High Excess Research Articles

Tarim Large Igneous Province Caused by a Wide and Wet Mantle Plume

AbstractLarge igneous provinces (LIPs) can form by interactions between a hot mantle plume and the lithosphere. The Tarim LIP between ~300 and 280 Ma, located in Northwest China, has been investigated by geochemistry and sedimentology studies. However, the factors controlling Tarim LIP formation and the ancient Tarim plume characteristics remain unclear. Here, a series of 3‐D geodynamic models are combined with geological observations to constrain the Tarim LIP evolution and the features of the related Tarim plume. Our results show that (1) an ancient plume produced abundant melts attributed to decompression melting, excess temperature, high water contents, and slow plate motion velocities to form the banded Tarim LIP. (2) The simulated pre‐eruption topography coincides with the stratigraphic records from the late Carboniferous to early Permian. Specifically, the swell area of pre‐eruption topography is sensitive only to the plume radius and enables us to constrain the ancient mantle plume size well. (3) Based on the volcanic activity and pre‐eruption topography, we infer that the ancient Tarim plume had a very large radius of ~200 km, a high excess temperature of ~250 K, and a high water content of ~5 wt.%. (4) Our parameter tests and global plate reconstruction results show that high water contents and slow plate motion velocities facilitate continental flood basalts to form with thick lithosphere. Our geodynamic modeling not only provides new constraints for the Tarim LIP evolution but also first quantificationally demonstrates that water in the mantle plays a key role in continental flood basalt formation.

Late Quaternary sporadic development of Desmophyllum dianthus deep-coral populations in the southern Labrador Sea with specific attention to their 14C- and 230Th-dating

About 70 fossil and live-collected specimens of Desmophyllum dianthus were collected from steep rocky surfaces and time-averaged assemblages at their base (“coral graveyards”) in the southern Labrador Sea at depths ranging from ~1700 m (Orphan Knoll) to ~2200 m (Flemish Cap). Aside from stable isotope and mineralogical analysis, U-series and 14C age determinations were performed on the samples. Fossil corals from the coral graveyards display two principal age clusters corresponding respectively to the Holocene and Marine Isotope Stage (MIS) 5c intervals. Three samples lay outside these clusters, at ~13.5 ka (Bølling-Allerød), ~ 64 ka (MIS 3) and at ~181 ka (MIS 7a). The clusters are thought to record intervals with both i) high food availability, either through pelagic primary production in the overlying water column or more effectively in relation with particulate and dissolved organic carbon transport via an active Western Boundary Undercurrent (WBUC), and ii) high carbonate micrite advection by this current from more open North Atlantic coccolithophorid production areas, maintaining an aragonite saturation horizon (now at 2300 m) slightly deeper than the coral habitat (~ 2200 m). Attempts at estimating ventilation ages from 230Th vs 14C age offsets in Holocene samples failed. This is due to uncertainties about the initial 14C-apparent age of coral skeletons and to their high initial excesses in 230Th. This initial excess relates mostly to the scavenging of 230Th produced by the dissolved marine U by the coral-feeding organic matter carried along the WBUC trajectory. In addition, discrete diagenetic U-fluxes can be documented in fossil samples. They are well illustrated in specimens from MIS 5c age, which depict variable excesses in 234U vs 238U, but similar 230Th/238U activity ratios, pointing to a recent but fractionating redistribution of uranium in the samples. These are also documented by the development of FeMn coatings of specimens exposed at the sea floor, due to the winnowing of embedding slope sediments, with the mid- to late Holocene intensified WBUC. Such diagenetic processes are to be notably taken into consideration for the dating of pre-Holocene samples. Thus, both the initial isotopic properties of corals from this WBUC-influenced, mid-continental slope, and subsequent diagenetic effects impact their calculated ages, and blur estimates of “ventilation ages” based on their 14C vs 230Th-ages offsets.

Analysis of the treatment regimen efficacy for columnaris disease in Pterophyllum scalare

The article presents the results of studies on the treatment scheme efficacy for columnaris in Pterophyllum scalare, common under private aquarium husbandry conditions. To establish the diagnosis, the clinical features of the diseased fish, pathological and anatomical changes and the results of microscopic and microbiological studies were taken into account. Separate chemical and microbiological parameters of aquarium water were also studied. It was established that fish disease developed against the background of adverse changes in the chemical composition and microbiocenosis of aquarium water. High alkalinity and excess of phosphates compared to the norm provoked accumulation of opportunistic microbiota, resulting in a balance disorder in the parasite-host system and development of clinical manifestation of the fish disease. During the disease outbreak, bacteriological indices of water indicated a high level of organic contamination and a low intensity of water self-purification processes. Clinically, the disease was manifested in P. scalare by decrease in appetite and motor activity, onset of ulcerative lesions of various shapes and sizes on the surface of the body and on the gill covers. Selected pure cultures of Flavobacterium columnare showed sensitivity to enrofloxacin (growth retardation zone 31.3 ± 1.0 mm); moderate resistance was found to tylosin. The microorganisms were resistant to amoxicillin, doxycycline, benzylpenicillin and tetracycline. Microscopic studies of intestinal specimens of dead P. scalare revealed numerous motile flagellates. It has been shown that an effective treatment regimen that provides recovery for 70% of diseased P. scalare is the use of enroxil 10% solution for five days, metronidazole three times a day, and “API MelaFix” for seven days. It is proved that the following measures are effective to restore the disrupted hydro-balance: periodic water replacement in the amount of 20% of the total volume, providing the aquarium with active aeration systems, planting slow-growing plants and reducing the amount of fish food provided. The measures developed were efficient, they led to elimination of the outbreak of columnaris in the P. scalare and to restoration of biological equilibrium in a closed aquatic ecosystem.

Integrating Distributed Acoustic Sensing, Treatment-Pressure Analysis, and Video-Based Perforation Imaging To Evaluate Limited-Entry-Treatment Effectiveness

Summary The primary objectives of perforating a lengthy cased-and-cemented wellbore section for fracture stimulation are to enable extensive communication with the reservoir and control the allocation of fluid and proppant into multiple intervals as efficiently as possible during fracturing treatments. Simultaneously treating multiple intervals reduces the number of fracture stages required, thus reducing treatment cost. One way to control the allocation is to use limited-entry perforating. Execution and optimization of limited-entry perforating requires awareness of the factors that can affect performance. This paper presents a case study of plug-and-perforate horizontal-well treatments in an unconventional shale play in which various diagnostic methods were used to better understand these factors. Within the case study, three types of perforation-evaluation diagnostics were implemented: injection step-down tests and pressure analysis of the fracturing treatments, video-based perforation imaging, and distributed acoustic sensing (DAS). Injection step-down tests indicated that all perforations were initially accepting fluid. Surface-pressure analysis of the main fracturing treatments indicated that in certain cases, several perforations were not accepting fluid and proppant (slurry) by the end of the job. Video-based imaging indicated that a large majority of perforations showed unambiguous evidence of significant proppant entry. Evaluation of the erosion patterns on the perforations showed a positional bias where for a given fracture stage, perforations in clusters nearest the heel of the well were more eroded than perforations in clusters nearest the toe of the well. DAS analysis showed a positional bias, allocating more slurry volume to clusters nearest the heel of the well. However, DAS analysis also showed that changing the number of perforations in a cluster had a larger effect than the positional bias. The results of the case study indicated that a staggered perforation design using more gradual changes among clusters would lead to a more balanced treatment. This scenario was evaluated along with a job design featuring high excess perforation friction and an equal number of perforations in each cluster. Fracture-simulation runs indicated that both tactics are likely to improve slurry allocation.

Екологічний моніторинг органолептичних і кисневих показників у поверхневих водах Житомирського району в період сніготанення

Наведено результати досліджень екологічного стану поверхневих вод Житомирського району за органолептичними та кисневими показниками в період сніготанення. До досліджуваних водойм належать річка Тетерів та її притоки, водосховище Відсічне, з якого здійснюють водозабір для питного водопостачання у Житомирі. Основні пункти відбору проб води нанесли на карту Житомирського району. Дослідження проводили у повеневий період, коли водність річок, і, відповідно, вплив чинників довкілля – найбільші. Упродовж 2016-2018 рр. спостерігали тенденцію до зміни органолептичних і кисневих показників, хоча і не значну. Найбільше перевищень норм ДСанПіН 2.2.4-171-10 та ДСТУ 4808:2007 спостерігали за кольоровістю та біологічним споживанням кисню (БСК). Понаднормову кольоровість та біологічне споживання кисню виявлено майже у всіх відібраних зразках води. Дещо кращою, але не набагато, була ситуація з мутністю води. За цим показником у 2016 р. забрудненими виявилося понад 80 % зразків, у 2017 р. – 50 % та в 2018 р. – 73 % відповідно. На підставі отриманих результатів можна стверджувати, що поверхневі води Житомирського р-ну відносять до ІІ класу якості, тобто це води, які мають мутність (каламутність) (до 150 мг/дм3) і кольоровість (до 120 градусів за платиново-кобальтовою шкалою (ПКШ)) та належать до полісапробних, БСК5 яких більше 12 мг О2/дм3).

Removal of glycerol from enzymatically produced 2-α-d-glucosyl-glycerol by discontinuous diafiltration

2-α-d-Glucosyl-glycerol (2-GG) is a natural glycoside that acts as a biological extremolyte. 2-GG is a promising ingredient for cosmetic products. Industrially, 2-GG is synthesised from sucrose in the presence of a high excess of glycerol using the enzyme sucrose phosphorylase. For commercial applications, the surplus glycerol must be removed and an efficient purification strategy is therefore demanded. Here, we demonstrate nanofiltration for the separation of glycerol from 2-GG. Based on membrane screening performed at varied pressure and temperature, we identified a 150–300 Da cut-off polyamide membrane for the selective removal of glycerol at high permeate throughput. An enzymatically produced 2-GG solution was purified with multicycle discontinuous diafiltration on the litre scale. The process was operated at constant permeate flux (13 kg m−2h−1) and at a temperature of 30 °C. A complete removal of glycerol was achieved after six diafiltration cycles. This was in accordance with the simulation results of a mass balance model. The purity of the product solution increased to 80%, which is comparable with commercially products containing functional carbohydrates. The achieved product recovery was around 85%.

Deep carbon through time: Earth’s diamond record and its implications for carbon cycling and fluid speciation in the mantle

Diamonds are unrivalled in their ability to record the mantle carbon cycle and mantle fO2 over a vast portion of Earth’s history. Diamonds’ inertness and antiquity means their carbon isotopic characteristics directly reflect their growth environment within the mantle as far back as ∼3.5 Ga. This paper reports the results of a thorough secondary ion mass spectrometry (SIMS) carbon isotope and nitrogen concentration study, carried out on fragments of 144 diamond samples from various locations, from ∼3.5 to 1.4 Ga for P [peridotitic]-type diamonds and 3.0 to 1.0 Ga for E [eclogitic]-type diamonds. The majority of the studied samples were from diamonds used to establish formation ages and thus provide a direct connection between the carbon isotope values, nitrogen contents and the formation ages. In total, 908 carbon isotope and nitrogen concentration measurements were obtained. The total δ13C data range from −17.1 to −1.9 ‰ (P = −8.4 to −1.9 ‰; E = −17.1 to −2.1‰) and N contents range from 0 to 3073 at. ppm (P = 0 to 3073 at. ppm; E = 1 to 2661 at. ppm). In general, there is no systematic variation with time in the mantle carbon isotope record since > 3 Ga. The mode in δ13C of peridotitic diamonds has been at −5 (±2) ‰ since the earliest diamond growth ∼3.5 Ga, and this mode is also observed in the eclogitic diamond record since ∼3 Ga. The skewness of eclogitic diamonds’ δ13C distributions to more negative values, which the data establishes began around 3 Ga, is also consistent through time, with no global trends apparent.No isotopic and concentration trends were recorded within individual samples, indicating that, firstly, closed system fractionation trends are rare. This implies that diamonds typically grow in systems with high excess of carbon in the fluid (i.e. relative to the mass of the growing diamond). Any minerals included into diamond during the growth process are more likely to be isotopically reset at the time of diamond formation, meaning inclusion ages would be representative of the diamond growth event irrespective of whether they are syngenetic or protogenetic. Secondly, the lack of significant variation seen in the peridotitic diamonds studied is in keeping with modeling of Rayleigh isotopic fractionation in multicomponent systems (RIFMS) during isochemical diamond precipitation in harzburgitic mantle. The RIFMS model not only showed that in water-maximum fluids at constant depths along a geotherm, fractionation can only account for variations of <1‰, but also that the principal δ13C mode of −5 ± 1‰ in the global harzburgitic diamond record occurs if the variation in fO2 is only 0.4 log units. Due to the wide age distribution of P-type diamonds, this leads to the conclusion that the speciation and oxygen fugacity of diamond forming fluids has been relatively consistent. The deep mantle has therefore generated fluids with near constant carbon speciation for 3.5 Ga.

Small modular reactor full scope core optimization using Cuckoo Optimization Algorithm

Small Modular Reactors (SMRs) with their excellent safety and economic features will be in high demand in the near future. Most SMR designs have longer burn-up cycle length with more fuel enrichment and smaller core size in comparison to the large conventional nuclear reactors. The small size of these reactors causes more neutron leakage (less core radius results in a higher area to volume ratio and more relative leakage). This feature of SMRs causes high values of maximum Power Peaking Factors (PPFs) through the core, so optimizing the safety parameters is of high necessity. Also, long burn-up cycle length needs a high initial excess reactivity, which results into use of some materials and methods to control this high excess reactivity. One of these methods is using a high number of Integral Fuel Burnable Absorber (IFBA) rods.In the present designs of IFBA rods, usually some amounts of fuel with lower enrichment are used at the top and bottom parts of the IFBA rods (known as cutback fuel) to flatten the axial PPFs. The small size of the SMRs (using a lower number of FAs) helps to have much less possible radial loading patterns (in comparison to the large reactors) and provides the possibility to optimize the axial variations in amounts of cutback fuel in IFBA rods simultaneously. Accordingly, the best axial and radial loading pattern according to the objective functions could be achieved. At the present work, the main goal is to optimize radial core loading pattern and axial variations of cutback fuel lengths at the IFBA rods of an SMR simultaneously using a multi-objective neutronic and thermal-hydraulic fitness function. The multi-objective fitness function includes burn-up cycle length, Minimum Departure from Nucleate Boiling (MDNBR), maximum and average radial and axial PPFs during the entire cycle lengths. The Cuckoo Optimization Algorithm (COA) as a new robust metaheuristic algorithm with high convergence speed and global optima achievement has been used. For the thermo-neutronic calculation, DRPACO package consists of the coupling system of DRAGON/PARCS/COBRA codes have been used. Finally, the results of SMR core axial and radial loading pattern optimization using COA presents a core configuration with improvement in the core safety and economic parameters in comparison to the reference SMR core.

Mortality Atlas of the Campania Region. All-cause and cause-specific mortality at municipal level, 2006-2014

Mortality Atlas of the Campania Region. All-cause and cause-specific mortality at municipal level, 2006-2014

Modulation of the catalytic activity of a metallonuclease by tagging with oligohistidine

Peptide tags are extensively used for affinity purification of proteins. In an optimal case, these tags can be completely removed from the purified protein by a specific protease mediated hydrolysis. However, the interactions of these tags with the target protein may also be utilized for the modulation of the protein function. Here we show that the C-terminal hexahistidine (6 × His) tag can influence the catalytic activity of the nuclease domain of the Colicin E7 metallonuclease (NColE7) used by E. coli to kill competing bacteria under stress conditions. This enzyme non-specifically cleaves the DNA that results in cytotoxicity. We have successfully cloned the genes of NColE7 protein and its R447G mutant into a modified pET-21a DNA vector fusing the affinity tag to the protein upon expression, which would be otherwise not possible in the absence of the gene of the Im7 inhibitory protein. This reflects the inhibitory effect of the 6 × His fusion tag on the nuclease activity, which proved to be a complex process via both coordinative and non-specific steric interactions. The modulatory effect of Zn2+ ion was observed in the catalytic activity experiments. The DNA cleavage ability of the 6 × His tagged enzyme was first enhanced by an increase of metal ion concentration, while high excess of Zn2+ ions caused a lower rate of the DNA cleavage. Modelling of the coordinative effect of the fusion tag by external chelators suggested ternary complex formation instead of removal of the metal ion from the active center.

Novel In Situ Gas Formation Analysis Technique Using a Multilayer Pouch Bag Lithium Ion Cell Equipped with Gas Sampling Port

Parasitic gas evolution in lithium ion battery (LIB) cells especially occurs within the first charge cycle, but can also take place during long-term cycling and storage, thereby, negatively affecting the cell performance. Gas formation is influenced by various factors, such as the cell chemistry and operating conditions, thus, demanding fundamental studies in terms of interphase and gas formation (gas volume and composition) and electrolyte consumption. Gas analyses in terms of mass spectrometry of gaseous products are regularly performed, however, usually using custom-made cell designs with a high excess of electrolyte. Here, a gas sampling port (GSP) is incorporated in a commercial small-scale multilayer pouch cell in a simple post-production process and systematically evaluated as proof-of-principle approach towards effective electrolyte additive research under practically relevant conditions, i.e., when applying a limited amount of electrolyte per cell capacity. The GSP-based LIB pouch cell design allows the voltage-dependent identification and separation of formed gases, while a clear correlation between electrolyte reduction peaks, observed in differential capacity profiles, and the onset of gas evolution is demonstrated. In summary, the novel GSP-based pouch cell setup benefits from the possibility of multiple time-, cell voltage- or state-of-charge-dependent gas measurements, without significantly influencing the original cell performance.

Effect of ceramic particles on precipitation in an Al-Mg-Si alloy with silicon excess during ageing

Providing a good balance between lightweight and high mechanical properties, the aluminum-based metal matrix composites (MMC) became an interesting alternative for specific industrial applications. However, considering an Al-Mg-Si alloy with a high silicon excess, the ceramic particles added as reinforcement can act on : i) the precipitation kinetics of the coherent and semi-coherent phases, ii) the precipitation sequence of the alloy and iii) the loss of mechanical strength from a peak-aged microstructure obtained by a T6 condition. In order to understand the influence of reinforcement on these aspects, the composite was characterized during isothermal ageing between 100°C and 350°C, allowing us to propose an experimental Isothermal Transformation Curve. Compared to the unreinforced alloy, heterogeneous precipitation of disordered semi-coherent phases occurs on dislocations and the precipitation kinetics were found to be accelerated in the composite leading to an acceleration of the loss of strength from the T6 state, due to the precipitation of the Type-C phase. A study performed on a deformed alloy, demonstrated that the most of the differences observed between the unreinforced alloy and the composite can be explained by the high dislocation density generated in the matrix of the composite due to the presence of ceramic particles. Finally, the JMAK approach turned out to be a powerful tool to model the decrease in mechanical strength occurring during isothermal treatments from T6 state.

Centrifuge Modeling of Axial Pipe-Soil Interaction of Deep-Water Pipelines

Abstract This article describes equipment primarily developed for modeling axial pipe-soil interaction of offshore pipelines in a beam centrifuge. The equipment can displace the pipe axially and simulate vertical forces or oscillations acting on the pipe while the pipe is instrumented to measure the contact stresses, pore pressure, and sliding resistance. Axial motion is actuated by a servomotor actuator coupled to a chain-drive system that moves the pipe in the axial direction relative to the soil bed. A closed-loop servo-driven vertical actuator simulates the vertical forces or oscillations acting on the pipe. The centrifuge model tests were conducted under 10-g model gravity. The pipe penetration response, axial pipe-soil resistance, and pore pressure behavior beneath the pipe were investigated. A higher axial pipe-soil resistance was measured for axial shearing of the pipe that was relatively slow compared to rapid axial shearing. For rapid pipe shearing, high excess pore pressure was generated at the pipe invert compared to relatively low pore water pressure for slower movement of the pipe. The results show that the developed equipment is capable of producing highly consistent results over the range of drained and undrained response, which also agree well with recently reported finite element studies and shear box tests conducted to explore long-term axial friction. This makes the equipment potentially useful for generating high-quality data under controlled conditions in the centrifuge for mechanistic and validation studies.

Influence of the cationic composition on the optical properties and photostability of AgInS2 and AgInS2/ZnS quantum dots

Semiconductor I-III-VI nanocrystals are highly luminescent low toxic materials with direct band gap and tunable emission in visible and near infrared region which can be synthesized in aqueous media via simple procedure making them competitive object in compare with well developed and investigated II-VI quantum dots. However the nature of radiative recombination pathways definition and effect of synthesis conditions on spectral characteristics of the nanocrystals investigation remains an important task. In the present work influence of the cation precursors ratio as well as the heat treatment duration on the composition, optical properties and photostability of AgInS2 and AgInS2/ZnS nanocrystals synthesized in aqueous media have been investigated. Due to the low reactivity of indium salts in aqueous solution coused by formation of a stable complexes with stabilizer or hydroxycomplexes the nearest stoichiometric Ag1,1InSx quantum dots are formed at the initial [In]:[Ag] ratio 7:1. Under high excess of Ag formation of Ag2S/AgInS2 core/shell quantum dots confirming by presence of large 12-15 nm nanocrystals and red shift of the photoluminescence maximum with increasing [In]:[Ag] ratio from 1 to 3 (shell thickness should increase proportionally) is possible. With a further increase of the [In]:[Ag] ratio the absorption edge and the photoluminescence maximum are green shifted indicating increase of the quantum dots band energy. That can be explained by lowering of the valence band ceiling energy and rising of the conduction band bottom energy due to decrease of density of states of Ag 4d orbitals and increase of density of states of In 5s and 5p orbitals involved in the AgInS2 band gap formation. Increase of Indium content leads to significant increase of the photoluminescence intensity of AgInS2 nanocrystals eliminating nonradiative defects such as Agi. It have been shown that the ZnS shell epitaxial grow occurs due to the cation exchange between Zn2+ and In3+ and takes place only at low concentration of Zinc precursor ([Zn]:[Ag] ≤ 4). With further enhancement of the ratio the solid solution of AgInS2-ZnS is forming. To achieve the highest possible photoluminescence intensity and energy the AgInS2-ZnS nanocrystals should be heated at 950C at least for 120 minutes. It have been shown that the nearly stoichiometric Ag1,1InSx nanocrystals posess the highest photostability under UV light irradiation.

Coronary Artery Perforation and Tamponade - Incidence, Risk Factors, Predictors and Outcomes From 12 Years' Data of the SCAAR Registry.

The incidence and short- and long-term outcomes of coronary artery perforation (CAP) are not well described. We analyzed the characteristics and the short- and long-term outcomes of CAP among 243,149 patients undergoing percutaneous coronary interventions (PCI) from 2005 until 2017 in the national Swedish registry. We identified 1,008 cases of CAP with an incidence of 0.42%. Major adverse event rates were significantly higher in patients with CAP than non-CAP (P<0.001). The 1-year mortality rate was 16% vs. 5.5%, respectively, and the 12-year mortality rate was 52% vs. 34%. The restenosis rate was 5.2% vs. 3.1% and 17% vs. 9%, respectively. The target lesion revascularization rate was 4.2% vs. 2.6% and 10.5% vs. 7%. The stent thrombosis rate was numerically higher, 1.5% vs. 0.8% and 4.5 vs. 2.8%, with no stent thrombosis cases for equine pericardial stent grafts. Among the patients with tamponade a large proportion of cases occurred at the late stage (215/1,008, 21%), and most were not recognized in the cath-lab (167/215, 78%). The mortality rate for late tamponade was similar in patients suffering acute tamponade at 1 year (25.6% vs. 27%) or at 12 years (54% vs. 58%). CAP is associated with an early high excess in morbidity and mortality but with low risk of additional adverse events in the long term. Late tamponade is as deadly as acute tamponade.

Does Corporate Governance Causally Impact Firm Returns? The Case of India

This paper discusses stakeholder wealth maximization as the ultimate objective of Corporate Governance. This study investigates the role of CG in minimizing the total risk on the firm and maximizing the wealth. At the end, paper intends to examine possibility of CG as a sorting variable for style investing that can provide abnormal returns in the long run. The main goal is to prove the significance of CG in managing abnormal returns, systematic risk and idiosyncratic risk. Main attention was paid to ordinary least squares regression, correlation studies and creation of financial value chain. This study tries to find an answer to the question, does CG holds the ability to determine the market valuation of the firm? The major findings of the paper finds possibility of high CGPI firms finds higher firm specific risk. Despite that investors seek higher excess returns to compensate the total risk. In lower CGPI firms, study finds lower COV, but a higher FGV, that leads to higher market valuation. The financial value chain hypothesizes CG response to critical variables in CAPM creates impact on COV and FGV, that forms the basis of FSR that eventually generates MVA. There exist a value premium that is accumulating over time and grows beyond growth premium to conclude value portfolio has potential wealth generation ability.

Recovery, Purification, and Reusability of Building Blocks for Solid Phase Synthesis.

Solid phase synthesis (SPS) is well established for the synthesis of biomacromolecules such as peptides, oligonucelotides, and oligosaccharides, and today is also used for the synthesis of synthetic macromolecules and polymers. The key feature of this approach is the stepwise assembly of building blocks on solid support, enabling monodispersity and monomer sequence control. However, in order to achieve such control, a high excess of building blocks is required during the reaction. Herein, the recovery, purification, and reusability of building blocks used in SPS, including representative examples of tailor-made building blocks, Fmoc-protected amino acids, and functionalized carbohydrate ligands, are reported for the first time. Results demonstrate the general applicability with recovery in high yields and high purity. Furthermore, the described recovery process can be applied in both manual and automated synthesis using a standard peptide synthesizer. Overall, this process is envisioned to be applicable for a large variety of building blocks used in the SPS of different types of molecules, and to contribute to more resourceful SPS syntheses.

Polycyclic Aromatic Hydrocarbons in Betula nana (Betulaceae, Magnoliópsida) under Exposure to a Thermal Power Plant

Abstract—The content of polycyclic aromatic hydrocarbons (PAH) in Betula nаnа L. and soil organogenic horizons was studied at a control site and sites affected by a thermal power station (TPS) at distances of 0.5, 1, and 1.5 km from the source of pollution. The PAH distribution over the vegetative organs of the dwarf birch was irregular. Different organs of the dwarf birch had similar qualitative composition of PAHs. No significant changes were detected in the PAH content in dwarf birch organs and on the surface of these organs at different distances from the TPS. The PAH content in the organs of plants affected by the TPS was 2–3 times higher than the background value, and the highest excess was found in leaves. The surface PAH concentration on the bark and roots increased threefold under contamination. No excess was revealed in the leaves and branches. The excess over the background value in the soil at contaminated sites was 3–3.5 times with the maximal accumulation at a distance of 1 km. The PAH content in the soil was three times higher than that in the dwarf birch at the control site and 5–6 times that at the contaminated sites. A strong correlation exists between the PAH concentrations in the soil and in B. nana. In the leaves and branches of B. nаnа, the proportion of surface accumulation in the total PAH pool was found to decrease at contaminated sites as compared with the control site. The opposite trend was observed for the bark and roots. Cluster analysis showed a clear separation between the surface and total PAH content in all plant organs under study. Factor analysis of the total PAH content in the organs of the dwarf birch allowed us to determine three main factors affecting the PAH distribution, with the light structures, toxic components, and the other PAHs were allocated in separate groups. Dwarf birch organs can be used as indicators for the contamination level in tundra communities. We suggest using the PAH content in leaves in order to analyze short-term changes in the PAH content and in the bark to assess the long-term impact.

Environmental and economic performance assessment of elemental sulfur recovery unit installation project

The problem of air pollution is one of the global problems of mankind at the present time. The Irkutsk region has been one of the “leaders” in Russia with the highest excess in air concentrations of maximum permissible concentrations of pollutants during the past decades. The current situation has a very negative impact on the environmental well-being of both adults and children. In the conditions of the prevailing realities, an immediate modernization of production is required, aimed at eliminating or reducing such a prolonged negative impact. The construction and installation of a sulfur recovery unit at oil refineries complies with the latest environmental protection requirements and contributes to a significant reduction in emissions of hydrogen sulfide and sulfur dioxide. The environmental and economic feasibility of such production modernization is illustrated by the example of the Angarsk Petrochemical Company JSC.

Probing planet formation and disk substructures in the inner disk of Herbig Ae stars with CO rovibrational emission

Context. CO rovibrational lines are efficient probes of warm molecular gas and can give unique insights into the inner 10 AU of proto-planetary disks, effectively complementing ALMA observations. Recent studies find a relation between the ratio of lines originating from the second and first vibrationally excited state, denoted as v2∕v1, and the Keplerian velocity or emitting radius of CO. Counterintuitively, in disks around Herbig Ae stars the vibrational excitation is low when CO lines come from close to the star, and high when lines only probe gas at large radii (more than 5 AU). The v2∕v1 ratio is also counterintuitively anti-correlated with the near-infrared (NIR) excess, which probes hot and warm dust in the inner disk. Aims. We aim to find explanations for the observed trends between CO vibrational ratio, emitting radii and NIR excess, and to identify their implications in terms of the physical and chemical structure of inner disks around Herbig stars. Methods. First, slab model explorations in local thermal equilibrium (LTE) and non-LTE are used to identify the essential parameter space regions that can produce the observed CO emission. Second, we explore a grid of thermo-chemical models using the DALI code, varying gas-to-dust ratio and inner disk radius. Line flux, line ratios, and emitting radii are extracted from the simulated lines in the same way as the observations and directly compared to the data. Results. Broad CO lines with low vibrational ratios are best explained by a warm (400–1300 K) inner disk surface with gas-to-dust ratios below 1000 (NCO &lt; 1018 cm−2); no CO is detected within or at the inner dust rim, due to dissociation at high temperatures. In contrast, explaining the narrow lines with high vibrational ratios requires an inner cavity of a least 5 AU in both dust and gas, followed by a cool (100–300 K) molecular gas reservoir with gas-to-dust ratios greater than 10 000 (NCO &gt; 1018 cm−2) at the cavity wall. In all cases, the CO gas must be close to thermalization with the dust (Tgas ~ Tdust). Conclusions. The high gas-to-dust ratios needed to explain high v2∕v1 in narrow CO lines for a subset of group I disks can be naturally interpreted as due to the dust traps that are proposed to explain millimeter dust cavities. The dust trap and the low gas surface density inside the cavity are consistent with the presence of one or more massive planets. The difference between group I disks with low and high NIR excess can be explained by gap opening mechanisms that do or do not create an efficient dust trap, respectively. The broad lines seen in most group II objects indicate a very flat disk in addition to inner disk substructures within 10 AU that can be related to the substructures recently observed with ALMA. We provide simulated ELT-METIS images to directly test these scenarios in the future.