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Zinc(I) compounds are rare, and require bulky ligands to stabilize the low oxidation state. Most zinc(I) compounds contain formally the [Zn2]2+ core, which is analogous to the [Hg2]2+ dimeric cation present in mercury(I) compounds. The diamagnetic nature of the ion confirms its dimeric structure. The first zinc(I) compound containing the ZnZn bond, (5-C5Me5)2Zn2, is also the first dimetallocene. The [Zn2]2+ ion rapidly disproportionates into zinc metal and zinc(II), and has only been obtained as a yellow glass formed by cooling a solution of metallic zinc in molten ZnCl2.
What core do most zinc(l) compounds contain?
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The answer: [Zn2]2+

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Some paleontologists suggest that animals appeared much earlier than the Cambrian explosion, possibly as early as 1 billion years ago. Trace fossils such as tracks and burrows found in the Tonian period indicate the presence of triploblastic worms, like metazoans, roughly as large (about 5 mm wide) and complex as earthworms. During the beginning of the Tonian period around 1 billion years ago, there was a decrease in Stromatolite diversity, which may indicate the appearance of grazing animals, since stromatolite diversity increased when grazing animals went extinct at the End Permian and End Ordovician extinction events, and decreased shortly after the grazer populations recovered. However the discovery that tracks very similar to these early trace fossils are produced today by the giant single-celled protist Gromia sphaerica casts doubt on their interpretation as evidence of early animal evolution.
How long ago do some paleontologists believe that animals first appeared?
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The answer: 1 billion years

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A series of experiments performed from the late 1800s to the early 1900s revealed that diabetes is caused by the absence of a substance normally produced by the pancreas. In 1869, Oskar Minkowski and Joseph von Mering found that diabetes could be induced in dogs by surgical removal of the pancreas. In 1921, Canadian professor Frederick Banting and his student Charles Best repeated this study, and found that injections of pancreatic extract reversed the symptoms produced by pancreas removal. Soon, the extract was demonstrated to work in people, but development of insulin therapy as a routine medical procedure was delayed by difficulties in producing the material in sufficient quantity and with reproducible purity. The researchers sought assistance from industrial collaborators at Eli Lilly and Co. based on the company's experience with large scale purification of biological materials. Chemist George Walden of Eli Lilly and Company found that careful adjustment of the pH of the extract allowed a relatively pure grade of insulin to be produced. Under pressure from Toronto University and a potential patent challenge by academic scientists who had independently developed a similar purification method, an agreement was reached for non-exclusive production of insulin by multiple companies. Prior to the discovery and widespread availability of insulin therapy the life expectancy of diabetics was only a few months.
Who discovered that pancreatic extract reversed symptoms of pancreas removal?
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The answer: Frederick Banting and his student Charles Best

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According to Italian fashion designer Roberto Cavalli, Beyonce uses different fashion styles to work with her music while performing. Her mother co-wrote a book, published in 2002, titled Destiny's Style an account of how fashion had an impact on the trio's success. The B'Day Anthology Video Album showed many instances of fashion-oriented footage, depicting classic to contemporary wardrobe styles. In 2007, Beyonce was featured on the cover of the Sports Illustrated Swimsuit Issue, becoming the second African American woman after Tyra Banks, and People magazine recognized Beyonce as the best-dressed celebrity.
Which African-American woman before Beyonce had posed for SI Swimsuit issue?
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The answer:
Tyra Banks