A CHARACTERIZATION MODEL WITH SPATIAL AND TEMPORAL RESOLUTION FOR LIFE CYCLE IMPACT ASSESSMENT OF PHOTOCHEMICAL PRECURSORS IN THE UNITED STATES

Photochemical pollution is formed due to the chemical reactions of atmospheric NOx, volatile organic compounds, CO, and CH4 in the presence of sunlight. It is a complex, non-linear process influenced by several parameters which change spatially and temporally. Ozone, which is the most common photochemical, damages human health, ecosystems, and man-made materials. It also contributes to climate change. Traditional life cycle impact assessment methodologies have used aggregated impact factors for a country or even for a continent, neglecting these variations.This research assesses the geographical and temporal variability in the characterization factors for emissions of NOx and VOC over the continental US by developing monthly state-level factors. A photochemical air quality modeling system (CAMx-MM5-SMOKE) is used to simulate the process of formation, transformation, transport, and removal of photochemical pollutants. Characterization factors are calculated at three levels along the cause-effect chain, namely, fate level, human and ecosystem exposure level, and human effect level. The results indicate that a spatial variability of one order of magnitude and a temporal variability of two orders of magnitude exist in both the fate level and human exposure and effect level characterization factors for NOx. The highest temporal variation in the characterization factors for NOx is seen in the Northeastern US. The summer time characterization factors for NOx are higher than the winter time factors. However, for anthropogenic VOC, the summer time factors are lower than the winter time in almost half of the states. The ecosystem exposure factors for NOx and VOC do not follow a regular pattern and show a spatial variation of about three orders of magnitude. The fate, human exposure, and human effect level factors correlate well as all three are dependent on the atmospheric concentration of ozone. However, they are poorly correlated with the ecosystem exposure factors. Sensitivity analysis of the characterization factors for meteorology and emissions inputs shows variation between negative 90% and positive 180%. This is still lower than the spatial and temporal variations. A life cycle assessment case study is included to illustrate the use of the disaggregated characterization factors

Julia: A Fresh Approach to Numerical Computing

Bridging cultures that have often been distant, Julia combines expertise from the diverse fields of computer science and computational science to create a new approach to numerical computing. Julia is designed to be easy and fast. Julia questions notions generally held as "laws of nature" by practitioners of numerical computing: 1. High-level dynamic programs have to be slow. 2. One must prototype in one language and then rewrite in another language for speed or deployment, and 3. There are parts of a system for the programmer, and other parts best left untouched as they are built by the experts. We introduce the Julia programming language and its design --- a dance between specialization and abstraction. Specialization allows for custom treatment. Multiple dispatch, a technique from computer science, picks the right algorithm for the right circumstance. Abstraction, what good computation is really about, recognizes what remains the same after differences are stripped away. Abstractions in mathematics are captured as code through another technique from computer science, generic programming. Julia shows that one can have machine performance without sacrificing human convenience.Comment: 37 page

Array operators using multiple dispatch: a design methodology for array implementations in dynamic languages

Arrays are such a rich and fundamental data type that they tend to be built into a language, either in the compiler or in a large low-level library. Defining this functionality at the user level instead provides greater flexibility for application domains not envisioned by the language designer. Only a few languages, such as C++ and Haskell, provide the necessary power to define $n$-dimensional arrays, but these systems rely on compile-time abstraction, sacrificing some flexibility. In contrast, dynamic languages make it straightforward for the user to define any behavior they might want, but at the possible expense of performance. As part of the Julia language project, we have developed an approach that yields a novel trade-off between flexibility and compile-time analysis. The core abstraction we use is multiple dispatch. We have come to believe that while multiple dispatch has not been especially popular in most kinds of programming, technical computing is its killer application. By expressing key functions such as array indexing using multi-method signatures, a surprising range of behaviors can be obtained, in a way that is both relatively easy to write and amenable to compiler analysis. The compact factoring of concerns provided by these methods makes it easier for user-defined types to behave consistently with types in the standard library.Comment: 6 pages, 2 figures, workshop paper for the ARRAY '14 workshop, June 11, 2014, Edinburgh, United Kingdo

DETERMINATION OF S-METHYL L-CYSTEINE BY HIGH-PERFORMANCE LIQUID CHROMATOGRAPHIC METHOD

Objective: A simple, reproducible and sensitive high-performance liquid chromatography method has been developed for determination of S-Methyl L-Cysteine. S-Methyl L-Cysteine is widely observed and most common amino acid in plants, including many edible vegetables, which is responsible for reducing blood cholesterol level in the body. Methods: S-Methyl L-Cysteine was chromatographed using Phosphate buffer of pH 6.5: Acetonitrile in the ratio of 97:3. The liquid chromatogram was equipped with a variable wavelength UV detector, an injector and a data processor. Inertsustain GL-Science Column C-18 (150 mm x 4.6 mm; 5μ) was used as a stationary phase. Results: The retention time of S-Methyl L-Cysteine was observed as 2.261±0.0016 min. The linearity value for S-Methyl L-Cysteine was found to be 100-2000 µg/ml with Correlation of Determination (R2) value as 0.9992. LOD and LOQ values obtained are 29.51μg/ml and 89.74 μg/ml, respectively. Conclusion: The method was developed and validated successfully as per ICH guidelines for analytical method validation

Piston actuated nastic materials

This study investigated nastic materials applied to twisting a rigid beam. Nastic materials contain small, simple machines in a compliant matrix. Here a generic beam must twist by ± 4 degrees; the ± 4 degrees twist is an optimum value to change the angle of attack on a helicopter’s rotor blade. Small piston actuators distributed through the beam’s outer core provide the internal work needed. By actuating the piston elements in their axial direction, which is transverse to the beam’s central axis, the beam twists as desired. This study’s objective is to gain insight into the geometry, the material property combinations, and the boundary conditions that produce nastic materials and structures that twist. An important performance metric is the work density, which is the product of blocked stress and free strain. Blocked stress is the maximum actuation stress in a single stroke that produces maximum work output and free strain is the maximum actuation strain that produces the maximum work output. Optimum work density was found for the piston actuators. As it is difficult to model distributed piston actuators across the beam’s outer core, piston actuator’s effective properties are calculated using finite element models and homogenized in the beam’s outer core. As the goal is to twist a beam, an important parameter in comparing the active beam to a passive beam is torsional stiffness. Torsional stiffness is torque per unit deflection. The active beam’s torsional stiffness is 13.705 MN-m/rad without twist in the initial state, which is 3.5 times stiffer than the passive beam, and 13.341 MN-m/rad at the twisted state, which shows that the beam loses 2.6% of its stiffness during twist. The passive beam’s density is 1000.01 kg/m3 and the active beam’s density is 1399.42 kg/m3, which shows that active structures have a weight penalty that must be less than achieving the motion by traditional systems

Formulation of sildenafil citrate loaded nasal microsphers: An in vitro, ex vivo characterization

The aim of the present study was to prepare gellan gum microspheres of Sildenafil citrate, for intranasal delivery to avoid the first pass metabolism. The microspheres were prepared using spray drying method. The microspheres were evaluated for characteristics like particle size, incorporation efficiency, swelling ability, zeta potential, in-vitro mucoadhesion, ex-vivo mucoadhesion, thermal analysis, XRD study and in-vitro drug release. Treatment of in-vitro data to different kinetic equations indicated diffusion controlled drug delivery from gellan gum microspheres. The results of DSC and XRD studies revealed the molecular amorphous dispersion of Sildenafil citrate into the gellan gum microspheres. Microspheres so prepared were discrete, bulky, free flowing and showed an average encapsulation efficiency ranging from 95-98%. The formulation exhibited a good mucoadhesive strength which was determined in in vitro conditions through falling film technique and was compared with ex vivo studies. The microspheres so prepared also exhibited a good swelling index which confirmed the strong mucoadhesive property of the formulation.Keywords: Gellan gum, Microsperes, Spray drying, Sildinafil citrate, Nasal delivery