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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 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 (|ΔG°|) is less than the reorganization parameter (λ).

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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 Thirst and sodium appetite

Regulation of cellular water. ADH = antidiuretic hormone.

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from article Thirst and sodium appetite

Hypovolemic thirst and sodium appetite are caused by altered sensory information from an underfilled circulation, reinforced by increases in circulating angiotensin II and mineralocorticoids. Angiotensin peptides generated from components of a…

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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 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 Platinum

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from article Overvoltage

Current density–potential curve.

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from article Overvoltage

Current density curves. (a) Experimental current–potential curve showing theoretical cathodic and anodic components. (b) Tafel plot.

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from article Radium

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from article Auger electron spectroscopy

Schematic diagram of an Auger electron being ejected from a carbon atom for a KL2L2 transition. Round forms are electrons.

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from article Auger electron spectroscopy

Integral (upper) and differential (lower) mode spectra of sputter-cleaned copper with the most intense peaks identified: A, M2,3M4,5M4,5; B, L3M4,5M4,5; C, L3M2,3M4,5; D, L3M2,3M2,3.

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from article Electromotive force (cells)

Cross-section diagram of Daniell cell. (After W. J. Moore, Physical Chemistry, 5th ed., Longman, 1974)

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from article Speech

Human head and thorax. (Courtesy of G. E. Peterson)

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from article Speech

Action of the glottis during speech. (a) Six successive positions of the vocal folds in one vibration cycle at 120 Hz. (b) Relation between pitch and vocal fold tension. (Courtesy of D. W. Farnsworth)

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from article Speech

Sound spectrograms of the utterance “speech production.” (a) Energy patterns: A, pulse; B, periodic; C, aperiodic; and D, silence. (b) The dotted lines represent the pitch pattern of the utterance.

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from article Speech

Computer-generated three-dimensional spectral display of the spoken syllable “yah.”

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from article Speech

Speech flakes of vowels in the words (a) “far,” (b) “food,” and (c) “fee.” (Courtesy of Charles Wooters)

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from article Speech

Regions of the brain involved in speech. (a) Left hemisphere, usually more involved in speech functions than the right hemisphere. (b) A model for the neural processes involved in speaking a heard word. Arrows indicate the path of the relayed signal…

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from article Organosilicon compound

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from article Art conservation chemistry

Fresco restoration in Casa della Scheletro in Herculanium, Italy. (Credit: National Geographic Image Collection/Alamy)

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from article MXenes

Crystal structures of side views of MXene blocks: (a) M2XTz, (b) M3X2Tz, (c) M4X3Tz.

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from article MXenes

Typical scanning electron microscope micrographs of (a) Ti3AlC2 MAX phase and (b) Ti3C2Tz MLs. (c) Transmission electron microscope micrographs of delaminated single Ti3C2Tz layers.

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from article MXenes

Side view of o-MXenes with chemical formulas (a) M′2M′′2X3Tz, and (b) M′2M′′X2Tz. The M′ and M′′ transition metals are denoted by two different blue spheres and carbon by black.

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from article MXenes

i-MXene (a) side views and (b) top view. Here both M elements are present after etching. (c) Same as (a) but with minority element etched together with Al layers (not shown). (d) Top view of (c) showing ordered divacancies in the basal plane. The…

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from article MXenes

Scanning electron microscope micrograph of (a) vacuum-filtered film of MXene flakes and (b) crumpled MXene flakes formed after aggregation of MXene colloids at high or low pH. Scale bar = 2 μm.

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from article Ligand

The complex hexaammineruthenium(III); the six ammine groups (:NH3) are the ligands.

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from article Ligand

Bidentate ligands. (a) Ethylenediamine (en) and the cobalt coordination complex [Co(en)3]3+ with three en ligands. (b) The bidentate aromatic imine 2,2′-bipyridine (bpy) ligand (highlighted) in the complex Ru(bpy)2imNH2R.

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from article Mental disorders

X-ray of a human brain (side view) against a black background. The image is transparent and detailed with soft blue swaps. (Credit: Brainmaster/Getty Images)

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from article Mental disorders

Colorized CT (computerizd tomography) scan of a healthy brain (view from above). The axial (horizontal) scan has revealed the head and brain in cross section. The front of the head is at the top. The ventricles (dark areas, center), which lie…

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from article Activated carbon