. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 698 592 a2 1419 692 592 1500 1250 1000 Wavenumbers (cm') hi b2. 0 200 400 600 800 1000 1200 Raman shift (cirr1) Figure 3. (a) Infrared spectra of (al) the concretions after ecdysis, when the storage structures are being resorbed (the IR spectrum of the concretions before ecdysis was identical and therefore is not shown); and (a2) control antler spicules of Pyura pachydermatina composed of stable amorphous calcium carbonate (ACC) (20). The ACC spectrum is charac- terized by a broad peak of the carbonate bending at 866 cm~' an
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 698 592 a2 1419 692 592 1500 1250 1000 Wavenumbers (cm') hi b2. 0 200 400 600 800 1000 1200 Raman shift (cirr1) Figure 3. (a) Infrared spectra of (al) the concretions after ecdysis, when the storage structures are being resorbed (the IR spectrum of the concretions before ecdysis was identical and therefore is not shown); and (a2) control antler spicules of Pyura pachydermatina composed of stable amorphous calcium carbonate (ACC) (20). The ACC spectrum is charac- terized by a broad peak of the carbonate bending at 866 cm~' and a split in the asymmetric stretch of the carbonate ion at 1420 and 1474 cm ~'. The additional peak at around 1070 cm"' is mainly assigned to phosphates. A powdered sample (about mg) was mixed with about 10 mg of anhy- drous KBr. The mixture was pressed into a 7-mm-diameter pellet. The analysis was performed at 4 cm"1 resolution using a Midac Corporation FTIR spectrometer. (b) Raman spectra of (b 1) one analysis of a concretion before ecdysis, at the end of the storage period; and (b2) control antler spicules of Pyura pachydermatina composed of stable amorphous calcium carbonate (21). The spectra are characterized by a broad peak at 150-250 cm"' and at about 1080 cm"'. Note that both the sample and the control have an additional peak at about 950 cm" ', which corresponds to ACP. Phosphorus was also detected in the concretions by energy dispersive spectrometry (EDS). For Raman spectroscopy, samples were placed on glass slides and were observed with a Leica microscope at a magnification of 50x, using reflected white light. After focusing on the object, the light source of the microscope was transferred to a diode laser (780 nm). The spectra were scanned for 10 s in the range 100-1200 cm"', using a Renishaw Raman It is now well established that these mineralized structures are transitory calcium deposits (18, 19). A previous Debye-Scherrer X-ray
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