Reliability Analysis of AlGaN-Based Deep UV-LEDs.

The current pandemic crisis caused by SARS-CoV-2 has also pushed researchers to work on LEDs, especially in the range of 220-240 nm, for the purpose of disinfecting the environment, but the efficiency of such deep UV-LEDs is highly demanding for mass adoption. Over the last two decades, several research groups have worked out that the optical power of GaN-based LEDs significantly decreases during operation, and with the passage of time, many mechanisms responsible for the degradation of such devices start playing their roles. Only a few attempts, to explore the reliability of these LEDs, have been presented so far which provide very little information on the output power degradation of these LEDs with the passage of time. Therefore, the aim of this review is to summarize the degradation factors of AlGaN-based near UV-LEDs emitting in the range of 200-350 nm by means of combined optical and electrical characterization so that work groups may have an idea of the issues raised to date and to achieve a wavelength range needed for disinfecting the environment from SARS-CoV-2. The performance of devices submitted to different stress conditions has been reviewed for the reliability of AlGaN-based UV-LEDs based on the work of different research groups so far, according to our knowledge. In particular, we review: (1) fabrication strategies to improve the efficiency of UV-LEDs; (2) the intensity of variation under constant current stress for different durations; (3) creation of the defects that cause the degradation of LED performance; (4) effect of degradation on C-V characteristics of such LEDs; (5) I-V behavior variation under stress; (6) different structural schemes to enhance the reliability of LEDs; (7) reliability of LEDs ranging from 220-240 nm; and (8) degradation measurement strategies. Finally, concluding remarks for future research to enhance the reliability of near UV-LEDs is presented. This draft presents a comprehensive review for industry and academic research on the physical properties of an AlGaN near UV-LEDs that are affected by aging to help LED manufacturers and end users to construct and utilize such LEDs effectively and provide the community a better life standard.

Novel Multi-featured Disinfection (MFD) System for COVID-19 and Related Pandemics

Society is under tremendous tension and pressure due to the Coronavirus (COVID-19) pandemic. Coronavirus pandemic-2019 is a critical health emergency with respect to the international concern. Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV-1) disease first came in 2002 and then Middle East Respiratory Syndrome Coronavirus (MERS-CoV) affects us in 2012. SARS-CoV-2 is the third coronavirus to emerge in the past two decades, which are acting as a serious warning to humans. These pandemic presents major challenges to scientist and international medical agencies to save the earth by this global life-threatening pandemic. Fighting with these major issues, scientists and doctors pointed out the solutions for COVID and Related pandemics, in which the most populated solution, such as ultraviolet (UV)-based disinfection systems. This article is presenting a unique technology for the COVID-19 infected surfaces to either sides. The proposed research is the providing the solutions with the integration/merging of two different technologies in the portable form to provide a unique disinfection system to disinfect the infected/suspected surfaces by ‘Coronavirus disease’ from top and bottom side by exposing the specified samples like currencies/hand held devices/mobile phones/various types of cards, etc. According to the various literatures, ultraviolet-C light as well as 650 nm laser light has the power to destroy the COVID-19 and related viruses. The proposed system is developed to disinfect the above-mentioned items surfaces from COVID-19 like issues and has the ability to disinfect the items in few second (within 3–5 s). The proposed system has the capability to serve the nation at different level as it may be designed and developed in different sizes as per the application. This integrated technology can serve the society in most of the applications like, the major field for disinfection is food and agriculture sectors. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

An overview of nanomaterial-based novel disinfection technologies for harmful microorganisms: Mechanism, synthesis, devices and application.

Harmful microorganism (e.g., new coronavirus) based infection is the most important security concern in life sciences and healthcare. This article aims to provide a state-of-the-art review on the development of advanced technology based on nanomaterial disinfection/sterilization techniques (NDST) for the first time including the nanomaterial types, disinfection techniques, bactericidal devices, sterilization products, and application scenarios (i.e., water, air, medical healthcare), with particular brief account of bactericidal behaviors referring to varied systems. In this emerging research area spanning the years from 1998 to 2021, total of ~200 publications selected for the type of review paper and research articles were reviewed. Four typical functional materials (namely type of metal/metal oxides, S-based, C-based, and N-based) with their development progresses in disinfection/sterilization are summarized with a list of synthesis and design. Among them, the widely used silver nanoparticles (AgNPs) are considered as the most effective bacterial agents in the type of nanomaterials at present and has been reported for inactivation of viruses, fungi, protozoa. Some methodologies against (1) disinfection by-products (DBPs) in traditional sterilization, (2) noble metal nanoparticles (NPs) agglomeration and release, (3) toxic metal leaching, (4) solar spectral response broadening, and (5) photogenerated e-/h+ pairs recombination are reviewed and discussed in this field, namely (1) alternative techniques and nanomaterials, (2) supporter anchoring effect, (3) nonmetal functional nanomaterials, (4) element doping, and (5) heterojunction constructing. The feasible strategies in the perspective of NDST are proposed to involve (1) non-noble metal disinfectors, (2) multi-functional nanomaterials, (3) multi-component nanocomposite innovation, and (4) hybrid techniques for disinfection/sterilization system. It is promising to achieve 100% bactericidal efficiency for 108 CFU/mL within a short time of less than 30 min.

Air disinfection for SARS-CoV-2 and other pathogens: A review

SARS, MERS, SARS-CoV-2 and other pathogens have caused many pandemics in the world. These pathogens are often spread as aerosols in the air. Thus, fast, efficient air disinfection is essential for effectively limiting the spread of the pathogens. A low temperature plasma disinfection method that deactivates many kinds of bacteria, fungi, viruses, spores and other microorganisms has attracted much attention due to its efficiency and environmental friendliness. Disinfection methods can be divided into physical disinfection, chemical disinfection and comprehensive disinfection based on their key factors. This paper reviews the disinfection mechanisms, application scenarios, development progress and other characteristics of various disinfection methods. The review then focuses on the application of these technologies to the disinfection of pathogens such as SARS-CoV-2 with emphasis on plasma disinfection including the key methods and prospects of plasma disinfection in central air conditioning systems. Finally, the Gong Zi Ting performance center of Tsinghua University is used as an example to show the practicality of this surface discharge plasma disinfection method as an example for further applications. This method can significantly improve epidemic prevention and control, as well as the construction of national biosafety systems. © 2021, Tsinghua University Press. All right reserved.

Disinfection technology and strategies for COVID-19 hospital and bio-medical waste management.

The isolation wards, institutional quarantine centers, and home quarantine are generating a huge amount of bio-medical waste (BMW) worldwide since the outbreak of novel coronavirus disease-2019 (COVID-19). The personal protective equipment, testing kits, surgical facemasks, and nitrile gloves are the major contributors to waste volume. Discharge of a new category of BMW (COVID-waste) is of great global concern to public health and environmental sustainability if handled inappropriately. It may cause exponential spreading of this fatal disease as waste acts as a vector for SARS-CoV-2, which survives up to 7 days on COVID-waste (like facemasks). Proper disposal of COVID-waste is therefore immediately requires to lower the threat of pandemic spread and for sustainable management of the environmental hazards. Henceforth, in the present article, disinfection technologies for handling COVID-waste from its separate collection to various physical and chemical treatment steps have been reviewed. Furthermore, policy briefs on the global initiatives for COVID-waste management including the applications of different disinfection techniques have also been discussed with some potential examples effectively applied to reduce both health and environmental risks. This article can be of great significance to the strategy development for preventing/controlling the pandemic of similar episodes in the future.