No abstract

A growing number of studies have been conducted to define and assess safety culture in a variety of complex, high-risk, industries. The purpose of the present study was to review these efforts in order to gain a better understanding of the "safety culture" concept, along with the highly related concept of "safety climate." Results suggest that there exists considerable disagreement among researchers as to how safety culture should be defined and whether or not safety culture is inherently different from the concept of safety climate. These differences, however, are not generally due to the uniqueness of the industry or work domain being studied, since many researchers have focused on common domains (e.g., nuclear power). A synthesis of these various perspectives was conducted and hybrid definitions of both safety culture and climate are provided. Perhaps a common nomenclature and set of definitions will enable researchers to better share information and strategies for improving safety culture.

In this study, we present a simple but effective fluorescent system for highly sensitive and versatile sensing of 2,4,6-trinitrotoluene (TNT) using few layered planar MoS quantum dots (QDs) as reporters. Excitation-independent emitting MoS QDs were first fabricated by using the proposed ultrasonic-hydrothermal-based top-down method assisted by carbon-free hydroxylamine hydrochloride. The obtained pristine MoS QDs were then modified with cysteine for introducing amino groups as TNT binding sites. The as-prepared MoS QDs possess a planar structure, which can more adequately interact with flat aromatic TNT molecules due to π-π attraction and decreased steric effects, compared with traditional spherical/quasi-spherical QDs. As a result, they exhibit extremely high sensitivity for TNT sensing (1 nM and 2 ng for solution and substrate assay, respectively). The common ions containing in environmental water samples do not interfere with the sensing. Furthermore, the QDs-decorated test paper shows an instantaneous (within 1 min) response to trace amounts of deposited TNT, and the fluorescence quenching can even be well-visualized by the naked eye. Because of favorable analytical performances, the proposed MoS QDs-based TNT sensing system has potential applications in both environmental water monitoring and security screening.

In this study, we have reported a new colorimetric platform for sensitive and selective sensing of Hg2+ using near-infrared (NIR) plasmonic Cu2‑x Se nanoparticles (NPs) as reporters. Because of ultrahigh affinity between Hg2+ and Se2–, the added Hg2+ can react with Cu2‑x Se NPs and exchange their Cu+/Cu2+, yielding a HgSe layer around the host NPs. Accordingly, the absorption profiles of the Cu2‑x Se NPs are modulated substantially: The absorbance at 400–600 nm is increased, and the NIR localized surface plasmon resonance dramatically decreases with a more than 150 nm bathochromic shift. Thus, the system possesses triple signal responses, namely, ratiometry, wavelength, and intensity, to the analytes simultaneously. Such uniquely multiple signal output not only provides more choices for the quantification, but also enhances the reliability in the analyte detection. By rationally choosing poly­(allylamine hydrochloride) as the NP template, Hg2+ ions can be determined as ranging from 0–800 nM. The detection limit is as low as 2.7 nM, which is nearly 4 times lower than the limit value (10 nM) defined by the U.S. Environmental Protection Agency for drinking water. Other heavy/transition metal ions, such as Cu2+, Ag+, Pb2+, Cd2+, Ni2+, Co2+, Mn2+, Zn2+, Cr3+, Fe2+, and FeF6 3–, do not interfere with the sensing. Especially, Hg2+ contents can be quantified, even if their concentrations are as low 10 nM in tap water and common environmental water samples. Due to favorable analytical performance, the proposed Cu2‑x Se NPs based system has potential applications in monitoring trace Hg2+ in various real samples, even in drinking water.

Binuclear complexes [{(DMOX)CuCl}2(μ-Cl)2] (1), mononuclear complexes [(DMOX)CuBr2] (2) (DMOX = 4,5-dihydro-2-(4,5-dihydro-4,4-dimethyloxazol-2-yl)-4,4-dimethyloxazole) and the pybox Cu(II) complex [(Dm-Pybox)CuBr2] (3) (Dm-Pybox = 2,6-bis[4',4'-dimethyloxazolin-2'-yl]pyridine) were obtained by reactions of CuX2 (X = Cl, Br) with DMOX and Dm-Pybox ligands, respectively. The molecular structures of 1, 2 and 3 have been determined by single-crystal X-ray diffraction analyses. The complexes 2 and 3 are efficient in catalyzing α-amination of ketones and esters through α-bromo carbonyl intermediate. The procedures are environmentally benign methods using molecular oxygen as an oxidant with water as the only byproduct.