Multiple Trapping Research Articles

Optical twin-vortex multi-trapping by Kolakoski lenses

In this work, we design and implement a new bifocal diffractive spiral lens within an optical tweezers system. The proposed diffractive optical element coined Kolokaski Kinoform Spiral Lens (KKSL), generates twin optical vortices along the propagation direction. The axial positions, as well as the diameters of the generated vortex beams, are correlated with the Kolakoski aperiodic sequence introduced in the design of the diffractive lens. The unique properties of KKSLs make it ideal for optical trapping applications, allowing independent multiple trapping and particle displacement within each optical vortex beam. We present both the focusing properties of KKSL and the experimental results of its integration into the optical tweezer setup.

Generating controllable optical trap arrays with a polarization-based metalense

Metalenses have been widely used in various optical systems due to their compact size, lightweight nature and high efficiency. This paper presents a novel metalense for generating multiple optical trap arrays. The proposed metalense is composed of many unit cells of half-wave plate. By changing the polarization state of the incident light, the optical trap array generated by the metalense can be controlled. To evaluate its performance, we simulate the metalense with total trap numbers of 4 and 6 respectively. The results show that the produced optical trap arrays exhibit precise positioning, uniform size, and intensity distribution. Furthermore, the arrays maintain excellent uniformity and shape integrity even when the number of optical traps is increased. Compared with the previous metalenses only produce a specific optical trap array, the designed metalense offers higher flexibility and better meets the experimental requirements of multi-trap optical tweezers. Our metalense exhibits significant potential for the integration and miniaturization of optical trap arrays, as well as other focusing optical systems.

Steady and transient modeling of dye-sensitive solar cells: The impact of electrode thickness and dye specifications

Investigating the impact of dye compounds on cell performance is crucial for advancing dye-sensitized solar cells (DSSCs). This research focuses on the sensitivity analysis of the effect of critical parameters to enhance DSSC efficiency using a thermo-electric numerical model. These parameters include dye types, trapping parameters, diffusion coefficients, and photoanode thickness. When the type of dye changes, in fact, both physical and chemical properties (molar absorption coefficient, etc.) Change, but to avoid the complexity of solving the equations and only to evaluate the effect of the absorption wavelength range on the cell performance only changes in physical properties are considered. The model calculates steady and transient currents under actual weather conditions and sunlight. It incorporates time/space-dependent relationships for increased accuracy and examines electron, iodide, and triiodide ion interactions under varying environmental conditions. Key concepts include the quasi-Fermi level and the multiple trap model, assuming that trapping processes are faster than electron transport and recombination. The results showed that increasing the trapping parameter can affect the transient current behavior, also increasing the thickness of the photoanode and the wavelength range of the dye increases the efficiency of the cell, so that the N749-BD provides the best performance. The findings provide insights into current–voltage characteristics, electron production, and the effects of photoanode thickness and dye types on cell performance, offering pathways for optimizing DSSC technology.

Switchable optical trapping and manipulation enabled by polarization-modulated multifunctional phase-change metasurfaces

Optical trapping, a cutting-edge methodology, is pivotal for contactlessly controlling and exploring microscopic objects. However, it encounters formidable challenges such as multiparticle trapping, flexible control, and seamless integration. Here, we employ a polarization-modulated multi-foci technique for versatile nanoparticle trapping using multifunctional metasurfaces relying on geometric phase. Numerical simulations demonstrate the generation of two focused spots with orthogonal polarization distributions through our metasurfaces when illuminated with linearly polarized light, with their polarization distributions be interchanged by orthogonally switching the incident polarizations. We extend this design to an array of multi-foci metasurface tweezers modulated by polarization, highlighting the versatility and robustness of our approach. Furthermore, we demonstrate the simultaneous generation of two distinct focusing cylindrical vector beams using a monolayer metasurface, showcasing the two vector beams possess the interchange ability of their polarization distributions. By leveraging the Maxwell stress tensor, we assess the distinct contributions of the focused beams to longitudinal and transverse optical forces on SiO2 spheres, validating diverse trapping and manipulation behaviors for nanoparticles with the proposed metasurface designs. By manipulating the phase states of Sb2S3 nanopillars, binary-switchable optical trapping and manipulation are facilitated for all proposed metasurface tweezers. Our work underscores the efficacy of polarization-modulation multifunctional metasurface tweezers in consolidating multiple trapping tasks into a single device, paving the way for innovative lab-on-a-chip optical trapping applications in biophysics, nanotechnology, and photonics.

Variable-order fractional diffusion: Physical interpretation and simulation within the multiple trapping model

The physical interpretation of a variable-order fractional diffusion equation within the framework of the multiple trapping model is presented. This interpretation enables the development of a numerical Monte Carlo algorithm to solve the associated subdiffusion equation. An important feature of the model is variation in energy density of localized states, when the detailed balance condition between localized and mobile particles is satisfied. The variable order anomalous diffusion equations under consideration can be applied to the description of transient subdiffusion in inhomogeneous materials, the order of which depends on the considered spatial and/or time scale. Examples of numerical solutions for different situations are demonstrated. Considering variable-order fractional drift, we calculate and analyze the transient current curves of the time-of-flight method for samples with varying density of localized states.

Techno-economic assessment of supercritical, cold liquid, and dissolved CO2 injection into sub-seafloor basalt

Injecting CO2 into subsea basalt can provide permanent storage via multiple trapping mechanisms, including mineralization reactions which convert the CO2 into solid carbonates over time. Injecting CO2 together with water can accelerate the process of mineralization, but presents additional challenges, such as high energy and water requirements. A techno-economic model of CO2 transport and injection into ocean basalt was developed to compare injection strategies using pure supercritical CO2, pure liquid CO2, and CO2 dissolved in seawater. The model was applied to a representative injection site off the coast of British Columbia, Canada. Injection of CO2 dissolved into seawater was found to be more energy and cost intensive than injection of supercritical or liquid CO2; this is primarily due to the reduced quantities of CO2 that can be injected into each well, and additional pumping energy required for the accompanying seawater. For the base assumptions, transport and storage costs for supercritical, liquid, and dissolved injection were estimated as $43/t, $38/t, and $250/t respectively. Their energy requirements were estimated as 93 kWh/t, 90 kWh/t, and 213 kWh/t respectively. The current best estimates of geological parameters for ocean basalt suggest good injectivity and very large storage capacities per well. This may help to compensate for the additional project expenses incurred by deep water, allowing cost-effective liquid and supercritical injection. However, this result is sensitive to high uncertainties in both geological parameters and component cost data.

Theoretical study on the thermoluminescence kinetics by glow curve analysis based on the genetic algorithm

The analysis of thermoluminescence (TL) glow curve is an important way to investigate the trap structure of the materials as well as the kinetics of the charge carrier transfer. Most currently used methods rely on the existence of an explicit expression of the theoretical glow curve. However, since the set of kinetic equations describing the TL process does not have analytical solutions, the derivation of an explicit expression always involves some sort of assumptions and approximations, which can compromise the universality and accuracy of the method. This paper proposes a new algorithm that focuses on the original kinetic equations and does not necessitate an explicit expression to analyze the TL glow curve. This algorithm establishes an objective function to evaluate the fitness of a selected combination of kinetic parameters, and then using the genetic algorithm (GA) to search for the optimal parameters. Various occasions were numerically simulated, demonstrating the algorithm's capability to handle kinetics of different order, multiple interactive peaks, deep trap, non-linear heating, and temperature dependent parameter cases. An actual glow curve of the LiF:Mg,Cu,P chip was also analyzed using this algorithm, and the corresponding kinetic parameters were identified. This algorithm provides a more universal and valid method for TL glow curve analysis.

Tunable plasmonic tweezers based on nanocavity array structure for multi-site nanoscale particles trapping

The ability of plasmonic optical tweezers based on metal nanostructure to stably trap and dynamically manipulate nanoscale objects at low laser power has been widely used in the fields of nanotechnology and life sciences. In particular, their plasmonic nanocavity structure can improve the local field intensity and trap depth by confining electromagnetic fields to subwavelength volumes. In this paper, the R6G dye molecules with 10−6 M were successfully trapped by using the Ag@Polydimethylsiloxane nanocavity array structure, and a R6G micro-ring was formed under the combined action of plasmonic optical force and thermophoresis. Subsequently, the theoretical investigation revealed that the trapping performance can be flexibly adjusted by changing the structural parameters of the conical nanocavity unit, and it can provide a stable potential well for polystyrene particles of RNP = 14 nm when the cavity depth is 140 nm. In addition, it is found that multiple trapping sites can be activated simultaneously in the laser irradiation area by investigating the trapping properties of the hexagonal conical nanocavity array structure. This multi-site stable trapping platform makes it possible to analyze multiple target particles contemporaneously.

Optical trapping of nanoparticles using all-dielectric quasi-bound states in the continuum

Plasmonic nanotweezers employing metallic nanostrctures provide a powerful tool for optical trapping of nanoscale objects; however, they are limited by strong heating effects resulting from the intrinsic loss in metallic materials. Alternatively, quasi-bound states in the continuum (q-BICs), supported in all-dielectric metasurfaces, offer a higher quality-factor (Q-factor) and electric field enhancement compared to plasmonic systems, making it a promising candidate for heatless nanotweezers with high performance. Here, we demonstrate an all-dielectric nanotweezer harnessing q-BIC for effective trapping of nanoparticles with low trapping power and negligible heating effects. The quasi-BIC system provides very high electromagnetic field intensity enhancement as well as high-quality-factor resonances. The q-BIC mode is induced by symmetry breaking of periodic double ring nanostructure, which leads to an increased optical force and potential energy in comparison to prior studies, enabling attractive promise in subwavelength particle trapping applications. Moreover, the q-BIC nanotweezer creates numerous optical hotspots characterized by significant field confinement and enhancement, generating multiple trapping sites and thus facilitating high-throughput trapping of nanoscale objects. Furthermore, the trapping wavelength (1047.59 nm) in our structure exactly corresponds with the current laser choice for working with biological samples. In addition, we show that trapped particles can improve the resonance mode of the cavity in a symmetry-broken system, which in turn enhances the trapping process. Our study paves the way for applying q-BIC systems to low-power particle trapping and sensing applications, especially for parallel analyses of biological cells and protein molecules.

Controllable multi-autofocusing of chirped multi-Pearcey beams and their trapping performance on Rayleigh particles

The exploration of structured light created through autofocusing beams has attracted widespread attention in optical manipulation. Here, we investigate the propagation dynamics of chirped multi-Pearcey beams (CMPBs) in theory and experiment, especially exploring the impact of chirped factors on the autofocusing characteristics of CMPBs. It is found that the autofocusing characteristics of the beams can be significantly modulated by introducing first-order and second-order chirped factors. Specifically, the first-order chirped factor greatly improves the autofocusing coefficient of CMPBs, while the second-order chirped factor introduces multiple autofocusing propagations. By analyzing the transverse power flow of CMPBs both without and with chirped factors, we explain why the chirped factors can remarkably strengthen the autofocusing performance of CMPBs. Finally, our theoretical analysis on trapping force on Rayleigh particles indicates that the introduction of chirped factors optimizes the intensity gradient and trapping capability of CMPBs, potentially enabling multiple longitudinal trapping positions. These findings offer a comprehensive insight into the propagation dynamics of CMPBs, opening avenues for flexible optical manipulation of multiple particles.

Fractional multiple trapping model of time-of-flight transient photocurrents in amorphous semiconductors

Fractional multiple trapping model of time-of-flight transient photocurrents in amorphous semiconductors

Fractional multiple trapping model of time-of-flight transient photocurrents in amorphous semiconductors

Модель многократного захвата оказалась весьма эффективной для понимания переноса неравновесных носителей заряда в аморфных полупроводниках. При определенных условиях эта модель описывается аномальными уравнениями диффузии с производными дробного порядка по времени. Это свидетельствует о полезности модели многократного захвата при интерпретации уравнений переноса дробного порядка, задании начальных и граничных условий и разработке численных методов решения кинетических уравнений дробного порядка. Представлен краткий обзор применения уравнений многократного захвата дробного порядка во времяпролетных экспериментах. Этот метод позволяет лучше понять связь между моделью многократного захвата и обобщенными кинетическими уравнениями дробного порядка. Найдены аналитические приближенные решения уравнения диффузии дробного порядка, включающего в себя многократный захват и преобразование Лапласа. Этот метод можно использовать для анализа пре- и постпролетных режимов переходного тока в аморфных полупроводниках с либо недисперсионным, либо дисперсионным переносом. Эффективность метода проиллюстрирована численным моделированием переходного тока с использованием обратного преобразования Лапласа и аппроксимации Паде. Результаты расчета хорошо согласуются с экспериментальными данными для тонких пленок аморфного селена. Полученные результаты открывают многообещающую перспективу. Во-первых, использование дробного исчисления для решения уравнений многократного захвата является новым по сравнению с имеющимися в литературе подходами и дает основания для включения в дробное исчисление эффектов памяти, когда на решение влияют предыдущие временны́е шаги. Во-вторых, численные результаты демонстрируют хорошее согласие с экспериментальными данными. Таким образом, дробное исчисление может помочь получить новые знания о поведении носителей заряда в аморфных полупроводниках.

Unveiling the potential of lead-free Cs2AgBiBr6 (CABB) perovskite for solar cell application

The remarkable structural stability and optoelectronic properties of Cs2AgBiBr6 (CABB) material have positioned it as a highly appealing candidate for the solar cell application. The research focused on modeling and examination of perovskite solar cells utilizing Cs2AgBiBr6 as the active material, incorporating various electron transport layers (ETL) and hole transport layers (HTL). The device structure comprised of ITO/ZnO:Al/ZnO/Cs2AgBiBr6/Cu2O/Au. This optimized device, shows Voc = 1.67 V, Jsc = 15.52 mA/cm2, fill factor (FF) = 71.32 %, and conversion efficiency = 18.5 %. Active layer defects and trap charges at the interface of the CABB layer can trap photo generated electrons and holes, permitting higher carrier recombination. That reduces both open circuit voltage and short circuit current density. The conversion efficiency deteriorates from 18.5 % to 2.65 % when the defect density increases from 1 × 1010/cm3 from 1 × 1016/cm3. Also trap charges and multiple trap charges play a vital role in the performance of the CABB solar cell.

Effect of porosity on deuterium retention in titanium thin film

Abstract The absorption process of deuterium in titanium was studied in titanium film produced in two different types of copper substrate, one was a polished copper substrate and the other one was chemically etched copper substrate. Titanium film was produced by thermal evaporation method. It was activated at a temperature of 500 0C followed by deuteration at room temperature. Titanium film was characterized by XRD for crystallographic information, SEM for surface morphology, RGA for deuterium desorption studies and weight measurement for D/Ti ratio. The difference in porosity of both the samples is confirmed from XRD analysis and SEM images. Different diffusion process is observed in two different substrates from the RGA spectra. Presence of multiple trap sites in the thin film of both the substrates is observed from the RGA spectra. From the weight measurement, D/Ti ratio in polished substrate is found to be 1.03 whereas in case of chemically etched substrate it is 1.54.

Surveillance and screening of Stomoxyinae flies from Mallorca Island (Spain) reveal the absence of selected pathogens but confirm the presence of the endosymbiotic bacterium Wolbachia pipientis

Adult brachycera biting flies can significantly impact livestock through both direct effects (reduction of food intake, disturbance, painful bites, and blood loss) and indirect effects (pathogen transmission), leading to substantial economic losses and production damage. This study aimed to assess the presence of blood-sucking flies in six mixed-animal farm environments on the island of Mallorca (Balearic Islands, Spain) by employing multiple trapping methods. Additionally, distribution maps of brachycera biting fly species recorded in Spain were created, based on data extracted thorough review of scientific literature and citizen digital databases. Investigation of several pathogens, including equine infectious anemia virus (EIAV), Anaplasmataceae bacteria, and piroplasm protozoa, was carried out using different PCR targets (18S rRNA, 16S rRNA, groESL, and tat genes). Citizen science databases and literature review corroborated the consistent distribution trend for two Stomoxyinae species, underscoring the importance of citizen collaboration as a complement to traditional entomological surveillance. Our study confirmed the presence of two biting Stomoxyinae species: the prevalent stable fly Stomoxys calcitrans across all sampled farms, and the horn fly Haematobia irritans, which turned out to be less abundant. DNA barcoding techniques validated the identification of the two species. Neither EIAV nor bacterial/protozoan pathogens were detected using the selected PCR targets in either fly species. However, Wolbachia pipientis (clustered in the supergroup A together with the only sequence of W. pipientis from the USA) was identified through PCR targeting 16S rRNA, groESL and wsp genes in all pools of H. irritans (n = 13) collected from two of the examined farms. This study represents the first attempt to investigate pathogens in Stomoxyinae biting flies in Spain. The discovery of the endosymbiotic Wolbachia organism in H. irritans represents the first record in Spain and the second from Europe. This finding holds significant implications for future research on the applications of this bacterium in biocontrol programs.

I2-DMSO mediated tetra-functionalization of enaminones for the construction of novel furo[2′,3′:4,5]pyrimido[1,2-b]indazole skeletons via in situ capture of ketenimine cations

The first-ever synthesis of the unknown furo[2′,3′:4,5]pyrimido[1,2-b]indazole skeleton was demonstrated based on the undiscovered tetra-functionalization of enaminones, with simple substrates and reaction conditions. The key to realizing this process lies in the multiple trapping of the in situ generated ketenimine cation by the 3-aminoindazole, which results in the formation of four new chemical bonds and two new rings in one pot. Moreover, the products of this new reaction were found to exhibit aggregation-induced emission (AIE) without modification.

Vacuum-assisted and multi-cumulative trapping in headspace solid-phase microextraction combined with comprehensive multidimensional chromatography-mass spectrometry for profiling virgin olive oil aroma

In the present work vacuum (Vac) and multiple cumulative trapping (MCT) headspace solid phase microextraction (HS-SPME) were evaluated as alternative or combined techniques for the volatile profiling. A higher extraction performance for semi-volatiles was shown by all three techniques. Synergic combination of Vac and MCT showed up to 5-times extraction power for less volatile compounds. The hyphenation of said techniques with comprehensive two-dimensional gas chromatography (GC × GC) enabled a comprehensive analysis of the volatilome. Firstly, 18 targeted quality markers, previously defined by means of classical HS-SPME, were explored for their ability to classify commercial categories. The applicability of such markers proved to be limited with the alternative sampling techniques. An untargeted approach enables the selection of specific features for each technique showing a better classification capacity of the commercial categories. No misclassifications were observed, except for one extra virgin olive oil classified as virgin olive oil in 3 × 10 min Vac-MCT-HS-SPME.

Surface-Potential-Based Drain Current Model for Ambipolar Organic TFTs

A surface-potential-based drain current model is presented for ambipolar organic thin-film transistors (OTFTs). First, following the multiple trapping and release (MTR) conduction mechanism, a drain current model is presented for unipolar OTFTs considering exponentially distributed trap state density in the energy gap of an organic semiconductor. Next, from the model for unipolar OTFTs, analyzing electrons or (and) holes in different regimes, the model for ambipolar OTFTs is presented. The presented model can describe the drain current by compact expressions and can estimate the trap states density. The model is verified by available experimental data considering temperature characteristics.

Small mammal assemblage in Gunung Tebu Forest Reserve, Terengganu: An environmentally sensitive area in East Coast Peninsular Malaysia

Effective spatial planning plays a pivotal role in defining the progress and growth of a certain region. One aspect of spatial planning by PLANMalaysia involves the incorporation of environmentally sensitive areas (ESAs), which comprises eleven different landscape management. Integrating biological features is crucial when defining ESA Permanent Forest Reserve, as relying solely on physical attributes may not accurately reflect the true sensitivity of the environment. Therefore, there is a need to gather biological information to strengthen existing ESA. A study was conducted in Gunung Tebu Forest Reserve (GTFR) from April to July 2023. Multiple trapping approaches were deployed to assess volant and non-volant small mammal assemblage. In total, 155 individuals comprised of 31 species of small mammals were documented with the highest species abundant recorded by Maxomys rajah (n = 29) and Leopoldamys sabanus (n = 27). The diversity indices were varied throughout five sampling sessions, (Shannon = 1.841 to 2.543), (Simpson = 0.7951 to 0.9056). Comparison on species assemblage between GTFR and forest reserves in Hulu Terengganu showed a moderate similarity level. This finding offers the most recent insight of the small mammals in GTFR and highlights the significance of conserving and preserving (ESA) in permanent forest reserves.

Three-dimensional optical multiple trapping using pure amplitude octagonal almost periodic structures.

We demonstrate a novel method for three-dimensional optical multiple trapping using pure amplitude octagonal almost periodic structures (PAOAPSs). We use a Gaussian beam to diffract through these structures and create a three-dimensional array of trapping spots with the aid of an objective lens. Our device is simple, cost-effective, and easy to fabricate, and it has several advantages over conventional methods for trapping multiple particles. By adjusting the rotation of the PAOAPS and the polarization of the beam, we can simultaneously rotate the trapped particles in both axial and orbital directions. We show that our device achieves an ∼19-fold increase in trapping efficiency compared to a recently introduced method based on an amplitude radial grating. Furthermore, our device transfers about 1/70 of the transmitted beam power to each optical trap, which is much more efficient than a spatial light modulator (SLM).