Log In Sign up
The largest database of trusted experimental protocols
> Chemicals & Drugs > Biomedical or Dental Material > SPAD

SPAD

SPAD (Single-Photon Avalanche Diode) is a type of photodetector that can detect individual photons with high sensitivity.
This technology has numerous applications in fields such as quantum optics, time-of-flight imaging, and lidar.
PubCompare.ai is an AI-driven platform that streamlines SPAD research by helping scientists easily locate relevant protocols from literature, preprints, and patents.
The platform's cutting-edg technology enables AI-powered comparisons to identify the best SPAD protocols and products for specific needs, elevating research accuracy and efficiency.
With PubCompare.ai, researchers can accelerate their SPAD studies and unlock new discoveries.

Most cited protocols related to «SPAD»

1
Leaf Chlorophyll Extraction and Estimation
Cited 33 times
Discs of 16 mm diameter (2 cm2) were used for the extraction. The exact point where sensor measurements were performed was sampled in order to mitigate for leaf heterogeneity. The sensing surface of SPAD is 2 mm × 3 mm, compared to a 10 mm diameter for CCM (Opti-Sciences, Hudson, NH ) and a 6 mm diameter for Dx4 (FORCE-A, Orsay, France). For chlorophyll estimation, measurements were always performed with the adaxial leaf side facing the light sources. Leaf discs were collected immediately after measurements, frozen in liquid nitrogen and stored at – 80°C until further processing. Discs were powdered in liquid nitrogen and extracted three times with methanol (3 × 1.5 ml) containing CaCO3. Supernatants of the three centrifugations (10 000 g, 5 min) were grouped and topped to 5 ml, then centrifuged again at 4100 g for 5 min. The extinction coefficients for pure methanol of Porra et al. (1989) were used to calculate the Chl concentration in the extracts (in µg cm–2):

where A stands for absorbance in a 1-cm cuvette at the specified wavelength (spectrophotometer HP 8453, Agilent, les Ulis, France).
LMA was estimated for each leaf by sampling a second 16-mm-diameter disc adjacent to the one used for Chl estimation. The disc was dried at 60°C for 48 h and weighed.
Cerovic Z.G., Masdoumier G., Ghozlen N.B, & Latouche G. (2012). A new optical leaf-clip meter for simultaneous non-destructive assessment of leaf chlorophyll and epidermal flavonoids. Physiologia Plantarum, 146(3), 251-260.
Publication 2012
Carbonate, Calcium Centrifugation Chlorophyll Extinction, Psychological Freezing Genetic Heterogeneity Light Methanol Nitrogen Plant Leaves SPAD
2
Mapping HIV-1 Integration Sites within SPAD and SE Regions
Cited 9 times
Chromosomal regions that lie within 500 nm of NSs are defined as SPADs33 (link). The SPAD data set33 (link) was reproduced herein using Bowtie267 (link) to map raw sequence reads from archived file SRR3538917 to human genome build hg19. As outlined in Chen et al.33 (link), SPAD sites were defined as TSA-Seq scores greater than the 95th percentile, which yielded 1,547,458 SPAD sequences each of 100 bp in length. SE sequences from Jurkat T cells were directly downloaded as a bed file from the dbSUPER database68 (link).
Illumina sequence reads from prior HIV-1 integration studies19 (link),22 (link),35 (link) were mapped to the human genome as previously described19 (link),69 (link),70 . In brief, U5 vDNA sequences trimmed from Illumina read1 reads were deduplicated and aligned to hg19 by BLAT71 (link) or HISAT272 (link). Unique integration sites were selected for downstream analysis.
The RIC data set was determined by digesting hg19 with MseI and BglII restriction enzymes in silico. Percentages of bulk integration sites that fell within SPAD or SE sequences were calculated using bedtools intersect73 (link). Associated p values were calculated by Fisher’s exact test in a pairwise manner using Python. The frequency of integration relative to SPADs in Fig. 8d–f and Supplementary Fig. 6b was plotted using 200 kb bins.
RIGs were identified as genes targeted for integration across cell types (HEK293T, HOS, MDM, and primary CD4+ T cells)19 (link). Briefly, the number of integrations per RefSeq gene was calculated using bedtools73 (link) for wet bench libraries and the in silico generated RIC. In each cell type, integration frequency observed in individual genes was compared to that of the RIC to identify genes that are frequently targeted for integration (genic integration frequency > RIC and p < 0.05; Fisher’s exact test). RIGs were then defined as genes frequently targeted for integration in at least three of the studied four cell types. This yielded a total of 46 RIGs from WT CPSF6-expressing cell types and 30 RIGs from cells infected under CPSF6-defective conditions (Supplementary Table S1). Distances from RIG to nearest SE or SPAD were determined as the distances between the closest boundaries between the gene vs. SE/SPAD using bedtools73 (link).
Francis A.C., Marin M., Singh P.K., Achuthan V., Prellberg M.J., Palermino-Rowland K., Lan S., Tedbury P.R., Sarafianos S.G., Engelman A.N, & Melikyan G.B. (2020). HIV-1 replication complexes accumulate in nuclear speckles and integrate into speckle-associated genomic domains. Nature Communications, 11, 3505.
Publication 2020
BP 100 CD4 Positive T Lymphocytes Cells Chromosomes Dietary Fiber DNA Restriction Enzymes Genes Genome, Human HIV-1 Homo sapiens Python SPAD T-Lymphocyte
3
Single-Molecule FRET Analysis using μs-ALEX Microscopy
Cited 5 times
For single-molecule experiments custom-built confocal microscopes for μs-ALEX described in115 (link)116 were used as schematically shown in Fig. S2. Shortly, the alternation period was set to 50 μs, and the excitation intensity to 60 μW at 532 nm and 25 μW at 640 nm. A 60x objective with NA = 1.35 (Olympus, UPLSAPO 60XO) was used. Laser excitation was focused to a diffraction limited spot 20 μm into the solution. Fluorescence emission was collected, filtered against background (using a 50-μm pinhole and bandpass filters) and detected with two avalanche photodiode detectors (τ-spad, Picoquant, Germany). After data acquisition, fluorescence photons arriving at the two detection channels (donor detection channel: Dem; acceptor detection channel: Aem) were assigned to either donor- or acceptor-based excitation on their photon arrival time as described previously66 (link)81 (link). From this, three photon streams were extracted from the data corresponding to donor-based donor emission F(DD), donor-based acceptor emission F(DA) and acceptor-based acceptor emission F(AA; Fig. S2A).
During diffusion (Fig. S2B), fluorophore stoichiometries S and apparent FRET efficiencies E* were calculated for each fluorescent burst above a certain threshold yielding a two-dimensional histogram66 (link)81 (link). Uncorrected FRET efficiency E* is calculated according to:

S is defined as the ratio between the overall green fluorescence intensity over the stotal green and red fluorescence intensity and describes the ratio of donor-to-acceptor fluorophores in the sample S:

Using published procedures to identify bursts corresponding to single molecules117 (link), we obtained bursts characterized by three parameters (M, T, and L). A fluorescent signal is considered a burst provided it meets the following criteria: a total of L photons, having M neighbouring photons within a time interval of T microseconds. For all data presented in this study, a dual colour burst search117 (link)118 (link) using parameters M = 15, T = 500 μs and L = 25 was applied; additional thresholding removed spurious changes in fluorescence intensity and selected for intense single-molecule bursts (all photons >100 photons unless otherwise mentioned). Binning the detected bursts into a 2D E*/S histogram where sub-populations are separated according to their S-values. E*- and S-distributions were fitted using a Gaussian function, yielding the mean values μi of the distribution and an associated standard deviations wi. Experimental values for E* and S were corrected for background, spectral crosstalk (proximity ratio EPR) and gamma factor resulting in histograms of accurate FRET E and corrected S according to published procedures48 (link).
Ploetz E., Lerner E., Husada F., Roelfs M., Chung S., Hohlbein J., Weiss S, & Cordes T. (2016). Förster resonance energy transfer and protein-induced fluorescence enhancement as synergetic multi-scale molecular rulers. Scientific Reports, 6, 33257.
Publication 2016
Avalanches Cross Reactions Diffusion Fluorescence Fluorescence Resonance Energy Transfer Gamma Rays Population Group Single Molecule Microscopy SPAD Strains Tissue Donors
4
Comprehensive Phenotyping of Common Bean Genotypes
Cited 5 times
These include non-destructive measurements that are related to physiological processes such as photosynthetic efficiency, total chlorophyll content (Soil–Plant Analyses Development or SPAD measurement), stomatal conductance, transpiration rate, leaf temperature (in both the morning and afternoon), and leaf water potential. The destructive measurements that are related to growth and metabolism include LAI, canopy dry weight per plant (leaf, stem and pod biomass), shoot nutrient (nitrogen and phosphorus) uptake, shoot and seed ash content, and shoot and seed total non-structural carbohydrates (TNC). Seed nitrogen, phosphorus, ash content, and TNC can be measured at the time of harvest.
Field evaluation of 121 RILs of the cross MD 23-24 × SEA 5 over 2 seasons at CIAT in Colombia using the above phenotyping protocol resulted in identification of one line (MR 81) that was superior in its adaptation to drought stress conditions (Rao et al., 2005 ). The superior performance of this line was associated with higher values of PHI, pod partitioning index, HI, and seed TNC, and a lower proportion of pod wall biomass and lower value of seed phosphorus content, indicating the importance of greater mobilization of photosynthates to pods and seeds per unit of seed phosphorus in common beans under rainfed conditions.
Beebe S.E., Rao I.M., Blair M.W, & Acosta-Gallegos J.A. (2013). Phenotyping common beans for adaptation to drought. Frontiers in Physiology, 4, 35.
Publication 2013
Acclimatization Carbohydrates Chlorophyll Droughts Metabolism Nitrogen Nutrients Phosphorus Photosynthesis Physiological Processes Plant Development Plant Embryos Plant Leaves Plants SPAD Stem, Plant Stress Disorders, Traumatic Surgical Stoma
5
FCCS Measurements of Lipid-Anchored Proteins
Cited 5 times
FCCS measurements of lipid-anchored proteins
in live cells were taken on a customized microscope setup. A Kr/Ar
mixed gas laser (Stabilite 2018-RM, Newport Corp., Irvine, CA) provides
a wavelength of 568 nm, while a pulsed diode laser (LDH-P-C-485, PicoQuant,
Berlin, Germany) provides a 479 nm wavelength. For FCCS, the 568 and
479 nm lines are combined and coupled into a single-mode optical fiber.
As the combined beams exit the fiber, they are collimated with an
achromatic objective lens (Leica, 10×) and directed via a custom
polychroic mirror (Chroma Technology Corp., Rockingham, VT) into the
optical path of the microscope (TE2000E, Nikon Corp., Tokyo, Japan).
A 100× TIRF oil objective, NA 1.49 (Nikon Corp., Tokyo, Japan),
focuses down the excitation beam. The fluorescence is collected through
the same objective and passed through a custom notch filter (Semrock,
Rochester, NY) to remove any scattered laser light. The emitted light
is then passed through a 50 μm confocal pinhole (Thorlabs, Newton,
NJ). A 580 nm long-pass beamsplitter then splits and directs the emitted
light toward two avalanche photodiodes (APDs) (SPCM-AQRH-16, Perkin-Elmer,
Canada). Short-pass (550 nm) and band-pass (645/75 nm) optical filters
(Chroma Technology Corp., Rockingham, VT) for the green and red channels,
respectively, further select for proper wavelengths. A time-correlated
single photon-counting (TCSPC) card (PicoQuant, TimeHarp 200, Berlin,
Germany) collects signal from the APDs through a universal router
(PRT 400, TTL SPAD router, PicoQuant, Berlin, Germany). The power
of each laser was measured before entering the optical path of the
microscope and was kept between 0.9 and 1.5 μW. Measurements
were taken with the lasers pulsing at 10 MHz. The cw Kr/Ar beam is
also pulsed at 10 MHz using an electro-optic modulator (EOM, 350-160
KD*P series, ConOptics) to give 18 ns pulses. The pulsing of the EOM
and the diode laser is controlled and synchronized by a pulse generator
(Quantum Composers, 9530 series). A delay of about 50 ns is set between
the diode pulse and the EOM to ensure that the fluorescence completely
decays between excitation pulses.
Cells with similar intensities
in GFP and mCherry epi-fluorescent channels were selected for FCCS.
When taking FCCS measurements, areas of the cell with obvious background
fluorescence from proteins inserted into membranes of organelles or
intracellular vesicles were avoided. The bottom membrane of the cell
was brought into focus, which was maintained with an active focus
stabilizer (Perfect Focus System, Nikon Corp., Tokyo, Japan). We measured
up to five 15 s measurements in three to five spots in each cell for
all samples. The cell samples were kept at room temperature for data
acquisition and were observed for no more than 1.5 h.
Triffo S.B., Huang H.H., Smith A.W., Chou E.T, & Groves J.T. (2012). Monitoring Lipid Anchor Organization in Cell Membranes by PIE-FCCS. Journal of the American Chemical Society, 134(26), 10833-10842.
Publication 2012
Avalanches Cells Exanthema Eye Fibrosis Fluorescence lactate dehydrogenase C Lasers, Semiconductor Lens, Crystalline Light Lipids Microscopy Organelles Proteins Pulse Rate Pulses SPAD Tissue, Membrane Vision

Most recents protocols related to «SPAD»

1
Chlorophyll Measurement in Leaf Samples
Not available on PMC !

Example 2

Chlorophyll contents were determined by measuring leaf absorbance in the red and infrared regions using a SPAD-502 Plus device (Minolta Camera Co., Osaka, Japan). Chlorophyll was measured twice in the same day at different positions in all fully expanded (length>15 cm) leaves (leaves 6-26) from six randomly-selected plants from each line at five growth stages: before flowering (6.5-week-old plants and 2.5 weeks before topping), at topping, 1 and 2.5 WPT and at harvest (30 days post topping) before flowering. The total chlorophyll content was calculated as an average of all measured leaf chlorophyll values per plant to minimize the influence of leaf position.

US11859192B2. Compositions and methods for producing tobacco plants and products having altered alkaloid levels with desirable leaf quality (2024-01-02). Altria Client Services LLC [US]. Inventors: Marcos Fernando de Godoy Lusso [US], James A. Strickland [US], Jesse Frederick [US], Dongmei Xu [US], Chengalrayan Kudithipudi [US].
Patent 2024
Chlorophyll Medical Devices Plant Leaves Plants SPAD
2
Measuring Chlorophyll Content Under Heat Stress
Chlorophyll content was measured using a self-calibrating SPAD chlorophyll meter (Model 502, Spectrum Technologies, Plainfield, IL) as described by Ristic et al. (2008) (link) with modifications. Briefly, three readings were taken in the middle of the flag leaf of the primary tiller of each plant and averaged for every pot. The measurements were conducted at Days 0, 4, 8, 12, and 16 during the heat stress treatment.
Fu J., Bowden R.L., Jagadish S.V, & Prasad P.V. (2023). Genetic variation for terminal heat stress tolerance in winter wheat. Frontiers in Plant Science, 14, 1132108.
Publication 2023
Chlorophyll Heat Stress Disorders Plant Leaves SPAD
3
Measuring Chlorophyll Content in Leaves
Third leaves from the top of the stem were sampled to determine the chlorophyll content on day 9. The chlorophyll contents were measured by a chlorophyll meter (SPAD-502, Minolta Co., Japan) and were represented as SPAD values.
Gururani M.A., Atteya A.K., Elhakem A., El-Sheshtawy A.N, & El-Serafy R.S. (2023). Essential oils prolonged the cut carnation longevity by limiting the xylem blockage and enhancing the physiological and biochemical levels. PLOS ONE, 18(3), e0281717.
Publication 2023
Chlorophyll Chlorophyll A SPAD Stem, Plant
4
Measuring Leaf Chlorophyll Content
The relative chlorophyll content of the leaves was measured by a SPAD chlorophyll meter (Apogee chlorophyll content meter). The measurements were done on the adaxial surface of the first and second true leaves in a single plant in five points uniformly distributed throughout the leaves and the average values were taken for analysis. The average value of two leaves was used to estimate the chlorophyll content. Chlorophyll was measured in CCI units. The CCI values of the instrument ranges from 1 to 100.
Hongal D.A., Raju D., Kumar S., Talukdar A., Das A., Kumari K., Dash P.K., Chinnusamy V., Munshi A.D., Behera T.K, & Dey S.S. (2023). Elucidating the role of key physio-biochemical traits and molecular network conferring heat stress tolerance in cucumber. Frontiers in Plant Science, 14, 1128928.
Publication 2023
Chlorophyll Chlorophyll A SPAD
5
Quantification of Leaf Biochemical Markers
The chlorophyll content of leaves was determined using the SPAD meter as described previously (Naus et al., 2010 (link); Ling et al., 2011 (link)). MDA content was measured via the thiobarbituric acid method (Castrejón and Yatsimirsky, 1997 (link)). The activity of SOD and CAT was assayed following the method described by García-Triana (García-Triana et al., 2010 (link)) and Zhao and Shi (Zhao and Shi, 2009 (link)), respectively. POD activity was measured as described in a previous report (Wang et al., 2014 (link)). Free proline content was determined based on the spectrophotometric method described by Vieira (Vieira et al., 2010 (link)). Soluble sugar content was determined using the anthranone reagent (Bodelón et al., 2010 (link)). Finally, soluble protein content was measured by the coomassie brilliant blue G-250 (Lowry et al., 1951 (link)).
Wang X., Wang M., Yan G., Yang H., Wei G., Shen T., Wan Z., Zheng W., Fang S, & Wu Z. (2023). Comparative analysis of drought stress-induced physiological and transcriptional changes of two black sesame cultivars during anthesis. Frontiers in Plant Science, 14, 1117507.
Publication 2023
brilliant blue G Carbohydrates Chlorophyll Proline Proteins SPAD Spectrophotometry thiobarbituric acid

Top products related to «SPAD»

1
Spad 502 by Konica Minolta
Sourced in Japan, United States, United Kingdom, Germany
The SPAD-502 is a portable, hand-held spectrophotometer designed to measure the Soil Plant Analysis Development (SPAD) index, which is a relative measure of leaf chlorophyll content. It provides quick and non-destructive measurements of leaf greenness or chlorophyll concentration in plants.
2
Spad 502 plus by Konica Minolta
Sourced in Japan, United States, Germany
The SPAD-502 Plus is a portable device used to measure the chlorophyll content of plant leaves. It utilizes optical sensors to analyze the light absorption characteristics of the leaf, providing a numerical value that corresponds to the chlorophyll concentration.
3
Spad 502 chlorophyll meter by Konica Minolta
Sourced in Japan, United States, United Kingdom
The SPAD-502 chlorophyll meter is a portable device designed to measure the relative chlorophyll content in plant leaves. It operates by emitting light at specific wavelengths and detecting the transmitted light, providing a numerical value that corresponds to the chlorophyll concentration in the measured leaf area.
4
Spad 502 plus chlorophyll meter by Konica Minolta
Sourced in Japan, United States, United Kingdom
The SPAD-502 Plus chlorophyll meter is a portable device designed to measure the relative chlorophyll content in plant leaves. It provides a non-destructive way to assess the overall health and nitrogen status of plants.
5
Li 6400 by LI COR
Sourced in United States
The LI-6400 is a portable photosynthesis system designed for measuring gas exchange in plants. It is capable of measuring net carbon dioxide and water vapor exchange, as well as environmental conditions such as temperature, humidity, and light levels.
6
Spad 502 meter by Konica Minolta
Sourced in Japan, United States
The SPAD-502 meter is a portable device designed to measure the relative chlorophyll content in plant leaves. It provides a non-destructive and rapid assessment of chlorophyll concentration, which is an important indicator of plant health and growth. The device features a compact and lightweight design for convenient field use.
7
Li 6400xt by LI COR
Sourced in United States, Germany, United Kingdom
The LI-6400XT is a portable photosynthesis system designed for measuring gas exchange in plants. It is capable of measuring net photosynthesis, transpiration, stomatal conductance, and other physiological parameters. The system consists of a control unit and a leaf chamber that encloses a portion of a plant leaf.
8
Minolta spad 502 by Konica Minolta
Sourced in Japan
The Minolta SPAD-502 is a handheld device designed for measuring the relative chlorophyll content in leaves. It utilizes non-destructive optical measurement technology to provide quick and accurate readings. The device is intended for use in various applications where the assessment of plant health and vigor is important.
9
Spad 502 plus chlorophyll meter by Spectrum Technologies
Sourced in United States
The SPAD 502 Plus Chlorophyll Meter is a portable device that measures the relative amount of chlorophyll in plant leaves. It provides a non-destructive method for assessing the chlorophyll content of plants.
10
Picoharp 300 by PicoQuant
Sourced in Germany
The PicoHarp 300 is a time-correlated single-photon counting (TCSPC) module for time-resolved measurements. It provides high-resolution time-tagging of detected photons with a time resolution of up to 1 picosecond. The PicoHarp 300 is capable of recording photon arrival times with respect to a reference signal, enabling time-resolved fluorescence and phosphorescence measurements.

More about "SPAD"