Two-dimensional nanomaterial based sensors for heavy metal ions

Two-dimensional (2D) nanomaterials are promising building blocks for sensors due to their unique physical, chemical, electronic, and optical properties. This review (with 253 references) first summarizes the historical developments of 2D nanomaterials and discusses the advantages of 2D nanomaterials when applied for constructing sensors. Next, their properties are discussed, with subsections on electronic, optical, mechanical and chemical properties. This is followed by an overview on methods for syntheses and the effects of positive and/or negative charges on the properties and in sensing applications. Then, recent advances in 2D nanomaterial-based electrochemical, fluorometric, colorimetric, electrochemiluminescent, photoelectrochemical, and field-effect transistor sensors are discussed. The discussion also includes the preparation of sensing elements, the roles of such nanomaterials, and assay strategies. Finally, on the basis of the current achievements in the field of 2D nanomaterials, the perspectives on the challenges and opportunities for the exploration of 2D nanomaterial-based sensors are put forward.

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Properties of ZnO nanocrystals prepared by radiation method

Zinc oxide nanoparticles were prepared by irradiation of aqueous solutions containing zinc(II) ions, propan-2-ol, polyvinyl alcohol, and hydrogen peroxide. Zinc oxide was found in solid phase either directly after irradiation, or after additional heat treatment. Various physicochemical parameters, including scintillation properties of prepared materials, were studied. After decomposition of impurities and annealing of oxygen vacancies, the samples showed intensive emission in visible spectral range and well-shaped exciton luminescence at 390–400 nm. The best scintillating properties had zinc oxide prepared from aqueous solutions containing zinc formate as initial precursor and hydrogen peroxide. Size of the crystalline particles ranged from tens to hundreds nm, depending on type of irradiated solution and post-irradiation thermal treatment.     

Material properties of anisotropic materials with pores

An approach based on cavity compliance contribution tensor is utilized for evaluation of effective stiffness of anisotropic materials with irregularly shaped pores. The shapes considered in the present work were extracted from the X-ray computed microtomography of a carbon/carbon composite sample. The cavity contribution tensors of individual pores were calculated numerically and then employed in the micromechanical modeling procedure. It was shown that presence of pores with total porosity of p = 9.13% results in approximately 20% reduction in the material's Young's moduli. (© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Reactions of benzopinacol with group 13 alkyl metals:: Crystal structure of Me6In4[OC(C6H5)2C(C6H5)2O]2(OCH3)2, a new alkylalkoxo indium diolate

Reactions of Me₅Al₃[OC(C₆H₅)₂C(C₆H₅)₂O]₂ (1) with alcohols ROH (R = Me, Et, ^tBu) in a 1:1 molar ratio afforded the compound Me₂Al₂[OC(C₆H₅)₂C(C₆H₅)₂O]₂(C₄H₈O) (2) and a mixture of methylaluminum alkoxides. The alcohols acted as the factor formally eliminating a molecule of Me₃Al (as a methylaluminum alkoxide) from compound 1. ^tBu₃Al reacted with an equimolar amount of benzopinacol to form the monomeric complex ^tBuAl[OC(C₆H₅)₂C(C₆H₅)₂O](C₄H₈O) (3). Reactions of Me₃Ga and Me₃In with benzopinacol yielded trinuclear complexes Me₅M₃[OC(C₆H₅)₂C(C₆H₅)₂O]₂ (4 (M = Ga), 5 (M = In)), isostructural to compound 1. In the presence of water and alcohols, compounds 4 and 5 underwent a decomposition reaction to benzopinacol and a mixture of metalloxanes and alkoxides. An unusual methylmethoxo indium benzopinacolate Me₆In₄[OC(C₆H₅)₂C(C₆H₅)₂O]₂(OCH₃)₂ (6) was obtained in the reaction of benzopinacol with Me₃In and Me₂InOMe in a 1:1:1 molar ratio. Molecular structures of the compounds 3, 4 and 6 were determined by X-ray crystallography.     

Synthesis and Characterization of Oxazaborinin Phosphonate for Blue OLED Emitter Applications

A blue-light emitting material based on a boron complex containing heteroaromatic phosphonate ligand is synthesized and characterized. The Phospho-Fries rearrangement is used in the synthesis route of the ligand as a convenient method of introducing phosphonate groups into phenols. Structural, thermal and photophysical properties of the resulting oxazaborinin phosphonate compound have been characterized. DFT geometry optimizations were studied as well as the spatial position and symmetry of the HOMO and LUMO. Good thermal stability up to 250 °C enables vacuum deposition methods next to solution processing. Combining the work function with the optical band gap from UV-Vis measurements shows that band alignment is possible with standard contact materials. Photoluminescence reveals an emission peak at 428 nm, which is suitable for a blue light-emitter.     

Reactions of hydroxymesitylboranes with metal alkyls: an approach to new sterically hindered (metaloxy)mesitylboranes

Reactions of mesitylboronic acid with alkyl derivatives of aluminum R(3)Al (R = Me, Et, Bu(i)), gallium (Me(3)Ga), and zinc (Et(2)Zn) were investigated. The treatment of mesitylboronic acid, MesB(OH)(2), with trimethylgallium afforded the discrete dimer [mu-(MesB(OH)O)GaMe(2)](2) (1), which is the simple example of a O-metalated boronic acid with no hydrogen bonding in the crystal lattice. In addition, the reaction of dimesitylborinic acid, Mes(2)BOH, with diethylzinc produced the low-valent zinc compound [(mu-Mes(2)BO)ZnEt](2) (2), which was also characterized by X-ray diffraction.     

Bayesian modeling of forestry data with R using optimization and simulation tools

Data generated in forestry biometrics are not normal in statistical sense as they rarely follow the normal regression model. Hence, there is a need to develop models and methods in forest biometric applications for non-normal models. Due to generality of Bayesian methods it can be implemented in the situations when Gaussian regression models do not fit the data. Data on diameter at breast height (dbh), which is a very important characteristic in forestry has been fitted to Weibull and gamma models in Bayesian paradigm and comparisons have also been made with its classical counterpart. It may be noted that MCMC simulation tools are used in this study. An attempt has been made to apply Bayesian simulation tools using \textbf{R} software.     

Incorporation of Ce3+ in crystalline Gd-silicate nanoclusters formed in silica

Structural and optical properties of sol–gel silica based glassceramics doped with 0.1 mol% Ce and codoped with Gd at high concentrations, from 5 mol% up to 40 mol%, are investigated and compared to those of analogous samples doped only with Ce. Raman scattering, transmission electron microscopy, and x-ray diffraction reveal the formation of Gd apatite-like silicate (Gd_4.67O(SiO₄)₃) and of Gd pyrosilicate (Gd₂Si₂O₇) nanophases whose morphology and crystallinity depend on the Gd concentration and thermal treatments. Optical absorption measurements demonstrate the role of the densification atmosphere in modifying the charge state of Ce ions. The incorporation of Ce³⁺ ions in the nanophases is put in evidence by photo- and radio-luminescence results.     

The Σp and Σd total cross sections at 19 GeV

The total cross sections of 18.7 GeV Σ⁻ hyperons on protons and deutrons have been measured to be 34.0 ± 1.1 mb and 61.3 + 1.4 mb, respectively. The derived Σ⁻ -neutron cross section is 30.0 ± 1.2 mb.