4,373 research outputs found
SYNTHESIS, CHARACTERIZATION, AND ACTIVATION OF PYRIDINE DIPYRROLIDE SUPPORTED VANADIUM-NITROGEN MULTIPLE BONDS
The chemistry of coordination complexes of vanadium supported by pyridine di-pyrrolide pincer ligands was probed via the synthesis and investigation of a variety of compounds from the trivalent starting material, (MesPDPPh)VCl(thf)2. Under reducing conditions and subsequent addition of terpyridine, a redox transfer series (1-, 0, 1+) stemming from the neutral product (MesPDPPh)V(terpy) was isolated and characterized by X-ray crystallography. The precise bond lengths, in conjunction with bulk magnetic susceptibility, allowed for a detailed study of the redox non-innocence of polypyridyl ligands in these systems.
Metathesis of the halide starting material with azide salts allowed for the isolation of [Na(18-crown-6)][(MesPDPPh)V(N3)2(thf)], which could be thermolyzed to produce the mixed nitride/azide salt, [Na(18-crown-6)][(MesPDPPh)VN(N3)]. Following characterization of the resulting vanadium-nitrogen triple bond, the activation of this species with electrophilic reagents was explored. The PDP supported vanadium nitride proved a competent nucleophile toward trimethylsilyl chloride, resulting in the imido complex (MesPDPPh)V(NTMS)(N3). This product was then subjected to reducing conditions as a first step toward silylation-coupled electron transfer, as a model analogue for homogeneous ammonia production, resulting in the isolation of the cobaltocenium salt of the parent complex.
The vanadium-imido complex (MesPDPPh)V(N-1Ad)(N3) was prepared by thermolysis of 1-adamantyl azide in the presence of the trivalent halide starting material, followed by metathesis with azide salts. This product, along with [Na(18-crown-6)][(MesPDPPh)VN(N3)] and (MesPDPPh)V(NTMS)(N3), were then subjected to photolytic conditions to generate transient diradical nitrene intermediate from the decomposition of the pendant azide ligand on the d0 V(V) metal center. Irradiation with green light lead to the generation of the intra-ligand C-H activated products [(Na(18-crown-6)][(MesPDPPh-NH)VN] and (MesPDPPh-NH)V(NTMS). Following the study of this reactivity, computations revealed an unusual lowest lying excited state, which may be responsible for a divergent deazotation mechanism for the preconceived unimolecular pathway.
In order to contrast work in this lab with the photosensitizer Zr(MesPDPPh)2, a new ligand was prepared and appended to a variety of early metals including titanium, zirconium, vanadium, and niobium. The pyridine di-amine (PDA) ligand scaffold was directly compared to the PDP ligand, and its reactions with metals gave several interesting products during the course of this study. However, none of these were luminescent. This result was investigated by empirical techniques and computational chemistry
Variable-Height Wind Tunnel Fairing
For wind tunnel testing, fairings are used to prevent support struts from disrupting airflow near a model and to prevent aerodynamic forces from acting on the support strut. With an infinite number of possible testing configurations, a fairing can be more or less effective for a test, impacting test accuracy. The purpose of this project is to create a fairing system with an adjustable height and investigate how this impacts aerodynamic testing. If a fairing is too short, the aerodynamic forces/moments from the model support strut can be picked up by the force balance. If a fairing is too tall it may get too close to the model and the fairing itself may disrupt airflow near the model. The designed fairing will be manufactured in-house at the MicaPlex Wind Tunnel facility using a 3-D printer with PLA filament. Once manufacturing of the model is complete, it will be force-tested to ensure structural sufficiency and will be tested at varying heights with a model in the wind tunnel. From these tests, drag and lift coefficients will be compared with known/theoretical values. The concept will be validated using CFD software. If this fairing design is found to be effective it will increase the accuracy of aerodynamic tests being conducted at the MicaPlex Wind Tunnel. Additionally, the fairing could be duplicated at similar facilities for better testing accuracy
Synonymous Codon Pair Recoding of the HIV-1 env Gene Affects Virus Replication Capacity
Synonymous codon pair deoptimization is an efficient strategy for virus attenuation; however, the underlying mechanism remains controversial. Here, we optimized and deoptimized the codon pair bias (CPB) of the human immunodeficiency virus type 1 (HIV-1) envelope (env) gene to investigate the influence of env synonymous CPB recoding on virus replication capacity, as well as the potential mechanism. We found that env CPB deoptimization did not always generate attenuation, whereas CPB optimization attenuated virus replication in MT-4 cells. Furthermore, virus attenuation correlated with reduced Env protein production but not with decreased viral RNA synthesis. Remarkably, in our model, increasing the number of CpG dinucleotides in the 5' end of env did not reduce the replication capacity of HIV-1. These results indicate that factors other than CPB or CpG content may have impacted the viral fitness of the synonymously recoded study variants. Our findings provide evidence that CPB recoding-associated attenuation can affect translation efficiency. Moreover, we demonstrated that an increased number of CpGs in the 5' end of HIV-1 env is not always associated with reduced virus replication capacity
Morphological Characterization of Indoor Airborne Particles in Seven Primary Schools
This paper focuses on a study of fine (less than 2.5 µm) airborne particles collected inside seven primary schools located on a coastal Mediterranean area which has a significant industrial hub for the processing of clays and other minerals as raw materials. Of the seven schools, three are located in an urban area 20 km away from the main industrial hub, three are in a town located next to the industrial estate, and one is in a rural location, 30 km from the industrial area. The objective of this study is to identify the main types of particles found in the three examined environments. The particle matter identified in the fine particle samples is grouped into three main groups: mineral compounds, particles from combustion processes and phases emitted in high-temperature industrial processes. The mineral particles, which can come from natural or anthropogenic emissions, have been classified depending on their morphology as isometric allotriomorphs or subidiomorphs, with a tabular habit; acicular forms; or pure crystalline forms. Compounds from combustion processes have two types of morphologies: spheroid and dendritic soot particles. Additionally, in smaller quantities, spherical particles associated with high-temperature industrial processes, such as the emissions of ceramic tile-firing and frit-melting processes, are identified. A summary table is shown, which lists the characteristics, as well as the most significant origin of the main particles identified in the fine (<2.5 μm) airborne particles collected inside primary schools located in three different environments (urban, industrial and rural). A visual scale has been established based on the number of particles observed in the samples of the atmospheric particulate fraction between the sizes of 2.5 and 10 µm collected inside the schools. The ratios Ca/Si, S/Si, S/Ca and (Si+Ca)/S have been established. Results obtained may be useful in epidemiological studies in the ceramic cluster area in order to estimate children’s exposure to different indoor primary school microenvironments. Effective policies and mitigation measurements for the protection of children’s health should be carried out in this highly industrialized area
Assessing the importance of the root mean square (RMS) value of different waveforms to determine the strength of a dielectrophoresis trapping force
Parque fluvial "Bocatoma Canal Surco"
El tema de investigación es sobre el desarrollo
del “Parque Fluvial de la Bocatoma del Canal Surco” mediante una red de espacios
públicos a lo largo de su franja marginal. Se busca mostrar la problemática que se genera a lo largo de este (social y
ambiental, principalmente) y evidenciar el gran potencial que tiene el canal Surco como
elemento paisajista y de integración de las comunidades para el tejido limeño.
Esta derivará luego en un proyecto de máster plan de los 2 primeros kilómetros iniciales
del canal Surco que consistirá en un parque fluvial que a su vez contará con programas
recreativos, culturales, administrativos y educativos
Optimización de sistema de aire comprimido en CREATUM S.A
Este trabajo se desarrolló en el marco de las prácticas profesionales para optar por el título de ingeniería mecatrónica, las cuales fueron realizadas en la empresa Creatum S.A. Compañía que está en la industria de la moda y se especializada en insumos con los más altos estándares de innovación, calidad y confiabilidad para la confección, marroquinería y calzado. En Creatum S.A en la mayoría de sus procesos utiliza la energía neumática, por este motivo, el sistema de aire comprimido juega un papel fundamental en la empresa. En la actualidad el sistema de aire comprimido no satisface las necesidades de la empresa, a causa de que el compresor ha perdido eficiencia, por culpa de su antigüedad y también sus reparaciones. Por esto se pierde energía, además el sistema no cuenta con un secador, lo cual hace que haya agentes contaminantes que afectan la calidad del aire. Igualmente, a lo largo de los años la empresa se ha ido expandiendo, por lo tanto, ha aumentado la demanda de consumo de aire comprimido. Este proyecto consistió en dos etapas: La primera en el análisis y diagnóstico, donde se identifican deficiencias en el sistema y pérdidas de energía. La segunda en la búsqueda y selección del equipo adecuado, que sea eficiente y que pueda abastecer la empresa.Ingeniero Mecatrónicopregrad
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