Monday, January 27, 2020
Rare Earth Doped Upconverting Nanoparticles
Rare Earth Doped Upconverting Nanoparticles Rare Earth Doped Upconverting Nanoparticles: Synthesis and Application in Bio-Imaging Nidhi Malviya1, Vinita Rajput Chouhan1, Sudeshna Ray2 ABSTRACT Upconversion luminescence, a nonlinear process, which re-emits a photon at a shorter wavelength by the absorption of more than one photon, successively at longer wavelengths via long-lived intermediate energy states, is useful for important applications in various fields like fluorescence bio-imaging and lasers. This NIR-to-NIR up-conversion process provides deeper light penetration into biologicalspecimen and results in high contrast optical imaging due to absence of an auto fluorescence background and decreased light scattering. Excitation at long wavelengths also minimizes damage to biological materials. Herein, we report the different mechanisms responsible for the Upconversion process of rare-earth (Er3+, Ho3+, Tm3+) doped nanoparticle and methods that are used to synthesize and decorate up converting nanoparticle. I INTRODUCTION Upconversion is an optical process that involves the conversion of lower-energy photons into higher-energy photons. It has been extensively studied since mid-1960s and widely applied in optical devices. Over the past decade, high-quality rare earth-doped Upconversion Nanoparticles have been successfully synthesized with the rapid development of nanotechnology and are becoming more prominent in biological sciences. The main difference between Upconversion Nanoparticles and other nonmaterial’s is that they can emit visible light under near infrared irradiation. Upconversion nanoparticle (UCNPs), particularly lanthanide-doped nanocrystals, which emit high energy photons under excitation by the near-infrared (NIR) light, have found potential applications in many fields, including biomedicine and is found improved tissue penetration and higher photochemical stability as compared with traditional down-conversion fluorescence imaging. The unique Upconversion process of UCNPs may be u tilized to activate photosensitive therapeutic agents for applications in cancer treatment. Upconversion luminescence imaging in vivo is expected to be the next generation photoluminescence imaging technique since it provides high sensitivity and spatial resolution. Due to their multicolour emission, high brightness and long lifetime, lanthanide ions based luminescent nonmaterial have tremendous promise as indicators and photon sources for numerous application such as boilable, light-emitting devices, sensor technology, and low-threshold lasers. So it is very important to successfully prepare the rare-earth doped inorganic nanocrystals with good dispensability in organic solvents. The Up conversion phenomenon has been transition metals, actinides, but mainly in the rare earth elements, which contain the lanthanide (Ln) series, Yttrium, and scandium. Ln3+ ions heave special 4fn 5d0-1inner shell configurations that are well – shielded by outer shell and have unique energy level structures. These Ln3+ ions can exhibit sharp luminescence emission via intra-4f or 4f-5d transitions. Their luminescence properties, as narrow bandwidth, long-time emission, and anti-stokes emission, have been widely applied in lasers, solar cell, analytical sensors, optical imaging, and photodynamic therapy. Most fluorescent materials, including dye molecules, quantum dots, and dye-doped silica/gold nanomaterials, emit light by the down conversion process (emitting lower-energy photons under higher-energy irradiation). Although the uses of a conventional organic dye molecule or quantum dot (QD) based biomarker have achieved significant progress in real-time detection and bio imaging, they still have drawbacks. These fluorescent materials are generally excited by ultraviolet (UV) or visible light, which may induce auto fluorescence and photo damage to biological samples, resulting in low signal-to-noise ratio and limited sensitivity. These limitations prompted the development of a new type of high-quality and well-shaped nonmaterial’s known as up conversion nonmaterial’s (UCNs [1-7]. Lanthanide-doped Upconversion (UC) nanophosphors are promising optical contrast agents for biomedical applications due to their photo stability, sharp emission peaks, and long emission lifetime [8, 9]. Upon near infrared (NIR) excitation, UC nanoparticle exhibit intense visible emission via multiphoton processes involving the lanthanide ions within them [10-12]. For in vitro or in vivo imaging, the use of NIR excitation minimizes absorbance, scattering, and fluorescence from cells and tissues, allowing imaging against a dark background [13]. In contrast, commercially available labels, such as organic dyes and quantum dots, typically must be imaged against a background of Stokes-shifted tissue autofluorescence induced by UV, blue, or green excitation[14]. In addition, because of the existence of real intermediate energy levels in lanthanide ions, this Upconversion process can be much more efficient than in conventional multiphoton-absorption-induced fluorescence of organic dyes or qua ntum dots, where the intermediate levels are virtual. Bio-imaging is a term that covers the complex chain of acquiring, processing and visualizing structural or functional images of living objects or systems, including extraction and processing of image-related information. II MOTIVATION OF MY WORK Lanthanide-doped upconversion-luminescent nanoparticles (UCNPs), which can be excited by near-infrared (NIR) laser irradiation to emit multiplex light, have been proven to be very useful for in vitro and in vivo molecular imaging studies. In comparison with the conventionally used down-conversion fluorescence imaging strategies, the NIR light excited luminescence of UCNPs displays high photostability, low cytotoxicity, little background auto-fluorescence, which allows for deep tissue penetration, making them attractive as contrast agents for biomedical imaging applications. In this review, we will mainly focus on the latest development of a new type of lanthanide-doped UCNP material and its main applications for in vitro and in vivo molecular imaging and we will also discuss the challenges and future perspectives. New materials with high Biocompatibility and more intense emission spectra are needed to be developed so for deep tissue imaging. III CONCLUSION The past decade a large number of scientists have investigated the potential application of UCNPs in bioimaging. Lim et al. firstly reported the use of UCNPs as in vivo Caenorhabditis elegans imaging agent. Along with the fast developement of UCNPs for biological applications. UCNPs have also been applied contrasts agents in positron emission tomography (PET), magnetic resonance imaging (MRI), X-ray computer tomography (CT) for in vitro and in vivo multimodal imaging. Futhermore, UCNPs could also be combined with anti-cancer drugs, photosensitizers or gold nanostructures for potential therapeutic application. Up to now, a variety of Upconversion nanophosphors have been developed for bioimaging, and most of them are based on rare earth doped NaYF4. Other kinds of RE doped nanoparticles, such as NaGdF4, NaLaF4, Y2O3, GdF3, CeO2, LiNaF4, Ca3(PO4)2, ZrO2 and GdOF etc. have al so been considered as excellent UCNPs in recent years due to their strong Upconversion luminescence intensity an d good photostability. REFERENCES F. Auzel, Chem. Rev. 2004, 104, 139; F. Wang, X Liu, Chem. Soc. Rev. 2009, 38, 976; D. K. Chatterjee, M. K. Gnanasammandhan, Y. Zhang, Small 2010, 6, 278 M. Haase, H. Schafer, Angew. Chem. Int. Ed. 2011, 50, 5808. D. K. Chatterjee, A. J. Rufaihah, Y. Zhang, Biomaterials 2008, 29, 937 J. Zhou, Y. Sun, X. Du, L. Xiong, H. Hu, F. Li, Biomaterials 2010, 31, 3287; L. Xiong, T. Yang, Y. Yang, C. Xu, F. Li, Biomate rials 2010, 31, 7078. Wu SW, Han G, Milliron DJ, Aloni 8 S, Altoe V, Talapin DV, et al. Proceedings of the National Academy of Sciences of the United States of America. 2009; 106: 10917-21. doi:DOI 10.1073/pnas.0904792106. Mai H-X, Zhang Y-W, Si R, Yan Z-G, Sun L-d, You L-P, et al. J Am Chem Soc. 2006; 128: 6426. doi:10.1021/ja060212h. Boyer J-C, Cuccia LA, Capobianco JA. Nano Letters. 2007; 7: 847-52. doi:10.1021/nl070235 Heer S, Kà ¶mpe K, Gà ¼del HU, Haase M..Advanced Materials. 2004; 16: 2102-5. doi:10.1002/adma.200400772. Chen GY, Ohulchanskyy TY, Kumar R, Agren H, Prasad PN. ACS Nano. 2010; 4: 3163-8. doi:Doi 10.1021/Nn100457j. Nyk M, Kumar R, Ohulchanskyy TY, Bergey EJ, Prasad PN. Nano Letters. 2008; 8: 3834-8. doi:10.1021/nl802223f. Wang M, Mi CC, Wang WX, Liu CH, Wu YF, Xu ZR, et al.. ACS Nano. 2009; 3: 1580-6. doi:Doi 10.1021/Nn900491j.
Sunday, January 19, 2020
Reliving a Memory through a Successful Narration Essay
People weave hundreds of stories throughout the course of their lives. Most of them are experiences that brought fear, embarrassment or changes in their lives. More often than not, these stories are shared with other people in one way or another. Telling a story can be done through several ways. You can re-enact the scenario to tell a story. You can utter words that describe the incident or you simply can put words into writing to form a narration. Before you put your story into writing, there are two things that need to be done: visualizing and planning. Prior to writing your narration, you should visualize the story. You yourself should be able to relive the scene in your mind to help you in coming up with the right words to describe the scenario. Then, you should plan on how you going about your story. Each part of your story is preceded by another. You should be able to prepare on how you would relate the previous scenario to the current one. Once you have visualized and planned for your narration, you are now ready to put your story into writing. Writing a narration involves a series of steps that could help the writer create a vivid picture of his experiences in life. Only when the reader is able to form clear mental images of each scenario can the narration be considered successful. The first step involves choosing the important details. You should only emphasize on important points of your story. Minor details should simply be de-emphasized or removed entirely. If you are telling about the time you won the lottery, then you should not dwell into details about the dinner you had before find out your win. You should only give emphasis on your initial reaction, on the reaction of the people around you, and on how you planned to spend your winnings. The use of a chronological order comprises the next step. Oftentimes, the best stories are told in the order in which they occur. This order helps the reader better understand the story as it unfolds. Centering on conflict is what the third step tells the writer to do in order to weave a successful narrative. These conflicts may either deal with inner dilemmas or with another person. It may also include conflicts with an impersonal outside force. In each story revolving around a conflict, the resolution of the conflict marks the end of the story. Showing the reader what happened is the fourth step. It is usually better to give the readers a visualization of the significant moments in the narration rather than telling the story. You can do so by using a detailed description of the event and each character participating in that even. However, using a dialogue has the strongest effect on the reader that it does not only make the reader see what is happening. It also makes the reader feel the emotions in the story. The next step involves making a point. It is simply important to have a point that would rationalize the existence of your story. You should present your point using a sentence. Telling a story can be done in various forms. However, one of the most common forms involves writing. Putting your story into writing is simple however making it a successful narration entails extra work. In order come up with a vivid picture of your story, there are steps which could be followed to ensure that the reader do not only see but also feel the emotions in the story.
Saturday, January 11, 2020
Impact of Christianity on Philosophy Essay
Introduction Christianity’s doctrines and tenets draw from a rich heritage of long historical development. And since it is a religion shaped by history, it follows only that its teachings are influenced by the prevailing philosophies within it. But there are also good reasons to think that, conversely, Christianity is a religion that did not only draw from existing philosophies in history but also generated a significant impact on them. Three reasons may be cited to support this contention. First, philosophy was made popular by the rise of Christianity; second, key Christian thinkers have endeavored to incorporate philosophy within their belief-systems; and third, many of their teachings are actually philosophical issues Christianized in the process. Christianity and Philosophy            First, the rise of Christianity seems to be a factor responsible for the great interest many people have shown towards philosophy during the ancient times. It must be noted that even before Christianity as a religious movement was to be commenced (following the death of Jesus, and the rapid conversion to a belief in him), prevailing philosophies such as Epicureanism, Neo-Platonism, Stoicism, and Skepticism were already in place (Moore & Bruder, 2005, p. 77). But since the Romans – the political power of that time – showed little or no interest to these philosophies, they remained largely an undercurrent phenomenon. In many ways, the rise of Christianity paved the way for such philosophies to become widespread, as they are (specifically, Neo-Platonism and Aristotleanism) employed in many â€Å"religious ideas and practices†(p. 78).            Second, key thinkers such as Augustine and Thomas Aquinas also contributed a lot in employing philosophy as a way to explicate Christian beliefs. With Augustine, â€Å"Christianity became so permanently interwoven with elements of Platonic thought†(Moore & Bruder, 2005, 79). Augustine’s theology was chiefly concerned with arguing truths about the eternality of Christian God and the capacity of the mind to grasp the eternal truths; and these teachings are importations of the Platonic metaphysics and cosmology. Aquinas meanwhile was responsible conceiving the â€Å"underlying accord between Christian principles and Aristotle’s philosophy†from the ashes of the dark ages (p. 88). As with Plato, Aquinas’ teachings about God, nature and existence, knowledge and the world conveniently employed the methods used by philosophy.            Third, many teachings forwarded by key Christian thinkers are actually philosophies which underwent a process of Christian adaptation. In other words, the manner by which these thinkers employed philosophy in explicating their theologies â€Å"in effect†may be regarded as a process of â€Å"grafting the principles and distinction†of Greek philosophy to â€Å"Christian revealed truth†(p. 88) The doctrine of the human soul and the Trinity are glaring examples to this. If only to argue, the Christian teaching that human persons have both body and souls is very reminiscent of the Platonic dualistic cosmology, i.e., that reality is composed of matter and form. The doctrine of the Trinity meanwhile is heavily employing the concepts of universals – a teaching that enables one to infer the conceptual similarities defining of two otherwise distinct entities. The result of this adaptation process is very significant to philosophy. What this process achieved was to ultimately create a â€Å"complete Christian philosophy†(p. 89). Conclusion            This paper concludes that indeed, Christianity is a religious movement that had a significant impact in the development of philosophy. While there are many reasons that could be cited to substantiate such a claim, three factors were deemed to be of paramount importance: namely, the rapid rise of Christianity during the ancient era, the use of prevailing philosophies to explain Christian tenets by key Christian thinkers, and the creation of a complete Christian philosophy which capitalized on adapting philosophical issues within the context of Christianity. Work Cited Moore, B. & Bruder, K. (2005). Philosophy: The Power of Ideas with PowerWeb. Sixth Edition.          New York, Mc-Graw Hill
Thursday, January 2, 2020
Essay about Informative Speech Outline- Sleep Apnea
Mikala Stevens Professor Tracie Kriska Public Speaking 6th March 2013 Working Outline Topic: Sleep Apnea General Purpose: to inform Specific Purpose: to inform the audience on Sleep Apnea Thesis: Sleep Apnea is becoming more of a dangerous disease that more people are starting to be diagnosed with. It is extremely important that Sleep Apnea is emphasized so that more people are aware of it. Introduction: â€Å"The National Sleep Foundation†says that a lot of people don’t know what sleep apnea is. Sleep Apnea is a dangerous disease that can lead to death while you’re sleeping. Body: I. There are two types of Sleep Apnea A. Central Sleep Apnea 1. Unlike OSA, the airway is not blocked, but the brain fails to signal†¦show more content†¦D. You’re overweight. The extra soft fat tissue can thicken the wall of the windpipe. This narrows the inside of the windpipe, which makes it harder to keep open. E. The aging process limits your brain signals’ ability to keep your throat muscles stiff during sleep. Thus, airway is more likely to narrow or collapse. Transition: â€Å"National Institute of Health†has Steps on how to treat Sleep Apnea. IV. â€Å"The National Institute of Health†suggests that Sleep Apnea should be treated with lifestyle changes, mouthpieces, breathing devices, and surgery. Goals of treating sleep apnea are to restore regular breathing during sleep and relieve symptoms such as loud snoring and daytime sleepiness. A. Lifestyle Changes 1. Avoid Alcohol and medicines that make you sleepy. 2. Losing weight if you’re overweight or obese. 3. Sleeping on your side instead of your back to help keep your throat open. 4. Keeping your nasal passages open at night with nasal sprays or allergy medicines, if needed. 5. If you smoke, quit. B. Mouthpieces 1. Oral Appliance C. Breathing Devices 1. Cpap Machine D. Surgery Conclusion: Learning that Sleep Apnea is a dangerous disease and more people are being diagnosed with it. I hope that learning more about this disease more people will be more aware of it. Works CitedShow MoreRelatedSleep Deprivation Essay883 Words  | 4 PagesFormal Informative Outline Sleeping Deprivation General Purpose: To inform. Specific purpose: Sleep is a precious gift that allows people to rest. Not getting enough rest on a constant basis can lead to greater problems, even death Organizational Pattern: Introduction I. Blame It On the Light Bulb.  College students and individuals around the world are suffering from a health problem that can be more detrimental to their health than some forms of cancer.  What is it?  Sleep Deprivation Read MoreChildhood Obesitiy Essay698 Words  | 3 PagesInformative Speech 1 Outline Childhood Obesity Planning Block General Purpose: To inform Specific Purpose: To inform the audience of the importance of childhood obesity Central Idea: Childhood obesity is an epidemic that is sweeping across America and will continue to get worse unless the problem is faced head on. Introduction Hook: Introduce myself. Then start talking about the â€Å"Maury Povich†show when there are fat babies. Then talk about how they think it may be funny/cuteRead MoreInformative Speech on Michael Jackson3232 Words  | 13 PagesInformative Speech Purpose: To inform or educate the audience about a topic of your choice. Time: 4-6 minutes Topic: Choose a topic that interests you and would probably interest your audience (the class). Consider what your audience already knows about this topic and what their attitude about this topic will be. Do not inform us of something we already know tons about. You may not choose something that could be done as a demonstration speech. Requirements: - You must inform the audienceRead MoreEssay on Informative Speech Outline-Childhood Obesity840 Words  | 4 PagesInformative Speech Outline Jill Lesmann Oral Communications Cathleen Kruska April 9th 2015  Topic: Childhood Obesity INTRODUCTION I. Attention Getter: Hi, my name is Jill. I have been a pediatric nurse for almost 2 years now. According to the National Center for Health Statistics in 2011, childhood Obesity has more than doubled in children and quadrupled in adolescents in the past 30 years. And in 2012, more than one-third of children and adolescents were overweight or obese. II
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