Efficient linking of two epoxides using potassium thioacetate in water and its use in polymerization

Two epoxides can be efficiently linked using potassium thioacetate in water even at their imbalanced stoichiometric ratios.

Численное моделирование поведения карбидов при высокоэнергетическом воздействии

The results of research on modeling thermodynamic parameters of shock-wave loading of carbides with different stoichiometric ratios are presented. The carbides are considered as a mixture of carbon with the corresponding component. The calculations of pressure, compression and temperature values under shock-wave loading for solid and porous carbides in the range of pressure values above 3 GPa are performed. The model calculations are compared with the known experimental results on the shock-wave loading of carbides with different porosity values. The possibility of modeling the behavior according to the proposed method for carbides for which there are no experimental data at high dynamic loads is shown.

Salts of 4-[(benzylamino)carbonyl]-1-methylpyridinium and iodide anions with different cation:iodine stoichiometric ratios

The two iodide salts, 4-[(benzylamino)carbonyl]-1-methylpyridinium iodide–iodine (2/1), C14H15N2O+·I−·0.5I2, I, and 4-[(benzylamino)carbonyl]-1-methylpyridinium triiodide, C14H15N2O+·I3 −, II, with different cation:iodine atoms ratios were studied. Salt I contains one cation, one iodide anion and half of the neutral I2 molecule in the asymmetric unit (cation:iodine atoms ratio is 1:2). Salt II contains two cations, one triiodide anion (I 3 −) and two half triiodide anions (cation:iodine atoms ratio is 1:3). The NH group forms N—H...I hydrogen bonds with the I− anion in the crystal of I or N—H...O hydrogen bonds in II where only triiodide anions are present.

Reactions of MoCl5 with 4-Methylpyridine, 2-Methylpyridine and 1-Methylimidazole in Tetrahydrofuran

MoCl5 reactions with 4-methylpyridine/2-methylpyridine/1-methylimidazole in THF in 1:1/1:2 stoichiometric ratios, at room temperature were carried out. The following products were synthesized: MoO2Cl(C6H7N), 1;Mo2O2Cl5(C6H7N)2(C4H8O)2,2; Mo4O4Cl4(C6H7N)3(C4H8O)2, 3 and Mo2O4Cl4(C4H6N)2(C4H8O), 4. These compounds have been investigated by FT-IR (transmission mode), FT-1H NMR, FT -13C NMR, microbiological, LC-MS and elemental (C, H, N, Mo, Cl) studies. In view of the sensitivity of all the reactants and products towards oxidation/hydrolysis by air/moisture, all the reactions and products were handled using dry nitrogen atmosphere in vacuum line. LC-MS and elemental studies agree with the formulae of compounds.

Silicon Changes C:N:P Stoichiometry and Favors Pre-Sprouted Seedling Growth, Yield and the Technological Quality of Sugarcane.

The importance of silicon (Si) in sugarcane is well known, but its effects on changing C:N:P stoichiometry enough to increase pre-sprouted seedling (PSS) and sugarcane development in the field remains unknown. To that end, the present study aimed to assess whether Si fertigation favors its absorption enough to change elemental stoichiometry (C:N:P), physiological attributes and PSS growth, as well as the growth, stem yield and juice quality of sugarcane. Two field experiments were conducted in the PSS formation stage and another in the sugarcane plant development phase. Experiment 1 was carried out in a greenhouse with PSSs under two treatments: in the absence and presence of Si (2 mmol L−1) fertigation. Experiment 2 was performed in the field in red-yellow argisol with the sugarcane plant undergoing the following treatments: absence of Si (No Si); Si supplied by fertigation during the PSS formation and sugarcane plant development phases (Si–C); and Si supplied during the PSS formation and sugarcane plant development phases (Si–M+C). The following were assessed in experiment I: growth, leaf green color index (GCI), chlorophyll fluorescence, C, N, P, and Si content, and C:Si, C:N and C:P stoichiometric ratios. In experiment II, the same stoichiometric ratios were assessed, as well as sugarcane growth, stem yield and juice quality. Si reduced the C:Si, C:N and C:P stoichiometric ratios in PSS. The C:Si ratio in the leaves and stems declined with the supply of Si, while the C:N and C:P ratio in the leaves and stem was higher in plants that received Si in the Si-M+C treatment. Applying Si fertigation in PSS formation to promote changes in C:N:P stoichiometry favored photosynthetic efficiency and growth. The Si–M+C treatment stood out, since it also caused enough C:N:P stoichiometric changes to increase sugarcane growth, yield and juice quality.

Different root exudates C/N ratios accelerate CO2 emission from paddy soil

Root exudates can greatly modify microbial activity and soil organic matter (SOM) mineralization. However, the mechanism of root exudation and its stoichiometric ratio of C/N controlling upon paddy soil C mineralization are poorly understand. In this study, we used a mixture of glucose, oxalic acid, and alanine as root exudate mimics, employing three C/N stoichiometric ratios (CN6, CN10, and CN80) to explore the underlying mechanisms involved in C mineralization. The input of root exudates enhanced CO2 emission by 1.8–2.3-fold than that of the control. Artificial root exudates with low C/N ratios (CN6 and CN10) increased the metabolic quotient (qCO2) by 12% over those obtained at higher stoichiometric ratios (CN80 and C-only), suggesting a relatively high energy demand for microorganisms to acquire organic N from SOM by increasing N-hydrolase production. The stoichiometric ratios of enzymes (β-1,4-glucosidase to β-1,4-N-acetyl glucosaminidase) promoting organic C degradation compared to those involved in organic N degradation showed a significant positive correlation with qCO2; the stoichiometric ratios of microbial biomass (MBC/MBN) were positively correlated with carbon use efficiency. This suggests that root exudates with higher C/N ratios entail an undersupply of N for microorganisms, triggering the release of N-degrading extracellular enzymes. This in turn decreases SOM mineralization, implying the C/N ratio of root exudates to be a controlling factor. Our findings show that the C/N stoichiometry of root exudates controls C mineralization by the specific response of the microbial biomass through the release of C- and N-releasing extracellular enzymes to adjust for the microbial C/N ratio.

Varying influence of phytoplankton biodiversity and stoichiometric plasticity on bulk particulate stoichiometry across ocean basins

Concentrations and elemental ratios of suspended particulate organic matter influence many biogeochemical processes in the ocean, including patterns of phytoplankton nutrient limitation and links between carbon, nitrogen and phosphorus cycles. Here we present direct measurements of cellular nutrient content and stoichiometric ratios for discrete phytoplankton populations spanning broad environmental conditions across several ocean basins. Median cellular carbon-to-phosphorus and nitrogen-to-phosphorus ratios were positively correlated with vertical nitrate-to-phosphate flux for all phytoplankton groups and were consistently higher for cyanobacteria than eukaryotes. Light and temperature were inconsistent predictors of stoichiometric ratios. Across nutrient-rich and phosphorus-stressed biomes in the North Atlantic, but not in the nitrogen-stressed tropical North Pacific, we find that a combination of taxonomic composition and environmental acclimation best predict bulk particulate organic matter composition. Our findings demonstrate the central role of plankton biodiversity and plasticity in controlling linkages between ocean nutrient and carbon cycles in some regions.

Response of C, N and P Ecological Stoichiometry in Plants and Soils During a Soybean Growth Season to O3 Stress and Straw Return in Northeast China

AimsC, N and P ecological stoichiometry plays important roles on biogeochemical cycles in ecosystems, yet the relationship between plant and soil stoichiometry and stoichiometric effects on the growth of soybean root in response to the O3 stress and straw return remain poorly understood. MethodsHere, a pot experiment was conducted in open top chambers to monitor the response of C, N and P ecological stoichiometry of leaves, shoots, roots and soils during a growing season (branching, flowering and podding stages) of soybean (Glycine max; a highly sensitive species to O3) to background O3 concentration (45 ± 10 ppb), O3 stress (80 ±10 ppb) and straw treatment (no straw return and straw return). ResultsThe O3 stress significantly decreased root biomass. The straw return significantly increased root biomass under the O3 stress at branching and flowering stages. Generally, the O3 stress and straw return showed significant effects on the C, N, P concentrations of leaves and soils, and stoichiometric ratios of leaves, shoots and microbial biomass. C, N, P concentrations and stoichiometric ratios of leaves, shoots, roots and soils responses to the O3 stress and straw return at branching stage were inconsistent with changes observed at the flowering and podding stages. The P conversion efficiency showed significant relationship with root P concentration under the combined effects of O3 stress and straw return. ConclusionsC, N, and P concentrations of soybean might be more important than stoichiometric ratios as a driver of defense against the O3 stress in the case of straw return.

How Elemental Stoichiometric Ratios in Microorganisms Respond to Thinning Management in Larix principis-rupprechtti Mayr. Plantations of the Warm Temperate Zone in China

The stoichiometric ratios of elements in microorganisms play an important role in biogeochemical cycling and evaluating the nutritional limits of microbial growth, but the effects of thinning treatment on the stoichiometric ratio of carbon, nitrogen, and phosphorus in microorganisms remain unclear. We conducted research in a Larix principis-rupprechtti Mayr. plantation to determine the main factors driving microbial carbon (C): nitrogen (N): phosphorus (P) stoichiometry following thinning and the underlying mechanisms of these effects. The plantation study varied in thinning intensity from 0% tree removal (control), 15% tree reduction (high density plantation, HDP), 35% tree reduction (medium density plantation, MDP), and 50% tree reduction (low density plantation, LDP). Our results indicated that medium density plantation significantly increased litter layer biomass, soil temperature, and other soil properties (e.g., soil moisture and nutrient contents). Understory vegetation diversity (i.e., shrub layer and herb layer) was highest in the medium density plantation. Meanwhile, thinning had a great influence on the biomass of microbial communities. For example, the concentration of phospholipid fatty acids (PLFA) for bacteria and fungi in the medium density plantation (MDP) was significantly higher than in other thinning treatments. Combining Pearson correlation analysis, regression modeling, and stepwise regression demonstrated that the alteration of the microbial biomass carbon: nitrogen was primarily related to gram-positive bacteria, gram-negative bacteria, soil temperature, and soil available phosphorus. Variation in bacteria, actinomycetes, gram-positive bacteria, gram–negative bacteria, and soil total phosphorus was primarily associated with shifts in microbial biomass carbon: phosphorus. Moreover, changes in microbial biomass nitrogen: phosphorus were regulated by actinomycetes, gram-negative bacteria, and soil temperature. In conclusion, our research indicates that the stoichiometric ratios of elements in microorganisms could be influenced by thinning management, and emphasizes the importance of soil factors and microbial communities in driving soil microbial stoichiometry.

Variations of Bacterial and Archaeal Community Structure and Diversity Along Soil Profiles in a Peatland in Southwest China

As bacteria and archaea are key components in the ecosystem, their alterations along soil profiles are important in understanding the biogeochemical cycles in peatland. However, little is known about the vertical distribution patterns of bacteria and archaea along the Bitahai peatland, as well as their relationship to soil chemical properties. Here, sequencing of 16S rRNA genes (Illumina, MiSeq) was used to analyze bacterial and archaeal abundance, diversity, and composition across 0-100 cm of the soil. Soil pH, total C, N, and P concentrations and stoichiometric ratios also were estimated. Results revealed that total C and total N contents, as well as C:P and N:P ratios, significantly increased with increasing peatland depths, while total P decreased. The top three dominant phyla were Proteobacteria (39.64%), Acidobacteria (12.93%), and Chloroflexi (12.81%) in bacterial communities, and were Crenarchaeota (58.67%), Thaumarchaeota (14.34%), and Euryarchaeota (10.82%) in archaeal communities in the Bitahai peatland, respectively. The total relative abundance of the methanogenic groups and ammonia-oxidizing microorganisms all significantly decreased with soil depths. Both bacterial and archaeal diversity were greatly affected by the soil depths. Soil C, N, and P concentrations and stoichiometric ratios markedly impacted the community structure and diversity just in archaea, not in bacteria. Therefore, these results highlighted that the microbial community structure and diversity depended on soil depths, and the affecting factors for bacteria and archaea were different in the peatlands.