Related Functional Groups Research Articles

Enhanced hydrolysis of spiramycin in aqueous solution using SiO2/SO3H

Abstract Sulfonated silicon dioxide (SiO2/SO3H) solid acids were synthesized and they were characterized and used for spiramycin hydrolysis pretreatment of antibiotic wastewater. Results show that the spiramycin removal effect rankings are as follows: SiO2/SO3H > SiO2 (pH = 3 or so) > control group. A first-order model was used to reflect the hydrolytic kinetics. The hydrolysis rate of the SiO2/SO3H solid acid calcined at 600°C is the highest, up to 3.59×10−2 (k). The performance of SiO2/SO3H is in positive correlation with the total acidity, which was determined by using the n-butylamine titration method. This hydrolytic method eliminates the need for the on-site handling of hazardous and corrosive mineral acids. As an attractive selective catalytic pretreatment method, it is targeted at removing related functional groups from antibiotics to reduce the inhibitory effect and allow antibiotic wastewater to further be easily biologically treated.

Traits and trails: Guild-specific effects of forest paths on bat activity

Human activities can substantially alter forest structure, consequently affecting forest animal communities. An important effect on bat behavior is given by canopy discontinuities like clearings or trails: while the former act as foraging sites, the latter are known to be used by bats to move inside the forest. For this reason, we can expect trails to have a strong influence on bat activity, with differences determined by the species' flying abilities. Here we assess the impact of trails on a local bat community by quantifying the effect of trails’ characteristics on the activity of bat species in relation to their wing morphology. We collected paired acoustic data and environmental variables along trails and in internal areas of a forest in central Italy. We modelled the activity levels of three bat guilds differing in wing morphology and identified the species mostly responsible for the observed compositional dissimilarity in between trails and internal zones by adopting a multivariate approach. Trail width and tree’s diameter were the main drivers of the observed differences between bat activity along trails and internal areas, but their effect differed among bat guilds. Edge and open-space foragers increased their activity along wider trails, while closed-space foragers showed an opposite trend; the latter also avoid trails in favor of internal areas especially when trees are larger. Four species yielded a significant contribution to the dissimilarity in activity levels between trails and internal areas, and namely Pipistrellus pipistrellus, Nyctalus noctula, Miniopterus schreibersii and Barbastella barbastellus. Our results show a clear effect of forest trails on bat activity, highlighting differences across functional groups in relation to trail characteristics. Furthermore, within guilds, not all species respond with the same intensity, suggesting differences in how different species are attracted to linear features and forest gaps. Overall, our results depict a complex interaction between forest trails and bat activity, suggesting that structural changes in forests can trigger diverse responses in bats. Future research on the topic may focus on assessing how such effects can affect bat communities at the landscape scale and longer time-scales.

Ferric citrate enhanced bioreduction of Cr(VI) by Bacillus cereus RCr in aqueous solutions: reduction performance and mechanisms.

The bioreduction characteristics and mechanisms of Cr(VI) onto Bacillus cereus RCr enhanced by ferric citrate were investigated. The optimum conditions were initial pH 9, temperature 40°C, inoculation amount 4%, and glucose 3g/L, respectively. The addition of 1.5g/L ferric citrate increased the average reduction rate from 120.43 to 220.61mg/(L∙h) compared with the control (without ferric citrate). The binding capacity of Cr(III) on the cell surface increased to 21%, in which the precipitates were mainly CrO(OH), Cr2O3, and FeCr2O4. Cell membrane was the main site of reduction, related important functional groups: - COOH, C-H, - NH2, C = C, and P-O. Fe(III) increased the yield of NADH and cytochrome c by approximately 48.51% and 68.63%, which significantly facilitated the electron generation and electron transfer, thus increasing the amount of electrons in the bioreduction of heavy metals by an average of 110%. Among the electrons obtained by Cr(VI), the proportion of indirect reduction mediated by Fe(III)/Fe(II) shuttle was 62% on average, whereas direct reduction mediated by reductase was 38%. These results may provide insights into the bioreduction process by bacteria enhanced by Fe(III) for detoxification of heavy metals with multiple valences, as an important step towards improving microbial remediation.

Examination of in situ and ex situ catalytic fast pyrolysis and liquid fractionation utilizing a free-fall reactor

This study examines biomass valorization through thermochemical conversion by an integrated catalytic fast pyrolysis process with liquid fractionation using a free-fall reactor, γ-alumina, as a catalyst and methanol for direct quenching. The novelty lies within the process intensification (i.e., a single-step conversion and fractionation pathway) to improve pyrolysis oil yield and quality. In particular, the conversion bioprocess utilizes in situ or ex situ catalytic free-fall fast pyrolysis reactors at 550°C and 10–15 psi to produce pyrolysis oil and char (bio-oil and biochar) from pinewood feedstocks. The results from the gas chromatography–mass spectrometry show that the main volatile fractions of bio-oil compounds are levoglucosan, furfural, hydroxy acetone, methyl acetate, and catechol. The electrospray ionization–mass spectrometry results determine the average molar mass, revealing improved cracking, thermal treatment, and fraction stabilization. The Fourier transform infrared spectroscopy and thermal aging provide insight into the change in functional groups in relation to experimental parameters. The outcomes indicate that γ-alumina successfully decreased acidic compounds and increased esters and phenolic content in the bio-oil. The bio-oil produced from the ex situ catalytic pyrolysis also shows the highest liquid yield (~41%), high phenolic content, and thermally stable properties. The in situ catalytic pyrolysis exhibits lower yields but favors high ketone formation. Fractions condensed in methanol exhibit the highest thermal stability and esterification potential; however, they still possess relatively high amounts of acidic compounds. It is concluded that ex situ catalytic pyrolysis, using γ-alumina catalyst and fractionation with methanol, can improve conversion reactions, particularly bio-oil quality, yield, and thermal stability.

Novel insights into the mechanism of dynamic changes in microstructure and physicochemical properties of corn straw pretreated by ball milling and feasibility analysis of anaerobic digestion

In this study, the effects of Ball milling (BM) pretreatment (0–240 min) on the microstructure, physicochemical properties and subsequent methanogenesis performance of corn straw (CS) were explored, and the feasibility analysis was carried out. The results showed that BM pretreatment destroyed the dense structure of the CS, and the particle size was significantly reduced (D50: 13.85 μm), transforming it into a cell-scale granular form. The number of mesopores increased, the pore volume (PV) (0.032 cm3/g) and specific surface area (SSA) (4.738 m2/g) considerably increased, and the water-absorbent property was improved. The crystalline order of cellulose was disrupted and the crystallinity (CrI) (8.61 %) and crystal size (CrS) (3.37) were remarkably reduced. The cross-links between lignocelluloses were broken, and the relative content and functional groups did not alter obviously. The bulk density (BD), repose angle (RA) and slip angle (SA) dramatically increased. As a result, CS was more readily accessible, attached and utilized by microorganisms and enzymes, causing the hydrolysis and acidification of AD to be greatly facilitated. Compared with the untreated group, the cumulative methane production (CMP) increased by 35.83 %–101.97 %, and the lag phase time (λ) was shortened by 33.04 %–71.17 %. The results of redundancy analysis, Pearson analysis and Mantel test showed that BM pretreatment affects the process of AD by changing the physicochemical factors of CS. The normalization analysis showed that particle size (D90) and BD can be used as direct indicators to evaluate the performance of AD and predict the threshold of biodegradation of CS. Energy analysis and energy conversion assessment showed that BM is a green and efficient AD pretreatment strategy. This result provides a theoretical basis for the industrial application of BM pretreatment towards more energy-efficient and sustainable development.

Ammonia gas adsorption study using copper impregnated on mesoporous activated carbon from seaweed waste for indoor air purification

Ammonia (NH3), as a toxic gas, has negative impacts on human health even at low concentration, especially in narrowed spaces. In this study, activated carbon was synthesized from seaweed waste and copper was loaded on its surface (Cu/AC filter) to prepare a cost-effective NH3 adsorbent. Pyrolysis (carbonization) temperature can significantly affect the texture properties of activated carbon, and the best activated carbon sample with BET of 1114 m2/g was obtained through pyrolysis at 500 °C followed by KOH-activation at 750 °C. Different from other lignocellulosic biomass-based activated carbons (mainly microporous structure), the prepared algae-based activated carbons mainly have a mesoporous structure (pore size: 7.0–9.0 nm). Copper-impregnation significantly changed the surface chemistry of activated carbon, thereby greatly increasing the NH3 adsorption capacity (max: 128.6 mg/g). The adsorption performance was primarily determined by chemical adsorption (caused by copper impregnation and related inherent functional groups, including O–H, C–H, O–Si–O and SiO–H), followed by physical adsorption (caused by BET). Isotherm studies indicated that NH3 adsorption on Cu/AC filter followed the Langmuir model, whereas the adsorption kinetics followed the pseudo-second-order model. Furthermore, the adsorption mechanism was controlled by intraparticle diffusion model with initial adsorption behavior. This can be attributed to the mesoporous structures of activated carbon, consequently dramatically improving the diffusion efficiency. In addition, the Cu/AC filter showed good regeneration performance, as it can still remain above 90 % after 5 cycles. Finally, this study demonstrated that the seaweed waste is a good precursor for activation carbon and has great potential as excellent NH3 adsorbent for indoor air purification.

Antibacterial and sunlight-driven photocatalytic activity of graphene oxide conjugated CeO2 nanoparticles

This work focuses on the structural, morphological, optical, photocatalytic, antibacterial properties of pure CeO2 nanoparticles (NPs) and graphene oxide (GO) based CeO2 nanocomposites (GO-1/CeO2, GO-5/CeO2, GO-10/CeO2, GO-15/CeO2), synthesized using the sol–gel auto-combustion and subsequent sonication method, respectively. The single-phase cubic structure of CeO2 NPs was confirmed by Rietveld refined XRD, HRTEM, FTIR and Raman spectroscopy. The average crystallite size was calculated using Debye Scherrer formula and found to increase from 20 to 25 nm for CeO2 to GO-15/CeO2 samples, respectively. The related functional groups were observed from Fourier transform infrared (FTIR) spectroscopy, consistent with the outcomes of Raman spectroscopy. The optical band gap of each sample was calculated by using a Tauc plot, which was observed to decrease from 2.8 to 1.68 eV. The valence state of Ce (Ce3+ and Ce4+) was verified using X-ray photoelectron spectroscopy (XPS) for CeO2 and GO-10/CeO2. The poisonous methylene blue (MB) dye was used to evaluate the photocatalytic activity of each sample in direct sunlight. The GO-15/CeO2 nanocomposite showed the highest photocatalytic activity with rate constant (0.01633 min–1), and it degraded the MB dye molecules by 100% within 120 min. The high photocatalytic activity of this material for degrading MB dye establishes it as an outstanding candidate for wastewater treatment. Further, these nanocomposites also demonstrated excellent antimicrobial activity against Pseudomonas aeruginosa PAO1.

Effective solid–solid and microwave-assisted formation of folic acid@titanium oxide nanoparticles for enhanced batch adsorptive uptake of toxic Cd(II) and Cu(II) pollutants

Synthesis of complicated multi-constituent nanocomposites for adsorption, removal and photocatalytic decomposition of miscellaneous pollutants is a tedious process with respect to the cost of synthesis, methodology and characterization of the produced materials. To find out a simple, short, and direct approach for preparation of an efficient nanomaterial from only two components is a challenging target. Therefore, it is aimed in this investigation to design and generate a potential nanosorbent by only combination of folic acid (Fol-Ac) with titanium oxide nanoparticles (TiO2NPs) via simple solid–solid and microwave-assisted formation of a novel Fol-Ac@TiO2NPs nanosorbent in less than 15 min. The assembled nanosorbent was confirmed by determination of the surface coverage using thermal gravimetric analysis 187.4 mg/g (425.6 µmol g−1), homogenous particles distribution with average particle size (56.92–96.74 nm) based on the TEM imaging. The surface was loaded with several effective and related functional groups to Fol-Ac and TiO2NPs as detected from the FT-IR analysis. The characterized Fol-Ac@TiO2NPs was then used as a novel nanosorbent to capture Cd(II) as a highly toxic divalent metal ion and Cu(II) as a moderately toxic ion via batch mode under the contribution of numerous experimental parameters. Zero charge point of Fol-Ac@TiO2NPs was identified at pHPZC = 6.6 to match with the optimum capture at pH 6.0–7.0 for both Cd(II) plus Cu(II) pollutants. Other parameters as reaction time and temperature as well as metal concentration were also performed and modeled to characterize the possible mechanisms via evaluation of the kinetic, thermodynamic and adsorption isotherm investigations, respectively. Fol-Ac@TiO2NPs nanosorbent was efficiently recycled providing 96.67–97.03 % and 91.34–92.47 % stability after the first and fifth cycles, respectively. Moreover, the efficient usage of Fol-Ac@TiO2NPs for uptake of Cd(II) plus Cu(II) pollutants from contaminated water samples was successfully performed providing 98.32–83.97 % and 93.45–83.39 %, respectively.

Synthesis and characterization of polydopamine-coated graphene oxide as a multifunctional filler for high-efficiency CO2 separation from flue gas

ABSTRACT In the separation of CO2 from flue gas by membrane technology, the development of high permeability and selectivity, environmentally friendly and inherent merit materials play a vital role in efficient membrane processes. For this purpose, chemically active polydopamine (PDA) was successfully synthesized by solution-oxidation method and used in the functionalization and modification of graphene oxide (GO) and GO-polyethylene glycol (PEG) nanomaterial as bio-fillers were incorporated into polyethersulfone (PES) membrane as the basis of the fabricated mixed membrane matrix (MMM). The chemical, physical, thermal behavior and crystallographic structure of bio-fillers and membranes were studied by several analyses. The related functional groups are successfully obtained during the three steps of synthesis, including PEG-GO, PDA-PEG-GO and PDA-GO synthesis. The separation performance of the synthesized-MMM for 30% CO2/70% N2 gas mixture was studied, which resulted to the selectivity of 577.8 and permeability of 416.05 Barrer for PES-PDA-PEG-GO membrane under humidified condition. As a case study, the separation performance of MMM was evaluated for CO2 separation from a typical flue gas that resulted in a selectivity of 339.56 and permeability of 237.5 Barrer. According to the results obtained from a typical flue, the synthesized membrane has an acceptable potential for CO2 separation and industrial uses.

Mechanistic insights on C(acyl)-N functionalisation mediated by late transition metals.

The carboxamide functional group has a privileged role in organic and biological chemistry due to its prevalence and utility across synthetic and natural products. Due to nN → π*CO delocalisation, amides and related functional groups are typically kinetically resistant to degradation. Nonetheless, over the past decade, transition metal catalysis has transformed our ability to utilise molecules featuring C(acyl)-N units as reactants. Alongside the burgeoning catalytic applications ranging from COx utilisation to small molecule synthesis, elucidation of the underlying mechanisms remains a critical ongoing effort. Herein, we aggregate and analyse current understanding of the mechanisms for C(acyl)-N functionalisation of amides and related functional groups with a focus on recent developments involving mechanisms unique to the late transition metals. Discussion is organized around three general mechanistic manifolds: redox-neutral mechanisms, 2e- redox-cycling mechanisms, and mechanisms involving 1e- redox steps. For each class, we focus on reactions that directly involve a transition metal mediator/catalyst in the C(acyl)-N cleavage step. We conclude with an outlook on the outstanding ambiguities and opportunities for innovation.

Moving towards a continuous health care system—payment reform for post-acute care in Changsha City Of China

Introduction: As an integral component of a healthcare system，PAC is not fully developed in China largely attributing to the lack of sound medical insurance coverage and payment for PAC . Changsha City in the middle-south of China draws on international experience to carry out the value-based payment reform for post-acute rehablitation, in order to facilitate the development of rehablitative system and promote the continuity and integration of current health care system. 
 Practice change implementation: According to the characteristics and rehabilitation intensity of inpatients, rehabilitation treatment is divided into two stages: recovery stage and chronic stage. For each stage, different patient classification systems are applied. For recovery phase Functional-Related Groups（FRGs）,a case based payment system is established locally. For chronic phase, payment is made on per-diem basis, and Patient-Driven Chronic Rehabilitation Groups (PDCRG) are applied as casemix groups. The adapted version of International Classification of Functioning, Disability and Health(ICF) scale is used to collect patient data as well as measure their functional gain, which enables the implementation of value-based payment. 
 Aim and theory of change: The pilot reform is to support the effective and quality delivery of rehabilitation services, promote the development of PAC system, and push forward the value-based payment of the medical insurance.
 Targeted population and stakeholders: ·Inpatients with intensive or chronic rehabilitation needs in Changsha City
 ·Rehabilitation service providers (including general hospitals, public and private rehabilitation specialist hospitals and other facilities providing medical rehabilitation services）in Changsha City
 ·Social Medical Insurance Department of Changsha City
 Timeline: The payment policy was introduced in Jun. 2022 and the development is ongoing. 
 Highlights: The key outcomes, impact and innovation include:
 ·Continuous rehabilitation: recovery stage and chronic stage, with acute care before and long-term care after
 ·The refinement of ICF assessment scale to local practice and the development of PAC insurance information system based on the assessment
 ·Value-based payment: provide a method to measure the functional gain of rehabilitation inpatients and link hospital payment to patient outcomes
 ·Offer practical experience for reform of medical insurance payment mode of rehabilitation
 Sustainability: ·The proposed mode stimulates the development of rehabilitation care services, meanwhile, decreases the burden on the medical and long-term care systems
 ·As a supplement of other payment modes, value-based payment mode fills the gap of rehabilitation medical insurance and supports integration of medical services.
 Transfer-ability: Nowadays, China has been pushing ahead with the payment reform of acute hospitalization and developing long-term care insurance for disabled elderly. The Value-based payment model for PAC could reliably classify the needs of rehabilitation inpatients, promoting the development of PAC system. There is significant potential for the model to be replicated.
 Conclusions (comprising key findings, discussion and lessons learned): Aimed at building a sound payment system for post-acute rehabilitaion, the payment reform for PAC in Changsha put forward a value-oriented payment model based mainly on patients’ functional conditions and classified rehabilitative patients into two stages. In the future, the criteria of the two stages and the referral mechanisms in the system need to be further explored and established.

AMEND: active module identification using experimental data and network diffusion

BackgroundMolecular interaction networks have become an important tool in providing context to the results of various omics experiments. For example, by integrating transcriptomic data and protein–protein interaction (PPI) networks, one can better understand how the altered expression of several genes are related with one another. The challenge then becomes how to determine, in the context of the interaction network, the subset(s) of genes that best captures the main mechanisms underlying the experimental conditions. Different algorithms have been developed to address this challenge, each with specific biological questions in mind. One emerging area of interest is to determine which genes are equivalently or inversely changed between different experiments. The equivalent change index (ECI) is a recently proposed metric that measures the extent to which a gene is equivalently or inversely regulated between two experiments. The goal of this work is to develop an algorithm that makes use of the ECI and powerful network analysis techniques to identify a connected subset of genes that are highly relevant to the experimental conditions.ResultsTo address the above goal, we developed a method called Active Module identification using Experimental data and Network Diffusion (AMEND). The AMEND algorithm is designed to find a subset of connected genes in a PPI network that have large experimental values. It makes use of random walk with restart to create gene weights, and a heuristic solution to the Maximum-weight Connected Subgraph problem using these weights. This is performed iteratively until an optimal subnetwork (i.e., active module) is found. AMEND was compared to two current methods, NetCore and DOMINO, using two gene expression datasets.ConclusionThe AMEND algorithm is an effective, fast, and easy-to-use method for identifying network-based active modules. It returned connected subnetworks with the largest median ECI by magnitude, capturing distinct but related functional groups of genes. Code is freely available at https://github.com/samboyd0/AMEND.

Myeloid lineage cells evince distinct steady-state level of certain gene groups in dependence on hereditary angioedema severity.

Hereditary angioedema (HAE) is a rare genetic disorder with variable expressivity even in carriers of the same underlying genetic defect, suggesting other genetic and epigenetic factors participate in modifying HAE severity. Recent knowledge indicates the role of immune cells in several aspects of HAE pathogenesis, which makes monocytes and macrophages candidates to mediate these effects. Here we combined a search for HAE phenotype modifying gene variants with the characterization of selected genes' mRNA levels in monocyte and macrophages in a symptom-free period. While no such gene variant was found to be associated with a more severe or milder disease, patients revealed a higher number of dysregulated genes and their expression profile was significantly altered, which was typically manifested by changes in individual gene expression or by strengthened or weakened relations in mutually co-expressed gene groups, depending on HAE severity. SERPING1 showed decreased expression in HAE-C1INH patients, but this effect was significant only in patients carrying mutations supposedly activating nonsense-mediated decay. Pro-inflammatory CXC chemokine superfamily members CXCL8, 10 and 11 were downregulated, while other genes such as FCGR1A, or long non-coding RNA NEAT1 were upregulated in patients. Co-expression within some gene groups (such as an NF-kappaB function related group) was strengthened in patients with a severe and/or mild course compared to controls. All these findings show that transcript levels in myeloid cells achieve different activation or depression levels in HAE-C1INH patients than in healthy controls and/or based on disease severity and could participate in determining the HAE phenotype.

Valorization of waste cassava peel into biochar: An alternative to electrically-powered process

Cassava production and consumption in its raw or processed form have experienced a rise in recent times globally, with Nigeria being the major producer of cassava in the world. However, the increased consumption of this crop has resulted in an increase in its peels, which if not properly disposed of or recycled, would burden the environment. Previous studies have only been able to engage electrically-powered reactors for the thermochemical conversion of these peels, which is a challenge as these reactors cannot be used in regions with an insufficient supply of electricity. In this study, the authors utilized a top-lit updraft reactor with retort heating for the conversion of waste cassava peels into biochar. The reactor, which is relatively cheap, simple to use, and environmentally friendly and modified for biochar production, is biomass-powered. The carbonization process, which lasted for 160 minutes, obtained a peak reactor temperature of 338 ℃, and gave rise to a biochar yield of 55.13%. FTIR analysis revealed that the cassava peel biochar consists of similar functional groups in relation to its precursor, but consists of more oxygenated functional groups. The BET surface area and BJH pore diameter of the biochar were obtained to be 319.784 m2/g and 2.447 nm, respectively. EDX analysis showed the biochar is majorly made up of carbon (56.93%) and silver (22.97%). SEM micrographs revealed that the biochar has a rough and porous surface. The DTA/TGA results showed that the carbonization process improved the thermal efficiency of the cassava peel material.

Effects of calcination temperatures on structural, functional, morphological, and magnetic properties of strontium ferrite (SrFe2O4) nanoparticles

In this proposed work, the strontium ferrite (SrFe2O4) nanoparticles were successfully synthesized in the presence of strontium nitrate (Sr (NO3)2) and ferric nitrate (Fe (NO3).9H2O) as primary sources by using chemical co-precipitation method. The prepared powders were kept different calcinations temperature (650, 750 and 850 ​°C) and characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM) techniques. The XRD patterns demonstrated the cubic and orthorhombic phase of spinel formation and FTIR transmittance spectra confirmed the presence of strontium ferrite related molecular functional groups. Further, SEM micrograph showed spherical nanoparticles with less agglomerated structure. VSM studies revealed the hard magnetic properties with the highest saturation magnetization (Ms), remanent magnetization (Mr) and coercivity (Hc) of 22.17 emu/g, 11.807 emu/g and 5662.6 ​Oe respectively by VSM.

Knowledge graph-enhanced molecular contrastive learning with functional prompt

Deep learning models can accurately predict molecular properties and help making the search for potential drug candidates faster and more efficient. Many existing methods are purely data driven, focusing on exploiting the intrinsic topology and construction rules of molecules without any chemical prior information. The high data dependency makes them difficult to generalize to a wider chemical space and leads to a lack of interpretability of predictions. Here, to address this issue, we introduce a chemical element-oriented knowledge graph to summarize the basic knowledge of elements and their closely related functional groups. We further propose a method for knowledge graph-enhanced molecular contrastive learning with functional prompt (KANO), exploiting external fundamental domain knowledge in both pre-training and fine-tuning. Specifically, with element-oriented knowledge graph as a prior, we first design an element-guided graph augmentation in contrastive-based pre-training to explore microscopic atomic associations without violating molecular semantics. Then, we learn functional prompts in fine-tuning to evoke the downstream task-related knowledge acquired by the pre-trained model. Extensive experiments show that KANO outperforms state-of-the-art baselines on 14 molecular property prediction datasets and provides chemically sound explanations for its predictions. This work contributes to more efficient drug design by offering a high-quality knowledge prior, interpretable molecular representation and superior prediction performance.

Tropical lacustrine sediment microbial community response to an extreme El Niño event

Salinity can influence microbial communities and related functional groups in lacustrine sediments, but few studies have examined temporal variability in salinity and associated changes in lacustrine microbial communities and functional groups. To better understand how microbial communities and functional groups respond to salinity, we examined geochemistry and functional gene amplicon sequence data collected from 13 lakes located in Kiritimati, Republic of Kiribati (2° N, 157° W) in July 2014 and June 2019, dates which bracket the very large El Niño event of 2015–2016 and a period of extremely high precipitation rates. Lake water salinity values in 2019 were significantly reduced and covaried with ecological distances between microbial samples. Specifically, phylum- and family-level results indicate that more halophilic microorganisms occurred in 2014 samples, whereas more mesohaline, marine, or halotolerant microorganisms were detected in 2019 samples. Functional Annotation of Prokaryotic Taxa (FAPROTAX) and functional gene results (nifH, nrfA, aprA) suggest that salinity influences the relative abundance of key functional groups (chemoheterotrophs, phototrophs, nitrogen fixers, denitrifiers, sulfate reducers), as well as the microbial diversity within functional groups. Accordingly, we conclude that microbial community and functional gene groups in the lacustrine sediments of Kiritimati show dynamic changes and adaptations to the fluctuations in salinity driven by the El Niño-Southern Oscillation.

Studies on competitive adsorption characteristics of bisphenol A and 17α-ethinylestradiol on thermoplastic polyurethane by site energy distribution theory.

Compound pollution of microplastics and estrogens is a growing ecotoxicological problem in aquatic environments. The adsorption isothermal properties of bisphenol A (BPA) and 17α-ethinyl estradiol (EE2) on polyamide (TPU) in monosolute and bisolute systems were studied. Under the same adsorption concentration (1-4mg L-1), EE2 had a greater adsorption capacity than BPA in the monsolute system. Compared to the energy distribution features of the adsorption sites of EE2 and BPA, the BPA adsorption sites were located in the higher energy area and were more evenly distributed than those of EE2, while the quantity of BPA adsorption sites was less than that of EE2. In the bisolute system, the average site energy, site energy inhomogeneity, and adsorption site numbers of BPA increased by 1.674, -17.166, and 16.793%, respectively. In comparison, the average site energy, site energy inhomogeneity, and adsorption sites numbers of EE2 increased by 2.267, 4.416, and 8.585%, respectively. The results showed that BPA and EE2 had a cooperative effect on the competitive adsorption of TPU. XPS analysis showed that BPA and EE2 had electron transfer on TPU, although the chemisorption effects and hydrogen bonds between BPA and TPU were more significant. Comparing the changes in the relative functional group content of TPU in monosolute and bisolute systems, BPA and EE2 were synergistically absorbed on TPU. This study can provide a theoretical reference for the study of competitive adsorption between coexisting organic pollutants.

Herbivores disrupt the flow of food resources to termites in dryland ecosystems.

Irruption of herbivore populations due to the extirpation of predators has led to dramatic changes in ecosystem functioning worldwide. Herbivores compete with other species for their primary source of nutrition, plant biomass. Such competition is typically considered to occur between species in closely related clades and functional groups but could also occur with detritivores that consume senescent plant biomass. In this study, we tested predictions that in ecosystems where herbivores are not regulated by predators, their indirect impacts on dead vegetation increase with primary productivity and extend to termites that feed on senescent vegetation. We compared dead vegetation cover and termite activity in herbivore exclosures and associated grazed plots at three locations situated along a rainfall gradient in arid Australia where kangaroo populations have irrupted. Dead vegetation cover and termite activity increased with rainfall in ungrazed plots but showed a negligible response to rainfall in grazed plots. Our results suggest that grazing can disrupt the flow of energy to detritivores and decouple the relationship between termite activity and primary productivity. Such disruption could have far-reaching impacts on arid ecosystems because many organisms sit within "brown food webs" that are sustained by energy derived from the decomposition of senescent plant tissues.

Stimulating effects of snow cover on gaseous nitrogen emissions are intensified by biological soil crusts

Winter weather patterns are changing due to global climate change, which impacts the soil nitrogen cycle and greenhouse gas flux in these ecosystems, particularly the snow cover in temperate deserts. Biological soil crusts are important soil communities of the desert ecosystem and are sensitive to environmental changes. However, knowledge of the responses of gaseous nitrogen emissions from biological soil crusts to changes in snow cover is limited. In this study, the effects of snow cover on gaseous nitrogen emissions and the abundance of nitrifier (amoA) and denitrifier (narG, nirS, nirK, nosZ) genes were investigated in three snow cover treatments (snow removal, ambient snow, and increased snow depth). Snow cover significantly affected N2O and NO emissions from bare sand and biological soil crusts in winter. The abundance of denitrifier genes in bare sand and biological soil crusts and the abundance of nitrifier genes in moss crust increased with the depths of snow addition. N2O emissions increased with the successional stages of biological soil crusts during the winter. Both N2O and NO emissions from bare sand and biological soil crusts peaked in the freeze–thaw period (March) and were lowest in mid-winter (January). The emissions of N2O increased with increasing the abundance of amoA, nirK and nosZ genes. Our findings show that N2O emissions generally increased with increasing snow cover through their effects on nitrogen cycle related functional microbial groups. These effects were regulated by the types of biological soil crust, which can increase the effect of snow cover in winter.