Holographic lactate sensor

Measurement of blood l-lactate is used to assess and monitor exercise performance in sports medicine. This report describes the initial development of a holographic sensor, which employs a synthetic receptor, to enable the selective and continuous real-time measurement of l-lactate for eventual in vivo application. Three boronic acid-based receptors have been synthesized, integrated into thin acrylamide hydrogel films, and then subsequently transformed into holographic sensors. Changes in the replay wavelength of the sensors were used to characterize the swelling behavior of the matrix as a function of l-lactate concentration. It was found that the incorporation of 3-acrylamidophenyl boronic acid into an acrylamide hydrogel produced the largest response toward l-lactate. The effects of hydrogel composition, fluctuating l-lactate concentrations, and the response of potential interfering agents to the sensor have been investigated.     

Quartz sensor for water absorption measurement in glass-fiberresins

The humidity sensor using the sensitive capacitive-dependent crystal is described. Presented is the probe sensitivity (dependence of df on the dCx). In addition, the new idea of excitation of the entire humidity sensor with stochastic test signals is described, and the humidity surface-measuring method is given. The latter includes the influence of test signals on the weighting function uncertainty. The results of the air-humidity measurement and water absorption measurement in glass-fiber resins are shown experimentally. The uncertainty of the surface humidity measurement is less than 0.1% (T=15-25 °C and air-humidity=50 to 98%)     

Sol-gel-based, planar waveguide sensor for water vapor

A water vapor sensor based on a combination of sol-gel processing and planar optical waveguide technologies has been developed. The indicator erythrosin B was entrapped in a thin sol-gel film (thickness ～100 nm) prepared from methyltriethoxysilane, dimethyldiethoxysilane, and tetraethoxysilane. This dye exhibits an increase in absorbance in the presence of liquid or gaseous water. The sol-gel layer containing the dye was deposited onto a sol-gel-derived, single-mode planar waveguide. Outcoupled light intensity measurements (at 514.5 nm) over a range of water vapor concentrations (in a nitrogen gas stream) yielded a response over a wide range of relative humidity (<1-～70%) at room temperature. Response and reversal times were less than 1 min, which may make this sensor attractive for real-time monitoring applications.     

The dilution of flammable polar solvents by water for safe disposal

The theory predicting the ‘Closed-up’ flashpoint of polar solvents diluted with water is used to estimate the quantities of water required to render safe spillages of these solvents.     

Holographic Beam-splitter in High Luminosity Holographic Recording

A holographic recording method in diffuse light is proposed. This method essentially allows to limit the losses of energy. In addition it is well adapted to the transmission and to the processing of holographic information by means of optic and electronic systems.     

Evanescent fiber-optic chemical sensor for monitoring volatile organic compounds in water

The transport of trichloroethylene, 1,1,1-trichloroethane, and toluene in aqueous solutions through a polydimethylsiloxane film was modeled using a Fickian diffusion model to fit data obtained from an evanescent fiber-optic chemical sensor (EFOCS). The resultant diffusion coefficients for these analytes were respectively 3 × 10(-)(7), 5 × 10(-)(7), and 1 × 10(-)(7) cm(2)/s. Inclusion of an interfacial conductance term, defined as the ratio of the mass transport coefficient across the polymer surface and the analyte diffusion coefficient in the polymer, was required to accurately model the data. It was determined that the interfacial conductance terms were generally of the same order of magnitude for the analytes examined, suggesting a constant transport mechanism for the analytes. Linear chemometric algorithms were used to model the EFOCS response to aqueous mixtures of the three analytes with individual analyte concentrations between 20 and 300 ppm. Both partial least-squares and principal component regression algorithms performed comparably on the calibration sets, with cross-validated root-mean-squared errors of prediction for trichloroethylene, 1,1,1-trichloroethane, and toluene of approximately 26, 29, and 22 ppm, respectively. The resultant prediction model was then used to determine analyte concentrations in an independent data set with comparable precision.     

Interfacial stability of graphene-based surfaces in water and organic solvents

The mass production of graphene and graphene oxide (GO) is essential for its use in commercial products. To improve its processing in the solution, dispersion behavior of graphene-based materials and their colloidal stability must be further understood. This study used all-atom molecular dynamics simulations to understand how electrostatics, van der Waals interactions, and hydrogen bonding affect the exfoliation and stability of three-layered graphene as a function of oxidation and solvent. Water, methanol, and ethanol were chosen as solvents due to their various dispersion behaviors. Our study indicated that (1) both surface oxidation level and solvent type can heavily influence the stability and (2) a decrease in interlayer vdW interactions, an increase in GO–solvent electrostatic interactions, and an increase in GO–solvent hydrogen bonding are important factors that can facilitate the dissolution of GO.     

Fluorescent polymer sensor array for detection and discrimination of explosives in water

A fluorescent polymer sensor array (FPSA) was made from commercially available fluorescent polymers coated onto glass beads and was tested to assess the ability of the array to discriminate between different analytes in aqueous solution. The array was challenged with exposures to 17 different analytes, including the explosives trinitrotoluene (TNT), tetryl, and RDX, various explosive-related compounds (ERCs), and nonexplosive electron-withdrawing compounds (EWCs). The array exhibited a natural selectivity toward EWCs, while the non-electron-withdrawing explosive 1,3,5-trinitroperhydro-1,3,5-triazine (RDX) produced no response. Response signatures were visualized by principal component analysis (PCA), and classified by linear discriminant analysis (LDA). RDX produced the same response signature as the sampled blanks and was classified accordingly. The array exhibited excellent discrimination toward all other compounds, with the exception of the isomers of nitrotoluene and aminodinitrotoluene. Of particular note was the ability of the array to discriminate between the three isomers of dinitrobenzene. The natural selectivity of the FPSA toward EWCs, plus the ability of the FPSA to discriminate between different EWCs, could be used to design a sensor with a low false alarm rate and an excellent ability to discriminate between explosives and explosive-related compounds.     

Absorption of water into organic solvents used for electrochemistry under conventional operating conditions

Many solvents used for electrochemistry can be dried to <1 × 10(-3) M water content by storing the solvents over 3 ? molecular sieves in a nitrogen or argon atmosphere. However, as soon as the solvents are placed in an electrochemical cell, the water content increases significantly. Karl Fischer coulometric titrations were conducted on several predried solvents commonly used for electrochemistry (acetonitrile, dichloromethane, N,N-dimethylformamide, and dimethyl sulfoxide) in a controlled-humidity environment (30%, 50%, and 70% relative humidity) to determine the rate of moisture uptake into the organic solvents when used under typical electrochemical conditions (either in an electrochemical cell under a nitrogen atmosphere or in an electrochemical cell directly exposed to the atmosphere). The results in this study give guidelines for estimating the water content of organic solvents under conventional electrochemical operating conditions.     

Holographic interferometry of oil films and droplets in water with a single-beam mirror-type scheme

Application of single-beam reflective laser optical interferometry for oil films and droplets in water detection and characterization is discussed. Oil films can be detected by the appearance of characteristic interference patterns. Analytical expressions describing intensity distribution in these interference patterns allow determination of oil film thickness, size of oil droplets, and distance to the oil film from the observation plane. Results from these analyses indicate that oil spill aging and breakup can be monitored in real time by analyzing time-dependent holographic fringe patterns. Interferometric methods of oil spill detection and characterization can be automated using digital holography with three-dimensional reconstruction of the time-changing oil spill topography. In this effort, the interferometric methods were applied to samples from Chevron oil and British Petroleum MC252 oil obtained during the Deep Water Horizon oil spill in the Gulf of Mexico.     

Holographic diffraction gratings for flat-field spectrometers

Abstract

Aberration properties of gratings for a number of flat-field spectrometers, recorded in different optical mountings are discussed. Spot diagrams and spread functions achieved using mathematical models of spectrometers with different gratings are presented.     

Holographic interference filters for infrared communications

We demonstrate that high-quality interference filters for the wavelength range 1300-1600 nm can be holographically fabricated in DuPont HRF-800X001 photopolymer material by use of visible laser illumination. We also summarize a chain-matrix technique, which we call thin-film decomposition, that is useful for modeling multilayer films with an arbitrary index profile n(z). We use the thin-film-decomposition technique to create design curves that allow one to choose the proper exposure angle and film thickness with which to fabricate a holographic interference filter with a desired transmission efficiency and bandwidth at a particular wavelength. These curves are of general utility and are not confined to any particular holographic recording medium. Excellent agreement between theory and experiment is found.     

Reflection Holographic Gratings for Optical Filtering

From the coupled wave theory the transfer function for phase-reflection holographic gratings is obtained with a view to their application as Fourier filters in the object space. After experimental confirmation, different resonance conditions are presented and suitable approximations are discussed. For resonance at normal incidence, a simplified expression is given for the field complex amplitude transmittance as an explicit function of spatial frequency.     

Holographic screening method for microelastic solids

An experimental method is presented for the rapid evaluation of structured solids with microelastic degrees of freedom associated with the microstructure. By contrast with earlier methods based on size effect studies, the present method makes use of a single specimen subjected to holographic interferometry. Results are presented for polymethyl methacrylate and for a dense polyurethane foam, which in previous studies were demonstrated to behave, respectively, as classically elastic and Cosserat solids.