Estudio teórico de las propiedades estructurales y electrónicas de los compuestos macrocíclicos R-pirogalol[4]arenos.

In this work, we report a theoretical study on the structural and electronic properties of the rccc and rctt conformers of several pyrogallol[4]arenes, R-Pyg[4]arenes (i.e., R = fluroethyl, methyl, t-butyl, phenyl, tolyl, and p-fluorophenyl) carried out by employing the HF-DFT hybrid B3LYP functional. Comparison of the B3LYP energies of the two stereo-isomers showed that the rccc conformer is more stable than its rctt counterpart for all the derivatives considered. However, calculations performed with the double-hybrid Grimme’s B97D functional confirmed the experimental observation that the relative stability depends upon the type of the R substituents. These results clearly suggest that the B97D functional together with large enough basis sets (i.e., split-valence plus polarization and diffuse functions) is sufficiently accurate for the purpose of describing the conformational features of these compounds. Computed electrostatic potential maps of the rccc of the different R-Pyg[4]arenes showed that a negative potential is present within the cavity of these compounds. In addition, it is observed that the size of this negative electrostatic potential depends on the electron-donating or electron-withdrawing character of the R substituents.En el presente trabajo, se reporta un estudio teórico de las propiedades estructurales y electrónicas de las conformaciones rccc y rctt, de varios R-pirogalol[4]arenos (i.e., R = fluoretil, metil, t-butil, fenil, tolil, and p-fluorfenil) realizado con el funcional híbrido HF-DFT B3LYP. Comparación de las energías B3LYP entre los estero-isómeros, mostró que la conformación rccc es más estable que su contraparte rctt, para todos los sistemas considerados. Sin embargo, cálculos realizados con el funcional doble híbrido de Grimme, B97D, confirmó la observación experimental que indica que la estabilidad relativa de los estéreo-isómeros de los R-pirogalol[4]arenos depende exclusivamente del tipo de grupo R utilizado como sustituyente. Estos resultados muestran que el funcional B97D, junto con un conjunto grande de funciones base (i.e., split-valence más funciones de polarización y funciones difusas) son suficientes para obtener una descripción correcta de las propiedades estructurales de estos compuestos. Al calcular los mapas de potencial electroestático de las conformaciones rccc de los diferentes R-pirogalol[4]arenos, se determinó la acumulación de un potencial negativo dentro de la cavidad de estos compuestos. Además, se observó que el tamaño del potencial acumulado dentro de la cavidad, depende del carácter electro-donador o electro-aceptor de lo sustituyentes R

Customizable heterogeneous catalysts: From 3D printed designs to mesoporous materials

This dissertation describes the author’s efforts in developing new heterogeneous catalytic systems. The work is focused on controlling the structure of heterogeneous catalysts at the macroscale (using 3D printing methods) and at the nanoscale (using Mesoporous Silica Nanoparticles). The first chapter consists of a general introduction to 3D printing and its applications in chemistry laboratories and in heterogeneous catalysis. The second chapter presents the 3D printing process of materials with active functional groups using a commercial stereolithographic 3D printer. Controlling the composition of the 3D printable resin, different organic/inorganic catalytic groups were incorporated into the 3D architectures. The active sites, part of the 3D structure, did not require any post-printing treatment for activation and they can be used directly after printing. The incorporated functionalities were accessible and catalytically active for the Mannich, aldol, and Huisgen cycloaddition reactions. As a proof of concept, custom-made catalysts were printed and used for studying the kinetics of a heterogeneously catalyzed reaction in a conventional solution spectrophotometer. In addition, we used 3D printed millifluidic devices containing catalytic copper(II)acetate sites within the walls to promote the azide-alkyne cycloaddition under flow conditions. We showed that 3D printing allows controlling the morphology of the active materials, resulting in enhancing catalytic activity upon increasing complexity of the 3D architectures. The third chapter presents a study of the effect of macroscopic catalyst morphology on the performance of batch reactions. A series of catalytically active magnetic stir-bar compartments (SBC) with different architectures were 3D printed and used to promote the hydrolysis of sucrose. Fixing the surface area and the number of accessible catalytic sites of the 3D printed SBC allowed exploring the effect of subtle changes in morphology on the fluid dynamics of the reaction systems, and consequently on the efficiency of the catalytic conversion. Moreover, varying the ratios between acrylic acid (AA) and 1,6- hexandieoldiacrylate (HDDA) in the SBC allowed tuning cooperativity between acidic sites and hydrophobic domains to control the rate of sucrose hydrolysis. This work demonstrates that 3D printing catalytic materials enables optimizing their performance by simultaneously controlling their macroscopic and molecular structures. The fourth chapter presents a new method for high-throughput screening of 3D printable catalytic resins. While, stereolithography (SLA) is a popular 3D printing technique, large volumes of resins (~150 mL) are required in each printing cycle. Thus, developing materials with different chemical or surface properties can be expensive and time consuming. To address this problem, we designed matrices of compartmentalized resin tanks and adapted them to a commercial 3D printer. The resin tanks with smaller volumes (2 mL) were used for fast and efficient discovery of new library of 3D printable materials, allowing to simultaneously print up to 16 compositions. Using this approach, we screened for resins that can produce 3D objects with different degrees of surface hydrophilicty/hydrophobicity and catalytic activities. The optimized 3D printed catalytic materials with the largest area were used for oxidation of benzyl alcohol into benzaldehyde. The accessibility to screen multiple materials simultaneously allowed us to combine the best observed properties to manufacture an optimized 3D printed geometry (i.e. highest hydrophobicity, highest catalytic activity and highest geometrical surface area) In chapter five, we studied the functionalization (grafting) kinetics of mesoporous silica nanoparticles (MSN) with organo-substituted trimethoxysilanes (R-TMS). Controlling and understanding the functionalization of MSN is necessary to enable a rational design of hierarchical MSN-based hybrid materials. We observed that the grafting process involves an adsorption/desorption equilibrium of R-TMS with the silica surface prior to its reaction with the surface silanols. Monitoring the changes in 3-aminopropyltrimethoxysilane (AP-TMS) grafting rates as a function of its concentration revealed a substrate-inhibition like behavior. Analysis of methanol production rates showed a significantly higher grafting rate for AP- TMS compared to other R-TMS, due to a catalytic effect of the amino group. This effect was used to control the grafting rates of other R-TMS by adding amines with different pKa values. Solid-state NMR (SSNMR) studies revealed that the amine additives can also control the distribution of the grafted R-TMS on the surface of MSN. In chapter six, phenyl-functionalized mesoporous silica materials were used to explore the effect of non-covalent interactions on the release of Ibuprofen into simulated body fluid. To this end, phenyl groups with different orientations and conformational mobilities were introduced onto mesoporous silica surfaces. The Ibuprofen release profiles from the materials were analyzed using an adsorption-diffusion model. All phenyl-containing mesoporous materials showed lower initial release rates than the bare silica. Comparing the different orientations of the phenyl groups, we observed that locked phenyl conformations provide stronger interactions with the drug than flexible phenethyl groups. The differences in adsorption interactions were consistent with DFT calculations. These results show how fine- tuning the orientation of groups can result in the control of a drug release profile

Deactivation of Ceria Supported Palladium through C–C Scission during Transfer Hydrogenation of Phenol with Alcohols

The stability of palladium supported on ceria (Pd/CeO2) was studied during liquid flow transfer hydrogenation using primary and secondary alcohols as hydrogen donors. For primary alcohols, the ceria support was reduced to cerium hydroxy carbonate within 14 h and was a contributing factor toward catalyst deactivation. For secondary alcohols, cerium hydroxy carbonate was not observed during the same time period and the catalyst was stable upon prolonged reaction. Regeneration through oxidation/reduction does not restore initial activity likely due to irreversible catalyst restructuring. A deactivation mechanism involving C–C scission of acyl and carboxylate intermediates is propose

Optimasi Portofolio Resiko Menggunakan Model Markowitz MVO Dikaitkan dengan Keterbatasan Manusia dalam Memprediksi Masa Depan dalam Perspektif Al-Qur`an

Risk portfolio on modern finance has become increasingly technical, requiring the use of sophisticated mathematical tools in both research and practice. Since companies cannot insure themselves completely against risk, as human incompetence in predicting the future precisely that written in Al-Quran surah Luqman verse 34, they have to manage it to yield an optimal portfolio. The objective here is to minimize the variance among all portfolios, or alternatively, to maximize expected return among all portfolios that has at least a certain expected return. Furthermore, this study focuses on optimizing risk portfolio so called Markowitz MVO (Mean-Variance Optimization). Some theoretical frameworks for analysis are arithmetic mean, geometric mean, variance, covariance, linear programming, and quadratic programming. Moreover, finding a minimum variance portfolio produces a convex quadratic programming, that is minimizing the objective function ðð¥with constraintsð ð 𥠥 ðandð´ð¥ = ð. The outcome of this research is the solution of optimal risk portofolio in some investments that could be finished smoothly using MATLAB R2007b software together with its graphic analysis

Search for heavy resonances decaying to two Higgs bosons in final states containing four b quarks

A search is presented for narrow heavy resonances X decaying into pairs of Higgs bosons (H) in proton-proton collisions collected by the CMS experiment at the LHC at root s = 8 TeV. The data correspond to an integrated luminosity of 19.7 fb(-1). The search considers HH resonances with masses between 1 and 3 TeV, having final states of two b quark pairs. Each Higgs boson is produced with large momentum, and the hadronization products of the pair of b quarks can usually be reconstructed as single large jets. The background from multijet and t (t) over bar events is significantly reduced by applying requirements related to the flavor of the jet, its mass, and its substructure. The signal would be identified as a peak on top of the dijet invariant mass spectrum of the remaining background events. No evidence is observed for such a signal. Upper limits obtained at 95 confidence level for the product of the production cross section and branching fraction sigma(gg -> X) B(X -> HH -> b (b) over barb (b) over bar) range from 10 to 1.5 fb for the mass of X from 1.15 to 2.0 TeV, significantly extending previous searches. For a warped extra dimension theory with amass scale Lambda(R) = 1 TeV, the data exclude radion scalar masses between 1.15 and 1.55 TeV

Search for supersymmetry in events with one lepton and multiple jets in proton-proton collisions at root s=13 TeV

Peer reviewe

Search for anomalous couplings in boosted WW/WZ -> l nu q(q)over-bar production in proton-proton collisions at root s=8TeV

Peer reviewe

Measurement of the top quark mass using charged particles in pp collisions at root s=8 TeV

Peer reviewe

MUSiC : a model-unspecific search for new physics in proton-proton collisions at root s=13TeV

Results of the Model Unspecific Search in CMS (MUSiC), using proton-proton collision data recorded at the LHC at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb(-1), are presented. The MUSiC analysis searches for anomalies that could be signatures of physics beyond the standard model. The analysis is based on the comparison of observed data with the standard model prediction, as determined from simulation, in several hundred final states and multiple kinematic distributions. Events containing at least one electron or muon are classified based on their final state topology, and an automated search algorithm surveys the observed data for deviations from the prediction. The sensitivity of the search is validated using multiple methods. No significant deviations from the predictions have been observed. For a wide range of final state topologies, agreement is found between the data and the standard model simulation. This analysis complements dedicated search analyses by significantly expanding the range of final states covered using a model independent approach with the largest data set to date to probe phase space regions beyond the reach of previous general searches.Peer reviewe

Measurement of prompt open-charm production cross sections in proton-proton collisions at root s=13 TeV

The production cross sections for prompt open-charm mesons in proton-proton collisions at a center-of-mass energy of 13TeV are reported. The measurement is performed using a data sample collected by the CMS experiment corresponding to an integrated luminosity of 29 nb(-1). The differential production cross sections of the D*(+/-), D-+/-, and D-0 ((D) over bar (0)) mesons are presented in ranges of transverse momentum and pseudorapidity 4 < p(T) < 100 GeV and vertical bar eta vertical bar < 2.1, respectively. The results are compared to several theoretical calculations and to previous measurements.Peer reviewe