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Project

1-Wire Weather Station

The weather station in this project is quite basic, measuring only temperature, pressure, and humidity, but it may be easily expanded to measure other weather components, such as wind speed and rainfall. The design is based on using a series of…

Project

3x3x3 LED Cube

LEDs (light-emitting diodes) are rectifying semiconductor devices that convert electrical energy into electromagnetic radiation. You can use these devices to create a 3-dimensional light display. LED cubes require some care and good soldering skills…

Project

Chatbot, an Artificially Intelligent Microcontroller

The term "Chatbot" is used for a computer or computer program that is made to emulate some form of human intelligence through conversation. In this project, you will learn how easy it is to make a specific microcontroller—an Arduino™ Uno—seem as…

Project

Text-Controlled RGB LED

A red, green, and blue (RGB) light-emitting diode (LED) is a useful electronic component that can produce visible light in a variety of colors. This is done by varying the intensity of the light output of the three different color LED elements (red,…

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from article Octopoda

An octopod swimming in the ocean. (Credit: Getty Images/iStockphoto)

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from article Octopoda

Hapalochlaena maculosa, the Southern or lesser blue-ringed octopus, has vivid, small blue rings on its body and arms, highlighted with black outlines. Location: Mrs. Watson's Bay, Lizard Island, Great Barrier Reef, Australia. (Credit: Clyde F. E.…

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from article Octopoda

Hapalochlaena fasciata, the blue-lined octopus, has vivid blue lines on its body and rings on its arms, highlighted with black outlines. Location: Long Reef, New South Wales, Australia. (Credit: Clyde F. E. Roper)

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from article Octopoda

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from article Polyplacophora

Chiton on a rock surface. (Photo courtesy of the NOAA Okeanos Explorer Program, National Oceanic and Atmospheric Administration)

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from article Polyplacophora

Polyplacophoran mollusk (chiton): (a) dorsal view; (b) ventral view.

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from article Eclipse

The August 21, 2017 total solar eclipse, as seen from Hopkinsville, Kentucky, USA at 2:25 p.m. EDT. (Credit: NASA)

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from article Eclipse

Circumstances of solar and lunar eclipses (not to scale).

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from article Eclipse

Diamond-ring effect at the beginning of totality during the solar eclipse of July 11, 2010, observed from Easter Island in the middle of the Pacific Ocean. (Credit: Jay M. Pasachoff/Science Faction, Muzhou Lu, and Craig Malamut, Williams College…

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from article Eclipse

Total solar eclipse of July 11, 2010, observed from Easter Island in the Pacific Ocean. (a) Image composited from several exposures using radial filters in order to show a wide dynamic range of intensity of the corona and to bring out the structures…

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from article Eclipse

Solar eclipse of April 8, 2005, observed during totality from a ship in the mid-Pacific Ocean, west of the Galápagos Islands. (Credit: Jay M. Pasachoff and Dava Sobel/Science Faction)

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from article Eclipse

Paths of all total solar eclipses from 2001 through 2025. The point of greatest eclipse is indicated by an asterisk on each eclipse path. (Credit: Eclipse map by Michael Zeiler, www.eclipse-maps.com. Eclipse paths by Xavier Jubier, xjubier.free.fr.)

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from article Eclipse

Cross section through the Earth's shadow cone (umbra) at the Moon's distance, showing the motion of the Moon at three types of lunar eclipses: penumbral eclipse, partial umbral eclipse, and total umbral eclipse.

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from article Eclipse

Stages of the total lunar eclipse of December 21, 2010. (Credit: Glenn Schneider)

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from article Eclipse

Total lunar eclipse of December 9, 1992, which was so dark that it rendered the Moon nearly invisible during totality. (Credit: F. Espenak)

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from article Strychnos

Strychnos nux-vomica: close-up view of leaves and flowering branch. (Photo courtesy of Dinesh Valke)

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from article Clathrate compounds

Schematic drawing of the lattices of (a, c) urea and (b, d) thiourea; c and d show accommodation of unbranched and branched paraffin chains, respectively.

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from article Clathrate compounds

Molecular model of α-dextrin–iodine compound seen in the direction of the c axis, that is, in the direction of the iodine chains, which lie in channels.

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from article Aconchulinida

Aconchulinida. (a) Penardia cometa. (b) Penardia mutabilis.

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from article Siphonaptera

Head of Spilopsyllus cuniculi (rabbit flea), with extended mouthparts.

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from article Planet

An artist’s impression of a mere sampling of the planetary diversity expected to exist in nature. [Credit: C. Pulliam & D. Aguilar (CfA)]

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from article Planet

Plan of the solar system's major and dwarf planets. (a) Solar system out to Neptune. (b) Dwarf planets in the outer solar system (Credit: Emily L. Schaller)

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from article Planet

Orbital elements, which determine the position of a planet in its orbit and the orientation of the orbit in space. Symbols explained in text.

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from article Planet

The interiors of the 8 planets and the dwarf planet Pluto. Mercury, Venus, Earth, and Mars are characterized by dense, metallic cores and lower-density mantles and crusts. Jupiter and Saturn have compositions that mimic the Sun's, though…

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from article Planet

Complex lunar crater Bullialdus, 60 km (37 mi) in diameter, shows terraced sides, a central peak, and a flat bottom. It may be compared to the small (less than 8 km or 5 mi) crater in the foreground, which is simple and bowl-shaped. (Credit: NASA)

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from article Planet

Ultraviolet images from the Hubble Space Telescope, which reveal auroral emission surrounding the north magnetic pole of Jupiter. [Credit: NASA, ESA, and J. Nichols (University of Leicester)]

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from article Breadfruit

Breadfruit (Artocarpus altilis), showing the rounded (or elliptic) fruit and the cylindrical staminate flower cluster. (Photo courtesy of Forest and Kim Starr)

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from article Wilkinson Microwave Anisotropy Probe

Wilkinson Microwave Anisotropy Probe (WMAP) spacecraft. (Courtesy of NASA/WMAP Science Team)

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from article Wilkinson Microwave Anisotropy Probe

WMAP sky-scan strategy. (a) Location of the satellite relative to the Earth and Sun (not to scale), and the orientation of the satellite and of the lines of sight to the spots on the sky focused by the primary reflectors, which continually changed…

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from article Wilkinson Microwave Anisotropy Probe

WMAP full-sky CMB anisotropy map. The microwaves captured in this picture from WMAP are from when the universe was 378,000 years old, over 13 × 109 years ago. It is a “baby picture” of the universe, equivalent to taking a picture of an 80-year-old…

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from article Digenea

Diagrams of various adult types of digenean trematodes. (After R. M. Cable, An Illustrated Laboratory Manual of Parasitology, Burgess, Minneapolis, 1940)

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from article Digenea

Digenean trematode life cycle. (After R. M. Cable, An Illustrated Laboratory Manual of Parasitology, Burgess, Minneapolis, 1940)

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from article Hydroponics

Green- and red-leaf lettuce growing in a hydroponic vegetable garden on a bamboo fence. The pipes, which supply nutrients and water, are part of the hydroponic system. (Credit: Piyachok Thawornmat, Shutterstock)

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from article Hydroponics

Hydroponic techniques: (a) aerated standing culture; (b) flowing-solution culture with standing solution; (c) nutrient film technique; (d) aeroponics.

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from article Mango

Tommy Atkins cultivar of mango (Mangifera indica) growing in Florida. (Credit: Wilhelmina Wasik/Agricultural Research Service, U.S. Department of Agriculture)

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from article Tomato

Tomatoes (Solanum lycopersicum). (Credit: Peggy Greb, Agricultural Research Service, U.S. Department of Agriculture)

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from article Tomato

Tomato affected by anthracnose (caused by the fungus Colletotrichum phomoides). (Credit: U.S. Department of Agriculture Cooperative Extension Slide Series, Clemson University)

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from article Tomato

Tomatoes showing blossom-end rot. (Credit: Mary Ann Hansen, Virginia Polytechnic Institute and State University)

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from article Electrolysis

Electrolysis cell in which the electrolyte is a solution of sodium chloride.

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from article Pine nut

Pine nuts in their hard shell (Mexican piñon pine, Pinus cembroides). (Photo by Steve Hurst, U.S. Department of Agriculture–Natural Resources Conservation Service PLANTS Database)

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from article Pine nut

Cone containing pine nuts (stone pine, Pinus pinea). (Photo by Vito Buono, Bari, Italy)

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from article Ultracentrifuge

Diagram of an electrically driven analytical ultracentrifuge. (Beckman Instruments)

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from article Ultracentrifuge

Analytical rotor. (Beckman Instruments)

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from article Ultracentrifuge

Fixed-angle preparative rotor and tubes. (Beckman Instruments)

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from article Ctenothrissiformes

A Cretaceous ctenothrissiform fossil, Ctenothrissa sp. (order Ctenothrissiformes), on a limestone matrix found in Lebanon. Size: 90 mm (3.5 in.). (Photo courtesy of The Virtual Fossil Museum)

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from article Acari

Parasitiformes body plan. Lateral view of a predatory adult female Mesostigmata showing major body regions and important structures. Scale bar = 0.1 mm (0.004 in.). (Scanning electron micrograph by D. E. Walter)

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from article Acari

Acariformes body plan. (a) Adult female Oribatida (Sarcoptiformes) in lateral view showing major body regions and important structures. (b) Hexapod larva (Trombidiformes): dorsal view of a chigger, a parasite of vertebrates. (c) Octopod deutonymph…

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from article Triple point

Phase diagram for water, showing gas, liquid, and several solid (ice) phases; triple points at A, B, and C. The pressure scale changes at 101 kilopascals from logarithmic scale at low pressure to linear at high pressure.

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from article Macrocyclic compound

Macrocyclic structures. (a) Two crown ethers. (b) A basic structure for three cryptands. (c) A lariat ether. (d) All-aliphatic spherand. (e) All-aromatic spherand.

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from article Macrocyclic compound

Macrocycles with various structural features. (a) Bicyclic cryptand (ditopic receptor). (b) Calix[6]arene; R represents a functional group. (c) Cavitand. (d) Carcerand. (e) Cyclophanes.

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from article Macrocyclic compound

Tetramers. (a) Resorcinarene having the rctt conformation. (b) Pyrogallolarene having the rccc conformation.

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from article Macrocyclic compound

The metal cation is the guest and the organic structure is the host in (a) 18-crown-6 complex of potassium cation (K+) and (b) sodium (Na+) complexed by a calix[4]arene.

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from article Macrocyclic compound

Complexing species. (a) Dibinaphtho-22-crown-6. (b) R,R-dibinaphtho-22-crown-6 complex of phenethylammonium chloride.

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from article Macrocyclic compound

Affinities for anions and cations shown for (a) pyrrole and (b) furan-derived cyclic tetramers.

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from article Macrocyclic compound

Amphiphiles. (a) Crown ether-steroid amphiphile. (b) Crown ether bolaamphiphile.

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from article Salicylate

Chemical structures of (a) salicylate, the conjugate base of (b) salicylic acid, and the nonsteroidal anti-inflammatory drug (NSAID) (c) acetylsalicylic acid (aspirin).

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from article Poplar

Quaking aspen (Populus tremuloides). (Photo courtesy of North Dakota State Soil Conservation Committee, USDA–NRCS PLANTS Database)

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from article Poplar

Common poplar species. (a) Quaking aspen (P. tremuloides); leaf scar with an axial bud, leaf, and twig. (b) Bigtooth aspen (P. grandidentata); leaf, terminal bud, and twig. (c) Cottonwood poplar (P. deltoides); leaf, leaf scar, terminal bud, and…

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from article Marcus equation

Free-energy plot for an electron-transfer reaction with zero standard free-energy change (an electron self-exchange reaction).

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from article Marcus equation

Free-energy plot for an electron-transfer reaction when the free-energy change (|Δ G °|) is less than the reorganization parameter (λ).

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from article Haplosporida

Spore of Urosporidium fuliginosum.

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from article Haplosporida

Stages in the development of Icthyosporidium giganteum.

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from article Lead

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from article Lead

Galena (lead sulfide, PbS) is an ore mined for lead. (Credit: USGS)

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from article Oxygen toxicity

The dual effect of oxygen on biologic activity. Organisms that avail themselves of the enormous metabolic advantages provided by dioxygen (O2) must defend themselves against its toxicity. (Copyright © McGraw Hill)

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from article Transmission lines

Two common transmission lines for communication. (a) Coaxial cable. (b) Strip line.

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from article Transmission lines

Equivalent circuit that represents three sections of a lossless transmission line. Each section is of length Δz, and has an inductor (L) and capacitor (C). Voltages (V ) and currents (I ), and their differences (ΔV and ΔI ) between successive…

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from article Transmission lines

Signal detection on an oscilloscope. (a) Oscilloscope pictures of voltage pulses at three locations, z1, z2, and z3, on a transmission line, successively more distant from the signal generator. (b) Oscilloscope pictures of a periodic voltage sine…

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from article Transmission lines

Transmission line with characteristic impedance Zc, terminated in a load impedance ZL. A change of coordinate system (from z to ζ) is indicated.

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from article Transmission lines

Envelope of the voltage standing wave consisting of a wave propagating from z = −∞ and being reflected at z = 0. The wavelength, λ, and the maximum and minimum voltages, Vmax and Vmin , are indicated.

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from article Transmission lines

Two waveguides, with conventional coordinates. (a) Rectangular waveguide. (b) Cylindrical waveguide.

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from article Transmission lines

Dispersion curve for a rectangular waveguide of width a, showing relationship between the propagation constant, β, and the angular frequency, ω. Here, n specifies the mode of propagation, and c is the speed of light.

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from article Transmission lines

Equivalent circuit of a power transmission line. The single-phase circuit is used to represent balanced three-phase lines. Here, R and X are the resistance and reactance (at the operational frequency), and C is the capacitance of the entire…

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from article Urodela

A typical member of the order Urodela: the longtail salamander (Eurycea longicauda). (Credit: Ryan Hagerty/U.S. Fish and Wildlife Service)

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from article Urodela

Southern dwarf siren (Pseudobranchus axanthus), which has undergone limb degeneration and retains only tiny forelimbs. (Credit: U.S. Geological Survey)

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from article Urodela

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from article Urodela

California tiger salamander (Ambystoma californiense). (Credit: John Cleckler/U.S. Fish and Wildlife Service)

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from article Urodela

The two-toed amphiuma salamander (Amphiuma means). (Credit: Southeast Ecological Center, U.S. Geological Survey)

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from article Urodela

The northern red salamander (Pseudotriton ruber ruber) is a member of the family Plethodontidae. (Credit: Alicia Lafever/U.S. National Park Service)

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from article Chamois

Alpine chamois (Rupicapra rupicapra). (Photograph courtesy of Brent Huffman/Ultimate Ungulate Images)

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from article Chicxulub impact crater

Bouguer gravity anomaly map over the Chicxulub impact crater. The coastline is designated by a thin white line, cenotes (natural pits) and sinkholes are designated by black dots, and the city of Mérida and the town of Chicxulub Puerto are designated…

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from article Chicxulub impact crater

Seismic line imaging of what lies beneath the seafloor, showing the Chicxulub impact crater. The crater includes many faults that can be grouped into an exterior ring fault, a series of outer ring faults, and a series of inner ring faults. Within…

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from article Bioassay

In conducting bioassays, researchers often employ laboratory culture tests, which use, for example, bacteria cultured in a petri dish (usually to model an effect on the organism of interest or on some basic cellular function). (Credit:…

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from article Surfactant

Foam blankets typically contain less than 1% surfactant to produce a stable foam that blocks oxygen for fire suppression. (Credit: U.S. Navy)

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from article Amniota

Basic types of vertebrate eggs.

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from article Amniota

Embryo developing in amniote eggs.

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from article Osage orange

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from article Mecoptera

Male scorpion fly (Panorpa), order Mecoptera.

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from article Matrix isolation

Vacuum-vessel base cross section for matrix photoionization experiments. 10 K = −263°C or −442°F.

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from article Matrix isolation

Schematic plan view of the matrix assembly for pulsed-laser ablation.

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from article Matrix isolation

Infrared and Raman spectra of lithium superoxide, Li+O2−, using lithium-7 and 30% 18O2, 50% 16O18O, and 20% 16O2 at concentrations of Ar/O2 = 100. The Raman spectrum was recorded by using 200 mW of 488-nm excitation at the sample.

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from article Matrix isolation

Visible and ultraviolet absorption spectra of naphthalene samples in solid argon at 20 K. Upper curves show Ar/CCl4/N = 3000/4/1, and lower curves show the same sample after 15 s of irradiation at 220–1000 nm from a high-pressure mercury arc.

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from article Matrix isolation

Infrared spectra in the 2000–1200 cm−1 region for the products of the reactions of laser-ablated Al atoms with pure hydrogen co-deposited at 3.5 K. (a) Spectrum obtained from initial deposited sample. (b) Spectrum after >290 nm irradiation. (c)…

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from article Magnolia

Flowers and leaves of the southern magnolia (Magnolia grandiflora). (Photo courtesy of Forest and Kim Starr)

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from article Ursa Minor

Modern boundaries of the constellation Ursa Minor, the Little Bear. The celestial equator is 0° of declination, which corresponds to celestial latitude. Right ascension corresponds to celestial longitude, with each hour of right ascension…

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from article Hackberry

Hackberry (Celtis occidentalis). (Credit: North Dakota State Soil Conservation Committee, USDA–NRCS PLANTS Database)

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1-Wire Weather Station

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