Capacitive Sensor to Monitor Enzyme Activity by Following Degradation of Macromolecules in Real Time

Applied Biochemistry and Biotechnology - A capacitive sensor was developed to analyze the presence and enzymatic activity of a model protease from standard solutions by following the degradation of...     

Reversible C=C Bond Activation by an Intramolecularly Coordinated Antimony(I) Compound

The reaction of N,C,N-chelated stibinidene ArSb ( 1 ) (Ar=C₆H₃-2,6-(CH=NtBu)₂) with selected N-alkyl/aryl-maleimides RN(C(O)CH)₂ (R=Me, tBu, Ph) gave the addition products with bridged bicyclic [2.2.1] structure containing an antimony atom at the bridgehead position, fused with a 6-membered benzene and a 5-membered N-alkyl/aryl-pyrrolidine ring. These compounds were completely characterized. More importantly, additional studies showed that these reactions are reversible in solution, thereby representing an unprecedented reversible activation of a C=C bond by an antimony(I) compound.     

Mildred Dresselhaus and Solid State Pedagogy at MIT

Mildred Dresselhaus is known for her influential research on the physics of carbon. Her wide‐ranging influence as a physics teacher, although well‐known to her students, has been less thoroughly examined. Exploring how Dresselhaus grew into her role teaching solid state physics at MIT reveals much about how that subfield evolved.     

Nonmetal-to-metal transition in dense fluid helium

The nonmetal-to-metal transition in dense fluid helium is discussed, which has been, in analogy to metallization of hydrogen, predicted as first-order plasma phase transition using chemical models for the equation of state and plasma composition. However, recent ab initio simulations performed for dense fluid helium indicate that this transition is continuous in the considered regime, without a density jump and latent heat as characteristic of a first-order phase transition. Implications for some astrophysical plasmas are discussed.     

Wave packet dynamics of nonlinear Gazeau–Klauder coherent states of a position-dependent mass system in a Coulomb-like potential

AD = 1 position-dependent mass approach to constructing nonlinear quantum states for a modified Coulomb potential is used to generate Gazeau–Klauder coherent states. It appears that their energy eigenvalues are scaled down by the quantum number and the nonlinearity coefficient. We study the basic properties of these states, which are found to be undefined on the whole complex plane, and some details of their revival structure are discussed.     

Catalytic Nitrene Transfer by an FeIV-Imido Complex Generated by a Comproportionation Process

Nitrene transfer reactions have emerged as one of the most powerful and versatile ways to insert an amine function to various kinds of hydrocarbon substrates. However, the mechanisms of nitrene generation have not been studied in depth albeit their formation is taken for granted in most cases without definitive evidence of their occurrence. In the present work, we compare the generation of tosylimido iron species and NTs transfer from Fe^II and Fe^III precursors where the metal is embedded in a tetracarbene macrocycle. Catalytic nitrene transfer to reference substrates (thioanisole, styrene, ethylbenzene and cyclohexane) revealed that the same active species was at play, irrespective of the ferrous versus ferric nature of the precursor. Through combination of spectroscopic (UV-visible, Mössbauer), ESI-MS and DFT studies, an Fe^IV tosylimido species was identified as the catalytically active species and was characterized spectroscopically and computationally. Whereas its formation from the Fe^II precursor was expected by a two-electron oxidative addition, its formation from an Fe^III precursor was unprecedented. Thanks to a combination of spectroscopic (UV-visible, EPR, Hyscore and Mössbauer), ESI-MS and DFT studies, we found that, when starting from the Fe^III precursor, an Fe^III tosyliodinane adduct was formed and decomposed into an Fe^V tosylimido species which generated the catalytically active Fe^IV tosylimide through a comproportionation process with the Fe^III precursor.     

Cytotoxicity of Shear Exfoliated Pnictogen (As,Sb, Bi) Nanosheets

The experimental achievement of phosphorene, which exhibits superior electronic, physical, and optical properties has spurred recent interest in other Group 15 elemental 2D nanomaterials such as arsenene, antimonene, and bismuthene. These unique and superior properties of the pnictogen nanosheets have spurred intensive research efforts and led to the discovery of their diversified potential applications; for instance, optical Kerr material, photonic devices, pnictogen-decorated microfibers, high-speed transistors, and flexible 2D electronics. Previous studies have mainly been dedicated to study the synthesis, properties, and applications of the heavy pnictogens nanosheets; however, the toxicological behaviour of these nanosheets has yet to be established. Herein, the cytotoxicity study of pnictogen nanosheets (As, Sb, and Bi) was conducted over 24 h of incubation with various concentrations of test materials and adenocarcinoma human lung epithelial A549 cells. After the treatment period, the remaining cell viabilities were obtained through absorbance measurements with WST-8 and MTT assays. These findings demonstrate that the toxicity of pnictogen nanosheets decreases down Group 15, whereby arsenic nanosheets are considered to be the most toxic, whereas bismuth nanosheets induce low cytotoxicity. The findings of this study constitute an important initial step towards enhancing our understanding of the toxicological effects of pnictogen nanosheets in light of their prospective commercial applications.     

Evaluation of Co and Zn competitive sorption by zeolitic material synthesized from fly ash using 60Co and 65Zn as radioindicators

Journal of Radioanalytical and Nuclear Chemistry - Zeolitic material prepared by hydrothermal treatment of brown coal fly ash was used for sorption separation of Co2+ and Zn2+ ions from single and...