Wing interference patterns are consistent and sexually dimorphic in the four families of crane flies (Diptera, Tipuloidea)

Wing interference patterns (WIP) are stable structural colors in insect wings caused by thin-film interference. This study seeks to establish WIP as a stable, sexually dimorphic, species-level character across the four families of Tipuloidea and investigate generic level WIP. Thirteen species of Tipuloidea were selected from museum specimens in the Academy of Natural Sciences of Drexel University collection. One wing from a male and female of each representative species was excised and mounted to a slide with coverslip, placed against a black background, and imaged using an integrated microscope camera. Images were minimally retouched but otherwise unchanged. Descriptions of the WIP for each sex of each species are provided. Twelve of thirteen species imaged had WIP, which were stable and species specific while eight of those twelve had sexually dimorphic WIP. Comparisons of three species of Nephrotoma were inconclusive regarding a generic level WIP. Gnophomyia tristissima had higher intraspecific variation than other species examined. This study confirms stable, species specific WIP in all four families of crane flies for the first time. More research must be done regarding generic-level stability of WIP in crane flies as well as the role sexual and natural selection play in the evolution of wing interference patterns in insects.

Thermodynamic probability analysis of the effects of Rb on the corrosion susceptibility of Cr-containing steels for nuclear materials canisters

Rubidium (Rb) generated from the β-decay of Kr-85 has been theorized to be corrosive toward steel, specifically in the storage of Kr-85 nuclear waste streams. In the present study, the phase equilibria of RbxCryOz oxides with Rb in dry oxygen and water are investigated to understand a possible pathway to unusual deterioration of the corrosion resistance of canister steels in the presence of Rb. It was found that, in dry oxygen environments, the accumulation of Rb (more than 0.01 mol) can completely consume the Cr in 1 mol of AISI 4130 steel by forming -Rb2CrO4 and Rb3CrO4 and prevent the formation of protective Cr2O3 scale. In aqueous environments, RbxCryOz oxides are metastable species. In order to investigate their role, the probability of forming various oxides is invoked in order to avoid the all-or-nothing approach to oxide formation typical of E-pH diagram, which only predicts the most stable species dissolved, ionized or solid ionized. Thus, the probability of forming RbxCryOz was considered and reported herein. It was found RbxCryOz can possess a larger than 7% probability of forming over Cr2O3 in Rb rich case and 15% in Cr rich case, indicating that it is expected to find small amount of RbxCryOz in the thermodynamically formed reaction products. Even though Cr2O3 is more stable than RbxCryOz oxides, the protective Cr2O3 scale is likely to have some vulnerability to Rb, leading to one possible route for the decline in the corrosion resistance of steel canisters in aqueous environments. Therefore, from a thermodynamic perspective, the current study supports the hypothesis that Rb can thermodynamically react with Cr in steels and can lead to formation of RbxCryOz at certain potentials and pH levels, showing the Rb influence of steel corrosion cannot be discounted. The paper considers experimental mixed potential and pH levels observed and relationship to thermodynamic probability. From this relative corrosion resistance can be assessed in a preliminary way in aqueous environments.

Bird diversity in the Gumuk ecosystem in Jember

Gumuk is one of the important ecosystems in bird conservation in Jember Regency. Currently, many gumuk ecosystems are being degraded, and very rapid land-use change that threatens the preservation and conservation of birds. This study aims to determine the diversity of birds around the gumuk as an effort to explain the important role of the gumuk as a bird habitat. The research was conducted in January-February 2021 in Ledokombo District, Jember Regency. Bird observation method using Point Count method, observation time is in the morning (06.00-08.00 WIB) and afternoon (15.00-17.00 WIB). The results showed that there were 33 species of birds from 20 families. The families of Campephagidae and Estrildidae show the families with the most species found. The level of diversity shows the moderate category (H'=2.253). Species with the highest abundance were Collocalia linchi (31.264%), and the lowest were Amandava amandava, Dicaeum concolor, Geopelia striata, Passer montanus, and Ardeola speciosa (0.044%). Evenness index (E) shows the condition of stable species distribution with a value of 0.644.

Methodological Investigation for Hydrogen Addition to Small Cage Carbon Fullerenes

Hydrogenated small fullerenes (Cn, n < 60) are of interest as potential astrochemical species, and as intermediates in hydrogen-catalysed fullerene growth. However, the computational identification of key stable species is difficult due to the vast configurationally space of structures. In this study, we explored routes to predict stable hydrogenated small fullerenes. We showed that neither local fullerene geometry nor local electronic structure analysis was able to correctly predict subsequent low-energy hydrogenation sites, and sequential stable addition searches also sometimes failed to identify most stable hydrogenated fullerene isomers. Of the empirical and semi-empirical methods tested, GFN2-xTB consistently gave highly accurate energy correlations (r > 0.99) to full DFT-LDA calculations at a fraction of the computational cost. This allowed identification of the most stable hydrogenated fullerenes up to 4H for four fullerenes, namely two isomers of C28 and C40, via “brute force” systematic testing of all symmetry-inequivalent combinations. The approach shows promise for wider systematic studies of smaller hydrogenated fullerenes.

An automated framework for high-throughput predictions of NMR chemical shifts within liquid solutions

Identifying stable speciation in multicomponent liquid solutions is of fundamental importance to areas ranging from electrochemistry to organic chemistry and biomolecular systems. However, elucidating this complex solvation environment is a daunting task even when using advanced experimental and computational techniques. Here, we introduce a fully automated, high-throughput computational framework for the accurate and robust prediction of stable species present in liquid solutions by computing the nuclear magnetic resonance (NMR) chemical shifts of molecules. The framework automatically extracts and categorizes hundreds of thousands of atomic clusters from classical molecular dynamics (CMD) simulations to identify the most stable speciation in the solution and calculate their NMR chemical shifts via DFT calculations. Additionally, the framework creates an output database of computed chemical shifts for liquid solutions across a wide chemical and parameter space. This task can be infeasible experimentally and challenging using conventional computational methods. To demonstrate the capabilities of our framework, we compare our computational results to experimental measurements for a complex test case of magnesium bis(trifluoromethanesulfonyl)imide Mg(TFSI)2 salt in dimethoxyethane (DME) solvent, which is a common electrolyte system for Mg-based batteries. Our extensive benchmarking and analysis of the Mg2+ solvation structural evolutions reveal critical factors such as the effect of force field parameters that influence the accuracy of NMR chemical shift predictions in liquid solutions. Furthermore, we show how the framework reduces the efforts of performing and managing over 300 13C and 600 1H DFT chemical shift predictions to a single submission procedure. By enabling more efficient and accurate high-throughput computations of NMR chemical shifts, our approach can accelerate theory-guided design of liquid solutions for various applications.

Methodological Investigation for Hydrogen Addition to Small Cage Carbon Fullerenes

Hydrogenated small fullerenes (Cn, n&lt;60) are of interest as potential astrochemical species, and as intermediates in hydrogen catalysed fullerene growth. However computational identification of key stable species is difficult due to the vast combinatorial space of structures. In this study we explore routes to predict stable hydrogenated small fullerenes. We show that neither local fullerene geometry nor local electronic structure analysis are able to correctly predict subsequent low energy hydrogenation sites, and indeed sequential stable addition searches also sometimes fail to identify most stable hydrogenated fullerene isomers. Of the empirical and semi-empirical methods tested, GFN2-xTB consistently gives highly accurate energy correlation (r&gt;0.99) to full DFT-LDA calculations at a fraction of the computational cost. This allows identification of the most stable hydrogenated fullerenes up to 4H for four fullerenes, namely two isomers of C28 and C40, via &ldquo;brute force&rdquo; systematic testing of all symmetry inequivalent combinations. The approach shows promise for wider systematic studies of smaller hydrogenated fullerenes.

Accurate Reference Gas Mixtures Containing Tritiated Molecules: Their Production and Raman-Based Analysis

Highly accurate, quantitative analyses of mixtures of hydrogen isotopologues—both the stable species, H2, D2, and HD, and the radioactive species, T2, HT, and DT—are of great importance in fields as diverse as deuterium–tritium fusion, neutrino mass measurements using tritium β-decay, or for photonuclear experiments in which hydrogen–deuterium targets are used. In this publication we describe a production, handling, and analysis facility capable of fabricating well-defined gas samples, which may contain any of the stable and radioactive hydrogen isotopologues, with sub-percent accuracy for the relative species concentrations. The production is based on precise manometric gas mixing of H2, D2, and T2. The heteronuclear isotopologues HD, HT, and DT are generated via controlled, in-line catalytic reaction or by b-induced self-equilibration, respectively. The analysis was carried out using an in-line intensity- and wavelength-calibrated Raman spectroscopy system. This allows for continuous monitoring of the composition of the circulating gas during the self-equilibration or catalytic evolution phases. During all procedures, effects, such as exchange reactions with wall materials, were considered with care. Together with measurement statistics, these and other systematic effects were included in the determination of composition uncertainties of the generated reference gas samples. Measurement and calibration accuracy at the level of 1% was achieved.

Predicting Bilayer B50, B52, B56, And B58: Structural Evolution In Bilayer B48–B72 Clusters

The successive experimental observations of planar, cage-like, seashell-like, and bilayer Bn–/0 clusters in the size range between n = 3–48 well demonstrate the structural diversity and rich chemistry of boron nanoclusters. Based on extensive global minimum search and density functional theory calculations, we predict herein the bilayer C1 B50 (I), C2h B52 (II), C1 B56 (IV), and C2v B58 (V) as the global minima of the systems to fill in the missing gap in the bilayer B2n series between B48–B72. These highly stable species all contain a B38 bilayer hexagonal prism at the center, with 2, 2, 3, and 3 effective interlayer B-B σ-bonds formed between inward-buckled atoms on the top and bottom layers, respectively. Our bilayer C1 B50 (I) and C1 B56 (IV) prove to be obviously more stable than the previously reported monolayer planar C2v B50 and C2v B56 with two adjacent B6 hexagonal holes. Detailed bonding analyses indicate that these bilayer clusters follow the universal bonding pattern of σ + π double delocalization, making them three-dimensionally aromatic in nature. The bilayer B2n species in the size range between B48–B72 evolve gradually on the waist around the B38 or elongated B46 bilayer hexagonal prism at the center.

Thionitroxyl Radical (H2NS) Isomers: Structures, Vibrational Spectroscopy, Electronic States and Photochemistry

The thionitroxyl radical (H2NS) isomers are characterized using advanced ab initio methodologies. Computations are done using standard and explicitly correlated coupled cluster, CASSCF and MRCI approaches in conjunction with large basis sets, extrapolated to the complete basis set (CBS) limit. The lowest electronic states of different isomers are mapped along the stretching coordinates, thereby confirming the existence of the four already known ground state structures, namely H2NS, H2SN, cis-HNSH and trans-HNSH. Also, it is shown that only the lowest electronic excited states are stable, whereas the upper electronic states may undergo unimolecular decomposition processes forming H + HNS/HSN or the HN + SH or N + H2S or S + NH2 fragments. These data allow an assignment of the deep blue glow observed after reactions between “active nitrogen” and H2S at the beginning of the XXth century. For stable species, a set of accurate structural and spectroscopic parameters are provided. Since small nitrogen-sulfur molecular species are of astrophysical relevance, this work may help for identifying the thionitroxyl radical isomers in astrophysical media and in the laboratory.

Contribution of ecological restoration in preservation of forests ecosystems in Algeria

Under the combined effect of anthropogenic pressures and climate change, forest ecosystems can no longer play their ecological and economic role if nothing is done to adapt them. The impacts of fires, overgrazing and overexploitation are that over 60% of forest ecosystems are in an advanced stage of degradation. It is in this context that a new strategy focused on ecological restoration must be quickly put in place. It must be based on ecological alternatives designed to adapt the composition and structure of these plant formations to environmental conditions. The concept of stable species, living space, keystone species, natural attributes and habitat identification. The ecological restoration proposed will allow preserving the vegetal cover at first time and then developing the species with resilience through a list of species that could develop under different pressures, both natural and anthropogenic.