Regulation of ARGs abundance by biofilm colonization on microplastics under selective pressure of antibiotics in river water environment.

Interactions of microplastics (MPs) biofilm with antibiotic resistance genes (ARGs) and antibiotics in aquatic environments have made microplastic biofilm an issue of keen scholarly interest. The process of biofilm formation and the degree of ARGs enrichment in the presence of antibiotic-selective pressure and the impact on the microbial community need to be further investigated. In this paper, the selective pressure of ciprofloxacin (CIP) and illumination conditions were investigated to affect the physicochemical properties, biomass, and extracellular polymer secretion of polyvinyl chloride (PVC) microplastic biofilm. In addition, relative copy numbers of nine ARGs were analyzed by real-time quantitative polymerase chain reaction (qPCR). In the presence of CIP, microorganisms in the water and microplastic biofilm were more inclined to carry associated ARGs (2-3 times higher), which had a contributing effect on ARGs enrichment. The process of pre-microplastic biofilm formation might have an inhibitory effect on ARGs (total relative abundance up to 0.151) transfer and proliferation compared to the surrounding water (total relative abundance up to 0.488). However, in the presence of CIP stress, microplastic biofilm maintained the abundance of ARGs (from 0.151 to 0.149) better compared to the surrounding water (from 0.488 to 0.386). Therefore, microplastic biofilm act as abundance buffer island of ARGs stabilizing the concentration of ARGs. In addition, high-throughput analyses showed the presence of antibiotic-resistant (Pseudomonas) and pathogenic (Vibrio) microorganisms in biofilm under different conditions. The above research deepens our understanding of ARGs enrichment in biofilm and provides important insights into the ecological risks of interactions between ARGs, antibiotics, and microplastic biofilm.

Superhydrophobic Thermoplastic Polyurethane Foam Fabricated by Phase Separation and Silica Coating for Oil-Water Separation.

Oil spills and the presence of oily wastewater have resulted in substantial ecological damage. Superhydrophobic polymer foam with selectivity and adsorption capacity is a promising candidate for efficient oil-water separation. In this study, a method that combines phase separation and silica coating to produce superhydrophobic thermoplastic polyurethane (TPU) foam is proposed. The TPU foam demonstrates superhydrophobicity with a water contact angle of 155.62°, and exhibits a maximum saturated adsorption capacity of 54.11 g g-1 . Furthermore, the foam can be utilized as a filter for oil-water separation, maintaining its filtration efficiency (41.2 m3  m2  h-1 ) even after ten filtration cycles.

Facile Photo and Thermal Two-Stage Curing for High-Performance 3D Printing of Poly(Dimethylsiloxane).

Three-dimensional (3D) printing of poly(dimethylsiloxane) (PDMS) is realized with a two-state curing strategy, i.e., photocuring for additively manufacturing high-precision architectures followed by thermal cross-linking for high-performance objects, taking Sylgard-184 as an example. In the mixture of base and curing agent of Sylgard-184, the photocuring ingredient methacrylated PDMS is incorporated to form hybrid inks with not only high-efficiency UV curing ability but also moderate rheological properties for 3D printing. The inks are then used to additively manufacture high-precision architectures by UV-assisted direct ink writing. Various architectures such as lattices and honeycombs, channels that can be used as microfluidics, and pressure-proof pipes with a feature size of ≈100 µm, can be readily printed. Thereafter, thermal cross-linking at elevated temperature is conducted to obtain the 3D PDMS objects with comparable properties to Sylgard-184. The facile, universal two-stage approach to 3D printing of PDMS can facilitate the development of microfluidics, flexible electronics, soft robots, and so on.

3D Printing of Photocuring Elastomers with Excellent Mechanical Strength and Resilience.

Three-dimensional (3D) printing elastomers, as a combination of transformative technology and widely used materials, have received great demand in many fields. However, commercial photocuring elastomer inks for 3D printing usually exhibit poor mechanical strength, inferior resilience, and lower elongation at break. In this study, photocuring inks that can be employed for digital light processing 3D printing are developed with acryloyl-modified polyethylene glycol (Acryl@PEG). The resultant photocuring inks exhibit not only high tensile strength of 14.1 MPa and elongation of 245.0%, but also excellent resilience (recover to 90.85% after 30 min under the 200% strain). With the photocuring elastomer inks, a variety of architectures including hollow vases, eggs, finger rings, and porous lattices are built with excellent precision, which all could experience large shape deformations repeatedly without any damage, indicating the excellent elasticity, outstanding shape-recovery property, and mechanical stability. The present photocuring elastomer inks for 3D printing are therefore believed to be promising for soft robots, wearable devices, flexible electronics, and many other applications.

Facile Thermally Impacted Water-Induced Phase Separation Approach for the Fabrication of Skin-Free Thermoplastic Polyurethane Foam and Its Recyclable Counterpart for Oil-Water Separation.

Developing a facile large-scale strategy to fabricate polymer foams with excellent wettability and recycling its counterpart for oil-water separation is in urgent demand. Here, a facile template-free thermally impacted water-induced phase separation approach for the fabrication of skin-free thermoplastic polyurethane foam with a water contact angle of 147°, porosity more than 90%, density less than 14 mg cm-3 , and excellent compressibility (>1000 cycles) is proposed. The foams show high efficiency of oil recovery (>98%) during the squeezing and pumping oil-water separation test. Moreover, the used foams could be recycled and reused to form refresh foams without sacrificing their high performance, which makes this method a promising prospect for environmental applications.

Ecological risk assessment and distribution of potentially harmful trace elements in lake sediments of Songnen Plain, NE China.

In order to understand the distribution and the ecological risk of the potentially harmful trace elements (PHTEs) in lake sediments of Songnen Plain, northeast (NE) China, an integrated survey of PHTEs (As, Cd, Cr, Cu, Ni, Pb, Zn and Ti) was conducted in July 2015 in 11 shallow lakes adjacent to Qiqihar and Daqing. The enrichment factor (EF) and Index of geoaccumulation (Igeo) results showed that Cd was obviously enriched in all lakes and reached the moderate pollution level. A comparison of PHTE concentrations in the lake sediments from 2005 to 2015 found the PHTEs pollution status doubled. Multivariate statistical analysis identified the heavy industries of petroleum and steel in the cities close to lakes and excessive agricultural fertilizing in the region as possible pollution sources of the PHTEs. The Håkanson index method (RI) and the sediment quality guidelines (SQGs) were used to assess the potential risk of PHTEs in sediments. The risk degree of 11 lakes had reached a medium level of potential ecological risk except for one lake which had a low potential ecological risk status. The Songnen Plain has been significantly affected by anthropogenic activities and this study provides an effective reference for the environmental protection and management of lakes (heavy metal pollution and control) around the heavy industrial cities of China and the world.

Stratified polymer brushes from microcontact printing of polydopamine initiator on polymer brush surfaces.

Stratified polymer brushes are fabricated using microcontact printing (µCP) of initiator integrated polydopamine (PDOPBr) on polymer brush surfaces and the following surface initiated atom transfer radical polymerization (SI-ATRP). It is found that the surface energy, chemically active groups, and the antifouling ability of the polymer brushes affect transfer efficiency and adhesive stability of the polydopamine film. The stickiness of the PDOPBr pattern on polymer brush surfaces is stable enough to perform continuous µCP and SI-ATRP to prepare stratified polymer brushes with a 3D topography, which have broad applications in cell and protein patterning, biosensors, and hybrid surfaces.

Decompression as a treatment for odontogenic cystic lesions of the jaw.

PURPOSE: To evaluate the effectiveness of decompression as the primary treatment of odontogenic cystic lesions of the jaw involving factors that affect relative shrinking speed and bone regeneration. PATIENTS AND METHODS: A total of 32 patients with odontogenic cystic lesions of the jaw underwent decompression with customized thermoplastic resin stents. Clinical examinations and pre- and postdecompression panoramic radiographs were analyzed. RESULTS: The mean relative speed of shrinkage of radicular cysts (RCs; 3.37 cm(2)/month) was faster than those of keratocystic odontogenic tumors (KCOTs; 2.87 cm(2)/month) and unicystic ameloblastomas (UABs; 2.71 cm(2)/month). The relative shrinking size increased linearly in a time-dependent manner for KCOTs (r = 0.849, P < .001), RCs (r = 0.681, P = .319), and UABs (r = 0.146, P = .730); a similar relation was detected between the primary radiolucent area of cystic lesions before decompression and relative shrinking speed after decompression in KCOTs (r = 0.481, P = .032), RCs (r = 0.260, P = .673), and UABs (r = 0.370, P = .366), but patient age did not affect the relative speed of shrinkage (P > .05). Furthermore, the increase in bone density was more significant in RCs than in KCOTs (P = .026) and UABs (P = .012) after decompression. CONCLUSION: Decompression was effective in reducing odontogenic cystic lesions of the jaw and increasing bone density. For aggressive lesions, secondary definitive surgery was necessary.

Development of a novel membrane-based quorum-quenching microbial isolator for biofouling control: Process performance and microbial mechanism.

Quorum quenching (QQ) can mitigate biofouling in membrane bioreactors (MBRs) by inhibiting cell-to-cell communication. However, it is difficult to maintain long-term QQ activity. Here, a novel microbial isolator composed of tubular microfiltration membranes was developed to separate QQ bacteria (Rhodococcus sp. BH4) from sludge. The time to reach a transmembrane pressure of 50 kPa was delayed by 69.55 % (p = 0.002, Student's t test) in MBR with QQ microbial isolator (MBR-Q), compared to that in the control MBR (MBR-C) during stable operation. The concentration of proteins in the extracellular polymeric substances of sludge was reduced by 20.61 % in MBR-Q relative to MBR-C. The results of the bacterial community analyses indicated less enrichment of fouling-associated bacteria (e.g., Acinetobacter) but a higher abundance of QQ enzymes in MBR-Q than in MBR-C. This environmentally friendly technique can decrease the cleaning frequency and increase the membrane lifespan, thus improving the sustainability of MBR technology.

Blood cellular membrane-coated Au/polydopamine nanoparticle-targeted NIR-II antibacterial therapy.

Bacterial infections are the primary causes of infectious diseases in humans. In recent years, the abuse of antibiotics has led to the widespread enhancement of bacterial resistance. Concerns have been raised about the identification of a common treatment platform for bacterial infections. In this study, a composite nanomaterial was used for near-infrared II (NIR-II) photothermal antibacterial treatment. Red blood cell membrane was peeled and coated onto the surface of the Au/polydopamine nanoparticle-containing aptamer. The composite nanomaterials based on Au/polydopamine exhibit highest photothermal conversion capability. Moreover, these assembled nanoparticles can quickly enter the body's circular system with a specific capability to recognise bacteria. In vivo experiments demonstrated that the composites could kill bacteria from infected blood while significantly reducing the level of bacteria in various organs. Such assemblies offer a paradigm for the treatment of bacterial infections caused by the side effects of antibiotics.

Effects comparison between the secondary nanoplastics released from biodegradable and conventional plastics on the transfer of antibiotic resistance genes between bacteria.

Antibiotic resistance genes (ARGs) have caused widespread concern because of their potential harm to environmental safety and human health. As substitutes for conventional plastics, the toxic effects of short-term degradation products of biodegradable plastics (polylactic acid (PLA) and polyhydroxyalkanoates (PHA)) on bacteria and their impact on ARGs transfer were the focus of this study. After 60 days of degradation, more secondary nanoplastics were released from the biodegradable plastics PLA and PHA than that from the conventional plastics polystyrene (PS). All kinds of nanoplastics, no matter released from biodegradable plastics or conventional plastics, had no significant toxicity to bacteria. Nanoplastic particles from biodegradable plastics could significantly increase the transfer efficiency of ARGs. Although the amount of secondary nanoplastics produced by PHA microplastics was much higher than that of PLA, the transfer frequency after exposure to PLA was much higher, which may be due to the agglomeration of PHA nanoplastics caused by plastic instability in solution. After exposure to the 60 d PLA nanoplastics, the transfer frequency was the highest, which was approximately 28 times higher than that of control. The biodegradable nanoplastics significantly enhanced the expression of the outer membrane pore protein genes ompA and ompC, which could increase cell membrane permeability. The expression levels of trfAp and trbBp were increased by repressed major global regulatory genes korA, korB, and trbA, which eventually led to an increase in conjugative transfer frequency. This study provides important insights into the evaluation of the environmental and health risks caused by secondary nanoplastics released from biodegradable plastics.

Controlled synthesis of transition metal/conducting polymer nanocomposites.

A novel displacement reaction has been observed to occur between conducting polymers (CP) and metal salts which can be used to fabricate nanostructured CP-metal composites in a one-pot manner. Vanadium pentoxide (V(2)O(5)) nanofiber is used during the synthesis as the reactive seeds to induce the nanofibril CP-metal network formation. The CP-metal nanocomposites exhibit excellent sensory properties for hydrogen peroxide (H(2)O(2)) detection, where both high sensitivity and a low detection limit can be obtained. The sensory performance of the CP-metal composite can be further enhanced by a facile microwave treatment. It is believed that the CP-metal nanofibril network can be converted to a carbon-metal network by a microwave-induced carbonization process and result in the sensory enhancement.

A flexible tactile sensor based on piezoresistive thin film for 3D force detection.

This paper presents a flexible tactile sensor with a compact structure based on a piezoresistive thin film and an elastomer for detecting three-dimensional (3D) force. The film contains four independent sensing cells, which were made using a type of piezoresistive ink and a specific pectinate conductive circuit pattern based on the flexible substrate to decrease the coupling effect. The elastomer with a spherical surface is bonded to the surface of the film and transfers the force to the sensing array. A model of 3D force detection based on the proposed sensor was established, and a prototype was designed and developed. Static and dynamic experiments were carried out, and the results show that the range of the prototype is 0-50 N in the z-axis and 0-6 N in the x-axis and y-axis, which with good static and dynamic performance, especially a low coupling effect, validates the mechanism of the proposed sensor and indicates that it has good potential application in robotic grasping.

Licochalcone A inhibits enterovirus A71 replication in vitro and in vivo.

Enterovirus A71 (EV-A71) is one of the main causative agents of hand-foot-mouth disease (HFMD) and causes serious neurological complications. However, no effective therapy is currently available for treating these infections. Therefore, effective drugs to prevent and treat EV-A71 infections are urgently needed. Here, we demonstrated that treatment with Licochalcone A (LCA) significantly inhibited EV-A71 replication in a dose-dependent manner, with an EC50 of 9.30 µM in RD cells and 5.73 µM in Vero cells. The preliminary results on the inhibition mechanism showed that LCA exerted antiviral effects by interfering with the early step of viral replication. We further demonstrated that LCA showed potent antiviral activity against many enteroviruses, including EV-A71 (strain C4), EV-A71 (strain H), and coxsackievirus A16 (CV-A16). Furthermore, LCA could effectively prevent the clinical symptoms and death of virus infected mice and decreased viral load in EV-A71-infected mice. Taken together, our studies showed for the first time, that LCA is a promising EV-A71 inhibitor and provide important information for the clinical development of LCA as a potential new anti-EV-A71 agent.

Polymeric waveguides with embedded micro-mirrors formed by Metallic Hard Mold.

In this paper, we presented fabrication of nickel based metal mold with 45 degrees tilted surfaces on both ends of the channel waveguide through electroplating process. To obtain a precise 45 degrees tilted angle, a 50microm thick SU-8 layer was UV exposed under de-ionized water, with repeatable error control of 0.5 degrees . The polymeric waveguide array with 45 degrees micro-mirrors, which is formed by a UV imprinting method with the fabricated metallic mold, shows total insertion losses around 4dB, propagation loss around 0.18dB/cm and 75% coupling efficiency.

MiR-497-5p Regulates Osteo/Odontogenic Differentiation of Stem Cells From Apical Papilla via the Smad Signaling Pathway by Targeting Smurf2.

Osteo/odontogenic differentiation is a key process of human stem cells from apical papilla (SCAP) in tooth root development. Emerging evidence indicates microRNAs (miRNAs) play diverse roles in osteogenesis. However, their functions in osteo/odontogenic differentiation of SCAP require further elucidation. To investigate the role of miRNA in SCAP osteo/odontogenic differentiation and underlying mechanisms, miRNA microarray analysis was performed to screen differentially expressed miRNAs between control and osteo/odontogenic-induced group. Quantitative real-time PCR (qRT-PCR) and western blot were used to detected osteo/odontogenic differentiation-related markers and possible signaling pathway SCAP-associated genes. Alizarin Red Staining (ARS) were applied to evaluated osteogenic capacity. The results showed that miR-497-5p increased during SCAP osteo/odontogenic differentiation. Overexpression of miR-497-5p enhanced the osteo/odontogenic differentiation of SCAP, whereas downregulation of miR-497-5p elicited the opposite effect, thus suggesting that miR-497-5p is a positive regulator of the osteo/odontogenic differentiation of SCAP. Bioinformatic analysis and dual luciferase reporter assay identified that SMAD specific E3 ubiquitin protein ligase 2 (Smurf2) is a direct target of miR-497-5p. Further study demonstrated that Smurf2 negatively regulates SCAP osteo/odontogenic differentiation, and silencing Smurf2 could block the inhibitory effect of the miR-497-5p inhibitor. Meanwhile, pathway detection manifested that miR-497-5p promotes osteo/odontogenic differentiation via Smad signaling pathway. Collectively, our findings demostrate that miR-497-5p promotes osteo/odontogenic differentiation of SCAP via Smad signaling pathway by targeting Smurf2.

Effect of syringic acid incorporation on the physical, mechanical, structural and antibacterial properties of chitosan film for quail eggs preservation.

The physical mechanics and structural properties of composite films based on chitosan and syringic acid (SA) were studied in this study. The results indicated that the addition of SA made the chitosan-SA films exhibited higher density, water solubility and opacity, but the water vapor permeability and water content were decreased. In addition, Chitosan-SA films had a significant antibacterial effect on test bacteria. The surface and cross-section of chitosan-SA films were more uniform and smoother when combined with 0.25% and 0.5% 0f SA. The FT-IR and XRD spectra of the chitosan-SA film indicated that the interaction between chitosan and SA may be non-covalent, and DSC indicated that the thermal stability of the composite film was reduced. In summary, the modified color, increased bacteriostatic and water-blocking properties, as well as the slight changes in mechanical properties indicated that the addition of SA may contribute to extend the shelf life of the food. Thus, chitosan-SA films incorporating 0.25% and 0.5% of SA can be further explored as active packing materials for food preservation. The composite film was used for the preservation of quail egg coatings, and it was found that 0.25% and 0.5% of the coating film had a good preservation effect.

Direct ink writing with high-strength and swelling-resistant biocompatible physically crosslinked hydrogels.

The three-dimensional (3D) printing of hydrogels has great potential for biomedicine applications. However, it is very rare to find suitable printable materials with high strength and swelling resistance that can offer high performance. To address this challenge, this paper demonstrates the fabrication of tailored hydrogel structures by using the direct ink writing (DIW) of hybrid hydrogel inks (polyvinyl alcohol (PVA) and κ-carrageenan) with outstanding rheology. The freezing and thawing processes following DIW induce the formation of physically crosslinked networks due to the crystallinity of PVA, and thus enhance the mechanical properties and swelling resistance of the printed architectures. The resultant hydrogels exhibit excellent cytocompatibility, and most importantly, cells not only attach well to the surface of the hydrogels, but also stretch into the spaces in the grid architectures, providing appropriate microenvironments for cell culture. The physically crosslinked hydrogels, with high strength, outstanding swelling resistance, biocompatibility, and good compatibility with the DIW technique, offer many opportunities in fields such as tissue engineering, drug delivery, bone regeneration and implant medicine.

Influence of hydrogen bond accepting ability of anions on the adsorption performance of ionic liquid surface molecularly imprinted polymers.

To illuminate the influence mechanism of anionic structure of ionic liquids (ILs) on the adsorption performance of surface molecularly imprinted polymers (MIPs), in this work, six newly designed MIPs were prepared on the surface of amino-poly(styrene-divinylbenzene) particles by using imidazolium ILs with the same cation [C4mim]+ but different anions (Cl, CH3SO3, PF6, BF4, C4F7O2, C4F9SO3) as template molecules, methacrylic acid as functional monomer, and ethylene dimethacrylate as cross-linker. The resulting MIP materials were characterized by IR and SEM, and the influence of hydrogen bond accepting ability of anions on the adsorption performance of the MIPs for the ILs was investigated in acetonitrile. It was found that adsorption capacity of the MIPs towards the ILs decreased in the order MIP[C4mim][Cl] > MIP[C4mim][C4F7O2] ≥ MIP[C4mim][BF4] and MIP[C4mim][CH3SO3] > MIP[C4mim][C4F9SO3] > MIP[C4mim][PF6], which is in good agreement with the ability of anions of the ILs to form hydrogen bonds. Ultraviolet, 1H-NMR and 35Cl-NMR spectroscopy was then used to study the interactions of anions of the ILs with the functional monomer. It was found that the hydrogen bond interaction between anions of the ILs and acidic proton of the functional monomer was the main driving force for the high adsorption selectivity of the imprinted polymers, and the stronger hydrogen bond interaction indicates higher binding capacity and higher selectivity of the polymers towards the ILs. It was also verified that the ILs with stronger hydrogen bond accepting ability of anions could be selectively extracted by the corresponding IL-MIPs. These results may provide new insight into the recognition mechanism of MIPs for ILs, and are also useful for the rational design of this new class of imprinting materials.

Identification of anthropogenic influences on water quality of rivers in Taihu watershed.

Surface water bodies are progressively subjected to stress as a result of anthropogenic activities. This study assessed and examined the impact of human activities on spatial variation in the water quality of 19 rivers in the Taihu watershed. Concentrations of physicochemical parameters of surface water quality were determined at the mouth of each river during the period of 2000-2004. Multivariate statistical techniques were applied to identify characteristics of the water quality in the studied rivers. The results showed that rivers strongly influenced by household wastewater have the highest concentrations of nutrients (TN and TP). Moreover, rivers in the vicinity of a metropolis presented low dissolved oxygen (DO) levels. However, organic-chemical pollution (petroleum and volatile phenolics) was identified with high localization. Two rivers influenced by sewage from industry and ships were distinguished from other rivers with high values of petroleum. The Taige channel, a river located in Changzhou City that is strongly influenced by wastewater from industry, was characterized with an extraordinarily high value of volatile phenolics. Rivers passing through countries, especially through hilly countries were characterized with high DO contents and low nutrient and organic-chemical pollution, suggesting that agriculture puts less pressure on water quality in adjacent rivers. Therefore, more effort should be made in controlling point pollution to restore water quality in rivers adjacent to cities.