Mix It Up: Teachers' Beliefs on Mixing Mathematics and Science

This paper defines correlation, describes the Mix It Up program, discusses the teachers' beliefs about the value of correlating mathematics and science prior to program participation, and identifies problems teachers associated with correlation before and during the program. Teachers' beliefs about the value of correlation and about the problems associated with correlation are based on results from both quantitative and qualitative methods used to evaluate the program. Results indicate that teachers believe correlating mathematics and science strengthens students' content knowledge in mathematics and science, bridges the gap between mathematics and science, enhances motivation, and increases students' flexibility in problem solving. Additionally, the areas identified by teachers to be most problematic were time, planning for instruction as a team, and exposure to correlation in the past. The most important finding from the program evaluation indicates that although teachers did not identify content knowledge weaknesses before participating in the program, they did recognize gaps in their own content knowledge during program participation, and more importantly they made connections among these gaps, classroom instruction, and their own students' performance in mathematics and science.     

Erratum to: Investigation of metal-oligonucleotide complexes by nanoelectrospray tandem mass spectrometry in the positive mode

The formation and fragmentation of multiply metal-coordinated oligonucleotides was studied by nanoelectrospray tandem mass spectrometry in the positive ion mode. Fundamental aspects of the gas-phase behavior of metal-oligonucleotide complexes are revealed. The addition of transition metal ions, such as iron(II), iron(III), and zinc(II), leads to very stable metal-oligonucleotide complexes which show heavily altered fragmentation patterns in contrast to uncomplexed oligonucleotides. The site of metal ion complexation was located by collision-induced dissociation (CID) experiments. It was found that all three metal ions investigated predominantly coordinate to the central phosphate groups of the oligonucleotides. Furthermore, it is demonstrated that the fragmentation of such complexes depends highly upon the metal ion complexed as well as on the sequence of the nucleobases in the oligonucleotide.     

Biomimetic Total Synthesis of Santalin Y

A biomimetic total synthesis of santalin Y, a structurally complex but racemic natural product, is described. The key step is proposed to be a (3+2) cycloaddition of a benzylstyrene to a “vinylogous oxidopyrylium”, which is followed by an intramolecular Friedel–Crafts reaction. This cascade generates the unique oxafenestrane framework of the target molecule and sets its five stereocenters in one operation. Our work provides rapid access to santalin Y and clarifies its biosynthetic relationship with other colorants isolated from red sandalwood.     

Preserved in a Shell: High‐Performance Graphene‐Confined Ruthenium Nanoparticles in Acetylene Hydrochlorination

The potential implementation of ruthenium‐based catalysts in polyvinyl chloride production via acetylene hydrochlorination is hindered by their inferior activity and stability compared to gold‐based systems, despite their 4‐fold lower price. Combining in‐depth characterization and kinetic analysis we reveal the superior activity of ruthenium nanoparticles with an optimal size of 1.5 nm hosted on nitrogen‐doped carbon (NC) and identify their deactivation modes: 1) nanoparticle redispersion into inactive single atoms and 2) coke formation at the metal sites. Tuning the density of the NC carrier enables a catalytic encapsulation of the ruthenium nanoparticles into single layer graphene shells at 1073 K that prevent the undesired metal redispersion. Finally, we show that feeding O₂ during acetylene hydrochlorination limits coke formation over the nanodesigned ruthenium catalyst, while the graphene layer is preserved, resulting in a stability increase of 20 times, thus rivalling the performance of gold‐based systems.     

N,N-Di(4-halophenyl)nitrenium ions: nucleophilic trapping, aromatic substitution, and hydrogen atom transfer

The reactive intermediates N,N-di(4-chlorophenyl)nitrenium ion and N,N-di(4-bromophenyl)nitrenium ion were generated through photolysis of the corresponding N-amino(2,4,6,-collidinium) ions. The behavior of these diarylnitrenium ions was characterized by laser flash photolysis, analysis of the stable photoproducts, and ab initio calculations with density functional theory. The latter predict these species to have singlet ground states. The halogenated diarylnitrenium ions are significantly longer lived than the unsubstituted diphenylnitrenium ion. Specifically, cyclization to form carbazole derivatives occurs negligibly, if at all, with the halogenated derivatives. They do, however, carry out most of the characteristic reactions of singlet arylnitrenium ions, including combining with nucleophiles on the aryl rings, adding to arenes, and accepting electrons from readily oxidized traps. Interestingly these species also abstract H atoms from 1,4-cyclohexadiene and various phenol derivatives. The implication of the latter process in relation to the computed singlet-triplet energy gaps of ca. -12.5 kcal/mol is discussed.     

Natural rubber in adhesives with permanent stickiness

A technology is suggested for producing adhesive compositions for adhesive tapes that consists in the application of a mixture of NR with different molecular weights derived via variation of the rubber plastication degree.     

Highly Crystalline and Semiconducting Imine-Based Two-Dimensional Polymers Enabled by Interfacial Synthesis

Single-layer and multi-layer 2D polyimine films have been achieved through interfacial synthesis methods. However, it remains a great challenge to achieve the maximum degree of crystallinity in the 2D polyimines, which largely limits the long-range transport properties. Here we employ a surfactant-monolayer-assisted interfacial synthesis (SMAIS) method for the successful preparation of porphyrin and triazine containing polyimine-based 2D polymer (PI-2DP) films with square and hexagonal lattices, respectively. The synthetic PI-2DP films are featured with polycrystalline multilayers with tunable thickness from 6 to 200 nm and large crystalline domains (100–150 nm in size). Intrigued by high crystallinity and the presence of electroactive porphyrin moieties, the optoelectronic properties of PI-2DP are investigated by time-resolved terahertz spectroscopy. Typically, the porphyrin-based PI-2DP 1 film exhibits a p-type semiconductor behavior with a band gap of 1.38 eV and hole mobility as high as 0.01 cm² V⁻¹ s⁻¹, superior to the previously reported polyimine based materials.     

Ni[B2(SO4)4] and Co[B2(SO4)4]: Unveiling Systematic Trends in Phyllosilicate Analogue Borosulfates

Borosulfates are compounds analogous to silicates, with heteropolyanionic subunits of vertex-linked (SO₄)- and (BO₄)-tetrahedra. In contrast to the immense structural diversity of silicates, the number of borosulfates is yet very limited and the extent of their properties is still unknown. This is particularly true for representatives with phyllosilicate and tectosilicate analogue anionic substructures. Herein, we present Ni[B₂(SO₄)₄] and Co[B₂(SO₄)₄], two new borosulfates with phyllosilicate analogue topology. While the anionic subunits of both structures are homeotypic, the positions of the charge compensating cations differ significantly: Ni^II is located between the borosulfate layers, while Co^II—in contrast—is embedded within the layer. Detailed analysis of these two structures based on single-crystal X-ray diffraction, magnetochemical investigations, X-ray photoelectron spectroscopy, and quantum chemical calculations, unveiled the reasons for this finding. By in silico comparison with other divalent borosulfates, we uncovered systematic trends for phyllosilicate analogues leading to the prediction of new species.