scholarly journals A novel pollen-tracking method: using quantum dots as pollen labels

2018 ◽  
Author(s):  
Corneile Minnaar ◽  
Bruce Anderson
Keyword(s):  
Quantum Dots ◽  
Oleic Acid ◽  
Quantum Dot ◽  
Uv Light ◽  
Semiconductor Nanocrystals ◽  
Bright Light ◽  
Pollen Grains ◽  
Pollen Grain ◽  
Pollen Transport ◽  
History Of

ABSTRACTTo understand the evolution of flowers and mating systems in animal-pollinated plants, we have to directly address the function for which flowers evolved—the movement of pollen from anthers to stigmas. However, despite a long history of making significant advances in our understanding natural selection and evolution, the field of pollination biology has largely studied pollen movement indirectly (e.g., pollen analogues or paternity assignment to seeds) due to a lack of suitable pollen tracking methods. Here, we develop and test a novel pollen-tracking technique using quantum dots as pollen-grain labels. Quantum dots are semiconductor nanocrystals so small in size that they behave like artificial atoms. When exposed to UV light, they emit extremely bright light in a range of different colours. Their photostability, broad excitation range, and customisable binding-li-gands make quantum dots ideal bio-labels. We tested the suitability of CuInSexS2-x/ZnS (core/shell) quantum dots with oleic acid (zinc-oleate complex) ligands as pollen-grain labels. We found that quantum dots attach to pollen grains of four different species even after agitation in a polar solvent, suggesting that the oleic acid ligands on quantum dots bind to pollenkitt surrounding pollen grains. We also showed that most pollen grains within anthers of the same four species are labelled with quantum dots after applying sufficient quantum-dot solution to anthers. To test whether quantum-dot pollen-labels influenced pollen transport, we conducted pollen transfer trials on Sparaxis villosa (Iridaceae) using captively reared honeybees. We found no difference in pollen transport between labelled and unlabelled pollen grains. Our experiments therefore demonstrate the potential for quantum dots to be used as easily applied pollen labels, which allow subsequent tracking of the fates of pollen grains in the field. The ability to track pollen grain movement in situ, may finally allow us to address an historically neglected aspect of plant reproductive ecology and evolution.

Employing Photo-Assisted Ligand Exchange Technique in Layered Quantum Dot LEDs

2011 ◽  
Vol 1286 ◽  
Author(s):  
Wenjia Hu ◽  
Shuai Gao ◽  
Paras N. Prasad ◽  
Jingkang Wang ◽  
Jian Xu
Keyword(s):  
Quantum Dots ◽  
Oleic Acid ◽  
Quantum Dot ◽  
Ligand Exchange ◽  
Light Emitting Diodes ◽  
Light Emitting ◽  
Exchange Technique ◽  
Ligand Replacement

AbstractWe presented in this paper a photo-assisted ligand exchange approach whereby light will be introduced to facilitate the replacement of oleic acid (OA) ligand molecules over PbSe quantum dots (QDs). The ligand-exchanged QDs were used to fabricate quantum dot light-emitting-diodes (QD-LEDs), which outperform the devices comprising the QDs without ligand-replacement.

Quantum Dot-Sensitized Solar Cells via Integrated Experimental and Modeling Study

2019 ◽  
Vol 16 (2) ◽  
pp. 436-440
Author(s):  
Lekshmi Gangadhar ◽  
Anusha Kannan ◽  
P. K. Praseetha
Keyword(s):  
Quantum Dots ◽  
Solar Cells ◽  
Solar Cell ◽  
Quantum Dot ◽  
Low Cost ◽  
Semiconductor Nanocrystals ◽  
Green Energy ◽  
Research Areas ◽  
Sensitized Solar Cells ◽  
Modeling Study

The solar energy is one of the potential renewable green energy source considering the availability of sunlight in abundance and the need for clean and renewable source of energy. Quantum dots are semiconductor nanocrystals having considerable interest in photovoltaic research areas. Cadmium sulfide-sensitized solar cells are synthesized by Chemical bath deposition and titanium nanowires were fabricated by hydrothermal method. The synthesized CdS quantum dots are sensitized to nanoporous TiO2 films to form quantum dots-sensitized solar cell applications. The introduction of TNWs enables the electrolyte to penetrate easily inside the film which increases the interfacial contact between the nanowires, the quantum dots and the electrolyte results in improvement in efficiency of solar cell. The goal of our research is to understand the fundamental physics and performance of quantum dot-sensitized solar cells with improved photoconversion efficiency at the low cost based on selection of TiO2 nanostructures, sensitizers and electrodes through an integrated experimental and modeling study.

scholarly journals Employing Photoassisted Ligand Exchange Technique in Layered Quantum Dot LEDs

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Wenjia Hu ◽  
Shuai Gao ◽  
Paras N. Prasad ◽  
Jingkang Wang ◽  
Jian Xu
Keyword(s):  
Quantum Dots ◽  
Oleic Acid ◽  
Quantum Dot ◽  
Ligand Exchange ◽  
Light Emitting Diodes ◽  
Light Emitting ◽  
Exchange Technique ◽  
Ligand Replacement

We presented in this paper a photoassisted ligand exchange approach whereby light will be introduced to facilitate the replacement of oleic acid (OA) ligand molecules over PbSe quantum dots (QDs). The ligand-exchanged QDs were used to fabricate quantum dot light-emitting-diodes (QD-LEDs), which outperform the devices comprising the QDs without ligand-replacement.

scholarly journals Quantum dot probes for cellular analysis

2017 ◽  
Vol 9 (18) ◽  
pp. 2621-2632 ◽  
Author(s):  
Dahai Ren ◽  
Bin Wang ◽  
Chen Hu ◽  
Zheng You
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Semiconductor Nanocrystals ◽  
Pivotal Role ◽  
Biological Applications ◽  
Cellular Analysis

Highly fluorescent and robust semiconductor nanocrystals (known as quantum dots or QDs) play a pivotal role in biological applications.

Applied to anti-counterfeiting and flexible composite utilizing photoluminescence properties of CdSe/ZnS nanocrystal quantum dots via hot-injection

2021 ◽  
Vol 11 (9) ◽  
pp. 1554-1560
Author(s):  
Jae Yong Jung ◽  
Soung Soo Yi
Keyword(s):  
Quantum Dots ◽  
Uv Light ◽  
Quantum Confinement Effect ◽  
Bright Light ◽  
Bank Note ◽  
Wide Range ◽  
Hot Injection ◽  
Nanocrystal Quantum Dots ◽  
Bio Imaging ◽  
Silicon Based

Quantum dots with excellent luminescence properties are being studied in a wide range of fields, such as displays, sunlight, and bio-imaging; although quantum dots are the same material, unlike bulk materials, as their size decreases their optical and electrical properties change due to the quantum confinement effect. In this study, CdSe quantum dots were synthesized by a well-known hot-injection method and a ZnS shell layer was formed on the surface of the CdSe quantum dot core to enhance the properties, thereby synthesizing the CdSe/ZnS core/shell structure. At this time, the quantum yield increased more than twice, and the emission line width decreased. When anti-counterfeiting ink was made using quantum dots with enhanced luminescence characteristics and applied to a bank note, it was impossible to check with the naked eye, but letters and emblems could be confirmed under UV light. In addition, a composite made by mixing with a silicon-based polymer showed excellent flexibility; and, when applied on a blue LED chip, a single wavelength and bright light peculiar to quantum dots were realized.

White Light Emitting CdS Quantum Dot Devices Coated with Layers of Graphene Carbon Quantum Dots

MRS Advances ◽  
2020 ◽  
Vol 5 (63) ◽  
pp. 3337-3343
Author(s):  
O. Deodanes ◽  
J. C. Molina ◽  
C. Violantes ◽  
D. Pleitez ◽  
J. Cuadra ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
White Light ◽  
Polyester Resin ◽  
Uv Light ◽  
Resin Matrix ◽  
Light Emitting ◽  
Quenching Effect ◽  
Cds Qds ◽  
Low Efficiency

AbstractCadmium sulfide quantum dots (CdS QDs) are semiconductor nanoparticles having sizes in the order of nanometers. They are materials that have outstanding properties for down conversion applications. These nanostructures have been used in the fabrication of white light emitting diodes (WLEDs) in the last years. However, inhomogeneous deposition of CdS QD conversion materials allows unwanted UV light escape. In addition, low efficiency due to strong self-quenching effect, incompatibility between CdS QD solution/crystal polyester resin matrix and reabsorption are common problems that need to be solved. In this work, we try to address the incompatibility between the CdS QD solution/crystal polyester resin matrix by using a solvent exchange procedure. To block the unwanted UV-light escape, we coated our devices with a mixture of graphene carbon quantum dot (GCQD) solution/crystal polyester resin matrix. The QDs and the WLED prototypes were characterized by absorption and photoluminescence (PL) spectroscopy. The QDs embedded in the matrix shown a good homogeneous dispersion. On the other hand, the mixture shown a rapid solidification. These facts indicate a good compatibility between the CdS QDs and the crystal polyester resin. We also observed a considerable reduction of unwanted near UV-light. White light emission from WLED devices with common crystal polyester resin and low-cost materials has been achieved.

SYNTHESIS OF NANOCRYSTALLINE CdS QUANTUM DOTS VIA PARAFFIN LIQUID AS SOLVENT AND OLEIC ACID AS THE REACTING MEDIA

2012 ◽  
Vol 11 (06) ◽  
pp. 1240038 ◽  
Author(s):  
WENJIANG LI ◽  
MINGRUI WANG ◽  
FEI XIE ◽  
SHA ZHU ◽  
YUE ZHAO
Keyword(s):  
Quantum Dots ◽  
Oleic Acid ◽  
Semiconductor Nanocrystals ◽  
Emission Spectra ◽  
Medical Diagnostics ◽  
X Ray Diffraction ◽  
Hrtem Observation ◽  
Average Grain Size ◽  
Cds Qds ◽  
Paraffin Liquid

Fluorescent semiconductor nanocrystals have been widely used as fluorescent materials in chemical sensors, biotechnology, medical diagnostics, biological imaging and many other fields. Compared to the conventional organic fluorophores, the inorganic quantum dots (QDs) have many advantages, including broad absorption spectra, narrow emission spectra, good photostability and long fluorescent lifetime after excitation. Here, the high quality CdS QDs were synthesized directly from sulfur and CdO using the paraffin liquid as solvent and the oleic acid as the reacting media. The synthesized CdS QDs with a zinc blende (cubic) crystal structure were proved by X-ray diffraction. HRTEM observation revealed that the CdS QDs were uniform and the average grain size was about 4 nm. The optical properties of the CdS QDs were characterized by using photoluminescence (PL) spectrophotometer and Ultraviolet-visible (UV-Vis) absorption spectrophotometer. The formation mechanism of CdS QDs in the paraffin liquid and oleic acid system was proposed.

scholarly journals Highly Responsive Ultraviolet Sensor Based on ZnS Quantum Dot Solid with Enhanced Photocurrent

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Sellan Premkumar ◽  
Devaraj Nataraj ◽  
Ganapathi Bharathi ◽  
Subramaniam Ramya ◽  
T. Daniel Thangadurai
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Uv Radiation ◽  
Uv Light ◽  
Fast Response ◽  
Average Lifetime ◽  
Synthesis Conditions ◽  
Efficient Detection ◽  
Visible Blind ◽  
Better Than

AbstractDetection of visible blind UV radiation is not only interesting but also of technologically important. Herein, we demonstrate the efficient detection of UV radiation by using cluster like ZnS quantum dot solid nanostructures prepared by simple reflux condensation technique. The short-chain ligand 3-mercaptopropionic acid (MPA) involved in the synthesis lead to the cluster like formation of ZnS quantum dots into solids upon prolonged synthesis conditions. The ZnS QD solid formation resulted in the strong delocalization of electronic wave function between the neighboring quantum dots. It increases the photocurrent value, which can be further confirmed by the decrease in the average lifetime values from 64 to 4.6 ns upon ZnS cluster like QD solid formation from ZnS QDs. The ZnS quantum dot solid based UV sensor shows good photocurrent response and a maximum responsivity of 0.31 (A/W) at a wavelength of 390 nm, is not only competitive when compared with previous reports but also better than ZnS and metal oxide-based photodetectors. The device exhibits a high current value under low-intensity UV light source and an on/off ratio of IUV/Idark = 413 at zero biasing voltage with a fast response. Further, photocurrent device has been constructed using ZnS quantum dot solid nanostructures with graphene hybrids as an active layer to improve the enhancement of photoresponsivity.

GaN quantum dot UV light emitting diode

2003 ◽  
Vol 798 ◽  
Author(s):  
Jeong-Sik Lee ◽  
Satoru Tanaka ◽  
Peter Ramvall ◽  
Hiroaki Okagawa
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Active Layer ◽  
Room Temperature ◽  
Uv Light ◽  
Light Emitting Diode ◽  
Current Injection ◽  
High Density ◽  
Light Emitting ◽  
Room Temperature Luminescence

ABSTRACTThe fabrication and evaluation of a UV light-emitting diode (LED) incorporating GaN quantum dots as the active layer is demonstrated. The GaN quantum dots were fabricated on an AlxGa1-xN (x∼0.1) surface using Si as an antisurfactant. Exposing the AlxGa1-xN surface to the Si antisurfactant prior to GaN growth enabled the formation of quantum dots on a surface where growth by the Stranski-Krastanov mode would not be possible. A fairly high density of dots (1010-1011 cm-2) with controllable dot sizes was achieved. Room temperature luminescence at 360 nm was clearly observed during current injection (cw) into an LED structure including the GaN quantum dots. The origin of the electroluminescence is discussed by comparing it to photoluminescence measurements.

scholarly journals Pollen analysis of animal coprolites recovered from vegetation mounds in El-Ga’ab paleolake: evidence for vegetation history of the desert of northern Sudan

2021 ◽  
Vol 3 (1) ◽  
pp. 8-13
Author(s):  
Mohammed Nasreldein ◽  
◽  
Ikram Madani Ahmed ◽  
Yahia Fadl Tahir ◽  
◽  
...  
Keyword(s):  
Vegetation History ◽  
Sand Dunes ◽  
Pollen Grains ◽  
Pollen Grain ◽  
Arid Zones ◽  
Two Samples ◽  
Arable Fields ◽  
Moist Habitat ◽  
History Of ◽  
Acacia Ehrenbergiana

In arid zones vegetation mounds are natural indicators for land degradation. Studying plants and animals remains in different strata of these mounds provide information about the past land use in which parts of the natural environment were modified into arable fields and pastures. They are suitable sites for preserving animal coprolites. In this study, two samples of different animal coprolites were collected from vertical trenches in vegetation mounds of Um Hilal and El-Hamra areas of El-Ga’ab depression in northern Sudan. Pollen grain analysis was conducted and eleven species that belong to eight families were identified. Five species recorded for El Hamra area and nine species were identified for Um Hilal area. Most of the pollen grains were identified as Suaeda monoica and Salsola imbricata which are halophytes indicates habitats of high soil salinity in El-Ga’ab depression. These species are still dominant in other law elevated areas of less dry sand dunes. Polygonum sp. Pollens were recorded in Um Hilal area indicating a moist habitat. Record of the comparatively large number of tree pollen grain of Acacia ehrenbergiana indicates no change in the dominant tree species. Presence of the pollen grains of Triticum sp. (wheat) and Heliotropium parciflorum is an evidence for past agricultural activities. This study recommended further intensive investigations of the old dry vegetation mounds distributed in the desert of northern Sudan to reconstruct its palaeoenvironment.

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