Research progress on photocatalysis systems for inactivation of microbial aerosol

Now in the context of the novel coronavirus pneumonia outbreak, the control and removal of microbial aerosols has once again attracted academic attention, while conventional air purification methods such as filtration, chemical agents and UV have their own defects and deficiencies. With the advantages of high efficiency, wide spectrum, green, no residue, dynamic continuous disinfection, photocatalysis has broad application prospects. In this paper, the research on the inactivation of microbial aerosols with photocatalysis system is summarized and analyzed from the aspects of the types of photocatalysts, the load of photocatalysts, the light source and the structure and operation of reactors. TiO2 or its derivative materials are selected as photocatalysts in most studies, and more novel and efficient photocatalysts should be applied. Porous, multi-channel and large surface area catalyst carriers can effectively improve the efficiency of photocatalysis system. The light source still depends on UV light, and the application of visible light needs more research. There are few studies on improving the photocatalysis system by optimizing the reactor structure, and the most commonly used is the ring reactor. Researchers have developed photocatalytic air purifiers or combined photocatalysis systems with indoor air duct systems. In the future, photocatalysis system will become an important means for indoor microbial aerosol control. © 2023 Chemical Industry Press. All rights reserved.

POCT detection device based on thermal convection fluorescence PCR amplification

This article is based on the principle of thermal convection PCR and nucleic acid fluorescence intensity detection technology. The principle of thermal convection PCR is to form a temperature difference by separately controlling the upper temperature and the bottom temperature of the reaction tube. The lower temperature liquid at the upper part has relatively high density or specific gravity, and the upper and lower liquids will produce convection, which drives the flow of molecules in the tubular chamber. The reaction solution is formed into thermal convection in the reaction test tube and subjected to different temperatures, so as to meet the required conditions for the reaction of different enzymes, and realize the pre-denaturation, annealing and extension processes in the nucleic acid PCR amplification in a short time. Nucleic acid fluorescence intensity detection technology involves embedded system design for device control and signal analysis, optical system design for optical signal filtering and collection, and differential amplifier circuit design. The embedded system design is based on the development of precise temperature control system, motion system and signal analysis system based on Stm32 single-chip microcomputer. The temperature control system includes independent temperature control to control the heaters at the bottom of the reaction tube and the top of the reaction tube respectively;the motion system includes sample switching and switching of the light source in the imaging system. The optical system design includes 540nm FAM excitation light source, 570nm CY3 excitation light source and spherical lens focusing excitation system. This device uses a photodiode to convert the optical signal into an electrical signal, and then amplifies the collected electrical signal with a two-stage operational amplifier through a two-color light differential amplifier circuit, and then uses the signal analysis system to record and display the electrical signal changes in real time, and Make a qualitative analysis. This device not only has the advantages of low cost and high sensitivity, but also solves the key problem of the long time (more than 2 hours) of the whole process of real-time fluorescent quantitative PCR in the detection of new crown nucleic acid and cannot be screened quickly on site. The PCR time of this device is from 2 The hour is reduced to 30 minutes, which is suitable for POCT inspections, and achieves rapid screening goals for crowds of people, which is conducive to responding to acute nucleic acid detection and large-scale nucleic acid detection. This device is currently used with COVID-19 detection reagents to detect new coronaviruses, and realize the detection of 20 copies of nucleic acid sensitivity within 30 minutes. Four samples can be processed in batches at a time, and the sample size for single processing can be increased appropriately according to needs. This device provides rapid and sensitive screening methods for global epidemic prevention and control, and is of great significance to improve human health. This device can also be applied to other rapid nucleic acid detection fields. With different nucleic acid detection reagents, this device can detect different gene loci, and has a broad development space and application fields. © 2023 SPIE.

UV germicidal rays working with timer and motion sensors

As a result of coronavirus (COVID-19) epidemic, the public has become actively involved in bodily sanitation. The "New Normal” lifestyle now focuses on cleanliness and disinfection to prevent the spread of germs. This research designed and programmed a microcontroller for a UVC disinfection system using an Arduino board as an open-source electronic platform operated with a motion sensor (PIR) and timer control module (RTC). The optical properties of an 8 Watt (W) UVC source were measured. The four UVC sources investigated had wavelengths ranging from 251 to 577 nm. A UVC wavelength of 251 nm eradicates germs but also destroys tissues and is harmful to humans. Experimental result showed that UVC intensity decreased with distance from the source according to the exponential decay function. A control system, installed inside a building to kill germs when there are no humans or pets, can control UVC light source operation with a maximum power of 2kW. Operational time can be adjusted by setting on the control case, while as an additional level of safety, the system can be turned off if a motion sensor detects movement. Movement detection distance at an angle of -90 to 90 degrees was recorded. Result gave 11 m detection distance at an angle of 0 degrees, with more than 3 m detection distance at -45 to 45 degrees, as suitable for installation above a door. This timer and motion sensor-operated UV germicidal ray system can be safely deployed to keep rooms germs free.

Intelligent unmanned medicine cabinet based on 51 single-chip microcomputer

With the relatively uneven distribution of medical resources in China and a new outbreak of COVID-19 at the end of 2019, we developed an intelligent medicine cabinet to alleviate the problem of high pressure and difficulty in accessing medical care in hospitals around the country. The medicine cabinet has a signal transmission circuit system based on 51 microcontroller and a new X-Y trajectory control module, which controls the Pulse Width Modulation (PWM) signal by Proportion Integration Differentiation (PID) algorithm to improve the accuracy of the DC motor. It has the functions of online drug selection, drug sales, drug transmission, etc. Meanwhile, the online drug purchase system based on the WeChat applet can reduce the probability of infection by a new coronavirus. And the new X-Y cargo track will significantly improve the safety of fragile drugs while ensuring their delivery. The development of this medicine cabinet will greatly reduce the operating cost of pharmacies and meet the demand of people to purchase medicine at night. © 2022 SPIE.

Research Progress of Surface Plasmon Resonance and Local Surface Plasmon Resonance in Virus Detection

Significance In 2009, influenza A (H1N1) broke out in Mexico and the United States, influencing 214 countries and killing at least 14000 people. The novel coronavirus epidemic which broke out in 2020 has still been raging all over the world for two years as the results of the huge difficulty in the rapid and real-time epidemic prevention detection and the other reasons. In addition, the spread of other viruses including dengue virus (DENV) and human immunodeficiency virus (HIV) is also threatening human health significantly. Virus detection is the key to curb the spread of the viruses. At present, enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR), as the gold standard in the field of virus detection, can be used to detect and trace virus samples with a high sensitivity. But these samples need to be collected to the laboratory, and the viruses must be isolated and determined using the sophisticated lab equipment operated by professionals in order to get accurate results. Surface plasmon resonance (SPR)and local surface plasmon resonance (LSPR) biosensors may be an effective alternative, as their structures are simple and easy to be miniaturized. Especially, the LSPR-based device only needs a light source and some sensing elements. Once the sensing elements successfully capture the virus, the detection process will be quickly, sensitively, and selectively finished. These characteristics of the SPR and LSPR techniques show their great application potential in the field of virus detection, especially for the point-of-care testing with limited conditions. With the rapid development of SPR and LSPR-based virus detection researches, researchers have reviewed the progress of materials and structures of sensors, methods for plasmonic virus detection, and their characteristics of signal amplification, and so on. According to the four general virus detection methods and starting from the four kinds of target analytes captured by the sensor, this paper systematically outlines the latest researches of the SPR and LSPR techniques for detecting viruses, which are of great significance for their clinical application (Fig. 1). Progress First, according to the four methods for virus detection, the application progress of SPR and LSPR in the fields of antibody, antigen, nucleic acid, and virus particle detection is reviewed successively. For the SPR or LSPR sensors based on the binding principle of specific antigen-antibodies, the detection limit is further optimized by modifying the appropriate antigens or antibodies. More stable and inexpensive aptamers and molecularly imprinted polymers are expected to replace antibodies as sensor recognition elements to detect virus antigens or particles. Because the number of virus genomes in clinical samples is usually very small, the detection of nucleic acid by SPR or LSPR alone is limited. However, the detection of virus samples with the concentration at the femto scale can be realized by combining SPR or LSPR with DNA amplification and fluorescent substances. Second, the problems of biological medium contamination and repeatability encountered by biosensors as well as their solutions are introduced (Fig. 13). As for the contamination of biological media, self-assembled monolayers (SAM) can be synthesized on the surface of sensor elements to alleviate this problem. Riedel et al. further reduced or even completely inhibited the biological contamination of plasma and serum by synthesizing polymer brushes. In order to ensure the repeatability of sensing elements, Yoo et al. used magnetic beads replaced under the control of magnetic field as the sensing element, allowing that the sensor chip could still work stably after many repeated measurements. Third, the configurations and parameters of the SPR and LSPR sensors for virus detection in the past 15 years are listed (Table 1), and the advantages of the SPR and LSPR techniques are described. Finally, the optimization strategies of the SPR and LSPR techniques and the present existing problems are summarized. Moreover, e application prospect is also forecasted. Conclusion and Prospect According to the current research progress, the optimization strategy of the SPR sensor mainly focuses on film material sensitization and metal particle coupling sensitization. The former includes the application of 2D materials and molecular imprinting through the construction of surface films to enhance practicality and applicability. In contrast, the latter uses nanoparticles to form sandwich structures. The LSPR sensing strategies are concentrated on the design and optimization of nanoparticles or nanostructures, which are often combined with fluorescent substances such as quantum dots (QDs) to form sensing probes for virus detection by the light absorption peak shift or the fluorescence intensity change. The LSPR biosensors are normally easier to be miniaturized than the SPR counterparts. In a word, the SPR and LSPR sensors show great application prospects in the field of virus detection. Predictably, owing to the diversity of the SPR and LSPR virus sensor modifiers, it may be possible to detect specific viruses for multiple target analytes at the same time through the integration of sensor recognition elements, which enables the multi-dimensional evaluation of virus infection in a short time to avoid false negative and false positive cases. © 2022 Science Press. All rights reserved.

One Shell of a Problem: Cumulative Threat Analysis of Male Sea Turtles Indicates High Anthropogenic Threat for Migratory Individuals and Gulf of Mexico Residents

Human use of oceans has dramatically increased in the 21st century. Sea turtles are vulnerable to anthropogenic stressors in the marine environment because of lengthy migrations between foraging and breeding sites, often along coastal migration corridors. Little is known about how movement and threat interact specifically for male sea turtles. To better understand male sea turtle movement and the threats they encounter, we satellite-tagged 40 adult male sea turtles of four different species. We calculated movement patterns using state-space modeling (SSM), and quantified threats in seven unique categories;shipping, fishing, light pollution, oil rigs, proximity to coast, marine protected area (MPA) status, and location within or outside of the U.S. Exclusive Economic Zone (EEZ). We found significantly higher threat severity in northern and southern latitudes for green turtles (Chelonia mydas) and Kemp’s ridleys (Lepidochelys kempii) in our study area. Those threats were pervasive, with only 35.9% of SSM points encountering no high threat exposure, of which 47% belong to just two individuals. Kemp’s ridleys were most exposed to high threats among tested species. Lastly, turtles within MPA boundaries face significantly lower threat exposure, indicating MPAs could be a useful conservation tool.

Design of a low cost Ultraviolet Disinfection unit to minimize the cross-contamination of COVID-19 in transport

In this work, a cost-effective disinfection system for Coronavirus Disease of 2019 (COVID-19) is proposed to be used inside public transport. The disinfection system is twofold, firstly containing a tower unit where UV-C (Ultraviolet type-C) lamps are positioned in parallel, in such a way that, 360-degree space is covered, and secondly a power unit that incorporates robotics and electrical parts. The UVC unit is a separate and movable tower that can be placed anywhere inside a vehicle horizontally or vertically. UV lamps in the tower have a 254 nm wavelength with a total power of 180 Watt. The system can provide a dose of it 16.9 mj/cm2 within 26.83 seconds if the distance of the targeted surface inside a vehicle from the UVC light source is 1.5 meters. Various distances from the UV source to the targeted surface inside the vehicle are chosen and calculated the required corresponding times to achieve the required dose to inactivate all viral concentrations. The developed disinfection system not only minimizes the growth of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by performing robotic features ensuring human detection auto turn off but also utilizes minimum labor work which is vital in the current Covid-19 pandemic. © 2022 IEEE.

Design of a cheap pulse Oximeter for home care systems

In the current pandemic time, one of the important parameters for assessing the health status of a patient with COVID 19 is level of blood oxygenation. The aim of our work is devoted to the development and construction of a pulse Oximeter based on MAX ICs. The initial pulse oxymetry studies were concerned with issues such as device size and power efficiency. Reduced power consumption and size are the major causes of our progress. We picked low-power electronic components to reduce power consumption. We used a diode field with two green, one red, one infrared, and two photodiodes as a light source and detector. A high-speed four-channel AD converter converts the signal from analog to digital. The signal is smoothed using an average filter in the algorithm. We found peaks that can be utilized to determine heart rate after smoothing the signal. The blood Oximeter level is calculated by processing the amplitude of red and infrared signals collected by a photodetector. Test algorithms were performed on the Arduino platform. The output of the device are values of blood oxygenation and heart rate. © 2022 IEEE.

UV tunable light source and its potential applications for UVC virus inactivation research

An ultraviolet tunable light source (UV-TLS) is a valuable tool in studying the effectiveness of virus inactivation using UV radiation. UV-TLS can verify effective inactivation UV dosages at different wavelengths to help establish industrial UV safety standards and calibrate UV radiation sources. We developed a high throughput UV-TLS to support research into methods of inactivating coronavirus, including the virus that causes the COVID-19 disease. The light source is powered by a laser-driven light source (LDLS™) with high UV wavelength brightness, superior stability, and a 10,000-hour lifetime. The UV-TLS covers the wavelength range from 200 nm to 770 nm and has a fiber-coupled output. Advanced design features include: (1) all reflective optics for aberrationfree light coupling;(2) a high-efficiency UV grating blazed at 250 nm;(3) fiber-coupled output with a 600 μm core diameter deep-UV fiber for application flexibility. Measured data shows that the UV-TLS achieved an in-band flux of 0.98 mW with an averaged FWHM of 4.3 nm in the 200 nm to 400 nm range, using the 600 μm fiber. The averaged in-band flux reaches 2.9 mW for free-space output with an averaged FWHM of 7.2 nm. Advantages of the newly developed UV-TLS are relatively higher in-band flux, UV light output at any wavelength from 200 nm to 400 nm, and the flexibility of a fiber light delivery. The bandwidth of UV output flux can be adjusted by selecting different monochromator slit sizes. © COPYRIGHT SPIE. Downloading of the is permitted for personal use only.

UV inactivation of Semliki Forest virus and E. coli bacteria by alternative light sources.

The quick spreading of the SARS-CoV-2 virus, initiating the global pandemic with a significant impact on economics and health, highlighted an urgent need for effective and sustainable restriction mechanisms of pathogenic microorganisms. UV-C radiation, causing inactivation of many viruses and bacteria, is one of the tools for disinfection of different surfaces, liquids, and air; however, mainly mercury 254 nm line is commonly used for it. In this paper, we report our results of the experiments with newly elaborated special type polychromatic non-mercury UV light sources, having spectral lines in the spectral region from 190 nm to 280 nm. Inactivation tests were performed with both Escherichia coli (E.coli) bacteria and Semliki Forest virus (SFV) as a representative of human enveloped RNA viruses. In addition, the effect of prepared lamps on virus samples in liquid and dry form (dried virus-containing solution) was tested. Reduction of 4 log10 of E.coli was obtained after 10 min of irradiation with both thallium-antimony and arsenic high-frequency electrodeless lamps. High reduction results for the arsenic light source demonstrated sensitivity of E. coli to wavelengths below 230 nm, including spectral lines around 200 nm. For the Semliki Forest virus, the thallium-antimony light source showed virus inactivation efficiency with a high virus reduction rate in the range of 3.10 to > 4.99 log10 within 5 min of exposure. Thus, the new thallium-antimony light source showed the most promising disinfection effect in bacteria and viruses, and arsenic light sources for bacteria inactivation, opening doors for many applications in disinfection systems, including for pathogenic human RNA viruses.

Viruses Such as SARS-CoV-2 Can Be Partially Shielded from UV Radiation When in Particles Generated by Sneezing or Coughing: Numerical Simulations

UV radiation can inactivate viruses such as SARS-CoV-2. However, designing effective UV germicidal ir- radiation (UVGI) systems can be difficult because the effects of dried respiratory droplets and other fomites on UV light intensities are poorly understood. Numerical modeling of UV intensities inside virus- containing particles on surfaces can increase understanding of these possible reductions in UV intensity. We model UV intensities within spherical approximations of virions randomly positioned within spherical particles. The model virions and dried particles have sizes and optical properties to approximate SARS- CoV-2 and dried particles formed from respiratory droplets, respectively. In 1-, 5- and 9-m diameter par- ticles on a surface, illuminated by 260-nm UV light from a direction perpendicular to the surface, 0 , 10 and 18 (respectively) of simulated virions are exposed to intensities less than 1/100 th of intensities in individually exposed virions (i.e., they are partially shielded). Even for 302-nm light (simulating sunlight), where absorption is small, 0 and 11 of virions in 1- and 9-m particles have exposures 1/100 th those of individually exposed virions. Shielding is small to negligible in sub-micron particles. Results show that shielding of virions in a particle can be reduced by illuminating a particle either from multiple widely separated incident directions, or by illuminating a particle rotating in air for a time sufficient to rotate through enough orientations. Because highly UV-reflective paints and surfaces can increase the angular ranges of illumination and the intensities within particles, they appear likely to be useful for reducing shielding of virions embedded within particles.

Study on the Light Field Regulation of UVC-LED Disinfection for Cold Chain Transportation

In this paper, the pain point that cold chain transportation urgently needs for an efficient disinfection method is pointed out. Thus, this work aims at solving the problems and improving the disinfection efficiency in cold chain transportation. While Ultraviolet-C (UVC) irradiation is an effective method by which to kill viruses, it is difficult to apply the commonly used UVC-LED disinfection light source to ice-covered cold chain transportation due to its uneven light field distribution. Thus, the light field regulation of UVC-LED disinfection for cold chain transportation is studied. A UVC-LED chip with a wavelength of 275 nm was used as a light source, and parallel light was obtained by collimating lenses. Then, microlens array homogenization technology was used to shape the UVC light into a uniform light spot, with an energy space uniformity rate of 96.4%. Moreover, a simulation was conducted to compare the effects of the ice layer on the absorption of UVC light. Finally, an experiment was carried out to verify that the disinfection efficiency can be increased nearly by 30% with the proposed system by disinfecting E. coli (Escherichia coli), and the results indicate that the proposed system is an effective disinfection solution during cold chain transportation.

Innovative Contactless Palmprint Recognition System Based on Dual-Camera Alignment

Recently, contactless bimodal palmprint recognition technology has attracted increased attention due to the COVID-19 pandemic. Many dual-camera-based sensors have been proposed to capture palm vein and palmprint images synchronously. However, translations between captured palmprint and palm vein images differ depending on the distance between the hand and the sensors. To address this issue, we designed a low-cost method to align the bimodal palm regions for current dual-camera systems. In this study, we first implemented a contactless palm image acquisition device with a dual-camera module and a single-point time of flight (TOF) ranging sensor. Using this device, we collected a dataset named DCPD under different distances and light source intensities from 271 different palms. Then, a bimodal palm image alignment method is proposed based on the imaging and ranging models. After the system model is calibrated, the translation between the visible light and infrared light palm regions can be estimated quickly based on the palm distance. Finally, we designed a convolutional neural network (CNN) to effectively extract the fine- and coarse-grained palm features. Compared to widely used existing methods, the proposed networks achieved the lowest equal error rate (EER) on the Tongji, IITD, and DCPD datasets, and the average time cost of the system to perform one-time identification is approximately 0.15 s. The experimental results indicate that the proposed methods achieved high efficiency and comparable accuracy. In addition, the system's EER and rank-1 on the DCPD dataset were 0.304%and 98.66%, respectively. IEEE

A Shared Autonomy Surface Disinfection System Using a Mobile Manipulator Robot

Robots are being increasingly used in the fight against highly-infectious diseases such as Ebola, MERS, and SARS-CoV-2. Many of these robots use ultraviolet lights mounted on a mobile base to inactivate the pathogens. While the lights are generally effective at irradiating open spaces and walls, they are less effective when it comes to horizontal surfaces, because of the orientation of the light sources. This can be problematic for pathogens such as Ebola, where transmission via contaminated work surfaces, which are often horizontal, is a concern. In this paper, we describe the design, implementation, and testing of an ultraviolet light disinfection system implemented on a mobile manipulator robot designed to address the problem of horizontal surface disinfection. A human supervisor designates a surface for disinfection, the robot autonomously plans and executes an end-effector trajectory to disinfect the surface to the required certainty, and then displays the results for the supervisor to verify. We also provide some background information on Ultraviolet Germicidal Irradiation (UVGI) and describe how we constructed and validated models of ultraviolet radiation propagation and accumulation in our system. Finally, we describe our implementation on a Fetch mobile manipulation platform, and discuss how the practicalities of implementation on a real robot affect our models. © 2021 IEEE.

Basic Research on Blood Coagulation Measurement of Extracorporeal Circulation Circuit Using Photoacoustic Imaging of LED Light Source

In extracorporeal circulation devices such as ECMO, blood coagulation occurs due to various factors. Blood coagulation in the extracorporeal circulation circuit is detected ex post facto by existing pressure sensors. Subsequent detection of blood clots leads to the destruction of blood in the circuit, which is detrimental to the patient. Therefore, for the purpose of preliminary measurement in the extracorporeal circulation circuit, we will conduct basic research on measurement using photoacoustic imaging using LEDs as a light source and report it (AcousticX). As a result of measuring the blood in the extracorporeal circulation circuit circulated using the extracorporeal circulation device by photoacoustic imaging over time, it was found that the wave number and intensity of the photoacoustic wave increased with the passage of time. It has been shown that it is possible to measure the temporal change of blood coagulation circulating in the circuit.

Looking Up to the Stars. A Call for Action to Save New Zealand’s Dark Skies for Future Generations to Come

The rapid development of technology coupled with humanity’s desire to reach beyond terra firma, has resulted in more than 60 years of Outer Space activities. Although the exploration of space has provided many advantages and benefits to society so far, including vast, new information that has greatly added to our understanding of our planet and beyond, unfortunately, mankind’s footprint has negative aspects that need to be minimised as much as possible. In recent decades, a major worldwide problem has emerged in regard to the significant increase in light pollution from ground-based illuminations, as well as a lack of proper regulatory frameworks to mitigate the issue in order to protect the night sky and astronomical research. More recently, due to the escalating demand of air space for microsatellites and the rapid development of these new space technologies, as well as unmanned aerial vehicles (UAV), a new problem has arisen connected to visual light pollution (VLP). New Zealand has been especially affected, as, because of its dark skies, it has the third highest number of astronomical observatories in the world. The aim of this research is to identify critical areas for broader investigation;an action plan to improve the impact of new technologies is urgently required, not only at a national level but also worldwide. This is crucial in order to preserve humanity’s right to access the night sky and to also enable continual professional and amateur night-time observations for the present and the future, as well as for New Zealand to become a Dark Sky Nation.