The core 1 β1-3-galactosyltransferase (T-synthase) transfers Gal from UDP-Gal to GalNAcα1-Ser/Thr (Tn antigen) to form the core 1 O-glycan Galβ1-3GalNAcα1-Ser/Thr (T antigen). The T antigen is a ...precursor for extended and branched O-glycans of largely unknown function. We found that wild-type mice expressed the NeuAcα2-3Galβ1-3GalNAcα1-Ser/Thr primarily in endothelial, hematopoietic, and epithelial cells during development. Gene-targeted mice lacking T-synthase instead expressed the nonsialylated Tn antigen in these cells and developed brain hemorrhage that was uniformly fatal by embryonic day 14. T-synthase-deficient brains formed a chaotic microvascular network with distorted capillary lumens and defective association of endothelial cells with pericytes and extracellular matrix. These data reveal an unexpected requirement for core 1-derived O-glycans during angiogenesis.
In order to evaluate the influence of particle size and particle concentration on the coagulation process, two kinds of particle suspensions, nanoparticles and microparticles, were employed to ...investigate the effect of particle size on coagulation mechanisms with varying coagulation parameters. Results showed that it is easier for nanoparticles to cause self-aggregation because of Brownian motion, while interception and sedimentation are the mainly physical processes affecting particle transport for microparticles, so they are more stable and disperse more easily. The particle size distribution and particle concentration had distinct influence on the coagulation mechanisms. Under neutral conditions, as the amount of coagulant increased, the coagulation mechanism for nanoparticles changed from charge neutralization to sweep flocculation and the nanoparticles became destabilized, re-stabilized and again destabilized. For microparticles, although the coagulation mechanism was the same as that of nanoparticles, the increased rate of aluminum hydroxide precipitation exceeded the adsorption of incipiently formed soluble alum species, resulting in the disappearance of the re-stabilization zone. Under acidic conditions, Brownian motion dominates for nanoparticles at low particle concentrations, while sweep flocculation is predominant at high particle concentrations. As for microparticles, charge neutralization and sweep flocculation are the mechanisms for low and high particle concentrations respectively. Under alkaline condition, although the mechanisms for both nano- and microparticles are the same, the morphology of flocs and the kinetics of floc formation are different. At low particle concentrations, nanoparticles have larger growth rate and final size of flocs, while at high particle concentrations, nanoparticles have higher fractal dimension and recovery factors.
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•Partitioning of four dyes-types on modified nanocluster and the mechanism was studied.•Surface modification was governed by chemisorption and followed Langmuir isotherm.•SDS sorption ...capacity had found to influence the equilibrium dye concentration.•With much increase in equilibrium SDS, the dyes seemed entrapped in the micelle.•Simultaneous removal of dye and suspension appeared to obey Brownian motion.
Simultaneous removal of poorly biodegradable synthetic dyes and associated suspended particles, like a textile effluent, is a common challenge in the water treatment sector. Herein, a method based on sodium dodecyl sulfate (SDS) as a sorbet to modify fresh aggregate of polycationic nanocluster (Al30) was developed for the simultaneous removal of dyes and suspension from the water by one-step treatment. The FT-IR, TEM and Zeta potential analysis revealed that dodecyl sulfate (DS) was favorably adsorbed onto the fresh aggregates of Al30, which was found to follow Langmuir isotherm (R2 = 0.988) rather than Freundlich model (R2 = 0.726). The negative ΔG0ads (−29.3) and RL value (0.1535), between 0 and 1, further corroborated the spontaneous SDS condensation on the Al30 aggregates. In the treatment of dye wastewater, the target dyes and turbidity were removed more than 95% at pH 8, concomitant with DS adsorption. The linear relation between Xadm and Xbul (R2 = 0.99) described the classical partitioning of dyes into the modified surface, which was further confirmed by TEM-EDX investigation and online fluorescence image. The simultaneous removal of concentrated dye and suspension suggests the applicability of this method for a textile and other dye wastewater treatment alternative.
Surface Enhanced Raman spectroscopy (SERS) is a molecular‐specific analytical technique with various applications. Although electromagnetic (EM) and chemical (CM) mechanisms have been proposed to be ...the main origins of SERS, exploring highly sensitive SERS substrates with well‐defined mechanistic pathways remains challenging. Since surface and electronic structures of substrates were crucial for SERS activity, zero‐valent transition metals (Fe and Cu) were intercalated into MoO3 to modulate its surface and electronic structures, leading to unexceptional high enhancement factors (1.0×108 and 1.1×1010 for Fe‐MoO3 and Cu‐MoO3, respectively) with decent reproducibility and stability. Interestingly, different mechanistic pathways (CM and EM) were proposed for Fe‐MoO3 and Cu‐MoO3 according to mechanistic investigations. The different mechanisms of Fe‐MoO3 and Cu‐MoO3 were rationalized by the electronic structures of the intercalated Fe(0) and Cu(0), which modulates the surface and electronic structures of Fe‐MoO3 and Cu‐MoO3 to differentiate their SERS mechanisms.
Intercalations of molybdenum trioxide using Fe and Cu lead to outstanding SERS activities through different mechanistic pathways. The Fe intercalation of molybdenum trioxide facilitates the charge transfer pathways for chemical mechanism, while the Cu intercalation enhances surface plasmon resonance by increasing charge carrier density, leading to electromagnetic mechanism.
Surface Enhanced Raman spectroscopy (SERS) is a molecular-specific analytical technique with various applications. Although electromagnetic (EM) and chemical (CM) mechanisms have been proposed to be ...the main origins of SERS, exploring highly sensitive SERS substrates with well-defined mechanistic pathways remains challenging. Since surface and electronic structures of substrates were crucial for SERS activity, zero-valent transition metals (Fe and Cu) were intercalated into MoO
to modulate its surface and electronic structures, leading to unexceptional high enhancement factors (1.0×10
and 1.1×10
for Fe-MoO
and Cu-MoO
, respectively) with decent reproducibility and stability. Interestingly, different mechanistic pathways (CM and EM) were proposed for Fe-MoO
and Cu-MoO
according to mechanistic investigations. The different mechanisms of Fe-MoO
and Cu-MoO
were rationalized by the electronic structures of the intercalated Fe(0) and Cu(0), which modulates the surface and electronic structures of Fe-MoO
and Cu-MoO
to differentiate their SERS mechanisms.
Mn(II) oxidation by free chlorine can be applied to remove Mn(II) at water treatment plants. This reaction also results in particulate MnO x formation and accumulation in drinking water ...distribution systems. This study investigated the effect of Fe(III) and Al(III) hydrolysis products (mainly precipitates) on Mn(II) oxidation by free chlorine under drinking water conditions. The results showed that Fe3+ added as FeCl3 and Al(III) added as polyaluminum chloride (PACl) at tens to hundreds of micrograms per liter dramatically catalyzed Mn(II) oxidation by free chlorine. Through hydrolytic precipitation at circumneutral pH, Fe3+ and Al13 (the dominant preformed Al species in PACl) generated Fe(OH)3-like particles and Al13 aggregates, respectively, which initiated heterogeneous Mn(II) oxidation. Kinetic modeling indicated that, once some MnO x was formed, MnO x and Fe(OH)3 catalyzed the subsequent Mn(II) oxidation to an equal extent. The particles (aggregates) formed from Al13 species exhibited a weaker catalytic capacity in comparison to MnO x and Fe(OH)3 at equivalent molar concentrations. Interestingly, unlike Al13 species in PACl, Al(III) added as AlCl3 had a negligible influence on Mn(II) oxidation, even when Al(OH)3(am) precipitates were formed. The catalytic effects of Fe3+ and Al13 hydrolysis products were confirmed by experiments with natural water and finished water, and the lower Mn(II) oxidation rate was mainly attributed to organic matter.
Natural organic matter (NOM) can tremendously influence the purification efficiency of the drinking water treatment process. Coagulation was the first and primary process of NOM removal in the ...drinking water treatment process. The interaction between coagulants and NOM molecules remains unclear. Three typical coagulants (Al13, FeCl3, and AlCl3) were used to investigate the effects on NOM removal. The measurement of NOM was conducted using 15 T Electrospray Ionization coupled Fourier-Transform-Ion Cyclotron Resonance Mass Spectrometry (ESI-FT-ICR MS). The coagulation process altered the mass peak numbers as well as relative intensity of the peaks which were positively correlated with TOC value. The lignin-like compound was the most abundant moiety in raw water. Al-based coagulants remove more unsaturated larger compounds (lower KMD and higher carbon number). Al13 remove the unsaturated hydrocarbons preferably. FeCl3 is more reactive with NOM molecules and removes more fully saturated compounds. These findings revealed the coagulation removal mechanism of NOM with different structural characteristics and advise the practical use of coagulants for various raw water with different NOM characteristics.
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•Non-targeted screening analysis of NOM were performed.•ESI-FT-ICRMS was used in the coagulation performance of NOM removal.•The removal specificity of coagulants was discovered.•Lignin-like moiety was major class in the raw water.
The effective removal of humic acid (HA) by coagulation has been extensively investigated for water treatments. However, the limitations of pH variation and excessive residual aluminum issues were ...still factors needed to be considered. In this study, to investigate the coagulation mechanism for removing HA by Al
and optimize Al
operation for removing HA, Al
and preformed Al
aggregates (Al
agg) were applied to remove HA at different pH conditions. The results showed that preformed Al
agg exhibited superior HA removal performance than Al
due to its wide pH range and low residual Al level. During coagulation, Al
and Al
agg interacted with HA in their original status, but the DSlope
difference implied that the complexation capacity between HA and Al
agg was stronger than Al
. The new peaks of HPSEC representing larger molecular weight substances were formed under acidic and neutral conditions, which indicated that HA firstly aggregated into larger complexed molecules by interacting with Al
or its hydrolysates and was subsequently removed by forming large flocs which was completely different from Al
agg situation. Therefore, the different coagulation mechanisms played the roles in HA removal for Al
and Al
agg which were studied in this paper. It was believed that the complexation and charge neutralization effects dominated coagulation process for Al
while sweep flocculation and adsorption coagulation were main driving force for Al
agg in HA removing. This work provides significant understanding of HA removal by Al
and Al
agg coagulation, which can help to design and optimize the high efficiency coagulant based on Al polycations.
Let X be a Banach space and
$ B(X) $
B
(
X
)
be the algebra of all bounded linear operators on X. Firstly, we prove that every derivable mapping at a nonzero element in
$ B(X) $
B
(
X
)
is a ...derivation. As a corollary, we show that every generalized derivable mapping on
$ B(X) $
B
(
X
)
is a general derivation. Secondly, we prove that every centralizable mapping on
$ B(X) $
B
(
X
)
is a centralizer.
Coagulation is well-established for controlling regulated disinfection by-products (DBPs), but its effectiveness for controlling unregulated DBPs remains unclear. The efficiency of coagulation in ...controlling unregulated DBPs requires clarification owing to their relatively high toxicity. In this study, three Al-based coagulants, aluminum sulfate (Alum), polyaluminum chloride (PAC), and a novel type of covalently bond hybrid coagulant (CBC, synthesized using AlCl3) were selected, and the coagulation performance of these Al-based coagulants in controlling DBPs and DBP-associated toxicity was compared over 5 classes of DBPs, including trihalomethanes, haloacetic acids, haloacetaldehydes, haloacetonitriles, and halonitromethanes. The results showed that Alum was the least efficient in removing DBP precursors among the three coagulants. The effectiveness of CBC and PAC for DBP control varied with the characteristics of source waters. CBC had an advantage in water with a low content of humic acids, and reduced DBP concentration and DBP-associated toxicity by 47% and 25%, respectively. For water rich in aromatic organics, CBC might serve as DBP precursors at a high-required dosage, suggesting that a trade-off between enhanced DBP control and serving as DBP precursors should be considered for CBC coagulation; PAC achieved the most reduction in DBP concentration and DBP-associated toxicity by 50% and 34%, respectively.
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•Coagulation performance and DBP control of three Al-based coagulants were evaluated.•CBC showed higher removal of turbidity and UV245 compared to PAC and Alum.•CBC outperformed Alum and PAC in the control of nitrogenous DBP formation.•A trade-off between enhanced DBP control and being DBP precursors is required for CBC.•Effectiveness of CBC and PAC for DBP control varied with the characteristics of source waters.
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