Observations of IRC +10216 with the Yebes 40m telescope between 31 and 50 GHz have revealed more than 150 unidentified lines. Some of them can be grouped into a new series of 26 doublets, ...harmonically related with integer quantum numbers ranging from J up=54 to 80. The separation of the doublets increases systematically with J, i.e., as expected for a linear species in one of its bending modes. The rotational parameters resulting from the fit to these data are B = 290.8844 ± 0.0004 MHz, D = 0.88 ± 0.04 Hz, q = 0.1463 ± 0.0001 MHz. The rotational constant is very close to that of the ground state of HC9N. Ab initio calculations show an excellent agreement between these parameters and those predicted for the lowest energy vibrationally excited state, ν 19=1, of HC9N. This is the first detection, and complete characterization in space, of vibrationally excited HC9N. An energy of 41.5 cm-1 is estimated for the ν 19 state. In addition, 17 doublets of HC7N in the ν 15=1 state, for which laboratory spectroscopy is available, have been detected for the first time in IRC+10216. Several doublets of HC5N in its ν 11=1 state have been also observed. The column density ratio between the ground and the lowest excited vibrational states are ≈127, 9.5, and 1.5 for HC5N, HC7N, and HC9N, respectively. We find that these lowest-lying vibrational states are most probably populated via infrared pumping to vibrationally excited states lying at ≈600 cm-1. The lowest vibrationally excited states thus need to be taken into account to precisely determine absolute abundances and abundanceratios for long carbon chains. The abundance ratios N(HC5N)/N(HC7N) and N(HC7N)/N(HC9N) are 2.4 and 7.7 respectively.
Objectives: To investigate the relationship of gap size and secondary caries in a newly developed secondary caries microbial model that permits adjustment of the gap between the tooth and a ...restoration. Methods: Tooth-resin-matrix composite specimens were mounted on gap-model stages with a gap size of 50 or 500 µm in experiment 1, and 0, 25, 250, or 1,000 µm in experiment 2. They were attached to plastic Petri plates, gas-sterilized and then incubated in a microbial caries model (with Streptococcus mutans TH16 in 1% sucrose tryptic soy broth for 1 h, 4 times/day, and with a buffer solution for the rest of the day). After 8 days of incubation, tooth specimens were sectioned and stained overnight with a rhodamine B solution. Digital images taken under a confocal microscope were analyzed for lesion size at the outer surface lesion and wall lesion (WL). Results: Gap size was found to affect the development of dentin WL area in experiment 1 and enamel and dentin WL areas in experiment 2, with bigger lesions being observed in the wider gap group (p < 0.05). Conclusion: The findings of this study suggest that the size of the gap between tooth and restoration affects the development of secondary caries along the cavity wall.
Abstract Objectives The influence of toothbrushing duration and dentifrice quantity on fluoride efficacy against dental caries is poorly understood. This study investigated effects of these two oral ...hygiene factors on enamel remineralisation (measured as surface microhardness recovery SMHR), enamel fluoride uptake (EFU), and net acid resistance (NAR) post-remineralisation in a randomized clinical study using an in situ caries model. Methods Subjects (n = 63) wore their partial dentures holding partially demineralised human enamel specimens and brushed twice-daily for two weeks, following each of five regimens: brushing for 120 or 45 s with 1.5 g of 1150 ppm F (as NaF) dentifrice; for 120 or 45 s with 0.5 g of this dentifrice; and for 120 s with 1.5 g of 250 ppm F (NaF) dentifrice. Results Comparing brushing for 120 s against brushing for 45 s, SMHR and EFU increased by 20.0% and 26.9% respectively when 1.5 g dentifrice was used; and by 22.8% and 19.9% respectively when 0.5 g dentifrice was used. Comparing brushing with 1.5 g against brushing with 0.5 g dentifrice, SMHR and EFU increased by 35.3% and 51.3% respectively when brushing for 120 s, and by 38.4% and 43.0% respectively when brushing for 45 s. Increasing brushing duration and dentifrice quantity also increased the NAR value. The effects of these two oral hygiene factors on SMHR, EFU, and NAR were statistically significant (p < 0.05 in all cases). Conclusion Brushing duration and dentifrice quantity have the potential to influence the anti-caries effectiveness of fluoride dentifrices. Study NCT01563172 on ClinicalTrials.gov. Clinical significance The effect of two key oral hygiene regimen factors – toothbrushing duration and dentifrice quantity – on fluoride’s anticaries effectiveness is unclear. This 2-week home-use in situ remineralisation clinical study showed both these factors can influence fluoride bioactivity, and so can potentially affect fluoride’s ability to protect against caries.
We report on the detection of hydromagnesium isocyanide, HMgNC, in the laboratory and in the carbon-rich evolved star IRC+10216. The J = 1-0 and J = 2-1 lines were observed in our microwave ...laboratory equipment in Valladolid with a spectral accuracy of 3 KHz. The hyperfine structure produced by the nitrogen atom was resolved for both transitions. The derived rotational constants from the laboratory data are B sub(0) = 5481.4333(6) MHz, D sub(0) = 2.90(8) KHz, and eQq(N) = -2.200(2) MHz. The predicted frequencies for the rotational transitions of HMgNC in the millimeter domain have an accuracy of 0.2-0.7 MHz. Four rotational lines of this species, J = 8-7, J = 10-9, J = 12-11, and J = 13-12, have been detected toward IRC+10216. The differences between observed and calculated frequencies are <0.5 MHz. The rotational constants derived from space frequencies are B sub(0) = 5481.49(3) MHz and D sub(0) = 3.2(1) KHz, i.e., identical to the laboratory ones. A merged fit to the laboratory and space frequencies provides B sub(0) = 5481.4336(4) MHz and D sub(0) = 2.94(5) KHz. We have derived a column density for HMgNC of (6 + or - 2) x 10 super(11) cm super(-2). From the observed line profiles the molecules have to be produced in the layer where other metal-isocyanides have been already found in this source. The abundance ratio between MgNC and its hydrogenated variety, HMgNC, is Asymptotically = to 20.
We report the detection of the oxygen-bearing complex organic molecules propenal (C
H
CHO), vinyl alcohol (C
H
OH), methyl formate (HCOOCH
), and dimethyl ether (CH
OCH
) toward the cyanopolyyne peak ...of the starless core TMC-1. These molecules are detected through several emission lines in a deep Q-band line survey of TMC-1 carried out with the Yebes 40m telescope. These observations reveal that the cyanopolyyne peak of TMC-1, which is the prototype of cold dark cloud rich in carbon chains, contains also O-bearing complex organic molecules like HCOOCH
and CH
OCH
, which have been previously seen in a handful of cold interstellar clouds. In addition, this is the first secure detection of C
H
OH in space and the first time that C
H
CHO and C
H
OH are detected in a cold environment, adding new pieces in the puzzle of complex organic molecules in cold sources. We derive column densities of (2.2 ± 0.3) × 10
cm
, (2.5 ± 0.5) × 10
cm
, (1.1 ± 0.2) × 10
cm
, and (2.5 ± 0.7) × 10
cm
for C
H
CHO, C
H
OH, HCOOCH
, and CH
OCH
, respectively. Interestingly, C
H
OH has an abundance similar to that of its well known isomer acetaldehyde (CH
CHO), with C
H
OH/CH
CHO ~ 1 at the cyanopolyyne peak. We discuss potential formation routes to these molecules and recognize that further experimental, theoretical, and astronomical studies are needed to elucidate the true mechanism of formation of these O-bearing complex organic molecules in cold interstellar sources.
We present the detection of the three 13C isotopologs of HCCNC and HNCCC toward TMC-1 using the QUIJOTE line survey. In addition, the D species has also been detected for these two isomers of HCCCN, ...whereas the 15N isotopolog was only detected for HCCNC. Using high-$J$ lines of HCCNC and HNCCC, we were able to derive very precise rotational temperatures, column densities, and subsequently the isotopic abundance ratios. We found that 12C/13C is sim 90 for the three possible substitutions in both isomers. These results are slightly different from what has been found for the most abundant isomer HCCCN, for which abundances of 105, 95, and 66 were found for each one of the three possible positions of 13C. The H/D abundance ratio was found to be 31pm 4 for HCCNC and of 53pm 6 for HNCCC. The latter is similar to the H/D abundace ratio derived for HCCCN (sim 59). The 14N/15N isotopic abundance ratio in HCCNC is 243pm 24.
Abstract
Satellite remote sensing is becoming a widely used monitoring technique in coastal sciences. Yet, no benchmarking studies exist that compare the performance of popular satellite-derived ...shoreline mapping algorithms against standardized sets of inputs and validation data. Here we present a new benchmarking framework to evaluate the accuracy of shoreline change observations extracted from publicly available satellite imagery (Landsat and Sentinel-2). Accuracy and precision of five established shoreline mapping algorithms are evaluated at four sandy beaches with varying geologic and oceanographic conditions. Comparisons against long-term in situ beach surveys reveal that all algorithms provide horizontal accuracy on the order of 10 m at microtidal sites. However, accuracy deteriorates as the tidal range increases, to more than 20 m for a high-energy macrotidal beach (Truc Vert, France) with complex foreshore morphology. The goal of this open-source, collaborative benchmarking framework is to identify areas of improvement for present algorithms, while providing a stepping stone for testing future developments, and ensuring reproducibility of methods across various research groups and applications.
Introduction: Previous studies have shown that a calcium prerinse can increase intraoral fluoride retention from a fluoride rinse. To explore the potential of this approach to control root caries, we ...assessed intraoral fluoride bioavailability after a calcium prerinse in older adults with normal to low salivary flow rates. Methods: In a 2-period crossover trial (NCT04239872), 20 participants (65–80 y old), with low or normal salivary flow rate, rinsed for 1 min with a 0.05% NaF mouth rinse (226 ppm F, F only) or with this rinse immediately after a 1-min rinse with 150 mM calcium lactate (Ca→F). Dental biofilm and saliva samples were collected before and up to 2 h after the rinse(s). Fluoride concentrations in saliva (whole and clarified) and dental biofilm (fluid and solid phases) were blindly determined. Data were statistically analyzed by a mixed-effects model for the effect of treatment, time, and their interaction ( α = 5%). Results: The Ca→F group resulted in significantly higher fluoride concentrations in all variables analyzed, for almost all of the collection time points. The effect was greater in the biofilm solids and whole saliva (compatible with the formation of calcium fluoride deposits) and still significant ( P < 0.001) after 2 h in the biofilm fluid and clarified saliva, suggesting that fluoride stored in insoluble particles was released, increasing free fluoride. Conclusion: The use of a calcium prerinse before a fluoride rinse was able to prolong intraoral fluoride bioavailability in older adults. Knowledge Transfer Statement: A calcium prerinse increased intraoral fluoride bioavailability in older individuals. This approach could be used to improve root caries control without the need to increase the fluoride concentration in dental products.
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