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A spectroscopic stack monitoring system for the measurement of noble gasses discharged from medical isotope production facility and nuclear power plant stacks has been designed and a prototype constructed. The prototype is based on a Marinelli beaker style HPGe measurement operating in a continuous acquisition mode. Continuous acquisition is accomplished with novel software and hardware which allows for unattended acquisition, analysis, and storage of data over multiple workflow definitions. As a direct result of the multiple averaging times and the use of the transistor reset preamplifier, the dynamic range of the system covers nearly 8 orders of magnitude.

We correlate the focusing dynamics of 50 femtosecond (fs) laser radiation as it interacts with a silicon sample to laser-induced breakdown spectroscopy (LIBS) signal strength. Presented are concentric ring-shaped variations in the electric field in the prefocus region due to lens aberrations and nonsymmetry between the prefocus and post-focus beam profile as a result of continuum generation, occurring around the focus. Experimental results show different signal trends for both atmospheric and vacuum conditions, attributed to the existence of a continuum for the former. Lens aberrations effects on the LIBS signal strength are investigated using a plano-convex spherical lens and an aspherized achromatic lens. High-resolution scanning electron micrographs of the silicon surface after ablation, along with theoretical simulations, reveal the electric field patterns near the focus. The research results contribute to fundamental understanding of the basic physics of ultrashort, femtosecond laser radiation interacting with materials.

The formation of nanoparticle covered pyramidal structures using femtosecond laser pulses with a fluence near the ablation threshold is reported for the first time. These unique structures form through a combination of preferential ablation of flat regions around the pyramids and redeposition of nanoparticles created during the ablation process. The structures are demonstrated on nickel and stainless steel 316. When produced by rastering Gaussian pulses across the sample, layers of nanoparticles join together by sintering to form unique layered shells.

Objective Compare effect of extrinsic materials and radiation dose levels on image processing times for model-based iterative reconstruction (MBIR) in computed tomography. Methods Chest computed tomography scans were performed on a phantom with three different levels of clothing and medical equipment at three tube current settings to reflect differing radiation doses. Reconstruction time for MBIR was recorded, and objective image quality was assessed via noise within the phantom mediastinum. Reconstruction time and noise were compared between scans, with noise also compared between MBIR and matching filtered back projection (FBP) images. Results Reconstruction times (minutes:seconds) ranged from 37:31 to 42:24. Times were generally faster with less extrinsic material and prolonged among high-dose scans when materials were present. On both the MBIR and FBP images, noise levels were improved with higher radiation doses, although for MBIR only minimally, and the relative effect of extrinsic materials at a given radiation dose was also minimal. In addition, noise was better with MBIR than FBP reconstruction for all conditions. Conclusions Typical MBIR reconstruction times are faster with less extrinsic materials in the scan field of views, and removing extraneous blankets or medical devices could positively affect workflow over the course of the day. In addition, MBIR reconstruction times are also shorter when using lower dose protocols in situations requiring extensive materials.

Nondestructive three-dimensional imaging of femtosecond laser-written buried structures is demonstrated using optical coherence microscopy providing lateral and depth resolution on a micron scale. This high speed technique, which requires no sample preparation, enables the visualization of volumetric structural modification created deep in transparent dielectric medium with high signal/noise contrast. Images of buried void structures with dimensions as large as 190 μm in length were obtained without shadowing effects impugning the image fidelity.

In this paper, we review ongoing progress in the development of novel on-chip, low loss planar molecular sensors that address the emerging need in the field of biochemical sensing. Chalcogenide glasses were identified as the material of choice for sensing due to their wide infrared transparency window. We report the details of manufacturing processes used to realize novel high-index-contrast, compact micro-disk resonators. Our findings demonstrate that our device can operate in dual modalities, for detection of the infrared optical absorption of a binding event using cavity enhanced spectroscopy, or sensing refractive index change due to surface molecular binding and extracting micro-structural evolution information via cavity enhanced refractometry.

In this paper, we report results of a systematic study to evaluate the relationship between compositional variation and the photo-response of Gallium containing sulfo-selenide glasses upon IR femtosecond laser exposure. We show that IR femtosecond laser irradiation in this system results in near-surface photo-expansion, which based on micro-Raman spectroscopy, has been related to an increased connection of GeS 4 units to form corner sharing GeS 4/2 units with a concurrent formation of S–S bridges. The lower surface photo-expansion of the Ga- containing sulfide and sulfo-selenide glasses compared to that of the Ga-free sulfide and sulfo-selenide glasses has been related to the presence of GaS 4 and Se–Se isolated units in the germanate glass network which are expected to restrict the connection between GeS 4 units during laser exposure. Such mechanistic understanding of material modification opens the pathway towards the laser writing of active photonic devices in the near-surface of these glasses.

This paper reviews ongoing progress in exploring the mechanistic origins of photoinduced structural modification in chalcogenide glasses (ChGs). These findings, reported by groups at the University of Central Florida, Clemson University, and throughout other research programs within the United States and abroad, have examined the relationship between the network modification and other photoresponse of IR glasses upon exposure to near-infrared (NIR) femtosecond laser exposure. Contained is a review on the principles of femtosecond laser writing in glass, the photoinduced phenomena, and a summary of the main models predicting photoinduced material response. We compare the photoresponse of As- and Ge-based films, taken as example, following NIR femtosecond laser irradiation that results in near-surface photoexpansion and an increase or decrease of the refractive index, respectively. This difference in photoresponse has been related to the "layered" network of the As-based glass that leads to the breaking and formation of bonds during laser exposure as compared to the 3-D network of Ge-based glass that leads only to a modification of the bond arrangements. Last, an explanation of the need to control the photoresponse of ChGs by aging, changing the glass thermal history, adding modifiers, or replacing the anions forming the network is discussed.

Directional and ratchet-like functionalized surfaces can induce liquid transport without the use of an external force. In this paper, we investigate the motion of liquid droplets near the Leidenfrost temperature on functionalized self-assembled asymmetric microstructured surfaces. The surfaces, which have angled microstructures, display unidirectional properties. The surfaces are fabricated on stainless steel through the use of a femtosecond laser-assisted process. Through this process, mound-like microstructures are formed through a combination of material ablation, fluid flow, and material redeposition. In order to achieve the asymmetry of the microstructures, the femtosecond laser is directed at an angle with respect to the sample surface. Two surfaces with microstructures angled at 45° and 10° with respect to the surface normal were fabricated. Droplet experiments were carried out with deionized water and a leveled hot plate to characterize the directional and self-propelling properties of the surfaces. It was found that the droplet motion direction is opposite of that for a surface with conventional ratchet microstructures reported in the literature. The new finding could not be explained by the widely accepted mechanism of asymmetric vapor flow. A new mechanism for a self-propelled droplet on asymmetric three-dimensional self-assembled microstructured surfaces is proposed.

In this paper, an experimental investigation of the effects of droplet diameters on the Leidenfrost temperature and its shifts has been carried out. Tests were conducted on a 304 stainless steel polished surface and a stainless steel surface which was processed by a femtosecond laser to form Above Surface Growth (ASG) nano/microstructures. To determine the Leidenfrost temperatures, the droplet lifetime method was employed for both the polished and processed surfaces. A precision dropper was used to vary the size of droplets from 1.5 to 4 millimeters. The Leidenfrost temperature was shown to display shifts as high as 85 °C on the processed surface over the range of droplet sizes, as opposed to a 45 °C shift on the polished surface. The difference between the shifts was attributed to the nature of the force balance between dynamic pressure of droplets and vapor pressure of the insulating vapor layer.

There are a growing number of unique self-organized micro/nanostructures created using femtosecond laser surface processing that have been demonstrated. Although researchers have provided insight into the formation processes for distinctive morphologies on specific materials, there is a need for a broader understanding of the physics behind the formation of a wide range of morphologies and what parameters affect their formation. In this work, the formation processes for mound structures on 316 stainless steel (SS) with growth above the original sample surface are studied. The formation process for the structures on 316 SS is compared to similar structures formed on nickel using the same technique. The structures are formed using 800 nm, 50 fs laser pulses, and are self-organized, meaning the structure dimensions are much smaller than the spot size of the pulses used to create them. The formation dynamics were studied using a stop-motion scanning electron microscope (SEM) technique, where the same location of an irradiated sample was imaged in the SEM at various pulse counts. The result is a series of images showing the developmental progress with increasing pulse counts. The structures form through a combination of fluid flow of the surface melt that results after irradiation, preferential ablation of the center of the pits between structures, and material/nanoparticle redeposition.

We describe the evolution of laser damage spots on bulk nickel generated by multipulse femtosecond laser irradiation with a 100 μm x 100 μm square flat-top beam profile as a function of the laser fluence and the number of pulses incident on the target. This large-area irradiation simulates conditions associated with the interaction of femtosecond laser pulses on a remote target. The larger area laser damage sites are characterized either by a series of self-organized surface structures with micro- and nanoscale features or a deep circular pit rather than a crater that mirrors the beam profile. Furthermore, the ablation rate of the deepest feature sharply increases above a laser fluence of 2 J/cm2; this increase is associated with the creation of a deep circular ablation pit generated during ablation with the first few pulses on the sample that continuously grows upon multipulse irradiation due to the focusing of incident laser energy into the pit by the sloped pit surfaces.

The formation of self-organized micro- and nano-structured surfaces on nickel via both above surface growth (ASG) and below surface growth (BSG) mechanisms using femtosecond laser pulse illumination is reported. Detailed stepped growth experiments demonstrate that conical mound-shaped surface structure development is characterized by a balance of growth mechanisms including scattering from surface structures and geometric effects causing preferential ablation of the valleys, flow of the surface melt, and redeposition of ablated material; all of which are influenced by the laser fluence and the number of laser shots on the sample. BSG-mound formation is dominated by scattering, while ASG-mound formation is dominated by material flow and redeposition. This is the first demonstration to our knowledge of the use of femtosecond laser pulses to fabricate metallic surface structures that rise above the original surface. These results are useful in understanding the details of multi-pulse femtosecond laser interaction with metals.

The expression level of proteins governing the electrical excitability of and conduction within ventricular myocardium are known to vary as a function of distance through the heart wall. The expression patterns of a subset of these proteins are altered in disease. Precise measurement of such patterns is therefore essential to understanding structure-function relationships within the heart in health and disease. Here, we report a new experimental approach using reverse-phase protein microarrays to map the left ventricular transmural proteome. This approach can yield submillimeter spatial resolution, and when coupled with the method of array microenvironment normalization, reduces nonbiological components of variability to ∼10% of overall study variability. In addition, the experimental design provides sufficient statistical power to detect small, yet potentially biologically significant expression changes on the order of 1.1-fold. The usefulness of this technique is demonstrated by mapping the transmural expression of Serca2a in the left ventricle of 12 canine hearts, each in one of three states: normal, dyssynchronous heart failure, and dyssynchronous heart failure followed by cardiac resynchronization therapy. We confirm the existence of a 40% transmural gradient (epi>endo) of Serca2a, and demonstrate the ability of this technique to yield highly significant transmural expression differences within each individual heart.

In recent years, a major interest in surface as well as bulk property modification of semiconductors using laser irradiation has developed. A.Kar et al. [1][2] and E.Mazur et al. [3] have shown introduction and control of dopants by long-pulse laser irradiation and increased absorption due to femtosecond irradiation respectively. With the development of mid-IR sources, a new avenue of irradiation can be established in a spectral region where the semiconductor material is highly transparent to the laser radiation. The characterization of the light-matter-interaction in this regime is of major interest. We will present a study on GaAs and its property changes due to pulsed laser irradiation ranging from the visible to the mid-IR region of the spectrum. Long-pulse as well as ultra-short pulse radiation is used to modify the material. Parameters such as ablation threshold, radiation penetration depth and thermal diffusion will be discussed.

Femtosecond laser direct writing (FLDW) has been widely employed to create volumetric structures in transparent materials that are applicable as various photonic devices such as active and passive waveguides, couplers, gratings, and diffractive optical elements (DOEs). The advantages of fabrication of volumetric DOEs using FLDW include not only the ability to produce embedded 3D structures but also a simple fabrication scheme, ease of customization, and a clean process. DOE fabrication techniques using FLDW are presented as well as the characterization of laserwritten DOEs by various methods such as diffraction efficiency measurement. Fresnel zone plates were fabricated in oxide glasses using various femtosecond laser systems in high and low repetition rate regimes. The diffraction efficiency as functions of fabrication parameters was measured to investigate the dependence on the different fabrication parameters such as repetition rate and laser dose. Furthermore, several integration schemes of DOE with other photonic structures are demonstrated for compact photonic device fabrication.

International audience; In this paper, we report the spatially controlled dissolution of silver nanoparticles in irradiated SiO2 sol–gel films. The Ag nanoparticles have been formed in the sol–gel solution before the film deposition by adding Triton and ascorbic acid and also after the film deposition using a heat treatment at 700 °C for few minutes or at 550 °C for 6 h in reducing atmosphere. Using a spectrometer, a new view white light interferometer and a micro-thermal analyzer, we demonstrate that the silver nanoparticles can be dissolved using a continuous black ray UV lamp or with a near-infrared (NIR) femtosecond laser, due to a significantly increase in the local temperature. We confirm that the micro-thermal analyzer can be used as a new tool to study the dissolution of metallic nanoparticles in thin film if located at the surface of the films.

Optical coherence microscopy (OCM) is used to image femtosecond laser direct written buried structures created within transparent media. Volumetric structures of optical damage and laser-induced refractive index change were produced in fused silica and borosilicate glass, respectively. Noninvasive 3D imaging of the structures was successfully demonstrated by a custom built OCM. High signal to noise ratio was obtained since the optical glasses have high transparency at the probe wavelength centered at 800 nm.

Femtosecond Laser Materials Processing (FLMP) is an active area of research for its superior processing quality compared to conventional laser processing with nano- and picosecond (ps) pulses. Advances in femtosecond (fs) laser technology including the development of high repetition rate fiber-based systems are now making FLMP more industrially viable by increasing reliability and throughput. The Laser Plasma Laboratory (LPL) within the Townes Laser Institute at the University of Central Florida is developing FLMP solutions towards the fabrication of micro-devices such as diffractive optical elements, photonic circuits, and micro-fluidic devices. Furthermore, we are investigating the use of FLMP to alter the optical or chemical properties of a material. In this talk, we present recent research activities involving FLMP by LPL including applications in biochemistry, photonics and optoelectronics.Femtosecond Laser Materials Processing (FLMP) is an active area of research for its superior processing quality compared to conventional laser processing with nano- and picosecond (ps) pulses. Advances in femtosecond (fs) laser technology including the development of high repetition rate fiber-based systems are now making FLMP more industrially viable by increasing reliability and throughput. The Laser Plasma Laboratory (LPL) within the Townes Laser Institute at the University of Central Florida is developing FLMP solutions towards the fabrication of micro-devices such as diffractive optical elements, photonic circuits, and micro-fluidic devices. Furthermore, we are investigating the use of FLMP to alter the optical or chemical properties of a material. In this talk, we present recent research activities involving FLMP by LPL including applications in biochemistry, photonics and optoelectronics.

Ternary chalcogenide glass films from identical parent bulk glasses were prepared by thermal evaporation (TE) and pulsed laser deposition (PLD) and subjected to 810-nm femtosecond laser exposure at both kHz and MHz repetition rates. The exposure-induced modification on the glass film's surface profile, refractive index, and structural properties were shown to be a function of laser irradiance, the number of laser pulses per focal spot, and repetition rate. Film response was shown to be related to deposition technique-related density and the number of glass bonds within the irradiated focal volume. The induced changes resulted from a reduction in glass network connectivity among GeS(4/2), GeS(4), S-S and S(3)Ge-S-GeS(3) units.

Objective Weight gain is a side effect of glucocorticoid (GC) use, but the natural history and health implications of changes in weight that occur during the treatment of inflammatory disease are not understood. Methods We evaluated data from the Wegener's Granulomatosis Etanercept Trial. Patients were categorized according to clinical outcome at 1 year: remission (no disease flares), single flare, or multiple flares. Risk factors for gaining ≥10 kg were examined in multivariate models. Results Weights at baseline and 1 year were available for 157 (93%) of the 168 patients analyzed. During year 1, the mean cumulative prednisone dosage in the multiple flares subgroup was 7.9 gm, compared with 6.0 gm and 3.9 gm in the single flare and remission subgroups, respectively (P < 0.001). Patients in these subgroups gained an average of 2.6 kg, 4.1 kg, and 5.8 kg, respectively (P = 0.005). Weight gain did not correlate with cumulative GC dose (R = 0.10, P = 0.25). Thirty-five patients (22.3%) gained and maintained ≥10 kg in the first year. New diagnosis of Wegener's granulomatosis at baseline was an independent predictor of gaining ≥10 kg at 1 year (odds ratio 19.7, 95% confidence interval 2.4–162.6, P = 0.006). Among the 78 patients in the remission subgroup, 40 sustained remissions through the 2-year time point. For these 40 patients, the mean weight gained at year 1 did not regress by the end of year 2, despite the absence of continued GC use. Conclusion Disease control was associated with lower cumulative GC doses but greater weight gain. More than one-fifth of patients gained >10 kg in the first year of treatment. The quantity of weight gained by patients during treatment has potential future health implications.

We have demonstrated nondestructive 3D imaging of the femtosecond laser written 3D structures of both index change and optical breakdown within fused silica by using the optical coherence microscopy providing high lateral and depth resolution.

We present the microstructuring of bulk and film chalcogenide glasses using IR femtosecond laser exposure and photolithography for molecular sensing.

Fs MR exposure has been used to induce refractive index change in bulks in the As0.42-x-yGexSbyS0.58 system. Photo- induced Deltan has been investigated as a function of laser dose by measuring diffraction efficiency of buried gratings.

An in-situ μ-Raman spectroscope is presented. The possibilities of obtaining Raman spectra at various pump frequencies without an expensive ultra-notch filter is discussed, including measurements of various materials like chalcogenide glasses, telluride glasses and semiconductors.

Refractive index modifications of film Ge0.23Sb0.07S0.7 induced by 800 nm femtosecond laser irradiation are studied for laser repetition rates of 1 kHz and 80 MHz. Measurements are taken using an interferometric method and analysis of the transmission spectra.

Negotiation is the process by which two or more parties exchange goods or services and attempt to agree upon an exchange rate for them (Wall, 1985; Wall/Blum, 1991). In the negotiation process, each side exercises and articulates its influence in an effort to accomplish its own objectives through its interaction with the other party (Bacharach/Lawler, 1981; Dansereau/Graen/Haga, 1975; Greenhalgh/Nelsin/Gilkey, 1985; Kipnis/Schmidt, 1983). As one of the basic processes of human behaviour, negotiation is something we all do on a daily basis. Negotiation is also widely used in labor-management relations, in business agreements such as mergers and sales, in international relations, and in international business (King/Hinson, 1994). As the world economy becomes more and more globalised, people from different cultures are becoming more frequently engaged in negotiation with one another. Thus, an understanding of the negotiation process and the impact of culture on it are essential to anyone who works with or through other people to accomplish objectives in many different situations (Le-wicki/Litterer/Saunders/Minton, 1994a).

This paper reviews ongoing progress in the design and fabrication of new, on-chip, low loss planar molecular sensors. We report the details of device design, material selection and manufacturing processes used to realise high-index-contrast (HIC), compact micro-disk resonators. These structures have been fabricated in thermally evaporated As- and Ge-based chalcogenide glass films with PDMS (polydimethylsiloxane) micro-fluidic channels using standard UV lithography. Discussed are findings that demonstrate that our novel chalcogenide-based micro-fluidic device can be used as highly sensitive refractive index sensors.

Chalcogenide glasses are widely used in device applications which capitalize on their unique linear and nonlinear optical properties, and infrared transparency. The role of the glass’ photosensitivity in device fabrication and eventual use, is discussed.