The Lost Ones: The Cold War State, Child Welfare Systems, And The Battles Over The Rosenberg Children

The conspiracy case against Julius and Ethel Rosenberg was a formative event in the early stages of the Cold War, but it also set their two sons adrift in a domestic climate which emphasized domestic order but feared communists and those connected to communists within their midst. Michael and Robert Rosenberg’s lives remained in various states of instability from their mother’s arrest in August 1950 until they were adopted by Anne and Abel Meeropol in 1958. The placement of the Rosenberg children with the Meeropols came only after years of upheaval and family strife in which the notoriety of the Rosenberg case kept the boys in the public eye and prevented them from settling with a permanent guardian The height of the battle over the Rosenberg children came in 1954, when New York state authorities removed them from the Meeropol home on charges that communists were exploiting the boys to raise funds. The state Department of Welfare and private Jewish childcare agencies petitioned for legal custody of the boys and their trust fund. The court cases which followed exposed the state’s commitment to controlling the futures of the Rosenberg children and led to conflict between anticommunist state forces, Rosenberg supporters, and professional child welfare workers. The case of Michael and Robert Rosenberg placed postwar American ideas on children and family in direct contention with Cold War anticommunism, and the eventual return of the boys to the Meeropols demonstrates the limits of the Red Scare and expands the understanding of the legacy of the Rosenberg spy case

Flag-Shaped Blockers of 123-Avoiding Permutation Matrices

A blocker of $123$-avoiding permutation matrices refers to the set of zeros contained within an $n\times n$ $123$-forcing matrix. Recently, Brualdi and Cao provided a characterization of all minimal blockers, which are blockers with a cardinality of $n$. Building upon their work, a new type of blocker, flag-shaped blockers, which can be seen as a generalization of the $L$-shaped blockers defined by Brualdi and Cao, are introduced. It is demonstrated that all flag-shaped blockers are minimum blockers. The possible cardinalities of flag-shaped blockers are also determined, and the dimensions of subpolytopes that are defined by flag-shaped blockers are examined.Comment: 19 page

Ascension

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Probing the Reaction Mechanism of the D-ala-D-ala Dipeptidase, VanX, by Using Stopped-Flow Kinetic and Rapid-Freeze Quench EPR Studies on the Co(II)-Substituted Enzyme

In an effort to probe the reaction mechanism of VanX, the D-ala-D-ala dipeptidase required for high-level vancomycin resistance in bacteria, stopped-flow kinetic and rapid-freeze quench EPR studies were conducted on the Co(II)-substituted enzyme when reacted with d-ala-d-ala. The intensity of the Co(II) ligand field band at 550 nm decreased (ε550 = 140 to 18 M-1 cm-1) when VanX was reacted with substrate, suggesting that the coordination number of the metal increases from 5 to 6 upon substrate binding. The stopped-flow trace was fitted to a kinetic mechanism that suggests the presence of an intermediate whose breakdown is rate-limiting. Rapid-freeze quench EPR studies verified the presence of a reaction intermediate that exhibits an unusually low hyperfine constant (33 G), which suggests a bidentate coordination of the intermediate to the metal center. The EPR studies also identified a distinct enzyme product complex. The results were used to offer a detailed reaction mechanism for VanX that can be used to guide future inhibitor design efforts

Engineering Native Amine Dehydrogenases for the Production of Chiral Amines

Chiral amines are fundamental building blocks in synthetic chemistry routinely used in the production of pharmaceuticals, agrochemicals or in the food industry. In recent years, given the need for more renewable and sustainable approaches to the synthesis of these chiral amines, biocatalysts have been investigated. The consideration of biocatalytic approaches has largely led to enantioselective routes to produce chiral amines often with better yields and less harsh reaction conditions and components. More recently, a class of enzymes, found by sequence driven searches of metagenomic databases and samples, known as native Amine Dehydrogenases (nat-AmDHs) have been used for the asymmetric reductive amination of a range of carbonyl compounds. Herein a selection of nat-AmDHs have been structurally and biochemically studied using a range of techniques such as X-ray crystallography, UV-vis spectrometry, and GC-FID analysis. The canonical structural functionalities of these enzymes were found to be consistent throughout. However, some aspects of these previously uncharacterised nat-AmDHs displayed interesting new properties. Namely the increased active site space in the binding pocket of MATOUAmDH2 which permitted the rational engineering of this enzyme to bind larger, more sterically hindered, substrates to produce pharmaceutically relevant amines such as 2-aminonorbornane. These results provide new knowledge and protein scaffolds for the further engineering of nat-AmDHs for the production of primary and secondary chiral amines of both biological and chemical significance

Extraction chromatographic studies of rutherfordium and dubnium homologs

Studying the chemistry of transactinide elements does not only allow for these elements to be properly placed in the Periodic Table, but it also permits for the extrapolation of the electronic structure based upon the position of the element in the Periodic Table. In addition it enable for the assessment of the role that relativistic effects play in the chemical behavior of the heaviest elements. An improved understanding of the role of relativistic effects in chemistry of the heaviest elements allows for a better understanding of the fundamentals principles that govern the Periodic Table. In order to investigate the chemistry of the transactinides, chemical studies on the homologs and pseudo-homologs of the element must first be performed. Chemical studies of the homologs and pseudo-homologs can be completed in a number of ways. Gas-phase chemistry, solvent extraction and ion-exchange chromatography have all been used to study a number of transactinide elements as well as their respective homologs and pseudo-homologs. No matter the method of study, a given system must fulfill the following requirements to be considered suitable; fast kinetics, high separation factors, large number of exchange steps, highly selective and samples easily prepared for alpha spectroscopy. The system must allow for rapid separation due to the short half-lives of transactinide elements (on the order of a few seconds up to a minute). A large number of exchange steps are necessary due to the fact there is only one atom present at a given time. In order for one atom to be statistically representative of a macroscopic amount the atom must undergo many interactions with the two phases of the separation system. The system should also be highly selective to ensure that background contamination is removed and separation of the transactinide from its homologs and pseudo-homologs is achieved. Finally, the samples generated from the separation must be easily and rapidly prepared for alpha spectroscopy so that the decay of the short lived transactinide element can be directly detected. The aim of this research is to develop two separation schemes for elements 104 and 105 that fulfill all of these requirements. For element 105 the proposed extractant molecule is a tetra diglycoloamide in a mixed acid matrix. In the case of element 104 crown ether based ligands of interest. The proposed separation schemes for element 104 and 105 are based on both commercially available and in-house synthesized resins

A Five-coordinate Metal Center in Co(II)-substituted VanX

In an effort to structurally probe the metal binding site in VanX, electronic absorption, EPR, and extended x-ray absorption fine structure (EXAFS) spectroscopic studies were conducted on Co(II)-substituted VanX. Electronic spectroscopy revealed the presence of Co(II) ligand field transitions that had molar absorptivities of ∼100 m–1 cm–1, which suggests that Co(II) is five-coordinate in Co(II)-substituted VanX. Low temperature EPR spectra of Co(II)-substituted VanX were simulated using spin Hamiltonian parameters of M = |±½〉, E/D = 0.14, greal(x,y) = 2.37, and grealS(z) = 2.03. These parameters lead to the prediction that Co(II) in the enzyme is five-coordinate and that there may be at least one solvent-derived ligand. Single scattering fits of EXAFS data indicate that the metal ions in both native Zn(II)-containing and Co(II)-substituted VanX have the same coordination number and that the metal ions are coordinated by 5 nitrogen/oxygen ligands at ∼ 2.0 Å. These data demonstrate that Co(II) (and Zn(II) from EXAFS studies) is five-coordinate in VanX in contrast to previous crystallographic studies (Bussiere, D. E., Pratt, S. D., Katz, L., Severin, J. M., Holzman, T., and Park, C. H. (1998) Mol. Cell 2, 75–84). These spectroscopic studies also demonstrate that the metal ion in Co(II)-substituted VanX when complexed with a phosphinate analog of substrate d-Ala-d-Ala is also five-coordinate

Poster Abstract: Crane Charades: Behavior Identification via Backpack Mounted Sensor Platforms

The Whooping Crane is an endangered species native to North America and there are approximately 575 in existence. There have been recent efforts to provide ecologists with a tool to study the multifaceted behavior of the endangered species. Like many species, cranes display distinctly identifiable movements while being threatened, acting territorial, migrating, or preening. The preliminary experiments described in this poster provide evidence that sensor data presented by a novel sensing platform, the CraneTracker, can be used to identify crane behaviors on-board. With the ability to identify these behaviors, ecologists will have a more granular insight on what occurs during a crane’s life on a daily basis