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Calcium fragment 39/27/2023 ![]() Historically, it had been assumed that when lime was incorporated into Roman concrete, it was first combined with water to form a highly reactive paste-like material, in a process known as slaking. Upon further characterization of these lime clasts, using high-resolution multiscale imaging and chemical mapping techniques pioneered in Masic’s research lab, the researchers gained new insights into the potential functionality of these lime clasts. “If the Romans put so much effort into making an outstanding construction material, following all of the detailed recipes that had been optimized over the course of many centuries, why would they put so little effort into ensuring the production of a well-mixed final product? There has to be more to this story.” “The idea that the presence of these lime clasts was simply attributed to low quality control always bothered me,” says Masic. Previously disregarded as merely evidence of sloppy mixing practices, or poor-quality raw materials, the new study suggests that these tiny lime clasts gave the concrete a previously unrecognized self-healing capability. “These are not found in modern concrete formulations, so why are they present in these ancient materials?” “Ever since I first began working with ancient Roman concrete, I’ve always been fascinated by these features,” says Masic. These white chunks, often referred to as “lime clasts,” originate from lime, another key component of the ancient concrete mix. Under closer examination, these ancient samples also contain small, distinctive, millimeter-scale bright white mineral features, which have been long recognized as a ubiquitous component of Roman concretes. This specific kind of ash was even shipped all across the vast Roman empire to be used in construction, and was described as a key ingredient for concrete in accounts by architects and historians at the time. The findings are published today in the journal Science Advances, in a paper by MIT professor of civil and environmental engineering Admir Masic, former doctoral student Linda Seymour ’14, PhD ’21, and four others.įor many years, researchers have assumed that the key to the ancient concrete’s durability was based on one ingredient: pozzolanic material such as volcanic ash from the area of Pozzuoli, on the Bay of Naples. Now, a team of investigators from MIT, Harvard University, and laboratories in Italy and Switzerland, has made progress in this field, discovering ancient concrete-manufacturing strategies that incorporated several key self-healing functionalities. Researchers have spent decades trying to figure out the secret of this ultradurable ancient construction material, particularly in structures that endured especially harsh conditions, such as docks, sewers, and seawalls, or those constructed in seismically active locations. Meanwhile, many modern concrete structures have crumbled after a few decades. Many of these structures were built with concrete: Rome’s famed Pantheon, which has the world’s largest unreinforced concrete dome and was dedicated in 128 C.E., is still intact, and some ancient Roman aqueducts still deliver water to Rome today. These results indicate that PTHrp(1–34) can stimulate placental Ca transfer by increasing 1,25-(OH) 2D synthesis, but also possibly by acting directly upon the placenta.The ancient Romans were masters of engineering, constructing vast networks of roads, aqueducts, ports, and massive buildings, whose remains have survived for two millennia. Both peptides also significantly increased plasma concentrations of 1,25 dihydroxy-vitamin D 3 (1,25-(OH) 2D). Placental Ca transfer (mmol/24 h per kg fetal wt) from the dam to the fetus was not different in control fetuses 7♱☐♶) and those given PTHrp(107–138) (7♲☐♵), but it was significantly increased by bovine PTH(1–34) (8♶☐♴ P < 0♰5) and by PTHrp(1–34) (10♱☐♳ P < 0♰1). three times per day from day 105 until day 116 of gestation. Each peptide (6 nmol/fetus per day) was injected i.v. The first group received PTHrp(1–34), the second PTHrp(107-138), the third bovine PTH(1–34), and the last (control) group was injected with solvent alone. ![]() The influence of synthetic parathyroid hormone related peptide (PTHrp) fragments on placental transfer of Ca was studied in four groups of four single ovine fetuses fitted with catheters chronically implanted into their left jugular vein (for injections) and carotid artery (for blood sampling), and used between days 104 and 118 of gestation.
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