Healthy reefs with more corals and fish generate predictably greater levels of noise, according to researchers working in Panama. By analysing recordings of coral reefs from the Las Perlas Archipelago in Pacific Panama ( Central America ), marine biologists working from the Smithsonian Tropical Research Institute have found that some reefs are noisier than others, and these differences in noise provide useful information about the health of the reef.

The post A noisy reef is a healthy reef appeared first on Smithsonian Insider.

Smithsonian plant physiologist Bert Drake has studied one wetland's response to climate change for more than two decades. He gives a tour of the field experiment and explains some of the findings.

The post On the Chesapeake Bay, Smithsonian plant physiologist Bert Drake has been studying one wetland’s response to climate change for more than two decades. appeared first on Smithsonian Insider.

By pulling together data from eight different studies, we now have irrefutable evidence that vines are on the rise not only in the Amazon, but throughout the American tropics.

The post Scientists race to determine why vines are taking over forests in the American tropics appeared first on Smithsonian Insider.

Can a tendency to get distracted lead to a career in science? It did for paleoecologist Conrad Labandeira. Working on his family's farm, he would find himself falling into a study of insect life in the fields. "If you go after what interests you," he says, "the rest will always fall into place."

The post Smithsonian paleoecologist Conrad Labandeira talks about how he became a scientist and why he loves his work appeared first on Smithsonian Insider.

The new copper(II) complex [CuLCl2]2, where L is a product of Schiff base condensation between methyl­amine and 2-pyridine­carbaldehyde, is built of discrete centrosymmetric dimers.

The asymmetric unit of the title compound contains two independent mol­ecules, consisting of perimidine and phenol units, which are linked through an N—H⋯O hydrogen bond. Intra­molecular O—H⋯N hydrogen bonds are observed in both independent mol­ecules.

The title compound, 1-(2,5-di­meth­oxy­phen­yl)-2,2,6,6-tetra­methyl­piperidine, was synthesized as a side-product during the synthesis of the inter­mediate, methyl 3,6-dimeth­oxy-2-(2-meth­oxy-2-oxoeth­yl)benzoate, necessary for the total synthesis of the isocoumarin 5,8-dimeth­oxy-3-methyl-1H-isochromen-1-one.

The title compound exhibits exceptionally weak inter­molecular C—H⋯π hydrogen bonding of the ethynyl groups, with the corresponding H⋯π separations [2.91 (2) and 3.12 (2) Å] exceeding normal vdW distances. This bonding compliments distal contacts of the CH (aliphatic)⋯π type [H⋯π = 3.12 (2)–3.14 (2) Å] to sustain supra­molecular layers.

The dihedral angle between the two aromatic rings of the title compound is 64.12 (14)°. The crystal structure is stabilized by a short Cl⋯H contact, C—Cl⋯π and van der Waals inter­actions.

The title complex, Cu(L)2 or [Cu(C15HF10O2)2], comprising one copper ion and two fully fluorinated ligands (L−), was crystallized with 3,4-ethyl­ene­dioxy­thio­phene (EDOT, C6H6O2S) as a guest mol­ecule to give in a di­chloro­methane solution a unique co-crystal, Cu(L)2·3C6H6O2S.

Compared with X-rays, electron diffraction faces a crucial challenge: dynamical electron scattering compromises structure solution and its effects can only be modelled in specific cases. Dynamical scattering can be reduced experimentally by decreasing crystal size but not without a penalty, as it also reduces the overall diffracted intensity. In this article it is shown that nanometre-sized crystals from organic pharmaceuticals allow positional refinement of the hydrogen atoms, even whilst ignoring the effects of dynamical scattering during refinement. To boost the very weak diffraction data, a highly sensitive hybrid pixel detector was employed. A general likelihood-based computational approach was also introduced for further reducing the adverse effects of dynamic scattering, which significantly improved model accuracy, even for protein crystal data at substantially lower resolution.

This work considers the scaling properties characterizing the hyperuniformity (or anti-hyperuniformity) of long-wavelength fluctuations in a broad class of one-dimensional substitution tilings. A simple argument is presented which predicts the exponent α governing the scaling of Fourier intensities at small wavenumbers, tilings with α > 0 being hyperuniform, and numerical computations confirm that the predictions are accurate for quasiperiodic tilings, tilings with singular continuous spectra and limit-periodic tilings. Quasiperiodic or singular continuous cases can be constructed with α arbitrarily close to any given value between −1 and 3. Limit-periodic tilings can be constructed with α between −1 and 1 or with Fourier intensities that approach zero faster than any power law.

In the title compound, C16H14Cl2FN3, the dihedral angle between the two aromatic rings is 64.12 (14)°. The crystal structure is stabilized by a short Cl...H contact, C—Cl...π and van der Waals interactions. The Hirshfeld surface analysis and two-dimensional fingerprint plots show that H...H (33.3%), Cl...H/H...Cl (22.9%) and C...H/H...C (15.5%) interactions are the most important contributors towards the crystal packing.

The title compound, C14H16, exhibits exceptionally weak intermolecular C—H...π hydrogen bonding of the ethynyl groups, with the corresponding H...π separations [2.91 (2) and 3.12 (2) Å] exceeding normal vdW distances. This bonding complements distal contacts of the CH (aliphatic)...π type [H...π = 3.12 (2)–3.14 (2) Å] to sustain supramolecular layers. Hirshfeld surface analysis of the title compound suggests a relatively limited significance of the C...H/H...C contacts to the crystal packing (24.6%) and a major contribution from H...H contacts accounting 74.9% to the entire surface.

The asymmetric unit of the title compound, C17H14N2O, contains two independent molecules each consisting of perimidine and phenol units. The tricyclic perimidine units contain naphthalene ring systems and non-planar C4N2 rings adopting envelope conformations with the C atoms of the NCN groups hinged by 44.11 (7) and 48.50 (6)° with respect to the best planes of the other five atoms. Intramolecular O—H...N hydrogen bonds may help to consolidate the molecular conformations. The two independent molecules are linked through an N—H...O hydrogen bond. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H...H (52.9%) and H...C/C...H (39.5%) interactions. Hydrogen bonding and van der Waals interactions are the dominant interactions in the crystal packing. Density functional theory (DFT) optimized structures at the B3LYP/ 6–311 G(d,p) level are compared with the experimentally determined molecular structure in the solid state. The HOMO–LUMO behaviour was elucidated to determine the energy gap.

In the title compound, C17H27NO2, the piperidine ring has a chair conformation and is positioned normal to the benzene ring. In the crystal, molecules are linked by C—H...O hydrogen bonds, forming chains propagating along the c-axis direction.

The new copper(II) complex, namely, di-μ-chlorido-bis{chlorido[methyl(pyridin-2-ylmethylidene)amine-κ2N,N']copper(II)}, [Cu2Cl4(C7H8N2)2], (I), with the ligand 2-pyridylmethyl-N-methylimine (L, a product of Schiff base condensation between methylamine and 2-pyridinecarbaldehyde) is built of discrete centrosymmetric dimers. The coordination about the CuII ion can be described as distorted square pyramidal. The base of the pyramid consists of two nitrogen atoms from the bidentate chelate L [Cu—N = 2.0241 (9), 2.0374 (8) Å] and two chlorine atoms [Cu—Cl = 2.2500 (3), 2.2835 (3) Å]. The apical position is occupied by another Cl atom with the apical bond being significantly elongated at 2.6112 (3) Å. The trans angles of the base are 155.16 (3) and 173.79 (2)°. The Cu...Cu separation in the dimer is 3.4346 (3) Å. In the crystal structure, the loosely packed dimers are arranged in stacks propagating along the a axis. The X-band polycrystalline 77 K EPR spectrum of (I) demonstrates a typical axial pattern characteristic of mononuclear CuII complexes. Compound (I) is redox active and shows a cyclic voltammetric response with E1/2 = −0.037 V versus silver–silver chloride electrode (SSCE) assignable to the reduction peak of CuII/CuI in methanol as solvent.

The crystal structure of tri­phenyl­methanol, C19H16O, has been redetermined using data collected at 295 and 153 K, and is compared to the model published by Ferguson et al. over 25 years ago [Ferguson et al. (1992). Acta Cryst. C48, 1272–1275] and that published by Serrano-González et al., using neutron and X-ray diffraction data [Serrano-González et al. (1999). J. Phys. Chem. B, 103, 6215–6223]. As predicted by these authors, the hy­droxy groups are involved in weak inter­molecular hydrogen bonds in the crystal, forming tetra­hedral tetra­­mers based on the two independent mol­ecules in the asymmetric unit, one of which is placed on the threefold symmetry axis of the Roverline{3} space group. However, the reliable determination of the hy­droxy H-atom positions is difficult to achieve, for two reasons. Firstly, a positional disorder affects the full asymmetric unit, which is split over two sets of positions, with occupancy factors of ca 0.74 and 0.26. Secondly, all hy­droxy H atoms are further disordered, either by symmetry, or through a positional disorder in the case of parts placed in general positions. We show that the correct description of the hydrogen-bonding scheme is possible only if diffraction data are collected at low temperature. The pro­chiral character of the hydrogen-bonded tetra­meric supra­molecular clusters leads to enanti­omorphic three-dimensional graphs in each tetra­mer. The crystal is thus a racemic mixture of supS and supR motifs, consistent with the centro­symmetric nature of the Roverline{3} space group.

The enanti­opure monopyrrolidine derivative (2S)-methyl (Z)-5-(2-tert-but­oxy-1-cyano-2-oxo­ethyl­idene)pyrrolidine-2-carboxyl­ate, C13H18N2O4, (1), represents a potential ligand and an attractive inter­mediate for the synthesis of chiral metal com­plexes. At the mol­ecular level, the com­pound features an intra­molecular N—H⋯O hydrogen bond; neighbouring mol­ecules inter­act via N—H⋯N contacts to form chains along [100]. Due to its elemental com­position, resonant scattering of the target com­pound is entirely insignificant for diffraction experiments with Mo Kα and small even for Cu Kα radiation. A preliminary study with the harder radiation type confirmed the chiral space group and the suitability of the single crystal chosen; as expected, the results concerning the absolute structure remained com­pletely inconclusive. A second data collection with the longer wavelength gave satisfactory quality indicators for the correct handedness of the mol­ecule, albeit with high standard uncertainties. The absolute configuration has been assessed independently: CD spectra for both enanti­omers of the target mol­ecule were calculated and the spectrum for the S-configured stereoisomer was in agreement with the experiment. The Cotton effect of (1) may be ascribed to π–π* transitions from HOMO to LUMO and from HOMO to LUMO+1. As both independent techniques agree with respect to the handedness of the target mol­ecule, the absolute structure may be assigned with a high degree of confidence.

During investigations of the formation of hydrated magnesium carbonates, a sample of the previously unknown magnesium carbonate hexa­hydrate (MgCO3·6H2O) was synthesized in an aqueous solution at 273.15 K. The crystal structure consists of edge-linked isolated pairs of Mg(CO3)(H2O)4 octa­hedra and noncoordinating water mol­ecules, and exhibits similarities to NiCO3·5.5H2O (hellyerite). The recorded X-ray diffraction pattern and the Raman spectra confirmed the formation of a new phase and its transformation to magnesium carbonate trihydrate (MgCO3·3H2O) at room temperature.

An operationally simple and time-efficient approach has been developed for the synthesis of racemic N-substituted 3-(2-aryl-2-oxoeth­yl)-3-hy­droxy­indolin-2-ones by a piperidine-catalysed aldol reaction between aryl methyl ketones and N-alkyl­isatins. These aldol products were used successfully as strategic inter­mediates for the preparation of N-substituted (E)-3-(2-hetaryl-2-oxo­ethyl­idene)indolin-2-ones by a stereoselective dehydration reaction under acidic conditions. The products have all been fully characterized by 1H and 13C NMR spectroscopy, by mass spectrometry and, for a representative selection, by crystal structure analysis. In each of (RS)-1-benzyl-3-hy­droxy-3-[2-(4-meth­oxy­phen­yl)-2-oxoeth­yl]indolin-2-one, C24H21NO4, (Ic), and (RS)-1-benzyl-3-{2-[4-(di­methyl­amino)­phen­yl]-2-oxoeth­yl}-3-hy­droxy­indolin-2-one, C25H24N2O3, (Id), inversion-related pairs of mol­ecules are linked by O—H⋯O hydrogen bonds to form R22(10) rings, which are further linked into chains of rings by a combination of C—H⋯O and C—H⋯π(arene) hydrogen bonds in (Ic) and by C—H⋯π(arene) hydrogen bonds in (Id). The mol­ecules of (RS)-1-benzyl-3-hy­droxy-3-[2-oxo-2-(pyridin-4-yl)eth­yl]indolin-2-one, C22H18N2O3, (Ie), are linked into a three-dimensional framework structure by a combination of O—H⋯N, C—H⋯O and C—H⋯π(arene) hydrogen bonds. (RS)-3-[2-(Benzo[d][1,3]dioxol-5-yl)-2-oxoeth­yl]-1-benzyl-3-hy­droxy­indolin-2-one, C24H19NO5, (If), crystallizes with Z' = 2 in the space group Poverline{1} and the mol­ecules are linked into com­plex sheets by a combination of O—H⋯O, C—H⋯O and C—H⋯π(arene) hydro­gen bonds. In each of (E)-1-benzyl-3-[2-(4-fluoro­phen­yl)-2-oxo­ethyl­idene]indolin-2-one, C23H16FNO2, (IIa), and (E)-1-benzyl-3-[2-oxo-2-(thiophen-2-yl)ethylidene]indolin-2-one, C21H15NO2S, (IIg), the mol­ecules are linked into simple chains by a single C—H⋯O hydrogen bond, while those of (E)-1-benzyl-3-[2-oxo-2-(pyridin-4-yl)ethyl­idene]indolin-2-one, C22H16N2O2, (IIe), are linked by three C—H⋯O hydrogen bonds to form sheets which are further linked into a three-dimensional structure by C—H⋯π(arene) hydrogen bonds. There are no hydrogen bonds in the structures of either (E)-1-benzyl-3-[2-(4-meth­oxy­phen­yl)-2-oxo­ethyl­idene]indolin-2-one, C24H19NO3, (IIc), or (E)-1-benzyl-5-chloro-3-[2-(4-chloro­phen­yl)-2-oxo­ethyl­idene]indolin-2-one, C23H15Cl2NO2, (IIh), but the mol­ecules of (IIh) are linked into chains of π-stacked dimers by a combination of C—Cl⋯π(arene) and aromatic π–π stacking inter­actions.

The com­pound poly[2-hy­droxy-N-methyl­ethan-1-aminium [μ3-cyanido-κ3C:C:N-di-μ-cyanido-κ4C:N-dicuprate(I)]], {(C3H10NO)[Cu2(CN)3]}n or [meoenH]Cu2(CN)3, crystallizes in the tetra­gonal space group P43. The structure consists of a three-dimensional (3D) anionic CuICN network with noncoordinated protonated N-methyl­ethano­lamine cations providing charge neutrality. Pairs of cuprophilic Cu atoms are bridged by the C atoms of μ3-cyanide ligands, which link these units into a 43 spiral along the c axis. The spirals are linked together into a 3D anionic network by the two other cyanide groups. The cationic moieties are linked into their own 43 spiral via N—H⋯O and O—H⋯O hydrogen bonds, and the cations inter­act with the 3D network via an unusual pair of N—H⋯N hydrogen bonds to one of the μ2-cyanide groups. Thermogravimetric analysis indicates an initial loss of the base cation and one cyanide as HCN at temperatures in the range 130–250 °C to form CuCN. We show how loss of a specific cyanide group from the 3D CuCN structure could form the linear CuCN structure. Further heating leaves a residue of elemental copper, isolated as the oxide.

The monoclinic crystal structure of Na2SO3(H2O)7 is characterized by an alternating stacking of (100) cationic sodium–water layers and anionic sulfite layers along [100]. The cationic layers are made up from two types of [Na(H2O)6] octa­hedra that form linear 1∞[Na(H2O)4/2(H2O)2/1] chains linked by dimeric [Na(H2O)2/2(H2O)4/1]2 units on both sides of the chains. The isolated trigonal–pyramidal sulfite anions are connected to the cationic layers through an intricate network of O—H⋯O hydrogen bonds, together with a remarkable O—H⋯S hydrogen bond, with an O⋯S donor–acceptor distance of 3.2582 (6) Å, which is about 0.05 Å shorter than the average for O—H⋯S hydrogen bonds in thio­salt hydrates and organic sulfur com­pounds of the type Y—S—Z (Y/Z = C, N, O or S). Structural relationships between monoclinic Na2SO3(H2O)7 and ortho­rhom­bic Na2CO3(H2O)7 are discussed in detail.

The positional change of nitro­gen-7 of the RNA constituent guanosine to the bridgehead position-5 leads to the base-modified nucleoside 5-aza-7-de­aza­guanosine. Contrary to guanosine, this mol­ecule cannot form Hoogsteen base pairs and the Watson–Crick proton donor site N3—H becomes a proton-acceptor site. This causes changes in nucleobase recognition in nucleic acids and has been used to construct stable `all-purine' DNA and DNA with silver-mediated base pairs. The present work reports the single-crystal X-ray structure of 7-iodo-5-aza-7-de­aza­guanosine, C10H12IN5O5 (1). The iodinated nucleoside shows an anti conformation at the glycosylic bond and an N conformation (O4'-endo) for the ribose moiety, with an anti­periplanar orientation of the 5'-hy­droxy group. Crystal packing is controlled by inter­actions between nucleobase and sugar moieties. The 7-iodo substituent forms a contact to oxygen-2' of the ribose moiety. Self-pairing of the nucleobases does not take place. A Hirshfeld surface analysis of 1 highlights the contacts of the nucleobase and sugar moiety (O—H⋯O and N—H⋯O). The concept of pK-value differences to evaluate base-pair stability was applied to purine–purine base pairing and stable base pairs were predicted for the construction of `all-purine' RNA. Furthermore, the 7-iodo substituent of 1 was functionalized with benzo­furan to detect motional constraints by fluorescence spectroscopy.

A new polymorph (form II) is reported for the 1:1 dimethyl sulfoxide solvate of 2,3,5,6-tetra­fluoro-1,4-di­iodo­benzene (TFDIB·DMSO or C6F4I2·C2H6SO). The structure is similar to that of a previously reported polymorph (form I) [Britton (2003). Acta Cryst. E59, o1332–o1333], containing layers of TFDIB mol­ecules with DMSO mol­ecules between, accepting I⋯O halogen bonds from two TFDIB mol­ecules. Re-examination of form I over the temperature range 300–120 K shows that it undergoes a phase transformation around 220 K, where the DMSO mol­ecules undergo re-orientation and become ordered. The unit cell expands by ca 0.5 Å along the c axis and contracts by ca 1.0 Å along the a axis, and the space-group symmetry is reduced from Pnma to P212121. Refinement of form I against data collected at 220 K captures the (average) structure of the crystal prior to the phase transformation, with the DMSO mol­ecules showing four distinct disorder com­ponents, corresponding to an overlay of the 297 and 120 K structures. Assessment of the inter­molecular inter­action energies using the PIXEL method indicates that the various orientations of the DMSO mol­ecules have very similar total inter­action energies with the molecules of the TFDIB framework. The phase transformation is driven by inter­actions between DMSO mol­ecules, whereby re-orientation at lower temperature yields significantly closer and more stabilizing inter­actions between neighbouring DMSO mol­ecules, which lock in an ordered arrangement along the shortened a axis.

Physical quantities in arbitrary dimensional space can be classified into 41 types using three antisymmetries within the framework of Clifford algebra.

The inversion of X-ray reflectivity to reveal the topography of a one-dimensional interface is evaluated through model calculations.

Combining sodium hydride with some solvents can be a bad idea, as a group of researchers from Corteva Agriscience and Dow Chemical remind the chemistry community in Organic Process Research & Development ,(2019, DOI: 10.1021/acs.oprd.9b00276). Reports of explosions from combining NaH with a polar aprotic solvent such as dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), and N,N-dimethylacetamide […]

The post Don’t mix sodium hydride with polar aprotic solvents appeared first on CENtral Science.

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What an animal eats is a fundamental aspect of its biology, but surprisingly, the evolution of diet had not been studied across the animal kingdom until now. Scientists at the University of Arizona report several unexpected findings from taking a deep dive into the evolutionary history of more than one million animal species and going back 800 million years, when the first animals appeared on our planet. The study revealed several surprising key insights: Many species living today that are carnivorous, meaning they eat other animals, can trace this diet back to a common ancestor more than 800 million years ago; A plant-based, or herbivorous, diet is not the evolutionary driver for new species that it was believed to be; Closely related animals tend to share the same dietary category -- plant-eating, meat-eating, or both. This finding implies that switching between dietary lifestyles is not something that happens easily and often over the course of evolution.

Image credit: Daniel Stolte/UANews

Source: Streetwise Reports   05/07/2020

Oil and gas technology services and solutions company ION Geophysical Corp. (IO:NYSE) yesterday afternoon announced financial results for Q1/20 ending March 31, 2020.

The firm reported total net revenues of $56.4 million in Q1/20, which represented a 53% increase over $37.0 million in Q1/19. The company advised that the increase was due primarily to an increase in 2D multi-client data library sales.

For Q1/20, the firm additionally reported operating income of $6.3 million, compared to an operating loss of $15.9 million in Q1/19. The company further indicated that in Q1/20, it posted a net loss of $2.3 million, or ($0.16) per share, compared to a net loss of $21.4 million, or ($1.52) per share in Q1/19.

The company's President and CEO Chris Usher commented, "We achieved the best first quarter performance in six years despite challenges from both coronavirus and oil price volatility...Our strong revenues of $56 million generated positive operating income and $23 million in Adjusted EBITDA, and, as a result, we expect our liquidity position to improve as revenues are collected in the second quarter. Our first quarter results reflect the value of our offshore data library and validate the combined effectiveness of our strategic refocus and over $20 million cost reductions. Our team creatively closed a number of large multi-client contracts, some of which were delayed from the fourth quarter, even after E&P market dynamics changed. I remain confident in ION's value proposition to cost-effectively support customers' data-driven decision-making in this lower-for-longer exploration and production environment."

The company indicated that it has maintained a strong liquidity position in the face of energy market turmoil and the COVID-19 situation. The firm stated that as of March 31, 2020, it had total liquidity of $53.8 million, which consisted of $42.7 million in cash and $11.1 million remaining available balance under its $50.0 million revolving credit line.

ION Geophysical Corp. is a technology-focused company headquartered in Houston, Tex. that provides geophysical technology, services and solutions to the global oil and gas industry. Its products and technical services are designed to help oil and gas exploration and production companies obtain images of the earth's subsurface.

ION Geophysical started off the day with a market capitalization of around $25.1 million and an enterprise value of $115.7 million with approximately 15.03 million shares outstanding and a short interest of about 6.40%. IO shares opened more than 100% higher today at $3.37 (+$1.70, +101.80%) over yesterday's $1.67 closing price. The stock has traded between $2.84 to $4.36 per share today and is currently trading at $2.88 (+$1.21, +72.46%).

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( Companies Mentioned: IO:NYSE, )

While the U.S. Environmental Protection Agencys guideline for protecting the public from a toxic form of mercury is justifiable based on the latest scientific evidence, some children of women who consume large amounts of fish and seafood during pregnancy may be at special risk of neurological problems.

No single approach -- technical, legal, economic, or educational -- will be sufficient to protect children from online pornography.

To meet the bodys daily energy and nutritional needs while minimizing risk for chronic disease, adults should get 45 percent to 65 percent of their calories from carbohydrates, 20 percent to 35 percent from fat, and 10 percent to 35 percent from protein.

A new report from the Institute of Medicine finds suggestive but limited evidence that exposure to Agent Orange and other herbicides used during the Vietnam War is associated with an increased chance of developing high blood pressure in some veterans.