Assessing the Impact of a Statewide STEM Investment on K–12, Higher Education,and Business/Community STEM Awareness Over Time

Despite monetary and educational investments in science, technology, engineering, and mathematics (STEM) being at record high levels, little attention has been devoted to generating a common understanding of STEM. In addition, working with business, K–12 schools, and/or institutions of higher education to establish a grassroots effort to help community members understand the importance of STEM regarding the future prosperity of the United States in general, and specifically the preparedness of children for careers of now and the future, has been nonexistent. The purpose of our study is to assess the impact of a statewide STEM professional development program implemented for two years on STEM awareness over time among various community stakeholders (i.e., K–12 teachers, higher education faculty, and business members). STEM awareness and beliefs about STEM engagement, resources, student preparation, and careers all improved over time for all groups. However, business members had the greatest growth over time and held significantly higher awareness compared with the other groups in most areas. Our findings suggest that a statewide STEM partnership/network model is a viable option for growing collective impact and sustainability of STEM K–12 education.     

The Astounding Chemistry of a 2‐Amino‐1,2‐dihydroisoquinoline Derivative

The cycloadducts of isoquinolinium N‐phenyl imide 2 with C=C bonds are derivatives of 2‐amino‐1,2‐dihydroisoquinoline. Their N^β‐vinylphenylhydrazine system is amenable to an acid‐catalyzed [3,3]‐sigmatropic shift; the formation of pentacyclic aminals is exemplified by 6 → 8 . The dimethyl maleate adduct 11 , C₂₁H₂₀N₂O₄, is exceptional by being converted on treatment with acid to bright‐yellow crystals, C₂₄H₂₂N₂O₆ (additional C₃H₂O₂). X‐Ray crystal‐structure analysis and NMR spectra reveal structure 13 , and mechanistic studies indicated an initial β‐elimination at the N−N bond of 11 to yield 18 ; this step is followed by a retro‐Mannich‐type cleavage that gives methyl isoquinoline‐1‐acetate ( 14 ) and methyl 2‐(phenylimino)acetate ( 15 ), according to the sequence C₂₁H₂₀N₂O₄ ( 11 )→ 18 →C₁₂H₁₁NO₂ ( 14 )+C₉H₉NO₂ ( 15 ). In the second act of the drama, electrophilic attack by 15 ‐H⁺ on the ene‐hydrazine group of a second molecule of 11 furnishes 13 by a polystep intramolecular redox reaction. All rate constants must be fine‐tuned in this reaction cascade to give 13 in yields of up to 78% with an overall stoichiometry: 2 C₂₁H₂₀N₂O₄ ( 11 )→C₂₄H₂₂N₂O₆ ( 13 )+C₁₂H₁₁NO₂ ( 14 )+aniline. Interception and model experiments confirmed the above pathway. A by‐product, C₃₃H₃₁N₃O₆ ( 62 ), arises from an acid‐catalyzed dimerization of 11 and subsequent elimination of 15 .     

A chemo-enzymatic route to enantiomerically pure cyclic tertiary amines

Deracemization of racemic chiral tertiary amines has been achieved by combination of an enantioselective amine oxidase, obtained through directed evolution, and ammonia borane in a one-pot process.     

How Can a Hydrophobic MOF be Water‐Unstable? Insight into the Hydration Mechanism of IRMOFs

We report an ab initio molecular dynamics study of the hydration process in a model IRMOF material. At low water content (one molecule per unit cell), water physisorption is observed on the zinc cation but the free?bound equilibrium strongly favors the free state. This is consistent with the hydrophobic nature of the host matrix and its type‐V isotherm observed in a classical Monte Carlo simulation. At higher loading, a water cluster can be formed at the Zn₄O site and this is shown to stabilize the water‐bound state. This structure rapidly transforms into a linker‐displaced state, where water has fully displaced one arm of a linker and which corresponds to the loss of the material’s fully ordered structure. Thus an overall hydrophobic MOF material can also become water unstable, a feature that has not been fully understood until now.     

Single molecule force spectroscopy using polyproteins

In recent years single molecule force spectroscopy has emerged as a powerful new tool to explore the mechanical stability and folding pathways of individual proteins. This technique is used to apply a stretching force between two points of a protein, unfolding the protein to an extended state. By measuring the unfolding and folding trajectories of individual proteins, insight can be gained into the physical mechanisms of protein folding. In this tutorial review we introduce the reader to single molecule force spectroscopy using the atomic force microscope (AFM), and explain the two main modes of operation of the AFM for force spectroscopy: force-extension and force-clamp. We introduce the approach of using polyproteins to obtain a clear mechanical fingerprint for monitoring the response of proteins to an applied mechanical force. In addition, we provide an informative and representative review of recent research on proteins using single molecule force spectroscopy. We focus on areas which have made a significant contribution to the single molecule protein folding field and highlight emerging areas of research which have wider implications for the general scientific community.     

Coherence-polarization mixing in resonance gratings

We show, using rigorous diffraction theory, that resonance gratings can be used to transfer partial spatial correlation to partial polarization even if the incident light beam is fully polarized. The phenomenon is based on the fact that either of the two orthogonal polarization components can be coupled into the leaky waveguide mode, leading to a strong phase delay, while the other one is reflected without being coupled into the grating. Numerical demonstrations are based on a Gaussian Schell-model beam and a grating analysis performed by rigorous Fourier modal method.     

Total syntheses of angelicoin A, hericenone J, and hericenol A via migratory prenyl- and geranylation-aromatization sequences

A five-step synthesis of the natural product angelicoin A using a late stage highly regioselective palladium(0)-catalyzed decarboxylative prenyl migration and aromatization sequence as the key step is reported. The method was extended with geranyl migration in eight-step total syntheses of hericenone J and hericenol A from geraniol.     

Identification of isomeric 5‐hydroxytryptophan‐ and oxindolylalanine‐containing peptides by mass spectrometry

Cells continuously produce reactive oxidative species that can modify all cellular components. In proteins, for example, cysteine, methionine, tryptophan (Trp), and tyrosine residues are particularly prone to oxidation. Here, we report two new approaches to distinguish two isomeric oxidation products of Trp residues, i.e. 5‐hydroxytryptophan (5‐HTP) and oxindolylalanine (Oia) residues, in peptides. First, 2‐nitrobenzenesulfenyl chloride, known to derivatize Trp residues in position 2 of the indole ring, was used to label 5‐HTP residues. The mass shift of 152.98 m/z units allowed identifying 5‐HTP‐ besides Trp‐containing peptides by mass spectrometry, whereas Oia residues were not labeled. Second, fragmentation of the Oia‐ and 5‐HTP‐derived immonium ions at m/z 175.08 produced ions characteristic for each residue that allowed their identification even in the presence of y₁ ions at m/z 175.12 derived from peptides with C‐terminal arginine residues. The pseudo MS³ spectra acquired on a quadrupole time‐of‐flight hybrid mass spectrometer displayed two signals at m/z 130.05 and m/z 132.05 characteristic for Oia‐containing peptides and a group of six signals (m/z 103.04, 120.04, 130.04, 133.03, 146.04, and 148.04) for 5‐HTP‐cointaining peptides. In both cases, the relative signal intensities appeared to be independent of the sequence providing a specific fingerprint of each oxidative modification. Copyright © 2012 John Wiley & Sons, Ltd.     

Overcharging of polyelectrolyte complexes by the guest polyelectrolyte studied by fluorescence spectroscopy

Polyion complexes (PICs) of anionic block copolymer poly(ethylene oxide)-block-poly(sodium methacrylate), PEO-block-(PMA)Na, and a cationic homopolymer, poly((methacryloyloxyethyl)trimethylammonium chloride), PMOTAC, have been studied by fluorescence spectroscopy. Pyrene and naphthalene singly labeled block copolymers were used with two different sodium methacrylate block lengths. The chain exchange between the stoichiometric PICs at the equilibrium state and the formation of the negatively charged PICs on addition of excess PEO-block-(PMA)Na to stoichiometric PIC solution were of interest. The chain exchange between the stoichiometric complexes was observed to occur via two mechanisms. The faster chain exchange occurs via insertion and expulsion of single chains, while merging and splitting of the PIC particles is behind the slower chain exchange event. Incorporation of an excess amount of the guest polyion into a stoichiometric PIC took place on further addition of the PEO-block-(PMA)Na. The same mechanisms were recognized in the overcharging process of the PICs as in the chain exchange between the stoichiometric PICs.