Comprehensive strategies for microcystin degradation: A review of the physical, chemical, and biological methods and genetic engineering.

Addressing the threat of harmful cyanobacterial blooms (CyanoHABs) and their associated microcystins (MCs) is crucial for global drinking water safety. In this review, we comprehensively analyze and compares the physical, chemical, and biological methods and genetic engineering for MCs degradation in aquatic environments. Physical methods, such as UV treatments and photocatalytic reactions, have a high efficiency in breaking down MCs, with the potential for further enhancement in performance and reduction of hazardous byproducts. Chemical treatments using chlorine dioxide and potassium permanganate can reduce MC levels but require careful dosage management to avoid toxic by-products and protect aquatic ecosystems. Biological methods, including microbial degradation and phytoremediation techniques, show promise for the biodegradation of MCs, offering reduced environmental impact and increased sustainability. Genetic engineering, such as immobilization of microcystinase A (MlrA) in Escherichia coli and its expression in Synechocystis sp., has proven effective in decomposing MCs such as MC-LR. However, challenges related to specific environmental conditions such as temperature variations, pH levels, presence of other contaminants, nutrient availability, oxygen levels, and light exposure, as well as scalability of biological systems, necessitate further exploration. We provide a comprehensive evaluation of MCs degradation techniques, delving into their practicality, assessing the environmental impacts, and scrutinizing their efficiency to offer crucial insights into the multifaceted nature of these methods in various environmental contexts. The integration of various methodologies to enhance degradation efficiency is vital in the field of water safety, underscoring the need for ongoing innovation.

Oxidation Mechanism of Core-Shell Structured Al@PVDF Powders Synthesized by Solvent/Non-Solvent Method.

Micron-sized aluminum (Al) powders are extensively added to energy-containing materials to enhance the overall reactivity of the materials. However, low oxidation efficiency and energy release limit the practical application of Al powders. Polyvinylidene fluoride (PVDF), the most common fluoropolymer, can easily react with Al to form aluminum fluoride (AlF3), thus promoting the oxidation of Al powders. In this paper, core-shell structured Al@PVDF powders were synthesized by solvent/non-solvent method. Thermal analysis results show that the weight and exothermic enthalpy of Al@PVDF powders are 166.10% and 11,976 J/g, which are superior to pure Al powders (140.06%, 6560 J/g). A detailed description of the oxidation mechanisms involved is provided. Furthermore, constant volume pressure results indicate that Al@PVDF powders have outstanding pressure output ability in the environment of 3 MPa oxygen. The study provides a valuable reference for the application of Al powders in energetic materials.

A Passive Wireless Crack Sensor Based on Patch Antenna with Overlapping Sub-Patch.

Monolithic patch antennas for deformation measurements are designed to be stressed. To avoid the issues of incomplete strain transfer ratio and insufficient bonding strength of stressed antennas, this paper presents a passive wireless crack sensor based on an unstressed patch antenna. The rectangular radiation patch of the proposed sensor is partially covered by a radiation sub-patch, and the overlapped length between them will induce the resonate frequency shift representing the crack width. First, the cavity model theory is adopted to show how the resonant frequencies of the crack sensor are related to the overlapped length between the patch antenna and the sub-patch. This phenomenon is further verified by numerical simulation using the Ansoft high-frequency structure simulator (HFSS), and results show a sensitivity of 120.24 MHz/mm on average within an effective measuring range of 1.5 mm. One prototype of proposed sensor was fabricated. The experiments validated that the resonant frequency shifts are linearly proportional to the applied crack width, and the resolution is suitable for crack width measuring.

A Displacement Sensor Based on a Normal Mode Helical Antenna.

This paper presents a passive displacement sensor based on a normal mode helical antenna. The sensor consists of an external helical antenna and an inserting dielectric rod. First, the perturbation theory is adopted to demonstrate that both the electric intensity and magnetic intensity have a noticeable gradient change within the in-and-out entrance of the helical antenna, which will cause the sensor to experience a resonant frequency shift. This phenomenon was further verified by numerical simulation using the Ansoft high frequency structure simulator (HFSS), and results show the linear correlation between the retrieved resonant frequency and the displacement. Two sets of proposed sensors were fabricated. The experiments validated that the resonant frequency shifts are linearly proportional to the applied displacement, and the sensing range can be adjusted to accommodate the user's needs.