|
|
| Line 1: |
Line 1: |
| '''Iron oxide nanoparticles''' are [[iron oxide]] particles with diameters between about 1 and 100 [[nanometers]]. The two main forms are [[magnetite]] ({{iron|3}}{{oxygen|4}}) and its oxidized form [[maghemite]] (γ-{{iron|2}}{{oxygen|3}}). They have attracted extensive interest due to their [[superparamagnetic]] properties and their potential applications in many fields (although {{cobalt}} and {{nickel}} are also highly magnetic materials, they are toxic and easily oxidized). | | Ordinarily I would not be in the marketplace for a chef's knife because I have what Best Kitchen Knife Gift would have been a quite high priced set of Wüsthof knives all nicely stored in a wooden knife block. A serrated knife with a lengthy, rectangular blade can cut through the crust of bread without the need of crushing it. It may possibly not be the knife a chef reaches for frequently, but it is [http://mondediplo.com/spip.php?page=recherche&recherche=uniquely uniquely] made for a certain job and is worth getting in any properly-stocked kitchen. The serrated knife operates properly on tomatoes as well, although a really sharp chef's knife can manage tomatoes completely properly. A boning knife is made use of to break down meat, fish and poultry.<br><br>How to Use It: The fifth critical tool for your knife block is actually not a knife at all but rather a honing steel, which is made to retain your knives at their peak sharpness for as long as attainable. Running your knife along a steel realigns the teeth (or fibers) on the blade, which leads to a sharper edge and thus a cleaner reduce. Chef Oliver extremely suggests building salads employing a range of lettuces and adds some carrots or radish to produce that crunch.<br><br>If you have any Victorinox Fibrox 8 Chef [http://www.adobe.com/cfusion/search/index.cfm?term=&Knife+Reviews&loc=en_us&siteSection=home Knife Reviews] thoughts about exactly where and how to use [http://www.thebestkitchenknivesreviews.com/best-chef-knives-reviews/ Best Vintage Chef's Knife], you can get in touch with us at our web page. They hold up extremely properly, and are very affordable at about $40 for and eight" chef knife, and but nevertheless forged. If you know how to manage knives, and care for them properly, a set of Wusthof Classics or Global GF Series appear the ideal selection. Lastly, but absolutely worth mentioning, the similar business that had been creating Swiss Army knives for years also makes a incredibly decent set of reasonably priced kitchen knives. Never ever place a excellent knife in the dishwasher.<br><br>Slicer - With its long, flexible blade, this knife is utilized for creating presentation-worthy slices of cooked meat. When your knife is balanced, you will be able to operate without the need of tiring you wrist for numerous hours. Another trouble can arrise when the knife has a metal manage which will make it heavier on the handle side of the knife, therefore producing unbalanced and tougher to use. A top quality set of knives is a good productivity booster.<br><br>In this absolutely free cooking video series, an specialist will show you how to improve your knife capabilities making use of a assortment of cutlery. You will find out how to use a serrated knife, vegetable knife, santoku knife and a paring knife. You will also get tips on how to dice and slice onions with a chef's knife, how to hold a chef's knife and how to cut a mango and pineapple. Some say this is the ideal, most versatile knife in existence. Its reasonably priced for both the amateur and expert chef.<br><br>When a little youngster I discovered that an adult cousin collected some quite old Japanese swords taken in Planet War II and sold at auction etc. I admire a fantastic cutting knife, but for some factors these days I have just been employing a small stake knife to reduce all the things. Quite interesting hub and I have to say you overcame a lot with intially possessing been attacked with a knife. Yes I have a very good set now, I would be lost if my chinese cleaver goes missing. The Paring knife from Master Reduce two is above all.<br><br>The knife set utilizes full tangs and that is anything that customers loved a lot due to the fact it increased the balance. A user mentioned that the ergonomic manage style was a little diverse from other knife sets and might be uncomfortable for some in the starting but with a couple of days to break it in, a single should really manage to get acquainted with them. For a affordable price tag, this is the very best achievable collection of skilled stamped knife set.<br><br>I'm not certain if most household cooks realize it or not, but black pepper tastes so a lot improved if it is ground fresh out of a peppermill If you do any seasoning at all though you cook, a fantastic peppermill is going to make a world of distinction in the way your meals tastes. Cooks can get leverage when cutting due to the chef knife's big blade, and chopping is created easy due to its curvature. |
| | |
| Applications of iron oxide nanoparticles include [[terabit]] [[magnetic storage]] devices, [[catalysis]], [[sensors]], and high-sensitivity biomolecular [[magnetic resonance imaging]] (MRI) for medical diagnosis and therapeutics. These applications require coating of the nanoparticles by agents such as long-chain [[fatty acid]]s, [[Amine#Alkylation|alkyl-substituted amines]] and [[diol]]s.
| |
| | |
| ==Structure==
| |
| Magnetite has an [[Spinel#The spinel structure|inverse spinel structure]] with oxygen forming a face-centered [[cubic crystal system]]. In magnetite, all tetrahedral sites are occupied by {{chem|Fe|3+}} and octahedral sites are occupied by both {{chem|Fe|3+}} and {{chem|Fe|2+}}. Maghemite differs from magnetite in that all or most of the iron is in the trivalent state ({{chem|Fe|3+}}) and by the presence of [[ion|cation]] [[Vacancy defect|vacancies]] in the octahedral sites. Maghemite has a cubic [[Unit_cell#Unit_cell|unit cell]] in which each cell contains 32 {{oxygen}} ions, 21{{fraction|1|3}} {{chem|Fe|3+}} ions and 2{{fraction|2|3}} vacancies. The cations are distributed randomly over the 8 tetrahedral and 16 octahedral sites.<ref name = laurent>{{cite journal | doi = 10.1021/cr068445e | title = Magnetic Iron Oxide Nanoparticles: Synthesis, Stabilization, Vectorization, Physicochemical Characterizations, and Biological Applications | year = 2008 | last1 = Laurent | first1 = Sophie | last2 = Forge | first2 = Delphine | last3 = Port | first3 = Marc | last4 = Roch | first4 = Alain | last5 = Robic | first5 = Caroline | last6 = Vander Elst | first6 = Luce | last7 = Muller | first7 = Robert N. | journal = Chemical Reviews | volume = 108 | pages = 2064–110 | pmid = 18543879 | issue = 6}}</ref><ref name = buschow>{{cite book | editor = Buschow, K.H.G. | title = Hand Book of Magnetic Materials | publisher = Elsevier | year = 2006}}</ref>
| |
| | |
| ==Magnetic properties==
| |
| Due to its 4 [[unpaired electron]]s in [[electron shell|3d shell]], an iron atom has a strong [[magnetic moment]]. Ions {{chem|Fe|2+}} have also 4 unpaired electrons in 3d shell and {{chem|Fe|3+}} have 5 unpaired electrons in 3d shell. Therefore, when crystals are formed from iron atoms or ions {{chem|Fe|2+}} and {{chem|Fe|3+}} they can be in [[ferromagnetic]], [[antiferromagnetic]] or [[ferrimagnetic]] states.
| |
| | |
| In the [[paramagnetic]] state, the individual atomic [[magnetic moment]]s are randomly oriented, and the substance has a zero net magnetic moment if there is no [[magnetic field]]. These materials have a relative [[Permeability (electromagnetism)|magnetic permeability]] greater than one and are attracted to magnetic fields. The magnetic moment drops to zero when the applied field is removed. But in a [[ferromagnetic]] material, all the atomic moments are aligned even without an external field. A [[ferrimagnetic]] material is similar to a ferromagnet but has two different types of atoms with opposing magnetic moments. The material has a magnetic moment because the opposing moments have different strengths. If they have the same magnitude, the crystal is [[antiferromagnetic]] and possesses no net magnetic moment.<ref name = teja>{{cite journal | doi =10.1016/j.pcrysgrow.2008.08.003 | title =Synthesis, properties, and applications of magnetic iron oxide nanoparticles | year =2009 | last1 =Teja | first1 =Amyn S. | last2 =Koh | first2 =Pei-Yoong | journal =Progress in Crystal Growth and Characterization of Materials | volume =55 | pages =22}}</ref>
| |
| | |
| When an external magnetic field is applied to a ferromagnetic material, the [[magnetization]] (''M'') increases with the strength of the magnetic field (''H'') until it approaches [[Saturation (magnetic)|saturation]]. Over some range of fields the magnetization has [[hysteresis]] because there is more than one stable magnetic state for each field. Therefore, a [[Remanence|remanent magnetization]] will be present even after removing the external magnetic field.<ref name = teja/> | |
| | |
| A [[single domain (magnetic)|single domain]] magnetic material (ex: magnetic nanoparticles) that has no hysteresis loop is said to be [[superparamagnetic]]. The ordering of magnetic moments in [[ferromagnetic]], [[antiferromagnetic]], and [[ferrimagnetic]] materials decreases with increasing temperature. Ferromagnetic and ferrimagnetic materials become disordered and lose their magnetization beyond the [[Curie temperature]] <math>''T''_C</math> and antiferromagnetic materials lose their magnetization beyond the [[Néel temperature]] <math>T_N</math>. [[Magnetite]] is ferrimagnetic at room temperature and has a Curie temperature of 850 [[Kelvin|K]]. [[Maghemite]] is ferrimagnetic at room temperature, unstable at high temperatures, and loses its [[Magnetic susceptibility|susceptibility]] with time. (Its Curie temperature is hard to determine). Both magnetite and maghemite nanoparticles are superparamagnetic at room temperature.<ref name = teja/>
| |
| This superparamagnetic behavior of iron oxide nanoparticles can be attributed to their size. When the size gets small enough (<20 nm), [[thermal fluctuations]] can change the direction of magnetization of the entire crystal. A material with many such crystals behaves like a [[paramagnetism|paramagnet]], except that the moments of entire crystals are fluctuating instead of individual atoms.<ref name = teja/>
| |
| | |
| ==Synthesis==
| |
| The preparation method has a large effect on shape, size distribution, and surface chemistry of the particles. It also determines to a great extent the distribution and type of structural defects or impurities in the particles. All these factors affect magnetic behavior. Recently, many attempts have been made to develop processes and techniques that would yield ‘[[monodisperse]] [[colloid]]s’ consisting of nanoparticles uniform in size and shape.
| |
| | |
| ===Coprecipitation===
| |
| By far the most employed method is [[coprecipitation]]. This method can be further divided into two types.
| |
| In the first, [[Iron(II) hydroxide|ferrous hydroxide]] [[Suspension (chemistry)|suspensions]] are partially oxidized with different oxidizing agents. For example, spherical magnetite particles of narrow size distribution with mean diameters between 30 and 100 nm can be obtained from a {{chem|Fe(II)}} salt, a base and a mild oxidant ([[nitrate]] ions).<ref>{{cite journal | doi = 10.1016/0021-9797(80)90187-3 | title = Formation of uniform spherical magnetite particles by crystallization from ferrous hydroxide gels*1 | year = 1980 | last1 = Sugimoto | first1 = T | journal = Journal of Colloid and Interface Science | volume = 74 | pages = 227}}</ref> The other method consists in ageing stoichiometric mixtures of ferrous and ferric hydroxides in aqueous media, yielding spherical magnetite particles homogeneous in size.<ref>Massart, R.; Cabuil, V.J.Chem.Phy.1987, 84,967.</ref> In the second type, the following chemical reaction occurs:
| |
| :2{{chem|Fe|3+}} + {{chem|Fe|2+}} + 8{{oxygen}}{{chem|H|-}}-→ {{iron|3}}{{oxygen|4}} + 4{{hydrogen|2}}{{oxygen}}
| |
| | |
| Optimum conditions for this reaction are [[pH]] between 8 and 14, {{chem|Fe|3+}}/{{chem|Fe|2+}} ratio of 2:1 and a non-oxidizing environment. Being highly susceptibile to oxidation, magnetite ({{iron|3}}{{oxygen|4}}) is transformed to maghemite (γ{{iron|2}}{{oxygen|3}}) in the presence of oxygen:<ref name = laurent/>
| |
| | |
| :2{{iron|3}}{{oxygen|4}} + {{oxygen|2}} → 2γ{{iron|2}}{{oxygen|3}}
| |
| | |
| The size and shape of the nanoparticles can be controlled by adjusting pH, [[ionic strength]], temperature, nature of the [[Salt (chemistry)|salts]] ([[perchlorate]]s, [[chloride]]s, [[sulfate]]s, and [[nitrate]]s), or the {{chem|Fe(II)}}/{{chem|Fe(III)}} concentration ratio.<ref name = laurent/>
| |
| | |
| ===Microemulsions===
| |
| A [[microemulsion]] is a stable [[isotropy|isotropic]] [[Dispersion (chemistry)|dispersion]] of 2 [[immiscible]] liquids consisting of nanosized domains of one or both liquids in the other stabilized by an [[Interface (chemistry)|interfacial]] film of surface-active molecules. Microemulsions may be categorized further as oil—in—water (o/w) or water—in—oil (w/o), depending on the dispersed and continuous phases.<ref name = buschow/>
| |
| Water—in—oil is more popular for synthesizing many kinds of nanoparticles. The water and oil are mixed with an amphiphillic [[surfactant]]. The surfactant lowers the surface tension between water and oil, making the solution transparent. The water nanodroplets act as nanoreactors for synthesizing nanoparticles. The shape of the water pool is spherical. The size of the nanoparticles will depend on size of the water pool to a great extent. Thus, the size of the spherical nanoparticles can be tailored and tuned by changing the size of the water pool.<ref>{{cite journal | doi = 10.1016/0021-9797(76)90030-8 | title = An expedient technique for determining solubility phase boundaries in surfactant?water systems*1 | year = 1976 | last1 = Laughlin | first1 = R | journal = Journal of Colloid and Interface Science | volume = 55 | pages = 239}}</ref>
| |
| | |
| ===High-temperature decomposition of organic precursors===
| |
| The decomposition of iron precursors in the presence of hot organic surfactants results in samples with good size control, narrow size distribution (5-12 nm) and good [[crystallinity]]; and the nanoparticles are easily dispersed. For biomedical applications like magnetic resonance imaging, magnetic cell separation or magnetorelaxometry, where particle size plays a crucial role, magnetic nanoparticles produced by this method are very useful. Viable iron precursors include {{chem|Fe(Cup)|3}},{{chem|Fe(CO)|5}}, or {{chem|Fe(acac)|3}} in organic solvents with surfactant molecules. A combination of Xylenes and Sodium Dodecylbenezensulfonate as a surfactant are used to create nanoreactors for which well dispersed iron(II) and iron (III) salts can react.<ref name = laurent/>
| |
| | |
| ==Biomedical Applications==
| |
| Magnetite and maghemite are preferred in [[biomedicine]] because they are [[Biocompatibility|biocompatible]] and potentially non-toxic to humans{{Citation needed|reason=please add reference for human cytotoxicity to support this claim|date=November 2010}}. Iron oxide is easily degradable and therefore useful for in vivo applications{{Citation needed|reason=the Brunner et al study consists entirely of in vitro evidence; please add references for in vivo cytotoxicity |date=November 2010}}. Results from exposure of a human [[mesothelium]] [[cell line]] and a [[murine]] [[fibroblast]] cell line to seven industrially important nanoparticles showed a nanoparticle specific [[cytotoxic]] mechanism for uncoated iron oxide.<ref>{{cite journal | doi = 10.1021/es052069i | title = In Vitro Cytotoxicity of Oxide Nanoparticles: Comparison to Asbestos, Silica, and the Effect of Particle Solubility† | year = 2006 | last1 = Brunner | first1 = Tobias J. | last2 = Wick | first2 = Peter | last3 = Manser | first3 = Pius | last4 = Spohn | first4 = Philipp | last5 = Grass | first5 = Robert N. | last6 = Limbach | first6 = Ludwig K. | last7 = Bruinink | first7 = Arie | last8 = Stark | first8 = Wendelin J. | journal = Environmental Science & Technology | volume = 40 | pages = 4374 | issue = 14|bibcode = 2006EnST...40.4374B }}</ref> Solubility was found to strongly influence the cytotoxic response.
| |
| Labelling cells (e.g. [[stem cells]], [[dendritic cells]]) with iron oxide nanoparticles is an interesting new tool to monitor such labelled cells in real time by [[magnetic resonance tomography]].<ref>{{cite journal|last=Bulte|first=Jeff W. M.|coauthors=Kraitchman, Dara L.|title=Iron oxide MR contrast agents for molecular and cellular imaging|journal=NMR in Biomedicine|year=2004|volume=17|issue=7|pages=484–499|doi=10.1002/nbm.924}}</ref>
| |
| | |
| ==References==
| |
| <!--- See [[Wikipedia:Footnotes]] on how to create references using <ref></ref> tags which will then appear here automatically -->
| |
| {{Reflist}}
| |
| | |
| [[Category:Nanomaterials]]
| |
| [[Category:Iron compounds]]
| |
| [[Category:Oxides]]
| |
Ordinarily I would not be in the marketplace for a chef's knife because I have what Best Kitchen Knife Gift would have been a quite high priced set of Wüsthof knives all nicely stored in a wooden knife block. A serrated knife with a lengthy, rectangular blade can cut through the crust of bread without the need of crushing it. It may possibly not be the knife a chef reaches for frequently, but it is uniquely made for a certain job and is worth getting in any properly-stocked kitchen. The serrated knife operates properly on tomatoes as well, although a really sharp chef's knife can manage tomatoes completely properly. A boning knife is made use of to break down meat, fish and poultry.
How to Use It: The fifth critical tool for your knife block is actually not a knife at all but rather a honing steel, which is made to retain your knives at their peak sharpness for as long as attainable. Running your knife along a steel realigns the teeth (or fibers) on the blade, which leads to a sharper edge and thus a cleaner reduce. Chef Oliver extremely suggests building salads employing a range of lettuces and adds some carrots or radish to produce that crunch.
If you have any Victorinox Fibrox 8 Chef Knife Reviews thoughts about exactly where and how to use Best Vintage Chef's Knife, you can get in touch with us at our web page. They hold up extremely properly, and are very affordable at about $40 for and eight" chef knife, and but nevertheless forged. If you know how to manage knives, and care for them properly, a set of Wusthof Classics or Global GF Series appear the ideal selection. Lastly, but absolutely worth mentioning, the similar business that had been creating Swiss Army knives for years also makes a incredibly decent set of reasonably priced kitchen knives. Never ever place a excellent knife in the dishwasher.
Slicer - With its long, flexible blade, this knife is utilized for creating presentation-worthy slices of cooked meat. When your knife is balanced, you will be able to operate without the need of tiring you wrist for numerous hours. Another trouble can arrise when the knife has a metal manage which will make it heavier on the handle side of the knife, therefore producing unbalanced and tougher to use. A top quality set of knives is a good productivity booster.
In this absolutely free cooking video series, an specialist will show you how to improve your knife capabilities making use of a assortment of cutlery. You will find out how to use a serrated knife, vegetable knife, santoku knife and a paring knife. You will also get tips on how to dice and slice onions with a chef's knife, how to hold a chef's knife and how to cut a mango and pineapple. Some say this is the ideal, most versatile knife in existence. Its reasonably priced for both the amateur and expert chef.
When a little youngster I discovered that an adult cousin collected some quite old Japanese swords taken in Planet War II and sold at auction etc. I admire a fantastic cutting knife, but for some factors these days I have just been employing a small stake knife to reduce all the things. Quite interesting hub and I have to say you overcame a lot with intially possessing been attacked with a knife. Yes I have a very good set now, I would be lost if my chinese cleaver goes missing. The Paring knife from Master Reduce two is above all.
The knife set utilizes full tangs and that is anything that customers loved a lot due to the fact it increased the balance. A user mentioned that the ergonomic manage style was a little diverse from other knife sets and might be uncomfortable for some in the starting but with a couple of days to break it in, a single should really manage to get acquainted with them. For a affordable price tag, this is the very best achievable collection of skilled stamped knife set.
I'm not certain if most household cooks realize it or not, but black pepper tastes so a lot improved if it is ground fresh out of a peppermill If you do any seasoning at all though you cook, a fantastic peppermill is going to make a world of distinction in the way your meals tastes. Cooks can get leverage when cutting due to the chef knife's big blade, and chopping is created easy due to its curvature.