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The nanocrystal aggregates formed as a result is studied by NMR, FT-IR and dynamic light scattering. The key findings are that aggregation of Ag- (I+II) in the presence of added III is reaction limited, while aggregation of Ag-II in the presence of added III exhibits diffusion-limited kinetics.

Research is presented concerning the use of nuclear magnetic resonance and dynamic light scattering to study the aggregation of silver nanocrystals which have been stabilized by chemisorption.

A study of a heterosupermolecule assembly by covalently linking a TiO (sub)2 ruthenium complex and a viologen has been investigated. Long-lived light-induced charge separation function and its potentiostatic modulation have been demonstrated.

Gold nanocrystal particles have been prepared by stabilizing a chemisorbed mixture of a long-chain alkane thiol, dodecanethiol (95%), and a long-chain dodecanethiol with a receptor, 12-mercaptododecyl-1-uracil (5%). This approach allows the chemisorption of a stabilizer to be regulated, while the desired receptor or substrate can be incorporated at the surface of the nanocrystals of a stable dispersion. The nanocrystals recognize and selectively bind in solution a long-chain alkane with N,N'-2,6-pyridinediylbis(undecamide) as a complementary substrate.

A study was conducted to characterize the covalent assembly of heterosupermolecules from TiO2 nanocrystal, ruthenium complex and violegin components. The colloidal dispersion of TiO2 nanocrystals were determined through the hydrolysis of titanium isopropoxide. The oxide powder was then grounded in an agate mortar supporting a dropwise addition of distilled water. Results indicated that the potentiostatic modulation of the quasi-Fermi level of the intrinsic substrates supported the effective modulation of heterosupermolecules in the heterosupramolecular assembly.

The measurement of the rates of acid-catalyzed dehydration of water adducts (hydrates) of benzene, naphthalene, anthracene and phenanthrene reveals that the mechanism of dehydration is different from that of simple alcohols which have a rate-determining deprotonation of the carbocation. This indicates the lower stability of an alkene than an arene product. The relative stabilities of carbocation intermediates and hydrate reactants are also revealed by their reactivity. Homoaromatic stabilization of the arene oxides is the cause for the reactivity.

Doped metal oxide nanostructure films are important in constructing ultrafast EC window and display technologies. Using a viologen modified semiconducting nanostructured metal oxide film as one electrode, and a phenothiazine modified conducting nanostructed metal oxide electrode it has proved possible to construct an ultrafast electrochromic window.

The preparation of an aqueous dispersion of electrostatically stabilized gold nanocrystals is described. These crystals were characterized by static light scattering, H NMR, small-angle X-ray scattering, dynamic light scattering and transmission electron microscopy.

Evidence that a 1,2-dihydroxycyclohexadienide anion is stabilized by aromatic “negative hyperconjugation” is described. It complements an earlier inference of “positive” hyperconjugative aromaticity for the cyclohexadienyl cation. The anion is a reactive intermediate in the dehydration of benzene cis-1,2-dihydrodiol to phenol. Rate constants for 3-substituted benzene cis-dihydrodiols are correlated by σ- values with ρ = 3.2. Solvent isotope effects for the reactions are kH2O/kD2O = 1.2-1.8. These measurements are consistent with reaction via a carbanion intermediate or a concerted reaction with a “carbanion-like” transition state. These and other experimental results confirm that the reaction proceeds by a stepwise mechanism, with a change in rate-determining step from proton transfer to the loss of hydroxide ion from the intermediate. Hydrogen isotope exchange accompanying dehydration of the parent benzene cis-1,2-dihydrodiol was not found, and thus, the proton transfer step is subject to internal return. A rate constant of ~1011 s-1, corresponding to rotational relaxation of the aqueous solvent, is assigned to loss of hydroxide ion from the intermediate. The rate constant for internal return therefore falls in the range 1011-1012 s-1. From these limiting values and the measured rate constant for hydroxide-catalyzed dehydration, a pKa of 30.8 ± 0.5 was determined for formation of the anion. Although loss of hydroxide ion is hugely exothermic, a concerted reaction is not enforced by the instability of the intermediate. Stabilization by negative hyperconjugation is proposed for 1,2-dihydroxycyclohexadienide and similar anions, and this proposal is supported by additional experimental evidence and by computational results, including evidence for a diatropic (“aromatic”) ring current in 3,3-difluorocyclohexadienyl anion. [ABSTRACT FROM AUTHOR]

Presents the measurements of equilibrium constants for the conversion of aromatic molecules and their hydrates to carbocations. Aqueous solvolyses of acyl derivatives of hydrates of anthracene and benzoduran; Rate constants for the deprotonation and for the nucleophilic reaction; Protonation of ethylene and acetylene.

Magnesium is renowned for its favorable low-density attributes, rendering it a viable choice for commercial engineering applications in which weight has substantial design implications. Magnesium (Mg) stands as a readily obtainable metallic element, exhibiting robustness, efficient heat dissipation, and excellent damping properties. The utilization of pure magnesium remains infrequent due to its susceptibility to instability under high temperatures and pronounced vulnerability to corrosion within humid environments. Hence, the incorporation of magnesium alloys into the design process of aircraft, automotive, and biomedical applications assumes paramount importance. This Review presents a comprehensive review of research endeavors and their resultant achievements concerning the advancement of magnesium alloys. Specifically focusing on aerospace, automotive, and biomedical applications, the Review underscores the pivotal role played by alloying constituents, namely aluminum (Al), copper (Cu), calcium (Ca), and PEO coatings, in influencing the microstructural attributes, mechanical potency, and resistance to corrosion., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)

Dicer is an RNase III enzyme that is responsible for the maturation of small RNAs such as microRNAs. As Dicer's cleavage products play key roles in promoting cellular homeostasis through the fine-tuning of gene expression, dysregulation of Dicer activity can lead to several human diseases, including cancers. Mutations in Dicer have been found to induce tumorigenesis and lead to the development of a rare pleiotropic tumor predisposition syndrome found in children and young adults called DICER1 syndrome. These patients harbor germline and somatic mutations in Dicer that lead to defective microRNA processing and activity. While most mutations occur within Dicer's catalytic RNase III domains, alterations within the Platform-PAZ (Piwi-Argonaute-Zwille) domain also cause loss of microRNA production. Using a combination of in vitro biochemical and cellular studies, we characterized the effect of disease-relevant Platform-PAZ-associated mutations on the processing of a well-studied oncogenic microRNA, pre-microRNA-21. We then compared these results to those of a representative from another Dicer substrate class, the small nucleolar RNA, snord37. From this analysis, we provide evidence that mutations within the Platform-PAZ domain result in differential impacts on RNA binding and processing, adding new insights into the complexities of Dicer processing of small RNA substrates.