General Approach to the Evolution of Singlet Nanoparticles from a Rapidly Quenched Point Source

Among the numerous point vapor sources, microsecond-pulsed spark ablation at atmospheric pressure is a versatile and environmentally friendly method for producing ultrapure inorganic nanoparticles ranging from singlets having sizes smaller than 1 nm to larger agglomerated structures. Due to its fast quenching and extremely high supersaturation, coagulational growth already begins at the atomic scale at room temperature. On the basis of this knowledge, we develop a simple semiempirical yet versatile model for predicting the size distribution of singlet particles as a function of the process conditions. The model assumes that a plume of a turbulent aerosol flow flares out from a concentrated point source, eventually reaching the walls of the confinement where a fraction of the particles is deposited. Despite the complexity of the entire process, the concentration and size evolution of particles can be adequately described by a first-order differential equation accounting for coagulation, turbulent dilution, and diffusional deposition to the walls. The model provides a simple and practical tool that can generally be used to design and control point vapor source reactors for the synthesis of singlets with tunable sizes starting from that of single atoms

Significant Enhancement of the Adhesion between Metal Films and Polymer Substrates by UV–Ozone Surface Modification in Nanoscale

Polymer metallization is extensively used in a variety of micro- and nanosystem technologies. However, the deposited metal film exhibits poor adhesion to polymer substrates, which may cause difficulties in many applications. In this work, ultraviolet (UV)–ozone surface modification is for the first time put forward to enhance the adhesion between metal films and polymer substrates. The adhesion of sputtered Cu films on UV-ozone modified poly­(methyl methacrylate) (PMMA) substrates is enhanced by a factor of 6, and that of Au films is improved by a factor of 10. Moreover, metal films on the modified PMMA substrates can withstand a long-time liquid immersion. To understand the mechanism for the adhesion enhancement, the surface modification is studied with contact angle measurements, attenuated total reflection Fourier-transform infrared spectrometry (ATR-FTIR) and atomic force microscopy (AFM). Detailed characterization results indicate that the significant adhesion enhancement is attributed to the increases of both the surface wettability by generating some polar functional groups and the roughness of the surface in nanoscale. To demonstrate this novel polymer metallization method, a 6-in. PMMA chip with arrays of three-electrode electrochemical microsensors is designed and fabricated, and the microsensor exhibits excellent reproducibility, uniformity, and long-term stability

Discovery of New SIRT2 Inhibitors by Utilizing a Consensus Docking/Scoring Strategy and Structure–Activity Relationship Analysis

SIRT2, which is a NAD+ (nicotinamide adenine dinucleotide) dependent deacetylase, has been demonstrated to play an important role in the occurrence and development of a variety of diseases such as cancer, ischemia-reperfusion, and neurodegenerative diseases. Small molecule inhibitors of SIRT2 are thought to be potential interfering agents for relevant diseases. Discovery of SIRT2 inhibitors has attracted much attention recently. In this investigation, we adopted a consensus docking/scoring strategy to screen for novel SIRT2 inhibitors. Structural optimization and structure–activity relationship (SAR) analysis were then carried out on highly potent compounds with new scaffolds, which led to the discovery of 2-((5-benzyl-5<i>H</i>-[1,2,4]­triazino­[5,6-<i>b</i>]­indol-3-yl)­thio)-<i>N</i>-(naphthalen-1-yl)­acetamide (<b>SR86</b>). This compound showed good activity against SIRT2 with an IC₅₀ value of 1.3 μM. <b>SR86</b> did not exhibit activity against SIRT1 and SIRT3, implying a good selectivity for SIRT2. In in vitro cellular assays, <b>SR86</b> displayed very good antiviability activity against breast cancer cell line MCF-7. In Western blot assays, <b>SR86</b> showed considerable activity in blocking the deacetylation of α-tubulin, which is a typical substrate of SIRT2. Collectively, because of the new scaffold structure and good selectivity of <b>SR86</b>, it could serve as a promising lead compound, hence deserving further studies