Improved accuracy of U-series and radiocarbon dating of ostrich eggshell using a sample preparation method based on microstructure and geochemistry: A study from the Middle Stone Age of Northwestern Ethiopia

2020 ◽  
Vol 247 ◽  
pp. 106525
Author(s):  
S.L. Loewy ◽  
J. Valdes ◽  
H. Wang ◽  
B. Ingram ◽  
N.R. Miller ◽  
...  
2021 ◽  
pp. 1-24
Author(s):  
R.N.E. Barton ◽  
L. Belhouchet ◽  
S.N. Collcutt ◽  
N. Aouadi ◽  
P.G. Albert ◽  
...  

Abstract This article reports on a new project to investigate the activities of early Homo sapiens in the area of the Chotts ‘megalake’ in southern Tunisia. Excavations in 2015 and 2019 at Oued el Akarit revealed one of a number of Middle Stone Age (MSA) horizons near the top of a long sequence of Upper Pleistocene deposits. The site identified as Oued el Akarit (Sondage 8) consists of lithic artefacts, bone fragments of large ungulates and pieces of ostrich eggshell. Many of the objects are burnt. Excavation of about nine square metres revealed that these were associated with a lightly trampled and combusted occupation surface. Amongst the identified artefacts were Levallois flakes some of which could be refitted, thereby indicating the generally undisturbed nature of the occupation. The lithic finds also included side scrapers and other tools diagnostic of the MSA but significantly no bifacial or tanged tools. OSL (Optically Stimulated Luminescence) dating of the sediments and AMS (Accelerator Mass Spectrometry) radiocarbon dating of ostrich eggshell have produced uncalibrated age determinations in the range 37,000–40,000 years ago, one of the youngest ages for MSA sites in the region. This is the first example of a securely dated later MSA occupation in a riparian environment in south-eastern Tunisia.


Author(s):  
Jian-Shing Luo ◽  
Hsiu Ting Lee

Abstract Several methods are used to invert samples 180 deg in a dual beam focused ion beam (FIB) system for backside milling by a specific in-situ lift out system or stages. However, most of those methods occupied too much time on FIB systems or requires a specific in-situ lift out system. This paper provides a novel transmission electron microscopy (TEM) sample preparation method to eliminate the curtain effect completely by a combination of backside milling and sample dicing with low cost and less FIB time. The procedures of the TEM pre-thinned sample preparation method using a combination of sample dicing and backside milling are described step by step. From the analysis results, the method has applied successfully to eliminate the curtain effect of dual beam FIB TEM samples for both random and site specific addresses.


Author(s):  
Swaminathan Subramanian ◽  
Khiem Ly ◽  
Tony Chrastecky

Abstract Visualization of dopant related anomalies in integrated circuits is extremely challenging. Cleaving of the die may not be possible in practical failure analysis situations that require extensive electrical fault isolation, where the failing die can be submitted of scanning probe microscopy analysis in various states such as partially depackaged die, backside thinned die, and so on. In advanced technologies, the circuit orientation in the wafer may not align with preferred crystallographic direction for cleaving the silicon or other substrates. In order to overcome these issues, a focused ion beam lift-out based approach for site-specific cross-section sample preparation is developed in this work. A directional mechanical polishing procedure to produce smooth damage-free surface for junction profiling is also implemented. Two failure analysis applications of the sample preparation method to visualize junction anomalies using scanning microwave microscopy are also discussed.


Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2277
Author(s):  
Piotr M. Kuś ◽  
Igor Jerković

Recently, we proposed a new sample preparation method involving reduced solvent and sample usage, based on dehydration homogeneous liquid–liquid extraction (DHLLE) for the screening of volatiles and semi-volatiles from honey. In the present research, the method was applied to a wide range of honeys (21 different representative unifloral samples) to determine its suitability for detecting characteristic honey compounds from different chemical classes. GC-FID/MS disclosed 130 compounds from different structural and chemical groups. The DHLLE method allowed the extraction and identification of a wide range of previously reported specific and nonspecific marker compounds belonging to different chemical groups (including monoterpenes, norisoprenoids, benzene derivatives, or nitrogen compounds). For example, DHLLE allowed the detection of cornflower honey chemical markers: 3-oxo-retro-α-ionols, 3,4-dihydro-3-oxoedulan, phenyllactic acid; coffee honey markers: theobromine and caffeine; linden honey markers: 4-isopropenylcyclohexa-1,3-diene-1-carboxylic acid and 4-(2-hydroxy-2-propanyl)cyclohexa-1,3-diene-1-carboxylic acid, as well as furan derivatives from buckwheat honey. The obtained results were comparable with the previously reported data on markers of various honey varieties. Considering the application of much lower volumes of very common reagents, DHLLE may provide economical and ecological advantages as an alternative sample preparation method for routine purposes.


Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2350
Author(s):  
Jianing Zhang ◽  
Fengjie Yu ◽  
Yunmin Tao ◽  
Chunping Du ◽  
Wenchao Yang ◽  
...  

In the present work, a novel sample preparation method, micro salting-out assisted matrix solid-phase dispersion (μ-SOA-MSPD), was developed for the determination of bisphenol A (BPA) and bisphenol B (BPB) contaminants in bee pollen. The proposed method was designed to combine two classical sample preparation methodologies, matrix solid-phase dispersion (MSPD) and homogenous liquid-liquid extraction (HLLE), to simplify and speed-up the preparation process. Parameters of μ-SOA-MSPD were systematically investigated, and results indicated the significant effect of salt and ACN-H2O extractant on the signal response of analytes. In addition, excellent clean-up ability in removing matrix components was observed when primary secondary amine (PSA) sorbent was introduced into the blending operation. The developed method was fully validated, and the limits of detection for BPA and BPB were 20 μg/kg and 30 μg/kg, respectively. Average recoveries and precisions were ranged from 83.03% to 94.64% and 1.76% to 5.45%, respectively. This is the first report on the analysis of bisphenol contaminants in bee pollen sample, and also on the combination of MSPD and HLLE. The present method might provide a new strategy for simple and fast sample preparation of solid and semi-solid samples.


Micron ◽  
2014 ◽  
Vol 58 ◽  
pp. 25-31 ◽  
Author(s):  
Neda Dalili ◽  
Peng Li ◽  
Martin Kupsta ◽  
Qi Liu ◽  
Douglas G. Ivey

Sign in / Sign up

Export Citation Format

Share Document