Emitter Configuration Research Articles

Importance of Ultraviolet-C (UV-C) Emitter Configuration for the Attenuation of Staphylococcus aureus and Candida auris Pathogens.

The relative importance of different ultraviolet-C (UV-C) emitter configurations on the attenuation of vegetative bacterial and fungal pathogens has not been assessed. We hypothesized that emitter configuration would impact the efficacy of UV-C attenuation of Staphylococcus aureus ( S. aureus) and Candida auris (C. auris) pathogens. American Type Culture Collection (ATCC) S. aureus (ATCC 6538) and C. auris (ATCC MYA-5001) carriers (ReadyNowTM Test Carriers, Stratix Labs Corporation, Saint Paul, MN) were mounted on an aluminum stand along with three calibrated radiometers (International Light Technologies model ILT1270, Peabody, MA). Five UV-C emitter configurations were assessed, including three emitters with a triangular configuration about the stand and each rotating 360° (1), one emitter facing the stand and rotating 360° (2), three emitters facing the stand in a linear configuration and each rotating 5° (3), one emitter facing the stand and rotating 5° (4), and one emitter facing the stand and rotating 90° (5). Three serial experiments were conducted. The first experiment involved the establishment of the minimally effective irradiation dose (mean and standard deviation mJ/cm2) required to achieve no growth (6-log reduction (LR)) with direct exposure to pathogen carriers positioned at the center of the lamp. We then assessed the relative efficacy of delivery of the minimally effective dose via the five emitter configurations in attenuating polycarbonate and textured pathogen carriers. Polycarbonate carriers were positioned at 25.5 and 69.5 inches from the floor and oriented vertically to the emitters. Textured plastic pathogen carriers were positioned at 47.5 or 58.5 inches from the floor and with a 45° or horizontal orientation to the emitters. Standard carriers (1"x0.9") were used for both pathogens and large carriers (1"x3") for C. auris,the latter to address the potential for cell clustering. With standard carriers, the minimally effective dose was 27.01± 0.15 mJ/cm2 for S. aureus but was not achieved for C. auris. The minimally effective dose for large C. auris carriers was 596.62 ± 27.98 mJ/cm2. With standard carriers, all configurations achieved a >6 log reduction for S. aureus, and none achieved a >6 log reduction for C. auris.All configurations achieved a > 6 log reduction when 596.62 ± 27.98 mJ/cm2 was delivered to large C. auris carriers. Changing to textured plastic carriers (standard for S. aureus and large for C. auris) and varying height (47.5-69.5 inches) from the floor and orientation to the emitters (45° and horizontal), the mean ± standard deviation for S. aureus and C. auris log reductions with delivery of the minimally effective dose was 4.44 ± 2.02, 2.58 ± 2.37, 3.55 ± 2.67, 2.33 ± 2.47, and 3.00 ± 2.64 for configurations one through five, respectively. Configuration one achieved a significantly greater LR than configurations two (adjusted P = 0.0018) and four (adjusted P = 0.023). There were 22% (6/27) of sites ≥ 100 colony-forming units (CFU) following cleaning but before UV-C vs. 0% (0/27) of sites ≥ 100 CFU after surface disinfection cleaning and nine minutes of configuration three UV-C treatment (P = 0.023). The choice of UV-C emitter configuration can impact S. aureus and C. auris attenuation when there is indirect exposure to the pathogen. Emitter configuration should be considered as an important parameter for future UV-C technological assessments.

Importance of Ultraviolet-C (UV-C) Emitter Configuration for Clostridioides difficile Attenuation.

The impact of ultraviolet-C (UV-C) emitter configuration on pathogen attenuation has not been assessed. We hypothesized that emitter configuration would impact UV-C efficacy forClostridioides difficile(C. difficile) attenuation. C. difficilecarriers(ReadyNowTM Test Carriers, Stratix Labs Corporation, Saint Paul, MN) inoculated with > 108 C. difficile American Type Culture Collection (ATCC) 43593 (according to American Society for Testing and Materials (ASTM) 3135 standards) were obtained, and the following experiments were conducted from April to August of 2023. Each of the three carriers along with three calibrated radiometers (ILT1270, International Light Technologies, Peabody, MA) were mounted on an aluminum stand at positions A (left of center of stand), B (center of stand), and C (right of center of stand). The stand was positioned at 9 feet (2.74 m) from and directly ahead of UV-C emitters utilizing low-pressure mercury gas UV-C lamps (Surfacide, Waukesha, WI). Five UV-C emitter configurations were assessed; (1) three emitters with a triangular configuration about the stand and each rotating 360 degrees, (2) one emitter facing the stand and rotating 360 degrees, (3) three emitters facing the stand in a linear configuration and each rotating 5 degrees, (4) one emitter facing the stand and rotating 5 degrees, and (5) one emitter facing the stand and rotating 90 degrees. Three serial experiments were conducted. The first experiment used a dose titration curve to identify the minimally effective irradiation dose (mean and standard deviation mJ/cm2) to achieve no growth (6-log reduction) in C. difficile counts with direct irradiation exposure. The second experiment involved assessing the relative efficacy of the five emitter configurations with the use of the minimally effective dose in attenuating polycarbonate C. difficile carrierspositionedat 25.5 and 69.5 inches (64.77 to 176.53 cm) from the floor and oriented vertically to the emitters. The third experiment evaluated the relative efficacy of the five configurations for polycarbonate and textured plastic C. difficile carriers positioned at 25.5 or 58.5 inches (64.77 to 148.59 cm) from the floor and with a 45-degree or horizontal orientation to the emitters. We assessed residual anaerobic bacterial contamination for three intensive care unit (ICU) rooms to ascertain clinical applications of study results. The minimally effective dose for polycarbonate C. difficile carriers with direct exposurewas 432.28 ± 2.12 mJ/cm2. Configurations one through five achieveda > 4-log reduction when the minimally effective dose was delivered to polycarbonate C. difficile carriers that were positioned at 9 feet from the emitters, 25.5 or 69.5 inches from the floor, and with vertical orientation to the emitters. When C. difficile carriers were changed to textured plastic, orientation to the emitters was changed to horizontal or 45 degrees, and height from the floor was changed to 25.5 and 58.5 inches, the log reductions achieved by configuration one through five were 1.61, 0.61, 0.79, 1.15, and 0.98, respectively, with configuration one achieving a greater log reduction than two (P = 0.0137).In each of the three ICU rooms,at least one of nine sampled locations returned ≥ 500 anaerobic CFU, indicating the need for at least a 0.7-log reduction (500 to 99 CFU). UV-C emitter configuration impacts efficacy in attenuating C. difficile.

Maximizing the notional area in single tip field emitters

One of the critical aspects in advancing high-brightness field emitter devices is determining the conditions under which single-tip emitters should be constructed to optimize their emission area. Recent experiments have explored varying the axis ratio ξ of the cap of a single-tip emitter, ranging from an oblate semi-spheroid to a prolate shape, mounted on a nearly cylindrical conducting body. In this work, we present a strategy, based on high-accuracy computer simulations using the finite element technique, to maximize the emission area of those single-tip emitters. Importantly, our findings indicate that the notional emission area achieves its maximum when the emitter’s cap is adjusted to an oblate semi-spheroid with a characteristic axis ratio ξC≈0.85. We do a comparison of notional emission area as a function of ξ for an ellipsoidal emitter on a post and compare these results from other emitter configurations, which are feasible to fabricate.

Pneumatic spray delivery-based fixed spray system configuration optimization for efficient agrochemical application in modern vineyards.

The hydraulic spray delivery (HSD)-based solid set canopy delivery system (SSCDS) emitter configuration has been optimized for agrochemical applications in vertical shoot position (VSP) vineyards. It uses cost-prohibitive emitters, and their placement restricts the mechanical pruning activities. Therefore, this study focused on optimizing the spray performance of a pneumatic spray delivery (PSD)-based SSCDS variant that addresses the earlier issues. Three PSD-SSCDS emitter configurations (C1-C3) were designed using modified low-cost emitters (E1: modified flat fan, E2: 90° modular flat fan) for agrochemical applications in VSP vineyards. C1 had an E1 installed on trellis posts at 1.67 m above ground level. C2 had a pair of E2 installed per vine at 0.3 m below the cordon, while C3 combined the emitter placement of C1 and C2. The spray deposition (ng cm-2) and coverage (%) were quantified (mean ± standard error) using mylar cards and water-sensitive paper samplers placed within the canopy, respectively. Spray deposition for C1, C2, and C3 was 301.12 ± 63.30, 347.9 ± 66.29, and 837.6 ± 92.53 ng cm-2, respectively. Whereas spray coverage for corresponding configurations was 18.02 ± 2.63, 8.98 ± 1.84, and 28.84 ± 2.46%, respectively. Overall, configuration C3 provided significantly higher spray deposition and coverage than C1 and C2. Substantially reduced system installation cost and emitter density per hectare with improved spray performance were achieved by C3 compared to earlier optimized HSD-SSCDS configuration in the VSP vineyards. © 2024 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Novel complementary Sziklai pair based high gain low noise small-signal amplifiers

<span lang="EN-US">A new paired configuration of opposite polarity BJTs, the “complementary Sziklai pair” is introduced in the series of multi-BJT-based devices like Darlington and Sziklai pair, and its viability is tested in small-signal common emitter (CE) and common collector (CC) amplifier configurations. The Darlington and Sziklai both face the problem of poor frequency response at a higher frequency which is addressed by the proposed configuration. The proposed pair with CE amplifier holds class-A amplification property with a high voltage gain of 200.05, a high current gain of 11.62, wider bandwidth of 1.64 MHz, and a low THD of 1.29E-6%, hence supports the potential of wide applicability in analog communication. Similarly, the proposed pair with CC configuration produces approximately a unit current gain of 0.99 with wider bandwidth of 1.90 MHz and low THD of 1.76E-6%, therefore it can be used as a current buffer in a generalized current follower circuit. Conclusively, the device structure of this new BJT pair may be considered the third consecutive member of the series of Darlington pair and Sziklai pair. The layout of the proposed CE and CC amplifier occupy small areas of 158.30 μm<sup>2</sup> (10.23×15.47 μm) and 141.16 μm<sup>2</sup> (10.20×13.84 μm) respectively in 180 nm process technology.</span>

Oxidative stability and oxygen permeability of oil-loaded capsules produced by spray-drying or electrospraying measured by electron spin resonance

The oxidative stability and the oxygen permeability of oil-loaded capsules were investigated by Electron Spin Resonance (ESR). The capsules were produced by spray-drying or electrospraying in the monoaxial or coaxial configuration using glucose syrup as the encapsulating agent. ESR-spin trapping results showed that electrosprayed capsules oxidized faster and during the early stages of incubation, irrespective of the emitter configuration (monoaxial or coaxial), when compared to those produced by spray-drying. Furthermore, ESR oximetry showed that oxygen inside the spray-dried capsules reached equilibrium with the surrounding atmosphere significantly slower than the monoaxially electrosprayed capsules (i.e., ∼2h and ∼10 min, respectively). These findings have been attributed to the larger particle size of the spray-dried capsules influencing the oxygen diffusion area (i.e., lower surface-to-volume ratio) and diffusion path (i.e., thicker encapsulating wall for a fixed oil load). Together, the lower oxygen uptake reported for the spray-dried capsules correlated well with their higher oxidative stability.

Ab initio spatial phase retrieval via intensity triple correlations.

Second-order intensity correlations from incoherent emitters can reveal the Fourier transform modulus of their spatial distribution, but retrieving the phase to enable completely general Fourier inversion to real space remains challenging. Phase retrieval via the third-order intensity correlations has relied on special emitter configurations which simplified an unaddressed sign problem in the computation. Without a complete treatment of this sign problem, the general case of retrieving the Fourier phase from a truly arbitrary configuration of emitters is not possible. In this paper, a general method for ab initio phase retrieval via the intensity triple correlations is described. Simulations demonstrate accurate phase retrieval for clusters of incoherent emitters which could be applied to imaging stars or fluorescent atoms and molecules. With this work, it is now finally tractable to perform Fourier inversion directly and reconstruct images of arbitrary arrays of independent emitters via far-field intensity correlations alone.

A tip-enhanced quantum emitter with integrated TiO2 slot waveguides in the optical regime

We study the coupling between a nanoscopic dielectric slot waveguide and a metallic-tip-enhanced dipole quantum emitter and search for optimal emission and guiding of photons along a titanium dioxide photonic waveguide. Finite element calculations are used to characterize the mode properties of the waveguide over a range of parameters and predict the efficiency of emission guidance along the waveguide. We show how the effective quantum yield is dependent on the waveguide parameters as well as the dipole position and orientation and show that the integrated system can reach a maximum quantum yield of more than 30% along each direction of the waveguide. By placing the dipole emitter near the apex of a silver nanotip situated above or inside the slot waveguide to increase the overall emission rate, we also enable the capability of controlling the emitter–waveguide​ coupling in situ. We numerically compute the excitation and radiation fields and find that despite a reduction in the quantum yield, a 35-fold increase in the overall emission rate can be obtained due to very large field enhancement factors of up to 4000 at the location of the dipole. By using alternative materials for the tip, this tip-enhanced-waveguide approach has the potential of further increasing the guided photon emission rate. With the possibility of controlling emitter–waveguide coupling in situ, this tip-enhanced emitter configuration provides an alternative approach for the realization of an efficient single-photon source.

Influencing factors and characterization methods of the anti‐clogging ability of labyrinth channel emitters

AbstractTo quantitatively evaluate the anti‐clogging performance of labyrinth channel emitters, literary data were used to study the clogging of different emitters under different conditions. The results showed that the emitter clogging comprehensive evaluation index (Ia) can be used as an inherent property of labyrinth flow channel emitters, denoted as the anti‐clogging ability characterization index, which is affected by flow channel structure parameters and dimensions. The larger Ia is, the more likely it is for the emitter to be clogged and for clogging to be more serious. The emitter anti‐clogging ability is affected by the emitter discharge (Q), flow path length (L), width (W), depth (D), cross‐sectional area (A, which equals W × D), minimum sectional size (min(D, W)), etc. The Ia value with Q, W, D, A and min(D, W) increases first decreases and then increases, and with L increases first increases and then decreasing, and a critical threshold range exists. Ia can be estimated by Q, W, D, A and min(D, W) and can be used as an effective indicator to quickly estimate emitter anti‐clogging ability and emitter configuration in drip irrigation systems. In practical applications, an emitter with x < 0.47 (flow index) should be selected, and an emitter with Ia < 0.45 has a better hydraulic performance and anti‐clogging ability. To obtain a better anti‐clogging ability, Q, W, D, A and min(D, W) should be 1.33–2.13 L/h, 0.71–0.90 mm, 0.55–0.71 mm, 0.33–0.68 mm2 and 0.60–0.75 mm, respectively. When L is 26.47–58.31 mm, the emitter anti‐clogging ability is relatively low.

Connecting steady-states of driven-dissipative photonic lattices with spontaneous collective emission phenomena

Recent experimental advances enable the fabrication of photonic lattices in which the light propagates with engineered energy dispersions. When interfaced with quantum emitters, such systems yield strong collective spontaneous emission phenomena, such as perfect sub-radiance, in which the decay into the bath is completely suppressed, forming bound-states-in-the-continuum (BIC). Since such photonic lattices are generally lossy, an alternative way of probing them consists in coherently driving them to an steady-state from which photoluminescence can be extracted. Here, we formalize connections between these two seemingly different situations and use that intuition to predict the formation of non-trivial photonic steady-states in one and two dimensions. In particular, we show that subradiant emitter configurations are linked to the emergence of steady-state light-localization in the driven-dissipative setting, in which the light features the same form than the spontaneously formed BIC. Besides, we also find configurations which leads to the opposite behaviour, an anti-localization of light, that is, it distributes over all the system except for the region defined between the driving lasers. These results shed light on the recently reported optically-defined cavities in polaritonic lattices, and can guide further experimental studies.

Numerical simulation and analysis of dual base transistor laser

AbstractIn this work, characteristics of dual base transistor laser are numerically analyzed for the first time. Active base region of the transistor laser is split into two unequal regions composing of shorter and longer sections, which are biased separately. Static characteristics of transistor laser are evaluated using a rate equation model, which reveals switching action in output optical power for a longer section base current of 9.2 mA with unpumped shorter section. Hysteresis behavior in the optical output is observed for the longer section input current till 1.6 mA. Optical bistable characteristics are studied for various values of gain (longer) and absorber (shorter) section currents. Further slope efficiency is evaluated using P‐I characteristics, before the onset of bistability, for gain lever features under common emitter (CE) configuration. A maximum gain lever of 4.5 dB is observed with the longer section bias current of 1.3 mA.

Key design and operation factors for high performance of C12A7:e-based cathodes

This work, based on an EU-funded project (NEMESIS), is summarising some of the results from the project activities on the research and development on electride-based cathode technology compatible with all kinds of electric propulsion (EP) systems requiring neutralization or electron emission. Further information describing in detail the performed tests and captured measurements can be found in the referenced documents of each section. Different cathode architectures and several emitter configurations with traditional and with alternative propellants are being developed and tested within the project, all of them using C12A7:e-electride material as thermionic electron source. Findings and conclusions derived from these multiple designs are allowing to figure out some of the key factors that determine the best performance of C12A7:e-electride based cathodes. In this work, a discussion of some of these key design and operation factors will be presented based both on the material characterization parameters, and on the performance tests carried out for the different cathode designs.

Single Photon Emitters Coupled to Plasmonic Waveguides: A Review

AbstractDuring the last two decades, many research groups have demonstrated coupling of single photon emitters to plasmonic waveguides, promising very high emission enhancements, for applications in quantum technologies. In this review, recent developments within this important research topic are discussed. Different plasmonic waveguide–quantum emitter configurations are compared from the application viewpoint by utilizing a figure‐of‐merit (FOM) reflecting the emission enhancement, coupling efficiency, and radiation loss. The experimental methods applied to obtain the coupled systems with high FOMs are described. Configurations that are exploited for reinforcing the coupling efficiency, i.e., the efficiency of funneling the emitted radiation into a plasmonic waveguide, are also considered as well as the scalability potential of various waveguide platforms. A recent experiment, in which enhanced light–matter interaction in a plasmonic waveguide is taken advantage of, resulting in the demonstration of non‐linearity at the single emitter level, is discussed.

An arduino experiment for measuring the base amplification factor of NPN transistors

The hFE of a transistor, or commonly known as the hybrid parameter forward current gain, is one of the important factors that characterizes the working of a transistor in any circuit. So designing such an experiment with readily available materials would help STEM students gain more intuition about the working principle of transistors in general. In this experiment we had used an Arduino UNO microcontroller along with some resistors and by using Ohm’s law we were able to deduce a formula for the hFE (hybrid parameter current gain) of any npn transistor used in the circuit, just by measuring the voltages across the input and output resistors used along with the transistor in a common emitter configuration.

Effect of Collector Voltage on the Large and Small Signal Modulation Characteristics of 980 nm Transistor Laser

Theoretical analysis of Transistor Laser is carried out and the static and frequency responses for different collector voltages, under common emitter configuration are determined. The threshold current (Ith) is observed as 33mA and it increases linearly with reverse collector to base voltage (VCB). Meanwhile, the output optical power is found to decrease proportionately when VCB is increased. A maximum of 18.7GHz modulation bandwidth is observed when an input base current of 95 mA is applied at a fixed value of VCB (1V). The modulation bandwidth is found to decrease with increase in reverse VCB. The turn on delay increases with collector voltage. However, it decreases with increase in base current.

Numerical study of mono-crystalline silicon solar cells with passivated emitter and rear contact configuration for the efficiency beyond 24% based on mass production technology

Mono-crystalline silicon solar cells with a passivated emitter rear contact (PERC) configuration have attracted extensive attention from both industry and scientific communities. A record efficiency of 24.06% on p-type silicon wafer and mass production efficiency around 22% have been demonstrated, mainly due to its superior rear side passivation. In this work, the PERC solar cells with a p-type silicon wafer were numerically studied in terms of the surface passivation, quality of silicon wafer and metal electrodes. A rational way to achieve a 24% mass-production efficiency was proposed. Free energy loss analyses were adopted to address the loss sources with respect to the limit efficiency of 29%, which provides a guideline for the design and manufacture of a high-efficiency PERC solar cell.

Circuit analysis and optimisation of the high‐voltage high‐efficiency IR‐UWB pulse generator for ranging and radar application

An in-depth circuital analysis of an energy-efficient high peak power impulse radio ultra-wideband (IR-UWB) pulse generator monolithic microwave integrated circuit (MMIC) design is presented. The proposed IR-UWB pulse generation process is explained in detail. A trade-off between the peak output power level and the frequency of operation is discussed. The proposed circuit is optimised for the highest possible peak output power in the 3–5 GHz UWB band for ranging and radar application. The presented IR-UWB pulse former makes use of the cascode heterojunction bipolar transistor (HBT) configuration for signal scaling operation instead of the common emitter configuration. The proposed cascode pair configuration results in higher output voltage swing as well as reduced power consumption. The effect of coupling capacitors on amplification factor of the pulse former stages as well as impedance profile of the distributed transmission line is discussed in great detail. The temperature-dependent parasitic component in the proposed circuit is studied. Its effect on the transient behaviour of the proposed IR-UWB pulse generator is analysed, which is important for IR-UWB beamforming applications. The required mathematical model for the parasitic effect is derived and explained.

A novel method for calculating heat emitter and controller configuration setpoint variations with EN15316-2

Estimating heat emission losses of heating systems is an important task of energy efficiency assessments in buildings. However, the present international standards do not specify how emission losses should be calculated or measured for different emitter and control system configurations. Aiming to fill this gap, here we propose a method for computing the temperature setpoint variations by addressing the heat distribution throughout a room with space heat emitters. This general and exact procedure enables the calculation of product category-specific setpoint variations for different types of heat emitters, accounting for the overall heat balance in the enclosure and including the cross-correlations of each component. Our method complements the procedure presented in the Standard EN15316-2, making it possible to compute emission losses as product-specific values of setpoint variations instead of tabulated values. As the main finding of the study, the calculation process is defined for a European Reference Room that allows an accurate and transparent evaluation of total setpoint variations. These are computed for specific products from measured vertical stratification and control parameters, by means of an annual IDA ICE simulation model of the reference enclosure. Applying the method to an annual energy performance simulation for an old and a new building in Strasbourg shows that emission losses are compensated by a total setpoint variation of respectively up to 2.00 °C and 1.20 °C, corresponding to an increase in total heating energy usage of up to 22% and 20%.

A 4.2-to-5.4 GHz stacked GaAs HBT power amplifier for C-band applications

PurposePower amplifiers (PAs) play an important role in wireless communications because they dominate system performance. High-linearity broadband PAs are of great value for potential use in multi-band system implementation. The purpose of this paper is to present a cascode power amplifier architecture to achieve high power and high efficiency requirements for 4.2∼5.4 GHz applications.Design/methodology/approachA common emitter (CE) configuration with a stacked common base configuration of heterojunction bipolar transistor (HBT) is used to achieve high power. T-type matching network is used as input matching network. To increase the bandwidth, the output matching networks are implemented using the two L-networks.FindingsBy using the proposed method, the stacked PA demonstrates a maximum saturated output power of 26.2 dBm, a compact chip size of 1.17 × 0.59 mm2 and a maximum power-added efficiency of 46.3 per cent. The PA shows a wideband small signal gain with less than 3 dB variation over working frequency. The saturated output power of the proposed PA is higher than 25 dBm between 4.2 and 5.4 GHz.Originality/valueThe technology adopted for the design of the 4.2-to-5.4 GHz stacked PA is the 2-µm gallium arsenide HBT process. Based on the proposed method, a better power performance of 3 dB improvement can be achieved as compared with the conventional CE or common-source amplifier because of high output stacking impedance.

A wavelength selective emitter design method using hyperbolic tangent level set-based shape optimization

A wavelength selective emitter is one of the key elements of the TPV generation system. Recently, a wavelength selective emitter with periodic microstructure on the surface has attracted attention. In this study, we propose a nonparametric design method of the wavelength selective emitter, which utilizes a shape optimization technique. The proposed method provides a design example of a 1D grating wavelength selective emitter that shows near unity emissivity at target wavelength. The obtained optimal configuration utilizes two physical mechanisms for the emissivity improvement: the excitation of the surface plasmon polariton and the cavity resonance. Furthermore, by considering multiple wavelengths, the proposed method can also provide an emitter configuration which has higher wavelength selectivity performance.