Intramolecular cyclization of isothiocyanyl amino acids/peptide: arrival at unnatural thioxoimidazolidinyl/thioxooxazolidinyl amino acids.

A novel intramolecular cyclization of isothiocyanyl amino acids/peptide is reported to arrive at unnatural thioxoimidazolidinyl (TOI)/thioxooxazolidinyl (TOO) amino acids for the first time. Interestingly, analogous isothiocyanyl amines under a similar reaction condition either follow 5-endo-dig cyclization to offer 5-membered thiourea or acyclic diethylaminyl thiourea derivative instead of 6-membered cyclic thiourea.

Quantitation of the Interactions of Alcohols and Amines with SmI2: Pros and Cons of VIS and NMR Spectroscopies.

While additives play an important role in the reactions of samarium iodide, ligand-SmI2 complexation constants are scarce. Here, VIS spectroscopy was harnessed along with NMR to determine the first complexation constant for most of the alcohols and amines used in SmI2 reactions. The second equilibrium constant was determined for selected ligands. In cases where both methods could be applied, in general, a good correlation between the equilibrium constants was obtained.

Quantification of the Interaction of SmI2 with Substrates and Ligands.

The method developed and introduced here enables for the first time (to the authors' knowledge), a quantitative assessment of the interaction of SmI2 with substrates prior to the electron transfer stage. As a proof of concept, equilibrium constants for some model substrates including carbonyl compounds and aromatic nuclei are reported here. In addition, the first equilibrium constants with some common ligands were also determined. The equilibrium constants range from approximately 0.07 m-1 for diisopropyl ketone to 2500 m-1 for hexamethylphosphoramide (HMPA). It is shown that the data acquired by this method, which is based on the concept of shift reagents, can shed light on the most intimate details of the reaction mechanism, and this method is a useful tool for planning a synthetic process.

The nature of binding of quinolate complex on the surface of ZnS quantum dots.

We report that the Z-type binding rather than X-type binding was favored when 8-hydroxyquinoline (HQ) reacted with presynthesized ZnS quantum dots (Qdots) to form surface zinc quinolinate complexes having a preferred stoichiometry of 1 : 2 (surface Zn2+ : HQ). Importantly, the higher solubility in polar solvents and high desorption coefficient (following Langmuir binding isotherm) of HQ-treated ZnS Qdot in DMSO solvent compared with those in methanol clearly indicated the favorable Z-type binding of HQ and thus the formation of surface octahedral ZnQ2 complex. Furthermore, the characteristics peaks in the 1H-nuclear magnetic resonance (NMR) spectrum of the desorbed species and the ligand density calculation of the surface complex (formed due to the reaction between HQ and ZnS Qdot) supported the octahedral ZnQ2 complex formation. Interestingly, the presence of dangling sulphide and the loss of planarity of ZnQ2 complex on the surface of ZnS Qdots (in turn gaining structural rigidity) may be the reasons for the Z-type binding of HQ. The specific binding might be the reason for superior optical properties and thermal stability of the surface ZnQ2 complex compared to the free ZnQ2 complex as such. The results can be considered important towards understanding the coordination chemistry of inorganic complex on the surface of Qdots and thus for their application potential.

Multipurpose isothiocyanyl alanine/lysine: Use as solvatochromic IR probes and in site specific labeling/ligation of short peptides.

The solvatochromic IR responsivity of small side chain -NCS in two unexplored unnatural amino acids, isothiocyanyl alanine (NCSAla = Ita) and lysine (NCSLys = Itl), without perturbing the conformation is demonstrated in two designed short tripeptide (BocAla-NCSAla-Ala-OMe) and hexapeptide (BocLeu-Val-Phe-Phe-NCSLys-Gly-OMe). Demonstration of site specific fluorescent labeling in both the peptides and ligation type reaction in NCSLys indicates the novelty of these two amino acids as alternative to the available canonical amino acids.

Isothiocyanyl Alanine as a Synthetic Intermediate for the Synthesis of Thioureayl Alanines and Subsequent Aminotetrazolyl Alanines.

The synthesis of unnatural amino acids with small side-chain functionalities usable for further transformations is highly demanding for the expansion of the genetic code and other possible biotechnological applications. To this end, we wanted to report the utility of an unexplored unnatural amino acid, isothiocyanyl alanine (NCSAla = Ita), for the synthesis of another class of unnatural amino acids, thioureayl alanines (TUAla = Tua). The synthesis of a third class of unnatural amino acids, amino tetrazolyl alanines (ATzAla = Ata), in a very good yield was subsequently achieved utilizing thioureayl alanines. Thus, a variety of aliphatic- and aromatic-substituted thioureayl alanines and aromatic-substituted amino tetrazolyl alanines were successfully synthesized in good to excellent yields. The photophysical properties of three of the fluorescent unnatural amino acids from two classes were also studied and presented herein.

Electrodeposited carbon nanostructured nickel composite coatings: A review.

The utilization of high-strength materials that can retain their strength after successive use under high mineral moisture (maximum weight of 1098 kg) for aerospace, automotive, and electromagnetic devices is challenging. Generally, coatings of nickel (Ni) and its alloys are utilized in the aforementioned applications, but the continuous use of the system degrades its mechanical stability and structural integrity. For the automotive and aerospace uses, the material should have high mechanical strength, wear tolerance, corrosion resistance, and magnetism. The bare Ni coatings can be altered with enhanced mechanical, tribological and electrochemical performances by using various reinforcements in the coatings. The abundantly used reinforcing agents are mainly carbonaceous nanoallotropes (such as graphene, carbon nanotubes, and diamond) for the fabrication of composite coatings. The current review unfolds the introduction of nickel and the major cause of damage to bare nickel coatings. Moreover, the review sheds light on how to mitigate the damage of nickel coatings with an emphasis on giving a flavor of distinct carbonaceous nanoallotropes. The conjugated studies on mechanical, wear, corrosion, and magnetic behavior of electrodeposited Ni-carbonaceous composite coatings are embraced in the review. Therefore, the present review can be endorsed by the readers for the protection of aircraft, automotive, and electromagnetic appliances.

Advancement in Fabrication and Characterization Techniques of Nanocomposites.

Advancements in the field of materials research have unveiled numerous unparalleled features, such as mechanical properties, clinical advances, interfacial strengthening, and porosities, providing a wide range of applications. The employment of any material begins with fabrication and characterization, demanding expertise for the effective execution of the investigation. This review encompasses the details of the working principles of some significant and frequently used fabrication and characterization techniques for various material categories, including pellets and coatings. The discussion begins with techniques for fabricating materials for various applications. A brief overview of coating synthesis methods can provide intriguing information for researchers in the field of coating fabrication. The report highlights the portrayal of morphological and physiochemical analysis techniques, followed by the estimation of the elastic modulus using nanoindentation and dynamic modulus mapping testing for the materials. Additionally, the review covers theoretical models for observing the elastic moduli of the materials. The review depicts tribological investigations of the materials, aiming to provide insight into fretting wear, pin-on-disc, and microscratch testing. The fundamentals of electrochemical characterization are presented, including the appraisal of linear polarization and potentiodynamic polarization as well as electrochemical impedance spectroscopy. Furthermore, the magnetic behavior was examined by using a vibrating sample magnetometer (VSM), and the estimation of magnetic domains in the materials was conducted through magnetic force microscopy. Thus, the report suggests that readers, especially beginners, can gain a comprehensive understanding of the extensive prospects associated with the fundamental principles of material synthesis and characterization.

Information Visualization Platform for Postmarket Surveillance Decision Support.

INTRODUCTION: The US FDA receives more than 2 million postmarket reports each year. Safety Evaluators (SEs) review these reports, as well as external information, to identify potential safety signals. With the increasing number of reports and the size of external information, more efficient solutions for data integration and decision making are needed. OBJECTIVES: The aim of this study was to develop an interactive decision support application for drug safety surveillance that integrates and visualizes information from postmarket reports, product labels, and biomedical literature. METHODS: We conducted multiple meetings with a group of seven SEs at the FDA to collect the requirements for the Information Visualization Platform (InfoViP). Using infographic design principles, we implemented the InfoViP prototype version as a modern web application using the integrated information collected from the FDA Adverse Event Reporting System, the DailyMed repository, and PubMed. The same group of SEs evaluated the InfoViP prototype functionalities using a simple evaluation form and provided input for potential enhancements. RESULTS: The SEs described their workflows and overall expectations around the automation of time-consuming tasks, including the access to the visualization of external information. We developed a set of wireframes, shared them with the SEs, and finalized the InfoViP design. The InfoViP prototype architecture relied on a javascript and a python-based framework, as well as an existing tool for the processing of free-text information in all sources. This natural language processing tool supported multiple functionalities, especially the construction of time plots for individual postmarket reports and groups of reports. Overall, we received positive comments from the SEs during the InfoViP prototype evaluation and addressed their suggestions in the final version. CONCLUSIONS: The InfoViP system uses context-driven interactive visualizations and informatics tools to assist FDA SEs in synthesizing data from multiple sources for their case series analyses.

Triazolo-ß-aza-ε-amino acid and its aromatic analogue as novel scaffolds for ß-turn peptidomimetics.

Triazolo-ß-aza-ε-amino acid and its aromatic analogue ((Al)TAA/(Ar)TAA) in the peptide backbone mark a novel class of conformationally constrained molecular scaffolds to induce ß-turn conformations. This was demonstrated for (Al)TAA in a Leu-enkephalin analogue and in a designed pentapeptide wherein the FRET process was established. Restricted rotation induced chirality and turn conformation into the achiral aromatic amino acid scaffold, (Ar)TAA, which in a short tripeptide backbone acted as a ß-turn mimic as a ß-sheet folding nucleator.