Search

Counterfeit electronic products not only cause financial losses but also come with safety risks. The worst‐case failure scenario certainly is a fire event. Since manufacturers are liable for damages and suffer image loss, fire‐proof postmortem taggants are needed, enabling differentiation between originals and counterfeits even after a fire incident. This work presents such taggants: optomagnetic supraparticles (SPs), i.e., complex microscale particles composed of luminescent and magnetic nanoparticles (NPs) are generated. Their hybrid nature is pivotal, as magnetic separation can effectively remove the tags from light‐absorbing fire debris, and a fire‐proof identification (ID) fingerprint is based on ratiometric luminescence signals. To achieve thermally stable magnets, iron oxide (IO) NPs are wet‐chemically coated with a SiO2‐3‐aminopropyltriethoxysilane (APTES) shell. Subsequently, these magnetic NPs are assembled with luminescent nanophosphors (lanthanide‐doped calcium phosphate NPs with a SiO2‐core) and SiO2‐APTES spacer NPs by spray‐drying to form hybrid SPs. The careful choice of type and ratios of the NPs and process parameters make it possible to achieve and precisely tune the desired functionality of the resulting fire‐proof taggants. A proof‐of‐concept is demonstrated, in which the taggants are incorporated as additives into coatings and subjected to real fire simulations. [ABSTRACT FROM AUTHOR]

Tuning the morphology of supraparticles can crucially influence their final properties and is, thus, important for their application in chemical, pharmaceutical, and food industries. The present study reveals how varied nanoparticle sizes, concentrations, and weight ratios in multicomponent dispersions influence the morphology of supraparticles assembled by these nanoparticle building blocks via spray‐drying. In a droplet containing monodisperse nanoparticles, smaller nanoparticles form a coherent elastic shell due to lower cohesive forces. As the solvent enclosed in the shell evaporates less easily due to the narrow pores between the nanoparticles, this ultimately results in rather non‐spherical supraparticles, while larger nanoparticles tend to yield spherical supraparticles. When small nanoparticles outweigh large ones in binary or trinary dispersions, the small nanoparticles form the outer shell that shrinks into a mushroom cap‐like shape upon drying of the spray‐droplet, while larger nanoparticles stay in the center of the droplet, resulting in non‐spherical supraparticles. Furthermore, the findings give a more systematic insight into structures that potentially arise from multimodal‐sized building blocks, thus, paving the way to tune the supraparticle morphology upon spray‐drying, when working with more complex, multicomponent dispersions. [ABSTRACT FROM AUTHOR]

To examine whether sex-specific associations between baseline PA level and follow up cognitive performance in Chinese subjects exist from the China Health and Retirement Longitudinal study (CHARLS). A total of 3395 adults aged 45 or old from the CHARLS were used for analysis. The combined scores of measurements of mental status and verbal episodic memory were utilized for assessing cognitive function at baseline in 2011 and the follow-up survey in 2015. Baseline PA level was quantified as the total PA score. Multiple linear regression and logistic regression models were used to examine the association between baseline PA status and global cognitive function and cognitive domains. In the female subjects (n = 1748), compared with individuals of PA level in the lower tertile, those grouped into the upper tertile had the lowest risk of global cognitive decline [odds ratio (OR) =0.273, 95% confidence interval (CI) =0.077-0.960; p = 0.043] and verbal episodic memory decline [OR)=0.257, 95% CI =0.066-1.003; p = 0.051] from 2011 to 2015. However, no significant associations were observed in the male subjects (n = 1647). In the female subjects, higher PA level was associated with reduced risk of cognitive decline within 4 years, this might be associated with reduced decline of verbal episodic memory. Our findings confirmed that female sex would positively affect the association between PA levels and cognitive decline. [ABSTRACT FROM AUTHOR]