electrodialysis method.

    PubMed

    Mao, Jingdong; Kong, Xueqian; Schmidt-Rohr, Klaus; Pignatello, Joseph J; Perdue, E Michael

    2012-06-01

    Advanced (13)C solid-state techniques were employed to investigate the major structural characteristics of two surface-seawater dissolved organic matter (DOM) samples isolated using the novel coupled reverse osmosis/electrodialysis method. The NMR techniques included quantitative (13)C direct polarization/magic angle spinning (DP/MAS) and DP/MAS with recoupled dipolar dephasing, (13)C cross-polarization/total sideband suppression (CP/TOSS), (13)C chemical shift anisotropy filter, CH, CH(2), and CH(n) selection, two-dimensional (1)H-(13)C heteronuclear correlation NMR (2D HETCOR), 2D HETCOR combined with dipolar dephasing, and (15)N cross-polarization/magic angle spinning (CP/MAS). The two samples (Coastal and Marine DOM) were collected at the mouth of the Ogeechee River and in the Gulf Stream, respectively. The NMR results indicated that they were structurally distinct. Coastal DOM contained significantly more aromatic and carbonyl carbons whereas Marine DOM was markedly enriched in alkoxy carbon (e.g., carbohydrate-like moieties). Both samples contained significant amide N, but Coastal DOM had nitrogen bonded to aromatic carbons. Our dipolar-dephased spectra indicated that a large fraction of alkoxy carbons were not protonated. For Coastal DOM, our NMR results were consistent with the presence of the major structural units of (1) carbohydrate-like moieties, (2) lignin residues, (3) peptides or amino sugars, and (4) COO-bonded alkyls. For Marine DOM, they were (1) carbohydrate-like moieties, (2) peptides or amino sugars, and (3) COO-bonded alkyls. In addition, both samples contained significant amounts of nonpolar alkyl groups. The potential sources of the major structural units of DOM were discussed in detail. Nonprotonated O-alkyl carbon content was proposed as a possible index of humification. PMID:22553962

  8. Face-related segregation reversal at Pt 50Ni 50 surfaces studied with the embedded atom method

    NASA Astrophysics Data System (ADS)

    Deurinck, P.; Creemers, C.

    1999-11-01

    The segregation to the three low-index surfaces of a Pt50Ni50 single crystal is modelled by Monte Carlo simulations combined with the embedded atom method (EAM). Using the best fit EAM parameters from the literature for the six transition metals of the Ni and Cu groups does not yield satisfactory results. In this work the EAM parameters are recalculated and optimised exclusively for the Pt-Ni alloy system under study. Only then does EAM reliably reproduce the driving forces for segregation. The experimental results [Y. Gauthier et al., Phys. Rev. B 31 (1985) 6216; Y. Gauthier et al., Phys. Rev. B 35 (1987) 7867; S.M. Foiles, in: P.A. Dobson, A. Miller (Eds.), Surface Segregation Phenomena, CRC Press, Boca Raton, FL, 1990, p. 79] reveal a face-related segregation reversal for the Pt50Ni50 single crystal. It appears from the simulations that this is caused by a relatively small difference in surface energy in close competition with the elastic strain release. At the open (110) surface the difference in surface energy dominates causing Ni segregation. At the (100) and (111) surfaces the difference in surface energy is overpowered by the elastic strain leading to Pt segregation. The simulations are in good agreement with the experimental results and reproduce quantitatively the Ni segregation to the (110) surface and the Pt segregation to the (100) and (111) surfaces. Only at the (110) surface significant relaxations are predicted in good agreement with experimental evidence. Atomic vibrations can be included by allowing a large number of very small displacements or with a more classical treatment of vibrational entropy. Both approaches yield the same results and show that the inclusion of atomic vibrations is important only for the (110) surface and tend to attenuate the Ni segregation profile.

  9. Coupled reverse transcription-polymerase chain reaction (RT-PCR) as a sensitive and rapid method for isozyme genotyping.

    PubMed

    Mocharla, H; Mocharla, R; Hodes, M E

    1990-09-14

    We have developed a highly sensitive and rapid coupled reverse transcription-polymerase chain reaction (RT-PCR) technique for detection of alpha-amylase-encoding gene transcripts and for distinguishing between the human salivary (AMY1) and pancreatic (AMY2) gene transcripts. The two genes are 93-94% homologous. However, the AMY1 gene has an additional exon known as exon S, and an extra 32 bp in exon 1. Genotyping of the different AMYs by RT-PCR was based on this unique feature of the AMY1 mRNA sequence. Detection of AMY gene (AMY1 and AMY2) transcripts in cellular RNA was achieved with a set of primers common to both human AMY1 and AMY2 genes and derived from the exon 3-4 regions. In contrast, AMY1 gene transcripts were distinguished from the pancreatic AMY2 gene transcripts by use of primers specific to the exon S-1 regions of the AMY1 gene. To distinguish AMY1 transcripts from a mixture of AMY1 and AMY2, use was made of the differences in the ethidium bromide-stained agarose gel patterns obtained after digestion of the amplified exon 3-4 fragments with TaqI. AMY gene transcripts were detectable by autoradiography in RT-PCR amplified DNA obtained from as little as 5 pg of human pancreatic or parotid total RNA. A comparison of sensitivity of Northern blotting vs. RT-PCR suggested that the RT-PCR method is about 3-6 x 10(3)-fold more sensitive than Northern blotting in detecting AMY gene transcripts in human pancreatic total RNA. PMID:1699848

  10. Changes in Use of Long-Acting Reversible Contraceptive Methods Among U.S. Women, 2009–2012

    PubMed Central

    Kavanaugh, Megan L.; Jerman, Jenna; Finer, Lawrence B.

    2016-01-01

    OBJECTIVE To examine current levels, current correlates of, and changes in long-acting reversible contraceptive (LARC) use, including intrauterine devices and implants, among females aged 15–44 years using contraception between 2008–2010 and 2011–2013 with specific attention to associations between race, income, and age and their LARC use. METHODS We analyzed data from two rounds of the National Survey of Family Growth, nationally representative samples of females aged 15–44 years, consisting of 6,428 females in 2008–2010 and 5,601 females in 2011–2013. We conducted simple and multivariable logistic regression analyses with adjustments for the sampling design to identify demographic characteristics predictive of LARC use and changes in these patterns between the two time periods. In this cross-sectional, descriptive study, our primary outcome of interest was current prevalence of LARC use among all contraceptive users at the time of the interview. RESULTS The prevalence of LARC use among contracepting U.S. females increased from 8.5% in 2009 to 11.6% in 2012 (P<.01). The most significant increases occurred among Hispanic females (from 8.5% to 15.1%), those with private insurance (7.1–11.1%), those with fewer than two sexual partners in the previous year (9.2–12.4%), and those who were nulliparous (2.1–5.9%) (all P<.01). In multivariable analyses adjusting for key demographic characteristics, the strongest associations with LARC use in 2012 were parity (adjusted odds ratios [ORs] 4.3–5.5) and having a history of stopping non-LARC hormonal use (adjusted OR 1.9). Women aged 35–44 years (adjusted OR 0.3) were less likely to be LARC users than their counterparts (all P<.001). Poverty status was not associated with LARC use. There were no differences in discontinuation of LARC methods resulting from dissatisfaction between minority women and non-Hispanic white women. CONCLUSION During the most recent time period surveyed, use of LARC methods

  11. A weighted reverse Cuthill-McKee procedure for finite element method algorithms to solve strongly anisotropic electrodynamic problems

    SciTech Connect

    Cristofolini, Andrea; Latini, Chiara; Borghi, Carlo A.

    2011-02-01

    This paper presents a technique for improving the convergence rate of a generalized minimum residual (GMRES) algorithm applied for the solution of a algebraic system produced by the discretization of an electrodynamic problem with a tensorial electrical conductivity. The electrodynamic solver considered in this work is a part of a magnetohydrodynamic (MHD) code in the low magnetic Reynolds number approximation. The code has been developed for the analysis of MHD interaction during the re-entry phase of a space vehicle. This application is a promising technique intensively investigated for the shock mitigation and the vehicle control in the higher layers of a planetary atmosphere. The medium in the considered application is a low density plasma, characterized by a tensorial conductivity. This is a result of the behavior of the free electric charges, which tend to drift in a direction perpendicular both to the electric field and to the magnetic field. In the given approximation, the electrodynamics is described by an elliptical partial differential equation, which is solved by means of a finite element approach. The linear system obtained by discretizing the problem is solved by means of a GMRES iterative method with an incomplete LU factorization threshold preconditioning. The convergence of the solver appears to be strongly affected by the tensorial characteristic of the conductivity. In order to deal with this feature, the bandwidth reduction in the coefficient matrix is considered and a novel technique is proposed and discussed. First, the standard reverse Cuthill-McKee (RCM) procedure has been applied to the problem. Then a modification of the RCM procedure (the weighted RCM procedure, WRCM) has been developed. In the last approach, the reordering is performed taking into account the relation between the mesh geometry and the magnetic field direction. In order to investigate the effectiveness of the methods, two cases are considered. The RCM and WRCM procedures

  12. Ferroelectric polarization reversal in single crystals

    NASA Technical Reports Server (NTRS)

    Stadler, Henry L.

    1992-01-01

    Research on the reversal of polarization in ferroelectric crystals is reviewed. Particular attention is given to observation methods for polarization reversal, BaTiO3 polarization reversal, crystal thickness dependence of polarization reversal, and domain wall movement during polarization reversal in TGS.

  13. Reversible Sterilization

    ERIC Educational Resources Information Center

    Largey, Gale

    1977-01-01

    Notes that difficult questions arise concerning the use of sterilization for alleged eugenic and euthenic purposes. Thus, how reversible sterilization will be used with relation to the poor, mentally ill, mentally retarded, criminals, and minors, is questioned. (Author/AM)

  14. Reversible Cardiomyopathies

    PubMed Central

    Patel, Harsh; Madanieh, Raef; Kosmas, Constantine E; Vatti, Satya K; Vittorio, Timothy J

    2015-01-01

    Cardiomyopathies (CMs) have many etiological factors that can result in severe structural and functional dysregulation. Fortunately, there are several potentially reversible CMs that are known to improve when the root etiological factor is addressed. In this article, we discuss several of these reversible CMs, including tachycardia-induced, peripartum, inflammatory, hyperthyroidism, Takotsubo, and chronic illness–induced CMs. Our discussion also includes a review on their respective pathophysiology, as well as possible management solutions. PMID:26052233

  15. HRMC_2.1: Hybrid Reverse Monte Carlo method with silicon, carbon, germanium and silicon carbide potentials

    NASA Astrophysics Data System (ADS)

    Opletal, G.; Petersen, T. C.; Russo, S. P.

    2014-06-01

    The Hybrid Reverse Monte Carlo (HRMC) code models the atomic structure of materials via the use of a combination of constraints including experimental diffraction data and an empirical energy potential. In this version 2.1 update, an empirical potential for silicon-carbide has been added to the code along with an experimentally motivated constraint on the bond type fraction applicable to systems containing multiple elements.

  16. Development of reverse transcription loop-mediated isothermal amplification assay as a simple detection method of Chrysanthemum stem necrosis virus in chrysanthemum and tomato.

    PubMed

    Suzuki, Ryoji; Fukuta, Shiro; Matsumoto, Yuho; Hasegawa, Toru; Kojima, Hiroko; Hotta, Makiko; Miyake, Noriyuki

    2016-10-01

    For a simple and rapid detection of Chrysanthemum stem necrosis virus (CSNV) from chrysanthemum and tomato, a reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay was developed. A primer set designed to the genome sequences of CSNV worked most efficiently at 63°C and could detect CSNV RNA within 12min by fluorescence monitoring using an isothermal DNA amplification and fluorescence detection device. The result of a specificity test using seven other viruses and one viroid-infectable chrysanthemum or tomato showed that the assay could amplify CSNV specifically, and a sensitivity comparison showed that the RT-LAMP assay was as sensitive as the reverse transcriptase polymerase chain reaction. The RT-LAMP assay using crude RNA, extracted simply, could detect CSNV. Overall, the RT-LAMP assay was found to be a simple, specific, convenient, and time-saving method for CSNV detection. PMID:27400833

  17. Simple method for the extraction and reversed-phase high-performance liquid chromatographic analysis of carotenoid pigments from red yeasts (Basidiomycota, Fungi).

    PubMed

    Weber, Roland W S; Anke, Heidrun; Davoli, Paolo

    2007-03-23

    A simple method for the extraction of carotenoid pigments from frozen wet cells of red yeasts (Basidiomycota) and their analysis by reversed-phase HPLC using a C(18) column and a water/acetone solvent system is described. Typical red yeast carotenoids belonging to an oxidative series from the monocyclic gamma-carotene to 2-hydroxytorularhodin and from the bicyclic beta-carotene to astaxanthin were separated. Pigment identity was confirmed by LC-atmospheric pressure chemical ionisation (APCI) mass spectrometry using similar chromatographic conditions. PMID:17266973

  18. Purification of flavonoids from licorice using an off-line preparative two-dimensional normal-phase liquid chromatography/reversed-phase liquid chromatography method.

    PubMed

    Fan, Yunpeng; Fu, Yanhui; Fu, Qing; Cai, Jianfeng; Xin, Huaxia; Dai, Mei; Jin, Yu

    2016-07-01

    An orthogonal (71.9%) off-line preparative two-dimensional normal-phase liquid chromatography/reversed-phase liquid chromatography method coupled with effective sample pretreatment was developed for separation and purification of flavonoids from licorice. Most of the nonflavonoids were firstly removed using a self-made Click TE-Cys (60 μm) solid-phase extraction. In the first dimension, an industrial grade preparative chromatography was employed to purify the crude flavonoids. Click TE-Cys (10 μm) was selected as the stationary phase that provided an excellent separation with high reproducibility. Ethyl acetate/ethanol was selected as the mobile phase owing to their excellent solubility for flavonoids. Flavonoids co-eluted in the first dimension were selected for further purification using reversed-phase liquid chromatography. Multiple compounds could be isolated from one normal-phase fraction and some compounds with bad resolution in one-dimensional liquid chromatography could be prepared in this two-dimensional system owing to the orthogonal separation. Moreover, this two-dimensional liquid chromatography method was beneficial for the preparation of relatively trace flavonoid compounds, which were enriched in the first dimension and further purified in the second dimension. Totally, 24 flavonoid compounds with high purity were obtained. The results demonstrated that the off-line two-dimensional liquid chromatography method was effective for the preparative separation and purification of flavonoids from licorice. PMID:27214649

  19. Optimisation of a gas chromatographic method for trace gaseous impurities in nitrogen trifluoride by column sequence reversal.

    PubMed

    de Coning, Johannes Petrus; Swinley, John McNeil

    2008-02-01

    Highly reactive fluorinated gaseous matrices require special equipment and techniques for the gas chromatographic analysis of trace impurities in these gases. The impurities that were analysed at the low mg/L levels included dioxygen (O2), dinitrogen (N2), carbon dioxide (CO2), carbon monoxide (CO), sulfur hexafluoride (SF6), methane (CH4) and nitrous oxide (N2O). Carbon tetrafluoride (CF4) is also present in the product at levels of 20-400mg/L and had to be analysed as well. This paper compares the use of a custom-built dual-channel gas chromatograph utilising single column back flush switching on one channel for the determination of O2, N2, CH4 and CO with column sequence reversal on a second channel for the determination of CO2, N2O, SF6 and CF4 to a similar system using a combination of dual-column back flush and heart-cut configurations. Pulsed discharge helium ionisation detectors were used on both channels in both configurations. PMID:18155712

  20. Detection of Single-Domain Co2FeAl Nanoparticles Using First-Order Reversal Curve Method

    NASA Astrophysics Data System (ADS)

    Alikhanzadeh-Arani, Sima; Almasi-Kashi, Mohammad; Pezeshki-Nejad, Zahra; Ramazani, Abdolali; Salavati-Niasari, Masoud

    2016-07-01

    Half-Heusler nanostructures of Co2FeAl alloys, synthesized via coprecipitation route, were found to contain both hard- and soft-phases magnetic grains, mapped using first-order reversal curves (FORCs) diagrams. The obtained results confirmed that these powders are highly interacting as a single-domain magnetizing system. A significant dependence of the morphology and particle size on the annealing rate was represented by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution TEM images. The presence of the strong magnetizing interaction between the nanoparticles led to the formation of chain-like structure stabilized by PVP polymer. By increasing the annealing rate from 278.15 K/min to 288.15 K/min (5 °C/min to 15 °C/min), the grain shape changed from long nanochain to nonuniform agglomerated grains. Additionally, the magnetic characteristics of the prepared alloys were found to be affected by tuning the annealing rate.

  1. Multifunctional Eu3+- and Er3+/Yb3+-doped GdVO4 nanoparticles synthesized by reverse micelle method

    NASA Astrophysics Data System (ADS)

    Gavrilović, Tamara V.; Jovanović, Dragana J.; Lojpur, Vesna; Dramićanin, Miroslav D.

    2014-02-01

    Synthesis of Eu3+- and Er3+/Yb3+-doped GdVO4 nanoparticles in reverse micelles and their multifunctional luminescence properties are presented. Using cyclohexane, Triton X-100, and n-pentanol as the oil, surfactant, and co-surfactant, respectively, crystalline nanoparticles with ~4 nm diameter are prepared at low temperatures. The particle size assessed using transmission electron microscopy is similar to the crystallite size obtained from X-ray diffraction measurements, suggesting that each particle comprises a single crystallite. Eu3+-doped GdVO4 nanoparticles emit red light through downconversion upon UV excitation. Er3+/Yb3+-doped GdVO4 nanoparticles exhibit several functions; apart from the downconversion of UV radiation into visible green light, they act as upconvertors, transforming near-infrared excitation (980 nm) into visible green light. The ratio of green emissions from 2H11/2 --> 2I15/2 and 4S3/2 --> 4I15/2 transitions is temperature dependent and can be used for nanoscale temperature sensing with near-infrared excitation. The relative sensor sensitivity is 1.11%K-1, which is among the highest sensitivities recorded for upconversion-luminescence-based thermometers.

  2. Multifunctional Eu3+- and Er3+/Yb3+-doped GdVO4 nanoparticles synthesized by reverse micelle method

    PubMed Central

    Gavrilović, Tamara V.; Jovanović, Dragana J.; Lojpur, Vesna; Dramićanin, Miroslav D.

    2014-01-01

    Synthesis of Eu3+- and Er3+/Yb3+-doped GdVO4 nanoparticles in reverse micelles and their multifunctional luminescence properties are presented. Using cyclohexane, Triton X-100, and n-pentanol as the oil, surfactant, and co-surfactant, respectively, crystalline nanoparticles with ~4 nm diameter are prepared at low temperatures. The particle size assessed using transmission electron microscopy is similar to the crystallite size obtained from X-ray diffraction measurements, suggesting that each particle comprises a single crystallite. Eu3+-doped GdVO4 nanoparticles emit red light through downconversion upon UV excitation. Er3+/Yb3+-doped GdVO4 nanoparticles exhibit several functions; apart from the downconversion of UV radiation into visible green light, they act as upconvertors, transforming near-infrared excitation (980 nm) into visible green light. The ratio of green emissions from 2H11/2 → 2I15/2 and 4S3/2 → 4I15/2 transitions is temperature dependent and can be used for nanoscale temperature sensing with near-infrared excitation. The relative sensor sensitivity is 1.11%K−1, which is among the highest sensitivities recorded for upconversion-luminescence-based thermometers. PMID:24572638

  3. Development and validation of a reversed-phase liquid chromatographic method for analysis of estradiol valerate and medroxyprogesterone acetate in a tablet formulation.

    PubMed

    Segall, A; Hormaechea, F; Vitale, M; Perez, V; Pizzorno, M T

    1999-04-01

    A simple and accurate liquid chromatographic method was developed for estimation of estradiol valerate and medroxyprogesterone acetate in pharmaceuticals. Drugs were chromatographed on a reverse phase C18 column, using a mixture (30:70) of ammonium nitrate buffer and acetonitrile and eluants monitored at a wavelength of 280 nm. Solution concentrations were measured on a weight basis to avoid the use of an internal standard. The method was statistically validated for its linearity, accuracy, precision and selectivity. Due to its simplicity and accuracy, the authors believe that the method may be used for routine quality control analysis. It does not require any specific sample preparation except the use of a column guard before the analytical column and suitable prefilter attached to the syringe prior to injection. PMID:10698544

  4. Stability-indicating reversed-phase HPLC method development and characterization of impurities in vortioxetine utilizing LC-MS, IR and NMR.

    PubMed

    Liu, Lei; Cao, Na; Ma, Xingling; Xiong, Kaihe; Sun, Lili; Zou, Qiaogen; Yao, Lili

    2016-01-01

    The current study reports the development and validation of a stability-indicating reversed phase HPLC method for the separation and identification of potential impurities in vortioxetine, a recently developed antidepressant. The structures of a new compound and four process-related impurities formed during the synthesis were characterized and confirmed by NMR, MS, and IR spectroscopy analyses. The most probable formation mechanisms of the impurities identified were proposed. Based on the characterization data, the new compound was proposed to be 1-[4-[(2,4-dimethylphenyl)thio]phenyl]-piperazine. In addition, an efficient chromatographic method was optimized to separate and quantify the impurities, which were obtained in the 0.05-0.75 μg/mL range. The developed HPLC method was validated with respect to accuracy, precision, linearity, robustness, and limits of detection and quantitation. PMID:26412721

  5. Development and evaluation of a culture-independent method for source determination of fecal wastes in surface and storm waters using reverse transcriptase-PCR detection of FRNA coliphage genogroup gene sequences

    EPA Science Inventory

    A complete method, incorporating recently improved reverse transcriptase-PCR primer/probe assays and including controls for determining interferences to phage recoveries from water sample concentrates and for detecting interferences to their analysis, was developed for the direct...

  6. Development and evaluation of a culture-independent method for source determination of fecal wastes in surface and storm waters using reverse transcriptase-PCR detection of FRNA coliphage genogroup gene sequences.

    EPA Science Inventory

    A complete method, incorporating recently improved reverse transcriptase-PCR primer/probe assays and including controls for determining interferences to phage recoveries from water sample concentrates and for detecting interferences to their analysis, was developed for the direct...

  7. Development and validation of a reversed-phase liquid chromatographic method for separation and simultaneous determination of COX-2 inhibitors in pharmaceuticals and its application to biological fluids.

    PubMed

    Rao, R Nageswara; Meena, S; Nagaraju, D; Rao, A Raghu Ram

    2005-06-01

    An isocratic reversed-phase high-performance liquid chromatographic method has been developed for separation and simultaneous determination of COX-2 inhibitors, viz., celecoxib, rofecoxib, valdecoxib, nimesulide and nabumetone, using 4-chloro-2-nitroaniline as internal standard. Good chromatographic separation was achieved using a reversed-phase Inertsil C(18) column with mobile phase consisting of methanol and 0.05% aqueous glacial acetic acid (68:32 v/v) using photodiode array (PDA) detector at 230 nm. It was validated with respect to accuracy, precision, linearity, limit of detection and quantification. The linearity range was found to be 1.0--20 microg/mL and the percentage recoveries were between 97.55 and 100.14. The method is suitable not only for the estimation of active ingredients in pharmaceutical dosage forms but also in vitro estimations in human plasma. It is simple, rapid, selective and capable of detecting and determining COX-2 inhibitors with a detection limit of 0.127--1.040 microg/mL simultaneously. PMID:15627281

  8. Self-Assembled Thermoresponsive Nanogels Prepared by Reverse Micelle → Positive Micelle Method for Ophthalmic Delivery of Muscone, a Poorly Water-Soluble Drug.

    PubMed

    Wang, Guohua; Nie, Qixia; Zang, Chen; Zhang, Baoxian; Zhu, Qiong; Luo, Gan; Wang, Shuang

    2016-09-01

    This study aimed to design a nanocarrier ophthalmic delivery system of muscone, a poorly water-soluble drug. The muscone thermoresponsive nanogels were self-assembled by reverse micelle → positive micelle method. Muscone was demonstrated to have uniform narrow particle size distribution in nanogel by the dynamic light scattering test. The developed nanocomposite hydrogel had a high muscone loading, and the rheology results showed that the phase transition temperature was 34.05°C. Thixotropy test indicated that the nanogel was able to resist the blinking of eyes because of the thixotropy recovery time, which is <5 s. Compared with muscone eye drops, muscone nanogels showed longer retention time on the corneal surface using fluorescent labeling technology and produced a 3.4-fold increase in apparent permeability coefficients (Papp). Draize testing showed that the developed nanogel caused no eye irritation. In vivo pharmacokinetic study indicated that the nanogel could significantly increase the bioavailability of muscone after administration compared with eye drops. These results indicate that self-assembled thermoresponsive nanogel prepared by reverse micelle → positive micelle method has potential for the ophthalmic delivery of poorly water-soluble drugs. PMID:27041413

  9. A rapid hydrolysis method and DABS-Cl derivatization for complete amino acid analysis of octreotide acetate by reversed phase HPLC.

    PubMed

    Akhlaghi, Yousef; Ghaffari, Solmaz; Attar, Hossein; Alamir Hoor, Amir

    2015-11-01

    Octreotide as a synthetic cyclic octapeptide is a somatostatin analog with longer half-life and more selectivity for inhibition of the growth hormone. The acetate salt of octreotide is currently used for medical treatment of somatostatin-related disorders such as endocrine and carcinoid tumors, acromegaly, and gigantism. Octreotide contains both cysteine and tryptophan residues which make the hydrolysis part of its amino acid analysis procedure very challenging. The current paper introduces a fast and additive-free method which preserves tryptophan and cysteine residues during the hydrolysis. Using only 6 M HCl, this hydrolysis process is completed in 30 min at 150 °C. This fast hydrolysis method followed by pre-column derivatization of the released amino acids with 4-N,N-dimethylaminoazobenzene-4'-sulfonyl chloride (DABS-Cl) which takes only 20 min, makes it possible to do the complete amino acid analysis of an octreotide sample in a few hours. The highly stable-colored DABS-Cl derivatives can be detected in 436 nm in a reversed phase chromatographic system, which eliminates spectral interferences to a great extent. The amino acid analysis of octreotide acetate including hydrolysis, derivatization, and reversed phase HPLC determination was validated according to International Conference of Harmonization (ICH) guidelines. PMID:26002809

  10. Fast and sensitive method to determine parabens by capillary electrophoresis using automatic reverse electrode polarity stacking mode: application to hair samples.

    PubMed

    Sako, Alysson V F; Dolzan, Maressa D; Micke, Gustavo Amadeu

    2015-09-01

    This paper describes a fast and sensitive method for the determination of methyl, ethyl, propyl, and butylparaben in hair samples by capillary electrophoresis using automatic reverse electrode polarity stacking mode. In the proposed method, solutions are injected using the flush command of the analysis software (940 mbar) and the polarity switching is carried out automatically immediately after the sample injection. The advantages compared with conventional stacking methods are the increased analytical frequency, repeatability, and inter-day precision. All analyses were performed in a fused silica capillary (50 cm, 41.5 cm in effective length, 50 μm i.d.), and the background electrolyte was composed of 20 mmol L(-1) sodium tetraborate in 10 % of methanol, pH 9.3. For the reverse polarity, -25 kV/35 s was applied followed by application of +30 kV for the electrophoretic run. Temperature was set at 20 °C, and all analytes were monitored at 297 nm. The method showed acceptable linearity (r (2) > 0.997) in the studied range of 0.1-5.0 mg L(-1), limits of detection below 0.017 mg L(-1), and inter-day, intra-day, and instrumental precision better than 6.2, 3.6, and 4.6 %, respectively. Considering parabens is widely used as a preservative in many products and the reported possibility of damage to the hair and also to human health caused by these compounds, the proposed method was applied to evaluate the adsorption of parabens in hair samples. The results indicate that there is a greater adsorption of methylparaben compared to the other parabens tested and also dyed hairs had a greater adsorption capacity for parabens than natural hairs. PMID:26168974

  11. Measurement of hold-up volumes in reverse-phase liquid chromatography Definition and comparison between static and dynamic methods.

    PubMed

    Gritti, Fabrice; Kazakevich, Yuri; Guiochon, Georges

    2007-08-17

    The hold-up volumes, V(M) of two series of RPLC adsorbents were measured using three different approaches. The first method is based on the difference between the volumes of the empty column tube (150x4.6mm) and of the material packed inside the column. It is considered as giving the correct value of V(M). This method combines the results of the BET characterization of the adsorbent before packing (giving the specific pore volume), of carbon element analysis (giving the mass fraction of silica and alkyl bonded chains), of Helium pycnometry (providing silica density), and of inverse size exclusion chromatography (ISEC) performed on the packed column (yielding the interparticle volume). The second method is static pycnometry, which consists in weighing the masses of the chromatographic column filled with two distinct solvents of different densities. The last method is based on the thermodynamic definition of the hold-up volume and uses the dynamic minor disturbance method (MDM) with binary eluents. The experimental results of these three non-destructive methods are compared. They exhibit significant, systematic differences. Pycnometry underestimates V(M) by a few percent for adsorbents having a high carbon content. The results of the MDM method depend strongly on the choice of the binary solution used and may underestimate or overestimate V(M). The hold-up volume V(M) of the RPLC adsorbents tested is best measured by the MDM method using a mixture of ethanol and water. PMID:17610882

  12. Development and validation of reversed phase high performance liquid chromatography method for determination of dexpanthenol in pharmaceutical formulations.

    PubMed

    Kulikov, A U; Zinchenko, A A

    2007-02-19

    This paper describes the validation of an isocratic HPLC method for the assay of dexpanthenol in aerosol and gel. The method employs the Vydac Proteins C4 column with a mobile phase of aqueous solution of trifluoroacetic acid and UV detection at 206 nm. A linear response (r>0.9999) was observed in the range of 13.0-130 microg mL(-1). The method shows good recoveries and intra and inter-day relative standard deviations were less than 1.0%. Validation parameters as specificity, accuracy and robustness were also determined. The method can be used for dexpanthenol assay of panthenol aerosol and gel with dexpanthenol as the method separates dexpanthenol from aerosol or gel excipients. PMID:17049793

  13. Development and validation of a reversed phase liquid chromatographic method for analysis of oxytetracycline and related impurities.

    PubMed

    Kahsay, Getu; Shraim, Fairouz; Villatte, Philippe; Rotger, Jacques; Cassus-Coussère, Céline; Van Schepdael, Ann; Hoogmartens, Jos; Adams, Erwin

    2013-03-01

    A simple, robust and fast high-performance liquid chromatographic method is described for the analysis of oxytetracycline and its related impurities. The principal peak and impurities are all baseline separated in 20 min using an Inertsil C₈ (150 mm × 4.6 mm, 5 μm) column kept at 50 °C. The mobile phase consists of a gradient mixture of mobile phases A (0.05% trifluoroacetic acid in water) and B (acetonitrile-methanol-tetrahydrofuran, 80:15:5, v/v/v) pumped at a flow rate of 1.3 ml/min. UV detection was performed at 254 nm. The developed method was validated for its robustness, sensitivity, precision and linearity in the range from limit of quantification (LOQ) to 120%. The limits of detection (LOD) and LOQ were found to be 0.08 μg/ml and 0.32 μg/ml, respectively. This method allows the separation of oxytetracycline from all known and 5 unknown impurities, which is better than previously reported in the literature. Moreover, the simple mobile phase composition devoid of non-volatile buffers made the method suitable to interface with mass spectrometry for further characterization of unknown impurities. The developed method has been applied for determination of related substances in oxytetracycline bulk samples available from four manufacturers. The validation results demonstrate that the method is reliable for quantification of oxytetracycline and its impurities. PMID:23277151

  14. Rapid and sensitive method for the determination of sibutramine active metabolites in human plasma by reversed-phase liquid chromatography-tandem mass spectroscopy.

    PubMed

    Bhatt, Jignesh; Shah, Bhavin; Kambli, Sandeep; Subbaiah, Gunta; Singh, Sadhana; Ameta, Suresh

    2007-02-01

    A new, rapid, and sensitive liquid chromatography-tandem mass spectrometry method is developed and validated to quantitate the sibutramine active metabolites mono desmethyl sibutramine (M1) and di-desmethyl sibutramine (M2) using imipramine as the internal standard in human plasma samples for routine bioequivalence studies. The method involves rapid solid-phase extraction from plasma, eliminating the drying and reconstitution steps. The analytes are chromatographed on a C8 reversed-phase chromatographic column and analyzed by mass spectrometry in the multiple reaction monitoring mode, which enables a quantitation limit at the sub-nanogram level. The method has a chromatographic run time of 2.8 min. The proposed method is validated with a linear range of 0.1-8.0 and 0.2-16.0 ng/mL for M1 and M2, respectively, with a correlation coefficient of regression > or = 0.9990. The method is sensitive and reproducible, having intra- and inter-assay precision at the lower limit of quantitation (0.1 ng/mL for M1 and 0.2 ng/mL for M2) < 10.0%. The overall recovery for M1 and M2 is 93.5% and 77.9%, respectively. The method has been applied to a bioequivalence clinical study with great success. PMID:17425138

  15. Spectrophotometric and reversed-phase high-performance liquid chromatographic methods for simultaneous determination of escitalopram oxalate and clonazepam in combined tablet dosage form.

    PubMed

    Gandhi, Santosh Vilashchand; Dhavale, Nilesh Dnyandev; Jadhav, Vijay Yeshawantrao; Sabnis, Shweta Sadanand

    2008-01-01

    Simple, accurate, precise, and sensitive ultraviolet spectrophotometric and reversed-phase high-performance liquid chromatographic (RP-HPLC) methods for simultaneous estimation of escitalopram oxalate (ESC) and clonazepam (CLO) in combined tablet dosage form have been developed and validated. The spectroscopic method employs an absorbance correction method using 238.6 and 308 nm as 2 wavelengths for estimation with methanol and water as solvents. Beer's law is obeyed in the concentration range of 10.0-50.0 and 0.5-3.0 micro/mL for ESC and CLO, respectively. The RP-HPLC method uses a Jasco HPLC system with HiQ SiL C18 column (250 x 4.6 mm id) acetonitrile-0.005 M tetrabutylammonium hydrogen sulfate (55 + 45, v/v) as the mobile phase, and satranidazole as an internal standard. The detection was carried out using an ultraviolet detector set at 287 nm. For the HPLC method, Beer's law is obeyed in the concentration range of 10.0-60.0 and 0.5-3.0 microg/mL for ESC and CLO, respectively. Both methods have been successfully applied for the analysis of the drugs in a pharmaceutical formulation. Results of analysis were validated statistically and by recovery studies. PMID:18376583

  16. Development and validation of a reversed-phase high-performance liquid chromatography method for routine identification and purity assessment of high-purity steviol glycoside sweeteners.

    PubMed

    Bililign, Tsion; Moore, Jeffrey C; Tan, Shane; Leeks, Allan T

    2014-02-12

    The widespread application of stevia-based sweeteners in food products has resulted in the need for reliable analytical methods for measuring the purity and identity of high-purity steviol glycoside ingredients. The objective of this research was to develop and validate a new reversed-phase separation method capable of separating and quantifying nine steviol glycosides present in typical high-purity stevia extract ingredients. Results of the study established the linearity of the method at a correlation factor of 1.000 for the two major components and other minor components of this food ingredient. Method accuracy values were in the range of 99.1-100.9%. The percent relative standard deviation for six independent assay determinations was 1.0%. The method was determined to be robust for minor changes in column temperature, initial acetonitrile content, flow rate, and wavelength. The validated high-performance liquid chromatography method was found to be suitable to be included by USP as a Food Chemicals Codex compendial standard for steviol glycosides. PMID:24443893

  17. Development and validation of reversed phase high-performance liquid chromatography method for estimation of lercanidipine HCl in pure form and from nanosuspension formulation

    PubMed Central

    Chonkar, Ankita D.; Managuli, Renuka S.; Rao, Josyula Venkata; Udupa, Nayanabhirama

    2015-01-01

    Aim: Quantitative estimation of lercanidipine HCl in bulk material as well as from nanosuspension formulations via a developed reverse phase HPLC method. Materials and Methods: Optimized chromatographic condition was used to achieve separation on a Kromasil (100-5c18 250 × 4.6 mm) column using Shimadzu HPLC system. The mobile phase consisted of a mixture of acetate buffer (20 mM pH 4.5) and acetonitrile in the ratio of 10:90, v/v. It is pumped through the chromatographic system at a flow rate of 1 ml/min. The detection was carried out at 240 nm using ultraviolet-visible spectrophotometry detector. The method was validated as per Q2 (R1) guidelines, and suitability of the developed method was established by optimized nanosuspension formulation. Results: The method is specific to lercanidipine (RT: 7.7 min), and has ability to resolve the analyte peak from excipient interferences. It is linear (regression coefficient: 0.9993), accurate (average recovery: 100%), and passed all the system suitability requirements. Conclusion: Developed method was found applicable for evaluation of drug content, content uniformity, and analyzing samples of dissolution studies of nanosuspension. PMID:26792958

  18. Fine-tuning of catalytic tin nanoparticles by the reverse micelle method for direct deposition of silicon nanowires by a plasma-enhanced chemical vapour technique.

    PubMed

    Poinern, Gérrard E J; Ng, Yan-Jing; Fawcett, Derek

    2010-12-15

    The reverse micelle method was used for the reduction of a tin (Sn) salt solution to produce metallic Sn nanoparticles ranging from 85 nm to 140 nm in diameter. The reverse micellar system used in this process was hexane-butanol-cetyl trimethylammonium bromide (CTAB). The diameters of the Sn nanoparticles were proportional to the concentration of the aqueous Sn salt solution. Thus, the size of the Sn nanoparticles can easily be controlled, enabling a simple, reproducible mechanism for the growth of silicon nanowires (SiNWs) using plasma-enhanced chemical vapour deposition (PECVD). Both the Sn nanoparticles and silicon nanowires were characterised using field-emission scanning electron microscopy (FE-SEM). Further characterisations of the SiNW's were made using transmission electron microscopy (TEM), atomic force microscopy (AFM) and Raman spectroscopy. In addition, dynamic light scattering (DLS) was used to investigate particle size distributions. This procedure demonstrates an economical route for manufacturing reproducible silicon nanowires using fine-tuned Sn nanoparticles for possible solar cell applications. PMID:20887996

  19. A simple method for the synthesis of a polar-embedded and polar-endcapped reversed-phase chromatographic packing with low activity of residue silanols.

    PubMed

    Liu, Hai-Yan; Li, Zhi-Yong; Liu, Dan; Xue, Ying-Wen; Shi, Zhi-Guo

    2016-04-22

    Octadecyl bonded silica (ODS) is the most popular packing for reversed-phase chromatography. However, it generally demonstrates bad resolution for polar analytes because of the residue silanols and its poor stability in aqueous mobile phase. To address the problem, a new reversed-phase packing containing both polar-embedded and polar-endcapped moieties was proposed. It was prepared by a very simple method, in which the epoxide addition reaction of 3-glycidoxypropyltrimethoxysilane with 1-octadecanethiol proceeded simultaneously with the reaction of silane coupling onto silica particles. By controlling the molecular ratio of 3-glycidoxypropyltrimethoxysilane to 1-octadecanethiol higher than 1.0 (1.56 for the present study), both polar-embedded and polar-endcapped moieties were achieved onto the packing. The performance of the packing was evaluated in detail. The results demonstrated that neutral, acidic and basic analytes were well separated on the packing. The column efficiency for phenanthrene was 34,200 theoretical plates per meter. In addition, four nucleotides can be separated in 100% phosphate buffered saline solution with good reproducibility, which indicates the packing has good stability in aqueous mobile phase. Amitriptyline, a typical basic analytes, was eluted out with relatively symmetric peak shape (asymmetry factor of 1.36), which implies that the packing has not suffered from the negative effect of residue silanols significantly. Good stability in buffer solution of pH ranging from 2.0 to 10.0 was also documented for the packing. PMID:27033982

  20. TRI2SOLID: an application of reverse engineering methods to the creation of CAD models of bone segments.

    PubMed

    Viceconti, M; Zannoni, C; Pierotti, L

    1998-06-01

    For many biomechanical engineering activities it would be useful to have the three dimensional (3D) geometry of bone segments available in form of vectorial models within computer aided design (CAD) environments. In this paper a new method for the semi-automatic conversion of a stack of CT images of a femur into a CAD solid model is described. This method is relatively simple, accurate, and requires only a 3D CAD plus a few additional programs available in the public domain. The proposed method was used to convert the CT scan data set of a human femur into a valid CAD model; the resulting solid was two times more accurate than that obtained using the commonly used procedure based on 2D segmentation. PMID:9725647

  1. Method to Calculate the Protamine Dose Necessary for Reversal of Heparin as a Function of Activated Clotting Time in Patients Undergoing Cardiac Surgery

    PubMed Central

    Cuenca, Javier Suárez; Diz, Pilar Gayoso; Sampedro, Francisco Gude; Zincke, J. Marcos Gómez; Acuña, Helena Rey; Fontanillo, M. Manuela Fontanillo

    2013-01-01

    Abstract: Activated clotting time (ACT) has been used to monitor coagulation and guide management of anticoagulation control in patients undergoing cardiac surgery for decades. However, reversal of heparin with protamine is typically empirically based on total heparin administered. Dose-related adverse effects of protamine are well described. The aim of this study was to evaluate a heparin reversal strategy based on calculation of the protamine dose based on ACT measurements. We present a method using a mathematical formula based on the dose–response line (1). To check the formula, we performed a retrospective observational cohort study of 177 patients undergoing cardiac surgery with cardiopulmonary bypass (CPB). The study group of 80 patients was administered the dose of protamine obtained using our formula, and the control group of 97 patients was administered the empirically calculated dose. The ACT returned to normal values in patients who were given doses of protamine that were calculated using our formula; all but two had a final ACT of 141. The application of the formula resulted in a significant reduction in the dose of protamine (p < .023). The formula we present is a valid method for calculating the dose of protamine necessary to neutralize heparin. This same method can be used working with a target ACT to adjust the dose of heparin. As a result of its functionality, it allows application on a daily basis standardizing the process. We believe that the formula we developed can be applied in all those procedures in which it is necessary to anticoagulate patients with heparin and later neutralization (cardiac surgery with or without CPB, vascular surgery, procedures of interventional cardiology, and extracorporeal depuration procedures). PMID:24649571

  2. Development and validation of a stability-indicating reversed-phase high performance liquid chromatography method for assay of betamethylepoxide and estimation of its related compounds.

    PubMed

    Xiao, Kang Ping; Chien, Dwight; Markovich, Robert; Rustum, Abu M

    2007-07-20

    Betamethylepoxide (16beta-methyl-Delta(1,4)-pregnadiene-9beta-11beta-oxide-17alpha,21-diol-3,20-dione) is a key intermediate for the synthesis of various active pharmaceutical ingredients (APIs) of steroid compounds. A stability-indicating reversed-phase HPLC method for assay of betamethylepoxide and estimation of its related compounds has been developed and validated. This method can accurately quantitate betamethylepoxide in the presence of numerous structurally related compounds (including the alpha-epimer, known as alphamethylepoxide). This method can also adequately separate most of the impurities from each other and estimate their quantities in betamethylepoxide samples. The stability-indicating capability of this method has been demonstrated by adequate separation of the degradation products from betamethylepoxide in stress degraded and aged stability samples. The HPLC column used in the method was a 5 cm YMC Hydrosphere C(18) column (4.6 mm I.D.) and the mobile phase consisted of (A) water and (B) acetonitrile:methanol (8:25, v/v). PMID:17512937

  3. A novel extraction method based on a reversible chemical conversion for the LC/MS/MS analysis of the stable organic germanium compound Ge-132.

    PubMed

    Yamaguchi, Hiroaki; Shimada, Yasuhiro; Takeda, Tomoya; Nakamura, Takashi; Mano, Nariyasu

    2015-02-17

    Poly trans-[(2-carboxyethyl)germasesquioxane] (IUPAC name) is the most common water-soluble organic germanium compound. This compound is known as bis(carboxyethyl)germaniumsesquioxide and it is commonly called Ge-132; it is hydrolyzed to 3-(trihydroxygermyl)propanoic acid (THGPA) in water. We have developed a method for the quantification of THGPA in rat plasma, using a novel extraction method based on a reversible chemical conversion. THGPA in plasma is converted to 3-(trichlorogermyl)propanoic acid (TCGPA) under acidic conditions using concentrated hydrochloride, which is followed by extraction with chloroform. TCGPA is then converted back to THGPA through hydrolysis. The extraction recovery of this method is approximately 100%. Moreover, we synthesized deuterated Ge-132, which was used as an internal standard in our experiments. This method covers a linearity range of 0.01-5 μg/mL for concentrations of THGPA in plasma. The intra-day and inter-day precisions of the analysis are about 4.1%, and the accuracy is within ±2.6% at THGPA concentrations of 0.025, 0.25, and 2.5 μg/mL. The total run time is 5 min. Our method was successfully applied to a pharmacokinetic investigation following oral administration of Ge-132. PMID:25621844

  4. Preparation of AgCl-polyacrylamide composite microspheres via combination of a polymer microgel template method and a reverse micelle technique.

    PubMed

    Zhang, Ying; Fang, Yu; Xia, Huiyun; Xie, Yuxia; Wang, Ruifang; Li, Xuejun

    2006-08-01

    A new route was created for the preparation of AgCl-polyacrylamide (AgCl-PAM) composite microspheres with patterned surface structures. The route is a combination of a polymer microgel template method and a reverse micelle technique. The size of the AgCl nanoparticles existing on the surfaces of the composite microspheres and the clearness of the surface patterns of the composite microspheres can be altered by simply adjusting the amount of precipitated AgCl and the rate of the deposition reaction. The route can be also used for the preparation of other water-insoluble salt-polymer composite microspheres, such as BaSO(4)-PAM. It is expected that the composite microspheres with patterned surface structures may not only combine the advantages of polymers and those of inorganic compounds, but also combine the advantages of microspheres in the micrometer size range and those in the nanometer size range. PMID:16678839

  5. Development and validation of reversed-phase column high-performance liquid chromatographic and first-derivative UV spectrophotometric methods for estimation of voriconazole in oral suspension powder.

    PubMed

    Prajapati, Arun M; Patel, Satish A; Patel, Natvarlal J; Patel, Dipti B; Patel, Sejal K

    2008-01-01

    This research paper describes validated reversed-phase high-performance column liquid chromatographic (RP-HPLC) and first-derivative UV spectrophotometric methods for the estimation of voriconazole (VOR) in oral suspension powder. The RP-HPLC separation was achieved on Phenomenex C18 column (250 x 4.6 mm id, 5 microm particle size) using water-acetonitrile (40 + 60, v/v; pH adjusted to 4.5 +/- 0.02 with acetic acid) as the mobile phase at a flow rate of 1.4 mL/min and ambient temperature. Quantification was achieved with photodiode array detection at 255 nm over the concentration range of 0.1-1 microg/mL with mean recovery of 99.49 +/- 0.83% for VOR by the RP-HPLC method. Quantification was achieved with UV detection at 266 nm over the concentration range of 8-20 microg/mL with mean recovery of 99.74 +/- 0.664% for VOR by the first-derivative UV spectrophotometric method. These methods are simple, precise, and sensitive, and they are applicable for the determination of VOR in oral suspension powder. PMID:18980120

  6. Improving reversal median computation using commuting reversals and cycle information.

    PubMed

    Arndt, William; Tang, Jijun

    2008-10-01

    In the past decade, genome rearrangements have attracted increasing attention from both biologists and computer scientists as a new type of data for phylogenetic analysis. Methods for reconstructing phylogeny from genome rearrangements include distance-based methods, MCMC methods, and direct optimization methods. The latter, pioneered by Sankoff and extended with the software suites GRAPPA and MGR, is the most accurate approach, but is very limited due to the difficulty of its scoring procedure--it must solve multiple instances of the reversal median problem to compute the score of a given tree. The reversal median problem is known to be NP-hard and all existing solvers are extremely slow when the genomes are distant. In this paper, we present a new reversal median heuristic for unichromosomal genomes. The new method works by applying sets of reversals in a batch where all such reversals both commute and do not break the cycle of any other. Our testing using simulated datasets shows that this method is much faster than the leading solver for difficult datasets with only a slight accuracy penalty, yet retains better accuracy than other heuristics with comparable speed, and provides the additional option of searching for multiple medians. This method dramatically increases the speed of current direct optimization methods and enables us to extend the range of their applicability to organellar and small nuclear genomes with more than 50 reversals along each edge. PMID:18774904

  7. Two Coils Resonant Ramsey’s Method for the Measurement of Time Reversal Invariance Violation in Neutron Transmission

    PubMed Central

    Loukachevitch, V. V.; Aldushchenkov, A. V.

    2005-01-01

    It is proposed within the framework of Ramsey’s method to register two-dimensional spectra, depending on the neutron phase and neutron energy, for measuring parity (P) and time (T) violating amplitudes of the interaction of polarized neutrons with polarized 139La nuclei in region of the p-wave resonance. The form of the phase spectrum and corresponding expressions for the asymmetries are obtained on the basis of a formalism of a spin density matrix. It is shown that the ratio of the P,T,-violating to P-violating imaginary amplitudes can be obtained from the measurements of the neutron phase spectrum with polarized and unpolarized 139La target. PMID:27308169

  8. Rapid evaluation of reverse-osmosis membranes

    NASA Technical Reports Server (NTRS)

    Hollahan, J. R.; Wydeven, T.

    1972-01-01

    Simultaneous reverse-osmosis tests conducted with centrifuges having multiple compartment heads are discussed. Equipment for retaining reverse-osmosis membrane is illustrated. Method of conducting tests is described.

  9. A method of reversible biomolecular immobilization for the surface plasmon resonance quantitative analysis of interacting biological macromolecules.

    PubMed

    Benítez, María J; Jiménez, Juan S

    2002-03-15

    This article presents a new procedure for the immobilization of macromolecules on gold surfaces, with the purpose of studying macromolecular interactions by simple optical configurations rendering surface plasmon resonance. Gold surfaces were covered by a three-layer structure composed of poly-L-lysine irreversibly bound to gold, followed by a second layer of heparin and a third layer of polylysine. The three-layer structure of polylysine-heparin-polylysine remains irreversibly bound to gold, it prevents biomolecules from coming into direct contact with the metal surface, and it allows the irreversible binding of different proteins and polynucleotides. After binding of a macromolecule to the three-layer structure, the interaction with a second macromolecule can be studied, and then the complex formed by the two interacting macromolecules, together with the second heparin layer and the third polylysine layer, can be broken down just by treatment with an alkaline solution having a pH value above the pK value of the amino groups of polylysine. The first polylysine layer remains irreversibly bound to gold, ready to form a new three-layer structure and, therefore, to support a new macromolecular interaction on the same regenerated surface. Polynucleotide interactions, the proteolytic action of chymotrypsin, and the interaction between the component subunits of a heterotetrameric enzyme are described as examples of macromolecular interactions studied by using this system. The method may be especially suitable for developing of low-cost systems aimed to look for surface resonance signals, and it offers the advantage of allowing calculation of parameters related to the size and stoichiometry of the interacting macromolecules, in addition to the kinetic and equilibrium properties of the interaction. PMID:11878793

  10. Apparatus and method for controlling the rotary airlocks in a coal processing system by reversing the motor current rotating the air lock

    DOEpatents

    Groombridge, Clifton E.

    1996-01-01

    An improvement to a coal processing system where hard materials found in the coal may cause jamming of either inflow or outflow rotary airlocks, each driven by a reversible motor. The instantaneous current used by the motor is continually monitored and compared to a predetermined value. If an overcurrent condition occurs, indicating a jamming of the airlock, a controller means starts a "soft" reverse rotation of the motor thereby clearing the jamming. Three patterns of the motor reversal are provided.

  11. A high pH based reversed-phase high performance liquid chromatographic method for the analysis of aminoglycoside plazomicin and its impurities.

    PubMed

    Tan, Li; Wlasichuk, Kenneth B; Schmidt, Donald E; Campbell, Robert L; Hirtzer, Pam; Cheng, Lisa; Karr, Dane E

    2012-07-01

    A reversed-phase high performance liquid chromatographic (RP-HPLC) method has been developed for the aminoglycoside (AG) plazomicin (ACHN-490). This method employed a high pH mobile phase (pH>11) with a gradient of 0.25 M ammonium hydroxide in water and acetonitrile, an XBridge C(18) column and UV detection at 210 nm. Although the molar UV absorption of plazomicin is weak, the high pH conditions of this method allow for higher loadings, which compensates for the inherent low UV sensitivity. Under these high pH conditions, impurities and degradants were base line separated from plazomicin. The mobile phases used for this method allowed for on-line mass detection for the impurities and degradants. The RP-HPLC method has been validated in terms of specificity, linearity and range, accuracy, and precision. The analytical method met specificity requirements of a homogenous peak with no interferences from the blank or from the known impurities in plazomicin. The linearity of the method for the plazomicin impurity determination was excellent, with a coefficient of determination (r(2)) of 0.9993, over the freebase (FB) concentration range of 0.0025-3.0 mg/mL. The method is capable of detecting impurities down to 0.1% of the peak area of plazomicin. A single point standard at a concentration of 1.0 mg/mL FB was validated over the range of 50-150% for quantitation of the freebase content (the assay) in bulk drug substance. The mean recoveries of FB are in the range 98.6-102.0% with a mean RSD (relative standard deviation) <1.0%. The study also examined the method precision for purity, impurities and the assay with two instruments on two different days. The method showed adequate accuracy and precision for the intended use. This high pH method was successfully used to determine the impurity and measure the drug content in the final plazomicin drug substance. In addition, the method with an on-line mass spectrometry detector has been used to characterize the structures of the

  12. Optimization of a reversed-phase high-performance liquid chromatography/mass spectrometry method for characterizing recombinant antibody heterogeneity and stability.

    PubMed

    Dillon, Thomas M; Bondarenko, Pavel V; Rehder, Douglas S; Pipes, Gary D; Kleemann, Gerd R; Ricci, Margaret Speed

    2006-07-01

    An enhanced analytical RP-HPLC/MS method was developed for monitoring the stability and production of intact and fragmented monoclonal antibodies (MAbs). The use of high column temperatures (70-80 degrees C), organic solvents with high eluotropic strength coefficients (isopropyl and n-propyl alcohols), and Zorbax StableBond columns, were critical for good recovery and resolution of immunoglobulin G1 (IgG1) and IgG2 monoclonal antibodies. Using this method, cleavage products of a degraded IgG1 antibody were clearly separated and identified by in-line electrospray ionization time-of-flight (ESI-TOF) mass spectrometry generating exact masses and unique terminal ladder sequences. The glycosylation profile, including mapping of the terminal galactose and fucose heterogeneity of the N-linked sugars, was determined by mass spectrometry of intact MAbs. In addition, we discovered that several IgG2 MAbs exhibited greater structural heterogeneity compared to IgG1s. Mass spectral characterization data and reduction data suggested that the heterogeneity is disulfide related. This reversed-phase LC/MS method represents a key advancement in monitoring intact MAb production and stability. PMID:16448656

  13. Development of a Reverse Transcription Loop-Mediated Isothermal Amplification Method for the Rapid Detection of Subtype H7N9 Avian Influenza Virus

    PubMed Central

    Bao, Hongmei; Zhao, Yuhui; Wang, Yunhe; Xu, Xiaolong; Shi, Jianzhong; Zeng, Xianying; Wang, Xiurong; Chen, Hualan

    2014-01-01

    A novel influenza A (H7N9) virus has emerged in China. To rapidly detect this virus from clinical samples, we developed a reverse transcription loop-mediated isothermal amplification (RT-LAMP) method for the detection of the H7N9 virus. The minimum detection limit of the RT-LAMP assay was 0.01 PFU H7N9 virus, making this method 100-fold more sensitive to the detection of the H7N9 virus than conventional RT-PCR. The H7N9 virus RT-LAMP assays can efficiently detect different sources of H7N9 influenza virus RNA (from chickens, pigeons, the environment, and humans). No cross-reactive amplification with the RNA of other subtype influenza viruses or of other avian respiratory viruses was observed. The assays can effectively detect H7N9 influenza virus RNA in drinking water, soil, cloacal swab, and tracheal swab samples that were collected from live poultry markets, as well as human H7N9 virus, in less than 30 min. These results suggest that the H7N9 virus RT-LAMP assays were efficient, practical, and rapid diagnostic methods for the epidemiological surveillance and diagnosis of influenza A (H7N9) virus from different resource samples. PMID:24689044

  14. Development and validation of a reversed-phase HPLC method for simultaneous estimation of ambroxol hydrochloride and azithromycin in tablet dosage form.

    PubMed

    Shaikh, K A; Patil, S D; Devkhile, A B

    2008-12-15

    A simple, precise and accurate reversed-phase liquid chromatographic method has been developed for the simultaneous estimation of ambroxol hydrochloride and azithromycin in tablet formulations. The chromatographic separation was achieved on a Xterra RP18 (250 mm x 4.6 mm, 5 microm) analytical column. A Mixture of acetonitrile-dipotassium phosphate (30 mM) (50:50, v/v) (pH 9.0) was used as the mobile phase, at a flow rate of 1.7 ml/min and detector wavelength at 215 nm. The retention time of ambroxol and azithromycin was found to be 5.0 and 11.5 min, respectively. The validation of the proposed method was carried out for specificity, linearity, accuracy, precision, limit of detection, limit of quantitation and robustness. The linear dynamic ranges were from 30-180 to 250-1500 microg/ml for ambroxol hydrochloride and azithromycin, respectively. The percentage recovery obtained for ambroxol hydrochloride and azithromycin were 99.40 and 99.90%, respectively. Limit of detection and quantification for azithromycin were 0.8 and 2.3 microg/ml, for ambroxol hydrochloride 0.004 and 0.01 microg/ml, respectively. The developed method can be used for routine quality control analysis of titled drugs in combination in tablet formulation. PMID:18993009

  15. Validated Stability-indicating Reverse-phase Ultra-performance Liquid Chromatography Method for Simultaneous Determination of Sodium Methylparaben, Sodium Propylparaben and Ketorolac Tromethamine in Topical Dosage Forms

    PubMed Central

    Roy, C.; Chakrabarty, J.; Modi, P. B.

    2013-01-01

    A sensitive, fast, and stability-indicating isocratic reverse-phase ultra-performance liquid chromatography method was developed and validated for quantitative simultaneous determination of sodium methylparaben, sodium propylparaben and ketorolac tromethamine in topical dosage forms. Separation of all peaks was achieved by using acquity ethylene bridged hybrid C18 (50×2.1 mm, 1.7 μ) as stationary phase, mobile phase used was triethylamine buffer (pH 2.5):tetrahydrofuran:methanol (665:35:300, v/v/v) with isocratic mode at a flow rate of 0.40 ml/min. All component were detected at 252 nm with 10 min run time. The described method was found to be linear in the concentration range of 248-744 μg/ml for ketorolac tromethamine, 20.8-62.4 μg/ml for sodium methylparaben and 2.38-7.13 μg/ml for sodium propylparaben with correlation coefficients more than 0.999. Method was validated in terms of specificity, linearity, accuracy, precision, solution stability, filter equivalency, and robustness as per International Conference on Harmonization guideline. Formulation was exposed to the stress conditions of peroxide, acid, base, thermal, and photolytic degradation and proven all components were well separated in the presence of degradants. PMID:24019569

  16. Stability-indicating capillary zone electrophoresis method for the assessment of recombinant human interleukin-11 and its correlation with reversed-phase liquid chromatography and biossay.

    PubMed

    Souto, Ricardo Bizogne; Stamm, Fernanda Pavani; Schumacher, Jéssica Barbieri; Cardoso, Clovis Dervil Appratto; de Freitas, Guilherme Weber; Perobelli, Rafaela Ferreira; Dalmora, Sérgio Luiz

    2014-06-01

    A stability-indicating capillary zone electrophoresis (CZE) method was validated for the analysis of recombinant human interleukin-11(rhIL-11) using rupatadine fumarate, as internal standard (IS). A fused-silica capillary, (50 µm i.d.; effective length, 40 cm) was used at 25°C; the applied voltage was 20 kV. The background electrolyte solution consisted of 50 mmol L(-1) sodium dihydrogen phosphate solution at pH 3.0. Injections were performed using a pressure mode at 50 mbar for 45 s, with detection by photodiode array detector set at 196 nm. Specificity and stability-indicating capability were established in degradation studies, which also showed that there was no interference of the excipients. The method was linear over the concentration range of 1.0-300 µg mL(-1) (r(2)=0.9992) and the limit of detection (LOD) and limit of quantitation (LOQ) were 0.2 µg mL(-1) and 1.0 µg mL(-1), respectively. The accuracy was 100.4% with bias lower than 1.1%. Moreover, the in vitro cytotoxicity test of the degraded products showed significant differences (p<0.05). The method was applied for the content/potency assessment of rhIL-11 in biopharmaceutical formulations, and the results were correlated to those of a validated reversed-phase LC method (RP-LC) and an TF-1 cell culture assay, showing non-significant differences (p>0.05). In addition the CZE and RP-LC methods were applied for the analysis of rhIL-11 in human plasma. Therefore, the proposed alternative method can be applied to monitor stability, to assure the batch-to-batch consistency and quality of the bulk and finished biotechnology-derived medicine. PMID:24725881

  17. Detection of Avian Retroviruses in Vaccines by Amplification on DF-1 Cells with Immunostaining and Fluorescent Product-Enhanced Reverse Transcriptase Endpoint Methods

    PubMed Central

    Dupont, Dominique; Riou, Patrice; Armanet, Corinne; Edamura, Kerrie Nichol; Martinho, Briolange; Serres, Aurelie; Jacouton, Severine; Detrez, Valerie; McNeil, Bryan; Schreiber, Martha; Gaillac, David; Bonnevay, Thierry; Gisonni-Lex, Lucy; Mallet, Laurent

    2013-01-01

    In order to ensure the safety of vaccines produced on avian cells, rigorous testing for the absence of avian retroviruses must be performed. Current methods used to detect avian retroviruses often exhibit a high invalid-test/false-positive rate, rely on hard-to-secure reagents, and/or have readouts that are difficult to standardize. Herein, we describe the development and validation of two consistent and sensitive methods for the detection of avian retroviruses in vaccines: viral amplification on DF-1 cells followed by immunostaining for the detection of avian leukosis virus (ALV) and viral amplification on DF-1 cells followed by fluorescent product-enhanced reverse transcriptase (F-PERT) for the detection of all avian retroviruses. Both assays share an infectivity stage on DF-1 cells followed by a different endpoint readout depending on the retrovirus to be detected. Validation studies demonstrated a limit of detection of one 50% cell culture infectious dose (CCID50)/ml for retrovirus in a 30-ml test inoculum volume for both methods, which was as sensitive as a classical method used in the vaccine industry, namely, viral amplification on primary chicken embryo fibroblasts followed by the complement fixation test for avian leukosis virus (COFAL). Furthermore, viral amplification on DF-1 cells followed by either immunostaining or F-PERT demonstrated a sensitivity that exceeds the regulatory requirements for detection of ALV strains. A head-to-head comparison of the two endpoint methods showed that viral amplification on DF-1 cells followed by F-PERT is a suitable method to be used as a stand-alone test to ensure that vaccine preparations are free from infectious avian retroviruses. PMID:23467603

  18. Multi-walled carbon nanotubes as alternative reversed-dispersive solid phase extraction materials in pesticide multi-residue analysis with QuEChERS method.

    PubMed

    Zhao, Pengyue; Wang, Lei; Zhou, Li; Zhang, Fengzu; Kang, Shu; Pan, Canping

    2012-02-17

    A multi-residue method based on modified QuEChERS sample preparation with multi-walled carbon nanotubes (MWCNTs) as reversed-dispersive solid phase extraction (r-DSPE) material and gas chromatography-mass spectrometry determination by selected ion monitoring (GC/MS-SIM) mode was validated on 30 representative pesticides residues in vegetables and fruits. The acetonitrile-based QuEChERS (quick, easy, cheap, effective, rugged and safe) sample preparation technique was used to obtain the extracts, and the further cleanup was carried out by applying r-DSPE. It was found that the amount of MWCNTs influenced the cleanup performance and the recoveries. The optimal amount of 10mg MWCNTs was suitable for cleaning up all selected matrices, as a suitable alternative r-DSPE material to primary secondary amine (PSA). This method was validated on cabbage, spinach, grape and orange spiked at concentration levels of 0.02 and 0.2 mg/kg. The recoveries of 30 pesticides were in the range of 71-110%, with relative standard deviations (RSDs, n=5) lower than 15%. Matrix effects were observed by comparing the slope of matrix-matched standard calibration with that of solvent. Good linearity was achieved at the concentration levels of 0.02-0.5 mg/L. The limits of quantification (LOQs) and the limits of detection (LODs) for 30 pesticides ranged from 0.003 to 0.05 mg/kg and 0.001 to 0.02 mg/kg at the signal-to-noise ratio (S/N) of 10 and 3, respectively. The method was successfully applied to analysis real samples in Beijing. In conclusion, the modified QuEChERS method with MWCNTs cleanup step showed reliable method validation performances and good cleanup effects in this study. PMID:22227363

  19. New In Situ Capture Quantitative (Real-Time) Reverse Transcription-PCR Method as an Alternative Approach for Determining Inactivation of Tulane Virus

    PubMed Central

    Wang, Dapeng; Xu, Shuxia; Yang, David; Young, Glenn M.

    2014-01-01

    Human noroviruses (HuNoVs) are the major cause of epidemic nonbacterial gastroenteritis. Although quantitative (real-time) reverse transcription-PCR (qRT-PCR) is widely used for detecting HuNoVs, it only detects the presence of viral RNA and does not indicate viral infectivity. Human blood group antigens (HBGAs) have been identified as receptors/co-receptors for both HuNoVs and Tulane virus (TV) and are crucial for viral infection. We propose that viral infectivity can be evaluated with a molecular assay based on receptor-captured viruses. In this study, we employed TV as an HuNoV surrogate to validate the HBGA-based capture qRT-PCR method against the 50% tissue culture infectious dose (TCID50) method. We employed type B HBGA on an immuno-well module to concentrate TV, followed by amplification of the captured viral genome by in situ qRT-PCR. We first demonstrated that this in situ capture qRT-PCR (ISC-qRT-PCR) method could effectively concentrate and detect TV. We then treated TV under either partial or full inactivation conditions and measured the remaining infectivity by ISC-qRT-PCR and a tissue culture-based amplification method (TCID50). We found that the ISC-qRT-PCR method could be used to evaluate virus inactivation deriving from damage to the capsid and study interactions between the capsid and viral receptor. Heat, chlorine, and ethanol treatment primarily affect the capsid structure, which in turns affects the ability of the capsid to bind to viral receptors. Inactivation of the virus by these methods could be reflected by the ISC-qRT-PCR method and confirmed by TCID50 assay. However, the loss of the infectivity caused by damage to the viral genome (such as that from UV irradiation) could not be effectively reflected by this method. Despite this limitation, the ISC-qRT-PCR provides an alternative approach to determine inactivation of Tulane virus. A particular advantage of the ISC-qRT-PCR method is that it is also a faster and easier method to effectively

  20. [Reverse Chaddock sign].

    PubMed

    Tashiro, Kunio

    2011-08-01

    It is widely accepted that the Babinski reflex is the most well-known and important pathological reflex in clinical neurology. Among many other pathological reflexes that elicit an upgoing great toe, such as Chaddock, Oppenheim, Gordon, Schaefer, and Stransky, only the Chaddock reflex is said to be as sensitive as the Babinski reflex. The optimal receptive fields of the Babinski and Chaddock reflexes are the lateral plantar surface and the external inframalleolar area of the dorsum, respectively. It has been said that the Babinski reflex, obtained by stroking the sole, is by far the best and most reliable method of eliciting an upgoing great toe. However, the Chaddock reflex, the external malleolar sign, is also considered sensitive and reliable according to the literature and everyday neurological practice. The major problems in eliciting the Babinski reflex by stroking the lateral part of the sole are false positive or negative responses due to foot withdrawal, tonic foot response, or some equivocal movements. On the other hand, according to my clinical experience, the external inframalleolar area, which is the receptive field of the Chaddock reflex, is definitely suitable for eliciting the upgoing great toe. In fact, the newly proposed method to stimulate the dorsum of the foot from the medial to the lateral side, which I term the "reversed Chaddock method," is equally sensitive to demonstrate pyramidal tract involvement. With the "reversed Chaddock method", the receptive field of the Chaddock reflex may be postulated to be in the territory of the sural nerve, which could be supported by the better response obtained on stimulation of the postero-lateral calf than the anterior shin. With regard to the receptive fields of the Babinski and Chaddock reflexes, the first sacral dermatome (S1) is also considered a reflexogenous zone, but since the dermatome shows marked overlapping, the zones vary among individuals. As upgoing toe responses are consistently observed in

  1. Rapid and Sensitive Reverse-phase High-performance Liquid Chromatography Method for Estimation of Ketorolac in Pharmaceuticals Using Weighted Regression

    PubMed Central

    Dubey, S. K.; Duddelly, S.; Jangala, H.; Saha, R. N.

    2013-01-01

    A reliable, rapid and sensitive isocratic reverse phase high-performance liquid chromatography method has been developed and validated for assay of ketorolac tromethamine in tablets and ophthalmic dosage forms using diclofenac sodium as an internal standard. An isocratic separation of ketorolac tromethamine was achieved on Oyster BDS (150×4.6 mm i.d., 5 μm particle size) column using mobile phase of methanol:acetonitrile:sodium dihydrogen phosphate (20 mM; pH 5.5) (50:10:40, %v/v) at a flow rate of 1.0 ml/min. The eluents were monitored at 322 nm for ketorolac and at 282 nm for diclofenac sodium with a photodiode array detector. The retention times of ketorolac and diclofenac sodium were found to be 1.9 min and 4.6 min, respectively. Response was a linear function of drug concentration in the range of 0.01-15 μg/ml (R2=0.994; linear regression model using weighing factor 1/x2) with a limit of detection and quantification of 0.002 μg/ml and 0.007 μg/ml, respectively. The % recovery and % relative standard deviation values indicated the method was accurate and precise. PMID:23901166

  2. Synthesis of MSnO{sub 3} (M = Ba, Sr) nanoparticles by reverse micelle method and particle size distribution analysis by whole powder pattern modeling

    SciTech Connect

    Ahmed, Jahangeer; Blakely, Colin K.; Bruno, Shaun R.; Poltavets, Viktor V.

    2012-09-15

    Highlights: ► BaSnO{sub 3} and SrSnO{sub 3} nanoparticles synthesized using the reverse micelle method. ► Particle size and size distribution studied by whole powder pattern modeling. ► Nanoparticles are of optimal size for investigation in dye-sensitized solar cells. -- Abstract: Light-to-electricity conversion efficiency in dye-sensitized solar cells critically depends not only on the dye molecule, semiconducting material and redox shuttle selection but also on the particle size and particle size distribution of the semiconducting photoanode. In this study, nanocrystalline BaSnO{sub 3} and SrSnO{sub 3} particles have been synthesized using the microemulsion method. Particle size distribution was studied by whole powder pattern modeling which confirmed narrow particle size distribution with an average size of 18.4 ± 8.3 nm for SrSnO{sub 3} and 15.8 ± 4.2 nm for BaSnO{sub 3}. These values are in close agreement with results of transmission electron microscopy. The prepared materials have optimal microstructure for successive investigation in dye-sensitized solar cells.

  3. Monitoring seasonal variation of epicatechin and gallic acid in the bark of Saraca asoca using reverse phase high performance liquid chromatography (RP-HPLC) method

    PubMed Central

    Ketkar, Pushkar M.; Nayak, Shraddha U.; Pai, Sandeep R.; Joshi, Rajesh K.

    2015-01-01

    Background: Saraca asoca (Roxb.) Wilde (Fabaceae) is a high valued but vulnerable medicinal plant of Western Ghats region. This plant is mainly known for its use in various gynecological disorders. Objective: The objective of the present study was to investigate seasonal variation of the polyphenolic compounds viz., epicatechin and gallic acid in the bark of S. asoca by using Reverse Phase High Performance Liquid Chromatography-Diode Array Detector (RP-HPLC-DAD) method. Materials and Methods: The bark was collected in six different Ritu (season) viz. Varsha (monsoon), Sharad (autumn), hemant (early winter), Shishir (winter), Vasanta (spring), and Grishma (summer) mentioned in Ayurveda. Results: The RP-HPLC-DAD analysis indicated that levels of epicatechin and gallic acid in the bark of S. asoca vary seasonally. The highest concentration of epicatechin was observed in Shishir Ritu (3315.19 ± 165.76 mg/100g) and gallic acid during Hemant Ritu (211.90 ± 10.60 mg/100 g). Conclusions: In present study, the ability to synthesize and accumulate both the compounds in bark of S. asoca varied greatly throughout the seasons. It was also observed that the compound epicatechin was present abundantly as compared to gallic acid throughout the seasons. PMID:25878461

  4. Simultaneous determination of related substances of telmisartan and hydrochlorothiazide in tablet dosage form by using reversed phase high performance liquid chromatographic method

    PubMed Central

    Mukhopadhyay, Sutirtho; Kadam, Kiran; Sawant, Laxman; Nachane, Dhanashree; Pandita, Nancy

    2011-01-01

    Objective: Telmisartan is a potent, long-lasting, nonpeptide antagonist of the angiotensin II type-1 (AT1) receptor that is indicated for the treatment of essential hypertension. Hydrochlorothiazide is a widely prescribed diuretic and it is indicated for the treatment of edema, control of essential hypertension and management of diabetes insipidus. In the current article a new, accurate, sensitive, precise, rapid, reversed phase high performance liquid chromatography (RP-HPLC) method was developed for determination of related substances of Telmisartan and Hydrochlorthiazide in tablet dosage form. Materials and Methods: Simultaneous determination of related substances was performed on Kromasil C18 analytical column (250 × 4.6 mm; 5μm pertical size) column at 40°C employing a gradient elution. Mobile phase consisting of solvent A (solution containing 2.0 g of potassium dihydrogen phosphate anhydrous and 1.04 g of Sodium 1- Hexane sulphonic acid monohydrate per liter of water, adjusted to pH 3.0 with orthophosphoric acid) and solvent B (mixture of Acetonitrile: Methanol in the ratio 80:20 v/v) was used at a flow rate of 1.0 ml min–1. UV detection was performed at 270 nm. Results: During method validation parameter such as precision, linearity, accuracy, specificity, limit of detection and quantification were evaluated, which remained within acceptable limits. Conclusions: HPLC analytical method is linear, accurate, precise, robust and specific, being able to separate the main drug from its degradation products. It may find application for the routine analysis of the related substances of both Telmisartan and Hydrochlorthiazide in this combination tablets. PMID:21966158

  5. Genotyping of 27 human papillomavirus types by using L1 consensus PCR products by a single-hybridization, reverse line blot detection method.

    PubMed

    Gravitt, P E; Peyton, C L; Apple, R J; Wheeler, C M

    1998-10-01

    Amplification of human papillomavirus (HPV) DNA by L1 consensus primer systems (e.g., MY09/11 or GP5(+)/6(+)) can detect as few as 10 to 100 molecules of HPV targets from a genital sample. However, genotype determination by dot blot hybridization is laborious and requires at least 27 separate hybridizations for substantive HPV-type discrimination. A reverse blot method was developed which employs a biotin-labeled PCR product hybridized to an array of immobilized oligonucleotide probes. By the reverse blot strip analysis, genotype discrimination of multiple HPV types can be accomplished in a single hybridization and wash cycle. Twenty-seven HPV probe mixes, two control probe concentrations, and a single reference line were immobilized to 75- by 6-mm nylon strips. Each individual probe line contained a mixture of two bovine serum albumin-conjugated oligonucleotide probes specific to a unique HPV genotype. The genotype spectrum discriminated on this strip includes the high-risk, or cancer-associated, HPV genotypes 16, 18, 26, 31, 33, 35, 39, 45, 51, 52, 55, 56, 58, 59, 68 (ME180), MM4 (W13B), MM7 (P291), and MM9 (P238A) and the low-risk, or non-cancer-associated, genotypes 6, 11, 40, 42, 53, 54, 57, 66, and MM8 (P155). In addition, two concentrations of beta-globin probes allowed for assessment of individual specimen adequacy following amplification. We have evaluated the performance of the strip method relative to that of a previously reported dot blot format (H. M. Bauer et al., p. 132-152, in C. S. Herrington and J. O. D. McGee (ed.), Diagnostic Molecular Pathology: a Practical Approach, (1992), by testing 328 cervical swab samples collected in Digene specimen transport medium (Digene Diagnostics, Silver Spring, Md.). We show excellent agreement between the two detection formats, with 92% concordance for HPV positivity (kappa = 0.78, P < 0.001). Nearly all of the discrepant HPV-positive samples resulted from weak signals and can be attributed to sampling error from

  6. A method for assessment of the genotoxicity of mainstream cigarette-smoke by use of the bacterial reverse-mutation assay and an aerosol-based exposure system.

    PubMed

    Kilford, Joanne; Thorne, David; Payne, Rebecca; Dalrymple, Annette; Clements, Julie; Meredith, Clive; Dillon, Debbie

    2014-07-15

    To date there are no widely accepted methods for the toxicological testing of complex gaseous mixtures and aerosols, such as cigarette smoke, although some modifications to the standard regulatory methods have been developed and used. Historically, routine testing of cigarettes has primarily focused on the particulate fraction of cigarette smoke. However, this fraction may not accurately reflect the full toxicity and mutagenicity of the smoke aerosol as a whole, which contains semi-volatiles and short-lived products of combustion. In this study we have used a modified version of the bacterial reverse-mutation (Ames) assay for the testing of mainstream smoke generated from 3R4F reference cigarettes with a Vitrocell(®) VC 10 exposure system. This method has been evaluated in four strains of Salmonella typhimurium (TA98, TA100, YG1024 and YG1042) and one strain of Escherichia coli (WP2 uvrA pKM101) in the absence and presence of a metabolic activation system. Following exposure at four concentrations of diluted mainstream cigarette-smoke, concentration-related and reproducible increases in the number of revertants were observed in all four Salmonella strains. E. coli strain WP2 uvrA pKM101 was unresponsive at the four concentrations tested. To quantify the exposure dose and to enable biological response to be plotted as a function of deposited mass, quartz-crystal microbalances were included in situ in the smoke-exposure set-up. This methodology was further assessed by comparing the responses of strain YG1042 to mainstream cigarette-smoke on a second VC 10 Smoking Robot. In summary, the Ames assay can be successfully modified to assess the toxicological impact of mainstream cigarette-smoke. PMID:25344108

  7. Development and validation of a reversed-phase HPLC method for CYP1A2 phenotyping by use of a caffeine metabolite ratio in saliva.

    PubMed

    Begas, Elias; Kouvaras, Evangelos; Tsakalof, Andreas K; Bounitsi, Maria; Asprodini, Eftihia Konstadinos

    2015-11-01

    CYP1A2 is important for metabolizing various clinically used drugs. Phenotyping of CYP1A2 may prove helpful for drug individualization therapy. Several HPLC methods have been developed for quantification of caffeine metabolites in plasma and urine. Aim of the present study was to develop a valid and simple HPLC method for evaluating CYP1A2 activity during exposure in xenobiotics by the use of human saliva. Caffeine and paraxanthine were isolated from saliva by liquid-liquid extraction (chlorophorm/isopropanol 85/15v/v). Extracts were analyzed by reversed-phase HPLC on a C18 column with mobile phase 0.1% acetic acid/methanol/acetonitrile (80/20/2 v/v) and detected at 273nm. Caffeine and paraxanthine elution times were <13min with no interferences from impurities or caffeine metabolites. Detector response was linear (0.10-8.00µg/ml, R(2) >0.99), recovery was >93% and bias <4.47%. Intra- and inter-day precision was <5.14% (n=6). The limit of quantitation was 0.10µg/ml and the limit of detection was 0.018±0.002µg/mL for paraxanthine and 0.032±0.002µg/ml for caffeine. Paraxanthine/caffeine ratio of 34 healthy volunteers was significantly higher in smokers (p<0.001). Saliva paraxanthine/caffeine ratios and urine metabolite ratios were highly correlated (r=0.85, p<0.001). The method can be used for the monitoring of CYP1A2 activity in clinical practice and in studies relevant to exposure to environmental and pharmacological xenobiotics. PMID:25891161

  8. Development and validation of a stability-indicating reverse phase ultra performance liquid chromatographic method for the estimation of nebivolol impurities in active pharmaceutical ingredients and pharmaceutical formulation.

    PubMed

    Thummala, Veera Raghava Raju; Lanka, Mohana Krishna

    2015-10-01

    A sensitive, stability-indicating gradient reverse phase ultra performance liquid chromatographic method has been developed for the quantitative estimation of nebivolol impurities in active pharmaceutical ingredient (API) and pharmaceutical formulation. Efficient chromatographic separation was achieved on an Acquity BEH C18 column (100 mm x 2.1 mm, 1.7 μm) with mobile phase of a gradient mixture. The flow rate of the mobile phase was 0.18 mL/min with column temperature of 30 degrees C and detection wavelength of 281 nm. The relative response factor values of (R*)-2-( benzylamino)-1-((S*)-6-fluorochroman-2-yl) ethanol ((R x S*) NBV-), (R)-1-((R)-6-fluorochroman-2-yl)-2-((S)-2-((S)-6-fluoro-chroman-2-yl)-2-hydroxyethyl-amino) ethanol ((RRSS) NBV-3), 1-(chroman-2-yl)-2-(2-(6-fluorochroman-2-yl)-2-hydroxyethyl amino) ethanol (monodesfluoro impurity), (S)-1-((R)-6-fluorochroman-2-yl)-2-((R)-2 (S*)-6-fluoro-chroman-2-yl)-2-hydroxyethylamino) ethanol hydrochloride ((RSRS) NBV-3) and (R*)-1-((S*)-6-fluorochroman-2-yl)-2-((S*)-2-((S*)-6-fluoro-chroman-2-yl)-2-hydroxyethylamino) ethanol ((R* S* S* S*) NBV-2) were 0.65, 0.91, 0.68, 0.92 and 0.91 respectively. Nebivolol formulation sample was subjected to the stress conditions of acid, base, oxidative, hydrolytic, thermal, humidity and photolytic degradation. Nebivolol was found to degrade significantly under peroxide stress condition. The degradation products were well resolved from nebivolol and its impurities. The peak purity test results confirmed that the nebivolol peak was homogenous and pure in all stress samples and the mass balance was found to be more than 98%, thus proving the stability-indicating power of the method. The developed method was validated according to International Conference on Hormonization (ICH) guidelines with respect to specificity, linearity, limits of detection and quantification, accuracy, precision and robustness. PMID:26930962

  9. A reversed-phase ion-pair high-performance liquid chromatography method for bovine testicular hyaluronidase digests using postcolumn derivatization with 2-cyanoacetamide and ultraviolet detection.

    PubMed

    Cramer, J A; Bailey, L C

    1991-07-01

    A reversed-phase ion-pair HPLC method for separating hyaluronic acid oligomers, using a polymeric C18 column at alkaline pH, is described. As the concentration of the ion-pairing agent tetrabutylammonium hydroxide increased, over the range of 0.01 to 0.06M, the capacity factors (k') of tetra- to dodecasaccharide decreased. The change in k', for each increment in pairing agent, increased with oligomer molecular weight. When changing mobile phase pH from 7 to 8, k' dramatically decreased and remained unchanged from pH 8 to 11. The isocratic separation was optimized to resolve tetrato dodecasaccharide at pH 9.0 in under 19 min. The postcolumn derivatizing agent 2-cyanoacetamide reacted with the reducing N-acetylglucosamine end groups of hyaluronic acid oligomers to yield reaction products that were monitored at 27 nm. In a series of control experiments using decasaccharide and N-acetylglucosamine, it was found that maximum product formation took place at pH 9 and was greatly influenced by borate buffer concentration. The optimum concentration for 2-cyanoacetamide was 0.33% and a temperature of 100 degrees C gave the best signal to noise ratio for the postcolumn reaction. The method is linear and reproducible, and has a lower limit of detection for tetrasaccharide of 20 ng (25 pmol). This system is suitable for studying the degradation kinetics of purified hyaluronic acid oligomers by bovine testicular hyaluronidase. Extension of the method to fluorescent and electrochemical detection and its applicability to other glycosaminoglycans is discussed. PMID:1888031

  10. Solid-liquid work of adhesion of coarse-grained models of n-hexane on graphene layers derived from the conditional reversible work method

    SciTech Connect

    Ardham, Vikram Reddy; Leroy, Frédéric E-mail: f.leroy@theo.chemie.tu-darmstadt.de; Deichmann, Gregor; Vegt, Nico F. A. van der E-mail: f.leroy@theo.chemie.tu-darmstadt.de

    2015-12-28

    We address the question of how reducing the number of degrees of freedom modifies the interfacial thermodynamic properties of heterogeneous solid-liquid systems. We consider the example of n-hexane interacting with multi-layer graphene which we model both with fully atomistic and coarse-grained (CG) models. The CG models are obtained by means of the conditional reversible work (CRW) method. The interfacial thermodynamics of these models is characterized by the solid-liquid work of adhesion W{sub SL} calculated by means of the dry-surface methodology through molecular dynamics simulations. We find that the CRW potentials lead to values of W{sub SL} that are larger than the atomistic ones. Clear understanding of the relationship between the structure of n-hexane in the vicinity of the surface and W{sub SL} is elucidated through a detailed study of the energy and entropy components of W{sub SL}. We highlight the crucial role played by the solid-liquid energy fluctuations. Our approach suggests that CG potentials should be designed in such a way that they preserve the range of solid-liquid interaction energies, but also their fluctuations in order to preserve the reference atomistic value of W{sub SL}. Our study thus opens perspectives into deriving CG interaction potentials that preserve the thermodynamics of solid-liquid contacts and will find application in studies that intend to address materials driven by interfaces.

  11. Advanced analytical methods for the structure elucidation of polystyrene-b-poly(n-butyl acrylate) block copolymers prepared by reverse iodine transfer polymerisation.

    PubMed

    Wright, Trevor Gavin; Pfukwa, Helen; Pasch, Harald

    2015-09-10

    Reverse iodine transfer polymerisation (RITP) is a living radical polymerisation technique that has shown to be feasible in synthesising segmented styrene-acrylate copolymers. Polymers synthesised via RITP are typically only described regarding their bulk properties using nuclear magnetic resonance spectroscopy and size exclusion chromatography. To fully understand the complex composition of the polymerisation products and the RITP reaction mechanism, however, it is necessary to use a combination of advanced analytical methods. In the present RITP procedure, polystyrene was synthesised first and then used as a macroinitiator to synthesise polystyrene-block-poly(n-butyl acrylate) (PS-b-PBA) block copolymers. For the first time, these PS-b-PBA block copolymers were analysed by a combination of SEC, in situ(1)H NMR and HPLC. (1)H NMR was used to determine the copolymer composition and the end group functionality of the samples, while SEC and HPLC were used to confirm the formation of block copolymers. Detailed information on the living character of the RITP process was obtained. PMID:26388490

  12. Design of a fully-fiber multi-chord interferometer and a new phase-shift demodulation method for field-reversed configuration

    SciTech Connect

    Fang, Dongfan Sun, Qizhi; Zhao, Xiaoming; Jia, Yuesong

    2014-05-15

    A 633 nm laser interferometer has been designed based on a novel concept, which, without the acousto-optic modulator or the demodulator circuit, adopts the fibers to connect all elements except photodetectors and oscilloscope in this system to make it more compact, portable, and efficient. The noteworthy feature is to mathematically compare the two divided interference signals, which have the same phase-shift caused by the electron density but possess the different initial phase and low angular frequencies. It is possible to read the plasma density directly on the oscilloscope by our original mathematic demodulation method without a camera. Based on the Abel inversion algorithm, the radial electron density profiles versus time can be obtained by using the multi-chord system. The designed measurable phase shift ranges from 0 to 2π rad corresponding to the maximum line integral of electron density less than 3.5 × 10{sup 17} cm{sup −2}, and the phase accuracy is about 0.017 rad corresponding to the line integral of electron density accuracy of 1 × 10{sup 15} cm{sup −2}. After the construction of eight-chord interferometer, it will provide the detailed time resolved information of the spatial distribution of the electron density in the field-reversed configuration (FRC) plasma target produced by the “Yingguang-1” programmed-discharge device, which is being constructed in the Key Laboratory of Pulsed Power, China Academy of Engineering Physics.

  13. A method for simultaneous detection and identification of Brazilian dog- and vampire bat-related rabies virus by reverse transcription loop-mediated isothermal amplification assay.

    PubMed

    Saitou, Yasumasa; Kobayashi, Yuki; Hirano, Shinji; Mochizuki, Nobuyuki; Itou, Takuya; Ito, Fumio H; Sakai, Takeo

    2010-09-01

    At present, the sporadic occurrence of human rabies in Brazil can be attributed primarily to dog- and vampire bat-related rabies viruses. Reverse transcription loop-mediated isothermal amplification (RT-LAMP) was employed as a simultaneous detection method for both rabies field variants within 60 min. Vampire bat-related rabies viruses could be distinguished from dog variants by digesting amplicons of the RT-LAMP reaction using the restriction enzyme AlwI. Amplification and digestion could both be completed within 120 min after RNA extraction. In addition, the RT-LAMP assay also detected rabies virus in isolates from Brazilian frugivorous bats and Ugandan dog, bovine and goat samples. In contrast, there were false negative results from several Brazilian insectivorous bats and all of Chinese dog, pig, and bovine samples using the RT-LAMP assay. This study showed that the RT-LAMP assay is effective for the rapid detection of rabies virus isolates from the primary reservoir in Brazil. Further improvements are necessary so that the RT-LAMP assay can be employed for the universal detection of genetic variants of rabies virus in the field. PMID:20403387

  14. Rapid genome detection of Schmallenberg virus and bovine viral diarrhea virus by use of isothermal amplification methods and high-speed real-time reverse transcriptase PCR.

    PubMed

    Aebischer, Andrea; Wernike, Kerstin; Hoffmann, Bernd; Beer, Martin

    2014-06-01

    Over the past few years, there has been an increasing demand for rapid and simple diagnostic tools that can be applied outside centralized laboratories by using transportable devices. In veterinary medicine, such mobile test systems would circumvent barriers associated with the transportation of samples and significantly reduce the time to diagnose important infectious animal diseases. Among a wide range of available technologies, high-speed real-time reverse transcriptase quantitative PCR (RT-qPCR) and the two isothermal amplification techniques loop-mediated isothermal amplification (LAMP) and recombinase polymerase amplification (RPA) represent three promising candidates for integration into mobile pen-side tests. The aim of this study was to investigate the performance of these amplification strategies and to evaluate their suitability for field application. In order to enable a valid comparison, novel pathogen-specific assays have been developed for the detection of Schmallenberg virus and bovine viral diarrhea virus. The newly developed assays were evaluated in comparison with established standard RT-qPCR using samples from experimentally or field-infected animals. Even though all assays allowed detection of the target virus in less than 30 min, major differences were revealed concerning sensitivity, specificity, robustness, testing time, and complexity of assay design. These findings indicated that the success of an assay will depend on the integrated amplification technology. Therefore, the application-specific pros and cons of each method that were identified during this study provide very valuable insights for future development and optimization of pen-side tests. PMID:24648561

  15. Optimization and validation of a reversed-phase high performance liquid chromatography method for the measurement of bovine liver methylmalonyl-coenzyme a mutase activity

    PubMed Central

    2013-01-01

    Background Methylmalonyl-CoA mutase (MCM) is an adenosylcobalamin-dependent enzyme that catalyses the interconversion of (2R)-methylmalonyl-CoA to succinyl-CoA. In humans, a deficit in activity of MCM, due to an impairment of intracellular formation of adenosylcobalamin and methylcobalamin results in a wide spectrum of clinical manifestations ranging from moderate to fatal. Consequently, MCM is the subject of abundant literature. However, there is a lack of consensus on the reliable method to monitor its activity. This metabolic pathway is highly solicited in ruminants because it is essential for the utilization of propionate formed during ruminal fermentation. In lactating dairy cows, propionate is the major substrate for glucose formation. In present study, a reversed-phase high performance liquid chromatography (RP-HPLC) was optimized and validated to evaluate MCM activity in bovine liver. The major aim of the study was to describe the conditions to optimize reproducibility of the method and to determine stability of the enzyme and its product during storage and processing of samples. Results Specificity of the method was good, as there was no interfering peak from liver extract at the retention times corresponding to methylmalonyl-CoA or succinyl-CoA. Repeatability of the method was improved as compared to previous RP-HPLC published data. Using 66 μg of protein, intra-assay coefficient of variation (CV) of specific activities, ranged from 0.90 to 8.05% and the CV inter-day was 7.40%. Storage and processing conditions (frozen homogenate of fresh tissue vs. fresh homogenate of tissue snapped in liquid nitrogen) did not alter the enzyme activity. The analyte was also stable in liver crude extract for three frozen/thawed cycles when stored at -20°C and thawed to room temperature. Conclusions The improved method provides a way for studying the effects of stages of lactation, diet composition, and physiology in cattle on MCM activity over long periods of time

  16. Development of an analytical method using reversed-phase HPLC-PDA for a semipurified extract of Paullinia cupana var. sorbilis (guaraná).

    PubMed

    Klein, Traudi; Longhini, Renata; de Mello, João Carlos Palazzo

    2012-01-15

    The Neotropical plant 'guaraná' has been widely used in medicine, cosmetics, and industry because of its versatile biological activities. These effects are mainly attributed to the presence of polyphenols. An efficient, precise, and reliable method was developed for quantification of the polyphenols catechin and epicatechin in guaraná extract solution, using HPLC-PDA detection. The ideal conditions for the analysis of a semipurified extract of guaraná (EPA), using solutions of 0.05% TFA-water (phase A) and 0.05% TFA in acetonitrile:methanol (75:25, vv(-1)) (phase B) as mobile phases were established. Gradient reversed-phase chromatography was performed using a guard cartridge (C18, 4.6mm×20mm, 4μm) and column (C18, 250mm×4.6mm, 4μm), flow of 0.5mLmin(-1) and detection at 280nm. The main validation parameters of the method were also determined. The method was linear over a range of 18.75-300μgmL(-1) for catechin and epicatechin, with detection limits of 0.70 and 0.88μgmL(-1) and quantification limits of 2.13 and 2.67μgmL(-1), respectively. The method also showed consistent mean recoveries of 91.3±3.8%, 2.14 RSD and 93.4±3.1, 2.74 RSD of catechin and epicatechin respectively. The relative standard deviations were relatively low: intra-day (0.72% and 0.66% for catechin and epicatechin, respectively) and inter-day (0.93% and 0.75% for catechin and epicatechin, respectively). The semipurified extract showed catechin, epicatechin, and caffeine contents of 180.75, 278.87, and 300.87μgmg(-1), respectively. The results demonstrated the efficiency, precision, accuracy, and robustness of the proposed method. The solutions remained stable for a sufficient time (one week) to complete the analytical process. PMID:22265533

  17. Evaluation of the BioPlex 2200 Syphilis System as a First-Line Method of Reverse-Sequence Screening for Syphilis Diagnosis

    PubMed Central

    Nardini, Paola; Foschi, Claudio; Moroni, Alessandra; D'Antuono, Antonietta; Bacchi Reggiani, Letizia; Cevenini, Roberto

    2013-01-01

    Despite recent technological advances, the diagnosis of syphilis remains a challenging enterprise. Actually, most high-volume laboratories have adopted the “reverse algorithm” due several factors, including the potential to automate testing. Recently, immunoassays processed on random-access systems have been proposed as screening tests. The purpose of this study was to evaluate diagnostic performances of BioPlex 2200 Syphilis IgG and BioPlex 2200 Syphilis IgM, tests based on Multiplex Flow technology, in comparison with the performance of Architect Syphilis TP, a chemiluminescent immunoassay for the detection of IgG and/or IgM anti-Treponema pallidum antibodies. A retrospective study was performed with a panel of 100 blood donor sera, a panel of 350 clinical and laboratory-characterized syphilitic sera, and 170 samples obtained from subjects with potentially interfering conditions. Moreover, 200 unselected samples submitted to the Microbiology Laboratory of St. Orsola Hospital in Bologna for routine screening for syphilis were evaluated. As confirmatory tests, T. pallidum hemagglutination and Western blot assays were used. Considering the IgG Western blot (WB) assay to be the gold standard method, BioPlex 2200 Syphilis IgG specificity was far higher than Architect Syphilis TP specificity (89.7% versus 78.4%, respectively), whereas the sensitivity was 100% for both automated methods. Compared to the IgM WB assay, BioPlex 2200 Syphilis IgM performed with a specificity of 94.9%, whereas the sensitivity was 84.8%. Considering the excellent ease of use and automation, the high sample throughput and its valuable analytical performances, BioPlex Syphilis 2200 IgG could represent a suitable choice for high-volume laboratories. BioPlex Syphilis 2200 IgM could be considered a good addition to IgG testing for uncovering active infections. PMID:23697575

  18. A new back-and-forth iterative method for time-reversed convection modeling: Implications for the Cenozoic evolution of 3-D structure and dynamics of the mantle

    NASA Astrophysics Data System (ADS)

    Glišović, Petar; Forte, Alessandro M.

    2016-06-01

    The 3-D distribution of buoyancy in the convecting mantle drives a suite of convection-related manifestations. Although seismic tomography is providing increasingly resolved images of the present-day mantle heterogeneity, the distribution of mantle density variations in the geological past is unknown, and, by implication, this is true for the convection-related observables. The one major exception is tectonic plate motions, since geologic data are available to estimate their history and they currently provide the only available constraints on the evolution of 3-D mantle buoyancy in the past. We developed a new back-and-forth iterative method for time-reversed convection modeling with a procedure for matching plate velocity data at different instants in the past. The crucial aspect of this reconstruction methodology is to ensure that at all times plates are driven by buoyancy forces in the mantle and not vice versa. Employing tomography-based retrodictions over the Cenozoic, we estimate the global amplitude of the following observables: dynamic surface topography, the core-mantle boundary ellipticity, the free-air gravity anomalies, and the global divergence rates of tectonic plates. One of the major benefits of the new data assimilation method is the stable recovery of much shorter wavelength changes in heterogeneity than was possible in our previous work. We now resolve what appears to be two-stage subduction of the Farallon plate under the western U.S. and a deeply rooted East African Plume that is active under the Ethiopian volcanic fields during the Early Eocene.

  19. Supercritical fluid reverse micelle separation

    DOEpatents

    Fulton, John L.; Smith, Richard D.

    1993-01-01

    A method of separating solute material from a polar fluid in a first polar fluid phase is provided. The method comprises combining a polar fluid, a second fluid that is a gas at standard temperature and pressure and has a critical density, and a surfactant. The solute material is dissolved in the polar fluid to define the first polar fluid phase. The combined polar and second fluids, surfactant, and solute material dissolved in the polar fluid is maintained under near critical or supercritical temperature and pressure conditions such that the density of the second fluid exceeds the critical density thereof. In this way, a reverse micelle system defining a reverse micelle solvent is formed which comprises a continuous phase in the second fluid and a plurality of reverse micelles dispersed in the continuous phase. The solute material is dissolved in the polar fluid and is in chemical equilibrium with the reverse micelles. The first polar fluid phase and the continuous phase are immiscible. The reverse micelles each comprise a dynamic aggregate of surfactant molecules surrounding a core of the polar fluid. The reverse micelle solvent has a polar fluid-to-surfactant molar ratio W, which can vary over a range having a maximum ratio W.sub.o that determines the maximum size of the reverse micelles. The maximum ratio W.sub.o of the reverse micelle solvent is then varied, and the solute material from the first polar fluid phase is transported into the reverse micelles in the continuous phase at an extraction efficiency determined by the critical or supercritical conditions.

  20. Supercritical fluid reverse micelle separation

    DOEpatents

    Fulton, J.L.; Smith, R.D.

    1993-11-30

    A method of separating solute material from a polar fluid in a first polar fluid phase is provided. The method comprises combining a polar fluid, a second fluid that is a gas at standard temperature and pressure and has a critical density, and a surfactant. The solute material is dissolved in the polar fluid to define the first polar fluid phase. The combined polar and second fluids, surfactant, and solute material dissolved in the polar fluid is maintained under near critical or supercritical temperature and pressure conditions such that the density of the second fluid exceeds the critical density thereof. In this way, a reverse micelle system defining a reverse micelle solvent is formed which comprises a continuous phase in the second fluid and a plurality of reverse micelles dispersed in the continuous phase. The solute material is dissolved in the polar fluid and is in chemical equilibrium with the reverse micelles. The first polar fluid phase and the continuous phase are immiscible. The reverse micelles each comprise a dynamic aggregate of surfactant molecules surrounding a core of the polar fluid. The reverse micelle solvent has a polar fluid-to-surfactant molar ratio W, which can vary over a range having a maximum ratio W[sub o] that determines the maximum size of the reverse micelles. The maximum ratio W[sub o] of the reverse micelle solvent is then varied, and the solute material from the first polar fluid phase is transported into the reverse micelles in the continuous phase at an extraction efficiency determined by the critical or supercritical conditions. 27 figures.

  1. Reversible DNA compaction.

    PubMed

    González-Pérez, Alfredo

    2014-01-01

    In this review we summarize and discuss the different methods we can use to achieve reversible DNA compaction in vitro. Reversible DNA compaction is a natural process that occurs in living cells and viruses. As a result these process long sequences of DNA can be concentrated in a small volume (compacted) to be decompacted only when the information carried by the DNA is needed. In the current work we review the main artificial compacting agents looking at their suitability for decompaction. The different approaches used for decompaction are strongly influenced by the nature of the compacting agent that determines the mechanism of compaction. We focus our discussion on two main artificial compacting agents: multivalent cations and cationic surfactants that are the best known compacting agents. The reversibility of the process can be achieved by adding chemicals like divalent cations, alcohols, anionic surfactants, cyclodextrins or by changing the chemical nature of the compacting agents via pH modifications, light induced conformation changes or by redox-reactions. We stress the relevance of electrostatic interactions and self-assembly as a main approach in order to tune up the DNA conformation in order to create an on-off switch allowing a transition between coil and compact states. The recent advances to control DNA conformation in vitro, by means of molecular self-assembly, result in a better understanding of the fundamental aspects involved in the DNA behavior in vivo and serve of invaluable inspiration for the development of potential biomedical applications. PMID:24444152

  2. Real time reverse transcription (RRT)-polymerase chain reaction (PCR) methods for detection of pandemic (H1N1) 2009 influenza virus and European swine influenza A virus infections in pigs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    BACKGROUND. Requirement to detect pandemic (H1N1) 2009 (H1N1v) and established swine influenza A viruses (SIVs) by RealTime real time reverse transcription (RRT) PCR methods. Objectives. First, modify an existing M gene RRT PCR for sensitive generic detection of H1N1v and other European SIVs. S...

  3. Reversible brazing process

    DOEpatents

    Pierce, Jim D.; Stephens, John J.; Walker, Charles A.

    1999-01-01

    A method of reversibly brazing surfaces together. An interface is affixed to each surface. The interfaces can be affixed by processes such as mechanical joining, welding, or brazing. The two interfaces are then brazed together using a brazing process that does not defeat the surface to interface joint. Interfaces of materials such as Ni-200 can be affixed to metallic surfaces by welding or by brazing with a first braze alloy. The Ni-200 interfaces can then be brazed together using a second braze alloy. The second braze alloy can be chosen so that it minimally alters the properties of the interfaces to allow multiple braze, heat and disassemble, rebraze cycles.

  4. Design and Assessment of a Real Time Reverse Transcription-PCR Method to Genotype Single-Stranded RNA Male-Specific Coliphages (Family Leviviridae).

    EPA Science Inventory

    A real-time, reverse transcription-PCR (RT-qPCR) assay was developed to differentiate the four genogroups of male-specific ssRNA coliphages (FRNA) (family Leviviridae). As FRNA display a trend of source-specificity (human sewage or animal waste) at the genogroup level, this assa...

  5. Reverse Correlation in Neurophysiology

    ERIC Educational Resources Information Center

    Ringach, Dario; Shapley, Robert

    2004-01-01

    This article presents a review of reverse correlation in neurophysiology. We discuss the basis of reverse correlation in linear transducers and in spiking neurons. The application of reverse correlation to measure the receptive fields of visual neurons using white noise and m-sequences, and classical findings about spatial and color processing in…

  6. Quantum Operation Time Reversal

    SciTech Connect

    Crooks, Gavin E.

    2008-03-25

    The dynamics of an open quantum system can be described by a quantum operation: A linear, complete positive map of operators. Here, I exhibit a compact expression for the time reversal of a quantum operation, which is closely analogous to the time reversal of a classical Markov transition matrix. Since open quantum dynamics are stochastic, and not, in general, deterministic, the time reversal is not, in general, an inversion of the dynamics. Rather, the system relaxes toward equilibrium in both the forward and reverse time directions. The probability of a quantum trajectory and the conjugate, time reversed trajectory are related by the heat exchanged with the environment.

  7. Stagnation point reverse flow combustor

    NASA Technical Reports Server (NTRS)

    Zinn, Ben T. (Inventor); Neumeier, Yedidia (Inventor); Seitzman, Jerry M. (Inventor); Jagoda, Jechiel (Inventor); Weksler, Yoav (Inventor)

    2008-01-01

    A method for combusting a combustible fuel includes providing a vessel having an opening near a proximate end and a closed distal end defining a combustion chamber. A combustible reactants mixture is presented into the combustion chamber. The combustible reactants mixture is ignited creating a flame and combustion products. The closed end of the combustion chamber is utilized for directing combustion products toward the opening of the combustion chamber creating a reverse flow of combustion products within the combustion chamber. The reverse flow of combustion products is intermixed with combustible reactants mixture to maintain the flame.

  8. A reversible molecular valve

    PubMed Central

    Nguyen, Thoi D.; Tseng, Hsian-Rong; Celestre, Paul C.; Flood, Amar H.; Liu, Yi; Stoddart, J. Fraser; Zink, Jeffrey I.

    2005-01-01

    In everyday life, a macroscopic valve is a device with a movable control element that regulates the flow of gases or liquids by blocking and opening passageways. Construction of such a device on the nanoscale level requires (i) suitably proportioned movable control elements, (ii) a method for operating them on demand, and (iii) appropriately sized passageways. These three conditions can be fulfilled by attaching organic, mechanically interlocked, linear motor molecules that can be operated under chemical, electrical, or optical stimuli to stable inorganic porous frameworks (i.e., by self-assembling organic machinery on top of an inorganic chassis). In this article, we demonstrate a reversibly operating nanovalve that can be turned on and off by redox chemistry. It traps and releases molecules from a maze of nanoscopic passageways in silica by controlling the operation of redox-activated bistable [2]rotaxane molecules tethered to the openings of nanopores leading out of a nanoscale reservoir. PMID:16006520

  9. Reverse photoacoustic standoff spectroscopy

    DOEpatents

    Van Neste, Charles W.; Senesac, Lawrence R.; Thundat, Thomas G.

    2011-04-12

    A system and method are disclosed for generating a reversed photoacoustic spectrum at a greater distance. A source may emit a beam to a target and a detector measures signals generated as a result of the beam being emitted on the target. By emitting a chopped/pulsed light beam to the target, it may be possible to determine the target's optical absorbance by monitoring the intensity of light collected at the detector at different wavelengths. As the wavelength of light is changed, the target may absorb or reject each optical frequency. Rejection may increase the intensity at the sensing element and absorption may decrease the intensity. Accordingly, an identifying spectrum of the target may be made with the intensity variation of the detector as a function of illuminating wavelength.

  10. Ice ages and geomagnetic reversals

    NASA Technical Reports Server (NTRS)

    Wu, Patrick

    1992-01-01

    There have been speculations on the relationship between climatic cooling and polarity reversals of the earth's magnetic field during the Pleistocene. Two of the common criticisms on this relationship have been the reality of these short duration geomagnetic events and the accuracy of their dates. Champion et al. (1988) have reviewed recent progress in this area. They identified a total of 10 short-duration polarity events in the last 1 Ma and 6 of these events have been found in volcanic rocks, which also have K-Ar dates. Supposing that the speculated relationship between climatic cooling and geomagnetic reversals actually exist, two mechanisms that assume climatic cooling causes short period magnetic reversals will be investigated. These two methods are core-mantle boundary topography and transfer of the rotational energy to the core.

  11. Vasectomy reversal: a clinical update.

    PubMed

    Patel, Abhishek P; Smith, Ryan P

    2016-01-01

    Vasectomy is a safe and effective method of contraception used by 42-60 million men worldwide. Approximately 3%-6% of men opt for a vasectomy reversal due to the death of a child or divorce and remarriage, change in financial situation, desire for more children within the same marriage, or to alleviate the dreaded postvasectomy pain syndrome. Unlike vasectomy, vasectomy reversal is a much more technically challenging procedure that is performed only by a minority of urologists and places a larger financial strain on the patient since it is usually not covered by insurance. Interest in this procedure has increased since the operating microscope became available in the 1970s, which consequently led to improved patency and pregnancy rates following the procedure. In this clinical update, we discuss patient evaluation, variables that may influence reversal success rates, factors to consider in choosing to perform vasovasostomy versus vasoepididymostomy, and the usefulness of vasectomy reversal to alleviate postvasectomy pain syndrome. We also review the use of robotics for vasectomy reversal and other novel techniques and instrumentation that have emerged in recent years to aid in the success of this surgery. PMID:26975488

  12. Vasectomy reversal: a clinical update

    PubMed Central

    Patel, Abhishek P; Smith, Ryan P

    2016-01-01

    Vasectomy is a safe and effective method of contraception used by 42–60 million men worldwide. Approximately 3%–6% of men opt for a vasectomy reversal due to the death of a child or divorce and remarriage, change in financial situation, desire for more children within the same marriage, or to alleviate the dreaded postvasectomy pain syndrome. Unlike vasectomy, vasectomy reversal is a much more technically challenging procedure that is performed only by a minority of urologists and places a larger financial strain on the patient since it is usually not covered by insurance. Interest in this procedure has increased since the operating microscope became available in the 1970s, which consequently led to improved patency and pregnancy rates following the procedure. In this clinical update, we discuss patient evaluation, variables that may influence reversal success rates, factors to consider in choosing to perform vasovasostomy versus vasoepididymostomy, and the usefulness of vasectomy reversal to alleviate postvasectomy pain syndrome. We also review the use of robotics for vasectomy reversal and other novel techniques and instrumentation that have emerged in recent years to aid in the success of this surgery. PMID:26975488

  13. Object discrimination reversal as a method to assess cognitive impairment in nonhuman primate enhanced pre- and postnatal developmental (ePPND) studies: statistical power analysis.

    PubMed

    Cappon, Gregg D; Bowman, Christopher J; Hurtt, Mark E; Grantham, Lonnie E

    2012-10-01

    An important aspect of the enhanced pre- and postnatal developmental (ePPND) toxicity study in nonhuman primates (NHP) is that it combines in utero and postnatal assessments in a single study. However, it is unclear if NHP ePPND studies are suitable to perform all of the evaluations incorporated into rodent PPND studies. To understand the value of including cognitive assessment in a NHP ePPND toxicity study, we performed a power analysis of object discrimination reversal task data using a modified Wisconsin General Testing Apparatus (ODR-WGTA) from two NHP ePPND studies. ODR-WGTA endpoints evaluated were days to learning and to first reversal, and number of reversals. With α = 0.05 and a one-sided t-test, a sample of seven provided 80% power to predict a 100% increase in all three of the ODR-WGTA endpoints; a sample of 25 provided 80% power to predict a 50% increase. Similar power analyses were performed with data from the Cincinnati Water Maze (CWM) and passive avoidance tests from three rat PPND toxicity studies. Groups of 5 and 15 in the CWM and passive avoidance test, respectively, provided 80% power to detect a 100% change. While the power of the CWM is not far superior to the NHP ODR-WGTA, a clear advantage is the routine use of larger sample size, with a group of 20 rats the CWM provides ~90% power to detect a 50% change. Due to the limitations on the number of animals, the ODR-WGTA may not be suitable for assessing cognitive impairment in NHP ePPND studies. PMID:22930561

  14. Surface properties, textural features and catalytic performance for NO + CO abatement of spinels MAl 2O 4 (M = Mg, Co and Zn) developed by reverse and bicontinuous microemulsion method

    NASA Astrophysics Data System (ADS)

    Giannakas, A. E.; Ladavos, A. K.; Armatas, G. S.; Pomonis, P. J.

    2007-06-01

    Three typical spinels of general formula MAl 2O 4 (M = Mg, Co and Zn) have been successfully prepared via a microemulsion method both in the reverse and bicontinuous state. The final solids were characterized by X-ray diffraction followed by Rietveld analysis, N 2 adsorption-desorption porosimetry and SEM. Pore connectivity ( c) was also calculated with Seaton's method. The analysis of all these properties shown that spinels prepared via reverse microemulsion route have better surface and textural properties than bicontinuous ones. The spinels were tested for NO + CO reaction and reverse spinels shown better catalytic activity than bicontinuous ones while the full sequence of catalytic activity is: ZnAl 2O 4-r > ZnAl 2O 4-b > MgAl 2O 4-r > MgAl 2O 4-b > CoAl 2O 4-r > CoAl 2O 4-b. The Rietveld analysis helped us to give an explanation about the catalytic activity and shown that the configuration of inverse spinel phase is the critical factor for the catalytic behavior of final solids. The reactants NO and CO react in a 2:1 ratio at low temperature but they convert in a 1:1 ratio at high temperatures. From the kinetic analysis the heats of NO adsorption are estimated and are in full agreement with the results of catalytic activity.

  15. Rapid Detection of Subtype H10N8 Influenza Virus by One-Step Reverse Transcription–Loop-Mediated Isothermal Amplification Methods

    PubMed Central

    Bao, Hongmei; Feng, Xiaoxiao; Ma, Yong; Shi, Jianzhong; Zhao, Yuhui; Gu, Linlin

    2015-01-01

    We developed hemagglutinin- and neuraminidase-specific one-step reverse transcription–loop-mediated isothermal amplification assays for detecting the H10N8 virus. The detection limit of the assays was 10 copies of H10N8 virus, and the assays did not amplify nonspecific RNA. The assays can detect H10N8 virus from chicken samples with high sensitivity and specificity, and they can serve as an effective tool for detecting and monitoring H10N8 virus in live poultry markets. PMID:26378283

  16. Bottom-up derivation of conservative and dissipative interactions for coarse-grained molecular liquids with the conditional reversible work method

    SciTech Connect

    Deichmann, Gregor; Marcon, Valentina; Vegt, Nico F. A. van der

    2014-12-14

    Molecular simulations of soft matter systems have been performed in recent years using a variety of systematically coarse-grained models. With these models, structural or thermodynamic properties can be quite accurately represented while the prediction of dynamic properties remains difficult, especially for multi-component systems. In this work, we use constraint molecular dynamics simulations for calculating dissipative pair forces which are used together with conditional reversible work (CRW) conservative forces in dissipative particle dynamics (DPD) simulations. The combined CRW-DPD approach aims to extend the representability of CRW models to dynamic properties and uses a bottom-up approach. Dissipative pair forces are derived from fluctuations of the direct atomistic forces between mapped groups. The conservative CRW potential is obtained from a similar series of constraint dynamics simulations and represents the reversible work performed to couple the direct atomistic interactions between the mapped atom groups. Neopentane, tetrachloromethane, cyclohexane, and n-hexane have been considered as model systems. These molecular liquids are simulated with atomistic molecular dynamics, coarse-grained molecular dynamics, and DPD. We find that the CRW-DPD models reproduce the liquid structure and diffusive dynamics of the liquid systems in reasonable agreement with the atomistic models when using single-site mapping schemes with beads containing five or six heavy atoms. For a two-site representation of n-hexane (3 carbons per bead), time scale separation can no longer be assumed and the DPD approach consequently fails to reproduce the atomistic dynamics.

  17. Bottom-up derivation of conservative and dissipative interactions for coarse-grained molecular liquids with the conditional reversible work method.

    PubMed

    Deichmann, Gregor; Marcon, Valentina; van der Vegt, Nico F A

    2014-12-14

    Molecular simulations of soft matter systems have been performed in recent years using a variety of systematically coarse-grained models. With these models, structural or thermodynamic properties can be quite accurately represented while the prediction of dynamic properties remains difficult, especially for multi-component systems. In this work, we use constraint molecular dynamics simulations for calculating dissipative pair forces which are used together with conditional reversible work (CRW) conservative forces in dissipative particle dynamics (DPD) simulations. The combined CRW-DPD approach aims to extend the representability of CRW models to dynamic properties and uses a bottom-up approach. Dissipative pair forces are derived from fluctuations of the direct atomistic forces between mapped groups. The conservative CRW potential is obtained from a similar series of constraint dynamics simulations and represents the reversible work performed to couple the direct atomistic interactions between the mapped atom groups. Neopentane, tetrachloromethane, cyclohexane, and n-hexane have been considered as model systems. These molecular liquids are simulated with atomistic molecular dynamics, coarse-grained molecular dynamics, and DPD. We find that the CRW-DPD models reproduce the liquid structure and diffusive dynamics of the liquid systems in reasonable agreement with the atomistic models when using single-site mapping schemes with beads containing five or six heavy atoms. For a two-site representation of n-hexane (3 carbons per bead), time scale separation can no longer be assumed and the DPD approach consequently fails to reproduce the atomistic dynamics. PMID:25494734

  18. The lipophilicity of artificial and natural sweeteners estimated by reversed-phase thin-layer chromatography and computed by various methods.

    PubMed

    Briciu, Rodica Domnica; Kot-Wasik, Agata; Wasik, Andrzej; Namieśnik, Jacek; Sârbu, Costel

    2010-06-01

    The chromatographic behavior of some artificial and natural sweeteners was established by reverse phase high performance thin-layer chromatography (RP-HPTLC) on RP-18, RP-18W, RP-8, CN and NH(2) stationary phases. The mobile phases were mixtures of acetonitrile-water in different proportions of volume, chosen to create a suitable migration during the chromatographic process. The lipophilicity was described through different chromatographic descriptors such as R(M0), mean of R(M) (mR(M)), and scores of R(M) values corresponding to the first principal component (PC1/R(M)). In addition, scores and loadings resulting from covariance matrix of retention data enable new information about similarity and differences of investigated compounds and between both the stationary and mobile phases. The experimental lipophilicity indices estimated from retention data are directly correlated with the computed values, via computer software and internet module, at a high significant statistical level. PMID:20430396

  19. Detection of Magnaporthe oryzae chrysovirus 1 in Japan and establishment of a rapid, sensitive and direct diagnostic method based on reverse transcription loop-mediated isothermal amplification.

    PubMed

    Komatsu, Ken; Urayama, Syun-Ichi; Katoh, Yu; Fuji, Shin-Ichi; Hase, Shu; Fukuhara, Toshiyuki; Arie, Tsutomu; Teraoka, Tohru; Moriyama, Hiromitsu

    2016-02-01

    Magnaporthe oryzae chrysovirus 1 (MoCV1) is a mycovirus with a dsRNA genome that infects the rice blast fungus Magnaporthe oryzae and impairs its growth. To date, MoCV1 has only been found in Vietnamese isolates of M. oryzae, and the distribution of this virus in M. oryzae isolates from other parts of the world remains unknown. In this study, using a one-step reverse transcription PCR (RT-PCR) assay, we detected a MoCV1-related virus in M. oryzae in Japan (named MoCV1-AK) whose sequence shares considerable similarity with that of the MoCV1 Vietnamese isolate. To establish a system for a comprehensive survey of MoCV1 infection in the field, we developed a reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay for direct detection of the virus. The sensitivity of the RT-LAMP assay was at least as high as that of the one-step RT-PCR assay. In addition, we detected MoCV1-AK in M. oryzae-infected oatmeal agar plates and lesions on rice leaves using the RT-LAMP assay without dsRNA extraction, by simple sampling with a toothpick. Preliminary screening of MoCV1 in Japanese M. oryzae isolates indicated that MoCV1 is currently distributed in rice fields in Japan. Our results provide a first example of the application of RT-LAMP for the detection of mycoviruses, which will accelerate surveys for mycovirus infection. PMID:26547578

  20. Estimation and uncertainty of reversible Markov models

    NASA Astrophysics Data System (ADS)

    Trendelkamp-Schroer, Benjamin; Wu, Hao; Paul, Fabian; Noé, Frank

    2015-11-01

    Reversibility is a key concept in Markov models and master-equation models of molecular kinetics. The analysis and interpretation of the transition matrix encoding the kinetic properties of the model rely heavily on the reversibility property. The estimation of a reversible transition matrix from simulation data is, therefore, crucial to the successful application of the previously developed theory. In this work, we discuss methods for the maximum likelihood estimation of transition matrices from finite simulation data and present a new algorithm for the estimation if reversibility with respect to a given stationary vector is desired. We also develop new methods for the Bayesian posterior inference of reversible transition matrices with and without given stationary vector taking into account the need for a suitable prior distribution preserving the meta-stable features of the observed process during posterior inference. All algorithms here are implemented in the PyEMMA software — http://pyemma.org — as of version 2.0.

  1. Ultrasonic Time Reversal Mirrors

    NASA Astrophysics Data System (ADS)

    Fink, Mathias; Montaldo, Gabriel; Tanter, Mickael

    2004-11-01

    For more than ten years, time reversal techniques have been developed in many different fields of applications including detection of defects in solids, underwater acoustics, room acoustics and also ultrasound medical imaging and therapy. The essential property that makes time reversed acoustics possible is that the underlying physical process of wave propagation would be unchanged if time were reversed. In a non dissipative medium, the equations governing the waves guarantee that for every burst of sound that diverges from a source there exists in theory a set of waves that would precisely retrace the path of the sound back to the source. If the source is pointlike, this allows focusing back on the source whatever the medium complexity. For this reason, time reversal represents a very powerful adaptive focusing technique for complex media. The generation of this reconverging wave can be achieved by using Time Reversal Mirrors (TRM). It is made of arrays of ultrasonic reversible piezoelectric transducers that can record the wavefield coming from the sources and send back its time-reversed version in the medium. It relies on the use of fully programmable multi-channel electronics. In this paper we present some applications of iterative time reversal mirrors to target detection in medical applications.

  2. Reverse Transfer in Australia

    ERIC Educational Resources Information Center

    Moodie, Gavin

    2004-01-01

    This article considers national Australian data on reverse transfer--the transfer of students from bachelor programs or higher to sub baccalaureate programs, institutions and sectors. It finds that previous studies have overstated the prevalence and perhaps also the significance of reverse transfer. The data are not good, but the best conclusion…

  3. Quantum reverse hypercontractivity

    SciTech Connect

    Cubitt, Toby; Kastoryano, Michael; Montanaro, Ashley; Temme, Kristan

    2015-10-15

    We develop reverse versions of hypercontractive inequalities for quantum channels. By generalizing classical techniques, we prove a reverse hypercontractive inequality for tensor products of qubit depolarizing channels. We apply this to obtain a rapid mixing result for depolarizing noise applied to large subspaces and to prove bounds on a quantum generalization of non-interactive correlation distillation.

  4. Justice and Reverse Discrimination.

    ERIC Educational Resources Information Center

    Goldman, Alan H.

    Defining reverse discrimination as hiring or admissions decisions based on normally irrelevant criteria, this book develops principles of rights, compensation, and equal opportunity applicable to the reverse discrimination issue. The introduction defines the issue and discusses deductive and inductive methodology as applied to reverse…

  5. Reverse Discrimination: Recent Cases.

    ERIC Educational Resources Information Center

    Steinhilber, August W.

    This paper discusses reverse discrimination cases with particular emphasis on Bakke v. Regents of University of California and those cases which preceded it. A brief history is given of court cases used by opponents and proponents in the discussion of reverse discrimination. Legal theory and a discussion of court cases that preceded Bakke follow.…

  6. Reversible Shape Memory

    NASA Astrophysics Data System (ADS)

    Zhou, Jing; Li, Qiaoxi; Turner, Sara; Brosnan, Sarah; Tippets, Cary; Carrillo, Jan-Michael; Nykypnachuk, Dmytro; Gang, Oleg; Dobrynin, Andrey; Lopez, Rene; Ashby, Valerie; Sheiko, Sergei

    2014-03-01

    Reversible shape memory has been achieved on various shapes, e.g. hairpin, origami, coil, robotic gripper and flow rate control device, allowing for multiple switching between encoded shapes without applying any external force. Also, the reversible photonic structure molded in dielectric elastomers has been designed. Maximum reversibility can be achieved by tuning the crosslinking density and the degree of crystallinity of semi-crystalline elastomers. Different crystallization protocols including isothermal and cooling crystallization have been applied to develop a universal picture integrating different shape memory (SM) behaviors: conventional one-way SM, two-way reversible SM, and one-way reversible SM. Acknowledge financial support from the NSF DMR-1122483, DMR- 1004576, and DMR-1206957.

  7. Development of an analytical method for simultaneous detection of psychotropic phenylalkylamines in hair by LC-MS/MS with a multi-mode reversed-phase column using pH gradient elution.

    PubMed

    Choi, Hyeyoung; Kim, Suncheun; Ahn, Suyoun; Chang, Hyejin; Lee, Sangki; Lee, Yongmoon

    2016-02-01

    Phenylalkylamine derivatives, such as methamphetamine (MA), 3,4-methylenedioxymethamphetamine (MDMA), phentermine, fenfluramine, phendimetrazine, amfepramone, and ketamine, are widely abused recreational or anorectic drugs in Korea, and their abuse has become a serious social problem. Hair is a useful specimen to prove chronic use and liquid chromatography-tandem mass spectrometry (LC-MS/MS) has recently become a more popular tool for hair analysis due to sensitivity and simplicity in sample preparation. In order to overcome limitations of standard reversed-phase column to separate low molecular weight amines, we adopted a multi-mode reversed-phase column, Scherzo SS-C18, which was composed of strong ionic ligands and C18 ligands, and used pH gradient elution to separate seven psychotropic phenylalkylamines and their metabolites. The essential validation parameters including selectivity, LOD, LLOQ, linearity, intra- and inter-assay precision and accuracy, recovery, and the matrix effect were satisfactory. The LODs ranged from 0.1ng/5mg hair (diethylnorephedrine, fenfluramine, ketamine, and MA) to 0.5ng/5mg hair (amfepramone, MDA, phendimetrazine, and phentermine). The LLOQs were 1ng/5mg hair for all analytes. The developed method was successfully applied to determination of phenylalkylamines in authentic hair samples analyzed previously by a routine gas chromatography/mass spectrometry (GC-MS) method. A good correlation was observed between the two methods, with a slope near one. PMID:26760907

  8. A short-range ordering in soft magnetic Fe-based metallic glasses studied by Mössbauer spectroscopy and Reverse Monte Carlo method

    NASA Astrophysics Data System (ADS)

    Babilas, Rafał; Mariola, Kądziołka-Gaweł; Burian, Andrzej; Temleitner, László

    2016-05-01

    Selected soft magnetic amorphous alloys Fe80B20, Fe70Nb10B20 and Fe62Nb8B30 were produced by the melt-spinning and characterized by X-ray diffraction (XRD), transmission Mössbauer spectroscopy (MS), Reverse Monte Carlo modeling (RMC) and relative magnetic permeability measurements. The Mössbauer spectroscopy allowed to study the local environments of the Fe-centered atoms in the amorphous structure of binary and ternary glassy alloys. The MS provided also information about the changes in the amorphous structure due to the modification of chemical composition by various boron and niobium content. The RMC simulation based on the structure factors determined by synchrotron XRD measurements was also used in modeling of the atomic arrangements and short-range order in Fe-based model alloys. Addition of boron and niobium in the ternary model alloys affected the disorder in as-cast state and also influenced on the number of nearest neighbor Fe-Fe atoms, consequently. The distributions of Fe- and B-centered coordination numbers showed that N=10, 9 and 8 are dominated around Fe atoms and N=9, 8 and 7 had the largest population around B atoms in the examined amorphous alloys. Moreover, the relationship between the content of the alloying elements, the local atomic ordering and the magnetic permeability (magnetic after-effects) was mentioned.

  9. A novel ultrasound-assisted back extraction reverse micelles method coupled with gas chromatography-flame ionization detection for determination of aldehydes in heated edibles oils.

    PubMed

    Ramezani, Zahra; Mirzajani, Roya; Kardani, Fatemeh

    2015-12-01

    A novel ultrasound-assisted back extraction reverse micelles coupled with gas chromatography-flame ionization detection has been developed for the extraction and determination of some short chain aldehydes in different heated edible oil samples. After the homogenization of the oil samples with Triton X-100, 200 μL of methanol was added to facilitate the phase separation. The aqueous micelle phase has been separated by centrifugation, then it was treated with a mixture of H2O: CHCl3 and ultrasonic vibration, were used to effectively back-extraction of the analytes into the chloroform phase. The sedimented organic phase was obtained after centrifugation, withdrawn into the microsyringe and directly injected into the GC-FID system. The calibration graphs were linear in the range 0.05-20 mg L(-1). The limits of detection were in the range of 0.02-0.15 mg L(-1). This procedure was successfully applied for determination of propanal, butanal, hexanal and heptanal in real heated oil samples. PMID:26041160

  10. Bayesian approach to the study of white dwarf binaries in LISA data: The application of a reversible jump Markov chain Monte Carlo method

    SciTech Connect

    Stroeer, Alexander; Veitch, John

    2009-09-15

    The Laser Interferometer Space Antenna (LISA) defines new demands on data analysis efforts in its all-sky gravitational wave survey, recording simultaneously thousands of galactic compact object binary foreground sources and tens to hundreds of background sources like binary black hole mergers and extreme-mass ratio inspirals. We approach this problem with an adaptive and fully automatic Reversible Jump Markov Chain Monte Carlo sampler, able to sample from the joint posterior density function (as established by Bayes theorem) for a given mixture of signals ''out of the box'', handling the total number of signals as an additional unknown parameter beside the unknown parameters of each individual source and the noise floor. We show in examples from the LISA Mock Data Challenge implementing the full response of LISA in its TDI description that this sampler is able to extract monochromatic Double White Dwarf signals out of colored instrumental noise and additional foreground and background noise successfully in a global fitting approach. We introduce 2 examples with fixed number of signals (MCMC sampling), and 1 example with unknown number of signals (RJ-MCMC), the latter further promoting the idea behind an experimental adaptation of the model indicator proposal densities in the main sampling stage. We note that the experienced runtimes and degeneracies in parameter extraction limit the shown examples to the extraction of a low but realistic number of signals.

  11. Reverse engineering of integrated circuits

    DOEpatents

    Chisholm, Gregory H.; Eckmann, Steven T.; Lain, Christopher M.; Veroff, Robert L.

    2003-01-01

    Software and a method therein to analyze circuits. The software comprises several tools, each of which perform particular functions in the Reverse Engineering process. The analyst, through a standard interface, directs each tool to the portion of the task to which it is most well suited, rendering previously intractable problems solvable. The tools are generally used iteratively to produce a successively more abstract picture of a circuit, about which incomplete a priori knowledge exists.

  12. FTIR study of horseradish peroxidase in reverse micelles.

    PubMed

    Chen, J; Xia, C; Niu, J; Li, S

    2001-04-20

    Fourier transform infrared (FTIR) method was used to study the secondary structures of horseradish peroxidase (HRP) in aqueous solution and in reverse micelles for the first time. Results indicated that the structure of HRP in sodium bis(2-ethylhexy)sulfosuccinate (AOT) reverse micelles was close to that in aqueous solution. In cetyltrimethylammonium bromide (CTAB) and sodium dodecylfate (SDS) reverse micelles the position of some bands changed. Results indicated that the secondary structure had a close relationship with the surfactant species of the reverse micelles. Among the three types of reverse micelles, the system of AOT reverse micelles was probably the most beneficial reaction media to HRP. PMID:11302746

  13. Improving the Convergence of Reversible Samplers

    NASA Astrophysics Data System (ADS)

    Rey-Bellet, Luc; Spiliopoulos, Konstantinos

    2016-06-01

    In Monte-Carlo methods the Markov processes used to sample a given target distribution usually satisfy detailed balance, i.e. they are time-reversible. However, relatively recent results have demonstrated that appropriate reversible and irreversible perturbations can accelerate convergence to equilibrium. In this paper we present some general design principles which apply to general Markov processes. Working with the generator of Markov processes, we prove that for some of the most commonly used performance criteria, i.e., spectral gap, asymptotic variance and large deviation functionals, sampling is improved for appropriate reversible and irreversible perturbations of some initially given reversible sampler. Moreover we provide specific constructions for such reversible and irreversible perturbations for various commonly used Markov processes, such as Markov chains and diffusions. In the case of diffusions, we make the discussion more specific using the large deviations rate function as a measure of performance.

  14. Improving the Convergence of Reversible Samplers

    NASA Astrophysics Data System (ADS)

    Rey-Bellet, Luc; Spiliopoulos, Konstantinos

    2016-08-01

    In Monte-Carlo methods the Markov processes used to sample a given target distribution usually satisfy detailed balance, i.e. they are time-reversible. However, relatively recent results have demonstrated that appropriate reversible and irreversible perturbations can accelerate convergence to equilibrium. In this paper we present some general design principles which apply to general Markov processes. Working with the generator of Markov processes, we prove that for some of the most commonly used performance criteria, i.e., spectral gap, asymptotic variance and large deviation functionals, sampling is improved for appropriate reversible and irreversible perturbations of some initially given reversible sampler. Moreover we provide specific constructions for such reversible and irreversible perturbations for various commonly used Markov processes, such as Markov chains and diffusions. In the case of diffusions, we make the discussion more specific using the large deviations rate function as a measure of performance.

  15. Removal of organic micro-pollutants (phenol, aniline and nitrobenzene) via forward osmosis (FO) process: Evaluation of FO as an alternative method to reverse osmosis (RO).

    PubMed

    Cui, Yue; Liu, Xiang-Yang; Chung, Tai-Shung; Weber, Martin; Staudt, Claudia; Maletzko, Christian

    2016-03-15

    In this study, we have explored and compared the effectiveness of using (1) lab-fabricated forward osmosis (FO) membranes under both FO and reverse osmosis (RO) modes and (2) commercially available RO membranes under the RO mode for the removal of organic micro-pollutants. The lab-fabricated FO membranes are thin film composite (TFC) membranes consisting of a polyamide layer and a porous substrate cast from three different materials; namely, Matrimid, polyethersulfone (PESU) and sulfonated polyphenylene sulfone (sPPSU). The results show that the FO mode is superior to the RO mode in the removal of phenol, aniline and nitrobenzene from wastewater. The rejections of all three TFC membranes to all the three organic micro-pollutants under the FO processes are higher than 72% and can be even higher than 90% for aniline when a 1000 ppm aromatic aqueous solution and 1 M NaCl are employed as feeds. These performances outperform the results obtained from themselves and commercially available RO membranes under the RO mode. In addition, the rejection can be maintained even when treating a more concentrated feed solution (2000 ppm). The removal performance can be further enhanced by using a more concentrated draw solution (2 M). The water flux is almost doubled, and the rejection increment can reach up to 17%. Moreover, it was observed that annealing as a post-treatment would help compact the membrane selective layer and further enhance the separating efficiency. The obtained organic micro-pollutant rejections and water fluxes under various feasible operating conditions indicate that the FO process has potential to be a viable treatment for wastewater containing organic micro-pollutants. PMID:26773492

  16. Development and validation of a high performance liquid chromatography method for determination of 6-benzyl-1-benzyloxymethyl-5-iodouracil (W-1), a novel non-nucleoside reverse transcriptase inhibitor and its application to a pharmacokinetic study in rats.

    PubMed

    Lu, Ying-Yuan; Wang, Xin; Wang, Xiao-Wei; Liu, Jun-Yi; Li, Pu; Ren, Hong; Lou, Ya-Qing; Lu, Chuang; Zhang, Guo-Liang

    2015-10-01

    A sensitive and selective high-performance liquid chromatographic (HPLC) method for determination of 6-benzyl-1-benzyloxymethyl-5-iodouracil (W-1), a novel non-nucleoside reverse transcriptase inhibitor in rat plasma, was developed and validated. Chromatographic separation of W-1 and megestrol acetate (internal standard) was achieved on a reversed-phase C18 column at 25°C. The mobile phase was consisted of acetonitrile-water (60:40, v/v) and pumped at a flow rate of 1.0 mL/min. The ultraviolet (UV) detector was set at the absorption wavelength of 284 nm. The calibration curve for W-1 was linear over the concentration range of 0.01-8 µg/mL and the lower limit of quantification was 10 ng/mL. The intra- and inter-day precision and accuracy were <8.9 and 5.3%, respectively. The extraction recoveries ranged from 97.9 to 101.6%. The validated HPLC method was successfully applied to a pharmacokinetic study of W-1 in rats. PMID:25808138

  17. Tubal ligation reversal

    MedlinePlus

    ... Fernandez H, Gervaise A. Tubal anastomosis after tubal sterilization: a review. Arch Gynecol Obstet . 2011 May;283( ... Berger GS, Zerden ML. Pregnancy success after hysteroscopic sterilization reversal. Obstet Gynecol . 2014 Dec;124(6):1183- ...

  18. Reversible shape memory

    NASA Astrophysics Data System (ADS)

    Sheiko, Sergei; Zhou, Jing; White, Sarah; Ashby, Valerie

    2012-02-01

    An ``Achilles' heel'' of shape memory materials is that shape transformations triggered by an external stimulus are usually irreversible. Here we present a new concept of reversible transitions between two well-defined shapes by controlling hierarchic crystallization of a dual-network elastomer. The reversibility was demonstrated for different types of shape transformations including rod bending, winding of a helical coil, and widening an aperture. The distinct feature of the reversible shape alterations is that both counter-shapes are infinitely stable at a temperature of exploitation. Shape reversibility is highly desirable property in many practical applications such as non-surgical removal of a previously inserted catheter and handfree wrapping up of an earlier unraveled solar sail on a space shuttle.

  19. Rapid Contraceptive Uptake and Changing Method Mix With High Use of Long-Acting Reversible Contraceptives in Crisis-Affected Populations in Chad and the Democratic Republic of the Congo.

    PubMed

    Rattan, Jesse; Noznesky, Elizabeth; Curry, Dora Ward; Galavotti, Christine; Hwang, Shuyuan; Rodriguez, Mariela

    2016-08-11

    The global health community has recognized that expanding the contraceptive method mix is a programmatic imperative since (1) one-third of unintended pregnancies are due to method failure or discontinuation, and (2) the addition of a new method to the existing mix tends to increase total contraceptive use. Since July 2011, CARE has been implementing the Supporting Access to Family Planning and Post-Abortion Care (SAFPAC) initiative to increase the availability, quality, and use of contraception, with a particular focus on highly effective and long-acting reversible methods-intrauterine devices (IUDs) and implants-in crisis-affected settings in Chad and the Democratic Republic of the Congo (DRC). This initiative supports government health systems at primary and referral levels to provide a wide range of contraceptive services to people affected by conflict and/or displacement. Before the initiative, long-acting reversible methods were either unknown or unavailable in the intervention areas. However, as soon as trained providers were in place, we noted a dramatic and sustained increase in new users of all contraceptive methods, especially implants, with total new clients reaching 82,855, or 32% of the estimated number of women of reproductive age in the respective catchment areas in both countries, at the end of the fourth year. Demand for implants was very strong in the first 6 months after provider training. During this time, implants consistently accounted for more than 50% of the method mix, reaching as high as 89% in Chad and 74% in DRC. To ensure that all clients were getting the contraceptive method of their choice, we conducted a series of discussions and sought feedback from different stakeholders in order to modify program strategies. Key program modifications included more focused communication in mass media, community, and interpersonal channels about the benefits of IUDs while reinforcing the wide range of methods available and refresher training for

  20. Offline solid-phase extraction for preconcentration of pharmaceuticals and personal care products in environmental water and their simultaneous determination using the reversed phase high-performance liquid chromatography method.

    PubMed

    G Archana; Dhodapkar, Rita; Kumar, Anupama

    2016-09-01

    The present study reports a precise and simple offline solid-phase extraction (SPE) coupled with reversed-phase high-performance liquid chromatography (RP-HPLC) method for the simultaneous determination of five representative and commonly present pharmaceuticals and personal care products (PPCPs), a new class of emerging pollutants in the aquatic environment. The target list of analytes including ciprofloxacin, acetaminophen, caffeine benzophenone and irgasan were separated by a simple HPLC method. The column used was a reversed-phase C18 column, and the mobile phase was 1 % acetic acid and methanol (20:80 v/v) under isocratic conditions, at a flow rate of 1 mL min(-1). The analytes were separated and detected within 15 min using the photodiode array detector (PDA). The linearity of the calibration curves were obtained with correlation coefficients 0.98-0.99.The limit of detection (LOD), limit of quantification (LOQ), precision, accuracy and ruggedness demonstrated the reproducibility, specificity and sensitivity of the developed method. Prior to the analysis, the SPE was performed using a C18 cartridge to preconcentrate the targeted analytes from the environmental water samples. The developed method was applied to evaluate and fingerprint PPCPs in sewage collected from a residential engineering college campus, polluted water bodies such as Nag river and Pili river and the influent and effluent samples from a sewage treatment plant (STP) situated at Nagpur city, in the peak summer season. This method is useful for estimation of pollutants present in microquantities in the surface water bodies and treated sewage as compared to nanolevel pollutants detected by mass spectrometry (MS) detectors. PMID:27502523

  1. Giant rodlike reversed micelles

    SciTech Connect

    Yu, Z.J.; Neuman, R.D. )

    1994-05-04

    Herein we report that sodium bis(2-ethylhexyl)phosphate, which is similar in structure to the classical surfactant sodium bis(2-ethylhexyl)sulfosuccinate (AOT), forms very large rodlike reversed micelles and that their size can be even much larger if water is removed from the apolar solution. We further suggest that long-range electrostatic interactions are the primary driving force for the formation of giant reversed micelles. 19 refs., 3 figs.

  2. Rapid Contraceptive Uptake and Changing Method Mix With High Use of Long-Acting Reversible Contraceptives in Crisis-Affected Populations in Chad and the Democratic Republic of the Congo

    PubMed Central

    Rattan, Jesse; Noznesky, Elizabeth; Curry, Dora Ward; Galavotti, Christine; Hwang, Shuyuan; Rodriguez, Mariela

    2016-01-01

    ABSTRACT The global health community has recognized that expanding the contraceptive method mix is a programmatic imperative since (1) one-third of unintended pregnancies are due to method failure or discontinuation, and (2) the addition of a new method to the existing mix tends to increase total contraceptive use. Since July 2011, CARE has been implementing the Supporting Access to Family Planning and Post-Abortion Care (SAFPAC) initiative to increase the availability, quality, and use of contraception, with a particular focus on highly effective and long-acting reversible methods—intrauterine devices (IUDs) and implants—in crisis-affected settings in Chad and the Democratic Republic of the Congo (DRC). This initiative supports government health systems at primary and referral levels to provide a wide range of contraceptive services to people affected by conflict and/or displacement. Before the initiative, long-acting reversible methods were either unknown or unavailable in the intervention areas. However, as soon as trained providers were in place, we noted a dramatic and sustained increase in new users of all contraceptive methods, especially implants, with total new clients reaching 82,855, or 32% of the estimated number of women of reproductive age in the respective catchment areas in both countries, at the end of the fourth year. Demand for implants was very strong in the first 6 months after provider training. During this time, implants consistently accounted for more than 50% of the method mix, reaching as high as 89% in Chad and 74% in DRC. To ensure that all clients were getting the contraceptive method of their choice, we conducted a series of discussions and sought feedback from different stakeholders in order to modify program strategies. Key program modifications included more focused communication in mass media, community, and interpersonal channels about the benefits of IUDs while reinforcing the wide range of methods available and refresher

  3. On thermodynamic and microscopic reversibility

    SciTech Connect

    Crooks, Gavin E.

    2011-07-12

    The word 'reversible' has two (apparently) distinct applications in statistical thermodynamics. A thermodynamically reversible process indicates an experimental protocol for which the entropy change is zero, whereas the principle of microscopic reversibility asserts that the probability of any trajectory of a system through phase space equals that of the time reversed trajectory. However, these two terms are actually synonymous: a thermodynamically reversible process is microscopically reversible, and vice versa.

  4. Reversible Seeding in Storage Rings

    SciTech Connect

    Ratner, Daniel; Chao, Alex; /SLAC

    2011-12-14

    We propose to generate steady-state microbunching in a storage ring with a reversible seeding scheme. High gain harmonic generation (HGHG) and echo-enabled harmonic generation (EEHG) are two promising methods for microbunching linac electron beams. Because both schemes increase the energy spread of the seeded beam, they cannot drive a coherent radiator turn-by-turn in a storage ring. However, reversing the seeding process following the radiator minimizes the impact on the electron beam and may allow coherent radiation at or near the storage ring repetition rate. In this paper we describe the general idea and outline a proof-of-principle experiment. Electron storage rings can drive high average power light sources, and free-electron lasers (FELs) are now producing coherent light sources of unprecedented peak brightness While there is active research towards high repetition rate FELs (for example, using energy recovery linacs), at present there are still no convenient accelerator-based sources of high repetition rate, coherent radiation. As an alternative avenue, we recently proposed to establish steady-state microbunching (SSMB) in a storage ring. By maintaining steady-state coherent microbunching at one point in the storage ring, the beam generates coherent radiation at or close to the repetition rate of the storage ring. In this paper, we propose a method of generating a microbunched beam in a storage ring by using reversible versions of linac seeding schemes.

  5. Bioanalytical method development and validation for the determination of glycine in human cerebrospinal fluid by ion-pair reversed-phase liquid chromatography-tandem mass spectrometry.

    PubMed

    Jiang, Jian; James, Christopher A; Wong, Philip

    2016-09-01

    A LC-MS/MS method has been developed and validated for the determination of glycine in human cerebrospinal fluid (CSF). The validated method used artificial cerebrospinal fluid as a surrogate matrix for calibration standards. The calibration curve range for the assay was 100-10,000ng/mL and (13)C2, (15)N-glycine was used as an internal standard (IS). Pre-validation experiments were performed to demonstrate parallelism with surrogate matrix and standard addition methods. The mean endogenous glycine concentration in a pooled human CSF determined on three days by using artificial CSF as a surrogate matrix and the method of standard addition was found to be 748±30.6 and 768±18.1ng/mL, respectively. A percentage difference of -2.6% indicated that artificial CSF could be used as a surrogate calibration matrix for the determination of glycine in human CSF. Quality control (QC) samples, except the lower limit of quantitation (LLOQ) QC and low QC samples, were prepared by spiking glycine into aliquots of pooled human CSF sample. The low QC sample was prepared from a separate pooled human CSF sample containing low endogenous glycine concentrations, while the LLOQ QC sample was prepared in artificial CSF. Standard addition was used extensively to evaluate matrix effects during validation. The validated method was used to determine the endogenous glycine concentrations in human CSF samples. Incurred sample reanalysis demonstrated reproducibility of the method. PMID:27262106

  6. Preparation and Properties of Nonionic Vesicles Prepared with Polyglycerol Fatty Acid Esters Using the Supercritical Carbon Dioxide Reverse Phase Evaporation Method.

    PubMed

    Yamaguchi, Shunsuke; Kimura, Zen; Misono, Takeshi; Tsuchiya, Koji; Sakai, Kenichi; Abe, Masahiko; Sakai, Hideki

    2016-01-01

    Previously, we reported a new preparation method for liposomes and niosomes (nonionic vesicles) using supercritical carbon dioxide (scCO2) as the solvent (scRPE method). In this study, niosomes were prepared from polyglycerol fatty acid ester (PG ester)-type nonionic surfactants. These surfactants are made from naturally derived materials and are neither harmful to the human body nor to the environment. Niosomes were prepared using the scRPE method with ethanol as the co-solvent. Through this method, decaglycerol distearate (DG2S) and decaglycerol diisostearate (DG2IS) formed niosomes. On the other hand, decaglycerol monostearate (DG1S), which has a high hydrophilic-lipophilic balance (HLB) value, yielded a solution of spherical micelles, and decaglycerol tristearate (DG3S), which has a low HLB value, yielded a gel-like solution. Niosomes of DG2IS had higher trapping efficiencies and dispersion stabilities than those of DG2S because the membrane fluidity of the DG2IS niosomes was greater than that of the DG2S niosomes. The niosomes obtained in the present study are candidates for cosmetic and pharmaceutical applications because they are formed from nonionic surfactants derived from natural sources, and prepared using the scRPE method, which avoids the use of harmful organic solvents. PMID:26876680

  7. Is Household Wealth Associated With Use of Long-Acting Reversible and Permanent Methods of Contraception? A Multi-Country Analysis.

    PubMed

    Ugaz, Jorge I; Chatterji, Minki; Gribble, James N; Banke, Kathryn

    2016-03-01

    As programs continue to expand access to family planning information, services, and products, it is critical that these efforts be undertaken with an equity lens, ensuring that regardless of socioeconomic status, all women and couples can use the method that meets their needs. This study explores the relationship between household wealth and the use of long-acting and permanent methods (LAPMs) versus short-acting methods of contraception among modern method users, using multivariate analyses based on Demographic Health Survey data from 30 developing countries conducted between 2006 and 2013. Overall, and controlling for relevant individual and household characteristics including age, number of living children, education, and urban/rural residence, we found that wealthier women were more likely than poorer women to use LAPMs instead of short-acting methods: 20 of the 30 countries showed a positive and statistically significant association between wealth and LAPM use. For 10 of those countries, however, LAPM use was significantly higher only for the top (1 or 2) wealthiest quintiles. Eight countries showed no broad pattern of association, while in 2 countries-Bangladesh and India-poorer women were more likely to use LAPMs than wealthier women. The positive association between wealth and LAPM use was found most consistently in the Latin American and the Caribbean countries in our sample. These findings can help program implementers respond better to women's needs for modern contraception, especially in reaching women from lower- and middle-income households. PMID:27016543

  8. Is Household Wealth Associated With Use of Long-Acting Reversible and Permanent Methods of Contraception? A Multi-Country Analysis

    PubMed Central

    Ugaz, Jorge I; Chatterji, Minki; Gribble, James N; Banke, Kathryn

    2016-01-01

    Abstract As programs continue to expand access to family planning information, services, and products, it is critical that these efforts be undertaken with an equity lens, ensuring that regardless of socioeconomic status, all women and couples can use the method that meets their needs. This study explores the relationship between household wealth and the use of long-acting and permanent methods (LAPMs) versus short-acting methods of contraception among modern method users, using multivariate analyses based on Demographic Health Survey data from 30 developing countries conducted between 2006 and 2013. Overall, and controlling for relevant individual and household characteristics including age, number of living children, education, and urban/rural residence, we found that wealthier women were more likely than poorer women to use LAPMs instead of short-acting methods: 20 of the 30 countries showed a positive and statistically significant association between wealth and LAPM use. For 10 of those countries, however, LAPM use was significantly higher only for the top (1 or 2) wealthiest quintiles. Eight countries showed no broad pattern of association, while in 2 countries—Bangladesh and India—poorer women were more likely to use LAPMs than wealthier women. The positive association between wealth and LAPM use was found most consistently in the Latin American and the Caribbean countries in our sample. These findings can help program implementers respond better to women’s needs for modern contraception, especially in reaching women from lower- and middle-income households. PMID:27016543

  9. A numerical solution of the magnetization reversal modeling in a permalloy thin film using fifth order Runge Kutta method with adaptive step size control

    NASA Astrophysics Data System (ADS)

    Romeo, A.; Finocchio, G.; Carpentieri, M.; Torres, L.; Consolo, G.; Azzerboni, B.

    2008-02-01

    The Landau-Lifshitz-Gilbert (LLG) equation is the fundamental equation to describe magnetization dynamics in microscale and nanoscale magnetic systems. In this paper we present a brief overview of a time-domain numerical method related to the fifth order Runge-Kutta formula, which has been applied to the solution of the LLG equation successfully. We discuss advantages of the method, describing the results of a numerical experiment based on the standard problem #4. The results are in good agreement with the ones present in literature. By including thermal effects in our framework, our simulations show magnetization dynamics slightly dependent on the spatial discretization.

  10. Reversible collisionless magnetic reconnection

    SciTech Connect

    Ishizawa, A.; Watanabe, T.-H.

    2013-10-15

    Reversible magnetic reconnection is demonstrated for the first time by means of gyrokinetic numerical simulations of a collisionless magnetized plasma. Growth of a current-driven instability in a sheared magnetic field is accompanied by magnetic reconnection due to electron inertia effects. Following the instability growth, the collisionless reconnection is accelerated with development of a cross-shaped structure of current density, and then all field lines are reconnected. The fully reconnected state is followed by the secondary reconnection resulting in a weakly turbulent state. A time-reversed simulation starting from the turbulent state manifests that the collisionless reconnection process proceeds inversely leading to the initial state. During the reversed reconnection, the kinetic energy is reconverted into the original magnetic field energy. In order to understand the stability of reversed process, an external perturbation is added to the fully reconnected state, and it is found that the accelerated reconnection is reversible when the deviation of the E × B streamlines due to the perturbation is comparable with or smaller than a current layer width.