研究目的
To characterize a fossilized feather using combined microscopy and spectroscopy techniques with minimal damage to the specimen, focusing on morphological and physicochemical analysis to confirm its identity and preservation.
研究成果
The combined techniques effectively characterized the fossilized feather as a downy feather with preserved melanosomes, evidenced by morphological and chemical data. The presence of sulfur indicates keratin, and fluorescence signals suggest melanin. The approach minimizes damage and provides comprehensive insights, supporting future fossil studies with similar methodologies.
研究不足
The study is limited to one fossil specimen from a specific formation, which may not represent all fossil feathers. Some techniques like TEM required minimal sample removal, though efforts were made to minimize damage. The interpretations rely on comparisons with extant feathers and prior studies, and the non-crystalline nature of melanosomes could affect certain analyses.
1:Experimental Design and Method Selection:
The study employed a correlative approach using SEM, TEM, EDS, FT-IR Spectroscopy, and CLSM to analyze the fossilized feather at mesoscale, microscale, and nanoscale without extensive sample preparation to minimize damage.
2:Sample Selection and Data Sources:
The fossil sample (MN 7754-V) was from the Crato Formation in Brazil, selected for its feather-like structures and preservation in laminated limestone.
3:List of Experimental Equipment and Materials:
Equipment included FEI SEM Quanta 200i, FEI Magellan 400 SEM, FEI TITAN 80-300 TEM, EDAX Apollo X SDD EDS detector, EDAX tops 30 OST EDS detector, Shimadzu IR Prestige-21 FT-IR spectrometer with AIM-8800 microscope, Leica TCS SPE AOBS CLSM, Leica EM uc7 ultramicrotome, epoxy resin (Spurr, Ted Pella Inc.), Lacey-Carbon coated Ni grids (Ted Pella Inc.), and glass cover slips.
4:Experimental Procedures and Operational Workflow:
For SEM, the sample was analyzed without sputtering at low and high magnifications. For TEM, a small piece was embedded in resin, sectioned with an ultramicrotome, and placed on grids. EDS was performed in SEM and TEM modes. FT-IR was done in ATR mode on the sample and matrix. CLSM involved spectral fluorescence scanning with specific parameters for excitation and emission wavelengths.
5:Data Analysis Methods:
Image analysis used ImageJ for morphometry (e.g., aspect ratio), Microsoft Excel for data processing, Digital Micrograph for FFT analysis, and LAS AF software for image deconvolution in CLSM. EDS and FT-IR spectra were compared between sample and matrix.
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SEM Quanta 200i
Quanta 200i
FEI
Used for low and high magnification imaging of the fossil sample without sputtering to observe general features and microstructures.
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SEM Magellan 400
Magellan 400
FEI
Used for high-resolution nanoscale imaging with a field emission gun to avoid sample damage.
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TEM TITAN 80-300
TITAN 80-300
FEI
Used for bright field TEM, HAADF imaging, and electron diffraction to analyze internal structure of melanosomes.
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FT-IR Prestige-21
IR Prestige-21
Shimadzu
Coupled with an optical microscope for ATR mode spectroscopy to detect chemical groups in the fossil sample.
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CLSM TCS SPE AOBS
TCS SPE AOBS
Leica
Used for confocal laser scanning microscopy to perform spectral fluorescence scanning and imaging for pigment mapping.
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Ultramicrotome EM uc7
EM uc7
Leica
Used to cut ultrathin sections of the embedded sample for TEM analysis.
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EDS Apollo X
Apollo X
EDAX
Used for elemental composition analysis in SEM mode.
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EDS tops 30 OST
tops 30 OST
EDAX
Used for elemental characterization in TEM mode on ultrathin sections.
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Epoxy Resin
Spurr
Ted Pella Inc.
Used for embedding the sample piece for TEM sectioning.
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Lacey-Carbon Coated Ni Grids
Ted Pella Inc.
Used as substrates for depositing ultrathin sections in TEM.
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Glass Cover Slip
Used for placing the sample in CLSM analysis.
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