Distinct Functional Groups Research Articles

Site‐Selective Functionalization of Sila‐Adamantane and Its Ensuing Optical Effects

AbstractThe first syntheses of functionalized sila‐adamantanes via site‐selective reactions are described. Mechanistic inquiry into the isomerization of sila‐adamantane revealed new approaches for installing halides at the 2‐position of the cluster. Meanwhile, isomerization via Lewis acid catalysts with non‐nucleophilic counteranions provided access to sila‐adamantane on the gram‐scale, enabling us to discover strategies for substituting its 1‐, 3‐, 5‐, and 7‐positions with identical or distinct functional groups. Optical absorbance and density functional theory studies show that σ‐withdrawing substituents at the 1‐position strongly perturb optical absorbance in sila‐adamantane, whereas substituents at the exocyclic and 2‐position are optically inert. As silicon diamondoids are atomically precise models for silicon nanocrystals, our findings suggest that passivation at tertiary surface sites carries an outsized impact on the optical properties of surface‐functionalized Si nanocrystals.

Site‐Selective Functionalization of Sila‐Adamantane and Its Ensuing Optical Effects

The first syntheses of functionalized sila-adamantanes via site-selective reactions are described. Mechanistic inquiry into the isomerization of sila-adamantane revealed new approaches for installing halides at the 2-position of the cluster. Meanwhile, isomerization via Lewis acid catalysts with non-nucleophilic counteranions provided access to sila-adamantane on the gram-scale, enabling us to discover strategies for substituting its 1-, 3-, 5-, and 7-positions with identical or distinct functional groups. Optical absorbance and density functional theory studies show that σ-withdrawing substituents at the 1-position strongly perturb optical absorbance in sila-adamantane, whereas substituents at the exocyclic and 2-position are optically inert. As silicon diamondoids are atomically precise models for silicon nanocrystals, our findings suggest that passivation at tertiary surface sites carries an outsized impact on the optical properties of surface-functionalized Si nanocrystals.

Structural and luminescence characteristics of thermally stable Dy3+ doped oxyfluoride strontium zinc borosilicate glasses for photonic device applications

Structural, thermal, and photoluminescence (PL) characteristics of a series of Dy3+ doped Oxyfluoride Strontium Zinc Borosilicate (OFSZBS) glasses have been investigated. The XRD of 1.0 mol% Dy3+ ions doped OFSZBS glass and FT-IR investigations conducted on an un-doped as well as all the Dy3+ ions doped OFSZBS glasses confirm the non-crystalline nature and distinct functional groups present in it respectively. The Differential Scanning Calorimetry (DSC) thermogram recorded for an un-doped OFSZBS glass reveals thermal stability (ΔT) and transition temperature (Tg). The optical band gaps were computed using the Tau'c method. Under 348 nm pumping wavelengths, the Photoluminescence (PL) spectra of the as-synthesized OFSZBSDy glass samples exhibit blue (450 nm), yellow (575 nm), and red (650 nm) color transitions. The PL intensity increases with Dy3+ ions concentration up to 1 mol% and after that intensity decreases due to the concentration quenching effect. The PL decay profiles reported at higher concentrations were best fitted to the Inokuti-Hirayama (I-H) model for s = 6, indicating the energy transfer process as dipole–dipole in nature. The result obtained from the I-H model is in consonance with that of Dexter's theory. At 448 K, the PL intensity is up to 85% of room temperature, indicating that the as-synthesized glasses have exceptional thermal stability. Relatively higher values of quantum efficiency (η), emission cross-sectional area (σse), and probability of radiative transition (AR) observed for 1 mol% Dy3+ ions doped OFSZBS glasses declare their suitability in photonic devices under n-UV/blue pumping wavelength.

Are all auditory sensilla of bushcrickets bimodal? Comment on: R. D. Zhantiev and O. S. Korsunovskaya, Functions of chordotonal sensilla in bushcrickets (Orthoptera, Tettigoniidae); Entomological Review, 2021, vol. 101 (6), pp. 755–766

Detection of sound and substrate vibration is crucial for the survival and reproduction of many animals, particularly insects. Bushcrickets (Orthoptera, Tettigoniidae), developed a large mechanosensory organ complex in their legs to detect such stimuli. As demonstrated by various studies in the past, sensilla in distinct functional groups form specialized vibratory organs (the subgenual organ and the accessory organ), respond sensitively to both vibration and sound (in the intermediate organ [IO]), or mediate hearing (in the crista acustica [CA]; the tympanal hearing organ). In their recent publication, Zhantiev and Korsunovskayaaddressed auditory and vibratory sensitivity in the IOand the CAin two species of bushcrickets, using single-cell recording and staining of sensory neurons from their soma in an isolated foreleg. Their main finding was that not only the IO but also the complete CAcontains bimodal sensilla responding with high sensitivity to both sound and vibration, which would be a true change in the paradigm of how the auditory/vibratory sense in Orthoptera works. In addition, they revealed vibratory tuning of the IOsensilla, which differs largely from that in previous studies. We propose three major experimental causes of such discrepancies: calibration, experiments with isolated legs, and differences in the sites of recording. To judge the causes of these discrepancies more adequately, a detailed comparison of methods and a number of control experiments are needed. This will deepen our understanding of sensory adaptations and specialization of insect mechanosensory organs to stimuli entering the system by different input pathways.

Functional Trajectories and Resilience Among Adults With Advanced Lung Cancer

IntroductionTo evaluate whether and the degree to which patients with advanced NSCLC (aNSCLC) receiving lung cancer treatments will experience functional disability or have resilience and to identify characteristics associated with functional disability. MethodsWe evaluated longitudinal data of patients with aNSCLC receiving treatment in the Beating Lung Cancer in Ohio prospective cohort study. Disability versus resilience in functional status (usual activities, mobility, and self-care) was measured monthly for 8 months using the EuroQol-5D-5L. Data captured included baseline demographics (Eastern Cooperative Oncology Group performance status), comorbidities, cancer and depressive symptoms (Patient Health Questionnaire-9), anxiety (Generalized Anxiety Disorder-7 scale), and cancer stress (impact of events). Group-based latent class trajectory modeling was used to determine clinically distinct functional disability trajectories jointly with attrition probability (death or withdrawal) in the study period. ResultsAmong 207 participants, the mean age was 63.5 years (range: 34–92 y), 58.9% were male, 6.8% were African American or Black, 73.3% were former smokers, and 35% resided in rural areas. At baseline, participants had adenocarcinoma histological subtype (74.9%), 40.3% had brain metastases, and 46.1% had bone metastases. Participants received chemotherapy plus immunotherapy (46.9%), immunotherapy single agent (21.7%), targeted treatments (18.8%), or no treatment (12.6%). Three distinct functional trajectory groups were identified, as follows: none/mild (n = 79, 38.2%), moderate (n = 99, 47.8%), and severe disability (n = 29, 14.0%). Characteristics associated with severe disability included baseline Eastern Cooperative Oncology Group performance status greater than 1, worse dyspnea and pain, and higher Patient Health Questionnaire-9 and Generalized Anxiety Disorder-7 scale scores. At month 8, 95 participants (45.9%) displayed resilience, 11 (5.3%) experienced functional decline, and 69 (33.3%) were deceased. ConclusionsWe identified three distinct functional trajectories among patients with aNSCLC. Risk stratification tools and targeted interventions designed to target these three groups are needed to improve functional resilience and prevent disability.

Optimization of compositional manipulation for hydroxyapatite modified with boron oxide and graphene oxide for medical applications

Bone tissue engineering is the most used technology in recent years for repairing damaged bones. A novel heterogeneous biomaterial is prepared and studied to be suggested as a promising bone substitute biomaterial, based on three different nanoparticles: hydroxyapatite (HAP), boron oxide (B2O3), and graphene oxide (GO) a triple nanocomposite is designed HAP/B2O3/GO. This hybrid scaffold is analyzed with XRD to examine the crystalline structure of HAP/B2O3/GO and shows its crystal planes. Moreover, the interaction between the three nanoparticles and their distinctive active functional groups is illustrated with FTIR analysis. Further, TEM micrographs demonstrate the structural alteration and the uniform incorporation of HAP and B2O3 into GO sheets with an average length of 30 nm and diameter of 6 nm for HAP, and a size of 8 mm for B2O3. Furthermore, SEM micrographs reveal the porous structure of HAP/B2O3/GO with a grain size of 5–10 nm. The maximum roughness average value is obtained by HAP/B2O3/GO which is 11.04 nm. Besides, HAP/B2O3/GO nanocomposite shows the highest cell viability value of 96.1 ± 1.2%. The bacterial toxicity of HAP/B2O3/GO is confirmed with the obtained inhibition zone against Escherichia coli and Staphylococcus aureus of 15.7 ± 1.1 mm and 16.2 ± 0.8 mm respectively. In addition, the hardness of the triple composite is improved showing a maximum value of 3.7 ± 0.3 GPa. Distinctly, the addition of B2O3 to HAP and GO nanosheets alter the morphological properties and enhances the roughness parameters of HAP/B2O3/GO. Besides, HAP/B2O3/GO shows improved porosity, cell viability, and biodegradability. Hence, studying HAP/B2O3/GO nanocomposite with different scans and analyses reveals its porous integrated structure and shows an excellent antibacterial property, so that HAP/B2O3/GO composite can be suggested as a promising bone substitute biomaterial.

Should We Worry About Surficial Dynamics When Assessing Nutrient Cycling in the Groundwater?

The fluxes of water and solutes in the subsurface compartment of the Critical Zone are temporally dynamic and it is unclear how this impacts microbial mediated nutrient cycling in the spatially heterogeneous subsurface. To investigate this, we undertook numerical modeling, simulating the transport in a wide range of spatially heterogeneous domains, and the biogeochemical transformation of organic carbon and nitrogen compounds using a complex microbial community with four (4) distinct functional groups, in water saturated subsurface compartments. We performed a comprehensive uncertainty analysis accounting for varying residence times and spatial heterogeneity. While the aggregated removal of chemical species in the domains over the entire simulation period was approximately the same as that in steady state conditions, the sub-scale temporal variation of microbial biomass and chemical discharge from a domain depended strongly on the interplay of spatial heterogeneity and temporal dynamics of the forcing. We showed that the travel time and the Damköhler number (Da) can be used to predict the temporally varying chemical discharge from a spatially heterogeneous domain. In homogeneous domains, chemical discharge in temporally dynamic conditions could be double of that in the steady state conditions while microbial biomass varied up to 75% of that in steady state conditions. In heterogeneous domains, the interquartile range of uncertainty in chemical discharge in reaction dominated systems (log10Da > 0) was double of that in steady state conditions. However, high heterogeneous domains resulted in outliers where chemical discharge could be as high as 10–20 times of that in steady state conditions in high flow periods. And in transport dominated systems (log10Da < 0), the chemical discharge could be half of that in steady state conditions in unusually low flow conditions. In conclusion, ignoring spatio-temporal heterogeneities in a numerical modeling approach may exacerbate inaccurate estimation of nutrient export and microbial biomass. The results are relevant to long-term field monitoring studies, and for homogeneous soil column-scale experiments investigating the role of temporal dynamics on microbial redox dynamics.

Landscape complexity and functional groups moderate the effect of diversified farming on biodiversity: A global meta-analysis

Homogenisation and intensification of agricultural ecosystems are among the most important threats to biodiversity, linked to declines in pollinators, soil biota and ecosystem functioning. Diversification has been proposed as a way to restore ecosystem functioning in agricultural landscapes. To manage agricultural land for multiple ecosystem functions, evidence is needed of the effect of diversification on functionally distinct taxa. We contribute to closing this knowledge gap through a global meta-analysis of 161 peer-reviewed articles addressing the abundance and richness of six distinct functional groups: autotrophs, decomposers, natural enemies, pests, pollinators, and other. We found diversified farming systems increased overall species richness by 26% on average, relative to simplified farming systems. However, the effect of diversified farming on the overall mean abundance was weak. Our study shows diversified farming systems enhanced the abundance and richness of beneficial species while reducing the abundance of pests (e.g., weeds, herbivores), thus providing benefits for both agricultural production and biodiversity. The positive effect of diversified farming systems on the overall mean species richness was stronger in farms in more simplified landscapes, i.e., those that are further from natural and semi-natural habitats or have a lower proportion of seminatural vegetation in a 1 km radius. Pollinator’s abundance and richness were highest in diversified farming plots located far away from natural and semi-natural habitats. In contrast, proximity to these natural and semi-natural habitats (<250 m) increased the positive effect of diversified farming systems on natural enemies’ abundance, while reducing the number of pests. Our results add to the body of evidence calling for the repurposing of policies, regulations, and international agendas to promote, support and incentivize the adoption of diversified farming practices for supporting biodiversity. Spatial planning of diversification schemes should consider the landscape context of farms to ensure the greatest benefit of intervention.

Green synthesis of NiFe2O4 nanoparticles for the degradation of Methylene Blue, sulfisoxazole and bacterial strains

The existence of toxic organic contaminants, such as dyes, antibiotics and bacteria in water has created a need for an environmentally safe and viable photocatalyst that can be used in the degradation of various pollutants. Thus, herein, nickel ferrite (NiFe2O4) nanoparticles were synthesized using an ecologically-friendly route using Monsonia burkeana (M. Burkeana) plant extracts and calcined at various temperatures. Structural analyses verified the formation of cubic spinel crystalline structures of NiFe2O4 for No-Cal, NiFe2O4 300 °C, NiFe2O4 500 °C and NiFe2O4 700 °C nanoparticles. The FT-IR analysis showed that the M. burkeana plant's distinctive functional groups were incorporated on the synthesized ferrite nanoparticles. The photocatalytic performance of the various calcined NiFe2O4 nanostructured was tested against various pollutants, such as Methylene blue (MB), Sulfisoxazole (SSX) and bacterial strains, E.coli and S.auerus. Among the calcined nanostructures, the NiFe2O4 500 °C disclosed a remarkable photodegradation of 99% and 74% for MB dye and SSX, respectively. Furthermore, NiFe2O4 500 °C demonstrated the highest degradation of 90% and 86% against E.coli and S.aureus, respectively after 120 min of irradiation exposure. Such degradation could be justified by surface defects detected from the photolumiscence and electron spin resonance. The superparamagnetic features of NiFe2O4 500 °C disclosed that it could be magnetically separated from the solution, due to its near-zero coercivity. Therefore, the simplistic separation and recovery of NiFe2O4 500 °C is very promising for its practical applications. Thus, these findings elucidated that it is possible to degrade various pollutants using an environmentally friendly ferrite material.

Strategic Design for Sumanene‐Derived Organic Cathodes with Tailored Redox Activity

AbstractDespite the use of organic macromolecules in durable, high‐performance lithium‐ion battery cathodes, relevant studies are still lacking. Herein, sumanene, a representative macromolecule, and its derivatives are introduced through either individual or combined incorporation of two distinct functional groups, namely carbonyls and cyanides, to understand the effects of the functionalization strategy on their electrochemical redox properties. This computational investigation reveals that the combined incorporation of the two distinct redox‐active sites would synergistically improve the open‐circuit redox potential, ultimately leading to an exceptionally high theoretical performance of a sumanene‐derivative fully functionalized with carbonyl and cyanide. Furthermore, this study enables to draw meaningful conclusions on the three discharging stages, namely the fully charged, ongoing, and fully discharged stages. Clearly, the open‐circuit redox potential of a compound corresponding to the fully charged stage depends on its electron affinity that is dominantly contributed by the charging energy. During the discharging process, the redox potentials of the compounds gradually decrease with the increase in the number of bound Li atoms because of the Li‐induced weakening of its reductive ability owing to the continuous increase in its charging energy, leading to the cooperative contribution of charging and reorganization energies to the redox potential. At the end of the discharging process, the compound loses the cathodic activity with a negative redox potential, primarily owing to a sudden increase in solvation energy.

Early Effects of Fertilizer and Herbicide Reduction on Root-Associated Biota in Oil Palm Plantations

To secure high yield, tropical oil palm plantations are fertilized, and understory vegetation is controlled by chemical clearing with herbicides. These treatments cause a drastic turnover of soil microbes and cause loss of beneficial mycorrhizal fungi. Here, we tested if reduced fertilization and weeding instead of conventional treatments restored beneficial ecological groups associated with roots. We conducted our study one year after the start of the reduced management in large-scale oil palm plantations. We hypothesized that reduced fertilizer application and weeding result in shifts of the root-associated species composition because changes in the management regimes affect belowground biomass and nutrients in soil and roots. Alternatively, we hypothesized that the legacy of massive soil fertilization and herbicide application preclude compositional shifts of root-associated biota within short time periods. We did not find any significant treatment effects on root nutrient contents, root biomass, and nutrients in soil. At the level of species (based on operational taxonomic units obtained by Illumina sequencing) or phyla, no significant effects of reduced management were observed. However, distinct functional groups showed early responses to the treatments: nematodes decreased in response to weeding; yeasts and ectomycorrhizal-multitrophic fungi increased under fertilizer treatments; arbuscular mycorrhizal fungi increased under fertilizer reduction. Since the responsive ecological groups were represented by low sequence abundances, their responses were masked by very high sequence abundances of saprotrophic and pathotrophic fungi. Thus, the composition of the whole root-associated community was unaffected by reduced management. In conclusion, our results show that changes in management regimes start to re-wire critical constituents of soil–plant food webs.

Evidence of weak interaction between ferric iron and extracellular polymeric substances of Acidithiobacillus ferrooxidans

Although ferric iron in extracellular polymeric substances (EPS) was believed to be pivotal in bioleaching, the real existing form of ferric iron in EPS has remained poorly understood. In this study, whole cells of Acidithiobacillus ferrooxidans were used to study the composition and properties of EPS. The components sugars, proteins and uronic acids could be extracted from cells rich in EPS. Four distinct surface functional groups were characterized on the bacterial surfaces by the fitting of titration data. Subsequently, these functional groups were confirmed as carboxyl groups, phosphoryl groups, thiol groups, and amine groups by combining FTIR and XPS. However, with the help of modeling results and FTIR, these functional groups failed to dissociate protons in a strong acidic environment. The protonated functional groups could unlikely complex ferric iron according to the site-specific surface complexation theory. Besides, the isolated EPS could not sharply reduce the concentration of free ferric ions, and the ferric iron could be removed by washing the cell surfaces with HClO4. These results indicate that there is no strong chemical interaction between bacteria and ferric iron. This study suggests a weak interaction of ferric iron with the EPS of A. ferrooxidans, and gives some deeper insight into the microenvironment of EPS.

Reactivity-based screening for natural product discovery.

Natural products have traditionally been a fruitful source of chemical matter that has been developed into novel therapeutics. Actinomycetes and several other bacterial taxa are especially gifted in biosynthesizing natural products. However, many decades of intense bioactivity-based screening led to a large rediscovery problem, rendering industrial natural product discovery pipelines uneconomical. Numerous methods for circumventing the rediscovery problem have been developed, among them various chemistry-focused strategies, including reactivity-based screening. Emerging from the field of chemical proteomics, reactivity-based screening relies on a reactive probe that chemoselectively modifies a functional group of interest in the context of a complex biological sample. Reactivity-based probes for several distinct functional groups have been deployed to discover new polyketide and peptidic natural products. This chapter describes the protocols to conduct a reactivity-based screening campaign, including bacteria cultivation and screening of cellular extracts with phenylglyoxal-, tetrazine-, thiol-, and aminooxy-functionalized probes, which respectively target primary uriedo, electron-rich olefins, Michael acceptors, and reactive carbonyls. In addition, a recent case study is presented that employs reactivity-based screening as a component of a forward genetics screen to identify a previously unknown peptidyl arginine deiminase. We anticipate that these methods will be useful for those interested in discovering natural products that evade detection by traditional, bioassay-guided methods and others who wish to rapidly connect metabolic chemotype with genotype.

Longitudinal functional status trajectories and its predictors among postpartum women with and without maternal morbidities in Northwest Ethiopia: a group based multi-trajectory modelling

IntroductionUnlike physiological recovery, return to full functional status following childbirth takes longer than 6 weeks (42 days) of the traditionally defined postnatal period, and women with maternal morbidity usually require...

Synthesis and Characterization of Silver Nanoparticles as Strong Antimicrobial Agents Using Bacteriocin of A Novel Probiotic Strain of Lactobacillus Pentosus S6 (KU92122)

The goal of this study was to use bacteriocin from a probiotic strain of Lactobacillus pentosus S6 (KU92122) to synthesize innovative strong silver nanoparticles (AgNPs). UV-Vis spectroscopy was used to analyze the synthesized nanoparticles, and the maximum absorbance was found to be approximately 450 nm. AgNPs produced were spherical in shape, with an average size of 50 nm, as validated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Fourier transform infrared spectroscopy (FTIR) was used to confirm the presence of distinct functional groups on the surface of nanoparticles. The positive antibacterial activity of produced silver nanoparticles was tested against multidrug resistant bacteria such as Staphylococcus aureus and Bacillus cereus, as well as challenging plant pathogens such as Aspergillus niger, Pythium aphanidermatum, Fusarium oxysporum, and Phytopthora parasitica with an apparent aim to use these AgNPs with bacteriocins as effective antimicrobial agents that can be employed at broader scale in clinical and biocontrol applications especially in medicine, agriculture and the food processing sectors.

Synthesis and characterisation of yittrium doped cerium oxide nanoparticles and their efficient antibacterial application invitro against gram-positive and gram-negative pathogens

The point of the study is to synthesize Ce1-xYtxO2 (X = 0.00, 0.02, 0.04, 0.06, and 0.08), and to characterize it. A chemical precipitation procedure was used to synthesize the yttrium (Yt) doped cerium oxide (CeO2) powders. Powder X-ray diffraction (XRD) analysis revealed that the phase pure cubic structured CeO2 crystal system exists. The Rietveld refining method has been used to look into the comprehensive structural examination of produced materials. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to examine the surface morphology and elemental content of the produced materials (EDAX). FTIR spectroscopy has revealed the presence of vibrational linkages linked to distinct functional groups. UV–Vis spectroscopy was used to look at the energy gap of synthetic materials.Photoluminescence (PL) analysis was used to investigate the luminescence activity of synthesized materials. Synthesized materials under 380 nm excitation produced a light-green emission at around 516 nm. In addition, the electron density distribution in synthetic materials has been achieved. Furthermore, Pseudomonas aeruginosa and Corynebacterium diphtheria were used to test the antibacterial activity of produced compounds. Hemolysis inquiry was then used to look at the destruction of human red blood cells. The 4% Yt3+ dopant level was shown to be the optimal level of Yt3+ dopant in the CeO2 host lattice in all of the characterization. The current study opens a viable path for developing efficient biomedical materials.

Ecosystem fluxes during drought and recovery in an experimental forest.

Severe droughts endanger ecosystem functioning worldwide. We investigated how drought affects carbon and water fluxes as well as soil-plant-atmosphere interactions by tracing 13CO2 and deep water 2H2O label pulses and volatile organic compounds (VOCs) in an enclosed experimental rainforest. Ecosystem dynamics were driven by different plant functional group responses to drought. Drought-sensitive canopy trees dominated total fluxes but also exhibited the strongest response to topsoil drying. Although all canopy-forming trees had access to deep water, these reserves were spared until late in the drought. Belowground carbon transport was slowed, yet allocation of fresh carbon to VOCs remained high. Atmospheric VOC composition reflected increasing stress responses and dynamic soil-plant-atmosphere interactions, potentially affecting atmospheric chemistry and climate feedbacks. These interactions and distinct functional group strategies thus modulate drought impacts and ecosystem susceptibility to climate change.

Glycerol‐derived solvents containing two or three distinct functional groups enabled by trifluoroethyl glycidyl ether

AbstractConversion of epichlorohydrin to glycidyl ethers creates versatile precursors that can be transformed into a variety of molecular species with glycerol skeletons, enabling the design of molecules with highly tailored functionalities. The synthesis of 2,2,2‐trifluoroethyl glycidyl ether (TFGE, IUPAC name: 2‐[(2,2,2‐trifluoroethoxy)methyl]oxirane, CAS# 1535‐91‐7) was optimized to provide high yield/selectivity and good “green metrics.” TFGE was then used as a platform molecule in the synthesis of asymmetric glycerol 1,3‐diether‐2‐alcohol derivatives, which were subsequently transformed to 1,2,3‐triethers or 1,3‐diether‐2‐ketones. The density, viscosity, and CO2 solubility of each molecule were measured and compared with those of other glycerol‐derived compounds as well as compounds with similar functional groups. Furthermore, quantum chemical calculations were performed to understand the structure–property–performance relationships of these molecules for CO2 absorption. Based on the results in this work, we foresee that TFGE (and similar glycidyl ethers) would offer great flexibility in molecular design of green solvents and precursors to more complex compounds.

Latitudinal gradient of copepod functional diversity in the South Atlantic Ocean

There is a growing consensus for assessing the multifaceted marine biodiversity by analyzing morphological taxonomy and biological traits to link the biodiversity and ecosystem functioning relationships (BEF) to environmental variability. We applied taxonomic and functional diversity indices to relate copepod biodiversity with ecosystem functioning along different biogeographic zones from the Southwestern Atlantic to the Southern Ocean. To assess the link between functional traits and environmental gradients, we clustered 94 species into functional groups based on the combination of five functional traits. Taxonomic and functional diversity showed a linear decreasing trend along the latitudinal gradient. Species richness peaked at the subtropical latitude (∼30°S), while the functional richness was similar from the tropical up to the temperate region (∼45°S), which hosted on average 70% of the total pool of species, and dropped to only 16% in polar waters. We found that small- and medium-bodied broadcasting, large cruising carnivorous and detritivorous copepods contributed mostly to the larger functional space in tropical and subtropical zones. In turn, dominant copepod species with contrasting traits enhanced the functional divergence and decreased functional evenness poleward. Our results indicate that distinct copepod functional groups with specific environmental preferences are influenced by ecological mechanisms that promote functional richness through complementary resource use and niche partitioning. These findings highlight the relationship between species diversity and ecosystem functioning, which might contribute to ecosystem stability and resilience along environmental gradients.

Antibacterial activity and characteristics of silver nanoparticles biosynthesized from Carduus crispus

In recent years’ synthesis of metal nanoparticle using plants has been extensively studied and recognized as a non-toxic and efficient method applicable in biomedical field. The aim of this study is to investigate the role of different parts of medical plant Carduus crispus on synthesizing silver nanoparticles and characterize the produced nanoparticle. Our study showed that silver nanoparticles (AgNP) synthesized via whole plant extract exhibited a blue shift in absorption spectra with increased optical density, which correlates to a high yield and small size. Also, the results of zeta potential, X-ray diffraction, photon cross-correlation spectroscopy analysis showed the surface charge of − 54.29 ± 4.96 mV (AgNP-S), − 42.64 ± 3.762 mV (AgNP-F), − 46.02 ± 4.17 mV (AgNP-W), the crystallite size of 36 nm (AgNP-S), 13 nm (AgNP-F), 14 nm (AgNP-W) with face-centered cubic structure and average grain sizes of 145.1 nm, 22.5 nm and 99.6 nm. Another important characteristic, such as elemental composition and constituent capping agent has been determined by energy-dispersive X-ray spectroscopy and Fourier transform infrared. The silver nanoparticles were composed of ~ 80% Ag, ~ 15% K, and ~ 7.5% Ca (or ~ 2.8% P) elements. Moreover, the results of the FTIR measurement suggested that the distinct functional groups present in both AgNP-S and AgNP-F were found in AgNP-W. The atomic force microscopy analysis revealed that AgNP-S, AgNP-F and AgNP-W had sizes of 131 nm, 33 nm and 70 nm respectively. In addition, the biosynthesized silver nanoparticles were evaluated for their cytotoxicity and antibacterial activity. At 17 µg/ml concentration, AgNP-S, AgNP-F and AgNP-W showed very low toxicity on HepG2 cell line but also high antibacterial activity. The silver nanoparticles showed antibacterial activity on both gram-negative bacterium Escherichia coli (5.5 ± 0.2 mm to 6.5 ± 0.3 mm) and gram-positive bacterium Micrococcus luteus (7 ± 0.4 mm to 7.7 ± 0.5 mm). Our study is meaningful as a first observation indicating the possibility of using special plant organs to control the characteristics of nanoparticles.