The individual and competitive adsorption of PbII, NiII, and SrII on graphene oxides (GOs) was investigated by experimental and density functional theory (DFT) studies. Experimental results indicate ...that 1) in all the single, binary, and ternary metal‐ion adsorption systems, the sequence of maximum adsorption capacities is PbII>NiII>SrII on GOs; 2) the desorption hysteresis of metal ions from GOs shows the adsorption affinity in the same sequence: PbII>NiII>SrII. For the first time, DFT calculations indicate that 1) PbII and NiII prefer to interact with the COH group, whereas SrII interacts with COH and COC comparably, and 2) PbII can easily the OH group from the GOs to form the much more stable Pb(OH)–GO complex. These findings are very important and useful for understanding the mechanisms of heavy‐metal‐ion adsorption on GOs and assessing the adsorption of coexisting heavy‐metal ions on GOs.
Ready, set, GO! The adsorption of PbII, NiII, and SrII on graphene oxides (GOs) has been investigated by experimental and density functional theory studies. The results indicate that PbII and NiII prefer to interact with COH, whereas SrII interacts with COH and COC comparably and PbII can OH from GOs to form the more stable Pb(OH)–GO complex (see figure).
To assess the environmental behavior and impact of graphene oxide (GO) on living organisms more accurately, the aggregation of GO and its deposition on Al2O3 particles were systematically ...investigated using batch experiments across a wide range of solution chemistries. The results indicated that the aggregation of GO and its deposition on Al2O3 depended on the solution pH and the types and concentrations of electrolytes. MgCl2 and CaCl2 destabilized GO because of their effective charge screening and neutralization, and the presence of NaH2PO4 and poly(acrylic acid) (PAA) improved the stability of GO with the increase in pH values as a result of electrostatic interactions and steric repulsion. Specifically, the dissolution of Al2O3 contributed to GO aggregation at relatively low pH or high pH values. Results from this study provide critical information for predicting the fate of GO in aquatic-terrestrial transition zones, where aluminum (hydro)oxides are present.
An obligate mutualistic relationship exists between the fungus
and woodwasp
. The fungus digests lignin in the host pine, providing essential nutrients for the growing woodwasp larvae. However, the ...functional properties of this symbiosis are poorly described. In this study, we identified, cloned, and characterized 14 laccase genes from
. These genes encoded proteins of 508 to 529 amino acids and contained three typical copper-oxidase domains, necessary to confer laccase activity. Besides, we performed molecular docking and dynamics simulation of the laccase proteins in complex with lignin compounds (monomers, dimers, trimers, and tetramers). AaLac2, AaLac3, AaLac6, AaLac8, and AaLac10 were found that had low binding energies with all lignin model compounds tested and three of them could maintain stability when binding to these compounds. Among these complexes, amino acid residues ALA, GLN, LEU, PHE, PRO, and SER were commonly present. Our study reveals the molecular basis of
laccases interacting with lignin, which is essential for understanding how the fungus provides nutrients to
These findings might also provide guidance for the control of
by informing the design of enzyme mutants that could reduce the efficiency of lignin degradation.
Microbial communities can be critical for many metazoans, which can lead to the observation of phylosymbiosis with phylogenetically related species sharing similar microbial communities. Most of the ...previous studies on phylosymbiosis were conducted across the host families or genera. However, it is unclear whether the phylosymbiosis signal is still prevalent at lower taxonomic levels. In this study, 54 individuals from six species of the fig wasp genus
(Hymenoptera: Agaonidae) collected from nine natural populations and their associated microbiota were investigated. The fig wasp species were morphologically identified and further determined by mitochondrial CO1 gene fragments and nuclear ITS2 sequences, and the V4 region of 16S rRNA gene was sequenced to analyze the bacterial communities. The results suggest a significant positive correlation between host genetic characteristics and microbial diversity characteristics, indicating the phylosymbiosis signal between the phylogeny of insect hosts and the associated microbiota in the lower classification level within a genus. Moreover, we found that the endosymbiotic
carried by fig wasps led to a decrease in bacterial diversity of host-associated microbial communities. This study contributes to our understanding of the role of host phylogeny, as well as the role of endosymbionts in shaping the host-associated microbial community.
Abstract Capturing gaseous mercury (Hg 0 ) from sulfur dioxide (SO 2 )-containing flue gases remains a common yet persistently challenge. Here we introduce a low-temperature sulfur chemical vapor ...deposition (S-CVD) technique that effectively converts SO 2 , with intermittently introduced H 2 S, into deposited sulfur (S d 0 ) on metal sulfides (MS), facilitating self-sustained adsorption of Hg 0 . ZnS, as a representative MS model, undergoes a decrease in the coordination number of Zn–S from 3.9 to 3.5 after S d 0 deposition, accompanied by the generation of unsaturated-coordinated polysulfide species (S n 2– , named S d * ) with significantly enhanced Hg 0 adsorption performance. Surprisingly, the adsorption product, HgS (ZnS@HgS), can serve as a fresh interface for the activation of S d 0 to S d * through the S-CVD method, thereby achieving a self-sustained Hg 0 adsorption capacity exceeding 300 mg g −1 without saturation limitations. Theoretical calculations substantiate the self-sustained adsorption mechanism that S 8 ring on both ZnS and ZnS@HgS can be activated to chemical bond S 4 chain, exhibiting a stronger Hg 0 adsorption energy than pristine ones. Importantly, this S-CVD strategy is applicable to the in-situ activation of synthetic or natural MS containing chalcophile metal elements for Hg 0 removal and also holds potential applications for various purposes requiring MS adsorbents.
Humic substances increased Co(II) sorption on MWCNT/iron oxide composites at low pH, whereas decreased Co(II) sorption at high pH.
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► MWCNT/iron oxide composites were used to remove ...Co(II) and humic substances. ► Humic substances affected Co(II) sorption on MWCNT/iron oxide composites. ► The Langmuir model fitted well Co(II) sorption isotherms. ► MWCNT/iron oxide composites can be used to remove the pollutants in large scale.
The effects of contact time, pH, ionic strength, foreign ions, temperature, humic substances (HSs), and the addition sequences of Co(II)/HSs on Co(II) sorption on magnetic multiwalled carbon nanotube/iron oxide composites (magnetic MWCNT/IO composites) were investigated under ambient conditions. The results indicated that Co(II) sorption on the magnetic MWCNT/IO composites increased with increasing pH. The ionic strength and foreign ion dependent of Co(II) sorption suggested that ion exchange and outer-sphere surface complexation were the main sorption mechanism at low pH, whereas the ionic strength and foreign ion independent of Co(II) sorption at high pH values indicated that inner-sphere surface complexation was predominant sorption mechanism. The Langmuir model fitted Co(II) sorption isotherms better than the Freundlich model. The thermodynamic data calculated from the temperature dependent sorption isotherms suggested that Co(II) sorption on the magnetic MWCNT/IO composites was a spontaneous and endothermic process. The removal of Co(II) by the magnetic MWCNT/IO composites was affected evidently by the presence of HSs and by the addition sequences of Co(II)/HSs. This study highlights the interactions between Co(II) and HSs to determine the mutual effects of inorganic and organic matters on the removal of metal ions in environmental pollution management.
Batch experiments were conducted to elucidate the adsorption of Pb(II) and three types of widely used surfactants (sodium dodecylbenzene sulfonate (SDBS), octyl-phenol-ethoxylate (TX-100), and ...benzalkonium chloride (BKC)) from aqueous solutions by using oxidized multiwall carbon nanotubes (OMWCNTs). The effect of each kind of surfactant on the adsorption of Pb(II) and vice versa were studied in detail. The results indicated that the pH values affected the adsorption of Pb(II), TX-100 and BKC to OMWCNTs dramatically, whereas the adsorption of SDBS was almost pH-independent at pH<9 and then decreased with increasing pH at pH>9. The adsorption of Pb(II) was enhanced obviously by the presence of SDBS, but slightly inhibited by the presence of BKC. The adsorption of Pb(II) can be well described by Langmuir model. The adsorption process in the Pb–surfactant–OMWCNT ternary system was attributed to electrostatic, hydrophobic and π–π interactions. XPS analysis showed that the adsorption mechanism was mainly due to chemical interaction between Pb(II) and the surface functional groups of OMWCNTs and the surfactants.
In this work, bentonite embedded in the polyacrylamide (PAAm) gels was used as a novel adsorbent for the removal of Cu(II) from aqueous solution. The sorption and desorption of Cu(II) on ...bentonite–polyacrylamide (BENT–PAAm) was investigated as the function of pH, ionic strength, adsorbent content, Cu(II) concentrations and temperature. The results indicated that the sorption of Cu(II) on BENT–PAAm was strongly dependent on pH, ionic strength and temperature. The sorption increased from about 9% to 97% at pH ranging from 2.4 to 7. The sorption of Cu(II) on BENT–PAAm increased with increasing temperature and decreasing ionic strength. The sorption of Cu(II) on BENT and on BENT–PAAm was an endothermic and irreversible process. The results of desorption indicated that the adsorbed Cu(II) ions on solid particles were difficult to be desorbed from solid to liquid phase. From the comparison with BENT, BENT–PAAm showed higher sorption capacity with
C
smax increasing from 29 to 33
mg/g at pH 6.2 and from 11 to 20
mg/g at pH 5.0 for the sorption of Cu(II) from BENT to BENT–PAAm composites. The average standard enthalpy change (Δ
H°) and the entropy change (Δ
S°) of Cu(II) sorption on BENT–PAAm are higher than those of Cu(II) sorption on BENT. The BENT–PAAm composites can be used as a super-adsorbent for the removal of Cu(II) from aqueous solution.
The adsorption of Cu(II) from aqueous solution to GMZ bentonite was studied using batch technique under ambient conditions. Removal percentage (%) and distribution coefficient (
K
d) were determined ...as a function of contact time, pH, ionic strength and temperature. The adsorption of Cu(II) on GMZ bentonite increased with increasing pH gradually at pH
<
6.5, and maintained high level at pH
>
6.5. At pH
<
6.5, the removal percentage of Cu(II) was the highest at ionic strength of 0.001
M NaNO
3 and was the lowest at ionic strength of 0.1
M NaNO
3. The presence of complementary cations depressed the adsorption of Cu(II) on bentonite in the order of Li
+
>
Na
+
>
K
+ at pH
<
6.5. The adsorption isotherms were simulated by the Langmuir, Freundlich, and Dubinin–Radushkevich (
D–
R) models very well. The thermodynamic parameters (i.e., Δ
H
0, Δ
S
0 and Δ
G
0) for the adsorption of Cu(II) were determined from the temperature dependent isotherms at 293.15, 313.15 and 333.15
K, respectively, and the results indicated that the adsorption reaction was favored at higher temperature. The results suggest that GMZ bentonite is a suitable material as an adsorbent for preconcentration and immobilization of Cu(II) from aqueous solution.
Axonal degeneration is a hallmark of many neuropathies, neurodegenerative diseases, and injuries. Here, using a Drosophila injury model, we have identified a highly conserved E3 ubiquitin ligase, ...Highwire (Hiw), as an important regulator of axonal and synaptic degeneration. Mutations in hiw strongly inhibit Wallerian degeneration in multiple neuron types and developmental stages. This new phenotype is mediated by a new downstream target of Hiw: the NAD+ biosynthetic enzyme nicotinamide mononucleotide adenyltransferase (Nmnat), which acts in parallel to a previously known target of Hiw, the Wallenda dileucine zipper kinase (Wnd/DLK) MAPKKK. Hiw promotes a rapid disappearance of Nmnat protein in the distal stump after injury. An increased level of Nmnat protein in hiw mutants is both required and sufficient to inhibit degeneration. Ectopically expressed mouse Nmnat2 is also subject to regulation by Hiw in distal axons and synapses. These findings implicate an important role for endogenous Nmnat and its regulation, via a conserved mechanism, in the initiation of axonal degeneration. Through independent regulation of Wnd/DLK, whose function is required for proximal axons to regenerate, Hiw plays a central role in coordinating both regenerative and degenerative responses to axonal injury.
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