scholarly journals A NEW RAMPED PYROXIDATION/COMBUSTION FACILITY AT 14CHRONO, BELFAST: SETUP DESCRIPTION AND INITIAL RESULTS

Radiocarbon ◽  
2021 ◽  
pp. 1-14
Author(s):  
Evelyn M Keaveney ◽  
Gerard T Barrett ◽  
Kerry Allen ◽  
Paula J Reimer
Keyword(s):  
Bulk Material ◽  
Correction Method ◽  
Source Attribution ◽  
Radiocarbon Age ◽  
Targeted Analysis ◽  
Consensus Values ◽  
Background Material ◽  
Initial Results ◽  
Blank Correction ◽  
Good Agreement

ABSTRACT The Belfast Ramped Pyroxidation/Combustion (RPO/RC) facility was established at the 14CHRONO Centre (Queen’s University Belfast). The facility was created to provide targeted analysis of bulk material for refined chronological analysis and carbon source attribution for a range of sample types. Here we report initial RPO results, principally on background material, but also including secondary standards that are routinely analyzed at 14CHRONO. A description of our setup, methodology, and background (blank) correction method for the system are provided. The backgrounds (anthracite, spar calcite, Pargas marble) reported by the system are in excess of 35,000 14C years BP with a mean age of 39,345 14C years BP (1σ = 36,497–43,800 years BP, N=44) with F14C = 0.0075 ± 0.0032. Initial results for standards are also in good agreement with consensus values: TIRI-B pine radiocarbon age = 4482 ± 47 years BP (N=13, consensus = 4508 years BP); IAEA-C6 ANU Sucrose F14C= 1.5036 ± 0.0034 (N=10, consensus F14C = 1.503). These initial tests have allowed problematic issues to be identified and improvements made for future analyses.

scholarly journals The Radiocarbon Content of Individual Lignin-Derived Phenols: Technique and Initial Results

Radiocarbon ◽  
2000 ◽  
Vol 42 (2) ◽  
pp. 219-227 ◽  
Author(s):  
A P McNichol ◽  
J R Ertel ◽  
T I Eglinton
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Phenolic Compounds ◽  
Accelerator Mass Spectrometry ◽  
Bulk Material ◽  
Polymeric Materials ◽  
Chemical Oxidation ◽  
Flavor Compounds ◽  
The Individual ◽  
Initial Results

We present a method for the isolation of phenolic compounds derived from lignin for radiocarbon analysis. These phenols are generated by chemical oxidation of polymeric materials and derivatized for separation and recovery by preparative capillary gas chromatography (PCGC). This technique yields tens of micrograms of pure, stable compounds that can be converted to graphite and analyzed by accelerator mass spectrometry (AMS). Analysis of model flavor compounds and dated woods indicates that, in most cases, the radiocarbon (14C) contents of the individual compounds, corrected for the contribution of the derivative, agree with that of the bulk material to within 20%.

scholarly journals Problems Associated with the Use of Coal As a Source of14C-Free Background Material

Radiocarbon ◽  
1989 ◽  
Vol 31 (2) ◽  
pp. 117-120 ◽  
Author(s):  
David C Lowe
Keyword(s):  
Fungal Activity ◽  
Background Material ◽  
Test Materials ◽  
Alternative Sources ◽  
Initial Results

Many14C dating laboratories have established that coal samples exhibit a finite14C age, apparently caused by contamination of the specimens before any laboratory preparation is undertaken. In this work, the possibility that the contamination is due to microbial and fungal activity in the coal substrate is considered and some suggestions are made for alternative sources of background test materials for14C dating laboratories. Initial results indicate that geologically formed graphites contain little14C and are likely to be good background test materials, especially in14C AMS laboratories.

scholarly journals Radar Z–RRelationship for Summer Monsoon Storms in Arizona

2005 ◽  
Vol 20 (4) ◽  
pp. 672-679 ◽  
Author(s):  
Efrat Morin ◽  
Robert A. Maddox ◽  
David C. Goodrich ◽  
Soroosh Sorooshian
Keyword(s):  
Hydrologic Model ◽  
Storm Events ◽  
Convective Storm ◽  
Convective Storms ◽  
Discharge Rates ◽  
Wide Range ◽  
Gauge Data ◽  
R Relation ◽  
Initial Results ◽  
Good Agreement

Abstract Radar-based estimates of rainfall rates and accumulations are one of the principal tools used by the National Weather Service (NWS) to identify areas of extreme precipitation that could lead to flooding. Radar-based rainfall estimates have been compared to gauge observations for 13 convective storm events over a densely instrumented, experimental watershed to derive an accurate reflectivity–rainfall rate (i.e., Z–R) relationship for these events. The resultant Z–R relationship, which is much different than the NWS operational Z–R, has been examined for a separate, independent event that occurred over a different location. For all events studied, the NWS operational Z–R significantly overestimates rainfall compared to gauge measurements. The gauge data from the experimental network, the NWS operational rain estimates, and the improved estimates resulting from this study have been input into a hydrologic model to “predict” watershed runoff for an intense event. Rainfall data from the gauges and from the derived Z–R relation produce predictions in relatively good agreement with observed streamflows. The NWS Z–R estimates lead to predicted peak discharge rates that are more than twice as large as the observed discharges. These results were consistent over a relatively wide range of subwatershed areas (4–148 km2). The experimentally derived Z–R relationship may provide more accurate radar estimates for convective storms over the southwest United States than does the operational convective Z–R used by the NWS. These initial results suggest that the generic NWS Z–R relation, used nationally for convective storms, might be substantially improved for regional application.

scholarly journals Continued Results from a Field Campaign of Wake Steering Applied at a Commercial Wind Farm: Part 2

2020 ◽  
Author(s):  
Paul Fleming ◽  
Jennifer King ◽  
Eric Simley ◽  
Jason Roadman ◽  
Andrew Scholbrock ◽  
...  
Keyword(s):  
Steady State ◽  
Wind Farm ◽  
Second Phase ◽  
Optimal Result ◽  
Energy Increase ◽  
Field Campaign ◽  
Original Intention ◽  
Steady State Model ◽  
Initial Results ◽  
Good Agreement

Abstract. This paper presents the results of a field campaign investigating the performance of wake steering applied at a section of a commercial wind farm. It is the second phase of the study in which the first phase was reported in Initial results from a field campaign of wake steering applied at a commercial wind farm – Part 1. The authors implemented wake steering on two turbine pairs, and compared results with the latest FLORIS (FLOw Redirection and Induction in Steady State) model of wake steering, showing good agreement in overall energy increase. Further, although not the original intention of the study, we also used results to detect the secondary steering phenomena. Results show an overall reduction in wake losses of approximately 6.6 % for the regions of operation, which corresponds to achieving roughly half of the static optimal result.

Thermal Conductivity and Specific Heat Measurements of Single Nanowires

2005 ◽  
Author(s):  
Chris Dames ◽  
Gang Chen
Keyword(s):  
Thermal Conductivity ◽  
Specific Heat ◽  
Bulk Material ◽  
Si Nanowires ◽  
Quantum Confinement Effects ◽  
Single Nanowires ◽  
Effective Use ◽  
20 Nm ◽  
Theory And Experiments ◽  
Good Agreement

For the effective use of nanowires and nanotubes in their many possible applications in sensing, computation and memory, optoelectronics, and energy conversion, it is important to understand their thermal properties, which may differ considerably from bulk [1]. For example, there is good agreement between theory and experiments on Si nanowires showing that the classical size effect of phonon boundary scattering may reduce the thermal conductivity by up to several orders of magnitude for diameters of 40 nm and up [2, 3, 12, 13]. However, more experiments are needed at 20 nm and smaller diameters. There is also a need for experiments on the specific heat of single nanowires, which is intimately related to thermal conductivity by kinetic theory, and may be altered by quantum confinement effects. We have previously measured the specific heat of a pellet of TiO2 nanotubes of ∼3 nm wall thickness and found it similar to the bulk material at temperatures above ∼80 K [4]; however, questions remain about the possible interactions between adjacent tubes, which single-tube studies would resolve.

Thermoluminescence properties and age estimates for Quaternary raised marine sediments, Hudson Bay Lowland, Canada

1987 ◽  
Vol 24 (12) ◽  
pp. 2405-2411 ◽  
Author(s):  
S. L. Forman ◽  
A. G. Wintle ◽  
L. H. Thorleifson ◽  
P. H. Wyatt
Keyword(s):  
Marine Sediments ◽  
Linear Growth ◽  
Control Sample ◽  
Growth Curves ◽  
High Light ◽  
Hudson Bay ◽  
Radiocarbon Age ◽  
Hudson Bay Lowland ◽  
Initial Results ◽  
Age Estimates

Thermoluminescence (TL) analyses of Quaternary nearshore marine sediments from the Hudson Bay Lowland revealed relatively high light emissions and linear growth curves to at least 400 Gy above the natural dose. Initial results indicate that anomalous fading may be circumvented by a preheating at 150 °C for 16 h without substantial thermal draining of stable TL components. Both the total bleach method with unfiltered sunlamp light and the partial bleach method with light blocked below 400 nm resulted in overbleaching and thus overestimates of age. A TL age estimate of 5.3 ± 0.8 ka on the Holocene control sample, similar to the radiocarbon age, was obtained using the partial bleach method with light blocked below 540 nm. This same method yielded an average TL age estimate of 73 ± 10 ka for a Pleistocene unit, which corresponds to the amino-acid-based age estimate of ca. 76 ka. The agreement of the two age estimates is encouraging, since both methods rely on separate assumptions that have not been independently verified.

scholarly journals New 14C Dates for the Early Natufian of El-Wad Terrace, Mount Carmel, Israel

Radiocarbon ◽  
2012 ◽  
Vol 54 (3-4) ◽  
pp. 813-822 ◽  
Author(s):  
Mina Weinstein-Evron ◽  
Reuven Yeshurun ◽  
Daniel Kaufman ◽  
Eileen Eckmeier ◽  
Elisabetta Boaretto
Keyword(s):  
Mass Spectrometry ◽  
Accelerator Mass Spectrometry ◽  
Southern Levant ◽  
Radiocarbon Age ◽  
Cultural Affiliation ◽  
The Core ◽  
Integral Role ◽  
First Results ◽  
Age Determinations ◽  
Good Agreement

The Natufian culture of the southern Levant played an integral role in the transition from simple huntergatherers to food-producing societies of the Neolithic, but the major Natufian hamlets are currently poorly dated. Moreover, none of these complex, continuously occupied base camps have delivered an adequate number of dates to enable an in-depth delineation of intra-Natufian developments. This paper presents the first results of our dating program at el-Wad terrace, Mount Carmel (Israel), one of the major Natufian hamlets of the “core area” of this culture. Thirteen accelerator mass spectrometry (AMS) radiocarbon age determinations were obtained from 46 bone (both ungulate and human) and charcoal samples, originating in Early Natufian living surfaces, dwellings, and burials. The obtained dates are largely in agreement with the cultural affiliation of the samples (13–15 kyr cal BP). Two series of dates from different locations show good agreement with the stratigraphy. The ages of the burials clearly point to their being younger than the living surfaces seemingly associated with them. Presently, no burials may be linked with the major architectural phase of Early Natufian el-Wad. Our ongoing dating program and the processing of additional samples from refined contexts will help shed important light on the initial phases of the Natufian culture, habitation duration, intensity, and continuity, as well as the relationships between site features and stratigraphy.

scholarly journals A Transmission-Based Dielectric Property Probe for Clinical Applications

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3484 ◽  
Author(s):  
Paul Meaney ◽  
Tomas Rydholm ◽  
Helena Brisby
Keyword(s):  
Dielectric Properties ◽  
Dielectric Property ◽  
Measurement Technique ◽  
Clinical Applications ◽  
Clinical Implementation ◽  
Compact Spaces ◽  
Low Profile ◽  
Typical Range ◽  
Initial Results ◽  
Good Agreement

We have developed a transmission-based, open-ended coaxial dielectric probe that can be used in clinical situations and overcomes many of the limitations related to the typical reflection-based dielectric probes. The approach utilizes the low profile, open-ended coaxial cables enabling clinicians to still probe relatively compact spaces. The sensing depth can be extended to as large as 1.5 to 2 cm compared with the more typical range of 0.3 mm for conventional probes and is dramatically less affected by measurement technique variability including poor sample contact and cable bending. As a precursor to an actual clinical implementation, we study the technique in a range of homogeneous liquids with substantially varying dielectric properties. The initial results demonstrate good agreement between the transmission-based probe and commercial, reflection-based probes and pave the way for more substantial clinical implementation.

scholarly journals Inverse modelling of national and European CH<sub>4</sub> emissions using the atmospheric zoom model TM5

2005 ◽  
Vol 5 (9) ◽  
pp. 2431-2460 ◽  
Author(s):  
P. Bergamaschi ◽  
M. Krol ◽  
F. Dentener ◽  
A. Vermeulen ◽  
F. Meinhardt ◽  
...  
Keyword(s):  
A Priori ◽  
A Priori Estimate ◽  
European Countries ◽  
Synoptic Scale ◽  
Source Attribution ◽  
Top Down ◽  
Ch4 Emissions ◽  
Model Driven ◽  
Good Agreement ◽  
The Eu

Abstract. A synthesis inversion based on the atmospheric zoom model TM5 is used to derive top-down estimates of CH4 emissions from individual European countries for the year 2001. We employ a model zoom over Europe with 1° × 1° resolution that is two-way nested into the global model domain (with resolution of 6° × 4°. This approach ensures consistent boundary conditions for the zoom domain and thus European top-down estimates consistent with global CH4 observations. The TM5 model, driven by ECMWF analyses, simulates synoptic scale events at most European and global sites fairly well, and the use of high-frequency observations allows exploiting the information content of individual synoptic events. A detailed source attribution is presented for a comprehensive set of 56 monitoring sites, assigning the atmospheric signal to the emissions of individual European countries and larger global regions. The available observational data put significant constraints on emissions from different regions. Within Europe, in particular several Western European countries are well constrained. The inversion results suggest up to 50-90% higher anthropogenic CH4 emissions in 2001 for Germany, France and UK compared to reported UNFCCC values (EEA, 2003). A recent revision of the German inventory, however, resulted in an increase of reported CH4 emissions by 68.5% (EEA, 2004), being now in very good agreement with our top-down estimate. The top-down estimate for Finland is distinctly smaller than the a priori estimate, suggesting much smaller CH4 emissions from Finnish wetlands than derived from the bottom-up inventory. The EU-15 totals are relatively close to UNFCCC values (within 4-30%) and appear very robust for different inversion scenarios.

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