The Role of Solvent Ligated Metal Complexes Associated with Weakly Coordinating Counteranions (WCAs) in Isobutylene Polymerization

Summary: Polyisobutylene is an industrially important polymer which is conventionally prepared by polymerization at temperatures below 0 °C. The application of solvent ligated metal complexes associated with weakly coordinating counteranions (WCAs), however, allows the room temperature (30 °C) polymerization of isobutylene resulting in highly reactive polyisobutylene (HR-PIB) containing a high content of terminal double bonds. Recently described complexes include manganese (II), copper(II), molybdenum(III) and zink(II) complexes which were coordinated octahedrally with the boron and alumina based WCAs, each with its own advantages and traits.     

Estimation of Joule heating effect on temperature and pressure distribution in electrokinetic-driven microchannel flows

In this study we present simple analytical models that predict the temperature and pressure variations in electrokinetic-driven microchannel flow under the Joule heating effect. For temperature prediction, a simple model shows that the temperature is related to the Joule heating parameter, autothermal Joule heating parameter, external cooling parameter, Peclet number, and the channel length to channel hydraulic diameter ratio. The simple model overpredicted the thermally developed temperature compared with the full numerical simulation, but in good agreement with the experimental measurements. The factors that affect the external cooling parameters, such as the heat transfer coefficient, channel configuration, and channel material are also examined based on this simple model. Based on the mass conservation, a simple model is developed that predicts the pressure variations, including the temperature effect. An adverse pressure gradient is required to satisfy the mass conservation requirement. The temperature effect on the pressure gradient is via the temperature-dependent fluid viscosity and electroosmotic velocity.     

Multifunctional carbon-coated magnetic sensing graphene oxide-cyclodextrin nanohybrid for potential cancer theranosis

Journal of Nanoparticle Research - Over the last years, an environmentally friendly and economically efficient way of nanoparticle production has been found in the biosynthesis of metal...     

Downward self‐polarization of lead‐free (K0.5Na0.5)(Mn0.005Nb0.995)O3 ferroelectric thin films on Nb:SrTiO3 substrate

Spontaneously appearing macroscopic polarization (self‐polarization) in ferroelectrics without an electrode or an external electric field would enable the freedom to design many ferroelectric heterostructures and devices. The (K_0.5Na_0.5)(Mn_0.005Nb_0.995)O₃ (KNMN) thin film was grown on Nb:SrTiO₃ single‐crystal substrate and the resultant self‐polarization behavior due to strain relaxation was investigated. The lattice mismatch and difference in TEC between the KNMN thin film and the Nb:SrTiO₃ substrate creates a compressive strain. The compressive strain gradient may be the main cause for the observed downward self‐polarization. The downward self‐polarization of the KNMN thin film can be explained by the strong inhomogeneous compressive strain caused by strain relaxation. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

Effects of Cu2−xS phase removal on surface potential of Cu2ZnSnS4 thin-films grown by electroplating

Cu₂ZnSnS₄ (CZTS) has an optical band gap of 1.4–1.5 eV, which is similar to that of Cu(In,Ga)Se₂ (CIGS), and a high absorption coefficient (>10⁴ cm⁻¹) in the visible light region. In previous reports, CIGS thin-film solar cells have been shown to improve the performance of the device since the secondary phase is removed by Potassium cyanide (KCN) etching treatment. Therefore, in this study we applied a KCN etching treatment on CZTS and measured the effects. We confirmed the removal of Cu_2−xS via Kelvin probe force microscopy (KPFM) and Raman scattering spectroscopy. The effects of the experiment indicate that we can define with precision the location of the secondary phases, and therefore the control of the secondary phases will be easier and more efficient. Such capabilities could improve the solar cell performance of CZTS thin-films.     

A lectin-coupled,multiple reaction monitoring based quantitative analysis of human plasma glycoproteins by mass spectrometry

Aberrant protein glycosylation may be closely associated with cancer pathology. To measure the abundance of protein glycoforms with a specific glycan structure in plasma samples, we developed a lectin-coupled multiple reaction monitoring (MRM)-based mass spectrometric method. It was confirmed that the method could provide reproducible results with precision sufficient to distinguish differences in the abundance of protein glycoforms between individuals. Plasma samples prepared from hepatocellular carcinoma (HCC) patients without immuno-depletion of highly abundant plasma proteins were fractionated by use of fucose-specific aleuria aurantia lectin (AAL) immobilized on magnetic beads by use of a biotin–streptavidin conjugate. The lectin-captured fractions were digested by trypsin and profiled by tandem mass spectrometry. From the proteomic profiling data, target glycoproteins were selected and analyzed quantitatively by MRM-based analysis. The reproducibility of MRM-based quantification of the selected target proteins was reliable, with precision (CV; ≤14% for batch-to-batch replicates and ≤19% for replicates over three days) sufficient to distinguish differences in the abundance of AAL-captured glycoforms between individual plasma samples. This lectin-coupled, MRM-based method, measuring only lectin-captured glycoforms of a target protein rather than total target protein, is a tool for monitoring differences between individuals by measuring the abundance of aberrant glycoforms of a target protein related to a disease. This method may be further applied to rapid verification of biomarker candidates involved in aberrant protein glycosylation in human plasma.     

Highly interconnected ordered mesoporous carbon-carbon nanotube nanocomposites: Pt-free, highly efficient, and durable counter electrodes for dye-sensitized solar cells

We report the preparation of highly interconnected ordered mesoporous carbon-carbon nanotube nanocomposites which show Pt-like dye-sensitized solar cell (DSSC) efficiency and remarkable long-term durability as DSSC counter electrodes.     

Direct Synthesis of PbO Nanoparticles From a Lead(II) Nano Coordination Polymer Precursor: Synthesis,Crystal Structure,and DFT Calculations of [Pb2(dmp)2(μ‐N3)2(μ‐ClO4)2]n with the First Pb2‐(μ‐ClO4)2 Unit

Nanostructures of a new coordination polymer of divalent lead with the ligand 2, 9‐dimethyl‐1, 10‐phenanthroline (dmp) containing the first Pb₂‐(μ‐ClO₄)₂ motif, [Pb₂(dmp)₂(μ‐N₃)₂(μ‐ClO₄)₂]_n ( 1 ), was synthesized by a sonochemical method that produces the coordination polymers at nano size. The new nanostructure was characterized by scanning electron microscopy, X‐ray powder diffraction, IR, ¹H NMR and ¹³C NMR spectroscopy, and elemental analysis. Compound 1 was structurally characterized by single‐crystal X‐ray diffraction and the single‐crystal X‐ray data shows that the coordination number of Pb^II ions is six, (PbN₄O₂), with two N‐donor atoms from aza‐aromatic base ligands and four O‐donors from two perchlorate anions and two N‐donors from two azide anions. It has a “stereo‐chemically active” electron lone pair, and the coordination sphere is hemidirected. The supramolecular features in these complexes are guided and controlled by weak directional intermolecular interactions. The chains interact with each other through π–π stacking interactions creating a 3D framework. The structure of the title complex was optimized by density functional theory calculations. Calculated structural parameters and IR spectra for the title complex are in agreement with the crystal structure. The PbO nanoparticles were obtained by thermolysis of 1 at 180 °C with oleic acid as a surfactant. The average diameter of the nanoparticles was estimated by the Scherrer equation to be 23 nm. The morphology and size of the prepared PbO samples were further observed using SEM.     

Reactive Polymer Coatings: A General Route to Thiol‐ene and Thiol‐yne Click Reactions

Reactive polymer coatings were synthesized via chemical vapor deposition (CVD) polymerization process. These coatings decouple surface design from bulk properties of underlying materials and provide a facile and general route to support thiol‐ene and thiol‐yne reactions on a variety of substrate materials. Through the reported technique, surface functions can be activated through a simple design of thiol‐terminated molecules such as polyethylene glycols (PEGs) or peptides (GRGDYC), and the according biological functions were demonstrated in controlled and low‐fouling protein adsorptions as well as accurately manipulated cell attachments.     

层状配位聚合物犤Pb(NCS)_2(bpea)_n的合成,结构和非线性光学性质(bpea=1,2-双(4-吡啶基)乙烷)(英文)

室温下Pb(OAC)2·3H2O,KNCS,和1,2-双(4-吡啶基)乙烷在甲醇中反应生成了八员环支撑的层状配位聚合物犤Pb(NCS)2(bpea)犦n。三阶非线性Z-扫描研究表明该化合物具有非线性折射行为:其非线性吸收系数α2=1.1×10-11m·W-1,非线性折射系数n2=6.055×10-18m2·W-1。