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merits of uniquely defined but arbitrary protocols for assigning that density. People in the trade will recognize that I'm talking about "Mulliken population analysis" or "natural bond analysis" or Richard Bader's beautifully worked out scheme for dividing up space in a molecule. What about experiment? Is there an obse... |
might gauge a charge on an atom? I think photoelectron spectroscopies (ESCA or Auger) come the closest. Here one measures the energy necessary to promote an inner-core electron to a higher level or to ionize it. Atoms in different oxidation states do tend to group themselves at certain energies. But |
the theoretical framework that relates these spectra to charges depends on the same assumptions that bedevil the definition of a charge on an atom. An oxidation state bears little relation to the actual charge on the atom (except in the interior of the sun, where ligands are gone, there is |
plenty of energy, and you can have iron in oxidation states up to +26). This doesn't stop the occasional theoretician today from making a heap of a story when the copper in a formal Cu(III) complex comes out of a calculation bearing a charge of, say, +0.51. Nor does it |
stop oxidation states from being just plain useful. Many chemical reactions involve electron transfer, with an attendant complex of changes in chemical, physical and biological properties. Oxidation state, a formalism and not a representation of the actual electron density at a metal center, is a wonderful way to "book... |
in the course of a reaction. Even if that electron, whether added or removed, spends a good part of its time on the ligands. But enough theory, or, as some of my colleagues would sigh, anthropomorphic platitudes. Let's look at some beautiful chemistry of extreme oxidation states. Incredible, But True |
Recently, a young Polish postdoctoral associate, Wojciech Grochala, led me to look with him at the chemical and theoretical design of novel high-temperature superconductors. We focused on silver (Ag) fluorides (F) with silver in oxidation states II and III. The reasoning that led us there is described in our forthcomin... |
paper. For now let me tell you about some chemistry that I learned in the process. I can only characterize this chemistry as incredible but true. (Some will say that I should have known about it, since it was hardly hidden, but the fact is I didn't.) Here is what |
Ag(II), unique to fluorides, can do. In anhydrous HF solutions it oxidizes Xe to Xe(II), generates C6F6+ salts from perfluorobenzene, takes perfluoropropylene to perfluoropropane, and liberates IrF6 from its stable anion. These reactions may seem abstruse to a nonchemist, but believe me, it's not easy to find a reagent... |
would accomplish them. Ag(III) is an even stronger oxidizing agent. It oxidizes MF6– (where M=Pt or Ru) to MF6. Here is what Neil Bartlett at the University of California at Berkeley writes of one reaction: "Samples of AgF3 reacted incandescently with metal surfaces when frictional heat from scratching or grinding |
of the AgF3 occurred." Ag(II), Ag(III) and F are all about equally hungry for electrons. Throw them one, and it's not at all a sure thing that the electron will wind up on the fluorine to produce fluoride (F–). It may go to the silver instead, in which case you |
may get some F2 from the recombination of F atoms. Not that everyone can (or wants to) do chemistry in anhydrous HF, with F2 as a reagent or being produced as well. In a recent microreview, Thomas O'Donnell says (with some understatement), "... this solvent may seem to be an |
unlikely choice for a model solvent system, given its reactivity towards the usual materials of construction of scientific equipment." (And its reactivity with the "materials of construction" of human beings working with that equipment!) But, O'Donnell goes on to say, "... with the availability of spectroscopic and ele... |
from fluorocarbons such as Teflon and Kel-F, synthetic sapphire and platinum, manipulation of and physicochemical investigation of HF solutions in closed systems is now reasonably straightforward." For this we must thank the pioneers in the field—generations of fluorine chemists, but especially Bartlett and Boris Zemva... |
Bartlett reports the oxidation of AgF2 to AgF4– (as KAgF4) using photochemical irradiation of F2 in anhydrous HF (made less acidic by adding KF to the HF). And Zemva used Kr2+ (in KrF2) to react with AgF2 in anhydrous HF in the presence of XeF6 to make XeF5+AgF4–. What a |
startling list of reagents! To appreciate the difficulty and the inspiration of this chemistry, one must look at the original papers, or at the informal letters of the few who have tried it. You can find some of Neil Bartlett's commentary in the article that Wojciech and I wrote, and |
in an interview with him. Charge It, Please Chemists are always changing things. How to tune the propensity of a given oxidation state to oxidize or reduce? One way to do it is by changing the charge on the molecule that contains the oxidizing or reducing center. The syntheses of |
the silver fluorides cited above contain some splendid examples of this strategy. Let me use Bartlett's words again, just explaining that "electronegativity" gauges in some rough way the tendency of an atom to hold on to electrons. (High electronegativity means the electron is strongly held, low electronegativity that ... |
weakly held.) It's easy to make a high oxidation state in an anion because an anion is electron-rich. The electronegativity is lower for a given oxidation state in an anion than it is in a neutral molecule. That in turn, is lower than it is in a cation. If I |
take silver and I expose it to fluorine in the presence of fluoride ion, in HF, and expose it to light to break of F2 to atoms, I convert the silver to silver(III), AgF4-. This is easy because the AG(III) is in an anion. I can then pass in boron |
trifluoride and precipitate silver trifluoride, which is now a much more potent oxidizer than AgF4- because the electronegativity in the neutral AgF3 is much higher than it is in the anion. If I can now take away a fluoride ion, and make a cation, I drive the electronegativity even further |
up. With such a cation, for example, AgF2+, I can steal the electron from PtF6- and make PtF6.... This is an oxidation that even Kr(II) is unable to bring about. Simple, but powerful reasoning. And it works. A World Record? Finally, a recent oxidation-state curiosity: What is the highest oxidation |
state one could get in a neutral molecule? Pekka Pyykkö and coworkers suggest cautiously, but I think believably, that octahedral UO6, that is U(XII), may exist. There is evidence from other molecules that uranium 6p orbitals can get involved in bonding, which is what they would have to do in |
UO6. What wonderful chemistry has come—and still promises to come—from the imperfect logic of oxidation states! © Roald Hoffmann I am grateful to Wojciech Grochala, Robert Fay and Debra Rolison for corrections and comments. Thanks to Stan Marcus for suggesting the title of this column. |
Threatened birds of the world: the official source for birds on the IUCN Red List. Barcelona: Lynx Edicions, 2000. Quarto, laminated boards, 852 pp. colour illustrations, maps. This comprehensive volume documents globally threatened species whether extinct in the wild, critical, |
Displaying 1 - 20 of 25 resources in Horses: 1. Animals recovered from horse rescue recovering Lin Beaune with Epona said three of the 41 animals didn't survive SOFE, due |
in large part to malnutrition, but of the remaining 38, all ... 2. Concern for Helping Animals in Israel (CHAI) Alexandria, VA, USA The mission of CHAI and Hakol Chai |
is to prevent and relieve animal suffering in Israel and to elevate consciousness about animals through education. We ... 3. Deputies find starving horses and squalid conditions in animal cruelty |
case Ribs and hip bones were visible under their skin, and nearby trees had been stripped of bark after the horses gnawed them clean. ... 4. Dozens of farm animals |
seized from rescue facility Authorities in western Ohio say they've removed more than 100 farm animals from a horse rescue facility as part of an animal cruelty investigation. ... 5. |
Early in Mayoral Battle, Carriage Horses Are Drawn Into Race New York's animals, from Central Park horses to rescue shelter dogs, have one of the city's most clamorous lobbying groups, |
with thousands of motivated supporters ... 6. Five horses die in animal cruelty case; 33 other animals rescued There were 23 other horses, nine goats and an alpaca that were |
rescued from the farm on Rockwell Road in Enterprise, Lt. Greg Scolapio said. ... 7. Freedom for Animals - Serbia Based in Belgrade, Freedom for Animals (Sloboda za životinje) focuses |
on vegetarianism and animal rights. Current campaigns include circus protests, anti-hunting demos, and the plight ... 8. From Carriage Horses To Chihuahas And Cockatiels, An Appeal For The Animal Lover |
Vote But only de Blasio supported NY CLASS's key goal of completely banning the horse-drawn carriages, while others talked about testing out alternatives or phasing them ... 9. Gonzalez entitled |
to return of animals, judge rules Two dogs and a horse confiscated when State Police obtained a search warrant on the complaint of Gonzalez' veterinarian must be returned, Lockport City |
Judge ... 10. Habitat for Horses Hithcock, TX, USA A non-profit organization established to provide information and enforcement of existing laws to protect abused, endangered, and neglected horses through a |
volunteer network. ... 11. Horse Behaviour and Psychology Kaikohe, New Zealand Comprehensive illustrated resource on the behaviour and psychology of equines from the White Horse Equine Ethology Project. ... Category: |
Educational Resources 12. Horse case puts spotlight on animal welfare in North Dakota A recent case of officials in Burleigh and Morton counties finding 99 dead horses in a man's |
custody and seizing an additional 157 live ones ... 13. Horse Meat In Human Food Chain Causes Health Concerns By one estimate, 160,000 American horses shared this fate last year, |
ending up in the human food chain. ... 14. Horse shooting highlights slaughter debate He strokes his nose and neck, swears at animal activitists, and then shoots it in the |
head. ... 15. International Association of Animal Behavior Consultants Cranberry Township, PA, USA IAABC members have diverse practices but believe that animals matter, and so do animal-owner relationships. They understand |
that animal behavior consultants can help manage and ... 16. Kefalonia Animal Trust (Greece) Argostoli , Greece Animal Welfare in Kefalonia is our primary concern. Kefalonia Animal Trust is a |
registered Greek animal charity, dedicated to caring for the welfare of the ... 17. Mercy For Animals Columbus, OH, USA Mercy For Animals (MFA) believes that non-human animals are irreplaceable |
individuals who have morally significant interests and hence rights, including the right to live and ... 18. More Canadians willing to try horse meat in wake of scandal Japan is |
the biggest importer of Alberta's horse meat, followed by France and Switzerland, she said. Canada exported about 13,500 metric tonnes of horse meat ... 19. More than 100 animals seized |
from Bellaire home It's heartbreaking to see such a large number of animals that are just desperate for your basic necessities, such as food and water," said Minton. ... 20. |
No Rodeo (Australia) Smithfield Plains, Australia No Rodeo has been lobbying the government since October 2004 to seek total prohibition of this cruel blood sport in South Australia. Much of |
Cancer and dogs. Things you could try ..... When a dog is battling cancer his immune system needs to be focused on one thing - and that's the cancer itself. The dog doesn't have the strength to fight other battles |
e.g. chemicals that might attack his system. To help , try and find non toxic alternatives to all your chemical cleaners. Don't use pesticides in the garden. Feed with organic food. Frontline etc or vaccinations of any sort may be |
detrimental to your dog's fight. Most vets recommend that dogs fighting cancer get a diet that is high in protein (about 95%) and low in carbs (5%). Most dog foods are not helpful to the dogs fight against cancer. A |
raw meat diet gives the right protein/carb mix and supplies additional nutrients to promote maximum energy and immune system support. Natural holistic dog foods can be an alternative. There are also several feed supplements available to help. Some target the |
cancer cells - either destroying them or otherwise slowing their growth. Others 'starve' the cancer by depriving it of the elements it needs to grow. Others serve as an extra boost to strengthen the dogs own energy and immune system. |
Most of these supplements can work well together. Best to speak to a trained holistic expert or vet. If the vet says for example that your dog has 6 months to live - you start to worry. We wonder how |
long the dog has left with us, is he suffering , could I have done something earlier etc. Dogs can sense the worrying. They draw energy from us... our sadness...our fears...our concerns actually make them feel down. As we worry |
we take energy from them. You MUST try and stay positive and strong. Your dog will be helped by positive reinforcement to heal. Healing can help you both at this time. It is complementary to veterinary care. |
Found throughout tropical regions of Africa, the Emperor Scorpion is one of the largest in the scorpion family. A predatory carnivore their diet ranges from insects to small mammals. In captivity we feed them live crickets, meal worms or morio |
worms about once a week. - Live up to 8 years. - With an exoskeleton which they molt once a year to enable growth. - Adult scorpions can grow to 15 centimetres in across. - Habitat being rain forest floor. |
- Nocturnal arachnids. Although it may look very dangerous, generally speaking the larger scorpions tend to be less poisonous than the smaller ones. Although it would still be painful if we were to get stung, it would not be life |
What motivates young people to learn? Fun? Imagination? Fear of the future without a college education? If you ask them, they will tell you that you can teach them anything if you make it matter to them. The easiest way |
is to make it about them. Nearly 20 years ago, when I took over the History Department of a Nairobi School, the most successful thing I did was to introduce a family tree project. I had Kikuyu students in my |
classroom, and Luo and Kalenjin and several born in Britain as well as five or six born in Nairobi but with parents or grandparents born in the Indian Subcontinent. Computers barely existed, so all information was gathered by talking to |
family members, either in person or on the phone, waiting for visits or even writing letters. Everyone had to keep notes and start drawing their tree – and as they grew, the trees became collages, with stories and even artefacts |
stuck on: a coin, a bead, a piece of cloth, a photograph. My students held court, sharing their research and findings, feeling the thrill of an attentive audience. They were the experts on their own lives, and they loved it |
(a lot more than Napoleon, who they’d done the previous term). Of course you can’t design thirteen or fourteen years of curriculum around ‘Me’ – at least not without creating a generation of narcissistic monsters. But taking time to relate |
distant or abstract material to those in the room, and finding ways to engage heart and emotions as well as head, makes excellent educational sense. This is one area where education can learn from the non-profit sector which has long |
understood that you engage people by creating proximity. It’s hard to care about people of whom we know nothing in a faraway country; the trick is to tell stories to bring them closer, to show the similarities between their lives |
and ours, to help us understand how it might feel to be them. To make it more real. Carl Jung wrote that people cannot stand too much reality, but I disagree: in my experience, teenagers gobble it up. It brings |
out the best in them, differentiating them as individuals with both abilities and passions. 2 years ago Mayor of London Boris Johnson and I both hit on the idea of a London Curriculum (although I’m pretty sure I thought of |
it first.) I based mine on an experimental class I’d taught a few years before in the US that used our local city as a classroom. Part of my inspiration also came from CITYTerm, a brilliant programme run out of |
the Masters School, which uses New York City as a classroom and laboratory. In both cases the approach was project-based and relied on collaboration with experts from the city – architects, engineers, poets, social workers and entrepreneurs. It can come |
as something of a shock to learn what’s on your doorstep: the things that are closest to us exert huge influence, yet we seldom look at them carefully, let alone understand them. The nearly 4 million people who have seen |
Chimamanda Adichie’s TED Talk on the danger of a single story will also have heard her descriptions of growing up on a Nigerian university campus reading British and American children’s books. She loved those books, but because of them, the |
first stories she wrote featured characters with white skin and blue eyes, who played in the snow and ate apples. Only later did she realise that people who looked and thought like her could be in books too. In January |
I met Deborah Ahenkorah, Ghanaian Echoing Green Fellow and founder of the Golden Baobab Prize for African literature for children and young adults. She created the prize because “the tremendous lack of good quality African children’s literature dawned on me. |
A continent so large and richly diverse has tons of wonderful stories to share with young people everywhere: where were these stories?” Last year they had more than 400 entries from 25 African countries. They also run workshops for writers |
and illustrators, and have plans to establish distribution channels across the continent to ensure that African books reach African children in their schools and, at last, in their own homes. And it’s not just African children on the continent who |
need stories about themselves. There are millions of children of African heritage in the diaspora who never read stories that connect them with their own identities either. For stories cross continents too. Last month in Ghana I visited the slave |
castles of the Gold Coast and saw the door of no return through which millions of men, women and children left, many of whom ended their days in Jamaica. With over 200,000 Ghanaians and 250,000 Jamaicans in London, shouldn’t these |
stories be told in British schools too? Who else is in our classrooms? Are we telling their stories? Growing up is an identity project, and if we want to engage young people, we need to show them that school is |
the place to learn about the things they care about. We do that best by nurturing schools’ most valuable secret weapons – infectiously enthusiastic teachers. They are an endangered species now, killed by the growing exam culture and an obsession |
with cookie-cutter, lockstep learning, but they are still there. Let’s hope that those who have been taught by them will realise that it is loving learning that matters most, and the freedom to explore who you are and how you |
For many, 1066 is the date when the Middle Ages began. Centuries of castles, cathedrals and churches followed, busy with chivalry, the Crusades and crop-rotation, all ending some time around 1500. This, of course, is an over-simplification, just as the term Middle Ages itself is. For a long time, the civilisations of t... |
ages in the middle - was regarded as inferior, a period of decline, disease and instability. Only with the Victorians was there some attempt to reconsider these centuries. They, like us, were transfixed by the imaginative leaps of medieval buildings and their intense spirituality. Certain themes dominate medieval archi... |
neighbourhood was the parish church, and the finest buildings created were the great stone cathedrals. Secondly, society was strictly ordered. For most of the Middle Ages, the hierarchy of the Feudal System dominated: the majority were poor peasants living in simple dwellings that have long disappeared. A few, the lord... |
Duke’s Charter, 1664 By this charter, King Charles II of England granted land that includes present-day New York, New Jersey, most of Maine, and parts of Connecticut and Pennsylvania to his brother James, Duke of York (later James II, King of England). The charter, or royal patent, was awarded on March 12, 1664, and se... |
send an armed force to compel the Dutch surrender of the New Netherland province to the English, and allows him to delegate the administration of matters of law, trade, rebellion, and defense in the colony. New York State Archives [Series B1371, Charter of the proprietary colony from Charles II to the Duke of York, 166... |
WORLD RELIGION RESOURCES The following sites have been awarded the ARIL Hot Site designation as offering among the best resources concerning world religion on the Internet. in World Religions Interesting format, numerous links, especially to Buddhist resources. These pages are put together by Deb Platt entirely out of ... |
of the relationship between and among world religions can find creative expression on the Internet. The place to go for facts and figures about membership in most world religions - The GodWeb features an active blog, original articles and information on the relationship between Christianity and other world religions. P... |
to study and document the growing religious diversity of the United States, with a special view to its new immigrant religious communities. The website includes a description of the CD-ROM and slide sets that give teachers and students of religion a remarkable multi-media resource to enhance their appreciation of relig... |
Professor of English at the University of Maryland, the main feature of this Web site is a large bibliographical database that lists and indexes writings by and about English figures of literary or spiritual importance, from the Middle Ages to the present. The database has been conceived on an ambitious scale, and anyo... |
visit this site frequently and watch it grow! University of Hong Kong: Research Institute for the Humanities Massive collection of philosophy and world religion resources; a well designed set of pages with links to study materials covering religion in particular and the humanities in general. Advanced HTML features. Re... |
Rutgers University. Well organized and well presented tools for the student of religion who is interested in the wider social and cultural context in which the great religious traditions exist and to which they contribute in sometimes surprising and refreshing ways. Society and Culture Dr. Hans Rollman of the Departmen... |
a visually appealing site combining serious scholarship with an obvious devotion to his subject. His pages covering nearly all aspects of the religious history and culture of Newfoundland are an example of how effective the Internet can be in communicating specialized knowledge to a wide audience that would not encount... |
in service of the secular, but there is much discussion here of biblical and theological issues. Though the editors of these pages put themselves forward as atheists and infidels, we admire their humor, irony, and Úlan. Theology Library, Emory University Here, by contrast, are the resources of a major theological libra... |
of religion. Consultants on Religious Tolerance A refreshing voice for inter-religious understanding within a sea of Internet intolerance. This site contains much useful information about world religions, religious hatred, and other related topics, including many interesting links and opportunities for dialogue across ... |
as current or recent conferences and other special events. While the website needs to be updated on a more regular basis, the information about UCLS's excellent interdisciplinary program is most welcome. |
Diagnosing Mesothelioma: MRIs Magnetic resonance imaging (MRI) is one of several imaging techniques that doctors use to detect, stage and evaluate the progression of mesothelioma. These non-invasive scans use magnets and radio waves to help doctors visualize a patient’s organs, |
tissues, bones and tumors. Many radiologists consider MRIs ideal for viewing the anatomical structures of the chest and abdomen – including the pleura and peritoneum, where mesothelioma tumors most commonly develop. The first commercial MRI units emerged in the 1980s. |
Since then, the technology has advanced considerably. Modern MRI units use superconductor magnets and coils to produce a constant magnetic field, as well as radiofrequency energy to measure signals from the nuclei of hydrogen atoms inside the body. Computers inside |
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