K2-18b Does Not Meet the Standards of Evidence for Life

The exchange of dimethyl sulfide (DMS), carbon disulfide (CS2), and dimethyl disulfide (DMDS) between soil and the atmosphere was investigated in three subtropical forests in south China, namely, a monsoon evergreen broadleaf forest (BF) in climax successional stage, a pine and broadleaf mixed forest (MF) in midsuccessional stage, and a pine forest (PF) in primary successional stage. The forest soils acted as sources for DMS with average flux in BF (1.27 ± 1.40 pmol m−2 s−1) significantly higher than those in MF (0.46 ± 0.30 pmol m−2 s−1) or in PF (0.47 ± 0.36 pmol m−2 s−1). Litter‐removed plots showed 55%, 21%, and 53% lower DMS emission fluxes compared to litter‐remained plots in BF, MF, and PF, respectively, suggesting the litter layer made evident contribution to DMS emission. DMS fluxes were significantly higher in rain seasons than in dry seasons. Dependence of DMS fluxes on soil temperature varied in the three forests, and significant correlations between DMS fluxes and soil temperature were only observed in BF and MF. No significant correlation was found between soil water content and DMS fluxes. However, DMS fluxes were found to be significantly correlated with soil temperature and water content together in polynomial forms with an order of 2. DMS fluxes were also exponentially correlated with CO2 fluxes. CS2 and DMDS fluxes showed no consistent direction. CS2 fluxes varied between −8.51 and 4.72 pmol m−2 s−1 and DMDS fluxes between −0.25 and 2.00 pmol m−2 s−1, respectively. No clear patterns were found for the influence of litter layer on the CS2 or DMDS fluxes.

We propose a new pixel binning scheme for color image sensors. We minimized distortion caused by binning by requiring that the superpixels lie on a square sampling lattice. The proposed binning schemes achieve the equivalent of 4.42 times signal strength improvement with the image resolution loss of 5 times, higher in noise performance and in resolution than the existing binning schemes. As a result, the proposed binning has considerably less artifacts and better noise performance compared with the existing binning schemes. In addition, we provide an extension to the proposed binning scheme for performing single-shot high dynamic range image acquisition.

AME Aquatic Microbial Ecology Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials AME 18:197-205 (1999) - doi:10.3354/ame018197 Microbial consumption and production of dimethyl sulfide (DMS) in the Labrador Sea Gordon V. Wolfe*, Maurice Levasseur**, Guy Cantin, Sonia Michaud Institut Maurice-Lamontagne, Ministère des Pêches et des Océans, CP 1000, Mont-Joli, Québec G5L 3A1, Canada *Present address: College of Oceanic and Atmospheric Sciences, Oregon State University, 104 Ocean. Admin. Bldg., Corvallis, Oregon 97331-5503, USA. **Addressee for correspondence. E-mail: levasseurm@dfo-mpo.gc.ca ABSTRACT: We examined microbial production and consumption of dimethyl sulfide (DMS) in Labrador Sea surface waters ranging in temperature from -0.1 to 6.9°C. 200 nM dimethyl disulfide (DMDS) was used to inhibit DMS consumption. We also studied DMS consumption kinetics by additions of 5 to 50 nM DMS, DMS production from added dimethylsulfoniopropionate (DMSP), and DMS production and consumption during zooplankton grazing. During the cruise, DMS concentrations were low, ranging from 1 to 7 nM throughout the study area, which included a bloom of the colonial haptophyte alga Phaeocystis pouchetii. DMDS additions often revealed rapid DMS production and consumption (up to 5 nM d-1) and very rapid turnover (<1 to 3 d), similar to rates found in coastal waters at much higher temperatures. There was no clear effect of temperature on DMS consumption; rather, DMS consumption appeared to be tightly coupled with production. Turnover was most rapid at low DMS concentrations, and DMS consumption was stimulated by additions of DMS, or by increased DMS production from additions of dissolved DMSP. DMDS additions to zooplankton grazing incubations revealed rapid gross DMS production and consumption which were nearly balanced, resulting in net steady-state DMS patterns. DMDS did not affect production or grazing of algal pigments or DMSP. DMS consumption saturated at 18 to 32 nM [DMS] and saturation kinetics were similar within the photic zone, but consumption was near-zero at greater depths. We suggest that DMS consumption likely saturates more easily than microbial DMS production from DMSP, and this, combined with temperature limitation on the growth of prokaryotic DMS consumers, may lead to the periodic buildup of high DMS concentrations previously observed in polar and subpolar waters. KEY WORDS: Dimethyl sulfide · Dimethylsulfoniopropionate · DMSP · DMS · Inhibitor technique · Consumption kinetics · Zooplankton grazing Full text in pdf format PreviousExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in AME Vol. 18, No. 2. Publication date: August 09, 1999 Print ISSN: 0948-3055; Online ISSN: 1616-1564 Copyright © 1999 Inter-Research.

This study evaluated the applicability of visible-light-driven N- and S-doped titanium dioxide(<TEX>$TiO_2$</TEX>) for the control of low-level dimethyl sulfide(DMS) and dimethyl disulfide(DMDS). In addition, a photocatalytic unit(PU)-adsorption hybrid was evaluated in order to examine the removal of DMS and DMDS which exited the PU and a gaseous photocatalytic byproduct(<TEX>$SO_2$</TEX>) which was generated during the photocatalytic processes. Fourier-Tranform-Infrared(FTIR) spectrum exhibited different surface characteristics among the three-types of catalysts. For the N- and S-doped <TEX>$TiO_2$</TEX> powders, a shift of the absorbance spectrum towards the visible-light region was observed. The absorption edge for both the N- and S-doped <TEX>$TiO_2$</TEX> was shifted to <TEX>$\lambda$</TEX> 720 nm. The N-doped <TEX>$TiO_2$</TEX> was superior to the S-doped <TEX>$TiO_2$</TEX> in regards to DMS degradation. Under low input concentration(IC) conditions(0.039 and 0.027 ppm for DMS and DMDS, respectively), the N-doped <TEX>$TiO_2$</TEX> revealed a high DMS removal efficiency(above 95%), but a gradual decreasing removal efficiency under high IC conditions(7.8 and 5.4 ppm for DMS and DMDS, respectively). Although the hybrid system exhibited a superior characteristic to PU alone regarding the removal efficiencies of both DMS and DMDS, this capability decreased during the course of a photocatalytic process under the high IC conditions. The present study identified the generation of sulfate ion on the catalyst surface and sulfur dioxide(maximum concentrations of 0.0019 and 0.0074 ppm for the photocatalytic processes of DMS and DMDS, respectively) in effluent gas of PU. However, this generation of <TEX>$TiO_2$</TEX> would be an insignificant addition to indoor air quality levels.

Odor emission is one of the most common problems associated with dead animals composting. Biofiltration treatment for eliminating exhaust odors formed during dead pigs and manure composting has been studied. The composting and biofiltration process consisted of two series of tests. Composting experimental trials lasted 6 weeks, and composting was performed using six pilot-scale reactor vessels. A total of 37 kinds of volatile organic compounds (VOCs) present in the air were identified, and temporal variations were determined during the 42 days of composting. Dimethyl sulfide (DMS), dimethyl disulfide (DMDS), dimethyl trisulfide (DMTS), and trimethylamine (TMA) were identified as the main odors VOCs component according to odor active values (OAVs). Nine biofilter vessels containing mature compost were used in studying the effect of different (30, 60, and 100 s) empty bed retention times (EBRT) on the simultaneous removal efficiencies (REs) of NH3, DMS, DMDS, DMTS, and TMA. Results indicated that the inlet concentration of NH3 applied was 12–447 mg m−3, and the average removal efficiencies were 85.4%, 88.7%, and 89.0% for EBRTs of 30, 60, and 100 s, respectively. The average REs of DMS, DMDS, DMTS, and TMA were 79.2%–95.4%, 81.9%–94.0%, 76.7%–99.1%, and 92.9%–100%, respectively, and their maximum elimination capacity (ECs) were 220, 1301, 296, and 603 mg m−3 h−1, respectively. The optimal EBRT for the stimulation removal of NH3, DMS, DMDS, DMTS, and TMA was 60 s. Implications: Dimethyl sulfide (DMS), dimethyl disulfide (DMDS), dimethyl trisulfide (DMTS), and trimethylamine (TMA) were identified as the main odors VOCs component during dead pigs and manure composting. Biofilter with mature as media can be used to stimulation remove NH3, DMS, DMDS, DMTS, and TMA, the optimal empty bed retention times EBRT was 60 s.

Context. Recent JWST observations of the temperate sub-Neptune K2-18 b have been interpreted as suggestive of a liquid water ocean with possible biological activity. Signatures of dimethyl sulfide (DMS) and dimethyl disulfide (DMDS) have been observed in the near-infrared (using the NIRISS and NIRSpec instruments) and mid-infrared (using MIRI). However, the statistical significance of the atmospheric imprints of these potential biomarkers has yet to be quantified from a joint analysis of the entire planet spectrum. Aims. We aim to test the robustness of the proposed DMS and DMDS detections by simultaneously modeling the NIRISS and NIRSpec observations jointly with the MIRI spectrum for the first time, considering different data reductions and modeling choices. Methods. We used three well-tested pipelines to re-reduce the JWST observations and two retrieval codes to analyze the resulting transmission spectra as well as previously published data. Results. The first joint analysis of the panchromatic (0.6–12 µm) spectrum of K2-18 b finds insufficient evidence for the presence of DMS and/or DMDS in the atmosphere of the planet. We find that any marginal preferences are the result of limiting the number of molecules considered in the model and oversensitivity to small changes between data reductions. Conclusions. Our results confirm that there is no statistical significance for DMS or DMDS in K2-18 b’s atmosphere. While previous works have demonstrated this on MIRI or NIRISS/NIRSpec observations alone, our analysis of the full, panchromatic transmission spectrum does not support claims of potential biomarkers. Using the best-fitting model including DMS and/or DMDS on the published data, we estimate that ∼25 more MIRI transits would be needed for a 3σ rejection of a flat line relative to DMS and/or DMDS features in the planet’s mid-infrared transmission spectrum.

Soil-incorporated plant materials have been associated with reduction in soilborne pathogens and diseases. Mechanisms of the biocidal actions are complex and not well understood. A glasshouse experiment, a non replicated field demonstration, and a field experiment were conducted to determine volatile compounds after incorporation of various plant species and their effect on pest control. Cabbage (Brassica oleracea), canola (Brassica rapa), kale (Brassica oleracea var. acephala), lettuce (Lactuca sativa var. valmaine), two mustard varieties -Caliente (Brassica juncea) and Green wave (Brassica juncea), two radish varieties - Oil seed (Raphanus sativus var. oleiformis) and Cherriette (Raphanus sativus), common rye (Secale cereale), and sorghum Sudan grass (Sorghum bicolor var. sudanese) were used in the glasshouse experiment. Caliente 199 mustard (Brassica hirta) was planted in the field demonstration and white mustard (Sinapis alba) was used in the field experiment. Fresh plant materials were chopped manually in the glasshouse experiment and mechanically in the field studies at the flowering stage before incorporation in natural field soils. In the glasshouse experiment, the equivalent biomass dry weight ranged from a minimum of 573 g m−2 for L. sativa var. valmaine to a maximum of 1851 g m−2 for S. bicolor var. sudanese. The average biomass was 792 g m−2 for B. hirta and 804 g m−2 for S. alba in the two field studies, respectively. The glasshouse experiment used a loamy sand field soil inoculated with a natural fine sandy loam soil that was known to contain high populations of Verticillium dahliae. Soils at both field sites belonged to the sandy loam series, and efforts were made to maintain sufficient soil moisture for plant growth. Although the interest was to determine all volatile compounds in general, only methyl sulfide and dimethyl disulfide were identified and subsequently quantified. Depending on plant species and time of sampling (one to seven days after soil incorporation), 2.7 to 346.4 μg g −1 plant dry weight for methyl sulfide and 0 to 283.2 μg g −1 plant dry weight for dimethyl disulfide were found in the glasshouse experiment. In general, high concentrations of dimethyl disulfide and methyl sulfide appeared to have reduced V. dahliae colony counts in bioassay potato stem saps in the glasshouse experiment. However, the correlation was weak (R2 = 0.31), but a relatively stronger correlation was obtained (R2 = 0.58) when excluding B. oleracea and B. rapa from the regression. Dimethyl disulfide and methyl sulfide were nearly non-detectable in the field demonstration, consequently no disease assessment was made. In the field experiment, a production of 5.2 μg g −1 plant dry weight for methyl sulfide and 1.2 μg g −1 dry weight for dimethyl disulfide was found two days after soil incorporation of S. alba. Compared to the untreated control, total Fusarium oxysporum counts in field soil were significantly lower 39 days after S. alba incorporation. However, no significant impact was found on total Pythium counts. Soil population of citrus nematode (Tylenchulus semipenetrans) in the S. alba plots was significantly reduced to similar levels found in the untreated control 112 days after S. alba incorporation. Compared to the untreated control, soil density of non plant parasitic freeliving nematodes was higher 39 days after S. alba incorporation. The study demonstrated quantifiable production of methyl sulfide and dimethyl disulfide gases from a variety of plant species in glasshouse and natural field environments. Some beneficial effects against V. dahliae, F. oxysporum, and T. semipenetrans were observed. Additional studies are needed to further elucidate these complex chemical and biological interactions.

In this study, two types of ozone generating experimental instrument were installed in commercial livestock manure fertilization facility, which can treat hundred tons of pig manure in a day. Gas samples to be treated were collected from the upper part of the liquid fertilization system and composting system of the commercial livestock manure fertilization facility. The gas sample was flowed to oxidation reactor through pipe line by suction blower, therefore, contacted with ozone. Ammonia and sulfur compounds of gas samples collected from the inlet and outlet point of the experimental instrument were analyzed. The oxidation effect by the contact with ozone was higher in sulfur compounds than ammonia. Ammonia content was reduced about 10% by ozone contact. Sulfur compounds, on the other hand, reduced significantly while treated with ozone. In case of gas sample collected from liquid fertilization system, the concentrations of hydrogen sulfide (), methyl mercaptan (MM), dimethyl sulfide (DMS), and dimethyl disulfide (DMDS) of inlet gas were 50.091, 4.9089, 27.8109 and 0.4683 ppvs, respectively. After oxidized by ozone, the concentrations of sulfur compounds were 1.2317, 0.3839, 14.7279 and 0.3145 ppvs, respectively. Another sample collected from aerobic composting system was oxidized in the same conditions. The concentrations of , MM, DMS and DMDS of the sample collected from inlet point of the reactor were 40.6682, 1.3675, 24.2458 and 0.8289 ppvs, respectively. After oxidized, the concentrations of , MM, DMS, and DMDS were reduced to 3.013, ND, 8.8998 and 0.3651 ppvs, respectively. By application of another type of ozone, the concentrations of , MM, DMS and DMDS of inlet gas were reduced from 43.397, 1.4559, 3.6021 and 0.4061 to ND, ND, ND, and 0.21ppvs, respectively.

Optimization and sensitive detection of sulfur compounds emitted from plants using proton transfer reaction mass spectrometry

Smaller pixel sizes of x-ray photon counting detectors (PCDs) benefit count rate capabilities but increase cross-talk and "double-counting" between neighboring PCD pixels. When an x-ray photon produces multiple (n) counts at neighboring (sub-)pixels and they are added during post-acquisition N×N binning process, the variance of the final PCD output-pixel will be larger than its mean. In the meantime, anti-scatter grids are placed at the pixel boundaries in most of x-ray CT systems and will decrease cross-talk between sub-pixels because the grids mask sub-pixels underneath them, block the primary x-rays, and increase the separation distance between active sub-pixels. The aim of this paper was, first, to study the PCD statistics with various N×N binning schemes and three different masking methods in the presence of cross-talks, and second, to assess one of the most fundamental performances of x-ray CT: soft tissue contrast visibility. We used a PCD cross-talk model (Photon counting toolkit, PcTK) and produced cross-talk data between 3×3 neighboring sub-pixels and calculated the mean, variance, and covariance of output-pixels with each of N×N binning scheme [4×4 binning, 2×2 binning, and 1×1 binning (i.e., no binning)] and three different sub-pixel masking methods (no mask, 1-D mask, and 2-D mask). We then set up simulation to evaluate the soft tissue contrast visibility. X-rays of 120 kVp were attenuated by 10-40cm-thick water, with the right side of PCDs having 0.5cm thicker water than the left side. A pair of output-pixels across the left-right boundary were used to assess the sensitivity index (SI or d'), which typically ranges 0-1 and is a generalized signal-to-noise ratio and a statistics used in signal detection theory. Binning a larger number of sub-pixels resulted in larger mean counts and larger variance-to-mean ratio when the lower threshold of the energy window was lower than the half of the incident energy. Mean counts are in the order of no mask (the largest), 1-D mask, and 2-D mask but the difference in variance-to-mean ratio was small. For a given sub-pixel size and masking method, binning more sub-pixels degraded the normalized SI values but the difference between 4×4 binning and 1×1 binning was typically less than 0.06. 1-D mask provided better normalized SI values than no mask and 2-D mask for side-by-side case and the improvements were larger with fewer binnings, although the difference was less than 0.10. 2-D mask was the best for embedded case. The normalized SI values of combined binning, sub-pixel size, and masking were in the order of 1×1 (900μm)2 binning, 2×2 (450μm)2 binning, and 4×4 (225μm)2 binning for a given masking method but the difference between each of them were typically 0.02-0.05. We have evaluated the effect of double-counting between PCD sub-pixels with various binning and masking methods. SI values were better with fewer number of binning and larger sub-pixels. The difference among various binning and masking methods, however, was typically less than 0.06, which might result in a dose penalty of 13% if the CT system were linear.

Measurements of the strong-phase difference between D0 and D¯0→π+π−π+π− are performed in bins of phase space. The study exploits a sample of quantum-correlated DD¯ mesons collected by the BESIII experiment in e+e− collisions at a center-of-mass energy of 3.773 GeV, corresponding to an integrated luminosity of 2.93 fb−1. Here, D denotes a neutral charm meson in a superposition of flavor eigenstates. The reported results are valuable for measurements of the CP-violating phase γ (also denoted ϕ3) in B±→DK±, D→π+π−π+π− decays, and the binning schemes are designed to provide good statistical sensitivity to this parameter. The expected uncertainty on γ arising from the precision of the strong-phase measurements, when applied to very large samples of B-meson decays, is around 1.5° or 2°, depending on the binning scheme. The binned strong-phase parameters are combined to give a value of F+4π=0.746±0.010±0.004 for the CP-even fraction of D0→π+π−π+π− decays, which is around 30% more precise than the previous best measurement of this quantity. Published by the American Physical Society 2024

In this paper, the meaning of duality in terms of the coding operations and the corresponding performance measures are examined. In this paper, operational duality to the channel and source coding problems with side information are extended. A class of deterministic maximal binning schemes is constructed. Each bin corresponds to a maximal channel code and the collection of the codewords in all the bins forms a maximal channel code. The construction of the binning scheme from the individual channel codes is greedy and provides an alternative proof of the coding theorem for the two side information problems.

Although redshift-space distortions only affect inferred distances and not angles, they still distort the projected angular clustering of galaxy samples selected using redshift dependent quantities. From an Eulerian view-point, this effect is caused by the apparent movement of galaxies into or out of the sample. From a Lagrangian view-point, we find that projecting the redshift-space overdensity field over a finite radial distance does not remove all the anisotropic distortions. We investigate this effect, showing that it strongly boosts the amplitude of clustering for narrow samples and can also reduce the significance of baryonic features in the correlation function. We argue that the effect can be mitigated by binning in apparent galaxy pair-centre rather than galaxy position, and applying an upper limit to the radial galaxy separation. We demonstrate this approach, contrasting against standard top-hat binning in galaxy distance, using sub-samples taken from the Hubble Volume simulations. Using a simple model for the radial distribution expected for galaxies from a survey such as the Dark Energy Survey (DES), we show that this binning scheme will simplify analyses that will measure baryon acoustic oscillations within such galaxy samples. Comparing results from different binning schemes has the potential to provide measurements of the amplitude of the redshift-space distortions. Our analysis is relevant for other photometric redshift surveys, including those made by the Panoramic Survey Telescope & Rapid Response System (Pan-Starrs) and the Large Synoptic Survey Telescope (LSST).

The liquid structure of some food aromas: Joint X-ray diffraction, all-atom molecular dynamics and reverse Monte Carlo investigations of dimethyl sulfide, dimethyl disulfide and dimethyl trisulfide

The isolation of a number of strains of bacteria able to grow on dimethyl disulphide and dimethyl sulphide as sole source of energy is described. The isolates came from diverse habitats, including soil, peat, marine mud and a freshwater pond. The isolates were morphologically and physiologically best described as thiobacilli, capable of growth as Calvin cycle autotrophs on inorganic sulphur compounds, methylated sulphides or thiocyanate. They could not grow heterotrophically or methylotrophically. One isolate (E6) was examined in detail. Substrate oxidation kinetics indicated that methanethiol, sulphide, formaldehyde and formate, but not dimethyl sulphide, could be implicated as intermediates in dimethyl disulphide metabolism. Apparent K s values for the oxidation of dimethyl disulphide and methanethiol were 2.5 and 3·2 μm respectively. Growth yields in chemostat culture on dimethyl disulphide with and without thiosulphate indicated that energy conservation was probably coupled to the oxidation of formaldehyde and sulphide (derived from dimethyl disulphide via methanethiol) to CO2 and sulphate. Maximum growth yield (Y max) on dimethyl disulphide was 17 g cell-carbon per mol of dimethyl disulphide. At one dilution rate (0·078 h−1), the biomass of a culture limited by dimethyl disulphide increased when thiosulphate was also supplied, indicating a thiosulphate-dependent yield of 2·45 g cell-carbon mol−1. This is the first demonstration of the isolation of organisms into pure culture that are capable of growth on dimethyl disulphide as sole energy substrate, and of degrading it completely to CO2 and sulphate.