bluuebunny/crossref_metadata_2025 huggingface dataset:
Recent Developments in DNA Fragment Sizing by Flow Cytometry
Authors: Johnson Mitchell E. , Petty Jeffrey T. , Goodwin Peter M. , Martin John C. , Ambrose W. Patrick , Marrone Babetta L. , Jett James H. , Keller Richard A.
Published: February 2023

Gel electrophoresis is the most widely accepted technique for analysis and separation of DNA fragments. Standard gel electrophoresis is used for fragment sizes up to approximately 50 kb in length. Larger fragments must be separated by some form of pulsed field electrophoresis (1). Capillary gel electrophoresis (2) and ultrathin slab gel electrophoresis (3) are currently being developed to allow for high speed separation of DNA sequencing ladders for sizes less than 1 kb. No matter what form of electrophoresis is used, the separation is highly non-linear and generally has an upper limit to the size of the DNA that can be analyzed. In addition, conventional gel-based separations may take many hours, depending on required resolution and detection method.
Monte Carlo Model of a Single Molecule Counting Experiment
Authors: Davis Lloyd M. , Li Li-Qiang
Published: February 2023

In experiments for fluorescence detection of single molecules in solution the background due to unrejected scattered light increases linearly with laser power while the dye molecule fluorescence signal and photodegradation probability saturate.
Electrophoresis of Single Fluorescent Molecules
Authors: Castro Alonso , Shera Brooks
Published: February 2023

The fast, efficient detection and separation of minute quantities of biologically important molecules plays a central role in a variety of fields, such as molecular biology, biotechnology, immunology, medical diagnostics, and forensic analysis. It has proven difficult to identify and separate biomolecules at such low concentrations by existing means. Thus, it is of importance to develop methods that are able to probe such low concentrations with adequate sensitivity, resolution and ease. Here, we describe a new method for detecting and identifying individual fluorescent molecules in solution. The technique involves the measurement of electrophoretic velocities of individual molecules in a mixture, and identification by comparison with the electrophoretic velocity known to be characteristic of a particular molecular species. The application of the method to the detection and size identification of DNA restriction fragments in solution at the single molecule level has been demonstrated. In a similar experiment, the electrophoretic velocities of single molecules of the protein phycoerythrin was determined. Although we have focused on the detection and identification of biologically important molecules, the technique has the potential to find applications in organic and inorganic chemical analysis.
Silicon Processing Chemical Diagnostics and Control Using Diode Lasers
Authors: Whittaker Edward A. , Sun H. C. , Ng C. K. , Singh B. , Patel V.
Published: February 2023

Infra-red diode laser absorption spectroscopy has long been a powerful tool for molecular spectroscopists and analytic chemists. Through recent improvements in lead salt laser fabrication lasers with modest power (up to several milliwatts), good beam quality and broad tunability (as much as 30% of center frequency) are now available. In addition, very low absorbence species detection, free of window induced interference fringes is now possible by utilizing a combination of frequency and wavelength modulation via the diode laser injection current.1 This modulation approach also lends itself to a simple feedback method that may be used to lock the laser frequency to a particular molecular absorption line and thus enable real time measurements of that species' absorbence in the presence of high levels of electrical background noise often found in industrial settings.2
Unimolecular Photochemistry Studied by Photodissociation-Photoionization Mass Spectrometry
Authors: Johnston M.V. , Ross P.L. , Van Bramer S.E. , Leavitt E.D.
Published: February 2023

Photochemical reactions are commonly studied in the condensed phase or in a high pressure gas. The primary photodissociation products are inferred from distributions of stable compounds produced by secondary reactions. As these investigations are extended to molecules of increasing size and complexity, identification of the primary products becomes difficult owing to the large number of possible secondary reactions. In photodissociation-photoionization mass spectrometry (PDPI-MS), molecular photodissociation is performed at low pressure in the source region of a mass spectrometer. After a short time delay, the neutral photodissociation products are softly ionized with coherent vacuum ultraviolet radiation and mass analyzed. Unlike photochemical experiments at high pressure, PDPI permits direct observation of the entire product distribution on the microsecond timescale.
Optical Diagnostics of Single Liquid Droplets
Authors: Winter Michael
Published: February 2023

Most propulsion and energy utilization devices rely on the spraying of liquid-phase fuel or oxidizer, into an energy conversion chamber. The behavior of individual droplets in a spray combustor is a critical part of the combustion process, and currently we can only speculate about several fundamental aspects related to droplet heat-up and evaporation. A series of laser diagnostic techniques has been developed to measure heat and mass transfer associated with individual droplets characteristic of a spray. One such technique provides images of flow patterns along a meridian slice of small droplets using Laser-Induced Fluorescence (LIF), illustrating the presence of internal circulation. Extremely accurate vaporization rate measurements are being performed by using individual droplets as miniature lasers, producing Morphology–Dependant Resonances (MDR). MDR output mode-structure (primarily wavelength) contains information about the laser cavity dimensions and is related to droplet size. Another set of measurements is aimed at studying gas-phase-flow/flame front interactions in a microgravity environment using both planar laser–induced fluorescence and Partical Image Velocimetry, (PIV). By developing new ways of probing individual droplets, an understanding of the fundamental physics governing their behavior may be gained.
Structure and Extended Electronic States in Molecular Assemblies of Hemicyanine Amphiphiles
Authors: Song Q. , Xu Z. , Lu W. , Bohn P.W. , Blanchard GJ.
Published: February 2023

Hemicyanine dyes containing long alkyl chains have attracted considerable attention in recent years due to their significance as possible optoelectronic and molecular electronic materials. With large non-linear molecular polarizabilities, amphiphilic hemicyanines are readily incorporated into Langmuir-Bludgett monolayer and multilayer films, forming artificial molecular assemblies with preferred spatial and orientational order [1,2], In contrast to centrosymmetric bulk materials, in which the individual effects are canceled, and the overall bulk second-order susceptibility vanishes [1], highly aligned structures ensure non-zero macroscopic second-order susceptibilities, χ(2). In addition molecular assemblies of these materials have been shown to be characterized by extended electronic states in which the relationship between molecular structure and delocalization of the electronic states is a matter of current interest.
Application Of Diode Lasers To Atmospheric Diagnostics
Authors: Silver Joel A. , Hovde D. Christian , Bomse David S. , Oh Daniel B. , Kane Daniel J. , Stanton Alan C.
Published: February 2023

Diode lasers provide reliable, inexpensive and compact sources of light readily usable for the detection of virtually any small molecule in the gas phase. In particular, near-infrared and visible diodes exhibit properties especially attractive to real-world measurement applications: operation at room temperature, fiber optic compatibility and minimal power requirements. These lasers can be used in rugged instruments designed for long-term, unattended operation. In this paper, a diverse range of applications in atmospheric sensing is discussed.
Laser Spectroscopy for Practical Isotope Ratio Measurements
Authors: Shaw Robert W. , Barshick C. M. , Young J. P. , Ramsey J. M.
Published: February 2023

Isotope ratio measurements are typically accomplished by methods that are seldom amenable to field use. An example is thermal ionization mass spectrometry (TIMS)i where solid samples are dissolved, a filament loaded with the resulting solution, the filament mounted in a source chamber, the mass spectrometer pumped to low pressure, the filament heated to produce analyte ions, and finally the ions separated according to mass in either space or time for counting. There is a need for field mass spectrometric measurements, particularly in the environmental remediation arena, where near real time results can save time and reduce costs. Miniaturized ion traps that can be deployed for field measurement of organics have been reported. 2 There currently are no isotope ratio methods in field use.
A Dual Fabry-Perot Optical Fiber Sensor
Authors: Wang Qi
Published: February 2023

Interferometric fiber—optic sensors, while capable of high resolution .have in general been accompanied by a limited unambiguous operating range. They also have had limited applicability for measurement temperature, strain and displacment. Owing to the problem of initiating the system, i. e. the interferometer switch off, all the information about the measured phase will be lost and new initial conditions must be determined when system is turn on again(1). A. S. Gerges had presented a system which is a Michelson interferometer with two equal length arms. A digital feedback servo is used to track the zero optical path difference(2). However, the optical fiber in Gerges’s system are inherently distributed sensors. This can be a disadvantage when point measurment Eire required. G. Beheim had presented another system in which a Fabry-Perot cavity is used as a sensing cavity(3), a Michelson interferometer is used to measure the spacing of the sensing cavity. Let us call it FPM system. The central peak of the interferometric fringe in FPM system is nearly as higher as other peaks. This makes the system very difficult to lock in the central peak. Also, the central peak's half-width of the FPM system is comparatively larger than that of dual F-P system ( DFP ) . This limits the resolution of FPM system. G. Beheim has also presented a dual F-P cavities system. But its electronics CEUI not make sure that the system is locked in the central peak of the transmitted optical signal(4).
IR Heterodyne Receiver For High Resolution Measurements of Molecular Species in the Stratosphere
Authors: Cheo P.K. , Zhou Y.
Published: February 2023

Remote sensing of trace molecules by measuring solar absorption spectra in the mid-IR region has been proved to be one of the useful methods to explore the earth's atmosphere. To fully resolve the Doppler broadened line profiles in the stratosphere, a resolving power of > 105 is required and only available technique is laser heterodyne spectroscopy[1].
Measuring CO Concentration and Temperature in a CH4/air Premixed Flame with Broadband Coherent Anti-Stokes Raman Spectroscopy
Authors: HAHN J.W. , PARK S.N. , KANG K.T. , CHUNG S.H.
Published: February 2023

Coherent anti-Stokes Raman spectroscopy (CARS) has been widely used as a diagnostic tool for probing the temperature and species concentration of gas phase samples. CARS concentration measurements are typically performed either from the integration1,2 or from the shape of a CARS spectrum.3, 4 If the resonant signal of CARS is much bigger than the nonresonant background, integration of the CARS spectrum depends linearly on the squares of the concentration of the species. In practice, this method can be used to measure the concentration of major species. When the fraction of a species goes down to the order of a few percentage, the nonresonant background becomes comparable to the resonant signal of CARS and interferes with the resonant signal. In such a case, the portion of the nonresonant background included in the integration of the CARS spectrum leads to a large error in the concentration measurement. The interference of the nonresonant background and the real term of the resonant signal of CARS form modulation dips on the spectrum that are sensitive to the concentration. Recently Hahn et al.5 proposed a new technique for measuring the minor species concentration from the modulation dip of nonresonant background of broadband CARS spectrum.
Laser Light-Scattering Interferometry for Real-Time Diagnostic Studies of Aerosols Produced by a New High-Efficiency Nebulizer
Authors: Montaser Akbar , Liu Huiying
Published: February 2023

Laser light-scattering interferometry or the Phase/Doppler technique has been used in a wide variety of particle-sizing applications, including diagnostic studies of combustion processes, nozzle sprays, and droplets in the atmosphere [1-5]. In this technique, radiation from a laser is split into two or four beams, the beams are focused and crossed over a very small measurement volume. As the droplets or particles pass through the intersection of the laser beams, scattering occurs and temporal and spatial frequencies of the droplets or particles are recorded to obtain droplet velocities, diameter, and concentration. The principle behind this measurement technique is similar to that for the laser Doppler velocimetery, except that scattered light is detected at large angle using two or more photodetectors. If a two-beam system (1D or one-component system) is used, particle size (0.5 to 10,000 μm) and particle velocities can be simultaneously measured in one direction on a microsecond time scale (down to 0.8 μs). With the two-component system (2D system), these parameters are assessed in two directions. In short, a Phase/Doppler instrument allows measurements of temporal and spatial information for a particle field. In contrast, the droplet size measured with laser Fraunhofer diffraction [6,7] represents a line-of-sight integral measurement, and droplet velocity information cannot be obtained.
Trapping of Laser Desorbed Ions in an Ion Trap Mass Spectrometer Using a Gated RF Field
Authors: Eiden G. C. , Garrett A. W. , Cisper M. E. , Nogar N. S. , Hemberger P. H.
Published: February 2023

We report a new method for trapping laser desorbed ions in a quadrupole ion trap mass spectrometer (ITMS). This method, gated RF trapping, improves the trapping efficiency by over two orders of magnitude over previous methods. If the RF trapping field is applied before the laser fires, there will be a large potential barrier for injection of ions into the trap.1 In general, ions either have insufficient energy to penetrate the entrance barrier, or they penetrate the entrance barrier and pass through the trap because the entrance and exit barrier heights are the same. Collisions reduce the kinetic energy of desorbed ions and increase the probability of trapping. Gated RF trapping takes advantage of the risetime of the RF in the ITMS: the laser is fired early in the rise of the RF and ions are presented with a small potential barrier to entry into the trap, but by the time the ions cross the trap the barrier has risen substantially, hindering their escape. Ions are more efficiently trapped than by buffer gas collisions alone and good sensitivity is obtained at very low buffer gas pressures (10-5 Torr) allowing high mass resolution operation. This simple picture is complicated by factors such as Debye shielding, plume reactions, and buffer gas collisions. In this paper, we describe the effects of laser-to-RF phase and delay, and buffer gas pressure and composition.2,3
Optical Diagnostics of VUV Laser CVD of Semiconductors
Authors: Barth M. , Knobloch J. , Hess P.
Published: February 2023

Amorphous hydrogenated germanium (a-Ge:H) was deposited using an ArF excimer laser (193 nm) and Ge2H6 as source gas in parallel configuration. The dependence of the film properties on the deposition parameters such as substrate temperature, laser power, digermane partial pressure and total pressure was fully characterized. The results obtained for the Urbach energy, hydrogen content, Tauc gap, density, E-modulus as well as dark and photoconductivity show that high quality material can be deposited by ArF laser CVD.
Diode-Laser-Based Detection of BTXE-Aromatics in Oil Polluted Soil Samples
Authors: Schade W. , Blanke T.
Published: February 2023

The generation of tunable laser radiation in the spectral range between 4 and 10 µm is of general interest for the spectroscopy since most of the fundamental vibrational modes of molecules are within this spectral region [1]. There exist several conventional tunable cw-laser systems, like lead salt-diodes, color center-, optical parametric-, and CO or CO2 side band lasers. However, they need cryogenic cooling, do not cover all spectral regions that are of general interest for the spectroscopy and in most cases they are very complicated and complex laser sources. This limits the possibilities for practical applications of mid-infrared absorption spectroscopy, e.g. in the trace analysis of environmental pollutants. Therefore there is still a lack in simple, compact, portable, and rugged mid-infrared laser sources. In this context diode-lasers and difference frequency generation (DFG) in new nonlinear media such as AgGaS2 have drawn considerable interest in the construction of compact cw laser spectrometers [2,3].
Characterization of Semiconductor Materials by the Photoionization of Sputtered Neutrals Using Ultra-High Laser Intensities
Authors: Wise Michael L. , Downey Stephen W.
Published: February 2023

The depth profiling of dopant concentrations across ultrathin device structures is critical to microelectronic device design and fabrication. Secondary Ion Mass Spectrometry (SIMS) remains an extremely important technique for semiconductor characterization. However, secondary ion production during sputtering is extremely dependent on matrix composition, complicating the characterization of elemental concentrations at or near the interfaces of two materials. For this reason, complementary analytical techniques referred to as Sputtered Neutrals Mass Spectrometry (SNMS) have been developed. In SNMS, a laser beam is used to ionize the neutral species in the gas phase above the sample after ion beam sputtering. These "post-ionization" techniques can accomplish surface analysis and depth profiling with high sensitivity and relative freedom from matrix effects. The application of ultra-high intensity lasers (>1014 W / cm2) to the post-ionization technique creates the possibility that all the sputtered species, regardless of electronic structure, will be non-resonantly ionized with high efficiency1. Uniform ionization of all the sputtered species within the laser volume will greatly simplify the quantification of unknown materials.
Advanced Laser Detection Techniques for Cone Penetrometer Sensors
Authors: Wormhoudt J. , Shorter J. H. , McManus J. B. , Kebabian P. L. , Nelson D. D. , Zahniser M. S. , Kolb C. E.
Published: February 2023

This paper presents work in two areas of laser detection technique development for application to cone penetrometer measurements of contaminants in soils. In both cases, the initial target contaminants are explosives and energetic materials, and the basic technique involves detection by heating contaminated soils and quantifying the resulting pyrolysis gases. In the first area, tunable infrared laser differential absorption spectroscopy (TILDAS) is being applied in two ways: as a sensitive, specific real-time diagnostic of laboratory experiments designed to improve understanding of basic mechanisms, and as a potential in situ detection technique for inclusion in a penetrometer probe. In the second area, a novel class of miniature laser devices will be extended to provided visible and ultraviolet light sources for laser induced fluorescence (LIF) detection of pyrolysis gases.
Real-Time Laser Ablation MS/MS of Individual Airborne Microparticles
Authors: Reilly P. T. A. , Yang M. , Gieray R. , Whitten W. B. , Ramsey J. M.
Published: February 2023

In the past, chemical analysis of airborne particulates was done in the
bulk. In other words, particles were collected on a filter and later
extracted and subjected to chemical analysis. This provides only a
very time consuming statistical constituent analysis of the ensemble
of particles that is generally incomplete. All information about
composition and chemistry of the individual particles was lost.
Recently, mass spectrometric techniques have been applied to
individual particles in real-time. Analysis of individual
particles via time-of-flight has had great success with the lighter
inorganic constituents, but is unenlightening when used on organic
based particles. Application of ion trap MS/MS techniques to
organically derived particulates permits positive identification of
any of the constituents.
Applications of Infrared Spectroscopy for Combustion Diagnostics
Authors: Rakestraw David J.
Published: February 2023

The application of infrared spectroscopies for combustion diagnostics offers an exciting new opportunity to measure a wide range of polyatomic molecular species. The ability to measure low concentrations of many species important in combustion chemistry has been limited to a great extent to molecules that that can be probed using laser-induced fluorescence in the visible and ultraviolet spectral regions. Over the past several years our group has been investigating the use of infrared spectroscopies in an effort to greatly expand the polyatomic molecules that can be probed using laser diagnostics. This effort has benefited from advances in laser technology as well as the development of new spectroscopic approaches. The work discussed in this paper makes use of a tunable single-mode optical parametric oscillator system to provide high resolution rovibrational spectra. Degenerate four-wave mixing (DFWM) and cavity ringdown laser absorption spectroscopy (CRLAS) are the two spectroscopic techniques investigated.
In-Flight Laser Induced Fluorescence from Microgravity Droplet Combustion
Authors: Winter Michael
Published: February 2023

Most propulsion and energy utilization devices rely on the spraying of
liquid-phase propellants, in the form of fuel or oxidizer, into an
energy conversion chamber. The behavior of individual droplets in a
spray combustor is a critical part of the combustion process. Basic
understanding is best advanced by well-controlled experiments and
simplified calculations. A great deal of attention has been paid to
studying the combustion of individual droplets, which is the
simplest example of non-premixed combustion. These single-droplet
flames provide an idealized geometry for investigating the interaction
of the physical and chemical processes involved. A significant means
of simplifying droplet combustion is to approach the phenomena in a
microgravity environment.
OH, NO, and Soot Measurement in Diesel Spray Flames Using Laser Induced Fluorescence and Laser Induced Incandescence
Authors: Nakagawa Hiroshi , Endo Hiroyuki , Deguchi Yoshihiro , Noda Matsuhei , Oikawa Hiroshi , Shimada Taizo
Published: February 2023

Although the time-space mechanism of NOx formation in diesel injection combustion in high temperature and pressure has conventionally been pursued by the sampling method and so forth(1), the cause-effect relationship on its formation factors still remains to be more accurately clarified. In our present research, NO, OH and soot in diesel fuel flames from a single injection in high temperature and pressure were measured using a motoring compressed injection test system by applying laser induced fluorescence (LIF)(2)(3)(4)(5)(6) and laser induced incandescence (LU)(6)(7), both of which can provide unperturbed measurements necessary for clarifying formation characteristics of harmful exhaust substances from diesel fuel flames in high pressure.
Multiplex polarization spectroscopy of OH for flame thermometry
Authors: New M.J. , Ewart P. , Dreizler A. , Dreier T.
Published: February 2023

Laser-based techniques for combustion diagnostics are becoming increasingly important as they allow remote and non-intrusive measurements of flame parameters with high spatial and temporal resolution. Linear light scattering methods such as Laser Induced Fluorescence, Rayleigh and Raman scattering have been successfully applied [1]. In some situations non-linear processes such as coherent anti-Raman scattering (CARS) offer certain advantages over linear techniques. CARS is a four-wave mixing process and generates a signal in the form of a coherent beam of radiation but is suitable only for the detection of majority species [1]. Degenerate four-wave mixing (DFWM) is an important resonant technique which has been used to detect [2] and image [3] minority species in flames and also has the advantages inherent to a coherent process.
Prognosis for a mid-infrared magnetic rotation spectrometer for the in situ detection of atmospheric free radicals
Authors: Chackerian C. , Blake T. A. , Mahon C. R. , Podolske. J. R.
Published: February 2023

We investigate magnetic rotation spectroscopy as a technique for the ultrasensitive detection of free radical molecular species in the Earth's atmosphere. In order to design field instruments which have parts per trillion by volume per second sensitivity we obtain a quantitative description of experiments we have done at higher concentration levels.
A Laser-Induced Breakdown Spectroscopy Probe for the In Situ Detection of Metal Contamination in Soils
Authors: Theriault Gregory A. , Lieberman Stephen H.
Published: February 2023

Laser-induced breakdown spectroscopy (LIBS) involves the analysis of the spectral emission from a laser-induced spark. In a typical LIBS measurement, the high power emission from a pulsed laser is focused to a small spot on a sample material. The resulting power density in the small volume about the focal point is usually in excess of several GW/cm2. Under these conditions, rapid heating, vaporization and ionization of a small amount of the sample material occurs and the subsequent laser-induced plasma emission is spectroscopically analyzed to yield information about the elemental species present in the sample.
High Resolution Visible Laser Spectroscopy of Molecular Ions
Authors: Tu Q. , Harvey V. I. , Marawar R. W. , Farley John W.
Published: February 2023

Molecular ions have posed a formidable challenge to spectroscopists due to the difficulty in generating sufficient concentrations of ions to produce a detectable signal. The high chemical reactivity of molecular ions and the mutual Coulomb repulsion of like charges result in small densities of ions, whose signal can be masked by larger densities of neutrals. For a long time spectroscopic information was limited to observations in optical emission. In the last two decades, spectroscopists have developed new techniques to study molecular ions1,2.
Diode Laser Absorption Spectroscopy of Combustion Gases Near 1.57 Microns
Authors: Sonnenfroh David M. , Allen Mark G.
Published: February 2023

Sensors for rapid, in-situ measurements of hydrocarbon combustion intermediates and products are required for applications ranging from advanced combustor testing to aeropropulsion engine health monitoring. Recent developments in room temperature diode laser technology and sensitive detection strategies now permit development of a new class of combustion sensors for simultaneous measurements of the speciation of the combustion gases as well as gasdynamic performance parameters of interest, including temperature, velocity, and mass flux.1,2 This work focusses on absorption measurements of CO, CO2, H2O, and OH in combustion gases near 1.57 µm. Experiments are conducted in low-pressure, room-temperature absorption cells and combustion gases of a flat-flame burner with hydrogen and methane fuels. The laser source is a New Focus Model 6262 external cavity diode laser, generating over 1 mW of output power across an 80 nm tuning range centered at 1.55 µm. High sensitivity detection is achieved using a dual-beam, Balanced Ratiometric Detector (BRD)1 which cancels common-mode laser amplitude noise in the signal channel (passing through the absorbing medium) and reference channel (passing through a non-absorbing gas or fiber).
Large-scale chemical analysis by laser-induced fluorescence detection and multiple capillary electrophoresis separation
Authors: Dovichi Norman J. , Zhang Jian Zhong , Bay Sue , Crabtree John , Roos Pieter
Published: February 2023

Capillary electrophoresis provides rapid separation of long DNA sequencing fragments. However, it is necessary to operate many capillaries in parallel to compete with slab-gel electrophoresis systems. A number of capillary array instruments have been reported based on a scanning optical detector; these systems suffer from a low detection duty cycle.
Cell Imaging by Laser-Induced Native Fluorescence Microscopy
Authors: Yeung Edward S. , Tong Wei , Lillard Sheri
Published: February 2023

The high degree of heterogeneity of the nervous and endocrine systems makes it extremely important for real-time monitoring of dynamic chemical changes at the single-cell level to gain a better understanding of the interaction of cells with their environment. Secretion mediated by exocytosis is one of the fundamental phenomena whose mechanism mimics the release of neurotransmitters at synaptic sites. Although the regulation of the secretory pathway has been studied extensively, its molecular mechanism is still not clear. It is important to develop methods that can follow real-time secretory processes with both high temporal and high spatial resolution. The native fluorescence of some proteins and neurotransmitters excited by a deep-UV laser has been shown to be a powerful probe for single-cell analysis. The advantages of direct native fluorescence detection include: (1) no chemical derivatization with fluorescent dyes is needed so no contamination or additional background will be introduced; (2) uncertainties about the efficiencies of the derivatization reaction are eliminated to ensure fast and quantitative response, without influences from slow reaction kinetics or incomplete equilibrium; and (3) the biological integrity of the cells will not be unnecessarily disturbed by having additional reagents or from exposure to artificial environments. We report the coupling of laser-induced native fluorescence detection with capillary electrophoresis (CE) to quantitatively monitor the secretion of insulin, serotonin and catecholamines from single cells. The uptake of serotonin by single living astrocytes was also recorded by native fluorescence imaging microscopy. The catecholamine (mainly epinephrine and norepinephrine) secreting adrenal chromaffin cells have been used as “model nerve terminals” to elucidate the molecular mechanism of neurotransmitter secretion at the nerve terminal. The in vitro dynamics of catecholamine release from bovine adrenal chromaffin cells was monitored with both high spatial and high temporal resolution.
Laser Induced Fluorescence in Inhibited Counterflow Diffusion Flames
Authors: Daniel Robert G. , Skaggs R. Reed , Homan Barie E. , Miziolek Andrzej W. , McNesby Kevin L.
Published: February 2023

As part of the continuing effort to find an effective, yet safe, replacement compound for the commonly used halon fire suppression agents, we have begun a study of reduced pressure counterflow diffusion flames inhibited with iron pentacarbonyl (Fe(CO)5). Iron pentacarbonyl has been shown to be a very effective fire suppression agent in small quantities, but there is little understanding of the mechanism of its activity. The goal of this study is to understand the mechanism by which Fe(CO)5 inhibits flames by coupling experimental measurements with computer modeling of diffusion flames. This project is part of the Next Generation Fire Suppression Program (NGFSP).
Diode-laser absorption measurements of CO2, H2O, and N2O near 2 μm
Authors: Mihalcea R. M. , Baer D. S. , Hanson R. K. , Feller G. S.
Published: February 2023

A tunable external-cavity diode laser (ECDL) operating near 2.0 μm was used to perform absorption measurements of CO2, H2O, and N2O in a heated static cell at various pressures (15 - 760 torr) and temperatures (294 K - 1460 K). The present work represents an extension of previous diode-laser absorption measurements of weaker vibrational overtones near 1.5 μm1 and thus offers significantly higher measurement sensitivity. Absorption survey spectra of CO2, H2O, and N2O in the spectral region between 4866 cm−1 and 5118 cm−1 were recorded, compared to calculations (based on the HITRAN96 and HITEMP databases), and used to select the optimum transitions for concentration measurements. Individual transitions (1-cm−1 scans) were measured in order to determine line strength values and self broadening parameters.
A Laser and Fiber Optics Based, Passive, Differential System to Measure the Optical Properties of Liquids and Gases
Authors: Harrolle Jennifer , Bass Michael , Acharekar Madhu
Published: February 2023

It is often desirable or necessary to measure the optical properties of liquids and gases in remote locations. Examples include measurement of the absorption and scattering of ocean water or the monitoring of liquid quality during manufacturing large volumes of product. In such cases it may be inconvenient or dangerous or both to retrieve samples for off line measurement and it may be too risky or expensive to submerse the appropriate conventional instruments. In this paper a device is described in which laser light is delivered to a remote sample of liquid by a fiber optic and collected through another fiber optic enabling measurement of optical absorption, scattering and also, if fluorescing materials are present, their emissions. The device is shown schematically in Fig. 1. In a safe location, in a console, are all the operator controls, laser light sources, beam handling and control optics and electronics to generate the light, deliver it to the send fiber and sense light returned by the appropriate collector lens return fiber combination. At the distal end of the send fiber a lens collimates the beam for transmission through the medium. A second lens collects the transmitted or scattered light and focuses it into a return fiber. Detectors and electronics in the console record and process this data.
Velocity, Temperature and Density Measurements in Reacting Flows Using Laser-Induced Gratings
Authors: Brown Michael S. , Roberts William L.
Published: February 2023

The development of future commercial combustors, as well as the refinement of current models, relies heavily on diagnostic information collected on operating combustors. Key diagnostic information includes spatially resolved maps of the local velocity, temperature, and density fields. Optical diagnostics in commercial combustors are hampered by complications due to high pressure and the presence of particulates, such as soot, which greatly increases the flame luminosity. To meet these challenges we are pursuing laser-induced grating techniques. Recent work has shown that these techniques perform well at high pressure (Brown et al 1995) and in the presence of soot (Brown and Roberts 1997). To date successful speciation and thermometry have been demonstrated, and the first report of velocity measurements has recently been communicated by Paul Ewart’s group.
Sodium concentration measurements with resonant holographic interferometry for gas and multi-phase environments
Authors: Dimalanta Ramon , Dunn-Rankin Derek , Brock Neal J. , DeBarber Peter A. , Brown Mike S. , Segall Jeff , Millerd James E.
Published: February 2023

Resonant holographic interferometry (RHI) is a non-intrusive, laser-based diagnostic that has the potential to quantify species concentrations in both gas-phase and multi-phase (liquid and gas) environments. The technique exploits the rapid change in refractive index of a probed medium near absorption features. The change in refractive index is significant enough to change the effective pathlength or create a phase change in the light tuned to the absorption line. These phase changes can be resolved interferometrically during reconstruction. The interferogram’s contours can then be analyzed for species concentration levels. One significant feature of RHI is its ability to uniquely create interferograms using species specific phase changes. Phase changes resulting from optical aberrations, thermal or pressure instabilities, or background species are subtracted out from the interferogram during reconstruction.
Use of a Fiber Optic-Based, Laser-Induced Breakdown Spectroscopy (LIBS) Probe for In Situ Determination of Metals in Soils
Authors: Theriault Gregory A. , Lieberman Stephen H. , Bodensteiner Scott
Published: February 2023

A Cone Penetrometer-deployed fiber optic probe for the in-situ assessment of metal contamination of soil is described. In this talk both system design features and field-testing results will be discussed.
In-Situ Measurements of Combustion Species Using Near-IR Diode Laser Sensors
Authors: Allen Mark G. , Upschulte Bernard L. , Sonnenfroh David M.
Published: February 2023

The rapid improvements in room-temperature diode laser technology for communications and data storage applications has given rise to a entirely new class of potential optical sensors for species composition and gasdynamic parameter measurements. These sensors are finding widespread application to chemical processing, environmental monitoring, and, increasingly, aerodynamic and propulsion needs. High quality devices are now commercially available in a number of discrete spectral windows between 630 nm and 2.0 μm. For aerodynamic and propulsion applications, most activity to date has focussed on O2-based measurements using 763 nm AlGaAs lasers and H2O-based measurements using 1.31 to 1.39 μm InGaAsP lasers. These devices are characterized by a rapid time response, extreme sensitivity, and opto-mechanical robustness consistent with practical industrial installations.
The Reality of the Moon Illusion
Authors: Wolbarsht Myron L. , Lockhead Gregory R.
Published: February 2023

The illusory (small) moon depends on information inducing empty field myopia: not optics; color; horizon, eye, and/or body position; or other factors.
Stars and Planets in the Daytime Sky
Authors: Ling Alister
Published: February 2023

An observer using normal polarizing sunglasses can readily see Jupiter in the daytime sky when it is located within the polarization band. This is contrary to the statements made by G.P. Konnen in "Polarized Light in Nature." In fact, the difference between unpolarized and polarized views is quite dramatic.
Beetles, Bubbles, and Butterflies: Iridescence in Nature
Authors: Greenler Robert G.
Published: February 2023

Most of the colors seen in Nature result from the selective absorption and scattering of light by pigments. However there are some that result from the interference or diffraction of light waves by physical structures that have dimensions comparable with the wavelength of light. This presentation given an introduction to a wide variety of such effects including the iridescence in bird feathers, butterfly wings, and beetle shells; the mother-of-pearl colors in oyster and clam shells; the colors of sun-lit spider webs; and the metallic-appearing spots on the chrysalis of a monarch butterfly. Many beautiful examples of iridescence will be shown — with specimen and with photograph. In some cases, explanations of the color-producing mechanisms are known, but in the majority of cases, questions will be posed to which the answers are not known.
Investigation into the Scattering of Light by Human Hair
Authors: Bustard Helen K. , Smith R.W.
Published: February 2023

The scattering of light by human hair depends on both the structure of the hair and how the hair has been treated. As hair grows it is naturally subjected to damage by grooming and the environment. A typical hair is a roughly cylindrical structure approximately 70 microns in diameter. It consists of three distinct layers of keratin material: the medulla, cortex and the cuticle (or scale layer). The outer layer (cuticle) is a laminar structure composed of between 5 and 10 elongated cells, which provide a radial mechanical constraint on the cortex. A schematic view of this arrangement is presented in figure 1.
Viewing Half-Rainbows in a Prism using Diffuse White Light
Authors: Edgerton Robert F.
Published: February 2023

A prism placed on a well-illuminated horizontal piece of white paper can be viewed at different angles (Figure 1). When the viewing angle is high, one sees the transmitted light coming through the air-glass interface from the horizontal white paper. One can also see a weak reflection off the glass-air interface that superimposes the vertical object's image as well. If the vertical object is a black piece of paper this overlapping image can be made negligible in intensity. When the viewing angle is low, the light from the horizontal white paper cannot get to your eye, and only the reflected light from the vertical object is viewed. If this is a black screen then very little light is observed at that viewing angle. At the boundary between these two types of viewing, one observes an arc of color - a red arc that blends into a red-orange and bright yellow band before fading into pink and, finally, white. This attractive arc of color is reminiscent of a rainbow, and appears as a half-rainbow. When the white and black paper screens are exchanged, an arc of color is observed that is blue. The blue arc is not as high contrast as the red one and is bordered by a bright green arc that blends into a bluish white and, finally, white. This is the complimentary half-rainbow.
Venus Crystals and Halo Scattering
Authors: Können G.P. , Tinbergen J.
Published: February 2023

As can easily be seen with a polarizer, halo scattering by birefringent crystals gives rise to a strong peak in the polarization, concentrated in a narrow scattering angular range. This peak can easily be observed in ice crystal halos by the naked eye, equipped with a polarizer. It becomes immediately evident that the inner edge of a parhelion is completely polarized. This narrow polarization peak provides a sensitive diagnostic for detecting birefringent crystals in their often complicated atmosphere and it may be worthwhile to scan their polarization with high angular resolution to look for their halos. However, as the halo angles for bright halos are considerably less than 90°, one has to be at the far side of the planet. For Earth-bound observers, this is only possible for the inner planets, of which only Venus has an atmosphere.
Rainbows in The Indian Rock Art of Desert Western America
Authors: Sassen Kenneth
Published: February 2023

Scattered throughout the Great Basin and the drainages of the upper Colorado and Rio Grande Rivers is a legacy of prehistoric and historic (i.e., post-Spanish contact) Indian rock art that represents a several-thousand year old tradition of creating culturally meaningful images on stone. Depending on the nature of the stone surface, and also on the intent of the "artist", the images were either pecked, scratched or abraded into the stone, or painted on suitably smooth and protected cliff walls. The terms petroglyph and pictograph are respectively applied to these two basic techniques. Petroglyphs typically were pecked through the dark patina coating, which slowly develops on many rock surfaces in the desert environment, to disclose the lighter colored rock beneath, whereas mineral-based pigments were employed in making pictographs. Among the inventory of images are human-like (anthropomorphic) and animal (zoomorphic) forms, as well as a large variety of abstract elements and more esoteric designs that are subject to various interpretations. With time, the rock art of the Great Basin area generally evolved from the abstract to the more representational, although many abstract designs remained popular (i.e., meaningful) throughout the area's long history.
Visual Perception in Challenging Environments
Authors: Owens D. Alfred
Published: February 2023

Scientific investigation of visual perception began with early astronomy and physics and continues today as an interdisciplinary field with strong ties to psychology, physiology, and computer science.
Blue Shadows
Authors: Churma Michael E.
Published: February 2023

As most artists and careful observers know, shadows seen outside are not just a darker portion of the surrounding environment; they often have a definite bluish appearance.
Color Simulation of the Size-dependent Features of Rainbows
Authors: Brandt R. K. , Greenler Robert
Published: February 2023

We frequently see reports of rainbows that don't appear to display the "usual" sequence of colors. Bows are reported with some colors missing and others are described with certain colors enhanced in brightness. We understand some of these reports qualitatively. For example, the red rainbow results from atmospheric scattering that selectively removes the blue end of the spectrum from the sunlight incident on the raindrops. The usual explanation for other reported variations is that the appearance of the bow depends somehow on the droplet size. This is a kind of shoulder-shrugging explanation that requires no understanding from the explainer and gives no insight to the listener. We do understand something about the transition to the white rainbow as the droplet size becomes very small but have no intuitive understanding, for example, of a violet rainbow.
Thirty years observing and documenting sky optical phenomena
Authors: Verschure Peter-Paul Hattinga
Published: February 2023

The Netherlands have a long tradition in sky optical phenomena observing. Since 1890 for more than 75 years all observations have been collected, processed and brought together by the Royal Netherlands Meteorological Institute in the famous annual series 'Onweders, Optische Verschijnselen enz. in Nederland naar vrijwillige waarnemingen' ('Thunderstorms, sky optical phenomena etc in The Netherlands from voluntary observations'). The observations were gathered by volunteer observers with pleasure in seeing and studying sky phenomena. They were accepted and stimulated by the annual publication of their observations by the Meteorological Institute. The observers described their findings on special printed postal cards. In that way a network was active for decades by which efforts lots of material has been collected. Dutch observations from this period are referred to in several important publications in the first half of the 20th century.
An Atlas of Refraction Halos
Authors: Können Günther P. , Tape Walter
Published: February 2023

We will introduce a natural halo parameter S
w
that leads to the classification of all halos due to refraction in preferentially oriented ice crystals. We are motivated by a desire to understand the many exotic halos that could conceivably arise in pyramidal crystals or in spinning crystals. Given sufficient space, we would first construct an atlas of all possible (refraction) halos, making no assumptions about real crystal shapes and only a minimal assumption about real crystal orientations. We would then show how real halos, or at least plausible halos, with their specific crystal shapes and orientations, fit into the atlas. In fact, however, in the space allotted we can only present two pages of the atlas and indicate the locations of a few more or less familiar halos.
Getting an Atmospheric Temperature Profile from the Setting Sun
Authors: Bruton Dan
Published: February 2023

Summary not available.