In situ surface modification of forward osmosis membrane by polydopamine/polyethyleneimine-silver nanoparticle for anti-fouling improvement in municipal wastewater treatment.

In this work, we demonstrate the surface functionalization of cellulose triacetate membrane with co-deposition of polydopamine (PDA)/polyethyleneimine (PEI) and silver nanoparticles (AgNPs) for antifouling property in municipal wastewater treatment. PDA/PEI was first coated on the membrane surface by single-step co-deposition, while AgNPs were formed in situ through catechol groups of PDA immobilizing silver ions and subsequently reducing. The successful surface modification was verified by different membrane characterization techniques. The modified PDA/PEI-nAg CTA membrane exhibits enhanced hydrophilicity and improved antiadhesion and antimicrobial activity. Furthermore, the functional layer had an indistinctive effect on the membrane transport parameters. In addition, dynamic forward osmosis (FO) fouling experiment with raw municipal wastewater as feed solution indicated that the PDA/PEI-nAg CTA membrane exhibited notably lower water flux decrease compared to the nascent CTA membrane. The results of confocal laser scanning microscopy (CLSM) showed that PDA/PEI-nAg CTA membranes effectively reduced the adsorption of organic foulants (proteins and polysaccharides) and inhibited the formation and development of the fouling layer. The membrane surface modification of the CTA membrane with PDA/PEI and AgNPs efficiently mitigated membrane fouling in municipal wastewater treatment.

Comparative proteomics reveals new insights into the endosperm responses to drought, salinity and submergence in germinating wheat seeds.

KEY MESSAGE: Beyond the role of a nutrient reservoir during germination, the endosperm of wheat seeds also responds to different abiotic stresses via modification of the protein profiles. The endosperm is the main component of wheat seeds. During seed germination, it provides nutrients to support the embryo development, and its constituents vary under environmental stresses such as drought, salinity and submergence that are associated with disordered water supply. However, the molecular mechanism of these stress responses remains unclear. In this study, a comparative label-free proteomic analysis was performed on endosperm from the germinating wheat seeds subjected to PEG, NaCl and submergence treatments. In total, 2273 high confidence proteins were detected, and 234, 207 and 209 of them were identified as differentially expressed proteins (DEPs) under the three stresses, respectively. Functional classification revealed that the DEPs were mainly involved in protein, amino acid and organic acid metabolic process in all stress treatments. While some other metabolic processes were highlighted in one or two of the stresses specifically, such as oxidative phosphorylation in PEG and submergence, and ß-alanine metabolism in PEG and NaCl treatments. The identification of a series of stress-related proteins and their biased expression in different stresses indicates the active stress-responding role of endosperm beyond a simple nutrient reservoir during germination, while the overall stress responses of the endosperm were found to be moderate and lag behind the embryo. Besides, some fundamental processes and DEPs shared by the three stresses could be selected priorly for future molecular breeding researches. Our results provide new insights into the mechanism of endosperm responses to abiotic stresses during seed germination.

Fractionation of technical lignin and its application on the lignin/poly-(butylene adipate-co-terephthalate) bio-composites.

Complex and heterogeneous structures of lignin impede its further conversion and valorization. Herein, three technical lignins (from softwood, hardwood, and grass) were fractionated with acetone solvent to reduce their structural heterogeneity, which were then blended with poly-(butylene adipate-co-terephthalate) (PBAT) to fabricate biodegradable bio-composites. Macromolecular structures of lignins and their effects on the properties of lignin/PBAT composites were thoroughly investigated. Results showed that all fractionated lignin composites displayed better properties. Particularly, the raw and fractionated softwood lignin-based composites exhibited superior performance compared with others. Benefiting from the lower molecular weight, hydroxyl groups, and condensation, acetone fractionated softwood lignin presented the lowest Tg (115.7 °C), achieving ideal melt miscibility and interfacial interaction between lignin and PBAT. The decreased Tg of lignin facilitated the lignin dispersion in the matrix and increase the mechanical strength of the composites. Overall, the fractionated technical lignin possessed desirable physical and chemical structure features, conferring composites good miscibility and mechanical properties.

CuO@carbon nanofiber as an efficient peroxymonosulfate catalyst for mitigation of organic matter fouling in the ultrafiltration process.

Persulfate oxidation has been increasingly integrated with membrane separation for water purification, whereas the oxidizing ability of persulfate is relatively limited, and appropriate activation methods are urgently required. In this work, a novel catalyst of carbon nanofiber (CNF) supported CuO (CuO@CNF) was synthesized for peroxymonosulfate (PMS) activation. The micro-morphology showed that CuO nanoparticles were well dispersed on the CNF support, which solved the agglomeration problem of nanoparticles and improved the catalytic ability. Furtherly, PMS oxidation activated by CuO@CNF was proposed as a pre-processing means for improving ultrafiltration (UF) water purification efficiency and mitigating membrane fouling. The prepared CuO@CNF was more efficient than individual CNF and CuO in activating PMS for the reduction of various typical natural organic matter, improving permeation flux, and mitigating membrane fouling. The fouling control efficiencies were also verified by characterizing the membrane surface functional groups. The CuO@CNF catalyst could signally promote the oxidative capacity by generating a series of reactive oxygen species, thus enhancing the removal of organics with varying species and molecular weight ranges in surface water. With respect to the fouling condition, the specific permeation flux after filtration was improved from 0.25 to 0.61, with the removal rate of reversible fouling resistance reached 89.6%. The fouling mechanism was apparently altered, with both standard and complete blocking dominated throughout the filtration process. The findings are beneficial for the development of new strategies to improve membrane-based water purification efficiency.

Recent Advances in Bioinspired Hydrogels with Environment-Responsive Characteristics for Biomedical Applications.

The development of hydrogel-integrated soft materials via the incorporation of therapeutic medicines into biocompatible hydrogels, serving as host, will significantly contribute to advances in medical diagnosis and treatment. Furthermore, intelligent hydrogels having the ability to respond to local environmental conditions offer a promising approach for the development of novel solutions in the biomedical field. Bioinspired intelligent hydrogels are now becoming a potentially powerful biomaterial class for tissue engineering, drug delivery, and medical device. Recent advances include bioinspired intelligent hydrogels that possess unique mechanical and optical properties as a result of their nature-inspired complex-structured design. This review highlights the latest advances in intelligent bionic hydrogels, as well as strategies targeting smart response of their characteristics across multiple dimensions (such as temperature, light, pH, among others). Finally, the potential development and prospective application of mimicking the natural intelligence of multifunctional medical hydrogels are also discussed.

Ferrous-activated sodium percarbonate pre-oxidation for membrane fouling control during ultrafiltration of algae-laden water.

Membrane technology has been shown to be promising for the treatment of algae-laden water, but membrane fouling is still an obstacle influencing the purification efficiency and effluent quality. To mitigate ultrafiltration membrane fouling during Microcystis aeruginosa-laden water treatment, a strategy of sodium percarbonate pre-oxidation activated with ferrous ion (Fe2+/SPC) was put forward in this study. Due to the synergistic effect of Fe2+ and SPC, this process was significantly more efficient with the terminal specific flux increased from 0.097 to 0.397, and the reversible fouling resistance reduced by approximately 80%. It was also found that subsequent sedimentation followed by Fe2+/SPC could further improve the fouling control efficiency. The model fitting results indicated that Fe2+/SPC pre-oxidation delayed the transition from standard blocking to cake filtration. Extracellular organic matter and algal cells were extracted from algal foulants to explore the contribution of each component, and the fouling control efficiencies were systematically studied. The characteristics of the algal foulants were determined with fluorescence excitation-emission matrix spectrum, and the results suggested that macromolecular proteinaceous substances were more efficiently removed by Fe2+/SPC, in comparison with humic-like matters. The alleviation of membrane fouling was also verified by the characterization methods of scanning electron microscopy and attenuated total reflection-Fourier infrared spectroscopy. Overall, the proposed strategy of Fe2+/SPC has an application prospect for membrane fouling control in algal-laden water treatment.

Effect of various pretreatments on improving cellulose enzymatic digestibility of tobacco stalk and the structural features of co-produced hemicelluloses.

Hereon, tobacco stalk was deconstructed by lyophilization, ball-milling, ultrasound-assisted alkali extraction, hydrothermal pretreatment (HTP), and alkali presoaking, respectively, followed by dilute alkali cooking to both improve its enzymatic digestibility and isolate the hemicellulosic streams. It was found that a maximum cellulose saccharification rate of 93.5% was achieved from the integrated substrate by ball-milling and dilute alkali cooking, which was 4.4-fold higher than that from the raw material. Interestingly, in this case, 76.9% of hemicelluloses were simultaneously recovered during the integrated treatment. Structural determination indicated that the hemicelluloses released from tobacco stalk by dilute alkali cooking were mixed polysaccharides, and the (1 â†’ 4)-linked ß-D-Xylp backbone branched with L-Araf units at O-2/O-3 and 4-O-Me-α-D-GlcpA units at O-2 of the xylose residues was the main structure. In comparison, ultrasound-assisted alkali extraction, ball-milling, and HTP favored the extraction of hemicelluloses with less branched structure and lower molecular weights in the following alkali cooking.

Sonic hedgehog signaling in epithelial tissue development.

The Sonic hedgehog (SHH) signaling pathway is essential for embryonic development and tissue regeneration. The dysfunction of SHH pathway is involved in a variety of diseases, including cancer, birth defects, and other diseases. Here we reviewed recent studies on main molecules involved in the SHH signaling pathway, specifically focused on their function in epithelial tissue and appendages development, including epidermis, touch dome, hair, sebaceous gland, mammary gland, tooth, nail, gastric epithelium, and intestinal epithelium. The advance in understanding the SHH signaling pathway will give us more clues to the mechanisms of tissue repair and regeneration, as well as the development of new treatment for diseases related to dysregulation of SHH signaling pathway.

[Electrophysiological characterization of long QT syndrome associated mutations V630A and N633S].

OBJECTIVE: To identify the electrophysiological properties of long-QT syndrome (LQTS) associated missense mutations in the outer mouth of the HERG potassium channel in vitro. METHODS: Mutations V630A and N633S were constructed by Megaprimer PCR method and cRNA were produced by T7 RNA polymerase. The electrophysiological properties of the mutation were investigated in the Xenopus oocyte heterologous expression system. RESULTS: Coexpression of mutant and wild-type HERG subunits caused a dominant-negative effect, and the currents were significantly decreased. Compared with wild-type HERG channels, V630A and N633S mutations were related to decreased time constants for inactivation for V630A/WT and N633S/WT at all potentials, reduced slope conductance and the voltage dependence of steady-state inactivation was shifted to negative potentials for V630A/WT and N633S/WT. CONCLUSION: Present study shows that LQTS associated missense mutations located in the outer mouth of HERG cause a dominant-negative effect and alterations in steady-state voltage dependence of channel gating of heteromultimeric channels suggesting a reduction in expressional current might be one of the pathophysiologic mechanisms of LQTS.

Evaluation of the chitosan/glycerol-beta-phosphate disodium salt hydrogel application in peripheral nerve regeneration.

Research efforts have been devoted to evaluating the application of the chitosan (CS)/glycerol-beta-phosphate (GP) disodium salt hydrogel in peripheral nerve regeneration. The gelation time was determined to be 770 s using ultraviolet spectrophotometry. A standard 10 mm long rat sciatic nerve defect model was employed, followed by bridging the proximal and distal stumps with chitosan conduits injected with the Schwann cell-containing hydrogel. Injections of the blank hydrogel, Schwann cell suspension and culture medium were used as controls. Two months later, electrophysiological assessment and fluorogold retrograde tracing showed that compound muscle action potentials (CMAPs) and fluorogold-labeled neurons were only detected in the Schwann cell suspension group and culture medium group. The rats were then killed, and implanted conduits were removed for examination. There were no regenerated nerves found in groups injected with the blank hydrogel or Schwann cell-containing hydrogel, while the other two groups clearly displayed regenerated nerves across the gaps. In the subsequent histological assessment, immunohistochemistry, toluidine blue staining and transmission electron microscopy were performed to evaluate the regenerated nerves. The relative wet weight ratio, Masson trichrome staining and acetylcholinesterase staining were employed for the examination of gastrocnemius muscles in all four groups. The Schwann cell suspension group showed the best results for all these indexes; the culture medium group ranked second and the two hydrogel-injected groups showed the least optimal results. In conclusion, our data revealed that the implanted CS/GP hydrogel actually impeded nerve regeneration, which is inconsistent with former in vitro reports and general supposition. We believe that the application of the CS/GP hydrogel in nerve regeneration requires a further study before a satisfactory result is obtained. In addition, the present study also confirmed that Schwann cell implantation stimulated nerve regeneration.

The effect of topology of chitosan biomaterials on the differentiation and proliferation of neural stem cells.

Neural stem cells (NSCs) are capable of self-renewal and differentiation into three principle central nervous system cell types under specific local microenvironments. Chitosan films (Chi-F), chitosan porous scaffolds (Chi-PS) and chitosan multimicrotubule conduits (Chi-MC) were used to investigate their effects on the differentiation and proliferation of NSCs isolated from the cortices of fetal rats. In the presence of 10% fetal bovine serum most NSCs cultured on Chi-F differentiated into astrocytes, NSCs cultured on Chi-MC showed a significant increase in neuronal differentiation, while Chi-PS somewhat promoted NSCs to differentiate into neurons. However, in serum-free medium with 20 ng ml(-1) basic fibroblast growth factor NSCs cultured on Chi-F showed the greatest proliferation, NSCs cultured on Chi-MC showed moderate cell proliferation, but NSCs cultured on Chi-PS exhibited the least cell proliferation. These observations indicate that chitosan topology can play an important role in regulating differentiation and proliferation of NSCs and raise the possibility of the utilization of chitosan in various structural biomaterials in neural tissue engineering.