Gas phase deposition of well-defined bimetallic gold-silver clusters for photocatalytic applications.

Cluster beam deposition is employed for fabricating well-defined bimetallic plasmonic photocatalysts to enhance their activity while facilitating a more fundamental understanding of their properties. AuxAg1-x clusters with compositions (x = 0, 0.1, 0.3, 0.5, 0.7, 0.9 and 1) spanning the metals' miscibility range were produced in the gas-phase and soft-landed on TiO2 P25-coated silicon wafers with an optimal coverage of 4 atomic monolayer equivalents. Electron microscopy images show that at this coverage most clusters remain well dispersed whereas EXAFS data are in agreement with the finding that the deposited clusters have an average size of ca. 5 nm and feature the same composition as the ablated alloy targets. A composition-dependant electron transfer from Au to Ag that is likely to impart chemical stability to the bimetallic clusters and protect Ag atoms against oxidation is additionally evidenced by XPS and XANES. Under simulated solar light, AuxAg1-x clusters show a remarkable composition-dependent volcano-type enhancement of their photocatalytic activity towards degradation of stearic acid, a model compound for organic fouling on surfaces. The Formal Quantum Efficiency (FQE) is peaking at the Au0.3Ag0.7 composition with a value that is twice as high as that of the pristine TiO2 P25 under solar simulator. Under UV the FQE of all compositions remains similar to that of pristine TiO2. A classical electromagnetic simulation study confirms that among all compositions Au0.3Ag0.7 features the largest near-field enhancement in the wavelength range of maximal solar light intensity, as well as sufficient individual photon energy resulting in a better photocatalytic self-cleaning activity. This allows ascribing the mechanism for photocatalysis mostly to the plasmonic effect of the bimetallic clusters through direct electron injection and near-field enhancement from the resonant cluster towards the conduction band of TiO2. These results not only demonstrate the added value of using well-defined bimetallic nanocatalysts to enhance their photocatalytic activity but also highlights the potential of the cluster beam deposition to design tailored noble metal modified photocatalytic surfaces with controlled compositions and sizes without involving potentially hazardous chemical agents.

Pharmacological properties, therapeutic potential, and legal status of Cannabis sativa L.: An overview.

Marijuana, or Cannabis sativa L., is a common psychoactive plant used for both recreational and medicinal purposes. In many countries, cannabis-based medicines have been legalized under certain conditions because of their immense prospects in medicinal applications. With a comprehensive insight into the prospects and challenges associated with the pharmacological use and global trade of C. sativa, this mini-review focuses on the medicinal importance of the plant and its legal status worldwide; the pharmacological compounds and its therapeutic potential along with the underlying public health concerns and future perspective are herein discussed. The existence of major compounds including Δ9 -tetrahydrocannabinol (Δ9 -THC), cannabidiol, cannabinol, and cannabichromene contributes to the medicinal effects of the cannabis plant. These compounds are also involved in the treatment of various types of cancer, epilepsy, and Parkinson's disease displaying several mechanisms of action. Cannabis sativa is a plant with significant pharmacological potential. However, several aspects of the plant need an in-depth understanding of the drug mechanism and its interaction with other drugs. Only after addressing these health concerns, legalization of cannabis could be utilized to its full potential as a future medicine.

Ochratoxins in food and feed: Occurrence and its impact on human health and management strategies.

Ochratoxins (OTs) are a group of mycotoxins produced by Aspergillus and Penicillium spp. which are ubiquitous. They infect the crops during pre- and post-harvest conditions and contaminate various food and feed. Among all the OTs produced, ochratoxin A (OTA) poses serious health issues like neurotoxicity and carcinogenesis. The harmful impact of the toxins is observed in both humans and animals. The toxins get accumulated in the organs of animals through the contaminated animal-feed which further contaminate the products derived from them, such as milk and meat-based products. Therefore, sensitive and robust identification, detection, and quantification methods along with efficient management and control measures are crucial. Spectrometric and spectroscopy techniques are quite sensitive and lead to better detection of the toxin in the food products. Control and preventive measures during harvesting, storage and transportation are found to be effective in managing the production of such toxins. This review insight on the occurrence, chemistry, biosynthesis, effects on human health and agriculture, detections, management, and control strategies of ochratoxins.