Romanian Academy

About: Romanian Academy is a archive organization based out in Bucharest, Romania. It is known for research contribution in the topics: Population & Nonlinear system. The organization has 3662 authors who have published 10491 publications receiving 146447 citations. The organization is also known as: Academia Română & Societatea Literară Română.

Individual-level trait diversity predicts phytoplankton community properties better than species richness or evenness

Abstract: Understanding how microbial diversity influences ecosystem properties is of paramount importance. Cellular traits—which determine responses to the abiotic and biotic environment—may help us rigorously link them. However, our capacity to measure traits in natural communities has thus far been limited. Here we compared the predictive power of trait richness (trait space coverage), evenness (regularity in trait distribution) and divergence (prevalence of extreme phenotypes) derived from individual-based measurements with two species-level metrics (taxonomic richness and evenness) when modelling the productivity of natural phytoplankton communities. Using phytoplankton data obtained from 28 lakes sampled at different spatial and temporal scales, we found that the diversity in individual-level morphophysiological traits strongly improved our ability to predict community resource-use and biomass yield. Trait evenness—the regularity in distribution of individual cells/colonies within the trait space—was the strongest predictor, exhibiting a robust negative relationship across scales. Our study suggests that quantifying individual microbial phenotypes in trait space may help us understand how to link physiology to ecosystem-scale processes. Elucidating the mechanisms scaling individual-level trait variation to microbial community dynamics could there improve our ability to forecast changes in ecosystem properties across environmental gradients.

Hypervalent silicon-based, anionic porous organic polymers with solid microsphere or hollow nanotube morphologies and exceptional capacity for selective adsorption of cationic dyes

Abstract: We report straightforward access to two new anionic porous organic polymers (Si-POPs) based on hexacoordinate [SiO6]2– species and polyimine aromatic linkers which exhibit outstanding capabilities for removal of cationic dyes from contaminated industrial water. These multifunctional materials are stable under air and in water; they were synthesized via solvothermal chemistry exploiting Schiff base formation between tri(protocatechuic aldehyde)-silicate and 4,4′-diaminobiphenyl acid (for Si-POP-1) or 4,4′-diamino-2,2′-stilbenedisulfonic acid (for Si-POP-2). Charge neutrality of the Si-POPs was achieved by [Et3NH]+ cations. The structures were determined by spectroscopic techniques (FT-IR and solid 13C-NMR spectroscopy), while SEM and TEM revealed a micrometer-scale solid sphere morphology for Si-POP-1 and hollow nanometer-sized tubes for Si-POP-2. BET specific surface area determination gave 376 and 234 m2 g−1 for Si-POP-1 and Si-POP-2, respectively. The unprecedented adsorption abilities of these materials for standard cationic dyes such as methylene blue (MB), malachite green (MG), and Basic Blue 7 (BB7) were revealed by studying the effects of system variables such as pH, contact time, temperature and mixed-dye solutions. At 25 °C, the maximum adsorption capacity of Si-POP-1 reached 300.3 mg g−1 for MB and 378.5 mg g−1 for MG, while the performance of Si-POP-2 at the same temperature was substantially higher (3516 mg g−1 for MB and 662 mg g−1 for MG). Furthermore, at 35 °C, the maximum adsorption of MB on Si-POP-2 reached 4098 mg g−1, surpassing the performance of previous adsorbents. It was found that both Si-POP-1 and Si-POP-2 exhibit charge and size-selective adsorption. Thermodynamics studies indicated that the adsorptions were spontaneous and endothermic. A minimal loss of adsorptive capacity of Si-POP-2 (less than 4%) was observed after four cycles, demonstrating an effective reuse of the regenerated POP in discarding MB from effluents. Importantly, this green protocol also allows recovery of the dye retained in the POP. These assets recommend these new hexacoordinate silicate-based adsorbents as viable materials for wastewater remediation by removal of organic dye pollutants affecting nature and public health.

Computing by communication in networks of membranes

Abstract: In this paper we consider networks of membranes which compute by communication only, using symport/antiport rules. Such rules are used both for communication with the environment and for direct communication among membranes. It turns out that, rather surprisingly, networks with a small number of membranes are computationally universal. This is proved both for the case of three membranes where each membrane communicates with each other membrane, and for the case of four membranes consisting of two pairs such that only the membranes within each pair communicate directly. A single pair of communicating membranes can compute the Parikh images of matrix languages. Several open problems are also formulated.

A Descriptive Review on the Prevalence of Gastrointestinal Disturbances and Their Multiple Associations in Autism Spectrum Disorder.

Abstract: Background and Objectives: Gastrointestinal disturbances have been frequently, but not unanimously, reported in autism spectrum disorder (ASD) individuals. Thus, digestive symptoms, such as constipation, diarrhea, abdominal bloating, and pain have been reported to correlate to the various maladaptive behaviors in ASD children, such as irritability, social withdrawal, stereotypy, hyperactivity, and even language regression. In this context, the present study provides an overview on the prevalence of the gastrointestinal (GI) disorders in ASD and the correlation between these and ASD symptoms and comorbidities and subsequently discusses the metabolic and microbiome factors underlying the effects of GI disorders in ASD. Materials and Methods: For our analysis of GI symptoms in children with ASD, we have searched peer-reviewed journals from 2005 to 2017 in PubMed databases that addressed the specificity of GI symptoms in ASD and included correlations of GI and ASD symptoms. The criteria for inclusion were clear quantitative mentioning of GI modifications, GI symptoms correlation with specific ASD symptoms or comorbidities, an appropriate methodology for defining ASD, and larger size samples. For this topic, only studies on human patients and original research were considered. A subsequent search in PubMed databases in journals from 2000 to 2017 we analyzed 13 articles on the mechanisms underlying the impact of GI dysfunctions in ASD, including gut microbial dysbiosis, immune reactivity, genetics, and altered neurotransmitters on the gut–brain axis. Results: In the 18 original research studies that we selected out of an initial 327 studies, despite the different methodology, a predominant 83% highlighted the increased prevalence of GI symptoms in ASD patients. Constipation was most frequently cited, appearing in 12 of the studies (80%), followed by diarrhea reports in eight studies (53%). The association between cognitive and behavioral deficits and GI disorders was suggested in certain groups of ASD individuals. Conclusion: The evidence presented so far by numerous studies seems to indicate that GI dysfunctions are of particular relevance in ASD, underlined by various abnormalities along the nervous connections between the central nervous system and the gut, such as impaired parasympathetic activity and increased endocrine stress response. Sufficiently large size samples and standardized methodology are required for future studies to clarify the complex interactions between GI disturbances and ASD symptoms.

Preparation of core-shell nanospheres of silica-silver : SiO2@Ag

Abstract: We prepared SiO 2 @Ag core–shell nanospheres: silver nanoparticles (∼4 ± 2 nm in diameter) coated silica nanospheres (∼50 ± 10 nm in diameter). The preparation route is a modification of the Stober method, and involves the preparation of homogeneous silica spheres at room temperature, combined with the deposition of silver nanoparticles from Ag + in solution, by using water/ethanol mixtures, tetraethyl-orthosilicate as Si source and silver nitrate as Ag source in a single-pot wet chemical route without an added coupling agent or surface modification, which leads to the formation of core@shell homogeneous nanospheres. We present the preparation and characterization of the SiO 2 @Ag core–shell nanospheres and also of bare silica spheres in the absence of silver, and propose a reaction mechanism for the formation of the core–shell structure.