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Photon Counting - Fundamentals and Applications || Detectors for Super-Resolution & Single-Molecule Fluorescence Microscopies
摘要： The resolution of light microscopy was thought to be limited to 250–300 nanometers based on the work of Ernest Abbe. This Abbe diffraction limit was believed to be insurmountable until the invention of Super-resolution microscopic techniques in the late 20th century. These techniques remove this limit and have provided unprecedented detail of cellular structures and dynamics down to several nanometers. An emerging goal in this field is to quantitatively measure individual molecules. Measurement of single-molecule dynamics, such as diffusion coefficients and complex stoichiometries, can be accomplished using fluorescence fluctuation techniques to reveal nanosecond-to-microsecond temporal reactions. These powerful complimentary experimental approaches are made possible by sensitive low-light photodetectors. In this chapter, an overview of the principles of super-resolution and single-molecule microscopies are provided. The different types of photodetectors employed in these techniques are explained. In addition, the advantages and disadvantages for these detectors are discussed, as well as the development of next generation detectors. Finally, example super-resolution and single-molecule cellular studies that take advantage of these detector technologies are presented.
关键词： biophysical techniques,STORM,nanoscopy,STED,protein dynamics,palm,spectroscopy,molecular brightness,fluorescence fluctuation
更新于2025-09-23 15:23:52
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Specialty probes give super-res imaging that special blink
摘要： Fluorescent probes light the way to cellular detail, but light can also get in the way. Because of the diffraction limit, structures closer to one another than 200 nanometers (nm) or so cannot be discerned. Unless you use probes with super-resolution imaging. These techniques, such as reversible saturable optical linear fluorescence transitions (RESOLFT) or photoactivated localization microscopy (PALM)/stochastic optical reconstruction microscopy (STORM), use specialty probes, dyes and fluorescent proteins (FPs) that can switch from dark to light and from one color to another. 'We need the labels in combination with the microscope to overcome the diffraction barrier,' says Stefan Jakobs, who develops probes at University Medical Center G?ttingen and the Max Planck Institute for Biophysical Chemistry. In structured illumination microscopy (SIM), labs routinely achieve 100-nm resolution, he says. Scientists using stimulated emission depletion microscopy (STED), RESOLFT, PALM or STORM reach beyond 50-nm resolution. In principle, he says, the methods are diffraction unlimited.
关键词： STORM,STED,RESOLFT,super-resolution imaging,SIM,fluorescent probes,diffraction limit,PALM
更新于2025-09-23 15:21:21
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Quantifying the Oligomeric States of Membrane Proteins in Cells through Super-Resolution Localizations
摘要： Transitions between different oligomeric states of membrane proteins are essential for proper cellular functions. However, the quantification of their oligomeric states in cells is technically challenging. Here we developed a new method to quantify oligomeric state(s) of highly-expressed membrane proteins using the probability density function of molecule density (PDFMD) calculated from super-resolution localizations. We provided the theoretical model of PDFMD, discussed the effects of protein concentration, cell geometry and photophysics of fluorescent proteins on PDFMD, and provided experimental criteria for proper quantification of oligomeric states. This method was further validated using simulated single-molecule fluorescent movies, and applied to two membrane proteins, UhpT and SbmA in E. coli. The study shows that PDFMD is useful in quantifying oligomeric states of membrane proteins in cells that can help in understanding cellular tasks. Potential applications to proteins with higher oligomeric states under high concentration and limitation of our methodology were also discussed.
关键词： PALM,Photophysics,Protein concentration,Cell geometry,Single molecule
更新于2025-09-23 15:21:01
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Classification of Oil Palm Fresh Fruit Bunches (FFB) Using Raman Spectroscopy
摘要： The current practice in determining oil palm fresh fruit bunches (FFB) ripeness is by its colour which could be inaccurate. This study investigates the classification of oil palm FFB ripeness using Raman spectroscopy. A feature extraction model is developed based on the different organic compositions that contribute to the ripeness classification. Samples are collected according to the Malaysian Palm Oil Board (MPOB) standards which are unripe, underripe, ripe, overripe, and rotten. Different characteristics of the Raman shift were detected which represent the material composition for each sample. The Raman intensity of the oil palm fruit increases from unripe to ripe before decreasing to rotten due to the carotenoid content in the fruit. In conclusion, Raman spectroscopy is a suitable technique to observe the changes in the composition of oil palm fruit classified by its ripeness.
关键词： oil palm fruit,Raman spectroscopy,carotenoids,ripeness
更新于2025-09-23 15:21:01
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Blue luminescence carbon quantum dots derived from oil palm empty fruit bunch biomass
摘要： Carbon quantum dots (CQDs) have attracted tremendous attention for their interesting properties such as excellent chemical and photo stability, good water dispersibility, biocompatibility and possessing outstanding photoluminescence (PL) properties. In this study, oil palm biomass is used as the carbon precursor to produce CQDs and exhibit high luminescent properties. However, a large amount of biomass produces by the oil palm industry is either burnt in the open air or disposed in waste ponds and contributes to global climate change via emissions of carbon dioxide and methane. Hence, synthesis the CQDs from oil palm biomass by hydrothermal treatment method has formed excellent properties in optical properties that could be comparable to semiconductor quantum dots. The results have shown the diameter size of CQDs in the range of 2-5 nm. While, the optical properties, UV-vis spectrum of CQDs have given a strong absorption at 282 nm and obtains in brown color under visible light and emitting blue luminescence under 365 nm of UV lamp. Furthermore, PL spectra of CQDs have shown excitation and emission wavelength at 360 nm and 450 nm, respectively. This is attribute to the excitation-wavelength dependent of PL properties. Hence, the spectra from FTIR showed the existence of hydroxyl and carboxyl groups on the CQDs would have originated from lignocellulosic materials, thus resulted in excellent water stability and solubility properties of CQDs. The presented study is the green approached reprocessed biomass from waste to materials with excellent optical properties that could utilize in various field of applications.
关键词： hydrothermal treatment,photoluminescence,optical properties,Carbon quantum dots,oil palm biomass
更新于2025-09-23 15:19:57
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Therapeutic Ultrasound and Photobiomodulation Applied on the Palm of Hands: A New Treatment for Fibromyalgia?A Man Case Study
摘要： Fibromyalgia is a chronic disorder put in the spotlight in the last decades. Known since the 1920s, the disease is described by multiple painful points, of heightened sensitivity to touch that prevails in women, and afflict 3% to 10% of worldwide population. Fibromyalgia affects skeletal muscles and soft tissues. However, although there is no joint pain. Pharmacological treatment consists in analgesics and anti-inflammatory drugs to ease the pain. In addition, antidepressants, anxiolytics and anticonvulsants can be prescribed to control pain crises. Non-pharmacological approaches as therapeutic ultrasound and photobiomodulation are an alternative for pain relief. Recently, the synergic action of therapeutic ultrasound and photobiomodulation has emerged as an alternative to treat fibromyalgia in women when applied at the palm of hands. The success of the treatment is attributed to stimulation of neuroreceptors close to blood vessels located at the palm of hands and found to be in higher incidence in fibromyalgic patients when compared to healthy patients. This study aimed to evaluate the synergic effect of therapeutic ultrasound and photobiomodulation applied to the palm of hands of a fibromyalgic man patient. Evaluation was based on Quality Life Questionnaire (SF-36) and Visual Analogue Scale (VAS). Results show the treatment could improve the patient’s quality of life (SF-36) and reduce pain (VAS), indicating a new therapeutic approach to treat chronic disorders like fibromyalgia, reducing pain and increasing quality of life of fibromyalgic patients.
关键词： Therapeutic ultrasound,Palm of hands,Photobiomodulation,Fibromyalgia,Ultra-laser
更新于2025-09-19 17:15:36
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3a??Hydroxypicolinic Acid as an Effective Matrix for Sophorolipid Structural Elucidation Using Matrixa??Assisted Laser Desorption Ionization Timea??ofa??Flight Mass Spectrometry
摘要： Determination of the distribution of sophorolipid (SL) congeners controls their self-assembly structures and therefore their employment as glycolipid biosurfactants in cosmetics, environmental remediation, and personal care applications. The compatibility of 3-hydroxypicolinic acid (HPA) as a matrix for compositional analysis of SL using palm olein as carbon energy source by matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) analysis under positive and negative ion modes is studied in this work. Examination in positive ion mode revealed ions that were not detected in negative ion mode. Molecular ions produced using HPA matrix were lactonic Glc-Glc-10,400-C18:1, anionic Glc-Glc-10-C18:1, lactonic monoacetate of Glc-Glc-10,400-C18:1, and anionic monoacetate Glc-Glc-10-C18:1 and the anionic diacetate of also detected Glc-Glc-10-C18:0, Glc-Glc-10-C18:1. We GlcOAc-Glc-10-C18:0, GlcOAc-GlcOAc-10,400-C18:0, and GlcOAc—GlcOAc-10-C18:0 which are congeners of SL with stearic acid moieties. 3-HPA has been established to be the superior matrix for elucidation of structures for SL using MALDI-TOF MS.
关键词： Biosurfactant,Palm oil,3-Hydroxypicolinic acid,MALDI-TOF MS,Sophorolipids
更新于2025-09-19 17:13:59
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Analysis of Changes in Oil Palm Canopy Architecture From Basal Stem Rot Using Terrestrial Laser Scanner
摘要： Basal stem rot (BSR), caused by the Ganoderma fungus, is an infectious disease that affects oil palm (Elaeis guineensis) plantations. BSR leads to a significant economic loss and reductions in yields of up to Malaysian Ringgit (RM) 1.5 billion (US$400 million) yearly. By 2020, the disease may affect ~1.7 million tonnes of fresh fruit bunches. The plants appear symptomless in the early stages of infection, although most plants die after they are infected. Thus, early, accurate, and nondestructive disease detection is crucial to control the impact of the disease on yields. Terrestrial laser scanning (TLS) is an active remote-sensing, noncontact, cost-effective, precise, and user-friendly method. Through high-resolution scanning of a tree’s dimension and morphology, TLS offers an accurate indicator for health and development. This study proposes an efficient image processing technique using point clouds obtained from TLS ground input data. A total of 40 samples (10 samples for each severity level) of oil palm trees were collected from 9-year-old trees using a ground-based laser scanner. Each tree was scanned four times at a distance of 1.5 m. The recorded laser scans were synched and merged to create a cluster of point clouds. An overhead two-dimensional image of the oil palm tree canopy was used to analyze three canopy architectures in terms of the number of pixels inside the crown (crown pixel), the degree of angle between fronds (frond angle), and the number of fronds (frond number). The results show that the crown pixel, frond angle, and frond number are significantly related and that the BSR severity levels are highly correlated (R2 = 0.76, P < 0.0001; R2 = 0.96, P < 0.0001; and R2 = 0.97, P < 0.0001, respectively). Analysis of variance followed post hoc tests by Student–Newman–Keuls (Newman–Keuls) and Dunnett for frond number presented the best results and showed that all levels were significantly different at a 5% significance level. Therefore, the earliest stage that a Ganoderma infection could be detected was mildly infected (T1). For frond angle, all post hoc tests showed consistent results, and all levels were significantly separated except for T0 and T1. By using the crown pixel parameter, healthy trees (T0) were separated from unhealthy trees (moderate infection [T2] and severe infection [T3]), although there was still some overlap with T1. Thus, Ganoderma infection could be detected as early as the T2 level by using the crown pixel and the frond angle parameters. It is hard to differentiate between T0 and T1, because during mild infection, the symptoms are highly similar. Meanwhile, T2 and T3 were placed in the same group, because they showed the same trend. This study demonstrates that the TLS is useful for detecting low-level infection as early as T1 (mild severity). TLS proved beneficial in managing oil palm plantation disease.
关键词： Ganoderma,LiDAR,crown,frond,oil palm architecture
更新于2025-09-11 14:15:04
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Use of a new agricultural product as thermal insulation for solar collector
摘要： Sources of clean energy are becoming increasingly common, and the use of solar thermal energy has also been rising. This paper presents a solar air heater designed with a vegetable material as insulating material, date palm wood, widespread in tropical and saharan countries for use in drying. The study focuses on the comparative thermal performance of this collector and another collectors identical in design, fabrication, and operating under the same conditions, using glass wool as heat insulation. The thermal efficiencies of differents insulators collectors were performed : a) insulator with Petiole Piece, b) insulator with Fibers Piece, c) insulator with Petiole powder, d) insulator with Fibers powder, e) insulator with Petiole + gypsum, f) insulator with Fibers + gypsum insulatin and collector with glass wool insulation were evaluated and graphs were plotted. The final resuls showed that thermal efficiencies of date palm wood (Petiole + gypsum) insulated collector was 37.7 % higher than glass wool insulated collector. The average outlet air temperature of glass wool insulated was 7 % lower than Petiole + gypsum insulated collector. Hence the date palm wood is a good candidate for the development of efficient and safe insulating materials.
关键词： Solar collector,date palm petiole,thermal insulation,gypsum,date palm fibers,glass wool
更新于2025-09-10 09:29:36
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Preparation of Nb2O5-decorated hierarchical porous ZnO microspheres with enhanced photocatalytic degradation of palm oil mill effluent
摘要： In the present work, Nb2O5-decorated hierarchical porous ZnO microspheres (ZnO/Nb2O5) were successfully prepared through a facile surfactant-free method. The as-prepared samples were characterized by X-ray diffraction, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, UV–Vis diffuse reflectance spectroscopy, photoluminescence spectroscopy and Brunauer–Emmett–Teller surface area analyses. Under UV light irradiation, the ZnO/Nb2O5 composites degraded palm oil mill effluent (POME) efficiently and demonstrated much higher photocatalytic activity compared to those of pure ZnO and Nb2O5. The enhanced photocatalytic degradation performance of ZnO/Nb2O5 composites was attributed to the high charge separation efficiency and hydroxyl radical generation ability as verified by the photoluminescence spectra. Phytotoxicity test upon the POME degradation over ZnO/Nb2O5 photocatalysis considerably decreased through the measurement of radicle lengths of Vigna radiata. Moreover, the ZnO/Nb2O5 composites were reused several times without appreciable loss of activity. This work revealed that the as-prepared ZnO/Nb2O5 composites have great potential for practical applications in the field of wastewater treatment.
关键词： Nb2O5-decorated hierarchical porous ZnO microspheres,Photocatalytic degradation,Charge separation efficiency,Palm oil mill effluent,Hydroxyl radical generation
更新于2025-09-10 09:29:36