bluuebunny/crossref_metadata_2025 huggingface dataset:
Potential Pitfalls of Pollen Dating
Authors: Neulieb Thomas , Levac Elisabeth , Southon John , Lewis Michael , Pendea I Florin , Chmura Gail L
Published: January 2017

Pollen extracted from ocean and wetland sediments cored from the eastern Canadian Margin, James Bay region, and Atlantic provinces of Canada have been radiocarbon dated and results are reported here. Pollen dates from ocean sediments were compared with marine carbonate (mollusk shells or foraminifera) dates from the same core levels, dates for which validity was assessed via correlations with other cores, and for which reworking has been excluded. Pollen samples from 3 tidal wetlands were taken from levels dated with 137Cs and 210Pb profiles. Pollen dates from 2 additional wetlands were compared with 14C dates of botanical macrofossils. Most pollen dates disagree with 14C dates based on macrofossils or carbonates, with age differences typically exceeding 250 yr and reaching 4000 yr in one instance. In some cores, pollen dates show age reversals. Significant proportions of reworked pollen grains in ocean and wetland samples are associated with pollen dates that are too old. Prolonged core storage could result in pollen 14C ages that are too young, possibly because of growth of fungi or other microbes, but more work is needed to verify this hypothesis. Despite the problems we encountered, some pollen dates are consistent with other 14C dates from the same core levels, suggesting this dating method can work, but at present, more work is needed to understand the conflicting results obtained.
Planktonic Foram Dates from the Indonesian Arc: Marine 14C Reservoir Ages and a Mythical AD 535 Eruption of Krakatau
Authors: Southon John , Mohtadi Mahyar , De Pol-Holz Ricardo
Published: January 2017

The Indonesian Arc represents the subduction of the Indian-Australian plate beneath Asia. It has been the scene of catastrophic tectonic activity, including the recent 2004 M=9.1 Aceh earthquake and resulting Indian Ocean tsunami. We have dated planktonic forams associated with historic tephras (Tambora, 1815 and Krakatau, 1883) in marine sediment cores to determine radiocarbon reservoir ages for 2 locations along the arc. Our best estimates for 19th century regional reservoir corrections (ΔR) are +90 ± 40 yr for surface-dwelling species and +220 ± 40 yr for mixed planktic assemblages containing some upper thermocline species, but scatter in the data suggests that past surface reservoir ages may have varied by about ±100 yr. We used the results of this study to investigate a proposed very large AD 535 eruption at or near Krakatau. We find no evidence for ash from such an eruption, and although this is negative evidence, we consider it sufficiently strong to rule out any possibility that one took place.
Radiocarbon Wiggle-Match Dating of Bulk Sediments—How Accurate can It Be?
Authors: Mellström Anette , Muscheler Raimund , Snowball Ian , Ning Wenxin , Haltia Eeva
Published: January 2017

We used the radiocarbon wiggle-match dating technique to date the varved sediments of Lake Gyltigesjön in southern Sweden with the main aim to construct an accurate chronology covering the period between about 3000 and 2000 cal BP. Wiggle-match dating was applied to bulk sediments to evaluate the possibility of constructing accurate chronologies in the absence of terrestrial plant macrofossils and when the amount of old carbon in the sediments is unknown. Facilitated by a floating varve chronology and relatively stable14C reservoir ages, the results show the possibility to assess the contribution of old carbon solely based on the14C wiggle-matching of bulk sediments. We confirm the wiggle-matched chronology and the14C reservoir age of approximately 260 yr by cross-checking the results with14C dating of macrofossils. The obtained calibrated ages based on bulk sediments have an uncertainty range of about 60–65 yr (95.4% confidence interval). This study confirms that14C wiggle-match dating of bulk sediments is a viable tool when constructing high-resolution chronologies. The method is especially useful in Sun-climate studies since the timing between solar activity variations (expressed as14C variations) and climate changes can be accurately determined.
Building the Radiocarbon Chronology for the Archaeological Site Ufa-II, Bashkortostan, Russia: Is this the Elusive “Bashkort” of Medieval Sources?
Authors: Levchenko Vladimir A , Sungatov Flarit A
Published: January 2017

A suite of accelerator mass spectrometry (AMS) radiocarbon dates for the Ufa-II archaeological site in Bashkortostan, Russia, is obtained for the first time. Dating was done on charcoal samples from a sequence of cultural deposits collected during the 2011 digging season. An age-depth chronology is established using the Bayesian deposition General Outlier P_Sequence model. The oldest age for the site at the horizon immediately over the sterile ground was cal AD 137–237 (68% probability), corresponding to the beginning of site occupation. The youngest 14C date found was late 6th to early 7th century cal AD for the extensive planked boardwalks unearthed at the site. The 14C dates are in good agreement with archaeological determinations based on discovered artifacts.
Reconstructing Human Subsistence Strategies During the Korean Neolithic: Contributions from Zooarchaeology, Geosciences, and Radiocarbon Dating
Authors: Bae Kidong , Bae Christopher J , Kim Jong Chan
Published: January 2017

The Neolithic in Korea began around 10,000 BP and is the period when many substantial changes appear in the archaeological record. In particular, one of the important changes is from a subsistence strategy that relied primarily on hunted, fished, and collected food packages to a diet that by the beginning of the Bronze Age (∼3500 BP) saw intensive agriculture as the primary form of sustenance. This paper discusses current research on this topic, in addition to presenting a comprehensive list of raw accelerator mass spectrometry (AMS) data from Korean Neolithic sites, particularly data that only became available over the past several years.
The Strange Case of the Ankhpakhered Mummy: Results of AMS 14C Dating
Authors: Quarta G , Malgora S , D'Elia M , Gaballo V , Braione E , Maruccio L , Corvaglia C , Calcagnile L
Published: January 2017

The ancient Egyptian mummy discovered in the wooden coffin of Ankhpakhered, priest of the god Min, has been studied at CEDAD (Centre for Dating and Diagnostics) at the University of Salento, Italy. The CT scan, performed by the multidisciplinary team of the Mummy Project of Milan, highlighted unusual features of the mummy, suggesting a reuse of the sarcophagus. Furthermore, specimens were taken via endoscopy for accelerator mass spectrometry (AMS) radiocarbon dating and Fourier transform infrared (FTIR) analyses, which have been carried out at CEDAD.
Fossil and Non-Fossil Sources of Different Carbonaceous Fractions in Fine and Coarse Particles by Radiocarbon Measurement
Authors: Zhang Y L , Zotter P , Perron N , Prévôt A S H , Wacker L , Szidat S
Published: January 2017

Radiocarbon offers a unique possibility for unambiguous source apportionment of carbonaceous particles due to a direct distinction of non-fossil and fossil carbon. In this work, particulate matter of different size fractions was collected at 4 sites in Switzerland to examine whether fine and coarse carbonaceous particles exhibit different fossil and contemporary sources. Elemental carbon (EC) and organic carbon (OC) as well as water-soluble OC (WSOC) and water-insoluble OC (WINSOC) were separated and determined for subsequent 14C measurement. In general, both fossil and non-fossil fractions in OC and EC were found more abundant in the fine than in the coarse mode. However, a substantial fraction (∼20 ± 5%) of fossil EC was found in coarse particles, which could be attributed to traffic-induced non-exhaust emissions. The contribution of biomass burning to coarse-mode EC in winter was relatively high, which is likely associated to the coating of EC with organic and/or inorganic substances emitted from intensive wood burning. Further, fossil OC (i.e. from vehicle emissions) was found to be smaller than non-fossil OC due to the presence of primary biogenic OC and/or growing in size of wood-burning OC particles during aging processes. 14C content in WSOC indicated that the second organic carbon rather stems from non-fossil precursors for all samples. Interestingly, both fossil and non-fossil WINSOC concentrations were found to be higher in fine particles than in coarse particles in winter, which is likely due to primary wood burning emissions and/or secondary formation of WINSOC.
Concentration of Radiocarbon in Soil-Respired CO2 Flux: Data-Model Comparison for Three Different Ecosystems in Southern Poland
Authors: Gorczyca Z , Kuc T , Rozanski K
Published: January 2017

We report and compare the results of long-term observations (1998–2006) of monthly mean soil CO2 fluxes and their carbon isotope composition, carried out at 3 sites with contrasting characteristics: 1) a grassland site located in the urban area of Krakow, southern Poland, which was exposed to anthropogenic impact for more than a century; 2) a mixed forest site; and 3) cultivated agricultural field site. A closed-chamber, dynamic sampling system was used to collect monthly cumulative samples of soil-respired CO2. The CO2 collected at the mixed forest site was enriched in 14C with respect to European free-atmosphere continental 14CO2 background (high-altitude station Jungfraujoch in Swiss Alps) by approximately 40%, while the urban site revealed 14C depletion by ∼30% against the same reference. The Δ14C values observed at the agricultural site were lying in between, clustering along the regional reference atmospheric Δ14CO2 trend curve. The Δ14C values of soil-respired CO2 at the urban site turned out to be indistinguishable from the Δ14CO2 values in the local atmosphere. For the estimation of mean turnover time of soil carbon for each of the monitored sites, we used a multicompartment model (MCM) accounting for input of carbon to the soil profile via deposition of fresh organic matter, as well as 3 different sources of CO2 in the soil profile: 1) root respiration; 2) “fast”; and 3) “slow” pools of soil carbon. The estimated mean turnover time of carbon in the “fast” carbon pool was ∼14 yr for both urban grassland and mixed forest sites, and ∼22 yr for the cultivated agricultural field. From the observed differences in Δ14C values of the measured fluxes of soil-respired CO2, we conclude that 14C content of the biogenic component in the local atmospheric CO2 is site-specific and may differ significantly from the regional atmospheric background Δ14CO2 value. Therefore, the assumption widely used in 14C-based assessments of the fossil-fuel contribution local atmospheric CO2 load, stating that 14C concentration in the biogenic CO2 component is equal to that of regional atmospheric reference value, needs to be carefully evaluated on a case-by-case basis.
Estimating the Amount of 14CO2 in the Atmosphere During the Holocene and Glacial Periods
Authors: Svetlik I , Povinec P P , Brabcova K Pachnerova , Fejgl M , Tomaskova L , Turek K
Published: January 2017

Radiocarbon has been used to define parameters for modeling past, recent, and future CO2/carbon amounts in the atmosphere and in other environmental compartments. In the present paper, we estimate the amount of 14C in the atmosphere by calculating the molar activity of 14CO2 (quantity of 14CO2 molecules per mol of air). Data on the reconstruction of the past concentration of atmospheric CO2 from Antarctic ice cores and Δ14C activities from the IntCal09 calibration curve were applied. The results obtained indicate that cosmogenic production had a dominant influence on the 14C amount in the atmosphere between 50 and 20 ka BP, when the CO2 concentrations were relatively stable, with a slowly decreasing trend. The decreasing 14C activity (Δ14C) between 20 and 2 ka BP seems to be caused predominantly by a dilution of atmospheric 14CO2 by input of CO2 with a depleted amount of 14C (probably from deeper oceanic layers), which is evident from a comparison with the Δ14C and molar activity time series. A strong linear relation was found between the 14C activity and CO2 concentration in the air for the period 20–2 ka BP, which confirms a dominant influence of atmospheric dilution of 14CO2. The observed linear relation between the CO2 and Δ14C levels persists even in the prevailing part of the Holocene. Likewise, the quantity of 14CO2 in the atmosphere (calculated as molar activity) during the prevailing part of the deglacial period (20–11 ka BP) was surprisingly increasing, although a decreasing trend in the 14C cosmogenic production rate could be expected.
Simulated Last Glacial Maximum Δ14Catm and the Deep Glacial Ocean Carbon Reservoir
Authors: Mariotti V , Paillard D , Roche D M , Bouttes N , Bopp L
Published: January 2017

Δ14Catm has been estimated as 420 ± 80% (IntCal09) during the Last Glacial Maximum (LGM) compared to preindustrial times (0%), but mechanisms explaining this difference are not yet resolved. Δ14Catm is a function of both cosmogenic production in the high atmosphere and of carbon cycling and partitioning in the Earth system. 10Be-based reconstructions show a contribution of the cosmogenic production term of only 200 ± 200% in the LGM. The remaining 220% have thus to be explained by changes in the carbon cycle. Recently, Bouttes et al. (2010, 2011) proposed to explain most of the difference in pCO2atm and Δ13C between glacial and interglacial times as a result of brine-induced ocean stratification in the Southern Ocean. This mechanism involves the formation of very saline water masses that contribute to high carbon storage in the deep ocean. During glacial times, the sinking of brines is enhanced and more carbon is stored in the deep ocean, lowering pCO2atm. Moreover, the sinking of brines induces increased stratification in the Southern Ocean, which keeps the deep ocean well isolated from the surface. Such an isolated ocean reservoir would be characterized by a low Δ14C signature. Evidence of such 14C-depleted deep waters during the LGM has recently been found in the Southern Ocean (Skinner et al. 2010). The degassing of this carbon with low Δ14C would then reduce Δ14Catm throughout the deglaciation. We have further developed the CLIMBER-2 model to include a cosmogenic production of 14C as well as an interactive atmospheric 14C reservoir. We investigate the role of both the sinking of brine and cosmogenic production, alongside iron fertilization mechanisms, to explain changes in Δ14Catm during the last deglaciation. In our simulations, not only is the sinking of brine mechanism consistent with past Δ14C data, but it also explains most of the differences in pCO2atm and Δ14Catm between the LGM and preindustrial times. Finally, this study represents the first time to our knowledge that a model experiment explains glacial-interglacial differences in pCO2atm, Δ13C, and Δ14C together with a coherent LGM climate.
A High-Resolution Coral-Based Δ14C Record of Surface Water Processes in the Western Mediterranean Sea
Authors: Tisnérat-Laborde Nadine , Montagna Paolo , McCulloch Malcolm , Siani Giuseppe , Silenzi Sergio , Frank Norbert
Published: January 2017

The first high-resolution time series of pre- and post-bomb radiocarbon measurements is reported for surface waters in the western Mediterranean Sea. The Δ14C record was obtained from the aragonite skeleton of Cladocora caespitosa using a 50-yr-old corallite collected in the Ligurian Sea in 1998. Laser-ablation ICP measurements of trace elements (Li/Mg and Sr/Ca) show a strong seasonal variability, enabling the chronology of the Δ14C record to be determined at annual timescales. The mean Δ14C of pre-bomb surface water is -56 ± 3%, corresponding to a reservoir age of 262 ± 29 yr. The post-bomb maximum occurs in 1972 with a Δ14C value of 90%, significantly lower than the peak of 150% observed in the North Atlantic. The dilution of the peak-amplitude of Δ14C in western Mediterranean surface waters is attributed to mixing of North Atlantic Central Water inflow with relatively depleted underlying Intermediate Mediterranean and Levantine Intermediate waters. Intensification of this mixing is observed in 1963–1964, consistent with the change in atmospheric circulation from a positive to negative NAO phase (1960–1967). The post-peak Δ14C variability is relatively limited, reflecting mainly local vertical mixing forced by wind stress.
Comparison of Particulate Organic and Dissolved Inorganic Radiocarbon Signatures in the Surface Northeast Pacific Ocean
Authors: Bertrand Chanda , Walker Brett , Griffin Sheila , Druffel E R M
Published: January 2017

It has long been assumed that radiocarbon (Δ14C) content of dissolved inorganic carbon (DIC) is equal to that of particulate organic carbon (POC) in surface seawater; however, little research has been conducted to explicitly test this assumption. Here, we report Δ14C measurements of surface POC samples and compare them with contemporaneous DIC Δ14C measurements from the northeast Pacific Ocean (Hwang et al. 2004; Druffel et al. 2010). Samples were collected from surface waters at Station M off California between 1995 and 2004. The POC Δ14C values decreased 3.2% per year from 1995 to 2004, similar to the decline observed in the DIC Δ14C values during the same period. Overall, our results show no statistical difference between POC and DIC Δ14C—consistent with the assumption that DIC and POC Δ14C values can generally be considered equivalent. However, significant variability was observed for POC Δ14C values during several fall/summer events, where POC Δ14C signatures were lower than DIC Δ14C values. An evaluation of 2 sample pretreatments also suggests that non-homogenized POC samples deviated less from average POC Δ14C values and more closely matched the DIC Δ14C average for the time series. The presence of seasonal POC/DIC Δ14C disagreements, combined with sample processing effects, suggest that infrequent contributions of allochthonous, older carbon may have originated from deeper in the water column, especially during periods when upwelling in this area was prominent.
Spatial Distribution of Radiocarbon in the Southwestern Japan/East Sea Immediately After Bottom Water Renewal
Authors: Aramaki Takafumi , Tanaka Shinichi S , Kushibashi Seiko , Kim Young-Il , Kim Chang-Jun , Hong Gi-Hoon , Senjyu Tomoharu
Published: January 2017

In April 2001, immediately after bottom water renewal in the Japan/East Sea, 7 vertical profiles of radiocarbon were obtained from the area, including the Japan Basin and the Tsushima/Ulleung Basin. The bottom water Δ14C of the Tsushima/Ulleung Basin increased by 24% during 1979–2001 and was 10–15% higher than the values reported for the Japan Basin and Yamato Basin during 1995–2002. Within the depth interval 800–2000 m, Δ14C values at the southernmost station in the Japan Basin were much higher than at other stations, with the maximum difference in Δ14C values being more than 50%. Based on a combination of physical observations with analysis of the Δ14C data, we concluded that the bottom water, which was formed by the sinking of surface water off Vladivostok, Russia, in late January-early February of 2001, had been widely distributed to depths below 2000 m within the southernmost Japan Basin in a timespan shorter than 2 months. However, there was no evidence that the water had been transported into the Tsushima/Ulleung Basin during the same time interval.
Radiocarbon Determination of Past Growth Rates of Living Acacia Tortilis Trees from Two Arid Sites in the Eastern Sahara
Authors: Goslar Tomasz , Andersen Gidske , Krzywinski Knut , Czernik Justyna
Published: January 2017

Reconstructions arc presented of past growth rates of 10 Acacia tortilis trees, 5 growing at an arid site (Gebeit, Sudan) and 5 at a hyperarid site (Wadi Nuqrus, Egypt). The reconstructions were made using a free-shape age-depth model based on a series of 14C dates obtained on samples taken along the wood cores retrieved from the trunks of the trees (78 dates in total). In spite of the large difference in annual precipitation between the 2 sites, the range of ages of the trees (60–350 yr) and the variability in their growth rates are quite similar across both sites, whereas within-site growth rates are quite different even for closely spaced individuals. However, the pattern of growth rates of Acacias from the hyperarid Wadi Nuqrus indicates 2 periods of different aridity (the less arid AD 1650–1780 and more arid AD 1780–1930), while at Gebeit no such pattern has been detected.
The Radiocarbon Intracavity Optogalvanic Spectroscopy Setup at Uppsala
Authors: Eilers Gerriet , Persson Anders , Gustavsson Cecilia , Ryderfors Linus , Mukhtar Emad , Possnert Göran , Salehpour Mehran
Published: January 2017

Accelerator mass spectrometry (AMS) is by far the predominant technology deployed for radiocarbon tracer studies. Applications are widespread from archaeology to biological, environmental, and pharmaceutical sciences. In spite of its excellent performance, AMS is expensive and complicated to operate. Consequently, alternative detection techniques for14C are of great interest, with the vision of a compact, user-friendly, and inexpensive analytical method. Here, we report on the use of intracavity optogalvanic spectroscopy (ICOGS) for measurements of the14C/12C ratio. This new detection technique was developed by Murnick et al. (2008). In the infrared (IR) region, CO2molecules have strong absorption coefficients. The IR-absorption lines are narrow in line width and shifted for different carbon isotopes. These properties can potentially be exploited to detect14CO2,13CO2, or12CO2molecules unambiguously. In ICOGS, the sample is in the form of CO2gas, eliminating the graphitization step that h is required in most AMS labs. The status of the ICOGS setup in Uppsala is presented. The system is operational but not yet fully developed. Data are presented for initial results that illustrate the dependence of the optogalvanic signal on various parameters, such as background and plasma-induced changes in the sample gas composition.
A Puzzling 14C Result Obtained for a Carbonized Wood Sample Embedded in Volcanic Lava
Authors: Lee J H , Choe K , Kang J , Song S , Song Y M , Yun M H , Kim J C
Published: January 2017

It has been reported that the characteristics of a very old wood charcoal sample are different from those of modern wood charcoal according to its state of preservation (Cohen-Ofri et al. 2006; Rebollo et al. 2008). It can be assumed that these differences may lead to some difficulties when radiocarbon dating very old wood charcoal samples. To investigate this problem, we studied a carbonized trunk of Prunus pendula for. acendens tree buried in lava and found at the Hantan River lava plateau on the Korean Peninsula. The 14C date of this sample was previously measured as >30,000 BP. However, separate 14C results of its outer crust and inner wood showed a considerable difference, exceeding the estimated age differences by tree-ring counting. To study the reason for this discrepancy, optical microscopy and FTIR (Fourier transform infrared spectroscopy) were performed to examine the differences in the structural and chemical states of the samples. For reference data and to expand our understanding of very old wood charcoal, we applied the same analysis tools (AMS, FTIR, FE-SEM, EDS, and optical microscopy) to a variety of wood charcoals and original wood. From these analyses, we noticed considerable chemical changes in the outer crust sample, and this might explain the age discrepancy. Although it seems that the age difference might be due to the digestion of 14C-free CO2 from a volcanic environment, this explanation would not account for such a large value in the age difference.
Radiocarbon Dating of Mortars from the Baptismal Font of the San Lorenzo Cathedral of Alba (Cuneo, Italy): Comparison with Thermoluminescence Dating of Related Bricks and Pipes
Authors: Pesce Giovanni L , Micheletto Egle , Quarta Gianluca , Uggè Sofia , Calcagnile Lucio , Decri Anna
Published: January 2017

The San Lorenzo Cathedral of Alba is a Romanesque church (rebuilt in Gothic epoch) located in northwest Italy. Since 2007, this church has been subjected to renovations and archaeological excavations that led to the finding of the lower part of the basin and the water drainage pipe of a baptismal font of unknown age. Thermoluminescence and radiocarbon dating have been carried out respectively on some ceramic elements and lime mortar samples used in both the pipe and basin of the font. Thermoluminescence results suggest that some of the bricks may have been reused from previous structures while 14C results suggest that the font was built between the 9th and the 11th centuries AD, most probably in the 10th century AD.
14C/12C Variations of Samples Exposed in Air According to Carbon Structure and Air Temperature
Authors: Park J H , Hong W , Park G , Sung K S
Published: January 2017

Various carbon structures, including carbon nanofilament (CNF), single-wall carbon nanotube (SWCNT), multi-wall carbon nanotube (MWCNT), and pyrolytic graphite sheet (PGS), were exposed in air to determine how they vary according to carbon structure and air temperature. CNF is the carbon structure used in accelerator mass spectrometry (AMS) radiocarbon dating (Santos et al. 2007). When CNF and MWCNT were exposed in cold air (3 or −18 °C) for longer than 6 hr, their 14C/12C ratio increased (>5 × 10–14). When heated in an oven (200 or 250 °C) for longer than 12 hr, their 14C/12C ratio decreased. However, when SWCNT and PGS were exposed in air cooled to 3 °C for 12 hr, their 14C/12C ratio did not increase. This phenomenon is very curious, and is useful for the development of a storage method for carbon samples made by reduction reactions of CO2.
Intercomparison of Models of 14C in the Biosphere for Solid Radioactive Waste Disposal
Authors: Mobbs Shelly , Shaw George , Norris Simon , Marang Laura , Sumerling Trevor , Albrecht Achim , Xu Shulan , Thorne Mike , Limer Laura , Smith Karen , Smith Graham
Published: January 2017

Radiocarbon is present in solid radioactive wastes arising from the nuclear power industry, in reactor operating wastes, and in graphite and activated metals that will arise from reactor decommissioning. Its half-life of 5730 yr, among other factors, means that 14C may be released to the biosphere from radioactive waste repositories. These releases may occur as 14C-bearing gases, especially methane, or as aqueous species, and enter the biosphere from below via natural processes or via groundwater pumped from wells. Assessment of radiation doses to humans due to such releases must take account of the major role of carbon in biological processes, requiring specific 14C assessment models to be developed. Therefore, an intercomparison of 5 14C assessment models was organized by the international collaborative forum, BIOPROTA. The intercomparison identified significantly different results for the activity concentrations in the soil, atmosphere, and plant compartments, based upon the different modeling approaches. The major source of uncertainty was related to the identification of conditions under which mixing occurs and isotopic equilibrium is established. Furthermore, while the assumed release area plays a role in determining the calculated atmospheric 14C concentrations, the openness of the plant canopy and the wind profile in and above the canopy are the key drivers. The intercomparison has aided understanding of the processes involved and helped to identify areas where further research is required to address some of the uncertainties.
Evolutionary and ecological aspects of recalcitrant seed biology
Authors: Pammenter N.W. , Berjak Patricia
Published: January 2017

There is a substantial literature on the basic physiology and response to desiccation of recalcitrant seeds, but little is known about their ecology and even less of their evolutionary status. It is difficult to assess the response of early land plants to dehydration, but it is likely that desiccation tolerance in vegetative tissue arose concomitantly with the invasion of the land. Similarly, from the fossil record it is not possible to assess the desiccation response of early seeds, and furthermore, it is difficult to see phylogenetic relationships among species producing recalcitrant seeds. A consideration of the available evidence, however, suggests that the first seeds were desiccation-sensitive, but tolerance evolved early and probably a number of times, independently. The desiccation sensitivity and short life span (generally shorter than the interval between flowering) of recalcitrant seeds have implications in terms of regeneration ecology. A long-term soil seed bank as such does not exist; rather the seeds germinate and form a seedling bank. However, there is a wide range in post-shedding physiology among recalcitrant seed species, and although species producing recalcitrant seeds are common in the humid tropics, they do occur in habitats with more marked seasonal variation. Here regeneration strategies may be more specialized.
An extensive suprarenal inferior vena cava thrombosis successfully treated with catheter-directed thrombolysis in a postpartum 14-year-old girl
Authors: Rimbas Roxana Cristina , Călin Simona Ionela , Ionescu Horatiu , Dorobat Bogdan , Vinereanu Dragos , Cinteza Mircea
Published: January 2017

Abstract. We report a case of extensive early postpartum acute suprarenal inferior vena cava thrombosis in a 14-year-old girl. Management included catheter-directed-thrombolysis, aiming to save renal function and prevent fatal pulmonary embolism. Treatment decisions were mostly based on adult guidelines, as guidelines for the paediatric population are not yet available.
Postelection Angst Spurs Some Women Scientists to Ally and Act
Authors: Sidder Aaron
Published: January 2017

An advocacy group for women scientists has formed in reaction to the contentious 2016 U.S. presidential campaign and expects to participate in the Women's March on Washington this weekend.
Quantum interference between transverse spatial waveguide modes
Authors: Mohanty Aseema , Zhang Mian , Dutt Avik , Ramelow Sven , Nussenzveig Paulo , Lipson Michal
Published: January 2017

Integrated quantum optics has the potential to markedly reduce the footprint and resource requirements of quantum information processing systems, but its practical implementation demands broader utilization of the available degrees of freedom within the optical field. To date, integrated photonic quantum systems have primarily relied on path encoding. However, in the classical regime, the transverse spatial modes of a multi-mode waveguide have been easily manipulated using the waveguide geometry to densely encode information. Here, we demonstrate quantum interference between the transverse spatial modes within a single multi-mode waveguide using quantum circuit-building blocks. This work shows that spatial modes can be controlled to an unprecedented level and have the potential to enable practical and robust quantum information processing.
Rapid generation of hypomorphic mutations
Authors: Arthur Laura L. , Chung Joyce J. , Janakirama Preetam , Keefer Kathryn M. , Kolotilin Igor , Pavlovic-Djuranovic Slavica , Chalker Douglas L. , Grbic Vojislava , Green Rachel , Menassa Rima , True Heather L. , Skeath James B. , Djuranovic Sergej
Published: January 2017

Hypomorphic mutations are a valuable tool for both genetic analysis of gene function and for synthetic biology applications. However, current methods to generate hypomorphic mutations are limited to a specific organism, change gene expression unpredictably, or depend on changes in spatial-temporal expression of the targeted gene. Here we present a simple and predictable method to generate hypomorphic mutations in model organisms by targeting translation elongation. Adding consecutive adenosine nucleotides, so-called polyA tracks, to the gene coding sequence of interest will decrease translation elongation efficiency, and in all tested cell cultures and model organisms, this decreases mRNA stability and protein expression. We show that protein expression is adjustable independent of promoter strength and can be further modulated by changing sequence features of the polyA tracks. These characteristics make this method highly predictable and tractable for generation of programmable allelic series with a range of expression levels.
Brain microvasculature defects and Glut1 deficiency syndrome averted by early repletion of the glucose transporter-1 protein
Authors: Tang Maoxue , Gao Guangping , Rueda Carlos B. , Yu Hang , Thibodeaux David N. , Awano Tomoyuki , Engelstad Kristin M. , Sanchez-Quintero Maria-Jose , Yang Hong , Li Fanghua , Li Huapeng , Su Qin , Shetler Kara E. , Jones Lynne , Seo Ryan , McConathy Jonathan , Hillman Elizabeth M. , Noebels Jeffrey L. , De Vivo Darryl C. , Monani Umrao R.
Published: January 2017

Haploinsufficiency of theSLC2A1gene and paucity of its translated product, the glucose transporter-1 (Glut1) protein, disrupt brain function and cause the neurodevelopmental disorder, Glut1 deficiency syndrome (Glut1 DS). There is little to suggest how reduced Glut1 causes cognitive dysfunction and no optimal treatment for Glut1 DS. We used model mice to demonstrate that low Glut1 protein arrests cerebral angiogenesis, resulting in a profound diminution of the brain microvasculature without compromising the blood–brain barrier. Studies to define the temporal requirements for Glut1 reveal that pre-symptomatic, AAV9-mediated repletion of the protein averts brain microvasculature defects and prevents disease, whereas augmenting the protein late, during adulthood, is devoid of benefit. Still, treatment following symptom onset can be effective; Glut1 repletion in early-symptomatic mutants that have experienced sustained periods of low brain glucose nevertheless restores the cerebral microvasculature and ameliorates disease. Timely Glut1 repletion may thus constitute an effective treatment for Glut1 DS.
Esterase mutation is a mechanism of resistance to antimalarial compounds
Authors: Istvan Eva S. , Mallari Jeremy P. , Corey Victoria C. , Dharia Neekesh V. , Marshall Garland R. , Winzeler Elizabeth A. , Goldberg Daniel E.
Published: January 2017

Pepstatin is a potent peptidyl inhibitor of various malarial aspartic proteases, and also has parasiticidal activity. Activity of pepstatin against cultured Plasmodium falciparum is highly variable depending on the commercial source. Here we identify a minor contaminant (pepstatin butyl ester) as the active anti-parasitic principle. We synthesize a series of derivatives and characterize an analogue (pepstatin hexyl ester) with low nanomolar activity. By selecting resistant parasite mutants, we find that a parasite esterase, PfPARE (P. falciparum Prodrug Activation and Resistance Esterase) is required for activation of esterified pepstatin. Parasites with esterase mutations are resistant to pepstatin esters and to an open source antimalarial compound, MMV011438. Recombinant PfPARE hydrolyses pepstatin esters and de-esterifies MMV011438. We conclude that (1) pepstatin is a potent but poorly bioavailable antimalarial; (2) PfPARE is a functional esterase that is capable of activating prodrugs; (3) Mutations in PfPARE constitute a mechanism of antimalarial resistance.
Enhanced superconductivity in TiO epitaxial thin films
Authors: Zhang Chao , Hao Feixiang , Gao Guanyin , Liu Xiang , Ma Chao , Lin Yue , Yin Yuewei , Li Xiaoguang
Published: January 2017

Titanium oxides have many fascinating optical and electrical properties, such as the superconductivity at 2 K in cubic titanium monoxide (TiO) polycrystalline bulk. However, the lack of TiO single crystals or epitaxial films has prevented systematic investigations on its superconductivity. Here, we report the basic superconductivity characterizations of cubic TiO films epitaxially grown on (0001)-oriented α-Al2O3 substrates. The magnetic and electronic transport measurements confirmed that TiO is a type-II superconductor and the recorded high Tc is about 7.4 K. The lower critical field (Hc1) at 1.9 K, the extrapolated upper critical field Hc2(0), and coherence length are about 18 Oe, 13.7 T, and 4.9 nm, respectively. With increasing pressure, the value of Tc shifts to lower temperature while the normal state resistivity increases. Our results on the superconducting TiO films confirm the strategy to achieve higher Tc in the epitaxial films, which may be helpful for finding more superconducting materials in various related systems.
Scale-dependent diffusion anisotropy in nanoporous silicon
Authors: Kondrashova Daria , Lauerer Alexander , Mehlhorn Dirk , Jobic Hervé , Feldhoff Armin , Thommes Matthias , Chakraborty Dipanjan , Gommes Cedric , Zecevic Jovana , de Jongh Petra , Bunde Armin , Kärger Jörg , Valiullin Rustem
Published: January 2017

Nanoporous silicon produced by electrochemical etching of highly B-doped p-type silicon wafers can be prepared with tubular pores imbedded in a silicon matrix. Such materials have found many technological applications and provide a useful model system for studying phase transitions under confinement. This paper reports a joint experimental and simulation study of diffusion in such materials, covering displacements from molecular dimensions up to tens of micrometers with carefully selected probe molecules. In addition to mass transfer through the channels, diffusion (at much smaller rates) is also found to occur in directions perpendicular to the channels, thus providing clear evidence of connectivity. With increasing displacements, propagation in both axial and transversal directions is progressively retarded, suggesting a scale-dependent, hierarchical distribution of transport resistances (“constrictions” in the channels) and of shortcuts (connecting “bridges”) between adjacent channels. The experimental evidence from these studies is confirmed by molecular dynamics (MD) simulation in the range of atomistic displacements and rationalized with a simple model of statistically distributed “constrictions” and “bridges” for displacements in the micrometer range via dynamic Monte Carlo (DMC) simulation. Both ranges are demonstrated to be mutually transferrable by DMC simulations based on the pore space topology determined by electron tomography.
Dynamical states, possibilities and propagation of stress signal
Authors: Malik Md. Zubbair , Ali Shahnawaz , Singh Soibam Shyamchand , Ishrat Romana , Singh R. K. Brojen
Published: January 2017

The stress driven dynamics of Notch-Wnt-p53 cross-talk is subjected to a few possible dynamical states governed by simple fractal rules, and allowed to decide its own fate by choosing one of these states which are contributed from long range correlation with varied fluctuations due to active molecular interaction. The topological properties of the networks corresponding to these dynamical states have hierarchical features with assortive structure. The stress signal driven by nutlin and modulated by mediator GSK3 acts as anti-apoptotic signal in this system, whereas, the stress signal driven by Axin and modulated by GSK3 behaves as anti-apoptotic for a certain range of Axin and GSK3 interaction, and beyond which the signal acts as favor-apoptotic signal. However, this stress system prefers to stay in an active dynamical state whose counterpart complex network is closest to hierarchical topology with exhibited roles of few interacting hubs. During the propagation of stress signal, the system allows the propagator pathway to inherit all possible properties of the state to the receiver pathway/pathways with slight modifications, indicating efficient information processing and democratic sharing of responsibilities in the system via cross-talk. The increase in the number of cross-talk pathways in the system favors to establish self-organization.
Clumping factor A of Staphylococcus aureus interacts with AnnexinA2 on mammary epithelial cells
Authors: Ashraf Shoaib , Cheng Jing , Zhao Xin
Published: January 2017

Staphylococcus aureus is one of major pathogens that can cause a series of diseases in different hosts. In the bovine, it mainly causes subclinical and contagious mastitis, but its mechanisms of infection are not fully understood. Considering the fact that virulence factors play key roles in interactions between the bacterium and host cells, this study aimed to identify if a binding partner of S. aureus clumping factor A (ClfA) exists on the bovine mammary epithelial cells. The ClfA protein was used as a bait to pull down lysates of cultured bovine mammary epithelial cells (MAC-T cells). One pull-down protein was identified through use of mass spectrometry and bioinformatics analyses as bovine AnnexinA2. The Western blot and in vitro binding assay confirmed that the full A domain of ClfA was necessary to bind to AnnexinA2. In addition, the interaction between ClfA and AnnexinA2 was validated biochemically by ELISA with a KD value of 418+/−93 nM. The confocal microscopy demonstrated that ClfA and AnnexinA2 partially co-localized in the plasma membrane and that the majority of them were transported into cytoplasm. Taken together, the results demonstrate that ClfA binds with AnnexinA2 and this interaction could mediate S. aureus invasion into bovine mammary epithelial cells.
The β-globin Replicator greatly enhances the potential of S/MAR based episomal vectors for gene transfer into human haematopoietic progenitor cells
Authors: Stavrou Eleana F. , Lazaris Vassileios M. , Giannakopoulos Aristeidis , Papapetrou Eirini , Spyridonidis Alexandros , Zoumbos Nikolas C. , Gkountis Antonis , Athanassiadou Aglaia
Published: January 2017

Specific human chromosomal elements enhance the performance of episomal gene-transfer vectors. S/MAR-based episomal vector pEPI-eGFP transfects CD34+ haematopoietic cells, but only transiently. To address this issue we reinforced (1) transgene transcription by replacing the CMV promoter driving eGFP with the EF1/HTLV or SFFV promoters to produce vectors pEPI-EF1/HTLV and pEPI-SFFV, respectively; and (2) plasmid replication by inserting the replication-Initiation Region (IR) from the β-globin locus into vector pEPI-SFFV to produce vector pEP-IR. All vectors supported stable transfections in K562 cells. Transfections of CD34+ cells from peripheral blood of healthy donors reached 30% efficiency. Upon evaluation of CD34+/eGFP+ cells in colony-forming cell (CFC) assays, vector pEP-IR showed superior performance after 14 days, by fluorescent microscopy: 100% eGFP+-colonies against 0% for pEPI-eGFP, 56.9% for pEPI-SFFV and 49.8% for pEPI-EF1/HTLV; 50% more plasmid copies per cell and 3-fold eGFP expression compared to the latter two constructs, by quantitative (q)PCR and RT-qPCR, respectively. Importantly, the establishment rate in CFC assays was 15% for pEP-IR against 5.5% for pEPI-SFFV and 5% for pEPI-EF1/HTLV. Vector pEP-IR shows extremely low delivery rate but supports eGFP expression in thalassaemic mouse haematopoietic progenitor cells. The IR is a novel human control element for improved episomal gene transfer into progenitor cells.
Evaluation of Three Block Anesthesia Methods for Pain Management During Mandibular Third Molar Extraction: A Meta-analysis
Authors: Yu Fanyuan , Xiao Yao , Liu Hanghang , Wu Fanzi , Lou Feng , Chen Dian , Bai Mingru , Huang Dingming , Wang Chenglin , Ye Ling
Published: January 2017

A patient’s pain during mandibular third molar extraction often creates problems for a dental surgeon and can also cause immense patient discomfort, such as decreased quality of life, serious complications, or even danger to the patients’ lives. Effective pain management is therefore of great importance. Conventional block anesthesia method often fails to control such pain completely during an operation. Therefore, two available alternatives, Gow-Gates (G-G) and Vazirani-Akinosi (V-A) methods, have been developed. However, the results of current studies regarding their effectiveness and safety are somewhat ambiguous. The use of G-G and V-A techniques is therefore restricted. This study did a comprehensive review of the relevant research and finally 7 RCTs were included. The results of this meta-analysis indicate that both G-G and V-A techniques have a lower risk of positive aspiration. G-G technique also evidenced a higher success rate than the conventional method. V-A was faster while the G-G technique in contrast had a slower onset time than the conventional technique. In terms of the measurement of analgesic success, however, the V-A method was statistically indistinguishable from conventional techniques. These findings will hopefully endow clinicians with the knowledge required to make appropriate choices for effective anesthesia during lower third molar extraction.
Diverse strategies of O2 usage for preventing photo-oxidative damage under CO2 limitation during algal photosynthesis
Authors: Shimakawa Ginga , Matsuda Yusuke , Nakajima Kensuke , Tamoi Masahiro , Shigeoka Shigeru , Miyake Chikahiro
Published: January 2017

Photosynthesis produces chemical energy from photon energy in the photosynthetic electron transport and assimilates CO2 using the chemical energy. Thus, CO2 limitation causes an accumulation of excess energy, resulting in reactive oxygen species (ROS) which can cause oxidative damage to cells. O2 can be used as an alternative energy sink when oxygenic phototrophs are exposed to high light. Here, we examined the responses to CO2 limitation and O2 dependency of two secondary algae, Euglena gracilis and Phaeodactylum tricornutum. In E. gracilis, approximately half of the relative electron transport rate (ETR) of CO2-saturated photosynthesis was maintained and was uncoupled from photosynthesis under CO2 limitation. The ETR showed biphasic dependencies on O2 at high and low O2 concentrations. Conversely, in P. tricornutum, most relative ETR decreased in parallel with the photosynthetic O2 evolution rate in response to CO2 limitation. Instead, non-photochemical quenching was strongly activated under CO2 limitation in P. tricornutum. The results indicate that these secondary algae adopt different strategies to acclimatize to CO2 limitation, and that both strategies differ from those utilized by cyanobacteria and green algae. We summarize the diversity of strategies for prevention of photo-oxidative damage under CO2 limitation in cyanobacterial and algal photosynthesis.
Gradient-Hierarchic-Aligned Porosity SiOC Ceramics
Authors: Vakifahmetoglu Cekdar , Zeydanli Damla , Innocentini Murilo Daniel de Mello , Ribeiro Fernanda dos Santos , Lasso Paulo Renato Orlandi , Soraru Gian Domenico
Published: January 2017

This work describes a simple technique to produce porous ceramics with aligned porosity having very high permeability and specific surface area. SiOC-based compositions were processed from blends of three types of preceramic polymer and a catalyst, followed by curing and pyrolysis. The heating applied from the bottom of molds promoted the nucleation, expansion and rising of gas bubbles, and the creation of a ceramic matrix with axially oriented channels interconnected by small round pores. The samples were analyzed by SEM, tomography, BET, water immersion porosimetry and permeation to gas flow. The resulting bodies presented levels of open porosity (69.9–83.4%), average channel diameter (0.59–1.25 mm) and permeability (0.56–3.83 × 10−9 m2) comparable to those of ceramic foams and honeycomb monoliths, but with specific surface area (4.8–121.9 m2/g) typical adsorbents, enabling these lotus-type ceramics to be advantageously used as catalytic supports and adsorption components in several environmental control applications.