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Synthetic polymers are all around us in the 21st century, ranging from commodity items made from poly(ethylene) and poly(vinyl chloride) to high-tech materials for aerospace, electronics, and medicine. Yet polymer chemistry is often neglected in formal chemical education. Once students recognize the many ways in which polymers are part of their everyday lives, they are motivated to learn about how polymers are made, their unique thermal, mechanical, and optical properties, and how plastics, fibers, elastomers, and adhesives all are possible because of long-chain molecules. Recognizing the importance of synthetic polymers as well as biopolymers, supramolecular structures, and nanoscale materials, the American Chemical Society (ACS) Committee on Professional Training now requires teaching of at least two of these topics in chemistry courses for ACS-certified undergraduate degrees. This special issue of the Journal is a contributed collection of papers describing how polymers are being taught in general, foundational, and advanced chemistry courses and also in high schools, workshops, and demonstrations for the public. The papers in general do not describe complete courses; instead, they describe modules and experiments that could be implemented at different educational levels and in different environments. The papers are sources of ideas of how instructors can incorporate polymer chemistry into their own courses. [ABSTRACT FROM AUTHOR]

Use of color 3D printers as a visualization tool is described in this paper. Starting from any file depicting a chemical structure, multicolor 3D printed chemical structures can be produced. Most structures were printed in hours, making the entire process from file preparation to tangible model quickly achievable. Chemical structure examples are showcased from organic chemistry, organometallic chemistry, and biochemistry. This paper presents a method of producing multicolor chemistry and biochemistry tangible models using Chimera and Magics molecular visualization and 3D printing software. [ABSTRACT FROM AUTHOR]

Mass spectrometry (MS) and Raman spectroscopy are complementary analytical techniques used to provide information related to chemical structures and functional groups of target analytes. Each instrument provides specific chemical information. If these two analytical tools are coupled online, comprehensive structural information can be simultaneously collected from the analytes of interest without losing any important chemical information. Nevertheless, exploring a suitable interface for coupling of these analytical tools, which are governed with different operation principles, remains challenging. In this study, we used a small piece of tissue paper as an interface for hyphenating a Raman spectroscope and a mass spectrometer online. The paper played multiroles as sample loading substrate and an emitter to generate electrospray. Furthermore, it can facilitate surface-enhanced Raman spectroscopic analysis to improve analyte signals in Raman spectra. A sample droplet was placed on the tissue paper located close to the laser of the Raman spectroscope and the inlet of mass spectrometer. Raman spectra were first collected by the Raman spectroscope through laser irradiation followed by generation of electrospray on the edge of the paper for MS analysis. Positional isomers were used as model samples to demonstrate the effectiveness of the hyphenated analytical tool in distinguishing isomers. The feasibility of using this Raman-MS hyphenated technique for monitoring chemical reactions online in real time was also investigated. [ABSTRACT FROM AUTHOR]

Chemical structure has been longrecognized to greatly influencepolymer glass formation, but a general molecular theory that predictshow chemical structure determines the properties of glass-formingpolymers has been slow to develop. While the generalized entropy theory(GET) explains the influence of various molecular details on polymerglass formation, the application of the GET has heretofore been limitedto the use of the simplest polymer model in which all united atomgroups within the monomers of a species interact with a common monomeraveraged van der Waals energy. However, energetic heterogeneitiesare ubiquitous within the monomers of real polymers, and their implicationsfor polymer glass formation remain to be investigated theoretically.This paper uses an extension of the GET to explore the influence ofenergetic heterogeneities within monomers upon the nature of polymerglass formation. This extension of the GET is achieved by combiningthe Adam–Gibbs theory relating the structural relaxation timeto the configurational entropy with a recent significant extensionof the lattice cluster theory for polymer melts with specific interactions,in particular, for melts where three distinct van der Waals interactionenergies are required to describe the energetic heterogeneities withinmonomers. The present paper focuses on establishing general trendsfor the variation of characteristic properties of glass formation,such as the isobaric fragility parameter mPand the glass transition temperature Tg, with molecular details, such as the specific interactions and chainstiffness. Our computations confirm that the previously used modelwith monomer averaged interactions correctly captures general trendsin the variation of mPand Tgwith various molecular parameters. More importantly,adjustment of the energetic heterogeneities within monomers aloneare shown to provide an efficient mechanism for tailoring the propertiesof glass-forming polymers. The variations of polymer properties alongiso-fragility and iso-Tglines are illustratedas important design tools for exhibiting the combined influence ofspecific interactions and chain stiffness. [ABSTRACT FROM AUTHOR]

Maximumtemperature limitations are encountered in distillationcolumns in which thermally sensitive materials are being separated.The maximum base temperature often results in expensive refrigerationbeing required in the condenser because of the resulting low condensertemperature. The concept of using two columns instead of one columnwas discussed in a recent paper (Masel, R. H.; Smith, D. W.; Luyben, W. L. Ind. Eng. Chem.Res.2013, 52, 5172−5176). Results demonstrated thata two-column process is economically better than the conventionalone-column process when the feed contains a significant amount ofthe light component and when there is a large difference in the normalboiling points between the light and heavy components. The purposeof this paper is to explore the dynamic control issues in the one-columnand two-column alternative flowsheets. The dynamic performances ofseveral control structures are evaluated, and effective control schemesare developed that handle large disturbances in throughput and feedcomposition. The key concept is the need to have a structure in whichboth the base temperature and bottoms composition are controlled.The temperature must be tightly controlled because of the maximumtemperature limitation. To maintain the bottoms composition at a constanttemperature (in a binary system), the base pressure must be maintained,not the condenser pressure. [ABSTRACT FROM AUTHOR]

This paper describes a systematicsensitivity analysis of optimal operation conducted on an activatedsludge process model based on the test-bed benchmark simulation modelno. 1 (BSM1) and the activated sludge model no. 1 (ASM1). The objectiveis to search for a control structure that leads to optimal economicoperation, while promptly rejecting disturbances at lower layers inthe control hierarchy avoiding thus violation of the more importantregulation constraints on effluent discharge. We start by optimizinga steady-state nonlinear model of the process. Here, a new steady-statesecondary settler mathematical model is developed based on the theoryof partial differential equations applied to the conservation lawwith discontinuous fluxes. The resulting active constraints must bechosen as economic controlled variables. These are the effluent ammoniafrom the bioreaction section and the final effluent total suspendedsolids at their respective upper limits, in addition to the internalrecycle flow rate at its lower bound. The remaining degrees of freedomneed to be fulfilled, and we use several local (linear) sensitivitymethods to find a set of unconstrained controlled variables that minimizesthe loss between actual and optimal operation; particularly we chooseto control linear combinations of readily available measurements soto minimize the effect of disturbances and implementation errors onthe optimal static performance of the plant. It is expected that theproposed methodology and results obtained therein can be used in practiceas general rules-of-thumb to be tested in actual wastewater treatmentplants of the kind discussed in this paper. [ABSTRACT FROM AUTHOR]

In the paper, we show how some modifications in the chemical structure of mesogenic molecules can lead to an essential increase of the dielectric permittivity of liquid crystalline material due to the reduced molecular ability to the antiparallel dipolar aggregation. As an example, the static permittivities of two nematogenic homologous series, CnH2n+1PhPhCN and CnH2n+1PhCOOPhCN, are analyzed. However, the structural modifications of mesogenic molecules lead often to unfavorable changes in some important physical properties of liquid crystalline material, as a shift in the clearing temperature, for example, or can lead even to a disappearance of the mesophase. This paper presents such an event observed for the compound composed of C5H11PhPh(CH3)CN molecules, the methyl derivatives of C5H11PhPhCN molecules, which form a well-known nematic liquid crystal. [ABSTRACT FROM AUTHOR]

Theoretical studies about reaction mechanisms are usually limited to the determination of the energetic paths that connect reactants, transition states, and products. Recently, our group proposed the structural evolution, which has provided insights about the molecular structure changes occurring along a reaction path. Structural evolution may be defined as the development of a chemical reaction system across the partitioning of the nuclear configuration space into a finite number of structural regions defined on account of the topology of a scalar field, e.g., the electron density. In this paper, we present a tool to investigate within the framework of the Quantum Theory of Moms in Molecules the evolvement of the Valence Shell Charge Concentration, the VSCC evolution, which is the description of the changes of electron density concentrations and depletions around the bonding area of an atom. The VSCC evolution provides supplementary information to the structural evolution because it allows the analysis of valence shells within a structural region, i.e., a subset of RQ with the same connectivity among the atoms forming molecule. This new approach constitutes also a complement to the Valence-Shell Electron Pair Repulsion (VSEPR) model because It gives an account of the adjustments of electron pairs in the valence shell of an atom across a chemical reaction. The insertion reaction in the hydroformylation reaction of ethylene, the reduction of cyclohexanone with lithium aluminum hydride, the oxidation of methanol with chlorochromate, and the bimolecular nucleophilic substitution of CH3F with F- are used as representatives examples of the application of the VSCC evolution. Overall, this paper shows how the VSCC evolution through an analysis of the modifications of local charge concentrations and depletions in individual steps of a chemical reaction gives new insights about these processes. [ABSTRACT FROM AUTHOR]

The determination of the structures and relative energies of microsolvated complexes remains an important challenge for theoretical chemistry because the number of possible aggregates rapidly increases when more solvent molecules are considered. Several approaches (chemical intuition, hierarchy of scheme, evolutionary trees, ...) have been proposed previously to identify the most stable geometries. In the present paper, we compare both the structures and interaction energies computed with different computational protocols for the model case of microhydrated protonated glycine, a system for which experimental complexation enthalpies are available. We compare the results obtained, one the one hand, by a hierarchical approach starting with a AMOEBA search followed by DFT and MP2 refinements and, on the other hand, by a Darwinian tree that uses evolutionary logic and counterpoise corrected MP2 calculations. It is shown that the two approaches yield relatively similar conclusions, though some structures can only be identified by one of the two strategies. This paper therefore underlines the interest of applying more than one minima search tactic for pinpointing all possible microsolvated complexes. [ABSTRACT FROM AUTHOR]

We consider and compare the structural properties of bulk TIP4P water and of a sodium chloride aqueous solution in TIP4P water with concentration c= 0.67 mol/kg, in the metastable supercooled region. In a previous paper (Corradini, D.; Rovere, M.; Gallo, P. J. Chem. Phys.2010, 132, 134508) we found in both systems the presence of a liquid−liquid critical point (LLCP). The LLCP is believed to be the end point of the coexistence line between a high density liquid (HDL) and a low density liquid (LDL) phase of water. In the present paper we study the different features of water−water structure in HDL and LDL both in bulk water and in the solution. We find that the ions are able to modify the bulk LDL structure, rendering water−water structure more similar to the bulk HDL case. By the study of the hydration structure in HDL and LDL, a possible mechanism for the modification of the bulk LDL structure in the solution is identified in the substitution of the oxygen by the chloride ion in oxygen coordination shells. [ABSTRACT FROM AUTHOR]

The control of a divided-wall column is more difficult than the control of a conventional two-column separation sequence for the separation of ternary mixtures because there is more interaction among control loops. In a previous paper, a control structure using four composition loops was shown to provide effective control of the purities of the three product streams and also achieve minimum energy consumption for both feed flow rate and feed composition disturbances. The numerical example studied the separation of benzene, toluene, and o-xylene. The four manipulated variables were reflux flow rate (R), side-stream flow rate (S), reboiler heat input (QR), and liquid split (βL) at the top of the wall. In this paper we explore the use of temperatures to avoid expensive and high-maintenance composition analyzers. Two types of temperature control structures are studied. In the first, three temperatures located in the main column and one temperature on the prefractionator side of the wall are used to adjust the four manipulated variables. Feed flow rate disturbances are well handled with this structure, but product purities start to deviate significantly from their desired values for feed composition changes greater than about 10%. In the second control structure, four differential temperature control loops are used. Performance is improved and disturbances of 20% in feed composition are well handled with only small deviations in product purities. This structure also handles large changes in column operating pressure. [ABSTRACT FROM AUTHOR]

Historically, structure–activity relationship (SAR) analysis has focused on small sets of molecules, but in recent years, there has been increasing efforts to analyze the growing amount of data stored in public databases like ChEMBL. The pharmacophore network introduced herein is dedicated to the organization of a set of pharmacophores automatically discovered from a large data set of molecules. The network navigation allows to derive essential tasks of a drug discovery process, including the study of the relations between different chemical series, the analysis of the influence of additional chemical features on the compounds’ activity, and the identification of diverse binding modes. This paper describes the method used to construct the pharmacophore network, and a case study dealing with BCR-ABL exemplifies its usage for large-scale SAR analysis. Thanks to a benchmarking study, we also demonstrate that the selection of a subset of representative pharmacophores can be used to conduct classification tasks. [ABSTRACT FROM AUTHOR]

Physical and technological principles of formation of clathrate structures for supramolecular electronics are given in this paper. It has been established that supramolecular nature of the "host-guest" conjunction, in general, and hierarchical architecture of the corresponding clathrates, in particular, provide realization of such an extraordinary effect as an optically or a magnetically controlled phenomenon of colossal "negative capacity" with a predicted frequency interval of manifestation, magnitude, and multiplicity. For the first time, the experimental confirmation of the behavior of the electretized fractal clathrate GaSe(β-CD(FeSO4)) as a dissipative element, which accumulates inductive energy, is demonstrated. A general approach for obtaining the generalized transport equations with fractional derivatives by using the Liouville equation with fractional derivatives for a system of classical particles and the Zubarev nonequilibrium statistical operator method within Renyi statistics is presented. New non-Markovian electrodiffusion equations for ions in a spatially heterogeneous medium with the fractal structure and a generalized Cattaneo-type diffusion equation taking into account the fractality of space-time are obtained. The model of subdiffusion impedance based on the Cattaneo equation with fractional derivatives is applied to multilayer nanostructures. Nyquist diagrams for different valuses of the parameter τ (delay time of a flow relative to a concentration gradient) and the subdiffusion coefficient Dα are calculated. [ABSTRACT FROM AUTHOR]

Annotation of metabolites remains a major challenge in liquid chromatography-mass spectrometry (LC-MS) based untargeted metabolomics. The current gold standard for metabolite identification is to match the detected feature with an authentic standard analyzed on the same equipment and using the same method as the experimental samples. However, there are substantial practical challenges in applying this approach to large data sets. One widely used annotation approach is to search spectral libraries in reference databases for matching metabolites; however, this approach is limited by the incomplete coverage of these libraries. An alternative computational approach is to match the detected features to candidate chemical structures based on their mass and predicted fragmentation pattern. Unfortunately, both of these approaches can match multiple identities with a single feature. Another issue is that annotations from different tools often disagree. This paper presents a novel LC-MS data annotation method, termed Biologically Consistent Annotation (BioCAn), that combines the results from database searches and in silico fragmentation analyses and places these results into a relevant biological context for the sample as captured by a metabolic model. We demonstrate the utility of this approach through an analysis of CHO cell samples. The performance of BioCAn is evaluated against several currently available annotation tools, and the accuracy of BioCAn annotations is verified using high-purity analytical standards. [ABSTRACT FROM AUTHOR]

Advances in the field of chemistry often involve nanoparticles, in which the structural transition is surprisingly different from the bulk material, and the difference between them is mainly attributed to the size of the nanoparticles. In this paper, tetragonal nano-CuFe2O4 (t-CuFe2O4) with different sizes ranging from 32 to 79 nm was prepared using the high temperature solid phase method. The structural transition of nano-CuFe2O4 from tetragonal to cubic was determined by differential scanning calorimetry (DSC). The theoretical derivations and experimental tests indicate that, as the size decreases, the temperature, the enthalpy, and the entropy of the structural transition of nano-CuFe2O4 decrease accordingly and present linear variation with the reciprocal of size, respectively. Furthermore, the effect of particle sizes on the magnetic properties of nano-CuFe2O4 was investigated. The results show that the size of nano-CuFe2O4 can obviously affect the magnetic properties: with the particle size of nano-CuFe2O4 decreasing, the saturated magnetic induction decreases, the coercivity increases, while the remanence decreases. [ABSTRACT FROM AUTHOR]

Porphyrin tapes possessing meso-meso β-β β-β triple direct linkages have been targets of extensive studies because of their fully conjugated characteristic p-electronic networks. In this paper, we report porphyrin arch-tapes that bear additional carbonyl group(s) or methylene group(s) inserted between one of the β-β linkage(s) of the porphyrin tapes. The carbonyl-inserted porphyrin arch-tapes were efficiently synthesized by double fusion reactions of β-to-β carbonyl-bridged porphyrin oligomers with DDQ and Sc(OTf)3, and were converted to the methylene-bridged porphyrin arch-tapes via Luche reduction with NaBH4 and CeCl3 followed by ionic hydrogenation with HBF4·OEt2 and BH3·NEt3. While the conventional porphyrin tapes display rigid and planar structures and low solubilities, these porphyrin arch-tapes show remarkably contorted structures, flexible conformations, and improved solubilities because of the presence of the incorporated seven-membered ring(s). Interestingly, the methylene-inserted arch-tapes exhibited conjugative electronic interactions that were comparable to those of porphyrin tapes probably owing to through-space interaction in the contorted conformations. The carbonyl-inserted arch-tapes displayed distinctly larger conjugative interactions owing to an active involvement of the carbonyl group(s) in the electronic conjugation. A similar trend was observed in the nonlinear optical properties, as evidenced by their two-photon absorption cross sections. Furthermore, as a benefit of the contorted structures, these porphyrin arch-tapes can catch C60 fullerene effectively. Naturally, the electron-rich methylene-bridged arch-tapes exhibited larger association constants than the electron-deficient carbonyl-bridged arch-tapes. Among these arch-tapes, a methylene-bridged syn-Ni(II) porphyrin trimer recorded the largest association constant of (1.5 ± 0.4) x 107 M-1 in toluene at 25 °C. [ABSTRACT FROM AUTHOR]

Description of the local microscopic structure in ionic liquids (ILs) is a prerequisite to obtain a comprehensive understanding of the influence of the nature of ions on the properties of ILs. The local structure is mainly determined by the spatial arrangement of the nearest neighboring ions. Therefore, the main interaction patterns in ILs, such as cation-anion H-bond-like motifs, cation-cation alkyl tail aggregation, and ring stacking, were considered within the framework of the nearest-neighbor approach with respect to each particular interaction site. We employed classical molecular dynamics (MD) simulations to study in detail the spatial, radial, and orientational relative distribution of ions in a set of imidazolium-based ILs, in which the 1-butyl-3-methylimidazolium (C4mim+) cation is coupled with the acetate (OAc-), chloride (Cl-), tetrafluoroborate (BF4 -), hexafluorophosphate (PF6 -), trifluoromethanesulfonate (TfO-), or bis(trifluoromethanesulfonyl)amide (TFSA-) anion. It was established that several structural properties are strongly anion-specific, while some can be treated as universally applicable to ILs, regardless of the nature of the anion. Namely, strongly basic anions, such as OAc- and Cl-, prefer to be located in the imidazolium ring plane next to the C-H2/4-5 sites. By contrast, the other four bulky and weakly coordinating anions tend to occupy positions above/below the plane. Similarly, the H-bond-like interactions involving the H² site are found to be particularly enhanced in comparison with the ones at H4-5 in the case of asymmetric and/or more basic anions (C4mimOAc, C4mimCl, C4mimTfO, and C4mimTFSA), in accordance with recent spectroscopic and theoretical findings. Other IL-specific details related to the multiple H-bond-like binding and cation stacking issues are also discussed in this paper. The secondary H-bonding of anions with the alkyl hydrogen atoms of cations as well as the cation-cation alkyl chain aggregation turned out to be poorly sensitive to the nature of the anion. [ABSTRACT FROM AUTHOR]

In this paper, compositions of nanodomains in a commercial high-impact polypropylene (HIPP) were investigated by an atomic force microscopy-infrared (AFM-IR) technique. An AFM-IR quantitative analysis method was established for the first time, which was then employed to analyze the polyethylene content in the nanoscopic domains of the rubber particles dispersed in the polypropylene matrix. It was found that the polyethylene content in the matrix was close to zero and was high in the rubbery intermediate layers, both as expected. However, the major component of the rigid cores of the rubber particles was found to be polypropylene rather than polyethylene, contrary to what was previously believed. The finding provides new insight into the complicated structure of HIPPs, and the AFM-IR quantitative method reported here offers a useful tool for assessing compositions of nanoscopic domains in complex polymeric systems. [ABSTRACT FROM AUTHOR]

Double network (DN) gels, consisting of a brittle first and flexible second network, have been known to be extremely tough and functional hydrogels. In a DN gel subjected to force, the brittle first network breaks prior to the fracture of the flexible network. This process, referred to as internal fracture, dissipates energy and increases the energy required to completely fracture DN gels. Such internal fracture macroscopically appears as a yielding-like phenomenon. The aim of this paper is to investigate the relationship between the yield point and the first network molecular structure of DN gels to more deeply understand the internal fracture mechanism of DN gels. To achieve this goal, we synthesized DN gels having a tetra-PEG first network, which is known to be a nearly ideal and well-controlled network gel. We have found that yielding of the DN gels occurs when the first network strands reach their extension limit (finite extensibility), regardless of their deformation mode. This conclusion not only helps by further understanding the toughening mechanism of DN gels but also allows for the design of DN gels with precisely controlled mechanical properties. [ABSTRACT FROM AUTHOR]

D609 (1) has been used as a lipid-related enzyme inhibitor during the past three decades. Although it has eight possible stereoisomers, no systematic research considering its chirality has been performed. In this paper, eight possible chiral alcohols as direct precursors of D609 were synthesized, and their stereochemistries were elucidated by a vibrational circular dichroism (VCD) technique. Phosphatidylcholine-specific phospholipase C and sphingomyelin synthase inhibition assays of these isomers showed considerable differences in their activities. [ABSTRACT FROM AUTHOR]

Thetranscription antiterminator RfaH has been shown to undergomajor structural rearrangements to perform multiple functions. Structuraldetermination of the C-terminal domain (CTD) of RfaH showed that itcan exist as either an α-helix bundle when interfacing withthe N-terminal domain (NTD) or as a β-barrel conformation whenit is not interfacing with the NTD. In this paper, we investigatethe full RfaH with both CTD and NTD using a variety of all-atom moleculardynamics (MD) simulation techniques, including targeted moleculardynamics, steered molecular dynamics, and adaptive biasing force,and calculate potentials of mean force. We also use network analysisto determine communities of amino acids that are important in transferringinformation about structural changes. We find that the CTD–NTDinterdomain interactions constitute the main barrier in the CTD α-helixto β-barrel structural conversion. Once the interfacial interactionsare broken, the structural conversion of the CTD is relatively easy.We determined which amino acids play especially important roles incontrolling the interdomain motions and also describe subtle structuralchanges that may be important in the functioning of RfaH. [ABSTRACT FROM AUTHOR]

This paper describes the dependence of the DC conductivity, film charging dynamics, and transient photocurrent dynamics of quasi-two-dimensional arrays of thiocyanate-capped PbS nanocubes (NCs) on the edge length of the NC. Arrays were prepared monolayer-by-monolayer using self-assembly at a liquid-air interface. Across-film conductivity increases with NC size with a dependence consistent with a simple diffusional hopping model. Upon application of a constant source-drain bias, the measured dark current decays exponentially to a nonzero steady-state value as immobile hole traps fill. Illumination with 532-nm light produces a repeatable photoresponse, which also fits to an exponential function. The lifetimes associated with decay of the dark current and growth of the photocurrent both increase with increasing NC size. Comparison of the electrical data with electron microscopy images reveals that this trend is related to the connectivity of the percolation networks within the film, which depends on the interparticle order and, in turn, on the edge length of the NCs. Correlations between interparticle order and electrical properties are made possible by the highly ordered films that result from the liquid-air interface deposition method. [ABSTRACT FROM AUTHOR]

In this paper, with the example of two different polymorphs of KEu(MoO4)2, the influence of the ordering of the A-cations on the luminescent properties in scheelite related compounds (A′,A″)n[(B′,B″)O4]m is investigated. The polymorphs were synthesized using a solid state method. The study confirmed the existence of only two polymorphic forms at annealing temperature range 923-1203 K and ambient pressure: a low temperature anorthic α-phase and a monoclinic high temperature β-phase with an incommensurately modulated structure. The structures of both polymorphs were solved using transmission electron microscopy and refined from synchrotron powder X-ray diffraction data. The monoclinic β-KEu(MoO4)2 has a (3+1)-dimensional incommensurately modulated structure (superspace group I2/b(αβ0)00, a = 5.52645(4) Å, b = 5.28277(4) Å, c = 11.73797(8) Å, γ = 91.2189(4)o, q = 0.56821(2)a*-0.12388(3)b*), whereas the anorthic α-phase is (3+1)-dimensional commensurately modulated (superspace group I1̅(αβγ)0, a = 5.58727(22) Å, b = 5.29188(18)Å, c = 11.7120(4) Å, α = 90.485(3)o, β = 88.074(3)o, γ = 91.0270(23)o, q = 1/2a* + 1/2c*). In both cases the modulation arises due to Eu/K cation ordering at the A site: the formation of a 2-dimensional Eu3+ network is characteristic for the α-phase, while a 3-dimensional Eu3+-framework is observed for the β-phase structure. The luminescent properties of KEu(MoO4)2 samples prepared under different annealing conditions were measured, and the relation between their optical properties and their structures is discussed. [ABSTRACT FROM AUTHOR]

The photoinduced E→ Zisomerization of azobenzene is a prototypicalexample of molecularswitching. On the way toward rigid molecular rods such as those foropto-mechanical applications, multiazobenzene structures have beensuggested in which several switching units are linked together withinthe same molecule (Bléger et al., J. Phys. Chem. B2011, 115, 9930–9940). Large differences inthe switching efficiency of multiazobenzenes have been observed, dependingon whether the switching units are electronically decoupled or not.In this paper we study, on a time-resolved molecular level, the E→Z isomerization of the simplest multiazobenzene, bisazobenzene (BAB).Two isomers (ortho-and para-BAB),differing only in the connectivity of two azo groups on a shared phenylring will be considered.To do so, nonadiabatic semiclassical dynamicsafter photoexcitation of the isomers are studied by employing an “on-the-fly”,fewest switches surface hopping approach. States and couplings arecalculated by Configuration Interaction (CI) based on a semiempirical(AM1) Hamiltonian (Persico and co-workers, Chem. Eur. J.2004, 10, 2327–2341). In the case of para-BAB, computed quantum yields for photoswitching aredrastically reduced compared to pristine azobenzene, due to electroniccoupling of both switching units. A reason for this (apart from alteredabsorption spectra and reduced photochromicity) is the drasticallyreduced lifetimes of electronically excited states which are transientlypopulated. In contrast for meta-connected species,electronic subsystems are largely decoupled, and computed quantumyields are slightly higher than that for pristine azobenzene becauseof new isomerization channels. In this case we can also distinguishbetween single- and double-switch events and we find a cooperativeeffect: The isomerization of a single azo group is facilitated ifthe other azo group is already in the Z-configuration. [ABSTRACT FROM AUTHOR]

The importance of reactions involving CO2, brine, and rock formations into which CO2 is injected for CO2 sequestration in saline aquifers is understood. However, the pore-level changes that occur due to these reactions under flow conditions and their impact on the ultimate fate of CO2 in the repository have not received the same level of attention because of the perceived slowness of the carbonation reactions. In this paper we examine these reactive changes and their impact on the pore structure in sandstones and limestones at realistic aquifer pressure and temperatures, and under reactive flow conditions. The changes observed at the pore-level by direct porosity and microcomputer tomography measurements were complemented by the measurements of time-dependent effluent concentrations of target cations. It is observed that iron chemistry plays an important role in the dissolution and precipitation reactions in Berea sandstone. Illite dissolution leads to a peak in iron concentration in effluent brines. A higher level of dissolution and an increased porosity are observed near the inlet of the core. In limestones, consistent dissolution is observed throughout the experiment. Wormholes are also generated for experiments with larger total flow rates. Results show that reactive changes can cause significant pore-level changes over a short injection span during CO2 sequestration in saline aquifers with profound implications on injectivity and possibly major mechanical changes. [ABSTRACT FROM AUTHOR]

Self-aggregation of the microtubule-bindingprotein Tau reducesits functionality and is tightly associated with Tau-related diseases,termed tauopathies. Tau aggregation is also strongly associated withtwo nucleating six-residue segments, namely PHF6 (VQIVYK) and PHF6*(VQIINK). In this paper, using experiments and computational modeling,we study the self-assembly of individual and binary mixtures of Taufragments containing PHF6* (R2/wt; 273GKVQIINKKLDL284) and PHF6 (R3/wt; 306VQIVYKPVDLSK317)and a mutant R2/ΔK280 associated with a neurodegenerative tauopathy.The initial stage of aggregation is probed by ion-mobility mass spectrometry,the kinetics of aggregation monitored with Thioflavin T assays, andthe morphology of aggregates visualized by transmission electron microscopy.Insights into the structure of early aggregates and the factors stabilizingthe aggregates are obtained from replica exchange molecular dynamicssimulations. Our data suggest that R3/wt has a much stronger aggregationpropensity than either R2/wt or R2/ΔK280. Heterodimers containingR3/wt are less stable than R3/wt homodimers but much more stable thanhomodimers of R2/wt and R2/ΔK280, suggesting a possible roleof PHF6*–PHF6 interactions in initiating the aggregation offull-length Tau. Lastly, R2/ΔK280 binds more strongly to R3/wtthan R2/wt, suggesting a possible mechanism for a pathological lossof normal Tau function. [ABSTRACT FROM AUTHOR]

The mammalian O-mannosylation pathway for protein post-translational modification is intricately involved in modulating cell-matrix interactions in the musculature and nervous system. Defects in enzymes of this biosynthetic pathway are causative for multiple forms of congenital muscular dystophy. The application of advanced genetic and biochemical technologies has resulted in remarkable progress in this field over the past few years, culminating with the publication of three landmark papers in 2013 alone. In this review, we will highlight recent progress focusing on the dramatic expansion of the set of genes known to be involved in O-mannosylation and disease processes, the concurrent acceleration of the rate of O-mannosylation pathway protein functional assignments, the tremendous increase in the number of proteins now known to be modified by O-mannosylation, and the recent progress in protein O-mannose glycan quantification and site assignment. Also, we attempt to highlight key outstanding questions raised by this abundance of new information. [ABSTRACT FROM AUTHOR]

Theincorporation of an organic group into sol–gel-derivedsilica causes significant changes in the structure and propertiesof these materials. Therefore, the thermal treatment of organosilicamaterials may require a different approach. In the present paper,kinetic parameters (activation energy, pre-exponential constant, andreaction models) have been determined from mass loss data for thedehydration, dehydroxylation, and decomposition reactions that takeplace upon heating silica and organosilica. Parameters were obtainedby employing model-free isoconversional methods to data obtained undermultiple heating rates as well as by multivariate analysis of thekinetics using a multistep reaction model with distributed activationenergy. For silica, it can be concluded that the reaction atmosphere(i.e., inert or thermo-oxidative) has no influence on the reactionrate of the dehydration and dehydroxylation reactions that are responsiblefor the densification of the material. Under inert atmosphere, fulldehydration can be reached without affecting the organic moiety. Achievingcomplete dehydroxylation of the organosilica is practically impossibleas decomposition does manifest itself under commonly employed calcinationtemperatures. This indicates that prudence is required in designinga heat treatment program for these hybrid materials. To aid in optimizingthe thermal treatment, a predictive model was developed, which canbe used to forecast the extent of dehydration, dehydroxylation, anddecomposition reactions under a multitude of temperature programs. [ABSTRACT FROM AUTHOR]

In this paper, various physical andchemical characteristics ofelectro-coagulated (ECC) and chemical-coagulated (CC) aluminum hydroxideflocs were explored comparatively in the context of their impactson the pollutant removal performance of the processes. First, thesedimentation rate, floc size and zeta potential of the flocs at differentpH values were measured in solution. Furthermore, flocs dried at 105°C were characterized by various techniques such as TGA,FT-IR,SEM, XRD, BET and XPS as well as by chemical analysis. It was foundthat ECC flocs were bigger in size, faster in sedimentation and betterpressed, while they had higher BET area, less water and higher isoelectricpH than CC flocs. Furthermore, pollutant removal tests using variouschemicals such as benzoquinone, hydroquinone and a reactive dye showedthat ECC flocs outperformed CC flocs, due to superior physical-chemicalcharacteristics. [ABSTRACT FROM AUTHOR]

Theeffective utilization of graphene in optoelectronic devicesrequires blending with other semiconductor materials, such as leadchalcogenide nanocrystals, and an understanding of the organic–inorganicinterface at the atomic level. In this paper, we present the firstreport of the successful self-assembly of close-packed monolayer arraysof PbTe nanocrystals on monolayer graphene. By using ultraclean chemicalvapor deposition grown graphene and aberration corrected transmissionelectron microscopy the unambiguous delineation of a ∼2 nmsoft ligand nanocrystal shell is achieved, which is compared to subsequentstudies after ligand exchange is performed on the same nanocrystal-graphenehybrid. Ligand exchange was shown to remove the soft ligand shellsurrounding the nanocrystals and to disassemble the close-packed monolayersinto amorphous nanocrystal aggregate film on the graphene substrate.Limited oriented attachment between nanocrystals in the anisotropicfilm was observed, and this was not significantly affected by extendedvacuum annealing. [ABSTRACT FROM AUTHOR]

In this paper, we report the synthesis and description of a new family of polynuclear cobalt(II) complexes. Starting from the same initial compounds but varying the reaction time results in the formation of several new clusters, an original structure based on [Co14][Co4] clusters was obtained, representing the first one-pot synthesis of a cobalt aggregate salt reported in the literature. The synthesis and magnetic properties of these cobalt compounds are discussed. Three of them display a binuclear molecular structure (1--3) with two encapsulated CoII ions and show slow relaxation of magnetization at small applied magnetic field (Ueff = 10.7 K for 2 and Ueff = 20.3 K for 3), a characteristic of single-molecule-magnet materials. [ABSTRACT FROM AUTHOR]

Whereas stable octanuclear clusters of the type M8I(E⋂E)6 (M = Cu, Ag; E⋂E = dithio or diseleno ligand) are known for being able to encapsulate a hydride or main-group anion under some circumstances, only the related hydride-containing heptanuclear [MI]7(H)(E⋂E)6 and empty hexanuclear [MI]6(E⋂E)6 species have been characterized so far. In this paper we investigate by the means of theoretical calculations and experiments the viability of empty and anion-centered clusters of the type [CuI]7(X)(E⋂E)6 and [CuI]6(X)(E⋂E)6 (X = vacancy, H or a main-group atom). The theoretical prediction for the existence of anion-containing heptanuclear species, the shape of which is modulated by the anion nature and size, have been fully confirmed by the synthesis and characterization of [Cu7(X){S2P(OiPr)2}6] (X = H, Br). This consistency between experiment and theory allows us to predict the stability and shape-modulated structure of a whole series of [CuI]7(X)(E⋂E)6 (X = vacancy, H, O, S, halogen) and [CuI]6(X)(E⋂E)6 (X = H, halogen) clusters. [ABSTRACT FROM AUTHOR]

Aiming to shed new light on the stabilityand constitution of theorganometallic intermediates involved in direct ortho-metalation processes, using trifluoromethylbenzene (1) as a case study, this paper investigates the deprotonation of 1using group 1 alkyl bases tBuLiand nBuNa in the presence of the Lewisdonors TMEDA (N,N,N′,N′-tetramethylethylenediamine),THF, and PMDETA (N,N,N′,N″,N″-pentamethyldiethylenetriamine).A systematic and comprehensive study combining structural, spectroscopic,and theoretical studies reveals that these donors strongly influencethe final outcome of the reactions, not only by activating the alkali-metalbases and facilitating deprotonation of 1but also bytuning the regioselectivity of the reaction. Thus, while using tBuLi/TMEDA, ortho-metalationof 1is preferred, switching to THF gives a complex mixtureof products with the meta-regioisomer being the majorspecies crystallizing from hexane solution. This donor effect is significantlyreduced when nBuNa is employed, as ortho-regioselectivity is observed almost exclusively usingTHF, TMEDA, or PMDETA. DFT calculations computing the relative energiesof the ortho-, meta-, and para-regioisomers obtained from these metalating systemshave also been carried out. Reinforcing the experimental findings,these theoretical studies show that although in all cases the productof ortho-metalation is the most thermodynamicallypreferred, the energy difference between the three possible modeledregioisomers is much larger for the Na systems than for the Li ones.The structures of key reaction intermediates [(TMEDA)·Li(C6H4-CF3)]2(2), [(TMEDA)·Na(C6H4-CF3)]2(3), and [(PMDETA)·Na(C6H4-CF3)]2(4) have been elucidatedby X-ray crystallographic studies. All compounds exhibit a similardimeric arrangement with a four-atom core constituting a {MCMC} ring.Interestingly for Na derivatives 3and 4unusual Na···F dative interactions are found, whichappear to contribute to the overall stability of these compounds,therefore favoring ortho-metalation of 1, as the metaor parastructuresdo not contain these additional interactions. [ABSTRACT FROM AUTHOR]

Predicting the complete electronic structure of carotenoidmoleculesremains an extremely complex problem, particularly in anisotropicmedia such as proteins. In this paper, we address the electronic propertiesof nine relatively simple carotenoids by the combined use of electronicabsorption and resonance Raman spectroscopies. Linear carotenoidsexhibit an excellent correlation between (i) the inverse of theirconjugation chain length N, (ii) the energy of theirS0→ S2electronic transition, and (iii)the position of their ν1Raman band (correspondingto the stretching mode of their conjugated CC bonds). Forcyclic carotenoids such as β-carotene, this correlation is alsoobserved between the latter two parameters (S0→S2energy and ν1frequency), whereas their“nominal” conjugation length Ndoesnot follow the same relationship. We conclude that β-caroteneand cyclic carotenoids in general exhibit a shorter effective conjugationlength than that expected from their chemical structure. In addition,the effect of solvent polarizability on these molecular parameterswas investigated for four of the carotenoids used in this study. Wedemonstrate that resonance Raman spectroscopy can discriminate betweenthe different effects underlying shifts in the S0→S2transition of carotenoid molecules. [ABSTRACT FROM AUTHOR]

In this paper, we present the phase diagram and magnetic properties of the layered Co2+-based compounds of formula Ba(CoPO4)2 for which the rhombohedral y form is well-known for its quasi-2D XY topology that is responsible for magnetization steps. The structural resolution of the new, room temperature-stable monoclinic a form shows similitude with the hydrated homologue Ba(CoPO4)2H2O and consists of the stacking between [CoPO4]- sheets with chain subunits. We show by means of high temperature powder XRD and thermal analyses that the a form transforms into several polymorphs also exhibiting layered architectures upon heating. Three reversible transitions at 773, 893, and 993 K were observed from DTA which allowed us to define several forms as follows: α -> α' -> α" -> β. The crystallographic relationships between the several polymorphs and hydrate analogue are discussed. The α' and α" cell parameters involve a direct relationship with the a form, whereas the trigonal ß phase was iully solved and found isomorphic with the compounds CaZn2P2O8 and BaAl2Si2O8. The magnetic study of the a form shows an antiferromagnetic ordering at TN = 17 K, with spins canting below TN. Then, the analysis of die magnetic interactions paths occurring within the layers evidence superexchange paths and additional supersuperexchange paths between the chains. This scheme leads to a hexagonal frustrated topology responsible for the canted spin structure in a 2D-topology of anisotropic Co2+ magnetic ions. [ABSTRACT FROM AUTHOR]

Proper selection of silane precursorsand polymer reinforcementsyields more durable and stronger silica aerogels. This paper focuseson the use of silane-end-capped urethane prepolymer and chain-extendedpolyurethane for reinforcement of silica aerogels. The silane endgroups were expected to participate in silica network formation anduniquely determine the amounts of urethanes incorporated into theaerogel network as reinforcement. The aerogels were prepared by one-stepsol–gel process from mixed silane precursors tetraethoxysilane,aminopropyltriethoxysilane (APTES), and APTES-end-capped polyurethanes.The morphology and mechanical and surface properties of the resultantaerogels were investigated in addition to elucidation of chemicalstructures by solid-state 13C and 29Si nuclearmagnetic resonance. Modification by 10 wt % APTES-end-capped chain-extendedpolyurethane yielded a 5-fold increase in compressive modulus and60% increase in density. APTES-end-capped chain-extended polyurethanewas found to be more effective in enhancement of mechanical propertiesand reduction of polarity. [ABSTRACT FROM AUTHOR]

Structured packings are widely usedin many separation processes.In this paper, the liquid film flow behavior as well as mass transferefficiency on the novel and the traditional structured packings isinvestigated after being simplified into multibaffled and inclinedplate, respectively. The novel structured packing has a number ofopenings punched through the ridges on the inner and outer sides ofthe packing surface, and this structure corresponds to a certain flowpattern that influences mass transfer processes other than the traditionalones. The CFD method and VOF model are applied to investigate thevapor–liquid two-phase flow behavior and mass transfer process.Isopropanol desorption on the two kinds of plates is studied experimentallyand numerically, and the experimental and simulation results are ingood agreement. A significantly higher mass transfer efficiency ofthe multibaffled plate is observed, and the simulation results indicatesuccessfully that the higher mass transfer efficiency on the novelstructured packing results from the increased renewal rate and disturbanceof liquid film flow. [ABSTRACT FROM AUTHOR]

This paper reports studies on CO2capturetechnologiesand presents the mathematical modeling, simulation, and optimizationof adsorption-based process alternatives, namely, pressure swing adsorption(PSA) and vacuum swing adsorption (VSA). Each technology includesfeed dehydration, capture of at least 90% of CO2from thefeed, and compression to almost pure CO2for sequestrationat 150 bar. Each process alternative is optimized over a range of feed CO2compositions andflow rates. A superstructure of alternatives is developed to selectthe optimum dehydration strategy for feed to each process. A four-stepprocess with pressurization, adsorption in multiple columns packedwith 13X zeolite, N2purging, and product recovery at moderateto low vacuum is configured. A nonlinear algebraic and partial differentialequation (NAPDE) based nonisothermal adsorption model is used, whichis fully discretized and solved via a kriging model. Explicit expressionsfor costs as functions of feed flow rate and CO2compositionare also developed for the PSA- and VSA-based CO2captureand compression for the first time. Furthermore, a cost-based comparisonof four leading CO2capture technologies, namely, absorption-,membrane-, PSA-, and VSA-based processes, is presented over a rangeof flue gas compositions and flow rates. This enables selection ofthe most cost-effective CO2capture and storage (CCS) technologyfor diverse emission scenarios. Results indicate that CO2can be captured with the least cost using a MEA-based chemical absorptionwhen the feed CO2composition is less than 15–20%.For higher CO2compositions, VSA is the preferred process. [ABSTRACT FROM AUTHOR]

Controland operation of energy-efficient dividing-wall columnscan be challenging. This paper demonstrates experimentally the start-upand steady state operation of a four-product Kaibel column separatingmethanol, ethanol, propanol, and n-butanol. We usea control structure with four temperature controllers and show thatit can handle feed rate disturbances as well as set point changes.The experiments compare well with an equilibrium stage model. [ABSTRACT FROM AUTHOR]

In this paper, we present MolFind, a highly multithreaded pipeline type software package for use as an aid in identifying chemical structures in complex biofluids and mixtures. MolFind is specifically designed for high-performance liquid chromatography/mass spectrometry (HPLC/MS) data inputs typical of metabolomics studies where structure identification is the ultimate goal. MolFind enables compound identification by matching HPLC/MS-based experimental data obtained for an unknown compound with computationally derived HPLC/MS values for candidate compounds downloaded from chemical databases such as PubChem. The downloaded "bins" consist of all compounds matching the monoisotopic molecular weight of the unknown. The computational HPLC/MS values predicted include retention index (RI), ECOM50 (energy required to fragment 50% of a selected precursor ion), drift time, and collision induced dissociation (CID) spectrum. RI, ECOM50, and drift-time models are used for filtering compounds downloaded from PubChem. The remaining candidates are then ranked based on CID spectra matching. Current RI and ECOM50 models allow for the removal of about 28% of compounds from PubChem bins. Our estimates suggest that this could be improved to as much as 87% with additional chemical structures included in the computational models. Quantitative structure property relationship-based modeling of drift times showed a better correlation with experimentally determined drift times than did Mobcal cross-sectional areas. In 23 of 35 example cases, filtering PubChem bins with RI and ECOM50 predictive models resulted in improved ranking of the unknown compounds compared to previous studies using CID spectra matching alone. In 19 of 35 examples, the correct candidate was ranked within the top 20 compounds in bins containing an average of 1635 compounds. [ABSTRACT FROM AUTHOR]

Ion-conducting polymers are ideal solid electrolytesfor most energystorage and conversion devices where ion transport is a critical functionality.The system performance and stability are related to the transportand mechanical properties of the ionomers, which are correlated throughphysiochemical interactions and morphology. Thus, there exists a balancebetween the chemical and mechanical energies which controls the structure–functionrelationship of the ionomer. In this paper, it is reported how andwhy thermal treatments result in different water uptakes and nanostructuresfor a perfluorinated sulfonic acid (PFSA) membrane. The nanostructureof the PFSA membrane is characterized using small- and wide-angleX-ray scattering experiments. These changes are correlated with watercontent and mechanical properties and result in fundamental relationshipsto characterize the membrane with different thermal histories. Moreover,quasi-equilibrium water uptake and domain spacing both decrease withpredrying or preconstraining the membrane, thereby suggesting thatsimilar mechanical energies govern the structural changes via internaland external constraints, respectively. The findings suggest thatheat treatments alter the balance between the chemical–mechanicalenergies where the interplay of the morphology and mechanical propertiescontrols the structure–function relationship of the membrane.Finally, a model is developed using an energy-balance approach withinputs of the mechanical and structural properties; the dependenceof water uptake on pretreatment is successfully predicted. [ABSTRACT FROM AUTHOR]

The polycyclic ether class of marine natural products has attracted the attention of researchers due to their complex and large chemical structures and diverse biological activities. Gambierol is a marine polycyclic ether toxin, first isolated along with ciguatoxin congeners from the dinoflagellate Gambierdiscus toxicus. The parent compound gambierol and the analogues evaluated in this work share the main crucial elements for biological activity, previously described to be the C28C29 double bond within the H ring and the unsaturated side chain [ Fuwa H. , Kainuma N. , Tachibana K. , Tsukano C. , Satake M. , and Sasaki M. (2004) Diverted total synthesis and biological evaluation of gambierol analogues: Elucidation of crucial structural elements for potent toxicity. Chem. Eur. J. 10 , 4894 − 4909 ]. With the aim to gain a deeper understanding of the cellular mechanisms involved in the biological activity of these compounds, we compared its activity in primary cultured neurons. The three compounds inhibited voltage-gated potassium channels (Kv) in a concentration-dependent manner and with similar potency, caused a small inhibition of voltage-gated sodium channels (Nav), and evoked cytosolic calcium oscillations. Moreover, the three compounds elicited a "loss of function" effect on Kv channels at concentrations of 0.1 nM. Additionally, both the tetracyclic and the heptacyclic derivatives of gambierol elicited synchronous calcium oscillations similar to those previously described for gambierol in cultured cerebellar neurons. Neither gambierol nor its tetracyclic derivative elicited cell toxicity, while the heptacyclic analogue caused a time-dependent decrease in cell viability. Neither the tetracyclic nor the heptacyclic analogues of gambierol exhibited lethality in mice after ip injection of 50 or 80 μg/kg of each compound. Altogether, the results presented in this work support an identical mechanism of action for gambierol and its tetracyclic and heptacyclic analogues and indicate a "loss of function" effect on potassium channels even after administration of the three compounds at subnanomolar concentrations. In addition, because gambierol is known to stabilize the closed state of Kv3 channels, the results presented in this paper may have implications for understanding of channel functions and for future development of therapies against ciguatera poisoning and potassium channel-related diseases. [ABSTRACT FROM AUTHOR]

In this paper, an unstable chiral drug l-alanyl-glutamine(l-(Ala-Gln)) was intercalated into layered double hydroxides(LDHs) and a systematic study combining experimental and theoreticalinvestigation was carried out. Structural characterization revealsthe microstructure of LDHs and properties of the intercalated l-(Ala-Gln). Solid-state UV–vis spectroscopy is adoptedto observe the energy absorption. This result shows that LDHs canblock the UV light, and inhibition of configuration conversion worksin the LDH host. Circular dichroism (CD) spectra suggest that theintercalated l-(Ala-Gln) can maintain its configuration inthe interlayer even when irradiated under UV light. Density functionaltheory (DFT) computations at the B3PW91/6-31G(d, p) level have beencarried out to understand the mechanism of l-(Ala-Gln) racemization.The computed result demonstrates that the thermal energy based onthe reaction temperature cannot support l-(Ala-Gln) to givean excited state, but it can be excited under the irradiation of UVlight with a wavelength less than 240 nm and undergoes conformationaltransition. When intercalated in the interlayer of LDHs, l-(Ala-Gln) is involved in strong guest–host interaction withthe layers and thus inhibition of configuration conversion is effectivein the LDH interlayer. [ABSTRACT FROM AUTHOR]

In this paper, we studied the synthesis, characterization,andflammability of the water-soluble, nonhalogenated organophosphorusflame retardant (FR) dimethyl-[1,3,5-(3,5-triacryloylhexahydro)triazinyl]-3-oxopropylphosphonatefor application to cotton fabrics by nonpolymeric network. The FRwas synthesized in a one-step reaction from dimethyl phosphite and1,3,5-triacryloylhexahydro-1,3,5-triazine under mild conditions, andits structure was fully characterized by 1H, 13C, and 31P nuclear magnetic resonance (NMR), mass spectrometry(MS), and Fourier transform infrared spectroscopy (FT-IR). The finishingconditions to achieve a covalent bond between the FR and fibers wereoptimized, and the FR capability of the treated cotton was investigatedby limiting oxygen index (LOI), flame test, thermogravimetric analysis(TGA), and micro cone calorimeter (MCC) tests. This study showed thatfabrics treated with the FR are effectively flame resistant, and theFR property is enhanced by covalent bonding of the FR to fibers. [ABSTRACT FROM AUTHOR]

This paper presents the synthesis and characterizationof new homoleptic lithium magnesiate reagents incorporating the silyl-substitutedalkyl ligand CH2SiMe3in the presence of a varietyof Lewis base donors, namely tetrahydrofuran (THF), 1,4-dioxane, N,N,N′,N′-tetramethylethylenediamine (TMEDA), and N,N,N′,N″,N″-pentamethyldiethylenetriamine(PMDETA). The constitution of these bimetallic compounds has beenassessed in both the solid state and solution using a combinationof X-ray crystallographic studies and multinuclear NMR spectroscopy,including 1H diffusion-ordered (1H-DOSY) NMRexperiments. These studies highlight the major role played by thedonor molecule in controlling the structure of the complexes as wellas the wide structural diversity available for these mixed-metal speciesranging from discrete molecules, as found for [(PMDETA)LiMg(CH2SiMe3)3] (6), to more complexsupramolecular arrangements, as in the 1D-polymeric chain [{(THF)LiMg(CH2SiMe3)3}∞] (2) or in the stoichiometrically distinct dioxane solvates[{(dioxane)2LiMgR3}∞] (3) and [{(dioxane)Li2Mg2R6}∞] (4). Furthermore, these studieshave also revealed that in some cases the donor molecule can promotea redistribution process, as shown for the reaction of triorganomagnesiate[LiMg(CH2SiMe3)3] (1) with 1 molar equiv of TMEDA, which led to the formation of lithium-richtetraorganomagnesiate [(TMEDA)Li2Mg(CH2SiMe3)4] (5) along with Mg(CH2SiMe3)2. The formation of the unprecedentedcationic lithium magnesiate [{(PMDETA)2Li2Mg(CH2SiMe3)3}+{Mg3(CH2SiMe3)6(OCH2SiMe3)}−] (7) is also described, by thecontrolled exposure to oxygen of the monomeric compound [(PMDETA)LiMg(CH2SiMe3)3] (6). [ABSTRACT FROM AUTHOR]

In this paper we report the synthesis and structural characterization of the 2D layered coordination polymer Mg(BPMGLY)(H20)2 (BPMGLY = bis-phosphonomethylglydne, (H03PCH2)2N(H)C002- ) . The Mg ion is found in a slightly distorted octahedral environment formed by four phosphonate oxygens and two water molecules. The carboxylate group is deprotonated but noncoordinated. This compound is a useful starting material for a number of topotactic transformations. Upon heating at 140 °C one (of the two) Mg-coordinated water molecule is lost, with the archetype 2D structure mamtaining itself. However, the octahedral Mg in Mg(BPMGLY)(H20)2 is now converted to trigonal bipyramidal in Mg(BPMGLY)(H20). Upon exposure of the monohydrate Mg(BPMGLY)(H20) compound to ammonia, one molecule of ammonia is inserted into the interlayer space and stabilized by hydrogen bonding. The 2D layered structure of the product Mg(BPMGLY)(H20)(NH3) is still maintained, with Mg now acquiring a pseudo-octahedral environment. All of these topotactic transformations are also accompanied by changes in hydrogen bonding between the layers. [ABSTRACT FROM AUTHOR]

The existence of ellipsoidal micelles in aqueous solutionhas been debated in the literature. Although a number of experimentalstudies suggest that certain surfactants form ellipsoidal micelles,many theoretical studies have claimed that micelles with an ellipsoidalshape cannot exist. To shed light on this topic, in this paper, wedevelop a curvature-corrected, molecular-thermodynamic model for thefree energy of micellization of nonionic surfactant biaxial ellipsoidalmicelles. We subsequently use this model to evaluate the feasibilityof forming ellipsoidal micelles, compared to forming spherical, spherocylindrical,and discoidal micelles, and conclude that ellipsoidal micelles canexist in solution. Utilizing the model developed here, we also establishtheoretical limits on the size of the ellipsoidal micelles. Theselimits depend solely on the chemical structure of the surfactant molecule. [ABSTRACT FROM AUTHOR]

This paper presents a novel in situmethodto prepare monodispersed palladium nanoparticles supported on porousglass beads with an egg-shell structure at room temperature. Thismethod integrates two processes of ion exchange and reduction in onestep just by changing the solvent from water to alcohol. The monodispersedPd nanoparticles around 3.75 nm in diameter with a face-centered cubicstructure have been successfully prepared. The adsorption capacityfor palladium reached 55.00 ± 0.55 mg/g in ethanol, which was26 times larger than that in water. These Pd nanoparticles supportedon porous glass beads showed an excellent catalytic performance throughthe hydrogenation of cyclohexene. In addition, this in situmethod was also successfully applied to prepare monodispersed silverand gold nanoparticles supported on porous glass beads. Overall, thisfacile method provided an alternative for preparing a supported nanoparticlecatalyst in a green way. [ABSTRACT FROM AUTHOR]

Surface-enhanced resonance Raman scattering (SERRS) spectroscopy is a highly sensitive optical technique capable of detecting multiple analytes rapidly and simultaneously. There is significant interest in SERRS detection in micro- and nanotechnologies, as it can be used to detect extremely low analyte concentrations in small volumes of fluids, particularly in microfluidic systems. There is also rapidly growing interest in the field of microdroplets, which promises to offer the analyst many potential advantages over existing technologies for both design and control of microfluidic assays. While there have been rapid advances in both fields in recent years, the literature on SERRS-based detection of individual microdroplets remains lacking. In this paper, we demonstrate the ability to quantitatively detect multiple variable analyte concentrations from within individual microdroplets in real time using SERRS spectroscopy. We also demonstrate the use of a programmable pump control algorithm to generate concentration gradients across a chain of droplets. [ABSTRACT FROM AUTHOR]