Interfacial Triboelectricity Lights Up Phosphor-Polymer Elastic Composites: Unraveling the Mechanism of Mechanoluminescence in Zinc Sulfide Microparticle-Embedded Polydimethylsiloxane Films.

Composites comprising copper-doped zinc sulfide phosphor microparticles embedded in polydimethylsiloxane (ZnS:Cu-PDMS) have received significant attention over the past decade because of their bright and durable mechanoluminescence (ML); however, the underlying mechanism of this unique ML remains unclear. This study reports empirical and theoretical findings that confirm this ML is an electroluminescence (EL) of the ZnS:Cu phosphor induced by the triboelectricity generated at the ZnS:Cu microparticle-PDMS matrix interface. ZnS:Cu microparticles that exhibit bright ML are coated with alumina, an oxide with strong positive triboelectric properties; the contact separation between this oxide coating and PDMS, a polymer with strong negative triboelectric properties, produces sufficient interfacial triboelectricity to induce EL in ZnS:Cu microparticles. The ML of ZnS:Cu-PDMS composites varies on changing the coating material, exhibiting an intensity that is proportional to the amount of interfacial triboelectricity generated in the system. Finally, based on these findings, a mechanism that explains the ML of phosphor-polymer elastic composites (interfacial triboelectric field-driven alternating-current EL model) is proposed in this study. It is believed that understanding this mechanism will enable the development of new materials (beyond ZnS:Cu-PDMS systems) with bright and durable ML.

Design and Synthesis of CdHgSe/HgS/CdZnS Core/Multi-Shell Quantum Dots Exhibiting High-Quantum-Yield Tissue-Penetrating Shortwave Infrared Luminescence.

Cdx Hg1- x Se/HgS/Cdy Zn1- y S core/multi-shell quantum dots (QDs) exhibiting bright tissue-penetrating shortwave infrared (SWIR; 1000-1700 nm) photoluminescence (PL) are engineered. The new structure consists of a quasi-type-II Cdx Hg1- x Se/HgS core/inner shell domain creating luminescent bandgap tunable across SWIR window and a wide-bandgap Cdy Zn1- y S outer shell boosting the PL quantum yield (QY). This compositional sequence also facilitates uniform and coherent shell growth by minimizing interfacial lattice mismatches, resulting in high QYs in both organic (40-80%) and aqueous (20-70%) solvents with maximum QYs of 87 and 73%, respectively, which are comparable to those of brightest visible-to-near infrared QDs. Moreover, they maintain bright PL in a photocurable resin (QY 40%, peak wavelength ≈ 1300 nm), enabling the fabrication of SWIR-luminescent composites of diverse morphology and concentration. These composites are used to localize controlled amounts of SWIR QDs inside artificial (Intralipid) and porcine tissues and quantitatively evaluate the applicability as luminescent probes for deep-tissue imaging.

Adsorptive removal of aromatic diamines from water using metal-organic frameworks functionalized with a nitro group.

Adsorptive removal of aromatic diamines such as methylenedianiline (MDA) and p-phenylenediamine (PPD) was firstly investigated with nitro-functionalized metal-organic frameworks (MOFs, MIL-101(Cr)-NO2). The MIL-101(Cr)-NO2 showed much better performances in the removal of MDA and PPD, in both adsorption capacity and kinetics, than any other adsorbents. For example, MIL-101(Cr)-NO2 had a much higher maximum adsorption capacity for MDA (1111 mg·g-1) than activated carbon (208 mg·g-1) or a reported adsorbent (391 mg·g-1). Based on experimental results, hydrogen bonding (especially, via the formation of a 6-membered ring (6-MR) between -NO2 of the adsorbent and -NH2 of the adsorbates) could be suggested as the main mechanism to interpret the noticeable adsorption of the diamines. Importantly, this is the first example to confirm that MOFs with nitro group can be a competitive adsorbent to remove organics composed of amino group, especially via making 6-MR through hydrogen bonding. Higher adsorption of MDA than that of PPD over MIL-101(Cr)-NO2 might be explained with π-π interaction between aromatic rings (π-lean aromatics of MOF and π-rich aromatics of the adsorbates). Moreover, MIL-101(Cr)-NO2 could be recycled after simple washing, suggesting the potential use of the MOF in adsorptive purification of contaminated water with organics with amino groups.

Zwitterion-Coated Colloidal Magnetic Nanoparticle Clusters for Reduced Nonspecific Adsorption of Biomolecules.

This paper demonstrates fabrication of silica-shell-coated magnetic nanoparticle clusters (SMNCs) and subsequent surface engineering of SMNCs to produce surface-modified SMNCs that have zwitterionic and primary amine ligands (SMNC-ZW/Am). SMNC-ZW/Am was passivated by zwitterionic ligands for improved colloidal stability and reduced nonspecific adsorption and by primary amine ligands for facilitated conjugation with biomolecules. Hydrodynamic (HD) size and zeta potential of SMNC-ZW/Am could be flexibly tuned by controlling the relative amounts of zwitterionic and primary amine ligands. SMNC-ZW/Am had higher colloidal stability in high salt concentration and broad pH range than did bare SMNC. Nonspecific adsorption with biomolecules onto SMNC-ZW/Am surface was significantly suppressed by the zwitterionic ligands. The facile bioconjugation capability of SWNC-ZW/Am enabled conjugation of biotin and antibody to the SWNC-ZW/Am surface. Biomolecule-conjugated SMNC-ZW/Am showed specific binding affinity to streptavidin and Salmonella bacteria, with reduced nonspecific adsorption; therefore, SWMC-ZW/Am has potential use as an antifouling nanosubstrate for separation and bioanalysis.

An Acridine-Based Fluorescent Sensor for Monitoring ClO- in Water Samples and Zebrafish.

A novel acridine-based fluorescent chemosensor, BK ((E)-2-((acridine-9-ylimino)methyl)-N-benzhydrylhydrazine-1-carbothioamide), for monitoring ClO- was prepared. The sensor BK was synthesized by introducing a new synthetic route of making aldehyde group using formic hydrazide. Probe BK displayed notable fluorescence quenching in the presence of ClO- and showed a great selectivity over other guest analytes. The detection limit was calculated to be 7.65 µM. Additionally, BK was satisfactorily applied for sensing ClO- in water samples and zebrafish.

Use of social-networking sites and subjective well-being: a study in South Korea.

Social-networking sites (SNSs) provide users with a unique computer-mediated environment where individuals are able to disclose their thoughts, feelings, and experiences within their circle of personal ties. From a positive psychological perspective, this research investigated the use of SNSs and users' subjective well-being. The results show that although the time spent using a SNS is not related to well-being, the amount of self-disclosure on SNSs is positively related to subjective well-being. In addition, an individual's socioeconomic status is negatively related to self-disclosing behavior.