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Journal articles on the topic 'SPAD'

Author: Grafiati

Published: 4 June 2021

Last updated: 26 July 2025

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1

Gaspar, Andrew H., and Hung Ton-That. "Assembly of Distinct Pilus Structures on the Surface of Corynebacterium diphtheriae." Journal of Bacteriology 188, no. 4 (2006): 1526–33. http://dx.doi.org/10.1128/jb.188.4.1526-1533.2006.

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ABSTRACT Different surface organelles contribute to specific interactions of a pathogen with host tissues or infectious partners. Multiple pilus gene clusters potentially encoding different surface structures have been identified in several gram-positive bacterial genomes sequenced to date, including actinomycetales, clostridia, corynebacteria, and streptococci. Corynebacterium diphtheriae has been shown to assemble a pilus structure, with sortase SrtA essential for the assembly of a major subunit SpaA and two minor proteins, SpaB and SpaC. We report here the characterization of a second pilus

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Sewore, Birhanu Mecha, Ayodeji Abe, and Mandefro Nigussie. "Evaluation of bread wheat (Triticum aestivum L.) genotypes for drought tolerance using morpho-physiological traits under drought-stressed and well-watered conditions." PLOS ONE 18, no. 5 (2023): e0283347. http://dx.doi.org/10.1371/journal.pone.0283347.

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Increasing frequency of drought spells occasioned by changing climatic conditions, coupled with rise in demand for bread wheat, calls for the development of high yielding drought resilient genotypes to enhance bread wheat production in areas with moisture deficit. This study was designed to identify and select drought-tolerant bread wheat genotypes using morpho-physiological traits. One hundred and ninety-six bread wheat genotypes were evaluated in greenhouse and field experiments, under well-watered (80% of field capacity) and drought-stressed (35% of field capacity) conditions, for two years

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von Ossowski, Ingemar, Justus Reunanen, Reetta Satokari, et al. "Mucosal Adhesion Properties of the Probiotic Lactobacillus rhamnosus GG SpaCBA and SpaFED Pilin Subunits." Applied and Environmental Microbiology 76, no. 7 (2010): 2049–57. http://dx.doi.org/10.1128/aem.01958-09.

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ABSTRACT Lactobacillus rhamnosus GG is a well-established Gram-positive probiotic strain, whose health-benefiting properties are dependent in part on prolonged residence in the gastrointestinal tract and are likely dictated by adherence to the intestinal mucosa. Previously, we identified two pilus gene clusters (spaCBA and spaFED) in the genome of this probiotic bacterium, each of which contained the predicted genes for three pilin subunits and a single sortase. We also confirmed the presence of SpaCBA pili on the cell surface and attributed an intestinal mucus-binding capacity to one of the p

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Qian, Xuanyu, Wei Jiang, Ahmed Elsharabasy, and M. Jamal Deen. "Modeling for Single-Photon Avalanche Diodes: State-of-the-Art and Research Challenges." Sensors 23, no. 7 (2023): 3412. http://dx.doi.org/10.3390/s23073412.

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With the growing importance of single-photon-counting (SPC) techniques, researchers are now designing high-performance systems based on single-photon avalanche diodes (SPADs). SPADs with high performances and low cost allow the popularity of SPC-based systems for medical and industrial applications. However, few efforts were put into the design optimization of SPADs due to limited calibrated models of the SPAD itself and its related circuits. This paper provides a perspective on improving SPAD-based system design by reviewing the development of SPAD models. First, important SPAD principles suc

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GÖREN, Hatice Kübra. "Determining Optimal Measurement Time Points for SPAD and Canopy Temperature in Drought Tolerant Cotton (Gossypium hirsutum L.) Breeding." ISPEC Journal of Agricultural Sciences 8, no. 2 (2024): 449–60. https://doi.org/10.5281/zenodo.11280512.

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This study investigates optimal physiological parameter measurement times in <em>Gossypium hirsutum</em> L. to assess the effects of drought stress. Observations of SPAD (Leaf Chlorophyll Content) and canopy temperature depression (CMD) were made at different growth stages, including Early Growth, Flowering, Bolling, and Boll Opening stages. These measurements were linked to yield and fiber quality parameters across the cotton grown stages.Data was analyzed using Principal Component Analysis (PCA) to uncover complex trait variations and genetic diversity under water-limited conditions. Specifi

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Yang, Jian, Yang Wang, Xiang-Liang Jin, Yan Peng, and Jun Luo. "Design and Fabrication of Near Ultraviolet Enhanced Composite Single Photon Avalanche Diode for Fluorescence Lifetime Imaging." Journal of Nanoelectronics and Optoelectronics 17, no. 2 (2022): 267–74. http://dx.doi.org/10.1166/jno.2022.3193.

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The near ultraviolet photon detection probability (PDP) of single photon avalanche diodes (SPADs) is very important for the fluorescence lifetime imaging. However, the PDP of traditional SPAD (T-SPAD) devices in the near-ultraviolet is not ideal, which is difficult to meet the requirements of fluorescence lifetime imaging. In response to the above problems, this paper realizes a near ultraviolet enhanced composite SPAD (NUEC-SPAD) based on photogate. The device is based on a photogate and a PN junction formed by P+/N-Well to detect photons. Therefore, the PDP of the device in the near ultravio

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Deng, Shijie, Alan P. Morrison, Yong Guo, et al. "Design of a Real-Time Breakdown Voltage and On-Chip Temperature Monitoring System for Single Photon Avalanche Diodes." Electronics 10, no. 1 (2020): 25. http://dx.doi.org/10.3390/electronics10010025.

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The design and implementation of a real-time breakdown voltage and on-chip temperature monitoring system for single photon avalanche diodes (SPADs) is described in this work. In the system, an on-chip shaded (active area of the detector covered by a metal layer) SPAD is used to provide a dark count rate for the breakdown voltage and temperature calculation. A bias circuit was designed to provide a bias voltage scanning for the shaded SPAD. A microcontroller records the pulses from the anode of the shaded SPAD and calculates its real-time dark count rate. An algorithm was developed for the micr

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Inoue, Akito, Toru Okino, Shinzo Koyama, and Yutaka Hirose. "Modeling and Analysis of Capacitive Relaxation Quenching in a Single Photon Avalanche Diode (SPAD) Applied to a CMOS Image Sensor." Sensors 20, no. 10 (2020): 3007. http://dx.doi.org/10.3390/s20103007.

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We present an analysis of carrier dynamics of the single-photon detection process, i.e., from Geiger mode pulse generation to its quenching, in a single-photon avalanche diode (SPAD). The device is modeled by a parallel circuit of a SPAD and a capacitance representing both space charge accumulation inside the SPAD and parasitic components. The carrier dynamics inside the SPAD is described by time-dependent bipolar-coupled continuity equations (BCE). Numerical solutions of BCE show that the entire process completes within a few hundreds of picoseconds. More importantly, we find that the total a

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Ma, Sizhuo, Varun Sundar, Paul Mos, Claudio Bruschini, Edoardo Charbon, and Mohit Gupta. "Seeing Photons in Color." ACM Transactions on Graphics 42, no. 4 (2023): 1–16. http://dx.doi.org/10.1145/3592438.

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Megapixel single-photon avalanche diode (SPAD) arrays have been developed recently, opening up the possibility of deploying SPADs as generalpurpose passive cameras for photography and computer vision. However, most previous work on SPADs has been limited to monochrome imaging. We propose a computational photography technique that reconstructs high-quality color images from mosaicked binary frames captured by a SPAD array, even for high-dyanamic-range (HDR) scenes with complex and rapid motion. Inspired by conventional burst photography approaches, we design algorithms that jointly denoise and

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Morimoto, Kazuhiro, and Edoardo Charbon. "A Scaling Law for SPAD Pixel Miniaturization." Sensors 21, no. 10 (2021): 3447. http://dx.doi.org/10.3390/s21103447.

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The growing demands on compact and high-definition single-photon avalanche diode (SPAD) arrays have motivated researchers to explore pixel miniaturization techniques to achieve sub-10 μm pixels. The scaling of the SPAD pixel size has an impact on key performance metrics, and it is, thereby, critical to conduct a systematic analysis of the underlying tradeoffs in miniaturized SPADs. On the basis of the general assumptions and constraints for layout geometry, we performed an analytical formulation of the scaling laws for the key metrics, such as the fill factor (FF), photon detection probability

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Gautam, V., R. Casanova, S. Terzo, and S. Grinstein. "Development of single photon avalanche detectors for NIR light detection." Journal of Instrumentation 17, no. 12 (2022): C12019. http://dx.doi.org/10.1088/1748-0221/17/12/c12019.

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Abstract Near-infrared (NIR) light is used in several non-invasive biomedical techniques to measure the blood flow in deep tissues. The BIOSPAD project targets the development of SPAD arrays specifically designed for Diffuse Correlation Spectroscopy (DCS) in the NIR to measure deep tissue microvascular blood flow. In the first stage of the project, single SPADs with multiplication layers buried at different depths have been designed at IFAE and produced in a 150 nm CMOS technology. In this study, we present results of the characterization of SPAD devices with an area of 50 × 50 µm2 operated wi

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Qiu, Chenxi, Peng Wang, Xiangshun Kong, et al. "On-Chip Compressive Sensing with a Single-Photon Avalanche Diode Array." Sensors 23, no. 9 (2023): 4417. http://dx.doi.org/10.3390/s23094417.

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Single-photon avalanche diodes (SPADs) are novel image sensors that record photons at extremely high sensitivity. To reduce both the required sensor area for readout circuits and the data throughput for SPAD array, in this paper, we propose a snapshot compressive sensing single-photon avalanche diode (CS-SPAD) sensor which can realize on-chip snapshot-type spatial compressive imaging in a compact form. Taking advantage of the digital counting nature of SPAD sensing, we propose to design the circuit connection between the sensing unit and the readout electronics for compressive sensing. To proc

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Goll, Bernhard, Bernhard Steindl, and Horst Zimmermann. "Avalanche Transients of Thick 0.35 µm CMOS Single-Photon Avalanche Diodes." Micromachines 11, no. 9 (2020): 869. http://dx.doi.org/10.3390/mi11090869.

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Two types of single-photon avalanche diodes (SPADs) with different diameters are investigated regarding their avalanche behavior. SPAD type A was designed in standard 0.35-µm complementary metal-oxide-semiconductor (CMOS) including a 12-µm thick p- epi-layer with diameters of 50, 100, 200, and 400 µm; and type B was implemented in the high-voltage (HV) line of this process with diameters of 48.2 and 98.2 µm. Each SPAD is wire-bonded to a 0.35-µm CMOS clocked gating chip, which controls charge up to a maximum 6.6-V excess bias, active, and quench phase as well as readout during one clock period

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Gil, Paula Torrealba de, Paulo Cezar Rezende Fontes, Paulo Roberto Cecon, and Francisco Affonso Ferreira. "Índice SPAD para o diagnóstico do estado de nitrogênio e para o prognóstico da produtividade da batata." Horticultura Brasileira 20, no. 4 (2002): 611–15. http://dx.doi.org/10.1590/s0102-05362002000400020.

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Determinou-se o nível crítico do índice SPAD (Soil Plant Analysis Development) na folha da batateira e verificou-se a possibilidade de sua utilização no prognóstico da produção de tubérculos de batata, cultivar Monalisa. O experimento foi realizado em Argissolo Vermelho-Amarelo, com o teor de N mineral de 39 mg kg-1. O ensaio foi conduzido no delineamento em blocos ao acaso, com quatro repetições, em esquema de parcela subdividida. As parcelas foram constituídas por cinco doses de N (0; 25; 50; 100 e 200 kg ha-1) aplicadas nos sulcos em pré-plantio. As subparcelas constituíram as quatro doses

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Wu, Jau-Yang, Yu-Wei Lu, Meng-Hsuan Liu, Tien-Ning Chang, and Chun-Hsien Liu. "An Analysis of Temperature-Dependent Timing Jitter Factors in the Structural Design of Complementary Metal-Oxide-Semiconductor Single-Photon Avalanche Detectors." Sensors 25, no. 2 (2025): 391. https://doi.org/10.3390/s25020391.

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Single-Photon Avalanche Photodiodes (SPADs) are increasingly utilized in high-temperature-operated, high-performance Light Detection and Ranging (LiDAR) systems as well as in ultra-low-temperature-operated quantum science applications due to their high photon sensitivity and timing resolution. Consequently, the jitter value of SPADs at different temperatures plays a crucial role in LiDAR systems and Quantum Key Distribution (QKD) applications. However, limited studies have been conducted on this topic. In this study, we analyze the jitter characteristics of SPAD devices, focusing on the influe

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Kurilla, Boldizsár. "Single Photon Communication with Avalanche Diodes and the General Basics of Photon Counting." Academic and Applied Research in Military and Public Management Science 15, no. 1 (2016): 19–30. http://dx.doi.org/10.32565/aarms.2016.1.2.

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Single photon communication (SPC) already exists in several applications in laboratory and even outdoor conditions. In the field of quantum cryptography SPC experiments are part of military applications too. There are several methods to detect every single impacting photon in such an experiment. Mostly photomultiplier tubes (PMT) are used. In some cases single photon avalanche diodes (SPAD) are more suitable for photon detection. Both the SPADs and PMTs have advantages and disadvantages. Usually PMTs have much larger detection areas than SPADs, but most of the PMTs detection efficiency peaks a

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Sun, Miao, Shenglong Zhuo, and Patrick Yin Chiang. "Multi-Scale Histogram-Based Probabilistic Deep Neural Network for Super-Resolution 3D LiDAR Imaging." Sensors 23, no. 1 (2022): 420. http://dx.doi.org/10.3390/s23010420.

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LiDAR (Light Detection and Ranging) imaging based on SPAD (Single-Photon Avalanche Diode) technology suffers from severe area penalty for large on-chip histogram peak detection circuits required by the high precision of measured depth values. In this work, a probabilistic estimation-based super-resolution neural network for SPAD imaging that firstly uses temporal multi-scale histograms as inputs is proposed. To reduce the area and cost of on-chip histogram computation, only part of the histogram hardware for calculating the reflected photons is implemented on a chip. On account of the distribu

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Nolet, Frédéric, Valérie Gauthier, Samuel Parent, et al. "Quenching Circuit Discriminator Architecture Impact on a Sub-10 ps FWHM Single-Photon Timing Resolution SPAD." Instruments 7, no. 2 (2023): 16. http://dx.doi.org/10.3390/instruments7020016.

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In the field of radiation instrumentation, there is a desire to reach a sub-10 ps FWHM timing resolution for applications such as time-of-flight positron emission tomography, time-of-flight positron computed tomography and time-resolved calorimetry. One of the key parts of the detection chain for these applications is a single-photon detector and, in recent years, the first single-photon avalanche diode (SPAD) with a sub-10 ps timing resolution was presented. To reach such a timing resolution, the SPAD was read out by an operational amplifier operated in open-loop as a comparator. This paper p

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Zhang, Runfei, Peiqi Yang, Shouyang Liu, Caihong Wang, and Jing Liu. "Evaluation of the Methods for Estimating Leaf Chlorophyll Content with SPAD Chlorophyll Meters." Remote Sensing 14, no. 20 (2022): 5144. http://dx.doi.org/10.3390/rs14205144.

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Leaf chlorophyll content (LCC) is an indicator of leaf photosynthetic capacity. It is crucial for improving the understanding of plant physiological status. SPAD meters are routinely used to provide an instantaneous estimation of in situ LCC. However, the calibration of meter readings into absolute measures of LCC is difficult, and a generic approach for this conversion remains elusive. This study presents an evaluation of the approaches that are commonly used in converting SPAD readings into absolute LCC values. We compared these approaches using three field datasets and one synthetic dataset

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ZHANG Zhijie, Guo Yanqiang, Guo Xiaoli, Zhang li, Song Kaiwei, and Zhang Mingjiang. "Ultra-fast exposure enhanced imaging with SPAD arrays based on super-resolution deep learning." Acta Physica Sinica 74, no. 15 (2025): 0. https://doi.org/10.7498/aps.74.20250432.

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In recent years, with wide applications of high-sensitivity single-photon detectors, especially in the field of quantum imaging and optical imaging has achieved many important results, and low-light imaging technology based on single-photon level has gradually become an important branch in high-resolution imaging systems. Currently, the main single-photon detectors are single-photon counting avalanche diode (SPAD) sensors and support pixel arrays of different sizes, ranging from single-pixel detector sizes to tens of thousands of pixel SPAD arrays. The process structure of single-pixel SPAD de

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Wu, Wen, Xiao Shan, Yaoqiang Long, et al. "Free-Running Single-Photon Detection via GHz Gated InGaAs/InP APD for High Time Resolution and Count Rate up to 500 Mcount/s." Micromachines 14, no. 2 (2023): 437. http://dx.doi.org/10.3390/mi14020437.

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Free-running InGaAs/InP single-photon avalanche photodiodes (SPADs) typically operate in the active-quenching mode, facing the problems of long dead time and large timing jitter. In this paper, we demonstrate a 1-GHz gated InGaAs/InP SPAD with the sinusoidal gating signals asynchronous to the incident pulsed laser, enabling free-running single-photon detection. The photon-induced avalanche signals are quenched within 1 ns, efficiently reducing the SPAD’s dead time and achieving a count rate of up to 500 Mcount/s. However, the timing jitter is measured to be ~168 ps, much larger than that of th

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Hijazi, Mohamad, Shenjie Huang, and Majid Safari. "Highly Sensitive SPAD-Based Receiver for Dimming Control in LiFi Networks." Sensors 23, no. 10 (2023): 4673. http://dx.doi.org/10.3390/s23104673.

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Visible light communication (VLC) is an emerging mode of wireless communication that supports both illumination and communication. One essential function of VLC systems is the dimming control, which requires a sensitive receiver for low-light conditions. The use of an array of single-photon avalanche diodes (SPADs) is one promising approach to enhancing receivers’ sensitivity in a VLC system. However, because of the non-linear effects brought on by the SPAD dead time, an increase in the brightness of the light might degrade its performance. In this paper, an adaptive SPAD receiver is proposed

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Campbell, Richard J., Kendrick N. Mobley, Richard P. Marini, and Douglas G. Pfeiffer. "Growing Conditions Alter the Relationship Between SPAD-501 Values and Apple Leaf Chlorophyll." HortScience 25, no. 3 (1990): 330–31. http://dx.doi.org/10.21273/hortsci.25.3.330.

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The relationship between SPAD-501 meter readings (SPAD) and total chlorophyll content (TCHL) was evaluated for `Delicious' apple (Malus domestica Borkh.) leaves grown in various environments. Regression models were developed between SPAD and TCHL for each of six separate experiments and were evaluated for statistical coincidence. SPAD was linearly related in a positive manner to TCHL in five of the six experiments; however, models differed between experiments, particularly between field- and greenhouse-grown trees. Thus, the relationship between SPAD and TCHL must be determined for each experi

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Zhang, Qing Wen, Zheng Li Yang, Ai Ping Zhang, and Ming Wang. "Responses of Rice (Oryza sativa L.) Nitrogen Status Indicators to Nitrogen Rates during the Different Rice Growth Stages." Advanced Materials Research 726-731 (August 2013): 4411–17. http://dx.doi.org/10.4028/www.scientific.net/amr.726-731.4411.

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The SPAD was shown as a diagnostic tool to assess the nitrogen (N) nutrition status. The objective of this study is to evaluate the performance of SPAD as N nutrition status for rice. We conducted two years field experiment in the Ningxia irrigation area. Five N application rates were applied to rice to obtain contrasting conditions of N availability. The leaves N concentrations, SPAD and N uptake by rice were assessed. The results showed that response of SPAD to N uptake rate depends on the developmental stage of the rice. The peak periods for N uptake by rice were the jointing-booting stage

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Nolet, Frédéric, Samuel Parent, Nicolas Roy, et al. "Quenching Circuit and SPAD Integrated in CMOS 65 nm with 7.8 ps FWHM Single Photon Timing Resolution." Instruments 2, no. 4 (2018): 19. http://dx.doi.org/10.3390/instruments2040019.

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This paper presents a new quenching circuit (QC) and single photon avalanche diode (SPAD) implemented in TSMC CMOS 65 nm technology. The QC was optimized for single photon timing resolution (SPTR) with a view to an implementation in a 3D digital SiPM. The presented QC has a timing jitter of 4 ps full width at half maximum (FWHM) and the SPAD and QC has a 7.8 ps FWHM SPTR. The QC adjustable threshold allows timing resolution optimization as well as SPAD excess voltage and rise time characterization. The adjustable threshold, hold-off and recharge are essential to optimize the performances of ea

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Nascimento, Helena Cristina Santos, and Ricardo Antonio Marenco. "SPAD-502 readings in response to photon fluence in leaves with different chlorophyll content." Revista Ceres 57, no. 5 (2010): 614–20. http://dx.doi.org/10.1590/s0034-737x2010000500008.

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The chlorophyll meter (SPAD-502) is widely used to estimate chlorophyll content, but non-uniform chloroplast distribution can affect its accuracy. This study aimed to assess the effect of photon fluence (F, irradiance x time of illumination) in leaves with different chlorophyll content and determine the effect of chlorophyll a/b on SPAD values of four tropical tree species (Croton draconoides Müll. Arg., Hevea guianensis Aubl., Hymenaea courbaril L. and Matisia cordata H.B.K.). There were also determined calibration equations for the chlorophyll meter and assessed the effect of F on SPAD value

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Sun, Xin, Hu Yan, Hongcun He, Xiangshun Kong, Chen Mao, and Feng Yan. "Comparative Analysis of Free-Running and Gating Imaging Modes of SPAD Sensors." Photonics 11, no. 8 (2024): 721. http://dx.doi.org/10.3390/photonics11080721.

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A single-photon avalanche diode (SPAD) is a photon-counting sensor renowned for its exceptional single-photon sensitivity. One significant feature of SPADs is their non-linear response to light, making them ideal for high-dynamic range imaging applications. In SPAD imaging, the photon detection mode, which depends on the quenching method employed, is crucial for optimizing image quality and dynamic range. This paper examines the free-running and gating imaging modes, evaluating their impacts on photon capture and saturation limits. Given that the number of incident photons follows a Poisson di

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Ito, Seigo, Mineki Soga, Shigeyoshi Hiratsuka, Hiroyuki Matsubara, and Masaru Ogawa. "Quality Index of Supervised Data for Convolutional Neural Network-Based Localization." Applied Sciences 9, no. 10 (2019): 1983. http://dx.doi.org/10.3390/app9101983.

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Automated guided vehicles (AGVs) are important in modern factories. The main functions of an AGV are its own localization and object detection, for which both sensor and localization methods are crucial. For localization, we used a small imaging sensor named a single-photon avalanche diode (SPAD) light detection and ranging (LiDAR), which uses the time-of-flight principle and arrays of SPADs. The SPAD LiDAR works both indoors and outdoors and is suitable for AGV applications. We utilized a deep convolutional neural network (CNN) as a localization method. For accurate CNN-based localization, th

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Scott, Ryan, Wei Jiang, Xuanyu Qian, and M. Jamal Deen. "A Multi-Time-Gated SPAD Array with Integrated Coarse TDCs." Electronics 11, no. 13 (2022): 2015. http://dx.doi.org/10.3390/electronics11132015.

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Time-gating of single-photon avalanche diodes (SPADs) was commonly used as a method to reduce dark noise in biomedical imaging applications where photon events are correlated with a reference clock. Time-gating was also used to obtain timing information of photon events by shifting the gate windows applied to a SPAD array. However, in this approach, fine timing resolution comes at the cost of a lengthened measurement time due to the large number of counts required for each shift. As a solution, we present a multi-time-gated SPAD array that simultaneously applies shifted gate windows to an arra

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Schenk, Tobias, Laura Trimborn, Song Chen, Christian Schenkel, and Ute Hoecker. "Light-induced degradation of SPA2 via its N-terminal kinase domain is required for photomorphogenesis." Plant Physiology 187, no. 1 (2021): 276–88. http://dx.doi.org/10.1093/plphys/kiab156.

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Abstract Arabidopsis (Arabidopsis thaliana) CONSTITUTIVELY PHOTOMORPHOGENIC1 (COP1) and members of the SUPPRESSOR OF PHYTOCHROMEA-105 (SPA) protein family form an E3 ubiquitin ligase that suppresses light signaling in darkness by polyubiquitinating positive regulators of the light response. COP1/SPA is inactivated by light to allow photomorphogenesis to proceed. Mechanisms of inactivation include light-induced degradation of SPA1 and, in particular, SPA2, corresponding to a particularly efficient inactivation of COP1/SPA2 by light. Here, we show that SPA3 and SPA4 proteins are stable in the li

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Chang, Dae Ryun. "SPAD." Journal of Promotion Management 2, no. 2 (1994): 45–58. http://dx.doi.org/10.1300/j057v02n02_03.

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Loh, Felix, Jason Grabosky, and Nina Bassuk. "191 Use of the Minolta SPAD-502 to Determine Chlorophyll Concentration in Ficus benjamina L. and Populus deltoides Marsh Leaf Tissue." HortScience 35, no. 3 (2000): 423D—424. http://dx.doi.org/10.21273/hortsci.35.3.423d.

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The Minolta SPAD meter has been used to evaluate chlorophyll concentration in plant material to provide an inexpensive method to collect rapid, nondestructive data. Correlations of SPAD data and chlorophyll concentrations in corn have been very accurate r2 = 0.95), and can be used to monitor plant nutrient status as a function of chlorophyll concentration. There has been evidence that the calibrated accuracy of the SPAD meter is diminished at low and high concentrations of chlorophyll. Our study attempted to build the same type of background information for two tree species for use in evaluati

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Ványiné Széles, A. "Evaluation of the level of N supply in maize hybrids at different nutritional levels." Acta Agronomica Hungarica 58, Supplement 1 (2010): 89–94. http://dx.doi.org/10.1556/aagr.58.2010.suppl.1.13.

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The aim of the research was to determine the effect of fertilisation and year on the SPAD value and on the dynamics of the SPAD value during the growing season.The results proved that the SPAD value steadily decreased over the growing season in a dry year, whereas it increased in a year with favourable precipitation. Fertilisation increased the SPAD values significantly (P<0.001). The significantly highest SPAD value, in both dry years and those with average rainfall, was achieved by applying 60 kg N ha −1 fertiliser active ingredient at the 6-leaf stage, and 120 kg N ha −1 at both the 12-l

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Rhezali, Abdelaziz, and Abdellah El Aissaoui. "Feasibility Study of Using Absolute SPAD Values for Standardized Evaluation of Corn Nitrogen Status." Nitrogen 2, no. 3 (2021): 298–307. http://dx.doi.org/10.3390/nitrogen2030020.

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Nitrogen fertilizer recommendations for corn (Zea mays L.) should ensure high yields using adequate N doses. Soil–plant analysis development (SPAD) meter technology using absolute SPAD values, might be more reliable than relative SPAD values in helping corn producers making timely decisions about N applications. This study aimed to develop a relationship between absolute SPAD values and leaf N concentration, and to determine optimal leaf N concentrations at early corn growth stages (V6, V8, V10, and V12). Three experiments were conducted during two summer seasons (2014 and 2015) using six N tr

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Li, Y. C., A. K. Alva, D. V. Calvert, and M. Zhang. "A Rapid Nondestructive Technique to Predict Leaf Nitrogen Status of Grapefruit Tree with Various Nitrogen Fertilization Practices." HortTechnology 8, no. 1 (1998): 81–86. http://dx.doi.org/10.21273/horttech.8.1.81.

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The objective of this study was to evaluate the use of a leaf chlorophyll meter (SPAD-502) to predict nitrogen status and yield response of grapefruit trees. The study included two irrigation treatments, three sources, and four rates of fertilizer [dry soluble granular fertilizer broadcast or through fertigation with N rates either 50, 100, 150 lb/acre/yr (56, 112, or 168 kg.ha-1.yr-1)], and controlled-release fertilizer with N rates either 25, 50, 100 lb/acre. Irrigation treatments did not affect SPAD readings and leaf N concentrations. Correlations between SPAD readings and leaf N were great

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Minotti, P. L., D. E. Halseth, and J. B. Sieczka. "Field Chlorophyll Measurements to Assess the Nitrogen Status of Potato Varieties." HortScience 29, no. 12 (1994): 1497–500. http://dx.doi.org/10.21273/hortsci.29.12.1497.

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We report three N rate experiments conducted on a gravelly loam soil to assess the N status of potato (Solanum tuberosum L.) using a Minolta SPAD-502 chlorophyll meter. Highly significant linear and quadratic trends were obtained for the regression of N rate on marketable tuber yields and SPAD readings. SPAD readings were taken at four times during the growing season and decreased as plants aged. Based on regression analysis, the early season SPAD readings, associated with N rates giving maximum marketable tuber yields, ranged from 49 to 56 units depending on year, variety, and location. Potat

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Xun, Mingzhu, Yudong Li, Jie Feng, Chengfa He, Mingyu Liu, and Qi Guo. "Effect of Proton Irradiation on Complementary Metal Oxide Semiconductor (CMOS) Single-Photon Avalanche Diodes." Electronics 13, no. 1 (2024): 224. http://dx.doi.org/10.3390/electronics13010224.

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The effects of proton irradiation on CMOS Single-Photon Avalanche Diodes (SPADs) are investigated in this article. The I–V characteristics, dark count rate (DCR), and photon detection probability (PDP) of the CMOS SPADs were measured under 30 MeV and 52 MeV proton irradiations. Two types of SPAD, with and without shallow trench isolation (STI), were designed. According to the experimental results, the leakage current, breakdown voltage, and PDP did not change after irradiation at a DDD of 2.82 × 108 MeV/g, but the DCR increased significantly at five different higher voltages. The DCR increased

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Zhu, Juanjuan, Nicolas Tremblay, and Yinli Liang. "Comparing SPAD and atLEAF values for chlorophyll assessment in crop species." Canadian Journal of Soil Science 92, no. 4 (2012): 645–48. http://dx.doi.org/10.4141/cjss2011-100.

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Zhu, J., Tremblay, N. and Liang, Y. 2012. Comparing SPAD and atLEAF values for chlorophyll assessment in crop species. Can. J. Soil Sci. 92: 645–648. This research had the objective of determining whether a new light transmittance meter, the atLEAF, could be used as a less expensive alternative to the SPAD meter. Both meters measure transmittance through leaf surfaces in wavelengths associated with chlorophyll, and both provide an indirect method for determining the nitrogen status of crop canopies. The current study compared SPAD and atLEAF values under different conditions and for six crop s

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Maiti, Debtanu, D. K. Das, Tanmoy Karak, and Mahua Banerjee. "Management of Nitrogen Through the Use of Leaf Color Chart (LCC) and Soil Plant Analysis Development (SPAD) or Chlorophyll Meter in Rice Under Irrigated Ecosystem." Scientific World JOURNAL 4 (2004): 838–46. http://dx.doi.org/10.1100/tsw.2004.137.

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A field experiment was conducted in a farmers field in the district of Nadia, West Bengal, India to study the management of N through leaf color chart (LCC) and soil plant analysis development (SPAD) or chlorophyll meter in rice (cv. IET-4094) during the Kharif (wet season) of 20012002 and 20022003 by taking the treatment combinations based on different levels of N at fixed schedule and through LCC and SPAD. The experimental soil (015 cm) had pH 7.33; organic C 0.43%; available N 408.70 kg ha−1; available P 6.92 kg ha−1; and available K 66.31 kg ha−1. The results of LCC and SPAD or chlorop

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Neilsen, Denise, Eugene J. Hogue, Gerald H. Neilsen, and Peter Parchomchuk. "Using SPAD-502 Values to Assess the Nitrogen Status of Apple Trees." HortScience 30, no. 3 (1995): 508–12. http://dx.doi.org/10.21273/hortsci.30.3.508.

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Four apple (Malus domestica Borkh) cultivars (`Fuji', `Spartan', `Fiesta', and `Gala') on Malling 9 (M.9) rootstock were grown in the field with three N rates (5, 20, and 35 g N/tree per year), supplied as Ca(NO3)2, and fertigated daily for 9 weeks. In the second year, leaf SPAD readings (chlorophyll readings obtained with the Minolta-502 SPAD meter) increased over the growing season for all cultivars, and leaf N decreased. Leaf SPAD and leaf N measurements increased in response to N fertigation rate at all sampling times. `Gala' consistently had lower SPAD readings than the other cultivars, a

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Loh, Felix C. W., Jason C. Grabosky, and Nina L. Bassuk. "Using the SPAD 502 Meter to Assess Chlorophyll and Nitrogen Content of Benjamin Fig and Cottonwood Leaves." HortTechnology 12, no. 4 (2002): 682–86. http://dx.doi.org/10.21273/horttech.12.4.682.

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A Minolta SPAD-502 leaf chlorophyll meter was used for nondestructive data collection on the chlorophyll and nitrogen (N) status of benjamin fig (Ficus benjamina) and cottonwood (Populus deltoides) to quantitatively evaluate foliage quality. The goal was to provide a specific calibration for interpreting SPAD data within a media study for each species. Triplicate SPAD readings were collected from each of six leaves, sampled from forty plants per species, then processed for foliar analysis. Leaf tissue disks were also collected directly over SPAD testing sites for chlorophyll concentration meas

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REENA, V.C. DHYANI, and SUMIT CHATURVEDI. "Efficient nitrogen management in wheat (Triticum aestivum) using leaf-colour chart and chlorophyll meter for optimizing growth, yield and nitrogen-use efficiency." Indian Journal of Agronomy 61, no. 3 (2001): 392–95. http://dx.doi.org/10.59797/ija.v61i3.4382.

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A field experiment was conducted at Pantnagar, Uttarkahand, during the winter (rabi) season of 201415, to study the effect of modern tools such as leaf colour chart (LCC) and chlorophyll meter (SPAD meter) on growth, yield and nitrogen-use efficiency in wheat [Triticum aestivum (L.) emend. Fiori & Paol.] crop. Application of N as 25 kg as basal + 40 kg (at LCC 4,5 and SPAD 35, 40) and 25 kg as basal + 40 kg at crown-root initiation + 40 kg at SPAD 40 (total 105 kg N/ha) resulted statistically similar growth and yield attributes, viz. shoot density, dry-matter accumulation, leaf-area index,

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Farid Hanafiyanto and Wahono. "PERBANDINGAN AKURASI PENGUKURAN KLOROFIL DAN KADAR NITROGEN ANTARA SPAD DENGAN NDVI PADA TANAMAN JAGUNG (Zea mays)." Jurnal Agro Indragiri 8, no. 2 (2021): 11–21. http://dx.doi.org/10.32520/jai.v8i2.1747.

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SPAD merupakan teknologi manual sebagai pendeteksi kandungan klorofil lapang. Penggunaan SPAD untuk mendeteksi kandungan klorofil dan menentukan kesehatan tanaman. SPAD membutuhkan waktu lama dan kurang efektif jika digunakan dalam suatu areal lahan yang luas. Perkembangan teknologi pertanian seperti UAV menjawab permasalahan dan kebutuhan masyarakat yang memiliki lahan yang luas, sehingga dapat menghemat waktu dan biaya. NDVI mempermudah mendeteksi kesehatan tanaman dengan melihat kandungan klorofil dan nitrogen pada tanaman. Tujuan penelitian ini yaitu (1) Mengetahui perbandingan akurasi pen

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D’Oliveira, Pérsio Sandir, Letícia Sayuri Suzuki, Jailton da Costa Carneiro, Juarez Campolina Machado, Jader Forquim Prates, and João Romero do Amaral Santos de Carvalho Rocha. "Use of SPAD index in elephant grass pre-breeding." Semina: Ciências Agrárias 41, no. 3 (2020): 1047. http://dx.doi.org/10.5433/1679-0359.2020v41n3p1047.

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The SPAD-502 (Soil Plant Analysis Development) chlorophyll meter is a simple diagnostic tool that instantly measures the chlorophyll content of plant leaves without damaging the leaf blade. This study aimed to evaluate the efficacy of the SPAD index as a tool for discriminating elephant grass acessions from different morphological groups. One hundred genotypes of the elephant grass Pennisetum purpureum from the Active Germplasm Bank at Embrapa Dairy Cattle, Minas Gerais, Brazil were evaluated. Following uniform cutting, six SPAD readings were taken from each accession every 60 days. Measuremen

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Mahmoudi, Hiwa, Michael Hofbauer, Bernhard Goll, and Horst Zimmermann. "Noise and Breakdown Characterization of SPAD Detectors with Time-Gated Photon-Counting Operation." Sensors 21, no. 16 (2021): 5287. http://dx.doi.org/10.3390/s21165287.

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Being ready-to-detect over a certain portion of time makes the time-gated single-photon avalanche diode (SPAD) an attractive candidate for low-noise photon-counting applications. A careful SPAD noise and performance characterization, however, is critical to avoid time-consuming experimental optimization and redesign iterations for such applications. Here, we present an extensive empirical study of the breakdown voltage, as well as the dark-count and afterpulsing noise mechanisms for a fully integrated time-gated SPAD detector in 0.35-μm CMOS based on experimental data acquired in a dark condit

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Goll, Bernhard, Mehran Saadi Nejad, Kerstin Schneider-Hornstein, and Horst Zimmermann. "Reducing Avalanche Build-Up Time by Integrating a Single-Photon Avalanche Diode with a BiCMOS Gating Circuit." Sensors 24, no. 23 (2024): 7598. http://dx.doi.org/10.3390/s24237598.

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It is shown that the integration of a single-photon avalanche diode (SPAD) together with a BiCMOS gating circuit on one chip reduces the parasitic capacitance a lot and therefore reduces the avalanche build-up time. The capacitance of two bondpads, which are necessary for the connection of an SPAD chip and a gating chip, are eliminated by the integration. The gating voltage transients of the SPAD are measured using an integrated mini-pad and a picoprobe. Furthermore, the gating voltage transients of a CMOS gating circuit and of the BiCMOS gating circuit are compared for the same integrated SPA

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Aguénounon, Enagnon, Safa Razavinejad, Jean-Baptiste Schell, et al. "Design and Characterization of an Asynchronous Fixed Priority Tree Arbiter for SPAD Array Readout." Sensors 21, no. 12 (2021): 3949. http://dx.doi.org/10.3390/s21123949.

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The usage of single-photon avalanche diode arrays is becoming increasingly common in various domains such as medical imaging, automotive vision systems, and optical communications. Nowadays, thanks to the development of microelectronics technologies, the SPAD arrays designed for these applications has been drastically well-facilitated, allowing for the manufacturing of large matrices. However, there are growing challenges for the design of readout circuits with the needs of reducing their energy consumption (linked to the usage cost) and data rate. Indeed, the design of the readout circuit for

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ZHOU, GUISU, and XINHUA YIN. "ASSESSING NITROGEN NUTRITIONAL STATUS, BIOMASS AND YIELD OF COTTON WITH NDVI, SPAD AND PETIOLE SAP NITRATE CONCENTRATION." Experimental Agriculture 54, no. 4 (2017): 531–48. http://dx.doi.org/10.1017/s0014479717000229.

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SUMMARYCanopy normalized difference vegetation index (NDVI), soil plant analysis development (SPAD) reading and petiole sap NO3−‒N concentration are increasingly used as quick and non-destructive methods to monitor plant N nutrition and growth status and predict yield of crops. However, little information is available on the comparisons of these three methods in assessing N nutrition, growth and yield for cotton (Gossypium hirsutum L.). Four N rates (0, 34, 67 and 101 kg N ha−1) under two cover conditions [no cover crop and hairy vetch (Vicia villosa) crop] in a 33-year long-term field trial w

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Peltonen, Jari, Ari Virtanen, Jaakko Helenius, Juha Suopelto, Kari Kittilä та Esko Eloranta. "Determination of barley nitrogen status with chlorophyll meter for high β-amylase in grains". Agricultural and Food Science 4, № 5-6 (1995): 495–501. http://dx.doi.org/10.23986/afsci.72625.

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The production of β-amylase is of great importance in two-rowed spring barley cv. Kymppi (Hordeum vulgare L.) in the Finland, where long-day conditions favour high enzyme activities. Nitrogen (N) fertilization of a crop is the main means of manipulating barley β-amylase activity for industrial purposes. In this study, leaf chlorophyll content determined with a portable chlorophyll meter (Minolta SPAD-502) in the field, was used to predict N availability of cv. Kymppi for β-amylase production. Critical chlorophyll meter readings (SPAD values) were calculated from data deriving from experiments

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Pinzón-Sandoval, Elberth Hernando, Helber Enrique Balaguera-López, and Pedro José Almanza-Merchán. "Evaluation of SPAD Index for Estimating Nitrogen and Magnesium Contents in Three Blueberry Varieties (Vaccinium corymbosum L.) on the Andean Tropics." Horticulturae 9, no. 2 (2023): 269. http://dx.doi.org/10.3390/horticulturae9020269.

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In the Ericaceae family, blueberries are the most commercially important species. Estimating the nutritional and physiological status of plants is a common practice carried out by producers. However, conventional methods are destructive, costly and time consuming. In recent years, methodologies such as measurements with the SPAD chlorophyll index have become available, which has proven to be an easy, fast and non-destructive method for estimating chlorophyll, N and Mg contents in the field. Therefore, this research aimed to estimate variations in SPAD readings between varieties and to determin

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