► Land use change impact on hydrology in a small watershed in Kenya is examined. ► The Soil and Water Assessment Tool is used to model hydrologic response to land use change. ► Impact of land use ...change on groundwater recharge and implications for community water sourcing and Lake Nakuru are addressed.
Land cover and land use changes in Kenya’s Rift Valley have altered the hydrologic response of the River Njoro watershed by changing the partitioning of excess rainfall into surface discharge and groundwater recharge. The watershed contributes a significant amount of water to Lake Nakuru National Park, an internationally recognized Ramsar site, as well as groundwater supplies for local communities and the city of Nakuru. Three land use maps representing a 17-year period when the region underwent significant transitions served as inputs for hydrologic modeling using the Automated Geospatial Watershed Assessment (AGWA) tool, a GIS-based hydrologic modeling system. AGWA was used to parameterize the Soil and Water Assessment Tool (SWAT), a hydrologic model suitable for assessing the relative impact of land cover change on hydrologic response. The SWAT model was calibrated using observation data taken during the 1990s with high annual concordance. Simulation results showed that land use changes have resulted in corresponding increases in surface runoff and decreases in groundwater recharge. Hydrologic changes were highly variable both spatially and temporally, and the uppermost reaches of the forested highlands were most significantly affected. These changes have negative implications for the ecological health of the river system as well as Lake Nakuru and local communities.
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This work empirically evaluated oxygenated blendstock - lubricant compatibility using a novel but simple method. The reactivity or compatibility was evaluated via gas chromatograph ...equipped with a flame ionization detector (GC-FID) before and after heating for 2 h at 150 °C, which would roughly mimic conditions encountered in the crankcase of a Spark Ignition (SI) or Compression-Ignition (CI) engine. Although 150 °C does not mimic combustion chamber temperatures, it may provide an insight of potential in-cylinder interactions. Five oxygenate blendstocks spanning several functional groups and chain lengths (prenol, isoprenol, butyl acetate, isohexanol, polyoxymethylene dimethyl ethers) were evaluated in a base fuel with nine variations of lubricant components of controlled concentrations, including fully formulated commercial lubricants. Baseline comparative examples were also generated, to decouple the effect of the oxygenate on the mixture, by heating only the base fuel with the lubricant component. Results demonstrate the relative compatibility between noted lubricants and oxygenates in base fuel upon heating. This was illustrated by minimal to no changes in the GC-FID traces. However, reactions of several of the chosen lubricants, especially Molybdenum di(2-ethylhexyl) phosphorodithioate (Molyvan L) and zinc dialkyldithiophosphate (ZDDP), with prenol and polyoxymethylene dimethyl ethers blendstocks showed substantial side reactions compared to corresponding baseline examples. Control experiments without oxygenates but comprising the same lubricant components showed no change in the mixture with heating. We concluded the reactivity is due to the oxygenate and not the components of the base fuel. This preliminary work is valuable in establishing trends as well as providing useful information when a new component is introduced in the fuel.
We document an artifact associated with the back reflection from samples or sampling accessories in Fourier transform spectrometers. Samples oriented normal to the incoming modulated beam can reflect ...light back to the interferometer and this light (the percentage dependent on the sample’s refractive index) is modulated by the interferometer a second time resulting in light erroneously appearing at twice its true frequency. The phenomenon occurs across the spectrum but is most apparent when positive-going narrow absorption peaks at 1f display as negative-going peaks at 2f. We have redressed the artifact by implementing a rotation stage directly beneath the sample holder: As the stage is rotated through small angles relative to beam normal, the back-reflected light does not enter the interferometer and the artifact disappears. The observation is relevant to several IR sampling methods: gas/liquid cells, alkali halide pellets, reflectance accessories, etc.
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For the past two decades, BTK a tyrosine kinase and member of the Tec family has been a drug target of significant interest due to its potential to selectively treat various B ...cell-mediated diseases such as CLL, MCL, RA, and MS. Owning to the challenges encountered in identifying drug candidates exhibiting the potency block B cell activation via BTK inhibition, the pharmaceutical industry has relied on the use of covalent/irreversible inhibitors to address this unmet medical need. Herein, we describe a medicinal chemistry campaign to identify structurally diverse reversible BTK inhibitors originating from HITS identified using a fragment base screen. The leads were optimized to improve the potency and in vivo ADME properties resulting in a structurally distinct chemical series used to develop and validate a novel in vivo CD69 and CD86 PD assay in rodents.
Bruton's tyrosine kinase (BTK), a member of the TEC family of kinases, plays a crucial role in B‐cell maturation and mast cell activation. Although the structures of the unphosphorylated mouse BTK ...kinase domain and the unphosphorylated and phosphorylated kinase domains of human ITK are known, understanding the kinase selectivity profiles of BTK inhibitors has been hampered by the lack of availability of a high resolution, ligand‐bound BTK structure. Here, we report the crystal structures of the human BTK kinase domain bound to either Dasatinib (BMS‐354825) at 1.9 Å resolution or to 4‐amino‐5‐(4‐phenoxyphenyl)‐7H‐pyrrolospyrimidin‐ 7‐yl‐cyclopentane at 1.6 Å resolution. This data provides information relevant to the development of small molecule inhibitors targeting BTK and the TEC family of nonreceptor tyrosine kinases. Analysis of the structural differences between the TEC and Src families of kinases near the Trp‐Glu‐Ile motif in the N‐terminal region of the kinase domain suggests a mechanism of regulation of the TEC family members.
The effects of light scattering and refraction play significantly different roles for aerosols than for bulk materials, making it challenging to identify aerosolized chemicals using traditional ...spectral methods or spectral reference libraries. Due to a potentially infinite number of particle morphologies, sizes, and compositions, constructing a database of laboratory-measured aerosol spectra is not a practical solution. Here, as an alternative approach, the measured n / k optical vectors of two example organic materials (diethyl phthalate and D-mannitol) are used in combination with particle absorption / scattering theory (Mie theory and FDTD) and the Beer-Lambert law to generate a series of synthetic infrared transmission / scattered light spectra. The synthetic spectra show significant differences versus simple slab transmission spectra, even for small changes in particle size (e.g., 5 vs. 10 µm) for both single particles and ensembles, potentially serving as useful reference data for aerosol sensing. For spherical single particles with diameters of 1 to 10 µm, FDTD simulations predict changes in the magnitudes of spectral shifts and the shapes of the peaks vs. particle size with only small deviations from Mie theory predictions, yet reliably capture the direction of the shifts. Typical spectral peak shifts in the longwave infrared correspond to Δλ ∼0.20 µm (∼34 cm -1 ) when compared to corresponding slab transmission spectra. Additionally, synthetic spectra generated from the n / k values derived using two different methods (KBr pellet transmission and single-angle reflectance) are compared using the Mie theory model.
The new guanidinylation reagent N,N'-diBoc-N''-triflylguanidine was used to efficiently convert multiamine-containing glycosides including kanamycin A and B, tobramycin, paromomycin, and neomycin B ...to the corresponding fully guanidinylated analogues (guanidinoglycosides). This transformation occurs in the presence of H(2)O under mild conditions. Guanidinotobramycin and guanidinoneomycin B were found to inhibit the replication of the HIV virus with activities approximately 100 times greater than the parent aminoglycosides.
•Method for generation of quantitative vapor-phase infrared spectra for solids with moderate volatility.•Solid analytes reported include dicyclopentadiene, menthol, syringol, phenol, camphor, and ...naphthalene.•Technique widely applicable/reproducible and proven useful at bypassing the challenges associated with high temperature measurements.•PNNL continues to expand database with high resolution, high accuracy broadband infrared spectra.
A method is presented to generate quantitative vapor-phase infrared spectra from substances that naturally occur as solids with moderate volatility. The solid is gravimetrically dissolved into a solvent that has few infrared spectral features, typically CS2 and CCl4 separately. The solution is flowed at a constant rate from a linearly pumped syringe into a metered stream of nitrogen carrier gas regulated by a mass flow controller. The analyte/solvent mix is flash vaporized by volatilizing the solution across a heated stainless-steel surface as it emanates from the syringe tip. The N2 gas-solution mixture is flowed into a long-path White cell thermostatted at a desired temperature, the long optical path compensating for the modest analyte mixing ratio. A composite spectrum is generated from typically ten or more 760-Torr pressure-broadened spectra over the 600 to 6500 cm−1 spectral range at 0.1 cm−1 spectral resolution. The solid analytes reported here using this novel technique include dicyclopentadiene, menthol, syringol, phenol, camphor, and naphthalene.
•Poly- and per-fluoroalkyl substances are known and persistent environmental hazards.•Database of quantitative gas-phase infrared spectra of perfluoroalkyl substances.•Data demonstrated to detect ...PFAS thermal degradation compounds.•Validated / documented methods for reliable data for remote and in situ sensing.
We report the construction of a database of quantitative infrared spectra specifically targeting volatile fluorocarbon gases that may be emitted during thermal treatment of per- and polyfluoroalkyl substances (PFAS) to assist understanding of treatment processes and improve quantification. To populate this database, protocols derived from the Pacific Northwest National Laboratory infrared spectral database have been employed. Each spectrum in the database is a weighted average derived from 10 or more individual measurements at different partial pressures (static method) or flow rates (dissemination method) to yield good fidelity for both strong and weak infrared signatures, with each composite spectrum ranging from ≥ 6500 cm−1 to ≤ 600 cm−1 at an apodized resolution of 0.112 cm−1. This resolution was chosen to fully resolve all spectral features, recognizing that atmospheric pressure broadening results in nearly all ro-vibrational lines having linewidths ≥ 0.1 cm−1. As an example case, application of the database is demonstrated via identification and quantification of dominant 1H-perfluoroheptane and perfluorohept-1-ene fluorocarbon products resulting from thermal decomposition of perfluorooctanoate (PFOA) below 450 °C.
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