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Léon Maquenne
Léon-Gervais-Marie Maquenne (2 December 1853 – 10 January 1925) was a French chemist and plant physiologist born in Paris. From 1871 he worked in the laboratory of agricultural chemistry at the ''Ecole d'agriculture'' in Grignon. Here, he was a student of Pierre Paul Dehérain (1830-1902). In 1883 he became ''préparateur'' at the Muséum national d'histoire naturelle, where from 1885 to 1898 he served as an assistant to the chair of ''Physiologie végétale''. In 1898 he succeeded Georges Ville (1824-1897) as chair of ''Physique végétale'', a position he held on to until 1925. In 1904 he became a member of the Académie des sciences. Among Maquenne's contributions was research involving the chemical make-up of sugar alcohols. He was able to resolve the chemical constitution of inositol and demonstrated it to be a hexahydroxycyclohexane. He is credited with invention of the so-called "Maquenne block", an apparatus used for determining the melting point of chemical compound ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemist
A chemist (from Greek ''chēm(ía)'' alchemy; replacing ''chymist'' from Medieval Latin ''alchemist'') is a graduated scientist trained in the study of chemistry, or an officially enrolled student in the field. Chemists study the composition of matter and its properties. Chemists carefully describe the properties they study in terms of quantities, with detail on the level of molecules and their component atoms. Chemists carefully measure substance proportions, chemical reaction rates, and other chemical properties. In Commonwealth English, pharmacists are often called chemists. Chemists use their knowledge to learn the composition and properties of unfamiliar substances, as well as to reproduce and synthesize large quantities of useful naturally occurring substances and create new artificial substances and useful processes. Chemists may specialize in any number of Chemistry#Subdisciplines, subdisciplines of chemistry. Materials science, Materials scientists and metallurgists sha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Melting Point
The melting point (or, rarely, liquefaction point) of a substance is the temperature at which it changes state of matter, state from solid to liquid. At the melting point the solid and liquid phase (matter), phase exist in Thermodynamic equilibrium, equilibrium. The melting point of a substance depends on pressure and is usually specified at a Standard temperature and pressure, standard pressure such as 1 Atmosphere (unit), atmosphere or 100 Pascal (unit), kPa. When considered as the temperature of the reverse change from liquid to solid, it is referred to as the freezing point or crystallization point. Because of the ability of substances to Supercooling, supercool, the freezing point can easily appear to be below its actual value. When the "characteristic freezing point" of a substance is determined, in fact, the actual methodology is almost always "the principle of observing the disappearance rather than the formation of ice, that is, the #Melting point measurements, melting ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plant Physiologists
Plants are the eukaryotes that form the Kingdom (biology), kingdom Plantae; they are predominantly Photosynthesis, photosynthetic. This means that they obtain their energy from sunlight, using chloroplasts derived from endosymbiosis with cyanobacteria to produce sugars from carbon dioxide and water, using the green pigment chlorophyll. Exceptions are parasitic plants that have lost the genes for chlorophyll and photosynthesis, and obtain their energy from other plants or fungi. Most plants are multicellular organism, multicellular, except for some green algae. Historically, as in Aristotle's biology, the plant kingdom encompassed all living things that were not animals, and included algae and fungi. Definitions have narrowed since then; current definitions exclude fungi and some of the algae. By the definition used in this article, plants form the clade Viridiplantae (green plants), which consists of the green algae and the embryophytes or land plants (hornworts, liverworts ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1853 Births
Events January–March * January 6 – ** Florida Governor Thomas Brown signs legislation that provides public support for the new East Florida Seminary, leading to the establishment of the University of Florida. **U.S. President-elect Franklin Pierce's only living child, Benjamin "Benny" Pierce, is killed in a train accident. * January 8 – Taiping Rebellion: Zeng Guofan is ordered to assist the governor of Hunan in organizing a militia force to search for local bandits. * January 12 – Taiping Rebellion: The Taiping army occupies Wuchang. * January 19 – Giuseppe Verdi's opera '' Il Trovatore'' premieres in performance at Teatro Apollo in Rome. * February 10 – Taiping Rebellion: Taiping forces assemble at Hanyang, Hankou, and Wuchang, for the march on Nanjing. * February 12 – The city of Puerto Montt is founded in the Reloncaví Sound, Chile. * February 22 – Washington University in St. Louis is founded as Eliot Seminary. * March 5 – Saint Paul Fire ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1925 Deaths
Events January * January 1 – The Syrian Federation is officially dissolved, the State of Aleppo and the State of Damascus having been replaced by the State of Syria (1925–1930), State of Syria. * January 3 – Benito Mussolini makes a pivotal speech in the Italian Chamber of Deputies (Italy), Chamber of Deputies which will be regarded by historians as the beginning of his dictatorship. * January 5 – Nellie Tayloe Ross becomes the first female governor (Wyoming) in the United States. Twelve days later, Ma Ferguson becomes first female governor of Texas. * January 25 – Hjalmar Branting resigns as Prime Minister of Sweden because of ill health, and is replaced by the minister of trade, Rickard Sandler. * January 27–February 1 – The 1925 serum run to Nome (the "Great Race of Mercy") relays diphtheria antitoxin by dog sled across the U.S. Territory of Alaska to combat an epidemic. February * February 25 – Art Gillham records (for Columbia Re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scientists From Paris
A scientist is a person who researches to advance knowledge in an area of the natural sciences. In classical antiquity, there was no real ancient analog of a modern scientist. Instead, philosophers engaged in the philosophical study of nature called natural philosophy, a precursor of natural science. Though Thales ( 624–545 BC) was arguably the first scientist for describing how cosmic events may be seen as natural, not necessarily caused by gods,Frank N. Magill''The Ancient World: Dictionary of World Biography'', Volume 1 Routledge, 2003 it was not until the 19th century that the term ''scientist'' came into regular use after it was coined by the theologian, philosopher, and historian of science William Whewell in 1833. History The roles of "scientists", and their predecessors before the emergence of modern scientific disciplines, have evolved considerably over time. Scientists of different eras (and before them, natural philosophers, mathematici ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
19th-century French Chemists
The 19th century began on 1 January 1801 (represented by the Roman numerals MDCCCI), and ended on 31 December 1900 (MCM). It was the 9th century of the 2nd millennium. It was characterized by vast social upheaval. Slavery was Abolitionism, abolished in much of Europe and the Americas. The First Industrial Revolution, though it began in the late 18th century, expanded beyond its British homeland for the first time during the 19th century, particularly remaking the economies and societies of the Low Countries, France, the Rhineland, Northern Italy, and the Northeastern United States. A few decades later, the Second Industrial Revolution led to ever more massive urbanization and much higher levels of productivity, profit, and prosperity, a pattern that continued into the 20th century. The Catholic Church, in response to the growing influence and power of modernism, secularism and materialism, formed the First Vatican Council in the late 19th century to deal with such problems an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sugars
Sugar is the generic name for Sweetness, sweet-tasting, soluble carbohydrates, many of which are used in food. Simple sugars, also called monosaccharides, include glucose, fructose, and galactose. Compound sugars, also called disaccharides or double sugars, are molecules made of two Glycosidic bond, bonded monosaccharides; common examples are sucrose (glucose + fructose), lactose (glucose + galactose), and maltose (two molecules of glucose). White sugar is almost pure sucrose. In the body, compound sugars are hydrolysed into simple sugars. Longer chains of monosaccharides (>2) are not regarded as sugars and are called oligosaccharides or polysaccharides. Starch is a glucose polymer found in plants, the most abundant source of energy in human food. Some other chemical substances, such as ethylene glycol, glycerol and sugar alcohols, may have a sweet taste but are not classified as sugar. Sugars are found in the tissues of most plants. Honey and fruits are abundant natural s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inositol
In biochemistry, medicine, and related sciences, inositol generally refers to ''myo''-inositol (formerly ''meso''-inositol), the most important stereoisomer of the chemical compound cyclohexane-1,2,3,4,5,6-hexol. Its elemental formula, formula is ; the molecule has a ring of six carbon atoms, each with a hydrogen atom and a hydroxyl group (–OH). In ''myo''-inositol, two of the hydroxyls, neither adjacent nor opposite, lie above the respective hydrogens relative to the mean plane of the ring. The compound is a carbohydrate, specifically a sugar alcohol (as distinct from aldoses like glucose) with half the sweetness of sucrose (table sugar). It is one of the most ancient components of living beings with multiple functions in eukaryotes, including structural lipids and secondary messengers. A human kidney makes about two grams per day from glucose, but other tissues synthesize it too. The highest concentration is in the brain, where it plays an important role in making other neurot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plant Physiologist
Plant physiology is a subdiscipline of botany concerned with the functioning, or physiology, of plants. Plant physiologists study fundamental processes of plants, such as photosynthesis, respiration, plant nutrition, plant hormone functions, tropisms, nastic movements, photoperiodism, photomorphogenesis, circadian rhythms, environmental stress physiology, seed germination, dormancy and stomata function and transpiration. Plant physiology interacts with the fields of plant morphology (structure of plants), plant ecology (interactions with the environment), phytochemistry (biochemistry of plants), cell biology, genetics, biophysics and molecular biology. Aims The field of plant physiology includes the study of all the internal activities of plants—those chemical and physical processes associated with life as they occur in plants. This includes study at many levels of scale of size and time. At the smallest scale are molecular interactions of photosynthesis and internal diffusion ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sugar Alcohols
Sugar alcohols (also called polyhydric alcohols, polyalcohols, alditols or glycitols) are organic compounds, typically derived from sugars, containing one hydroxyl group attached to each carbon atom. They are white, water-soluble solids that can occur naturally or be produced industrially by hydrogenating sugars. Since they contain multiple groups, they are classified as polyols. Sugar alcohols are used widely in the food industry as thickeners and sweeteners. In commercial foodstuffs, sugar alcohols are commonly used in place of table sugar (sucrose), often in combination with high-intensity artificial sweeteners, in order to offset their low sweetness. Xylitol and sorbitol are popular sugar alcohols in commercial foods. Structure Sugar alcohols have the general formula . In contrast, sugars have two fewer hydrogen atoms, for example, or . Like their parent sugars, sugar alcohols exist in diverse chain length. Most have five- or six-carbon chains, because they are derived r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Académie Des Sciences
The French Academy of Sciences (, ) is a learned society, founded in 1666 by Louis XIV at the suggestion of Jean-Baptiste Colbert, to encourage and protect the spirit of French Scientific method, scientific research. It was at the forefront of scientific developments in Europe in the 17th and 18th centuries, and is one of the earliest Academy of Sciences, Academies of Sciences. Currently headed by Patrick Flandrin (President of the academy), it is one of the five Academies of the . __TOC__ History The Academy of Sciences traces its origin to Colbert's plan to create a general academy. He chose a small group of scholars who met on 22 December 1666 in the King's library, near the present-day Bibliothèque nationale de France, Bibliothèque Nationale, and thereafter held twice-weekly working meetings there in the two rooms assigned to the group. The first 30 years of the academy's existence were relatively informal, since no statutes had as yet been laid down for the ins ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
