High Lability Research Articles

Photochemical Deracemization of N‐Carboxyanhydrides En Route to Chiral α‐Amino Acid Derivatives

AbstractReadily accessible, racemic N‐carboxyanhydrides (NCAs) of α‐amino acids underwent a deracemization reaction upon irradiation at λ=366 nm in the presence of a chiral benzophenone catalyst. The enantioenriched NCAs (up to 98 % ee) serve as activated α‐amino acid surrogates and, due to their instability, they were directly converted into consecutive products. N‐Protected α‐amino acid esters were obtained after reaction with MeOH and N‐benzoylation (14 examples, 70 %‐quant., 82–96 % ee). Other consecutive reactions included amide (ten examples, 65 %‐quant., 90–98 % ee) and peptide (three examples, 75–89 %, d. r.=97/3 to 94/6) bond formation. Limitations of the method relate for some NCAs to issues with solubility, photooxidation, and high configurational lability.

Photochemical Deracemization of N-Carboxyanhydrides En Route to Chiral α-Amino Acid Derivatives.

Readily accessible, racemic N-carboxyanhydrides (NCAs) of α-amino acids underwent a deracemization reaction upon irradiation at λ=366 nm in the presence of a chiral benzophenone catalyst. The enantioenriched NCAs (up to 98 % ee) serve as activated α-amino acid surrogates and, due to their instability, they were directly converted into consecutive products. N-Protected α-amino acid esters were obtained after reaction with MeOH and N-benzoylation (14 examples, 70 %-quant., 82-96 % ee). Other consecutive reactions included amide (ten examples, 65 %-quant., 90-98 % ee) and peptide (three examples, 75-89 %, d. r.=97/3 to 94/6) bond formation. Limitations of the method relate for some NCAs to issues with solubility, photooxidation, and high configurational lability.

Влияние лесозаготовительной техники на динамику естественного возобновления леса после рубки хвойно-лиственного насаждения средней тайги

The work presents the results of experimental studies on assessment of preliminary and subsequent reforestation depending on the disturbance of the soil cover by logging equipment. The initial survey of the reforestation in the clearing showed the uneven settlement of the territory by woody plants in most parts and individual technological elements. According to morphological characteristics and a set of soil genetic horizons, the soil can be classified as typical Albic Retisols, which develop on loamy soil-forming rocks in well-drained landscapes. We found that the soil of the skidding trail is morphologically close to the original soil. The drag soils have undergone both morphological and chemical changes. The key difference is the change in the composition of the organic horizon following the arrival of a large amount of felling residues and changes in the composition of the ground cover plants. The morphometric parameters of the trees in the mixed stand and undergrowth are of high lability. The stand was dominated by small trees and small undergrowth. The stand and undergrowth are characterized as “healthy”. Relatively good uniformity of its settlement by woody plants was revealed only on portages in ruts with a predominant regeneration of small-leaved species. When the trails are heavily littered, there is no appearance of woody plants. There is no regeneration in the reclaimed felling areas in the first and second years. There is no resumption in sections with aligned tracks in the first and second year.

Carboxylate-Based Metal-Organic Framework and Coordination Polymer Glasses: Progress and Perspectives.

ConspectusCoordination polymers (CPs) and metal-organic frameworks (MOFs) represent versatile materials with diverse structural and functional properties, making them appealing for various applications. However, their conventional forms, which are typically synthesized as powders or crystals, pose challenges due to limited processability and mechanical fragility. Recently, CP/MOF glasses have emerged as promising alternatives, offering enhanced processability while retaining some of the unique characteristics shown in the mother crystalline materials. Despite the prevalence of carboxylate ligands in CP/MOF synthesis, the development of carboxylate-based CP/MOF glasses has been limited compared to that of zeolitic-imidazole framework (ZIF)-based glasses. This is attributed to the strong metal-ligand bonds and low thermal stability of carboxylic acids, which hinder their melting in CP/MOF structures. Nonetheless, recent advancements have led to a surge in methods for synthesizing carboxylate-based CP/MOF glasses. So far, desolvation and melt-quenching have been introduced for achieving glass structures from CP/MOF precursors.The first melt-quenched MOF glass was reported in 2015 with ZIFs. However, we informally observed the melting of the MOF during thermal decomposition research of aliphatic carboxylate-based MOFs as a sacrificial template dating back to 2013. In that study, aliphatic ligands, instead of aromatic carboxylate, were employed due to their high lability, lower thermal stability, and high degree of freedom, which facilitated pyrolysis. The results were published with a focus on synthesizing hierarchically porous MgO via the pyrolysis of an aliphatic ligand-based Mg-MOF in an inert environment. A decade later, it was revisited and studied as the first melt-quenched carboxylate-based MOF glass, converted from a crystalline MOF through the liquid phase before decomposition during the heating process.This Account aims to introduce six studies, including the aforementioned example, on the synthesis of CP/MOF glasses from carboxylate-based CPs/MOFs that have been published so far. To overcome the challenges with aromatic carboxylates in CP/MOF glass formation, the metal coordination sphere should be altered and the degree of freedom in the ligands should be increased. Based on these approaches, the strategies for vitrification of carboxylate-based CPs/MOFs can be divided into two categories: desolvation and melt-quenching. Desolvation can be preceded by vapor perturbation such as hydration. Carboxylate-based CP/MOF glasses possess the potential to expand into a broader range of applications beyond those of existing CP/MOF glasses. Alongside the diversity offered by carboxylic acid ligands, these materials mirror the extensive range of applications previously explored in the existing carboxylate-based CP/MOF crystals. Moreover, their high processability, inherent to glass materials, enables their applications in various industrial fields. This versatility may extend to previously unexplored areas of utilization such as a novel class of bioactive glass.

Characterizing Neurobehavioral Dysregulation Among Former American Football Players: Findings From the DIAGNOSE CTE Research Project.

Neurobehavioral dysregulation (NBD), a core clinical feature of traumatic encephalopathy syndrome, encompasses neuropsychiatric symptoms reported among individuals with a history of repetitive head impact exposure, including contact sport athletes. The objective of this study was to examine the construct and subconstructs of NBD through a series of factor and cluster analyses. Six clinician-scientists selected self-report questionnaire items relevant to NBD from seven available neuropsychiatric scales through a blinded voting process. These items were subjected to confirmatory factor analyses in a sample of 178 former college and professional American football players and 60 asymptomatic individuals without a history of repetitive head impact exposure. All participants were enrolled in the Diagnostics, Imaging, and Genetics Network for the Objective Study and Evaluation of Chronic Traumatic Encephalopathy Research Project. Factor scores were generated on the basis of the optimal expert-informed model for NBD. Construct validity was assessed with neuropsychiatric scales not included in generation of the factor scores. Cluster analyses with NBD factor scores were used to examine symptom profiles. Factor analyses confirmed that NBD was composed of four subconstructs: explosivity, emotional dyscontrol, impulsivity, and affective lability. Cluster analyses indicated four distinct symptom profiles of NBD in this group of former football players: asymptomatic (N=80, 45%), short fuse (N=33, 19%), high affective lability (N=34, 19%), and high NBD (N=31, 17%). These findings characterize NBD as a multifaceted clinical construct with a heterogeneous presentation, providing a foundation for empirical work on the diagnostic criteria for traumatic encephalopathy syndrome and research on the neurobiological underpinnings of NBD.

Host-Guest Stimuli-Responsive Click Chemistry.

Click chemistry has reached its maturity as the weapon of choice for the irreversible ligation of molecular fragments, with over 20 years of research resulting in the development or improvement of highly efficient kinetically controlled conjugation reactions. Nevertheless, traditional click reactions can be disadvantageous not only in terms of efficiency (side products, slow kinetics, air/water tolerance, etc.), but also because they completely avoid the possibility to reversibly produce and control bound/unbound states. Recently, non-covalent click chemistry has appeared as a more efficient alternative, in particular by using host-guest self-assembled systems of high thermodynamic stability and kinetic lability. This review discusses the implementation of molecular switches in the development of such non-covalent ligation processes, resulting in what we have termed stimuli-responsive click chemistry, in which the bound/unbound constitutional states of the system can be favored by external stimulation, in particular using host-guest complexes. As we exemplify with handpicked selected examples, these supramolecular systems are well suited for the development of human-controlled molecular conjugation, by coupling thermodynamically regulated processes with appropriate temporally resolved extrinsic control mechanisms, thus mimicking nature and advancing our efforts to develop a more function-oriented chemical synthesis.

Concentration and compositional controls on degradation of permafrost‐derived dissolved organic matter on the Qinghai–Tibetan Plateau

AbstractUnderstanding the fate of permafrost‐derived dissolved organic matter (DOM) is critical for unraveling its role in carbon cycling. However, it remains unclear whether the high lability of permafrost‐derived DOM can be attributed to intrinsic chemical properties or elevated carbon concentrations. We investigated the dynamics of permafrost DOM from the Qinghai–Tibetan Plateau using both biodegradation and photodegradation experiments. Biodegradation and photodegradation of permafrost‐derived DOM exhibited distinct qualitative preferences for specific chemical groups (i.e., peptide‐like and aromatics, respectively). Notably, reducing the initial concentration of dissolved organic carbon (DOC) by half and a quarter resulted in shifts in biodegradable DOC content from 11.2% to 11.5% and 8.5%, respectively, accompanied by a corresponding decrease in the biodegradation rate from 0.11 to 0.06 and 0.03. This insight highlights the importance of recognizing the interplay between DOM quality and concentration and bears broader significance for our understanding of the fate of permafrost‐derived DOM in natural ecosystems.

Dorsal and Ventral Plumage Coloration Evolve as Distinct Modules with Different Environmental Correlations.

AbstractMany animals exhibit contrast between their dorsal coloration and their ventral coloration. If selection acts differently on dorsal versus ventral coloration, ancestral covariance between these traits should break down, eventually leading to independent modules of trait evolution. Here, we compare the evolution of feather color across body regions for a clade of Australasian songbirds (Meliphagoidea). We find evidence for three modules of covarying color regions. Among these modules, ventral feathers evolve with high lability, evolving at three times the rate of dorsal plumage and 20 times the rate of flight feathers. While both dorsal plumage and ventral plumage are darker in areas with more precipitation and vegetation, we find that dorsal plumage is twice as similar to colors in satellite photos of background substrates. Overall, differential selection on ventral and dorsal colors likely maintains these as distinct modules over evolutionary timescales-a novel explanation for dorsoventral contrast in pigmentation.

The coordination of alkali-metal nickelates to organic π-systems: synthetic, structural and spectroscopic insights.

Low-valent nickelates have recently been shown to be key intermediates in challenging cross-coupling reactions using aryl ethers as electrophiles. Key for the success of these transformations is the activation of the substrate through π-coordination to the nickelate intermediate, however there is still limited knowledge about the fundamental structure and coordination chemistry of these heterobimetallic complexes. Herein, we report the synthesis, structures, and spectroscopic analysis of a diverse family of alkali-metal nickelates derived from phenyl-alkali-metal reagents and Ni(ttt-CDT), where ttt-CDT = trans,trans,trans-1,5,9-cyclododecatriene. The co-complexation of PhLi with Ni(ttt-CDT) was found to yield 1 : 1, 2 : 1 or 4 : 2 lithium nickelates depending on the stoichiometry and reaction conditions employed. The high lability of the ttt-CDT ligand enables facile ligand exchange with an assorted series of organic π-acceptors, ranging from polyaromatic hydrocarbons to ketones, imines and nitriles. For anthracene and phenanthrene, a homologous series of Li, Na and K nickelates could be obtained, which lead to different structural motifs or degrees of aggregation in the solid-state spanning solvated monomers to complex polymeric arrangements. For π-extended systems such as perylene or coronene, competing single-electron-transfer to give the corresponding radical anions was observed, illustrating the highly reducing nature of the alkali-metal nickelates. X-ray crystallographic analysis and NMR spectroscopy of the phenyl-alkali-metal nickelates reveal extreme back-bonding from Ni(0) to the organic π-acceptors due to strong σ-donation from the carbanionic ligands.

Seasonal influenza in children: complications, treatment, prevention (subject publication review).

Aim: To study the specificity of seasonal flu in children, in particular, in young children, as well as treatment, prevention and complications of seasonal flu. Materials and Methods: For the methodological justification of the article, we used the pool of research technologies. Methods of theoretical analysis, system-analytical, comparative methods provided us with the opportunity to characterize the features of influenza incidence in children. Conclusions: A distinctive feature of influenza is the high lability of the genes of the infectious agent. In this regard, it is extremely important to timely update information about new strains of the pathogen, creation of new types of vaccines and antiviral drugs, as well as changes in the course of the disease. Our literature review is intended to improve the medical community.

Fractionation of metals in bottom sediments of St. Petersburg rivers

Based on the method of successive extraction, the forms of heavy metals in the bottom sediments from eight rivers in the central part of St. Petersburg were studied. Watercourses are characterized by a high degree of technogenic pollution, the features of which are determined by the industry specialization of enterprises located on the banks of watercourses. Exchangeable forms, metals bound to carbonates, organic-sulfide (oxidized) fraction, bound to hydrate iron and manganese oxides (reduced) fraction, crystalline (acid) forms, and silicate (residual) forms were extracted from bottom sediment samples. A feature of urban precipitation was the predominance of residual forms and a high proportion of oxidized ones. Based on the methods of multivariate statistics (factorial and dispersion analysis), the technogenic geochemical specialization of different watercourses was established, the industrial and post-industrial (modern) horizons were identified in the section of bottom sediments, and the leading forms of metals were established. Sediments were characterized by a very wide range of total metal content. However, the dependence of the absolute content of metals in different extracts on the total concentration was contained only for Mn, Ni, Co, and Cd. Among the studied metals, the single-phase composition was found by Ba and Sr, which are 85–98% represented by the silicate form. ANOVA analysis of the metal content (without taking into account the residual fraction) showed that the accumulation of Cr, Cu, Zn, Mn, Co, Ni occurs in the oxidized form; for Ba and Pb, acid extraction plays a leading role; for Fe, the maximum concentration was found in oxidized and acidic extracts; for Cd, the exchange and carbonate forms are leading. A series of decrease in the mobility of metals Cd>Zn>Cr>Cu»Ni>Mn»Co>Pb>>Fe>>Sr>Ba indicated a high lability of chalcophile elements and a decrease in mobility in the series siderophiles - lithophiles. An expert assessment of the potential for secondary contamination of metals during bottom cleaning and soil dumping in the Neva Bay was obtained, which was especially significant for Zn, Cu, Cr and Mn.

Impact of residue retention and nutrient management on carbon sequestration, soil biological properties, and yield in multi-ratoon sugarcane

Sequestration of carbon (C) in arable cropping systems is considered one of the potential climate change mitigation strategies. In this context, assessing the potential of sugarcane cropping systems should be a priority, as it leaves substantial amounts of recyclable residues essential for maintaining soil organic carbon (SOC), improving soil health, and strengthening overall resources. We evaluated the impacts of residue retention and nutrient management practices on SOC and its pools, storage, soil biology, and yield in a multi-ratooning sugarcane system. A field experiment was conducted in the split-plot design with residue burning (RB) and residue retention (RR) as the main plot treatments and three nutrient management practices, that is, 25% of the recommended dose of fertilizers (RDF, i.e., 300:150:150 kg of N, P2O5, and K2O kg ha−1, respectively) as basal + 75% through fertigation (N1); 50% of RDF as basal + 50% through fertigation (N2); and 75% of RDF as basal + 25% through fertigation (N3) as subplot treatments in ratoon sugarcane. Soil samples were collected initially and after 6 years of multi-ratooning (one plant and four ratoon crops) from a soil depth of 0–30 cm. The results indicated that RR plots had 21% higher total SOC with 42, 47, 17, and 13% higher very labile, labile, less labile, and non-labile C pools, respectively, than RB plots (P < 0.05). RR also had a higher lability and recalcitrant index than RB. Of the total SOC stock, the contribution of passive pools was higher (72–75%) than active pools. Significantly higher dehydrogenase activity (DHA) (86%), alkaline phosphatase activity (APA) (16%), and ß-glucosidase activity (BGA) (22%) were observed in RR plots as compared to RB plots, whereas for nutrient management practices, it followed the order of N2 > N3> N1. Microbial counts also followed the same trend as that of enzyme activities. Residue retention practices reported higher C sequestration (0.68 Mg C ha−1 yr−1), carbon retention efficiency (37%), and yield (38%) with a potential to reduce GHG emissions by 2.72 Mg CO2 ha−1 yr−1 as compared to traditional practices. Residue retention and 50–75% RDF as basal is recommended for higher soil C retention and soil biology for sustained sugarcane productivity.

Comparative floral development in Mimosa (Fabaceae: Caesalpinioideae) brings new insights into merism lability in the mimosoid clade.

The genus Mimosa L. (Leguminosae; Caesalpinioideae; mimosoid clade), comprising more than 500 species, is an intriguing genus because, like other members of the mimosoid clade, it presents an enormous variation in floral characteristics and high merism lability. Thus, this study aimed to elucidate the floral development and identify which ontogenetic pathways give rise to merism variation and andromonoecy in Mimosa caesalpiniifolia, M. pudica, M. bimucronata, and M. candollei. Floral buds at various stages of development and flowers were collected, fixed, and processed for surface analysis (SEM). The development of the buds is synchronous in the inflorescences. Sepals appear simultaneously as individualized primordia in M. caesalpiniifolia and in reversed unidirectional order in M. bimucronata, with union and formation of an early ring-like calyx. Petal primordia appear in unidirectional order, with a noticeably elliptical shape in M. caesalpiniifolia. The wide merism variation in Mimosa results from the absence of organs from inception in the perianth and androecium whorls: in dimerous, trimerous, or tetramerous flowers, the additional organs primordia to compose the expected pentamerous flowers are not initiated. The haplostemonous androecium of M. pudica results from the absence of antepetalous stamens from inception. In the case of intraspecific variations (instabilities), there is no initiation and subsequent abortion of organs in the events of reduction in merosity. In addition, extra primordia are initiated in supernumerary cases. On the other hand, staminate flowers originate from the abortion of the carpel. Mimosa proved to be an excellent model for studying merism variation. The lability is associated with actinomorphic and rather congested flowers in the inflorescences. Our data, in association with others of previous studies, suggest that the high lability in merism appeared in clades that diverged later in the mimosoid clade. Thus, phylogenetic reconstruction studies are needed for more robust evolutionary inferences. The present investigation of ontogenetic processes was relevant to expand our understanding of floral evolution in the genus Mimosa and shed light on the unstable merism in the mimosoid clade.

Training basketball players technology of of student teams of the humanitarian profile higher education institutions

Background and purpose. At the current stage, the importance of training basketball players during their studies at higher education institutions is growing. After all, it is precisely at the age of 18-25 years, which coincides with the age of studying at the university, that the highest rate of increase in sports achievements of basketball players is observed. But combining sports training with professional development, which requires studying at a university, has difficulties. It is difficult for the coach to take into account the psychological and psychophysiological characteristics of the students of the basketball team. Such features include the properties of the nervous system, its mobility, lability, strength, endurance, as well as the type of thinking based on the predominance of the right or left hemisphere of the brain, that is, imaginative (artistic) or logical (mental).
 Purpose: to develop and experimentally justify the methodology of training basketball teams of humanitarian higher educational institutions, taking into account the psychophysiological capabilities of the players.
 Material and methods. 23 students - players of the national basketball team H.S. Skovoroda Kharkiv National Pedagogical University. Athletes were divided into 2 groups, control (n=12) and experimental (n=11). In the experimental group, a specially developed technology for training basketball players was used, taking into account the peculiarities of the nervous system and the type of thinking of students of humanitarian universities, that is, high mobility and lability and low endurance of the nervous system with a predominance of the artistic type of thinking. The technology included exercises for the development of speed qualities in combination with informational means of influencing the perception of technical and tactical elements in basketball. Research methods: analysis of modern literature, methods of determining the physical and technical level of athletes, methods of determining the level of attention, methods of determining the ability to concentrate and switch attention, methods of statistical analysis.
 Results. In the study, based on the results of the literature analysis, the psychophysiological features of students of humanitarian universities were determined. These features consist in the predominance of mobility and lability of the nervous system over endurance. On the basis of these data, a method of training basketball teams of humanitarian higher educational institutions was developed.
 Special informational methods of influence on the perception of basketball players of humanitarian higher educational institutions of the elements of basketball technique and tactics have been developed. These methods correspond to the imaginative, artistic type of thinking of students of humanitarian universities and the peculiarities of their nervous system - high mobility and lability in combination with a low level of endurance development.
 Conclusions. The method of training basketball players of student teams, based on the psychophysiological characteristics of students of humanitarian universities, is effective for improving the level of special physical fitness of players, as well as the technical and tactical skills of basketball students of humanitarian universities.

Microbial dynamics in soils of the Damma glacier forefield show succession in the functional genetic potential.

Glacier retreat is a visible consequence of climate change worldwide. Although taxonomic change of the soil microbiomes in glacier forefields have been widely documented, how microbial genetic potential changes along succession is little known. Here, we used shotgun metagenomics to analyse whether the soil microbial genetic potential differed between four stages of soil development (SSD) sampled along three transects in the Damma glacier forefield (Switzerland). The SSDs were characterized by an increasing vegetation cover, from barren soil, to biological soil crust, to sparsely vegetated soil and finally to vegetated soil. Results suggested that SSD significantly influenced microbial genetic potential, with the lowest functional diversity surprisingly occurring in the vegetated soils. Overall, carbohydrate metabolism and secondary metabolite biosynthesis genes overrepresented in vegetated soils, which could be partly attributed to plant-soil feedbacks. For C degradation, glycoside hydrolase genes enriched in vegetated soils, while auxiliary activity and carbohydrate esterases genes overrepresented in barren soils, suggested high labile C degradation potential in vegetated, and high recalcitrant C degradation potential in barren soils. For N-cycling, organic N degradation and synthesis genes dominated along succession, and gene families involved in nitrification were overrepresented in barren soils. Our study provides new insights into how the microbial genetic potential changes during soil formation along the Damma glacier forefield.

Tocopherols and associated derivatives track the phytoplanktonic response to evolving pelagic redox conditions spanning Oceanic Anoxic Event 2.

Tocopherols serve a critical role as antioxidants inhibiting lipid peroxidation in photosynthetic organisms, yet are seldom used in geobiological investigations. The ubiquity of tocopherols in all photosynthetic lifeforms is often cited as an impediment to any diagnostic paleoenvironmental potential, while the inability to readily analyze these compounds via conventional methods, such as gas chromatography-mass spectrometry, further diminishes the capacity to serve as useful 'biomarkers'. Here, we analyzed an exceptionally preserved black shale sequence from the Demerara Rise that spans Oceanic Anoxic Event 2 (OAE-2) to reexamine the significance of tocopherols and associated derivatives (i.e. tocol derivatives) in ancient sediments. Tocol derivatives were analyzed via liquid chromatography-quadrupole time-of-flight-mass spectrometry and included tocopherols, a methyltrimethyltridecylchroman, and the first reported detection of tocopherol quinones and methylphytylbenzoquinones in the geologic record. Strong correlations between tocol derivatives were observed over the studied interval. Tocol derivative concentrations and ratios, which normalized tocopherols to potential derivatives, revealed absolute and relative increases in tocopherols as exclusive features of OAE-2 that can be explained by two possible mechanisms related to tocopherol production and preservation. The development of photic zone euxinia during OAE-2 likely forced an upward migration of oxygenic photoautotrophs, increasing oxidative stress that elicited heightened tocopherol biosynthesis. However, shoaling euxinic conditions may have simultaneously acted to enhance tocopherol preservation given the relatively high lability of tocopherols in the water column. Both scenarios could produce the observed stratigraphic distribution of tocol derivatives in this study, although the elevated tocopherol concentrations that define OAE-2 at the Demerara Rise are primarily attributed to enhanced tocopherol production by shoaling phytoplanktonic communities. Thus, the occurrence of tocopherols and associated derivatives in sediments and rocks of marine origin is likely indicative of shallow-water anoxia, tracking the phytoplanktonic response to the abiotic stresses associated with vertical fluctuations in pelagic redox.

Long-term integrated crop-livestock grazing stimulates soil ecosystem carbon flux, increasing subsoil carbon storage in California perennial agroecosystems

The strategic use of ruminant grazing in perennial cropland is steadily increasing throughout Mediterranean perennial agroecosystems. Integrated sheep-vineyard (ISV) management, where small ruminant livestock graze on understory vegetation, is viewed by some practitioners as a feasible transition opportunity to facilitate less petrochemically intensive vineyard understory management. However, our knowledge of soil carbon dynamics associated with grazing in perennial integrated crop-livestock (ICL) agroecosystems is notably limited, especially within Mediterranean climate contexts. Here, we use a series of on-farm paired surveys to assess soil ecosystem habitat and resource conditions related to SOC flux and storage in vineyards utilizing sheep-integration (ISV) and conventional understory management techniques (CONV). Our results show that long-term grazing increased the quantity of active, labile, and soluble carbon (C) within ISV soils, with much higher quantities of microbial biomass carbon (MBC). Vineyard soils with sheep grazing also showed increases in phospholipid fatty acid (PLFA) biomarkers, particularly amongst core functional groups related to decomposition. Soil microbial communities under ISV had higher C mineralization rates as well as higher carbon use-efficiency, as indicated by less CO2-C respired relative to the size of the MBC pool. Whereas inorganic soil nitrogen (N) and phosphorous (P) were also higher under ISV, microbial communities showed distinct metabolic investment strategies related to nutrient acquisition, with lower P-cycling enzyme activity and higher N-cycling enzyme activity. Additionally, ISV resulted in an increase in subsoil SOC storage, including higher quantities of physicochemical stabilization in the mineral-associated organic carbon (MAOC) pool of the deepest measured subsoil layer (30–45 cm). We observed no differences in soil structure indicators between treatments nor differences in the carbon fractions associated with four distinct aggregate size categories. We propose a framework to explain observed shifts in SOC dynamics of perennial ICL systems that include i) deposition of C and nutrient inputs with higher lability and solubility; ii) ruminant-induced decoupling of C from N and P, resulting in increased nutrient bioavailability; and iii) altered soil microbial metabolic strategies with more efficient biomass accumulation. These findings show strong potential of strategically applied ICL grazing to enhance soil functioning and increase SOC storage in Mediterranean perennial agroecosystems.

Synthesis of 1,3-Dienes via Ligand-Enabled Sequential Dehydrogenation of Aliphatic Acids.

1,3-Dienes are common scaffolds in biologically active natural products as well as building blocks for chemical synthesis. Developing efficient methods for the synthesis of diverse 1,3-dienes from simple starting materials is therefore highly desirable. Herein, we report a Pd(II)-catalyzed sequential dehydrogenation reaction of free aliphatic acids via β-methylene C-H activation, which enables one-step synthesis of diverse E,E-1,3-dienes. Free aliphatic acids of varying complexities, including the antiasthmatic drug seratrodast, were found to be compatible with the reported protocol. Considering the high lability of 1,3-dienes and lack of protecting strategies, dehydrogenation of aliphatic acids to reveal 1,3-dienes at the late stage of synthesis offers an appealing strategy for the synthesis of complex molecules containing such motifs.

High lability of global niche and range in the Giant African Snail (Lissachatina fulica): Small niche expansions resulting in large range shifts

As a major source of global change, biological invasions have received increasing attention in past decades. Niche and range dynamics of alien invasive species provide essential evidence for understanding mechanisms underlying biological invasions. However, to our knowledge few relevant studies on mollusks have been reported. Here, from the perspective of climatic suitability, we investigated niche and range shifts of the Giant African Snail (Lissachatina fulica), one of the world’s most invasive mollusks. We observed that, compared with its native counterpart, this invasive snail could survive in environments with wider temperature ranges. The invasive snail showed a wider niche breadth and larger potential range than its native counterpart, and occupied different niche and range positions, indicating its high lability in terms of niche and range. This invasive Giant African Snail did not conform to the niche and range conservatism hypotheses, probably due to the influence of human introductions and niche releasing. Given that large shifts in range size can result from small niche expansions, making niche shifts a more important indicator for biological invasion assessments than range shifts. While most invasive species show low lability in niche space, highly labile niche was observed in the Giant African Snail, indicating that strategies to prevent biological invasions by this invasive mollusk should be prioritized. Our study, to certain extent, could further our understanding on the niche shifts and range dynamics between the invasive mollusks and their native counterparts.

Experimental study of the transformation of 2-aminophenylacetic acid hexafluorosilicate into 2-oxindol under mild conditions

Currently, ammonium hexafluorosilicates are being actively studied as new anti-caries agents, which, according to the results of researches on rats, show a more significant caries-preventive effectiveness compared to sodium fluoride with a simultaneous significant improvement of the biochemical indicators of the dental pulp and the absence of hepatotoxic effects. Previously, we’ve synthesized 2-, 3-, 4-aminophenylacetic acid hexafluorosilicates (2-, 3-, 4-APhHFS); in an attempt to recrystallize the 2-APhHFS salt from ethanol, a red crystalline product was obtained.
 The purpose of the research – considering the potential prospects of 2-, 3-, 4-APhHFS, it is expedient to establish the composition and structure of the recrystallization product of 2-APhHFS. Mass spectra were recorded on MX-1321 and VG 7070 spectrometers (VG Analytical), X-ray structural analysis was carried out on an Xcalibur E diffractometer.
 As follows from the comparison of the external inspection of the original 2-APhHFS and its recrystallization product (RP) samples, they differ significantly: light brown amorphous 2-APhHFS and red crystalline RP. The characteristics of the mass spectra of 2-APhHFS and RP are also different. The structure of RP as 2-oxindole was objectively established by X-ray diffraction data.
 The recrystallization process of 2-APhHFS to obtain 2-oxindole does not require heating of the reaction mixture, i.e., it is carried out under extremely mild conditions. It is possible that it's connected with the participation of the protonated form of 2-aminophenylacetic acid in the composition of 2-APhHFS in chemical transformations.
 Thus, caution should be exercised in experiments with both solutions and, apparently, solid samples of 2-APhHFS during salt purification procedures or other manipulations. The high lability of 2-aminophenylacetic acid hexafluorosilicate limits the possibilities of using standard purification methods (sublimation, recrystallization) for this compound.