-NH2 modified upconverting(yellow-green)
SKU: 29467763295

-NH2 modified upconverting(yellow-green)

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Description

-NH2 modified upconverting(yellow-green)Product Name Name: NH2 modified upconverting nanoparticlesyellow green light Product Overview Upconversion nanoparticles (UCNPs) are nanomaterials that can convert low energy light into high energy light. They are composed of inorganic nanocrystals doped with rare earth ions and have unique upconversion luminescence properties. Rare earth upconversion luminescence is based on the 4f electron transition of lanthanide rare earth ions. Currently, the

Product Name

Name: -NH2 modified upconverting nanoparticles(yellow-green light)

Product Overview

Upconversion nanoparticles (UCNPs) are nanomaterials that can convert low-energy light into high-energy light. They are composed of inorganic nanocrystals doped with rare earth ions and have unique upconversion luminescence properties. Rare earth upconversion luminescence is based on the 4f electron transition of lanthanide rare earth ions. Currently, the common upconversion luminescence mechanisms can be summarized into three types: excited state absorption, energy transfer upconversion, and photon avalanche.

The preparation methods of upconversion nanoparticles mainly include coprecipitation method, high-temperature pyrolysis method, hydrothermal method, solvothermal method, sol gel method, etc. In order to widely apply UCNPs in the biomedical field, in addition to improving luminescence efficiency, it is also necessary to functionalize their surfaces to enhance water solubility and biocompatibility, and achieve multifunctionality. The main surface modification methods include ligand exchange (PEG, PEI, etc. with - COOH, - NH2 groups), ligand oxidation, ligand adsorption, layer by layer self-assembly, and silica coating.

Most of the rare earth doped ions in the nuclear nanoparticles are exposed on the crystal surface, which is prone to non radiative energy transfer with the external environment, leading to fluorescence quenching and thus reducing the upconversion luminescence efficiency. The most commonly used method to reduce this quenching process is to wrap an inert shell layer on the surface of doped nanocrystals to form a core-shell structure, which confines the luminescent ions in the internal core. The shell layer increases the distance between the luminescent center ion and the external environment, effectively reducing energy transfer and thus increasing the luminescence efficiency. At present, the most commonly used method is to modify the shell layer in the previously synthesized nuclear layer structure that is the same as the matrix material, such as NaYF: Yb, Er@NaYF4 NaYF4: Yb, Tm@NaYF4.

Technical Parameter

Emission wavelength: 545/660 nm

Excitation wavelength: 975-980nm

Particle diameter: 35 nm

Main components: NaYREF4 (RE:Yb, Er) 

Product Features

Colorful luminescence: By changing the type and concentration of rare earth ions doped, multi-color luminescence from visible light to near-infrared light can be achieved.

Stokes shift is large: Stokes shift refers to the difference between the emission wavelength and the excitation wavelength. The Stokes shift of upconversion nanoparticles is relatively large, which can effectively reduce self absorption and background interference, improve luminescence efficiency and detection sensitivity.

Good photostability: Upconversion nanoparticles have good photostability and can maintain stable luminescence performance under long-term illumination.

Good biocompatibility: Through surface modification, upconversion nanoparticles can be coupled with biomolecules (such as proteins, antibodies, etc.) to achieve biological labeling and detection.

Non damaging to biological tissues: Its excitation light source near-infrared light (980nm or 808nm) has strong light penetration, almost no damage to biological tissues, and no background fluorescence.

Application Fields

Biomedical: Upconversion nanoparticles can serve as biomarkers for cell imaging, biological detection, drug delivery, and other applications. For example, coupling upconversion nanoparticles with antibodies or biomolecules can achieve targeted labeling and detection of specific cells or biomolecules.

Optical imaging: Upconversion nanoparticles can be used for deep tissue imaging, such as in vivo animal imaging. Due to its longer emission wavelength, it can penetrate deeper biological tissues, reduce tissue scattering and self fluorescence interference, and improve imaging clarity and contrast.

Photocatalysis: Upconversion nanoparticles can convert visible light into ultraviolet or near-infrared light, thereby broadening the spectral response range of photocatalytic materials and improving photocatalytic efficiency.

Solar cells: Upconversion nanoparticles can be used to improve the efficiency of solar cells. By combining upconversion nanoparticles with solar cell materials, low-energy photons can be converted into high-energy photons, increasing the absorption and utilization of solar light by the cell.

Related Information

Please e-mail for the detailed characterization data.

E-mail:[email protected] 

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SKU: 29467763295

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Geddes J
Boise, US
★★★★★ 4
Good History Book
Format: Kindle
Twenty years that change history and the Americas. Even though the civil war ended slavery at a humongous cost, it it failed to bring social justice a d civil rights to the population of the country. It was not until 1920 that women were granted voting rights. And some problems and divisions persist nowdays.
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Reviewed in the United States on July 2, 2024
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Ian R
Charlottesville, US
★★★★★ 5
interesting and fresh perspective on the American civil war
Format: Kindle
Fresh perspective on the well known American Civil War. I appreciate Dr Taylor’s emphasis on the preservation of slavery over the states’ rights argument for why the American Civil War was fought.
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Reviewed in the United States on June 1, 2024
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gloine36
Grantham, US
★★★★★ 5
A Masterpiece by the most Influential Historian of the 20th Century
Format: Paperback
The late Edmund Morgan may very well have been the most influential American historian of the 20th century. So much of what he wrote has had a definitive impact on the field of American history that he literally stands above the rest of his peers. Few historians can claim to have changed how we view the founding of America, and Morgan is one of that very select company. In American Slavery, American Freedom Morgan managed to alter the relationship of slavery to America. While he was primarily writing about colonial Virginia, he explored the issue of slavery and illustrated how the colonial Virginians used racism to develop the form of chattel slavery that rose here in the colonies during the 17th century. Often as we teach our history courses our students will invariably answer the question about why people came to the colonies with the statement, "People wanted to be free." Yet, we know from the records that most people who came to Virginia were anything but free. The facts are there and have always been there proving this, yet few speak about it because it conflicts with American heritage. Morgan shattered that illusion in this book. He showed that colonial Virginia was the exact opposite of freedom and that many people in the 17th century were forced to go there. In addition he showed how thousands of people died in Virginia from various causes during the first half of the century. He also investigated the role of class in colonial Virginia and how those in power sought to use the colonial government to retain that power for themselves and similar people. At times this ran contrary to what the English monarchs wanted in their colonies, but the upper class of Virginia managed to overcome obstacles and stay in power. Morgan did this by examining the records of the colony including the laws as they were enacted. He found that many laws were designed to help those with money at the expense of those without. He also found where the laws changed and became race conscious which he interpreted as the sign that the upper class was making a clear distinction between white and black in order to create the classic Us vs. Them division. This division would be the racist wedge used to keep poor whites of the lower class from associating with the blacks of any class and to reinforce the status of slavery on all blacks. This book won the Francis Parkman award and is regarded as an American history classic. One of the great things about Morgan was that his writing was wonderful and academic at the same time. Notes are given to the reader on each page via footnotes and reveal the great depth of research that Morgan used to develop this topic. It is a must read even today for anyone studying the history of Virginia. It is also a wonderful example of what a history book should be in its style and literary quality. Morgan's appendix does make one wonder what would have happened had he developed a quantification theory to go with his topic. The data results would probably have reinforced his conclusion. The appendix is an early use of that type of approach and shows that Morgan's conclusion would have been validated by quantification. All in all this book is a must read for any scholar of Virginia, colonial America, or slavery. Reading it will help the student develop a deeper contextual feeling for how colonial Virginia developed and a greater understanding as to why certain things in this country came about. The theme of racism has been existent in America for centuries and Morgan showed us exactly why that was. This book is a must have in my collection and many others for its high quality of research.
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Reviewed in the United States on October 9, 2013
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Wald1900
Charlottesville, US
★★★★★ 5
Fascinating Insights into the Origins of American Racism
Format: Paperback
This is a fantastic, must read book for anyone interested in the origins of American racism. Morgan recounts the cultural, economic and political evolution of the 17th and early 18th century Virginia, and with it, makes comprehensible the reasons why racial slavery emerged as an integral component to the development of the white community's pre-revolutionary ideals of independence and liberty. At the founding of the Jamestown colony in 1607, Virginia offered vast tracts of land available to anyone willing to make the trip and who could survive their first season (or two or three) in the New World. Unlike in England where opportunities for land ownership were constrained, the fact that Virginia land was to be had for the taking made the economic equation simple - more labor = more profits. To provide this labor, England's surplus poor (of which there was an overabundance) were sent to Virginia as indentured servants for a period of four to seven years in order to work off the costs of their relocation. Once their indenture period was over, they were free.....and poor. Over time, as established interests grabbed more and more of the land, opportunities for released bondsmen decrease, essentially creating an ever-growing class of destitute (and thoroughly despised) whites who threatened the social and political stability of the colony. Racial slavery was introduced over time to stem this proliferation of poor whites, who, after having served the term of their indenture, were free to be a "blight" on the community. These planter elites were also constantly at political war with a succession of governors appointed by the crown to manage the affairs of the colony in a manner most beneficial to the king. By enfranchising poor whites and enlisting their support for the colonial assembly, the elites were able to exercise political power over affairs of the colony in a manner most beneficial to the colonists, rich and poor alike. The result of these forces caused a major adjustment in white social strata - the role of detested poor who would only work under the threat of the lash was imposed upon enslaved blacks, and poor whites were elevated to the level of political partners with the elites. This simultaneously endowed all whites with a fierce sense of entitlement over their political rights and the prerogatives of power on the one hand, and contempt for their black slaves on the other. Liberty and equality came to be seen as inalienable birthrights while slavery was the means by which the "shiftless, lazy, indolent" poor could be transformed from burdens on society to positive (albeit brutally coerced) contributors. In other words, Virginia whites came to think of blacks with the same sense of scorn and contempt that English aristocrats held for the poor in England while, at the same time, assuming as a birthright the same sense of political entitlement enjoyed by the elite class in England. It was this, to our modern eyes, bizarre combination of egalitarian and tyrannical ideals that informed and inspired Jefferson, Washington and Madison (among others) as they participated in the formation of what would become the United States. The implication of this history on modern political discourse is obvious. Those who today passionately cite the liberty-loving ethos of the founding fathers while simultaneously exhibiting contempt for the poor are only looking at one side of the equation. For the Virginians, slavery and liberty went hand in hand; without the one there could not have been the other. A full, rich and nuanced understanding of our heritage compels us to recognize the human inclination to despise and exploit the powerless with the same vigor and passion that we celebrate the ennobling power of freedom. On a final note of criticism - while the book does a masterful job of making the origins of colonial racism comprehensible, it does so at the expense of "black experience" narratives. The story addresses issues of slavery only to the extent of discussing laws passed throughout the pre-revolutionary period in order to institutionalize it and the effect these laws had on the attitudes of whites towards blacks. I started the book expecting a far deeper dive in this area, and was disappointed by how little was presented concerning the evolution of slavery throughout the 17th century from a black perspective. After having read the book, I concede that this deeper dive was not strictly necessary in order for the author to prove his thesis, yet it would have been a stronger work had greater efforts in this area been made.
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Reviewed in the United States on February 23, 2013
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Reader KA
Boise, US
★★★★★ 5
Great Historical Reading
Format: Paperback
I found "American Slavery, American Freedom" to be a thought-provoking book that contained a great deal of useful information. I wrote in the margins of the book, took notes, and highlighted entire pages. "American Slavery, American Freedom" was well-written and enjoyable to read. I had read countless books on slavery over the years. This book did not focus primarily on slavery. A detailed description of the steps and events that led to the creation of the Commonwealth of Virginia can be found in "American Slavery, American Freedom." The history of Virginia is characterized by slavery and servitude. Since many of the books I had read on slavery lacked a compelling backstory, I found this book refreshing. As far as I can tell, the author denied or downplayed the fact that Thomas Jefferson fathered many children with a slave named Sally Hemmings. The author probably worked on this book for years before its publication in 1975. There was a possibility that Edmund Morgan did not want to write about any "touchy" topics. "American Slavery, American Freedom" was a pleasure to read. I would recommend it to others.
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Reviewed in the United States on September 30, 2020

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