Science.gov

Sample records for detecting crystal wplyw

  1. Automated macromolecular crystal detection system and method

    DOEpatents

    Christian, Allen T.; Segelke, Brent; Rupp, Bernard; Toppani, Dominique

    2007-06-05

    An automated macromolecular method and system for detecting crystals in two-dimensional images, such as light microscopy images obtained from an array of crystallization screens. Edges are detected from the images by identifying local maxima of a phase congruency-based function associated with each image. The detected edges are segmented into discrete line segments, which are subsequently geometrically evaluated with respect to each other to identify any crystal-like qualities such as, for example, parallel lines, facing each other, similarity in length, and relative proximity. And from the evaluation a determination is made as to whether crystals are present in each image.

  2. Rapid leak detection with liquid crystals

    NASA Technical Reports Server (NTRS)

    Heisman, R. M.; Iceland, W. F.; Ruppe, E. P.

    1978-01-01

    Small leaks in vacuum lines are detected by applying liquid-crystal coating, warming suspected area, and observing color change due to differential cooling by leak jet. Technique is used on inside or outside walls of vacuum-jacketed lines.

  3. Neutron detection with single crystal organic scintillators

    SciTech Connect

    Zaitseva, N; Newby, J; Hamel, S; Carman, L; Faust, M; Lordi, V; Cherepy, N; Stoeffl, W; Payne, S

    2009-07-15

    Detection of high-energy neutrons in the presence of gamma radiation background utilizes pulse-shape discrimination (PSD) phenomena in organics studied previously only with limited number of materials, mostly liquid scintillators and single crystal stilbene. The current paper presents the results obtained with broader varieties of luminescent organic single crystals. The studies involve experimental tools of crystal growth and material characterization in combination with the advanced computer modeling, with the final goal of better understanding the relevance between the nature of the organic materials and their PSD properties. Special consideration is given to the factors that may diminish or even completely obscure the PSD properties in scintillating crystals. Among such factors are molecular and crystallographic structures that determine exchange coupling and exciton mobility in organic materials and the impurity effect discussed on the examples of trans-stilbene, bibenzyl, 9,10-diphenylanthracene and diphenylacetylene.

  4. Two-dimensional photonic crystal surfactant detection.

    PubMed

    Zhang, Jian-Tao; Smith, Natasha; Asher, Sanford A

    2012-08-01

    We developed a novel two-dimensional (2-D) crystalline colloidal array photonic crystal sensing material for the visual detection of amphiphilic molecules in water. A close-packed polystyrene 2-D array monolayer was embedded in a poly(N-isopropylacrylamide) (PNIPAAm)-based hydrogel film. These 2-D photonic crystals placed on a mirror show intense diffraction that enables them to be used for visual determination of analytes. Binding of surfactant molecules attaches ions to the sensor that swells the PNIPAAm-based hydrogel. The resulting increase in particle spacing red shifts the 2-D diffracted light. Incorporation of more hydrophobic monomers increases the sensitivity to surfactants. PMID:22720790

  5. Neutron detection using a crystal ball calorimeter

    SciTech Connect

    Martem’yanov, M. A. Kulikov, V. V.; Krutenkova, A. P.

    2015-12-15

    The program of experiments of the A2 Collaboration performed on a beam of tagged photons of the MAMI electron microtron in Mainz (Germany) includes precision measurements of the total and differential cross sections of the pion photoproduction on neutrons of a deuterium target. The determination of the detector ability to detect neutrons is undoubtedly one of the important problems of the experiment. The calorimetric system of the detector contains a segmented NaI Crystal Ball detector, which gives information about the position, energy, and detection time of neutral and charged particles in a wide angular range. In this work, we describe the measurement of the neutron detection efficiency in the energy range from 20 to 400MeV. The results are compared with BNL data obtained on a pion beam and proton target.

  6. Neutron detection using a crystal ball calorimeter

    NASA Astrophysics Data System (ADS)

    Martem'yanov, M. A.; Kulikov, V. V.; Krutenkova, A. P.

    2015-12-01

    The program of experiments of the A2 Collaboration performed on a beam of tagged photons of the MAMI electron microtron in Mainz (Germany) includes precision measurements of the total and differential cross sections of the pion photoproduction on neutrons of a deuterium target. The determination of the detector ability to detect neutrons is undoubtedly one of the important problems of the experiment. The calorimetric system of the detector contains a segmented NaI Crystal Ball detector, which gives information about the position, energy, and detection time of neutral and charged particles in a wide angular range. In this work, we describe the measurement of the neutron detection efficiency in the energy range from 20 to 400MeV. The results are compared with BNL data obtained on a pion beam and proton target.

  7. Ionizing particle detection based on phononic crystals

    SciTech Connect

    Aly, Arafa H. E-mail: arafa.hussien@science.bsu.edu.eg; Mehaney, Ahmed; Eissa, Mostafa F.

    2015-08-14

    Most conventional radiation detectors are based on electronic or photon collections. In this work, we introduce a new and novel type of ionizing particle detector based on phonon collection. Helium ion radiation treats tumors with better precision. There are nine known isotopes of helium, but only helium-3 and helium-4 are stable. Helium-4 is formed in fusion reactor technology and in enormous quantities during Big Bang nucleo-synthesis. In this study, we introduce a technique for helium-4 ion detection (sensing) based on the innovative properties of the new composite materials known as phononic crystals (PnCs). PnCs can provide an easy and cheap technique for ion detection compared with conventional methods. PnC structures commonly consist of a periodic array of two or more materials with different elastic properties. The two materials are polymethyl-methacrylate and polyethylene polymers. The calculations showed that the energies lost to target phonons are maximized at 1 keV helium-4 ion energy. There is a correlation between the total phonon energies and the transmittance of PnC structures. The maximum transmission for phonons due to the passage of helium-4 ions was found in the case of making polyethylene as a first layer in the PnC structure. Therefore, the concept of ion detection based on PnC structure is achievable.

  8. Ionizing particle detection based on phononic crystals

    NASA Astrophysics Data System (ADS)

    Aly, Arafa H.; Mehaney, Ahmed; Eissa, Mostafa F.

    2015-08-01

    Most conventional radiation detectors are based on electronic or photon collections. In this work, we introduce a new and novel type of ionizing particle detector based on phonon collection. Helium ion radiation treats tumors with better precision. There are nine known isotopes of helium, but only helium-3 and helium-4 are stable. Helium-4 is formed in fusion reactor technology and in enormous quantities during Big Bang nucleo-synthesis. In this study, we introduce a technique for helium-4 ion detection (sensing) based on the innovative properties of the new composite materials known as phononic crystals (PnCs). PnCs can provide an easy and cheap technique for ion detection compared with conventional methods. PnC structures commonly consist of a periodic array of two or more materials with different elastic properties. The two materials are polymethyl-methacrylate and polyethylene polymers. The calculations showed that the energies lost to target phonons are maximized at 1 keV helium-4 ion energy. There is a correlation between the total phonon energies and the transmittance of PnC structures. The maximum transmission for phonons due to the passage of helium-4 ions was found in the case of making polyethylene as a first layer in the PnC structure. Therefore, the concept of ion detection based on PnC structure is achievable.

  9. Enhanced photoacoustic detection using photonic crystal substrate

    NASA Astrophysics Data System (ADS)

    Zhao, Yunfei; Liu, Kaiyang; McClelland, John; Lu, Meng

    2014-04-01

    This paper demonstrates the enhanced photoacoustic sensing of surface-bound light absorbing molecules and metal nanoparticles using a one-dimensional photonic crystal (PC) substrate. The PC structure functions as an optical resonator at the wavelength where the analyte absorption is strong. The optical resonance of the PC sensor provides an intensified evanescent field with respect to the excitation light source and results in enhanced optical absorption by surface-immobilized samples. For the analysis of a light absorbing dye deposited on the PC surface, the intensity of photoacoustic signal was enhanced by more than 10-fold in comparison to an un-patterned acrylic substrate. The technique was also applied to detect gold nanorods and exhibited more than 40 times stronger photoacoustic signals. The demonstrated approach represents a potential path towards single molecule absorption spectroscopy with greater performance and inexpensive instrumentation.

  10. Enhanced photoacoustic detection using photonic crystal substrate

    SciTech Connect

    Zhao, Yunfei; Liu, Kaiyang; McClelland, John; Lu, Meng

    2014-04-21

    This paper demonstrates the enhanced photoacoustic sensing of surface-bound light absorbing molecules and metal nanoparticles using a one-dimensional photonic crystal (PC) substrate. The PC structure functions as an optical resonator at the wavelength where the analyte absorption is strong. The optical resonance of the PC sensor provides an intensified evanescent field with respect to the excitation light source and results in enhanced optical absorption by surface-immobilized samples. For the analysis of a light absorbing dye deposited on the PC surface, the intensity of photoacoustic signal was enhanced by more than 10-fold in comparison to an un-patterned acrylic substrate. The technique was also applied to detect gold nanorods and exhibited more than 40 times stronger photoacoustic signals. The demonstrated approach represents a potential path towards single molecule absorption spectroscopy with greater performance and inexpensive instrumentation.

  11. Color changing photonic crystals detect blast exposure.

    PubMed

    Cullen, D Kacy; Xu, Yongan; Reneer, Dexter V; Browne, Kevin D; Geddes, James W; Yang, Shu; Smith, Douglas H

    2011-01-01

    Blast-induced traumatic brain injury (bTBI) is the "signature wound" of the current wars in Iraq and Afghanistan. However, with no objective information of relative blast exposure, warfighters with bTBI may not receive appropriate medical care and are at risk of being returned to the battlefield. Accordingly, we have created a colorimetric blast injury dosimeter (BID) that exploits material failure of photonic crystals to detect blast exposure. Appearing like a colored sticker, the BID is fabricated in photosensitive polymers via multi-beam interference lithography. Although very stable in the presence of heat, cold or physical impact, sculpted micro- and nano-structures of the BID are physically altered in a precise manner by blast exposure, resulting in color changes that correspond with blast intensity. This approach offers a lightweight, power-free sensor that can be readily interpreted by the naked eye. Importantly, with future refinement this technology may be deployed to identify soldiers exposed to blast at levels suggested to be supra-threshold for non-impact blast-induced mild TBI.

  12. Color changing photonic crystals detect blast exposure

    PubMed Central

    Cullen, D. Kacy; Xu, Yongan; Reneer, Dexter V.; Browne, Kevin D.; Geddes, James W.; Yang, Shu; Smith, Douglas H.

    2010-01-01

    Blast-induced traumatic brain injury (bTBI) is the “signature wound” of the current wars in Iraq and Afghanistan. However, with no objective information of relative blast exposure, warfighters with bTBI may not receive appropriate medical care and are at risk of being returned to the battlefield. Accordingly, we have created a colorimetric blast injury dosimeter (BID) that exploits material failure of photonic crystals to detect blast exposure. Appearing like a colored sticker, the BID is fabricated in photosensitive polymers via multi-beam interference lithography. Although very stable in the presence of heat, cold or physical impact, sculpted micro- and nano-structures of the BID are physically altered in a precise manner by blast exposure, resulting in color changes that correspond with blast intensity. This approach offers a lightweight, power-free sensor that can be readily interpreted by the naked eye. Importantly, with future refinement this technology may be deployed to identify soldiers exposed to blast at levels suggested to be supra-threshold for non-impact blast-induced mild TBI. PMID:21040795

  13. Acoustic Methods to Monitor Protein Crystallization and to Detect Protein Crystals in Suspensions of Agarose and Lipidic Cubic Phase.

    PubMed

    Ericson, Daniel L; Yin, Xingyu; Scalia, Alexander; Samara, Yasmin N; Stearns, Richard; Vlahos, Harry; Ellson, Richard; Sweet, Robert M; Soares, Alexei S

    2016-02-01

    Improvements needed for automated crystallography include crystal detection and crystal harvesting. A technique that uses acoustic droplet ejection to harvest crystals was previously reported. Here a method is described for using the same acoustic instrument to detect protein crystals and to monitor crystal growth. Acoustic pulses were used to monitor the progress of crystallization trials and to detect the presence and location of protein crystals. Crystals were detected, and crystallization was monitored in aqueous solutions and in lipidic cubic phase. Using a commercially available acoustic instrument, crystals measuring ~150 µm or larger were readily detected. Simple laboratory techniques were used to increase the sensitivity to 50 µm by suspending the crystals away from the plastic surface of the crystallization plate. This increased the sensitivity by separating the strong signal generated by the plate bottom that can mask the signal from small protein crystals. It is possible to further boost the acoustic reflection from small crystals by reducing the wavelength of the incident sound pulse, but our current instrumentation does not allow this option. In the future, commercially available sound-emitting transducers with a characteristic frequency near 300 MHz should detect and monitor the growth of individual 3 µm crystals.

  14. Optical detection of sepsis markers using liquid crystal based biosensors

    NASA Astrophysics Data System (ADS)

    McCamley, Maureen K.; Artenstein, Andrew W.; Opal, Steven M.; Crawford, Gregory P.

    2007-02-01

    A liquid crystal based biosensor for the detection and diagnosis of sepsis is currently in development. Sepsis, a major clinical syndrome with a significant public health burden in the US due to a large elderly population, is the systemic response of the body to a localized infection and is defined as the combination of pathologic infection and physiological changes. Bacterial infections are responsible for 90% of cases of sepsis in the US. Currently there is no bedside diagnostic available to positively identify sepsis. The basic detection scheme employed in a liquid crystal biosensor contains attributes that would find value in a clinical setting, especially for the early detection of sepsis. Utilizing the unique properties of liquid crystals, such as birefringence, a bedside diagnostic is in development which will optically report the presence of biomolecules. In a septic patient, an endotoxin known as lipopolysaccharide (LPS) is released from the outer membrane of Gram-negative bacteria and can be found in the blood stream. It is hypothesized that this long chained molecule will cause local disruptions to the open surface of a sensor containing aligned liquid crystal. The bulk liquid crystal ampli.es these local changes at the surface due to the presence of the sepsis marker, providing an optical readout through polarizing microscopy images. Liquid crystal sensors consisting of both square and circular grids, 100-200 μm in size, have been fabricated and filled with a common liquid crystal material, 5CB. Homeotropic alignment was confirmed using polarizing microscopy. The grids were then contacted with either saline only (control), or saline with varying concentrations of LPS. Changes in the con.guration of the nematic director of the liquid crystal were observed through the range of concentrations tested (5mg/mL - 1pg/mL) which have been confirmed by a consulting physician as clinically relevant levels.

  15. Detection of endotoxin using a photonic crystal nanolaser

    NASA Astrophysics Data System (ADS)

    Takahashi, Daichi; Hachuda, Shoji; Watanabe, Takumi; Nishijima, Yoshiaki; Baba, Toshihiko

    2015-03-01

    Fast and reliable detection of endotoxin (ET) in medical equipment and pharmaceutical products is an essential precursor to clinical treatment. In this study, we demonstrate the use of shifts in wavelength of photonic crystal nanolasers for sensing the Limulus amebocyte lysate reaction, which is a standard method for detecting ET. From working curves of wavelength shift vs ET concentration, whose correlation factors were as high as 98%, we detected a required concentration of 0.001 EU/ml within 33 min and detected a low concentration of 0.0001 EU/ml.

  16. Detection of endotoxin using a photonic crystal nanolaser

    SciTech Connect

    Takahashi, Daichi; Hachuda, Shoji; Watanabe, Takumi; Nishijima, Yoshiaki; Baba, Toshihiko

    2015-03-30

    Fast and reliable detection of endotoxin (ET) in medical equipment and pharmaceutical products is an essential precursor to clinical treatment. In this study, we demonstrate the use of shifts in wavelength of photonic crystal nanolasers for sensing the Limulus amebocyte lysate reaction, which is a standard method for detecting ET. From working curves of wavelength shift vs ET concentration, whose correlation factors were as high as 98%, we detected a required concentration of 0.001 EU/ml within 33 min and detected a low concentration of 0.0001 EU/ml.

  17. Liquid crystals detect voids in fiber glass laminates

    NASA Technical Reports Server (NTRS)

    Hollar, W. T.

    1967-01-01

    Liquid crystal solution nondestructively detects voids or poor bond lines in fiber glass laminates. A thin coating of the solution is applied by spray or brush to the test article surface, and when heated indicates the exact location of defects by differences in color.

  18. A liquid-crystal-based DNA biosensor for pathogen detection

    PubMed Central

    Khan, Mashooq; Khan, Abdur Rahim; Shin, Jae-Ho; Park, Soo-Young

    2016-01-01

    A liquid-crystal (LC)-filled transmission electron microscopy (TEM) grid cell coated with the cationic surfactant dodecyltrimethylammonium bromide (DTAB), to which a single-stranded deoxyribonucleic acid probe (ssDNAprobe) was adsorbed at the LC/aqueous interface (TEMDTAB/DNA), was applied for the highly specific detection of target DNA molecules. The DTAB-coated E7 (used LC mixture) in the TEM grid (TEMDTAB) exhibited a homeotropic orientation, and changed to a planar orientation upon adsorption of the ssDNAprobe. The TEMDTAB/DNA was then exposed to complementary (target) ssDNA, which resulted in a planar-to-homeotropic configurational change of E7 that could be observed through a polarized optical microscope under crossed polarizers. The optimum adsorption density (2 μM) of ssDNAprobe enabled the detection of ≥0.05 nM complementary ssDNA. This TEMDTAB/DNA biosensor could differentiate complementary ssDNA from mismatched ssDNA as well as double-stranded DNA. It also successfully detected the genomic DNAs of the bacterium Erwinia carotovora and the fungi Rhazictonia solani. Owe to the high specificity, sensitivity, and label-free detection, this biosensor may broaden the applications of LC-based biosensors to pathogen detection. PMID:26940532

  19. Nanostructured Surfaces and Detection Instrumentation for Photonic Crystal Enhanced Fluorescence

    PubMed Central

    Chaudhery, Vikram; George, Sherine; Lu, Meng; Pokhriyal, Anusha; Cunningham, Brian T.

    2013-01-01

    Photonic crystal (PC) surfaces have been demonstrated as a compelling platform for improving the sensitivity of surface-based fluorescent assays used in disease diagnostics and life science research. PCs can be engineered to support optical resonances at specific wavelengths at which strong electromagnetic fields are utilized to enhance the intensity of surface-bound fluorophore excitation. Meanwhile, the leaky resonant modes of PCs can be used to direct emitted photons within a narrow range of angles for more efficient collection by a fluorescence detection system. The multiplicative effects of enhanced excitation combined with enhanced photon extraction combine to provide improved signal-to-noise ratios for detection of fluorescent emitters, which in turn can be used to reduce the limits of detection of low concentration analytes, such as disease biomarker proteins. Fabrication of PCs using inexpensive manufacturing methods and materials that include replica molding on plastic, nano-imprint lithography on quartz substrates result in devices that are practical for single-use disposable applications. In this review, we will describe the motivation for implementing high-sensitivity fluorescence detection in the context of molecular diagnosis and gene expression analysis though the use of PC surfaces. Recent efforts to improve the design and fabrication of PCs and their associated detection instrumentation are summarized, including the use of PCs coupled with Fabry-Perot cavities and external cavity lasers. PMID:23624689

  20. A liquid-crystal-based DNA biosensor for pathogen detection.

    PubMed

    Khan, Mashooq; Khan, Abdur Rahim; Shin, Jae-Ho; Park, Soo-Young

    2016-01-01

    A liquid-crystal (LC)-filled transmission electron microscopy (TEM) grid cell coated with the cationic surfactant dodecyltrimethylammonium bromide (DTAB), to which a single-stranded deoxyribonucleic acid probe (ssDNAprobe) was adsorbed at the LC/aqueous interface (TEMDTAB/DNA), was applied for the highly specific detection of target DNA molecules. The DTAB-coated E7 (used LC mixture) in the TEM grid (TEMDTAB) exhibited a homeotropic orientation, and changed to a planar orientation upon adsorption of the ssDNAprobe. The TEMDTAB/DNA was then exposed to complementary (target) ssDNA, which resulted in a planar-to-homeotropic configurational change of E7 that could be observed through a polarized optical microscope under crossed polarizers. The optimum adsorption density (2 μM) of ssDNAprobe enabled the detection of ≥0.05 nM complementary ssDNA. This TEMDTAB/DNA biosensor could differentiate complementary ssDNA from mismatched ssDNA as well as double-stranded DNA. It also successfully detected the genomic DNAs of the bacterium Erwinia carotovora and the fungi Rhazictonia solani. Owe to the high specificity, sensitivity, and label-free detection, this biosensor may broaden the applications of LC-based biosensors to pathogen detection.

  1. A liquid-crystal-based DNA biosensor for pathogen detection.

    PubMed

    Khan, Mashooq; Khan, Abdur Rahim; Shin, Jae-Ho; Park, Soo-Young

    2016-01-01

    A liquid-crystal (LC)-filled transmission electron microscopy (TEM) grid cell coated with the cationic surfactant dodecyltrimethylammonium bromide (DTAB), to which a single-stranded deoxyribonucleic acid probe (ssDNAprobe) was adsorbed at the LC/aqueous interface (TEMDTAB/DNA), was applied for the highly specific detection of target DNA molecules. The DTAB-coated E7 (used LC mixture) in the TEM grid (TEMDTAB) exhibited a homeotropic orientation, and changed to a planar orientation upon adsorption of the ssDNAprobe. The TEMDTAB/DNA was then exposed to complementary (target) ssDNA, which resulted in a planar-to-homeotropic configurational change of E7 that could be observed through a polarized optical microscope under crossed polarizers. The optimum adsorption density (2 μM) of ssDNAprobe enabled the detection of ≥0.05 nM complementary ssDNA. This TEMDTAB/DNA biosensor could differentiate complementary ssDNA from mismatched ssDNA as well as double-stranded DNA. It also successfully detected the genomic DNAs of the bacterium Erwinia carotovora and the fungi Rhazictonia solani. Owe to the high specificity, sensitivity, and label-free detection, this biosensor may broaden the applications of LC-based biosensors to pathogen detection. PMID:26940532

  2. A liquid-crystal-based DNA biosensor for pathogen detection

    NASA Astrophysics Data System (ADS)

    Khan, Mashooq; Khan, Abdur Rahim; Shin, Jae-Ho; Park, Soo-Young

    2016-03-01

    A liquid-crystal (LC)-filled transmission electron microscopy (TEM) grid cell coated with the cationic surfactant dodecyltrimethylammonium bromide (DTAB), to which a single-stranded deoxyribonucleic acid probe (ssDNAprobe) was adsorbed at the LC/aqueous interface (TEMDTAB/DNA), was applied for the highly specific detection of target DNA molecules. The DTAB-coated E7 (used LC mixture) in the TEM grid (TEMDTAB) exhibited a homeotropic orientation, and changed to a planar orientation upon adsorption of the ssDNAprobe. The TEMDTAB/DNA was then exposed to complementary (target) ssDNA, which resulted in a planar-to-homeotropic configurational change of E7 that could be observed through a polarized optical microscope under crossed polarizers. The optimum adsorption density (2 μM) of ssDNAprobe enabled the detection of ≥0.05 nM complementary ssDNA. This TEMDTAB/DNA biosensor could differentiate complementary ssDNA from mismatched ssDNA as well as double-stranded DNA. It also successfully detected the genomic DNAs of the bacterium Erwinia carotovora and the fungi Rhazictonia solani. Owe to the high specificity, sensitivity, and label-free detection, this biosensor may broaden the applications of LC-based biosensors to pathogen detection.

  3. Liquid crystals as optical amplifiers for bacterial detection.

    PubMed

    Zafiu, C; Hussain, Z; Küpcü, S; Masutani, A; Kilickiran, P; Sinner, E-K

    2016-06-15

    Interactions of bacteria with target molecules (e.g. antibiotics) or other microorganisms are of growing interest. The first barrier for targeting gram-negative bacteria is layer of a Lipopolysaccharides (LPS). Liquid crystal (LC) based sensors covered with LPS monolayers, as presented in this study, offer a simple model to study and make use of this type of interface for detection and screening. This work describes in detail the production and application of such sensors based on three different LPS that have been investigated regarding their potential to serve as sensing layer to detect bacteria. The LPS O127:B8 in combination with a LC based sensor was identified to be most useful as biomimetic sensing surface. This LPS/LC combination interacts with three different bacteria species, one gram-positive and two gram-negative species, allowing the detection of bacterial presence regardless from their viability. It could be shown that even very low bacterial cell numbers (minimum 500 cell ml(-1)) could be detected within minutes (maximum 15 min). The readout mechanism is the adsorption of bacterial entities on surface bond LPS molecules with the LC serving as an optical amplifier.

  4. Liquid crystal based biosensors for bile acid detection

    NASA Astrophysics Data System (ADS)

    He, Sihui; Liang, Wenlang; Tanner, Colleen; Fang, Jiyu; Wu, Shin-Tson

    2013-03-01

    The concentration level of bile acids is a useful indicator for early diagnosis of liver diseases. The prevalent measurement method in detecting bile acids is the chromatography coupled with mass spectrometry, which is precise yet expensive. Here we present a biosensor platform based on liquid crystal (LC) films for the detection of cholic acid (CA). This platform has the advantage of low cost, label-free, solution phase detection and simple analysis. In this platform, LC film of 4-Cyano-4'-pentylbiphenyl (5CB) was hosted by a copper grid supported with a polyimide-coated glass substrate. By immersing into sodium dodecyl sulfate (SDS) solution, the LC film was coated with SDS which induced a homeotropic anchoring of 5CB. Addition of CA introduced competitive adsorption between CA and SDS at the interface, triggering a transition from homeotropic to homogeneous anchoring. The detection limit can be tuned by changing the pH value of the solution from 12uM to 170uM.

  5. Detection of Membrane Protein Two-Dimensional Crystals in Living Cells

    PubMed Central

    Gualtieri, E.J.; Guo, F.; Kissick, D.J.; Jose, J.; Kuhn, R.J.; Jiang, W.; Simpson, G.J.

    2011-01-01

    It is notoriously difficult to grow membrane protein crystals and solve membrane protein structures. Improved detection and screening of membrane protein crystals are needed. We have shown here that second-order nonlinear optical imaging of chiral crystals based on second harmonic generation can provide sensitive and selective detection of two-dimensional protein crystalline arrays with sufficiently low background to enable crystal detection within the membranes of live cells. The method was validated using bacteriorhodopsin crystals generated in live Halobacterium halobium bacteria and confirmed by electron microscopy from the isolated crystals. Additional studies of alphavirus glycoproteins indicated the presence of localized crystalline domains associated with virus budding from mammalian cells. These results suggest that in vivo crystallization may provide a means for expediting membrane protein structure determination for proteins exhibiting propensities for two-dimensional crystal formation. PMID:21190673

  6. Photonic crystal fiber modal interferometer for explosives detection

    NASA Astrophysics Data System (ADS)

    Tao, Chuanyi; Wei, Heming; Krishnaswamy, Sridhar

    2016-04-01

    The detection of explosives and their residues is of great importance in public health, antiterrorism and homeland security applications. The vapor pressures of most explosive compounds are extremely low and attenuation of the available vapor is often great due to diffusion in the environment, making direct vapor detection difficult. In this paper, a photonic-microfluidic integrated sensor for highly sensitive 2,4,6-trinitrotoluene (TNT) detection is described based on an in-fiber Mach-Zehnder interferometer (MZI) in a photonic crystal fiber (PCF). A segment of PCF is inserted between standard single-mode fibers (SMF) via butt coupling to form a modal interferometer, in which the cladding modes are excited and interfere with the fundamental core mode. Due to butt coupling, the small air gap between SMF and PCF forms a coupling region and also serves as an inlet/outlet for the gas. The sensor is fabricated by immobilizing a chemo-recognition coating on the inner surface of the holey region of the PCF, which selectively and reversibly binds TNT molecules on the sensitized surface. The sensing mechanism is based on the determination of the TNT-induced wavelength shift of interference peaks due to the refractive index change of the holey-layer. The sensor device therefore is capable of field operation.

  7. Quartz crystal microbalance biosensor for rapid detection of aerosolized microorganisms

    NASA Astrophysics Data System (ADS)

    Farka, Zdenĕk.; Kovár, David; Skládal, Petr

    2015-05-01

    Biological warfare agents (BWAs) represent the current menace of the asymmetric war. The early detection of BWAs, especially in the form of bioaerosol, is a challenging task for governments all around the world. Label-free quartz crystal microbalance (QCM) immunosensor and electrochemical immunosensor were developed and tested for rapid detection of BWA surrogate (E. coli) in the form of bioaerosol. Two immobilization strategies for the attachment of antibody were tested; the gold sensor surface was activated by cysteamine and then antibody was covalently linked either using glutaraldehyde, or the reduced antibodies were attached via Sulfo-SMCC. A portable bioaerosol chamber was constructed and used for safe manipulation with aerosolized microorganisms. The dissemination was done using a piezoelectric humidifier, distribution of bioaerosol inside the chamber was ensured using three 12-cm fans. The whole system was controlled remotely using LAN network. The disseminated microbial cells were collected and preconcentrated using the wetted-wall cyclone SASS 2300, the analysis was done using the on-line linked immunosensors. The QCM immunosensor had limit of detection 1×104 CFU·L-1 of air with analysis time 16 min, the whole experiment including dissemination and sensor surface regeneration took 40 min. In case of blank (disseminated sterile buffer), no signal change was observed. The electrochemical immunosensor was able to detect 150 CFU·L-1 of air in 20 min; also in this case, no interferences were observed. Reference measurements were done using particle counter Met One 3400 and by cultivation method on agar plates. The sensors have proved to be applicable for rapid screening of microorganisms in air.

  8. Specific and ultrasensitive ciprofloxacin detection by responsive photonic crystal sensor.

    PubMed

    Zhang, Rong; Wang, Yong; Yu, Li-Ping

    2014-09-15

    A new approach for specific and ultrasensitive measurement of ciprofloxacin has been developed by integrating ternary complexes into responsive photonic crystal (RPC). Tryptophan was first immobilized within the polyacrylamide hydrogel substrates of RPC. The determination of ciprofloxacin was via the existence of zinc(II) ions that function as a 'bridge' to form specific tryptophan-zinc(II)-ciprofloxacin complexes step by step, which resulted in a stepwise red-shift of the diffraction wavelength. A maximum wavelength shift from 798 to 870 nm for ciprofloxacin was observed when the RPC film was immersed in 10(-4)M ciprofloxacin. A linear relationship has been obtained between the Δλ of diffraction peak and logarithm of ciprofloxacin concentration at pH 5.0 in the range of 10(-10) to 10(-4)M. And the least detectable concentration in present work is about 5 × 10(-11)M. The results demonstrated that the as-designed ternary complexes-based RPC sensor exhibited high sensitivity, satisfactory specificity and excellent recoverability for sensing of ciprofloxacin in aqueous media and were validated by detecting ciprofloxacin in the eye-drop sample. PMID:25127388

  9. Porous silicon photonic crystals for detection of infections

    NASA Astrophysics Data System (ADS)

    Gupta, B.; Guan, B.; Reece, P. J.; Gooding, J. J.

    2012-10-01

    In this paper we demonstrate the possibility of modifying porous silicon (PSi) particles with surface chemistry and immobilizing a biopolymer, gelatin for the detection of protease enzymes in solution. A rugate filter, a one-dimensional photonic crystal, is fabricated that exhibits a high-reflectivity optical resonance that is sensitive to small changes in the refractive index. To immobilize gelatin in the pores of the particles, the hydrogen-terminated silicon surface was first modified with an alkyne, 1,8-nonadiyne via hydrosilylation to protect the silicon surfaces from oxidation. This modification allows for further functionality to be added such as the coupling of gelatin. Exposure of the gelatin modified particles to the protease subtilisin in solution causes a change in the refractive index, resulting in a shift of the resonance to shorter wavelengths, indicating cleavage of organic material within the pores. The ability to monitor the spectroscopic properties of microparticles, and shifts in the optical signature due to changes in the refractive index of the material within the pore space, is demonstrated.

  10. Detection and recognition of analytes based on their crystallization patterns

    DOEpatents

    Morozov, Victor; Bailey, Charles L.; Vsevolodov, Nikolai N.; Elliott, Adam

    2008-05-06

    The invention contemplates a method for recognition of proteins and other biological molecules by imaging morphology, size and distribution of crystalline and amorphous dry residues in droplets (further referred to as "crystallization pattern") containing predetermined amount of certain crystal-forming organic compounds (reporters) to which protein to be analyzed is added. It has been shown that changes in the crystallization patterns of a number of amino-acids can be used as a "signature" of a protein added. It was also found that both the character of changer in the crystallization patter and the fact of such changes can be used as recognition elements in analysis of protein molecules.

  11. Acoustic detection of ice crystals in Antarctic waters

    NASA Astrophysics Data System (ADS)

    Penrose, John D.; Conde, M.; Pauly, T. J.

    1994-06-01

    During the voyage of the RSV Aurora Australis to the region of Prydz Bay, Antarctica in January-March 1991, ice crystals were encountered at depths from the surface to 125-m in the western area of the bay. On two occasions, crystals were retrieved by netting, and echo sounder records have been used to infer additional regions of occurrence. Acoustic target strength estimates made on the ice crystal assemblies encountered show significant spatial variation, which may relate to crystal size and/or aggregation. Data from a suite of conductivity-temperature-depth casts have been used to map regions of the study area where in situ water temperatures fell below the computed freezing point. Such regions correlate well with those selected on the basis of echogram type and imply that ice crystals occurred at depth over large areas of the bay during the cruise period. The ice crystal distribution described is consistent with that expected from a plume of supercooled water emerging from under the Amery Ice Shelf and forming part of the general circulation of the bay. The magnitude of the supercooled water plume is greater than those reported previously in the Prydz Bay region. If misinterpreted as biota on echo sounder records, ice crystals could significantly bias biomass estimates based on echo integration in this and potentially other areas.

  12. Accurate Optical Detection of Amphiphiles at Liquid-Crystal-Water Interfaces

    NASA Astrophysics Data System (ADS)

    Popov, Piotr; Mann, Elizabeth K.; Jákli, Antal

    2014-04-01

    Liquid-crystal-based biosensors utilize the high sensitivity of liquid-crystal alignment to the presence of amphiphiles adsorbed to one of the liquid-crystal surfaces from water. They offer inexpensive, easy optical detection of biologically relevant molecules such as lipids, proteins, and cells. Present techniques use linear polarizers to analyze the alignment of the liquid crystal. The resulting images contain information not only about the liquid-crystal tilt with respect to the surface normal, the quantity which is controlled by surface adsorption, but also on the uncontrolled in-plane liquid-crystal alignment, thus making the detection largely qualitative. Here we show that detecting the liquid-crystal alignment between circular polarizers, which are only sensitive to the liquid-crystal tilt with respect to the interface normal, makes possible quantitative detection by measuring the transmitted light intensity with a spectrophotometer. Following a new procedure, not only the concentration dependence of the optical path difference but also the film thickness and the effective birefringence can be determined accurately. We also introduce a new "dynamic" mode of sensing, where (instead of the conventional "steady" mode, which detects the concentration dependence of the steady-state texture) we increase the concentration at a constant rate.

  13. Limits in detecting an individual dopant atom embedded in a crystal.

    PubMed

    Mittal, Anudha; Mkhoyan, K Andre

    2011-07-01

    Annular dark field scanning transmission electron microscope (ADF-STEM) images allow detection of individual dopant atoms located on the surface of or inside a crystal. Contrast between intensities of an atomic column containing a dopant atom and a pure atomic column in ADF-STEM image depends strongly on specimen parameters and microscope conditions. Analysis of multislice-based simulations of ADF-STEM images of crystals doped with one substitutional dopant atom for a wide range of crystal thicknesses, types and locations of dopant atom inside the crystal, and crystals with different atoms reveal some interesting trends and non-intuitive behaviours in visibility of the dopant atom. The results provide practical guidelines to determine the optimal microscope and specimen conditions to detect a dopant atom in experiment, obtain information about the 3-d location of a dopant atom, and recognize cases where detecting a single dopant atom is not possible.

  14. Detection of pharmaceutical crystals in polymer particles by transmission electron microscopy

    NASA Astrophysics Data System (ADS)

    Ricarte, Ralm; Hillmyer, Marc; Lodge, Timothy

    2015-03-01

    The use of solid dispersions, blends of an active pharmaceutical ingredient (API) and a polymer excipient, may significantly enhance the dissolution performance of a poorly water soluble drug. However, the polymer's role in inhibiting API crystallization within the solid dispersion is not well understood. One of the main challenges in elucidating this mechanism is the difficulty of detecting small amounts of API crystals (less than 5 volume percent) within the polymer matrix. In this work, we explore the use of transmission electron microscopy (TEM) to characterize the crystallinity of griseofulvin (GF) in hydroxypropyl methylcellulose acetate succinate (HPMCAS) solid dispersions. Using both real-space images and electron diffraction patterns from TEM, GF crystals in the HPMCAS matrix were unambiguously identified with nanometer resolution and with a crystal detection sensitivity superior to both wide-angle X-ray scattering and differential scanning calorimetry. TEM shows great potential for characterizing even trace API crystallinity in solid polymeric dispersions.

  15. Ce-doped single crystal and ceramic garnets for γ ray detection

    SciTech Connect

    Hull, G; Roberts, J; Kuntz, J; Fisher, S; Sanner, R; Tillotson, T; Drobshoff, A; Payne, S; Cherepy, N

    2007-07-30

    Ceramic and single crystal Lutetium Aluminum Garnet scintillators exhibit energy resolution with bialkali photomultiplier tube detection as good as 8.6% at 662 keV. Ceramic fabrication allows production of garnets that cannot easily be grown as single crystals, such as Gadolinium Aluminum Garnet and Terbium Aluminum Garnet. Measured scintillation light yields of Cerium-doped ceramic garnets indicate prospects for high energy resolution.

  16. Application of LiTaO3 pyroelectric crystal for pulsed neutron detection

    NASA Astrophysics Data System (ADS)

    Liang, W. F.; Lu, Y.; Wu, J.; Gao, H.; Li, M.

    2016-08-01

    The feasibility of a LiTaO3 pyroelectric crystal for pulsed neutron detection has been studied. The detector consists of a slice of electroded Z-cut LiTaO3 pyroelectric crystal, and no additional neutron converter is required owing to the Li contained in the crystal. The slight temperature increase caused by neutron radiation will lead to the release of bound charges and will give rise to a pyroelectric signal. The response of it has been studied both theoretically and experimentally. Our preliminary experiment on the CFBR-II reactor suggests that the LiTaO3 pyroelectric detector is promising for high intensity neutron - pulse measurement.

  17. Far-field detection system for laser beam and crystal alignment

    NASA Astrophysics Data System (ADS)

    Zhang, Jiachen; Liu, Daizhong; Zhu, Baoqiang; Tang, Shunxing; Gao, Yanqi

    2016-03-01

    Laser beam far-field alignment as well as frequency-doubling and frequency-tripling crystal adjustment is very important for high-power laser facility. Separate systems for beam and crystal alignment are generally used while the proposed approach by off-axial grating sampling share common optics for these two functions, reducing both space and cost requirements. This detection system has been demonstrated on the National Laser Facility of Israel. The experimental results indicate that the average far-field alignment error is <5% of the spatial filter pinhole diameter, average autocollimation angle error of crystals is <10 μrad, and average frequency-tripling conversion efficiency is 69.3%, which meet the alignment system requirements on the beam direction and crystals.

  18. Two-dimensional photonic crystal sensors for visual detection of lectin concanavalin A.

    PubMed

    Zhang, Jian-Tao; Cai, Zhongyu; Kwak, Daniel H; Liu, Xinyu; Asher, Sanford A

    2014-09-16

    We fabricated a two-dimensional (2-D) photonic crystal lectin sensing material that utilizes light diffraction from a 2-D colloidal array attached to the surface of a hydrogel that contains mannose carbohydrate groups. Lectin-carbohydrate interactions create hydrogel cross-links that shrink the hydrogel volume and decrease the 2-D particle spacing. This mannose containing 2-D photonic crystal sensor detects Concanavalin A (Con A) through shifts in the 2-D diffraction wavelength. Con A concentrations can be determined by measuring the diffracted wavelength or visually determined from the change in the sensor diffraction color. The concentrations are easily monitored by measuring the 2-D array Debye ring diameter. Our observed detection limit for Con A is 0.02 mg/mL (0.7 μM). The 2-D photonic crystal sensors are completely reversible and can monitor Con A solution concentration changes. PMID:25162117

  19. Far-field detection system for laser beams alignment and crystals alignment

    NASA Astrophysics Data System (ADS)

    Liu, D.; Qin, H.; Zhu, B.

    2015-08-01

    Laser beams far-field alignment is very important for the high power laser facility as well as the frequency doubling crystals adjustment. Traditional beams alignment system and crystals alignment system are separated. That means, they use different optical image systems and CCD cameras, which will occupy larger space and use more money. A new farfield detection system of laser beams is presented with a big diffraction grating (37mm*37mm), a set of optical imaging components and a high resolution CCD camera. This detection system, which is fully demonstrated on the National Laser Facility of Israel, can align high power laser facility beams' direction as well as the frequency doubling crystals. The new system occupies small space in the spatial filter through off-axial grating sampling. The experimental results indicate that the average far-field alignment error is less than 5% of spatial filter pinhole diameter, and the average crystals' matching angle error is less than 10urad, which meet the alignment system requirements for beams and crystals.

  20. Sensitive detection of malachite green and crystal violet by nonlinear laser wave mixing and capillary electrophoresis.

    PubMed

    Maxwell, Eric J; Tong, William G

    2016-05-01

    An ultrasensitive label-free antibody-free detection method for malachite green and crystal violet is presented using nonlinear laser wave-mixing spectroscopy and capillary zone electrophoresis. Wave-mixing spectroscopy provides a sensitive absorption-based detection method for trace analytes. This is accomplished by forming dynamic gratings within a sample cell, which diffracts light to create a coherent laser-like signal beam with high optical efficiency and high signal-to-noise ratio. A cubic dependence on laser power and square dependence on analyte concentration make wave mixing sensitive enough to detect molecules in their native form without the use of fluorescent labels for signal enhancement. A 532 nm laser and a 635 nm laser were used for malachite green and crystal violet sample excitation. The use of two lasers of different wavelengths allows the method to simultaneously detect both analytes. Selectivity is obtained through the capillary zone electrophoresis separation, which results in characteristic migration times. Measurement in capillary zone electrophoresis resulted in a limit of detection of 6.9 × 10(-10)M (2.5 × 10(-19) mol) for crystal violet and 8.3 × 10(-11)M (3.0 × 10(-20) mol) for malachite green at S/N of 2.

  1. Sensitive detection of malachite green and crystal violet by nonlinear laser wave mixing and capillary electrophoresis.

    PubMed

    Maxwell, Eric J; Tong, William G

    2016-05-01

    An ultrasensitive label-free antibody-free detection method for malachite green and crystal violet is presented using nonlinear laser wave-mixing spectroscopy and capillary zone electrophoresis. Wave-mixing spectroscopy provides a sensitive absorption-based detection method for trace analytes. This is accomplished by forming dynamic gratings within a sample cell, which diffracts light to create a coherent laser-like signal beam with high optical efficiency and high signal-to-noise ratio. A cubic dependence on laser power and square dependence on analyte concentration make wave mixing sensitive enough to detect molecules in their native form without the use of fluorescent labels for signal enhancement. A 532 nm laser and a 635 nm laser were used for malachite green and crystal violet sample excitation. The use of two lasers of different wavelengths allows the method to simultaneously detect both analytes. Selectivity is obtained through the capillary zone electrophoresis separation, which results in characteristic migration times. Measurement in capillary zone electrophoresis resulted in a limit of detection of 6.9 × 10(-10)M (2.5 × 10(-19) mol) for crystal violet and 8.3 × 10(-11)M (3.0 × 10(-20) mol) for malachite green at S/N of 2. PMID:26998858

  2. X-ray detection capability of a BaCl{sub 2} single crystal scintillator

    SciTech Connect

    Koshimizu, Masanori; Onodera, Kazuya; Asai, Keisuke; Nishikido, Fumihiko; Haruki, Rie; Shibuya, Kengo; Kishimoto, Shunji

    2012-01-15

    The x-ray detection capability of a scintillation detector equipped with a BaCl{sub 2} single crystal was evaluated. The scintillation decay kinetics can be expressed by a sum of two exponential decay components. The fast and slow components have lifetimes of 1.5 and 85 ns, respectively. The total light output is 5% that of YAP:Ce. A subnanosecond timing resolution was obtained. The detection efficiency of a 67.41 keV x-ray is 87% for a detector equipped with a BaCl{sub 2} crystal 6-mm thick. Thus, excellent timing resolution and high detection efficiency can be simultaneously achieved. Additionally, luminescence decay characteristics under vacuum ultraviolet excitation have been investigated. Radiative decay of self-trapped excitons is thought to be responsible for the fast scintillation component.

  3. Detection of single nano-defects in photonic crystals between crossed polarizers.

    PubMed

    Grepstad, Jon Olav; Kaspar, Peter; Johansen, Ib-Rune; Solgaard, Olav; Sudbø, Aasmund

    2013-12-16

    We investigate, by simulations and experiments, the light scattering of small particles trapped in photonic crystal membranes supporting guided resonance modes. Our results show that, due to amplified Rayleigh small particle scattering, such membranes can be utilized to make a sensor that can detect single nano-particles. We have designed a biomolecule sensor that uses cross-polarized excitation and detection for increased sensitivity. Estimated using Rayleigh scattering theory and simulation results, the current fabricated sensor has a detection limit of 26 nm, corresponding to the size of a single virus. The sensor can potentially be made both cheap and compact, to facilitate use at point-of-care.

  4. Electrically detected magnetic resonance signal from iron contaminated Czochralski silicon crystal

    NASA Astrophysics Data System (ADS)

    Mchedlidze, T.; Matsumoto, K.

    1998-04-01

    The electrical detection of magnetic resonance (EDMR) measurement, a detection method for the spin-dependent recombination, was applied to characterize iron contaminated silicon samples grown by the Czochralski method. The observed signal was different than previously reported electron paramagnetic resonance signals from defects in silicon. In addition, as the signal was not detected from similarly contaminated samples prepared from floating zone grown silicon crystal, we propose that the signal originates from defects containing iron and oxygen, namely, from iron decorated oxide precipitates. The dependency of EDMR signal on different experimental conditions (microwave power, illumination intensity, and temperature) were studied.

  5. Development of a biological protocol for endotoxin detection using quartz crystal microbalance (QCM).

    PubMed

    Pérez-Lorenzo, E; Zuzuarregui, A; Arana, S; Mujika, M

    2014-12-01

    In this paper, a biological protocol for endotoxin detection has been developed and optimized by quartz crystal microbalance (QCM). The parameters involved in the formation of the self-assembled monolayer (SAM) have been analyzed, and a study of the pH of the ligand buffer has been performed in order to find the best condition for the ligand immobilization and, in consequence, for the endotoxin detection. The detection limit obtained with the characterized biological protocol corresponds to 1.90 μg/ml. The effectiveness of the optimized biological protocol has been analyzed by cyclic voltammetry analysis. PMID:25183316

  6. Spatially selective photonic crystal enhanced fluorescence and application to background reduction for biomolecule detection assays

    PubMed Central

    Chaudhery, Vikram; Huang, Cheng-Sheng; Pokhriyal, Anusha; Polans, James; Cunningham, Brian T.

    2011-01-01

    By combining photonic crystal label-free biosensor imaging with photonic crystal enhanced fluorescence, it is possible to selectively enhance the fluorescence emission from regions of the PC surface based upon the density of immobilized capture molecules. A label-free image of the capture molecules enables determination of optimal coupling conditions of the laser used for fluorescence imaging of the photonic crystal surface on a pixel-by-pixel basis, allowing maximization of fluorescence enhancement factor from regions incorporating a biomolecule capture spot and minimization of background autofluorescence from areas between capture spots. This capability significantly improves the contrast of enhanced fluorescent images, and when applied to an antibody protein microarray, provides a substantial advantage over conventional fluorescence microscopy. Using the new approach, we demonstrate detection limits as low as 0.97 pg/ml for a representative protein biomarker in buffer. PMID:22109210

  7. Angular spectrum detection instrument for label-free photonic crystal sensors.

    PubMed

    Liu, Longju; Xu, Zhen; Dong, Liang; Lu, Meng

    2014-05-01

    An angular spectrum analysis system was demonstrated to monitor the optical resonant mode of a photonic crystal (PC) sensor comprised of a one-dimensional grating structure. Exposed to solutions with different refractive indices or adsorbed with biomaterials, the PC sensor exhibited changes of the optical resonant modes. The developed detection system utilized a focused laser beam to detect shifts of the resonant angle, and thereby allowed a kinetic analysis of chemical absorption. Such a detection apparatus offers an adjustable angular resolution and a tunable detection range for a wide variety of refractometric sensing applications. A limit of detection of 6.57×10(-5) refractive index unit has been observed. The instrument also offers an imaging capability of rapidly characterizing low-contrast samples deposited on the PC surface with a spatial resolution of 10 μm. PMID:24784094

  8. Distant optical detection of small rotations and displacements by means of chiral liquid crystals

    SciTech Connect

    Shibaev, Petr V. E-mail: shibayev@fordham.edu; Troisi, Juliana; Reddy, Kathryn; Iljin, Andrey

    2014-01-15

    The paper describes novel chiral viscoelastic liquid crystalline mixtures and their application for the detection of small rotational displacements of two plates confining cholesteric liquid crystals (CLC). The mixtures are characterized by extremely high viscosities and stability of the selective reflection band (SRB) at ambient temperatures. Even a small rotation applied to the chiral liquid crystal (CLC) cell results in dramatic changes of the reflective properties of sandwiched CLC films. The angle and direction of rotation as well as the magnitude of CLC's shear deformation can be determined for a variety of experimental geometries, each of which is characterized by its own response function. The proposed model explains changes in the reflection spectra for different experimental geometries and relates them to the angle of rotation and magnitude of shear. The method was tested for a detection of small rotations from a distance of up to 50 m and allows for resolving small rotations of the order of fractions of degrees.

  9. Neutron beam test of barium fluoride crystal for dark matter direct detection

    NASA Astrophysics Data System (ADS)

    Guo, C.; Ma, X. H.; Wang, Z. M.; Bao, J.; Dai, C. J.; Guan, M. Y.; Liu, J. C.; Li, Z. H.; Ren, J.; Ruan, X. C.; Yang, C. G.; Yu, Z. Y.; Zhong, W. L.

    2016-10-01

    In order to test the capabilities of Barium Fluoride (BaF2) crystal for dark matter direct detection, nuclear recoils are studied with mono-energetic neutron beam. The energy spectra of nuclear recoils, quenching factors for elastic scattering neutrons and discrimination capability between neutron inelastic scattering events and γ events are obtained for various recoil energies of the F content in BaF2.

  10. Optical detection of paramagnetic centres: From crystals to glass-ceramics

    NASA Astrophysics Data System (ADS)

    Rogulis, Uldis

    2016-07-01

    An unambiguous attribution of the absorption spectra to definite paramagnetic centres identified by the EPR techniques in the most cases is problematic. This problem may be solved by applying of a direct measurement techniques—the EPR detected via the magnetic circular dichroism, or briefly MCD-EPR. The present survey reports on the advantages and disadvantages applying the MCD-EPR techniques to simple and complex paramagnetic centres in crystals as well as glasses and glass-ceramics.

  11. Handheld imaging photonic crystal biosensor for multiplexed, label-free protein detection

    PubMed Central

    Jahns, Sabrina; Bräu, Marion; Meyer, Björn-Ole; Karrock, Torben; Gutekunst, Sören B.; Blohm, Lars; Selhuber-Unkel, Christine; Buhmann, Raymund; Nazirizadeh, Yousef; Gerken, Martina

    2015-01-01

    We present a handheld biosensor system for the label-free and specific multiplexed detection of several biomarkers employing a spectrometer-free imaging measurement system. A photonic crystal surface functionalized with multiple specific ligands forms the optical transducer. The photonic crystal slab is fabricated on a glass substrate by replicating a periodic grating master stamp with a period of 370 nm into a photoresist via nanoimprint lithography and deposition of a 70-nm titanium dioxide layer. Capture molecules are coupled covalently and drop-wise to the photonic crystal surface. With a simple camera and imaging optics the surface-normal transmission is detected. In the transmission spectrum guided-mode resonances are observed that shift due to protein binding. This shift is observed as an intensity change in the green color channel of the camera. Non-functionalized image sections are used for continuous elimination of background drift. In a first experiment we demonstrate the specific and time-resolved detection of 90.0 nm CD40 ligand antibody, 90.0 nM EGF antibody, and 500 nM streptavidin in parallel on one sensor chip. In a second experiment, aptamers with two different spacer lengths are used as receptor. The binding kinetics with association and dissociation of 250 nM thrombin and regeneration of the sensor surface with acidic tris-HCl-buffer (pH 5.0) is presented for two measurement cycles. PMID:26504624

  12. Handheld imaging photonic crystal biosensor for multiplexed, label-free protein detection.

    PubMed

    Jahns, Sabrina; Bräu, Marion; Meyer, Björn-Ole; Karrock, Torben; Gutekunst, Sören B; Blohm, Lars; Selhuber-Unkel, Christine; Buhmann, Raymund; Nazirizadeh, Yousef; Gerken, Martina

    2015-10-01

    We present a handheld biosensor system for the label-free and specific multiplexed detection of several biomarkers employing a spectrometer-free imaging measurement system. A photonic crystal surface functionalized with multiple specific ligands forms the optical transducer. The photonic crystal slab is fabricated on a glass substrate by replicating a periodic grating master stamp with a period of 370 nm into a photoresist via nanoimprint lithography and deposition of a 70-nm titanium dioxide layer. Capture molecules are coupled covalently and drop-wise to the photonic crystal surface. With a simple camera and imaging optics the surface-normal transmission is detected. In the transmission spectrum guided-mode resonances are observed that shift due to protein binding. This shift is observed as an intensity change in the green color channel of the camera. Non-functionalized image sections are used for continuous elimination of background drift. In a first experiment we demonstrate the specific and time-resolved detection of 90.0 nm CD40 ligand antibody, 90.0 nM EGF antibody, and 500 nM streptavidin in parallel on one sensor chip. In a second experiment, aptamers with two different spacer lengths are used as receptor. The binding kinetics with association and dissociation of 250 nM thrombin and regeneration of the sensor surface with acidic tris-HCl-buffer (pH 5.0) is presented for two measurement cycles. PMID:26504624

  13. Surface-sensitive diamond photonic crystals for high-performance gas detection.

    PubMed

    Blin, C; Han, Z; Girard, H A; Bergonzo, P; Boucaud, P; El Kurdi, M; Saada, S; Sauvage, S; Checoury, X

    2016-09-15

    Diamond slotted photonic crystal (PhC) cavities were fabricated and used for gas detection. They exhibit wavelength sensitivity reaching a 350 nm per unit change of the refractive index of the gaseous environment of the PhC. With a simple oxidized surface termination, diamond PhCs display an ultrahigh sensitivity to the surface adsorption of polar molecules. Gaseous concentrations as low as 80 parts per million (ppm) of hexanol vapor in nitrogen are probed, and a detection limit in the ppm range is inferred, demonstrating a high interest of such devices for trace sensing. PMID:27628397

  14. Liquid crystal-based sensors for selective and quantitative detection of nitrogen dioxide

    PubMed Central

    Sen, Avijit; Kupcho, Kurt A.; Grinwald, Bart A.; VanTreeck, Heidi J.; Acharya, Bharat R.

    2013-01-01

    A highly sensitive nitrogen dioxide (NO2) sensor based on orientational transition of a thin film of liquid crystal (LC) supported on a gold surface is reported. Transport of NO2 molecules through the LC film to the LC-gold interface induces an orientation transition in the LC film. The dynamic behavior of the sensor response exhibits a concentration-dependent response rate that is employed to generate an algorithm for quantitative determination of unknown concentrations. Sensitive, selective and reversible detection with minimal effects of environmental fluctuations suggest that these sensors can be used for quantitative NO2 detection for a number of applications. PMID:23526230

  15. Liquid crystal-based sensors for selective and quantitative detection of nitrogen dioxide.

    PubMed

    Sen, Avijit; Kupcho, Kurt A; Grinwald, Bart A; Vantreeck, Heidi J; Acharya, Bharat R

    2013-03-01

    A highly sensitive nitrogen dioxide (NO2) sensor based on orientational transition of a thin film of liquid crystal (LC) supported on a gold surface is reported. Transport of NO2 molecules through the LC film to the LC-gold interface induces an orientation transition in the LC film. The dynamic behavior of the sensor response exhibits a concentration-dependent response rate that is employed to generate an algorithm for quantitative determination of unknown concentrations. Sensitive, selective and reversible detection with minimal effects of environmental fluctuations suggest that these sensors can be used for quantitative NO2 detection for a number of applications. PMID:23526230

  16. Knee effusion: ultrasound as a useful tool for the detection of calcium pyrophosphate crystals.

    PubMed

    Ruta, Santiago; Catay, Erika; Marin, Josefina; Rosa, Javier; García-Monaco, Ricardo; Soriano, Enrique R

    2016-04-01

    The objective of this study was to evaluate the sensitivity and specificity of ultrasound (US) and conventional radiography (CR) for the detection of calcium pyrophosphate (CPP) crystals in patients with knee effusion. Consecutive patients ≥50 years old with knee effusion were included. All patients underwent arthrocentesis with aspiration of synovial fluid (SF) and subsequent analysis of CPP crystals using plain light and polarizing light microscopy. US and CR of the involved knee were performed immediately after arthrocentesis. CR results were read by an experienced rheumatologist, searching for chondrocalcinosis. US examinations were carried out by an experienced rheumatologist blinded to all clinical and imaging data. The following US abnormal findings were considered indicative of CPP crystals deposition (CPPD): (1) hyperechoic bands within the femoral hyaline cartilage layer, and (2) hyperechoic sparkling spots in meniscal fibrocartilage. A total of 75 knees were evaluated in the same number of patients. Analysis of SF revealed CPP crystals in 15 out of 75 (20 %) knees: all (10) patients with previous diagnosis of CPPD, 3 patients with previous diagnosis of primary knee osteoarthritis (OA) and 2 patients without previous definitive diagnosis of a rheumatic condition. Using SF analysis as reference method, sensitivity and specificity for US findings was 60 and 96.7 %, respectively, while CR showed a sensitivity of 40 % and a specificity of 83.3 %. US results showed high specificity with acceptable sensitivity to detect CPP crystals in patients with knee effusion. Compared with CR, US results had better specificity and sensitivity. US may be used in daily rheumatologic practice when CPPD is suspected.

  17. Detection of DNA targets hybridized to solid surfaces using optical images of liquid crystals.

    PubMed

    Lai, Siok Lian; Tan, Wei Ling; Yang, Kun-Lin

    2011-09-01

    In this paper, we report a method of detecting DNA targets hybridized to a solid surface by using liquid crystals (LC). The detection principle is based on different interference colors of LC supported on surfaces decorated with single-stranded DNA (ssDNA) or double-stranded DNA (dsDNA). However, the contrast between the ssDNA and dsDNA is not obvious, unless DNA-streptavidin complexes are introduced to the dsDNA to increase the surface mass density. Two different approaches of introducing streptavidin to the system are studied and compared. We find that by premixing the biotin-labeled DNA targets with streptavidin prior to the DNA hybridization, branched-streptavidin complexes are formed and clear LC signal can be observed. This LC-based DNA detection principle represents an important step toward the development of a simple, instrument- and fluorophore-free DNA detection method.

  18. Bio-inspired photonic-crystal microchip for fluorescent ultratrace detection.

    PubMed

    Hou, Jue; Zhang, Huacheng; Yang, Qiang; Li, Mingzhu; Song, Yanlin; Jiang, Lei

    2014-06-01

    Ultratrace detection attracts great interest because it is still a challenge to the early diagnosis and drug testing. Enriching the targets from highly diluted solutions to the sensitive area is a promising method. Inspired by the fog-collecting structure on Stenocara beetle's back, a photonic-crystal (PC) microchip with hydrophilic-hydrophobic micropattern was fabricated by inkjet printing. This device was used to realize high-sensitive ultratrace detection of fluorescence analytes and fluorophore-based assays. Coupled with the fluorescence enhancement effect of a PC, detection down to 10(-16) mol L(-1) was achieved. This design can be combined with biophotonic devices for the detection of drugs, diseases, and pollutions of the ecosystem.

  19. Linear viscoelasticity of hard sphere colloidal crystals from resonance detected with dynamic light scattering

    NASA Astrophysics Data System (ADS)

    Phan, See-Eng; Li, Min; Russel, William B.; Zhu, Jixiang; Chaikin, Paul M.; Lant, Chris T.

    1999-08-01

    We present measurements of the high-frequency shear modulus and dynamic viscosity for nonaqueous hard sphere colloidal crystals both in normal and microgravity environments. All experiments were performed on a multipurpose PHaSE instrument. For the rheological measurements, we detect the resonant response to oscillatory forcing with a dynamic light scattering scheme. The resonant response for colloidal crystals formed in normal and microgravity environments was similar, indicating that the bulk rheological properties are unaffected by differing crystal structure and crystallite size within the experimental error. Our high-frequency shear modulus seems reasonable, lying close to Frenkel and Ladd's predictions [Phys. Rev. Lett. 59, 1169 (1987)] for the static modulus of hard sphere crystals. Our high-frequency dynamic viscosity, on the other hand, seems high, exceeding Shikata and Pearson [J. Rheol. 38, 601 (1994)] and van der Werff et al.'s measurements [Phys. Rev. A 39, 795 (1989)] on the high-frequency dynamic viscosity for metastable fluids. The measurements are in the linear regime for the shear modulus but may not be for the dynamic viscosity as Frith et al. [Powder Technol. 51, 27 (1987)] report that the dynamic viscosity passes through a maximum with strain amplitude.

  20. A chromogenic limulus test for detection of microbes that decreases the laser damage threshold of potassium dihydrogen phosphate crystals

    NASA Astrophysics Data System (ADS)

    Yokotani, A.; Nishida, Y.; Fujioka, K.; Sasaki, T.; Yamanaka, T.; Yamanaka, C.

    1987-05-01

    The chromogenic limulus test has been applied for the first time to detect an organic impurity contained in potassium dihydrogen phosphate (KDP) crystals. Impurities arise from microbes present during crystal growth, and are responsible for a reduced laser damage threshold. A sensitivity of 10 pg/g KDP (10-5 ppm) was achieved, provided that the KDP solution was neutralized to ˜pH 7. Endotoxin content in the prismatic region of KDP crystals grown in a microbe-rich solution was approximately 100 pg/g KDP. The presence of an organic material in seemingly perfect KDP crystals could be experimentally confirmed.

  1. An immuno-biosensor system based on quartz crystal microbalance for avian influenza virus detection

    NASA Astrophysics Data System (ADS)

    Liu, Shengping; Chen, Guoming; Zhou, Qi; Wei, Yunlong

    2007-12-01

    For the quick detection of Avian Influenza Virus (AIV), a biosensor based on Quartz Crystal Microbalance (QCM) was fabricated according to the specific bonding principle between antibody and antigen. Staphylococcal Protein A (SPA) was extracted from Staphylococcus and purified. Then SPA was coated on the surface of QCM for immobilizing AIV monoclonal antibodies. The use of AIV monoclonal antibody could enhance the specificity of the immuno-biosensor. A multi-channel piezoelectricity detection system for the immuno-biosensor was developed. The system can work for the quick detection of AIV antigen in the case of the entirely aqueous status owe to one special oscillating circuit designed in this work. The optimum conditions of SPA coating and AIV monoclonal antibody immobilization were investigated utilizing the multi-channel detection system. The preliminary application of the immuno-biosensor system for detection of AIV was evaluated. Results indicate that the immuno-biosensor system can detect the AIV antigens with a linear range of 3-200ng/ml. The system can accomplish the detection of AIV antigens around 40 minutes.

  2. Direct molecule-specific glucose detection by Raman spectroscopy based on photonic crystal fiber.

    PubMed

    Yang, Xuan; Zhang, Alissa Y; Wheeler, Damon A; Bond, Tiziana C; Gu, Claire; Li, Yat

    2012-01-01

    This paper reports the first step toward the development of a glucose biosensor based on Raman spectroscopy and a photonic crystal fiber (PCF) probe. Historically, it has been very challenging to detect glucose directly by Raman spectroscopy due to its inherently small Raman scattering cross-section. In this work, we report the first quantitative glucose Raman detection in the physiological concentration range (0-25 mM) with a low laser power (2 mW), a short integration time (30 s), and an extremely small sampling volume (~50 nL) using the highly sensitive liquid-filled PCF probe. As a proof of concept, we also demonstrate the molecular specificity of this technique in the presence of a competing sugar, such as fructose. High sensitivity, flexibility, reproducibility, low cost, small sampling volume, and in situ remote sensing capability make PCF a very powerful platform for potential glucose detection based on Raman spectroscopy. PMID:22120042

  3. Amplification of interference color by using liquid crystal for protein detection

    NASA Astrophysics Data System (ADS)

    Zhu, Qingdi; Yang, Kun-Lin

    2013-12-01

    Micrometer-sized, periodic protein lines printed on a solid surface cause interference color which is invisible to the naked eye. However, the interference color can be amplified by using a thin layer of liquid crystal (LC) covered on the surface to form a phase diffraction grating. Strong interference color can thus be observed under ambient light. By using the LC-amplified interference color, we demonstrate naked-eye detection of a model protein—immunoglobulin G (IgG). Limit of detection can reach 20 μg/ml of IgG without using any instrumentation. This detection method is potentially useful for the development of low-cost and portable biosensors.

  4. Amplification of interference color by using liquid crystal for protein detection

    SciTech Connect

    Zhu, Qingdi; Yang, Kun-Lin

    2013-12-09

    Micrometer-sized, periodic protein lines printed on a solid surface cause interference color which is invisible to the naked eye. However, the interference color can be amplified by using a thin layer of liquid crystal (LC) covered on the surface to form a phase diffraction grating. Strong interference color can thus be observed under ambient light. By using the LC-amplified interference color, we demonstrate naked-eye detection of a model protein—immunoglobulin G (IgG). Limit of detection can reach 20 μg/ml of IgG without using any instrumentation. This detection method is potentially useful for the development of low-cost and portable biosensors.

  5. Detection of calcium phosphate crystals in the joint fluid of patients with osteoarthritis – analytical approaches and challenges

    PubMed Central

    Yavorskyy, Alexander; Hernandez-Santana, Aaron; McCarthy, Geraldine

    2008-01-01

    Clinically, osteoarthritis (OA) is characterised by joint pain, stiffness after immobility, limitation of movement and, in many cases, the presence of basic calcium phosphate (BCP) crystals in the joint fluid. The detection of BCP crystals in the synovial fluid of patients with OA is fraught with challenges due to the submicroscopic size of BCP, the complex nature of the matrix in which they are found and the fact that other crystals can co-exist with them in cases of mixed pathology. Routine analysis of joint crystals still relies almost exclusively on the use of optical microscopy, which has limited applicability for BCP crystal identification due to limited resolution and the inherent subjectivity of the technique. The purpose of this Critical Review is to present an overview of some of the main analytical tools employed in the detection of BCP to date and the potential of emerging technologies such as atomic force microscopy (AFM) and Raman microspectroscopy for this purpose. PMID:18299743

  6. Molecular imprinted photonic crystal hydrogels for the rapid and label-free detection of imidacloprid.

    PubMed

    Wang, Xuan; Mu, Zhongde; Liu, Ran; Pu, Yuepu; Yin, Lihong

    2013-12-15

    A novel sensor for the rapid and label-free detection of imidacloprid was developed based on the combination of a colloidal crystal templating method and a molecular imprinting technique. The molecular imprinted photonic hydrogel film was prepared with methacrylic acid as monomers, ethylene glycol dimethylacrylate as cross-linkers and imidacloprid as imprinting template molecules. When the colloidal crystal template and the molecularly imprinted template was removed, the resulted MIPH film possessed a highly ordered three-dimensional macroporous structure with nanocavities. The response of the MIPH film to imidacloprid in aqueous solution can be detected through a readable Bragg diffraction red shift. When the concentration of imidacloprid increased from 10(-13) to 10(-7) g/mL, the Bragg diffraction peak shifted from 551 to 589 nm, while there were no obvious peak shifts for thiamethoxam and acetamiprid. This sensor which comprises of no label techniques and expensive instruments has potential application for the detection of trace imidacloprid. PMID:23993570

  7. Quartz crystal microbalance (QCM) as biosensor for the detecting of Escherichia coli O157:H7

    NASA Astrophysics Data System (ADS)

    Thanh Ngo, Vo Ke; Giang Nguyen, Dang; Phuong Uyen Nguyen, Hoang; Tran, Van Man; Nguyen, Thi Khoa My; Phat Huynh, Trong; Lam, Quang Vinh; Dat Huynh, Thanh; Truong, Thi Ngoc Lien

    2014-12-01

    Although Escherichia coli (E. coli) is a commensalism organism in the intestine of humans and warm-blooded animals, it can be toxic at higher density and causes diseases, especially the highly toxic E. coli O157:H7. In this paper a quartz crystal microbalance (QCM) biosensor was developed for the detection of E. coli O157:H7 bacteria. The anti-E. coli O157:H7 antibodies were immobilized on a self-assembly monolayer (SAM) modified 5 MHz AT-cut quartz crystal resonator. The SAMs were activated with 16-mercaptopropanoic acid, in the presence of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and ester N-hydroxysuccinimide (NHS). The result of changing frequency due to the adsorption of E. coli O157:H7 was measured by the QCM biosensor system designed and fabricated by ICDREC-VNUHCM. This system gave good results in the range of 102-107 CFU mL-1 E. coli O157:H7. The time of bacteria E. coli O157:H7 detection in the sample was about 50 m. Besides, QCM biosensor from SAM method was comparable to protein A method-based piezoelectric immunosensor in terms of the amount of immobilized antibodies and detection sensitivity.

  8. Detection of anthrax lef with DNA-based photonic crystal sensors

    NASA Astrophysics Data System (ADS)

    Zhang, Bailin; Dallo, Shatha; Peterson, Ralph; Hussain, Syed; Weitao, Tao; Ye, Jing Yong

    2011-12-01

    Bacillus anthracis has posed a threat of becoming biological weapons of mass destruction due to its virulence factors encoded by the plasmid-borne genes, such as lef for lethal factor. We report the development of a fast and sensitive anthrax DNA biosensor based on a photonic crystal structure used in a total-internal-reflection configuration. For the detection of the lef gene, a single-stranded DNA lef probe was biotinylated and immobilized onto the sensor via biotin-streptavidin interactions. A positive control, lef-com, was the complementary strand of the probe, while a negative control was an unrelated single-stranded DNA fragment from the 16S rRNA gene of Acinetobacter baumannii. After addition of the biotinylated lef probe onto the sensor, significant changes in the resonance wavelength of the sensor were observed, resulting from binding of the probe to streptavidin on the sensor. The addition of lef-com led to another significant increase as a result of hybridization between the two DNA strands. The detection sensitivity for the target DNA reached as low as 0.1 nM. In contrast, adding the unrelated DNAs did not cause an obvious shift in the resonant wavelength. These results demonstrate that detection of the anthrax lef by the photonic crystal structure in a total-internal-reflection sensor is highly specific and sensitive.

  9. Real-Time Biomolecular Binding Detection Using a Sensitive Photonic Crystal Biosensor

    PubMed Central

    Guo, Yunbo; Ye, Jing Yong; Divin, Charles; Huang, Baohua; Thomas, Thommey P.; Baker, James R.; Norris, Theodore B.

    2010-01-01

    Real-time measurement of specific biomolecular interactions is critical to many areas of biological research. A number of label-free techniques for directly monitoring biomolecular binding have been developed, but it is still challenging to measure the binding kinetics of very small molecules, to detect low concentrations of analyte molecules, or to detect low affinity interactions. In this study, we report the development of a highly sensitive photonic crystal biosensor for label-free, real-time biomolecular binding analysis. We characterize the performance of this biosensor using a standard streptavidin-biotin binding system. Optimization of the surface functionalization methods for streptavidin immobilization on the silica sensing surface is presented, and the specific binding of biotinylated analyte molecules ranging over 3 orders of magnitude in molecular weight, including very small molecules (<250 Da), DNA oligonucleotides, proteins, and antibodies (>150 000 Da), are detected in real time with a high signal-to-noise ratio. Finally, we document the sensor efficiency for low mass adsorption, as well as multilayered molecular interactions. By all important metrics for sensitivity, we anticipate this photonic crystal biosensor will provide new capabilities for highly sensitive measurements of biomolecular binding. PMID:20486666

  10. Multiplexed Cancer Biomarker Detection Using Quartz-based Photonic Crystal Surfaces

    SciTech Connect

    Huang, Cheng-Sheng; Chaudhey, Vikram; Pokhriyal, A.; George, Sherine; Polans, James; Lu, Meng; Tan, Ruimin; Zangar, Richard C.; Cunningham, Brian T.

    2013-01-17

    A photonic crystal (PC) surface is demonstrated as a high-sensitivity platform for detection of a panel of 21 cancer biomarker antigens using a sandwich enzyme-linked immunosorbent assay (ELISA) microarray format. A quartz-based PC structure fabricated by nanoimprint lithography, selected for its low autofluorescence, supports two independent optical resonances that simultaneously enable enhancement of fluorescence detection of biomarkers and label-free quantification of the density of antibody capture spots. A detection instrument is demonstrated that supports fluorescence and label-free imaging modalities, with the ability to optimize the fluorescence enhancement factor on a pixel-by-pixel basis throughout the microarray using an angle-scanning approach for the excitation laser that automatically compensates for variability in surface chemistry density and capture spot density. Measurements show that the angle-scanning illumination approach reduces the coefficient of variation of replicate assays by 20–99% compared to ordinary fluorescence microscopy, thus supporting reduction in limits of detectable biomarker concentration. Using the PC resonance, biomarkers in mixed samples were detectable at the lowest concentrations tested (2.1–41 pg/mL), resulting in a three-log range of quantitative detection.

  11. High-sensitivity photonic crystal fiber interferometer for chemical vapors detection

    NASA Astrophysics Data System (ADS)

    Villatoro, Joel; Kreuzer, Mark P.; Jha, Rajan; Minkovich, Vladimir P.; Finazzi, Vittoria; Badenes, Gonçal; Pruneri, Valerio

    2009-05-01

    We report an in-reflection photonic crystal fiber (PCF) interferometer which exhibits high sensitivity to different volatile organic compounds (VOCs), without the need of any permeable material. The interferometer is compact, robust, and consists of a stub of PCF spliced to standard optical fiber. In the splice the voids of the PCF are fully collapsed, thus allowing the excitation and recombination of two core modes. The device reflection spectrum exhibits very regular interference pattern which shifts differently when the voids of the PCF are infiltrated with VOC molecules. The volume of voids responsible for the shift is around 500 picoliters whereas the detectable levels are in the nanomole range.

  12. Polymer-based Photonic Crystal Cavity Sensor for Optical Detection in the Visible Wavelength Region.

    PubMed

    Maeno, Kenichi; Aki, Shoma; Sueyoshi, Kenji; Hisamoto, Hideaki; Endo, Tatsuro

    2016-01-01

    In this study, a polymer-based two-dimensional photonic crystal (PhC) cavity for visible-light-based optical-sensing applications was designed and fabricated for the first time. The PhC cavity configuration was designed to operate at 650 nm, and fabricated with a polymer (resist) on a silicon substrate using electron-beam lithography. For investigating sensing applications based on shifting of condition exhibiting a photonic bandgap (PBG), the polymer monolayer deposition (layer-by-layer method) was monitored as the light-intensity change at the cavity position. Consequently, the monolayer-level detection of polyions was achieved. PMID:26753717

  13. Fabrication of liquid crystal based sensor for detection of hydrazine vapours

    NASA Astrophysics Data System (ADS)

    Nandi, Rajib; Singh, Sachin Kumar; Singh, Hemant Kumar; Singh, Bachcha; Singh, Ranjan K.

    2014-10-01

    A novel liquid crystal (LC) based sensor to detect trace level amount of hydrazine vapour has been developed. The LC 4‧-pentyl-4-biphenylcarbonitrile (5CB) doped with 0.5 wt% 4-decyloxy benzaldehyde (DBA) shows dark to bright optical texture upon exposure of hydrazine vapours as revealed by polarizing optical microscopy under crossed polarizers. The hydrazine interacts with the doped DBA and form diimine compound which disrupt the orientation of aligned 5CB. The interaction between DBA and hydrazine has been also studied by Raman spectroscopy.

  14. Ultrafast state detection and 2D ion crystals in a Paul trap

    NASA Astrophysics Data System (ADS)

    Ip, Michael; Ransford, Anthony; Campbell, Wesley

    2016-05-01

    Projective readout of quantum information stored in atomic qubits typically uses state-dependent CW laser-induced fluorescence. This method requires an often sophisticated imaging system to spatially filter out the background CW laser light. We present an alternative approach that instead uses simple pulse sequences from a mode-locked laser to affect the same state-dependent excitations in less than 1 ns. The resulting atomic fluorescence occurs in the dark, allowing the placement of non-imaging detectors right next to the atom to improve the qubit state detection efficiency and speed. We also study 2D Coulomb crystals of atomic ions in an oblate Paul trap. We find that crystals with hundreds of ions can be held in the trap, potentially offering an alternative to the use of Penning traps for the quantum simulation of 2D lattice spin models. We discuss the classical physics of these crystals and the metastable states that are supported in 2D. This work is supported by the US Army Research Office.

  15. Applications of metal ions and liquid crystals for multiplex detection of DNA.

    PubMed

    Liu, Yanyang; Yang, Kun-Lin

    2015-02-01

    Many cations such as sodium ions have strong influence on anchoring behaviors of liquid crystals (LC). Since DNA is negatively charged and forms complex with metal ions, it is possible to form DNA/metal ions complex on surfaces to disrupt orientations of LC. This phenomenon is used to establish a principle for detecting surface immobilized DNA by using LC. In contrast, peptide nucleic acid (PNA) is electroneutral. It does not complex with metal ions or affect the orientations of LC. Therefore, PNA can be used as a probe to hybridize with specific DNA with a unique sequence, and the principle mentioned above can be used to detect the DNA target by using metal ions and LC. Based on this method, a 600bp DNA target in buffer can be detected with a limit of detection at 10fM. Unlike other fluorescence-based DNA assays, this LC-based detection method does not require labeling of DNA, and the test result can be viewed with the naked eye under a polarized microscope.

  16. A liquid crystal-based sensor for the simple and sensitive detection of cellulase and cysteine.

    PubMed

    Wang, Yi; Hu, Qiongzheng; Tian, Tongtong; Gao, Yan'an; Yu, Li

    2016-11-01

    A liquid crystal (LC)-based sensor, which is capable of monitoring enzymatic activity at the aqueous/LC interface and detecting cellulase and cysteine (Cys), was herein reported. When functionalized with a surfactant, dodecyl β-d-glucopyranoside, the 4-cyano-4'-pentylbiphenyl (5CB) displays a dark-to-bright transition in the optical appearance for cellulase. We attribute this change to the orientational transition of LCs, as a result of enzymatic hydrolysis between cellulase and surfactant. Furthermore, by adding cellulase and Cu(2+), our surfactant-LCs system performs an interesting ability to detect Cys, even though Cys could not interact with surfactant or LC directly. Alternatively, through the strong binding between Cys and Cu(2+), cellulase was able to hydrolyze surfactant in the presence of Cu(2+), leading to the transition of LCs from dark to bright. The detection limit of the LC sensor was around 1×10(-5)mg/mL and 82.5μM for cellulase and Cys, respectively. The LC-based sensor may contribute to the development of low-cost, expedient, and label-free detection for cellulase and Cys and the design strategy may also provide a novel way for detecting multiple analytes.

  17. Antibody-free detection of human chorionic gonadotropin by use of liquid crystals.

    PubMed

    Ding, Xiaokang; Yang, Kun-Lin

    2013-11-19

    Human chorionic gonadotropin (hCG) is an important biomarker for the diagnosis of pregnancy and cancers. In this study, we report an antibody-free and label-free mechanism for detecting hCG. To replace enzyme-labeled antibodies, we use a short oligopeptide as an hCG receptor to bind hCG. The short oligopeptide sequence, (N-)PPLRINRHILTR(-C), is identified after 5 rounds of screening by use of a phage library. After binding, liquid crystal (LC) is used to transduce the binding event into optical signals. The captured hCG can disrupt a thin layer (~6 μm) of LC covered on the surface. Depending on the initial concentration of hCG, LC gives distinct optical signals visible to the naked eye. The limit of detection (LOD) for this method is approximately 1 IU/mL (2 nM) in both phosphate-buffered saline and urine samples, and only 0.6 μL of hCG solution is required. This means that as little as 45.5 pg of hCG can be detected by this method. Compared to other detection methods for hCG, this detection method does not require the use of antibody and is label-free. It has the potential to become a portable diagnostic kit for hCG. PMID:24147645

  18. Desalting by crystallization: detection of attomole biomolecules in picoliter buffers by mass spectrometry.

    PubMed

    Gong, Xiaoyun; Xiong, Xingchuang; Wang, Song; Li, Yanyan; Zhang, Sichun; Fang, Xiang; Zhang, Xinrong

    2015-10-01

    Sensitive detection of biomolecules in small-volume samples by mass spectrometry is, in many cases, challenging because of the use of buffers to maintain the biological activities of proteins and cells. Here, we report a highly effective desalting method for picoliter samples. It was based on the spontaneous separation of biomolecules from salts during crystallization of the salts. After desalting, the biomolecules were deposited in the tip of the quartz pipet because of the evaporation of the solvent. Subsequent detection of the separated biomolecules was achieved using solvent assisted electric field induced desorption/ionization (SAEFIDI) coupled with mass spectrometry. It allowed for direct desorption/ionization of the biomolecules in situ from the tip of the pipet. The organic component in the assistant solvent inhibited the desorption/ionization of salts, thus assured successful detection of biomolecules. Proteins and peptides down to 50 amol were successfully detected using our method even if there were 3 × 10(5) folds more amount of salts in the sample. The concentration and ion species of the salts had little influence on the detection results.

  19. A liquid crystal-based sensor for the simple and sensitive detection of cellulase and cysteine.

    PubMed

    Wang, Yi; Hu, Qiongzheng; Tian, Tongtong; Gao, Yan'an; Yu, Li

    2016-11-01

    A liquid crystal (LC)-based sensor, which is capable of monitoring enzymatic activity at the aqueous/LC interface and detecting cellulase and cysteine (Cys), was herein reported. When functionalized with a surfactant, dodecyl β-d-glucopyranoside, the 4-cyano-4'-pentylbiphenyl (5CB) displays a dark-to-bright transition in the optical appearance for cellulase. We attribute this change to the orientational transition of LCs, as a result of enzymatic hydrolysis between cellulase and surfactant. Furthermore, by adding cellulase and Cu(2+), our surfactant-LCs system performs an interesting ability to detect Cys, even though Cys could not interact with surfactant or LC directly. Alternatively, through the strong binding between Cys and Cu(2+), cellulase was able to hydrolyze surfactant in the presence of Cu(2+), leading to the transition of LCs from dark to bright. The detection limit of the LC sensor was around 1×10(-5)mg/mL and 82.5μM for cellulase and Cys, respectively. The LC-based sensor may contribute to the development of low-cost, expedient, and label-free detection for cellulase and Cys and the design strategy may also provide a novel way for detecting multiple analytes. PMID:27497931

  20. Detection of amino acid neurotransmitters by surface enhanced Raman scattering and hollow core photonic crystal fiber

    NASA Astrophysics Data System (ADS)

    Tiwari, Vidhu S.; Khetani, Altaf; Monfared, Ali Momenpour T.; Smith, Brett; Anis, Hanan; Trudeau, Vance L.

    2012-03-01

    The present work explores the feasibility of using surface enhanced Raman scattering (SERS) for detecting the neurotransmitters such as glutamate (GLU) and gamma-amino butyric acid (GABA). These amino acid neurotransmitters that respectively mediate fast excitatory and inhibitory neurotransmission in the brain, are important for neuroendocrine control, and upsets in their synthesis are also linked to epilepsy. Our SERS-based detection scheme enabled the detection of low amounts of GLU (10-7 M) and GABA (10-4 M). It may complement existing techniques for characterizing such kinds of neurotransmitters that include high-performance liquid chromatography (HPLC) or mass spectrography (MS). This is mainly because SERS has other advantages such as ease of sample preparation, molecular specificity and sensitivity, thus making it potentially applicable to characterization of experimental brain extracts or clinical diagnostic samples of cerebrospinal fluid and saliva. Using hollow core photonic crystal fiber (HC-PCF) further enhanced the Raman signal relative to that in a standard cuvette providing sensitive detection of GLU and GABA in micro-litre volume of aqueous solutions.

  1. A novel opal closest-packing photonic crystal for naked-eye glucose detection.

    PubMed

    Hong, Xiaodi; Peng, Yuan; Bai, Jialei; Ning, Baoan; Liu, Yuanyuan; Zhou, Zhijiang; Gao, Zhixian

    2014-04-01

    A novel opal closest-packing (OCP) photonic crystal (PC) is successfully prepared for naked-eye glucose detection. This PC is fabricated via a vertical convective self-assembly method with a new type of monodisperse microsphere polymerized by co-monomers, namely, methyl methacrylate (MMA), N-isopropylacrylamide (NIPA), and 3-acrylamidophenylboronic acid (AAPBA). The OCP PC has high stability and periodically-ordered structure, showing the desired structural color. The proposed PC material displays a red shift and reduced reflection intensity when detecting glucose molecules. The red-shift wavelength reaches 75 nm, which clearly changes the structural color from brilliant blue to emerald green. This visually distinguishable color change facilitates the detection of the glucose concentrations from 3 to 20 mm, which demonstrates the potential of the opal PC material for naked-eye detection. Thus, the novel PMMA–NIPA–AAPBA OCP PC is a simply prepared and sensitive material, which shows promising use in the diagnosis of diabetes mellitus and in real-time monitoring of diabetes. Different types of appropriated recognition groups are expected to be introduced into the 3D OCP PC to form new functional materials or chemical sensors, which will extensively broaden the PC material application. PMID:24829962

  2. Spherical porphyrin sensor array based on encoded colloidal crystal beads for VOC vapor detection.

    PubMed

    Xu, Hua; Cao, Kai-Di; Ding, Hai-Bo; Zhong, Qi-Feng; Gu, Hong-Cheng; Xie, Zhuo-Ying; Zhao, Yuan-Jin; Gu, Zhong-Ze

    2012-12-01

    A spherical porphyrin sensor array using colloidal crystal beads (CCBs) as the encoding microcarriers has been developed for VOC vapor detection. Six different porphyrins were coated onto the CCBs with distinctive encoded reflection peaks via physical adsorption and the sensor array was fabricated by placing the prepared porphyrin-modified CCBs together. The change in fluorescence color of the porphyrin-modified CCBs array serves as the detection signal for discriminating between different VOC vapors and the reflection peak of the CCBs serves as the encoding signal to distinguish between different sensors. It was demonstrated that the VOC vapors detection using the prepared sensor array showed excellent discrimination: not only could the compounds from the different chemical classes be easily differentiated (e.g., alcohol vs acids vs ketones) but similar compounds from the same chemical family (e.g., methanol vs ethanol) and the same compound with different concentration ((e.g., Sat. ethanol vs 60 ppm ethanol vs 10 ppm ethanol) could also be distinguished. The detection reproducibility and the humidity effect were also investigated. The present spherical sensor array, with its simple preparation, rapid response, high sensitivity, reproducibility, and humidity insensitivity, and especially with stable and high-throughput encoding, is promising for real applications in artificial olfactory systems. PMID:23163575

  3. A novel opal closest-packing photonic crystal for naked-eye glucose detection.

    PubMed

    Hong, Xiaodi; Peng, Yuan; Bai, Jialei; Ning, Baoan; Liu, Yuanyuan; Zhou, Zhijiang; Gao, Zhixian

    2014-04-01

    A novel opal closest-packing (OCP) photonic crystal (PC) is successfully prepared for naked-eye glucose detection. This PC is fabricated via a vertical convective self-assembly method with a new type of monodisperse microsphere polymerized by co-monomers, namely, methyl methacrylate (MMA), N-isopropylacrylamide (NIPA), and 3-acrylamidophenylboronic acid (AAPBA). The OCP PC has high stability and periodically-ordered structure, showing the desired structural color. The proposed PC material displays a red shift and reduced reflection intensity when detecting glucose molecules. The red-shift wavelength reaches 75 nm, which clearly changes the structural color from brilliant blue to emerald green. This visually distinguishable color change facilitates the detection of the glucose concentrations from 3 to 20 mm, which demonstrates the potential of the opal PC material for naked-eye detection. Thus, the novel PMMA–NIPA–AAPBA OCP PC is a simply prepared and sensitive material, which shows promising use in the diagnosis of diabetes mellitus and in real-time monitoring of diabetes. Different types of appropriated recognition groups are expected to be introduced into the 3D OCP PC to form new functional materials or chemical sensors, which will extensively broaden the PC material application.

  4. A Label-Free Immunosensor for Ultrasensitive Detection of Ketamine Based on Quartz Crystal Microbalance

    PubMed Central

    Yang, Ya; Tu, Yifeng; Wang, Xiaoshu; Pan, Jinyin; Ding, Yun

    2015-01-01

    In this study, we have developed a label-free immunosensor with the variation of resonance frequency (Δf) of a quartz crystal microbalance (QCM) as readout signal for ultrasensitive detection of Ketamine (KT). An optimized strategy for immobilization of KT antibody on the surface of the QCM chip was implemented via the self-assembly modification of 3-mercaptopropionic acid, and then activated with 1-ethyl-3- (3-dimethylaminoprophl) carbodiimide and n-hydroxysuccinimide. The specific affinity between the antibody and the antigen ensured a selective response toward KT. The Δf linearly related to the concentration of KT in the range of 1 to 40 pg/mL, with a detection limit of 0.86 pg/mL (S/N = 3). The obtained immunosensor was applied to detect the KT in spiked human urine without any pretreatment but dilution with recoveries from 91.8% to 108%. The developed sensor is promising to perform the portable or on-spot KT detection in clinic or forensic cases. PMID:25871722

  5. Detecting, visualizing, and measuring gold nanoparticle chirality using helical pitch measurements in nematic liquid crystal phases.

    PubMed

    Sharma, Anshul; Mori, Taizo; Lee, Huey-Charn; Worden, Matthew; Bidwell, Eric; Hegmann, Torsten

    2014-12-23

    Chirality at the nanoscale, or more precisely, the chirality or chiroptical effects of chiral ligand-capped metal nanoparticles (NPs) is an intriguing and rapidly evolving field in nanomaterial research with promising applications in catalysis, metamaterials, and chiral sensing. The aim of this work was to seek out a system that not only allows the detection and understanding of NP chirality but also permits visualization of the extent of chirality transfer to a surrounding medium. The nematic liquid crystal phase is an ideal candidate, displaying characteristic defect texture changes upon doping with chiral additives. To test this, we synthesized chiral cholesterol-capped gold NPs and prepared well-dispersed mixtures in two nematic liquid crystal hosts. Induced circular dichroism spectropolarimetry and polarized light optical microscopy revealed that all three gold NPs induce chiral nematic phases, and that those synthesized in the presence of a chiral bias (disulfide) are more powerful chiral inducers than those where the NP was formed in the absence of a chiral bias (prepared by conjugation of a chiral silane to preformed NPs). Helical pitch data here visually show a clear dependence on the NP size and the number of chiral ligands bound to the NP surface, thereby supporting earlier experimental and theoretical data that smaller metal NPs made in the presence of a chiral bias are stronger chiral inducers.

  6. Equilibrium Liquid Crystal Phase Diagrams and Detection of Kinetic Arrest in Cellulose Nanocrystal Suspensions

    NASA Astrophysics Data System (ADS)

    Honorato Rios, Camila; Kuhnhold, Anja; Bruckner, Johanna; Dannert, Rick; Schilling, Tanja; Lagerwall, Jan

    2016-05-01

    The cholesteric liquid crystal self-assembly of water-suspended cellulose nanocrystal (CNC) into a helical arrangement was observed already more than 20 years ago and the phenomenon was used to produce iridescent solid films by evaporating the solvent or via sol-gel processing. Yet it remains challenging to produce optically uniform films and to control the pitch reproducibly, reflecting the complexity of the three-stage drying process that is followed in preparing the films. An equilibrium liquid crystal phase formation stage is followed by a non-equilibrium kinetic arrest, which in turn is followed by structural collapse as the remaining solvent is evaporated. Here we focus on the first of these stages, combining a set of systematic rheology and polarizing optics experiments with computer simulations to establish a detailed phase diagram of aqueous CNC suspensions with two different values of the surface charge, up to the concentration where kinetic arrest sets in. We also study the effect of varying ionic strength of the solvent. Within the cholesteric phase regime, we measure the equilibrium helical pitch as a function of the same parameters. We report a hitherto unnoticed change in character of the isotropic-cholesteric transition at increasing ionic strength, with a continuous weakening of the first-order character up to the point where phase coexistence is difficult to detect macroscopically due to substantial critical fluctuations.

  7. Label-free Detection of Cardiac Troponin I with a Photonic Crystal Biosensor

    PubMed Central

    Zhang, Bailin; Morales, Andres W.; Peterson, Ralph; Tang, Liang; Ye, Jing Yong

    2014-01-01

    A biosensor has been developed with a photonic crystal structure used in a total-internal-reflection (PC-TIR) configuration for label-free detection of a cardiac biomarker: Troponin I (cTnI). In contrast to a conventional optical microcavity that has a closed structure with its cavity layer sandwiched between two high-reflection surfaces, the PC-TIR configuration creates a unique open microcavity, which allows its cavity layer (sensing layer) to be easily functionalized and directly exposed to analyte molecules for bioassays. In this study, a PC-TIR sensor has been used for the label-free measurements of cardiac biomarkers by monitoring the changes in the resonant condition of the cavity due to biomolecular binding processes. Antibodies against cTnI are immobilized on the sensor surface for specific detection of cTnI with a wide range of concentrations. Detection limit of cTnI with a concentration as low as 0.1 ng mL−1 has been achieved. PMID:24632136

  8. Label-free detection of cardiac troponin I with a photonic crystal biosensor.

    PubMed

    Zhang, Bailin; Morales, Andres W; Peterson, Ralph; Tang, Liang; Ye, Jing Yong

    2014-08-15

    A biosensor has been developed with a photonic crystal structure used in a total-internal-reflection (PC-TIR) configuration for label-free detection of a cardiac biomarker: Troponin I (cTnI). In contrast to a conventional optical microcavity that has a closed structure with its cavity layer sandwiched between two high-reflection surfaces, the PC-TIR configuration creates a unique open microcavity, which allows its cavity layer (sensing layer) to be easily functionalized and directly exposed to analyte molecules for bioassays. In this study, a PC-TIR sensor has been used for the label-free measurements of cardiac biomarkers by monitoring the changes in the resonant condition of the cavity due to biomolecular binding processes. Antibodies against cTnI are immobilized on the sensor surface for specific detection of cTnI with a wide range of concentrations. Detection limit of cTnI with a concentration as low as 0.1ngmL(-1) has been achieved. PMID:24632136

  9. Single-nanoparticle detection with slot-mode photonic crystal cavities

    SciTech Connect

    Wang, Cheng; Kita, Shota; Lončar, Marko; Quan, Qimin; Li, Yihang

    2015-06-29

    Optical cavities that are capable for detecting single nanoparticles could lead to great progress in early stage disease diagnostics and the study of biological interactions on the single-molecule level. In particular, photonic crystal (PhC) cavities are excellent platforms for label-free single-nanoparticle detection, owing to their high quality (Q) factors and wavelength-scale modal volumes. Here, we demonstrate the design and fabrication of a high-Q (>10{sup 4}) slot-mode PhC nanobeam cavity, which is able to strongly confine light in the slotted regions. The enhanced light-matter interaction results in an order of magnitude improvement in both refractive index sensitivity (439 nm/RIU) and single-nanoparticle sensitivity compared with conventional dielectric-mode PhC cavities. Detection of single polystyrene nanoparticles with radii of 20 nm and 30 nm is demonstrated in aqueous environments (D{sub 2}O), without additional laser and temperature stabilization techniques.

  10. Trap and track: designing self-reporting porous Si photonic crystals for rapid bacteria detection.

    PubMed

    Massad-Ivanir, Naama; Mirsky, Yossi; Nahor, Amit; Edrei, Eitan; Bonanno-Young, Lisa M; Ben Dov, Nadav; Sa'ar, Amir; Segal, Ester

    2014-08-21

    The task of rapid detection and identification of bacteria remains a major challenge in both medicine and industry. This work introduces a new concept for the design of self-reporting optical structures that can detect and quantify bacteria in real-time. The sensor is based on a two-dimensional periodic structure of porous Si photonic crystals in which the pore size is adjusted to fit the target bacteria cells (Escherichia coli). Spontaneous bacteria capture within the pores induces measurable changes in the zero-order reflectivity spectrum collected from the periodic structure. Confocal laser microscopy and electron microscopy confirm that the Escherichia coli cells are individually imprisoned within the porous array. A simple model is suggested to correlate the optical readout and the bacteria concentration and its predictions are found to be in good agreement with experimental results. In addition, we demonstrate that sensing scheme can be easily modified to potentially allow monitoring of concentration, growth and physiological state of bacteria cells. This generic platform can be tailored to target different microorganisms by tuning the array periodicity and its surface chemistry for rapid and label-free detection outside the laboratory environment.

  11. A nonionic surfactant-decorated liquid crystal sensor for sensitive and selective detection of proteins.

    PubMed

    Wang, Yi; Hu, Qiongzheng; Tian, Tongtong; Gao, Yan'an; Yu, Li

    2016-09-21

    Proteins are responsible for most biochemical events in human body. It is essential to develop sensitive and selective methods for the detection of proteins. In this study, liquid crystal (LC)-based sensor for highly selective and sensitive detection of lysozyme, concanavalin A (Con A), and bovine serum albumin (BSA) was constructed by utilizing the LC interface decorated with a nonionic surfactant, dodecyl β-d-glucopyranoside. A change of the LC optical images from bright to dark appearance was observed after transferring dodecyl β-d-glucopyranoside onto the aqueous/LC interface due to the formation of stable self-assembled surfactant monolayer, regardless of pH and ion concentrations studied in a wide range. The optical images turned back from dark to bright appearance after addition of lysozyme, Con A and BSA, respectively. Noteworthy is that these proteins can be further distinguished by adding enzyme inhibitors and controlling incubation temperature of the protein solutions based on three different interaction mechanisms between proteins and dodecyl β-d-glucopyranoside, viz. enzymatic hydrolysis, specific saccharide binding, and physical absorption. The LC-based sensor decorated with dodecyl β-d-glucopyranoside shows high sensitivity for protein detection. The limit of detection (LOD) for lysozyme, Con A and BSA reaches around 0.1 μg/mL, 0.01 μg/mL and 0.001 μg/mL, respectively. These results might provide new insights into increasing selectivity and sensitivity of LC-based sensors for the detection of proteins.

  12. Piezoelectric-Crystal-Resonator High-Frequency Gravitational Wave Generation and Synchro-Resonance Detection

    NASA Astrophysics Data System (ADS)

    Baker, Robert M. L.; Woods, R. Clive; Li, Fangyu

    2006-01-01

    Here we show the generation of high-frequency-gravitational-waves (HFGWs) utilizing piezoelectric elements such as the ubiquitous Film-Bulk-Acoustic-Resonators (FBARs), found in cell phones, as energized by inexpensive magnetrons, found in microwave ovens, generating GWs having a frequency of about 4.9GHz and their detection by means of new synchro-resonance techniques developed in China. In the 1960s Weber suggested piezoelectric crystals for gravitational-wave (GW) generation. Since then researchers have proposed specific designs. The major obstacle has been the cost of procuring, installing, and energizing a sufficient number of such resonators to generate sufficiently powerful GWs to allow for detection. Recent mass-production techniques, spurred on by the production of cell phones, have driven the cost of resonators down. The new Chinese detector for detecting the 4.9×109Hz HFGW is a coupling-system of fractal membranes-beam-splitters and a narrow, 6.1 cm-radius, pulsed-Gaussian-laser or continuous-Gaussian detection beam passing through a static 15T-magnetic field. The detector is sensitive to GW amplitudes of ~10-30 to be generated with signal-to-noise ratios greater than one. It is concluded that a cost-effective HFGW generation and detection apparatus can now be fabricated and operated in the laboratory. If the two groups or clusters of magnetrons and FBARs were space borne and at lunar distance (e.g., at the Moon and at the lunar L3 libration point) and the quadrupole formalism approximately holds for GW radiators (the FBAR clusters) many GW wavelengths apart, then the HFGW power would be about 420 W and the flux about 2×105 Wm-2 (or more than one hundred times greater than the solar radiation flux at the Earth) focused at the focal spot, or remote-HFGW-emitter, anywhere in the Earth's environs - on or below the Earth's surface.

  13. A nonionic surfactant-decorated liquid crystal sensor for sensitive and selective detection of proteins.

    PubMed

    Wang, Yi; Hu, Qiongzheng; Tian, Tongtong; Gao, Yan'an; Yu, Li

    2016-09-21

    Proteins are responsible for most biochemical events in human body. It is essential to develop sensitive and selective methods for the detection of proteins. In this study, liquid crystal (LC)-based sensor for highly selective and sensitive detection of lysozyme, concanavalin A (Con A), and bovine serum albumin (BSA) was constructed by utilizing the LC interface decorated with a nonionic surfactant, dodecyl β-d-glucopyranoside. A change of the LC optical images from bright to dark appearance was observed after transferring dodecyl β-d-glucopyranoside onto the aqueous/LC interface due to the formation of stable self-assembled surfactant monolayer, regardless of pH and ion concentrations studied in a wide range. The optical images turned back from dark to bright appearance after addition of lysozyme, Con A and BSA, respectively. Noteworthy is that these proteins can be further distinguished by adding enzyme inhibitors and controlling incubation temperature of the protein solutions based on three different interaction mechanisms between proteins and dodecyl β-d-glucopyranoside, viz. enzymatic hydrolysis, specific saccharide binding, and physical absorption. The LC-based sensor decorated with dodecyl β-d-glucopyranoside shows high sensitivity for protein detection. The limit of detection (LOD) for lysozyme, Con A and BSA reaches around 0.1 μg/mL, 0.01 μg/mL and 0.001 μg/mL, respectively. These results might provide new insights into increasing selectivity and sensitivity of LC-based sensors for the detection of proteins. PMID:27590553

  14. Detection of UV light based on chemically stimulated luminescence of crystal phosphors

    NASA Astrophysics Data System (ADS)

    Grankin, D. V.; Grankin, V. P.; Martysh, M. A.

    2016-06-01

    High-efficiency accommodation of heterogeneous-reaction energy via an electronic channel and the possibility of using this effect to design an ionizing (UV) radiation detector based on chemically stimulated luminescence have been investigated. Preliminary irradiation of a ZnS sample by UV light is found to cause a luminescence flash under subsequent exposure of the sample surface to a flux of hydrogen atoms. The flash intensity depends on the UV excitation level and increases by several orders of magnitude in comparison with an unirradiated sample. It is shown that a new method for detecting UV light using chemically stimulated luminescence of crystal phosphors accumulating light yield can be developed based on this effect.

  15. Silver corrosion and sulfur detection using a quartz crystal microbalance with silver electrode surfaces

    SciTech Connect

    Zabarnick, S.; Zelesnik, P.; Whitacre, S.D.

    1996-08-01

    A quartz crystal microbalance (QCM) with silver electrodes is used for detection of sulfur and measurement of silver corrosion by sulfur in jet fuels. It is found that the device responds very sensitively to elemental sulfur by reaction at the silver surface, resulting in the formation of surface silver sulfide. It is also expected that the device will respond to hydrogen sulfide. The response of the QCM is found to depend on the fuel matrix. The presence of oxygen inhibits the surface reaction, resulting in a lower mass accumulation. It is also found that the sulfur compounds which produce a response in this test are not players in the formation of autoxidative surface deposition. It is shown that the QCM response (surface mass per unit time) is proportional to the concentration of elemental sulfur present in the fuel.

  16. Self assembled monolayer based liquid crystal biosensor for free cholesterol detection

    NASA Astrophysics Data System (ADS)

    Tyagi, Mukta; Chandran, Achu; Joshi, Tilak; Prakash, Jai; Agrawal, V. V.; Biradar, A. M.

    2014-04-01

    A unique cholesterol oxidase (ChOx) liquid crystal (LC) biosensor, based on the disruption of orientation in LCs, is developed for cholesterol detection. A self-assembled monolayer (SAM) of Dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (DMOAP) and (3-Aminopropyl)trimethoxy-silane (APTMS) is prepared on a glass plate by adsorption. The enzyme (ChOx) is immobilized on SAM surface for 12 h before utilizing the film for biosensing purpose. LC based biosensing study is conducted on SAM/ChOx/LC (5CB) cells for cholesterol concentrations ranging from 10 mg/dl to 250 mg/dl. The sensing mechanism has been verified through polarizing optical microscopy, scanning electron microscopy, and spectrometric techniques.

  17. Two-dimensional silicon photonic crystal based biosensing platform for protein detection.

    PubMed

    Lee, Mindy R; Fauchet, Philippe M

    2007-04-16

    We theoretically and experimentally demonstrate an ultrasensitive two-dimensional photonic crystal microcavity biosensor. The device is fabricated on a silicon-on-insulator wafer and operates near its resonance at 1.58 microm. Coating the sensor internal surface with proteins of different sizes produces a different amount of resonance redshift. The present device can detect a molecule monolayer with a total mass as small as 2.5 fg. The device performance is verified by measuring the redshift corresponding to the binding of glutaraldehyde and bovine serum albumin (BSA). The experimental results are in good agreement with theory and with ellipsometric measurements performed on a flat oxidized silicon wafer surface. PMID:19532700

  18. Two-dimensional silicon photonic crystal based biosensing platform for protein detection

    NASA Astrophysics Data System (ADS)

    Lee, Mindy R.; Fauchet, Philippe M.

    2007-04-01

    We theoretically and experimentally demonstrate an ultrasensitive two-dimensional photonic crystal microcavity biosensor. The device is fabricated on a silicon-on-insulator wafer and operates near its resonance at 1.58 μm. Coating the sensor internal surface with proteins of different sizes produces a different amount of resonance redshift. The present device can detect a molecule monolayer with a total mass as small as 2.5 fg. The device performance is verified by measuring the redshift corresponding to the binding of glutaraldehyde and bovine serum albumin (BSA). The experimental results are in good agreement with theory and with ellipsometric measurements performed on a flat oxidized silicon wafer surface.

  19. Self assembled monolayer based liquid crystal biosensor for free cholesterol detection

    SciTech Connect

    Tyagi, Mukta; Agrawal, V. V.; Chandran, Achu; Joshi, Tilak; Prakash, Jai; Biradar, A. M.

    2014-04-14

    A unique cholesterol oxidase (ChOx) liquid crystal (LC) biosensor, based on the disruption of orientation in LCs, is developed for cholesterol detection. A self-assembled monolayer (SAM) of Dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (DMOAP) and (3-Aminopropyl)trimethoxy-silane (APTMS) is prepared on a glass plate by adsorption. The enzyme (ChOx) is immobilized on SAM surface for 12 h before utilizing the film for biosensing purpose. LC based biosensing study is conducted on SAM/ChOx/LC (5CB) cells for cholesterol concentrations ranging from 10 mg/dl to 250 mg/dl. The sensing mechanism has been verified through polarizing optical microscopy, scanning electron microscopy, and spectrometric techniques.

  20. A Customized Raman System for Point-of-Care Detection of Arthropathic Crystals in the Synovial Fluid

    PubMed Central

    Li, Bolan; Yang, Shan; Akkus, Ozan

    2014-01-01

    Monosodium urate (MSU) and calcium pyrophosphate dihydrate (CPPD) are the most frequently observed crystals in joint space, leading to painful arthropathies. Correct diagnosis of the crystal identity is critical for the appropriate course of treatment. In this work, a custom Raman device in combination with a practical and efficient sample preparation method is used for chemically selective diagnosis of MSU and CPPD crystals in an automated fashion. The samples were prepared by a brief enzymatic digestion treatment of synovial fluid followed by a customized filtration process which was able to congregate crystals over a submillimeter sized spot. The data acquisition and collection was automated to collect multiple spectra distributed over the filtration spot. The performance of the cost-efficient Raman system was compared to a research-grade high fidelity Raman instrument. The custom-designed Raman device could detect MSU crystals at sub-clinical concentration of 0.1 μg/mL, and 1 μg/mL for CPPD crystals. This practical sample preparation approach in tandem with the low-cost customized Raman device has a potential to be a novel tool for point-and-shoot Raman diagnosis of arthritic crystals in synovial fluid at the point of care. PMID:24419093

  1. Optical detection of a single rare-earth ion in a crystal

    PubMed Central

    Kolesov, R.; Xia, K.; Reuter, R.; Stöhr, R.; Zappe, A.; Meijer, J.; Hemmer, P.R.; Wrachtrup, J.

    2012-01-01

    Rare-earth-doped laser materials show strong prospects for quantum information storage and processing, as well as for biological imaging, due to their high-Q 4f↔4f optical transitions. However, the inability to optically detect single rare-earth dopants has prevented these materials from reaching their full potential. Here we detect a single photostable Pr3+ ion in yttrium aluminium garnet nanocrystals with high contrast photon antibunching by using optical upconversion of the excited state population of the 4f↔4f optical transition into ultraviolet fluorescence. We also demonstrate on-demand creation of Pr3+ ions in a bulk yttrium aluminium garnet crystal by patterned ion implantation. Finally, we show generation of local nanophotonic structures and cell death due to photochemical effects caused by upconverted ultraviolet fluorescence of praseodymium-doped yttrium aluminium garnet in the surrounding environment. Our study demonstrates versatile use of rare-earth atomic-size ultraviolet emitters for nanoengineering and biotechnological applications. PMID:22929786

  2. Biomimetic Receptors for Bioanalyte Detection by Quartz Crystal Microbalances — From Molecules to Cells †

    PubMed Central

    Latif, Usman; Qian, Jianjin; Can, Serpil; Dickert, Franz L.

    2014-01-01

    A universal label-free detection of bioanalytes can be performed with biomimetic quartz crystal microbalance (QCM) coatings prepared by imprinting strategies. Bulk imprinting was used to detect the endocrine disrupting chemicals (EDCs) known as estradiols. The estrogen 17β-estradiol is one of the most potent EDCs, even at very low concentrations. A highly sensitive, selective and robust QCM sensor was fabricated for real time monitoring of 17β-estradiol in water samples by using molecular imprinted polyurethane. Optimization of porogen (pyrene) and cross-linker (phloroglucinol) levels leads to improved sensitivity, selectivity and response time of the estradiol sensor. Surface imprinting of polyurethane as sensor coating also allowed us to generate interaction sites for the selective recognition of bacteria, even in a very complex mixture of interfering compounds, while they were growing from their spores in nutrient solution. A double molecular imprinting approach was followed to transfer the geometrical features of natural bacteria onto the synthetic polymer to generate biomimetic bacteria. The use of biomimetic bacteria as template makes it possible to prepare multiple sensor coatings with similar sensitivity and selectivity. Thus, cell typing, e.g., differentiation of bacteria strains, bacteria growth profile and extent of their nutrition, can be monitored by biomimetic mass sensors. Obviously, this leads to controlled cell growth in bioreactors. PMID:25490598

  3. When nano meets bio: Biological molecule detection based on silicon two-dimensional photonic crystals

    NASA Astrophysics Data System (ADS)

    Lee, Mindy Ren

    Over the past few years, techniques for early detection and identification of biological substances have been pursued with great interest in wide-ranging fields. One of the fast growing areas in biosensing research involves developing label-free optical biosensors. Theses biosensors do not use radioactive or fluorescent labels, hence not only reduce the complexity in sample preparation and possible contamination to biological materials in vivo but allow measurement in real-time. Recently photonic crystals (PhCs) have shown great promise as a novel sensing platform because of their strong light confinement. By introducing a localized defect (e.g. point-like defect, line-like defect) inside a PhC, an electromagnetic microcavity can be created which gives rise to defect states inside photonic bandgaps. The transmission spectrum of the microcavity shows resonance peaks. The capture of material inside the microcavity is monitored by observing resonance peak shifts. Such cavities can be designed to have ultra-high quality factor (Q > 106) and hence are extremely sensitive to the refractive index change due to biological molecule capture. Our device has a small sensing area (1 microm2 ˜ 40 microm2) which requires only a very small amount of sample analyte (˜ fg). Moreover, a small sensing area would also allow dense integration of multiple sensors on a single chip. The device can be potentially used for quantitively measuring protein monolayer thickness and detecting single viruses.

  4. Magneto-optical effects for detection of in-plane magnetization in plasmonic crystals

    NASA Astrophysics Data System (ADS)

    Kalish, A. N.; Belotelov, V. I.

    2016-08-01

    Methods for magneto-optical detection of the in-plane magnetization in a magnetic film due to the deposition of a one-dimensional metallic diffraction grating on the film have been considered. This structure is a magnetoplasmonic crystal, in which the excitation of the waveguide and plasmon modes leads to the appearance of five resonant magneto-optical effects that consist in a change of the intensity, the polarization, and the phase of the transmitted and reflected waves. The conditions responsible for the origin of these effects and their magnitude are determined by the configuration of the incident light, the parameters of the metallic grating, and the chemical composition of the magnetic layer. It has been found that the magnetophotonic intensity effects are the most optimal for the detection of the in-plane magnetization. The influence of the parameters of the metallic grating on the magneto-optical effects has been analyzed and the most optimal conditions for the observation of these effects have been determined. It has also been found that an increase in the concentration of bismuth in a magnetic dielectric material can lead to a weakening of the optical and magneto-optical responses.

  5. Quartz crystal microbalance (QCM) affinity biosensor for genetically modified organisms (GMOs) detection.

    PubMed

    Mannelli, Ilaria; Minunni, Maria; Tombelli, Sara; Mascini, Marco

    2003-03-01

    A DNA piezoelectric sensor has been developed for the detection of genetically modified organisms (GMOs). Single stranded DNA (ssDNA) probes were immobilised on the sensor surface of a quartz crystal microbalance (QCM) device and the hybridisation between the immobilised probe and the target complementary sequence in solution was monitored. The probe sequences were internal to the sequence of the 35S promoter (P) and Nos terminator (T), which are inserted sequences in the genome of GMOs regulating the transgene expression. Two different probe immobilisation procedures were applied: (a) a thiol-dextran procedure and (b) a thiol-derivatised probe and blocking thiol procedure. The system has been optimised using synthetic oligonucleotides, which were then applied to samples of plasmidic and genomic DNA isolated from the pBI121 plasmid, certified reference materials (CRM), and real samples amplified by the polymerase chain reaction (PCR). The analytical parameters of the sensor have been investigated (sensitivity, reproducibility, lifetime etc.). The results obtained showed that both immobilisation procedures enabled sensitive and specific detection of GMOs, providing a useful tool for screening analysis in food samples.

  6. On-line detection of organic pollutants in water by selective quartz crystal microbalance

    SciTech Connect

    Lucklum, R.; Roesler, S.; Hauptmann, P.

    1996-12-31

    Today the automatic analysis of small amounts of toxic substances and metabolites is an important task of and environmental control but still expensive. Only a few sensors are able to detect neutral molecules in liquids specifically and most of them work off-line. Development of Quartz Crystal Microbalance (QCM)-sensors designed for on-line detection of organic in aqueous systems is discussed. Chemical resonant sensors are easy to fabricate, due to their frequency analogous output compatible to digital electronics and customary configurable to the analyte of interest with chemically sensitive and selective organic coatings. Basically designed to measure surface mass changes, e.g. via analyte adsorption, QCM in liquids is considerable more complex. The observed frequency shift is not only caused by the mass effect also the viscous coupling with the liquid at the quartz surface, surface roughness, occurring surface stresses, changing liquid properties and even the driver electronics can change the sensor signal. QCM as biosensor is already well known and based on the specific bioreceptor-ligand (analytes) interactions and the high molecular mass of these bioanalytes. The authors aim is the application of QCM as specific chemical sensor for substances in liquids with molecular masses between 80 and 200 g/mol.

  7. From Exploratory Synthesis to Hard Radiation Detection: Crystal Growth and Characterization of Chalcogenide and Chalcohalide Materials

    NASA Astrophysics Data System (ADS)

    Nguyen, Sandy Linhsa

    In the first half of this thesis work, exploratory synthesis of materials using mixed polychalcogenide fluxes yielded four quaternary mixed Te/S compounds, with the respective chalcogen atoms residing in different crystallographic sites. Two-dimensional thiotellurite compounds (Ag2TeS3) 2·A2S6 (A = Rb, Cs), containing the trigonal pyramidal [TeS 3]2- unit, were synthesized and characterized. These structures are composed of layers of neutral [Ag2TeS3] alternating with charge-balanced salt layers containing the polysulfide chain [S6]2- and alkali metal ions. Using mixed Te/S polychalcogenide fluxes for compound discovery, we then investigated a new set of layered metal dichalcogenides, Ag2Te(MS2)3 (M = V, Nb) crystallizing in the P-62m space group. Ag2Te(MS2)3 contains layers of [Ag2Te] sandwiched between layers of [MS2] (M = V, Nb). The Ag and, more interestingly, Te atoms are linearly coordinated by S atoms in the [MS2] layers. This linear coordination of the Te atom by S atoms is unprecedented in the literature and stabilized by charge transfer within the [Ag2Te] layers. In the latter half, we report the bulk crystal growth and characterization of Tl-based chalcogenide and chalcohalide materials for hard radiation (X- and gamma-ray) detection, which requires high density, wide band gaps, and high resistivity. Lattice hybridization was applied to identify materials with optimal properties for hard radiation detection, resulting in the chalcohalide compound Tl6SI4. Tl6SI4 exhibits low effective mass of carriers, high resistivity, optimal band gap, and large hardness values. The figure of merit mutau products, (mutau) e = 2.1 x 10-3 cm2V-1 and (mutau)h = 2.3 x 10-5 cm2V -1, are comparable to state-of-the-art commercially used materials. Furthermore, high resolution detection of Ag X-rays by Tl6SI 4 was seen at 22 keV (2.6%). Dimensional reduction was used to identify Tl-based chalcogenide materials Tl2MS3 (M = Ge, Sn). Tl2MS3 show great potential for use as hard

  8. Hydrophilic-Hydrophobic Patterned Molecularly Imprinted Photonic Crystal Sensors for High-Sensitive Colorimetric Detection of Tetracycline.

    PubMed

    Hou, Jue; Zhang, Huacheng; Yang, Qiang; Li, Mingzhu; Jiang, Lei; Song, Yanlin

    2015-06-01

    A hydrophilic-hydrophobic patterned molecularly imprinted (MIP) photonic crystal (PC) sensor is fabricated for highly sensitive tetracycline detection. The relationship between the tetracycline concentration, its corresponding color of the sensor, and the diameter of MIP-PC dot is found using a fan-shaped color card. This work provides a new strategy to design the sensors with tunable detection ranges for practical applications.

  9. Hydrophilic-Hydrophobic Patterned Molecularly Imprinted Photonic Crystal Sensors for High-Sensitive Colorimetric Detection of Tetracycline.

    PubMed

    Hou, Jue; Zhang, Huacheng; Yang, Qiang; Li, Mingzhu; Jiang, Lei; Song, Yanlin

    2015-06-01

    A hydrophilic-hydrophobic patterned molecularly imprinted (MIP) photonic crystal (PC) sensor is fabricated for highly sensitive tetracycline detection. The relationship between the tetracycline concentration, its corresponding color of the sensor, and the diameter of MIP-PC dot is found using a fan-shaped color card. This work provides a new strategy to design the sensors with tunable detection ranges for practical applications. PMID:25649896

  10. Synthesis of hierarchical iron hydrogen phosphate crystal as a robust peroxidase mimic for stable H₂O₂ detection.

    PubMed

    Zhang, Tongbao; Lu, Yangcheng; Luo, Guangsheng

    2014-08-27

    To develop a green, cost-efficient and robust peroxidase mimic, micro/nano hierarchical morphology (for ease of separation and reuse), relative chemically stable composition (for ease of storage) and stable crystal structure (for long-term stability) are highly desired. Herein, using phosphoric acid as a chelating ligand to control the release of iron ions, hierarchical iron(III) hydrogen phosphate hydrate crystals are successfully prepared by nanosheets formation and following self-assembling in a facile low-temperature hydrothermal process. They are first found to have peroxidase-like activity and showed higher affinity for H2O2 and lower affinity for 3,3',5,5'-tetramethylbenzidine compared with horseradish peroxidase. The affinity feature is used for quantitative detection of H2O2 and shows a wide linear detection range from 57.4 to 525.8 μM (R(2) = 0.994) with a low detection limit of 1 μM. Benefited from chemical stability of hierarchical iron(III) salt crystals, they own good reproducibility (relative standard deviation = 1.95% for 10 independent measurements), long-term stability (no activity loss after 10 cycles), and ease of recovery (by simple centrifugation). Because the method is easily accessible, iron hydrogen phosphate hierarchical crystals have great potential for practical use of H2O2 sensing and detection under harsh conditions.

  11. Using channelized Hotelling observers to quantify temporal effects of medical liquid crystal displays on detection performance

    NASA Astrophysics Data System (ADS)

    Platiša, Ljiljana; Goossens, Bart; Vansteenkiste, Ewout; Badano, Aldo; Philips, Wilfried

    2010-02-01

    Clinical practice is rapidly moving in the direction of volumetric imaging. Often, radiologists interpret these images in liquid crystal displays at browsing rates of 30 frames per second or higher. However, recent studies suggest that the slow response of the display can compromise image quality. In order to quantify the temporal effect of medical displays on detection performance, we investigate two designs of a multi-slice channelized Hotelling observer (msCHO) model in the task of detecting a single-slice signal in multi-slice simulated images. The design of msCHO models is inspired by simplifying assumptions about how humans observe while viewing in the stack-browsing mode. For comparison, we consider a standard CHO applied only on the slice where the signal is located, recently used in a similar study. We refer to it as a single-slice CHO (ssCHO). Overall, our results confirm previous findings that the slow response of displays degrades the detection performance of the observers. More specifically, the observed performance range of msCHO designs is higher compared to the ssCHO suggesting that the extent and rate of degradation, though significant, may be less drastic than previously estimated by the ssCHO. Especially, the difference between msCHO and ssCHO is more significant for higher browsing speeds than for slow image sequences or static images. This, together with their design criteria driven by the assumptions about humans, makes the msCHO models promising candidates for further studies aimed at building anthropomorphic observer models for the stack-mode image presentation.

  12. Antenna-coupled silicon-organic hybrid integrated photonic crystal modulator for broadband electromagnetic wave detection

    NASA Astrophysics Data System (ADS)

    Zhang, Xingyu; Hosseini, Amir; Subbaraman, Harish; Wang, Shiyi; Zhan, Qiwen; Luo, Jingdong; Jen, Alex K.; Chung, Chi-jui; Yan, Hai; Pan, Zeyu; Nelson, Robert L.; Lee, Charles Y.; Chen, Ray T.

    2015-03-01

    The detection and measurement of electromagnetic fields have attracted significant amounts of attention in recent years. Traditional electronic electromagnetic field sensors use large active conductive probes which perturb the field to be measured and also make the devices bulky. In order to address these problems, integrated photonic electromagnetic field sensors have been developed, in which an optical signal is modulated by an RF signal collected by a miniaturized antenna. In this work, we design, fabricate and characterize a compact, broadband and highly sensitive integrated photonic electromagnetic field sensor based on a silicon-organic hybrid modulator driven by a bowtie antenna. The large electro-optic (EO) coefficient of organic polymer, the slow-light effects in the silicon slot photonic crystal waveguide (PCW), and the broadband field enhancement provided by the bowtie antenna, are all combined to enhance the interaction of microwaves and optical waves, enabling a high EO modulation efficiency and thus a high sensitivity. The modulator is experimentally demonstrated with a record-high effective in-device EO modulation efficiency of r33=1230pm/V. Modulation response up to 40GHz is measured, with a 3-dB bandwidth of 11GHz. The slot PCW has an interaction length of 300μm, and the bowtie antenna has an area smaller than 1cm2. The bowtie antenna in the device is experimentally demonstrated to have a broadband characteristics with a central resonance frequency of 10GHz, as well as a large beam width which enables the detection of electromagnetic waves from a large range of incident angles. The sensor is experimentally demonstrated with a minimum detectable electromagnetic power density of 8.4mW/m2 at 8.4GHz, corresponding to a minimum detectable electric field of 2.5V/m and an ultra-high sensitivity of 0.000027V/m Hz-1/2 ever demonstrated. To the best of our knowledge, this is the first silicon-organic hybrid device and also the first PCW device used for the

  13. Application of a quartz-crystal microbalance for detection of phase transitions in liquid crystals and lipid multibilayers

    SciTech Connect

    Okahata, Yoshio; Ebato, Hiroshi )

    1989-10-01

    Resonance frequency increased abruptly at the phase transition temperature (T{sub c}) from solid to liquid crystalline state of liquid crystals (LCs) or lipid multibilayer films cast on a quartz-crystal microbalance (QCM) electrode when the ambient temperature increased gradually. The large frequency enhancement at the T{sub c} was observed in the case of smectic LC-coated QCM compared with those of nematic and cholesteric LC-coated QCM. Although the frequency enhancement at the T{sub c} of the LC-coated QCM was observed independent of media such as water and air phases, the frequency of the lipid multibilayer-coated QCM increased abruptly at the T{sub c} only in a water phase, but not in an air phase. Frequency enhancements at T{sub c} can be explained by slipping between layered structures of smectic LC and lipid multibilayer in the fluid liquid crystalline state above the T{sub c}. In the case of lipid multibilayers, the penetration of water into interlayers (swelling) occurs at the T{sub c} and then the frequency increase is observed due to slipping between hydrated and fluid layers only in aqueous phases.

  14. Small organic molecules detection based on aptamer-modified gold nanoparticles-enhanced quartz crystal microbalance with dissipation biosensor.

    PubMed

    Zheng, Bin; Cheng, Sheng; Liu, Wei; Lam, Michael Hon-Wah; Liang, Haojun

    2013-07-15

    Small molecules are difficult to detect by the conventional quartz crystal microbalance with dissipation (QCM-D) technique directly because the changes in frequency resulting from the binding processes of small biomolecules are often small. In the current study, an aptamer-based gold nanoparticles (AuNPs)-enhanced sensing strategy for detection of small molecules was developed. The QCM crystal was first modified with a layer of thiolated linker DNA, which can be partly base-paired with the detection part containing the adenosine aptamer sequence. In the presence of adenosine, the aptamer bound with adenosine and folded to the complex structure, which precluded the reporter part carrying AuNPs to combine with the random coiled detection part. Therefore, the lower the concentration of adenosine, the more AuNPs combined to the crystal. The resulting aptasensor showed a linear response to the increase of the adenosine concentration in the range of 0-2 μM with a linear correlation of r=0.99148 and a detection limit of 65 nM. Moreover, the aptasensor exhibited several excellent characteristics such as high sensitivity, selectivity, good stability, and reproducibility.

  15. Molded plasmonic crystals for detecting and spatially imaging surface bound species by surface-enhanced Raman scattering.

    SciTech Connect

    Baca, A. J.; Truong, T. T.; Cambrea, L. R.; Montgomery, J. M.; Abdula, D.; Banks, T. R.; Yao, J.; Nuzzo, R. G.; Gray, S. K.; Rogers, J. A.

    2009-06-24

    This report introduces a type of plasmonic crystal that consists of metal coated nanostructures of relief molded on a polymer film as a substrate for surface-enhanced Raman scattering (SERS). Such crystals exhibit SERS enhancement factors of {approx} 10{sup 5}, over large areas and with sufficiently high levels of uniformity for precise two-dimensional Raman mapping of surface bound monolayers. The ease of fabrication together with the high sensitivities and spatial resolution that can be achieved suggests an attractive route to SERS substrates for portable chemical warfare agent detection, environmental monitors, noninvasive imaging of biomolecules, and other applications.

  16. Photonic crystal fiber injected with Fe{sub 3}O{sub 4} nanofluid for magnetic field detection

    SciTech Connect

    Thakur, Harneet V.; Nalawade, Sandipan M.; Gupta, Swati; Kitture, Rohini; Kale, S. N.

    2011-10-17

    We report a magnetic field sensor having advantages of both photonic crystal fiber and optofluidics, combining them on a single platform by infiltrating small amount of Fe{sub 3}O{sub 4} magnetic optofluid/nanofluid in cladding holes of polarization-maintaining photonic crystal fiber. We demonstrated that magnetic field of few mT can be easily and very well detected with higher sensitivity of 242 pm/mT. The change in the birefringence values has been correlated to the response of nanofluid to applied field.

  17. Liquid crystal-based sensors for the detection of heavy metals using surface-immobilized urease.

    PubMed

    Hu, Qiong-Zheng; Jang, Chang-Hyun

    2011-12-01

    In this study, a new method for the detection of heavy metals in aqueous phase was developed using liquid crystals (LCs). When UV-treated nematic LC, 4-cyano-4'-pentyl biphenyl (5CB) that was confined in the urease-modified gold grid was immersed in a urea solution, an optical response from bright to dark was observed under a polarized microscope, indicating that a planar-to-homeotropic orientational transition of the LC occurred at the aqueous/LC interface. Since urease hydrolyzes urea to produce ammonia, which would be ionized into ammonium and hydroxide ions, the main product of the photochemically degraded 5CB, 4-cyano-4'-biphenylcarboxylic acid (CBA), was deprotonated and self-assembled at the interface, inducing the orientational transition in the LC. Due to the high sensitivity and rapid response of this system, detection of heavy metal ions was further exploited. The divalent copper ion, which could effectively inhibit the activity of urease, was used as a model heavy metal ion. The optical appearance of the LC did not change when urea was in contact with the copper nitrate hydrate-blocked urease. After the copper-inhibited urease was reactivated by EDTA, a bright-to-dark shift in the optical signal was regenerated, indicating an orientational transition of the LC. This type of LC-based sensor shows high spatial resolution due to its optical characteristics and therefore could potentially be used to accurately monitor the presence of enzyme inhibitors such as heavy metal ions in real-time. PMID:21846586

  18. Liquid crystal-based sensors for the detection of heavy metals using surface-immobilized urease.

    PubMed

    Hu, Qiong-Zheng; Jang, Chang-Hyun

    2011-12-01

    In this study, a new method for the detection of heavy metals in aqueous phase was developed using liquid crystals (LCs). When UV-treated nematic LC, 4-cyano-4'-pentyl biphenyl (5CB) that was confined in the urease-modified gold grid was immersed in a urea solution, an optical response from bright to dark was observed under a polarized microscope, indicating that a planar-to-homeotropic orientational transition of the LC occurred at the aqueous/LC interface. Since urease hydrolyzes urea to produce ammonia, which would be ionized into ammonium and hydroxide ions, the main product of the photochemically degraded 5CB, 4-cyano-4'-biphenylcarboxylic acid (CBA), was deprotonated and self-assembled at the interface, inducing the orientational transition in the LC. Due to the high sensitivity and rapid response of this system, detection of heavy metal ions was further exploited. The divalent copper ion, which could effectively inhibit the activity of urease, was used as a model heavy metal ion. The optical appearance of the LC did not change when urea was in contact with the copper nitrate hydrate-blocked urease. After the copper-inhibited urease was reactivated by EDTA, a bright-to-dark shift in the optical signal was regenerated, indicating an orientational transition of the LC. This type of LC-based sensor shows high spatial resolution due to its optical characteristics and therefore could potentially be used to accurately monitor the presence of enzyme inhibitors such as heavy metal ions in real-time.

  19. Chirality amplification and detection by tactoids of lyotropic chromonic liquid crystals.

    PubMed

    Peng, Chenhui; Lavrentovich, Oleg D

    2015-10-01

    Detection of chiral molecules requires amplification of chirality to measurable levels. Typically, amplification mechanisms are considered at the microscopic scales of individual molecules and their aggregates. Here we demonstrate chirality amplification and visualization of structural handedness in water solutions of organic molecules that extends over the scale of many micrometers. The mechanism is rooted in the long-range elastic nature of orientational order in lyotropic chromonic liquid crystals (LCLCs) formed in water solutions of achiral disc-like molecules. The nematic LCLC coexists with its isotropic counterpart, forming elongated tactoids; the spatial confinement causes a structural twist even when the material is nonchiral. Minute quantities of chiral molecules such as the amino acid l-alanine and limonene transform the racemic array of left- and right-twisted tactoids into a homochiral set. The left and right chiral enantiomers are readily distinguished from each other as the induced structural handedness is visualized through a simple polarizing microscope observation. The effect is important for developing our understanding of chirality amplification mechanisms; it also might open up new possibilities in biosensing. PMID:26238525

  20. Detection of gamma photons using solution-grown single crystals of hybrid lead halide perovskites

    NASA Astrophysics Data System (ADS)

    Yakunin, Sergii; Dirin, Dmitry N.; Shynkarenko, Yevhen; Morad, Viktoriia; Cherniukh, Ihor; Nazarenko, Olga; Kreil, Dominik; Nauser, Thomas; Kovalenko, Maksym V.

    2016-09-01

    The decay of the majority of radioactive isotopes involves the emission of gamma (γ) photons with energies of ∼50 keV to 10 MeV. Detectors of such hard radiation that are low-cost, highly sensitive and operate at ambient temperatures are desired for numerous applications in defence and medicine, as well as in research. We demonstrate that 0.3–1 cm solution-grown single crystals (SCs) of semiconducting hybrid lead halide perovskites (MAPbI3, FAPbI3 and I-treated MAPbBr3, where MA = methylammonium and FA = formamidinium) can serve as solid-state gamma-detecting materials. This possibility arises from a high charge-carrier mobility–lifetime (μτ) product of 1.0–1.8 × 10‑2 cm2 V‑1, a low dark carrier density of 109–1011 cm‑3 (refs 3,4), a low density of charge traps of 109–1010 cm‑3 (refs 4,5) and a high absorptivity of hard radiation by the lead and iodine atoms. We demonstrate the utility of perovskite detectors for testing the radiopurity of medical radiotracer compounds such as 18F-fallypride. Energy-resolved sensing at room temperature is presented using FAPbI3 SCs and an 241Am source.

  1. Visual detection of 2,4,6-trinitrotolune by molecularly imprinted colloidal array photonic crystal.

    PubMed

    Lu, Wei; Asher, Sanford A; Meng, Zihui; Yan, Zequn; Xue, Min; Qiu, Lili; Yi, Da

    2016-10-01

    We developed a photonic crystal (PhC) sensor for the quantification of 2,4,6-trinitrotoluene (TNT) in solution. Monodisperse (210nm in diameter) molecularly imprinted colloidal particles (MICs) for TNT were prepared by the emulsion polymerization of methyl methacrylate and acrylamide in the presence of TNT as a template. The MICs were then self-assembled into close-packed opal PhC films. The adsorption capacity of the MICs for TNT was 64mg TNT/g. The diffraction from the PhC depended on the TNT concentration in a methanol/water (3/2, v/v) potassium dihydrogen phosphate buffer solution (pH=7.0, 30mM). The limit of detection (LOD) of the sensor was 1.03μg. The color of the molecularly imprinted colloidal array (MICA) changed from green to red with an 84nm diffraction red shift when the TNT concentration increased to 20mM. The sensor response time was 3min. The PhC sensor was selective for TNT compared to similar compounds such as 2,4,6-trinitrophenol, 2,4-dinitrotoluene, 2,6-dinitrotoluene, 2-nitromesitylene, 4-nitrotoluene, 2-nitrotoluene, 1,3-dinitrobenzene, methylbenzene, 4-nitrophenol, 2-nitroaniline, 3-aminophenol and 3-nitroaniline. The sensor showed high stability with little response change after three years storage. This sensor technology might be useful for the visual determination of TNT. PMID:27214001

  2. Detection of H3N2 canine influenza virus using a Quartz Crystal Microbalance.

    PubMed

    Kim, Yong Kwan; Lim, Seong-In; Cho, Yoon-Young; Choi, Sarah; Song, Jae-Young; An, Dong-Jun

    2014-11-01

    Label-free technology-based Quartz Crystal Microbalance (QCM) is an emerging tool in biological research. In this study, QCM was applied successfully for the rapid diagnosis of H3N2 canine influenza virus (CIV) infection. ProLinker™ B, a calixcrown derivative, enables antibodies to be attached to a gold-coated quartz surface and positioned in a regular pattern with the correct orientation. The ProLinker-coated quartz-based assay detected H3N2 CIV at lower concentrations (2(2) HA unit) than a commercial immunochromatography Ag kit (2(3) HA unit). Three independent experiments in which H3N2 CIV-positive reference samples were applied to an anti-CIV nucleoprotein (NP) monoclonal antibody immobilized on a quartz surface yielded standard deviations (SD) of ≤5%, indicating high reproducibility. In addition, the QCM assay with a cut-off value (-140 Hz) showed 97.1% (34/35) sensitivity and 94.7% (36/38) specificity in testing 73 field saliva samples, respectively. Thus, the QCM assay described herein will be a valuable tool for the rapid diagnosis of H3N2 CIV infection with high sensitivity and specificity, and should overcome several of the disadvantages and limitations inherent in the commercial immunochromatography Ag kit. PMID:25072379

  3. Detection of gamma photons using solution-grown single crystals of hybrid lead halide perovskites

    NASA Astrophysics Data System (ADS)

    Yakunin, Sergii; Dirin, Dmitry N.; Shynkarenko, Yevhen; Morad, Viktoriia; Cherniukh, Ihor; Nazarenko, Olga; Kreil, Dominik; Nauser, Thomas; Kovalenko, Maksym V.

    2016-09-01

    The decay of the majority of radioactive isotopes involves the emission of gamma (γ) photons with energies of ˜50 keV to 10 MeV. Detectors of such hard radiation that are low-cost, highly sensitive and operate at ambient temperatures are desired for numerous applications in defence and medicine, as well as in research. We demonstrate that 0.3-1 cm solution-grown single crystals (SCs) of semiconducting hybrid lead halide perovskites (MAPbI3, FAPbI3 and I-treated MAPbBr3, where MA = methylammonium and FA = formamidinium) can serve as solid-state gamma-detecting materials. This possibility arises from a high charge-carrier mobility-lifetime (μτ) product of 1.0-1.8 × 10-2 cm2 V-1, a low dark carrier density of 109-1011 cm-3 (refs 3,4), a low density of charge traps of 109-1010 cm-3 (refs 4,5) and a high absorptivity of hard radiation by the lead and iodine atoms. We demonstrate the utility of perovskite detectors for testing the radiopurity of medical radiotracer compounds such as 18F-fallypride. Energy-resolved sensing at room temperature is presented using FAPbI3 SCs and an 241Am source.

  4. Active layer identification of photonic crystal waveguide biosensor chip for the detection of Escherichia coli

    NASA Astrophysics Data System (ADS)

    Painam, Balveer; Kaler, Rajinder S.; Kumar, Mukesh

    2016-07-01

    This work represents experimental and simulation analysis of photonic crystal waveguide (PCW)-based biosensor structures, which is used for detection of the Escherichia coli (E. coli) cell. A method is adopted for E. coli culture to measure length, diameter, and refractive index to finalize the structural design and to verify the suitability of PCW as a biosensor. This method is tested using DH5α strains of E. coli. The typical precisions of measurements are varied in ranges from 1.132 to 1.825 μm and from 0.447 to 0.66 μm for pathogen's length and diameter, respectively. The measured distribution of samples over length and diameter are in correlation with the measurements performed by scanning electron microscope. After obtaining average length and diameter of cylindrical shaped E. coli cell, we consider these values for simulation analysis of designed PCW biosensor. E. coli cell is trapped in the middle of the PCW biosensor having three different types of waveguides, i.e., gallium arsenide/silicon dioxide (GaAs/SiO2), silicon/silicon dioxide (Si/SiO2), or silicon nitride/silicon dioxide (Si3N4/SiO2) to observe the maximum resonance shift and sensitivity. It is observed from the simulation data analysis that GaAs/SiO2 is the preferred PCW biosensor for the identification of E. coli.

  5. Apparatus for detecting and recognizing analytes based on their crystallization patterns

    DOEpatents

    Morozov, Victor; Bailey, Charles L.; Vsevolodov, Nikolai N.; Elliott, Adam

    2010-12-14

    The invention contemplates apparatuses for recognition of proteins and other biological molecules by imaging morphology, size and distribution of crystalline and amorphous dry residues in droplets (further referred to as "crystallization patterns") containing predetermined amount of certain crystal-forming organic compounds (reporters) to which protein to be analyzed is added. Changes in the crystallization patterns of a number of amino-acids can be used as a "signature" of a protein added. Also, changes in the crystallization patterns, as well as the character of such changes, can be used as recognition elements in analysis of protein molecules.

  6. Pathogen detection in complex samples by quartz crystal microbalance sensor coupled to aptamer functionalized core-shell type magnetic separation.

    PubMed

    Ozalp, Veli C; Bayramoglu, Gulay; Erdem, Zehra; Arica, M Yakup

    2015-01-01

    A quartz crystal microbalance sensor (QCM) was developed for sensitive and specific detection of Salmonella enterica serovar typhimurium cells in food samples by integrating a magnetic bead purification system. Although many sensor formats based on bioaffinity agents have been developed for sensitive and specific detection of bacterial cells, the development of robust sensor applications for food samples remained a challenging issue. A viable strategy would be to integrate QCM to a pre-purification system. Here, we report a novel and sensitive high throughput strategy which combines an aptamer-based magnetic separation system for rapid enrichment of target pathogens and a QCM analysis for specific and real-time monitoring. As a proof-of-concept study, the integration of Salmonella binding aptamer immobilized magnetic beads to the aptamer-based QCM system was reported in order to develop a method for selective detection of Salmonella. Since our magnetic separation system can efficiently capture cells in a relatively short processing time (less than 10 min), feeding captured bacteria to a QCM flow cell system showed specific detection of Salmonella cells at 100 CFU mL(-1) from model food sample (i.e., milk). Subsequent treatment of the QCM crystal surface with NaOH solution regenerated the aptamer-sensor allowing each crystal to be used several times.

  7. Automated detection and characterization of microstructural features: application to eutectic particles in single crystal Ni-based superalloys

    NASA Astrophysics Data System (ADS)

    Tschopp, M. A.; Groeber, M. A.; Fahringer, R.; Simmons, J. P.; Rosenberger, A. H.; Woodward, C.

    2010-03-01

    Serial sectioning methods continue to produce an abundant amount of image data for quantifying the three-dimensional nature of material microstructures. Here, we discuss a methodology to automate detecting and characterizing eutectic particles taken from serial images of a production turbine blade made of a heat-treated single crystal Ni-based superalloy (PWA 1484). This method includes two important steps for unassisted eutectic particle characterization: automatically identifying a seed point within each particle and segmenting the particle using a region growing algorithm with an automated stop point. Once detected, the segmented eutectic particles are used to calculate microstructural statistics for characterizing and reconstructing statistically representative synthetic microstructures for single crystal Ni-based superalloys. The significance of this work is its ability to automate characterization for analysing the 3D nature of eutectic particles.

  8. Terahertz electro-optic detection using a ⟨012⟩-cut chalcopyrite ZnGeP2 crystal

    NASA Astrophysics Data System (ADS)

    Carnio, B. N.; Greig, S. R.; Firby, C. J.; Zawilski, K. T.; Schunemann, P. G.; Elezzabi, A. Y.

    2016-06-01

    The electro-optic detection capabilities of a <012>-cut chalcopyrite ZnGeP2 (ZGP) crystal is investigated in the terahertz (THz) frequency regime. Our experiments attest that ZGP exhibits low THz losses and dispersion, and that phonon-polariton effects are too weak to perturb the THz pulse. Additionally, ZGP is shown to have excellent phase matching between an optical probe pulse and a THz pulse. For a 1080 μm thick ZGP crystal, this phase matching yields a detection bandwidth 1.3 times greater than ZnTe and 4.8 times greater than ZnSe and GaP. Thus, ZGP has promising applications in THz time-domain spectroscopy.

  9. Self-assembly of cholesterol DNA at liquid crystal/aqueous interface and its application for DNA detection

    NASA Astrophysics Data System (ADS)

    Lai, Siok Lian; Hartono, Deny; Yang, Kun-Lin

    2009-10-01

    In this letter, we report a strategy of detecting the DNA targets by using a thin layer of self-assembled cholesterol-labeled DNA probes at the liquid crystal (LC)/aqueous interface. When the system is exposed to 51 μg/ml of complementary DNA targets, the optical appearance of LC shows a continuous change from dark to bright under the crossed polars within 15 min. No obvious change can be observed when the system is exposed to one or two base-pair mismatch DNA targets. This system provides a principle for label-free and real-time detection of DNA targets without any fluorescent labeling.

  10. Real-time microbe detection based on director distortions around growing immune complexes in lyotropic chromonic liquid crystals.

    PubMed

    Shiyanovskii, S V; Schneider, T; Smalyukh, I I; Ishikawa, T; Niehaus, G D; Doane, K J; Woolverton, C J; Lavrentovich, O D

    2005-02-01

    We describe director distortions in the nematic liquid crystal (LC) caused by a spherical particle with tangential surface orientation of the director and show that light transmittance through the distorted region is a steep function of the particle's size. The effect allows us to propose a real-time microbial sensor based on a nontoxic lyotropic chromonic LC (LCLC) that detects and amplifies the presence of immune complexes. A cassette is filled with LCLC, antibody, and antigen-bearing particles. Small and isolated particles cause no macroscopic distortions of the LCLC. Upon antibody-antigen binding, the growing immune complexes distort the director and cause detectable optical transmittance between crossed polarizers.

  11. Design, construction and testing of a system for detection of toxic gases based on piezoelectric crystals.

    PubMed

    Leyva, J A; de Cisneros, J L; de Barreda, D G; Becerra, A J

    1994-01-01

    A system for static operation of toxic gas sensors based on piezoelectric crystals was constructed as a preliminary step in the development of this type of sensor. The sensing part of the setup consists of a twin oscillating circuit assembled from commercially available electronic parts mounted on a motherboard. The oscillating circuits can accommodate two piezoelectric crystals, of which one or both can be coated with different materials, or a single one, as required. The sensing assembly (crystals plus oscillating circuits) is placed in a customized test chamber that allows one to control and reproduce its internal environment. Once assembled and fine-tuned, the proposed setup was used to test a commercially available piezoelectric crystal for sensing formaldehyde in order to expand available information on this type of sensor. PMID:18965902

  12. Selective detection of sub-atto-molar Streptavidin in 10(13)-fold impure sample using photonic crystal nanolaser sensors.

    PubMed

    Hachuda, Shoji; Otsuka, Shota; Kita, Shota; Isono, Toshinari; Narimatsu, Michimasa; Watanabe, Keisuke; Goshima, Yoshio; Baba, Toshihiko

    2013-05-20

    Biosensors selectively detecting a very small amount of biomarker protein in human blood are desired for early and reliable diagnoses of severe diseases. This paper reports the detection of protein (streptavidin: SA) in ultra-low concentration, with an ultra-high selectivity against contaminants, using photonic crystal nanolasers. For biotin-modified nanolasers in pure water with SA, an extremely-low detection limit of 16 zM is evaluated. Even in a mixture with 1 μM bovine serum albumin as the contaminant, 100 zM SA is detected, meaning a selectivity of 10(13). These are remarkable capabilities that are promising for practical biosensing in the medical applications mentioned above.

  13. Resistively detected NMR spectra of the crystal states of the two-dimensional electron gas in a quantizing magnetic field

    NASA Astrophysics Data System (ADS)

    Côté, R.; Simoneau, Alexandre M.

    2016-02-01

    Transport experiments on the two-dimensional electron gas (2DEG) confined into a semiconductor quantum well and subjected to a quantizing magnetic field have uncovered a rich variety of uniform and nonuniform phases such as the Laughlin liquids, the Wigner, bubble, and Skyrme crystals, and the quantum Hall stripe state. Optically pumped nuclear magnetic resonance (OP-NMR) has also been extremely useful in studying the magnetization and dynamics of electron solids with exotic spin textures such as the Skyrme crystal. Recently, it has been demonstrated that a related technique, resistively-detected nuclear magnetic resonance (RD-NMR), could be a good tool to study the topography of the electron solids in the fractional and integer quantum Hall regimes. In this work, we compute theoretically the RD-NMR line shapes of various crystal phases of the 2DEG and study the relation between their spin density and texture and their NMR spectra. This allows us to evaluate the ability of the RD-NMR to discriminate between the various types of crystal states.

  14. Ultra-sensitive detection of zinc oxide nanowires using a quartz crystal microbalance and phosphoric acid DNA

    NASA Astrophysics Data System (ADS)

    Jang, Kuewhan; You, Juneseok; Park, Chanhoo; Park, Hyunjun; Choi, Jaeyeong; Choi, Chang-Hwan; Park, Jinsung; Lee, Howon; Na, Sungsoo

    2016-09-01

    Recent advancements of nanomaterials have inspired numerous scientific and industrial applications. Zinc oxide nanowires (ZnO NWs) is one of the most important nanomaterials due to their extraordinary properties. However, studies performed over the past decade have reported toxicity of ZnO NWs. Therefore, there has been increasing demand for effective detection of ZnO NWs. In this study, we propose a method for the detection of ZnO NW using a quartz crystal microbalance (QCM) and DNA probes. The detection method is based on the covalent interaction between ZnO NWs and the phosphoric acid group of single-stranded DNA (i.e., linker DNA), and DNA hybridization between the linker DNA and the probe DNA strand on the QCM electrode. Rapid, high sensitivity, in situ detection of ZnO NWs was demonstrated for the first time. The limit of detection was 10‑4 μg ml‑1 in deionized water, which represents a sensitivity that is 100000 times higher than the toxic ZnO NW concentration level. Moreover, the selectivity of the ZnO NW detection method was demonstrated by comparison with other types of nanowires and the method was able to detect ZnO NWs in tap water sensitively even after stored for 14 d in a refrigerator. The performance of our proposed method was sufficient to achieve detection of ZnO NW in the ‘real-world’ environment.

  15. Ultra-sensitive detection of zinc oxide nanowires using a quartz crystal microbalance and phosphoric acid DNA

    NASA Astrophysics Data System (ADS)

    Jang, Kuewhan; You, Juneseok; Park, Chanhoo; Park, Hyunjun; Choi, Jaeyeong; Choi, Chang-Hwan; Park, Jinsung; Lee, Howon; Na, Sungsoo

    2016-09-01

    Recent advancements of nanomaterials have inspired numerous scientific and industrial applications. Zinc oxide nanowires (ZnO NWs) is one of the most important nanomaterials due to their extraordinary properties. However, studies performed over the past decade have reported toxicity of ZnO NWs. Therefore, there has been increasing demand for effective detection of ZnO NWs. In this study, we propose a method for the detection of ZnO NW using a quartz crystal microbalance (QCM) and DNA probes. The detection method is based on the covalent interaction between ZnO NWs and the phosphoric acid group of single-stranded DNA (i.e., linker DNA), and DNA hybridization between the linker DNA and the probe DNA strand on the QCM electrode. Rapid, high sensitivity, in situ detection of ZnO NWs was demonstrated for the first time. The limit of detection was 10-4 μg ml-1 in deionized water, which represents a sensitivity that is 100000 times higher than the toxic ZnO NW concentration level. Moreover, the selectivity of the ZnO NW detection method was demonstrated by comparison with other types of nanowires and the method was able to detect ZnO NWs in tap water sensitively even after stored for 14 d in a refrigerator. The performance of our proposed method was sufficient to achieve detection of ZnO NW in the ‘real-world’ environment.

  16. Ultra-sensitive detection of zinc oxide nanowires using a quartz crystal microbalance and phosphoric acid DNA.

    PubMed

    Jang, Kuewhan; You, Juneseok; Park, Chanhoo; Park, Hyunjun; Choi, Jaeyeong; Choi, Chang-Hwan; Park, Jinsung; Lee, Howon; Na, Sungsoo

    2016-09-01

    Recent advancements of nanomaterials have inspired numerous scientific and industrial applications. Zinc oxide nanowires (ZnO NWs) is one of the most important nanomaterials due to their extraordinary properties. However, studies performed over the past decade have reported toxicity of ZnO NWs. Therefore, there has been increasing demand for effective detection of ZnO NWs. In this study, we propose a method for the detection of ZnO NW using a quartz crystal microbalance (QCM) and DNA probes. The detection method is based on the covalent interaction between ZnO NWs and the phosphoric acid group of single-stranded DNA (i.e., linker DNA), and DNA hybridization between the linker DNA and the probe DNA strand on the QCM electrode. Rapid, high sensitivity, in situ detection of ZnO NWs was demonstrated for the first time. The limit of detection was 10(-4) μg ml(-1) in deionized water, which represents a sensitivity that is 100000 times higher than the toxic ZnO NW concentration level. Moreover, the selectivity of the ZnO NW detection method was demonstrated by comparison with other types of nanowires and the method was able to detect ZnO NWs in tap water sensitively even after stored for 14 d in a refrigerator. The performance of our proposed method was sufficient to achieve detection of ZnO NW in the 'real-world' environment.

  17. Ultra-sensitive detection of zinc oxide nanowires using a quartz crystal microbalance and phosphoric acid DNA.

    PubMed

    Jang, Kuewhan; You, Juneseok; Park, Chanhoo; Park, Hyunjun; Choi, Jaeyeong; Choi, Chang-Hwan; Park, Jinsung; Lee, Howon; Na, Sungsoo

    2016-09-01

    Recent advancements of nanomaterials have inspired numerous scientific and industrial applications. Zinc oxide nanowires (ZnO NWs) is one of the most important nanomaterials due to their extraordinary properties. However, studies performed over the past decade have reported toxicity of ZnO NWs. Therefore, there has been increasing demand for effective detection of ZnO NWs. In this study, we propose a method for the detection of ZnO NW using a quartz crystal microbalance (QCM) and DNA probes. The detection method is based on the covalent interaction between ZnO NWs and the phosphoric acid group of single-stranded DNA (i.e., linker DNA), and DNA hybridization between the linker DNA and the probe DNA strand on the QCM electrode. Rapid, high sensitivity, in situ detection of ZnO NWs was demonstrated for the first time. The limit of detection was 10(-4) μg ml(-1) in deionized water, which represents a sensitivity that is 100000 times higher than the toxic ZnO NW concentration level. Moreover, the selectivity of the ZnO NW detection method was demonstrated by comparison with other types of nanowires and the method was able to detect ZnO NWs in tap water sensitively even after stored for 14 d in a refrigerator. The performance of our proposed method was sufficient to achieve detection of ZnO NW in the 'real-world' environment. PMID:27479871

  18. Solitary wave-based delamination detection in composite plates using a combined granular crystal sensor and actuator

    NASA Astrophysics Data System (ADS)

    Kim, Eunho; Restuccia, Francesco; Yang, Jinkyu; Daraio, Chiara

    2015-12-01

    We experimentally and numerically investigate a diagnostic method for detecting hidden delamination in composite panels, using highly nonlinear solitary waves. Solitary waves are a type of nonlinear waves with strong energy intensity and non-distortive nature, which can be controllably generated in one-dimensional granular crystals. In this study, we use granular crystals as a combined sensor and actuator to detect hidden delamination in carbon fiber reinforced polymer (CFRP) composite panels. Specifically, we locally excite a CFRP composite specimen using the granular crystal as an actuator and measure the reflected waves that carry the specimen’s diagnostic information using the same device as a sensor. We first investigate the effect of the panel’s boundary conditions on the response of the reflected solitary waves. We then investigate the interactions of a solitary wave with delamination hidden in the CFRP composite specimen. Lastly, we define a damage index based on the solitary waves’ responses to identify the location of the hidden delamination in the CFRP composite panel. The solitary wave-based diagnostic method can provide unique merits, such as portable and fast sensing of composites’ hidden damage, thereby with the potential of being used for hot spot monitoring of composite-based structures.

  19. Use of shear-stress-sensitive, temperature-insensitive liquid crystals for hypersonic boundary-layer transition detection

    SciTech Connect

    Aeschliman, D.P.; Croll, R.H.; Kuntz, D.W.

    1997-04-01

    The use of shear-stress-sensitive, temperature-insensitive (SSS/TI) liquid crystals (LCs) has been evaluated as a boundary-layer transition detection technique for hypersonic flows. Experiments were conducted at Mach 8 in the Sandia National Laboratories Hypersonic Wind Tunnel using a flat plate model at near zero-degree angle of attack over the freestream unit Reynolds number range 1.2-5.8x10{sup 6}/ft. Standard 35mm color photography and Super VHS color video were used to record LC color changes due to varying surface shear stress during the transition process for a range of commercial SSS liquid crystals. Visual transition data were compared to an established method using calorimetric surface heat-transfer measurements to evaluate the LC technique. It is concluded that the use of SSS/TI LCs can be an inexpensive, safe, and easy to use boundary-layer transition detection method for hypersonic flows. However, a valid interpretation of the visual records requires careful attention to illumination intensity levels and uniformity, lighting and viewing angles, some prior understanding of the general character of the flow, and the selection of the appropriate liquid crystal for the particular flow conditions.

  20. Direct detection of density of gap states in C60 single crystals by photoemission spectroscopy

    NASA Astrophysics Data System (ADS)

    Bussolotti, Fabio; Yang, Janpeng; Hiramoto, Masahiro; Kaji, Toshihiko; Kera, Satoshi; Ueno, Nobuo

    2015-09-01

    We report on the direct and quantitative evaluation of density of gap states (DOGS) in large-size C60 single crystals by using ultralow-background, high-sensitivity ultraviolet photoemission spectroscopy. The charging of the crystals during photoionization was overcome using photoconduction induced by simultaneous laser irradiation. By comparison with the spectra of as-deposited and gas exposed C60 thin films the following results were found: (i) The DOGS near the highest occupied molecular orbital edge in the C60 single crystals (1019-1021states e V-1c m-3) mainly originates from the exposure to inert and ambient gas atmosphere during the sample preparation, storage, and transfer; (ii) the contribution of other sources of gap states such as structural imperfections at grain boundaries is negligible (<1018states e V-1c m-3) .

  1. Investigations of Cadmium Manganese Telluride Crystals for Room-Temperature Radiation Detection

    SciTech Connect

    Yang, G.; Bolotnikov, A.; Camarda, G.; Cui, Y.; Hossain, A.; Kim, K.; Carcelen, V.; Gul, R.; James, R.

    2009-10-06

    Cadmium manganese telluride (CMT) has high potential as a material for room-temperature nuclear-radiation detectors. We investigated indium-doped CMT crystals taken from the stable growth region of the ingot, and compared its characteristics with that from the last-to-freeze region. We employed different techniques, including synchrotron white-beam X-ray topography (SWBXT), current-voltage (I-V) measurements, and low-temperature photoluminescence spectra, and we also assessed their responses as detectors to irradiation exposure. The crystal from the stable growth region proved superior to that from the last-to-freeze region; it is a single-grain crystal, free of twins, and displayed a resistivity higher by two orders-of-magnitude. The segregation of indium dopant in the ingot might be responsible for its better resistivity. Furthermore, we recorded a good response in the detector fabricated from the crystal taken from the stable growth region; its ({mu}{tau}){sub e} value was 2.6 x 10{sup -3} cm{sup 2}/V, which is acceptable for thin detectors, including for applications in medicine.

  2. Evaluation of crystal violet decolorization assay for minimal inhibitory concentration detection of primary antituberculosis drugs against Mycobacterium tuberculosis isolates*

    PubMed Central

    Coban, Ahmet Yilmaz; Akbal, Ahmet Ugur; Uzun, Meltem; Cayci, Yeliz Tanriverdi; Birinci, Asuman; Durupinar, Belma

    2016-01-01

    In this study we evaluated the crystal violet decolorization assay (CVDA) for detection of minimum inhibitory concentration (MIC) of antituberculosis drugs. 53 isolates were tested in this study and 13 of them were multidrug resistant (MDR) isolates. The antibiotics concentrations were 2-0.06 mg/L for isoniazid (INH) and rifampicin (RIF) and were 16-0.25 mg/L for streptomycin (STM) and ethambutol (EMB). Crystal violet (CV-25 mg/L) was added into the microwells on the seventh day of incubation and incubation was continued until decolorization. Decolorization of CV was the predictor of bacterial growth. Overall agreements for four drugs were detected as 98.1%, and the average time was detected as 9.5 ± 0.89 day after inoculation. One isolate for INH and two isolates for STM were determined resistant in the reference method, but susceptible by the CVDA. One isolate was susceptible to EMB by the reference method, but resistant by the CVDA. All results were concordant for RIF. This study shows that CVDA is a rapid, reliable and suitable for determination of MIC values of Mycobacterium tuberculosis. And it can be used easily especially in countries with limited-sources. PMID:27304025

  3. Evaluation of crystal violet decolorization assay for minimal inhibitory concentration detection of primary antituberculosis drugs against Mycobacterium tuberculosis isolates.

    PubMed

    Coban, Ahmet Yilmaz; Akbal, Ahmet Ugur; Uzun, Meltem; Cayci, Yeliz Tanriverdi; Birinci, Asuman; Durupinar, Belma

    2016-06-10

    In this study we evaluated the crystal violet decolorization assay (CVDA) for detection of minimum inhibitory concentration (MIC) of antituberculosis drugs. 53 isolates were tested in this study and 13 of them were multidrug resistant (MDR) isolates. The antibiotics concentrations were 2-0.06 mg/L for isoniazid (INH) and rifampicin (RIF) and were 16-0.25 mg/L for streptomycin (STM) and ethambutol (EMB). Crystal violet (CV-25 mg/L) was added into the microwells on the seventh day of incubation and incubation was continued until decolorization. Decolorization of CV was the predictor of bacterial growth. Overall agreements for four drugs were detected as 98.1%, and the average time was detected as 9.5 ± 0.89 day after inoculation. One isolate for INH and two isolates for STM were determined resistant in the reference method, but susceptible by the CVDA. One isolate was susceptible to EMB by the reference method, but resistant by the CVDA. All results were concordant for RIF. This study shows that CVDA is a rapid, reliable and suitable for determination of MIC values of Mycobacterium tuberculosis. And it can be used easily especially in countries with limited-sources. PMID:27304025

  4. A novel dendritic surfactant for enhanced microcystin-LR detection by double amplification in a quartz crystal microbalance biosensor.

    PubMed

    Xia, Yuetong; Zhang, Jianping; Jiang, Long

    2011-08-01

    Enhanced sensitivity for the hepatotoxin microcystin-LR (MC-LR) was achieved in a quartz crystal microbalance (QCM) system via double amplification. For primary amplification, an innovative interface on the QCM was obtained as a matrix by the vesicle layer formed by our synthetic dendritic surfactant, bis (amidoethyl-carbamoylethyl) octadecylamine (C18N3). The vesicle matrix was then functionalised by an optimised concentration of monoclonal antibodies against MC-LR (anti-MC-LR) to detect the analyte. The results showed that a detection limit of 100 ng/mL was achieved by primary amplification. To achieve higher sensitivity, secondary amplification was implemented with anti-MC-LR gold nanoparticle (AuNPs) conjugates as probes, which lowered the detection limit for MC-LR to 1 ng/mL (the maximum concentration recommended by the World Health Organization [WHO] in drinking water for humans). The QCM immunosensor reported here has advantages such as high sensitivity, portability, simplicity, and cost-effectiveness for MC-LR detection. It would be uniquely superior compared with current MC-LR detection techniques for on-the-spot water detection. Furthermore, the methodology described here is also potentially significant in many fields for the routine monitoring of environmental and food safety.

  5. Polyvinylpyrrolidone/reduced graphene oxide nanocomposites thin films coated on quartz crystal microbalance for NO2 detection at room temperature

    NASA Astrophysics Data System (ADS)

    Huang, Junlong; Xie, Guangzhong; Zhou, Yong; Xie, Tao; Tai, HuiLing; Yang, Guangjin

    2014-08-01

    Polyvinylpyrrolidone (PVP)/reduced graphene oxide (RGO) nanocomposites are sprayed on quartz crystal microbalance (QCM) for NO2 sensing. The thin films are characterized by Fourier transform infrared spectroscopy (FTIR) and ultraviolet-visible spectroscopy (UV-VIS). The experimental results reveal that PVP/RGO sensor exhibits higher sensitivity and shorter recovery time than those of PVP. Besides, the response to 20 ppm NO2 is higher than other gases such as CO, CO2 and NH3 even at 100ppm. When the PVP/RGO sensor is exposed to these gases, the good selectivity to NO2 makes the sensor ideal for NO2 detection.

  6. Detection of low concentration formaldehyde gas by photonic crystal sensor fabricated by nanoimprint process in polymer material

    NASA Astrophysics Data System (ADS)

    Boersma, A.; van Ee, Renz J.; Stevens, Ralph S. A.; Saalmink, Milan; Charlton, Martin D. B.; Pollard, Michael E.; Chen, Ruiqi; Kontturi, Ville; Karioja, Pentti; Alajoki, Teemu

    2014-05-01

    This paper describes experimental measurement results for photonic crystal sensor devices which have been functionalized for gas sensing applications. The sensor consists of a two dimensional photonic crystal etched into a slab waveguide having a refractive index of 1.7-1.9. Test devices were fabricated from SiON material on silicon / silicon dioxide platform, and also in polymer materials on silicon platform. The inorganic photonic crystals were made using direct write electron-beam lithography and reactive ion etching. The polymeric devices were made by nano-imprint lithography using the SiON structure as the imprint master. The high refractive index polymer was composed of a TiO2 - UV resin nanocomposite having a nanoparticle fraction between 50 and 60 wt%. This resulted in a tunable refractive index between 1.7 and 1.85. Devices were functionalized for gas sensing applications by coating the surface with a chemical receptor. This responsive layer reacts with the target gas and changes its refractive index. This change causes the angle of out-coupling to change slightly. In this paper we report successful detection of formaldehyde in air at sub ppm levels, and discuss details of chemical functionalization of the PC sensor.

  7. Multiplexed DNA detection using spectrally encoded porous SiO2 photonic crystal particles

    PubMed Central

    Meade, Shawn O.; Chen, Michelle Y.

    2009-01-01

    A particle-based multiplexed DNA assay based on encoded porous SiO2 photonic crystal disks is demonstrated. A “spectral barcode” is generated by electrochemical etch of a single-crystal silicon wafer using a programmed current-time waveform. A lithographic procedure is used to isolate cylindrical microparticles 25 microns in diameter and 10 microns thick, which are then oxidized, modified with a silane linker, and conjugated to various amino functionalized oligonucleotide probes via cyanuric chloride. It is shown that the particles can be decoded based on their reflectivity spectra, and that a multiple analyte assay can be performed in a single sample with a modified fluorescence microscope. The homogeneity of the reflectivity and fluorescence spectra, both within and across the microparticles is also reported. PMID:19271746

  8. Label-free optical detection of bacteria on a 1-D photonic crystal of porous silicon

    NASA Astrophysics Data System (ADS)

    Wu, Chia-Chen; Alvarez, Sara D.; Rang, Camilla U.; Chao, Lin; Sailor, Michael J.

    2009-02-01

    The construction of a specific, label-free, bacteria biosensor using porous silicon 1-D photonic crystals will be described. Bacteria resident on the surface of porous silicon act as scattering centers for light resonant with the photonic crystal; the diffusely scattered light possesses the optical spectrum of the underlying photonic crystal. Using a spectrometer fitted to a light microscope, the bacteria are imaged without using exogenous dyes or labels and are quantified by measuring the intensity of scattered light. In order to selectively bind and identify bacteria using porous Si, we use surface modifications to reduce nonspecific binding to the surface and to engineer bacteria specificity onto the surface. Bovine serum albumin (BSA) was adsorbed to the porous Si surface to reduce nonspecific binding of bacteria. The coatings were then chemically activated to immobilize polyclonal antibodies specific to Escherichia coli. Two E. coli strains were used in our study, E. coli DH5α and non-pathogenic enterohemorrhagic Escherichia coli (EHEC) strain. The nonpathogenic Vibrio cholerae O1 strain was used to test for antibody specificity. Successful attachment of antibodies was measured using fluorescence microscopy and the scattering method was used to test for bacteria binding specificity.

  9. Ultrasensitive detection of streptomycin using flow injection analysis-electrochemical quartz crystal nanobalance (FIA-EQCN) biosensor.

    PubMed

    Mishra, Geetesh K; Sharma, Atul; Bhand, Sunil

    2015-05-15

    This work presents the development of an ultrasensitive biosensor for detection of streptomycin residues in milk samples using flow injection analysis-electrochemical quartz crystal nanobalance (FIA-EQCN) technique. Monoclonal antibody specific to streptomycin was immobilized on to the thiol modified gold quartz crystal surface. A broad dynamic range (0.3-300 ng/mL) was obtained for streptomycin with a good linearity in the range 0.3-10 ng/mL for PBS and 0.3-50 ng/mL for milk. The correlation coefficient (R(2)) of the biosensor was found to be 0.994 and 0.997 for PBS and milk respectively. Excellent recoveries were obtained from the streptomycin spiked milk samples in the range 98-99.33%, which shows the applicability of the developed biosensor in milk. The reproducibility of the developed biosensor was found satisfactory with % RSD (n=5) 0.351. A good co-relation was observed between the streptomycin recoveries measured through the developed biosensor and the commercial ELISA kit. The analytical figures of merit of the developed biosensor confirm that the developed FIA-EQCN biosensor could be very effective for low-level detection of streptomycin in milk samples.

  10. Bovine serum albumin detection and quantitation based on capacitance measurements of liquid crystals

    NASA Astrophysics Data System (ADS)

    Lin, Chi-Hao; Lee, Mon-Juan; Lee, Wei

    2016-08-01

    Liquid crystal (LC)-based biosensing is generally limited by the lack of accurate quantitative strategies. This study exploits the unique electric capacitance properties of LCs to establish quantitative assay methods for bovine serum albumin (BSA) biomolecules. By measuring the voltage-dependent electric capacitance of LCs under an alternating-current field with increasing amplitude, positive correlations were derived between the BSA concentration and the electric capacitance parameters of LCs. This study demonstrates that quantitative analysis can be achieved in LC-based biosensing through electric capacitance measurements extensively employed in LCD research and development.

  11. Feasibility demonstration for hydrogen chloride detection using a chemisorption technique and a quartz crystal microbalance

    NASA Technical Reports Server (NTRS)

    Jex, D. W.; Workman, G. L.

    1975-01-01

    A method of measuring concentrations of hydrogen chloride between 1 part per billion and 10 parts per million at standard temperature and pressure is presented. The feasibility of a low-cost device incorporating a chemisorption technique coupled with a quartz crystal microbalance was demonstrated in the field at the Viking B launch using a Titan-Centaur vehicle from Kennedy Space Center on August 20, 1975. Hydrogen chloride is a product of solid rocket combustion. The concentration level of hydrogen chloride for this particular launch was measured as approximately 0.2 parts per million at 4 km from the launch site.

  12. Polarization switching detection method using a ferroelectric liquid crystal for dichroic atomic vapor laser lock frequency stabilization techniques.

    PubMed

    Dudzik, Grzegorz; Rzepka, Janusz; Abramski, Krzysztof M

    2015-04-01

    We present a concept of the polarization switching detection method implemented for frequency-stabilized lasers, called the polarization switching dichroic atomic vapor laser lock (PSDAVLL) technique. It is a combination of the well-known dichroic atomic vapor laser lock method for laser frequency stabilization with a synchronous detection system based on the surface-stabilized ferroelectric liquid crystal (SSFLC).The SSFLC is a polarization switch and quarter wave-plate component. This technique provides a 9.6 dB better dynamic range ratio (DNR) than the well-known two-photodiode detection configuration known as the balanced polarimeter. This paper describes the proposed method used practically in the VCSEL laser frequency stabilization system. The applied PSDAVLL method has allowed us to obtain a frequency stability of 2.7×10⁻⁹ and a reproducibility of 1.2×10⁻⁸, with a DNR of detected signals of around 81 dB. It has been shown that PSDAVLL might be successfully used as a method for spectra-stable laser sources.

  13. Liquid crystal-based detection of thrombin coupled to interactions between a polyelectrolyte and a phospholipid monolayer.

    PubMed

    Zhang, Minmin; Jang, Chang-Hyun

    2014-06-15

    Herein, we describe a real-time, label-free biosensing strategy for thrombin detection that uses the orientational properties of nematic liquid crystals (LCs) and the interactions between a polyelectrolyte and a phospholipid monolayer. The imaging principle is based on the disruption of the orientation of 4-cyano-4'-pentylbiphenyl by reorganized 1,2-dioleoyl-sn-glycero-3-phospho-rac-(1-glycerol) sodium salt (DOPG) at the aqueous/LC interface. Positively charged, multiple arginine peptides (poly-l-arginine hydrochloride) interacted with negatively charged DOPG at the aqueous/LC interface, which caused reorganization of the phospholipid layer and induced an orientational transition of LCs from a homeotropic to a planar state. As a result, a dark to bright shift in the optical response was observed. Thrombin cleaves poly-l-arginine hydrochloride into peptides. Thus, when thrombin was added, the optical signals generated by the LCs reverted from bright to dark because of the weakened ability of the fragments to induce electrostatic interactions. The limit of detection of the LC-based sensor was 0.25ng/mL (6.7pM) thrombin, and the sensor was fully reusable. The detection limit of our LC-based interface sensor is 600 times lower than that of a previously reported enzyme-linked aptamer assay for the detection of thrombin. Thus, we have established a new, simple thrombin biosensor with high sensitivity and low interference. PMID:24708935

  14. Acetylcholinesterase liquid crystal biosensor based on modulated growth of gold nanoparticles for amplified detection of acetylcholine and inhibitor.

    PubMed

    Liao, Shuzhen; Qiao, Yanan; Han, Wenting; Xie, Zhaoxia; Wu, Zhaoyang; Shen, Guoli; Yu, Ruqin

    2012-01-01

    A novel acetylcholinesterase (AChE) liquid crystal (LC) biosensor based on enzymatic growth of gold nanoparticles (Au NPs) has been developed for amplified detection of acetylcholine (ACh) and AChE inhibitor. In this method, AChE mediates the hydrolysis of acetylthiocholine (ATCl) to form thiocholine, and the latter further reduces AuCl(4)(-) to Au NPs without Au nanoseeds. This process, termed biometallization, leads to a great enhancement in the optical signal of the LC biosensor due to the large size of Au NPs, which can greatly disrupt the orientational arrangement of LCs. On the other hand, the hydrolysis of ATCl is inhibited in the presence of ACh or organophosphate pesticides (OPs, a AChE inhibitor), which will decrease the catalytic growth of Au NPs and, as a result, reduce the orientational response of LCs. On the basis of such an inhibition mechanism, the AChE LC biosensor can be used as an effective way to realize the detection of ACh and AChE inhibitors. The results showed that the AChE LC biosensor was highly sensitive to ACh with a detection limit of 15 μmol/L and OPs with a detection limit of 0.3 nmol/L. This study provides a simple and sensitive AChE LC biosensing approach and offers effective signal enhanced strategies for the development of enzyme LC biosensors. PMID:22148672

  15. Liquid Crystal Based Sensor to Detect Beta-Sheet Formation of Peptides

    NASA Astrophysics Data System (ADS)

    Sadati, Monirosadat; Izmitli Apik, Aslin; Abbott, Nicholas L.; de Pablo, Juan J.

    2015-03-01

    Protein aggregation into amyloid fibrils is involved in the progression of Alzheimer's, typeII diabetes and Huntington's diseases. Although larger aggregates remain important for clinical determination, small oligomers are of great interest due to their potentially toxic nature. It is therefore crucial to develop methods that probe the aggregation process at early stages and in the vicinity of biological membranes. Here, we present a simple method that relies on liquid crystalline materials and a Langmuir monolayer at the aqueous-liquid crystal (LC) interface. The approach is based on the LC's specific response to β-sheet structures, which abound in amyloid fibrils. When the system is observed under polarized light, the fibrils formed by amyloidogenic peptides give rise to the formation of elongated and branched structures in the LCs. Moreover, the PolScope measurements prove that the LCs are predominantly aligned along the fibrils when exposed to a β-sheet forming peptide. In contrast, non-amyloidogenic peptides form ellipsoidal domains of irregularly tilted LCs. This method is capable of reporting aggregation at lipid-aqueous interfaces at nanomolar concentrations of the peptide, and much earlier than commonly used fluorescence-based techniques. We thank Prof. Oleg D. Levrentovich and Young-Ki Kim from the Liquid Crystal Institute of Kent State University for the use of their PolScope instrument. This work was partially supported by the Swiss National Science Foundation (P300P2_151342).

  16. Microbial Manganese Oxidation in Saltmarsh Surface Sediments Using a Leuco Crystal Violet Manganese Oxide Detection Technique

    NASA Astrophysics Data System (ADS)

    Spratt, Henry G.; Siekmann, Ellen C.; Hodson, Robert E.

    1994-01-01

    Microbial manganese (Mn) oxide production in surface sediments of a Georgia saltmarsh was directly measured using an assay involving the oxidation of 4,4',4″-methylidynetris (N,N-dimethylaniline), leuco crystal violet (LCV), by Mn oxides to produce crystal violet. The assay exhibits high specificity for Mn oxides without interference by Mn(II) and is sufficiently sensitive to determine rates of Mn oxidation in surface sediment or saltmarsh creek water suspensions. Sample salinity affects crystal violet absorbance in the 0-25 salinity range and must be corrected for in Mn oxide determinations for estuarine samples of variable salinity. Other oxidants found to oxidize LCV slowly included Cl(I), Cr(III), I(V), Fe(III), and Mn(III), although the sensitivity of the assay for Mn(IV) oxides was found to be seven times greater than for Mn(III), and at least 100 times greater than for any of the other oxidants. Rates of abiotic Mn oxide production in sediment suspensions treated with either sodium azide or formalin, or autoclaved, were much slower than rates determined for untreated sediments. Sodium azide (7·7 mM) inhibited Mn oxide production in these sediment suspensions to rates between 5 and 10% of the rates of Mn oxidation determined for unamended suspensions. Manganese oxidation was highly temperature dependent, with maximal rates on a dry weight basis (8·9 nmol mg dwt -1 h -1), occurring at 60°C, and negligible activity at 100 and 0°C. Rates were also dependent on sample pH, with maximal rates at pH 6·7, decreasing to near 0 as the pH was lowered to approximately 3·0. For Mn(II) concentrations ranging from 9 to 91 μM, rates of Mn oxide production were independent of Mn(II) concentration, while Mn oxide production was inhibited at concentrations greater than 91 μM (e.g. by 25-40% at 450 μM). Rates of microbial Mn oxide production in surface sediment/saltmarsh creek water suspensions incubated under natural conditions of temperature, pH, and Mn

  17. Crystal Diagnostics Xpress™ E7 STEC Kit for the Rapid Multiplex Detection of E. coli O157 and non-O157 Shiga toxin-producing E. coli.

    PubMed

    Zhao, Weidong; Stumpf, Curtis H; Bullard, Brian; Kuzenko, Stephanie; Niehaus, Gary D

    2015-01-01

    The Crystal Diagnostics (CDx) Xpress E7 STEC kit is a rapid and sensitive detection assay for the detection of Escherichia coli O157 and six non-O157 Shiga toxin-producing E. coli (serogroups O26, O45, O1O3, O111, O121, and O145, collectively referred to as STEC) at 1 CFU/325 g of raw ground beef and raw beef trim, or 200 g of spinach. The system comprises an automatic Crystal Diagnostics Xpress System Reader that integrates immunochemical and optical processes for the liquid crystal-based detection of microorganisms, a CDx BioCassette that incorporates antibody-coupled microspheres and liquid crystal for selective identification of the intended microbe, and additional commercially available components. The Crystal Diagnostics Xpress System(TM) combines proprietary liquid crystal technology with antibody-coated paramagnetic microspheres to selectively capture and detect STEC from food matrixes. The Xpress System expeditiously (9.5 h enrichment) provides the sensitivity and specificity of the U. S. Department of Agriculture Food Safety and Inspection Service and the U. S. Food and Drug Administration reference methods in screening as low as 1 STEC CFU/test portion. The inclusivity validation demonstrated detection of 53 of 54 STEC test strains. Shelf life testing of the antibody-coated microspheres and other Crystal Diagnostic consumables indicated that all materials were stable for a minimum of 3 months (ongoing), and lot-to-lot testing demonstrated consistent results between lots (data not shown). The internal and independent laboratory tests demonstrate that the method is rapid and sensitive for screening of the target STEC. PMID:26651567

  18. Bio-functionalized hollow core photonic crystal fibers for label-free DNA detection

    NASA Astrophysics Data System (ADS)

    Candiani, A.; Salloom, Hussein T.; Coscelli, E.; Sozzi, M.; Manicardi, A.; Ahmad, Ahmad K.; Al-Janabi, A. Hadi; Corradini, R.; Picchi, G.; Cucinotta, A.; Selleri, S.

    2014-02-01

    Bio-functionalization of inner surfaces of all silica Hollow Core-Photonic Crystal Fibers (HC-PCF) has been investigated. The approach is based on layer-by-layer self-assembly Peptide Nucleic Acid (PNA) probes, which is an oligonucleotide mimic that is well suited for specific DNA target recognition. Two kinds of HC-PCFs have been considered: a photonic Bragg fiber and a hollow core (HC-1060) fiber. After spectral characterization and internal surface functionalization by using PNA probes, genomic DNA solutions from soy flour were infiltrated into the fibers. The experimental results indicate that hybridization of the complementary strand of target DNA increases the thickness of the silica layer and leads up to the generation of surface modes, resulting in a significant modulation of the transmission spectra. Numerical analysis confirms such behavior, suggesting the possibility to realize biological sensing.

  19. Photonic crystal fiber in-line Mach-Zehnder interferometer for explosive detection.

    PubMed

    Tao, Chuanyi; Wei, Heming; Feng, Wenlin

    2016-02-01

    We report a photonic crystal fiber (PCF) in-line Mach-Zehnder interferometer used as a gas sensor device which exhibits high sensitivity to the explosive trinitrotoluene (TNT). The interferometric sensor head is formed by embedding a segment of large-mode-area/grapefruit PCF between standard single-mode fibers via butt coupling, which produces two small air gaps in between terminated fiber ends with ceramic ferrule connectors as coupling regions, which also serve as inlet/outlet for the gas. The spectral response of the interferometer is investigated in terms of its wavelength spectrum. The selectivity to TNT vapor is achieved by immobilizing a molecular recognition ployallylamine layer on the inner surface of the holey region of the PCF. The TNT-induced variations of the interference fringes are measured and the sensing capability of the proposed sensor is demonstrated experimentally. PMID:26906849

  20. Spectroscopic detection and state preparation of a single praseodymium ion in a crystal.

    PubMed

    Utikal, T; Eichhammer, E; Petersen, L; Renn, A; Götzinger, S; Sandoghdar, V

    2014-04-11

    The narrow optical transitions and long spin coherence times of rare earth ions in crystals make them desirable for a number of applications ranging from solid-state spectroscopy and laser physics to quantum information processing. However, investigations of these features have not been possible at the single-ion level. Here we show that the combination of cryogenic high-resolution laser spectroscopy with optical microscopy allows one to spectrally select individual praseodymium ions in yttrium orthosilicate. Furthermore, this spectral selectivity makes it possible to resolve neighbouring ions with a spatial precision of the order of 10 nm. In addition to elaborating on the essential experimental steps for achieving this long-sought goal, we demonstrate state preparation and read out of the three ground-state hyperfine levels, which are known to have lifetimes of the order of hundred seconds.

  1. Radial Photonic Crystal for detection of frequency and position of radiation sources

    PubMed Central

    Carbonell, J.; Díaz-Rubio, A.; Torrent, D.; Cervera, F.; Kirleis, M. A.; Piqué, A.; Sánchez-Dehesa, J.

    2012-01-01

    Based on the concepts of artificially microstructured materials, i.e. metamaterials, we present here the first practical realization of a radial wave crystal. This type of device was introduced as a theoretical proposal in the field of acoustics, and can be briefly defined as a structured medium with radial symmetry, where the constitutive parameters are invariant under radial geometrical translations. Our practical demonstration is realized in the electromagnetic microwave spectrum, because of the equivalence between the wave problems in both fields. A device has been designed, fabricated and experimentally characterized. It is able to perform beam shaping of punctual wave sources, and also to sense position and frequency of external radiators. Owing to the flexibility offered by the design concept, other possible applications are discussed. PMID:22870387

  2. Spectroscopic detection and state preparation of a single praseodymium ion in a crystal.

    PubMed

    Utikal, T; Eichhammer, E; Petersen, L; Renn, A; Götzinger, S; Sandoghdar, V

    2014-01-01

    The narrow optical transitions and long spin coherence times of rare earth ions in crystals make them desirable for a number of applications ranging from solid-state spectroscopy and laser physics to quantum information processing. However, investigations of these features have not been possible at the single-ion level. Here we show that the combination of cryogenic high-resolution laser spectroscopy with optical microscopy allows one to spectrally select individual praseodymium ions in yttrium orthosilicate. Furthermore, this spectral selectivity makes it possible to resolve neighbouring ions with a spatial precision of the order of 10 nm. In addition to elaborating on the essential experimental steps for achieving this long-sought goal, we demonstrate state preparation and read out of the three ground-state hyperfine levels, which are known to have lifetimes of the order of hundred seconds. PMID:24722142

  3. Spectroscopic detection and state preparation of a single praseodymium ion in a crystal

    NASA Astrophysics Data System (ADS)

    Utikal, T.; Eichhammer, E.; Petersen, L.; Renn, A.; Götzinger, S.; Sandoghdar, V.

    2014-04-01

    The narrow optical transitions and long spin coherence times of rare earth ions in crystals make them desirable for a number of applications ranging from solid-state spectroscopy and laser physics to quantum information processing. However, investigations of these features have not been possible at the single-ion level. Here we show that the combination of cryogenic high-resolution laser spectroscopy with optical microscopy allows one to spectrally select individual praseodymium ions in yttrium orthosilicate. Furthermore, this spectral selectivity makes it possible to resolve neighbouring ions with a spatial precision of the order of 10 nm. In addition to elaborating on the essential experimental steps for achieving this long-sought goal, we demonstrate state preparation and read out of the three ground-state hyperfine levels, which are known to have lifetimes of the order of hundred seconds.

  4. Refocusing resolution based on negative refractive-photonic crystal group with Ag defects for target detection and imaging

    NASA Astrophysics Data System (ADS)

    Lian, Yingfei; Zhu, Na; Fang, Yuntuan; Sun, Jiwen; Chen, Junlv; Qian, Huili

    2015-03-01

    Negative refractive-photonic crystal (NR-PC) lenses that can exceed the diffraction limit of focus resolution for imaging and target detection in the near field have gotten more and more special attention in recent years. Three flat lens groups with Ag defects based on NR-PC are designed, and the focusing imaging in the NR-PC three flat lens groups is concluded with the extension of Snell's law, and the influence on the resolution for a target detection dynamic scanning scheme is simulated by using the finite difference time domain method. An optimal-doped structure with Ag defects is achieved by different simulation combinations. The refocusing resolution 0.18834λ is achieved in the optimal structure and there is approximately a 0.06806λ improvement in the refocusing resolution compared to those undoped with Ag (0.2564λ) it also possesses distinct smaller side-lobes than a single flat lens doped with Ag. This means the optimal detecting ability for the three NR-PC flat lens groups with Ag defects is more improved than that for a single undoped and doped with Ag. This is significant for the perfect imaging being achieved for a particle structure.

  5. Nanoporous gold leaf as a signal amplification agent for the detection of VOCs with a quartz crystal microbalance.

    PubMed

    Zhang, Lu; Liu, Yuan; Song, Han; Huang, Bintong; Ye, Bang-Ce; Li, Yingchun

    2016-08-01

    In this work, a novel sensing framework coupling nanoporous gold leaf (NPGL) and sensitive materials on a quartz crystal microbalance (QCM) sensor was developed for the detection of volatile organic compounds (VOCs). A bi-layer structure was established through a two-step modification process, where NPGL served as a loading platform to anchor more sensitive materials and provide a larger surface area. Sensitive materials for different target analytes (ethanol, benzene and n-heptane) were optimized, as well as the selection of the most suitable NPGL. The morphology of the bi-layer was characterized and the sensing performance, including the detection range, response time, reversibility, stability, etc., was investigated. The thermodynamics and kinetics of the gas adsorption process were studied by employing several classical models. It was found that the adsorption of the tested VOCs was more accurately represented using the Freundlich isotherm and the adsorption kinetics of these VOCs fitted well with pseudo second-order kinetics. The results of on-line monitoring demonstrated admirable sensing properties, fully indicating that the QCM sensor modified with a composite layer of sensitive material/NPGL has promising application prospects for real-time detection. PMID:27280177

  6. A cationic surfactant-decorated liquid crystal sensing platform for simple and sensitive detection of acetylcholinesterase and its inhibitor.

    PubMed

    Wang, Yi; Hu, Qiongzheng; Guo, Yongxian; Yu, Li

    2015-10-15

    In this paper, construction of the liquid crystal (LC)-based sensing platform for simple and sensitive detection of acetylcholinesterase (AChE) and its inhibitor using a cationic surfactant-decorated LC interface was demonstrated. A change of the optical images of LCs from bright to dark appearance was observed when the cationic surfactant, myristoylcholine chloride (Myr), was transferred onto the aqueous/LC interface, due to the formation of a stable surfactant monolayer at the interface. A dark-to-bright change of the optical appearance was then observed when AChE was transferred onto the Myr-decorated LC interface. The sensitivity of this new type of LC-based sensor is 3 orders of magnitude higher in the serum albumin solution than that only in the buffer solution. Noteworthy is that the AChE LC sensor shows a very high sensitivity for the detection of the enzyme inhibitor, which is around 1 fM. The constructed low-cost LC-based sensor is quite simple and convenient, showing high promise for label-free detection of AChE and its inhibitors. PMID:25957073

  7. Ultrasensitive Detection of Cymbidium Mosaic Potexvirus Using a Single-Wall Carbon Nanotube-Functionalized Quartz Crystal Microbalance

    NASA Astrophysics Data System (ADS)

    Chen, Yu-Shiun; Hung, Yao-Ching; Chiou, Jin-Chern; Wang, Hui-Liang; Huang, Hung-Shu; Huang, Li-Chia; Huang, Guewha Steven

    2010-10-01

    We have developed an ultrasensitive, convenient, real-time platform for detecting Cymbidium mosaic potexvirus (CymMV) based on single-wall carbon nanotube (SWNT)-functionalized quartz crystal microbalance (QCM) sensors. Functionalization was achieved by coating the QCM electrode with SWNTs, followed by 1,1'-carbonyldiimidazole-activated Tween 20 (CDI-Tween 20) modification and conjugation of antibodies. Sensitivity was enhanced from 2.18 to 11.5 Hz ng-1 when 0.1 µg mL-1 CymMV was applied. The low limit of detection of SWNT-functionalized QCM sensors was improved from 2.08 to 0.502 ng. The SWNT-functionalized QCM sensor was successfully used to quantify the amount of CymMV contained in infected orchid leaves. Compared to enzyme-linked immunosorbent assay (ELISA), SWNT-functionalized QCM sensors are fast, economical, and ultra-sensitive, with comparable sensitivities. The current study demonstrates the application of QCM sensors as a convenient platform to detect and quantify CymMV.

  8. Development of molecularly imprinted polymer films used for detection of profenofos based on a quartz crystal microbalance sensor.

    PubMed

    Gao, Na; Dong, Jianwei; Liu, Ming; Ning, Baoan; Cheng, Chaonan; Guo, Chun; Zhou, Caihong; Peng, Yuan; Bai, Jialei; Gao, Zhixian

    2012-03-01

    A quartz crystal microbalance (QCM) sensor based on molecularly imprinted ultra-thin films was developed for detecting profenofos in real samples. Films prepared by physical entrapment (MIP-A) and in situ self-assembly (MIP-B) were compared. The results indicated that the best sensing signal was obtained through the in situ self-assembly method. The QCM sensor chip was pretreated with 11-mercaptoundecanoic acid (MUA) to form a self-assembled monolayer (SAM), and then polymer films were immobilized directly on the SAM using surface-initiated radical polymerization. In this paper, all detection experiments were taken in air. The reaction was processed in solution, and the electrode was washed with deionized water and dried with N(2) before QCM measurement. The film was characterized by a scanning electron microscope (SEM), AC impedance and cyclic voltammetry. Analysis of the QCM response in the presence of different concentrations of profenofos showed a good linear correlation during 1.0 × 10(-8) to 1.0 × 10(-5) mg mL(-1) (y = 5log x + 42.5, R = 0.9960) and 1.0 × 10(-5) to 1.0 × 10(-3) mg mL(-1) (y = 25.86log x + 146, R = 0.9959), respectively. The MIP-QCM sensor was used to detect profenofos in tap water, and showed good recovery and repeatability. PMID:22262283

  9. Direct detection of transcription factors in cotyledons during seedling development using sensitive silicon-substrate photonic crystal protein arrays.

    PubMed

    Jones, Sarah I; Tan, Yafang; Shamimuzzaman, Md; George, Sherine; Cunningham, Brian T; Vodkin, Lila

    2015-03-01

    Transcription factors control important gene networks, altering the expression of a wide variety of genes, including those of agronomic importance, despite often being expressed at low levels. Detecting transcription factor proteins is difficult, because current high-throughput methods may not be sensitive enough. One-dimensional, silicon-substrate photonic crystal (PC) arrays provide an alternative substrate for printing multiplexed protein microarrays that have greater sensitivity through an increased signal-to-noise ratio of the fluorescent signal compared with performing the same assay upon a traditional aminosilanized glass surface. As a model system to test proof of concept of the silicon-substrate PC arrays to directly detect rare proteins in crude plant extracts, we selected representatives of four different transcription factor families (zinc finger GATA, basic helix-loop-helix, BTF3/NAC [for basic transcription factor of the NAC family], and YABBY) that have increasing transcript levels during the stages of seedling cotyledon development. Antibodies to synthetic peptides representing the transcription factors were printed on both glass slides and silicon-substrate PC slides along with antibodies to abundant cotyledon proteins, seed lectin, and Kunitz trypsin inhibitor. The silicon-substrate PC arrays proved more sensitive than those performed on glass slides, detecting rare proteins that were below background on the glass slides. The zinc finger transcription factor was detected on the PC arrays in crude extracts of all stages of the seedling cotyledons, whereas YABBY seemed to be at the lower limit of their sensitivity. Interestingly, the basic helix-loop-helix and NAC proteins showed developmental profiles consistent with their transcript patterns, indicating proof of concept for detecting these low-abundance proteins in crude extracts. PMID:25635113

  10. Liquid-Crystal Biosensor Based on Nickel-Nanosphere-Induced Homeotropic Alignment for the Amplified Detection of Thrombin.

    PubMed

    Zhao, Dongyu; Peng, Yi; Xu, Lihong; Zhou, Wei; Wang, Qian; Guo, Lin

    2015-10-28

    A new liquid-crystal (LC)-based sensor operated by nickel nanosphere (NiNS)-induced homeotropic alignment for the label-free monitoring of thrombin was reported. When doped with NiNSs, a uniform vertical orientation of 4-cyano-4'-pentylbiphenyl (5CB) was easily obtained. A sandwich system of aptamer/thrombin/aptamer-functionalized gold nanoparticles (AuNPs) was fabricated, and AuNPs-aptamer conjugation caused the disruption of the 5CB orientation, leading to an obvious change of the optical appearance from a dark to a bright response to thrombin concentrations from 0.1 to 100 nM. This design also allowed quantitative detection of the thrombin concentration. This distinctive and sensitive thrombin LC sensor provides a new principle for building LC-sensing systems.

  11. Planar scanning method for detecting refraction characteristics of two-dimensional photonic quasi-crystal wedge-shaped prisms.

    PubMed

    Liu, Jianjun; Tan, Wei; Liu, Exian; Hu, Haili; Fan, Zhigang; Zhang, Tianhua; Zhang, Xiong

    2016-05-01

    In this study, a planar scanning method is proposed. This novel method adapts two monitors moving along double planar tracks that can be used to detect refraction characteristics of two-dimensional (2D) photonic quasi-crystal (PQC) wedge-shaped prisms. Refraction of a decagonal Penrose-type PQC prism is analyzed for a given incident beam and two polarization modes at different incident positions in the prism using this method. Refraction from the prism is irregular, indicating that nonuniformity in the arrangement of scatterers in the prism causes Bragg-like scattering irregularities. Numerical results show that this method can be used for guiding the design of a 2D PQC prism and for the analysis of its refraction characteristics. PMID:27140896

  12. Label-free detection of glycated haemoglobin in human blood using silicon-based photonic crystal nanocavity biosensor

    NASA Astrophysics Data System (ADS)

    Olyaee, Saeed; Seifouri, Mahmood; Mohsenirad, Hamideh

    2016-07-01

    In this paper, we describe a two-dimensional photonic crystal-based biosensor that consists of a waveguide and a nanocavity with high sensitivity. A new method is employed for increasing sensitivity of the biosensor. The simulation results show that biosensor is highly sensitive to the refractive index (RI) variations due to injected biomaterials, like glycated haemoglobin, into the sensing surface. The proposed biosensor is designed for the wavelength range of 1514.4-1896.3 nm. The sensitivity and the quality factor are calculated to be 3000 and 272.43 nm/RIU, respectively. The designed structure can detect a 0.002 change in the RI via resonant wavelength shift of 0.9 nm. The band diagram and transmission spectra are computed using plane wave expansion and finite difference time domain methods.

  13. Liquid-Crystal Biosensor Based on Nickel-Nanosphere-Induced Homeotropic Alignment for the Amplified Detection of Thrombin.

    PubMed

    Zhao, Dongyu; Peng, Yi; Xu, Lihong; Zhou, Wei; Wang, Qian; Guo, Lin

    2015-10-28

    A new liquid-crystal (LC)-based sensor operated by nickel nanosphere (NiNS)-induced homeotropic alignment for the label-free monitoring of thrombin was reported. When doped with NiNSs, a uniform vertical orientation of 4-cyano-4'-pentylbiphenyl (5CB) was easily obtained. A sandwich system of aptamer/thrombin/aptamer-functionalized gold nanoparticles (AuNPs) was fabricated, and AuNPs-aptamer conjugation caused the disruption of the 5CB orientation, leading to an obvious change of the optical appearance from a dark to a bright response to thrombin concentrations from 0.1 to 100 nM. This design also allowed quantitative detection of the thrombin concentration. This distinctive and sensitive thrombin LC sensor provides a new principle for building LC-sensing systems. PMID:26458050

  14. Planar scanning method for detecting refraction characteristics of two-dimensional photonic quasi-crystal wedge-shaped prisms.

    PubMed

    Liu, Jianjun; Tan, Wei; Liu, Exian; Hu, Haili; Fan, Zhigang; Zhang, Tianhua; Zhang, Xiong

    2016-05-01

    In this study, a planar scanning method is proposed. This novel method adapts two monitors moving along double planar tracks that can be used to detect refraction characteristics of two-dimensional (2D) photonic quasi-crystal (PQC) wedge-shaped prisms. Refraction of a decagonal Penrose-type PQC prism is analyzed for a given incident beam and two polarization modes at different incident positions in the prism using this method. Refraction from the prism is irregular, indicating that nonuniformity in the arrangement of scatterers in the prism causes Bragg-like scattering irregularities. Numerical results show that this method can be used for guiding the design of a 2D PQC prism and for the analysis of its refraction characteristics.

  15. Label-Free Detection of Soybean Rust Spores using Photonic Crystal Biosensors

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soybean rust, caused by the fungus Phakopsora pachyrhizi, is one of the most devastating foliar diseases affecting soybeans grown worldwide. The disease was reported for the first time in the United States in 2004. Early spore detection, prior to the appearance of visible symptoms, is critical to ef...

  16. Design of photonic crystal based ring resonator for detection of different blood constituents

    NASA Astrophysics Data System (ADS)

    Sharma, Poonam; Sharan, Preeta

    2015-08-01

    In this paper a photonic crystal based ring resonator structure (PCRR) which can sense different bio-constituents in blood in the wavelength range of 1530-1565 nm for biomedical applications has been successfully demonstrated. Simulation and analysis has been done for Biotin-Streptavidin, Bovine Serum Albumin, Cytop (polymer), Ethanol, Glucose solution (40gm/100 ml), Hemoglobin, Blood Plasma, Polyacrylamide and Sylgard184. Finite Difference Time Domain (FDTD) method has been used for the analysis. MEEP (MIT Electromagnetic Equation Propagation) and MPB (MIT Photonic Bands) simulation tools have been used for modeling and designing of PCRR and IPKISS software framework has been used for generation of mask design which can be used for the fabrication of the PCRR sensor. The optical properties of different bio-constituents are studied and the normalized transmitted output power, transmission wavelength and Q factor have been observed for different blood-constituents which can be used for blood analysis.It has been observed that for little change in dielectric constant (ɛ) according to the blood-constituent taken there will be a moderate shift in the transmitted output power, transmission wavelength and quality factor and hence it acts as a sensor. This indicates that it is highly sensitive even for little change in refractive index. Our designed sensor has achieved sensitivity of 343 nm/RIU.

  17. A novel assay for detecting canine parvovirus using a quartz crystal microbalance biosensor.

    PubMed

    Kim, Yong Kwan; Lim, Seong-In; Choi, Sarah; Cho, In-Soo; Park, Eun-Hye; An, Dong-Jun

    2015-07-01

    Rapid and accurate diagnosis is crucial to reduce both the shedding and clinical signs of canine parvovirus (CPV). The quartz crystal microbalance (QCM) is a new tool for measuring frequency changes associated with antigen-antibody interactions. In this study, the QCM biosensor and ProLinker™ B were used to rapidly diagnosis CPV infection. ProLinker™ B enables antibodies to be attached to a gold-coated quartz surface in a regular pattern and in the correct orientation for antigen binding. Receiver operating characteristics (ROC) curves were used to set a cut-off value using reference CPVs (two groups: one CPV-positive and one CPV-negative). The ROC curves overlapped and the point of intersection was used as the cut-off value. A QCM biosensor with a cut-off value of -205 Hz showed 95.4% (104/109) sensitivity and 98.0% (149/152) specificity when used to test 261 field fecal samples compared to PCR. In conclusion, the QCM biosensor described herein is eminently suitable for the rapid diagnosis of CPV infection with high sensitivity and specificity. Therefore, it is a promising analytical tool that will be useful for clinical diagnosis, which requires rapid and reliable analyses.

  18. Silicon photonic crystal microarrays for high throughput label-free detection of lung cancer cell line lysates with sensitivity and specificity

    NASA Astrophysics Data System (ADS)

    Chakravarty, Swapnajit; Lai, Wei-Cheng; Zou, Yi; Gemmill, Robert M.; Chen, Ray T.

    2013-03-01

    Detection of biomolecules on microarrays based on label-free on-chip optical biosensors is very attractive since this format avoids complex chemistries caused by steric hindrance of labels. Application areas include the detection of cancers and allergens, and food-borne pathogens to name a few. We have demonstrated photonic crystal microcavity biosensors with high sensitivity down to 1pM concentrations (67pg/ml). High sensitivities were achieved by slow light engineering which reduced the radiation loss and increased the stored energy in the photonic crystal microcavity resonance mode. Resonances with high quality factor Q~26,760 in liquid ambient, coupled with larger optical mode volumes allowed enhanced interaction with the analyte biomolecules which resulted in sensitivities down to 10 cells per micro-liter to lung cancer cell lysates. The specificity of detection was ensured by multiplexed detections from multiple photonic crystal microcavities arrayed on the arms of a multimode interference power splitter. Specific binding interactions and control experiments were performed simultaneously at the same instant of time with the same 60 microliter sample volume. Specificity is further ensured by sandwich assay methods in the multiplexed experiment. Sandwich assay based amplification increased the sensitivity further resulting in the detection of lung cancer cell lysates down to concentrations of 2 cells per micro-liter. The miniaturization enabled by photonic crystal biosensors coupled with waveguide interconnected layout thus offers the potential of high throughput proteomics with high sensitivity and specificity.

  19. In situ and fast detection of single-walled carbon nanotubes by using DNA mediated aggregation method and quartz crystal microbalance

    NASA Astrophysics Data System (ADS)

    Jang, Kuewhan; Park, Jinsung; Lee, Sangmyung; You, Juneseok; Park, Chanho; Lee, Jaeryung; Park, Woonghwi; Yun, Jinsu; Ahn, Sanghyun; Na, Sungsoo

    2015-07-01

    Carbon nanotubes (CNTs) have attracted great interest from scientific interest to industrial areas. Due to the toxicity effect of CNTs, assessment methods for CNTs are one of the noticeable issues. In this work, we report the in situ and fast detection of single-walled carbon nanotubes (SWCNTs) by using a quartz crystal microbalance. The detection is based on DNA hybridization between the DNA on a quartz electrode and the DNA of aggregated SWCNTs. It is shown that our detection tool is capable of the in situ and fast detection of 5 min with the limit of detection (LOD) of 10 ng ml-1 in distilled water. Furthermore, our detection tool is able to detect SWCNTs in a real practical sample of tap water with the LOD of 100 ng ml-1. Our work sheds light on a direct monitoring tool that could detect and assess the toxicity of SWCNTs in a real environment.

  20. Optical detection of ultrasound using AFC-based quantum memory technique in cryogenic rare earth ion doped crystals

    NASA Astrophysics Data System (ADS)

    Taylor, Luke R.; McAuslan, David L.; Longdell, Jevon J.

    2013-03-01

    We present results of a novel and highly sensitive technique for the optical detection of ultrasound using the selective storage of frequency shifted photons in an inherently highly efficient and low noise atomic frequency comb (AFC) based quantum memory. The ultrasound `tagged' optical sidebands are absorbed within a pair of symmetric AFCs, generated via optical pumping in a Pr3+:Y2SiO5 sample (tooth separation Δ = 150 kHz, comb finesse fc ~ 2 and optical depth αL ~ 2), separated by twice the ultrasound modulation frequency (1.5 MHz) and centered on either side of a broad spectral pit (1.7 MHz width) allowing transmission of the carrier. The stored sidebands are recovered with 10-20% efficiency as a photon echo (as defined by the comb parameters), and we demonstrate a record 49 dB discrimination between the sidebands and the carrier pulse, high discrimination being important for imaging tissues at depth. We further demonstrate detector limited discrimination (~29 dB) using a highly scattered beam, confirming that the technique is immune to speckle decorrelation. We show that it also remains valid in the case of optically thin samples, and thus represents a significant improvement over other ultrasound detection methods based on rare-earth-ion-doped crystals. These results strongly suggest the suitability of our technique for high-resolution non-contact real-time imaging of biological tissues.

  1. Molecular imprinted opal closest-packing photonic crystals for the detection of trace 17β-estradiol in aqueous solution.

    PubMed

    Sai, Na; Wu, Yuntang; Sun, Zhong; Huang, Guowei; Gao, Zhixian

    2015-11-01

    A novel opal closest-packing (OCP) photonic crystal (PC) was prepared by the introduction of molecular imprinting technique into the OCP PC. This molecular imprinted (MI)-OCP PC was fabricated via a vertical convective self-assembly method using 17β-estradiol (E2) as template molecules for monitoring E2 in aqueous solution. Morphology characterization showed that the MI-OCP PC possessed a highly ordered three-dimensional (3D) periodically-ordered structure, showing the desired structural color. The proposed PC material displayed a reduced reflection intensity when detecting E2 in water environment, because the molecular imprinting recognition events make the optical characteristics of PC change. The Bragg diffraction intensity decreased by 19.864 a.u. with the increase of E2 concentration from 1.5 ng mL(-1) to 364.5 ng mL(-1) within 6 min, whereas there were no obvious peak intensity changes for estriol, estrone, cholesterol, testosterone and diethylstilbestrol, indicating that the MI-OCP PC had selective and rapid response for E2 molecules. The adsorption results showed that the OCP structure and homogeneous layers were created in the MI-OCP PC with higher adsorption capacity. Thus, it was learned the MI-OCP PC is a simple prepared, sensitive, selective, and easy operative material, which shows promising use in routine supervision for residue detection in food and environment. PMID:26452805

  2. Molecular imprinted opal closest-packing photonic crystals for the detection of trace 17β-estradiol in aqueous solution.

    PubMed

    Sai, Na; Wu, Yuntang; Sun, Zhong; Huang, Guowei; Gao, Zhixian

    2015-11-01

    A novel opal closest-packing (OCP) photonic crystal (PC) was prepared by the introduction of molecular imprinting technique into the OCP PC. This molecular imprinted (MI)-OCP PC was fabricated via a vertical convective self-assembly method using 17β-estradiol (E2) as template molecules for monitoring E2 in aqueous solution. Morphology characterization showed that the MI-OCP PC possessed a highly ordered three-dimensional (3D) periodically-ordered structure, showing the desired structural color. The proposed PC material displayed a reduced reflection intensity when detecting E2 in water environment, because the molecular imprinting recognition events make the optical characteristics of PC change. The Bragg diffraction intensity decreased by 19.864 a.u. with the increase of E2 concentration from 1.5 ng mL(-1) to 364.5 ng mL(-1) within 6 min, whereas there were no obvious peak intensity changes for estriol, estrone, cholesterol, testosterone and diethylstilbestrol, indicating that the MI-OCP PC had selective and rapid response for E2 molecules. The adsorption results showed that the OCP structure and homogeneous layers were created in the MI-OCP PC with higher adsorption capacity. Thus, it was learned the MI-OCP PC is a simple prepared, sensitive, selective, and easy operative material, which shows promising use in routine supervision for residue detection in food and environment.

  3. Chemically Selective Coated Quartz Crystal Microbalance (QCM) Array for Detection of Volatile Organic Chemicals

    SciTech Connect

    Bohuszewicz, T.V.; Frye-Mason, G.C.; Martin, S.J.; Osbourn, G.C. Bartholomew, J.W.; Schneider, T.W.; Spates, J.J.

    1998-11-04

    Liquid flow cells have been fabricated to prepare an array of QCMS operating simultaneously for detection and identification of VOCS in water. TWO signals, a tlequency response and a damping voltage response, were obtained per resonator. A blank QCM was used as a reference to account for changes in liquid density and viscosity. Nine different polymer coatings applied using a spin coat technique have been examined for VOC response under liquid flow conditions. A matrix of three classes of VOCS were examined for each coating with four chemicals in each class. The three classes of VOCS are polar, nonpolar and chlorinated. A pattern recognition technique, called visually empirical region of influence (VERI), was used to cluster the responses in n-dimensional space. Chemicals within a class varying by only one methyl group (e.g., toluene and xylene) are easily discriminated using only two different coatings with three different QCM responses. All chemicak were easily separated and detected with a total of 5 films and 6 responses with >99% accuracy.

  4. Nanomechanical Detection of Magnetic Hysteresis of a Single-crystal Yttrium Iron Garnet Micromagnetic Disk

    NASA Astrophysics Data System (ADS)

    Losby, Joseph; Diao, Zhu; Burgess, Jacob; Compton, Shawn; Fani Sani, Fatemeh; Firdous, Tayyaba; Vick, Douglas; Belov, Miro; Hiebert, Wayne; Freeman, Mark

    2013-03-01

    A micromagnetic disk was milled from a monocrystalline yttrium iron garnet film using a focused ion beam and micromanipulated onto a nanoscale torsional resonator. Nanomechanical torque magnetometry results show a unipolar magnetic hysteresis characteristic of a magnetic vortex state. Landau-Lifshitz-Gilbert-based micromagnetic simulations of the disk show a rich, flux-enclosed, three-dimensional domain structure. On the top and bottom faces of the disk, a skewed vortex state exists with a very small core. The core region extends through the thickness of the disk with a smooth variation in core diameter reaching a maximum along the midplane of the disk. The single crystalline nature of the disk lends to an observed absence of Barkhausen-like steps in the magnetization-versus-field curves, qualitatively different in comparison to the magnetometry results of an individual polycrystalline permalloy microdisk. Prospects for the mechanical detection of spin dynamical modes in these structures will also be discussed.

  5. A quartz crystal microbalance cell biosensor: detection of microtubule alterations in living cells at nM nocodazole concentrations.

    PubMed

    Marx, K A; Zhou, T; Montrone, A; Schulze, H; Braunhut, S J

    2001-12-01

    The quartz crystal microbalance (QCM) was used to create a piezoelectric biosensor utilizing living endothelial cells (ECs) as the biological signal transduction element. ECs adhere to the hydrophilically treated gold QCM surface under growth media containing serum. At 24 h following cell addition, calibration curves were constructed relating the steady state Deltaf and DeltaR shift values observed to the numbers of electronically counted cells requiring trypsinization to be removed from the surface. We then utilized this EC QCM biosensor for the detection of the effect of [nocodazole] on the steady state Deltaf and DeltaR shift values. Nocodazole, a known microtubule binding drug, alters the cytoskeletal properties of living cells. At the doses used in these studies (0.11-15 microM), nocodazole, in a dose dependent fashion, causes the depolymerization of microtubules in living cells. This leads a monolayer of well spread ECs to gradually occupy a smaller area, lose cell to cell contact, exhibit actin stress fibers at the cell periphery and acquire a rounded cell shape. We observed the negative Deltaf shift values and the positive DeltaR shift values to increase significantly in magnitude over a 4-h incubation period following nocodazole addition, in a dose dependent fashion, with a transition midpoint of 900 nM. Fluorescence microscopy of the ECs, fixed on the gold QCM surface and stained for actin, demonstrated that the shape and cytoskeleton of ECs were affected by as little as 330 nM nocodazole. These results indicate that the EC QCM biosensor can be used for the study of EC attachment and to detect EC cytoskeletal alterations. We suggest the potential of this cellular biosensor for the real time identification or screening of all classes of biologically active drugs or biological macromolecules that affect cellular attachment, regardless of their molecular mechanism of action.

  6. High-power terahertz-wave generation using DAST crystal and detection using mid-infrared powermeter.

    PubMed

    Suizu, Koji; Miyamoto, Katsuhiko; Yamashita, Tomoyu; Ito, Hiromasa

    2007-10-01

    The exact power output of a table-top-sized terahertz (THz)-wave source using a nonlinear optical process has not been clarified because detectors for these experiments [Si bolometer, deuterated triglycine sulfate (DTGS), etc.] are not calibrated well. On the other hand, powermeters for the mid-infrared (mid-IR) region are well established and calibrated. We constructed a high-power dual-wavelength optical parametric oscillator with two KTP crystals as a light source for difference frequency generation. The obtained powers of dual waves were 21 mJ at ~1300 nm, ten times higher than that of the previous measurement. The device provides high-power THz-wave generation with ~100 times greater output power than that reported in previous works. A well-calibrated mid-IR powermeter at ~27 THz detected the generated THz wave; its measured energy was 2.4 microJ. Although the powermeter had no sensitivity in the lower-frequency range (below 20 THz), the pulse energy at such a low-frequency region was estimated in reference to the output spectrum obtained using a DTGS detector: the energy would be from about the submicrojoule level to a few microjoules in the THz-wave region.

  7. Using MRI to detect and differentiate calcium oxalate and calcium hydroxyapatite crystals in air-bubble-free phantom.

    PubMed

    Mustafi, Devkumar; Fan, Xiaobing; Peng, Bo; Foxley, Sean; Palgen, Jeremy; Newstead, Gillian M

    2015-12-01

    Calcium oxalate (CaOX) crystals and calcium hydroxyapatite (CaHA) crystals were commonly associated with breast benign and malignant lesions, respectively. In this research, CaOX (n = 6) and CaHA (n = 6) crystals in air-bubble-free agarose phantom were studied and characterized by using MRI at 9.4 T scanner. Calcium micro-crystals, with sizes that ranged from 200 to 500 µm, were made with either 99% pure CaOX or CaHA powder and embedded in agar to mimic the dimensions and calcium content of breast microcalcifications in vivo. MRI data were acquired with high spatial resolution T2-weighted (T2W) images and gradient echo images with five different echo times (TEs). The crystal areas were determined by setting the threshold relative to agarose signal. The ratio of crystal areas was calculated by the measurements from gradient echo images divided by T2W images. Then the ratios as a function of TE were fitted with the radical function. The results showed that the blooming artifacts due to magnetic susceptibility between agar and CaHA crystals were more than twice as large as the susceptibility in CaOX crystals (p < 0.05). In addition, larger bright rings were observed on gradient echo images around CaHA crystals compared to CaOX crystals. Our results suggest that MRI may provide useful information regarding breast microcalcifications by evaluating the apparent area of crystal ratios obtained between gradient echo and T2W images.

  8. Growth of high quality mercurous halide single crystals by physical vapor transport method for AOM and radiation detection applications

    NASA Astrophysics Data System (ADS)

    Amarasinghe, Priyanthi M.; Kim, Joo-Soo; Chen, Henry; Trivedi, Sudhir; Qadri, Syed B.; Soos, Jolanta; Diestler, Mark; Zhang, Dajie; Gupta, Neelam; Jensen, Janet L.; Jensen, James

    2016-09-01

    Single crystals of mercurous halide were grown by physical vapor transport method (PVT). The orientation and the crystalline quality of the grown crystals were determined using high resolution x-ray diffraction (HRXRD) technique. The full width at half maximum (FWHM) of the grown mercurous bromide crystals was measured to be 0.13 degrees for (004) reflection, which is the best that has been achieved so far for PVT grown mercurous halide single crystals. The extended defects of the crystals were also analyzed using high resolution x-ray diffraction topography. Preliminary studies were carried out to evaluate the performance of the crystals on acousto-optic modulator (AOM) and gamma-ray detector applications. The results indicate the grown mercurous halide crystals are excellent materials for acousto-optic modulator device fabrication. The diffraction efficiencies of the fabricated AOM device with 1152 and 1523 nm wavelength lasers polarizing parallel to the acoustic wave were found to be 35% and 28%, respectively. The results also indicate the grown crystals are a promising material for gamma-ray detector application with a very high energy resolution of 1.86% FWHM.

  9. Detection of high energy muons with sub-20 ps timing resolution using L(Y)SO crystals and SiPM readout

    NASA Astrophysics Data System (ADS)

    Benaglia, A.; Gundacker, S.; Lecoq, P.; Lucchini, M. T.; Para, A.; Pauwels, K.; Auffray, E.

    2016-09-01

    Precise timing capability will be a key aspect of particle detectors at future high energy colliders, as the time information can help in the reconstruction of physics events at the high collision rate expected there. Other than being used in detectors for PET, fast scintillating crystals coupled to compact Silicon Photomultipliers (SiPMs) constitute a versatile system that can be exploited to realize an ad-hoc timing device to be hosted in a larger high energy physics detector. In this paper, we present the timing performance of LYSO:Ce and LSO:Ce codoped 0.4% Ca crystals coupled to SiPMs, as measured with 150 GeV muons at the CERN SPS H2 extraction line. Small crystals, with lengths ranging from 5 mm up to 30 mm and transverse size of 2 × 2mm2 or 3 × 3mm2 , were exposed to a 150 GeV muon beam. SiPMs from two different companies (Hamamatsu and FBK) were used to detect the light produced in the crystals. The best coincidence time resolution value of (14.5 ± 0.5) ps , corresponding to a single-detector time resolution of about 10 ps, is demonstrated for 5 mm long LSO:Ce,Ca crystals coupled to FBK SiPMs, when time walk corrections are applied.

  10. Post-column reaction for simultaneous analysis of chromatic and leuco forms of malachite green and crystal violet by high-performance liquid chromatography with photometric detection

    USGS Publications Warehouse

    Allen, J.L.; Meinertz, J.R.

    1991-01-01

    The chromatic and leuco forms of malachite green and crystal violet were readily separated and detected by a sensitive and selective high-performance liquid chromatographic procedure. The chromatic and leuco forms of the dyes were separated within 11 min on a C18 column with a mobile phase of 0.05 M sodium acetate and 0.05 M acetic acid in water (19%) and methanol (81%). A reaction chamber, containing 10% PbO2 in Celite 545, was placed between the column and the spectrophotometric detector to oxidize the leuco forms of the dyes to their chromatic forms. Chromatic and leuco malachite green were quantified by their absorbance at 618 nm; and chromatic and leuco Crystal Violet by their absorbance at 588 nm. Detection limits for chromatic and leuco forms of both dyes ranged from 0.12 to 0.28 ng. A linear range of 1 to 100 ng was established for both forms of the dyes.

  11. SERS active Ag encapsulated Fe@SiO2 nanorods in electromagnetic wave absorption and crystal violet detection.

    PubMed

    Senapati, Samarpita; Srivastava, Suneel Kumar; Singh, Shiv Brat; Kulkarni, Ajit R

    2014-11-01

    The present work is focused on the preparation of Fe nanorods by the chemical reduction of FeCl3 (aq) using NaBH4 in the presence of glycerol as template followed by annealing of the product at 500°C in the presence of H2 gas flow. Subsequently, its surface has been modified by silica followed by silver nanoparticles to form silica coated Fe (Fe@SiO2) and Ag encapsulated Fe@SiO2 nanostructure employing the Stöber method and silver mirror reaction respectively. XRD pattern of the products confirmed the formation of bcc phase of iron and fcc phase of silver, though silica remained amorphous. FESEM images established the growth of iron nanorods from the annealed product and also formation of silica and silver coating on its surface. The appearance of the characteristics bands in FTIR confirmed the presence of SiO2 on the Fe surface. Magnetic measurements at room temperature indicated the ferromagnetic behavior of as prepared iron nanorods, Fe@SiO2 and silver encapsulated Fe@SiO2 nanostructures. All the samples exhibited strong microwave absorption property in the high frequency range (10GHz), though it is superior for Ag encapsulated Fe@SiO2 (-14.7dB) compared with Fe@SiO2 (-9.7dB) nanostructures of the same thickness. The synthesized Ag encapsulated Fe@SiO2 nanostructure also exhibited the SERS phenomena, which is useful in the detection of the carcinogenic dye crystal violet (CV) upto the concentration of 10(-10)M. All these findings clearly demonstrate that the Ag encapsulated Fe@SiO2 nanostructure could efficiently be used in the environmental remediation.

  12. SERS active Ag encapsulated Fe@SiO2 nanorods in electromagnetic wave absorption and crystal violet detection.

    PubMed

    Senapati, Samarpita; Srivastava, Suneel Kumar; Singh, Shiv Brat; Kulkarni, Ajit R

    2014-11-01

    The present work is focused on the preparation of Fe nanorods by the chemical reduction of FeCl3 (aq) using NaBH4 in the presence of glycerol as template followed by annealing of the product at 500°C in the presence of H2 gas flow. Subsequently, its surface has been modified by silica followed by silver nanoparticles to form silica coated Fe (Fe@SiO2) and Ag encapsulated Fe@SiO2 nanostructure employing the Stöber method and silver mirror reaction respectively. XRD pattern of the products confirmed the formation of bcc phase of iron and fcc phase of silver, though silica remained amorphous. FESEM images established the growth of iron nanorods from the annealed product and also formation of silica and silver coating on its surface. The appearance of the characteristics bands in FTIR confirmed the presence of SiO2 on the Fe surface. Magnetic measurements at room temperature indicated the ferromagnetic behavior of as prepared iron nanorods, Fe@SiO2 and silver encapsulated Fe@SiO2 nanostructures. All the samples exhibited strong microwave absorption property in the high frequency range (10GHz), though it is superior for Ag encapsulated Fe@SiO2 (-14.7dB) compared with Fe@SiO2 (-9.7dB) nanostructures of the same thickness. The synthesized Ag encapsulated Fe@SiO2 nanostructure also exhibited the SERS phenomena, which is useful in the detection of the carcinogenic dye crystal violet (CV) upto the concentration of 10(-10)M. All these findings clearly demonstrate that the Ag encapsulated Fe@SiO2 nanostructure could efficiently be used in the environmental remediation. PMID:25262081

  13. Bridgman Growth of Large SrI2:Eu2+ Single Crystals: A High-performance Scintillator for Radiation Detection Applications

    SciTech Connect

    Boatner, Lynn A; Ramey, Joanne Oxendine; Kolopus, James A; Hawrami, Rastgo; Higgins, William; Van Loef, Edgar; Glodo, J.; Shah, Kanai; Bhattacharya, P.; Tupitsyn, E; Groza, Michael; Burger, Arnold

    2013-01-01

    Single-crystal strontium iodide (SrI2) doped with relatively high levels (e.g., 3 - 6 %) of Eu2+ exhibits characteristics that make this material superior, in a number of respects, to other scintillators that are currently used for radiation detection. Specifically, SrI2:Eu2+ has a light yield that is significantly higher than LaBr3:Ce3+ -a currently employed commercial high-performance scintillator. Additionally, SrI2:Eu2+ is characterized by an energy resolution as high as 2.6% at the 137Cs gamma-ray energy of 662 keV, and there is no radioactive component in SrI2:Eu2+ - unlike LaBr3:Ce3+ that contains 138La. The Ce3+-doped LaBr3 decay time is, however, faster (30 nsec) than the 1.2 sec decay time of SrI2:Eu2+. Due to the relatively low melting point of strontium iodide (~515 oC), crystal growth can be carried out in quartz crucibles by the vertical Bridgman technique. Materials-processing and crystal-growth techniques that are specific to the Bridgman growth of europium-doped strontium iodide scintillators are described here. These techniques include the use of a porous quartz frit to physically filter the molten salt from a quartz antechamber into the Bridgman growth crucible and the use of a bent or bulb grain selector design to suppress multiple grain growth. Single crystals of SrI2:Eu2+ scintillators with good optical quality and scintillation characteristics have been grown in sizes up to 5.0 cm in diameter by applying these techniques. Other aspects of the SrI2:Eu2+ crystal-growth methods and of the still unresolved crystal-growth issues are described here.

  14. Immobilization of bovine serum albumin as a sensitive biosensor for the detection of trace lead ion in solution by piezoelectric quartz crystal impedance.

    PubMed

    Yin, Jian; Wei, Wanzhi; Liu, Xiaoying; Kong, Bo; Wu, Ling; Gong, Shuguo

    2007-01-01

    A biosensor based on bovine serum albumin (BSA) for the detection of lead (Pb(2+)) ion was developed and characterized. BSA was immobilized onto a colloidal Au-modified piezoelectric quartz crystal (PQC) as a biosensor for the detection of Pb(2+) ion by piezoelectric quartz crystal impedance (PQCI). Calibration curves for the quantification of Pb(2+) ion showed excellent linearity throughout the concentration range from 1.0 x 10(-7) to 3.0 x 10(-9)mol/L. The interaction between the Pb(2+) ions and the sensor chip is influenced significantly by the pH of the reaction buffer, and the optimal pH for the experiment was 5.4. Under the optimal conditions, the detection limit of 1.0 x 10(-9)mol/L for Pb(2+) was obtained. Kinetic parameters of the Pb(2+)-BSA interactions were also determined by using this chip. The sensor chip could be regenerated for use by dipping in the ethylenediaminetetraacetic acid (EDTA) solution for approximately 2h, and the chip was used to detect Pb(2+) ion for eight times without obvious signal attenuation.

  15. The development of DNA-based quartz crystal microbalance integrated with isothermal DNA amplification system for human papillomavirus type 58 detection.

    PubMed

    Prakrankamanant, Preeda; Leelayuwat, Chanvit; Promptmas, Chamras; Limpaiboon, Temduang; Wanram, Surasak; Prasongdee, Prinya; Pientong, Chamsai; Daduang, Jureerat; Jearanaikoon, Patcharee

    2013-02-15

    To address the effect of dramatic change in temperature and viscosity during PCR process on quartz crystal microbalance (QCM) sensor and to increase the sensitivity, isothermal amplification was employed in the system. We combined loop-mediated isothermal amplification (LAMP) technique with QCM, called as LAMP-QCM, for detection of high-risk human papillomavirus viral DNA type 58 (HPV-58) which is commonly found in Asian women. The liquid-phase LAMP-QCM prototype comprised the frequency counter, a temperature control device and housing of the quartz crystal with polished gold electrodes on both sides. QCM detection signal was monitored in real-time based on an avidin-biotin binding between avidin coated QCM surface and specific biotinylated LAMP products. Analytical performance was evaluated for precision, sensitivity and specificity. A plasmid clone containing the HPV-58 sequence was diluted from 10(6) to 1 copy and used for detection limit. Cut-off value was estimated at 28.8 Hz from negative viral template. The system could detect 100 copies with Δf at 34.0±3.6 Hz compared to 1000 copies detected by conventional LAMP. No cross-reaction was observed with other HPV types. The HPV-58 detection was compared among LAMP-QCM, conventional LAMP and nested PCR in 50 cervical cancer tissues. The positive rate of LAMP-QCM was higher than that of conventional LAMP with 100% sensitivity and 90.5% specificity. The integrated LAMP-QCM system has improved the detection limit up to ten times compared to conventional LAMP with less-time consuming. PMID:22959017

  16. Detection of nano-oxidation sites on the surface of hemoglobin crystals using tip-enhanced Raman scattering.

    PubMed

    Wood, Bayden R; Asghari-Khiavi, Mehdi; Bailo, Elena; McNaughton, Don; Deckert, Volker

    2012-03-14

    Hemoglobin nanocrystals were analyzed with tip-enhanced Raman scattering (TERS), surface-enhanced resonance Raman scattering (SERRS) and conventional resonance Raman scattering (RRS) using 532 nm excitation. The extremely high spatial resolution of TERS enables selective enhancement of heme, protein, and amino acid bands from the crystal surface not observed in the SERRS or RRS spectra. Two bands appearing at 1378 and 1355 cm(-1) assigned to the ferric and ferrous oxidation state marker bands, respectively, were observed in both TERS and SERRS spectra but not in the RRS spectrum of the bulk sample. The results indicate that nanoscale oxidation changes are occurring at the hemoglobin crystal surface. These changes could be explained by oxygen exchange at the crystal surface and demonstrate the potential of the TERS technique to obtain structural information not possible with conventional Raman microscopy.

  17. Generation and detection of the polarization of multi-GeV photons by use of two diamond crystals

    NASA Astrophysics Data System (ADS)

    Kirsebom, K.; Kononets, Yu. V.; Mikkelsen, U.; Møller, S. P.; Uggerhøj, E.; Worm, T.; Elsener, K.; Biino, C.; Ballestrero, S.; Sona, P.; Avakian, R. O.; Ispirian, K. A.; Taroian, S. P.; Connell, S. H.; Sellschop, J. P. F.; Vilakazi, Z. Z.

    1999-07-01

    Presented are experimental results for the difference in pair production probability (the asymmetry) for 5-150 GeV photons polarized parallel and perpendicular to a (110) plane in a 1.5 mm thick diamond <100> crystal. The photons are produced by interaction of 150 GeV electrons with an aligned diamond <100> crystal of 0.5 mm thickness. A significant asymmetry is found over the whole energy range, which corresponds to a high degree of linear polarization of the photons as well as a difference in the refractive index. This proof-of-principle result gives the possibility of producing high energy photons with circular polarization by use of a crystal. This might open for several opportunities in high energy physics like for instance the investigation of the contribution of the gluons to the spin of the nucleon.

  18. Liquid Crystals

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Thermochromic liquid crystals, or TLCs, are a type of liquid crystals that react to changes in temperature by changing color. The Hallcrest/NASA collaboration involved development of a new way to visualize boundary layer transition in flight and in wind tunnel testing of aircraft wing and body surfaces. TLCs offered a new and potentially better method of visualizing the boundary layer transition in flight. Hallcrest provided a liquid crystal formulation technique that afforded great control over the sensitivity of the liquid crystals to varying conditions. Method is of great use to industry, government and universities for aerodynamic and hydrodynamic testing. Company's principal line is temperature indicating devices for industrial use, such as non-destructive testing and flaw detection in electric/electronic systems, medical application, such as diagnostic systems, for retail sale, such as room, refrigerator, baby bath and aquarium thermometers, and for advertising and promotion specials. Additionally, Hallcrest manufactures TLC mixtures for cosmetic applications, and liquid crystal battery tester for Duracell batteries.

  19. Magneto-optical spectroscopy and optical detection of EPR spectra of Yb3+ paramagnetic centers with cubic symmetry in single crystals MeF2 ( Me = Cd, Ca, Pb)

    NASA Astrophysics Data System (ADS)

    Gerasimov, K. I.; Falin, M. L.

    2009-04-01

    Cubic paramagnetic centers formed by Yb3+ impurity ions in fluorite-type crystals MeF2 ( Me = Cd, Ca, Pb) have been investigated using electron paramagnetic resonance, magnetic circular dichroism, magnetic circular polarization of luminescence, Zeeman splitting of optical absorption and luminescence lines, and optical detection of electron paramagnetic resonance. The g factors of the 2Γ7 state in the excited multiplet 2 F 5/2 of Yb3+ ions in Me F2 crystals, the hyperfine interaction constant 171 A (171Yb) for the excited multiplet 2 F 5/2 in the CaF2 crystal, and the energies and symmetry properties of all energy levels of Yb3+ ions in MeF2 crystals are determined. The crystal-field parameters for the crystals under investigation are calculated.

  20. Fabrication of a PMN-PT Single Crystal-Based Transcranial Doppler Transducer and the Power Regulation of Its Detection System

    PubMed Central

    Yue, Qingwen; Liu, Dongxu; Wang, Wei; Di, Wenning; Lin, Di; Wang, Xi'an; Luo, Haosu

    2014-01-01

    Doppler sonographic measurement of flow velocity in the basal cerebral arteries through the intact skull was developed using a pulsed Doppler technique and 2 MHz emitting frequency. Relaxor-based ferroelectric single crystals Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) were chosen to be the piezoelectric transducer material due to their ultrahigh piezoelectric coefficients, high electromechanical coupling coefficients and low dielectric loss. The pulse-echo response of the transducer was measured using the conventional pulse-echo method in a water bath at room temperature. The −6 dB bandwidth of the transducer is 68.4% and the sensitivity is −17.4 dB. In order to get a good match between transducer and detection system, different transmission powers have been regulated by changing the impedance of the transmitting electric circuit. In the middle cerebral artery (MCA) measurement photograph results, as the transmission power is increasing, the detection results become clearer and clearer. A comparison at the same transmission power for different transducers shows that the detection photograph obtained by the crystal transducer was clearer than that obtained with a commercial transducer, which should make it easier for doctors to find the cerebral arteries. PMID:25536000

  1. Fabrication of a PMN-PT single crystal-based transcranial Doppler transducer and the power regulation of its detection system.

    PubMed

    Yue, Qingwen; Liu, Dongxu; Wang, Wei; Di, Wenning; Lin, Di; Wang, Xi'an; Luo, Haosu

    2014-12-19

    Doppler sonographic measurement of flow velocity in the basal cerebral arteries through the intact skull was developed using a pulsed Doppler technique and 2 MHz emitting frequency. Relaxor-based ferroelectric single crystals Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) were chosen to be the piezoelectric transducer material due to their ultrahigh piezoelectric coefficients, high electromechanical coupling coefficients and low dielectric loss. The pulse-echo response of the transducer was measured using the conventional pulse-echo method in a water bath at room temperature. The -6 dB bandwidth of the transducer is 68.4% and the sensitivity is -17.4 dB. In order to get a good match between transducer and detection system, different transmission powers have been regulated by changing the impedance of the transmitting electric circuit. In the middle cerebral artery (MCA) measurement photograph results, as the transmission power is increasing, the detection results become clearer and clearer. A comparison at the same transmission power for different transducers shows that the detection photograph obtained by the crystal transducer was clearer than that obtained with a commercial transducer, which should make it easier for doctors to find the cerebral arteries.

  2. Fabrication of a PMN-PT single crystal-based transcranial Doppler transducer and the power regulation of its detection system.

    PubMed

    Yue, Qingwen; Liu, Dongxu; Wang, Wei; Di, Wenning; Lin, Di; Wang, Xi'an; Luo, Haosu

    2014-01-01

    Doppler sonographic measurement of flow velocity in the basal cerebral arteries through the intact skull was developed using a pulsed Doppler technique and 2 MHz emitting frequency. Relaxor-based ferroelectric single crystals Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) were chosen to be the piezoelectric transducer material due to their ultrahigh piezoelectric coefficients, high electromechanical coupling coefficients and low dielectric loss. The pulse-echo response of the transducer was measured using the conventional pulse-echo method in a water bath at room temperature. The -6 dB bandwidth of the transducer is 68.4% and the sensitivity is -17.4 dB. In order to get a good match between transducer and detection system, different transmission powers have been regulated by changing the impedance of the transmitting electric circuit. In the middle cerebral artery (MCA) measurement photograph results, as the transmission power is increasing, the detection results become clearer and clearer. A comparison at the same transmission power for different transducers shows that the detection photograph obtained by the crystal transducer was clearer than that obtained with a commercial transducer, which should make it easier for doctors to find the cerebral arteries. PMID:25536000

  3. Rare-Earth Tri-Halide Methanol-Adduct Single-Crystal Scintillators for Gamma Ray and Neutron Detection - 8/17/09

    SciTech Connect

    Boatner, Lynn A; Wisniewski, D.; Neal, John S; Bell, Zane W; Ramey, Joanne Oxendine; Kolopus, James A; Chakoumakos, Bryan C; Custelcean, Radu; Wisniewska, Monika; Peña, K. E.

    2009-01-01

    Cerium activated rare-earth tri- halides represent a well-known family of high performance inorganic rare-earth scintillators - including the high-light-yield, high-energy-resolution scintillator, cerium-doped lanthanum tribromide. These hygroscopic inorganic rare-earth halides are currently grown as single crystals from the melt - either by the Bridgman or Czochralski techniques slow and expensive processes that are frequently characterized by severe cracking of the material due to anisotropic thermal stresses and cleavage effects. We have recently discovered a new family of cerium-activated rare-earth metal organic scintillators consisting of tri-halide methanol adducts of cerium and lanthanum namely CeCl3(CH3OH)4 and LaBr3(CH3OH)4:Ce. These methanol-adduct scintillator materials can be grown near room temperature from a methanol solution, and their high solubility is consistent with the application of the rapid solution growth methods that are currently used to grow very large single crystals of potassium dihydrogen phosphate. The structures of these new rare-earth metal-organic scintillating compounds were determined by single crystal x-ray refinements, and their scintillation response to both gamma rays and neutrons, as presented here, was characterized using different excitation sources. Tri-halide methanol-adduct crystals activated with trivalent cerium apparently represent the initial example of a solution-grown rare-earth metal-organic molecular scintillator that is applicable to gamma ray, x-ray, and fast neutron detection.

  4. Highly sensitive and selective detection of Pb2+ ions using a novel and simple DNAzyme-based quartz crystal microbalance with dissipation biosensor.

    PubMed

    Teh, Hui Boon; Li, Haiyan; Yau Li, Sam Fong

    2014-10-21

    A novel, label-free DNAzyme-based quartz crystal microbalance with dissipation monitoring (QCM-D) biosensor was developed for the highly sensitive and specific detection of Pb(2+) ions. To enhance the performance of the sensor, oligonucleotide-functionalized gold nanoparticles were used for both frequency and dissipation amplification. This sensor was developed by immobilizing Pb(2+)-specific DNAzymes onto the QCM-D sensor surface and allowing them to hybridize with substrate-functionalized AuNPs. The DNAzyme catalyzed the cleavage of the substrate in the presence of Pb(2+) ions, causing the cleaved substrate-functionalized AuNPs to be removed from the sensor surface. Thus, Pb(2+) ions can be determined on-line by monitoring the change in frequency and dissipation signals. The results revealed that the sensor showed a sensitive response to Pb(2+) ions with detection limits of 14 nM and 20 nM for frequency and dissipation, respectively. This QCM-D biosensor also exhibited excellent selectivity toward Pb(2+) ions in the presence of other divalent metal ions. In addition, the approach was able to detect Pb(2+) in tap water, demonstrating its great potential for monitoring drinking water quality. The proposed sensor system described here represents a new class of lead ion sensor. Its simple detection strategy makes it feasible for 'pollution-free' detection; thus, the approach could have applications in on-line water quality monitoring.

  5. 10 aJ-level sensing of nanosecond pulse below 10 THz by frequency upconversion detection via DAST crystal: more than a 4 K bolometer.

    PubMed

    Qi, Feng; Fan, Shuzhen; Notake, Takashi; Nawata, Koji; Matsukawa, Takeshi; Takida, Yuma; Minamide, Hiroaki

    2014-03-01

    By using frequency upconversion detection of terahertz (THz) waves via 4-dimethylamino-N-methyl-4-stilbazolium tosylate (DAST) crystal with an optimized frequency conversion process, ultrahigh sensitivity has been achieved. Direct comparisons with a 4 K bolometer were implemented. By using a simple positive intrinsic negative (PIN) diode without either electrical amplification or optical amplification, frequency upconversion detection can compete with the commercial 4 K bolometer, while by replacing the PIN diode with an avalanche photo diode (APD), it performs more than three orders better than the 4 K bolometer. Based on power calibration, the minimum detectable THz pulse energy is in the order of 10 aJ (9-25 aJ) at 4.3 THz, with a pulse duration of 6 ns. Thus, the minimum number of THz photons that can be detected is down to the order of 10(3) at room temperature. The current THz detection system gives a noise equivalent power (NEP) in the order of 100  fW/Hz(1/2) (50-128  fW/Hz(1/2)). Moreover, by switching current optical detectors, the dynamic range is over six orders. PMID:24690730

  6. Double labeling and simultaneous detection of B- and T cells using fluorescent nano-crystal (q-dots) in paraffin-embedded tissues.

    PubMed

    Zahavy, Eran; Freeman, Esther; Lustig, Shlomo; Keysary, Avi; Yitzhaki, Shmuel

    2005-09-01

    A double immunohistochemical technique for the simultaneous detection of T- and B cells in paraffin-embedded mice tissues have been developed. This procedure is based on using fluorescent nano-crystals (q-dots). The benefit of using q-dots evolves from their unique fluorescence characteristics advantages: such as broad excitation spectrum, narrow emission band and high photo-bleaching threshold compare to organic fluorophores. T cells antigens (CD3) were stained using antibody-coated q-dots with max emission at 655 nm (GalphaRb-QD655). B cells antigens (CD45R/B220) were stained using streptavidin-coated q-dots with max emission at 585 nm (SA-QD585). The simultaneous detection of T- and B cells was demonstrated in paraffin-embedded lymph node using standard fluorescence microscope.

  7. Development and application of quartz crystal microbalance sensor based on novel molecularly imprinted sol-gel polymer for rapid detection of histamine in foods.

    PubMed

    Dai, Jie; Zhang, Yan; Pan, Mingfei; Kong, Lingjie; Wang, Shuo

    2014-06-11

    To rapidly detect histamine (HA) in foods, a novel material for HA-specific recognition was synthesized by a sol-gel process and coated on a quartz crystal microbalance (QCM) sensor. The Scatchard model was used to evaluate the adsorption performance of the material; high affinity for HA was demonstrated. Based on QCM frequency change, the sensor exhibited linear behavior for HA concentrations of 0.11 × 10(-2) to 4.45 × 10(-2) mg L(-1), a detection limit of 7.49 × 10(-4) mg kg(-1) (S/N = 3), high selectivity for HA (selectivity coefficient >4) compared with structural analogues, good reproducibility, and long-term stability. The sensor was used to determine the concentration of HA in spiked fish products; the recovery values were satisfactory (93.2-100.4%) and compared well with those obtained by high-performance liquid chromatography (correlation coefficient, r(2) = 0.9965).

  8. Sensitive Detection of Protein and miRNA Cancer Biomarkers using Silicon-Based Photonic Crystals and A Resonance Coupling Laser Scanning Platform

    PubMed Central

    George, Sherine; Chaudhery, Vikram; Lu, Meng; Takagi, Miki; Amro, Nabil; Pokhriyal, Anusha; Tan, Yafang; Ferreira, Placid; Cunningham, Brian T.

    2013-01-01

    Enhancement of the fluorescent output of surface-based fluorescence assays by performing them upon nanostructured photonic crystal (PC) surfaces has been demonstrated to increase signal intensities by >8000×. Using the multiplicative effects of optical resonant coupling to the PC in increasing the electric field intensity experienced by fluorescent labels (“enhanced excitation”) and the spatially biased funneling of fluorophore emissions through coupling to PC resonances (“enhanced extraction”), PC enhanced fluorescence (PCEF) can be adapted to reduce the limits of detection of disease biomarker assays, and to reduce the size and cost of high sensitivity detection instrumentation. In this work, we demonstrate the first silicon-based PCEF detection platform for multiplexed biomarker assay. The sensor in this platform is a silicon-based PC structure, comprised of a SiO2 grating that is overcoated with a thin film of high refractive index TiO2 and is produced in a semiconductor foundry for low cost, uniform, and reproducible manufacturing. The compact detection instrument that completes this platform was designed to efficiently couples fluorescence excitation from a semiconductor laser to the resonant optical modes of the PC, resulting in elevated electric field strength that is highly concentrated within the region <100 nm from the PC surface. This instrument utilizes a cylindrically focused line to scan a microarray in <1 minute. To demonstrate the capabilities of this sensor-detector platform, microspot fluorescent sandwich immunoassays using secondary antibodies labeled with Cy5 for two cancer biomarkers (TNF-α and IL-3) were performed. Biomarkers were detected at concentrations as low as 0.1 pM. In a fluorescent microarray for detection of a breast cancer miRNA biomarker miR-21, the miRNA was detectable at a concentration of 0.6 pM. PMID:23963502

  9. Surface modification of alignment layer by ultraviolet irradiation to dramatically improve the detection limit of liquid-crystal-based immunoassay for the cancer biomarker CA125

    NASA Astrophysics Data System (ADS)

    Su, Hui-Wen; Lee, Mon-Juan; Lee, Wei

    2015-05-01

    Liquid crystal (LC)-based biosensing has attracted much attention in recent years. We focus on improving the detection limit of LC-based immunoassay techniques by surface modification of the surfactant alignment layer consisting of dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (DMOAP). The cancer biomarker CA125 was detected with an array of anti-CA125 antibodies immobilized on the ultraviolet (UV)-modified DMOAP monolayer. Compared with a pristine counterpart, UV irradiation enhanced the binding affinity of the CA125 antibody and reproducibility of immunodetection in which a detection limit of 0.01 ng/ml for the cancer biomarker CA125 was achieved. Additionally, the optical texture observed under a crossed polarized microscope was correlated with the analyte concentration. In a proof-of-concept experiment using CA125-spiked human serum as the analyte, specific binding between the CA125 antigen and the anti-CA125 antibody resulted in a distinct and concentration-dependent optical response despite the high background caused by nonspecific binding of other biomolecules in the human serum. Results from this study indicate that UV modification of the alignment layer, as well as detection with LCs of large birefringence, contributes to the enhanced performance of the label-free LC-based immunodetection, which may be considered a promising alternative to conventional label-based methods.

  10. Surface modification of alignment layer by ultraviolet irradiation to dramatically improve the detection limit of liquid-crystal-based immunoassay for the cancer biomarker CA125.

    PubMed

    Su, Hui-Wen; Lee, Mon-Juan; Lee, Wei

    2015-05-01

    Liquid crystal (LC)-based biosensing has attracted much attention in recent years. We focus on improving the detection limit of LC-based immunoassay techniques by surface modification of the surfactant alignment layer consisting of dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (DMOAP). The cancer biomarker CA125 was detected with an array of anti-CA125 antibodies immobilized on the ultraviolet (UV)-modified DMOAP monolayer. Compared with a pristine counterpart, UV irradiation enhanced the binding affinity of the CA125 antibody and reproducibility of immunodetection in which a detection limit of 0.01 ng∕ml for the cancer biomarker CA125 was achieved. Additionally, the optical texture observed under a crossed polarized microscope was correlated with the analyte concentration. In a proof-of-concept experiment using CA125-spiked human serum as the analyte, specific binding between the CA125 antigen and the anti-CA125 antibody resulted in a distinct and concentration-dependent optical response despite the high background caused by nonspecific binding of other biomolecules in the human serum. Results from this study indicate that UVmodification of the alignment layer, as well as detection with LCs of large birefringence, contributes to the enhanced performance of the label-free LC-based immunodetection, which may be considered a promising alternative to conventional label-based methods. PMID:26000796

  11. Label-free optical detection of C-reactive protein by nanoimprint lithography-based 2D-photonic crystal film.

    PubMed

    Endo, Tatsuro; Kajita, Hiroshi; Kawaguchi, Yukio; Kosaka, Terumasa; Himi, Toshiyuki

    2016-06-01

    The development of high-sensitive, and cost-effective novel biosensors have been strongly desired for future medical diagnostics. To develop novel biosensor, the authors focused on the specific optical characteristics of photonic crystal. In this study, a label-free optical biosensor, polymer-based two-dimensional photonic crystal (2D-PhC) film fabricated using nanoimprint lithography (NIL), was developed for detection of C-reactive protein (CRP) in human serum. The nano-hole array constructed NIL-based 2D-PhC (hole diameter: 230 nm, distance: 230, depth: 200 nm) was fabricated on a cyclo-olefin polymer (COP) film (100 µm) using thermal NIL and required surface modifications to reduce nonspecific adsorption of target proteins. Antigen-antibody reactions on the NIL-based 2D-PhC caused changes to the surrounding refractive index, which was monitored as reflection spectrum changes in the visible region. By using surface modified 2D-PhC, the calculated detection limit for CRP was 12.24 pg/mL at an extremely short reaction time (5 min) without the need for additional labeling procedures and secondary antibody. Furthermore, using the dual-functional random copolymer, CRP could be detected in a pooled blood serum diluted 100× with dramatic reduction of nonspecific adsorption. From these results, the NIL-based 2D-PhC film has great potential for development of an on-site, high-sensitivity, cost-effective, label-free biosensor for medical diagnostics applications. PMID:27150702

  12. A method of layer-by-layer gold nanoparticle hybridization in a quartz crystal microbalance DNA sensing system used to detect dengue virus.

    PubMed

    Chen, Sz-Hau; Chuang, Yao-Chen; Lu, Yi-Chen; Lin, Hsiu-Chao; Yang, Yun-Liang; Lin, Chih-Sheng

    2009-05-27

    Dengue virus (DENV) is nowadays the most important arthropod-spread virus affecting humans existing in more than 100 countries worldwide. A rapid and sensitive detection method for the early diagnosis of infectious dengue virus urgently needs to be developed. In the present study, a circulating-flow quartz crystal microbalance (QCM) biosensing method combining oligonucleotide-functionalized gold nanoparticles (i.e. AuNP probes) used to detect DENV has been established. In the DNA-QCM method, two kinds of specific AuNP probes were linked by the target sequences onto the QCM chip to amplify the detection signal, i.e. oscillatory frequency change (DeltaF) of the QCM sensor. The target sequences amplified from the DENV genome act as a bridge for the layer-by-layer AuNP probes' hybridization in the method. Besides being amplifiers of the detection signal, the specific AuNP probes used in the DNA-QCM method also play the role of verifiers to specifically recognize their target sequences in the detection. The effect of four AuNP sizes on the layer-by-layer hybridization has been evaluated and it is found that 13 nm AuNPs collocated with 13 nm AuNPs showed the best hybridization efficiency. According to the nanoparticle application, the DNA-QCM biosensing method was able to detect dengue viral RNA in virus-contaminated serum as plaque titers being 2 PFU ml(-1) and a linear correlation (R(2) = 0.987) of DeltaF versus virus titration from 2 x 10(0) to 2 x 10(6) PFU ml(-1) was found. The sensitivity and specificity of the present DNA-QCM method with nanoparticle technology showed it to be comparable to the fluorescent real-time PCR methods. Moreover, the method described herein was shown to not require expensive equipment, was label-free and highly sensitive.

  13. A method of layer-by-layer gold nanoparticle hybridization in a quartz crystal microbalance DNA sensing system used to detect dengue virus

    NASA Astrophysics Data System (ADS)

    Chen, Sz-Hau; Chuang, Yao-Chen; Lu, Yi-Chen; Lin, Hsiu-Chao; Yang, Yun-Liang; Lin, Chih-Sheng

    2009-05-01

    Dengue virus (DENV) is nowadays the most important arthropod-spread virus affecting humans existing in more than 100 countries worldwide. A rapid and sensitive detection method for the early diagnosis of infectious dengue virus urgently needs to be developed. In the present study, a circulating-flow quartz crystal microbalance (QCM) biosensing method combining oligonucleotide-functionalized gold nanoparticles (i.e. AuNP probes) used to detect DENV has been established. In the DNA-QCM method, two kinds of specific AuNP probes were linked by the target sequences onto the QCM chip to amplify the detection signal, i.e. oscillatory frequency change (ΔF) of the QCM sensor. The target sequences amplified from the DENV genome act as a bridge for the layer-by-layer AuNP probes' hybridization in the method. Besides being amplifiers of the detection signal, the specific AuNP probes used in the DNA-QCM method also play the role of verifiers to specifically recognize their target sequences in the detection. The effect of four AuNP sizes on the layer-by-layer hybridization has been evaluated and it is found that 13 nm AuNPs collocated with 13 nm AuNPs showed the best hybridization efficiency. According to the nanoparticle application, the DNA-QCM biosensing method was able to detect dengue viral RNA in virus-contaminated serum as plaque titers being 2 PFU ml-1 and a linear correlation (R2 = 0.987) of ΔF versus virus titration from 2 × 100 to 2 × 106 PFU ml-1 was found. The sensitivity and specificity of the present DNA-QCM method with nanoparticle technology showed it to be comparable to the fluorescent real-time PCR methods. Moreover, the method described herein was shown to not require expensive equipment, was label-free and highly sensitive.

  14. Microfluidic sensing devices employing in situ-formed liquid crystal thin film for detection of biochemical interactions.

    PubMed

    Liu, Ye; Cheng, Daming; Lin, I-Hsin; Abbott, Nicholas L; Jiang, Hongrui

    2012-10-01

    Although biochemical sensing using liquid crystals (LC) has been demonstrated, relatively little attention has been paid towards the fabrication of in situ-formed LC sensing devices. Herein, we demonstrate a highly reproducible method to create uniform LC thin film on treated substrates, as needed, for LC sensing. We use shear forces generated by the laminar flow of aqueous liquid within a microfluidic channel to create LC thin films stabilized within microfabricated structures. The orientational response of the LC thin films to targeted analytes in aqueous phases was transduced and amplified by the optical birefringence of the LC thin films. The biochemical sensing capability of our sensing devices was demonstrated through experiments employing two chemical systems: dodecyl trimethylammonium bromide (DTAB) dissolved in an aqueous solution, and the hydrolysis of phospholipids by the enzyme phospholipase A(2) (PLA(2)).

  15. Microfludic Sensing Devices Employing In Situ-Formed Liquid Crystal Thin Film for Detection of Biochemical Interactions1†

    PubMed Central

    Liu, Ye; Cheng, Daming; Lin, I-Hsin; Abbott, Nicholas L.; Jiang, Hongrui

    2012-01-01

    Although biochemical sensing using liquid crystals (LC) has been demonstrated, relatively little attention has been paid towards the fabrication of in situ-formed LC sensing devices. Herein, we demonstrate a highly reproducible method to create uniform LC thin film on treated substrates, as needed, for LC sensing. We use shear forces generated by the laminar flow of aqueous liquid within a microfluidic channel to create LC thin films stabilized within microfabricated structures. The orientational response of the LC thin films to targeted analytes in aqueous phases was transduced and amplified by the optical birefringence of the LC thin films. The biochemical sensing capability of our sensing devices was demonstrated through experiments employing two chemical systems: dodecyl trimethylammonium bromide (DTAB) dissolved in an aqueous solution, and the hydrolysis of phospholipids by the enzyme phospholipase A2 (PLA2). PMID:22842797

  16. First order magnetic transition in single crystal CaFe2As2 detected by 75As NMR

    SciTech Connect

    Baek, Seung Ho; Curro, Nicholas J

    2008-01-01

    We report {sup 75}As Nuclear Magnetic Resonance data in a single crystal of CaFe{sub 2}As{sub 2}. The Knight shift, the electric field gradient, and the spin lattice relaxation rate are strongly temperature dependent in the paramagnetic state, and change discontinuously at the structural transition temperature, T{sub S} = T{sub N} = 167 K. Immediately below, the NMR spectra reveal an internal field at the As site associated with the presence of a commensurate magnetic order. These results indicate that the structural and magnetic transitions in CaFe{sub 2}As{sub 2} are first order and strongly coupled, and that the electron density in the FeAs plane is highly sensitive to the out-of-plane structure.

  17. Microfluidic sensing devices employing in situ-formed liquid crystal thin film for detection of biochemical interactions.

    PubMed

    Liu, Ye; Cheng, Daming; Lin, I-Hsin; Abbott, Nicholas L; Jiang, Hongrui

    2012-10-01

    Although biochemical sensing using liquid crystals (LC) has been demonstrated, relatively little attention has been paid towards the fabrication of in situ-formed LC sensing devices. Herein, we demonstrate a highly reproducible method to create uniform LC thin film on treated substrates, as needed, for LC sensing. We use shear forces generated by the laminar flow of aqueous liquid within a microfluidic channel to create LC thin films stabilized within microfabricated structures. The orientational response of the LC thin films to targeted analytes in aqueous phases was transduced and amplified by the optical birefringence of the LC thin films. The biochemical sensing capability of our sensing devices was demonstrated through experiments employing two chemical systems: dodecyl trimethylammonium bromide (DTAB) dissolved in an aqueous solution, and the hydrolysis of phospholipids by the enzyme phospholipase A(2) (PLA(2)). PMID:22842797

  18. Detection of an intermediate biaxial phase in the phase diagram of biaxial liquid crystals: Entropic sampling study

    NASA Astrophysics Data System (ADS)

    Kamala Latha, B.; Jose, Regina; Murthy, K. P. N.; Sastry, V. S. S.

    2014-05-01

    We investigate the phase sequence of biaxial liquid crystals, based on a general quadratic model Hamiltonian over the relevant parameter space, with a Monte Carlo simulation which constructs equilibrium ensembles of microstates, overcoming possible (free) energy barriers (combining entropic and frontier sampling techniques). The resulting phase diagram qualitatively differs from the universal phase diagram predicted earlier from mean-field theory (MFT), as well as the Monte Carlo simulations with the Metropolis algorithm. The direct isotropic-to-biaxial transition predicted by the MFT is replaced in certain regions of the space by the onset of an additional intermediate biaxial phase of very low order, leading to the sequence NB-NB1-I. This is due to inherent barriers to fluctuations of the components comprising the total energy, and may explain the difficulties in the experimental realization of these phases.

  19. Detection of an intermediate biaxial phase in the phase diagram of biaxial liquid crystals: entropic sampling study.

    PubMed

    Kamala Latha, B; Jose, Regina; Murthy, K P N; Sastry, V S S

    2014-05-01

    We investigate the phase sequence of biaxial liquid crystals, based on a general quadratic model Hamiltonian over the relevant parameter space, with a Monte Carlo simulation which constructs equilibrium ensembles of microstates, overcoming possible (free) energy barriers (combining entropic and frontier sampling techniques). The resulting phase diagram qualitatively differs from the universal phase diagram predicted earlier from mean-field theory (MFT), as well as the Monte Carlo simulations with the Metropolis algorithm. The direct isotropic-to-biaxial transition predicted by the MFT is replaced in certain regions of the space by the onset of an additional intermediate biaxial phase of very low order, leading to the sequence N(B)-N(B1)-I. This is due to inherent barriers to fluctuations of the components comprising the total energy, and may explain the difficulties in the experimental realization of these phases.

  20. The cylindrical air holes of the negative-refraction photonic crystal double flat lens group for lightwave target detection and imaging

    NASA Astrophysics Data System (ADS)

    Lu, Jian; Shen, Yang; Shen, TingGen; Lian, YingFei; Wang, FeiFei; Xu, Yang

    2013-06-01

    The influence of the cylindrical air holes of the negative-refraction photonic crystal (NR-PC) double flat lens group on the performance of lightwave target detection and imaging is studied in this paper using the finite-difference time-domain (FDTD) method. Numerical simulations indicate that significant enhancement of the scattering signal can be obtained by using a NR-PC flat lens; consequently, great improvement of the refocusing gain as well as the imaging resolution will be provided. We further research the effects of different positions for target detection by using a NR-PC double flat lens group with cylindrical air holes. Then we use defective air holes instead of perfect ones. By using a dynamic scanning scheme, we find that the distance between two flats could be changed flexibly. And it could improve the lateral resolution of target scanning and enlarge the distance between the target and flat greatly. In conclusion, our investigation optimized the performance of the detection and imaging system, and provided the basis for converting an idealized left-handed material lens into a physically realizable NR-PC double flat lens group.

  1. Direct Detection of Transcription Factors in Cotyledons during Seedling Development Using Sensitive Silicon-Substrate Photonic Crystal Protein Arrays1[OPEN

    PubMed Central

    Jones, Sarah I.; Tan, Yafang; Shamimuzzaman, Md; George, Sherine; Cunningham, Brian T.; Vodkin, Lila

    2015-01-01

    Transcription factors control important gene networks, altering the expression of a wide variety of genes, including those of agronomic importance, despite often being expressed at low levels. Detecting transcription factor proteins is difficult, because current high-throughput methods may not be sensitive enough. One-dimensional, silicon-substrate photonic crystal (PC) arrays provide an alternative substrate for printing multiplexed protein microarrays that have greater sensitivity through an increased signal-to-noise ratio of the fluorescent signal compared with performing the same assay upon a traditional aminosilanized glass surface. As a model system to test proof of concept of the silicon-substrate PC arrays to directly detect rare proteins in crude plant extracts, we selected representatives of four different transcription factor families (zinc finger GATA, basic helix-loop-helix, BTF3/NAC [for basic transcription factor of the NAC family], and YABBY) that have increasing transcript levels during the stages of seedling cotyledon development. Antibodies to synthetic peptides representing the transcription factors were printed on both glass slides and silicon-substrate PC slides along with antibodies to abundant cotyledon proteins, seed lectin, and Kunitz trypsin inhibitor. The silicon-substrate PC arrays proved more sensitive than those performed on glass slides, detecting rare proteins that were below background on the glass slides. The zinc finger transcription factor was detected on the PC arrays in crude extracts of all stages of the seedling cotyledons, whereas YABBY seemed to be at the lower limit of their sensitivity. Interestingly, the basic helix-loop-helix and NAC proteins showed developmental profiles consistent with their transcript patterns, indicating proof of concept for detecting these low-abundance proteins in crude extracts. PMID:25635113

  2. Detection of apoptosis and drug resistance of human breast cancer cells to taxane treatments using quartz crystal microbalance biosensor technology.

    PubMed

    Braunhut, Susan J; McIntosh, Donna; Vorotnikova, Ekaterina; Zhou, Tiean; Marx, Kenneth A

    2005-02-01

    Taxanes are used for the treatment of many human cancers, as first- and second-line chemotherapeutics. In the course of treatment many patients develop resistance or hypersensitivity to one form of taxane and require a different taxane to rescue the therapeutic benefit of the drug. There is currently no method to reliably predict tumor responses to taxanes prior to therapy or when resistance or hypersensitivity develops. We adapted the quartz crystal microbalance (QCM) biosensor technique to study responses of human mammary epithelial tumor cells to taxanes. Studies indicate that stable frequency and resistance levels are reached at 24 h. Cells in the QCM can then be treated with taxanes and responses monitored in real time via frequency and resistance changes reflecting alterations of cell mass distribution and viscoelastic properties. Distinct shifts in frequency and resistance accurately predicted apoptosis or resistance to treatment, as determined in parallel convention assays. QCM analysis accurately predicted docetaxel was more effective than paclitaxel and MCF-7 cells were more resistant to taxanes compared to MDA-MB-231 cells. These studies suggest "signature" patterns for taxane responsivity could be compared to those of patient biopsy samples to predict therapy outcome prior to treatment for initial therapy or to rescue therapy efficacy.

  3. Detection of the phase transition of Langmuir-Blodgett films on a quartz-crystal microbalance in an aqueous phase

    SciTech Connect

    Okahata, Yoshio; Kimura, Kazuhiko; Ariga, Katsuhiko )

    1989-12-20

    The frequency of the quartz-crystal microbalance (QCM) deposited with Langmuir-Blodgett (LB) films was observed to increase abruptly at the phase transition temperature (T{sub c}) from solid to liquid crystalline state of LB films in distilled water when the temperature was gradually raised. The frequency increase at the T{sub c} was not observed in the air phase. The LB films were observed from the frequency changes to swell (mass increase and frequency decrease) with the water penetration in the interlayers near (just below) the T{sub c} but not to swell both in the solid state (below the T{sub c}) and in the liquid crystalline state (above the T{sub c}) when in a water phase. The frequency increase at the T{sub c} of LB films can be explained by the fact that the slipping behavior occurs between the swelled hydrophilic interlayers in the fluid liquid crystalline state of LB films at the T{sub c}. The QCM is a useful tool to characterize LB films in the water phase.

  4. Detection of the Impact of Ice Crystal Accretion in an Aircraft Engine Compression System During Dynamic Operation

    NASA Technical Reports Server (NTRS)

    May, Ryan D.; Simon, Donald L.; Guo, Ten-Huei

    2014-01-01

    The accretion of ice in the compression system of commercial gas turbine engines operating in high ice water content conditions is a safety issue being studied by the aviation community. While most of the research focuses on the underlying physics of ice accretion and the meteorological conditions in which accretion can occur, a systems-level perspective on the topic lends itself to potential near-term operational improvements. Here a detection algorithm is developed which has the capability to detect the impact of ice accretion in the Low Pressure Compressor of an aircraft engine during steady flight as well as during changes in altitude. Unfortunately, the algorithm as implemented was not able to distinguish throttle changes from ice accretion and thus more work remains to be done.

  5. Enhanced sandwich immunoassay using antibody-functionalized magnetic iron-oxide nanoparticles for extraction and detection of soluble transferrin receptor on a photonic crystal biosensor.

    PubMed

    Peterson, Ross D; Chen, Weili; Cunningham, Brian T; Andrade, Juan E

    2015-12-15

    Iron deficiency anemia (IDA) has detrimental effects on individuals and societies worldwide. A standard sandwich assay (SA) for the detection of soluble transferrin receptor (sTfR), a biomarker of IDA, on a photonic crystal (PC) biosensor was established, but it was susceptible to non-specific signals from complex matrixes. In this study, iron-oxide nanoparticles (fAb-IONs) were used as magnetic immuno-probes to bind sTfR and minimize non-specific signals, while enhancing detection on the PC biosensor. This inverse sandwich assay (IA) method completely bound sTfR with low variability (<4% RSD) in buffer and allowed for its accurate and precise detection in sera (Liquichek™ control sera) on the PC biosensor using two certified ELISAs as reference methods. A linear dose-response curve was elicited at the fAb-IONs concentration in which the theoretical binding ratio (sTfR:fAb-IONs) was calculated to be <1 on the IA. The LoDs for sTfR in the SA and IA were similar (P>0.05) at 14 and 21 μg/mL, respectively. The inherent imprecision of the IA and reference ELISAs was σ(δ)=0.45 µg/mL and the mean biases for Liquichek™ 1, 2 and 3 were 0.18, 0.19 and -0.04 µg/mL, respectively. Whereas the inherent imprecision of the SA and reference ELISAs was σ(δ)=0.52 µg/mL and the biases for Liquichek™ 1, 2 and 3 were 0.66, 0.14 and -0.67 µg/mL, respectively. Thus, unlike the SA, the IA method measures sTfR with the same bias as the reference ELISAs. Combined magnetic separation and detection of nutrition biomarkers on PC biosensors represents a facile method for their accurate and reliable quantification in complex matrixes.

  6. Crystal Creations.

    ERIC Educational Resources Information Center

    Whipple, Nona; Whitmore, Sherry

    1989-01-01

    Presents a many-faceted learning approach to the study of crystals. Provides instructions for performing activities including crystal growth and patterns, creating miniature simulations of crystal-containing rock formations, charcoal and sponge gardens, and snowflakes. (RT)

  7. Fugitive methane leak detection using mid-infrared hollow-core photonic crystal fiber containing ultrafast laser drilled side-holes

    NASA Astrophysics Data System (ADS)

    Karp, Jason; Challener, William; Kasten, Matthias; Choudhury, Niloy; Palit, Sabarni; Pickrell, Gary; Homa, Daniel; Floyd, Adam; Cheng, Yujie; Yu, Fei; Knight, Jonathan

    2016-05-01

    The increase in domestic natural gas production has brought attention to the environmental impacts of persistent gas leakages. The desire to identify fugitive gas emission, specifically for methane, presents new sensing challenges within the production and distribution supply chain. A spectroscopic gas sensing solution would ideally combine a long optical path length for high sensitivity and distributed detection over large areas. Specialty micro-structured fiber with a hollow core can exhibit a relatively low attenuation at mid-infrared wavelengths where methane has strong absorption lines. Methane diffusion into the hollow core is enabled by machining side-holes along the fiber length through ultrafast laser drilling methods. The complete system provides hundreds of meters of optical path for routing along well pads and pipelines while being interrogated by a single laser and detector. This work will present transmission and methane detection capabilities of mid-infrared photonic crystal fibers. Side-hole drilling techniques for methane diffusion will be highlighted as a means to convert hollow-core fibers into applicable gas sensors.

  8. Development and application of quartz crystal microbalance sensor based on novel molecularly imprinted sol-gel polymer for rapid detection of histamine in foods.

    PubMed

    Dai, Jie; Zhang, Yan; Pan, Mingfei; Kong, Lingjie; Wang, Shuo

    2014-06-11

    To rapidly detect histamine (HA) in foods, a novel material for HA-specific recognition was synthesized by a sol-gel process and coated on a quartz crystal microbalance (QCM) sensor. The Scatchard model was used to evaluate the adsorption performance of the material; high affinity for HA was demonstrated. Based on QCM frequency change, the sensor exhibited linear behavior for HA concentrations of 0.11 × 10(-2) to 4.45 × 10(-2) mg L(-1), a detection limit of 7.49 × 10(-4) mg kg(-1) (S/N = 3), high selectivity for HA (selectivity coefficient >4) compared with structural analogues, good reproducibility, and long-term stability. The sensor was used to determine the concentration of HA in spiked fish products; the recovery values were satisfactory (93.2-100.4%) and compared well with those obtained by high-performance liquid chromatography (correlation coefficient, r(2) = 0.9965). PMID:24823260

  9. MWIR/LWIR filter based on Liquid-Crystal Fabry-Perot structure for tunable spectral imaging detection

    NASA Astrophysics Data System (ADS)

    Zhang, Huaidong; Muhammad, Afzal; Luo, Jun; Tong, Qing; Lei, Yu; Zhang, Xinyu; Sang, Hongshi; Xie, Changsheng

    2015-03-01

    An electrically tunable medium-wave infrared (MWIR)/long-wave infrared (LWIR) filter based on the key structure of Liquid-Crystal (LC) Fabry-Perot (FP), which works in the wavelength range from 2.5 μm to 12 μm, is designed and fabricated successfully in this paper. According to the optical interference principle of the FP cavity and electrically controlled birefringence of nematic LC molecules, the particular functions including spectral selection and spectral staring and spectral adjustment, can be realized by the developed MWIR/LWIR filter driven and controlled electrically. As to the LC-FP filter, both planar reflective mirrors are shaped by depositing a layer of aluminum (Al) film (∼60 nm) over one side of double-side polished Zinc Selenide (ZnSe) wafer (∼1 mm), and then polyimide (PI) layer with the thickness of ∼100 nm is coated directly on Al film. With typical sandwich architecture, the depth of the cavity with nematic LC molecules sealed in is ∼7.5 μm. To make sure the LC molecules parallel aligned and twist regularly under voltage driving signal applied on Al film, which also acts as electrode, the V-grooves are formed in PI layer with the depth of ∼90 nm and the width of ∼350 nm at average by strong rubbing. The typical transmission spectrum in MWIR&LWIR wavelength range and several spectral images in MWIR wavelength range based on the fabricated LC-FP filter, have been obtained through applying a voltage driving-signal with different root-means-square (RMS) value over the electrodes of LC-FP filter in the selected voltage range from 0VRMS to 19.8VRMS. The testing result demonstrates a prospect of realization smart spectral imaging and further integrating the LC-FP filter with infrared focal plane arrays (FPAs) to achieve the purpose infrared multispectral imaging. The developed MWIR&LWIR LC-FP filters show some obvious advantages such as wide working wavelength range, electrically tunable spectral selection, ultra-compact, low cost, being

  10. Electrically tunable infrared filter based on the liquid crystal Fabry-Perot structure for spectral imaging detection.

    PubMed

    Zhang, Huaidong; Muhammmad, Afzal; Luo, Jun; Tong, Qing; Lei, Yu; Zhang, Xinyu; Sang, Hongshi; Xie, Changsheng

    2014-09-01

    An electrically tunable infrared (IR) filter based on the liquid crystal (LC) Fabry-Perot (FP) key structure, which works in the wavelength range from 5.5 to 12 μm, is designed and fabricated successfully. Both planar reflective mirrors with a very high reflectivity of ∼95%, which are shaped by depositing a layer of aluminum (Al) film over one side of a double-sided polished zinc selenide wafer, are coupled into a dual-mirror FP cavity. The LC materials are filled into the FP cavity with a thickness of ∼7.5  μm for constructing the LC-FP filter, which is a typical type of sandwich architecture. The top and bottom mirrors of the FP cavity are further coated by an alignment layer with a thickness of ∼100  nm over Al film. The formed alignment layer is rubbed strongly to shape relatively deep V-grooves to anchor LC molecules effectively. Common optical tests show some particular properties; for instance, the existing three transmission peaks in the measured wavelength range, the minimum full width at half-maximum being ∼120  nm, and the maximum adjustment extent of the imaging wavelength being ∼500  nm through applying the voltage driving signal with a root mean square (RMS) value ranging from 0 to ∼19.8  V. The experiment results are consistent with the simulation, according to our model setup. The spectral images obtained in the long-wavelength IR range, through the LC-FP device driven by the voltage signal with a different RMS value, demonstrates the prospect of the realization of smart spectral imaging and further integrating the LC-FP filter with IR focal plane arrays. The developed LC-FP filters show some advantages, such as electrically tunable imaging wavelength, very high structural and photoelectronic response stability, small size and low power consumption, and a very high filling factor of more than 95% compared with common MEMS-FP spectral imaging approaches. PMID:25321356

  11. Detection of heavy-metal ions using liquid crystal droplet patterns modulated by interaction between negatively charged carboxylate and heavy-metal cations.

    PubMed

    Han, Gyeo-Re; Jang, Chang-Hyun

    2014-10-01

    Herein, we demonstrated a simple, sensitive, and rapid label-free detection method for heavy-metal (HM) ions using liquid crystal (LC) droplet patterns on a solid surface. Stearic-acid-doped LC droplet patterns were spontaneously generated on an n-octyltrichlorosilane (OTS)-treated glass substrate by evaporating a solution of the nematic LC, 4-cyano-4'-pentylbiphenyl (5CB), dissolved in heptane. The optical appearance of the droplet patterns was a dark crossed texture when in contact with air, which represents the homeotropic orientation of the LC. This was caused by the steric interaction between the LC molecules and the alkyl chains of the OTS-treated surface. The dark crossed appearance of the acid-doped LC patterns was maintained after the addition of phosphate buffered saline (PBS) solution (pH 8.1 at 25°C). The deprotonated stearic-acid molecules self-assembled through the LC/aqueous interface, thereby supporting the homeotropic anchoring of 5CB. However, the optical image of the acid-doped LC droplet patterns incubated with PBS containing HM ions appeared bright, indicating a planar orientation of 5CB at the aqueous/LC droplet interface. This dark to bright transition of the LC patterns was caused by HM ions attached to the deprotonated carboxylate moiety, followed by the sequential interruption of the self-assembly of the stearic acid at the LC/aqueous interface. The results showed that the acid-doped LC pattern system not only enabled the highly sensitive detection of HM ions at a sub-nanomolar concentration but it also facilitated rapid detection (<10 min) with simple procedures. PMID:25059128

  12. Detection of heavy-metal ions using liquid crystal droplet patterns modulated by interaction between negatively charged carboxylate and heavy-metal cations.

    PubMed

    Han, Gyeo-Re; Jang, Chang-Hyun

    2014-10-01

    Herein, we demonstrated a simple, sensitive, and rapid label-free detection method for heavy-metal (HM) ions using liquid crystal (LC) droplet patterns on a solid surface. Stearic-acid-doped LC droplet patterns were spontaneously generated on an n-octyltrichlorosilane (OTS)-treated glass substrate by evaporating a solution of the nematic LC, 4-cyano-4'-pentylbiphenyl (5CB), dissolved in heptane. The optical appearance of the droplet patterns was a dark crossed texture when in contact with air, which represents the homeotropic orientation of the LC. This was caused by the steric interaction between the LC molecules and the alkyl chains of the OTS-treated surface. The dark crossed appearance of the acid-doped LC patterns was maintained after the addition of phosphate buffered saline (PBS) solution (pH 8.1 at 25°C). The deprotonated stearic-acid molecules self-assembled through the LC/aqueous interface, thereby supporting the homeotropic anchoring of 5CB. However, the optical image of the acid-doped LC droplet patterns incubated with PBS containing HM ions appeared bright, indicating a planar orientation of 5CB at the aqueous/LC droplet interface. This dark to bright transition of the LC patterns was caused by HM ions attached to the deprotonated carboxylate moiety, followed by the sequential interruption of the self-assembly of the stearic acid at the LC/aqueous interface. The results showed that the acid-doped LC pattern system not only enabled the highly sensitive detection of HM ions at a sub-nanomolar concentration but it also facilitated rapid detection (<10 min) with simple procedures.

  13. Crystal face temperature determination means

    DOEpatents

    Nason, D.O.; Burger, A.

    1994-11-22

    An optically transparent furnace having a detection apparatus with a pedestal enclosed in an evacuated ampule for growing a crystal thereon is disclosed. Temperature differential is provided by a source heater, a base heater and a cold finger such that material migrates from a polycrystalline source material to grow the crystal. A quartz halogen lamp projects a collimated beam onto the crystal and a reflected beam is analyzed by a double monochromator and photomultiplier detection spectrometer and the detected peak position in the reflected energy spectrum of the reflected beam is interpreted to determine surface temperature of the crystal. 3 figs.

  14. A Fast and Sensitive Method for the Detection of Leuprolide Acetate: A High-Throughput Approach for the In Vitro Evaluation of Liquid Crystal Formulations.

    PubMed

    Báez-Santos, Yahira M; Otte, Andrew; Park, Kinam

    2016-05-01

    The suitability of using fluorescence spectroscopy to rapidly assay drug release by quantifying the time-dependent increase in total intrinsic protein fluorescence was assessed. Leuprolide acetate, a synthetic nonapeptide analogue of gonadotropin-releasing hormone (GnRH or LHRH), is the active pharmaceutical ingredient used to treat a wide range of sex hormone-related disorders, including advanced prostatic cancer, endometriosis, and precocious puberty. During the in vitro evaluation of drug delivery technologies for leuprolide acetate, one of the most time-consuming steps is the detection and accurate quantification of leuprolide release from formulation candidates. Thus far, the dominant means for leuprolide detection involves conventional multistep high-performance liquid chromatography (HPLC) methods, requiring sampling, dilutions, sample filtration, and chromatography, which can take up to 40 min for each sample. With the increasing demand for assay adaptation to high-throughput format, here we sought to exploit fluorescence spectroscopy as a tool to develop a novel method to rapidly assay the in vitro release of leuprolide acetate. By utilizing the intrinsic fluorescence of the tryptophan (Trp) and tyrosine (Tyr) amino acid residues present in the leuprolide nonapeptide, the in vitro release from liquid crystal formulations was accurately quantified as a function of fluorescence intensity. Here, we demonstrate that assaying leuprolide release using intrinsic protein fluorescence in a 96-well format requiring volumes as low as 100 μL is a cost-effective, rapid, and highly sensitive alternative to conventional HPLC methods. Furthermore, the high signal-to-noise ratios and robust Z'-factors of >0.8 indicate high sensitivity, precision, and feasibility for miniaturization, high-throughput format adaptation, and automation. PMID:27040983

  15. A Fast and Sensitive Method for the Detection of Leuprolide Acetate: A High-Throughput Approach for the In Vitro Evaluation of Liquid Crystal Formulations.

    PubMed

    Báez-Santos, Yahira M; Otte, Andrew; Park, Kinam

    2016-05-01

    The suitability of using fluorescence spectroscopy to rapidly assay drug release by quantifying the time-dependent increase in total intrinsic protein fluorescence was assessed. Leuprolide acetate, a synthetic nonapeptide analogue of gonadotropin-releasing hormone (GnRH or LHRH), is the active pharmaceutical ingredient used to treat a wide range of sex hormone-related disorders, including advanced prostatic cancer, endometriosis, and precocious puberty. During the in vitro evaluation of drug delivery technologies for leuprolide acetate, one of the most time-consuming steps is the detection and accurate quantification of leuprolide release from formulation candidates. Thus far, the dominant means for leuprolide detection involves conventional multistep high-performance liquid chromatography (HPLC) methods, requiring sampling, dilutions, sample filtration, and chromatography, which can take up to 40 min for each sample. With the increasing demand for assay adaptation to high-throughput format, here we sought to exploit fluorescence spectroscopy as a tool to develop a novel method to rapidly assay the in vitro release of leuprolide acetate. By utilizing the intrinsic fluorescence of the tryptophan (Trp) and tyrosine (Tyr) amino acid residues present in the leuprolide nonapeptide, the in vitro release from liquid crystal formulations was accurately quantified as a function of fluorescence intensity. Here, we demonstrate that assaying leuprolide release using intrinsic protein fluorescence in a 96-well format requiring volumes as low as 100 μL is a cost-effective, rapid, and highly sensitive alternative to conventional HPLC methods. Furthermore, the high signal-to-noise ratios and robust Z'-factors of >0.8 indicate high sensitivity, precision, and feasibility for miniaturization, high-throughput format adaptation, and automation.

  16. Glycine lithium nitrate crystals

    NASA Astrophysics Data System (ADS)

    González-Valenzuela, R.; Hernández-Paredes, J.; Medrano-Pesqueira, T.; Esparza-Ponce, H. E.; Jesús-Castillo, S.; Rodriguez-Mijangos, R.; Terpugov, V. S.; Alvarez-Ramos, M. E.; Duarte-Möller, A.

    Crystals of glycine lithium nitrate with non-linear optical properties have been grown in a solution by slow evaporation at room temperature. The crystal shows a good thermal stability from room temperature to 175 °C where the crystal begins to degrade. This property is desirable for future technological applications. Also, a good performance on the second harmonic generation was found, characterizing the emitted dominant wavelength by a customized indirect procedure using luminance and chromaticity measured data based on the CIE-1931 standard. Additionally, the 532 nm signal was detected by using a variant to the Kurtz and Perry method.

  17. Crystal Systems.

    ERIC Educational Resources Information Center

    Schomaker, Verner; Lingafelter, E. C.

    1985-01-01

    Discusses characteristics of crystal systems, comparing (in table format) crystal systems with lattice types, number of restrictions, nature of the restrictions, and other lattices that can accidently show the same metrical symmetry. (JN)

  18. Virtual Crystallizer

    SciTech Connect

    Land, T A; Dylla-Spears, R; Thorsness, C B

    2006-08-29

    Large dihydrogen phosphate (KDP) crystals are grown in large crystallizers to provide raw material for the manufacture of optical components for large laser systems. It is a challenge to grow crystal with sufficient mass and geometric properties to allow large optical plates to be cut from them. In addition, KDP has long been the canonical solution crystal for study of growth processes. To assist in the production of the crystals and the understanding of crystal growth phenomena, analysis of growth habits of large KDP crystals has been studied, small scale kinetic experiments have been performed, mass transfer rates in model systems have been measured, and computational-fluid-mechanics tools have been used to develop an engineering model of the crystal growth process. The model has been tested by looking at its ability to simulate the growth of nine KDP boules that all weighed more than 200 kg.

  19. Crystal growing

    NASA Technical Reports Server (NTRS)

    Neville, J. P.

    1990-01-01

    One objective is to demonstrate the way crystals grow and how they affect the behavior of material. Another objective is to compare the growth of crystals in metals and nonmetals. The procedures, which involve a supersaturated solution of a salt that will separate into crystals on cooling and the pouring off of an eutectic solution to expose the crystals formed by a solid solution when an alloy of two metals forms a solid and eutectic solution on cooling, are described.

  20. Channeling through Bent Crystals

    SciTech Connect

    Mack, Stephanie; /Ottawa U. /SLAC

    2012-09-07

    Bent crystals have demonstrated potential for use in beam collimation. A process called channeling is when accelerated particle beams are trapped by the nuclear potentials in the atomic planes within a crystal lattice. If the crystal is bent then the particles can follow the bending angle of the crystal. There are several different effects that are observed when particles travel through a bent crystal including dechanneling, volume capture, volume reflection and channeling. With a crystal placed at the edge of a particle beam, part of the fringe of the beam can be deflected away towards a detector or beam dump, thus helping collimate the beam. There is currently FORTRAN code by Igor Yazynin that has been used to model the passage of particles through a bent crystal. Using this code, the effects mentioned were explored for beam energy that would be seen at the Facility for Advanced Accelerator Experimental Tests (FACET) at a range of crystal orientations with respect to the incoming beam. After propagating 5 meters in vacuum space past the crystal the channeled particles were observed to separate from most of the beam with some noise due to dechanneled particles. Progressively smaller bending radii, with corresponding shorter crystal lengths, were compared and it was seen that multiple scattering decreases with the length of the crystal therefore allowing for cleaner detection of the channeled particles. The input beam was then modified and only a portion of the beam sent through the crystal. With the majority of the beam not affected by the crystal, most particles were not deflected and after propagation the channeled particles were seen to be deflected approximately 5mm. After a portion of the beam travels through the crystal, the entire beam was then sent through a quadrupole magnet, which increased the separation of the channeled particles from the remainder of the beam to a distance of around 20mm. A different code, which was developed at SLAC, was used to

  1. Naphthoquinone based Chemosensor 2-(2‧-aminoethylpyridine)-3-chloro-1,4-naphthoquinone: Detection of metal ions, X-ray -crystal structures and DFT studies

    NASA Astrophysics Data System (ADS)

    Patil, Amit; Ware, Anuja P.; Bhand, Sujit; Chakrovarty, Debamitra; Gonnade, Rajesh; Pingale, Subhash S.; Salunke-Gawali, Sunita

    2016-06-01

    Naphthoquinone based Chemosensor 2; 2-(2‧-aminoethylpyridine)-3-chloro-1,4-napthoquinone have been synthesized and characterized. Chemosensor 2 crystallizes in the orthorhombic space group Pbcn and shows extensive intramolecular as well as intermolecular hydrogen bonding interactions. Each molecule of Chemosensor 2 showed interaction with five neighboring molecules via C-H⋯N, N-H⋯N, C-H⋯Cl and C-H⋯O interactions. Slipped π-π stacking interaction was observed in adjacent quinonoid and benzenoid rings. Chemosensor abilities of Chemosensor 2 ligand have been evaluated with metal ions viz. Cu2+, Ni2+, Zn2+, Co2+, Fe3+, Mn2+, Cr3+, Hg2+, La3+ and Cd2+ in methanol, methanol-water mixture and in presence of mild base triethylamine. Stoichiometry of Chemosensor 2 with metal ions such as Cu2+, Ni2+, Zn2+and Co2+ ions was determined by Jobs method in methanol and were found as 1:1 for Cu2+and 2:1 for Ni2+, Zn2+ Co2+. The variation in the metal ligand ratio is observed in aqueous media for Cu2+. Chemosensor 2 can be used selectively for naked eye detection of Cu2+ ions. The association constant obtained in methanol shows the trend Cu2+>Ni2+>Co2+. Cu2+ and two (Ni-1 and Ni-2) Ni2+ complexes were synthesized. Ni-2 complex showed coordination of Chemosensor 2 ligands was through pyridine nitrogen's only. The Chemosensor 2 and its deprotonated forms in methanol, water and triethylamine were also studied by TD-DFT studies.

  2. Small-scale microcosms to detect chemical induced changes in soil nematode communities--effects of crystal proteins and Bt-maize plant material.

    PubMed

    Höss, Sebastian; Reiff, Nicola; Nguyen, Hang T; Jehle, Johannes A; Hermes, Hanna; Traunspurger, Walter

    2014-02-15

    Small-scale laboratory microcosms (30 g soil in 50 ml tubes) were evaluated for their suitability to assess the impact of chemicals on in situ soil nematode communities. For this purpose, appropriate conditions in the microcosms were explored to ensure stable conditions and a homogenous distribution of the nematodes. Then, the microcosms were used to assess the toxicity of insecticidal crystal proteins (Cry1A.105, Cry2Ab2, Cry3Bb1) present in genetically modified maize (MON89034×MON88017) on in situ nematode communities. Highly abundant and genus rich nematode communities could be maintained over a period of 12 weeks. Due to a low variance between the replicates of the treatments, low detection limits could be achieved. Using meaningful stress indices, such as the maturity indices, the microcosm study revealed dose-dependent effects of the insecticidal Cry proteins that could be verified as toxic effects by comparing with effects of two positive controls (Cu, nematicidal Cry5B). Moreover, toxic effects could be differentiated from organic enrichment effects that were induced by the addition of plant material. With a NOECCommunity of 0.1 mg kg(-1) dry wt, the nematode communities reacted considerably more sensitive to the Cry proteins than a single-species nematode toxicity test (NOEC: 29 mg l(-1)). The small-scale microcosm set-up turned out to be a suitable, low-budget tool for assessing the toxicity of chemicals on soil nematodes on community level, representing a link between single-species toxicity tests and large scale outdoor mesocosms. PMID:24317172

  3. Calibration of the infrared molar absorption coefficients by elastic recoil detection analysis (ERDA) for H measurements in olivine and clinopyroxene crystals and rhyolitic glasses

    NASA Astrophysics Data System (ADS)

    Aubaud, C.; Bureau, H.; Raepsaet, C.; Khodja, H.; Hirschmann, M. M.; Withers, A. C.; Bell, D. R.

    2007-12-01

    Fourier transform infrared (FTIR) spectroscopy is the most widely applied technique for measuring hydrogen in nominally anhydrous minerals (NAMs) and silicate glasses. FTIR is rapid, sensitive, widely available and gives information on the bonding environment of H-bearing species. H determination relies on the Beer-Lambert law and therefore requires constraints on the applicable molar absorption coefficient, ɛ. Values of ɛ may be derived only from independent absolute methods. These ɛ are now reasonably well known for glasses, but to date determinations of ɛ applicable to NAMs are extremely limited and subject to uncertainties. Most notably, the Paterson (1982) calibration gives H contents in olivine that are a factor of 2.5- 3.5 lower than those suggested by the Bell et al. JGR 2003 calibration. We performed elastic recoil detection analysis (ERDA) on a range of samples that had been previously analyzed by FTIR, including natural rhyolitic glasses (1430-1772 ppm H2O), natural and synthetic olivine (0-910 ppm), natural orthopyroxene (38-147 ppm), and natural clinopyroxene crystals (0-490 ppm). ERDA is a nuclear microprobe technique that yields matrix-independent absolute determinations of H concentration. A 3 MeV beam of 4He is employed at high spatial resolution (50 × 200 microns). The detection limit, determined from analysis of dry minerals is 150±20 ppm H2O, too great for analysis of many NAMs from the upper mantle, but applicable to H-rich natural and synthetic NAMs. For glasses, synthetic olivines, and clinopyroxenes, we found good proportionality between the measured ERDA hydrogen concentration and the linear (rhyolite) or integrated (minerals) absorbance measured by FTIR. The ɛ found for rhyolite (103±9 l/mol per cm) is close to that of 88±2 l/mol per cm given by Dobson et al. (GCA, 1989). For clinopyroxene, we obtain ɛ 47010±6070 l/mol per cm2, slightly larger than 38300±1700 l/mol per cm2 found by Bell et al. (Am. Min. 1995). Finally, for

  4. Simultaneous detection of surface coverage and structure of krypton films on gold by helium atom diffraction and quartz crystal microbalance techniques.

    PubMed

    Danışman, M Fatih; Özkan, Berrin

    2011-11-01

    We describe a quartz crystal microbalance setup that can be operated at low temperatures in ultra high vacuum with gold electrode surfaces acting as substrate surface for helium diffraction measurements. By simultaneous measurement of helium specular reflection intensity from the electrode surface and resonance frequency shift of the crystal during film adsorption, helium diffraction data can be correlated to film thickness. In addition, effects of interfacial viscosity on the helium diffraction pattern could be observed. To this end, first, flat gold films on AT cut quartz crystals were prepared which yield high enough helium specular reflection intensity. Then the crystals were mounted in the helium diffractometer sample holder and driven by means of a frequency modulation driving setup. Different crystal geometries were tested to obtain the best quality factor and preliminary measurements were performed on Kr films on gold surfaces. While the crystal structure and coverage of krypton films as a function of substrate temperature could successfully be determined, no depinning effects could be observed.

  5. Simultaneous detection of surface coverage and structure of krypton films on gold by helium atom diffraction and quartz crystal microbalance techniques

    SciTech Connect

    Danisman, M. Fatih; Oezkan, Berrin

    2011-11-15

    We describe a quartz crystal microbalance setup that can be operated at low temperatures in ultra high vacuum with gold electrode surfaces acting as substrate surface for helium diffraction measurements. By simultaneous measurement of helium specular reflection intensity from the electrode surface and resonance frequency shift of the crystal during film adsorption, helium diffraction data can be correlated to film thickness. In addition, effects of interfacial viscosity on the helium diffraction pattern could be observed. To this end, first, flat gold films on AT cut quartz crystals were prepared which yield high enough helium specular reflection intensity. Then the crystals were mounted in the helium diffractometer sample holder and driven by means of a frequency modulation driving setup. Different crystal geometries were tested to obtain the best quality factor and preliminary measurements were performed on Kr films on gold surfaces. While the crystal structure and coverage of krypton films as a function of substrate temperature could successfully be determined, no depinning effects could be observed.

  6. Lysozyme Crystal

    NASA Technical Reports Server (NTRS)

    2004-01-01

    To the crystallographer, this may not be a diamond but it is just as priceless. A Lysozyme crystal grown in orbit looks great under a microscope, but the real test is X-ray crystallography. The colors are caused by polarizing filters. Proteins can form crystals generated by rows and columns of molecules that form up like soldiers on a parade ground. Shining X-rays through a crystal will produce a pattern of dots that can be decoded to reveal the arrangement of the atoms in the molecules making up the crystal. Like the troops in formation, uniformity and order are everything in X-ray crystallography. X-rays have much shorter wavelengths than visible light, so the best looking crystals under the microscope won't necessarily pass muster under the X-rays. In order to have crystals to use for X-ray diffraction studies, crystals need to be fairly large and well ordered. Scientists also need lots of crystals since exposure to air, the process of X-raying them, and other factors destroy them. Growing protein crystals in space has yielded striking results. Lysozyme's structure is well known and it has become a standard in many crystallization studies on Earth and in space.

  7. RNA Crystallization

    NASA Technical Reports Server (NTRS)

    Golden, Barbara L.; Kundrot, Craig E.

    2003-01-01

    RNA molecules may be crystallized using variations of the methods developed for protein crystallography. As the technology has become available to syntheisize and purify RNA molecules in the quantities and with the quality that is required for crystallography, the field of RNA structure has exploded. The first consideration when crystallizing an RNA is the sequence, which may be varied in a rational way to enhance crystallizability or prevent formation of alternate structures. Once a sequence has been designed, the RNA may be synthesized chemically by solid-state synthesis, or it may be produced enzymatically using RNA polymerase and an appropriate DNA template. Purification of milligram quantities of RNA can be accomplished by HPLC or gel electrophoresis. As with proteins, crystallization of RNA is usually accomplished by vapor diffusion techniques. There are several considerations that are either unique to RNA crystallization or more important for RNA crystallization. Techniques for design, synthesis, purification, and crystallization of RNAs will be reviewed here.

  8. Protein Crystallization

    NASA Technical Reports Server (NTRS)

    Chernov, Alexander A.

    2005-01-01

    Nucleation, growth and perfection of protein crystals will be overviewed along with crystal mechanical properties. The knowledge is based on experiments using optical and force crystals behave similar to inorganic crystals, though with a difference in orders of magnitude in growing parameters. For example, the low incorporation rate of large biomolecules requires up to 100 times larger supersaturation to grow protein, rather than inorganic crystals. Nucleation is often poorly reproducible, partly because of turbulence accompanying the mixing of precipitant with protein solution. Light scattering reveals fluctuations of molecular cluster size, its growth, surface energies and increased clustering as protein ages. Growth most often occurs layer-by-layer resulting in faceted crystals. New molecular layer on crystal face is terminated by a step where molecular incorporation occurs. Quantitative data on the incorporation rate will be discussed. Rounded crystals with molecularly disordered interfaces will be explained. Defects in crystals compromise the x-ray diffraction resolution crucially needed to find the 3D atomic structure of biomolecules. The defects are immobile so that birth defects stay forever. All lattice defects known for inorganics are revealed in protein crystals. Contribution of molecular conformations to lattice disorder is important, but not studied. This contribution may be enhanced by stress field from other defects. Homologous impurities (e.g., dimers, acetylated molecules) are trapped more willingly by a growing crystal than foreign protein impurities. The trapped impurities induce internal stress eliminated in crystals exceeding a critical size (part of mni for ferritin, lysozyme). Lesser impurities are trapped from stagnant, as compared to the flowing, solution. Freezing may induce much more defects unless quickly amorphysizing intracrystalline water.

  9. Computational crystallization.

    PubMed

    Altan, Irem; Charbonneau, Patrick; Snell, Edward H

    2016-07-15

    Crystallization is a key step in macromolecular structure determination by crystallography. While a robust theoretical treatment of the process is available, due to the complexity of the system, the experimental process is still largely one of trial and error. In this article, efforts in the field are discussed together with a theoretical underpinning using a solubility phase diagram. Prior knowledge has been used to develop tools that computationally predict the crystallization outcome and define mutational approaches that enhance the likelihood of crystallization. For the most part these tools are based on binary outcomes (crystal or no crystal), and the full information contained in an assembly of crystallization screening experiments is lost. The potential of this additional information is illustrated by examples where new biological knowledge can be obtained and where a target can be sub-categorized to predict which class of reagents provides the crystallization driving force. Computational analysis of crystallization requires complete and correctly formatted data. While massive crystallization screening efforts are under way, the data available from many of these studies are sparse. The potential for this data and the steps needed to realize this potential are discussed.

  10. Unifying the crystallization behavior of hexagonal and square crystals with the phase-field-crystal model

    NASA Astrophysics Data System (ADS)

    Tao, Yang; Zheng, Chen; Jing, Zhang; Yongxin, Wang; Yanli, Lu

    2016-03-01

    By employing the phase-field-crystal models, the atomic crystallization process of hexagonal and square crystals is investigated with the emphasis on the growth mechanism and morphological change. A unified regime describing the crystallization behavior of both crystals is obtained with the thermodynamic driving force varying. By increasing the driving force, both crystals (in the steady-state) transform from a faceted polygon to an apex-bulged polygon, and then into a symmetric dendrite. For the faceted polygon, the interface advances by a layer-by-layer (LL) mode while for the apex-bulged polygonal and the dendritic crystals, it first adopts the LL mode and then transits into the multi-layer (ML) mode in the later stage. In particular, a shift of the nucleation sites from the face center to the area around the crystal tips is detected in the early growth stage of both crystals and is rationalized in terms of the relation between the crystal size and the driving force distribution. Finally, a parameter characterizing the complex shape change of square crystal is introduced. Project supported by the National Natural Science Foundation of China (Grant Nos. 54175378, 51474176, and 51274167), the Natural Science Foundation of Shaanxi Province, China (Grant No. 2014JM7261), and the Doctoral Foundation Program of Ministry of China (Grant No. 20136102120021).

  11. Robotic CCD microscope for enhanced crystal recognition

    DOEpatents

    Segelke, Brent W.; Toppani, Dominique

    2007-11-06

    A robotic CCD microscope and procedures to automate crystal recognition. The robotic CCD microscope and procedures enables more accurate crystal recognition, leading to fewer false negative and fewer false positives, and enable detection of smaller crystals compared to other methods available today.

  12. Crystal Data

    National Institute of Standards and Technology Data Gateway

    SRD 3 NIST Crystal Data (PC database for purchase)   NIST Crystal Data contains chemical, physical, and crystallographic information useful to characterize more than 237,671 inorganic and organic crystalline materials. The data include the standard cell parameters, cell volume, space group number and symbol, calculated density, chemical formula, chemical name, and classification by chemical type.

  13. Invisible defects in complex crystals

    SciTech Connect

    Longhi, Stefano Della Valle, Giuseppe

    2013-07-15

    We show that invisible localized defects, i.e. defects that cannot be detected by an outside observer, can be realized in a crystal with an engineered imaginary potential at the defect site. The invisible defects are synthesized by means of supersymmetric (Darboux) transformations of an ordinary crystal using band-edge wavefunctions to construct the superpotential. The complex crystal has an entire real-valued energy spectrum and Bragg scattering is not influenced by the defects. An example of complex crystal synthesis is presented for the Mathieu potential. -- Highlights: •We show the existence of invisible localized defects in complex crystals. •They turn out to be fully invisible to Bloch waves belonging to any lattice band. •An example of invisible defect is presented for a PT-symmetric Mathieu crystal.

  14. Crystal face temperature determination means

    DOEpatents

    Nason, Donald O.; Burger, Arnold

    1994-01-01

    An optically transparent furnace (10) having a detection apparatus (29) with a pedestal (12) enclosed in an evacuated ampule (16) for growing a crystal (14) thereon. Temperature differential is provided by a source heater (20), a base heater (24) and a cold finger (26) such that material migrates from a polycrystalline source material (18) to grow the crystal (14). A quartz halogen lamp (32) projects a collimated beam (30) onto the crystal (14) and a reflected beam (34) is analyzed by a double monochromator and photomultiplier detection spectrometer (40) and the detected peak position (48) in the reflected energy spectrum (44) of the reflected beam (34) is interpreted to determine surface temperature of the crystal (14).

  15. Microfluidic crystallization.

    PubMed

    Leng, Jacques; Salmon, Jean-Baptiste

    2009-01-01

    Microfluidics offers a wide range of new tools that permit one to revisit the formation of crystals in solution and yield insights into crystallization processes. We review such recent microfluidic devices and particularly emphasize lab-on-chips dedicated to the high-throughput screening of crystallization conditions of proteins with nanolitre consumption. We also thoroughly discuss the possibilities offered by the microfluidic tools to acquire thermodynamic and kinetic data that may improve industrial processes and shed a new light on nucleation and growth mechanisms.

  16. Crystal Furnace

    NASA Technical Reports Server (NTRS)

    1985-01-01

    A "melt recharging" technique which eliminates the cooldown and heating periods in a crystal "growing" crucible, resulted from a Jet Propulsion Laboratory (JPL)/Kayex Corporation program. Previously, the cost of growing the silicon solar cells had been very high. The JPL/Kayex system improved productivity by serially growing crystals from the same crucible using a melt recharger which made it possible to add raw silicon to an operating crucible. An isolation value, developed by Kayex, allowed the hopper to be lowered into the crucible without disturbing the inert gas atmosphere. The resulting product, a CG6000 crystal growing furnace, has become the company's major product.

  17. The effect of Se content on defect levels in CuInSe{sub 2} single crystals detected by photoacoustic spectrometry

    SciTech Connect

    Zegadi, A.; Yakushev, M.V.; Ahmed, E.; Hill, A.E.; Tomlinson, R.D.; Slifkin, M.A.

    1994-12-31

    The objective of this paper is to investigate the impact of changes in the selenium content of CuInSe{sub 2} single crystals on their optical properties in the subgap region of the infrared spectrum. A high resolution near-infrared photoacoustic spectrometer of the gas-microphone type is used for room temperature analysis of non-radiative defect states in as-grown n and p-type CIS crystals. Samples with an excess and a deficiency of Se (5% off the stoichiometric composition), were grown from the melt by the vertical Bridgman technique. The absorption coefficient has been derived from photoacoustic spectra in order to establish activation energies for several defect-related energy levels.

  18. Dynamically controlled crystal growth system

    NASA Technical Reports Server (NTRS)

    Bray, Terry L. (Inventor); Kim, Larry J. (Inventor); Harrington, Michael (Inventor); DeLucas, Lawrence J. (Inventor)

    2002-01-01

    Crystal growth can be initiated and controlled by dynamically controlled vapor diffusion or temperature change. In one aspect, the present invention uses a precisely controlled vapor diffusion approach to monitor and control protein crystal growth. The system utilizes a humidity sensor and various interfaces under computer control to effect virtually any evaporation rate from a number of different growth solutions simultaneously by means of an evaporative gas flow. A static laser light scattering sensor can be used to detect aggregation events and trigger a change in the evaporation rate for a growth solution. A control/follower configuration can be used to actively monitor one chamber and accurately control replicate chambers relative to the control chamber. In a second aspect, the invention exploits the varying solubility of proteins versus temperature to control the growth of protein crystals. This system contains miniature thermoelectric devices under microcomputer control that change temperature as needed to grow crystals of a given protein. Complex temperature ramps are possible using this approach. A static laser light scattering probe also can be used in this system as a non-invasive probe for detection of aggregation events. The automated dynamic control system provides systematic and predictable responses with regard to crystal size. These systems can be used for microgravity crystallization projects, for example in a space shuttle, and for crystallization work under terrestial conditions. The present invention is particularly useful for macromolecular crystallization, e.g. for proteins, polypeptides, nucleic acids, viruses and virus particles.

  19. Fiber thermometer based on the cross detection of the fluorescence lifetime of Cr3+:YAG crystal fiber and Plank"s blackbody radiation from cryogenic up to 1400°C

    NASA Astrophysics Data System (ADS)

    Ye, Linhua; Qiu, Yanqing; Shen, Yonghang; He, Sailing

    2005-02-01

    A fiber thermometer using the cross detection of the fluorescence lifetime and blackbody radiation was presented to measure temperature from -10°C up to 1400°C. Using a long pure YAG crystal fiber as the seed and a 0.1 at. % Cr2O3-doped Y3Al5O12 sintered powder rod as the source rod, a YAG fiber thermal probe with Cr3+ -ions doped end was grown by laser heated pedestal growth method. A blackbody cavity was constructed by sintered a thin ceramic layer around the Cr3+: YAG fiber end. A phase-locked detection scheme was used for the fluorescence lifetime detection. The fluorescence characteristics of the Cr3+-ions doped YAG was analyzed in a temperature range from -10°C up to 500°C. From 350°C to 1400°C the blackbody radiation signal in a narrow waveband were detected. Because the fluorescence lifetime was intensity independent, it should have the long-term stability and would not change if the fiber connectors of the probes were realigned. So the fluorescence lifetime based temperature measurement could be used to recalibrate that based on the blackbody radiation detection. Preliminary experimental results showed that the system could achieve a resolution much better than 1°C over the whole temperature range from -10°C to 1400°C.

  20. Crystal Compton Camera

    SciTech Connect

    Ziock, Klaus-Peter; Braverman, Joshua B.; Harrison, Mark J.; Hornback, Donald Eric; Fabris, Lorenzo; Newby, Jason

    2013-09-26

    Stand-off detection is one of the most important radiation detection capabilities for arms control and the control of illicit nuclear materials. For long range passive detection one requires a large detector and a means of “seeing through” the naturally occurring and varying background radiation, i.e. imaging. Arguably, Compton imaging is the best approach over much of the emission band suitable for long range detection. It provides not only imaging, but more information about the direction of incidence of each detected gamma-ray than the alternate approach of coded-aperture imaging. The directional information allows one to reduce the background and hence improve the sensitivity of a measurement. However, to make an efficient Compton imager requires localizing and measuring the simultaneous energy depositions when gamma-rays Compton scatter and are subsequently captured within a single, large detector volume. This concept has been demonstrated in semi-conductor detectors (HPGe, CZT, Si) but at ~ $1k/cm3 these materials are too expensive to build the large systems needed for standoff detection. Scintillator detectors, such as NaI(Tl), are two orders of magnitude less expensive and possess the energy resolution required to make such an imager. However, they do not currently have the ability to localize closely spaced, simultaneous energy depositions in a single large crystal. In this project we are applying a new technique that should, for the first time ever, allow cubic-millimeter event localization in a bulk scintillator crystal.

  1. Crystal growth furnace safety system validation

    NASA Technical Reports Server (NTRS)

    Mackowski, D. W.; Hartfield, R.; Bhavnani, S. H.; Belcher, V. M.

    1994-01-01

    The findings are reported regarding the safe operation of the NASA crystal growth furnace (CGF) and potential methods for detecting containment failures of the furnace. The main conclusions are summarized by ampoule leak detection, cartridge leak detection, and detection of hazardous species in the experiment apparatus container (EAC).

  2. Sensitive detection of trypsin using liquid-crystal droplet patterns modulated by interactions between poly-L-lysine and a phospholipid monolayer.

    PubMed

    Zhang, Minmin; Jang, Chang-Hyun

    2014-08-25

    Liquid-crystal (LC) droplet patterns are formed on a glass slide by evaporating a solution of nematic LC dissolved in heptane. In the presence of an anionic phospholipid, 1,2-dioleoyl-sn-glycero-3-phospho-rac-(1-glycerol) (DOPG), the LCs display a dark cross pattern, indicating a homeotropic orientation. When LC patterns are incubated with an aqueous mixture of DOPG and poly-L-lysine (PLL), there is a transition in the LC pattern from a dark cross to a bright fan shape due to the electrostatic interaction between DOPG and PLL. Known to catalyze the hydrolysis of PLL into oligopeptide fragments, trypsin is preincubated with PLL, significantly decreasing the interactions between PLL and DOPG. LCs adopt a perpendicular orientation at the water-LC droplet interface, which gives rise to a dark cross pattern. This optical response of LC droplets is the basis for a quick and sensitive biosensor for trypsin. PMID:24850496

  3. Point defects in CdTexSe1-x crystals grown from a Te-rich solution for applications in detecting radiation

    SciTech Connect

    Gul, R.; Roy, U. N.; Bolotnikov, A. E.; Camarda, G. S.; Cui, Y.; Hossain, A.; Lee, W.; Yang, G.; Burger, A.; James, R. B.; Cui, Y.

    2015-04-15

    We investigated cadmium telluride selenide (CdTeSe) crystals, newly grown by the Traveling Heater Method (THM), for the presence and abundance of point defects. Deep Level Transient spectroscopy (I-DLTS) was used to determine the energies of the traps, their capture cross sections, and densities. The bias across the detectors was varied from (1–30) V. Four types of point defects were identified, ranging from 10 meV to 0.35 eV. Two dominant traps at energies of 0.18 eV and 0.14 eV were studied in depth. Cd vacancies are found at lower concentrations than other point defects present in the material.

  4. Point defects in CdTexSe1-x crystals grown from a Te-rich solution for applications in detecting radiation

    DOE PAGESBeta

    Gul, R.; Roy, U. N.; Bolotnikov, A. E.; Camarda, G. S.; Cui, Y.; Hossain, A.; Lee, W.; Yang, G.; Burger, A.; James, R. B.; et al

    2015-04-15

    We investigated cadmium telluride selenide (CdTeSe) crystals, newly grown by the Traveling Heater Method (THM), for the presence and abundance of point defects. Deep Level Transient spectroscopy (I-DLTS) was used to determine the energies of the traps, their capture cross sections, and densities. The bias across the detectors was varied from (1–30) V. Four types of point defects were identified, ranging from 10 meV to 0.35 eV. Two dominant traps at energies of 0.18 eV and 0.14 eV were studied in depth. Cd vacancies are found at lower concentrations than other point defects present in the material.

  5. Laser Crystal

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Lightning Optical Corporation, under an SBIR (Small Business Innovative Research) agreement with Langley Research Center, manufactures oxide and fluoride laser gain crystals, as well as various nonlinear materials. The ultimate result of this research program is the commercial availability in the marketplace of a reliable source of high-quality, damage resistant laser material, primarily for diode-pumping applications.

  6. Comparing Crystals

    ERIC Educational Resources Information Center

    Sharp, Janet; Hoiberg, Karen; Chumbley, Scott

    2003-01-01

    This standard lesson on identifying salt and sugar crystals expands into an opportunity for students to develop their observation, questioning, and modeling skills. Although sugar and salt may look similar, students discovered that they looked very different under a magnifying glass and behaved differently when dissolved in water. In addition,…

  7. Optical Crystals

    ERIC Educational Resources Information Center

    Bergsten, Ronald

    1974-01-01

    Discusses the production and structure of a sequence of optical crystals which can serve as one-, two-, and three-dimensional diffraction plates to illustrate diffraction patterns by using light rather than x-rays or particles. Applications to qualitative presentations of Laue theory at the secondary and college levels are recommended. (CC)

  8. Therapeutic Crystals

    ERIC Educational Resources Information Center

    Bond, Charles S.

    2014-01-01

    Some readers might not fully know what the difference is between crystallography, and the "new age" practice of dangling crystals around the body to capitalise on their healing energy. The latter is often considered to be superstition, while ironically, the former has actually resulted in real rationally-based healing of human diseases…

  9. Detection of Significant Aprotic Solvent Effects on the Conformational Distribution of Methyl 4-Nitrophenyl Sulfoxide: From Gas-Phase Rotational to Liquid-Crystal NMR Spectroscopy.

    PubMed

    Celebre, Giorgio; De Luca, Giuseppina; Di Pietro, Maria Enrica; Giuliano, Barbara Michela; Melandri, Sonia; Cinacchi, Giorgio

    2015-08-01

    The conformational equilibrium of methyl 4-nitrophenyl sulfoxide (MNPSO) was experimentally investigated in the gas phase by using microwave spectroscopy and in isotropic and nematic liquid-crystal solutions, in which the solvents are nonaqueous and aprotic, by using NMR spectroscopy; moreover, it was theoretically studied in vacuo and in solution at different levels of theory. The overall set of results indicates a significant dependence of the solute conformational distribution on the solvent dielectric permittivity constant: when dissolved in low-polarity media, the most stable conformation of MNPSO proved to be strongly twisted with respect to that in more polar solvents, in which the conformational distribution maximum essentially coincides with that obtained in the gas phase. We discuss a possible explanation of this behavior, which rests on electrostatic solute-solvent interactions and is supported by calculations of the solute electric dipole moment as a function of the torsional angle. This function shows that the least polar conformation of MNPSO is located at a twist angle close to that of the conformational distribution maximum found in less-polar solvents. This fact, associated with a relatively flat torsional potential, can justify the stabilization of the twisted conformation by the less-polar solvents.

  10. Passive particle dosimetry. [silver halide crystal growth

    NASA Technical Reports Server (NTRS)

    Childs, C. B.

    1977-01-01

    Present methods of dosimetry are reviewed with emphasis on the processes using silver chloride crystals for ionizing particle dosimetry. Differences between the ability of various crystals to record ionizing particle paths are directly related to impurities in the range of a few ppm (parts per million). To understand the roles of these impurities in the process, a method for consistent production of high purity silver chloride, and silver bromide was developed which yields silver halides with detectable impurity content less than 1 ppm. This high purity silver chloride was used in growing crystals with controlled doping. Crystals were grown by both the Czochalski method and the Bridgman method, and the Bridgman grown crystals were used for the experiments discussed. The distribution coefficients of ten divalent cations were determined for the Bridgman crystals. The best dosimeters were made with silver chloride crystals containing 5 to 10 ppm of lead; other impurities tested did not produce proper dosimeters.

  11. In vitro detection of human breast cancer cells (SK-BR3) using herceptin-conjugated liquid crystal microdroplets as a sensing platform.

    PubMed

    Ding, Wang; Gupta, Kailash Chandra; Park, Soo-Young; Kim, Young-Kyoo; Kang, Inn-Kyu

    2016-10-20

    The present study utilizes antibody-protein interactions to develop an LC microdroplet based biosensor for naked eye detection of SK-BR3 human breast cancer cells. The herceptin antibody-conjugated LC microdroplets were fabricated using 4-cyano-4'-pentyl biphenyl (5CB) as the liquid crystalline phase and sodium dodecyl sulfate (SDS) as the surfactant. The poly (styrene-b-acrylic acid) amphiphilic block copolymer (PS-b-PA) played a role as a modifier for the liquid crystalline interfaces. The 5CB molecules in the herceptin antibody-conjugated LC microdroplets have shown an orientation transition from radial to bipolar on selective interactions with targeted SK-BR3 breast cancer cells, which are over expressed by the human epidermal growth factor receptor 2-positive (HER2). The herceptin antibody-conjugated LC microdroplets are found to be highly selective in the detection of SK-BR3 cancer cells in the presence of control cells, such as KB cancer cells and fibroblast (FB), and also in the presence of 10% human blood plasma. The interaction forces of the SK-BR3 cancer cells were only effective in causing orientation transitions in 5CB molecules in the LC microdroplets, which clearly suggested that the herceptin antibody-conjugated LC microdroplets could be used as a selective biosensor for a real-time detection of SK-BR3 cancer cells in biological fluids.

  12. In vitro detection of human breast cancer cells (SK-BR3) using herceptin-conjugated liquid crystal microdroplets as a sensing platform.

    PubMed

    Ding, Wang; Gupta, Kailash Chandra; Park, Soo-Young; Kim, Young-Kyoo; Kang, Inn-Kyu

    2016-10-20

    The present study utilizes antibody-protein interactions to develop an LC microdroplet based biosensor for naked eye detection of SK-BR3 human breast cancer cells. The herceptin antibody-conjugated LC microdroplets were fabricated using 4-cyano-4'-pentyl biphenyl (5CB) as the liquid crystalline phase and sodium dodecyl sulfate (SDS) as the surfactant. The poly (styrene-b-acrylic acid) amphiphilic block copolymer (PS-b-PA) played a role as a modifier for the liquid crystalline interfaces. The 5CB molecules in the herceptin antibody-conjugated LC microdroplets have shown an orientation transition from radial to bipolar on selective interactions with targeted SK-BR3 breast cancer cells, which are over expressed by the human epidermal growth factor receptor 2-positive (HER2). The herceptin antibody-conjugated LC microdroplets are found to be highly selective in the detection of SK-BR3 cancer cells in the presence of control cells, such as KB cancer cells and fibroblast (FB), and also in the presence of 10% human blood plasma. The interaction forces of the SK-BR3 cancer cells were only effective in causing orientation transitions in 5CB molecules in the LC microdroplets, which clearly suggested that the herceptin antibody-conjugated LC microdroplets could be used as a selective biosensor for a real-time detection of SK-BR3 cancer cells in biological fluids. PMID:27533001

  13. Pressure sensor using liquid crystals

    NASA Technical Reports Server (NTRS)

    Parmar, Devendra S. (Inventor); Holmes, Harlan K. (Inventor)

    1994-01-01

    A pressure sensor includes a liquid crystal positioned between transparent, electrically conductive films (18 and 20), that are biased by a voltage (V) which induces an electric field (E) that causes the liquid crystal to assume a first state of orientation. Application of pressure (P) to a flexible, transparent film (24) causes the conductive film (20) to move closer to or farther from the conductive film (18), thereby causing a change in the electric field (E'(P)) which causes the liquid crystal to assume a second state of orientation. Polarized light (P.sub.1) is directed into the liquid crystal and transmitted or reflected to an analyzer (A or 30). Changes in the state of orientation of the liquid crystal induced by applied pressure (P) result in a different light intensity being detected at the analyzer (A or 30) as a function of the applied pressure (P). In particular embodiments, the liquid crystal is present as droplets (10) in a polymer matrix (12) or in cells (14) in a polymeric or dielectric grid (16) material in the form of a layer (13) between the electrically conductive films (18 and 20). The liquid crystal fills the open wells in the polymer matrix (12) or grid (16) only partially.

  14. Visible light absorbance enhanced by nitrogen embedded in the surface layer of Mn-doped sodium niobate crystals, detected by ultra violet - visible spectroscopy, x-ray photoelectron spectroscopy, and electric conductivity tests

    NASA Astrophysics Data System (ADS)

    Molak, A.; Pilch, M.

    2016-05-01

    Sodium niobate crystals doped with manganese ions, Na(NbMn)O3, were annealed in a nitrogen N2 flow at 600, 670, and 930 K. It was verified that simultaneous doping with Mn ions and annealing in nitrogen enhanced the photocatalytic features of sodium niobate. The transmission in the ultraviolet-visible range was measured at room temperature. The absorbance edge is in the range from 3.4 to 2.3 eV. The optical band gap Egap = 1.2-1.3 eV was evaluated using the Tauc relation. Crystals annealed at 670 K and 930 K exhibited an additional shift of the absorption edge of ˜20-40 nm toward longer wavelengths. The optical energy gap narrowed as a result of the superimposed effect of Mn and N co-doping. The x-ray photoelectron spectroscopy test showed that N ions incorporated into the surface layer. The valence band consisted of O 2p states hybridized with Nb 4d, Mn 3d, and N 2s states. The disorder detected in the surroundings of Nb and O ions decreased due to annealing. The binding energy of oxygen ions situated within the surface layer was EB ≈ 531 eV. The other contributions were assigned to molecular contamination. The contribution centered at 535.5 eV vanished after annealing at 600 K and 670 K. The contribution centered at 534 eV vanished after annealing at 930 K. The N2 annealing partly removed carbonates from the surfaces of the samples. In the 480-950 K range, the electric conductivity activation energy, Ea = 0.7-1.2 eV, was comparable with the optical Egap. The electric permittivity showed dispersion in the 0.1-800 kHz range that corresponds to the occurrence of defects.

  15. Quartz Crystal Microbalance Data

    SciTech Connect

    Baxamusa, S H

    2011-11-16

    We are using a Qpod quartz crystal microbalance (manufactured by Inficon) for use as a low-volume non-volatile residue analysis tool. Inficon has agreed to help troubleshoot some of our measurements and are requesting to view some sample data, which are attached. The basic principle of an NVR analysis is to evaporate a known volume of solvent, and weigh the remaining residue to determine the purity of the solvent. A typical NVR analysis uses 60 g of solvent and can measure residue with an accuracy of +/- 0.01 mg. The detection limit is thus (0.01 mg)/(60 g) = 0.17 ppm. We are attempting to use a quartz crystal microbalance (QCM) to make a similar measurement. The attached data show the response of the QCM as a 5-20 mg drop of solvent evaporates on its surface. The change in mass registered by the QCM after the drop evaporates is the residue that deposits on the crystal. On some measurements, the change in mass in less than zero, which is aphysical since the drop will leave behind {>=}0 mass of residue. The vendor, Inficon, has agreed to look at these data as a means to help troubleshoot the cause.

  16. Method For Screening Microcrystallizations For Crystal Formation

    DOEpatents

    Santarsiero, Bernard D. , Stevens, Raymond C. , Schultz, Peter G. , Jaklevic, Joseph M. , Yegian, Derek T. , Cornell, Earl W. , Nordmeyer, Robert A.

    2003-10-07

    A method is provided for performing array microcrystallizations to determine suitable crystallization conditions for a molecule, the method comprising: forming an array of microcrystallizations, each microcrystallization comprising a drop comprising a mother liquor solution whose composition varies within the array and a molecule to be crystallized, the drop having a volume of less than 1 microliter; storing the array of microcrystallizations under conditions suitable for molecule crystals to form in the drops in the array; and detecting molecule crystal formation in the drops by taking images of the drops.

  17. Biological Macromolecule Crystallization Database

    National Institute of Standards and Technology Data Gateway

    SRD 21 Biological Macromolecule Crystallization Database (Web, free access)   The Biological Macromolecule Crystallization Database and NASA Archive for Protein Crystal Growth Data (BMCD) contains the conditions reported for the crystallization of proteins and nucleic acids used in X-ray structure determinations and archives the results of microgravity macromolecule crystallization studies.

  18. Photonic Crystal Nanolaser Biosensors

    NASA Astrophysics Data System (ADS)

    Kita, Shota; Otsuka, Shota; Hachuda, Shoji; Endo, Tatsuro; Imai, Yasunori; Nishijima, Yoshiaki; Misawa, Hiroaki; Baba, Toshihiko

    High-performance and low-cost sensors are critical devices for high-throughput analyses of bio-samples in medical diagnoses and life sciences. In this paper, we demonstrate photonic crystal nanolaser sensor, which detects the adsorption of biomolecules from the lasing wavelength shift. It is a promising device, which balances a high sensitivity, high resolution, small size, easy integration, simple setup and low cost. In particular with a nanoslot structure, it achieves a super-sensitivity in protein sensing whose detection limit is three orders of magnitude lower than that of standard surface-plasmon-resonance sensors. Our investigations indicate that the nanoslot acts as a protein condenser powered by the optical gradient force, which arises from the strong localization of laser mode in the nanoslot.

  19. Crystallization of Stretched Polyimides: A Structure-Property Study

    NASA Technical Reports Server (NTRS)

    Hinkley, Jeffrey A.; Dezern, James F.

    2002-01-01

    A simple rotational isomeric state model was used to detect the degree to which polyimide repeat units might align to give an extended crystal. It was found experimentally that the hallmarks of stretch-crystallization were more likely to occur in materials whose molecules could readily give extended, aligned conformations. A proposed screening criterion was 84% accurate in selecting crystallizing molecules.

  20. Crystallization process

    DOEpatents

    Adler, Robert J.; Brown, William R.; Auyang, Lun; Liu, Yin-Chang; Cook, W. Jeffrey

    1986-01-01

    An improved crystallization process is disclosed for separating a crystallizable material and an excluded material which is at least partially excluded from the solid phase of the crystallizable material obtained upon freezing a liquid phase of the materials. The solid phase is more dense than the liquid phase, and it is separated therefrom by relative movement with the formation of a packed bed of solid phase. The packed bed is continuously formed adjacent its lower end and passed from the liquid phase into a countercurrent flow of backwash liquid. The packed bed extends through the level of the backwash liquid to provide a drained bed of solid phase adjacent its upper end which is melted by a condensing vapor.

  1. Ribbon crystals.

    PubMed

    Bohr, Jakob; Markvorsen, Steen

    2013-01-01

    A repetitive crystal-like pattern is spontaneously formed upon the twisting of straight ribbons. The pattern is akin to a tessellation with isosceles triangles, and it can easily be demonstrated with ribbons cut from an overhead transparency. We give a general description of developable ribbons using a ruled procedure where ribbons are uniquely described by two generating functions. This construction defines a differentiable frame, the ribbon frame, which does not have singular points, whereby we avoid the shortcomings of the Frenet-Serret frame. The observed spontaneous pattern is modeled using planar triangles and cylindrical arcs, and the ribbon structure is shown to arise from a maximization of the end-to-end length of the ribbon, i.e. from an optimal use of ribbon length. The phenomenon is discussed in the perspectives of incompatible intrinsic geometries and of the emergence of long-range order.

  2. Ribbon Crystals

    PubMed Central

    Bohr, Jakob; Markvorsen, Steen

    2013-01-01

    A repetitive crystal-like pattern is spontaneously formed upon the twisting of straight ribbons. The pattern is akin to a tessellation with isosceles triangles, and it can easily be demonstrated with ribbons cut from an overhead transparency. We give a general description of developable ribbons using a ruled procedure where ribbons are uniquely described by two generating functions. This construction defines a differentiable frame, the ribbon frame, which does not have singular points, whereby we avoid the shortcomings of the Frenet–Serret frame. The observed spontaneous pattern is modeled using planar triangles and cylindrical arcs, and the ribbon structure is shown to arise from a maximization of the end-to-end length of the ribbon, i.e. from an optimal use of ribbon length. The phenomenon is discussed in the perspectives of incompatible intrinsic geometries and of the emergence of long-range order. PMID:24098360

  3. Solution-grown crystals for neutron radiation detectors, and methods of solution growth

    SciTech Connect

    Zaitseva, Natalia; Carman, M Leslie; Payne, Steve

    2014-10-28

    An organic crystal according to one embodiment includes an organic crystal comprising diphenylacetylene and stilbene or a stilbene derivative, the crystal having physical characteristics of formation from solution, the organic crystal exhibiting a signal response signature for neutrons from a radioactive source. A system according to one embodiment includes an organic crystal comprising diphenylacetylene and stilbene or a stilbene derivative, the crystal having physical characteristics of formation from solution, the organic crystal exhibiting a signal response signature for neutrons from a radioactive source; and a photodetector for detecting the signal response of the organic crystal. Methods of making such crystals are also provided.

  4. Optical temperature sensor utilizing birefringent crystals

    NASA Technical Reports Server (NTRS)

    Quick, William H. (Inventor); James, Kenneth A. (Inventor); Strahan, Virgil H. (Inventor)

    1980-01-01

    A temperature sensor comprising an optical transducer member having an array of birefringent crystals. The length and, accordingly, the sensitivity to temperature change of successive birefringent crystals varies according to a particular relationship. The transducer is interconnected with a fiber optic transmission and detecting system. Respective optical output signals that are transmitted from the birefringent crystals via the fiber optic transmission system are detected and decoded so as to correspond to digits of a numbering system, whereby an accurate digital representation of temperature can ultimately be provided.

  5. Light scattering by randomly oriented crystals

    NASA Astrophysics Data System (ADS)

    Muinonen, Karri; Lumme, Kari; Peltoniemi, Jouni; Irvine, William M.

    The scattering phase function and the degree of linear polarization for small crystals oriented randomly in space have been computed using the geometric ray tracing theory and assuming that the crystals are homogeneous and isotropic. Calculations have been carried out for the main crystal geometries. Detection of halos from crystals other than hexagonal water ice is briefly discussed. The crystal size and shape parameters have also been averaged over some simple distributions in order to examine general light scattering properties of sharp-edged particles. A scalar physical optics correction has been developed for the geometric optics phase functions. Results can be applied to light scattering from regoliths and planetary rings, and possibly also to atmospheric halos. Retroreflecting crystals in the regolith would cause an opposition spike, a phenomenon observed for many bright satellites.

  6. Liquid Crystal Devices.

    ERIC Educational Resources Information Center

    Bradshaw, Madeline J.

    1983-01-01

    The nature of liquid crystals and several important liquid crystal devices are described. Ideas for practical experiments to illustrate the properties of liquid crystals and their operation in devices are also described. (Author/JN)

  7. Liquid Crystal Inquiries.

    ERIC Educational Resources Information Center

    Marroum, Renata-Maria

    1996-01-01

    Discusses the properties and classification of liquid crystals. Presents a simple experiment that illustrates the structure of liquid crystals and the differences between the various phases liquid crystals can assume. (JRH)

  8. Hanging drop crystal growth apparatus

    NASA Technical Reports Server (NTRS)

    Naumann, Robert J. (Inventor); Witherow, William K. (Inventor); Carter, Daniel C. (Inventor); Bugg, Charles E. (Inventor); Suddath, Fred L. (Inventor)

    1990-01-01

    This invention relates generally to control systems for controlling crystal growth, and more particularly to such a system which uses a beam of light refracted by the fluid in which crystals are growing to detect concentration of solutes in the liquid. In a hanging drop apparatus, a laser beam is directed onto drop which refracts the laser light into primary and secondary bows, respectively, which in turn fall upon linear diode detector arrays. As concentration of solutes in drop increases due to solvent removal, these bows move farther apart on the arrays, with the relative separation being detected by arrays and used by a computer to adjust solvent vapor transport from the drop. A forward scattering detector is used to detect crystal nucleation in drop, and a humidity detector is used, in one embodiment, to detect relative humidity in the enclosure wherein drop is suspended. The novelty of this invention lies in utilizing angular variance of light refracted from drop to infer, by a computer algorithm, concentration of solutes therein. Additional novelty is believed to lie in using a forward scattering detector to detect nucleating crystallites in drop.

  9. Laser-induced crystallization and crystal growth.

    PubMed

    Sugiyama, Teruki; Masuhara, Hiroshi

    2011-11-01

    Recent streams of laser studies on crystallization and crystal growth are summarized and reviewed. Femtosecond multiphoton excitation of solutions leads to their ablation at the focal point, inducing local bubble formation, shockwave propagation, and convection flow. This phenomenon, called "laser micro tsunami" makes it possible to trigger crystallization of molecules and proteins from their supersaturated solutions. Femtosecond laser ablation of a urea crystal in solution triggers the additional growth of a single daughter crystal. Intense continuous wave (CW) near infrared laser irradiation at the air/solution interface of heavy-water amino acid solutions results in trapping of the clusters and evolves to crystallization. A single crystal is always prepared in a spatially and temporally controlled manner, and the crystal polymorph of glycine depends on laser power, polarization, and solution concentration. Upon irradiation at the glass/solution interface, a millimeter-sized droplet is formed, and a single crystal is formed by shifting the irradiation position to the surface. Directional and selective crystal growth is also possible with laser trapping. Finally, characteristics of laser-induced crystallization and crystal growth are summarized.

  10. Using Inorganic Crystals To Grow Protein Crystals

    NASA Technical Reports Server (NTRS)

    Shlichta, Paul J.; Mcpherson, Alexander A.

    1989-01-01

    Solid materials serve as nucleating agents. Protein crystals induced by heterogeneous nucleation and in some cases by epitaxy to grow at lower supersaturations than needed for spontaneous nucleation. Heterogeneous nucleation makes possible to grow large, defect-free single crystals of protein more readily. Such protein crystals benefits research in biochemistry and pharmacology.

  11. EDITORIAL: Photonic Crystal Devices

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Pallab K.

    2007-05-01

    The engineering of electromagnetic modes at optical frequencies in artificial dielectric structures with periodic and random variation of the refractive index, enabling control of the radiative properties of the materials and photon localization, was first proposed independently by Yablonovitch and John in 1987. It is possible to control the flow of light in the periodic dielectric structures, known as photonic crystals (PC). As light waves scatter within the photonic crystal, destructive interference cancels out light of certain wavelengths, thereby forming a photonic bandgap, similar to the energy bandgap for electron waves in a semiconductor. Photons whose energies lie within the gap cannot propagate through the periodic structure. This property can be used to make a low-loss cavity. If a point defect, such as one or more missing periods, is introduced into the periodic structure a region is obtained within which the otherwise forbidden wavelengths can be locally trapped. This property can be used to realize photonic microcavities. Similarly, a line of defects can serve as a waveguide. While the realization of three-dimensional (3D) photonic crystals received considerable attention initially, planar two-dimensional (2D) structures are currently favoured because of their relative ease of fabrication. 2D photonic crystal structures provide most of the functionality of 3D structures. These attributes have generated worldwide research and development of sub-μm and μm size active and passive photonic devices such as single-mode and non- classical light sources, guided wave devices, resonant cavity detection, and components for optical communication. More recently, photonic crystal guided wave devices are being investigated for application in microfludic and biochemical sensing. Photonic crystal devices have been realized with bulk, quantum well and quantum dot active regions. The Cluster of articles in this issue of Journal of Physics D: Applied Physics provides a

  12. Protein crystals as scanned probes for recognition atomic force microscopy.

    PubMed

    Wickremasinghe, Nissanka S; Hafner, Jason H

    2005-12-01

    Lysozyme crystal growth has been localized at the tip of a conventional silicon nitride cantilever through seeded nucleation. After cross-linking with glutaraldehyde, lysozyme protein crystal tips image gold nanoparticles and grating standards with a resolution comparable to that of conventional tips. Force spectra between the lysozyme crystal tips and surfaces covered with antilysozyme reveal an adhesion force that drops significantly upon blocking with free lysozyme, thus confirming that lysozyme crystal tips can detect molecular recognition interactions.

  13. Na-doped optical Germanium bulk crystals

    NASA Astrophysics Data System (ADS)

    Pekar, G. S.; Singaevsky, A. F.

    2012-09-01

    In an effort to develop a material for infrared (IR) optics with improved parameters, bulk crystals of optical germanium doped with Na have been first grown and studied. Single-crystalline and coarse-crystalline Ge:Na boules of different shapes and dimensions, up to 10 kg by weight, have been grown. Sodium was incorporated into the Ge crystal during the crystal growing from the melt. Despite the fact that Na contamination in the source material was not strictly controlled, the density of Na in the grown crystals determined by the neutron activation analysis as well as by the glow discharge mass spectrometry did not exceed 1015 cm-3. Just this value may be supposed to be close to the solubility limit of Na incorporated in Ge in the course of bulk crystal growth. A first demonstration of donor behavior of Na in bulk Ge crystals is made by means of a thermoelectric type of testing. An interstitial location of Na impurity has been verified by experiments on donor drift in the dc electric field. The crystals are grown with free electron density in the range from 5ṡ1013 to 4ṡ1014 cm-3 which is optimal for using Ge crystals as an optical material for fabricating passive elements of the IR technique. A comparison between the properties of Ge:Na crystals and Ge crystals doped with Sb, a conventional impurity in optical germanium, grown under the same technological conditions and from the same intrinsic Ge as a source material, revealed a number of advantages of Ge:Na crystals; among them, the higher transparency in the IR region, smaller radiation scattering and higher regular optical transmission, lower dislocation density, more uniform distribution of electrical and optical characteristics over the crystal volume, the identity of optical parameters in the single-crystalline, and coarse-crystalline boules. No degradation of optical elements fabricated from Ge:Na crystals was detected in the course of their commercial application, starting from 1998.

  14. Sublimation Crystal Growth of Yttrium Nitride

    SciTech Connect

    Du, Li; Edgar, J H; Meisner, Roberta Ann; Bakalova-hadjikrasteva, Silvia; Kuball, M

    2010-01-01

    The sublimation recombination crystal growth of bulk yttrium nitride crystals is reported. The YN source material was prepared by reacting yttrium metal with nitrogen at 1200 C and 800 Torr total pressure. Crystals were produced by subliming this YN from the source zone, and recondensing it from the vapor as crystals at a lower temperature (by 50 C). Crystals were grown from 2000 to 2100 C and with a nitrogen pressure from 125 to 960 Torr. The highest rate was 9.64 10 5 mol/h (9.92 mg/h). The YN sublimation rate activation energy was 467.1 21.7 kJ/mol. Individual crystals up to 200 m in dimension were prepared. X-ray diffraction confirmed that the crystals were rock salt YN, with a lattice constant of 4.88 . The YN crystals were unstable in air; they spontaneously converted to yttria (Y2O3) in 2 4 h. A small fraction of cubic yttria was detected in the XRD of a sample exposed to air for a limited time, while non-cubic yttria was detected in the Raman spectra for a sample exposed to air for more than 1 h.

  15. Surface adsorption of Cs137 ions on quartz crystals

    USGS Publications Warehouse

    Antkiw, Stephen; Waesche, H.; Senftle, F.

    1954-01-01

    Adsorption tests were made on four large synthetic and three natural quartz crystals to see if surface defects might be detected by subsequent autoradiography techniques. The adsorbent used was radioactive Cs137 in a solution of Cs 137Cl. Natural quartz crystals adsorbed more cesium than the synthetic crystals. Certain surface defects were made evident by this method, but twinning features could not be detected.

  16. Drilling technique for crystals

    NASA Technical Reports Server (NTRS)

    Hunter, T.; Miyagawa, I.

    1977-01-01

    Hole-drilling technique uses special crystal driller in which drill bit rotates at fixed position at speed of 30 rpm while crystal slowly advances toward drill. Technique has been successfully applied to crystal of Rochell salt, Triglycine sulfate, and N-acetyglycine. Technique limits heat buildup and reduces strain on crystal.

  17. Liquid encapsulated crystal growth

    NASA Technical Reports Server (NTRS)

    Morrison, Andrew D. (Inventor)

    1987-01-01

    Low-defect crystals are grown in a closed ampoule under a layer of encapsulant. After crystal growth, the crystal is separated from the melt and moved into the layer of encapsulant and cooled to a first temperature at which crystal growth stops. The crystal is then moved into the inert gas ambient in the ampoule and further cooled. The crystal can be separated from the melt by decanting the melt into and adjacent reservoir or by rotating the ampoule to rotate the crystal into the encapsulant layer.

  18. Liquid encapsulated crystal growth

    NASA Technical Reports Server (NTRS)

    Morrison, Andrew D. (Inventor)

    1989-01-01

    Low-defect crystals are grown in a closed ampoule under a layer of encapsulant. After crystal growth, the crystal is separated from the melt and moved into the layer of encapsulant and cooled to a first temperature at which crystal growth stops. The crystal is then moved into the inert gas ambient in the ampoule and further cooled. The crystal can be separated from the melt by decanting the melt into an adjacent reservoir or by rotating the ampoule to rotate the crystal into the encapsulant layer.

  19. Mixed crystal organic scintillators

    DOEpatents

    Zaitseva, Natalia P; Carman, M Leslie; Glenn, Andrew M; Hamel, Sebastien; Hatarik, Robert; Payne, Stephen A; Stoeffl, Wolfgang

    2014-09-16

    A mixed organic crystal according to one embodiment includes a single mixed crystal having two compounds with different bandgap energies, the organic crystal having a physical property of exhibiting a signal response signature for neutrons from a radioactive source, wherein the signal response signature does not include a significantly-delayed luminescence characteristic of neutrons interacting with the organic crystal relative to a luminescence characteristic of gamma rays interacting with the organic crystal. According to one embodiment, an organic crystal includes bibenzyl and stilbene or a stilbene derivative, the organic crystal having a physical property of exhibiting a signal response signature for neutrons from a radioactive source.

  20. The next generation of crystal detectors

    NASA Astrophysics Data System (ADS)

    Zhu, Ren-Yuan

    2015-09-01

    Crystal detectors have been used widely in high energy and nuclear physics experiments, medical instruments and homeland security applications. Novel crystal detectors are continuously being discovered and developed in academia and in industry. In high energy and nuclear physics experiments, total absorption electromagnetic calorimeters (ECAL) made of inorganic crystals are known for their superb energy resolution and detection efficiency for photon and electron measurements. A crystal ECAL is thus the choice for those experiments where precision measurements of photons and electrons are crucial for their physics missions. For future HEP experiments at the energy and intensity frontiers, however, the crystal detectors used in the above mentioned ECALs are either not bright and fast enough, or not radiation hard enough. Crystal detectors have also been proposed to build a Homogeneous Hadron Calorimeter (HHCAL) to achieve unprecedented jet mass resolution by duel readout of both Cherenkov and scintillation light, where development of cost-effective crystal detectors is a crucial issue because of the huge crystal volume required. This paper discusses several R&D directions for the next generation of crystal detectors for future HEP experiments.

  1. Solution-grown crystals for neutron radiation detectors, and methods of solution growth

    SciTech Connect

    Zaitseva, Natalia P.; Hull, Giulia; Cherepy, Nerine J.; Payne, Stephen A.; Stoeffl, Wolfgang

    2012-06-26

    A method according to one embodiment includes growing an organic crystal from solution, the organic crystal exhibiting a signal response signature for neutrons from a radioactive source. A system according to one embodiment includes an organic crystal having physical characteristics of formation from solution, the organic crystal exhibiting a signal response signature for neutrons from a radioactive source; and a photodetector for detecting the signal response of the organic crystal. A method according to another embodiment includes growing an organic crystal from solution, the organic crystal being large enough to exhibit a detectable signal response signature for neutrons from a radioactive source. An organic crystal according to another embodiment includes an organic crystal having physical characteristics of formation from solution, the organic crystal exhibiting a signal response signature for neutrons from a radioactive source, wherein the organic crystal has a length of greater than about 1 mm in one dimension.

  2. Pressure cryocooling protein crystals

    DOEpatents

    Kim, Chae Un; Gruner, Sol M.

    2011-10-04

    Preparation of cryocooled protein crystal is provided by use of helium pressurizing and cryocooling to obtain cryocooled protein crystal allowing collection of high resolution data and by heavier noble gas (krypton or xenon) binding followed by helium pressurizing and cryocooling to obtain cryocooled protein crystal for collection of high resolution data and SAD phasing simultaneously. The helium pressurizing is carried out on crystal coated to prevent dehydration or on crystal grown in aqueous solution in a capillary.

  3. Identification of hydroxyapatite crystals in synovial fluid.

    PubMed

    Halverson, P B; McCarty, D J

    1979-04-01

    A semiquantitative technique employing (14C) ethane-1-hydroxy 1, -1-diphosphonate (EHDP) binding has been used to detect crystals, presumably hydroxyapatite, in human synovial fluid samples which were handled to prevent the formation of artifactual mineral phase. Binding material was found in 29% of non-inflammatory and in none of inflammatory joint fluids. Nuclide binding material was strongly correlated with the presence of CPPD crystals and with radiographic evidence of cartilaginous degeneration. PMID:106859

  4. CRYSTALLIZATION IN MULTICOMPONENT GLASSES

    SciTech Connect

    KRUGER AA; HRMA PR

    2009-10-08

    In glass processing situations involving glass crystallization, various crystalline forms nucleate, grow, and dissolve, typically in a nonuniform temperature field of molten glass subjected to convection. Nuclear waste glasses are remarkable examples of multicomponent vitrified mixtures involving partial crystallization. In the glass melter, crystals form and dissolve during batch-to-glass conversion, melter processing, and product cooling. Crystals often agglomerate and sink, and they may settle at the melter bottom. Within the body of cooling glass, multiple phases crystallize in a non-uniform time-dependent temperature field. Self-organizing periodic distribution (the Liesegnang effect) is common. Various crystallization phenomena that occur in glass making are reviewed.

  5. Use of dye to distinguish salt and protein crystals under microcrystallization conditions

    NASA Technical Reports Server (NTRS)

    Cosenza, Larry (Inventor); Bray, Terry L. (Inventor); DeLucas, Lawrence J. (Inventor); Gester, Thomas E. (Inventor); Hamrick, David T. (Inventor)

    2007-01-01

    An improved method of screening crystal growth conditions is provided wherein molecules are crystallized from solutions containing dyes. These dyes are selectively incorporated or associated with crystals of particular character thereby rendering crystals of particular character colored and improving detection of the dyed crystals. A preferred method involves use of dyes in protein solutions overlayed by oil. Use of oil allows the use of small volumes of solution and facilitates the screening of large numbers of crystallization conditions in arrays using automated devices that dispense appropriate solutions to generate crystallization trials, overlay crystallization trials with an oil, provide appropriate conditions conducive to crystallization and enhance detection of dyed (colored) or undyed (uncolored) crystals that result.

  6. Crystallization Pathways in Biomineralization

    NASA Astrophysics Data System (ADS)

    Weiner, Steve; Addadi, Lia

    2011-08-01

    A crystallization pathway describes the movement of ions from their source to the final product. Cells are intimately involved in biological crystallization pathways. In many pathways the cells utilize a unique strategy: They temporarily concentrate ions in intracellular membrane-bound vesicles in the form of a highly disordered solid phase. This phase is then transported to the final mineralization site, where it is destabilized and crystallizes. We present four case studies, each of which demonstrates specific aspects of biological crystallization pathways: seawater uptake by foraminifera, calcite spicule formation by sea urchin larvae, goethite formation in the teeth of limpets, and guanine crystal formation in fish skin and spider cuticles. Three representative crystallization pathways are described, and aspects of the different stages of crystallization are discussed. An in-depth understanding of these complex processes can lead to new ideas for synthetic crystallization processes of interest to materials science.

  7. Growth of dopamine crystals

    NASA Astrophysics Data System (ADS)

    Patil, Vidya; Patki, Mugdha

    2016-05-01

    Many nonlinear optical (NLO) crystals have been identified as potential candidates in optical and electro-optical devices. Use of NLO organic crystals is expected in photonic applications. Hence organic nonlinear optical materials have been intensely investigated due to their potentially high nonlinearities, and rapid response in electro-optic effect compared to inorganic NLO materials. There are many methods to grow organic crystals such as vapor growth method, melt growth method and solution growth method. Out of these methods, solution growth method is useful in providing constraint free crystal. Single crystals of Dopamine have been grown by evaporating the solvents from aqueous solution. Crystals obtained were of the size of orders of mm. The crystal structure of dopamine was determined using XRD technique. Images of crystals were obtained using FEG SEM Quanta Series under high vacuum and low KV.

  8. Apparatus for growing crystals

    NASA Technical Reports Server (NTRS)

    Jasinski, Thomas J. (Inventor); Witt, August F. (Inventor)

    1986-01-01

    An improved apparatus and method for growing crystals from a melt employing a heat pipe, consisting of one or more sections, each section serving to control temperature and thermal gradients in the crystal as it forms inside the pipe.

  9. Apparatus for mounting crystal

    DOEpatents

    Longeway, Paul A.

    1985-01-01

    A thickness monitor useful in deposition or etching reactor systems comprising a crystal-controlled oscillator in which the crystal is deposited or etched to change the frequency of the oscillator. The crystal rests within a thermally conductive metallic housing and arranged to be temperature controlled. Electrode contacts are made to the surface primarily by gravity force such that the crystal is substantially free of stress otherwise induced by high temperature.

  10. Crystallization from Gels

    NASA Astrophysics Data System (ADS)

    Narayana Kalkura, S.; Natarajan, Subramanian

    Among the various crystallization techniques, crystallization in gels has found wide applications in the fields of biomineralization and macromolecular crystallization in addition to crystallizing materials having nonlinear optical, ferroelectric, ferromagnetic, and other properties. Furthermore, by using this method it is possible to grow single crystals with very high perfection that are difficult to grow by other techniques. The gel method of crystallization provides an ideal technique to study crystal deposition diseases, which could lead to better understanding of their etiology. This chapter focuses on crystallization in gels of compounds that are responsible for crystal deposition diseases. The introduction is followed by a description of the various gels used, the mechanism of gelling, and the fascinating phenomenon of Liesegang ring formation, along with various gel growth techniques. The importance and scope of study on crystal deposition diseases and the need for crystal growth experiments using gel media are stressed. The various crystal deposition diseases, viz. (1) urolithiasis, (2) gout or arthritis, (3) cholelithiasis and atherosclerosis, and (4) pancreatitis and details regarding the constituents of the crystal deposits responsible for the pathological mineralization are discussed. Brief accounts of the theories of the formation of urinary stones and gallstones and the role of trace elements in urinary stone formation are also given. The crystallization in gels of (1) the urinary stone constituents, viz. calcium oxalate, calcium phosphates, uric acid, cystine, etc., (2) the constituents of the gallstones, viz. cholesterol, calcium carbonate, etc., (3) the major constituent of the pancreatic calculi, viz., calcium carbonate, and (4) cholic acid, a steroidal hormone are presented. The effect of various organic and inorganic ions, trace elements, and extracts from cereals, herbs, and fruits on the crystallization of major urinary stone and gallstone

  11. Protein crystal growth in low gravity

    NASA Technical Reports Server (NTRS)

    Feigelson, Robert S.

    1993-01-01

    This Final Technical Report for NASA Grant NAG8-774 covers the period from April 27, 1989 through December 31, 1992. It covers five main topics: fluid flow studies, the influence of growth conditions on the morphology of isocitrate lyase crystals, control of nucleation, the growth of lysozyme by the temperature gradient method and graphoepitaxy of protein crystals. The section on fluid flow discusses the limits of detectability in the Schlieren imaging of fluid flows around protein crystals. The isocitrate lyase study compares crystals grown terrestrially under a variety of conditions with those grown in space. The controlling factor governing the morphology of the crystals is the supersaturation. The lack of flow in the interface between the drop and the atmosphere in microgravity causes protein precipitation in the boundary layer and a lowering of the supersaturation in the drop. This lowered supersaturation leads to improved crystal morphology. Preliminary experiments with lysozyme indicated that localized temperature gradients could be used to nucleate crystals in a controlled manner. An apparatus (thermonucleator) was designed to study the controlled nucleation of protein crystals. This apparatus has been used to nucleate crystals of materials with both normal (ice-water, Rochelle salt and lysozyme) and retrograde (horse serum albumin and alpha chymotrypsinogen A) solubility. These studies have lead to the design of an new apparatus that small and more compatible with use in microgravity. Lysozyme crystals were grown by transporting nutrient from a source (lysozyme powder) to the crystal in a temperature gradient. The influence of path length and cross section on the growth rate was demonstrated. This technique can be combined with the thermonucleator to control both nucleation and growth. Graphoepitaxy utilizes a patterned substrate to orient growing crystals. In this study, silicon substrates with 10 micron grooves were used to grow crystals of catalase

  12. Induced Positron Annihiliation Investigation of Cadmium Zinc Telluride Crystal Microstructures

    SciTech Connect

    D. W. Akers

    2005-06-01

    Cadmium-Zinc-Telluride (CZT) crystals are used in semiconductor radiation detectors for the detection of x-ray and gamma radiation. However, production of detector grade crystals is difficult as small variations in compositional uniformity and primarily the zinc content can significantly affect the ability of the CZT crystal to function as a radiation detector. Currently there are no known nondestructive methods that can be used to identify detector grade crystals. The current test method is to fabricate and test the detector to determine if the crystal is sufficiently uniform and of the correct composition to be considered a detector grade crystal. Consequently, nondestructive detection methods are needed to identify detector grade crystals prior to the fabrication process. The purpose of this feasibility study was to perform a preliminary assessment of the ability of several new, nondestructive technologies based on Induced Positron Annihilation (IPA) to determine if detector grade CZT crystals can be identified. Results of measurements performed on specimens from Fisk University and EV Products, Inc. indicate that both the near surface Distributed Source Positron Annihilation (up to 3 mm penetration) and the volumetric Photon Induced Positron Annihilation methods may be suitable for determining CZT crystal quality. Further work on CZT crystals with a broader range of compositions and detector characteristics is needed to provide a well defined, calibrated, method for assessing CZT crystal quality.

  13. Protein Crystal Based Nanomaterials

    NASA Technical Reports Server (NTRS)

    Bell, Jeffrey A.; VanRoey, Patrick

    2001-01-01

    This is the final report on a NASA Grant. It concerns a description of work done, which includes: (1) Protein crystals cross-linked to form fibers; (2) Engineering of protein to favor crystallization; (3) Better knowledge-based potentials for protein-protein contacts; (4) Simulation of protein crystallization.

  14. Total immersion crystal growth

    NASA Technical Reports Server (NTRS)

    Morrison, Andrew D. (Inventor)

    1987-01-01

    Crystals of wide band gap materials are produced by positioning a holder receiving a seed crystal at the interface between a body of molten wide band gap material and an overlying layer of temperature-controlled, encapsulating liquid. The temperature of the layer decreases from the crystallization temperature of the crystal at the interface with the melt to a substantially lower temperature at which formation of crystal defects does not occur, suitably a temperature of 200 to 600 C. After initiation of crystal growth, the leading edge of the crystal is pulled through the layer until the leading edge of the crystal enters the ambient gas headspace which may also be temperature controlled. The length of the column of liquid encapsulant may exceed the length of the crystal such that the leading edge and trailing edge of the crystal are both simultaneously with the column of the crystal. The crystal can be pulled vertically by means of a pulling-rotation assembly or horizontally by means of a low-angle withdrawal mechanism.

  15. Food Crystalization and Eggs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Food Crystalization and Eggs Deana R. Jones, Ph.D. USDA Agricultural Research Service Egg Safety and Quality Research Unit Athens, Georgia, USA Deana.Jones@ars.usda.gov Sugar, salt, lactose, tartaric acid and ice are examples of constituents than can crystallize in foods. Crystallization in a foo...

  16. Triangular ice crystals

    NASA Astrophysics Data System (ADS)

    Murray, Benjamin; Salzmann, Christoph; Heymsfield, Andrew; Neely, Ryan

    2014-05-01

    We are all familiar with the hexagonal form of snow crystals and it is well established that this shape is derived from the arrangement of water molecules in the crystal lattice. However, crystals with a triangular form are often found in the Earth's atmosphere and the reason for this non-hexagonal shape has remained elusive. Recent laboratory work has shed light on why ice crystals should take on this triangular or three-fold scalene habit. Studies of the crystal structure of ice have shown that ice which initially crystallises can be made of up of hexagonal layers which are interlaced with cubic layers to produce a 'stacking disordered ice'. The degree of stacking disorder can vary from crystals which are dominantly hexagonal with a few cubic stacking faults, through to ice where the cubic and hexagonal sequences are fully randomised. The introduction of stacking disorder to ice crystals reduces the symmetry of the crystal from 6-fold (hexagonal) to 3-fold (triangular); this offers an explanation for the long standing problem of why some atmospheric ice crystals have a triangular habit. We discuss the implications of triangular crystals for halos, radiative properties, and also discuss the implications for our understanding of the nucleation and early stages of ice crystal growth for ice crystals in the atmosphere.

  17. Artistic Crystal Creations

    ERIC Educational Resources Information Center

    Lange, Catherine

    2008-01-01

    In this inquiry-based, integrative art and science activity, Grade 5-8 students use multicolored Epsom salt (magnesium sulfate) crystallizing solutions to reveal beautiful, cylindrical, 3-dimensional, needle-shaped structures. Through observations of the crystal art, students analyze factors that contribute to crystal size and formation, compare…

  18. CrystPro: Spatiotemporal Analysis of Protein Crystallization Images

    PubMed Central

    2015-01-01

    Thousands of experiments corresponding to different combinations of conditions are set up to determine the relevant conditions for successful protein crystallization. In recent years, high throughput robotic set-ups have been developed to automate the protein crystallization experiments, and imaging techniques are used to monitor the crystallization progress. Images are collected multiple times during the course of an experiment. Huge number of collected images make manual review of images tedious and discouraging. In this paper, utilizing trace fluorescence labeling, we describe an automated system called CrystPro for monitoring the protein crystal growth in crystallization trial images by analyzing the time sequence images. Given the sets of image sequences, the objective is to develop an efficient and reliable system to detect crystal growth changes such as new crystal formation and increase of crystal size. CrystPro consists of three major steps- identification of crystallization trials proper for spatio-temporal analysis, spatio-temporal analysis of identified trials, and crystal growth analysis. We evaluated the performance of our system on 3 crystallization image datasets (PCP-ILopt-11, PCP-ILopt-12, and PCP-ILopt-13) and compared our results with expert scores. Our results indicate a) 98.3% accuracy and .896 sensitivity on identification of trials for spatio-temporal analysis, b) 77.4% accuracy and .986 sensitivity of identifying crystal pairs with new crystal formation, and c) 85.8% accuracy and 0.667 sensitivity on crystal size increase detection. The results show that our method is reliable and efficient for tracking growth of crystals and determining useful image sequences for further review by the crystallographers. PMID:26640418

  19. Protein crystallization with paper

    NASA Astrophysics Data System (ADS)

    Matsuoka, Miki; Kakinouchi, Keisuke; Adachi, Hiroaki; Maruyama, Mihoko; Sugiyama, Shigeru; Sano, Satoshi; Yoshikawa, Hiroshi Y.; Takahashi, Yoshinori; Yoshimura, Masashi; Matsumura, Hiroyoshi; Murakami, Satoshi; Inoue, Tsuyoshi; Mori, Yusuke; Takano, Kazufumi

    2016-05-01

    We developed a new protein crystallization method that incorporates paper. A small piece of paper, such as facial tissue or KimWipes, was added to a drop of protein solution in the traditional sitting drop vapor diffusion technique, and protein crystals grew by incorporating paper. By this method, we achieved the growth of protein crystals with reducing osmotic shock. Because the technique is very simple and the materials are easy to obtain, this method will come into wide use for protein crystallization. In the future, it could be applied to nanoliter-scale crystallization screening on a paper sheet such as in inkjet printing.

  20. Understanding single-crystal superalloys

    NASA Technical Reports Server (NTRS)

    Dreshfield, Robert L.

    1986-01-01

    The unique properties of single crystals are considered. The anisotropic properties of single crystals, and the relation between crystal orientation and the fatigue life and slip systems of the crystals are examined. The effect of raft formation on the creep-rupture life of the crystals is studied. Proposed research on the properties of and new applications for single crystals is discussed.

  1. Protein Crystal Growth

    NASA Technical Reports Server (NTRS)

    2003-01-01

    In order to rapidly and efficiently grow crystals, tools were needed to automatically identify and analyze the growing process of protein crystals. To meet this need, Diversified Scientific, Inc. (DSI), with the support of a Small Business Innovation Research (SBIR) contract from NASA s Marshall Space Flight Center, developed CrystalScore(trademark), the first automated image acquisition, analysis, and archiving system designed specifically for the macromolecular crystal growing community. It offers automated hardware control, image and data archiving, image processing, a searchable database, and surface plotting of experimental data. CrystalScore is currently being used by numerous pharmaceutical companies and academic and nonprofit research centers. DSI, located in Birmingham, Alabama, was awarded the patent Method for acquiring, storing, and analyzing crystal images on March 4, 2003. Another DSI product made possible by Marshall SBIR funding is VaporPro(trademark), a unique, comprehensive system that allows for the automated control of vapor diffusion for crystallization experiments.

  2. Welding Molecular Crystals.

    PubMed

    Adolf, Cyril R R; Ferlay, Sylvie; Kyritsakas, Nathalie; Hosseini, Mir Wais

    2015-12-16

    Both for fundamental and applied sciences, the design of complex molecular systems in the crystalline phase with strict control of order and periodicity at both microscopic and macroscopic levels is of prime importance for development of new solid-state materials and devices. The design and fabrication of complex crystalline systems as networks of crystals displaying task-specific properties is a step toward smart materials. Here we report on isostructural and almost isometric molecular crystals of different colors, their use for fabrication of core-shell crystals, and their welding by 3D epitaxial growth into networks of crystals as single-crystalline entities. Welding of crystals by self-assembly processes into macroscopic networks of crystals is a powerful strategy for the design of hierarchically organized periodic complex architectures composed of different subdomains displaying targeted characteristics. Crystal welding may be regarded as a first step toward the design of new hierarchically organized complex crystalline systems.

  3. Photonic crystal light source

    DOEpatents

    Fleming, James G.; Lin, Shawn-Yu; Bur, James A.

    2004-07-27

    A light source is provided by a photonic crystal having an enhanced photonic density-of-states over a band of frequencies and wherein at least one of the dielectric materials of the photonic crystal has a complex dielectric constant, thereby producing enhanced light emission at the band of frequencies when the photonic crystal is heated. The dielectric material can be a metal, such as tungsten. The spectral properties of the light source can be easily tuned by modification of the photonic crystal structure and materials. The photonic crystal light source can be heated electrically or other heating means. The light source can further include additional photonic crystals that exhibit enhanced light emission at a different band of frequencies to provide for color mixing. The photonic crystal light source may have applications in optical telecommunications, information displays, energy conversion, sensors, and other optical applications.

  4. Biosensing using smectic and cholesteric liquid crystals

    NASA Astrophysics Data System (ADS)

    Popov, Piotr; Mann, Elizabeth; Jakli, Antal

    2015-03-01

    Liquid-crystal-based biosensors utilize liquid crystal alignment's high sensitivity to the presence of lipids and proteins self-assembled at the liquid crystal/aqueous solution interface. The optical response of the bulk liquid crystal to the interface offers inexpensive, easy optical detection of such biologically relevant molecules. Present technique uses nematic liquid crystal phase state that typically has a planar-to-homeotropic response only. Here we show that smectic and cholesteric phase states of liquid crystals can be used as new sensing modes that can provide additional information or improve the characteristics of a potential biosensor device. Smectic-A phase extends the detection range both toward the lower and higher concentration. Cholesteric phase (nematic with a chiral dopant) may be sensitive to the chirality of biological surface-active molecules such as phospholipids. Additionally, the ``finger-print'' texture of a cholesteric phase may show the differences between biomolecule homologues, thus providing a promising way of distinguishing between subtle differences of hydrocarbon chain or head-group size and structure.

  5. Salt-induced aggregation of lysozyme: Implications for crystal growth

    NASA Technical Reports Server (NTRS)

    Wilson, Lori J.

    1994-01-01

    Crystallization of proteins is a prerequisite for structural analysis by x-ray crystallography. While improvements in protein crystals have been obtained in microgravity onboard the U.S. Space Shuttle, attempts to improve the crystal growth process both on the ground and in space have been limited by our lack of understanding of the mechanisms involved. Almost all proteins are crystallized with the aid of a precipitating agent. Many of the common precipitating agents are inorganic salts. An understanding of the role of salts on the aggregation of protein monomers is the key to the elucidation of the mechanisms involved in protein crystallization. In order for crystallization to occur individual molecules must self-associate into aggregates. Detection and characterization of aggregates in supersaturated protein solutions is the first step in understanding salt-induced crystallization.

  6. Macromolecular Crystallization in Microgravity

    NASA Technical Reports Server (NTRS)

    Snell, Edward H.; Helliwell, John R.

    2004-01-01

    The key concepts that attracted crystal growers, macromolecular or solid state, to microgravity research is that density difference fluid flows and sedimentation of the growing crystals are greatly reduced. Thus, defects and flaws in the crystals can be reduced, even eliminated, and crystal volume can be increased. Macromolecular crystallography differs from the field of crystalline semiconductors. For the latter, crystals are harnessed for their electrical behaviors. A crystal of a biological macromolecule is used instead for diffraction experiments (X-ray or neutron) to determine the three-dimensional structure of the macromolecule. The better the internal order of the crystal of a biological macromolecule then the more molecular structure detail that can be extracted. This structural information that enables an understanding of how the molecule functions. This knowledge is changing the biological and chemical sciences with major potential in understanding disease pathologies. Macromolecular structural crystallography in general is a remarkable field where physics, biology, chemistry, and mathematics meet to enable insight to the basic fundamentals of life. In this review, we examine the use of microgravity as an environment to grow macromolecular crystals. We describe the crystallization procedures used on the ground, how the resulting crystals are studied and the knowledge obtained from those crystals. We address the features desired in an ordered crystal and the techniques used to evaluate those features in detail. We then introduce the microgravity environment, the techniques to access that environment, and the theory and evidence behind the use of microgravity for crystallization experiments. We describe how ground-based laboratory techniques have been adapted to microgravity flights and look at some of the methods used to analyze the resulting data. Several case studies illustrate the physical crystal quality improvements and the macromolecular structural

  7. Invited Review Article: Development of crystal lenses for energetic photons

    SciTech Connect

    Smither, Robert K.

    2014-08-15

    This paper follows the development of crystal diffraction lenses designed to focus energetic photons. It begins with the search for a solution to the astrophysics problem of how to detect weak astrophysics sources of gamma rays and x-rays. This led to the basic designs for a lens and to the understanding of basic limitations of lens design. The discussion of the development of crystal diffraction lenses is divided into two parts: lenses using crystals with mosaic structure, and lenses that use crystals with curved crystal planes. This second group divides into two sub-groups: (1) Curved crystals that are used to increase the acceptance angle of the diffraction of a monochromatic beam and to increase the energy bandwidth of the diffraction. (2) Curved crystals used to focus gamma ray beams. The paper describes how these two types of crystals affect the design of the corresponding crystal lenses in different fields: astrophysics, medical imaging, detection of weak, distant, gamma-ray sources, etc. The designs of crystal lenses for these applications are given in enough detail to allow the reader to design a lens for his own application.

  8. Protein crystal growth

    NASA Technical Reports Server (NTRS)

    2001-01-01

    Atomic force microscopy uses laser technology to reveal a defect, a double-screw dislocation, on the surface of this crystal of canavalin, a major source of dietary protein for humans and domestic animals. When a crystal grows, attachment kinetics and transport kinetics are competing for control of the molecules. As a molecule gets close to the crystal surface, it has to attach properly for the crystal to be usable. NASA has funded investigators to look at those attachment kinetics from a theoretical standpoint and an experimental standpoint. Dr. Alex McPherson of the University of California, Irvine, is one of those investigators. He uses X-ray diffraction and atomic force microscopy in his laboratory to answer some of the many questions about how protein crystals grow. Atomic force microscopy provides a means of looking at how individual molecules are added to the surface of growing protein crystals. This helps McPherson understand the kinetics of protein crystal growth. McPherson asks, How fast do crystals grow? What are the forces involved? Investigators funded by NASA have clearly shown that such factors as the level of supersaturation and the rate of growth all affect the habit [characteristic arrangement of facets] of the crystal and the defects that occur in the crystal.

  9. Cluster Mechanism of Homogeneous Crystallization (Computer Study)

    NASA Astrophysics Data System (ADS)

    Belashchenko, D. K.

    2008-12-01

    A molecular dynamics (MD) study of homogeneous crystallization of liquid rubidium is conducted with an inter-particle pair potential. The equilibrium crystallization temperature of the models was 313 K. Models consisted of 500, 998, and 1968 particles in a basic cube. The main investigation method was as follows: to detect (along the MD run) the atoms with Voronoi polyhedrons (VP) of 0608 type (“0608-atoms,” as in a bcc crystal) and to detect the bound groups of 0608-atoms (“0608-clusters”) that could play the role of the seeds in crystallization. Full crystallization was observed only at temperatures lower than 185 K with the creation of a predominant bcc crystal. The crystallization mechanism of Rb models differs drastically from the mechanism adopted in classical nucleation theory. It consists of the growth of the total number of 0608-atoms on cooling and the formation of 0608-clusters, analogous to the case of coagulation of solute for a supersaturated two-component solution. At the first stage of the process the clusters have a very loose structure (something like medusa or octopus with many tentacles) and include inside atoms with other Voronoi polyhedron types. The dimensions of clusters quickly increase and approach those of the basic cube. 0608-atoms play the leading role in the crystallization process and activate the transition of the atoms involved in the 0608-coordination. The fast growth of the maximum cluster begins after it attains a critical size (about 150 0608-atoms). The fluctuations of cluster sizes are very important in the creation of a 0608-cluster of critical (threshold) size. These fluctuations are especially large in the interval from 180 K to 185 K.

  10. Device and method for screening crystallization conditions in solution crystal growth

    NASA Technical Reports Server (NTRS)

    Carter, Daniel C. (Inventor)

    1995-01-01

    A device and method for detecting optimum protein crystallization conditions and for growing protein crystals in either 1g or microgravity environments comprising a housing, defining at least one pair of chambers for containing crystallization solutions is presented. The housing further defines an orifice therein for providing fluid communication between the chambers. The orifice is adapted to receive a tube which contains a gelling substance for limiting the rate of diffusive mixing of the crystallization solutions. The solutions are diffusively mixed over a period of time defined by the quantity of gelling substance sufficient to achieve equilibration and to substantially reduce density driven convection disturbances therein. The device further includes endcaps to seal the first and second chambers. One of the endcaps includes a dialysis chamber which contains protein solution in which protein crystals are grown. Once the endcaps are in place, the protein solution is exposed to the crystallization solutions wherein the solubility of the protein solution is reduced at a rate responsive to the rate of diffusive mixing of the crystallization solutions. This allows for a controlled approach to supersaturation and allows for screening of crystal growth conditions at preselected intervals.

  11. Device and Method for Screening Crystallization Conditions in Solution Crystal Growth

    NASA Technical Reports Server (NTRS)

    Carter, Daniel C. (Inventor)

    1997-01-01

    A device and method for detecting optimum protein crystallization conditions and for growing protein crystals in either 1 g or microgravity environments comprising a housing defining at least one pair of chambers for containing crystallization solutions. The housing further defines an orifice therein for providing fluid communication between the chambers. The orifice is adapted to receive a tube which contains a gelling substance for limiting the rate of diffusive mixing of the crystallization solutions. The solutions are diffusively mixed over a period of time defined by the quantity of gelling substance sufficient to achieve equilibration and to substantially reduce density driven convection disturbances therein. The device further includes endcaps to seal the first and second chambers. One of the endcaps includes a dialysis chamber which contains protein solution in which protein crystals are grown. Once the endcaps are in place. the protein solution is exposed to the crystallization solutions wherein the solubility of the protein solution is reduced at a rate responsive to the rate of diffusive mixing of the crystallization solutions. This allows for a controlled approach to supersaturation and allows for screening of crystal growth conditions at preselected intervals.

  12. Differences between individual ZSM-5 crystals in forming hollow single crystals and mesopores during base leaching.

    PubMed

    Fodor, Daniel; Krumeich, Frank; Hauert, Roland; van Bokhoven, Jeroen A

    2015-04-13

    After base treatment of ZSM-5 crystals below 100 nm in size, TEM shows hollow single crystals with a 10 nm shell. SEM images confirm that the shell is well- preserved even after prolonged treatment. Determination of the Si/Al ratios with AAS and XPS in combination with argon sputtering reveals aluminum zoning of the parent zeolite, and the total pore volume increases in the first two hours of base treatment. In corresponding TEM images, the amount of hollow crystals are observed to increase during the first two hours of base treatment, and intact crystals are visible even after 10 h of leaching; these observations indicate different dissolution rates between individual crystals. TEM of large, commercially available ZSM-5 crystals shows inhomogeneous distribution of mesopores among different crystals, which points to the existence of structural differences between individual crystals. Only tetrahedrally coordinated aluminum is detected with (27) Al MAS NMR after the base leaching of nano-sized ZSM-5.

  13. Stability of Detached Grown Germanium Single Crystals

    NASA Technical Reports Server (NTRS)

    Schweizer, M.; Volz, M. P.; Cobb, S. D.; Vujisic, L.; Szofran, F. R.; Rose, M. Franklin (Technical Monitor)

    2001-01-01

    Detachment of the melt meniscus from the crucible during semiconductor Bridgman growth experiments has been observed in recent years, especially under microgravity experiments. Under earth conditions, the hydrostatic pressure counteracts the mechanism, whereby it is more difficult to achieve detached Bridgman growth. Attempts to get stable detached growth under terrestrial conditions have been discussed in the literature and have been the subject of recent experiments in our own group. The advantage of crystals grown without wall contact is obvious: In general, they possess a higher crystal quality than conventional Bridgman grown crystals with wall contact. However, due to the interaction of different parameters such as the wetting behavior of the melt with the crucible, and the dependence of the growth angle with the shape of the melt meniscus, the mechanism leading to detachment is very complicated and not completely understood. We have grown several doped and undoped Germanium crystals with the detached Bridgman and the normal Bridgman growth technique. Pyrolytic boron nitride containers were used for all growth experiments. In the detached grown crystals the typical gap thickness between the pBN crucible and the crystal is in the range of 10 to 100 micrometers, which was determined by performing profilometer measurements. Etch pit density measurements were also performed and a comparison between detached and attached grown crystals will be given. An interesting feature was detected on the surface of a detached grown crystal. Strong surface striations with an average axial distance of 0.5 mm were observed around the whole circumference. The maximum fluctuation of the gap thickness is in the range of 5-10 micrometers. These variations of the detached gap along the crystal axis can be explained by a kind of stiction of the melt/crucible interface and thus by a variation of the meniscus shape. This phenomenon leading to the fluctuation of the gap thickness will be

  14. Stability of Detached Grown Germanium Single Crystals

    NASA Technical Reports Server (NTRS)

    Schweizer, M.; Volz, M. P.; Cobb, S. D.; Motakef, S.; Szofran, F. R.; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    Detachment of the melt meniscus from the crucible during semiconductor Bridgman growth experiments has been observed in recent years especially, under microgravity experiments. Under earth conditions, the hydrostatic pressure counteracts the mechanism, whereby it is more difficult to achieve detached Bridgman growth. Attempts to get stable detached growth under terrestrial conditions have been discussed in the literature and have been the subject of recent experiments in our own group. The advantage of crystals grown without wall contact is obvious: In general, they possess a higher crystal quality than conventional Bridgman grown crystals with wall contact. However, due to the interaction of different parameters such as the wetting behavior of the melt with the crucible, and the dependence of the growth angle with the shape of the melt meniscus, the mechanism leading to detachment is very complicated and not completely understood. We have grown several doped and undoped Germanium crystals with the detached Bridgman and the normal Bridgman growth technique. Pyrolytic boron nitride containers were used for all growth experiments. In the detached grown crystals the typical gap thickness between the pBN crucible and the crystal is in the range of 10 to 100 microns, which was determined by performing profilometer measurements. Etch pit density measurements were also performed and a comparison between detached and attached grown crystals will be given. An interesting feature was detected on the surface of a detached grown crystal. Strong surface striations with an average axial distance of 0.5mm were observed around the whole circumference. The maximum fluctuation of the gap thickness is in the range of 5-10 microns. These variations of the detached gap along the crystal axis can be explained by a kind of stiction of the melt/crucible interface and thus by a variation of the meniscus shape. This phenomenon leading to the fluctuation of the gap thickness will be

  15. Crystallization of Macromolecules

    PubMed Central

    Friedmann, David; Messick, Troy; Marmorstein, Ronen

    2014-01-01

    X-ray crystallography has evolved into a very powerful tool to determine the three-dimensional structure of macromolecules and macromolecular complexes. The major bottleneck in structure determination by X-ray crystallography is the preparation of suitable crystalline samples. This unit outlines steps for the crystallization of a macromolecule, starting with a purified, homogeneous sample. The first protocols describe preparation of the macromolecular sample (i.e., proteins, nucleic acids, and macromolecular complexes). The preparation and assessment of crystallization trials is then described, along with a protocol for confirming whether the crystals obtained are composed of macromolecule as opposed to a crystallization reagent . Next, the optimization of crystallization conditions is presented. Finally, protocols that facilitate the growth of larger crystals through seeding are described. PMID:22045560

  16. Automated macromolecular crystallization screening

    DOEpatents

    Segelke, Brent W.; Rupp, Bernhard; Krupka, Heike I.

    2005-03-01

    An automated macromolecular crystallization screening system wherein a multiplicity of reagent mixes are produced. A multiplicity of analysis plates is produced utilizing the reagent mixes combined with a sample. The analysis plates are incubated to promote growth of crystals. Images of the crystals are made. The images are analyzed with regard to suitability of the crystals for analysis by x-ray crystallography. A design of reagent mixes is produced based upon the expected suitability of the crystals for analysis by x-ray crystallography. A second multiplicity of mixes of the reagent components is produced utilizing the design and a second multiplicity of reagent mixes is used for a second round of automated macromolecular crystallization screening. In one embodiment the multiplicity of reagent mixes are produced by a random selection of reagent components.

  17. Function photonic crystals

    NASA Astrophysics Data System (ADS)

    Wu, Xiang-Yao; Zhang, Bai-Jun; Yang, Jing-Hai; Liu, Xiao-Jing; Ba, Nuo; Wu, Yi-Heng; Wang, Qing-Cai

    2011-07-01

    In this paper, we present a new kind of function photonic crystals (PCs), whose refractive index is a function of space position. Conventional PCs structure grows from two materials, A and B, with different dielectric constants εA and εB. Based on Fermat principle, we give the motion equations of light in one-dimensional, two-dimensional and three-dimensional function photonic crystals. For one-dimensional function photonic crystals, we give the dispersion relation, band gap structure and transmissivity, and compare them with conventional photonic crystals, and we find the following: (1) For the vertical and non-vertical incidence light of function photonic crystals, there are band gap structures, and for only the vertical incidence light, the conventional PCs have band gap structures. (2) By choosing various refractive index distribution functions n( z), we can obtain more wider or more narrower band gap structure than conventional photonic crystals.

  18. Single Crystal Membranes

    NASA Technical Reports Server (NTRS)

    Stormont, R. W.; Morrison, A.

    1974-01-01

    Single crystal a- and c-axis tubes and ribbons of sodium beta-alumina and sodium magnesium beta-alumina were grown from sodium oxide rich melts. Additional experiments grew ribbon crystals containing sodium magnesium beta, beta double prime, beta triple prime, and beta quadruple prime. A high pressure crystal growth chamber, sodium oxide rich melts, and iridium for all surfaces in contact with the melt were combined with the edge-defined, film-fed growth technique to grow the single crystal beta-alumina tubes and ribbons. The crystals were characterized using metallographic and X-ray diffraction techniques, and wet chemical analysis was used to determine the sodium, magnesium, and aluminum content of the grown crystals.

  19. Protein crystallization in microgravity.

    PubMed

    Aibara, S; Shibata, K; Morita, Y

    1997-12-01

    A space experiment involving protein crystallization was conducted in a microgravity environment using the space shuttle "Endeavour" of STS-47, on a 9-day mission from September 12th to 20th in 1992. The crystallization was carried out according to a batch method, and 5 proteins were selected as flight samples for crystallization. Two of these proteins: hen egg-white lysozyme and co-amino acid: pyruvate aminotransferase from Pseudomonas sp. F-126, were obtained as single crystals of good diffraction quality. Since 1992 we have carried out several space experiments for protein crystallization aboard space shuttles and the space station MIR. Our experimental results obtained mainly from hen egg-white lysozyme are described below, focusing on the effects of microgravity on protein crystal growth.

  20. Automation in biological crystallization.

    PubMed

    Stewart, Patrick Shaw; Mueller-Dieckmann, Jochen

    2014-06-01

    Crystallization remains the bottleneck in the crystallographic process leading from a gene to a three-dimensional model of the encoded protein or RNA. Automation of the individual steps of a crystallization experiment, from the preparation of crystallization cocktails for initial or optimization screens to the imaging of the experiments, has been the response to address this issue. Today, large high-throughput crystallization facilities, many of them open to the general user community, are capable of setting up thousands of crystallization trials per day. It is thus possible to test multiple constructs of each target for their ability to form crystals on a production-line basis. This has improved success rates and made crystallization much more convenient. High-throughput crystallization, however, cannot relieve users of the task of producing samples of high quality. Moreover, the time gained from eliminating manual preparations must now be invested in the careful evaluation of the increased number of experiments. The latter requires a sophisticated data and laboratory information-management system. A review of the current state of automation at the individual steps of crystallization with specific attention to the automation of optimization is given.

  1. Tunable plasmonic crystal

    DOEpatents

    Dyer, Gregory Conrad; Shaner, Eric A.; Reno, John L.; Aizin, Gregory

    2015-08-11

    A tunable plasmonic crystal comprises several periods in a two-dimensional electron or hole gas plasmonic medium that is both extremely subwavelength (.about..lamda./100) and tunable through the application of voltages to metal electrodes. Tuning of the plasmonic crystal band edges can be realized in materials such as semiconductors and graphene to actively control the plasmonic crystal dispersion in the terahertz and infrared spectral regions. The tunable plasmonic crystal provides a useful degree of freedom for applications in slow light devices, voltage-tunable waveguides, filters, ultra-sensitive direct and heterodyne THz detectors, and THz oscillators.

  2. Liquid Crystal Optofluidics

    SciTech Connect

    Vasdekis, Andreas E.; Cuennet, J. G.; Psaltis, D.

    2012-10-11

    By employing anisotropic fluids and namely liquid crystals, fluid flow becomes an additional degree of freedom in designing optofluidic devices. In this paper, we demonstrate optofluidic liquid crystal devices based on the direct flow of nematic liquid crystals in microfluidic channels. Contrary to previous reports, in the present embodiment we employ the effective phase delay acquired by light travelling through flowing liquid crystal, without analysing the polarisation state of the transmitted light. With this method, we demonstrate the variation in the diffraction pattern of an array of microfluidic channels acting as a grating. We also discuss our recent activities in integrating mechanical oscillators for on-chip peristaltic pumping.

  3. Automation in biological crystallization

    PubMed Central

    Shaw Stewart, Patrick; Mueller-Dieckmann, Jochen

    2014-01-01

    Crystallization remains the bottleneck in the crystallographic process leading from a gene to a three-dimensional model of the encoded protein or RNA. Automation of the individual steps of a crystallization experiment, from the preparation of crystallization cocktails for initial or optimization screens to the imaging of the experiments, has been the response to address this issue. Today, large high-throughput crystallization facilities, many of them open to the general user community, are capable of setting up thousands of crystallization trials per day. It is thus possible to test multiple constructs of each target for their ability to form crystals on a production-line basis. This has improved success rates and made crystallization much more convenient. High-throughput crystallization, however, cannot relieve users of the task of producing samples of high quality. Moreover, the time gained from eliminating manual preparations must now be invested in the careful evaluation of the increased number of experiments. The latter requires a sophisticated data and laboratory information-management system. A review of the current state of automation at the individual steps of crystallization with specific attention to the automation of optimization is given. PMID:24915074

  4. Phononic crystal devices

    DOEpatents

    El-Kady, Ihab F.; Olsson, Roy H.

    2012-01-10

    Phononic crystals that have the ability to modify and control the thermal black body phonon distribution and the phonon component of heat transport in a solid. In particular, the thermal conductivity and heat capacity can be modified by altering the phonon density of states in a phononic crystal. The present invention is directed to phononic crystal devices and materials such as radio frequency (RF) tags powered from ambient heat, dielectrics with extremely low thermal conductivity, thermoelectric materials with a higher ratio of electrical-to-thermal conductivity, materials with phononically engineered heat capacity, phononic crystal waveguides that enable accelerated cooling, and a variety of low temperature application devices.

  5. The improved scintillation crystal lead tungstate scintillation for PET

    NASA Astrophysics Data System (ADS)

    Wan, Youbao; WU, Rurong; Xiao, Linrong; Zhang, Jianxin; Yang, Peizhi; Yan, Hui

    2009-07-01

    As a valuable material for the detecting of γ-ray, PbWO4 and BaF2:PbWO4 crystals were grown by a novel multi-crucible temperature gradient system developed by ourselves. Utilizing a topical partial heating method, this system can form a topical partial high temperature in its hearth. Thus this system could melt raw materials in step by step as requirement. The advantage of this method is that there would be solid obstruct left on the melt in the procedure of the crystal growing up. The left obstruct could prevent the volatilization of the component in the melt. Hence it is helpful for the composition homogenization in the crystal. The system also offers a sustaining device for multi-crucibles and thus it can grow many crystals simultaneity. The optical properties and scintillation properties of the crystals were studied. The results reveal that the ions doping improves the scintillation properties of the crystal. The transmittance spectra show that the transmittance of BaF2:PbWO4 crystals are better than that of PbWO4 crystals. For the PbWO4 crystals, their absorption edge is at 325nm, and their maximum transmittance is 68%. For the BaF2:PbWO4 crystals, their absorption edge is at 325nm and their maximum transmittance is upto76%. The X-ray excited luminescence spectra shows that the luminescence peak is at 420nm for the samples of PbWO4 crystal while the peak is at 430nm for the samples of BaF2:PbWO4 crystal respectively. The luminescence intensity of the samples of BaF2:PbWO4 crystal is about two times than that of PbWO4 crystal. And their peak shape is different for the two kind of crystal. The light yield of BaF2:PbWO4 crystals is about 2.9 times than that of PbWO4 crystal Analyzing these scintillation properties, we find that the VPb 3+ and VO- defects do harm for the optical properties of the crystal. Ions doping method could reduce the defect concentration and improving its illumination performance of the crystal. Specially, the doped F- ions in O2- site can

  6. Advanced Protein Crystallization Facility (APCF)

    NASA Technical Reports Server (NTRS)

    1998-01-01

    This section of the Life and Microgravity Spacelab (LMS) publication contains articles entitled: (1) Crystallization of EGFR-EGF; (2) Crystallization of Apocrustacyanin C1; (3) Crystallization and X-ray Analysis of 5S rRNA and the 5S rRNA Domain A; (4) Growth of Lysozyme Crystals at Low Nucleation Density; (5) Comparative Analysis of Aspartyl tRNA-synthetase and Thaumatin Crystals Grown on Earth and In Microgravity; (6) Lysosome Crystal Growth in the Advanced Protein Crystallization Facility Monitored via Mach-Zehnder Interferometry and CCD Video; (7) Analysis of Thaumatin Crystals Grown on Earth and in Microgravity; (8) Crystallization of the Nucleosome Core Particle; (9) Crystallization of Photosystem I; (10) Mechanism of Membrane Protein Crystal Growth: Bacteriorhodopsin-mixed Micelle Packing at the Consolution Boundary, Stabilized in Microgravity; (11) Crystallization in a Microgravity Environment of CcdB, a Protein Involved in the Control of Cell Death; and (12) Crystallization of Sulfolobus Solfataricus

  7. Pendellösung effect in photonic crystals

    NASA Astrophysics Data System (ADS)

    Savo, S.; di Gennaro, E.; Miletto, C.; Andreone, A.; Dardano, P.; Moretti, L.; Mocella, V.

    2008-06-01

    At the exit surface of a photonic crystal, the intensity of the diffracted wave can be periodically modulated, showing a maximum in the "positive" (forward diffracted) or in the "negative" (diffracted) direction, depending on the slab thickness. This thickness dependence is a direct result of the so-called Pendellosung phenomenon, consisting of the periodic exchange inside the crystal of the energy between direct and diffracted beams. We report the experimental observation of this effect in the microwave region at about 14 GHz by irradiating 2D photonic crystal slabs of different thickness and detecting the intensity distribution of the electromagnetic field at the exit surface and inside the crystal itself.

  8. Development of a 2D Photonic Crystal Biosensing Platform

    NASA Astrophysics Data System (ADS)

    Baker, James; Sriram, Rashmi; Miller, Benjamin

    2014-03-01

    The importance of early disease diagnosis both for initiating successful clinical treatment and preventing disease transmission continues to propel the development of rapid, ultrasensitive, label-free biosensors. Sensors that implement two-dimensional photonic bandgap crystal structures, in particular, have demonstrated the potential to achieve single-pathogen detection. To reach such high sensitivity, the architecture of the photonic crystal must be designed in a way that pathogen infiltration events are evident in the optical transmission spectrum of the crystal. Computational modeling results are useful both when designing an appropriate photonic crystal geometry and when interpreting experimental observations. Results of ongoing work are presented.

  9. Density Fluctuations in Crystallizing Polymers: Fact or Fiction?

    NASA Astrophysics Data System (ADS)

    Baert, Jimmy; Van Puyvelde, Peter

    2008-07-01

    The fact that, in polymer crystallization, nucleation might be accompanied by large scale density fluctuations has been investigated for the flow-induced crystallization of isotactic poly-1-butene (PB-1). Small Angle Light Scattering (SALS) was applied to measure density and orientation fluctuations, whereas complementary results were obtained from optical microscopy. The observations seem to indicate that the detected density fluctuations result from the presence of weakly anisotropic structures, rather than being an indication of densification before the onset of crystallization. In addition, the present work provides a critical review of polymer crystallization studies using SALS.

  10. Vaterite Crystals Contain Two Interspersed Crystal Structures

    NASA Astrophysics Data System (ADS)

    Kabalah-Amitai, Lee; Mayzel, Boaz; Kauffmann, Yaron; Fitch, Andrew N.; Bloch, Leonid; Gilbert, Pupa U. P. A.; Pokroy, Boaz

    2013-04-01

    Calcite, aragonite, and vaterite are the three anhydrous polymorphs of calcium carbonate, in order of decreasing thermodynamic stability. Although vaterite is not commonly found in geological settings, it is an important precursor in several carbonate-forming systems and can be found in biological settings. Because of difficulties in obtaining large, pure, single crystals, the crystal structure of vaterite has been elusive for almost a century. Using aberration-corrected high-resolution transmission electron microscopy, we found that vaterite is actually composed of at least two different crystallographic structures that coexist within a pseudo-single crystal. The major structure exhibits hexagonal symmetry; the minor structure, existing as nanodomains within the major matrix, is still unknown.

  11. Fluorescent Applications to Crystallization

    NASA Technical Reports Server (NTRS)

    Pusey, Marc L.; Forsythe, Elizabeth; Achari, Aniruddha

    2006-01-01

    By covalently modifying a subpopulation, less than or equal to 1%, of a macromolecule with a fluorescent probe, the labeled material will add to a growing crystal as a microheterogeneous growth unit. Labeling procedures can be readily incorporated into the final stages of purification, and tests with model proteins have shown that labeling u to 5 percent of the protein molecules does not affect the X-ray data quality obtained . The presence of the trace fluorescent label gives a number of advantages. Since the label is covalently attached to the protein molecules, it "tracks" the protein s response to the crystallization conditions. The covalently attached probe will concentrate in the crystal relative to the solution, and under fluorescent illumination crystals show up as bright objects against a darker background. Non-protein structures, such as salt crystals, do not show up under fluorescent illumination. Crystals have the highest protein concentration and are readily observed against less bright precipitated phases, which under white light illumination may obscure the crystals. Automated image analysis to find crystals should be greatly facilitated, without having to first define crystallization drop boundaries as the protein or protein structures is all that shows up. Fluorescence intensity is a faster search parameter, whether visually or by automated methods, than looking for crystalline features. Preliminary tests, using model proteins, indicates that we can use high fluorescence intensity regions, in the absence of clear crystalline features or "hits", as a means for determining potential lead conditions. A working hypothesis is that more rapid amorphous precipitation kinetics may overwhelm and trap more slowly formed ordered assemblies, which subsequently show up as regions of brighter fluorescence intensity. Experiments are now being carried out to test this approach using a wider range, of proteins. The trace fluorescently labeled crystals will also

  12. Protein crystal growth

    NASA Technical Reports Server (NTRS)

    Bugg, Charles E.

    1993-01-01

    Proteins account for 50% or more of the dry weight of most living systems and play a crucial role in virtually all biological processes. Since the specific functions of essentially all biological molecules are determined by their three-dimensional structures, it is obvious that a detailed understanding of the structural makeup of a protein is essential to any systematic research pertaining to it. At the present time, protein crystallography has no substitute, it is the only technique available for elucidating the atomic arrangements within complicated biological molecules. Most macromolecules are extremely difficult to crystallize, and many otherwise exciting and promising projects have terminated at the crystal growth stage. There is a pressing need to better understand protein crystal growth, and to develop new techniques that can be used to enhance the size and quality of protein crystals. There are several aspects of microgravity that might be exploited to enhance protein crystal growth. The major factor that might be expected to alter crystal growth processes in space is the elimination of density-driven convective flow. Another factor that can be readily controlled in the absence of gravity is the sedimentation of growing crystal in a gravitational field. Another potential advantage of microgravity for protein crystal growth is the option of doing containerless crystal growth. One can readily understand why the microgravity environment established by Earth-orbiting vehicles is perceived to offer unique opportunities for the protein crystallographer. The near term objectives of the Protein Crystal Growth in a Microgravity Environment (PCG/ME) project is to continue to improve the techniques, procedures, and hardware systems used to grow protein crystals in Earth orbit.

  13. YAP multi-crystal gamma camera prototype

    SciTech Connect

    Blazek, K.; Maly, P.; Notaristefani, F. de |; Pani, R.; Pellegrini, R.; Pergola, A.; Scopinaro, F.; Soluri, A.

    1995-10-01

    The Anger camera principle has shown a practical limit of a few millimeters spatial resolution. To overcome this limit, a new gamma camera prototype has been developed, based on a position-sensitive photomultiplier tue (PSPMT) coupled with a new scintillation crystal. The Hamamatsu R2486 PSPMT is a 76-mm diameter photomultiplier tube in which the electrons produced in the conventional bi-alkali photocathode are multiplied by proximity mesh dynodes and form a charge cloud around the original coordinates of the light photon striking the photocathode. A crossed wire anode array collects the charge and detects the original position. The intrinsic spatial resolution of PSPMT is better than 0.3 mm. The scintillation crystal consists of yttrium aluminum perovskit (YAP:Ce or YAlO{sub 3}:Ce). This crystal has a light efficient of about 38% relative to NaI, no hygroscopicity and a good gamma radiation absorption. To match the characteristics of the PSPMT, a special crystal assembly was produced by the Preciosa Company, consisting of a bundle of YAP:Ce pillars where single crystals have 0.6 {times} 0.6 mm{sup 2} cross section and 3 mm to 18 mm length. Preliminary results from such gamma camera prototypes show spatial resolution values ranging between 0.7 mm and 1 mm with an intrinsic detection efficiency of 37 {divided_by} 65% for 140 keV gamma energy.

  14. Modeling the SHG activities of diverse protein crystals

    SciTech Connect

    Haupert, Levi M.; DeWalt, Emma L.; Simpson, Garth J.

    2012-11-01

    The origins of the diversity in the SHG signal from protein crystals are investigated and potential protein-crystal coverage by SHG microscopy is assessed. A symmetry-additive ab initio model for second-harmonic generation (SHG) activity of protein crystals was applied to assess the likely protein-crystal coverage of SHG microscopy. Calculations were performed for 250 proteins in nine point-group symmetries: a total of 2250 crystals. The model suggests that the crystal symmetry and the limit of detection of the instrument are expected to be the strongest predictors of coverage of the factors considered, which also included secondary-structural content and protein size. Much of the diversity in SHG activity is expected to arise primarily from the variability in the intrinsic protein response as well as the orientation within the crystal lattice. Two or more orders-of-magnitude variation in intensity are expected even within protein crystals of the same symmetry. SHG measurements of tetragonal lysozyme crystals confirmed detection, from which a protein coverage of ∼84% was estimated based on the proportion of proteins calculated to produce SHG responses greater than that of tetragonal lysozyme. Good agreement was observed between the measured and calculated ratios of the SHG intensity from lysozyme in tetragonal and monoclinic lattices.

  15. Crystal growth and crystallography

    NASA Technical Reports Server (NTRS)

    Chernov, A. A.

    1998-01-01

    Selected topics that may be of interest for both crystal-structure and crystal-growth communities are overviewed. The growth of protein crystals, along with that of some other compounds, is one of the topics, and recent insights into related phenomena are considered as examples of applications of general principles. The relationship between crystal growth shape and structure is reviewed and an attempt to introduce semiquantitative characterization of binding for proteins is made. The concept of kinks for complex structures is briefly discussed. Even at sufficiently low supersaturations, the fluctuation of steps may not be sufficient to implement the Gibbs-Thomson law if the kink density is low enough. Subsurface ordering of liquids and growth of rough interfaces from melts is discussed. Crystals growing in microgravity from solution should be more perfect if they preferentially trap stress-inducing impurities, thus creating an impurity-depleted zone around themselves. Evidently, such a zone is developed only around the crystals growing in the absence of convection. Under terrestrial conditions, the self-purified depleted zone is destroyed by convection, the crystal traps more impurity and grows stressed. The stress relief causes mosaicity. In systems containing stress-inducing but poorly trapped impurities, the crystals grown in the absence of convection should be worse than those of their terrestrial counterparts.

  16. Demonstration of Crystal Structure.

    ERIC Educational Resources Information Center

    Neville, Joseph P.

    1985-01-01

    Describes an experiment where equal parts of copper and aluminum are heated then cooled to show extremely large crystals. Suggestions are given for changing the orientation of crystals by varying cooling rates. Students are more receptive to concepts of microstructure after seeing this experiment. (DH)

  17. Walkout in Crystal City

    ERIC Educational Resources Information Center

    Barrios, Greg

    2009-01-01

    When students take action, they create change that extends far beyond the classroom. In this article, the author, who was a former teacher from Crystal City, Texas, remembers the student walkout that helped launch the Latino civil rights movement 40 years ago. The Crystal City student walkout remains a high point in the history of student activism…

  18. Crystals for stellar spectrometers

    NASA Technical Reports Server (NTRS)

    Alexandropoulos, N. G.; Cohen, G. G.

    1974-01-01

    Crystal evaluation as it applies to instrumentation employed in X-ray astronomy is reviewed, and some solutions are offered to problems that are commonly encountered. A general approach for selecting the most appropriate crystals for a given problem is also suggested. The energy dependence of the diffraction properties of (002) PET, (111) Ge, (101) ADP, (101) KAP, and (001) RAP are reported.

  19. Crystal Shape Bingo.

    ERIC Educational Resources Information Center

    Rule, Audrey C.

    This document describes a game that provides students with practice in recognizing three dimensional crystal shapes and planar geometric shapes of crystal faces. It contains information on the objective of the game, game preparation, and rules for playing. Play cards are included (four to a page). (ASK)

  20. Do protein crystals nucleate within dense liquid clusters?

    SciTech Connect

    Maes, Dominique; Vorontsova, Maria A.; Potenza, Marco A. C.; Sanvito, Tiziano; Sleutel, Mike; Giglio, Marzio; Vekilov, Peter G.

    2015-06-27

    The evolution of protein-rich clusters and nucleating crystals were characterized by dynamic light scattering (DLS), confocal depolarized dynamic light scattering (cDDLS) and depolarized oblique illumination dark-field microscopy. Newly nucleated crystals within protein-rich clusters were detected directly. These observations indicate that the protein-rich clusters are locations for crystal nucleation. Protein-dense liquid clusters are regions of high protein concentration that have been observed in solutions of several proteins. The typical cluster size varies from several tens to several hundreds of nanometres and their volume fraction remains below 10{sup −3} of the solution. According to the two-step mechanism of nucleation, the protein-rich clusters serve as locations for and precursors to the nucleation of protein crystals. While the two-step mechanism explained several unusual features of protein crystal nucleation kinetics, a direct observation of its validity for protein crystals has been lacking. Here, two independent observations of crystal nucleation with the proteins lysozyme and glucose isomerase are discussed. Firstly, the evolutions of the protein-rich clusters and nucleating crystals were characterized simultaneously by dynamic light scattering (DLS) and confocal depolarized dynamic light scattering (cDDLS), respectively. It is demonstrated that protein crystals appear following a significant delay after cluster formation. The cDDLS correlation functions follow a Gaussian decay, indicative of nondiffusive motion. A possible explanation is that the crystals are contained inside large clusters and are driven by the elasticity of the cluster surface. Secondly, depolarized oblique illumination dark-field microscopy reveals the evolution from liquid clusters without crystals to newly nucleated crystals contained in the clusters to grown crystals freely diffusing in the solution. Collectively, the observations indicate that the protein-rich clusters in

  1. Polymer Crystallization under Confinement

    NASA Astrophysics Data System (ADS)

    Floudas, George

    Recent efforts indicated that polymer crystallization under confinement can be substantially different from the bulk. This can have important technological applications for the design of polymeric nanofibers with tunable mechanical strength, processability and optical clarity. However, the question of how, why and when polymers crystallize under confinement is not fully answered. Important studies of polymer crystallization confined to droplets and within the spherical nanodomains of block copolymers emphasized the interplay between heterogeneous and homogeneous nucleation. Herein we report on recent studies1-5 of polymer crystallization under hard confinement provided by model self-ordered AAO nanopores. Important open questions here are on the type of nucleation (homogeneous vs. heterogeneous), the size of critical nucleus, the crystal orientation and the possibility to control the overall crystallinity. Providing answers to these questions is of technological relevance for the understanding of nanocomposites containing semicrystalline polymers. In collaboration with Y. Suzuki, H. Duran, M. Steinhart, H.-J. Butt.

  2. Direct preparation of spherically agglomerated salicylic acid crystals during crystallization.

    PubMed

    Kawashima, Y; Okumura, M; Takenaka, H; Kojima, A

    1984-11-01

    Needle-like salicylic acid crystals were transformed into a spherically shaped dense form during crystallization by the spherical crystallization technique. Agitation of a mixture of ethanol-water-chloroform containing salicylic acid yielded spherically agglomerated salicylic acid crystals. The crystallinity of the agglomerated salicylic acid the amount of ethanol in the solvent mixture was decreased. The wettability of the agglomerated crystals increased when the amount of ethanol in the solvent mixture was decreased, and this enhanced the dissolution rate of the crystals. The remarkable improvements in the flow and packing of the agglomerated crystals enabled the direct compression of the crystals.

  3. Biodegradation of crystal violet by Agrobacterium radiobacter.

    PubMed

    Parshetti, G K; Parshetti, S G; Telke, A A; Kalyani, D C; Doong, R A; Govindwar, S P

    2011-01-01

    Agrobacterium radiobacter MTCC 8161 completely decolorized the Crystal Violet with 8 hr (10 mg/L) at static anoxic conditions. The decreased decolorization capability by A. radiobacter was observed, when the Crystal Violet concentration was increased from 10 to 100 mg/L. Semi-synthetic medium containing 1% yeast extract and 0.1% NH4C1 has shown 100% decolorization of Crystal Violet within 5 hr. A complete degradation of Crystal Violet by A. radiobacter was observed up to 7 cycles of repeated addition (10 mg/L). When the effect of increasing inoculum concentration on decolorization of Crystal Violet (100 mg/L) was studied, maximum decolorization was observed with 15% inoculum concentration. A significant increase in the activities of laccase (184%) and aminopyrine N-demethylase (300%) in cells obtained after decolorization indicated the involvement of these enzymes in decolorization process. The intermediates formed during the degradation of Crystal Violet were analyzed by gas chromatography and mass spectroscopy (GC/MS). It was detected the presence of N,N,N',N"-tetramethylpararosaniline, [N, N-dimethylaminophenyl] [N-methylaminophenyl] benzophenone, N, N-dimethylaminobenzaldehyde, 4-methyl amino phenol and phenol. We proposed the hypothetical metabolic pathway of Crystal Violet biodegradation by A. radiobacter. Phytotoxicity and microbial toxicity study showed that Crystal Violet biodegradation metabolites were less toxic to bacteria (A. radiobacter, P. aurugenosa and A. vinelandii) contributing to soil fertility and for four kinds of plants (Sorghum bicolor Vigna radiata, Lens culinaris and Triticum aestivum) which are most sensitive, fast growing and commonly used in Indian agriculture.

  4. New organic crystals for pulse shape discrimination

    SciTech Connect

    Hull, G; Zaitseva, N; Cherepy, N; Newby, J; Stoeffl, W; Payne, S

    2008-07-16

    Efficient, readily-available, low-cost, high-energy neutron detectors can play a central role in detecting illicit nuclear weapons since neutrons are a strong indication for the presence of fissile material such as Plutonium and Highly-Enriched Uranium. The main challenge in detecting fast neutrons consists in the discrimination of the signal from the gamma radiation background. At present, the only well-investigated organic crystal scintillator for fast neutron detection, in a n/{gamma} mixed field, is stilbene, which while offering good pulse shape discrimination, is not widely used because of its limited availability and high cost. In this work we report the results of our studies made with a number of new organic crystals, which exhibit pulse shape discrimination for detection of fast neutrons. In particular 1,1,4,4-tetraphenyl-1,3-butadiene features a light yield higher than anthracene and a Figure of Merit (FOM) for the pulse shape discrimination better than stilbene. New crystals are good candidates for the low-cost solution growth method, thus representing promising organic scintillators for widespread deployment for high-energy neutron detection.

  5. Crystallization of macromolecular complexes: combinatorial complex crystallization

    NASA Astrophysics Data System (ADS)

    Stura, Enrico A.; Graille, Marc; Charbonnier, Jean-Baptiste

    2001-11-01

    The usefulness of antibody complexation, as a way of increasing the chances of crystallization needs to be re-evaluated after many antibody complexes have been crystallized and their structure determined. It is somewhat striking that among these, only a small number is a complex with a large protein antigen. The problem is that the effort of raising, cleaving and purifying an Fab is rewarded only by an extra chance of getting crystals; depending on the relative likelihood of crystallization of the complexed and uncomplexed protein. The example of the complex between HIV gp120, CD4 and an Fab fragment from a neutralizing antibody suggests that further complexation of an antigen-antibody complex with a third protein could, by increasing the number of possible combinations, improve the likelihood of crystallization. We propose the use of Ig-binding proteins as a way of extending the method from HIV gp120 to all proteins for which there are monoclonal antibodies. We discuss this technique, combinatorial complex crystallization (CCC), as part of a multi-component system for the enhancement of crystallization of macromolecular complexes. The method makes use of single Ig-binding domains from Staphylococcus aureus protein A (SpA), Peptostreptococcus magnus protein L (PpL) and the streptococcal protein G (SpG). The generality of the method depends on the ability of these domains to interact with a large repertoire of antibodies without affecting antigen binding. There is strong evidence to suggest that these Ig-binding domains bind outside the antigen-combining site of the antibody without perturbing antigen binding. It is clear from the crystal structure of the single SpG domain complexed with an Fab that the interaction involves mainly the immunoglobulin CH1 domain, a region not involved in antigen recognition. We have recently determined the structure of the complex between a human Fab and the domain D from SpA and found that steric hindrance is unlikely even for large

  6. Dispersion in photonic crystals

    NASA Astrophysics Data System (ADS)

    Witzens, Jeremy

    2005-11-01

    Investigations on the dispersive properties of photonic crystals, modified scattering in ring-resonators, monolithic integration of vertical-cavity surface-emitting lasers and advanced data processing techniques for the finite-difference time-domain method are presented. Photonic crystals are periodic mesoscopic arrays of scatterers that modify the propagation properties of electromagnetic waves in a similar way as "natural" crystals modify the properties of electrons in solid-state physics. In this thesis photonic crystals are implemented as planar photonic crystals, i.e., optically thin semiconductor films with periodic arrays of holes etched into them, with a hole-to-hole spacing of the order of the wavelength of light in the dielectric media. Photonic crystals can feature forbidden frequency ranges (the band-gaps) in which light cannot propagate. Even though most work on photonic crystals has focused on these band-gaps for application such as confinement and guiding of light, this thesis focuses on the allowed frequency regions (the photonic bands) and investigates how the propagation of light is modified by the crystal lattice. In particular the guiding of light in bulk photonic crystals in the absence of lattice defects (the self-collimation effect) and the angular steering of light in photonic crystals (the superprism effect) are investigated. The latter is used to design a planar lightwave circuit for frequency domain demultiplexion. Difficulties such as efficient insertion of light into the crystal are resolved and previously predicted limitations on the resolution are circumvented. The demultiplexer is also fabricated and characterized. Monolithic integration of vertical-cavity surface-emitting lasers by means of resonantly enhanced grating couplers is investigated. The grating coupler is designed to bend light through a ninety-degree angle and is characterized with the finite-difference time-domain method. The vertical-cavity surface-emitting lasers are

  7. Shaped Crystal Growth

    NASA Astrophysics Data System (ADS)

    Tatartchenko, Vitali A.

    Crystals of specified shape and size (shaped crystals) with controlled crystal growth (SCG) defect and impurity structure have to be grown for the successful development of modern engineering. Since the 1950s many hundreds of papers and patents concerned with shaped growth have been published. In this chapter, we do not try to enumerate the successful applications of shaped growth to different materials but rather to carry out a fundamental physical and mathematical analysis of shaping as well as the peculiarities of shaped crystal structures. Four main techniques, based on which the lateral surface can be shaped without contact with the container walls, are analyzed: the Czochralski technique (CZT), the Verneuil technique (VT), the floating zone technique (FZT), and technique of pulling from shaper (TPS). Modifications of these techniques are analyzed as well. In all these techniques the shape of the melt meniscus is controlled by surface tension forces, i.e., capillary forces, and here they are classified as capillary shaping techniques (CST). We look for conditions under which the crystal growth process in each CST is dynamically stable. Only in this case are all perturbations attenuated and a crystal of constant cross section shaping technique (CST) grown without any special regulation. The dynamic stability theory of the crystal growth process for all CST is developed on the basis of Lyapunov's dynamic stability theory. Lyapunov's equations for the crystal growth processes follow from fundamental laws. The results of the theory allow the choice of stable regimes for crystal growth by all CST as well as special designs of shapers in TPS. SCG experiments by CZT, VT, and FZT are discussed but the main consideration is given to TPS. Shapers not only allow crystal of very complicated cross section to be grown but provide a special distribution of impurities. A history of TPS is provided later in the chapter, because it can only be described after explanation of the

  8. Protein crystal growth in microgravity

    NASA Technical Reports Server (NTRS)

    Delucas, Lawrence J.; Smith, Craig D.; Smith, H. Wilson; Vijay-Kumar, Senadhi; Senadhi, Shobha E.; Ealick, Steven E.; Carter, Daniel C.; Snyder, Robert S.

    1989-01-01

    The crystals of most proteins or other biological macromolecules are poorly ordered and diffract to lower resolutions than those observed for most crystals of simple organic and inorganic compounds. Crystallization in the microgravity environment of space may improve crystal quality by eliminating convection effects near growing crystal surfaces. A series of 11 different protein crystal growth experiments was performed on U.S. Space Shuttle flight STS-26 in September 1988. The microgravity-grown crystals of gamma-interferon D1, porcine elastase, and isocitrate lyase are larger, display more uniform morphologies, and yield diffraction data to significantly higher resolutions than the best crystals of these proteins grown on earth.

  9. Quartz crystal growth

    DOEpatents

    Baughman, Richard J.

    1992-01-01

    A process for growing single crystals from an amorphous substance that can undergo phase transformation to the crystalline state in an appropriate solvent. The process is carried out in an autoclave having a lower dissolution zone and an upper crystallization zone between which a temperature differential (.DELTA.T) is maintained at all times. The apparatus loaded with the substance, solvent, and seed crystals is heated slowly maintaining a very low .DELTA.T between the warmer lower zone and cooler upper zone until the amorphous substance is transformed to the crystalline state in the lower zone. The heating rate is then increased to maintain a large .DELTA.T sufficient to increase material transport between the zones and rapid crystallization. .alpha.-Quartz single crystal can thus be made from fused quartz in caustic solvent by heating to 350.degree. C. stepwise with a .DELTA.T of 0.25.degree.-3.degree. C., increasing the .DELTA.T to about 50.degree. C. after the fused quartz has crystallized, and maintaining these conditions until crystal growth in the upper zone is completed.

  10. Biomolecular membrane protein crystallization

    NASA Astrophysics Data System (ADS)

    Reddy Bolla, Jani; Su, Chih-Chia; Yu, Edward W.

    2012-07-01

    Integral membrane proteins comprise approximately 30% of the sequenced genomes, and there is an immediate need for their high-resolution structural information. Currently, the most reliable approach to obtain these structures is X-ray crystallography. However, obtaining crystals of membrane proteins that diffract to high resolution appears to be quite challenging, and remains a major obstacle in structural determination. This brief review summarizes a variety of methodologies for use in crystallizing these membrane proteins. Hopefully, by introducing the available methods, techniques, and providing a general understanding of membrane proteins, a rational decision can be made about now to crystallize these complex materials.

  11. Hypersonic phononic crystals.

    PubMed

    Gorishnyy, T; Ullal, C K; Maldovan, M; Fytas, G; Thomas, E L

    2005-03-25

    In this Letter we propose the use of hypersonic phononic crystals to control the emission and propagation of high frequency phonons. We report the fabrication of high quality, single crystalline hypersonic crystals using interference lithography and show that direct measurement of their phononic band structure is possible with Brillouin light scattering. Numerical calculations are employed to explain the nature of the observed propagation modes. This work lays the foundation for experimental studies of hypersonic crystals and, more generally, phonon-dependent processes in nanostructures.

  12. Quantum Hall Liquid Crystals

    NASA Astrophysics Data System (ADS)

    Radzihovsky, Leo

    2003-03-01

    Liquid-crystals, defined as states of matter intermediate in their properties between fully disordered isotropic liquids and fully ordered crystals are ubiquitous in nature. Recent transport measurements on two-dimensional electron systems in moderate magnetic fields suggest the existence of a spontaneously orientationally-ordered, compressible liquid state. I will discuss electronic liquid-crystals interpretation of these experiments, focusing on a recently proposed quantum Hall nematic state that is predicted to exhibit a novel, highly anisotropic q^3 density-director mode and other interesting phenomenology.

  13. Raman scattering in crystals

    SciTech Connect

    Edwards, D.F.

    1988-09-30

    A tutorial presentation is given of Raman scattering in crystals. The physical concepts are emphasized rather than the detailed mathematical formalism. Starting with an introduction to the concepts of phonons and conservation laws, the effects of photon-phonon interactions are presented. This interaction concept is shown for a simple cubic crystal and is extended to a uniaxial crystal. The correlation table method is used for determining the number and symmetry of the Raman active modes. Finally, examples are given to illustrate the relative ease of using this group theoretical method and the predictions are compared with measured Raman spectra. 37 refs., 17 figs., 6 tabs.

  14. Analysis of Crystallization Kinetics

    NASA Technical Reports Server (NTRS)

    Kelton, Kenneth F.

    1997-01-01

    A realistic computer model for polymorphic crystallization (i.e., initial and final phases with identical compositions), which includes time-dependent nucleation and cluster-size-dependent growth rates, is developed and tested by fits to experimental data. Model calculations are used to assess the validity of two of the more common approaches for the analysis of crystallization data. The effects of particle size on transformation kinetics, important for the crystallization of many systems of limited dimension including thin films, fine powders, and nanoparticles, are examined.

  15. Molecules in crystals

    NASA Astrophysics Data System (ADS)

    Spackman, Mark A.

    2013-04-01

    Hirshfeld surface analysis has developed from the serendipitous discovery of a novel partitioning of the crystal electron density into discrete molecular fragments, to a suite of computational tools used widely for the identification, analysis and discussion of intermolecular interactions in molecular crystals. The relationship between the Hirshfeld surface and very early ideas on the internal structure of crystals is outlined, and applications of Hirshfeld surface analysis are presented for three molecules of historical importance in the development of modern x-ray crystallography: hexamethylbenzene, hexamethylenetetramine and diketopiperazine.

  16. Shaping Crystal-Crystal Phase Transitions

    NASA Astrophysics Data System (ADS)

    Du, Xiyu; van Anders, Greg; Dshemuchadse, Julia; Glotzer, Sharon

    Previous computational and experimental studies have shown self-assembled structure depends strongly on building block shape. New synthesis techniques have led to building blocks with reconfigurable shape and it has been demonstrated that building block reconfiguration can induce bulk structural reconfiguration. However, we do not understand systematically how this transition happens as a function of building block shape. Using a recently developed ``digital alchemy'' framework, we study the thermodynamics of shape-driven crystal-crystal transitions. We find examples of shape-driven bulk reconfiguration that are accompanied by first-order phase transitions, and bulk reconfiguration that occurs without any thermodynamic phase transition. Our results suggest that for well-chosen shapes and structures, there exist facile means of bulk reconfiguration, and that shape-driven bulk reconfiguration provides a viable mechanism for developing functional materials.

  17. Photonic crystal beam splitters.

    PubMed

    Chen, Chii-Chang; Chien, Hung-Da; Luan, Pi-Gang

    2004-11-20

    This work studies two-dimensional photonic crystal beam splitters with two input ports and two output ports. The beam splitter structure consists of two orthogonally crossed line defects and one point defect in square-lattice photonic crystals. The point defect is positioned at the intersection of the line defects to divide the input power into output ports. If the position and the size of the point defect are varied, the power of two output ports can be identical. The beam splitters can be used in photonic crystal Mach-Zehnder interferometers or switches. The simulation results show that a large bandwidth of the extinction ratio larger than 20 dB can be obtained while two beams are interfered in the beam splitters. This enables photonic crystal beam splitters to be used in fiber optic communication systems.

  18. Diffusion in Coulomb crystals.

    PubMed

    Hughto, J; Schneider, A S; Horowitz, C J; Berry, D K

    2011-07-01

    Diffusion in Coulomb crystals can be important for the structure of neutron star crusts. We determine diffusion constants D from molecular dynamics simulations. We find that D for Coulomb crystals with relatively soft-core 1/r interactions may be larger than D for Lennard-Jones or other solids with harder-core interactions. Diffusion, for simulations of nearly perfect body-centered-cubic lattices, involves the exchange of ions in ringlike configurations. Here ions "hop" in unison without the formation of long lived vacancies. Diffusion, for imperfect crystals, involves the motion of defects. Finally, we find that diffusion, for an amorphous system rapidly quenched from Coulomb parameter Γ=175 to Coulomb parameters up to Γ=1750, is fast enough that the system starts to crystalize during long simulation runs. These results strongly suggest that Coulomb solids in cold white dwarf stars, and the crust of neutron stars, will be crystalline and not amorphous. PMID:21867316

  19. Crystallization of Silicon Ribbons

    NASA Technical Reports Server (NTRS)

    Leipold, M. H.

    1984-01-01

    Purity constraints for reasonable solar-cell efficiency require that silicon-ribbon growth for photovoltaics occur in a regime in which constitutional supercooling or other compositional effects on the crystallization front are not important. A major consideration in the fundamentals of crystallization is the removal of the latent heat of fusion. The direction of removal, compared with the growth direction, has a major influence on the crystallization rate and the development of localized stresses. The detailed shape of the crystallization front appears to have two forms: that required for dendritic-web growth, and that occurring in all others. After the removal of the latent heat of fusion, the thermal-mechanical behavior of all ribbons appears similar within the constraints of the exothermal gradient. The technological constraints in achieving the required thermal and mechanical conditions vary widely among the growth processes.

  20. Diffusion in Coulomb crystals.

    PubMed

    Hughto, J; Schneider, A S; Horowitz, C J; Berry, D K

    2011-07-01

    Diffusion in Coulomb crystals can be important for the structure of neutron star crusts. We determine diffusion constants D from molecular dynamics simulations. We find that D for Coulomb crystals with relatively soft-core 1/r interactions may be larger than D for Lennard-Jones or other solids with harder-core interactions. Diffusion, for simulations of nearly perfect body-centered-cubic lattices, involves the exchange of ions in ringlike configurations. Here ions "hop" in unison without the formation of long lived vacancies. Diffusion, for imperfect crystals, involves the motion of defects. Finally, we find that diffusion, for an amorphous system rapidly quenched from Coulomb parameter Γ=175 to Coulomb parameters up to Γ=1750, is fast enough that the system starts to crystalize during long simulation runs. These results strongly suggest that Coulomb solids in cold white dwarf stars, and the crust of neutron stars, will be crystalline and not amorphous.

  1. Crystal-Clear Technology.

    ERIC Educational Resources Information Center

    Ondris-Crawford, Renate J.; And Others

    1993-01-01

    Provides diagrams to aid in discussing polymer dispersed liquid crystal (PDLC) technology. Equipped with a knowledge of PDLC, teachers can provide students with insight on how the gap between basic science and technology is bridged. (ZWH)

  2. Crystal Field Handbook

    NASA Astrophysics Data System (ADS)

    Newman, D. J.; Ng, Betty

    2007-09-01

    List of contributors; Preface; Introduction; 1. Crystal field splitting mechanisms D. J. Newman and Betty Ng; 2. Empirical crystal fields D. J. Newman and Betty Ng; 3. Fitting crystal field parameters D. J. Newman and Betty Ng; 4. Lanthanide and actinide optical spectra G. K. Liu; 5. Superposition model D. J. Newman and Betty Ng; 6. Effects of electron correlation on crystal field splitting M. F. Reid and D. J. Newman; 7. Ground state splittings in S-state ions D. J. Newman and Betty Ng; 8. Invariants and moments Y. Y. Yeung; 9. Semiclassical model K. S. Chan; 10. Transition intensities M. F. Reid; Appendix 1. Point symmetry D. J. Newman and Betty Ng; Appendix 2. QBASIC programs D. J. Newman and Betty Ng; Appendix 3. Accessible program packages Y. Y. Yeung, M. F. Reid and D. J. Newman; Appendix 4. Computer package CST Cz. Rudowicz; Bibliography; Index.

  3. Protein Crystal Quality Studies

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Eddie Snell, Post-Doctoral Fellow the National Research Council (NRC) uses a reciprocal space mapping diffractometer for macromolecular crystal quality studies. The diffractometer is used in mapping the structure of macromolecules such as proteins to determine their structure and thus understand how they function with other proteins in the body. This is one of several analytical tools used on proteins crystallized on Earth and in space experiments. Photo credit: NASA/Marshall Space Flight Center (MSFC)

  4. Characterizing protein crystal nucleation

    NASA Astrophysics Data System (ADS)

    Akella, Sathish V.

    We developed an experimental microfluidic based technique to measure the nucleation rates and successfully applied the technique to measure nucleation rates of lysozyme crystals. The technique involves counting the number of samples which do not have crystals as a function of time. Under the assumption that nucleation is a Poisson process, the fraction of samples with no crystals decays exponentially with the decay constant proportional to nucleation rate and volume of the sample. Since nucleation is a random and rare event, one needs to perform measurements on large number of samples to obtain good statistics. Microfluidics offers the solution of producing large number of samples at minimal material consumption. Hence, we developed a microfluidic method and measured nucleation rates of lysozyme crystals in supersaturated protein drops, each with volume of ˜ 1 nL. Classical Nucleation Theory (CNT) describes the kinetics of nucleation and predicts the functional form of nucleation rate in terms of the thermodynamic quantities involved, such as supersaturation, temperature, etc. We analyzed the measured nucleation rates in the context of CNT and obtained the activation energy and the kinetic pre-factor characterizing the nucleation process. One conclusion is that heterogeneous nucleation dominates crystallization. We report preliminary studies on selective enhancement of nucleation in one of the crystal polymorprhs of lysozyme (spherulite) using amorphous mesoporous bioactive gel-glass te{naomi06, naomi08}, CaO.P 2O5.SiO2 (known as bio-glass) with 2-10 nm pore-size diameter distribution. The pores act as heterogeneous nucleation centers and claimed to enhance the nucleation rates by molecular confinement. The measured kinetic profiles of crystal fraction of spherulites indicate that the crystallization of spherulites may be proceeding via secondary nucleation pathways.

  5. SINGLE CRYSTAL NEUTRON DIFFRACTION.

    SciTech Connect

    KOETZLE,T.F.

    2001-03-13

    Single-crystal neutron diffraction measures the elastic Bragg reflection intensities from crystals of a material, the structure of which is the subject of investigation. A single crystal is placed in a beam of neutrons produced at a nuclear reactor or at a proton accelerator-based spallation source. Single-crystal diffraction measurements are commonly made at thermal neutron beam energies, which correspond to neutron wavelengths in the neighborhood of 1 Angstrom. For high-resolution studies requiring shorter wavelengths (ca. 0.3-0.8 Angstroms), a pulsed spallation source or a high-temperature moderator (a ''hot source'') at a reactor may be used. When complex structures with large unit-cell repeats are under investigation, as is the case in structural biology, a cryogenic-temperature moderator (a ''cold source'') may be employed to obtain longer neutron wavelengths (ca. 4-10 Angstroms). A single-crystal neutron diffraction analysis will determine the crystal structure of the material, typically including its unit cell and space group, the positions of the atomic nuclei and their mean-square displacements, and relevant site occupancies. Because the neutron possesses a magnetic moment, the magnetic structure of the material can be determined as well, from the magnetic contribution to the Bragg intensities. This latter aspect falls beyond the scope of the present unit; for information on magnetic scattering of neutrons see Unit 14.3. Instruments for single-crystal diffraction (single-crystal diffractometers or SCDs) are generally available at the major neutron scattering center facilities. Beam time on many of these instruments is available through a proposal mechanism. A listing of neutron SCD instruments and their corresponding facility contacts is included in an appendix accompanying this unit.

  6. Macromolecular Crystal Quality

    NASA Technical Reports Server (NTRS)

    Snell, Edward H.; Borgstahl, Gloria E. O.; Bellamy, Henry D.; Curreri, Peter A. (Technical Monitor)

    2001-01-01

    There are many ways of judging a good crystal. Which we use depends on the qualities we seek. For gemstones size, clarity and impurity levels (color) are paramount. For the semiconductor industry purity is probably the most important quality. For the structural crystallographer the primary desideratum is the somewhat more subtle concept of internal order. In this chapter we discuss the effect of internal order (or the lack of it) on the crystal's diffraction properties.

  7. Phononic crystal diffraction gratings

    NASA Astrophysics Data System (ADS)

    Moiseyenko, Rayisa P.; Herbison, Sarah; Declercq, Nico F.; Laude, Vincent

    2012-02-01

    When a phononic crystal is interrogated by an external source of acoustic waves, there is necessarily a phenomenon of diffraction occurring on the external enclosing surfaces. Indeed, these external surfaces are periodic and the resulting acoustic diffraction grating has a periodicity that depends on the orientation of the phononic crystal. This work presents a combined experimental and theoretical study on the diffraction of bulk ultrasonic waves on the external surfaces of a 2D phononic crystal that consists of a triangular lattice of steel rods in a water matrix. The results of transmission experiments are compared with theoretical band structures obtained with the finite-element method. Angular spectrograms (showing frequency as a function of angle) determined from diffraction experiments are then compared with finite-element simulations of diffraction occurring on the surfaces of the crystal. The experimental results show that the diffraction that occurs on its external surfaces is highly frequency-dependent and has a definite relation with the Bloch modes of the phononic crystal. In particular, a strong influence of the presence of bandgaps and deaf bands on the diffraction efficiency is found. This observation opens perspectives for the design of efficient phononic crystal diffraction gratings.

  8. High-throughput crystallization screening.

    PubMed

    Skarina, Tatiana; Xu, Xiaohui; Evdokimova, Elena; Savchenko, Alexei

    2014-01-01

    Protein structure determination by X-ray crystallography is dependent on obtaining a single protein crystal suitable for diffraction data collection. Due to this requirement, protein crystallization represents a key step in protein structure determination. The conditions for protein crystallization have to be determined empirically for each protein, making this step also a bottleneck in the structure determination process. Typical protein crystallization practice involves parallel setup and monitoring of a considerable number of individual protein crystallization experiments (also called crystallization trials). In these trials the aliquots of purified protein are mixed with a range of solutions composed of a precipitating agent, buffer, and sometimes an additive that have been previously successful in prompting protein crystallization. The individual chemical conditions in which a particular protein shows signs of crystallization are used as a starting point for further crystallization experiments. The goal is optimizing the formation of individual protein crystals of sufficient size and quality to make them suitable for diffraction data collection. Thus the composition of the primary crystallization screen is critical for successful crystallization.Systematic analysis of crystallization experiments carried out on several hundred proteins as part of large-scale structural genomics efforts allowed the optimization of the protein crystallization protocol and identification of a minimal set of 96 crystallization solutions (the "TRAP" screen) that, in our experience, led to crystallization of the maximum number of proteins.

  9. Crystal growth of artificial snow

    NASA Technical Reports Server (NTRS)

    Kimura, S.; Oka, A.; Taki, M.; Kuwano, R.; Ono, H.; Nagura, R.; Narimatsu, Y.; Tanii, J.; Kamimiytat, Y.

    1984-01-01

    Snow crystals were grown onboard the space shuttle during STS-7 and STS-8 to facilitate the investigation of crystal growth under conditions of weightlessness. The experimental design and hardware are described. Space-grown snow crystals were polyhedrons looking like spheres, which were unlike snow crystals produced in experiments on Earth.

  10. Automated High Throughput Protein Crystallization Screening at Nanoliter Scale and Protein Structural Study on Lactate Dehydrogenase

    SciTech Connect

    Li, Fenglei

    2006-08-09

    The purposes of our research were: (1) To develop an economical, easy to use, automated, high throughput system for large scale protein crystallization screening. (2) To develop a new protein crystallization method with high screening efficiency, low protein consumption and complete compatibility with high throughput screening system. (3) To determine the structure of lactate dehydrogenase complexed with NADH by x-ray protein crystallography to study its inherent structural properties. Firstly, we demonstrated large scale protein crystallization screening can be performed in a high throughput manner with low cost, easy operation. The overall system integrates liquid dispensing, crystallization and detection and serves as a whole solution to protein crystallization screening. The system can dispense protein and multiple different precipitants in nanoliter scale and in parallel. A new detection scheme, native fluorescence, has been developed in this system to form a two-detector system with a visible light detector for detecting protein crystallization screening results. This detection scheme has capability of eliminating common false positives by distinguishing protein crystals from inorganic crystals in a high throughput and non-destructive manner. The entire system from liquid dispensing, crystallization to crystal detection is essentially parallel, high throughput and compatible with automation. The system was successfully demonstrated by lysozyme crystallization screening. Secondly, we developed a new crystallization method with high screening efficiency, low protein consumption and compatibility with automation and high throughput. In this crystallization method, a gas permeable membrane is employed to achieve the gentle evaporation required by protein crystallization. Protein consumption is significantly reduced to nanoliter scale for each condition and thus permits exploring more conditions in a phase diagram for given amount of protein. In addition

  11. Acoustic emission and the plasticity of crystals

    NASA Astrophysics Data System (ADS)

    Pawelek, Andrzej; Malecki, Ignacy

    This treatise is mainly devoted to a discussion of the application of acoustic emission in basic research on the plastic deformation mechanisms of metal and alloy single crystals. The acoustic emission method also provides the possibility of obtaining additional information on the nature of these mechanisms. Knowledge of the basic relationships between acoustic emission and deformation mechanisms will also facilitate the use of acoustic emission in industrial conditions (for industrial process control and for early problem detection). The material contained in this article is divided into three sections. The first section discusses the basic types of plastic deformation mechanisms in metal single crystals with simple crystal structures. The rest of this section is devoted to the problem of locating deformations, which is currently one of the most important problems in plastic deformation mechanics. The next section is based on extant literature and presents experiment data on measurements of acoustic emission during the plastic deformation of single crystals. The authors also use the results of their own research in a discussion of the most frequently encountered models and theoretical concepts concerning the causes of acoustic emission during the plastic deformation of crystals. The final section describes the basic mathematics behind these concepts and a brief attempt to assess the consistency of theoretical results and extant experimental results.

  12. Research Update: Point defects in CdTe{sub x}Se{sub 1−x} crystals grown from a Te-rich solution for applications in detecting radiation

    SciTech Connect

    Gul, R.; Roy, U. N.; Bolotnikov, A. E.; Camarda, G. S.; Cui, Y.; Hossain, A.; Yang, G.; James, R. B.; Lee, W.; Cui, Y.; Burger, A.

    2015-04-01

    We investigated cadmium telluride selenide (CdTeSe) crystals, newly grown by the Traveling Heater Method (THM), for the presence and abundance of point defects. Current Deep Level Transient spectroscopy (I-DLTS) was used to determine the energies of the traps, their capture cross sections, and densities. The bias across the detectors was varied from 1 to 30 V. Four types of point defects were identified, ranging from 10 meV to 0.35 eV. Two dominant traps at energies of 0.18 eV and 0.14 eV were studied in depth. Cd vacancies are found at lower concentrations than other point defects present in the material.

  13. Identifying, studying and making good use of macromolecular crystals

    SciTech Connect

    Calero, Guillermo; Cohen, Aina E.; Luft, Joseph R.; Newman, Janet; Snell, Edward H.

    2014-07-25

    As technology advances, the crystal volume that can be used to collect useful X-ray diffraction data decreases. The technologies available to detect and study growing crystals beyond the optical resolution limit and methods to successfully place the crystal into the X-ray beam are discussed. Structural biology has contributed tremendous knowledge to the understanding of life on the molecular scale. The Protein Data Bank, a depository of this structural knowledge, currently contains over 100 000 protein structures, with the majority stemming from X-ray crystallography. As the name might suggest, crystallography requires crystals. As detectors become more sensitive and X-ray sources more intense, the notion of a crystal is gradually changing from one large enough to embellish expensive jewellery to objects that have external dimensions of the order of the wavelength of visible light. Identifying these crystals is a prerequisite to their study. This paper discusses developments in identifying these crystals during crystallization screening and distinguishing them from other potential outcomes. The practical aspects of ensuring that once a crystal is identified it can then be positioned in the X-ray beam for data collection are also addressed.

  14. Large-amplitude motion in polymer crystals and mesophases

    SciTech Connect

    Wunderlich, B. |

    1994-12-31

    Large-amplitude motion of macromolecules involves mainly rotation about bonds (conformational motion). In the liquid phases, the large- amplitude motion is coupled with disorder and accounts for the flow and viscoelastic behavior. Perfectly ordered crystals, in contrast, permit only little large-amplitude motion. The mesophases are intermediate in order and mobility. In crystals, large-amplitude motion leads initially to gauche defects and kinks (conformational defects), and ultimately may produce conformationally disordered crystals (conis crystals). Molecular dynamics simulations of crystals with up to 30,000 atoms have been carried out and show the mechanism of defect formation, permit the study of the distribution of defects, and the visualization of hexagonal crystals. Distinction between main-chain liquid-crystalline macromolecules and condis crystals, the two mesophases of polymers, can be done on basis of analysis of phase separation (partial crystallinity), present in condis crystals and not in liquid crystals. Solid state NMR is the tool of choice for detecting mobile and rigid phases. In highly drawn fibers one can find four different states of order and mobility. Besides the (defect) crystalline phase and the isotropic amorphous phase, an intermediate oriented phase and a rigid amorphous phase exists.

  15. Fiber based photonic-crystal acoustic sensor

    NASA Astrophysics Data System (ADS)

    Kilic, Onur

    Photonic-crystal slabs are two-dimensional photonic crystals etched into a dielectric layer such as silicon. Standard micro fabrication techniques can be employed to manufacture these structures, which makes it feasible to produce them in large areas, usually an important criterion for practical applications. An appealing feature of these structures is that they can be employed as free-space optical devices such as broadband reflectors. The small thickness of the slab (usually in the vicinity of half a micron) also makes it deflectable. These combined optical and mechanical properties make it possible to employ photonic-crystal slabs in a range of practical applications, including displacement sensors, which in turn can be used for example to detect acoustic waves. An additional benefit of employing a photonic-crystal slab is that it is possible to tailor its optical and mechanical properties by adjusting the geometrical parameters of the structure such as hole radius or shape, pitch, and the slab thickness. By altering the hole radius and pitch, it is possible to make broadband reflectors or sharp transmission filters out of these structures. Adjusting the thickness also affects its deformability, making it possible to make broadband mirrors compliant to acoustic waves. Altering the hole shape, for example by introducing an asymmetry, extends the functionalities of photonic-crystal slabs even further. Breaking the symmetry by introducing asymmetric holes enables polarization-sensitive devices such as retarders, polarization beam splitters, and photonic crystals with additional non-degenerate resonances useful for increased sensitivity in sensors. All these practical advantages of photonic-crystal slabs makes them suitable as key components in micromachined sensor applications. We report one such example of an application of photonic-crystal slabs in the form of a micromachined acoustic sensor. It consists of a Fabry-Perot interferometer made of a photonic-crystal

  16. 21 CFR 884.2982 - Liquid crystal thermographic system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... breast cancer or other uses—(1) Identification. A nonelectrically powered or an AC-powered liquid crystal... for detection of breast cancer or other uses is a nonelectrically powered or an AC-powered device... screening for detection of breast cancer or other uses—(1) Identification. A nonelectrically powered or...

  17. 21 CFR 884.2982 - Liquid crystal thermographic system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... breast cancer or other uses—(1) Identification. A nonelectrically powered or an AC-powered liquid crystal... for detection of breast cancer or other uses is a nonelectrically powered or an AC-powered device... screening for detection of breast cancer or other uses—(1) Identification. A nonelectrically powered or...

  18. 21 CFR 884.2982 - Liquid crystal thermographic system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... breast cancer or other uses—(1) Identification. A nonelectrically powered or an AC-powered liquid crystal... for detection of breast cancer or other uses is a nonelectrically powered or an AC-powered device... screening for detection of breast cancer or other uses— (1) Identification. A nonelectrically powered or...

  19. 21 CFR 884.2982 - Liquid crystal thermographic system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... breast cancer or other uses—(1) Identification. A nonelectrically powered or an AC-powered liquid crystal... for detection of breast cancer or other uses is a nonelectrically powered or an AC-powered device... screening for detection of breast cancer or other uses—(1) Identification. A nonelectrically powered or...

  20. 21 CFR 884.2982 - Liquid crystal thermographic system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... breast cancer or other uses—(1) Identification. A nonelectrically powered or an AC-powered liquid crystal... for detection of breast cancer or other uses is a nonelectrically powered or an AC-powered device... screening for detection of breast cancer or other uses—(1) Identification. A nonelectrically powered or...

  1. Anti-solvent co-crystallization of carbamazepine and saccharin.

    PubMed

    Wang, In-Chun; Lee, Min-Jeong; Sim, Sang-Jun; Kim, Woo-Sik; Chun, Nan-Hee; Choi, Guang J

    2013-06-25

    The co-crystal approach has been investigated extensively over the past decade as one of the most promising methods to enhance the dissolution properties of insoluble drug substances. Co-crystal powders are typically produced by mechanical grinding (neat or wet) or a solution method (evaporation or cooling). In this study, high-purity carbamazepine-saccharin (CBZ-SAC) co-crystals were manufactured by a novel method, anti-solvent addition. Among various solvents, methanol was found to perform well with water as the anti-solvent for the co-crystallization of CBZ and SAC. When water was added to the methanol solution of CBZ and SAC at room temperature under agitation, nucleation of CBZ-SAC co-crystals occurred within 2-3 min. Co-crystallization was complete after 30 min, giving a solid yield as high as 84.5% on a CBZ basis. The effects of initial concentrations, focusing on the SAC/CBZ ratio, were examined to establish optimal conditions. The whole anti-solvent co-crystallization process was monitored at-line via ATR-FTIR analysis of regularly sampled solutions. The nucleation and crystal growth of CBZ-SAC co-crystals were detected by a significant increase in absorption in the range of 2400-2260 cm(-1), associated with the formation of hydrogen bonds between the carbonyl group in CBZ and the N-H of SAC. When CBZ hydrates were formed as impurities during anti-solvent co-crystallization, the hydrogen bonding between methanol and water was reduced greatly, primarily due to the incorporation of water molecules into the CBZ crystal lattice. In conclusion, an anti-solvent approach can be used to produce highly pure CBZ-SAC co-crystal powders with a high solid yield. PMID:23598078

  2. Anti-solvent co-crystallization of carbamazepine and saccharin.

    PubMed

    Wang, In-Chun; Lee, Min-Jeong; Sim, Sang-Jun; Kim, Woo-Sik; Chun, Nan-Hee; Choi, Guang J

    2013-06-25

    The co-crystal approach has been investigated extensively over the past decade as one of the most promising methods to enhance the dissolution properties of insoluble drug substances. Co-crystal powders are typically produced by mechanical grinding (neat or wet) or a solution method (evaporation or cooling). In this study, high-purity carbamazepine-saccharin (CBZ-SAC) co-crystals were manufactured by a novel method, anti-solvent addition. Among various solvents, methanol was found to perform well with water as the anti-solvent for the co-crystallization of CBZ and SAC. When water was added to the methanol solution of CBZ and SAC at room temperature under agitation, nucleation of CBZ-SAC co-crystals occurred within 2-3 min. Co-crystallization was complete after 30 min, giving a solid yield as high as 84.5% on a CBZ basis. The effects of initial concentrations, focusing on the SAC/CBZ ratio, were examined to establish optimal conditions. The whole anti-solvent co-crystallization process was monitored at-line via ATR-FTIR analysis of regularly sampled solutions. The nucleation and crystal growth of CBZ-SAC co-crystals were detected by a significant increase in absorption in the range of 2400-2260 cm(-1), associated with the formation of hydrogen bonds between the carbonyl group in CBZ and the N-H of SAC. When CBZ hydrates were formed as impurities during anti-solvent co-crystallization, the hydrogen bonding between methanol and water was reduced greatly, primarily due to the incorporation of water molecules into the CBZ crystal lattice. In conclusion, an anti-solvent approach can be used to produce highly pure CBZ-SAC co-crystal powders with a high solid yield.

  3. Optical monitoring of protein crystal growth

    NASA Technical Reports Server (NTRS)

    Choudry, A.

    1988-01-01

    The possibility of using various optical techniques for detecting the onset of nucleation in protein crystal growth was investigated. Direct microscopy, general metrologic techniques, light scattering, ultraviolet absorption, and interferometry are addressed along with techniques for determining pH value. The necessity for collecting basic data on the optical properties of the growth solution as a prerequisite to the evaluation of monitoring techniques is pointed out.

  4. Veselago lens by photonic hyper-crystals

    SciTech Connect

    Huang, Zun Narimanov, Evgenii E.

    2014-07-21

    Based on the recent concept of the photonic hyper-crystal—an artificial optical medium that combines the properties of hyperbolic materials and photonic crystals, we present the imaging system functioning as a Veselago lens. This planar lens shows a nearly constant negative refractive index with substantially reduced image aberrations, and can find potential applications in photolithography and hot-spots detection of silicon-based integrated circuits.

  5. The Pressure induced by salt crystallization in confinement

    PubMed Central

    Desarnaud, J.; Bonn, D.; Shahidzadeh, N.

    2016-01-01

    Salt crystallization is a major cause of weathering of rocks, artworks and monuments. Damage can only occur if crystals continue to grow in confinement, i.e. within the pore space of these materials, thus generating mechanical stress. We report the direct measurement, at the microscale, of the force exerted by growing alkali halide salt crystals while visualizing their spontaneous nucleation and growth. The experiments reveal the crucial role of the wetting films between the growing crystal and the confining walls for the development of the pressure. Our results suggest that the measured force originates from repulsion between the similarly charged confining wall and the salt crystal separated by a ~1.5 nm liquid film. Indeed, if the walls are made hydrophobic, no film is observed and no repulsive forces are detected. We also show that the magnitude of the induced pressure is system specific explaining why different salts lead to different amounts of damage to porous materials. PMID:27493020

  6. The Pressure induced by salt crystallization in confinement

    NASA Astrophysics Data System (ADS)

    Desarnaud, J.; Bonn, D.; Shahidzadeh, N.

    2016-08-01

    Salt crystallization is a major cause of weathering of rocks, artworks and monuments. Damage can only occur if crystals continue to grow in confinement, i.e. within the pore space of these materials, thus generating mechanical stress. We report the direct measurement, at the microscale, of the force exerted by growing alkali halide salt crystals while visualizing their spontaneous nucleation and growth. The experiments reveal the crucial role of the wetting films between the growing crystal and the confining walls for the development of the pressure. Our results suggest that the measured force originates from repulsion between the similarly charged confining wall and the salt crystal separated by a ~1.5 nm liquid film. Indeed, if the walls are made hydrophobic, no film is observed and no repulsive forces are detected. We also show that the magnitude of the induced pressure is system specific explaining why different salts lead to different amounts of damage to porous materials.

  7. The Pressure induced by salt crystallization in confinement.

    PubMed

    Desarnaud, J; Bonn, D; Shahidzadeh, N

    2016-01-01

    Salt crystallization is a major cause of weathering of rocks, artworks and monuments. Damage can only occur if crystals continue to grow in confinement, i.e. within the pore space of these materials, thus generating mechanical stress. We report the direct measurement, at the microscale, of the force exerted by growing alkali halide salt crystals while visualizing their spontaneous nucleation and growth. The experiments reveal the crucial role of the wetting films between the growing crystal and the confining walls for the development of the pressure. Our results suggest that the measured force originates from repulsion between the similarly charged confining wall and the salt crystal separated by a ~1.5 nm liquid film. Indeed, if the walls are made hydrophobic, no film is observed and no repulsive forces are detected. We also show that the magnitude of the induced pressure is system specific explaining why different salts lead to different amounts of damage to porous materials. PMID:27493020

  8. Introduction to protein crystallization.

    PubMed

    McPherson, Alexander; Gavira, Jose A

    2014-01-01

    Protein crystallization was discovered by chance about 150 years ago and was developed in the late 19th century as a powerful purification tool and as a demonstration of chemical purity. The crystallization of proteins, nucleic acids and large biological complexes, such as viruses, depends on the creation of a solution that is supersaturated in the macromolecule but exhibits conditions that do not significantly perturb its natural state. Supersaturation is produced through the addition of mild precipitating agents such as neutral salts or polymers, and by the manipulation of various parameters that include temperature, ionic strength and pH. Also important in the crystallization process are factors that can affect the structural state of the macromolecule, such as metal ions, inhibitors, cofactors or other conventional small molecules. A variety of approaches have been developed that combine the spectrum of factors that effect and promote crystallization, and among the most widely used are vapor diffusion, dialysis, batch and liquid-liquid diffusion. Successes in macromolecular crystallization have multiplied rapidly in recent years owing to the advent of practical, easy-to-use screening kits and the application of laboratory robotics. A brief review will be given here of the most popular methods, some guiding principles and an overview of current technologies.

  9. Introduction to protein crystallization

    PubMed Central

    McPherson, Alexander; Gavira, Jose A.

    2014-01-01

    Protein crystallization was discovered by chance about 150 years ago and was developed in the late 19th century as a powerful purification tool and as a demonstration of chemical purity. The crystallization of proteins, nucleic acids and large biological complexes, such as viruses, depends on the creation of a solution that is supersaturated in the macromolecule but exhibits conditions that do not significantly perturb its natural state. Supersaturation is produced through the addition of mild precipitating agents such as neutral salts or polymers, and by the manipulation of various parameters that include temperature, ionic strength and pH. Also important in the crystallization process are factors that can affect the structural state of the macromolecule, such as metal ions, inhibitors, cofactors or other conventional small molecules. A variety of approaches have been developed that combine the spectrum of factors that effect and promote crystallization, and among the most widely used are vapor diffusion, dialysis, batch and liquid–liquid diffusion. Successes in macromolecular crystallization have multiplied rapidly in recent years owing to the advent of practical, easy-to-use screening kits and the application of laboratory robotics. A brief review will be given here of the most popular methods, some guiding principles and an overview of current technologies. PMID:24419610

  10. Protein Crystals and their Growth

    NASA Technical Reports Server (NTRS)

    Chernov, A. A.

    2004-01-01

    Recent results on binding between protein molecules in crystal lattice, crystal-solution surface energy, elastic properties and strength and spontaneous crystal cracking are reviewed and discussed in the first half of this paper (Sea 2-4). In the second par&, some basic approaches to solubility of proteins are followed by overview on crystal nucleation and growth (Sec 5). It is argued that variability of mixing in batch crystallization may be a source for scattering of crystal number ultimately appearing in the batch. Frequency at which new molecules join crystal lattice is measured by kinetic coefficient and related to the observable crystal growth rate. Numerical criteria to discriminate diffusion and kinetic limited growth are discussed on this basis in Sec 7. In Sec 8, creation of defects is discussed with the emphasis on the role of impurities and convection on macromolecular crystal I;erfection.

  11. The growth and Raman scattering studies of TGSP crystal as the IR room temperature infrared detector

    NASA Astrophysics Data System (ADS)

    Malekfar, R.; Abbasi, B.

    2005-09-01

    The partial substitution of sulphate (SO42-) by phosphate (PO43-) in triglycine sulfate (TGS) single crystal can improve the properties of the TGS family crystal as room temperature infrared (IR) detector. Phosphoric acid (H3PO4)-doped triglycine sulfate (TGSP) single crystal has strong pyroelectric properties due to its high pyroelectric coefficient and reasonably low dielectric constant. This family of single crystals can grow easily and rapidly and are reasonably good uniform detectors in the electromagnetic region from UV to IR at room temperature and without using cryogenic cooling. TGSP single crystals were grown by saturated solution method. In order to investigate the detection sensitivity of the TGSP crystal, single crystals with different dopant concentration of phosphate (PO43-) ion were grown. A rather complete back-scattering Raman scattering spectra and hysteresis loops of the grown crystals were recorded and compared with each other. The Raman spectra and their assignments only will be reported here.

  12. Magnetically actuated liquid crystals.

    PubMed

    Wang, Mingsheng; He, Le; Zorba, Serkan; Yin, Yadong

    2014-07-01

    Ferrimagnetic inorganic nanorods have been used as building blocks to construct liquid crystals with optical properties that can be instantly and reversibly controlled by manipulating the nanorod orientation using considerably weak external magnetic fields (1 mT). Under an alternating magnetic field, they exhibit an optical switching frequency above 100 Hz, which is comparable to the performance of commercial liquid crystals based on electrical switching. By combining magnetic alignment and lithography processes, it is also possible to create patterns of different polarizations in a thin composite film and control over the transmittance of light in particular areas. Developing such magnetically responsive liquid crystals opens the door toward various applications, which may benefit from the instantaneous and contactless nature of magnetic manipulation.

  13. Photonic Crystal Microchip Laser

    PubMed Central

    Gailevicius, Darius; Koliadenko, Volodymyr; Purlys, Vytautas; Peckus, Martynas; Taranenko, Victor; Staliunas, Kestutis

    2016-01-01

    The microchip lasers, being very compact and efficient sources of coherent light, suffer from one serious drawback: low spatial quality of the beam strongly reducing the brightness of emitted radiation. Attempts to improve the beam quality, such as pump-beam guiding, external feedback, either strongly reduce the emission power, or drastically increase the size and complexity of the lasers. Here it is proposed that specially designed photonic crystal in the cavity of a microchip laser, can significantly improve the beam quality. Experiments show that a microchip laser, due to spatial filtering functionality of intracavity photonic crystal, improves the beam quality factor M2 reducing it by a factor of 2, and increase the brightness of radiation by a factor of 3. This comprises a new kind of laser, the “photonic crystal microchip laser”, a very compact and efficient light source emitting high spatial quality high brightness radiation. PMID:27683066

  14. Flexible ferroelectric organic crystals

    NASA Astrophysics Data System (ADS)

    Owczarek, Magdalena; Hujsak, Karl A.; Ferris, Daniel P.; Prokofjevs, Aleksandrs; Majerz, Irena; Szklarz, Przemysław; Zhang, Huacheng; Sarjeant, Amy A.; Stern, Charlotte L.; Jakubas, Ryszard; Hong, Seungbum; Dravid, Vinayak P.; Stoddart, J. Fraser

    2016-10-01

    Flexible organic materials possessing useful electrical properties, such as ferroelectricity, are of crucial importance in the engineering of electronic devices. Up until now, however, only ferroelectric polymers have intrinsically met this flexibility requirement, leaving small-molecule organic ferroelectrics with room for improvement. Since both flexibility and ferroelectricity are rare properties on their own, combining them in one crystalline organic material is challenging. Herein, we report that trisubstituted haloimidazoles not only display ferroelectricity and piezoelectricity--the properties that originate from their non-centrosymmetric crystal lattice--but also lend their crystalline mechanical properties to fine-tuning in a controllable manner by disrupting the weak halogen bonds between the molecules. This element of control makes it possible to deliver another unique and highly desirable property, namely crystal flexibility. Moreover, the electrical properties are maintained in the flexible crystals.

  15. Flexible ferroelectric organic crystals

    PubMed Central

    Owczarek, Magdalena; Hujsak, Karl A.; Ferris, Daniel P.; Prokofjevs, Aleksandrs; Majerz, Irena; Szklarz, Przemysław; Zhang, Huacheng; Sarjeant, Amy A.; Stern, Charlotte L.; Jakubas, Ryszard; Hong, Seungbum; Dravid, Vinayak P.; Stoddart, J. Fraser

    2016-01-01

    Flexible organic materials possessing useful electrical properties, such as ferroelectricity, are of crucial importance in the engineering of electronic devices. Up until now, however, only ferroelectric polymers have intrinsically met this flexibility requirement, leaving small-molecule organic ferroelectrics with room for improvement. Since both flexibility and ferroelectricity are rare properties on their own, combining them in one crystalline organic material is challenging. Herein, we report that trisubstituted haloimidazoles not only display ferroelectricity and piezoelectricity—the properties that originate from their non-centrosymmetric crystal lattice—but also lend their crystalline mechanical properties to fine-tuning in a controllable manner by disrupting the weak halogen bonds between the molecules. This element of control makes it possible to deliver another unique and highly desirable property, namely crystal flexibility. Moreover, the electrical properties are maintained in the flexible crystals. PMID:27734829

  16. Frequency doubling crystals

    DOEpatents

    Wang, Francis; Velsko, Stephan P.

    1989-01-01

    A systematic approach to the production of frequency conversion crystals is described in which a chiral molecule has attached to it a "harmonic generating unit" which contributes to the noncentrosymmetry of the molecule. Certain preferred embodiments of such harmonic generating units include carboxylate, guanadyly and imidazolyl units. Certain preferred crystals include L-arginine fluoride, deuterated L-arginine fluoride, L-arginine chloride monohydrate, L-arginine acetate, dithallium tartrate, ammonium N-acetyl valine, N-acetyl tyrosine and N-acetyl hydroxyproline. Chemical modifications of the chiral molecule, such as deuteration, halogenation and controlled counterion substitution are available to adapt the dispersive properties of a crystal in a particular wavelength region.

  17. Photonic Crystal Microchip Laser

    NASA Astrophysics Data System (ADS)

    Gailevicius, Darius; Koliadenko, Volodymyr; Purlys, Vytautas; Peckus, Martynas; Taranenko, Victor; Staliunas, Kestutis

    2016-09-01

    The microchip lasers, being very compact and efficient sources of coherent light, suffer from one serious drawback: low spatial quality of the beam strongly reducing the brightness of emitted radiation. Attempts to improve the beam quality, such as pump-beam guiding, external feedback, either strongly reduce the emission power, or drastically increase the size and complexity of the lasers. Here it is proposed that specially designed photonic crystal in the cavity of a microchip laser, can significantly improve the beam quality. Experiments show that a microchip laser, due to spatial filtering functionality of intracavity photonic crystal, improves the beam quality factor M2 reducing it by a factor of 2, and increase the brightness of radiation by a factor of 3. This comprises a new kind of laser, the “photonic crystal microchip laser”, a very compact and efficient light source emitting high spatial quality high brightness radiation.

  18. Crystallization of atactic polystyrene

    NASA Astrophysics Data System (ADS)

    Chai, Yu; Forrest, James

    Atactic polystyrene is often used as an archetypical example of a material that has no crystalline ground state due to the lack of order in the arrangement of phenyl groups along the backbone. However, even in polymers with perfect Bernoullian (random) statistics, there is a probability that a given molecule will have larger blocks of a given stereoregularity. These blocks, in turn, could allow the formation of nanocrysalline domains. As a model system to investigate whether such blocks could lead to nanoscale crystallinity, we consider PS with Mw less than 1000 where there is a reasonable probability of a molecule having all meso or racemo diads . For the case of Mw 600, there are clear indications of crystal growth with two characteristic temperatures below which two different crystal species can nucleate and grow. Similar crystal growth and melting behavior is observed for Mw 1000.

  19. Photonic crystal self-collimation sensor.

    PubMed

    Wang, Yufei; Wang, Hailing; Xue, Qikun; Zheng, Wanhua

    2012-05-21

    A novel refractive index sensor based on the two dimensional photonic crystal folded Michelson interferometer employing the self-collimation effect is proposed and its performances are theoretically investigated. Two sensing areas are included in the sensor. Simulation results indicate the branch area is suitable for the small index variety range and fine detection, whereas the reflector area prone to the large index change range and coarse detection. Because of no defect waveguides and no crosstalk of signal, the sensor is desirable to perform monolithic integrated, low-cost, label-free real-time parallel sensing. In addition, a flexible design of self-collimation sensors array is demonstrated. PMID:22714197

  20. CLearance of calcium pyrophosphate dihydrate crystals in vivo. II. Studies using triclinic crystals doubly labeled with 45Ca and 85Sr.

    PubMed

    McCarty, D J; Palmer, D W; James, C

    1979-10-01

    The clearance rate of isotopically labeled synthetic triclinic calcium pyrophosphate dihydrate (CPPD) crystals injection into rabbit joints was estimated by serial counting. Kinetic analysis using a four compartment model showed that half of the injected dose was cleared from 4 rabbit knee joints in 19.1 +/- 0.42 (SEM) days. Profound hypomagnesemia, produced in 2 rabbits with a low magnesium diet, did not affect the rate of crystal clearance detectably. Lavage of joints with solutions known to promote CPPD crystal solubility failed to remove detectable radioactivity. The previous finding of CPPD crystals in synovial phagocytes by electron microscopy, together with the finding of nuclide activity in the synovium and the failure to remove such activity by joint lavage, suggests that endocytosis by synovial cells is an important, effective mechanism controlling the synovial fluid concentration of crystals in patients with CPPD crystal deposition disease. PMID:226098

  1. Cirrus Crystal Terminal Velocities.

    NASA Astrophysics Data System (ADS)

    Heymsfield, Andrew J.; Iaquinta, Jean

    2000-04-01

    Cirrus crystal terminal velocities are of primary importance in determining the rate of transport of condensate from upper- to middle-tropospheric levels and profoundly influence the earth's radiation balance through their effect on the rate of buildup or decay of cirrus clouds. In this study, laboratory and field-based cirrus crystal drag coefficient data, as well as analytical descriptions of cirrus crystal shapes, are used to derive more physically based expressions for the velocities of cirrus crystals than have been available in the past.Polycrystals-often bullet rosettes-are shown to be the dominant crystal types in synoptically generated cirrus, with columns present in varying but relatively large percentages, depending on the cloud. The two critical parameters needed to calculate terminal velocity are the drag coefficient and the ratio of mass to cross-sectional area normal to their fall direction. Using measurements and calculations, it is shown that drag coefficients from theory and laboratory studies are applicable to crystals of the types found in cirrus. The ratio of the mass to area, which is shown to be relatively independent of the number of bullets in the rosette, is derived from an analytic model that represents bullet rosettes containing one to eight bullets in 19 primary geometric configurations. The ratio is also derived for columns. Using this information, a general set of equations is developed to calculate the terminal velocities and masses in terms of the aspect ratio (width divided by length), ice density, and rosette maximum dimension. Simple expressions for terminal velocity and mass as a function of bullet rosette maximum dimension are developed by incorporating new information on bullet aspect ratios.The general terminal velocity and mass relations are then applied to a case from the First International Satellite Cloud Climatology Project (ISCCP) Research Experiment (FIRE) 2, when size spectra from a balloon-borne ice crystal

  2. FRACTIONAL CRYSTALLIZATION FEED ENVELOPE

    SciTech Connect

    HERTING DL

    2008-03-19

    Laboratory work was completed on a set of evaporation tests designed to establish a feed envelope for the fractional crystallization process. The feed envelope defines chemical concentration limits within which the process can be operated successfully. All 38 runs in the half-factorial design matrix were completed successfully, based on the qualitative definition of success. There is no feed composition likely to be derived from saltcake dissolution that would cause the fractional crystallization process to not meet acceptable performance requirements. However, some compositions clearly would provide more successful operation than other compositions.

  3. Protein Crystal Malic Enzyme

    NASA Technical Reports Server (NTRS)

    1992-01-01

    Malic Enzyme is a target protein for drug design because it is a key protein in the life cycle of intestinal parasites. After 2 years of effort on Earth, investigators were unable to produce any crystals that were of high enough quality and for this reason the structure of this important protein could not be determined. Crystals obtained from one STS-50 were of superior quality allowing the structure to be determined. This is just one example why access to space is so vital for these studies. Principal Investigator is Larry DeLucas.

  4. Protein Crystal Quality Studies

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Eddie Snell (standing), Post-Doctoral Fellow the National Research Council (NRC),and Marc Pusey of Marshall Space Flight Center (MSFC) use a reciprocal space mapping diffractometer for marcromolecular crystal quality studies. The diffractometer is used in mapping the structure of marcromolecules such as proteins to determine their structure and thus understand how they function with other proteins in the body. This is one of several analytical tools used on proteins crystalized on Earth and in space experiments. Photo credit: NASA/Marshall Space Flight Center (MSFC)

  5. Semiconductor nanorod liquid crystals

    SciTech Connect

    Li, Liang-shi; Walda, Joost; Manna, Liberato; Alivisatos, A. Paul

    2002-01-28

    Rodlike molecules form liquid crystalline phases with orientational order and positional disorder. The great majority of materials in which liquid crystalline phases have been observed are comprised of organic molecules or polymers, even though there has been continuing and growing interest in inorganic liquid crystals. Recent advances in the control of the sizes and shapes of inorganic nanocrystals allow for the formation of a broad class of new inorganic liquid crystals. Here we show the formation of liquid crystalline phases of CdSe semiconductor nanorods. These new liquid crystalline phases may have great importance for both application and fundamental study.

  6. Crystallization seeds favour crystallization only during initial growth

    PubMed Central

    Allahyarov, E.; Sandomirski, K.; Egelhaaf, S.U.; Löwen, H.

    2015-01-01

    Crystallization represents the prime example of a disorder–order transition. In realistic situations, however, container walls and impurities are frequently present and hence crystallization is heterogeneously seeded. Rarely the seeds are perfectly compatible with the thermodynamically favoured crystal structure and thus induce elastic distortions, which impede further crystal growth. Here we use a colloidal model system, which not only allows us to quantitatively control the induced distortions but also to visualize and follow heterogeneous crystallization with single-particle resolution. We determine the sequence of intermediate structures by confocal microscopy and computer simulations, and develop a theoretical model that describes our findings. The crystallite first grows on the seed but then, on reaching a critical size, detaches from the seed. The detached and relaxed crystallite continues to grow, except close to the seed, which now prevents crystallization. Hence, crystallization seeds facilitate crystallization only during initial growth and then act as impurities. PMID:25975451

  7. Dynamically controlled crystallization method and apparatus and crystals obtained thereby

    NASA Technical Reports Server (NTRS)

    Arnowitz, Leonard (Inventor); Steinberg, Emanuel (Inventor)

    1999-01-01

    A method and apparatus for dynamically controlling the crystallization of proteins including a crystallization chamber or chambers for holding a protein in a salt solution, one or more salt solution chambers, two communication passages respectively coupling the crystallization chamber with each of the salt solution chambers, and transfer mechanisms configured to respectively transfer salt solution between each of the salt solution chambers and the crystallization chamber. The transfer mechanisms are interlocked to maintain the volume of salt solution in the crystallization chamber substantially constant. Salt solution of different concentrations is transferred into and out of the crystallization chamber to adjust the salt concentration in the crystallization chamber to achieve precise control of the crystallization process.

  8. Experimental demonstration of self-collimation inside a three-dimensional photonic crystal.

    PubMed

    Lu, Zhaolin; Shi, Shouyuan; Murakowski, Janusz A; Schneider, Garrett J; Schuetz, Christopher A; Prather, Dennis W

    2006-05-01

    We present our experimental demonstration of self-collimation inside a three-dimensional (3D) simple cubic photonic crystal at microwave frequencies. The photonic crystal was designed with unique dispersion property and fabricated by a high precision computer-controlled machine. The self-collimation modes were excited by a grounded waveguide feeding and detected by a scanning monopole. Self-collimation of electromagnetic waves in the 3D photonic crystal was demonstrated by measuring the 3D field distribution, which was shown as a narrow collimated beam inside the 3D photonic crystal but a diverged beam in the absence of the photonic crystal. PMID:16712297

  9. Crystalline structures, thermal properties and crystallizing mechanism of polyamide 6 nanotubes in confined space

    NASA Astrophysics Data System (ADS)

    Li, Xiaoru; Peng, Zhi; Yang, Chao; Han, Ping; Song, Guojun; Cong, Longliang

    2016-09-01

    The polyamide 6 (PA6) nanotubes were prepared by infiltrating the anodic aluminum oxide templates with polymer solution. Crystalline regions in the nanotube walls were detected by high-resolution transmission electron microscopy (HRTEM). X-ray diffraction (XRD), Fast Fourier Transform (FFT) and differential scanning calorimetry (DSC) techniques were employed to investigate crystallization, crystal faces and thermodynamics. It was found that the crystals were transformed from α-form in bulk to γ-form in nanotubes. It was made a detailed analysis in this article. Moreover, schematic diagram for the crystallizing mechanism of PA6 nanotubes was given to explain PA6 molecules how to crystallize in the nano-pores.

  10. Calcium Oxalate Crystals in Eucalypt Ectomycorrhizae: Morphochemical Characterization

    PubMed Central

    Pylro, Victor Satler; de Freitas, André Luiz Moreira; Otoni, Wagner Campos; da Silva, Ivo Ribeiro; Borges, Arnaldo Chaer; Costa, Maurício Dutra

    2013-01-01

    Ectomycorrhizal fungi are ubiquitous in forest ecosystems, benefitting plants principally by increasing the uptake of water and nutrients such as calcium from the soil. Previous work has demonstrated accumulation of crystallites in eucalypt ectomycorrhizas, but detailed morphological and chemical characterization of these crystals has not been performed. In this work, cross sections of acetic acid-treated and cleared ectomycorrhizal fragments were visualized by polarized light microscopy to evaluate the location of crystals within cortical root cells. Ectomycorrhizal sections were also observed by scanning electron microscopy (SEM) coupled with energy dispersive x-ray (EDS) microprobe analysis. The predominant forms of crystals were crystal sand (granules) and concretions. Calcium, carbon and oxygen were detected by EDS as constituent elements and similar elemental profiles were observed between both crystal morphologies. All analyzed crystalline structures were characterized as calcium oxalate crystals. This is the first report of the stoichiometry and morphology of crystals occurring in eucalypt ectomycorrhizas in tropical soils. The data corroborates the role of ectomycorrhizae in the uptake and accumulation of calcium in the form of calcium oxalate crystals in hybrid eucalypt plants. PMID:23844062

  11. Iron Oxide with Different Crystal Phases (α- and γ-Fe2O3) in Electroanalysis and Ultrasensitive and Selective Detection of Lead(II): An Advancing Approach Using XPS and EXAFS.

    PubMed

    Li, Shan-Shan; Li, Wen-Juan; Jiang, Tian-Jia; Liu, Zhong-Gang; Chen, Xing; Cong, Huai-Ping; Liu, Jin-Huai; Huang, Yu-Ying; Li, Li-Na; Huang, Xing-Jiu

    2016-01-01

    Iron oxide with different crystal phases (α- and γ-Fe2O3) has been applied to electrode coatings and been demonstrated to ultrasensitive and selective electrochemical sensing toward heavy metal ions (e.g., Pb(II)). A range of Pb(II) contents in micromoles (0.1 to 1.0 μM) at α-Fe2O3 nanoflowers with a sensitivity of 137.23 μA μM(-1) cm(-2) and nanomoles (from 0.1 to 1.0 nM) at γ-Fe2O3 nanoflowers with a sensitivity of 197.82 μA nM(-1) cm(-2) have been investigated. Furthermore, an extended X-ray absorption fine structure (EXAFS) technique was applied to characterize the difference of local structural environment of the adsorbed Pb(II) on the surface of α- and γ-Fe2O3. The results first showed that α- and γ-Fe2O3 had diverse interaction between Pb(II) and iron (hydro)oxides, which were consistent with the difference of electrochemical performance. Determining the responses of Cu(II) and Hg(II) as the most appropriate choice for comparison, the stripping voltammetric quantification of Pb(II) with high sensitivity and selectivity at γ-Fe2O3 nanoflower has been demonstrated. This work reveals that the stripping performances of a nanomodifier have to be directly connected with its intrinsic surface atom arrangement.

  12. Bridgman crystal growth

    NASA Technical Reports Server (NTRS)

    Carlson, Frederick

    1990-01-01

    The objective of this theoretical research effort was to improve the understanding of the growth of Pb(x)Sn(1-x)Te and especially how crystal quality could be improved utilizing the microgravity environment of space. All theoretical growths are done using the vertical Bridgman method. It is believed that improved single crystal yields can be achieved by systematically identifying and studying system parameters both theoretically and experimentally. A computational model was developed to study and eventually optimize the growth process. The model is primarily concerned with the prediction of the thermal field, although mass transfer in the melt and the state of stress in the crystal were of considerable interest. The evolution is presented of the computer simulation and some of the important results obtained. Diffusion controlled growth was first studied since it represented a relatively simple, but nontheless realistic situation. In fact, results from this analysis prompted a study of the triple junction region where the melt, crystal, and ampoule wall meet. Since microgravity applications were sought because of the low level of fluid movement, the effect of gravitational field strength on the thermal and concentration field was also of interest. A study of the strength of coriolis acceleration on the growth process during space flight was deemed necessary since it would surely produce asymmetries in the flow field if strong enough. Finally, thermosolutal convection in a steady microgravity field for thermally stable conditions and both stable and unstable solutal conditions was simulated.

  13. Protein Crystal Bovine Insulin

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The comparison of protein crystal, Bovine Insulin space-grown (left) and earth-grown (right). Facilitates the incorporation of glucose into cells. In diabetics, there is either a decrease in or complete lack of insulin, thereby leading to several harmful complications. Principal Investigator is Larry DeLucas.

  14. Laser schlieren crystal monitor

    NASA Technical Reports Server (NTRS)

    Owen, Robert B. (Inventor); Johnston, Mary H. (Inventor)

    1987-01-01

    A system and method for monitoring the state of a crystal which is suspended in a solution is described which includes providing a light source for emitting a beam of light along an optical axis. A collimating lens is arranged along the optical axis for collimating the emitted beam to provide a first collimated light beam consisting of parallel light rays. By passing the first collimated light beam through a transparent container, a number of the parallel light rays are deflected off the surfaces of said crystal being monitored according to the refractive index gradient to provide a deflected beam of deflected light rays. A focusing lens is arranged along optical axis for focusing the deflected rays towards a desired focal point. A knife edge is arranged in a predetermined orientation at the focal point; and a screen is provided. A portion of the deflected beam is blocked with the knife edge to project only a portion of the deflected beam. A band is created at one edge of the image of the crystal which indicates the state of change of the surface of the crystal being monitored.

  15. The Crystal Set

    ERIC Educational Resources Information Center

    Greenslade, Thomas B., Jr.

    2014-01-01

    In past issues of this journal, the late H. R. Crane wrote a long series of articles under the running title of "How Things Work." In them, Dick dealt with many questions that physics teachers asked themselves, but did not have the time to answer. This article is my attempt to work through the physics of the crystal set, which I thought…

  16. Computer-assisted Crystallization.

    ERIC Educational Resources Information Center

    Semeister, Joseph J., Jr.; Dowden, Edward

    1989-01-01

    To avoid a tedious task for recording temperature, a computer was used for calculating the heat of crystallization for the compound sodium thiosulfate. Described are the computer-interfacing procedures. Provides pictures of laboratory equipment and typical graphs from experiments. (YP)

  17. Single crystals of inulin.

    PubMed

    André, I; Putaux, J L; Chanzy, H; Taravel, F R; Timmermans, J W; de Wit, D

    1996-04-01

    Lamellar crystals of inulin were grown by crystallizing sharp fractions of low molecular weight inulin from dilute aqueous ethanol solutions. The crystals were analyzed using three-dimensional electron diffraction and X-ray powder diagrams. Two crystalline polymorphs were observed, depending on the hydration conditions: a hydrated form which indexed on an orthorhombic unit cell, with space group P2(1)2(1)2(1) and with cell dimensions of a = 1.670 nm, b = 0.980 nm and c (chain axis) = 1.47 nm, together with a pseudo-hexagonal semi-hydrated form with unit cell parameters a = 1.670 nm, b = 0.965 nm and c (chain axis) = 1.44 nm. These parameters, together with the density data, indicate that inulin crystallizes along a pseudo-hexagonal six-fold symmetry with an advance per monomer of 0.24 nm. The difference between the hydrated and the semi-hydrated unit cells does not seem to correspond to any change in the conformation of inulin, but rather to a variation in water content.

  18. DIFFRACTION FROM MODEL CRYSTALS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Although calculating X-ray diffraction patterns from atomic coordinates of a crystal structure is a widely available capability, calculation from non-periodic arrays of atoms has not been widely applied to cellulose. Non-periodic arrays result from modeling studies that, even though started with at...

  19. Copolymer Crystallization: Approaching Equilibrium

    NASA Astrophysics Data System (ADS)

    Crist, Buckley; Finerman, Terry

    2002-03-01

    Random ethylene-butene copolymers of uniform chemical composition and degree of polymerization are crystallized by evaporation of thin films (1 μ m - 5 μ m) from solution. Macroscopic films ( 100 μm) formed by sequential layer deposition are characterized by density, calorimetry and X-ray techniques. Most notable is the density, which in some cases implies a crystalline fraction nearly 90% of the equilibrium value calculated from Flory theory. Melting temperature of these solution deposited layers is increased by as much as 8 ^oC over Tm for the same polymer crystallized from the melt. Small-angle X-ray scattering indicates that the amorphous layer thickness is strongly reduced by this layered crystallization process. X-ray diffraction shows a pronounced orientation of chain axes and lamellar normals parallel to the normal of the macroscopic film. It is clear that solvent enhances chain mobility, permitting proper sequences to aggregate and crystallize in a manner that is never achieved in the melt.

  20. Protein crystal growth in microgravity

    NASA Technical Reports Server (NTRS)

    Rosenblum, William M.; Delucas, Lawrence J.; Wilson, William W.

    1989-01-01

    Major advances have been made in several of the experimental aspects of protein crystallography, leaving protein crystallization as one of the few remaining bottlenecks. As a result, it has become important that the science of protein crystal growth is better understood and that improved methods for protein crystallization are developed. Preliminary experiments with both small molecules and proteins indicate that microgravity may beneficially affect crystal growth. For this reason, a series of protein crystal growth experiments using the Space Shuttle was initiated. The preliminary space experiments were used to evolve prototype hardware that will form the basis for a more advanced system that can be used to evaluate effects of gravity on protein crystal growth. Various optical techniques are being utilized to monitor the crystal growth process from the incipient or nucleation stage and throughout the growth phase. The eventual goal of these studies is to develop a system which utilizes optical monitoring for dynamic control of the crystallization process.

  1. Protein crystal growth in space

    NASA Technical Reports Server (NTRS)

    Delucas, Lawrence J.; Bugg, Charles E.

    1991-01-01

    Studies of protein crystal growth in the microgravity environment in space are described with special attention given to the crystal growth facilities and the techniques used in Space Shuttle experiments. The properties of large space-grown crystals of gamma interferon, elastase, lathyros ochrus lectin I, and few other proteins grown on various STS flights are described. A comparison of the microgravity-grown crystals with the bast earth-grown crystals demonstrated that the space-grown crystals are more highly ordered at the molecular level than their earth-grown counterparts. When crystallization conditions were optimized, the microgravity-grown protein crystals were larger, displayed more uniform morphologies, and yielded diffraction data to significantly higher resolution than their earth-grown counterparts.

  2. Controlling Chirality of Entropic Crystals

    NASA Astrophysics Data System (ADS)

    Damasceno, Pablo F.; Karas, Andrew S.; Schultz, Benjamin A.; Engel, Michael; Glotzer, Sharon C.

    2015-10-01

    Colloidal crystal structures with complexity and diversity rivaling atomic and molecular crystals have been predicted and obtained for hard particles by entropy maximization. However, thus far homochiral colloidal crystals, which are candidates for photonic metamaterials, are absent. Using Monte Carlo simulations we show that chiral polyhedra exhibiting weak directional entropic forces self-assemble either an achiral crystal or a chiral crystal with limited control over the crystal handedness. Building blocks with stronger faceting exhibit higher selectivity and assemble a chiral crystal with handedness uniquely determined by the particle chirality. Tuning the strength of directional entropic forces by means of particle rounding or the use of depletants allows for reconfiguration between achiral and homochiral crystals. We rationalize our findings by quantifying the chirality strength of each particle, both from particle geometry and potential of mean force and torque diagrams.

  3. Macromolecular crystal growth in microgravity

    NASA Astrophysics Data System (ADS)

    McPherson, Alexander

    1996-03-01

    Two T=1 and one T=3 plant viruses, along with a protein were crystallized in microgravity during the International Microgravity Laboratory-2 (IML-2) mission in July of 1994 (Koszelak, et al. 1995). The method employed was liquid-liquid diffusion in the European Space Agency's Advanced Protein Crystallization Facility (APCF). Distinctive alterations in the habits of Turnip Yellow Mosaic Virus (TYMV) crystals and hexagonal canavalin crystals were observed. Crystals of cubic Satellite Tobacco Mosaic Virus (STMV) more than thirty times the volume of crystals grown in the laboratory were produced in microgravity. X-ray diffraction analysis demonstrated that both crystal forms of canavalin and the cubic STMV crystals diffracted to significantly higher resolution and had superior diffraction properties as judged by relative Wilson plots.

  4. Protein Crystals of Raf Kinase

    NASA Technical Reports Server (NTRS)

    1995-01-01

    This image shows crystals of the protein raf kinase grown on Earth (photo a) and on USML-2 (photo b). The space-grown crystals are an order of magnitude larger. Principal Investigator: Dan Carter of New Century Pharmaceuticals

  5. Controlling Chirality of Entropic Crystals.

    PubMed

    Damasceno, Pablo F; Karas, Andrew S; Schultz, Benjamin A; Engel, Michael; Glotzer, Sharon C

    2015-10-01

    Colloidal crystal structures with complexity and diversity rivaling atomic and molecular crystals have been predicted and obtained for hard particles by entropy maximization. However, thus far homochiral colloidal crystals, which are candidates for photonic metamaterials, are absent. Using Monte Carlo simulations we show that chiral polyhedra exhibiting weak directional entropic forces self-assemble either an achiral crystal or a chiral crystal with limited control over the crystal handedness. Building blocks with stronger faceting exhibit higher selectivity and assemble a chiral crystal with handedness uniquely determined by the particle chirality. Tuning the strength of directional entropic forces by means of particle rounding or the use of depletants allows for reconfiguration between achiral and homochiral crystals. We rationalize our findings by quantifying the chirality strength of each particle, both from particle geometry and potential of mean force and torque diagrams. PMID:26550757

  6. Dichroism in Helicoidal Crystals.

    PubMed

    Cui, Xiaoyan; Nichols, Shane M; Arteaga, Oriol; Freudenthal, John; Paula, Froilanny; Shtukenberg, Alexander G; Kahr, Bart

    2016-09-21

    Accounting for the interactions of light with heterogeneous, anisotropic, absorbing, optically active media is part of the characterization of complex, transparent materials. Stained biological structures in thin tissue sections share many of these features, but systematic optical analyses beyond the employ of the simple petrographic microscopes have not be established. Here, this accounting is made for polycrystalline, spherulitic bundles of twisted d-mannitol lamellae grown from melts containing light-absorbing molecules. It has long been known that a significant percentage of molecular crystals readily grow as helicoidal ribbons with mesoscale pitches, but a general appreciation of the commonality of these non-classical crystal forms has been lost. Helicoidal crystal twisting was typically assayed by analyzing refractivity modulation in the petrographic microscope. However, by growing twisted crystals from melts in the presence of dissolved, light-absorbing molecules, crystal twisting can be assayed by analyzing the dichroism, both linear and circular. The term "helicoidal dichroism" is used here to describe the optical consequences of anisotropic absorbers precessing around radii of twisted crystalline fibrils or lamellae. d-Mannitol twists in two polymorphic forms, α and δ. The two polymorphs, when grown from supercooled melts in the presence of a variety of histochemical stains and textile dyes, are strongly dichroic in linearly polarized white light. The bis-azo dye Chicago sky blue is modeled because it is most absorbing when parallel and perpendicular to the radial axes in the respective spherulitic polymorphs. Optical properties were measured using Mueller matrix imaging polarimetry and simulated by taking into account the microstructure of the lamellae. The optical analysis of the dyed, patterned polycrystals clarifies aspects of the mesostructure that can be difficult to extract from bundles of tightly packed fibrils. PMID:27617640

  7. Dichroism in Helicoidal Crystals.

    PubMed

    Cui, Xiaoyan; Nichols, Shane M; Arteaga, Oriol; Freudenthal, John; Paula, Froilanny; Shtukenberg, Alexander G; Kahr, Bart

    2016-09-21

    Accounting for the interactions of light with heterogeneous, anisotropic, absorbing, optically active media is part of the characterization of complex, transparent materials. Stained biological structures in thin tissue sections share many of these features, but systematic optical analyses beyond the employ of the simple petrographic microscopes have not be established. Here, this accounting is made for polycrystalline, spherulitic bundles of twisted d-mannitol lamellae grown from melts containing light-absorbing molecules. It has long been known that a significant percentage of molecular crystals readily grow as helicoidal ribbons with mesoscale pitches, but a general appreciation of the commonality of these non-classical crystal forms has been lost. Helicoidal crystal twisting was typically assayed by analyzing refractivity modulation in the petrographic microscope. However, by growing twisted crystals from melts in the presence of dissolved, light-absorbing molecules, crystal twisting can be assayed by analyzing the dichroism, both linear and circular. The term "helicoidal dichroism" is used here to describe the optical consequences of anisotropic absorbers precessing around radii of twisted crystalline fibrils or lamellae. d-Mannitol twists in two polymorphic forms, α and δ. The two polymorphs, when grown from supercooled melts in the presence of a variety of histochemical stains and textile dyes, are strongly dichroic in linearly polarized white light. The bis-azo dye Chicago sky blue is modeled because it is most absorbing when parallel and perpendicular to the radial axes in the respective spherulitic polymorphs. Optical properties were measured using Mueller matrix imaging polarimetry and simulated by taking into account the microstructure of the lamellae. The optical analysis of the dyed, patterned polycrystals clarifies aspects of the mesostructure that can be difficult to extract from bundles of tightly packed fibrils.

  8. Chiral Crystallization of Ethylenediamine Sulfate

    ERIC Educational Resources Information Center

    Koby, Lawrence; Ningappa, Jyothi B.; Dakesssian, Maria; Cuccia, Louis A.

    2005-01-01

    The optimal conditions for the crystallization of achiral ethylenediamine sulfate into large chiral crystals that are ideal for polarimetry studies and observation using Polaroid sheets are presented. This experiment is an ideal undergraduate experiment, which clearly demonstrates the chiral crystallization of an achiral molecule.

  9. Physical vapor transport crystal growth

    NASA Technical Reports Server (NTRS)

    Yoel, Dave W.; Anderson, Elmer; Wu, Maw-Kuen; Cheng, H. Y.

    1987-01-01

    The goals of this research are two-fold: to study effective means of growing ZnSe crystals of good optical quality and to determine the advantages of growing such crystals in microgravity. As of this date the optimal conditions for crystal growth have not been determined. However, successful growth runs were made in two furnances and the results are given.

  10. Growing Crystals for Infrared Detectors

    NASA Technical Reports Server (NTRS)

    Lehoczky, S. L.; Szofran, F. R.

    1984-01-01

    Unidirectional solidification yields bulk crystals with compositional homogeneity. Unidirectionaly crystal-growth furnace assembly travels vertically so crystal grows upward from bottom tapered end of ampoule. Separately controlled furnaces used for hot (upper) and cold (lower) zones. New process produces ingots with radial compositional homogeneity suitable for fabricating infrared detectors.

  11. Direct flow crystal growth system

    DOEpatents

    Montgomery, Kenneth E.; Milanovich, Fred P.

    1992-01-01

    A crystal is grown in a constantly filtered solution which is flowed directly into the growing face of a crystal. In a continuous flow system, solution at its saturation temperature is removed from a crystal growth tank, heated above its saturation temperature, filtered, cooled back to its saturation temperature, and returned to the tank.

  12. Surface properties of HMX crystal

    NASA Technical Reports Server (NTRS)

    Yee, R. Y.; Adicoff, A.; Dibble, E. J.

    1980-01-01

    The surface properties of Beta-HMX crystals were studied. The surface energies of three principal crystal faces were obtained by measuring contact angles with several reference liquids. The surface energies and polarity of the three crystal faces are found to be different.

  13. Small Business Innovations (Crystal Components)

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Scientific Materials Corporation, Bozeman, MT developed the SciMax line of improved Nd:Yag crystals under an Small Business Innovation Research (SBIR) contract with Langley Research Center. They reduced the amount of water trapped in the crystals during growth to improve the optical quality and efficiency. Applications of the crystals include fiber optics, telecommunications, welding, drilling, eye surgery and medical instrumentation.

  14. Direct observation of crystal growth from solution using optical investigation of a growing crystal face

    NASA Technical Reports Server (NTRS)

    Lal, Ravindra

    1994-01-01

    The first technical report for the period 1 Jan. 1993 till 31 Dec. 1993 for the research entitled, 'Direct observation of crystal growth from solution using Optical Investigation of a growing crystal Face' is presented. The work on the project did not start till 1 June 1993 due to the non-availability of the required personnel. The progress of the work during the period 1 June 1993 till the end of 1993 is described. Significant progress was made for testing various optical diagnostic techniques for monitoring crystal solution. Some of the techniques that are being tested are: heterodyne detection technique, in which changes in phase are measured as a interferometric function of time/crystal growth; a conventional technique, in which a fringe brightness is measured as a function of crystal growth/time; and a Mach-Zehnder interferometric technique in which a fringe brightness is measured as a function of time to obtain information on concentration changes. During the second year it will be decided to incorporate the best interferometric technique along with the ellipsometric technique, to obtain real time in-situ growth rate measurements. A laboratory mock-up of the first two techniques were made and tested.

  15. Liquid crystal orientation control in photonic liquid crystal fibers

    NASA Astrophysics Data System (ADS)

    Chychlowski, M. S.; Nowinowski-Kruszelnicki, E.; Woliński, T. R.

    2011-05-01

    Similarly to liquid crystal displays technology in photonic liquid crystal fibers (PLCFs) a molecular orientation control is a crucial issue that influences proper operation of PLCF-based devices. The paper presents two distinct configurations: planar and radial escaped orientation of the LC molecules inside capillaries as well as methods of their application to photonic liquid crystal fibers. Possibilities of LC orientation control influence both: attenuation and transmitting spectra of the PLCF The orienting method is based on creation of an additional orienting layer on the inner surface of the capillary or air hole of the photonic liquid crystal fiber. Aligning materials used in the experiment are commercially available polyimides SE1211 and SE130 which induce liquid crystal homeotropic and planar anchoring conditions. The orienting layer increase an order parameter of the liquid crystal improving propagation properties and stability of photonic liquid crystal fiber-based devices.

  16. Laser alexandrite crystals grown by horizontal oriented crystallization technique

    NASA Astrophysics Data System (ADS)

    Gurov, V. V.; Tsvetkov, E. G.; Yurkin, A. M.

    2008-05-01

    Comparative studies were performed for alexandrite crystals, Al 2BeO 4:Cr 3+, employed in solid state lasers and grown by the horizontal oriented crystallization (HOC) technique and alexandrite crystals grown by the Czochralski (Cz) method. It was shown that the structural quality and possibilities of generation of stimulated emission HOC-crystals are similar to Cz-crystals, whereas their damage threshold is about three times higher. The obtained results and considerably lower cost price of HOC-alexandrite crystals prove their advantageous application in powerful laser systems, which require large laser rods with a higher resistance to laser beam. It is emphasized that application of HOC technique is promising for growth of laser crystals of other high-temperature oxide compounds.

  17. Inclusion Analysis and Absorption Measurement in Nonlinear Crystals

    SciTech Connect

    Smith, L L

    2005-08-26

    Yttrium calcium oxyborate (YCOB) is a newly developed nonlinear optical crystal used for second harmonic generation in the Mercury laser. As with any new crystal, optical characterization of the material properties needs to be fully investigated. We are developing two new techniques to detect inclusions and measure optical absorption. With the side illuminating detection examination (SIDE) method, we hope to identify and map the size, density, and the morphology of inclusions. The multi-pass absorption technique (MPAT) will be used to help determine the absorption coefficient of various finished crystalline pieces at near-infrared wavelengths.

  18. Crystallization-induced properties from morphology-controlled organic crystals.

    PubMed

    Park, Chibeom; Park, Ji Eun; Choi, Hee Cheul

    2014-08-19

    During the past two decades, many materials chemists have focused on the development of organic molecules that can serve as the basis of cost-effective and flexible electronic, optical, and energy conversion devices. Among the potential candidate molecules, metal-free or metal-containing conjugated organic molecules offer high-order electronic conjugation levels that can directly support fast charge carrier transport, rapid optoelectric responses, and reliable exciton manipulation. Early studies of these molecules focused on the design and synthesis of organic unit molecules that exhibit active electrical and optical properties when produced in the form of thin film devices. Since then, researchers have worked to enhance the properties upon crystallization of the unit molecules as single crystals provide higher carrier mobilities and exciton recombination yields. Most recently, researchers have conducted in-depth studies to understand how crystallization induces property changes, especially those that depend on specific crystal surfaces. The different properties that depend on the crystal facets have been of particular interest. Most unit molecules have anisotropic structures, and therefore produce crystals with several unique crystal facets with dissimilar molecular arrangements. These structural differences would also lead to diverse electrical conductance, optical absorption/emission, and even chemical interaction properties depending on the crystal facet investigated. To study the effects of crystallization and crystal facet-dependent property changes, researchers must grow or synthesize crystals of highly conjugated molecules that have both a variety of morphologies and high crystallinity. Morphologically well-defined organic crystals, that form structures such as wires, rods, disks, and cubes, provide objects that researchers can use to evaluate these material properties. Such structures typically occur as single crystals with well-developed facets with

  19. Amplification and transduction of biospecific interactions at surfaces by using liquid crystals

    NASA Astrophysics Data System (ADS)

    Skaife, Justin John

    The research described in this thesis develops principles that exploit the sensitivity of liquid crystals to surfaces as a means for the detection of biologically important molecules. These principles are based on three observations: (1) the orientations of molecules forming liquid crystalline phases are highly sensitive to changes in surface structure on sub-micron length scales, (2) changes in the orientation of liquid crystals near surfaces (a few molecular lengths) can be amplified into bulk alignment transitions and (3) liquid crystals are birefringent, thus bulk alignment transitions can be transduced into readily observed optical signals. This thesis investigates: (I) the influence of the structure of supporting gold substrates on the alignment of liquid crystals, (II) the optical response of liquid crystal to proteins bound to these substrates, (III) manipulation of the mesoscale and molecular scale structure of surfaces to control the optical response of liquid crystals to bound proteins, (IV) the generality of these methods for detection of other biologically important types of molecules, and (V) patterning of substrates with ligands and controlled delivery of analytes using microfluidic networks for multiple analyte detection. This research has made possible the development of a quantitative diagnostic assay based on liquid crystals which can rapidly detect proteins at nanomolar concentrations without the need for labeled antibodies. In addition, this work has realized methods by which the optical response of liquid crystal to bound protein can be adjusted and multiple analytes can be detected on a single, small area.

  20. Protein Crystals Grown in Space

    NASA Technical Reports Server (NTRS)

    2000-01-01

    A collage of protein and virus crystals, many of which were grown on the U.S. Space Shuttle or Russian Space Station, Mir. The crystals include the proteins canavalin; mouse monoclonal antibody; a sweet protein, thaumatin; and a fungal protease. Viruses are represented here by crystals of turnip yellow mosaic virus and satellite tobacco mosaic virus. The crystals are photographed under polarized light (thus causing the colors) and range in size from a few hundred microns in edge length up to more than a millimeter. All the crystals are grown from aqueous solutions and are useful for X-ray diffraction analysis. Credit: Dr. Alex McPherson, University of California, Irvine.

  1. Plenum type crystal growth process

    DOEpatents

    Montgomery, Kenneth E.

    1992-01-01

    Crystals are grown in a tank which is divided by a baffle into a crystal growth region above the baffle and a plenum region below the baffle. A turbine blade or stirring wheel is positioned in a turbine tube which extends through the baffle to generate a flow of solution from the crystal growing region to the plenum region. The solution is pressurized as it flows into the plenum region. The pressurized solution flows back to the crystal growing region through return flow tubes extending through the baffle. Growing crystals are positioned near the ends of the return flow tubes to receive a direct flow of solution.

  2. Unprecedented crystal dynamics: reversible cascades of single-crystal-to-single-crystal transformations.

    PubMed

    Lv, Gao-Chao; Wang, Peng; Liu, Qing; Fan, Jian; Chen, Kai; Sun, Wei-Yin

    2012-10-21

    A series of Cu(II) complexes showed unprecedented reversible cascades of single-crystal-to-single-crystal (SCSC) transformations, and more interestingly, very rapid crystal dynamic processes were observed in this system via the substitution of coordinating components without loss of single crystallinity.

  3. Surrogate Seeds For Growth Of Crystals

    NASA Technical Reports Server (NTRS)

    Shlichta, Paul J.

    1989-01-01

    Larger crystals of higher quality grown. Alternative method for starting growth of crystal involves use of seed crystal of different material instead of same material as solution. Intended for growing single-crystal proteins for experiments but applicable in general to growth of crystals from solutions and to growth of semiconductor or other crystals from melts.

  4. CRYSTAL/FACE

    NASA Technical Reports Server (NTRS)

    Baumgardner, Darrel; Kok, Greg; Anderson, Bruce

    2004-01-01

    Droplet Measurement Technologies (DMT), under funding from NASA, participated in the CRYSTAL/FACE field campaign in July, 2002 with measurements of cirrus cloud hydrometeors in the size range from 0.5 to 1600 microns. The measurements were made with the DMT Cloud, Aerosol and Precipitation Spectrometer (CAPS) that was flown on NASA's WB57F. With the exception of the first research flight when the data system failed two hours into the mission, the measurement system performed almost flawlessly during the thirteen flights. The measurements from the CAPS have been essential for interpretation of cirrus cloud properties and their impact on climate. The CAPS data set has been used extensively by the CRYSTAL/FACE investigators and as of the date of this report, have been included in five published research articles, 10 conference presentations and six other journal articles currently in preparation.

  5. Graphite polyhedral crystals.

    PubMed

    Gogotsi, Y; Libera, J A; Kalashnikov, N; Yoshimura, M

    2000-10-13

    Polyhedral nano- and microstructures with shapes of faceted needles, rods, rings, barrels, and double-tipped pyramids, which we call graphite polyhedral crystals (GPCs), have been discovered. They were found in pores of glassy carbon. They have nanotube cores and graphite faces, and they can exhibit unusual sevenfold, ninefold, or more complex axial symmetry. Although some are giant radially extended nanotubes, Raman spectroscopy and transmission electron microscopy suggest GPCs have a degree of perfection higher than in multiwall nanotubes of similar size. The crystals are up to 1 micrometer in cross section and 5 micrometers in length, and they can probably be grown in much larger sizes. Preliminary results suggest a high electrical conductivity, strength, and chemical stability of GPC.

  6. Macromolecular crystal growing system

    NASA Technical Reports Server (NTRS)

    Snyder, Robert S. (Inventor); Herren, Blair J. (Inventor); Carter, Daniel C. (Inventor); Yost, Vaughn H. (Inventor); Bugg, Charles E. (Inventor); Delucas, Lawrence J. (Inventor); Suddath, Fred L. (Inventor)

    1991-01-01

    A macromolecular crystal growing system especially designed for growing crystals in the low gravity of space as well as the gravity of earth includes at least one tray assembly, a carrier assembly which receives the tray, and a refrigeration-incubation module in which the carrier assembly is received. The tray assembly includes a plurality of sealed chambers with a plastic syringe and a plug means for the double tip of the syringe provided therein. Ganging mechanisms operate the syringes and plugs simultaneously in a precise and smooth operation. Preferably, the tray assemblies are mounted on ball bearing slides for smooth operation in inserting and removing the tray assemblies into the carrier assembly. The plugging mechanism also includes a loading control mechanism. A mechanism for leaving a syringe unplugged is also provided.

  7. Twisted aspirin crystals.

    PubMed

    Cui, Xiaoyan; Rohl, Andrew L; Shtukenberg, Alexander; Kahr, Bart

    2013-03-01

    Banded spherulites of aspirin have been crystallized from the melt in the presence of salicylic acid either generated from aspirin decomposition or added deliberately (2.6-35.9 mol %). Scanning electron microscopy, X-ray diffraction analysis, and optical polarimetry show that the spherulites are composed of helicoidal crystallites twisted along the <010> growth directions. Mueller matrix imaging reveals radial oscillations in not only linear birefringence, but also circular birefringence, whose origin is explained through slight (∼1.3°) but systematic splaying of individual lamellae in the film. Strain associated with the replacement of aspirin molecules by salicylic acid molecules in the crystal structure is computed to be large enough to work as the driving force for the twisting of crystallites. PMID:23425247

  8. Crystallization of the large membrane protein complex photosystem I in a microfluidic channel.

    PubMed

    Abdallah, Bahige G; Kupitz, Christopher; Fromme, Petra; Ros, Alexandra

    2013-12-23

    Traditional macroscale protein crystallization is accomplished nontrivially by exploring a range of protein concentrations and buffers in solution until a suitable combination is attained. This methodology is time-consuming and resource-intensive, hindering protein structure determination. Even more difficulties arise when crystallizing large membrane protein complexes such as photosystem I (PSI) due to their large unit cells dominated by solvent and complex characteristics that call for even stricter buffer requirements. Structure determination techniques tailored for these "difficult to crystallize" proteins such as femtosecond nanocrystallography are being developed yet still need specific crystal characteristics. Here, we demonstrate a simple and robust method to screen protein crystallization conditions at low ionic strength in a microfluidic device. This is realized in one microfluidic experiment using low sample amounts, unlike traditional methods where each solution condition is set up separately. Second harmonic generation microscopy via second-order nonlinear imaging of chiral crystals (SONICC) was applied for the detection of nanometer- and micrometer-sized PSI crystals within microchannels. To develop a crystallization phase diagram, crystals imaged with SONICC at specific channel locations were correlated to protein and salt concentrations determined by numerical simulations of the time-dependent diffusion process along the channel. Our method demonstrated that a portion of the PSI crystallization phase diagram could be reconstructed in excellent agreement with crystallization conditions determined by traditional methods. We postulate that this approach could be utilized to efficiently study and optimize crystallization conditions for a wide range of proteins that are poorly understood to date.

  9. Crystal chemistry and real structure of crystals

    NASA Astrophysics Data System (ADS)

    Bartl, H.; Bats, J. W.; Dyck, W.; Fuess, H.; Gregory, A.; Joswig, W.; Lottermoser, W.; Koerfer, M.; Mueller, R.; Schweiss, B. P.

    1984-03-01

    Elastic and inelastic scattering, X-ray diffraction and spectroscopy were combined to obtain a comprehensive picture of the properties of crystals. The electron density distribution allows one to verify the models of the theoretical chemistry. Systematic investigations of chemically similar anions (ClO3 and ClO4; S2O3, SO3 and SO4) show differences in bonding and reaction capability. The X-ray-neutron method applied to these anions shows maxima between 0.2 and 0.4 eXA to the power-3 in the bondings of the unbound electrons on S and D. For the SO3-group good agreement is found with theoretical calculations. The effect of the Mg (two times ionized) cation on the density is demonstrated on the water molecules of MgS2O3.6H2O and MgSO3.6H2O. Magnetic structure and magnetization density were investigated on CO3V2O8, Fe2SiO4 and Mn2SiO4 with polarized neutrons. The differences in magnetic moments of both cation states is also demonstrated for Fe2SiO4 with complementary Mossbauer measurements. Inelastic time of flight experiments allow predictions concerning the motion of the NH3-group in aniliniumbromide and of the water molecule in natural zeolites. The theoretical model to calculate the photon dispersion on CaSO4 shows good agreement with the measured dispersion curves.

  10. Path to protein crystallization

    SciTech Connect

    2010-01-01

    Growth of two-dimensional S-layer crystals on supported lipid bilayers observed in solution using in situ atomic force microscopy. This movie shows proteins sticking onto the supported lipid bilayer, forming a mobile phase that condenses into amorphous clusters, and undergoing a phase transition to crystalline clusters composed of 2 to 15 tetramers. These initial clusters then enter a growth phase in which new tetramers form exclusively at unoccupied lattice sites along the cluster edges.

  11. The Crystal Set

    NASA Astrophysics Data System (ADS)

    Greenslade, Thomas B.

    2014-04-01

    In past issues of this journal, the late H. R. Crane wrote a long series of articles under the running title of "How Things Work." In them, Dick dealt with many questions that physics teachers asked themselves, but did not have the time to answer. This article is my attempt to work through the physics of the crystal set, which I thought I knew, but actually did not.

  12. Protein Crystal Isocitrate Lyase

    NASA Technical Reports Server (NTRS)

    1998-01-01

    The comparison of protein crystal, Isocitrate Lyase earth-grown (left) and space-grown (right). This is a target enzyme for fungicides. A better understanding of this enzyme should lead to the discovery of more potent fungicides to treat serious crop diseases such as rice blast; it regulates the flow of metabolic intermediates required for cell growth. Principal Investigator is Larry DeLucas.

  13. Photonic crystal optical memory

    NASA Astrophysics Data System (ADS)

    Lima, A. Wirth; Sombra, A. S. B.

    2011-06-01

    After several decades pushing the technology and the development of the world, the electronics is giving space for technologies that use light. We propose and analyze an optical memory embedded in a nonlinear photonic crystal (PhC), whose system of writing and reading data is controlled by an external command signal. This optical memory is based on optical directional couplers connected to a shared optical ring. Such a device can work over the C-Band of ITU (International Telecommunication Union).

  14. High density protein crystal growth

    NASA Technical Reports Server (NTRS)

    Rouleau, Robyn (Inventor); Delucas, Lawrence (Inventor); Hedden, Douglas Keith (Inventor)

    2004-01-01

    A protein crystal growth assembly including a crystal growth cell and further including a cell body having a top side and a bottom side and a first aperture defined therethrough, the cell body having opposing first and second sides and a second aperture defined therethrough. A cell barrel is disposed within the cell body, the cell barrel defining a cavity alignable with the first aperture of the cell body, the cell barrel being rotatable within the second aperture. A reservoir is coupled to the bottom side of the cell body and a cap having a top side is disposed on the top side of the cell body. The protein crystal growth assembly may be employed in methods including vapor diffusion crystallization, liquid to liquid crystallization, batch crystallization, and temperature induction batch mode crystallization.

  15. Crystallization of human nicotinamide phosphoribosyltransferase

    SciTech Connect

    Takahashi, Ryo; Nakamura, Shota; Yoshida, Takuya; Kobayashi, Yuji; Ohkubo, Tadayasu

    2007-05-01

    Human nicotinamide phosphoribosyltransferase has been crystallized using microseeding methods and X-ray diffraction data have been collected at 2.0 Å resolution. In the NAD biosynthetic pathway, nicotinamide phosphoribosyltransferase (NMPRTase; EC 2.4.2.12) plays an important role in catalyzing the synthesis of nicotinamide mononucleotide from nicotinamide and 5′-phosphoribosyl-1′-pyrophosphate. Because the diffraction pattern of the initally obtained crystals was not suitable for structure analysis, the crystal quality was improved by successive use of the microseeding technique. The resultant crystals diffracted to 2.0 Å resolution. These crystals belonged to space group P21, with unit-cell parameters a = 60.56, b = 106.40, c = 82.78 Å. Here, the crystallization of human NMPRTase is reported in the free form; the crystals should be useful for inhibitor-soaking experiments on the enzyme.

  16. Modern trends in technical crystallization

    NASA Astrophysics Data System (ADS)

    Matz, G.

    1980-04-01

    Interesting and significant developments have occurred in the last decade in both crystallization equipment and in the theory of crystallization process. In the field of technical crystallization new crystallizers have been developed and computer modelling has become important in scaling up and in the achievement of increased performance. The DP-Kristaller developed by Escher-Wyss-Tsukishima, the Brodie purifier, the sieve tray column having dancing balls, the automated multiple crystallization process due to Mützenberg and Saxer and the double belt cooler, all of which represent technical developments, are described in the first section. The second part of the paper reviews computer modelling of the fluidized bed crystallizer, chemical precipitation, flaking and prilling. Finally, there is a brief discussion of the impact of technical crystallization processes on environmental protection.

  17. Crystallization of undercooled liquid fenofibrate.

    PubMed

    Amstad, Esther; Spaepen, Frans; Weitz, David A

    2015-11-28

    Formulation of hydrophobic drugs as amorphous materials is highly advantageous as this increases their solubility in water and therefore their bioavailability. However, many drugs have a high propensity to crystallize during production and storage, limiting the usefulness of amorphous drugs. We study the crystallization of undercooled liquid fenofibrate, a model hydrophobic drug. Nucleation is the rate-limiting step; once seeded with a fenofibrate crystal, the crystal rapidly grows by consuming the undercooled liquid fenofibrate. Crystal growth is limited by the incorporation of molecules into its surface. As nucleation and growth both entail incorporation of molecules into the surface, this process likely also limits the formation of nuclei and thus the crystallization of undercooled liquid fenofibrate, contributing to the good stability of undercooled liquid fenofibrate against crystallization.

  18. Gelled Lyotropic Liquid Crystals.

    PubMed

    Xu, Yang; Laupheimer, Michaela; Preisig, Natalie; Sottmann, Thomas; Schmidt, Claudia; Stubenrauch, Cosima

    2015-08-11

    In our previous work we were able to prove that gelled bicontinuous microemulsions are a novel type of orthogonal self-assembled system. The study at hand aims at complementing our previous work by answering the question of whether gelled lyotropic liquid crystals are also orthogonal self-assembled systems. For this purpose we studied the same system, namely, water-n-decane/12-hydroxyoctadecanoic acid (12-HOA)-n-decyl tetraoxyethylene glycol ether (C10E4). The phase boundaries of the nongelled and the gelled lyotropic liquid crystals were determined visually and with (2)H NMR spectroscopy. Oscillating shear measurements revealed that the absolute values of the storage and loss moduli of the gelled liquid crystalline (LC) phases do not differ very much from those of the binary organogel. While both the phase behavior and the rheological properties of the LC phases support the hypothesis that gelled lyotropic liquid crystals are orthogonal self-assembled systems, freeze-fracture electron microscopy (FFEM) seems to indicate an influence of the gel network on the structure of the Lα phase and vice versa.

  19. Slotted Photonic Crystal Sensors

    PubMed Central

    Scullion, Mark G.; Krauss, Thomas F.; Di Falco, Andrea

    2013-01-01

    Optical biosensors are increasingly being considered for lab-on-a-chip applications due to their benefits such as small size, biocompatibility, passive behaviour and lack of the need for fluorescent labels. The light guiding mechanisms used by many of them results in poor overlap of the optical field with the target molecules, reducing the maximum sensitivity achievable. This review article presents a new platform for optical biosensors, namely slotted photonic crystals, which provide higher sensitivities due to their ability to confine, spatially and temporally, the optical mode peak within the analyte itself. Loss measurements showed values comparable to standard photonic crystals, confirming their ability to be used in real devices. A novel resonant coupler was designed, simulated, and experimentally tested, and was found to perform better than other solutions within the literature. Combining with cavities, microfluidics and biological functionalization allowed proof-of-principle demonstrations of protein binding to be carried out. Higher sensitivities were observed in smaller structures than possible with most competing devices reported in the literature. This body of work presents slotted photonic crystals as a realistic platform for complete on-chip biosensing; addressing key design, performance and application issues, whilst also opening up exciting new ideas for future study. PMID:23503295

  20. Slotted photonic crystal sensors.

    PubMed

    Scullion, Mark G; Krauss, Thomas F; Di Falco, Andrea

    2013-01-01

    Optical biosensors are increasingly being considered for lab-on-a-chip applications due to their benefits such as small size, biocompatibility, passive behaviour and lack of the need for fluorescent labels. The light guiding mechanisms used by many of them results in poor overlap of the optical field with the target molecules, reducing the maximum sensitivity achievable. This review article presents a new platform for optical biosensors, namely slotted photonic crystals, which provide higher sensitivities due to their ability to confine, spatially and temporally, the optical mode peak within the analyte itself. Loss measurements showed values comparable to standard photonic crystals, confirming their ability to be used in real devices. A novel resonant coupler was designed, simulated, and experimentally tested, and was found to perform better than other solutions within the literature. Combining with cavities, microfluidics and biological functionalization allowed proof-of-principle demonstrations of protein binding to be carried out. Higher sensitivities were observed in smaller structures than possible with most competing devices reported in the literature. This body of work presents slotted photonic crystals as a realistic platform for complete on-chip biosensing; addressing key design, performance and application issues, whilst also opening up exciting new ideas for future study. PMID:23503295

  1. The polymorphic weddellite crystals in three species of Cephalocereus (Cactaceae).

    PubMed

    Bárcenas-Argüello, María-Luisa; Gutiérrez-Castorena, Ma C-del-Carmen; Terrazas, Teresa

    2015-10-01

    Mineral inclusions in plant cells are genetically regulated, have an ecological function and are used as taxonomic characters. In Cactaceae, crystals in epidermal and cortical tissues have been reported; however, few studies have conducted chemical and morphological analyses on these crystals, and even fewer have reported non-mineral calcium to determine its systematic value. Cephalocereus apicicephalium, C. totolapensis and C. nizandensis are Cactaceae species endemic to the Isthmus of Tehuantepec, Mexico with abundant epidermal prismatic crystals. In the present study, we characterize the mineral cell inclusions, including their chemical composition and their morphology, for three species of Cephalocereus. Crystals of healthy branches of the three species were isolated and studied. The crystals were identified by X-ray diffraction (XRD), their morphology was described using a petrographic and scanning electron microscope (SEM), and their elemental composition was measured with Energy Dispersive X-ray (EDXAR). The three species synthesized weddellite with different degrees of hydration depending on the species. The optical properties of calcium oxalate crystals were different from the core, which was calcium carbonate. We observed a large diversity of predominantly spherical forms with SEM. EDXAR analysis detected different concentrations of Ca and significant amounts of elements, such as Si, Mg, Na, K, Cl, and Fe, which may be related to the edaphic environment of these cacti. The occurrence of weddellite is novel for the genus according to previous reports. The morphological diversity of the crystals may be related to their elemental composition and may be a source of phylogenetic characters.

  2. Origin of Aggregate Formation in Antibody Crystal Suspensions Containing PEG.

    PubMed

    Hildebrandt, Christian; Mathaes, Roman; Saedler, Rainer; Winter, Gerhard

    2016-03-01

    The crystalline state of proteins is deemed as a promising formulation platform for biopharmaceuticals. However, a stabilizing effect of protein crystal suspensions is controversially discussed. In fact, antibodies can display an increased aggregation and particle formation profile after the crystallization process compared with liquid or solid amorphous formulations. Nevertheless, studies regarding aggregate formation and its origin remain meager in literature. It was the aim of this study to investigate these aspects for a model IgG antibody (mAb1), which shows an increased aggregate formation after crystallization with polyethylene glycol. The presence of a dynamic equilibrium, a steady exchange of protein between the crystals and the supernatant, was demonstrated by replacing the supernatant with an identical but fluorescence-labeled protein solution and followed by confocal laser scanning microscopy. Aggregate formation was monitored by size exclusion high-pressure chromatography and flow cytometry. Constantly increasing aggregate levels were found for the crystal fraction and for the supernatant. For the later, markedly higher particle counts were detected. The labeled supernatant and the unlabeled protein crystals allowed a precise identification of the origin of the aggregates. The rising aggregate fractions of the crystals displayed high mean fluorescence intensities that elucidated their origin in the supernatant. PMID:26886344

  3. Discrete breathers in crystals

    NASA Astrophysics Data System (ADS)

    Dmitriev, S. V.; Korznikova, E. A.; Baimova, Yu A.; Velarde, M. G.

    2016-05-01

    It is well known that periodic discrete defect-containing systems, in addition to traveling waves, support vibrational defect-localized modes. It turned out that if a periodic discrete system is nonlinear, it can support spatially localized vibrational modes as exact solutions even in the absence of defects. Since the nodes of the system are all on equal footing, it is only through the special choice of initial conditions that a group of nodes can be found on which such a mode, called a discrete breather (DB), will be excited. The DB frequency must be outside the frequency range of the small-amplitude traveling waves. Not resonating with and expending no energy on the excitation of traveling waves, a DB can theoretically conserve its vibrational energy forever provided no thermal vibrations or other perturbations are present. Crystals are nonlinear discrete systems, and the discovery in them of DBs was only a matter of time. It is well known that periodic discrete defect-containing systems support both traveling waves and vibrational defect-localized modes. It turns out that if a periodic discrete system is nonlinear, it can support spatially localized vibrational modes as exact solutions even in the absence of defects. Because the nodes of the system are all on equal footing, only a special choice of the initial conditions allows selecting a group of nodes on which such a mode, called a discrete breather (DB), can be excited. The DB frequency must be outside the frequency range of small-amplitude traveling waves. Not resonating with and expending no energy on the excitation of traveling waves, a DB can theoretically preserve its vibrational energy forever if no thermal vibrations or other perturbations are present. Crystals are nonlinear discrete systems, and the discovery of DBs in them was only a matter of time. Experimental studies of DBs encounter major technical difficulties, leaving atomistic computer simulations as the primary investigation tool. Despite

  4. Investigation of New Ionic Plastic Crystals in Tetraalkylammonium Tetrabuthylborate

    NASA Astrophysics Data System (ADS)

    Hayasaki, Tomoyuki; Hirakawa, Satoru; Honda, Hisashi

    2014-09-01

    New plastic crystals of NEt3PrBBu4 and NEt2Pr2BBu4 were formed in a new region of ionic plastic crystal. In this area, globular cations and anions are assembled by weak interactions. Differential scanning calorimeter (DSC) measurements of these salts showed a low entropy change of 19:6 and 14:0 JK-1 mol-1 at each melting point, respectively. On the basis of solid-state 1H and 13C nuclear magnetic resonance (NMR) spectra and electrical conductivity measurements, isotropic reorientation and ion transfer of globular cations and anions were detected in these crystals. The other compounds of NEtxMe(4-x)BBu4 (x = 1 - 3) showed tumbling motions and low activation energies of self-diffusion in crystals

  5. Proton extraction from the CERN SPS using bent silicon crystals

    NASA Astrophysics Data System (ADS)

    Elsener, K.; Fidecaro, G.; Gyr, M.; Herr, W.; Klem, J.; Mikkelsen, U.; Møller, S. P.; Uggerhøj, E.; Vuagnin, G.; Weisse, E.

    1996-10-01

    The extraction of high energy particles from a circular accelerator by means of channeling in bent crystals is an attractive alternative to classical extraction schemes, in particular for high energy proton colliders where a classical scheme becomes expensive and incompatible with normal operation. This paper reviews the ongoing extraction experiments at the CERN-SPS with bent silicon crystals. It describes the principles of beam extraction by means of a bent crystal and the different extraction schemes used: first- and multi-pass extraction and the methods to create diffusion. The limitations in tuning the accelerator to the desired impact parameters and crucial items concerning crystal preparation, bending and pre-alignment are discussed. The experimental procedures including an overview of the detection of circulating and extracted beam are given. Finally, the paper summarizes the results of these experiments together with ideas for future developments.

  6. Coupling light in photonic crystal waveguides: A review

    NASA Astrophysics Data System (ADS)

    Dutta, Hemant Sankar; Goyal, Amit Kumar; Srivastava, Varun; Pal, Suchandan

    2016-07-01

    Submicron scale structures with high index contrast are key to compact structures for realizing photonic integrated structures. Ultra-compact optical devices in silicon-on-insulator (SOI) substrates serve compatibility with semiconductor fabrication technology leading to reduction of cost and mass production. Photonic crystal structures possess immense potential for realizing various compact optical devices. However, coupling light to photonic crystal waveguide structures is crucial in order to achieve strong transmission and wider bandwidth of signal. Widening of bandwidth will increase potential for various applications and high transmission will make easy signal detection at the output. In this paper, the techniques reported so far for coupling light in photonic crystal waveguides have been reviewed and analyzed so that a comprehensive guide for an efficient coupling to photonic crystal waveguides can be made possible.

  7. Functionalizing Designer DNA Crystals

    NASA Astrophysics Data System (ADS)

    Chandrasekaran, Arun Richard

    Three-dimensional crystals have been self-assembled from a DNA tensegrity triangle via sticky end interaction. The tensegrity triangle is a rigid DNA motif containing three double helical edges connected pair-wise by three four-arm junctions. The symmetric triangle contains 3 unique strands combined in a 3:3:1 ratio: 3 crossover, 3 helical and 1 central. The length of the sticky end reported previously was two nucleotides (nt) (GA:TC) and the motif with 2-helical turns of DNA per edge diffracted to 4.9 A at beam line NSLS-X25 and to 4 A at beam line ID19 at APS. The purpose of these self-assembled DNA crystals is that they can be used as a framework for hosting external guests for use in crystallographic structure solving or the periodic positioning of molecules for nanoelectronics. This thesis describes strategies to improve the resolution and to incorporate guests into the 3D lattice. The first chapter describes the effect of varying sticky end lengths and the influence of 5'-phosphate addition on crystal formation and resolution. X-ray diffraction data from beam line NSLS-X25 revealed that the crystal resolution for 1-nt (G:C) sticky end was 3.4 A. Motifs with every possible combination of 1-nt and 2-nt sticky-ended phosphorylated strands were crystallized and X-ray data were collected. The position of the 5'-phosphate on either the crossover (strand 1), helical (strand 2), or central strand (3) had an impact on the resolution of the self-assembled crystals with the 1-nt 1P-2-3 system diffracting to 2.62 A at APS and 3.1 A at NSLS-X25. The second chapter describes the sequence-specific recognition of DNA motifs with triplex-forming oligonucleotides (TFOs). This study examined the feasibility of using TFOs to bind to specific locations within a 3-turn DNA tensegrity triangle motif. The TFO 5'-TTCTTTCTTCTCT was used to target the tensegrity motif containing an appropriately embedded oligopurine.oligopyrimidine binding site. As triplex formation involving cytidine

  8. Crystallization Optimum Solubility Screening: using crystallization results to identify the optimal buffer for protein crystal formation

    SciTech Connect

    Collins, Bernard; Stevens, Raymond C.; Page, Rebecca

    2005-12-01

    It is shown how protein crystallization results can be used to identify buffers that improve protein solubility and, in turn, crystallization success. An optimal solubility screen is described that uses the results of crystallization trials to identify buffers that improve protein solubility and, in turn, crystallization success. This screen is useful not only for standard crystallization experiments, but also can easily be implemented into any high-throughput structure-determination pipeline. As a proof of principle, the predicted novel-fold protein AF2059 from Archaeoglobus fulgidus, which was known to precipitate in most buffers and particularly during concentration experiments, was selected. Using the crystallization results of 192 independent crystallization trials, it was possible to identify a buffer containing 100 mM CHES pH 9.25 that significantly improves its solubility. After transferring AF2059 into this ‘optimum-solubility’ buffer, the protein was rescreened for crystal formation against these same 192 conditions. Instead of extensive precipitation, as observed initially, it was found that 24 separate conditions produced crystals and the exchange of AF2059 into CHES buffer significantly improved crystallization success. Fine-screen optimization of these conditions led to the production of a crystal suitable for high-resolution (2.2 Å) structure determination.

  9. Morphological conversion of calcium oxalate crystals into stones is regulated by osteopontin in mouse kidney.

    PubMed

    Okada, Atsushi; Nomura, Shintaro; Saeki, Yukihiko; Higashibata, Yuji; Hamamoto, Shuzo; Hirose, Masahito; Itoh, Yasunori; Yasui, Takahiro; Tozawa, Keiichi; Kohri, Kenjiro

    2008-10-01

    An important process in kidney stone formation is the conversion of retentive crystals in renal tubules to concrete stones. Osteopontin (OPN) is the major component of the kidney calcium-containing stone matrix. In this study, we estimated OPN function in early morphological changes of calcium oxalate crystals using OPN knockout mice: 100 mg/kg glyoxylate was intra-abdominally injected into wildtype mice (WT) and OPN knockout mice (KO) for a week, and 24-h urine oxalate excretion showed no significant difference between WT and KO. Kidney crystal depositions were clearly detected by Pizzolato staining but not by von Kossa staining in both genotypes, and the number of crystals in KO was significantly fewer than in WT. Morphological observation by polarized light optical microphotography and scanning electron microphotography (SEM) showed large flower-shaped crystals growing in renal tubules in WT and small and uniform crystals in KO. X-ray diffraction detected the crystal components as calcium oxalate monohydrate in both genotypes. Immunohistochemical staining of OPN showed that the WT crystals contained OPN protein but not KO crystals. We concluded that OPN plays a crucial role in the morphological conversion of calcium oxalate crystals to stones in mouse kidneys.

  10. Crystal growth in salt efflorescence

    NASA Astrophysics Data System (ADS)

    Zehnder, Konrad; Arnold, Andreas

    1989-09-01

    Salt efflorescences strongly affect wall paintings and other monuments. The external factors governing the crystal habits and aggregate forms are studied phenomenologically in laboratory experiments. As salt contaminated materials dry, slats crystallize forming distinct sequences of crystal habits and aggregate forms on and underneath the surfaces. Four phases may be distinguished: (1) Large individual crystals with equilibrium forms grow immersed in a thick solution film; (2) granular crusts of small isometric crystals grow covered by a thin solution film; (3) fibrous crusts of columnar crystals grow from a coherent but thin solution film so that the crystals are in contact with solution only at their base; (4) whiskers grow from isolated spots of very thin solution films into the air. The main factor governing these morphologies is the humidity of the substrate. A porous material cracks while granular crystals (approaching their equilibrium forms) grow within the large pores. As the fissures widen, the habits pass into columnar crystals and then into whiskers. Because this succession corresponds to the crystallization sequence on the substrate surface it can be traced back to the same growth conditions.

  11. DDA Computations of Porous Aggregates with Forsterite Crystals: Effects of Crystal Shape and Crystal Mass Fraction

    NASA Technical Reports Server (NTRS)

    Wooden, Diane H.; Lindsay, Sean S.; Harker, David; Woodward, Charles; Kelley, Michael S.; Kolokolova, Ludmilla

    2015-01-01

    Porous aggregate grains are commonly found in cometary dust samples and are needed to model cometary IR spectral energy distributions (SEDs). Models for thermal emissions from comets require two forms of silicates: amorphous and crystalline. The dominant crystal resonances observed in comet SEDs are from Forsterite (Mg2SiO4). The mass fractions that are crystalline span a large range from 0.0 < or = fcrystal < or = 0.74. Radial transport models that predict the enrichment of the outer disk (>25 AU at 1E6 yr) by inner disk materials (crystals) are challenged to yield the highend-range of cometary crystal mass fractions. However, in current thermal models, Forsterite crystals are not incorporated into larger aggregate grains but instead only are considered as discrete crystals. A complicating factor is that Forsterite crystals with rectangular shapes better fit the observed spectral resonances in wavelength (11.0-11.15 microns, 16, 19, 23.5, 27, and 33 microns), feature asymmetry and relative height (Lindley et al. 2013) than spherically or elliptically shaped crystals. We present DDA-DDSCAT computations of IR absorptivities (Qabs) of 3 micron-radii porous aggregates with 0.13 < or = fcrystal < or = 0.35 and with polyhedral-shaped Forsterite crystals. We can produce crystal resonances with similar appearance to the observed resonances of comet Hale- Bopp. Also, a lower mass fraction of crystals in aggregates can produce the same spectral contrast as a higher mass fraction of discrete crystals; the 11micron and 23 micron crystalline resonances appear amplified when crystals are incorporated into aggregates composed otherwise of spherically shaped amorphous Fe-Mg olivines and pyroxenes. We show that the optical properties of a porous aggregate is not linear combination of its monomers, so aggregates need to be computed. We discuss the consequence of lowering comet crystal mass fractions by modeling IR SEDs with aggregates with crystals, and the implications for radial

  12. Magneto-photonic crystals for optical sensing applications

    NASA Astrophysics Data System (ADS)

    Dissanayake, Neluka

    Among the optical structures investigated for optical sensing purpose, a significant amount of research has been conducted on photonic crystal based sensors. A particular advantage of photonic crystal based sensors is that they show superior sensitivity for ultra-small volume sensing. In this study we investigate polarization changes in response to the changes in the cover index of magneto-optic active photonic band gap structures. One-dimensional photonic-band gap structures fabricated on iron garnet materials yield large polarization rotations at the band gap edges. The enhanced polarization effects serve as an excellent tool for chemical sensing showing high degree of sensitivity for photonic crystal cover refractive index changes. The one dimensional waveguide photonic crystals are fabricated on single-layer bismuth-substituted rare earth iron garnet films ((Bi, Y, Lu)3(Fe, Ga)5O12 ) grown by liquid phase epitaxy on gadolinium gallium garnet substrates. Band gaps have been observed where Bragg scattering conditions links forward-going fundamental waveguide modes to backscattered high-order waveguide modes. Large near-band-edge polarization rotations which increase progressively with backscattered-mode order have been experimentally demonstrated for multiple samples with different composition, film thickness and fabrication parameters. Experimental findings are supported by theoretical analysis of Bloch modes polarization states showing that large near stop-band edge rotations are induced by the magneto-photonic crystal. Theoretical and experimental analysis conducted on polarization rotation sensitivity to waveguide photonic crystal cover refractive index changes shows a monotonic enhancement of the rotation with cover index. The sensor is further developed for selective chemical sensing by employing Polypyrrole as the photonic crystal cover layer. Polypyrrole is one of the extensively studied conducting polymers for selective analyte detection. Successful

  13. Mechanical twinning in small quartz crystals

    NASA Astrophysics Data System (ADS)

    Laughner, J. W.; Newnham, R. E.; Cross, L. E.

    1982-02-01

    Quartz is known to be ferrobielastic; that is, quartz crystals have domain states (Dauphiné twins) which differ in their elastic compliance values and which can be switched by an appropriately oriented stress. Polycrystalline quartz has also been reported (Tullis 1970) to show preferential orientation of these domains following application of large uniaxial stresses. These experiments were designed to study twinning of synthetic quartz “grains” (minimum size 0.07×0.07×0.02 cm) in specially-constructed composites and of grains in three natural quartz aggregates — a quartzite, a novaculite, and a jasper. Backreflection X-ray techniques were used to verify twinning in the composite grains, while special electroding and electrical detection allowed the twinning processes to be examined in “real time.” Small synthetic quartz crystals were found to behave identically to the massive samples previously studied. Electrical pulses due to the reversal of piezoelectric coefficient d 11 in twinned quartz were detected from quartzite and from the man-made composites. Novaculite also gave electrical pulses which were probably from twinning (evidenced by the correlation of expected and observed pulse sizes and shapes), while no pulses from the jaspers indicative of twinning were detected. Grain size distribution differences are considered the main structural reason for the different behaviors.

  14. Features of the uniaxial elastic deformation of X-ray-irradiated p-Si crystals

    SciTech Connect

    Pavlyk, B. V.; Lys, R. M. Didyk, R. I.; Shykorjak, J. A.

    2015-05-15

    Changes in the conductivity of p-Si single-crystals irradiated at room temperature during their mechanical compression and stress relief are studied. It is shown that irradiation is accompanied by the generation of point defects in silicon, which play the role of stoppers for dislocation motion. The effect of “radiation memory” in “electronic” silicon crystals is detected.

  15. Infrared Signal Detection by Upconversion Technique

    NASA Technical Reports Server (NTRS)

    Wong, Teh-Hwa; Yu, Jirong; Bai, Yingxin; Johnson, William E.

    2014-01-01

    We demonstrated up-conversion assisted detection of a 2.05-micron signal by using a bulk periodically poled Lithium niobate crystal. The 94% intrinsic up-conversion efficiency and 22.58% overall detection efficiency at pW level of 2.05-micron was achieved.

  16. Ambient air contamination: Characterization and detection techniques

    NASA Technical Reports Server (NTRS)

    Nulton, C. P.; Silvus, H. S.

    1985-01-01

    Techniques to characterize and detect sources of ambient air contamination are described. Chemical techniques to identify indoor contaminants are outlined, they include gas chromatography, or colorimetric detection. Organics generated from indoor materials at ambient conditions and upon combustion are characterized. Piezoelectric quartz crystals are used as precision frequency determining elements in electronic oscillators.

  17. Dynamically controlled crystallization method and apparatus and crystals obtained thereby

    NASA Technical Reports Server (NTRS)

    Arnowitz, Leonard (Inventor); Steinberg, Emanuel (Inventor)

    2003-01-01

    A method and apparatus for dynamically controlling the crystallization of molecules including a crystallization chamber (14) or chambers for holding molecules in a precipitant solution, one or more precipitant solution reservoirs (16, 18), communication passages (17, 19) respectively coupling the crystallization chamber(s) with each of the precipitant solution reservoirs, and transfer mechanisms (20, 21, 22, 24, 26, 28) configured to respectively transfer precipitant solution between each of the precipitant solution reservoirs and the crystallization chamber(s). The transfer mechanisms are interlocked to maintain a constant volume of precipitant solution in the crystallization chamber(s). Precipitant solutions of different concentrations are transferred into and out of the crystallization chamber(s) to adjust the concentration of precipitant in the crystallization chamber(s) to achieve precise control of the crystallization process. The method and apparatus can be used effectively to grow crystals under reduced gravity conditions such as microgravity conditions of space, and under conditions of reduced or enhanced effective gravity as induced by a powerful magnetic field.

  18. Screening of nucleation conditions using levitated drops for protein crystallization.

    PubMed

    Santesson, Sabina; Cedergren-Zeppezauer, Eila S; Johansson, Thomas; Laurell, Thomas; Nilsson, Johan; Nilsson, Staffan

    2003-04-01

    The growth of suitable protein crystals is an essential step in the structure determination of a protein by X-ray crystallography. At present, crystals are mostly grown using trial-and-error procedures, and protocols that rapidly screen for the crystal nucleation step are rare. Presented here is an approach to minimize the consumption of precious protein material while searching for the nucleation conditions. Acoustically levitated drops of known protein concentration (0.25-1.5-microL volumes) are injected with crystallizing agents using piezoelectric flow-through dispensers (ejecting 50-100-pL droplets at 1-9000 droplets/s). A restricted number of crystallizing agents representing three classes are used: poly(ethylene glycol), salts, and the viscous alcohol 2-methyl 2,4-pentanediol. From a digitized picture of the levitated drop volume, calculations are performed giving the concentrations of all components in the drop at any time during a "precipitation experiment". Supersaturation is the prerequisite for crystal nucleation, and protein precipitation indicates high supersaturation. A light source illuminates the levitated drop, and protein precipitation is monitored using right-angle light scattering. On the basis of these intensity measurements and the volume determination, precipitation diagrams for each crystallizing agent are constructed that give the protein/crystallizing agent concentration boundaries between the minimum and the maximum detectable protein precipitation. Guided by the concentration values obtained from such plots, when approaching the supersaturation region, separate crystallization drops are mixed and allowed to equilibrate under paraffin oil. At conditions in which microcrystals can be observed, the nucleation tendency of the macromolecule is confirmed. Optimization of crystallization conditions can then follow. Proteins tested include alcohol dehydrogenase and D-serine dehydratase. Alcohol dehydrogenase, known to crystallize easily, was

  19. Lasing from fluorescent protein crystals.

    PubMed

    Oh, Heon Jeong; Gather, Malte C; Song, Ji-Joon; Yun, Seok Hyun

    2014-12-15

    We investigated fluorescent protein crystals for potential photonic applications, for the first time to our knowledge. Rod-shaped crystals of enhanced green fluorescent protein (EGFP) were synthesized, with diameters of 0.5-2 μm and lengths of 100-200 μm. The crystals exhibit minimal light scattering due to their ordered structure and generate substantially higher fluorescence intensity than EGFP or dye molecules in solutions. The magnitude of concentration quenching in EGFP crystals was measured to be about 7-10 dB. Upon optical pumping at 485 nm, individual EGFP crystals located between dichroic mirrors generated laser emission with a single-mode spectral line at 513 nm. Our results demonstrate the potential of protein crystals as novel optical elements for self-assembled, micro- or nano-lasers and amplifiers in aqueous environment.

  20. Dissipation by a crystallization process

    NASA Astrophysics Data System (ADS)

    Dorosz, Sven; Voigtmann, Thomas; Schilling, Tanja

    2016-01-01

    We discuss crystallization as a non-equilibrium process. In a system of hard spheres under compression at a constant rate, we quantify the amount of heat that is dissipated during the crystallization process. We interpret the dissipation as arising from the resistance of the system against phase transformation. An intrinsic compression rate is identified that separates a quasi-static regime from one of rapidly driven crystallization. In the latter regime the system crystallizes more easily, because new relaxation channels are opened, at the cost of forming a higher fraction of non-equilibrium crystal structures. We rationalize the change in the crystallization mechanism by analogy with shear thinning, in terms of a kinetic competition between near-equilibrium relaxation and external driving.