Identification of lower-order inositol phosphates (IP₅ and IP₄) in soil extracts as determined by hypobromite oxidation and solution ³¹P NMR spectroscopy

Inositol phosphates (IPs) are a major pool of identifiable organic phosphorus (P) in soil. However, insight into their distribution and cycling in soil remains limited, particularly of lower-order IP (IP5 and IP4). This is because the quantification of lower-order IP typically requires a series of chemical extractions, including hypobromite oxidation to isolate IP, followed by chromatographic separation. Here, for the first time, we identify the chemical nature of organic P in four soil extracts following hypobromite oxidation using solution 31P NMR spectroscopy and transverse relaxation (T2) experiments. Soil samples analysed include A horizons from a Ferralsol (Colombia), a Cambisol and a Gleysol from Switzerland, and a Cambisol from Germany. Solution 31P nuclear magnetic resonance (NMR) spectra of the phosphomonoester region in soil extracts following hypobromite oxidation revealed an increase in the number of sharp signals (up to 70) and an on average 2-fold decrease in the concentration of the broad signal compared to the untreated soil extracts. We identified the presence of four stereoisomers of IP6, four stereoisomers of IP5, and scyllo-IP4. We also identified for the first time two isomers of myo-IP5 in soil extracts: myo-(1,2,4,5,6)-IP5 and myo-(1,3,4,5,6)-IP5. Concentrations of total IP ranged from 1.4 to 159.3 mg P per kg soil across all soils, of which between 9 % and 50 % were comprised of lower-order IP. Furthermore, we found that the T2 times, which are considered to be inversely related to the tumbling of a molecule in solution and hence its molecular size, were significantly shorter for the underlying broad signal compared to for the sharp signals (IP6) in soil extracts following hypobromite oxidation. In summary, we demonstrate the presence of a plethora of organic P compounds in soil extracts, largely attributed to IPs of various orders, and provide new insight into the chemical stability of complex forms of organic P associated with soil organic matter.

Structure solution of incommensurately modulated La6MnSb15

La6MnSb15 is synthesized from the constituent elements in quartz ampoules at 973 K. Crucial for the quality of the obtained single-crystals was a slow cooling rate of 2 K h−1. The crystal structure of La6MnSb15 was investigated via single-crystal X-ray diffraction experiments, leading to the observation of superstructure reflections as described in the literature. Two crystals, with refined compositions of La6MnSb15 (1) and La6MnSb14.66(1) (2) were obtained from different batches, yet both showed an orthorhombic body centered unit cell as well as additional reflections at q1 = (0,0,0.258(1)) for crystal (1) and q1 = (0,0,0.244(1)) for crystal (2). The structure could be solved and refined in superspace group Immm(00γ)000 (71.1.12.1), leading to a concise structural model. Due to γ not being exactly 1/4, an incommensurate modulation is present in the presented compounds. In order to describe the structural influence of the modulation in 3D, different approximants were chosen and the differences compared. Additionally, the temperature dependence of the electrical resistivity was investigated, indicating a metallic behavior of the title compound. This result is in line with the retro-theoretical investigation in the literature that counts excess electrons when using the Zintl–Klemm–Busmann concept. 121Sb Mößbauer-spectroscopic investigations at 78 K show a broad signal with an average isomeric shift of δ ∼ −10 mm s−1, in line with a negatively charged Sb species. The massive line broadening can be explained by the large number of crystallographic antimony sites in the basic structure and the approximant.

Quantitative measures of myo-IP6 in soil using solution 31P NMR spectroscopy and spectral deconvolution fitting including a broad signal

Inositol phosphates, particularly myo-inositol hexakisphosphate (myo-IP6), are an important pool of soil organic phosphorus (P) in terrestrial ecosystems.

Identification of lower-order inositol phosphates (IP₅ and IP₄) in soil extracts as determined by hypobromite oxidation and solution ³¹P NMR spectroscopy

Inositol phosphates (IP) are a major pool of identifiable organic phosphorus (P) in soil. However, insight on their distribution and cycling in soil remains limited, particularly of lower-order IP (IP5 and IP4). This is because their quantification typically requires a series of chemical extractions, including hypobromite oxidation to isolate IP, followed by chromatographic separation. Here, for the first time, we identify the chemical nature of organic P in four soil extracts following hypobromite oxidation using solution 31P NMR spectroscopy and transverse relaxation (T2) experiments. Soil samples analysed include the A horizon of a Ferralsol from Colombia, of a Cambisol from Switzerland, of a Gleysol from Switzerland and of a Cambisol from Germany. Solution 31P NMR spectra of the phosphomonoester region on soil extracts following hypobromite oxidation revealed an increase in the number of sharp signals (up to 70), and an on average 2-fold decrease in the concentration of the broad signal compared to the untreated soil extracts. We identified the presence of four stereoisomers of IP6, four stereoisomers of IP5, and scyllo-IP4 (using solution 31P NMR spectroscopy). We also identified for the first time two isomers of myo-IP5 in soil extracts: myo-(1,2,4,5,6)-IP5 and myo-(1,3,4,5,6)-IP5. Concentrations of total IP ranged from 1.4 to 159.3 mg P/kgsoil across all soils, of which between 9 % and 50 % were comprised of lower-order IP. Furthermore, we found that the T2 times, which are considered to be inversely related to the tumbling of a molecule in solution and hence its molecular size, were significantly shorter for the underlying broad signal compared to the sharp signals (IP6) in soil extracts following hypobromite oxidation. In summary, we demonstrate the presence of a plethora of organic P compounds in soil extracts, largely attributed to IP of various order, and provide new insight on the chemical stability of complex forms of organic P associated with soil organic matter.

Drosophila have distinct activity-gated pathways that mediate attraction and aversion to CO2

Carbon dioxide is a volatile and broad signal of many organic processes, and serves as a convenient cue for insects in search of blood hosts1–6, flowers7, decaying matter8–11, communal nests12, fruit13, and wildfires14. Curiously, although Drosophila melanogaster feed on yeast that produce CO2 and ethanol during fermentation, laboratory experiments suggest that flies actively avoid CO215–25. Here, we resolve this paradox by showing that both flying and walking fruit flies do actually find CO2 attractive, but only when they are in an active state associated with foraging. Aversion at low activity levels may be an adaptation to avoid CO2-seeking-parasites, or succumbing to respiratory acidosis in the presence of high concentrations of CO2 that are occasionally found in nature26,27. In contrast to CO2, flies are attracted to ethanol in all behavioral states, and invest twice as much time searching near ethanol compared to CO2. These behavioral differences reflect the fact that whereas CO2 is a generated by many natural processes, ethanol is a unique signature of yeast fermentation. Using genetic tools, we determined that the evolutionarily ancient ionotropic co-receptor IR25a is required for both CO2 and ethanol attraction, and that the receptors previously identified for CO2 avoidance are not involved. Our study lays the foundation for future research to determine the neural circuits underlying both state- and odorant-dependent decision making in Drosophila.

Power1D: a Python toolbox for numerical power estimates in experiments involving one-dimensional continua

The unit of experimental measurement in a variety of scientific applications is the one-dimensional (1D) continuum: a dependent variable whose value is measured repeatedly, often at regular intervals, in time or space. A variety of software packages exist for computing continuum-level descriptive statistics and also for conducting continuum-level hypothesis testing, but very few offer power computing capabilities, where ‘power’ is the probability that an experiment will detect a true continuum signal given experimental noise. Moreover, no software package yet exists for arbitrary continuum-level signal/noise modeling. This paper describes a package called power1d which implements (a) two analytical 1D power solutions based on random field theory (RFT) and (b) a high-level framework for computational power analysis using arbitrary continuum-level signal/noise modeling. First power1d’s two RFT-based analytical solutions are numerically validated using its random continuum generators. Second arbitrary signal/noise modeling is demonstrated to show how power1d can be used for flexible modeling well beyond the assumptions of RFT-based analytical solutions. Its computational demands are non-excessive, requiring on the order of only 30 s to execute on standard desktop computers, but with approximate solutions available much more rapidly. Its broad signal/noise modeling capabilities along with relatively rapid computations imply that power1d may be a useful tool for guiding experimentation involving multiple measurements of similar 1D continua, and in particular to ensure that an adequate number of measurements is made to detect assumed continuum signals.

Synthesis and Characterisation of New Symmetrical Binucleating Ligands and Their Binuclear Copper(II) Complexes

New symmetrical binucleating ligands N,N-bis[2-hydroxy-5-methyl-3-(4-methyl-piperazinomethyl)benzyl]-alkylamines L1 and L2 and their copper(II) complexes [Cu2L(X)2]·2H2O, where X = CH3COO−, C6H5COO−, Cl−, and ClO4-, were prepared and characterised. All the complexes undergo quasi-reversible reduction at negative potential (E = −0.48 to −1.02 V). The acetate and benzoate complexes undergo a two-step single electron transfer at –0.48 to –0.60 V and −0.9 to −1.02 V. The chloro and perchlorate complexes undergo a single step two-electron transfer at −0.55 to −0.75 V. Variable temperature magnetic studies show the presence of weak exchange interaction for acetate (−2 J around 25 to 40 cm−1) and benzoate (−2 J around 45 to 55 cm−1) bridged complexes and no exchange interaction is found for chloro and perchlorate complexes. ESR spectra of chloro and perchlorate complexes are like mononuclear copper(II) complexes with hyperfine splitting (A = 165 ± 5, g∥ = 2.17–2.23, and g⊥ = 2.05–2.10). The ESR spectra of acetate and benzoate complexes are like binuclear copper(II) complexes with broad signal (g = 2.2).

Joint Pain Undergoes a Transition in Accordance with Signal Changes of Bones Detected by MRI in Hip Osteoarthritis

Objectives: In this study, we aimed to investigate whether joint pain is derived from cartilage or bone alterations. Methods: We reviewed 23 hip joints of 21 patients with primary hip osteoarthritis (OA), which were classified into Kellgren–Laurence (KL) grading I to IV. Plain radiographs and magnetic resonance imaging (MRI) were obtained from all of the 23 joints. Two of the 21 patients had bilateral hip OA. Pain was assessed based on the pain scale of Denis. A Welch t test was performed for age, height, weight, body mass index, bone mineral density, and a Mann–Whitney U test was performed for KL grading. Results: Four of 8 hip joints with pain and OA showed broad signal changes detected by MRI. Fourteen hip joints without pain, but with OA did not show broad signal changes by MRI. Collectively, MRI analyses showed that broad signal changes in OA cases without joint pain or with a slight degree of joint pain were not observed, while broad signal changes were observed in OA cases with deteriorated joint pain. Conclusion: Our findings suggest that hip joint pain might be associated with bone signal alterations in the hips of OA patients.

Synthesis and Characterization of Heteronuclear Copper(II)-Lanthanide(III) Complexes of N,N′-1,3-Propylenebis(Salicylaldiminato) Where Lanthanide(III) = Gd or Eu

Three complexes, namely, [Cu(salbn)] (1), [Cu(salbn)Gd(NO3)3·H2O] (2), and [Cu(salbn)Eu(NO3)3·H2O] (3) where salbn = N,N′-1,3-propylenebis (salicylaldiminato) have been synthesized and characterized by elemental analyses, ICP-AES, IR, UV, NMR, MS, EDX, powder XRD, and EPR spectroscopies. The EDX results suggest the presence of two different metal ions in heteronuclear complexes (2) and (3). The ligand(salbn), complex (1), and complex (3) crystallize in triclinic system while complex (2) crystallizes in monoclinic system. The EPR studies suggest that [Cu(salbn)] complex is tetragonally coordinated monomeric copper(II) complex with unpaired electron in the dx2-y2 orbital and spectral features that are the characteristics of axial symmetry while complex (2) in DMF solution at liquid nitrogen temperature exhibits an anisotropic broad signal around g ~ 2.03 which may suggest a weak magnetic spin-exchange interaction between Gd(III) and Cu(II) ions. The fluorescence intensity of Eu(III) decreased markedly in the complex (3).

On the interference of Kr during carbon isotope analysis of methane using continuous-flow combustion–isotope ratio mass spectrometry

Stable carbon isotope analysis of methane (δ13C of CH4) on atmospheric samples is one key method to constrain the current and past atmospheric CH4 budget. A frequently applied measurement technique is gas chromatography (GC) isotope ratio mass spectrometry (IRMS) coupled to a combustion-preconcentration unit. This report shows that the atmospheric trace gas krypton (Kr) can severely interfere during the mass spectrometric measurement, leading to significant biases in δ13C of CH4, if krypton is not sufficiently separated during the analysis. According to our experiments, the krypton interference is likely composed of two individual effects, with the lateral tailing of the doubly charged 86Kr peak affecting the neighbouring m/z 44 and partially the m/z 45 Faraday cups. Additionally, a broad signal affecting m/z 45 and especially m/z 46 is assumed to result from scattered ions of singly charged krypton. The introduced bias in the measured isotope ratios is dependent on the chromatographic separation, the krypton-to-CH4 mixing ratio in the sample, the focusing of the mass spectrometer as well as the detector configuration and can amount to up to several per mil in δ13C. Apart from technical solutions to avoid this interference, we present correction routines to a posteriori remove the bias.