Home Biology Debate heats up over claims that hot water sometimes freezes faster than cold It seems logical to expect cold water to freeze faster than hot, but some experiments have suggested the opposite. There’s now a new explanation for why hot water might freeze faster than cold under certain conditions. The phenomenon, known as the Mpemba effect, may be due to the properties of the chemical bonds that link up neighboring water molecules, a team of chemists reports. Yet other researchers contend that the effect doesn’t exist at all. References to quick-freezing hot water date back to the early days of science: Aristotle reported observing hot water freezing faster than cold. In a paper published online December 6 in Journal of Chemical Theory and Computation, scientists propose that hydrogen bonds, the links formed between hydrogen atoms and the oxygen atoms of neighboring water molecules, could be part of the puzzle. Cremer and colleagues realized their new understanding of hydrogen bonds could explain the Mpemba effect.
Woma Exploring Nature Educational Resource: A Natural Science Resource for Students and Educators Questioning the Mpemba effect: hot water does not cool more quickly than cold Biophiles D'abord un petit blabla (court, promis) sur ce site... Un site désiré... pourquoi ? Parce que cela faisait longtemps que je voulais le faire, tout proportion gardée... Partage des connaissances Je suis étudiante en biologie et durant mes années précédentes, j'ai eu l'occasion de me procurer les cours d'années antérieures corrrespondant mots pour mots à ceux que je suivais. Avertissement Je mets à disposition MES notes de cours !! Un autre détail : Assistez aux cours !!
A decade on, vaccine has halved cervical cancer rate Image copyright Getty Images The world's first cancer vaccine was administered in Australia exactly 10 years ago. Since then, the human papilloma virus (HPV) vaccine has been rolled out across 130 countries and halved the number of new cervical cancers. The HPV vaccine also protects against cancers in the throat and mouth in both men and women. Prof Ian Frazer said the vaccine could eradicate cancers caused by HPV within 40 years. "It helps not only control cervical cancer but also the oropharyngeal cancer - the cancers inside the mouth that are caused by these viruses," Prof Frazer, chief executive of the Translational Research Institute, said. "If we vaccinate enough people we will eliminate these viruses because they only infect humans. 'Very common indeed' HPV is a very common virus that lives on our skin and other areas of the body, including the mouth, genital areas and anus. The virus is most often passed during vaginal and anal sex, but can also be transmitted through oral sex.
Portail BioMedia-UPMC L'équipe BioMédia au sein de la Faculté de Biologie (UFR 927), crée des ressources pédagogiques en utilisant les moyens actuels (graphisme, animations, vidéos) pour une meilleure compréhension des phénomènes biologiques. Cela constitue une base importante de ressources web (documents de cours, sujets transversaux, sujets ponctuels, mises au point...). En 2016, grâce à un financement IDEX SUPER Sorbonne Universités, nous avons créé un nouveau site responsive de Ressources Numériques pour l'enseignement en licence de Biologie (RN'Bio). Nous proposons également sur le site Bmedia, des documents utilisables par les étudiants, les enseignants et un public plus large. Pour la formation en biologie de l'UPMC, l'équipe BioMédia gère les sites de mention "Licence SdV" et "Master bmc" et le site de l'Ecole Doctorale "Logique du Vivant" (ED515). De plus, nous assurons la mise en ligne de documents de cours pour les étudiants en biologie de l’UPMC.
Glyphosate Vs. Caffeine: Acute and Chronic Toxicity Assessments Explained – Food and Farm Discussion Lab [Please consider supporting Food and Farm Discussion Lab with an ongoing contribution of $1, $2, $3, $5 or $10 a month on Patreon. All contributors receive a subscription to our email newsletter the FAFDL Dispatch. ] GUEST AUTHOR: Alison Bernstein, PhD is a neuroscientist, who studies the role of epigenetics and environmental exposures in Parkinson’s disease. Follow her on Facebook and G+, where she writes as “Mommy PhD”, and on Twitter @mommyphd2. Article length: 2800 words – 12-15 minute read. Fear of chemicals in our food has taken on an outsized role in the food discussion. Much of this problem arises from a general misunderstanding of the science of toxicity,. What is an LD50? Let’s get something straight about LD50 – it is a measure of ACUTE toxicity. An LD50, or the median Lethal Dose, and the related LC50 (median lethal concentration, for inhalation rather than ingestion) are measures of acute toxicity only. Measures of chronic toxicity Oral RfD for caffeine Oral RfD for glyphosate
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