标题: X-Ray Phase-Contrast Imaging Reads Rolled Papyri [打印本页] 作者: choi 时间: 1-24-2015 16:03 标题: X-Ray Phase-Contrast Imaging Reads Rolled Papyri Mocella V et al, Revealing Letters in Rolled Herculaneum Papyri by X-Ray Phase-Contrast Imaging. Nature Communications, 6: _ (online publication Jan 20, 2015). www.nature.com/ncomms/2015/150120/ncomms6895/full/ncomms6895.html
Note:
(a) "The explosion of Vesuvius in 79 AD, the most famous eruption of this volcano, destroyed several Roman towns in Campania, especially Pompeii and Herculaneum."
(i) Campania
en.wikipedia.org/wiki/Campania
(The name of Campania itself is derived from Latin, as the Romans knew the region as Campania felix, which translates into English as "fertile countryside”)
(A) Latin English dictionary: felix (adj): “1: happy 2: fertile”
en.wiktionary.org/wiki/felix
(B) Regarding Latin noun “campania,”
* Co-hosting University of Illinois at Urbana–Champaign, Champaign, Illinois
en.wikipedia.org/wiki/Champaign,_Illinois
(in Champaign County [so is Urbana, which is county seat]; Both the city and county name were derived from Champaign County, Ohio)
* Champaign County, Ohio
en.wikipedia.org/wiki/Champaign_County,_Ohio
("Its county seat is Urbana [also]. It takes its name from the French word for 'open level country'")
* The English nouns champaign, campaign and champagne (wine) all descend from this Latin
* champaign (n; etymology): "an expanse of level open country : PLAIN" www.merriam-webster.com/dictionary/champaign
* The champagne wine is produced in Chamoagne region of France. www.etymonline.com/index.php?term=champagne
(ii) Herculaneum
en.wikipedia.org/wiki/Herculaneum
(b) “an entire library was discovered in a small room of a huge villa (thought by some to have belonged to the wealthy Roman statesman Calpurnius Piso Caesoninus”
(i) Villa of the Papyri
en.wikipedia.org/wiki/Villa_of_the_Papyri
(perhaps owned by Julius Caesar's father-in-law, Lucius Calpurnius Piso Caesoninus [c 100 BC – 43 BC])
(ii) papyrus (n; plural: papyri or papyruses; via Latin from Greek) www.oxforddictionaries.com/us/definition/american_english/papyrus
The “i” in “papyri” is the plural form of a Latin noun whereas “es,” English.
(c) “in the last 20 years a great deal of progress has been made in reading the Herculaneum texts that had already been unrolled.”
The emphasis is “unrolled.” If the papyrus remained rolled, the reading can’t be done until now.
(d) “In Antiquity, papyri were written using a black carbon-based ink obtained from smoke residues, the density of which is almost the same as that of the carbonized papyrus.”
(e) "In X-ray computed tomography (XCT) * * * the image contrast mechanism is based on differential X-ray absorption within a compound object. This technique works particularly well for discriminating strongly absorbing materials, such as bone, from weakly absorbing materials such as soft tissues. As the variations [of X-ray absorption] in this case are minimal, XCT does not appear to be a suitable technique, but one promising approach that has proven to overcome these limitations is the X-ray phase-contrast tomography (XPCT) technique. Unlike XCT, XPCT exploits variations in the refractive index (that is, X-ray phase shifts) between structures that absorb quite uniformly within a composite object, thus significantly enhancing the image-contrast effect. * * * As the X-rays propagate from the sample, portions of the wavefront that have experienced different deflections in the sample generate characteristic patterns. Due to Fresnel diffraction, the phase shifts are transformed into measurable intensity variations, which are recorded by a detector located at an appropriately chosen distance." (footnotes omitted)
(i) deflection (n): : "the act of changing or causing something to change direction" www.merriam-webster.com/dictionary/deflection
is a generic term, not used in physics.
(ii) diffraction
en.wikipedia.org/wiki/Diffraction
(occur when a wave encounters an obstacle or a slit; Huygens Fresnel principle)
(f) "The Herculaneum scrolls were burnt by a blast of furnace-like (c 320 °C) gas from the volcano into a vastly homogenous sample matrix. In Antiquity, the most common writing material used for books and other documents was papyrus. The stalks of papyrus plants were cut into thin strips, then two strips were laid atop and perpendicular to one another; these strips were then combined by pressing them until the plant’s natural starch that acted as a paste. The resulting sheets of papyrus were then smoothed and bleached. A papyrus roll consisted of some number of such sheets pasted together end on end. The resulting sheet, which could reach 15 m or more in length, was then rolled up from right to left, so that it could be read from left to right. Papyrus writing material, therefore, consisted of two layers, whose fibres ran perpendicular to one another; the scribe would usually write the text in vertical columns on the side of the papyrus sheet where the horizontal fibres were uppermost. The carbon-based ink he used did not penetrate into the papyrus fibres, but sat atop them. As we shall see, this fact proved to be crucial for our experiments. In general, the letters stand out in slight relief from the papyrus surface * * * The relief of the letters, which rise at least one hundred microns above the surface of the papyrus fibres, is by itself sufficient to produce appreciable phase contrast."
(i) papyrus
en.wikipedia.org/wiki/Papyrus
(ii) "cut into thin strips, then two strips were laid atop and perpendicular to one another"
Go to images.google.com, and search with (papyrus making).