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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

3D Floor Plan

Floor plans show walls, windows, doors, and other features of a room or building. Architects and engineers use them to study spatial relationships and describe their designs. Typically, floor plans are rendered as two-dimensional drawings.In this…

Project

3D Skull Candy Mold

Whether preparing for Halloween or just a regular day, you can make skull-shaped edibles from this project's 3D candy mold. Like many molds, this one is a hollow container into which you can pour water or hot liquids, such as gelatin, chocolate, or…

Project

3D Spur Gear

A spur gear is a common toothed wheel that works with other wheels in a set to adjust the speed, power, or direction of a complex machine. It's found in many everyday devices, such as electric screwdrivers, washing machines, and mechanical clocks…

Project

3D Terrain Map

Terrain maps are physical models that give you an at-a-glance overview of landforms. Architects, builders, and engineers often use these types of maps to provide context to proposed building designs. In this project, you'll create a layered…

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

Arduino Oscilloscope

An oscilloscope is a device that allows you to see an electronic signal so that it appears as a waveform. Traditional oscilloscopes work by amplifying a signal to control the position of a dot on the y-axis (vertical axis) of a cathode-ray tube…

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

Heart-Rate Monitor

This project uses a sensitive light-detecting resistor to detect small changes in the light beaming through your finger as your blood pumps through tiny arteries in the finger. This device is not the same as the heart-rate monitors typically used in…

Project

Jumbo Foam Glider

This project takes you through the steps to build, launch, and fly a foam glider in sustained and controlled flight. Control in flight is achieved by modifying the wind the glider flies through with a large cardboard sheet (paddle). If this is your…

Project

Laser-Grid Intruder Alarm

This is a working alarm. It uses a laser beam that bounces between mirrors attached to two walls that face each other. The figure to the right has been digitally edited to show the path of the beam. When the beam is broken, a buzzer sounds.This…

Project

Levitation Machine

This project allows you to use electromagnetic levitation to suspend a globe of the world above a surface. The "globe" is actually a table tennis ball painted to look like a globe. Keeping it in place requires careful control of electrical current…

Project

Light and Temperature Logger

Environmental research often involves the use of data loggers to record data at regular intervals over a period of time. Most data loggers are based on digital processors, and can be fairly expensive, but you can build your own. This project uses a…

Project

Pulse Generator Circuits

A pulse generator circuit is an important building block for many electronic projects, such as the heart of a digital clock. Its purpose is basically to switch an output on and off for as long as the circuit is activated. Sometimes, these circuits…

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,…

Project

Theremin-like Instrument

A theremin is a musical instrument developed in the 1920s by the Russian inventor, Léon Theremin. It was one of the world's first electronic musical instruments. The original invention used radio-frequency electronics and a pair of antennae. By…

Project

Tumblewing Walkalong Glider

This project takes you through the steps to build, launch,and fly a paper airplane (glider) in sustained and controlled flight. Control in flight is achieved by modifying the wind the glider flies through with a large cardboard sheet or foam board…

Project

Ultralight Foam Glider

This project takes you through the steps to build, launch, and fly an ultralight foam glider in sustained and controlled flight. Controlled flight is achieved by modifying the wind the glider flies through with a large cardboard sheet, or paddle.The…

Project

White-Noise Generator

White noise is a smooth hiss consisting of all audio frequencies played back at random simultaneously. Because your ears cannot "lock" onto any specific frequencies or patterns in white noise, this device has the effect of shutting off your ears to…

Project

Wind Lantern

In this project, you will build a small, vertical-axis wind turbine, or VAWT for short. VAWTs are not as efficient as their horizontal-axis cousins, but they are better suited to urban environments where wind can come from different…

Project

Constant-Speed Vehicle

Everything in the universe is in motion. One basic, yet important, type of motion is constant-speed motion. This project takes you through assembly of a model battery-powered vehicle that moves at a constant speed. This particular vehicle is built…

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from article Microtechnique

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Materials and method for applying cover slip to balsam wholemount. (a) Correct way; notice that the cover slip is held vertically centered over the drop of balsam. (b) Wrong way; this method draws the object to one side. (After P. Gray, Handbook of…

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from article Microtechnique

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Making a smear preparation. (a) Place the drop about 1 in. (2.5 cm) from end of slide. (b) Apply a second slide just in front of the drop. (c) Push slide smoothly forward to spread the smear. (After P. Gray, Handbook of Basic Microtechnique, 3d ed.,…

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from article Microtechnique

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Rotary microtome produced by the American Optical Co. (From P. Gray, Handbook of Basic Microtechnique, 3d ed., McGraw-Hill, 1964)

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from article Microtechnique

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Method of mounting the wax block on the block holder. (After P. Gray, Handbook of Basic Microtechnique, 3d ed., McGraw-Hill, 1964)

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from article Microtechnique

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Basic steps in cutting and mounting paraffin ribbons prior to staining. (a) Starting the ribbon. (b) Cutting the ribbon in lengths. (c) Mounting the dry ribbon. (d) Flooding the ribbons. (e) Warming the flooded ribbons to flatten them. (After P.…

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from article Microtechnique

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Coplin jars for starting a slide through the reagent series. (After P. Gray, Handbook of Basic Microtechnique, 3d ed., McGraw-Hill, 1964)

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from article Absorption

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Incident sunlight is absorbed, reflected, and scattered by tree leaves. (Credit: Shutterstock / photolinc)

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from article Capricornus

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Modern boundaries of the constellation Capricornus, the Sea Goat. The celestial equator is 0° of declination, which corresponds to celestial latitude. Right ascension corresponds to celestial longitude, with each hour of right ascension representing…

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from article Bioorganic chemistry

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Vancomycin and an analog that is active against vancomycin-resistant bacteria.

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from article Bioorganic chemistry

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The rate of this intramolecular lactonization, relative to that of intermolecular esterification, mimics the rate increase caused by an enzyme's binding and orienting substrates for a bimolecular reaction.

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from article Bioorganic chemistry

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Intramolecular models of enzymatic general acid and general base catalysis. (a) Intramolecular general acid catalysis causes this acetal to hydrolyze at pH 7 more than 107 times faster than the corresponding acetal without the carboxylic acid group.…

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from article Bioorganic chemistry

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An antibody raised against the phosphonate analog of a tetrahedral intermediate catalyzes the hydrolysis of cocaine to ecgonine methyl ester.

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from article Bioorganic chemistry

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A functionalized cyclodextrin mimics the enzyme RNase by catalyzing the regioselective hydrolysis of a model phosphodiester.

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from article Bioorganic chemistry

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Enzyme-catalyzed reactions that have been commercialized as industrial processes.

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from article Bioorganic chemistry

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Mechanism of DNA scission by calicheamicin. Reductive or nucleophilic cleavage of the trisulfide triggers conjugate (Michael) addition to the enone, rehybridization of the bridgehead carbon, and Bergman cyclization of the enediyne, generating a…

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from article Negative temperature

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Populations (n) of states of a thermodynamic system consisting of N magnetically interacting nuclei of spin 2 at absolute temperatures T = +D/k and T = −D/k, where k is Boltzmann's constant and D is the energy spacing between successive states.

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from article Type 1 diabetes

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One characteristic feature of type 1 diabetes is glomerulosclerosis (Kimmelstiel-Wilson lesion), which involves the scarring or hardening of the glomeruli (blood vessels) in the kidneys. (Copyright © McGraw-Hill Education)

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from article Type 1 diabetes

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Stages in the development of type 1 diabetes. (Credit: Type 1 Diabetes TrialNet)

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from article Parathyroid gland

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Common positions of human parathyroid glands on the posterior aspect of the thyroid. (After W. H. Hollinshead, Anatomy of the endocrine glands, Surg. Clin. N. Amer., 32(4):1115–1140, 1952)

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from article Parathyroid gland

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Section of human parathyroid gland, demonstrating the two main parenchymal cell types. Zenker-formal fixation, Mallory-azan stain. (After D. Bloom and D. W. Fawcett, A Textbook of Histology, 9th ed., Saunders, 1968)

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from article Geotechnical engineering

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Mike O'Callaghan-Pat Tillman Memorial Bridge over the Colorado River at the Hoover Dam, spanning Nevada and Arizona, USA. Geotechnical engineering of the bridge site included 3D laser scanning of the canyon walls, geologic mapping, core drilling,…

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from article Tanaidacea

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Leviapseudes bipartitus. [K. Larsen, Deep-Sea Tanaidacea (Peracarida) from the Gulf of Mexico, Brill, Leiden, 2005]

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from article Tanaidacea

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Typhlotanais ohtsukae: (top) female; (bottom) male. [K. Larsen and M. Shimomura, Tanaidacea (Crustacea: Peracarida) from Japan: II. Tanaidomorpha from the East China Sea, the West Pacific Ocean and the Nansei Islands, Zootaxa, 1464:1–43, 2007]

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from article Rock mechanics

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Typical rock mass containing numerous discontinuities. The person in picture is conducting a scanline survey, where a tape is placed across the rock and detailed information is gathered on the fractures that intersect the scanline.

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from article Rock mechanics

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(a) Uniaxial compression test, where an axial stress is applied to a core sample of rock and increased until failure. (b) Triaxial compression test, where a constant confining stress is first applied, then the axial stress is increased until failure.

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