Lead

Lead (/lɛd/) is a chemical element in the carbon group with symbol Pb (from Latin: plumbum) and atomic number 82. It is a soft, malleable and heavy post-transition metal. Freshly cut, solid lead has a bluish-white color that soon tarnishes to a dull grayish color when exposed to air; the liquid metal has shiny chrome-silver luster. Lead is the heaviest (has the highest atomic number) non-radioactive element (two radioactive elements, namely technetium and promethium, are lighter), although the next higher element, bismuth, has one isotope with a half-life that is so long (over one billion times the estimated age of the universe) that it can be considered stable. Lead's four stable isotopes each have 82 protons, a magic number in the nuclear shell model of atomic nuclei. The isotope lead-208 also has 126 neutrons, another magic number, and is hence double magic, a property that grants it enhanced stability: lead-208 is the heaviest known stable nuclide.

Lead is used in building construction, lead-acid batteries, bullets and shot, weights, as part of solders, pewters, fusible alloys, and as a radiation shield.

Cutoff (steam engine)

In a steam engine, cutoff is the point in the piston stroke at which the inlet valve is closed. On a steam locomotive, the cutoff is controlled by the reversing gear.

The point at which the inlet valve closes and stops the entry of steam into the cylinder from the boiler plays a crucial role in the control of a steam engine. Once the valve has closed, steam trapped in the cylinder expands adiabatically. The steam pressure drops as it expands. A late cutoff delivers full steam pressure to move the piston through its entire stroke, for maximum start-up forces. But, since there will still be unexploited pressure in the cylinder at the end of the stroke, this is achieved at the expense of engine efficiency. In this situation the steam will still have considerable pressure remaining when it is exhausted resulting in the characteristic “chuff chuff” sound of a steam engine. An early cutoff has greater thermodynamic efficiency but results in a lower Mean effective pressure so less average force on the piston and is used for running the engine at higher speeds. The steam engine is the only thermodynamic engine design that can provide its maximum torque at zero revolutions per minute.

Lead (disambiguation)

Lead has two different pronunciations and several different meanings, usually related to either the chemical element lead (a heavy metal) or the verb to lead.

When pronounced /ˈlɛd/ (rhymes with "bed")

With this pronunciation, "lead" refers to:

The past tense of the verb to lead is led, pronounced /ˈlɛd/. It is often misspelled as lead.

See also:

When pronounced /ˈliːd/ (rhymes with "need")

With this pronunciation, "lead" generally means "first", "ahead", or "guide":

Sled (TV series)

Sled (translated as Trace; Russian: "След") is a Russian crime drama television series about employees of Federal Expert Service ('FES'), the fictional organization. It was broadcast on the Channel One Russia from September 3, 2007 till August 25, 2011 (Monday – Thursday, night TV broadcast). According to Alexander Levin, Producer, the idea of the TV-series belonged to Konstantin Ernst. From September 5, 2011 premiere episodes broadcast on Petersburg – Channel 5, and show has high ratings.

FES

The show tells the story of new governmental body created in MVD to solve X files and high crimes cases. FES (Russian: "Федеральная экспертная служба") is Federal Expert Service, bringing together specialists in various areas: software development, ballistics, forensic and investigators. FES is doing the whole range of expertise and researches, and it is investigating the most complex and intricate crimes. Launched as an experiment, FES trains young professionals and it assists to other special organizations as FSB and MVDs branches in solving crimes. Any investigator or detective, people from the Prosecutor's Office and a police officer can ask FES for a help. There was futuristic office created especially for shooting: laboratory, a meeting room, a morgue, interrogation room and so on. There was number of cases when Russian citizens complained to FES, because they were not aware that the organization shown in the TV-series was fictional. Press Service of the Ministry of Internal Affairs for the Primorye Territory asked residents to beware of scams that have long posed as employees of FES.

SLED

A sled is a type of sliding vehicle.

SLED or Sled may also refer to: