Environmental quality

The potential use of space systems to help determine the current state of air, water, and land environments was examined; the effects of man's activities on these parameters were also examined. Data are limited to pollutants introduced into the major environmental media, environmental changes manifested by such pollutants, and the effectiveness of abatement and control methods. Data also cover land quality as related to land use and public health

Atmospheric aerosols: Their Optical Properties and Effects

Measured properties of atmospheric aerosol particles are presented. These include aerosol size frequency distribution and complex retractive index. The optical properties of aerosols are computed based on the presuppositions of thermodynamic equilibrium and of Mie-theory

Radiative properties of aerosols in Saharan dust outbreaks using ground-based and satellite data: applications to radiative forcing

We report on measurements of atmospheric transmission (ATT) and aerosol optical depth (AODT) made at three wavelengths (368, 500, and 778 nm) with a spectroradiometer placed on Tenerife (28.5°N, 16.3°W), Canary Islands. Using the National Oceanic and Atmospheric Administration (NOAA) advanced very high resolution radiometer (AVHRR) channel 1, we also measured the aerosol optical depth (AODS) and albedo over a region of the North Atlantic Ocean extending from 15°–35°N to 12°–25°W. We observe large changes in ATT and AODT when dust outbreaks pass over this region. Using all these data, we derive the asymmetry factor (g), the single-scattering albedo (ω), and the local mean AODT and we compute the direct radiative forcing ΔF attributable to mineral dust. The local radiative forcing obtained is over the ocean ΔF = −9.7 W/m2 and for the land ΔF = −4.5 W/m2 with an error of ±25%. Extending these results to global-scale averages, we obtain values of ΔF of −1.22 W/m2 over the ocean and −0.57 W/m2 over land. The forcings attributable to dust are comparable in magnitude to those reported in the literature for anthropogenic sulphate and for biomass burning aerosols.We wish to thank the Gobierno Autónomo de Canarias for its financial support by contract 4/95, the Comisi6n Interministerial de Ciencia y Tecnologia (CICYT) by contract CLI97- 0453, and the University of La Laguna by contract 1802260003. A portion of this work was carried out as part of the Atmosphere/Ocean Chemistry Experiment (AEROCE) and supported by the National Science Foundation grants ATM-9414808, ATM-9414812, and ATM- 9414846

The Aerosol Limb Imager

Stratospheric aerosol has been measured globally from satellite platforms over the past three decades. The variability of the natural and anthropogenic sources and resulting effect on climate make continued and improved measurements a priority. Yet, few satellite instruments capable of measuring stratospheric aerosol currently exist, with a lack of planned missions to fill the gap left by the ultimate loss of current instruments. The Aerosol Limb Imager (ALI) is an optical remote sensing instrument designed to image scattered sunlight from the atmospheric limb. These measurements are used to retrieve spatially resolved information of the stratospheric aerosol distribution, including spectral extinction coefficient and particle size. Here we present the design, development and test results of an ALI prototype. The instrument design uses a large aperture Acousto-Optic Tunable Filter (AOTF) to image the sunlit stratospheric limb in a selectable narrow wavelength band ranging from the visible to the near infrared. Through the nature of the AOTF operation, ALI measures one orientation of the polarized limb radiance, rather than the historically observed total radiance. A modelling study on the impact of this approach on the retrievals shows that while there is no distinct advantage to the linearly polarized measurement, there are also no clear disadvantages assuming the somewhat lower overall signal levels can be handled in the instrument design or operation. The long term goal of this work is the eventual realization of ALI on a satellite platform in low earth orbit, where it can provide high spatial resolution observations, both in the vertical and cross-track dimensions. The ALI prototype was tested on a stratospheric balloon flight from the Canadian Space Agency (CSA) launch facility in Timmins, Canada, in September 2014. Preliminary analysis of the hyperspectral images indicate that the radiance measurements are of high quality, and these are used to successfully retrieve vertical profiles of stratospheric aerosol extinction coefficient from 650–950 nm, along with one moment of the particle size distribution

Abstracts of papers presented at the Eleventh International Laser Radar Conference

Abstracts of 39 papers discuss measurements of properties from the Earth's ocean surface to the mesosphere, made with techniques ranging from elastic and inelastic scattering to Doppler shifts and differential absorption. Topics covered include: (1) middle atmospheric measurements; (2) meteorological parameters: temperature, density, humidity; (3) trace gases by Raman and DIAL techniques; (4) techniques and technology; (5) plume dispersion; (6) boundary layer dynamics; (7) wind measurements; visibility and aerosol properties; and (9) multiple scattering, clouds, and hydrometers

Effects of selected additives on a luminous diffusion flame

Imperial Users onl

Assessment of the biophysical characteristics of rangeland community using scatterometer and optical measurements

Research activities for the following study areas are summarized: single scattering of parallel direct and axially symmetric diffuse solar radiation in vegetative canopies; the use of successive orders of scattering approximations (SOSA) for treating multiple scattering in a plant canopy; reflectance of a soybean canopy using the SOSA method; and C-band scatterometer measurements of the Konza tallgrass prairie

PARTICLE BEAM GLOW DISCHARGE SPECTROSCOPY AS A TOOL FOR SPECIATION AND METALLOMICS ANALYSIS

Metallomics is a growing field of interdisciplinary research that investigates metals in biological and environmental systems. One of the major problems in detecting metals in biological systems is the instrumentation required to analyze these complex biological samples. Typically, an inductively coupled plasma-optical emission spectrometer or -mass spectrometer (ICP - OES or - MS) is used for elemental analysis and an electrospray ionization-mass spectrometer (ESI-MS) is used for molecular information. In almost all cases, the sample introduction matrix is different for each instrument, which can affect the physiological conditions of the sample and change its properties. Particle beam/hollow cathode-optical emission spectroscopy (PB/HC-OES) and liquid chromatography-particle beam/glow discharge mass spectrometry (LC-PB/GDMS) are presented as tools for obtaining both elemental and molecular species information without changing sample preparation. The PB/HC system was coupled to a high resolution Jobin-Yvon polychromator and optimized with respect to operational parameters using a metal mixture of Ag, Ni, and Pb to display the ability of the PB/HC-OES system as a simultaneous multiple element detector. Additionally, a commercially available Hewlett Packard 5973 gas chromatography-mass spectrometer (GC-MS) was converted to a LC-PB/GDMS capable of providing comprehensive speciation (both atomic and molecular) information. The PB/HC-OES method is presented as a tool for determining metal binding characteristics involving Tf. Transferrin (Tf) is an iron transport protein that is essential for cellular survival, providing Fe3+ to cells via receptor mediated endocytosis. Transferrin is ~ 40 % Fe3+-loaded, leaving roughly 60 % of Tf with free binding sites that can potentially bind other metal ions. Validation of the PB/HC-OES method for quantitative analysis was provided by comparing loading percentages of Fe3+ into apo-Tf with UV-VIS absorbance measurements. The PB/HC-OES method was used to determine metal loading of Ni2+ and Zn2+ into the C- and N-lobes of apo-Tf and binding of Ag+ to the surface methionines of Tf. The monitoring of Cr3+ loading into apo-Tf by PB/HC-OES and ICP-OES/UV-VIS absorbance methods are presented as further validation for the use of the PB/HC-OES method. Finally, the PB/HC-OES method was used to monitor the direct metal (Fe3+, Cr3+, and Ni2+) competition for transferrin binding under physiological relevant concentrations

SYNTHESIS, CHARACTERIZATION, AND APPLICATION OF Ag NANOSTRUCTURES

Noble metal nanoparticles (NPs) have been used for many centuries; however their properties were not truly scrutinized until Michael Farady\u27s investigations in the 1850\u27s. Advances in the field of nanotechnology over the last three decades have enabled insights into the properties of materials as their dimensions are reduced to the nanoscale. The repercussions of these insights are seen in many modern applications. In this dissertation, properties of novel nanostructures based on Ag NPs are presented and discussed. The exceptional optical properties of Ag NPs stem from the collective oscillations of the conduction electrons known as plasmon resonances. The excitation of plasmon resonances leads to the strongest known interaction of light with matter as compared to any known organic or inorganic chromophore. A novel type of nanostructure, composed of Ag NPs capped with various materials and termed asymmetric hybrid nanoparticles (AHNs) was proposed and implemented. The concept of AHNs allows the addition of new properties to nanoparticles. Metals and dielectric materials were used as caps, imparting strong effects on the plasmon resonances of the AHNs. Multilayer AHNs were fabricated to render magnetic properties to Ag NPs. The AHN concept led to the development of a novel type of optical labels. The labels are based on the surface enhanced Raman scattering (SERS) phenomenon from organic molecules sandwiched between Ag core and Ag cap. The observed strong SERS is well suited for multiplexed assays with optical detection. The structures were also used for fundamental SERS investigations. An alternative enhancement mechanism termed plasmon-induced electronic coupling was proposed from the results. Capitalizing on their large cross-section for the interaction with light, Ag NPs were also investigated as optical labels based on light scattering. Ag NPs were encapsulated in silica shells, modified with amine functionalities, followed by conjugation with neutravidin molecules. Neutravidin offers a scaffold for attaching biotinylated biomolecules including antibodies. Silica shells provided nearly complete protection of Ag core in saline solutions often used in bioanalytical applications. The ongoing work focused on the application of these labels to flow cytometry