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Amperometric electrochemical sensing schemes, which are easily fabricated and can directly relate measured current with analyte concentrations, remain a promising strategy for the development of the portable, in situ detection of commonly employed adulterants. Xylazine (XYL) is a non-narcotic compound designed for veterinary use as a sedative known as Rompun®. XYL is increasingly being abused as a recreational drug, as an opioid adulterant and, because of its chemical properties, has found unfortunate prominence as a date rape drug spiked into beverages. In this study, a systematic exploration and development of fouling-resistant, amperometric XYL sensors is presented. The sensing strategy features layer-by-layer (LBL) modification of glassy carbon electrodes (GCEs) with carbon nanotubes (CNTs) for sensitivity and the engagement of cyclodextrin host–guest chemistry in conjunction with polyurethane (PU) semi-permeable membranes for selectivity. The optimization of different materials and parameters during development created a greater fundamental understanding of the interfacial electrochemistry, allowing for a more informed subsequent design of effective sensors exhibiting XYL selectivity, effective sensitivity, rapid response times (<20 s), and low estimated limits of detection (~1 ppm). Most importantly, the demonstrated XYL sensors are versatile and robust, easily fabricated from common materials, and can effectively detect XYL at <10 ppm in both common alcoholic and non-alcoholic beverages, requiring only minimal volume (20 µL) of the spiked beverage for a standard addition analysis. [ABSTRACT FROM AUTHOR]

As the opioid crisis continues to wreak havoc on a global scale, it is increasingly critical to develop methodologies to detect the most dangerous drugs such as fentanyl and its derivatives, which have orders of magnitude higher potency than morphine. The scientific challenge for chemical detection of fentanyl and its derivatives is complicated by both the constantly increasing synthetic variations of the drug as well as the expanded use of adulterants. One tragically consequential example is the nocuous street drug known as "Tranq", which combines fentanyl or a fentanyl derivative with the veterinary sedative Rompun®, chemically identified as xylazine (XYL). This pervasive street cocktail is exacerbating the already staggering number of fentanyl-related deaths as its acute toxicity poses a danger to medical first-responders and complicates their initial assessment and treatment options for overdose victims. Given the widespread use of XYL as an adulterant, an electrochemical XYL sensor capable of on-site operation by non-experts as a fast-screening tool is a notable goal. This work presents a voltammetry-based sensor featuring carbon electrodes modified with carboxylic-acid functionalized multi-walled carbon nanotubes layered with cyclodextrin and polyurethane membranes for sensitivity and selectivity enhancements. The sensor has critical and robust fouling resistance while providing sensitivity at 950 μA/mM∙cm2, a low limit of detection (~5 ppm), and the ability to detect XYL in the presence of fentanyl and/or other non-fentanyl stimulants like cocaine. The demonstrated sensor can be applied to promote public health with its ability to detect and indicate XYL in the presence of opioids, serving to protect drug-users, first responders, medical examiners, and on-site forensic investigators from exposure to these dangerous mixtures. [ABSTRACT FROM AUTHOR]

Warm-water coral reefs are facing unprecedented Anthropogenic driven threats to their continued existence as biodiverse, functional ecosystems upon which hundreds of millions of people rely. Determining the tipping point thresholds of coral reef ecosystems requires robust assessment of multiple stressors and their interactive effects. We draw upon a literature search and the recent Global Tipping Points Revision initiative to consider warm-water coral reef ecosystem tipping point threshold sensitivity. Considering observed and projected stressor impacts we recognise a global mean surface temperature (relative to pre-industrial) tipping point threshold of 1.2°C (range 0.7-1.5°C) and an atmospheric CO2 warming threshold of 350ppm (range 326-400 ppm), whilst acknowledging that interacting stressors, ocean warming response time, overshoot and cascading impacts have yet to be sufficiently assessed but are likely to lower this threshold. These uncertainties around tipping point sensitivities for such a crucially important ecosystem underlines the imperative of robust assessment and, in the case of knowledge gaps, employing a precautionary principle favouring the lower range tipping point values. [ABSTRACT FROM AUTHOR]

The understanding of magnetic properties of hybrid compounds is important for the design of magnetic devices. In this contribution a prominent odd–even effect in both the structural characteristics and magnetic properties of four new hybrid compounds comprised of n-carboxyalkylammonium cations and perchloridomanganate anions is reported. When the n-carboxyalkylammonium cations contain an even number of carbon atoms, compounds of the formula (NH3(CH2)nCOOH)2[MnCl4], with n = 3 and 5, are formed, which display the two-dimensional (2D) hybrid halide perovskite structure in which bridging chlorido ligands link Mn2+ ions. Compounds containing n-carboxyalkylammonium cations with an odd number of carbon atoms have the formula (NH3(CH2)nCOOH)2[MnCl4(H2O)2], with n = 2 and 4, and display a zero-dimensional (0D) structure with hydrogen bonding interactions linking neighbouring [MnCl4(H2O)2]2− anions. The odd–even effect is also evident in the magnetic properties of the compounds, which are linked to the structural differences observed in these compounds. Compounds containing an even number of carbon atoms show antiferromagnetic (AFM) interactions and spin canting at temperature TN, with 2JK = −8.28(5) K and TN = 45.0(5) K when n = 3 and 2JK = −7.72(4) K and TN = 43(1) K when n = 5. Much weaker AFM interactions and no spin canting is observed in compounds containing an odd number of carbon atoms, with 2JK = −0.14(2) K when n = 2 and 2JK = −0.14(2) K when n = 4. [ABSTRACT FROM AUTHOR]

This work focuses on the transitions found in magnetic measurements of DyCrTiO5 nanoparticles with the associated magnetocaloric behavior. The nanoparticles have been synthesized through a fast and easy synthesis technique i.e., sol-gel method and then calcined at 800 °C. The orthorhombic structure of the material with lattice constants, a, b, and c are of 7.3158(7), 8.6431(9), 5.8390(8) Å, respectively, was established from the x-ray diffraction pattern. The transmission electron microscopy result confirms the 37 ± 1 nm particle size of the synthesised sample. The Néel temperature, TN = 153 ± 1 K, was obtained from the magnetic measurement in which magnetization (M) was measured with increasing the temperature (T). In addition, spin reorientation is observed at a temperature TSR = 49 ± 1 K. Irreversibility is seen in the field-cool-cooling curves and field-cool-warming curves of M(T) measurements at low temperatures, not previously observed in bulk samples of this material. The ferromagnetic nature, with the exchange bias effect, is confirmed for the sample from the magnetization measurements at constant temperature by varying the applied field. Additionally, a change in magnetic entropy (−ΔSm) of 10.9 ± 0.1 J kg−1 K−1 is found at a 3 T difference in the field. The obtained magnetic behavior of DyCrTiO5 nanoparticles is discussed in terms of the competing interactions of Cr3+ and Dy3+, respectively. [ABSTRACT FROM AUTHOR]

The coral reefs of the Pitcairn Islands are in one of the most remote areas of the Pacific Ocean, and yet they are exposed to the impacts of anthropogenic climate change. The Pitcairn Islands Marine Protected Area was designated in 2016 and is one of the largest in the world, but the marine environment around these highly isolated islands remains poorly documented. Evidence collated here indicates that while the Pitcairn Islands' reefs have thus far been relatively sheltered from the effect of warming sea temperatures, there is substantial risk of future coral decalcification due to ocean acidification. The projected acceleration in the rate of sea level rise, and the reefs' exposure to risks from distant ocean swells and cold-water intrusions, add further uncertainty as to whether these islands and their reefs will continue to adapt and persist into the future. Coordinated action within the context of the Pitcairn Islands Marine Protected Area can help enhance the resilience of the reefs in the Pitcairn Islands. Options include management of other human pressures, control of invasive species and active reef interventions. More research, however, is needed in order to better assess what are the most appropriate and feasible options to protect these reefs. [ABSTRACT FROM AUTHOR]

Author(s): Charles R. C. Sheppard [1] In 1998, more than 90% of shallow corals were killed on most Indian Ocean reefs [1]. High sea surface temperature (SST) was a primary [...]