Science & Philosophy: Hydrazones to Incompatibility

Science Encyclopedia

Hydrocarbon - Carbon's Chemical Bonding, Aliphatic Hydrocarbons, Alkanes, Alkenes, Alkynes, Aromatic Hydrocarbons

A hydrocarbon is any chemical compound whose molecules are made up of nothing but carbon and hydrogen atoms. Carbon atoms have the unique ability to form strong bonds to each other, atom after atom. Every hydrocarbon molecule is built upon a skeleton of carbon atoms bonded to each other either in the form of closed rings or in a continuous row like links in a chain. A chain of carbon atoms may be …

3 minute read

Hydrocephalus - Two types of hydrocephalus

Hydrocephalus, which means literally, "water on the brain," is a condition in which excessive fluid collects inside the skull. The fluid is a naturally produced liquid that normally is found in the brain. Accumulation of excessive amounts of the fluid may build pressure to levels that cause brain damage and subsequent disability. The brain rests within the natural bony vault of the c…

5 minute read

Hydrofoil

The hydrofoil is very similar to the hovercraft, because it moves in the boundary between air and water. It avoids drag by lifting itself out of the water, using wing-shaped structures called hydrofoils that extend into the water from the craft. These hydrofoils function like the wings on a plane, creating lift and flying the hull above the surface of the water. The first person to work on this id…

1 minute read

Hydrogen Peroxide

Hydrogen peroxide is most widely found in homes in brown bottles containing 3% solutions (3% hydrogen peroxide and 97% water). The decomposition of hydrogen peroxide happens much faster in the presence of light so that an opaque bottle helps slow this process down. The decomposition of hydrogen peroxide can be summarized by the chemical equation: which states that two molecules of hydrogen pe…

1 minute read

Hydrologic Cycle - Major Compartments And Fluxes Of The Hydrologic Cycle, Hydrologic Cycle Of A Watershed, Influences Of Human Activities On The Hydrologic Cycle

The hydrologic, or water, cycle is the continuous, interlinked circulation of water among its various compartments in the environment. Hydrologic budgets are analyses of the quantities of water stored, and the rates of transfer into and out of those various compartments. The most important places in which water occurs are the ocean, glaciers, underground aquifers, surface waters, and the atmospher…

1 minute read

Hydrology

Hydrology is the science of water. It is concerned with the occurrence and circulation of water on and within Earth, the physical and chemical properties of bodies of water, the relationship between water and other parts of the environment, and societal or economic aspects of water resources. Hydrology is an interdisciplinary field of study, and hydrologists have academic backgrounds that include …

2 minute read

Hydrolysis

Whenever water reacts with another chemical compound, the process is called hydrolysis. Hydrolysis differs somewhat from hydration, although the two can occur together. Hydration is the bonding of whole water molecules to an ion (a charged atom or molecule), usually a metal ion. Hydrolysis, on the other hand, involves an actual chemical reaction of the water molecule itself with another reactant. …

1 minute read

Hydroponics

There are several early examples of hydroponics, or soil-free agriculture, including the hanging gardens of Babylon and the floating gardens of China and Aztec Mexico. Early Egyptian paintings also depict the growing of plants in water. In 1600, the Belgian Jan Baptista van Helmont (1579-1644) demonstrated that a willow shoot kept in the same soil for five years with routine watering gained 160 lb…

1 minute read

Hydrosphere

Hydrosphere refers to that portion of Earth that is composed of water. The hydrosphere represents one component of Earth's system, operating in conjunction with the solid crust (lithosphere) and the air that envelopes the planet (atmosphere). The derivation of the term hydrosphere, from the Greek words for water and ball, is truly descriptive of our world, as it reflects the abundance and i…

2 minute read

Hydrothermal Vents

Hydrothermal vents are places where hot fluids (up to 752°F [400°C]) related to volcanic activity are released from the ocean floor. Because of the high pressure exerted by the water at depth on the sea floor, hydrothermal fluids can exceed 212°F (100°C) without boiling. The most visible indications of on-going volcanic activity are the plumes of hot fluids issuing from…

3 minute read

Hydrozoa

Hydrozoa (phylum Coelenterata, class Hydrozoa) are coelenterates that are closely related to the hydra, sea anemones, corals, and jellyfish. Although a large majority of these species are common and widespread, they are often overlooked, as they are all small animals. The vast majority are marine species, but several freshwater hydrozoans have also been identified, for example, Cordylophora lacust…

1 minute read

Hyena - Species of hyena

Hyenas (or hyaenas) are African and Asian dog-like carnivores in the family Hyaenidae, order Carnivora, which also includes the dogs, cats, seals, and bears. Hyenas are very powerfully built animals with a stout head, a short snout, short ears, and powerful jaws with strong teeth, useful for crushing bones to get at the nutrients contained inside. The neck of the hyena is rather elongate, and the …

6 minute read

Hypertension - Causes And Symptoms, Diagnosis, Treatment, Prognosis - Prevention

Hypertension is high blood pressure. Blood pressure is the force of blood pushing against the walls of arteries as it flows through them. Arteries are the blood vessels that carry oxygenated blood from the heart to the body's tissues. As blood flows through arteries it pushes against the inside of the artery walls. The more pressure the blood exerts on the artery walls, the higher the blood…

4 minute read

Hypothermia - Intentional Hypothermia, Accidental Hypothermia

Hypothermia is the intentional or accidental reduction of core body temperature to below 95°F (35°C) which, in severe instances, is fatal. Because humans are endothermic—warm-blooded creatures producing our own body heat—our core body temperature remains relatively constant at 98.6°F (37°C), even in fluctuating environmental temperatures. However, in extre…

3 minute read

Hyraxes

Hyraxes are rabbit-sized, hoofed African mammals that surprisingly share a common ancestry with elephants and manatees, or seacows. Hyraxes were originally thought to be rodents, and were later grouped with rhinoceroses. They are now placed in an order of their own, the Hyracoidea, since they share many common features of primitive ungulates. The fossil record indicates that hyraxes were the most …

3 minute read

Ibises - Habitat And Behavior, Historical References

Ibises are grouped together with large wading birds such as storks, herons, flamingos, and spoonbills, in the order Ciconiiformes. Ibises, like most birds in this order, have long legs and a long bill for feeding on fish and aquatic animals in shallow water. They also have broad wings, a short tail, and four long toes on each foot. The 26 species of ibis share the family Threskiornithidae with the…

1 minute read

Ice - Structure Of Ice, Physical Properties Of Ice, Natural Ice Occurrence, Current Glaciology Research

Ice is the solid state of water. The great abundance of water on the surface of Earth includes a great quantity of ice in the Polar Regions and high elevations. The relative proportion of each of the three states of water on Earth is a delicately balanced equilibrium controlled by the amount of incoming solar energy and the amount of reflection, known as Aledo, from clouds, water, ice caps, etc. T…

less than 1 minute read

Ice Age Refuges

The series of ice ages that occurred between 2.4 million and 10,000 years ago had a dramatic effect on the climate and the life forms in the tropics. During each glacial period the tropics became both cooler and drier, turning some areas of tropical rain forest into dry seasonal forest or savanna. For reasons associated with local topography, geography, and climate, some areas of forest escaped th…

3 minute read

Ice Ages - The Most Recent Ice Era, Evidence For The Ice Ages, Causes Of The Ice Ages

The ice ages were periods in Earth's history during which significant portions of Earth's surface were covered by glaciers and extensive fields of ice. Scientists sometimes use more specific terms for an ice "age" depending on the length of time it lasts. It appears that over the long expanse of Earth history, seven major periods of severe cooling have occurred. These p…

4 minute read

Icebergs

An iceberg is a large mass of free-floating ice that has broken away from a glacier. Beautiful and dangerous, icebergs wander over the ocean surface until they melt. Most icebergs come from the glaciers of Greenland or from the massive ice sheets of Antarctica. A few icebergs originate from smaller Alaskan glaciers. Snow produces the glaciers and ice sheets so, ultimately, icebergs originate from …

6 minute read

Iconography - Historical Development, Cesare Ripa (fl. 1593), Émile MÂle (1862–1954), Erwin Panofsky (1892–1968)

Iconography is the description, classification, and interpretation of the subject matter of a work of art. Derived from the Greek words eikon, meaning image or icon, and graphia, meaning description, writing, or sketch, the word iconography is one of the least understood, most abused, and most flexible terms in the English language. Its primary purpose is to understand and explicate the meaning be…

2 minute read

History of Ideas - Bibliography

The "history of ideas," phrase and concept, goes back almost three centuries to the work of J. J. Brucker (1696–1770) and Giambattista Vico (1668–1744) in the early eighteenth century, followed in the nineteenth century by Victor Cousin (1792–1867) and his eclectic and "spiritualist" philosophy. The story begins with Brucker's Historia doctri…

7 minute read

Identity Element

Any mathematical object that, when applied by an operation, such as addition or multiplication, to another mathematical object, such as a number, leaves the other object unchanged is called an identity element. The two most familiar examples are 0, which when added to a number gives the number, and 1, which is an identity element for multiplication. More formally, an identity element is defined wi…

less than 1 minute read

Igneous Rocks

Igneous rocks are formed by the cooling and hardening of molten material called magma. The word igneous comes from the Latin word igneus, meaning fire. There are two types of igneous rocks: intrusive and extrusive. Intrusive igneous rock forms within Earth's crust; the molten material rises, filling voids in the crust, and eventually hardens. Intrusive rocks are also called plutonic rocks, …

3 minute read

Iguanas - Classification And Characteristics, Distribution And Diet, Reproduction, Display Patterns As Attractions And Deterrents, Popularity And Extinction

Iguanas are large, ancient, herbivorous lizards with a stocky trunk, long, slender tail, scaly skin, and a single row of spines from the nape of the neck to the tip of the tail. On either side of the head is an eye with a round pupil and with moveable lids. The well-defined snout has two nostrils, the mouth houses a short, thick tongue, and dangling beneath the chin is a "dewlap," or…

less than 1 minute read

Icons Images and Idols - Sacred Image, Icon As Revelation, Idol And Idolatry, Islam And Shirk, To See Her Face

Placing the words images, icons, and idols together as the subject of an entry that seeks to articulate the perspective of world culture suggests their intimate relationship. Such a grouping also demands that an emphasis be placed on the particular role biblical religions have had in the development and use of the last two terms, the ideas of "icon" and "idol" that play…

less than 1 minute read

Imaginary Number

In addition to providing solutions for algebraic equations, the imaginary numbers, when combined with the real numbers, form the complex numbers. Each complex number is the sum of a real number and an imaginary number, such as (6 + 9i). The complex numbers are very useful in mathematical analysis, the study of electricity and magnetism, the physics of quantum mechanics, and in the practical field …

1 minute read

Immortality and the Afterlife - Bibliography

Indeed, in the early twenty-first century, Nicholas Smith has argued that Plato's views in the Republic seem to be intended to provoke thought rather than to set forth consistent views. As such, we should not be surprised that in Plato's work another "view" of immortality can be found. Plato's Symposium offers this alternative view. Here Plato's Socrates r…

10 minute read

Immune System - Organs Of The Immune System, Specific Immune Defenses, A Closer Look At Antibodies - Overview of the immune system, The non-specific defenses, How antibodies work to destroy invaders

The immune system protects the body from diseasecausing microorganisms. It consists of two levels of protection, the non-specific defenses and the specific defenses. The non-specific defenses, such as the skin and mucous membranes, prevent microorganisms from entering the body. The specific defenses are activated when microorganisms evade the non-specific defenses and invade the body. The human bo…

13 minute read

Impact Crater

The impact crater is typically the most common type of landform seen on the surface of most of the rocky and icy planets and satellites in our solar system. Impact craters form when a minor planetary body (meteoritic fragment, asteroid, or comet) strikes the surface of a larger body or major planet. A physical scar is excavated on the surface and much energy is dispersed in the process. Most impac…

6 minute read

Imprinting - Genomic Imprinting, Behavioral Imprinting

Imprinting is a term used to describe two very distinct processes. Genomic imprinting is an epigenetic chromosomal modification that describes the preferential expression of a specific parental form of a gene (allele). Imprinting is also a term used in the behavioral science to describe a learning process during which a younger animal identifies with, and adopts behaviors exhibited by, other anima…

1 minute read

In Vitro Fertilization (IVF) - Precautions, Description, Preparation, Risks, Normal Results - Aftercare, Abnormal results

In vitro fertilization (IVF) is a procedure in which eggs (ova) from a woman's ovary are removed, fertilized with sperm in a laboratory procedure, and then the resulting fertilized egg (embryo) is returned to the woman's uterus. Human fertilization in vivo (in the living body) occurs in oviducts (fallopian tubes) of the female reproductive tract. IVF is a procedure of assisted reprod…

3 minute read

In Vitro and in Vivo

The definition of in vitro and in vivo research depends on the experimental model used. In vitro research is generally referred to as the manipulation of organs, tissues, cells, and biomolecules in a controlled, artificial environment. The characterization and analysis of biomolecules and biological systems in the context of intact organisms is known as in vivo research. The basic unit of living o…

3 minute read

Incandescent Light - History Of Incandescent Lamps, Design, Applications

Incandescent light is given off when an object is heated until it glows. To emit white light, an object must be heated to at least 1,341°F (727°C). White-hot iron in a forge is incandescent, as is red lava flowing down a volcano, as are the red burners on an electric stove. The most common example of incandescence is the white-hot filament in the light bulb of an incandescent lamp. T…

5 minute read