Field Screening Research Articles

Genetic resistance derived from Solanum pimpinellifolium AAU2019 is monogenic recessive to tomato leaf curl virus

AbstractTomato leaf curl disease is a severe threat to tomato production. Yield losses are generally high in the absence of effective management strategies. The disease is caused by tomato leaf curl virus (ToLCV) and is transmitted by a whitefly vector that is challenging to control. Resistance to ToLCV is absent from most cultivated tomato gene pools, although the use of resistant cultivars would provide a better control option than minimizing the vector population. Unfortunately, resistance sources based on field screening break down when virus pressure is severe. Our previous screening and virus testing of 40 tomato genotypes led to the identification of a highly resistant genotype, Solanum pimpinellifolium AAU2019, as a new source of resistance. In this study, we investigated the inheritance and genetics of resistance to ToLCV in the cross of Pusa Ruby × S. pimpinellifolium AAU2019 in F2 and BC1Ps populations, revealing a monogenic recessive gene (best‐fit ratios of resistance: susceptible to be 1:3 and 0:1) responsible for ToLCV resistance in S. pimpinellifolium AAU2019. Hence, S. pimpinellifolium AAU2019 could be considered as a potential donor parent in breeding programmes to develop tomato cultivars with resistance to ToLCV.

Emergent magnetic monopole and dipole screening by free electrons in aluminum/artificial spin ice heterostructures

In this work, we present screening of magnetic monopole and dipole by the presence of a 20 nm aluminum cover layer on square artificial spin ice systems. Our measurements were performed by magnetic force microscopy on samples with and without aluminum at remanence, after application of successive external magnetic field steps. Experimental results show that both evolution of magnetization and monopole population under external field are affected by the aluminum presence. Very good agreement between those results and excitation model simulations was found when both emergent magnetic monopole and dipole strengths decrease on the presence of the aluminum cap. We suggest that the observed strength weakening of emergent particles occurs due to its field screening by aluminum-free electrons. The screening on the presented heterostructure could be used for devices design with different magnetic monopole mobility or for selective thermodynamic activation in samples close to superparamagnetic regime.

Developing a high‐throughput method to screen soybean germplasm for hypoxia tolerance in a hydroponic system

AbstractCurrent field screening methods for soybean [Glycine max L. (Merr.)] flood tolerance are time‐ and labor‐intensive. The purpose of this research was to develop a method of screening soybean in a low‐O2 and CO2–rich treatment using hydroponic culture in a greenhouse setting. Growth media, solution, and plant response were evaluated at various days after termination of gas treatment (DAT). Initially, a flood‐susceptible genotype at early vegetative stage was subjected to a hypoxic treatment, displacing O2 by bubbling CO2 into the system for 5 d. The methodology was tested with 33 soybean genotypes, and normalized difference vegetation index (NDVI), soil–plant analysis development (SPAD), and foliar damage score (FDS) were measured. Then, the reaction of 17 genotypes was compared between hydroponic and field conditions. Expanded clay pebbles were identified as the best substrate for the screening method, as germination rate was not different from control. Gas treatment was shown to affect the level of dissolved O2 in solution and to elicit phenotypic responses, of which NDVI was the most effective for differentiating germplasm, with an average of 0.29 and 0.69 for the CO2 treatment and ambient air control, respectively (p < .0001). Also, repeatability of NDVI response across genotypes was 94.5%. Finally, preliminary field validation supported the ability of this new hydroponic methodology to separate susceptible and tolerant genotypes under hypoxia and water‐logged conditions.

Evaluation of portable vibrational spectroscopy for identifying plasticizers in dairy tubing

ABSTRACT Plasticisers are commonly used to increase the flexibility of a wide variety of food contact materials including the plastic tubing, liners, and gaskets used in the dairy industry. In recent years, some classes of plasticisers have come under scrutiny due to the potential for transfer of these compounds into the milk itself, which can then be further processed into foods such as powdered milks and cheeses, infant formula, and baked goods. One such set of plasticisers that is being evaluated for frequency of use, potential routes of exposure, and risk to consumers is ortho-phthalates, hereafter referred to as phthalates. In order to better understand the actual use of phthalate versus non-phthalate plasticised tubing, a robust, rapid, and portable analytical method is necessary for on-site screening. Laboratory Raman and near-infrared spectrometers have been used extensively for polymer and additive evaluation, and advances in portable/hand-held technology could lead to feasible plasticiser evaluation in the field. This research overviews efforts to evaluate six portable spectroscopy devices for their ability to identify phthalate versus non-phthalate plasticised polyvinyl chloride (PVC) dairy tubing, liners, and gaskets. The most successful method, a hand-held Raman spectrometer along with a plasticiser spectral library or a chemometric model, can rapidly and accurately identify phthalate containing PVC and has the potential to be employed as a future field screening technique for regulators and the dairy industry.

Rapid in situ assessment of luminescence-bleaching depths for deriving burial and exposure chronologies of rock surfaces

Recent developments in luminescence dating offer new ways to date exposure and burial durations of rocks. The new rock surface dating methods ideally require high-resolution data, faster sample preparation and measurement times, and field screening methods to select samples with appropriate luminescence characteristics and bleaching histories. Presented here is a demonstration of an EMCCD (electron multiplying charge coupled device) based system capable of imaging high-resolution infrared stimulated luminescence (IRSL) and infrared-photoluminescence (IRPL) from rock samples. The IRPL can be detected at both 880 nm and 955 nm. Using this instrument, the entire luminescence-depth profile can be reconstructed by imaging a single surface cut perpendicular to the exposed rock face. We demonstrate the possibility of reconstructing luminescence-depth profiles suitable for rock surface dating from large (cm-scale) rock samples, without using a regeneration dose for normalisation of the natural luminescence signals. Based on the different bleaching characteristics of the IRSL and IRPL emissions at 880 nm and 955 nm, we show that it is possible to gain reliable estimates of bleaching depths from measurement of as few as two images of the IRPL signal (one for each emission), or from measurement of the IRSL decay curve. We thus by-pass laborious sample preparations and the need for a gamma source to estimate the bleaching depth, thereby extending the 2D luminescence-depth profile imaging technique to other laboratories that lack access to ionising radiation facilities. This study also makes a significant progression towards development of a field instrument for in situ relative exposure dating, and sample screening for rock surface burial dating. • Direct imaging of luminescence-depth profiles in rocks using IRPL or IRSL. • New methods for normalising spatial variations in luminescence without irradiation. • Characterising bleachability of different OSL emissions from the principal trap. • Rock surface dating for rapid field analysis or laboratories lacking irradiation facilities.

Identification of novel resources for panicle blast resistance from wild rice accessions and mutants of cv. Nagina 22 by syringe inoculation under field conditions.

Panicle blast is the most severe type of rice blast disease. Screening of rice genotypes for panicle blast resistance at the field level requires an efficient and robust method of inoculation. Here, we standardized a method that can be utilized for both small- and large-scale screening and assessment of panicle blast infection and disease reaction. The method involves inoculation of Magnaporthe oryzae spore culture in the neck of the rice panicle using a syringe and covering the inoculation site with wet cotton wrapped with aluminum foil to provide the required humidity for spore germination. The method was standardized using panicle blast-resistant cv. Tetep and susceptible cv. HP2216 inoculated with Mo-ni-025 isolate of M. oryzae. The method was evaluated at phenotypic as well as molecular level by expression analysis of disease responsive pathogenesis-related (PR) genes. We found this method simple, robust, reliable, and highly efficient for screening of large germplasm sets of rice for panicle blast. This was validated by screening the wild rice germplasm for panicle blast response in the field using three M. oryzae strains and subsequently with the most virulent strain in 45 EMS-induced mutants of Nagina 22 shortlisted based on field screening in a blast hotspot region. We identified five novel blast disease-resistant wild rice genotypes and 15 Nagina 22 mutants that can be used in breeding programmes.

Response to selection to different breeding methods for soybean flood tolerance

AbstractSelection for flood‐tolerance in soybean [Glycine max (L.) Merr.] is mainly phenotypic. With the development of new molecular breeding tools, our research objective was to assess the effect of different selection methods at the F4:5 and F4:6 stages on the response to flood tolerance and yield at F4:6 stage. Four breeding populations were subjected to six selection treatments: (a) flood tolerance screening using hill‐plots (VIShill); (b) flood tolerance screening using long rows (VISrow); (c) genomic selection using population‐specific training (GShill); (d) genomic selection using broad‐based training population (GSrow); (e) marker‐assisted selection (MAS); (f) advanced based on agronomic adaptation under nonflooded conditions (random selection, RND). The top 15% lines within were tagged for selection, except for MAS that was adjusted based on recovery of desired haplotype. The complete base populations (BP) were advanced into flood and yield trials to determine probability of discard (POD), tolerance index (TOL), and seed yield. Analysis of variance was conducted across populations, and means were separated via Dunnett to the BP. Results indicated significantly different responses for flood tolerance (POD and TOL) across selection methods (p < .0001), with VISrow and GSrow consistently having better tolerance selections than the BP (p < .0001). In addition, lines selected by RND had lower tolerance than BP (p = .0053 and .0618 for POD and TOL, respectively). Moreover, no significant differences were observed among selection treatments (p = .6797) for yield. In conclusion, when breeding for flood tolerance, selections under standard agronomic practices are inadequate, and genomic selection (GSrow) or field screening using long rows (VISrow) are favored selection methods.

Mechanism for switchability in electron-doped ferroelectric interfaces

With the recent experimental verification that ferroelectric lattice distortions survive in the metallic phase of some materials, there is a desire to create devices that are both switchable and take advantage of the novel functionalities afforded by polar interfaces. In this work, we explore a simple model for such an interface and demonstrate a mechanism by which a metallic ferroelectric substrate may be switched by a bias voltage. This finding is in contrast to the reasonable expectation that hysteresis is prevented by screening of external fields in ferroelectric metals. Instead, the electron gas binds to polarization gradients to form a compensated state. Uncompensated electrons, which may screen external fields, are generated either when the electron density exceeds the ferroelectric polarization or when the bias voltage exceeds a "spillover" threshold. We propose that switchable thin films may be optimized by choosing an electron density that is slightly less than the lattice polarization. In addition to the high-polarization states, we find that thin metallic films also have a low-polarization state with average polarization near zero. Unlike in insulating films, where the polarization is small everywhere in this state, the low-polarization state in the metallic films consists of two head-to-head domains of opposite polarization. This domain formation is enabled by the screening of depolarizing fields by the electron gas.

Quantification of Efficiency Losses Due to Mobile Ions in Perovskite Solar Cells via Fast Hysteresis Measurements

Perovskite semiconductors differ from most inorganic and organic semiconductors due to the presence of mobile ions in the material. Although the phenomenon is intensively investigated, important questions such as the exact impact of the mobile ions on the steady‐state power conversion efficiency (PCE) and stability remain. Herein, a simple method is proposed to estimate the efficiency loss due to mobile ions via “fast‐hysteresis” measurements by preventing the perturbation of mobile ions out of their equilibrium position at fast scan speeds (1000 V s−1). The “ion‐free” PCE is between 1% and 3% higher than the steady‐state PCE, demonstrating the importance of ion‐induced losses, even in cells with low levels of hysteresis at typical scan speeds (100 mV s−1). The hysteresis over many orders of magnitude in scan speed provides important information on the effective ion diffusion constant from the peak hysteresis position. The fast‐hysteresis measurements are corroborated by transient charge extraction and capacitance measurements and numerical simulations, which confirm the experimental findings and provide important insights into the charge carrier dynamics. The proposed method to quantify PCE losses due to field screening induced by mobile ions clarifies several important experimental observations and opens up a large range of future experiments.

High‐Performance Phototransistors by Alumina Encapsulation of a 2D Semiconductor with Self‐Aligned Contacts

Abstract2D semiconductors are promising candidates for next generation electronics and optoelectronics. However, their exposure to air and/or resists during device fabrication can cause considerable degradation of material quality, hindering their study and exploitation. Here, field effect transistors (FETs) are designed and fabricated by encapsulation of the 2D semiconductor indium selenide (InSe) with alumina (Al2O3) and by self‐aligned electrical contacts. The Al2O3‐film is grown directly on InSe immediately after its exfoliation to provide a protecting capping layer during and after device fabrication. The InSe‐FETs exhibit a high electron mobility of up to ≈103 cm2 V−1 s−1 at room temperature for a 4‐nm‐thick InSe layer, a low contact resistance (down to 0.18 kΩ) and a high, fast, and broad‐band photoresponsivity. The photoresponsivity depends on the InSe‐layer thickness and photon wavelength, reaching a value of up to 108 A W−1 in the visible spectral range, at least one order of magnitude larger than previously reported for similar photodetectors. The proposed fabrication is scalable and suitable for high‐precision pattern definition. It could be extended to other 2D materials and multilayer structures where alumina could also provide effective screening of the electric field induced by polar molecules and/or charged impurities present near the surface of the 2D layer.

Review of Machine Learning Applications Using Retinal Fundus Images.

Automating screening and diagnosis in the medical field saves time and reduces the chances of misdiagnosis while saving on labor and cost for physicians. With the feasibility and development of deep learning methods, machines are now able to interpret complex features in medical data, which leads to rapid advancements in automation. Such efforts have been made in ophthalmology to analyze retinal images and build frameworks based on analysis for the identification of retinopathy and the assessment of its severity. This paper reviews recent state-of-the-art works utilizing the color fundus image taken from one of the imaging modalities used in ophthalmology. Specifically, the deep learning methods of automated screening and diagnosis for diabetic retinopathy (DR), age-related macular degeneration (AMD), and glaucoma are investigated. In addition, the machine learning techniques applied to the retinal vasculature extraction from the fundus image are covered. The challenges in developing these systems are also discussed.

CORRELATION AND PATH ANALYSIS OF YIELD AND YIELD ATTRIBUTING CHARACTERS IN RICE UNDER REPRODUCTIVE DROUGHT STRESS CONDITION

A field screening of eight genotypes at farmer’s field of Sundarbazar, Lamjung in randomized complete block design with three replications was conducted to study the character association between yield and yield attributing traits of rice and their direct and indirect effect on grain yield under reproductive drought stress condition from June to November 2018. The analysis of variance revealed significant differences for all traits except plant height, which indicates existence of genetic variability, potential for selection and further improvement among all genotypes under study. Correlation and path analysis revealed that flag leaf area, chlorophyll content, days to heading and thousand grain weight showed significant and positive association as well as positive direct effect on yield of rice which means direct selection of these traits would be beneficial for the improvement of grain yield facilitating the selection and progress on breeding program.

MgB2 Superconducting Joint Architecture with the Functionality to Screen External Magnetic Fields for MRI Magnet Applications.

A superconducting joint architecture to join unreacted carbon-doped multifilament magnesium diboride (MgB2) wires with the functionality to screen external magnetic fields for magnetic resonance imaging (MRI) magnet applications is proposed. The intrinsic diamagnetic property of a superconducting MgB2 bulk was exploited to produce a magnetic field screening effect around the current transfer path within the joint. Unprecedentedly, the joint fabricated using this novel architecture was able to screen magnetic fields up to 1.5 T at 20 K and up to 2 T at 15 K and thereby almost nullified the effect of the applied magnetic field by maintaining a constant critical current (Ic). The joint showed an Ic of 30.8 A in 1.5 T at 20 K and an ultralow resistance of about 3.32 × 10-14 Ω at 20 K in a self-field. The magnetic field screening effect shown by the MgB2 joint is expected to be extremely valuable for MRI magnet applications, where the Ic of the joints is lower than the Ic of the connected MgB2 wires in a given magnetic field and temperature.

Natural infection of cape gooseberry (Physalis peruviana) by the potyvirus Tamarillo leaf malformation virus (TaLMV).

Tamarillo leaf malformation virus (TaLMV) is apotyvirus first discovered in cape gooseberry fields in Eastern, and South-western Antioquia. This virus is responsible for avery damaging disease that has resulted in significant reductions in yields and cultivated area for this crop in Colombia. Tamarillo is frequently co-cultivated with other solanaceous plants but no evidence for cross-pathogenicity of TaLMV has been found until now. In this work, we report anatural infection of cape gooseberry (Physalis peruviana L.) by TaLMV. Infection by TaLMV was detected by RNAseq screening of cape gooseberry fields and confirmed by RT-qPCR and Sanger sequencing. The sequenced genome is 99.3% identical to previously sequenced TaLMV isolates, and evidence suggests that it can accumulate at high loads in this new reported host. RT-qPCR analysis indicates that TaLMV is already widely distributed, can naturally infect other solanaceous hosts and may become an emerging threat to the cape gooseberry agroindustry, the second most important exotic fruit export in Colombia. Keywords: high-throughput sequencing; plant virology; Potyviridae; RT-qPCR; Solanaceae.

Evaluation of the Role of BIOCHIP Mosaic Based Indirect Immunofluorescence and ELISA BP 180 and BP 230 Autoantibodies in the Diagnosis of Bullous Pemphigoid Patients.

Bullous pemphigoid (BP) is characterized by tissue-bound and circulating Immunoglobulin G (IgG) autoantibodies against BP 180 and BP 230. Diagnosis of BP is a multi-step procedure. Enzyme-linked immunosorbent assay (ELISA) is a quantitative analysis of target antigens, whereas BIOCHIP mosaic-based indirect immunofluorescence (IIF) has a combination of screening and target antigen-specific substrates in a single miniature incubation field. This study is done to compare BIOCHIP mosaic based IIF and ELISA for the diagnosis of BP. A total of 42 biopsy and/or direct immunofluorescence (DIF) proven BP patients were included in the study. Serum was subjected to BIOCHIP mosaic-based IIF and ELISA. The results were then compared. Using ELISA, the sensitivity of BP 180 and BP 230 was 92.3% and 54.5%, respectively. The sensitivity of BP 180 and BP 230 by BIOCHIP was 77.4% and 60%, respectively. The association between ELISA and BIOCHIP was analyzed using the Chi-square test and was found to be statistically significant with a P value ≤ 0.05. Our study concluded that both BIOCHIP and ELISA showed comparable sensitivity in diagnosing BP. Both are non-invasive, less time-consuming, and provide fast results. However, BIOCHIP can delineate bullous pemphigoid from other sub-epidermal bullous diseases.

GaN-based bipolar cascade lasers with 25 nm wide quantum wells

We analyze internal device physics, performance limitations, and optimization options for a unique laser design with multiple active regions separated by tunnel junctions, featuring surprisingly wide quantum wells. Contrary to common assumptions, these quantum wells are revealed to allow for perfect screening of the strong built-in polarization field, while optical gain is provided by higher quantum levels. However, internal absorption, low p-cladding conductivity, and self-heating are shown to strongly limit the laser performance.

Material Gain in Polar GaInN and AlGaN Quantum Wells: How to Overcome the ‘Dead’ Width for Light Emitters in These QW Systems?

<bold xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Polar GaInN and AlGaN quantum wells (QWs) are widely used in light emitting diodes and laser diodes (LDs). However, the widths of such QWs are usually limited to a few nanometers in order to ensure a sufficiently large overlap between the wave functions of the ground electron and the ground hole state. By increasing the QW width we enter the area of ‘dead’ width where, the overlap of the electron and hole wave functions decreases almost to zero and the luminescence efficiency drastically deteriorates. Therefore, it is assumed that wide QWs are not suitable for light emitters and very wide (8-15 nm) QWs are not considered as a promising gain medium for LDs. Hence such QWs are very rarely studied both experimentally and theoretically. In this work the material gain is calculated for Ga_0.8In_0.2N/GaN and Al_0.8Ga_0.2N/AlN QWs with a width varying in the range of 2-15 nm. We observed that the material gain at fixed carrier concentration for these QWs drops to zero with the increase in the QW width and reaches negative values in the width range of ∼4-8 nm even for high carrier concentrations, but after exceeding a certain width to ∼8-12 nm it begins to increase rapidly and reaches the values greater than those observed for narrow QWs. This phenomenon is related to the screening of the built-in electric field by carriers, which is easier for wide QWs, and the reduction of the distance between the energy levels for electrons and holes. For the latter reason, optical transitions between higher energy states make a very significant contribution to the positive material gain</b> .

Twist in the Tale: Exploring the Dielectric Screening Effect in Twisted Bilayer Graphene

Although the screening of an external electric field, strongly influences the electronic states of two-dimensional material stack, it is not well understood. Magnetotransport measurements of twisted double bilayer graphene uncovered the screening of atomic layers.

Field screening of certain chickpea genotypes against gram pod borer, Helicoverpa armigera (Hubner)

Field screening of certain chickpea genotypes against gram pod borer, Helicoverpa armigera (Hubner)

FIELD SCREENING OF SEVEN GENOTYPES OF MAIZE AGAINST FALL ARMYWORM (Spodoptera Frugiperda) AT GOKULESHWOR, BAITADI

The main aim of this study was to know the genotype of maize that would be least affected by the fall armyworm infestation. The Field screening of seven genotypes of maize, namely Arun-2, Arun-4, Manakamana, Posilo makai, Local seto makai, Rampur composite, and Deuti against Fall armyworm (Spodoptera frugiperda) were carried out at the research farm of Entomology section, Gokuleshwor Agriculture and Animal Science College, Baitadi with RCBD design. Each genotype was assigned as a treatment and each were replicated three times. Density of the pest was recorded on the respective days. None of the seven genotypes were found to be completely resistant to Fall armyworm, however their population density varied according to genotype. During field observation, the population of Fall armyworm larvae was found highest at 60 DAS on genotype Arun-2 and Deuti, 75 DAS on genotype Arun-2, Arun-4, and Rampur composite and the lowest population was observed at 30 DAS on genotype Local seto makai, 45 DAS on genotype Deuti. Similarly, maximum foliar damage intensity was observed at 60 DAS on genotype Manakamana and Local seto makai, 75 DAS on genotype Manakamana and Local seto makai, and minimum intensity of foliar damage was observed at 30 DAS on Arun-4, 45 DAS on genotype Arun-2. Highest yield was obtained from genotype Rampur composite while the lowest yield was obtained from Deuti.