Ultrasound-electrospinning-assisted fabrication and sensing evaluation of a novel membrane as ultrasensitive sensor for copper (II) ions detection in aqueous environment

Simple colorimetric copper(II) sensor - Spectral characterization and possible applications

New o-hydroxyazocompound L bearing pyrrole residue was obtained in the simple synthetic protocol. The structure of L was confirmed and analyzed by X-ray diffraction. It was found that new chemosensor can be successfully used as copper(II) selective spectrophotometric regent in solution and can be also applied for the preparation of sensing materials generating selective color signal upon interaction with copper(II). Selective colorimetric response towards copper(II) is manifested by a distinct color change from yellow to pink. Proposed systems were effectively used for copper(II) determination at concentration level 10^-8 M in model and real samples of water.

Advances in electrospun nanofibrous membrane sensors for ion detection

Harmful metal ions and toxic anions produced in industrial processes cause serious damage to the environment and human health.

Ultra-stable fluorescent film sensor based on quantum dots for the real-time detection of Cu2

Fluorescent films have recently gained attention as chemo-sensors for real-time detection in view of their high sensitivity and rapid response. However, these sensors are usually sensitive to UV irradiation, high temperature, etc., which seriously affects sensing accuracy and limits practical use. Here, an ultra-stable fluorescent film sensor based on CdSe/Cd_xZn_1-xS QDs and polyamide-6 nanofibrous membranes has been developed for the detection of Cu²⁺. To achieve high fluorescence stability, QDs with high colloidal stability are evenly immobilized on the surface of electrospun nanofibres by a dip-coating method, which can avoid fluorescence quenching caused by aggregation in the electrospinning process. As a result, the film sensor exhibits nearly constant PL intensity under the following conditions: pH values from 5.0 to 13.0, high temperature of 100 °C, 365 nm UV light for 60 min and long preservation time of 90 days. Under optimized conditions, a linear relationship was observed between the fluorescence quenching of the film and the concentration of Cu²⁺ in the range of 0-100 μM. In addition, the film sensor responds visually with a detection limit of 10 μM and response time of 10 s, which enabled it to be used as test strips in real-time detection and may provide new insights for the detection of other substances.

Diverse response of vegetation growth to multi-time-scale drought under different soil textures in China's pastoral areas

The pastoral areas of China are mainly located in ecologically fragile regions, where its ecosystems are highly sensitive to drought trends. Although numerous studies have been carried out on the response of vegetation to droughts, it is not entirely clear whether soil properties can influence this relationship. Using the Normalized Difference Vegetation Index (NDVI) and the Standardized Precipitation Evapotranspiration Index (SPEI), covering the period 1982 to 2015, we carefully analyzed drought impacts on vegetation in China's pastoral areas, to determine the effects of vegetation communities and soil types on vegetation response to multi-time-scale drought. Significantly positive correlations between NDVI and SPEI were observed in most regions, properly indicating that vegetation was largely influenced by drought, particularly the pastures in Inner Mongolia. Generally, forest was sensitive to longer time-scales of droughts, while grassland and cropland showed a close relationship with shorter or median drought time-scales. However, noticeable differences were found on the Tibetan Plateau, mainly because drought was not the main factor affecting vegetation growth in the region. The NDVI-SPEI correlations and the corresponding SPEI time-scales of each soil texture differed considerably, even in areas of the same land cover type, revealing that soil properties, here mainly refer to soil texture (classified by fractions of each separate soil, i.e., sand, silt, and clay), can assuredly affect the resistance and resilience of vegetation to drought stress. The underlying mechanism is the difference in particle size and permeability which can alter the storage and position of available soil water, thus affecting water absorption by the root system. Our results highlight the considerable importance of properly integrating edaphic factors when exploring the impact of likely climate change on ecosystems.

Functionalized Electrospun Nanofibers as a Versatile Platform for Colorimetric Detection of Heavy Metal Ions in Water: A Review

The increasing heavy metal pollution in the aquatic ecosystem mainly driven by industrial activities has raised severe concerns over human and environmental health that apparently necessitate the design and development of ideal strategies for the effective monitoring of heavy metals. In this regard, colorimetric detection provides excellent opportunities for the easy monitoring of heavy metal ions, and especially, corresponding solid-state sensors enable potential opportunities for their applicability in real-world monitoring. As a result of the significant interest originating from their simplicity, exceptional characteristics, and applicability, the electrospun nanofiber-based colorimetric detection of heavy metal ions has undergone radical developments in the recent decade. This review illustrates the range of various approaches and functional molecules employed in the fabrication of electrospun nanofibers intended for the colorimetric detection of various metal ions in water. We highlight relevant investigations on the fabrication of functionalized electrospun nanofibers encompassing different approaches and functional molecules along with their sensing performance. Furthermore, we discuss upcoming prospectus and future opportunities in the exploration of designing electrospun nanofiber-based colorimetric sensors for real-world applications.