scholarly journals 14C Blank Assessment in Small-Scale Compound-Specific Radiocarbon Analysis of Lipid Biomarkers and Lignin Phenols

Radiocarbon ◽  
2019 ◽  
Vol 62 (1) ◽  
pp. 207-218
Author(s):  
Shuwen Sun ◽  
Vera D Meyer ◽  
Andrew M Dolman ◽  
Maria Winterfeld ◽  
Jens Hefter ◽  
...  
Keyword(s):  
Lipid Biomarkers ◽  
Small Samples ◽  
Small Scale ◽  
Radiocarbon Dates ◽  
Combustion Gas ◽  
Lignin Phenols ◽  
Procedural Blank ◽  
Alkanoic Acids ◽  
Unknown Composition ◽  
Intersection Points

ABSTRACTCompound-specific radiocarbon (14C) dating often requires working with small samples of < 100 µg carbon (µgC). This makes the radiocarbon dates of biomarker compounds very sensitive to biases caused by extraneous carbon of unknown composition, a procedural blank, which is introduced to the samples during the steps necessary to prepare a sample for radiocarbon analysis by accelerator mass spectrometry (i.e., isolating single compounds from a heterogeneous mixture, combustion, gas purification and graphitization). Reporting accurate radiocarbon dates thus requires a correction for the procedural blank. We present our approach to assess the fraction modern carbon (F14C) and the mass of the procedural blanks introduced during the preparation procedures of lipid biomarkers (i.e. n-alkanoic acids) and lignin phenols. We isolated differently sized aliquots (6–151 µgC) of n-alkanoic acids and lignin phenols obtained from standard materials with known F14C values. Each compound class was extracted from two standard materials (one fossil, one modern) and purified using the same procedures as for natural samples of unknown F14C. There is an inverse linear relationship between the measured F14C values of the processed aliquots and their mass, which suggests constant contamination during processing of individual samples. We use Bayesian methods to fit linear regression lines between F14C and 1/mass for the fossil and modern standards. The intersection points of these lines are used to infer F14Cblank and mblank and their associated uncertainties. We estimate 4.88 ± 0.69 μgC of procedural blank with F14C of 0.714 ± 0.077 for n-alkanoic acids, and 0.90 ± 0.23 μgC of procedural blank with F14C of 0.813 ± 0.155 for lignin phenols. These F14Cblank and mblank can be used to correct AMS results of lipid and lignin samples by isotopic mass balance. This method may serve as a standardized procedure for blank assessment in small-scale radiocarbon analysis.

100 ASSESSMENT OF LOCUS-SPECIFIC DNA METHYLATION: OPTIMIZATION FOR BOVINE EMBRYOS

2009 ◽  
Vol 21 (1) ◽  
pp. 150
Author(s):  
E. Wroclawska ◽  
J. O. Brant ◽  
T. P. Yang ◽  
K. Moore
Keyword(s):  
Dna Methylation ◽  
Somatic Cell ◽  
Chromatin Remodeling ◽  
Plasmid Dna ◽  
Dna Amplification ◽  
Early Embryo ◽  
Small Samples ◽  
Small Scale ◽  
Research Education

Assessment of chromatin remodeling in early embryos is a major focus of studies today, and evaluation of DNA methylation at specific loci is one approach to study these epigenetic modifications. Our objective was to optimize the bisulfite sequencing methodology for use with very small cell numbers originating from pre-implantation embryos, making the process more time- and cost-efficient. The optimized steps include bisulfite conversion of small samples, bisulfite primer design, high-throughput plasmid DNA amplification, and preparation for sequencing. Methylation at 2 loci, Satellite I and Oct4, was investigated in bovine in vitro-produced (IVP) embryos collected at the 2-cell, 8-cell, and blastocyst stages. Bovine skin fibroblasts were first used to optimize the particular steps of the process. All reactions were run in duplicate and no-template negative and somatic cell-positive controls were treated alongside samples. Incorporating the use of Methyl Primer Express (Applied Biosystems, Foster City, CA), MacVector (Oxford Molecular Ltd., Campbell, CA), and Mfold software (Mathews DH et al. 1999 J. Mol. Biol. 288, 911–940; Zuker M 2003 Nucleic Acids Res. 31, 3406–3415) improved the specificity of bisulfite primers by exclusion of secondary or tertiary structures. The DNA from bisulfite treatment for 15 to 16 h was of better quality than DNA treated for 18 h. After initial PCR optimization, different cell concentrations were used to establish that detectable PCR products and subsequent methylation data could be obtained from DNA isolated from as few as 8 cells. Treating single blastocysts and pools of ten 8-cell and forty 2-cell embryos was sufficient for the entire scope of the experiment, allowing use of the same samples across all loci. After molecular cloning, plasmid DNA was amplified by 3 different methods and evaluated for efficiency: miniprep, TempliPhi (GE Healthcare, Piscataway, NJ), or 96-well glycerol stocks and automated TempliPhi format. Although TempliPhi alone was better than miniprep for small-scale experiments, it was the 96-well format that saved weeks of time and was most cost-effective. Sequencing was performed on a minimum of 8 clones/sample using ABI Prism sequencers (Applied Biosystems), and results were analyzed using Chromas Pro software (Technelysium Pty. Ltd., Helensvale, Australia). Percentage methylation of bovine IVP 2-cell, 8-cell, and blastocyst stage embryos for Satellite I was 25, 10, and 22%, respectively, and for Oct4 was 88, 88, and 79%, respectively. However, somatic cell methylation was 74% for Satellite I and 88% for Oct4, implying that Satellite I is demethylated during early embryo development, whereas Oct4 remains hypermethylated. In conclusion, these improved methods will benefit further studies of chromatin remodeling in early bovine pre-implantation embryos. This project was supported by National Research Initiative Competitive Grant no. 2006-35203-16620 from the USDA Cooperative State Research, Education, and Extension Service.

The Bigger The Better? - Updates on the Statistical Limits of Nano-Palaeomagnetic Works and (sub)millimeter Samples

2020 ◽  
Author(s):  
Thomas Berndt ◽  
Adrian Muxworthy ◽  
Karl Fabian ◽  
Liao Chang
Keyword(s):  
Statistical Physics ◽  
Magnetic Particles ◽  
Small Samples ◽  
Small Scale ◽  
Iron Meteorites ◽  
Statistical Reliability ◽  
Magnetic Imaging ◽  
Magnetic Remanence ◽  
Indispensable Tool

&lt;p&gt;A recent trend in paleomagnetism is the study of samples of ever decreasing sizes, going down to (sub)millimeter scales and even microscopic scales (&amp;#8220;nanopaleomagnetism&amp;#8221;). These include studies of single-silicate-crystals, microscopic magnetic imaging of the cloudy zones in Iron meteorites, and recently even the determination of individual magnetic remanence carriers. As single-crystal and nanopalaeomagnetic methods are getting more adopted, it is getting increasingly important to assess the statistical reliability with which such small samples can record remanences from a physical perspective. We previously proposed a benchmark to assess small-scale samples of randomly oriented non-interacting single-domain (SD) particles and found that in most cases, the number of magnetic particles a sample must contain lies in the order of tens to hundreds of millions &amp;#8211; or equivalently NRM strengths of the order of 10&lt;sup&gt;-12&lt;/sup&gt; Am&lt;sup&gt;2&lt;/sup&gt;. In this talk, we present how this benchmark can be used as a simple yet indispensable tool to assess whether or not (sub)millimeter-size and nanopalaeomagnetic samples are able to statistically reliably record palaeomagnetic fields. Moreover, this talk will provide an outlook into future limitations but also opportunities of the statistical physics nature of microscopic magnetic particle systems. It will explore if multi-domain particles should ever be considered statistically reliable recorders, how interactions in SD particle clusters might affect statistical reliability, and will review the various challenges that Iron meteorites pose as a remanence recorder.&lt;/p&gt;

Excavations and Metal-working at Llwyn Bryn-dinas Hillfort, Llangedwyn, Clwyd

1992 ◽  
Vol 58 (1) ◽  
pp. 265-283 ◽  
Author(s):  
C. R. Musson ◽  
W. J. Britnell ◽  
J. P. Northover ◽  
C. J. Salter ◽  
P. Q. Dresser ◽  
...  
Keyword(s):  
Bronze Age ◽  
Iron Age ◽  
Copper Alloy ◽  
Radiocarbon Date ◽  
Small Scale ◽  
Metal Working ◽  
Radiocarbon Dates ◽  
Alloy Casting ◽  
The North ◽  
Local Evidence

Small-scale rescue excavations at Llwyn Bryn-dinas hillfort, on the Welsh Borderland, showed that the earliest fortification belonged to the late Bronze Age, with radiocarbon dates in the late 9th and 8th centuries be. A terrace, subsequently cut into the rear of the rampart to accommodate a metal-working floor, was associated with a radiocarbon date centred in the late 3rd century bc. Detailed analysis of the metal-working debris suggests that copper-alloy casting, iron forging and possibly bronze production were carried out within a single workshop. The finds include a distinctive form of handled crucible. The industry appears to have been fairly small-scale, of short duration, and probably only designed to meet the internal needs of the hillfort population. The excavation adds significantly to the local evidence for metal-working during the later prehistoric period. A distinctive zinc-impurity pattern in the copper alloy and raw copper, previously identified in material from other sites nearby, confirms the suggestion of an Iron Age bronze-working industry based on a specific metal source in the north Powys area. In addition, analysis of the iron-working debris suggests the exploitation of a distinctive local ore body. The metal-working activity appears to have come to an abrupt end, possibly with the enlargement or local repair of the rampart. Later phases of activity include a final occupation deposit with an associated radiocarbon date centred in the mid 2nd century bc.

scholarly journals Toward Distribution Estimation under Local Differential Privacy with Small Samples

2018 ◽  
Vol 2018 (3) ◽  
pp. 84-104 ◽  
Author(s):  
Takao Murakami ◽  
Hideitsu Hino ◽  
Jun Sakuma
Keyword(s):  
Census Data ◽  
Differential Privacy ◽  
Estimation Error ◽  
Personal Data ◽  
Local Model ◽  
Small Samples ◽  
Small Scale ◽  
Reconstruction Method ◽  
True Value ◽  
Distribution Estimation

Abstract A number of studies have recently been made on discrete distribution estimation in the local model, in which users obfuscate their personal data (e.g., location, response in a survey) by themselves and a data collector estimates a distribution of the original personal data from the obfuscated data. Unlike the centralized model, in which a trusted database administrator can access all users’ personal data, the local model does not suffer from the risk of data leakage. A representative privacy metric in this model is LDP (Local Differential Privacy), which controls the amount of information leakage by a parameter ∈ called privacy budget. When ∈ is small, a large amount of noise is added to the personal data, and therefore users’ privacy is strongly protected. However, when the number of users ℕ is small (e.g., a small-scale enterprise may not be able to collect large samples) or when most users adopt a small value of ∈, the estimation of the distribution becomes a very challenging task. The goal of this paper is to accurately estimate the distribution in the cases explained above. To achieve this goal, we focus on the EM (Expectation-Maximization) reconstruction method, which is a state-of-the-art statistical inference method, and propose a method to correct its estimation error (i.e., difference between the estimate and the true value) using the theory of Rilstone et al. We prove that the proposed method reduces the MSE (Mean Square Error) under some assumptions.We also evaluate the proposed method using three largescale datasets, two of which contain location data while the other contains census data. The results show that the proposed method significantly outperforms the EM reconstruction method in all of the datasets when ℕ or ∈ is small.

Optimum Operation of Externally-Fired Microturbine in Combined Heat and Power Generation

2007 ◽  
Author(s):  
Juha Kaikko ◽  
Jari L. H. Backman ◽  
Lasse Koskelainen ◽  
Jaakko Larjola
Keyword(s):  
Power Generation ◽  
Heat Exchanger ◽  
Gas Turbines ◽  
Combined Heat And Power ◽  
Small Scale ◽  
Inlet Temperature ◽  
Control Methods ◽  
Gas Temperature ◽  
Combustion Gas ◽  
Part Load

Externally-fired microturbines (EFMT) yield promising performance in small-scale utilization of biofuels. As in larger gas turbines, the part-load performance of the EFMT is very sensitive to the selected power control method, and in general subject to severe degradation at part load. The control parameters typically include the maximum combustion gas temperature or turbine inlet temperature and the speed of the shaft. At the design point, power generation efficiency can be increased by allowing a fraction of air to bypass the burner and the combustion gas – air heat exchanger. At the same time the heat exchanger size is increased. Therefore, the by-pass flow affects the optimal sizing of the EFMT as well. In this paper, the effect of by-pass flow on the part-load performance of a single-shaft EFMT in combined heat and power generation is analyzed. In the application, the microturbine is operated by the heat demand. The control methods incorporate the use of the maximum combustion gas temperature, the speed of the shaft, and the amount of by-pass air. The focus of the study is to determine the economically optimal control scheme for the engine. The economy model uses the profit flow from the EFMT as a criterion. The results show that the inclusion of the by-pass variation in the control methods can improve the economy of temperature-controlled EFMT at part load but has no benefits when using speed control.

A small-scale milling technique for establishment of flour yield of wheat

1974 ◽  
Vol 14 (70) ◽  
pp. 658 ◽  
Author(s):  
BR Whan
Keyword(s):  
Moisture Content ◽  
Wheat Breeding ◽  
Soft Wheat ◽  
Small Samples ◽  
Small Scale ◽  
Common Basis ◽  
Constant Moisture Content ◽  
Flour Yield ◽  
Milling Yield ◽  
Satisfactory Relationship

The Brabender Quadrumat Junior mill was investigated as a possible means of estimating the flour yield of small samples of wheat. When very hard, hard and soft wheats were milled at a constant moisture content (whether equilibrium or a higher, conditioned moisture content) on the Quadrumat Junior mill, the flour yields did not correlate with those from a Buhler experimental mill, because the hard and very hard varieties were over-estimated. A satisfactory relationship was obtained by milling the hard wheats at a moisture content one per cent higher than the soft wheats, and the very hard wheats two per cent higher than the soft wheats. All wheats could then be compared on a common basis. When seven soft wheat samples were milled on the Quadrumat Junior and six large experimental mills, the Quadrumat Junior estimated the flour yields as accurately as any of the large mills. This method appears to be suitable for selection in a wheat breeding programme to improve milling yield. Samples as small as 5 g can be used

scholarly journals Developing Ultra Small-Scale Radiocarbon Sample Measurement at the University of Tokyo

Radiocarbon ◽  
2010 ◽  
Vol 52 (2) ◽  
pp. 310-318 ◽  
Author(s):  
Yusuke Yokoyama ◽  
Mamito Koizumi ◽  
Hiroyuki Matsuzaki ◽  
Yosuke Miyairi ◽  
Naohiko Ohkouchi
Keyword(s):  
Ion Beam ◽  
Measurement Techniques ◽  
Beam Current ◽  
Ion Source ◽  
Small Samples ◽  
Small Scale ◽  
Target Holder ◽  
Vacuum Line ◽  
The Difference ◽  
Beam Currents

We have developed accelerator mass spectrometry (AMS) measurement techniques for ultra small-size samples ranging from 0.01 to 0.10 mg C with a new type of MC-SNICS ion source system. We can generate 4 times higher ion beam current intensity for ultra-small samples by optimization of graphite position in the target holder with the new ionizer geometry. CO2 gas graphitized in the newly developed vacuum line is pressed to a depth of 1.5 mm from the front of the target holder. This is much deeper than the previous position at 0.35 mm depth. We measured 12C4+ beam currents generated by small standards and ion beam currents (15–30 μA) from the targets in optimized position, lasting 20 min for 0.01 mg C and 65 min for 0.10 mg C. We observed that the measured 14C/12C ratios are unaffected by the difference of ion beam currents ranging from 5 to 30 μA, enabling measurement of ultra-small samples with high precision. Examination of the background samples revealed 1.1 μg of modern and 1 μg of dead carbon contaminations during target graphite preparation. We make corrections for the contamination from both the modern and background components. Reduction of the contamination is necessary for conducting more accurate measurement.

scholarly journals The AMS Dating of Separate Fractions in Archaeology

Radiocarbon ◽  
1986 ◽  
Vol 28 (2A) ◽  
pp. 698-701 ◽  
Author(s):  
R J Batten ◽  
Richard Gillespie ◽  
J A J Gowlett ◽  
Rem Hedges
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Humic Acid ◽  
Carbon Source ◽  
High Molecular Weight ◽  
Complex Mixture ◽  
Small Samples ◽  
Radiocarbon Dates ◽  
Ams Dating ◽  
Relationship Of

The usefulness of radiocarbon dates in archaeology greatly depends on both the stratigraphic relationship of the sample submitted and on the origin and homogeneity of the measured carbon. For very small samples, stratigraphic relationships can raise additional problems of movement. In chemically well-characterized materials, the best example being collagen, the carbon source can be reasonably well purified. Many samples, however, survive as a complex mixture of high molecular weight polyphenolic materials, with properties between charcoals, humic acids, and lignins. Charred bone, eg, which rarely contains useful quantities of amino acids, and charred seeds, as well as ‘charcoal,’ frequently come into this category. For such samples, the likelihood of contamination by percolating soil humics is high. It is often possible to extract chemically different fractions and to compare the dates obtained. A less exact comparison can also be made for different samples from the same context. The results suggest that ‘humic’ acid dates can be reliable in a surprisingly frequent number of situations, and that where direct comparison is possible, the reliability can be individually assessed.

scholarly journals Open Source Vacuum Oven Design for Low-Temperature Drying: Performance Evaluation for Recycled PET and Biomass

2021 ◽  
Vol 5 (2) ◽  
pp. 52
Author(s):  
Benjamin R. Hubbard ◽  
Lindsay I. Putman ◽  
Stephen Techtmann ◽  
Joshua M. Pearce
Keyword(s):  
Additive Manufacturing ◽  
Open Source ◽  
Small Samples ◽  
Small Scale ◽  
Vacuum Drying ◽  
Time Saving ◽  
Vacuum Oven ◽  
Recycled Pet ◽  
And Performance ◽  
Air Dryer

Vacuum drying can dehydrate materials further than dry heat methods, while protecting sensitive materials from thermal degradation. Many industries have shifted to vacuum drying as cost- or time-saving measures. Small-scale vacuum drying, however, has been limited by the high costs of specialty scientific tools. To make vacuum drying more accessible, this study provides design and performance information for a small-scale open source vacuum oven, which can be fabricated from off-the-shelf and 3-D printed components. The oven is tested for drying speed and effectiveness on both waste plastic polyethylene terephthalate (PET) and a consortium of bacteria developed for bioprocessing of terephthalate wastes to assist in distributed recycling of PET for both additive manufacturing as well as potential food. Both materials can be damaged when exposed to high temperatures, making vacuum drying a desirable solution. The results showed that the open source vacuum oven was effective at drying both plastic and biomaterials, drying at a higher rate than a hot-air dryer for small samples or for low volumes of water. The system can be constructed for less than 20% of commercial vacuum dryer costs for several laboratory-scale applications, including dehydration of bio-organisms, drying plastic for distributed recycling and additive manufacturing, and chemical processing.

scholarly journals A Model for Igniter Mass Flow Rate History Evaluation for Solid Rocket Motors

2019 ◽  
Vol 2019 ◽  
pp. 1-12
Author(s):  
Yanjie Ma ◽  
Futing Bao ◽  
Weihua Hui ◽  
Yang Liu ◽  
Yijie Gao
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Large Scale ◽  
Rocket Motor ◽  
Small Scale ◽  
Solid Rocket Motor ◽  
Combustion Gas ◽  
Proposed Model ◽  
Solid Rocket

This paper describes a zero-dimensional model for evaluating the mass flow rate history of a solid rocket motor igniter. Based on the results of an igniter-firing experiment, in which the igniter is the only source of combustion gas and no propellant is ignited, the proposed model can be used to compute the mass flow rate of the igniter. Different species and temperature-dependent properties, such as the specific heat for each species, are considered. The coupling between the flow field variables in the combustion chamber and the heat transfer at the gas-solid interface is computed in a segment way. Calculations are performed for different species and properties, and the errors are discussed. Using the computed igniter mass flow rate as a boundary condition, a two-dimensional calculation is performed for validation purposes. The results are in good agreement with experimental data. The proposed model can be used to provide reasonable boundary conditions for solid rocket motor simulations and to evaluate the performance of igniters. Although derived on the basis of a small-scale solid rocket motor, the model has the potential to be used in large-scale systems.

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