Trapping Medium Research Articles

Ex Situ Evaluation of Beeswax-based Cercarial Trapping: a Collection Tool for Environmental Surveillance of Schistosoma japonicum

Schistosomiasis is a neglected tropical disease that affects over 230 million people worldwide, burdening populations in the margins in countries like the Philippines. Despite the utility of environmental detection methods such as polymerase chain reaction assay, it remains difficult to collect adequate DNA samples from large bodies of water. Hence, studies about the development of cercarial traps for reliable environmental surveillance have become an emerging focus in research, with beeswax being a material of interest as a cercarial attractant. This study investigated the effect of supplemental trap attractants on Schistosoma japonicum cercarial attachment. Three trapping media were prepared using plain beeswax, beeswax with olive oil, and beeswax with pifithrin-μ. Cercariae were collected from crushed Oncomelania hupensis quadrasi snails and then distributed to each trap, with different trapping media, and exposed ex situ for 2 h. The presence of attached cercariae was determined using microscopy. Afterward, data on the cercarial capture percentage (CCP) and cercarial attachment grade (CAG) of the three attractants were recorded and analyzed using a one-way analysis of variance. Results showed that beeswax with pifithrin-μ recorded the highest mean CCP (83.20%). Cercarial attachment in beeswax with olive oil demonstrated the highest attachment with only the head (22.86%), whereas the whole cercariae could be seen attached in most of the traps containing beeswax with pifithrin-μ (99.04%). This study has proven that beeswax-based cercarial traps could be a useful collection tool for the environmental surveillance of schistosomiasis in endemic areas.

Optimization Thickness of Photoanode Layer and Membrane as Electrolyte Trapping Medium for Improvement Dye-Sensitized Solar Cell Performance

Dye-Sensitized Solar Cells (DSSC) are photovoltaic devices that contain a dye that acts as a solar light acceptor. The use of dyesensitized solar cells to solve increasing energy demand and environmental problems still results in low efficiency values. In this study, optimization of DSSC components was carried out to increase DSSC efficiency by varying the thickness of the titanium dioxide (TiO2) semiconductor photoanode layer, polyvinylidene fluoride (PVDF) trap electrolyte membrane, and polyvinylidene fluoride nanofiber (PVDF NF) to obtain the optimum thickness. Scanning Electron Microscope (SEM) results of membrane thickness variation and titanium dioxide (TiO2) semiconductor photoanode coating showed the formation of nanofiber fibers composed of three-dimensional, porous, and diameter networks connected to the PVDF NF membrane. The increase in density and decrease in pore size, along with an increase in thickness and cracking as the TiO2 photoanode semiconductor layer increases, affect the electron transport rate of the DSSC. The higher particle density level will inhibit the electron transport rate, so it can reduce the efficiency of DSSC. The optimum thickness of the TiO2 semiconductor layer and PVDF NF electrolyte membrane of 0.20 mm and 0.35 mm can produce values, voltage, fill factor current density, and electrical efficiency of 500 mV, 2.7 x 10−3 mA.cm−2, 1.80%, and 2.40%, respectively.

Persisting roadblocks in arthropod monitoring using non-destructive metabarcoding from collection media of passive traps.

Broad-scale monitoring of arthropods is often carried out with passive traps (e.g., Malaise traps) that can collect thousands of specimens per sample. The identification of individual specimens requires time and taxonomic expertise, limiting the geographical and temporal scale of research and monitoring studies. DNA metabarcoding of bulk-sample homogenates has been found to be faster, efficient and reliable, but the destruction of samples prevents a posteriori validation of species occurrences and relative abundances. Non-destructive metabarcoding of DNA extracted from collection medium has been applied in a limited number of studies, but further tests of efficiency are required with different trap types and collection media to assess the consistency of the method. We quantified the detection rate of arthropod species when applying non-destructive DNA metabarcoding with a short (127-bp) fragment of mitochondrial COI on two combinations of passive traps and collection media: (1) water with monopropylene glycol (H2O-MPG) used in window-flight traps (WFT, 53 in total); (2) ethanol with monopropylene glycol (EtOH-MPG) used in Malaise traps (MT, 27 in total). We then compared our results with those obtained for the same samples using morphological identification (for WFTs) or destructive metabarcoding of bulk homogenate (for MTs). This comparison was applied as part of a larger study of arthropod species richness in silver fir (Abies alba Mill., 1759) stands across a range of climate-induced tree dieback levels and forest management strategies. Of the 53 H2O-MPG samples from WFTs, 16 produced no metabarcoding results, while the remaining 37 samples yielded 77 arthropod MOTUs in total, of which none matched any of the 343 beetle species morphologically identified from the same traps. Metabarcoding of 26 EtOH-MPG samples from MTs detected more arthropod MOTUs (233) than destructive metabarcoding of homogenate (146 MOTUs, 8 orders), of which 71 were shared MOTUs, though MOTU richness per trap was similar between treatments. While we acknowledge the failure of metabarcoding from WFT-derived collection medium (H2O-MPG), the treatment of EtOH-based Malaise trapping medium remains promising. We conclude however that DNA metabarcoding from collection medium still requires further methodological developments and cannot replace homogenate metabarcoding as an approach for arthropod monitoring. It can be used nonetheless as a complementary treatment when enhancing the detection of soft-bodied arthropods like spiders and Diptera.

Visible Light‐Sensitive Artificial Photonic Synapse

AbstractComputing based on artificial neuron networks holds great promise in overcoming the von Neumann bottleneck and significantly enhancing computing efficiency. It offers a wide range of possibilities for artificial visual system applications. Photonic synapses, as essential components, can contribute to improved efficiency in visual information processing by leveraging their low latency, high propagation speed, and broad bandwidth capabilities. Herein, a photonic transistor capable of detecting visible light and exhibiting synaptic characteristics under various visible stimuli is presented. This is achieved by integrating a photo‐sensitive polymer as a floating gate charge trapping medium. The synaptic device successfully emulates fundamental synaptic behaviors such as excitatory postsynaptic current (EPSC), pair‐pulse facilitation, the transition of short‐term memory to long‐term memory, and learning and forgetting processes. Furthermore, leveraging the ESPC responses, the informative synaptic outputs modulated by light signals enable a non‐contact writing method, paving the way for advancements in optical wireless communication. It is believed that this work serves as a promising building block to complete the bio‐inspired photonic computing paradigm.

Harnessing optical vortices to control current flow via quantized torque in coherently prepared multilevel atoms

This study delves into the interaction between coherently prepared trapped atoms and optical vortices, focusing on the intriguing phenomenon of light-induced torque enhancement and the resultant persistent current flow. Beginning with a three-level atom ensemble in the Λ configuration, we initiate a coherent superposition of lower levels to establish a coherent population trapping medium. The atoms interact with a pair of optical vortices, producing a quantized torque on each trapped atom that is directly proportional to the topological charge of the inhomogeneous coupling beams. This torque imparts a rotation to the entire ensemble, thereby generating a striking ring-shaped atomic current flow. With careful manipulation of the initial internal state of the atoms and the strength of the vortex pair, we can control the magnitude of the torque. Extending the model to include more complex level schemes with additional laser beams offers even greater potential for enhancing light-induced torque and refining our control over the current flow.

External DNA contamination and efficiency of bleach decontamination for arthropod diet analysis

AbstractDNA metabarcoding is increasingly used to analyze the diet of arthropods, including spiders. However, high sensitivity to DNA contamination makes it difficult to apply to organisms obtained from mass‐sampling methods such as pitfall traps. An alternative is to hand‐sample spiders, but it is unclear how effectively this prevents external contamination, especially with new knowledge showing the wide spread of eDNA in the environment. Protocols using bleach to remove external DNA have been tested on several invertebrates, though testing with both mass‐sampling methods and spiders is lacking. Here, we used wolf spiders (Lycosidae) to assess the risk of external DNA contamination from pitfall trapping and hand sampling, and the efficacy of bleach decontamination. We first conducted a contamination experiment where we placed spiders in pitfall traps containing trapping medium and a nonprey insect species to simulate external DNA contamination. We also compared sampling methods by collecting spiders using pitfall traps and hand sampling. Spiders from the contamination experiment and sampling method comparison were either bleached or untreated, then metabarcoded using multiple primer pairs. The contamination experiment resulted in the contamination of almost all spiders from pitfall traps, which was successfully eliminated with bleaching. Interestingly, there was no difference in the number of amplicon sequence variants (ASVs) detected per spider between pitfall trapping and hand sampling but bleaching resulted in significantly fewer ASV detections for both methods. Additionally, bleaching, but not sampling method, affected the taxonomic diet composition for both hand‐sampled and pitfall‐trapped spiders, indicating similar levels of external contamination. Our results are the first to confirm that DNA metabarcoding can be used together with bleaching for spiders sampled from pitfall traps, and that hand sampling does not necessarily exclude external DNA contamination. Thus, diet studies using metabarcoding should address the risk of external contamination with field‐sampled arthropods, regardless of sampling method.

Sensitivity Enhancement of Surface Plasmon Resonance-based Biosensor using Aluminium-Cobalt-Tungsten Disulfide-Graphene Heterostructure

An attempt has been made to enhance the sensitivity of a high-sensitive surface plasmon resonance (SPR) biosensor with an aluminium-cobalt bimetallic layer covered by a tungsten disulfide-graphene heterostructure. A thin layer of cobalt coated on an aluminium layer contributed substantially to increase the sensor performance. The use of Al and Co metals instead of noble metals like Ag and Au reduced the cost of the sensor. Further, tungsten disulfide (WS2) layers were employed to improve sensitivity and protect the bimetal Al-Co from becoming oxidized, whereas graphene served as the biomolecule trapping medium. The number of WS2 and graphene layers have optimized for better sensitivity. The proposed biosensor Al-Co-WS2-graphene structure displayed an excellent sensitivity of 300°/RIU, convenient for sensing biomolecules.

A comparative study of dielectric barrier discharge plasma device and plasma jet to generate plasma activated water and post-discharge trapping of reactive species

This work shows a comparative study of a change in properties of plasma-activated water (PAW) when prepared by using two different dielectric barrier discharge (DBD) configurations named a pencil plasma jet (PPJ) and a plasma device (PD). The air plasma produced from the DBD-PPJ and DBD-PD is characterized by voltage-current characteristics, and plasma species/radicals are identified using optical emission spectroscopy. Moreover, the present work emphasizes the trapping of reactive species (O3, NOx, etc.) carried by post-discharge residual gases during PAW production. The trapping of these gases' reactive species is carried out in water, which provides a useful by-product named plasma processed water (PPW). The results revealed a higher concentration of reactive oxygen species (dissolved O3 and H2O2) and a lower concentration of reactive nitrogen species (NO3− and NO2− ions) in PAW prepared by the DBD-PPJ configuration compared to the DBD-PD configuration. The trapping of reactive species (O3 and NOx) present in post-discharge residual gases is confirmed by determining the change in physicochemical properties and reactive oxygen–nitrogen species (RONS) concentration in virgin water used as a trapping medium. The high concentration of RONS in PPW showed a high concentration of reactive species in post-discharge residual gases and vice versa. Therefore, the reduction in reactive species downstream of post-discharge residual gases is shown by a substantial decrease in the concentration of RONS and physicochemical properties of PPW. Thus, PAW and PPW (by-product) prepared in this work could be used for multiple applications such as microbial inactivation, food preservation, and agriculture.

Intake of New Zealand Blackcurrant Powder Affects Skin-Borne Volatile Organic Compounds in Middle-Aged and Older Adults

Skin volatile organic compounds (VOCs) can cause body odor or reveal human disease and may result from lipid peroxidation or activity by skin bacteria. We examined the effect of intake of New Zealand blackcurrant (NZBC) powder for 77 skin VOCs in middle-aged and older adults in a crossover design. Fourteen adults (nine males, age: 55 ± 5 yrs) consumed NZBC powder for 7 days (6 g·day−1 with 138.6 mg anthocyanins). Two hours after the last intake, a passive flux sampler with trapping media was applied in the base of the neck for 1 hour. Gas chromatography-mass spectrometry was used for media analysis. Habitual anthocyanin intake was quantified using a food frequency questionnaire. Compared to control (i.e., no intake of NZBC powder), emission of six skin VOCs (i.e., 2-nonenal, acetic acid, 2-hexanone, 6-methyl-5-hepten-2-one, benzaldehyde, allyl methyl sulfide) were lower by more than 25%. Increases were observed for γ-octanolactone (+184%) and γ-decanolactone (+89%). A trend for a decrease for isovaleraldehyde, hexanal, and 2-pentanone, and an increase for heptanoic acid and γ-nonanolactone was observed. There was a significant correlation with daily habitual dietary anthocyanin intake for control values of hexanal and percentage change of γ-octanolactone. NZBC powder can change emanation of some VOCs in human skin. Analysis of skin VOCs following specific polyphenol intake may address the impact of dietary components to affect internal metabolic processes, body odor, and health.

Determination of certain VOCs in paints and architectural coatings by dynamic headspace gas chromatography-mass spectrometry.

A quantitative method for the determination of the following VOCs: acetone, dichloromethane, dimethyl carbonate, methyl acetate, tertiary butyl acetate, chlorobenzotrifluoride (4-CBTF) and propylene carbonate in paints was developed in support of Environment and Climate Change Canada's Automotive Refinishing Product and Architectural Coatings VOC Concentration Limits regulations. These compounds are excluded from the VOC definition by Canadian Environmental Protection Act (CEPA) regulations, and their content do not contribute to the overall VOC content in products for regulatory purposes. The method is based on Dynamic Headspace GC-MS. It was determined that activated carbon is the best trapping medium for these compounds. The technique has been compared to a currently used direct injection technique, with comparable results. Contrary to the direct injection method which requires complex sample handling prior to injection in the gas chromatograph, the dynamic headspace method practically eliminates the need for sample handling allowing for much shorter sample turnover and reducing the possibility of sampling handling errors.

Integration of fluorographene trapping medium in MoS2-based nonvolatile memory device

Graphene and 2D analogs such as transition metal dichalcogenides (TMDCs) have been widely investigated for their tuneable electronic properties. There is a large spectrum of applications of such 2D analogs; for example, non-volatile memory, which is a key building block for future low-power consumer electronics. In this work, we have investigated a vertical heterostructure composed of a chemical vapour-deposited molybdenum disulphide transistor channel coupled with silicon tunnel oxide (SiO2) and hafnium oxide as a blocking barrier, with fluorographene (FGr) being used as the charge trapping medium. Owing to the larger trap density of FGr, the memory window is three times larger, and the data retention measurements at room temperature yield a 50% charge loss extrapolated to 10 years. The low barrier at the FGr/SiO2 interface induces a steeper charge loss for holes. Nevertheless, the stack can sustain at least to 550 cycles without showing any sign of degradation. Although bandgap engineering is required to improve the data retention, particularly for the holes, the combination studied here is an encouraging route for 2D-based non-volatile memories.

Non-Volatile Organic Transistor Memory Based on Black Phosphorus Quantum Dots as Charge Trapping Layer

High performance organic nano-floating gate transistor memory (NFGTM) has important prerequisites of low processing temperature, solution–processable layers and charge trapping medium with high storage capacity. We demonstrate organic NFGTM using black phosphorus quantum dots (BPQDs) as a charge trapping medium by simple spin-coating and low processing temperature ( 104 over 10,000 sec by introducing PMMA as the tunneling layer.

Large area and low-cost nanoholes-based plasmonic back reflector fabricated by a simple nanofabrication technique for photovoltaics applications

Plasmonic back reflectors (PBRs) are employed in thin film and ultra-thin film solar cells to increase their optical thickness and energy conversion efficiency. Here, we report a wet-chemical etching based nanofabrication technique to prepare large area and low-cost nanoholes-based plasmonic back reflectors (n-PBRs). The n-PBR is a 150 nm thick Ag thin film embedded with random nanoholes with varying structure and morphology. We successfully incorporated the n-PBR into a standard a-Si:H thin film solar cell built on a randomly textured FTO substrate; the textured FTO serves as both the front contact and light-entry side light trapping medium. Three n-PBRs each with different density of random nanoholes were studied. All the plasmonic a-Si:H solar cells with n-PBRs exhibited an optical absorption enhancement in the spectrally intense 550–800 nm wavelength range with an overall enhancement factor of 1.1 and a maximum enhancement factor of 1.3 in the 720–780 nm wavelength range. The n-PBRs produced a haze of 65% in the 700–800 wavelength range. The hazy back contact effectively scatters the unabsorbed light back into the active medium of the solar cell with increased path length and hence, contributes to the enhanced absorption in the solar cell. The method of nanofabrication reported here to produce plasmonic back reflectors can be easily adopted into commercial fabrication of various types of solar cells including ultrathin inorganic and organic, polymer, perovskite and dye-sensitized solar cells to enhance their energy conversion efficiency without adding any cost/watt to the solar cells.

Selective Enrichment of Phosphorylated Peptides by Monolithic Polymers Surface Imprinted with bis-Imidazolium Moieties by UV-Initiated Cryopolymerization.

Reversible protein phosphorylation on serine, threonine, and tyrosine residues is essential for fast, specific, and accurate signal transduction in cells. Up to now, the identification and quantification of phosphorylated amino acids, peptides, and proteins continue to be one of the significant challenges in contemporary bioanalytical research. In this paper, a series of surface grafted monoliths in the capillary format targeting phosphorylated serine has been prepared by first synthesizing a monolithic core substrate material based on trimethylolpropane trimethacrylate, onto which a thin surface-imprinted layer was established by oriented photografting of a variety of mono- and bis-imidazolium host monomers at subzero temperature, using six different continuous or pulsed UV light sources. The imprinted monolith capillaries were evaluated in a capillary liquid chromatographic system connected to a mass spectrometer in order to test the specific retention of phosphorylated peptides. Site-specific recognition selectivity and specificity for phosphorylated serine was demonstrated when separating amino acids and peptides, proving that the optimized materials could be used as novel trapping media in affinity-based phosphoproteomic analysis.

Effect of New Zealand Blackcurrant Powder on Skin Emission of Volatile Organic Compounds in Middle Aged and Older Adults (P06-092-19)

ObjectivesVolatile organic compounds (i.e., VOCs) emanating from the human skin are used to detect disease biomarkers and causes of body odour. Seven-day intake of New Zealand blackcurrant (NZBC) powder reduced skin emission of 2-nonenal, a lipid peroxidation compound responsible for body odour in older adults. Anthocyanin-induced bioavailability of plasma metabolites by intake of NZBC may affect the production of VOCs. In the present study, we examined the effect of 7-day NZBC powder intake on the skin emission of 76 VOCs. MethodsFourteen Caucasian adults (9 males, age: 55 ± 5 yr) volunteered. Participants consumed NZBC powder for 7 days (Sujon Berries, NZ, 6 g·day-1 with 138.6 mg anthocyanin, 49 mg Vit C, 5.2 g of carbohydrates and total phenolic content of 271.6 mg per serving). Two hours after the last intake, a passive flux sampler with trapping media (MonoTrap®, DCC18, GL Science, Japan) was applied to the skin in the base of the neck for one hour, and gas chromatography-mass spectrometry was used for media analysis (Kimura et al., 2016). Participants did not use hot water or soap for 48 hrs on the skin sampling location. Dietary anthocyanin intake was quantified using a food frequency questionnaire. Data were analysed with paired, two-tailed t-test and effect size (Cohen’s d) was calculated. ResultsDecreases in skin emission were observed for acetic acid (–57%, P = 0.006, d = –1.26), 2-hexanone (–47%, P = 0.031, d = –0.86), 6-methyl-5-hepten-2-one (–93%, P = 0.005, d = –1.23), benzaldehyde (–86%, P = 0.004, d = –0.96), allyl methyl sulfide (–35%, P = 0.015, d = –0.98) and increases for γ-octanolactone (+65%, P = 0.023, d = 0.98) and γ-decanolactone (+47%, P = 0.015, d = 1.11). For these VOCs, there was no significant correlation between daily anthocyanin intake and baseline values. A trend for a decrease was observed for isovaleraldehyde, hexanal and 2-pentanone and an increase for heptanoic acid and γ-nonanolactone, all 0.05 < P < 0.1. ConclusionsAnthocyanin-containing NZBC powder can change the emanation of some volatile organic compounds in human skin. Analysis of volatile organic compounds in human skin following nutritional interventions can address the impact of dietary components to affect human body odour and health. Funding SourcesSujon Berries (Nelson, NZ) provided supplements. Support for conference attendance was obtained from Blackcurrant New Zealand Inc. (NZ).

Mimicking Neuroplasticity in a Hybrid Biopolymer Transistor by Dual Modes Modulation

AbstractNeuromorphic computing systems that are capable of parallel information storage and processing with high area and energy efficiencies, offer important opportunities for future storage systems and in‐memory computing. Here, it is shown that a carbon dots/silk protein (CDs/silk) blend can be used as a light‐tunable charge trapping medium to fabricate an electro‐photoactive transistor synapse. The synaptic device can be optically operated in volatile or nonvolatile modes, ensuring concomitant short‐term and long‐term neuroplasticity. The synaptic‐like behaviors are attributed to the photogating effect induced by trapped photogenerated electrons in the hybrid CDs/silk film which is confirmed with atomic force microscopy based electrical techniques. In addition, system‐level pattern recognition capability of the synaptic device is evaluated by a single‐layer perceptron model. The remote optical operation of neuromorphic architecture provides promising building blocks to complete bioinspired photonic computing paradigms.

Derivation of Feynman–Kac and Bloch–Torrey Equations in a Trapping Medium

We derive rigorously the fractional counterpart of the Feynman–Kac equation for a transport problem with trapping events characterized by fat-tailed time distributions. Our starting point is a random walk model with an inherent time subordination process due to the difference between clock times and operational times. We pass to the hydrodynamic limit using weak convergence arguments. Due to the lack of regularity of physical data, we use the framework of measure theory. We finally derive a Bloch–Torrey type equation for nuclear magnetic resonance data in this subdiffusive context.

Tunable size selectivity and nanoparticle immobilization on a photonic crystal optical trap.

We harness residual thermal effects in a low-absorptivity system to manipulate parallel optical trapping of particles on the nanoscale. A photonic crystal is used to generate a 2D array of optical traps. We show that the size selectivity of the trap can be tuned by adding a non-ionic surfactant to the solution, altering the thermophoretic effect that delivers nanoparticles to trapping sites. We further show that particles can be permanently immobilized on the photonic crystal via photopolymerization of the trapping medium.

Solution-processed nonvolatile Hf-doped ZnO thin-film transistor memory with SiO2 micro- and nanoparticles as a trapping medium

We report a nonvolatile-memory device based on solution-processed Hf-doped ZnO (ZnO:Hf) thin-film transistors (TFTs) fabricated by inserting SiO2 microparticles (MPs) and nanoparticles (NPs) as a charge trapping medium. The transfer characteristics of ZnO:Hf TFT devices inserted with SiO2 particles showed a large clockwise hysteresis behavior owing to charge carrier trapping capability. Both memory devices exhibited a highly programmable memory window during the program/erase operation, which can be attributed to charge carrier trapping and de-trapping in SiO2 particles. Particularly, the memory device with SiO2 NPs revealed a larger memory window over 25 V than that with MPs. Furthermore, the fabricated memory devices showed remarkably long-term retention characteristics and the ON/OFF current ratio greater than 104.

Rapid synthesis and decoration of reduced graphene oxide with gold nanoparticles by thermostable peptides for memory device and photothermal applications

This article presents novel, rapid, and environmentally benign synthesis method for one-step reduction and decoration of graphene oxide with gold nanoparticles (NAuNPs) by using thermostable antimicrobial nisin peptides to form a gold-nanoparticles-reduced graphene oxide (NAu-rGO) nanocomposite. The formed composite material was characterized by UV/Vis spectroscopy, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, and high-resolution transmission electron microscopy (HR-TEM). HR-TEM analysis revealed the formation of spherical AuNPs of 5–30 nm in size on reduced graphene oxide (rGO) nanosheets. A non-volatile-memory device was prepared based on a solution-processed ZnO thin-film transistor fabricated by inserting the NAu-rGO nanocomposite in the gate dielectric stack as a charge trapping medium. The transfer characteristic of the ZnO thin-film transistor memory device showed large clockwise hysteresis behaviour because of charge carrier trapping in the NAu-rGO nanocomposite. Under positive and negative bias conditions, clear positive and negative threshold voltage shifts occurred, which were attributed to charge carrier trapping and de-trapping in the ZnO/NAu-rGO/SiO2 structure. Also, the photothermal effect of the NAu-rGO nanocomposites on MCF7 breast cancer cells caused inhibition of ~80% cells after irradiation with infrared light (0.5 W cm−2) for 5 min.