Transparent and visible light-activated antimicrobial air filters from electrospun crystal violet-embedded polyacrylonitrile nanofibers.

Bioaerosols pose significant risks to indoor environments and public health, driving interest in advanced antimicrobial air filtration technologies. Conventional antimicrobial filters often suffer from diminished efficacy over time and require additional binders to retain antimicrobial agents. This study introduces CV@PAN, a self-disinfecting nanofiber fabricated via electrospinning of crystal violet (CV) and polyacrylonitrile (PAN).

A Cylindrical Lens Spectrometer with Parallel Detection for Reflection Electron Energy Loss Spectroscopy.

Reflection electron energy loss spectroscopy (REELS) has played a pivotal role in allowing researchers to explore the characteristics of various bulk materials. This study presents results for the low-loss region of REELS with a new cylindrical lens spectrometer integrated into a low-voltage scanning electron microscope. The operational principles and implementation of the spectrometer are explained through comparisons between electron optical simulations and experimental results.

Design and optimization of a conical electrostatic objective lens of a low-voltage scanning electron microscope for surface imaging and analysis in ultra-high-vacuum environment.

Low-voltage scanning electron microscopy (LV-SEM) with landing energies below 5 keV has been widely used due to its advantages in mitigating the damage and charging effects to a specimen and enhancing surface information due to small interaction volume of electrons inside a specimen. Additionally, for elemental analysis of the surfaces of bulk specimens with Auger electron spectroscopy (AES) or electron energy loss spectroscopy (EELS), ultra-high-vacuum (UHV) environment is essential to maintain clean surfaces without the absorption of gas molecules during the electron beam irradiation for the acquisition of spectral data. In this study, we propose the optimal design and condition of a conical Electrostatic Objective Lens (EOL) for a UHV LV-SEM to achieve the high spatial resolution and secondary electron (SE) detection efficiency.

The Effectiveness of a Mechanical Ventilation System for Indoor PM in Residential Houses.

The mechanical ventilation systems used in houses are designed to reduce carbon dioxide emissions while minimizing the energy loss resulting from ventilation. However, the increase in indoor fine particulate (PM) concentration because of external PM influx through the ventilation system poses a problem. Here, we analyzed the changes in indoor PM concentration, distinguishing between cases of high and low outdoor PM concentrations and considering the efficiency of the filters used in residential mechanical ventilation systems.

Exploring the Potential of a Thermionic LaB6 Virtual Source Mode Electron Gun for a High Angular Current Density and a Narrow Energy Distribution.

To date, lanthanum hexaboride (LaB6) thermionic electron sources have not been able fully to capitalize on their inherent potential, resulting in an ambiguous position within the application area. Although they exhibit higher brightness compared with a tungsten filament source, they still fall short of the performance of Schottky electron sources. This study aims to explore the capabilities of the LaB6 electron source under different operating conditions to bridge the gap, ultimately to realize its untapped potential.

Performance comparison of photodynamic antimicrobial chemotherapy with visible-light-activated organic dyes: Rose bengal, crystal violet, methylene blue, and toluidine blue O.

This study evaluated the photobiocidal performance of four widely distributed visible-light-activated (VLA) dyes against two bacteria (Staphylococcus epidermidis and Escherichia coli) and two bacteriophages (phages MS2 and phi 6): rose bengal (RB), crystal violet, methylene blue, and toluidine blue O (TBO). The photobiocidal performance of each dye depended on the relationship between the type of dye and microorganism. Gram-negative E.

Prediction of indoor PM concentrations and reduction strategies for cooking events through various IAQ management methods in an apartment of South Korea.

Indoor PM in apartments must be effectively managed to minimize adverse impacts on human health. Cooking is the one of the main PM sources in apartments, and indoor air quality (IAQ) management methods (natural ventilation, mechanical ventilations, range hoods, and air purifiers) are typically used to reduce PM generated during cooking. For effective control of indoor PM , prediction of PM reduction for various IAQ management methods is necessary.

The Actual Efficacy of an Air Purifier at Different Outdoor PM Concentrations in Residential Houses with Different Airtightness.

It is important to control airborne particles in residential houses for protecting human health. Indoor particulate matter of <2.5 μm (PM2.

Multiplexed electrospraying of water in cone-jet mode using a UV-embossed pyramidal micronozzle film.

The electrospraying of water in the cone-jet mode is difficult in practical applications owing to its low throughput and the electrical discharge caused by the high surface tension of water. A film with multiple dielectric micronozzles is essential for multiplexed electrospraying of water in cone-jet mode without electrical discharge. Thus, a pyramidal micronozzle film with five nozzles was fabricated using the UV-embossing process.

High-Performance Compact Pre-Lens Retarding Field Energy Analyzer for Energy Distribution Measurements of an Electron Gun.

The energy distribution of an electron gun is one of the most important characteristics determining the performance of electron beam-based instruments, such as electron microscopes and electron energy loss spectroscopes. For accurate measurements of the energy distribution, this study presents a novel retarding field energy analyzer (RFEA) with the feature of an additional integrated pre-lens, which enables an adjustment of beam trajectory into the analyzer. The advantages of this analyzer are its compact size and simple electrode configuration.

Photobiocidal-triboelectric nanolayer coating of photosensitizer/silica-alumina for reusable and visible-light-driven antibacterial/antiviral air filters.

Outbreaks of airborne pathogens pose a major threat to public health. Here we present a single-step nanocoating process to endow commercial face mask filters with photobiocidal activity, triboelectric filtration capability, and washability. These functions were successfully achieved with a composite nanolayer of silica-alumina (Si-Al) sol-gel, crystal violet (CV) photosensitizer, and hydrophobic electronegative molecules of 1H, 1H, 2H, 2H-perfluorooctyltriethoxysilane (PFOTES).

A Novel Monochromator with Offset Cylindrical Lenses and Its Application to a Low-Voltage Scanning Electron Microscope.

Low-voltage scanning electron microscopes (LV-SEMs) are widely used in nanoscience. However, image resolution for SEMs is restricted by chromatic aberration due to energy spread of the electron beam at low acceleration voltage. This study introduces a new monochromator (MC) with offset cylindrical lenses (CLs) as one solution for LV-SEMs.

Quartz crystal microbalance with thermally-controlled surface adhesion for an efficient fine dust collection and sensing.

The mass concentration of fine dust or particles acts as a standard measure to express the severity of air pollution. In connection with this, many related sensor technologies have been suggested for both indoor and outdoor uses. Among several technologies, the direct measurement of the dust mass using resonant platforms is the most preferable as it possesses multiple advantages including high sensitivity, low limit of detection, and a rapid response time.

Effects of Air Purifiers on the Spread of Simulated Respiratory Droplet Nuclei and Virus Aggregates.

The present study was performed to quantitatively evaluate the effects of air purifiers on the spread of COVID-19 and to suggest guidelines for their safe use. To simulate respiratory droplet nuclei and nano-sized virus aggregates, deionized water containing 100 nm of polystyrene latex (PSL) particles was sprayed using a vibrating mesh nebulizer, and the changes in the particle number concentration were measured for various locations of the particle source and air purifier in a standard 30 m test chamber. The spread of the simulated respiratory droplet nuclei by the air purifier was not significant, but the nano-sized aggregates were significantly affected by the airflow generated by the air purifier.

High-sensitivity microvolume UV absorption spectrometry for routine analysis of small-volume biological samples.

Substantial improvement of microvolume UV absorption spectrometry in sensitivity, robustness and ease of operation was achieved for routine biological applications. A unique microtubing-based absorption cell (208 μm internal diameter) featuring enhanced light transmission with a liquid core waveguide technique provided dramatically enhanced absorption sensitivity, proportional to the extended path length (50 mm, from the typical 1 mm), while robust measurement performance was attained by implementation of preventive measures against bubble trapping along the light path. For plasmid DNA, absorbance at 260 nm was reliably measurable down to 0.

Study and design of a lens-type retarding field energy analyzer without a grid electrode.

A retarding field energy analyzer (RFEA) for measuring the energy distribution of charged particles offers the advantages of a simple structure and suitability for simultaneous observations of beam patterns in two dimensions. In this study, lens-based RFEAs without a grid electrode were theoretically investigated with regard to the geometry and lens condition to achieve high performance. The simulation results show that the proposed RFEA can achieve a resolution of 2.

Fabrication of a trimer/single atom tip for gas field ion sources by means of field evaporation without tip heating.

A gas field ion source (GFIS) has many advantages that are suitable for ion microscope sources, such as high brightness and a small virtual source size, among others. In order to apply a tip-based GFIS to an ion microscope, it is better to create a trimer/single atom tip (TSAT), where the ion beam must be generated in several atoms of the tip apex. Here, unlike the conventional method which uses tip heating or a reactive gas, we show that the tip surface can be cleaned using only the field evaporation phenomenon and that the TSAT can also be fabricated using an insulating layer containing tungsten oxide, which remains after electrochemical etching.

Black P/graphene hybrid: A fast response humidity sensor with good reversibility and stability.

Black phosphorus (BP) materials have attracted considerable attention owing to their ultra-sensitive humidity sensing characteristics because of the natural absorption of water (HO) molecules on the BP surface caused by the specific 2D layer-crystalline structure. On the other hand, the BP-based humidity sensor is less repeatable due to the instability of BP with water molecules and the stability of the sensor is reduced. In this study, this limitation of the BP-based humidity sensor was overcome by preparing a BP/graphene hybrid as a novel humidity sensing nanostructure.

Serial number coding and decoding by laser interference direct patterning on the original product surface for anti-counterfeiting.

Here, we investigate a method to distinguish the counterfeits by patterning multiple reflective type grating directly on the surface of the original product and analyze the serial number from its rotation angles of diffracted fringes. The micro-sized gratings were fabricated on the surface of the material at high speeds by illuminating the interference fringe generated by passing a high-energy pulse laser through the Fresnel biprism. In addition, analysis of the grating's diffraction fringes was performed using a continuous wave laser.

Experimental investigations on characteristics of stable water electrospray in air without discharge.

An experimental study was conducted to resolve previous conflicting results on water electrospray in air at atmospheric pressure. Using a small flow rate relative to that used in previous studies and a small nonmetallic nozzle, we observed stable electrospray of water in air without discharge and distinguished three distinct operating regimes for applied voltage and flow rate. The well-known cone-jet mode was observed and the general scaling law of the generated droplet size in the cone-jet mode was confirmed by direct visualization of the meniscus, jet, and generated droplets.

High-harmonic generation by field enhanced femtosecond pulses in metal-sapphire nanostructure.

Plasmonic high-harmonic generation (HHG) drew attention as a means of producing coherent extreme ultraviolet (EUV) radiation by taking advantage of field enhancement occurring in metallic nanostructures. Here a metal-sapphire nanostructure is devised to provide a solid tip as the HHG emitter, replacing commonly used gaseous atoms. The fabricated solid tip is made of monocrystalline sapphire surrounded by a gold thin-film layer, and intended to produce EUV harmonics by the inter- and intra-band oscillations of electrons driven by the incident laser.

Note: O-ring stack system for electron gun alignment.

We present a reliable method for aligning an electron gun which consists of an electron source and lenses by controlling a stack of rubber O-rings in a vacuum condition. The beam direction angle is precisely tilted along two axes by adjusting the height difference of a stack of O-rings. In addition, the source position is shifted in each of three orthogonal directions.