Mussel-Inspired, Underwater Self-Healing Ionoelastomers Based on α-Lipoic Acid for Iontronics.

Weak adhesion and lack of underwater self-healability hinder advancing soft iontronics particularly in wet environments like sweaty skin and biological fluids. Mussel-inspired, liquid-free ionoelastomers are reported based on seminal thermal ring-opening polymerization of a biomass molecule of α-lipoic acid (LA), followed by sequentially incorporating dopamine methacrylamide as a chain extender, N,N'-bis(acryloyl) cystamine, and lithium bis(trifluoromethanesulphonyl) imide (LiTFSI). The ionoelastomers exhibit universal adhesion to 12 substrates in both dry and wet states, superfast self-healing underwater, sensing capability for monitoring human motion, and flame retardancy. The underwater self-repairabilitiy prolongs over three months without deterioration, and sustains even when mechanical properties greatly increase. The unprecedented underwater self-mendability benefits synergistically from the maximized availability of dynamic disulfide bonds and diverse reversible noncovalent interactions endowed by carboxylic groups, catechols, and LiTFSI, along with the prevented depolymerization by LiTFSI and tunability in mechanical strength. The ionic conductivity reaches 1.4 × 10-6 -2.7 × 10-5 S m-1 because of partial dissociation of LiTFSI. The design rationale offers a new route for creating a wide range of LA- and sulfur-derived supramolecular (bio)polymers with superior adhesion, healability, and other functionalities, and thus has technological implications for coatings, adhesives, binders and sealants, biomedical engineering and drug delivery, wearable and flexible electronics, and human-machine interfaces.

Erratum: How ß-cyclodextrin- loaded mesoporous SiO2 nanospheres ensure efficient adsorption of rifampicin.

[This corrects the article DOI: 10.3389/fchem.2022.1040435.].

How ß-cyclodextrin- loaded mesoporous SiO2 nanospheres ensure efficient adsorption of rifampicin.

In this study, ß-CD@mesoporous SiO2 nanospheres (ß-CD@mSi) were prepared by loading ß-cyclodextrin (ß-CD) onto mesoporous silica nanospheres through an in situ synthesis. This not only solved the defect of ß-CD being easily soluble in water, but also changed the physical structure of the mesoporous silica nanospheres. FTIR and XPS results showed that ß-CD was successfully loaded onto mesoporous silica nanospheres (mSi), while enhancing the adsorption effect. ß-CD@mSi with a monomer diameter of about 150 nm were prepared. At a temperature of 298k, the removal efficiency of a 100 mg/L solution of rifampicin can reach 90% in 4 h and the adsorption capacity was 275.42 mg g-1 at high concentration. Through the calculation and analysis of adsorption kinetics, adsorption isotherms and adsorption thermodynamics based on the experimental data, the reaction is a spontaneous endothermic reaction dominated by chemical adsorption. The electron transfer pathway, structure-activity relationship and energy between ß-CD@mSi and rifampicin were investigated by quantum chemical calculations. The accuracy of the characterization test results to judge the adsorption mechanism was verified, to show the process of rifampicin removal by ß-CD@mSi more clearly and convincingly. The simulation results show that π-π interaction plays a major interaction in the reaction process, followed by intermolecular hydrogen bonding and electrostatic interactions.

Contrasting response of fungal versus bacterial residue accumulation within soil aggregates to long-term fertilization.

Soil microorganisms are critical for soil carbon (C) cycling. They primarily regulate the turnover of the soil organic C (SOC) by adjusting their community structure, and contributing residues with a considerable amount to the resistant SOC. Nevertheless, how long-term fertilization (e.g., the combination of manure and chemical fertilizer) affects the spatial distribution of both living microbial communities and dead microbial residue within soil aggregate fractions remains largely unclear. In this study, we analyzed changes in microbial community (lipid biomarkers) and microbial residue retention (amino sugar biomarkers), and also calculated the contribution of microbial residue to organic C in bulk soil and different soil aggregates (> 2 mm, 1-2 mm, 0.25-1 mm, and < 0.25 mm) in Alfisols treated with 29 years fertilization or no fertilization (control). Our results showed that long-term fertilization significantly increased the mean weight diameter (MWD) of aggregates and organic C contents in all aggregate fractions. The fertilization treatment increased the contents of PLFAs and microbial residue C, but the relative contribution of microbial residue to SOC was higher in the control (56.8% vs. 49.0%), due to the low SOC background caused by much lower level of non-microbially derived C input. These results suggested that long-term fertilization could increase SOC by accumulating both plant- and microbial-derived C, while the C deficient soil is more dependent on the accumulation of microbial residues. Long-term fertilization promoted the enrichment of bacterial-derived muramic acid in micro aggregates, but increased the proportion of fungal-derived glucosamine in macro aggregates. Meanwhile, the contribution of bacterial residue to organic C in the fertilization treatment was higher in micro aggregates (7.6% for > 2 mm vs. 9.2% for < 0.25 mm aggregate), while the contribution of fungal residue was higher in macro aggregate fractions (40.9% for > 2 mm vs. 35.7% for < 0.25 mm aggregate). The above results indicated that long-term fertilization could drive the differentiation of heterogeneous microbial residue accumulation patterns that significantly alter the contribution of fungal- versus bacterial-derived C to organic C within soil aggregate fractions.

Quantitative characterization of non-DLVO factors in the aggregation of black soil colloids.

The variable role and fate of soil colloids under different environmental conditions are derived from their dispersion and aggregation properties. In this work, dynamic and static light scattering were used to characterize the original size, aggregation kinetics of natural black soil colloids (BSCs) and structural features of aggregates in electrolytes with different cations (K+, Mg2+, Ca2+), respectively. For these three cations, the aggregation kinetics followed the trend of Ca2+ > Mg2+ > K+ and the critical coagulation concentration (CCC) followed the sequence: K+ (134.30 mmol L-1) > Mg2+ (13.27 mmol L-1) > Ca2+ (4.19 mmol L-1). The results indicated that the aggregation behavior in different valence cation systems followed the classical Derjaguin-Landau-Verwey-Overbeek (DLVO) model qualitatively. However, the quantitative differences of CCC suggest the existence of ion-specific effects. The effective ionic charge coefficient 1.31, 2.20, and 2.78 of K+, Mg2+ and Ca2+ were proposed to consider of all the non-DLVO factors, which were obtained by forming a relationship based on mathematic between the electrostatic repulsion and the van der Waals attractive interaction at the CCC. The non-classical polarization of cations in a strong soil electric field is a primary mechanism of cation effects on soil colloid interactions, causing the difference in colloid interaction energy and further affecting soil colloid aggregation. This result is crucial for enriching the theory of charged colloidal interactions.

[Multi-center randomized double-blind controlled study on children's anorexia (spleen-stomach disharmony) treated with Child Compound Endothelium Corneum].

Child Compound Endothelium Corneum(CCEC)has the effects in invigorating the spleen and appetizing the appetite, and dissolving the accumulation of food. The recent studies have proved that it could improve gastrointestinal motility, restore physiological gastrointestinal peristalsis, increase gastrointestinal digestive motility, and enhance appetite. This trial aimed to evaluate its clinical efficacy and safety in the treatment of children's anorexia(spleen-stomach disharmony). A total of 240 children with anorexia in line with the inclusion and exclusion criteria were selected and randomly divided into experimental group and control group, with 120 in each group. Patients in the experimental group took CCEC and Erpixing Granules simulant. Patients in the control group took Erpi-xing Granules and CCEC simulant. After 21 days of treatment, there was no statistical difference in the recovery rate of anorexia, reduced food intake, eating time, weight change, traditional Chinese medicine syndrome effect, single symptom effect, and trace element Zn recovery rate between the two groups. Based on the non-inferiority test, the experimental group was not inferior to the control group in efficacy. How-ever, the effect of CCEC in reducing appetite in children with anorexia was better than that of control drugs(P<0.05). There was no statistical difference in the incidence of adverse events and adverse reactions between the two groups during the trial. This experiment confirmed the efficacy and safety of CCEC in the treatment of children's anorexia(spleen-stomach disharmony), with a safety and re-liability in clinical application. In addition, it was a better choice for children with anorexia who were mainly manifested by reduced appetite. Meanwhile, compared with granule, chewable tablets were more convenient to take in clinic. Therefore, the efficacy and safety of CCEC for the treatment of children's anorexia(spleen-stomach disharmony) were not inferior to those of Erpixing Granules, with a safety and reliability in clnic. However, due to the small sample size of this trial, the efficacy results only show a trend. It is suggested to further carry out a large-sample-size clinical study to define the clinical advantages of CCEC.

[Allocation and Stabilization Responses of Rice Photosynthetic Carbon in the Plant-Soil System to Phosphorus Application].

This research studied the response of the input and allocation of photosynthetic carbon (C) to phosphorus (P) in paddy soils. Two treatments were conducted in this experiment:no P application (P0) and the application of 80 mg·kg-1 of P (P80). The rice cultivar was the indica Zhongzao 39. The 13C-CO2 continuous labeling technique was used to identify the photosynthetic C distribution of the rice. The results showed that the application of P80 significantly increased the photosynthates allocation in the rice aboveground, but reduced their allocation in the rhizosphere soil (P<0.05). At the jointing stage, P80 application increased the photosynthetic C content of the rice by 70%, but the root dry weight decreased 31%. Compared with P0, the total C content of the aboveground rice was increased 0.31 g·pot-1 by P80. The ratio of rice roots to shoots decreased with the P80 treatment. Moreover, P80 application led to an increase in the photosynthetic microbial biomass in the non-rhizosphere soil C (13C-MBC) of 0.03 mg·kg-1, but still decreased its allocation in the rhizosphere soil. The allocation of photosynthetic C to the particulate organic matter fraction (POC) and mineral fraction (MOC) in the non-rhizosphere soil showed no significant differences between P0 and P80. Additionally, the P80 fertilization treatment significantly lowered the content of POC in the rhizosphere soil. In summary, P application increased the allocation of photosynthetic C in the soil-rice system, but reduced the accumulation of photosynthetic C in the soil. This research provided a theoretical basis and data supporting the rational application of P fertilizer, and was also of great significance as a study of the transportation and allocation of photosynthetic C and its sequestration potential response to the application of P to the rice soil.

Description of colloidal particles aggregation in the presence of Hofmeister effects: on the relationship between ion adsorption energy and particle aggregation activation energy.

Particle aggregation is acutely affected by Hofmeister effects. Results for aggregation behavior in the presence of Hofmeister effects predicted by the classic DLVO model were not satisfactory. In this study, description of colloidal clay particles aggregation in the presence of Hofmeister effects based on a theoretical relationship between ion adsorption energy and aggregation activation energy was established. Moreover, the validity of the suggested theory was confirmed with the published experimental data on montmorillonite particles aggregation in solutions of LiNO3, KNO3, CsNO3, Mg(NO3)2 and Ca(NO3)2. In the presence of Hofmeister effects, the differences in adsorption ability of the involved five cations were quantitatively characterized by defining an additional Hofmeister energy. We found that the additional Hofmeister energy for Li+, K+, Cs+, Mg2+ and Ca2+ on montmorillonite surface were 0.063, 0.942, 1.864, 0.850 and 2.010-times larger, respectively, than the classic Coulomb interaction energy. Taking these additional Hofmeister energies into account, CCC values for the presence of different cations were theoretically calculated by the suggested theory, and the predicted CCC values matched well with the experimental results. The theoretically predicted CCC values in montmorillonite aggregation for KNO3, CsNO3, Mg(NO3)2 and Ca(NO3)2 were 78.8, 29.9, 6.48, and 3.12 mM, respectively, and the corresponding measured CCC values were 80.3, 27.2, 7.99, and 2.38 mM. Our findings are helpful for further understanding the interactions of nanoparticles with cations and quantitatively answer how ion-surface interactions affect particle interaction processes.

The Effects of Different Oxytetracycline and Copper Treatments on the Performance of Anaerobic Digesters and the Dynamics of Bacterial Communities.

Oxytetracycline and copper are the common residues in animal manures. Meanwhile, anaerobic digestion is considered as a clean biotechnology for the disposal of animal manures. In this paper, the performance of anaerobic digesters and the dynamics of bacterial communities under the different treatments of oxytetracycline and copper were discussed. The parameters of methane production and pH values were studied to reflect the performance of anaerobic digester. Results showed that the changes of methane production and pH values were not obvious compared with the control. This means that the treatments of oxytetracycline and copper almost have no effects on the performance of anaerobic digesters. This phenomenon might be due to the chelation reaction between oxytetracycline and copper. This chelation reaction might reduce the toxicity of oxytetracycline. The study on the dynamics of bacterial communities was based on the polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) method. Results indicated that the bacterial communities had significant differences under the different treatments of oxytetracycline and copper. Uncultured Bacteroidetes bacterium (CU922272.1) and uncultured Bacteroidetes bacterium (AB780945.1) showed adaptability to the different treatments of oxytetracycline and copper and were the dominant bacterial communities.

[Impact of SDBS/Na+ on red soil colloidal stability].

The interactions between soil colloidal-sized particles and organic contaminants or inorganic ions profoundly affect numerous soil physical, chemical and biological processes. The coupling effect of sodium dodecylbenzene sulfonate (SDBS) and Na+ on the aggregation process of red soil colloid was studied using the dynamic light scattering method, and the mechanism of interactions between soil colloidal-sized particles and SDBS/Na+ was analyzed according to the pH and Zeta potential of suspension during the aggregation process. Results show that, (1) under a given concentration of Na+, the soil colloidal suspension becomes more stable with increasing SDBS concentrations. For example, under 120 mmol x L(-1) Na+, as the concentrations of SDBS increase from 0 mmol x L(-1) to 10 mmol x L(-1), the effective diameters of aggregates decrease from 702 nm to 193 nm, and the total average aggregation rates of aggregates decrease from 28.6 nm x min(-1) to 3.36 nm x min(-1). (2) Under a given concentration of SDBS, as the concentrations of Na+ increase, the Zeta potential of suspension sharply decreases, while the effective diameters and the total average aggregation rates of aggregates gradually increase. (3) The absolute values of Zeta potential for suspensions without adding NaNO3 solution increase from 47.6 mV to 62.2 mV as the SDBS concentrations increase, and the pH of the suspensions increase from 6.17 to 6.76, although these pH values are lower than that of initial soil colloidal suspension (6.89). Therefore, the adsorption of SDBS onto soil colloidal-sized particles, which is attributed to the hydrophobic effect and electrostatic effect, results in the increment of surface charge number, as well as the decrease in effective concentration of Na+ around colloidal-sized particles' surface (resulting from the steric hindrance of long hydrophobic chain of adsorbed SDBS and adsorption of Na+ by SDBS micelle). As a result, soil colloidal suspension becomes more stable and needs to absorb more Na+ to aggregate.

Activation energies of colloidal particle aggregation: towards a quantitative characterization of specific ion effects.

A quantitative description of specific ion effects is an essential and focused topic in colloidal and biological science. In this work, the dynamic light scattering technique was employed to study the aggregation kinetics of colloidal particles in the various alkali ion solutions with a wide range of concentrations. It indicated that the activation energies could be used to quantitatively characterize specific ion effects, which was supported by the results of effective hydrodynamic diameters, aggregation rates and critical coagulation concentrations. At a given concentration of 25 mmol L(-1), the activation energies for Li(+) are 1.2, 5.7, 28, and 126 times as much for Na(+), K(+), Rb(+), and Cs(+), respectively. Most importantly, the activation energy differences between two alkali cation species increase sharply with decrease of electrolyte concentrations, implying the more pronounced specific ion effects at lower concentrations. The dominant role of electrolyte cations during the aggregation of negatively charged colloidal particles was confirmed by alternative anions. Among the various theories, only the polarization effect can give a rational interpretation of the above specific ion effects, and this is substantially supported by the presence of strong electric fields from montmorillonite surfaces and its association mainly with electrolyte cations and montmorillonite particles. The classical induction theory, although with inclusion of electric field, requires significant corrections because it predicts an opposite trend to the experimentally observed specific ion effects.

Determination of trace tetracycline antibiotics in foodstuffs by liquid chromatography-tandem mass spectrometry coupled with selective molecular-imprinted solid-phase extraction.

A rapid, specific, and sensitive method has been developed using molecularly imprinted polymers (MIPs) as solid-phase extraction sorbents for extraction of trace tetracycline antibiotics (TCs) in foodstuffs. MIPs were prepared by precipitation polymerization using tetracycline as the template. Under the optimal condition, the imprinting factors for MIPs were 4.1 (oxytetracycline), 7.0 (tetracycline), 7.4 (chlortetracycline), 7.7 (doxycycline), respectively. Furthermore, the performance of MIPs as solid-phase extraction sorbents was evaluated and high extraction efficiency of molecularly imprinted solid-phase extraction (MISPE) procedure was demonstrated. Compared with commercial sorbents, MISPE gave a better cleanup efficiency than C18 cartridge and a higher recovery than Oasis HLB cartridge. Finally, the method of liquid chromatography-tandem mass spectrometry coupled with molecular-imprinted solid-phase extraction was validated in real samples including lobster, duck, honey, and egg. The spiked recoveries of TCs ranged from 94.51% to 103.0%. The limits of detection were in the range of 0.1-0.3 microg kg(-1).