Boundary conditions control for a shallow‐water model

A variational data assimilation technique was used to estimate optimal discretization of interpolation operators and derivatives in the nodes adjacent to the rigid boundary. Assimilation of artificially generated observational data in the shallow‐water model in a square box and assimilation of real observations in the model of the Black sea are discussed. It is shown in both experiments that controlling the discretization of operators near a rigid boundary can bring the model solution closer to observations as in the assimilation window and beyond the window. This type of control also allows to improve climatic variability of the model. Copyright © 2011 John Wiley & Sons, Ltd.     

Application of HSQC in the delineation of NMR signals of E and Z isomers of octadecyl p‐coumarates

Octadecyl p‐coumarates undergo E–Z isomerization in daylight. Although ¹H NMR, ¹³C NMR and ¹H–¹H COSY gave indications about this isomerization, the overlapping of some signals in the ¹H NMR of aromatic region prevented the delineation of signals of the individual isomers. However, heteronuclear spin quantum coupling correlation (HSQC) with the unique feature of two sets of nearby δ_C–δ_H correlations gave conclusive evidence for this isomerization and helped in the delineation of ¹H NMR and ¹³C NMR signals of E‐octadecyl p‐coumarate and Z‐octadecyl p‐coumarate. Copyright © 2012 John Wiley & Sons, Ltd.     

Development of an Instrument to Assess and Deliberate on the Integration of Mathematics into Student‐Centered Science Learning

It has long been noted in research literature that there does not exist a shared definition of integration of science and mathematics. Classifying a particular set of integration practices by one of many labels has limited value. Moving past the definition debate, this study describes the development and testing of the Mathematics Integrated into Science: Classroom Observation Protocol (MISCOP). The MISCOP consists of 20 items separated into five constructs. The instrument was found to be internally consistent and has strong construct‐to‐total correlations. Factor analyses revealed five factors that, while not completely aligned with the five designed categories, did have notable correspondence. The pilot testing and analyses reveal the MISCOP to be a useful instrument for measuring the degree to which mathematics is integrated into student‐centered learning of science.     

Anionic polymerization of biomass‐derived furfuryl methacrylate: Controlling polymer tacticity and thermoreversibility

Biomass‐derived furfuryl methacrylate (FMA) has been successfully polymerized for the first time by anionic polymerization to produce atactic (at‐), isotactic (it‐), or syndiotactic (st‐) poly(furfuryl methacrylate) (PFMA), depending on initiator structure and reaction conditions. Thermal properties of the PFMA materials are strongly affected by the polymer tacticity. Most notably, while both isotactic and syndiotactic polymers can undergo inter‐ or intrachain crosslinking reactions when heated to 290 °C, there is no evidence for the atactic polymer to perform the same reaction. Furthermore, the PFMA tacticity also greatly affects the amount of stable carbonaceous materials it produces when heated to 650 °C, with st‐PFMA forming the largest amount of such materials (26.9%), as compared to only 5.6% by at‐PFMA. Using the Diels–Alder (DA) “click reaction” between the reactive furfuryl group within the PFMA polymers as the diene equivalent and a bismaleimide as the dienophile, thermoreversible smart polymers have been successfully prepared. Thermoreversibility of the preformed crosslinked polymers has been demonstrated, thanks to the facile retro‐DA reaction upon heating and the DA reaction upon cooling of such self‐healing materials. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2793–2803     

A Systematic Study of Structure and E−H Bond Activation Chemistry by Sterically Encumbered Germylene Complexes

A series of new germylene compounds has been synthesized offering systematic variation in the σ‐ and π‐capabilities of the α‐substituent and differing levels of reactivity towards E?H bond activation (E=H, B, C, N, Si, Ge). Chloride metathesis utilizing [(terphenyl)GeCl] proves to be an effective synthetic route to complexes of the type [(terphenyl)Ge(ER_n)] ( 1 – 6 : ER_n=NHDipp, CH(SiMe₃)₂, P(SiMe₃)₂, Si(SiMe₃)₃ or B(NDippCH)₂; terphenyl=C₆H₃Mes₂‐2,6=Ar^Mes or C₆H₃Dipp₂‐2,6=Ar^Dipp; Dipp=C₆H₃iPr₂‐2,6, Mes=C₆H₂Me₃‐2,4,6), while the related complex [{(Me₃Si)₂N}Ge{B(NDippCH)₂}] ( 8 ) can be accessed by an amide/boryl exchange route. Metrical parameters have been probed by X‐ray crystallography, and are consistent with widening angles at the metal centre as more bulky and/or more electropositive substituents are employed. Thus, the widest germylene units (θ>110°) are found to be associated with strongly σ‐donating boryl or silyl ancillary donors. HOMO–LUMO gaps for the new germylene complexes have been appraised by DFT calculations. The aryl(boryl)‐germylene system [Ar^MesGe{B(NDippCH)₂}] ( 6 ‐Mes), which features a wide C‐Ge‐B angle (110.4(1)°) and (albeit relatively weak) ancillary π‐acceptor capabilities, has the smallest HOMO–LUMO gap (119 kJ mol^?1). These features result in 6 ‐Mes being remarkably reactive, undergoing facile intramolecular C?H activation involving one of the mesityl ortho‐methyl groups. The related aryl(silyl)‐germylene system, [Ar^MesGe{Si(SiMe₃)₃}] ( 5 ‐Mes) has a marginally wider HOMO–LUMO gap (134 kJ mol^?1), rendering it less labile towards decomposition, yet reactive enough to oxidatively cleave H₂ and NH₃ to give the corresponding dihydride and (amido)hydride. Mixed aryl/alkyl, aryl/amido and aryl/phosphido complexes are unreactive, but amido/boryl complex 8 is competent for the activation of E?H bonds (E=H, B, Si) to give hydrido, boryl and silyl products. The results of these reactivity studies imply that the use of the very strongly σ‐donating boryl or silyl substituents is an effective strategy for rendering metallylene complexes competent for E?H bond activation.     

A Convenient Synthesis of β,β-Bis(Alkylthio)Acrylonitriles

We describe a useful synthesis of a variety of β,β-bis(alkylthio)acrylonitriles via the alkylation of the salt arising from the condensation of acetonitrile with carbon disulfide in ether.     

Comparative Structural Study of Three Tetrahalophthalic Anhydrides: Recognition of X···O(anhydride) Halogen Bond and πh···O(anhydride) Interaction

Structures of three tetrahalophthalic anhydrides (TXPA: halogen = Cl (TCPA), Br (TBPA), I (TIPA)) were studied by X-ray diffraction, and several types of halogen bonds (HaB) and lone pair···π-hole (lp···πh) contacts were revealed in their structures. HaBs involving the central oxygen atom of anhydride group (further X···O(anhydride) were recognized in the structures of TCPA and TBPA. In contrast, for the O(anhydride) atom of TIPA, only interactions with the π system (π-hole) of the anhydride ring (further lp(O)···πh) were observed. Computational studies by a number of theoretical methods (molecular electrostatic potentials, the quantum theory of atoms in molecules, the independent gradient model, natural bond orbital analyses, the electron density difference, and symmetry-adapted perturbation theory) demonstrated that the X···O(anhydride) contacts in TCPA and TBPA and lp(O)···πh in TIPA are caused by the packing effect. The supramolecular architecture of isostructural TCPA and TBPA was mainly affected by X···O(acyl) and X···X HaBs, and, for TIPA, the main contribution provided I···I HaBs.     

Toughening Brittle Bio-P3HB with Synthetic P3HB of Engineered Stereomicrostructures

Poly(3-hydroxybutyrate) (P3HB), a biologically produced, biodegradable natural polyester, exhibits excellent thermal and barrier properties but suffers from mechanical brittleness, largely limiting its applications. Here we report a mono-material product design strategy to toughen stereoperfect, brittle bio or synthetic P3HB by blending it with stereomicrostructurally engineered P3HB. Through tacticity ([mm] from 0 to 100 %) and molecular weight (M_n to 788 kDa) tuning, high-performance synthetic P3HB materials with tensile strength to ≈30 MPa, fracture strain to ≈800 %, and toughness to 126 MJ m⁻³ (>110× tougher than bio-P3HB) have been produced. Physical blending of the brittle P3HB with such P3HB in 10 to 90 wt % dramatically enhances its ductility from ≈5 % to 95–450 % and optical clarity from 19 % to 85 % visible light transmittance while maintaining desirably high elastic modulus (>1 GPa), tensile strength (>35 MPa), and melting temperature (160–170 °C). This P3HB-toughening-P3HB methodology departs from the traditional approach of incorporating chemically distinct components to toughen P3HB, which hinders chemical or mechanical recycling, highlighting the potential of the mono-material product design solely based on biodegradable P3HB to deliver P3HB materials with diverse performance properties.