Estimation of Clear-Water Local Scour at Pile Groups Using Genetic Expression Programming (GEP) and Multivariate Adaptive Regression Splines (MARS).

M.S. Thesis. University of Hawaiʻi at Mānoa 2017

Independent control of elastomer properties through stereocontrolled synthesis

In most synthetic elastomers, changing the physical properties by monomer choice also results in a change to the crystallinity of the material, which manifests through alteration of its mechanical performance. Using organocatalyzed stereospecific additions of thiols to activated alkynes, high-molar-mass elastomers were isolated via step-growth polymerization. The resulting controllable double-bond stereochemistry defines the crystallinity and the concomitant mechanical properties as well as enabling the synthesis of materials that retain their excellent mechanical properties through changing monomer composition. Using this approach to elastomer synthesis, further end group modification and toughening through vulcanization strategies are also possible. The organocatalytic control of stereochemistry opens the realm to a new and easily scalable class of elastomers that will have unique chemical handles for functionalization and post synthetic processing

Retroperitoneal Hematoma as an Atypical Presentation of Choriocarcinoma: A Case Report

A 38-year-old female with an etonogestrel implant in place and history of previous ectopic pregnancy presented with acute abdominal pain and vaginal bleeding. She was found to have a beta-hCG of \u3e12,000 mIU/mL and free fluid noted on a focused assessment with sonography in trauma exam. She underwent an emergent diagnostic laparoscopy due to the suspicion of a ruptured ectopic pregnancy. Findings at the time of surgery included a normal-appearing uterus and left fallopian tube, a surgically absent right fallopian tube and large volume hemoperitoneum with a rapidly expanding left retroperitoneal hematoma. A postoperative computerized tomography (CT) angiogram suggested active bleeding from a pseudoaneurysm of the left renal artery which was successfully embolized by interventional radiology. Biopsy confirmed gestational trophoblastic neoplasia (GTN) after metastases to the brain. In this report, we describe the details of this case of GTN with an atypical presentation

3,9-Dibromo-6,7-dihydro-5H-dibenzo[c,e]thiepine

In the title mol­ecule, C14H10Br2S, the two benzene rings form a dihedral angle of 48.35 (14)°. The seven-membered ring adopts a boat conformation. In the crystal structure, mol­ecules are related by translation along the b axis and exhibit C—H⋯π inter­actions

Dibenzo[b,e]thiepin-11(6H)-one

In the title compound, C14H10OS, the seven-membered thiepin ring adopts a distorted boat conformation with the dihedral angle between the mean planes of the two fused benzene rings being 56.5 (1)°

6,11-Dihydro­dibenz[b,e]oxepin-11-one

In the title compound, C14H10O2, the seven-membered oxepine ring adopts a twist-boat conformation with a dihedral angle between the mean planes of the two fused benzene rings of 42.0 (1)°. In the crystal, mol­ecules are linked into chains propagating along the c axis by inter­molecular C—H⋯O hydrogen bonds and the chains are arranged in layers parallel to (100)

11-[3-(Dimethyl­amino)prop­yl]-6,11-dihydro­dibenzo[b,e]thiepin-11-ol

There are two independent mol­ecules (A and B) in the asymmetric unit of the title compound, C19H23NOS. In each mol­ecule, the seven-membered thiepine ring is bent into a slightly twisted V-shape. The dihedral angles between the mean planes of the two benzene rings fused to the thiepine ring are 75.7 (5) in mol­ecule A and 73.8 (4)° in mol­ecule B. In both mol­ecules, an intra­molecular O—H⋯N hydrogen bond occurs. In the crystal, weak inter­molecular C—H⋯O and C—H⋯π-ring inter­actions are observed

Konzertierte nukleophile aromatische Substitutionen

Jüngste Entwicklungen in der experimentellen und theoretischen Chemie haben zur Identifizierung einer schnell wachsenden Klasse von nukleophilen aromatischen Substitutionsreaktionen geführt, die einem konzertierten Mechanismus (cSNAr) folgen, und nicht dem klassischen, zweistufigen SNAr-Mechanismus. Während klassische SNAr-Reaktionen auf die substantielle Aktivierung des aromatischen Ringes durch elektronenziehende Substituenten angewiesen sind, ist eine solche Aktivierung für den konzertierten Reaktionsverlauf nicht zwingend nötig

Concerted nucleophilic aromatic substitution reactions

Recent developments in experimental and computational chemistry have identified a rapidly growing class of nucleophilic aromatic substitutions that proceed by concerted (cS NAr) rather than classical, two-step, S NAr mechanisms. Whereas traditional S NAr reactions require substantial activation of the aromatic ring by electron-withdrawing substituents, such activating groups are not mandatory in the concerted pathways

Apparent Alkyl Transfer and Phenazine Formation via an Aryne Intermediate

Treatment of chlorotriaryl derivatives 3a and 3d or fluorotriaryl derivatives 3b and 3e with potassium diisopropylamide afforded alkyl-shifted phenazine derivatives 5a/5b, rather than the expected 9-membered triazaorthocyclophane 2a. The phenazine derivatives were isolated in 78–98% yield depending on the halogen and alkyl group present. In the absence of the halogen (chloro or fluoro), the apparent alkyl shift proceeds more slowly and cannot proceed via the intermediacy of the aryne intermediate. Mechanistic possibilities include intramolecular nucleophilic attack on an aryne intermediate leading to a zwitterionic intermediate and alkyl transfer via a 5-endo-tet process, or via a Smiles rearrangement