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Hierarchical porous carbon materials with high surface area are facilely prepared by directly carbonizing carex meyeriana without any extra activation procedure. The as-prepared porous carbon samples possess high Brunauer–Emmett–Teller (BET) surface areas (in the ~ 518–742 m2 g−1 range) and unique hierarchical porous structure containing macropore channels and mesopores and micropores developed in the wall of macropores. These intriguing characteristics make the as-prepared hierarchical porous carbon samples a promising electrode material for supercapacitors. The capacitive performance was measured in the three-electrode system with 6 M KOH electrolyte. The hierarchical porous carbon prepared at the carbonization temperature of 1000 °C presents a high specific capacitance of 178.6 F g−1 at a current density of 0.5 A g−1, a good rate performance ( about 65.2% retention ratio at the current density of 20 A g−1), and an excellent cycling stability (no obvious performance fading after 10,000 cycles). In addition, the fabricated two-electrode device achieves an energy density of 4.33 Wh kg−1 at a high power density of 5 kW kg−1. These results provide a green and facile method to synthesize the electrode material from biomass for high-performance supercapacitors.

To explore the water resistance properties of lime soil ground, the physical and mechanical properties of lime soil with 5%, 10%, 15% and 20% lime content after long-term water immersion were studied by conducting unconfined compressive tests, density tests and water absorption tests. The results show that the stress–strain relationship curves of the lime soil during immersion are of the strain-softening type. The curves are multistage and nonlinear with evident peak values, and the lime soil achieves ductility and toughness with an increase in immersion time. The failure modes of the lime soil samples mainly include single slope shear failures, brittle splitting failures and conjugate shear failures, which are mainly affected by the lime content and immersion time. The strength of the lime soil decreases sharply in a short time while interacting with water. The strength slowly increases to 50.07–69.15% of the initial strength after immersion for a long time, i.e., still far less than the initial strength without immersion. Under long-term immersion, the water absorption of the lime soil increases gradually at the initial stage of immersion and then increases to a stable value of 16.76–21.67%. The change law of the wet density is essentially controlled by the water absorption. The strength of lime soil decreases significantly, and the water resistance capacity is poor after soaking; lime soil with 15% lime content has better engineering properties. It is recommended to apply lime soil with 15% lime content in practical engineering with a volume ratio of lime to soil of 3:7 and to avoid using lime soil materials in immersed or other dry-humid environments.

Hierarchical porous carbon arrays (HPCAs) are facilely produced by directly carbonizing Carex meyeriana through a self-activated and self-template process. The morphology analysis and nitrogen sorption measurements reveal that the obtained HPCAs have a large specific surface area and unique hierarchical pore structure comprising macropore channel arrays and micropores and mesopores developed on the wall of macropore channels. The HPCA electrodes are subsequently prepared by depositing HPCAs to the fluorine-doped tin oxide conductive substrate. Electrochemical tests demonstrate that the HPCA electrode shows a superior electrocatalytic activity for the regeneration of the I–/I3– electrolyte. The superior electrocatalytic activity of HPCA electrodes is mainly due to the combined effect of unique hierarchical pore architecture and large surface area, which facilitates the electrolyte diffusion and provides the abundant effective electrocatalytic active sites. Under 1 sun illumination, the HPCA electrode-based dye-sensitized solar cell displays a gratifying conversion efficiency of 6.45%, which is close to that based on commonly used Pt electrodes.

To meet the increased performance and cost requirements of commercial supercapacitor, a N and O self-doped hierarchical porous carbon is fabricated via a green and simple self-activation route utilizing leaves of wild hollyhock as raw materials. Comparing to commercial activated carbon, the reported material exhibits some marked merits, such as simple and green fabrication process, low cost, and superior capacitance performance. The specific surface area of the obtained N and O co-doped hierarchical porous carbon arrives 954 m2 g−1, and the content of the self-doped nitrogen and oxygen reaches 2.64 at.% and 7.38 at.%, respectively. The specific capacitance of the obtained material reaches 226 F g−1 while the specific capacitance of the symmetric supercapacitor arrives 47.3 F g−1. Meanwhile, more than 90.3% of initial specific capacitance is kept under a current density of 20 A g−1, and no arresting degradation is observed for capacitance after 5000 times cycle, perfectly demonstrating the excellent cycle and rate capability of the obtained material. The obtained N and O co-doped hierarchical porous carbon are expected to be an ideal substitution for commercial activated carbon.

Microbial disinfection associated with medical device surfaces has been an increasing need, and surface modification strategies such as antibacterial coatings have gained great interest. Here, we report the development of polydopamine-ferrocene (PDA-Fc)-functionalized TiO2 nanorods (Ti-Nd-PDA-Fc) as a context-dependent antibacterial system on implant to combat bacterial infection and hinder biofilm formation. In this work, two synergistic antimicrobial mechanisms of the PDA-Fc coating are proposed. First, the PDA-Fc coating is redox-active and can be locally activated to release antibacterial reactive oxygen species (ROS), especially ·OH in response to the acidic microenvironment induced by bacteria colonization and host immune responses. The results demonstrate that redox-based antimicrobial activity of Ti-Nd-PDA-Fc offers antibacterial efficacy of over 95 and 92% against methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli (E. coli), respectively. Second, the photothermal effect of PDA can enhance the antibacterial capability upon near-infrared (NIR) irradiation, with over 99% killing efficacy against MRSA and E. coli, and even suppress the formation of biofilm through both localized hyperthermia and enhanced ·OH generation. Additionally, Ti-Nd-PDA-Fc is biocompatible when tested with model pre-osteoblast MC-3T3 E1 cells and promotes cell adhesion and spreading presumably due to its nanotopographical features. The MRSA-infected wound model also indicates that Ti-Nd-PDA-Fc with NIR irradiation can effectively eliminate bacterial infection and suppress host inflammatory responses. We believe that this study demonstrates a simple means to create biocompatible redox-active coatings that confer context-dependent antibacterial activities to implant surfaces.

Carbon electrode-based all-inorganic perovskite solar cells (PSCs) without hole-transport materials are attracting extensive interest due to their low cost, simple fabrication process, and high stability. Nevertheless, the conversion efficiency of carbon electrode-based PSCs is far from satisfactory owing to serious charge recombination at the inorganic perovskite/carbon interface, which mainly derives from the mismatched energy level between the inorganic perovskite film and carbon layer. Herein, a hydrophobic CuSCN film is introduced into carbon electrode-based CsPbIBr2 all-inorganic PSCs as a multifunctional interlayer between the CsPbIBr2 perovskite film and carbon electrode to form a favorable interfacial energy level alignment and protect the CsPbIBr2 perovskite from ambient moisture. It is found that introducing a CuSCN interlayer can not only enhance the hole extraction and suppress the charge recombination in carbon electrode-based CsPbIBr2 all-inorganic PSCs, but also improve the stability of the cell. Moreover, the very strong interaction between SCN−1 and Pb2+ remarkably reduces the surface defects of the CsPbIBr2 perovskite film. Consequently, the device with the CuSCN interlayer displays an improved power conversion efficiency of 7.30% in comparison with 5.19% for the device without the CuSCN interlayer and an excellent long-term stability under the ambient conditions.

The contamination of chronic wound with bacteria especially methicillin-resistant Staphylococcus aureus (MRSA) is considered as the major factor interferencing normal wound healing. There still remain great challenges in developing safe and effective wound dressings with wide-spectrum antibacterial functions. Alginate hydrogel is a common dressing for wound treatment. Copper is one of the trace elements in human body with inherent antibacterial activity. Traditional methods for preparing a structure-controlled copper-alginate antibacterial matrix are difficult however, due to the fast and uncontrolled gelation between alginate and metal ions. In this work, we report an electrodeposition method for rapid fabrication of copper cross-linked alginate antibacterial films (Cu2+-Alg) with controlled structure and copper content, which is relied on an electrical signal controlled release of copper ions from the reaction of insoluble salt Cu2(OH)2CO3 and the generated protons via water electrolysis on anode. The results prove that the physical structure and chemical composition of the electrodeposited Cu2+-Alg films can be continuously modulated by the imposed charges during electrodeposition. In vitro tests demonstrate the film has Cu2+ content-dependent bactericidal activities. Film’s cytocompatibility is well controlled by the imposed charges for Cu2+-Alg fabrication. The MRSA infected wound model in vivo also indicates that Cu2+-Alg film can effectively eliminate bacterial infection and suppress host inflammatory responses. We believe this study demonstrates a convenient and controllable strategy to fabricate alginate antibacterial dressings with potential applications for infected wound treatment. More broadly, our work reveals electrodeposition is a general and simple platform to design alginate films with versatile functions.

Hemp fiber, as a kind of renewable textile fiber, has evoked much interest due to its excellent properties in various fields. It has been investigated in just one step to finish the process of chemo-enzymatic degumming and modification of hemp fiber, which is done in acetic acidsodium acetate buffer solution containing laccase (6.0 g), hemicellulase (0.3 g) and 2,2,6,6-tetramethylpiperidine-1-oxyl radical (0.3 g) under a mild condition (pH 5, 50C). The degumming effects of different batches of raw hemp fibers were also discussed. We found that the residual rate, fineness, length and tensile strength of degummed fiber were 15–27%, 9.00–24.00 dtex, 14.00–19.00 cm and 3.8–5.1 cN/dtex, respectively. Meanwhile, some of the oxidized functional groups were introduced into degummed fiber, which improved the moisture absorption and water retention value of the hemp fiber. The hemp fiber treated by this process could be further improved and then applied in the textile industry.

Ultra-high density large-sized Al:ZnO sputtering targets were prepared by hot isostatic pressing(HIP). Studies were conducted on the characteristics of the microstructure of the targets and the photoelectric properties of the deposited film prepared by medium-frequency magnetron sputtering. Experiments showed that, compared to 98% density target, HIP process had no apparent influence on the change of grain dimension of the targets. However, a reduction of the quantity and size of the porosities in the target matrix was recognized and led to an improvement in the uniformity of resistance and thickness and IR transmittance of the deposited film. In this paper, the favorable machining allowance associated to the thickness of the HIPed targets, due to the oxygen-loss layer, was suggested by developing the empirical formula.

All-inorganic CsPbIBr2 perovskite has been regarded as a promising candidate for perovskite solar cells (PSCs) considering its suitable bandgap and high stability. However, the poor quality of CsPbIBr2 film greatly impedes the performance improvement of CsPbIBr2-based PSCs. Herein, we report a facile strategy to improve the quality of CsPbIBr2 perovskite film by introducing cellulose acetate (CA) into the perovskite precursor solution. The interaction between the oxygen functional groups of CA and Pb2+ and the increase of the precursor viscosity induced by CA addition can slow down the crystallization rate of CsPbIBr2 perovskite, which allows the perovskite films have enough time to form high-quality crystal structure. By optimizing the amount of CA (the optimal amount of CA is 2.5 wt%), a high-quality CsPbIBr2 perovskite film with high crystallinity, large grain size, and smooth surface is obtained. As consequence, the carbon-based PSC with a structure of FTO/TiO2/perovskite/carbon using the CsPbIBr2 perovskite film with 2.5 wt% CA achieves a champion efficiency of 7.52%, which is increased by 40.8% compared with the cell based on pure CsPbIBr2 perovskite film. In addition, the PSC based on CsPbIBr2 film with CA exhibits an excellent long-term stability under both ambient condition and high-humidity environment.

High liquid limit clay is widely distributed in China with its special properties. GDS dynamic triaxial test was carried out to investigate its dynamic response under vehicle load in the article. The response law of the accumulative strain and plastic modulus of the high liquid limit clay under different dynamic stress amplitude, cycle times, compaction, water content and confining pressure was attained. The research results have important reference value for the design of high liquid limit clay subgrade.

Considerable interest has been devoted to developing nanoscale biomass materials as adsorbents for wastewater treatment. A facile route was proposed to prepare cellulose-based composite nanofibers via electrospinning of cellulose acetate with organically modified montmorillonite, followed by deacetylation. The composite nanofibers are suitable for metal adsorption given their reasonably high selectivity in removing Cr 6+ ions from aqueous solution. The effects of experimental parameters, including solution pH, temperature, and contact time, on the removal of Cr 6+ ions were determined in a batch system to optimize the adsorption conditions. Results from this study may provide a promising biosorbent that can be used as an emerging material in large-scale adsorption of heavy metal ions.

Photothermal therapy (PTT) that utilizes phSUPPotothermal conversion agents (PTC) to ablate tumor under NIR light irradiation has attracted increasing attention due to its excellent therapeutic efficacy and improved target selectivity. Herein, a novel core-shell nanoparticle based on disulfide-crosslinked poly(methacrylic acid) (PMAA) layer coated polydopamine (PDA) particle has been successfully synthesized by precipitation polymerization. For these PDA@PMAA composite nanoparticles, PDA core exhibits high photothermal efficacy, meanwhile, the redox-labile PMAA shell serves as carriers to encapsulate anticancer drugs and selectively release them. Due to the characteristic of the disulfide bond, PMAA shell occurs at selective degradation as well as controlled drug release upon entering cancer cells. Moreover, the DOX-loaded PDA@PMAA nanoparticles demonstrated a synergistic effect, which shows a significantly improved inhibition effect against cancer cells by the combination of photothermal therapy and traditional chemotherapy with low drug dosage and short laser irradiation in an in vitro study. Electronic supplementary material The online version of this article (10.1186/s11671-019-3027-6) contains supplementary material, which is available to authorized users.

Membrane separation is recognized as one of the most effective strategies to treat the complicated wastewater system for economic development. However, serious membrane fouling has restricted its further application. Inspired by sphagnum, a 0D/2D heterojunction composite membrane is engineered by depositing graphitic carbon nitride nano/microspheres (CNMS) with plentiful wrinkles onto the polyacrylic acid functionalized carbon nanotubes (CNTs-PAA) membrane through hydrogen bond force. Through coupling unique structure and chemistry properties, the CNTs-PAA/CNMS heterojunction membrane presents superhydrophilicity and underwater superoleophobicity. Furthermore, thanks to the J-type aggregates during the solvothermal process, it is provided with a smaller bandgap (1.77 eV) than the traditional graphitic carbon nitride (g-C3 N4 ) sheets-based membranes (2.4-2.8 eV). This feature endows the CNTs-PAA/CNMS membrane with superior visible-light-driven self-cleaning ability, which can maintain its excellent emulsion separation (with a maximum flux of 5557 ± 331 L m-2 h-1 bar-1 and an efficiency of 98.5 ± 0.6%), photocatalytic degradation (with an efficiency of 99.7 ± 0.2%), and antibacterial (with an efficiency of ≈100%) ability even after cyclic experimental processes. The excellent self-cleaning performance of this all-in-one membrane represents its potential value for water purification.

Uniaxially aligned cellulose nanofibers (CNFs), which are fabricated by electrospinning of cellulose acetate derived from bamboo cellulose (B-CA) followed by deacetylation, were used as reinforcements to make optically transparent composite films. We examined the effects of B-CA concentration and electrospinning parameters (e.g. spinning distance, and collection speed) on fiber morphology and orientation, which act on mechanical-to-optical properties of the CNFs-reinforced composites. Consequently, the resultant composite film exhibits high visible-light transmittance even with high fiber content, as well as improved mechanical properties. The understanding obtained from this study may facilitate the development of novel nanofibrous materials for various optical uses.

Cellulose acetate derived from bamboo cellulose (B-CA) was prepared via a typical acetylation process and used to fabricate the aligned electrospun nanofibrous membranes (ENMs). A solvent post-treatment by soaking the B-CA ENMs in a mixture solution with different ethanol/acetone volume ratios was also performed to improve the mechanical properties of the membranes. In this study, we showed that this approach can enhance the bonding in the fiber membranes by solvent-induced fusion of inter-fiber junction points and change the degree of molecular orientation of the polymer, which are both considered to have important influences on the mechanical properties of ENMs. The treated membranes exhibited a significant enhancement in mechanical strength while retaining high hydraulic permeability. Increased performances will improve the prospects of ENMs as an emerging material in the filtration space for handling and scale-up manufacturing.

Carbon-based CsPbIBr2 inorganic perovskite solar cells (PSCs) have emerged as one of the most promising photovoltaic devices owing to their excellent stability and simple fabrication process. Nevertheless, the efficiency of state-of-the-art carbon-based CsPbIBr2 PSCs is far from satisfactory due to the poor quality of CsPbIBr2 perovskite film. Herein, we prepare the high-quality CsPbIBr2 perovskite film through a one-step spin-coating method by optimizing both the substrate pre-heating temperature and the post-annealing temperature. The optimization of the substrate pre-heating and post-annealing temperatures greatly improves the coverage and crystallinity of CsPbIBr2 perovskite films, leading to enhanced light harvest and suppressed charge recombination. With the CsPbIBr2 perovskite film prepared at the optimized substrate pre-heating and post-annealing temperatures, the fabricated carbon-based CsPbIBr2 PSC with a simple structure of FTO/TiO2/CsPbIBr2/carbon exhibits a gratifying conversion efficiency of 8.10% with a high open-circuit voltage of 1.27 V. Moreover, the fabricated carbon-based CsPbIBr2 PSC without any encapsulation shows an excellent long-term stability under ambient condition.

Herein, graphene nanoplatelets (GNPs) are incorporated into carbon electrode to fabricate carbon-based CsPbBr3 inorganic PSCs with the FTO/TiO2/CsPbBr3/carbon configuration. Steady-state photoluminescence and electrochemical impedance spectroscopy measurements indicate that the incorporation of GNPs into carbon electrode remarkably enhances the hole extraction and decreases the interfacial charge recombination in carbon-based PSCs compared with unincorporated one. Consequently, the CsPbBr3 PSC with GNP (33.3 wt%)-incorporated electrode exhibits much higher photovoltaic performance than the device with pristine carbon electrode with the efficiency being increased from 4.84% to 6.48%. In addition, the excellent long-term stability of PSC with carbon electrode is also measured under ambient condition.

Vanadium carbide/titanium carbide (VC/TiC) superlattice films were synthesized by magnetron sputtering method. The effects of modulation period on the microstructure evolution and mechanical properties were investigated by EDXA, XRD, HRTEM and nano-indentation. The results reveal that the VC/TiC superlattice films form an epitaxial structure when their modulation period is less than a critical value, accompanied with a remarkable increase in hardness. Further increasing the modulation period, the hardness of superlattices decreases slowly to the rule-of-mixture value due to the destruction of epitaxial structures. The XRD results reveal that three-directional strains are generated in superlattices when the epitaxial structure is formed, which may change the modulus of constituent layers. This may explain the remarkable hardness enhancement of VC/TiC superlattices.

Wound dressings play important roles in the management of wounds, and calcium cross-linked alginate (Ca2+-Alg) is a commonly used hydrogel that is adapted for wound treatment. However, conventional methods for fabricating Ca2+-Alg hydrogels can be tedious and difficult to control because of the rapid Ca2+-induced gelation of alginate. In this study, An electrodeposition method was used to rapidly and controllably fabricate Ca2+-Alg films for wound treatment. Several measures of film growth (e.g., thickness and mass) are shown to linearly correlate to the imposed charge transfer at the electrode. Similarly, this charge transfer was also observed to control important physicochemical wound healing properties such as water uptake and retention capacity. Furthermore, a wound healing animal test was performed to evaluate the performance of this electro-fabricated calcium alginate film for wound treatment. This in vivo study demonstrated that wounds dressed with an electro-fabricated Ca2+-Alg film closed faster than that of untreated wounds. Further, the new dermis tissue that formed was composed of reorganized and stratified epithelial layer, with fully developed connective tissue, hair follicle, sebaceous glands as well as aligned collagen. Therefore, our study indicates that this electrofabrication method for the rapid and controlled preparation of alginate film could provide exciting opportunities for wound treatment. More broadly, this study demonstrates the potential of electrochemistry for the fabrication of high performance polymeric materials. Here we report a rapid and controllable fabrication of free-standing alginate films by coupling anodic electrodeposition with subsequent peeling of deposited materials for wound dressing.

Stearic and oleic acid-coated Fe3O4 nanoparticles were dispersed in decahydronaphthalene (DN). This oil phase was dispersed in water using ternary graft copolymer poly(glycidyl methacrylate)-graft-[polystyrene-ran-(methoxy polyethylene glycol)-ran-poly(2-cinnamoyloxyethyl methacrylate)] or PGMA-g-(PS-r-MPEG-r-PCEMA) to yield capsules. The walls of these capsules were composed of PCEMA chains that were soluble in neither water nor DN, and the DN-soluble PS chains stretched into the droplet phase and the water-soluble MPEG chains extended into the aqueous phase. Structurally stable capsules were prepared by photolyzing the capsules with UV light to cross-link the PCEMA layer. Both the magnetite particles and the magnetite-containing capsules were superparamagnetic. The sizes of the capsules increased as they were loaded with more magnetite nanoparticles, reaching a maximal loading of ~0.5 mg of ligated magnetite nanoparticles per mg of copolymer. But the radii of the capsules were always100 nm. Thus, a novel nanomaterial--superparamagnetic-oil-filled polymer nanocapsules--was prepared. The more heavily loaded capsules were readily captured by a magnet and could be redispersed via shaking. Although the cross-linked capsules survived this capturing and redispersing treatment many times, the un-cross-linked capsules ruptured after four cycles. These results suggest the potential to tailor-make capsules with tunable wall stability for magnetically controlled release applications.

A series of novel thermosensitive macroporous poly (ethylene glycol) (PEG)-co-poly(N-isopropylacrylamide) (PNIPAAm)-co-poly (e-caprolactone) (PCL) hydrogels were synthesized via in situ free radical polymerization. Poly(ethylene glycol diacrylate) (PEGDAc) and poly(e-caprolactone diacrylate) (PCLDAc) were prepared as macrocrosslinkers. All compounds were investigated by Nuclear Magnetic Resonance (NMR) and Fourier transform-infrared spectroscopy (FT-IR). Differential Scanning Calorimetry (DSC) results showed the lower critical solution temperatures (LCSTs) of the gels were at around 31°C. The macroporous gels not only had considerable swelling ratios, but also exhibited rapid swelling kinetics and response sensitivity. Above mentioned hydrogels showed a remarkable oscillatory swelling–deswelling transition, making them have potential application in long-term drug delivery. POLYM. ENG. SCI., 55:223–230, 2015. © 2014 Society of Plastics Engineers

An amphiphilic binary graft copolymer polysulfone-graft-[poly(methyl methacrylate)-random-poly(acrylic acid)], PSf-g-(PMMA-r-PAA), was synthesized via a combination of atom transfer radical polymerization (ATRP) and click chemistry. This copolymer and polysulfone (PSf) were used to prepare porous membranes through the phase inversion method, which involved dissolving the polymers in a common solvent N-methyl pyrrolidone (NMP), casting the solution onto a glass plate to obtain a film, and subsequently immersing this film into a coagulant (a mixture of dimethylformamide and water at a given pH). The surfaces of the membrane and its pore walls were covered by the copolymer, and these surfaces were enriched with PAA domains due to the immiscibility of PAA and PSf and the miscibility of PMMA and PSf. More specifically, while the hydrophobic PMMA component served as an anchor to fix the graft copolymer onto the PSf bulk substrate, the hydrophilic PAA component assembled and became exposed at the surfaces of the membrane and the pore walls. Factors influencing this surface AA concentration or carboxyl group content (CGC) enrichment and the surface and pore morphologies of the membranes include the ratio between the amount of the copolymer and PSf in the mixture, the solvent quality of the coagulant for PSf, and the temperature as well as the pH of the coagulant. These factors have been systematically adjusted to optimize the hydrophilization of the PSf membrane and the resultant membranes have been characterized by water contact angle (WCA) measurements, scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). Optimization of the phase inversion process yielded membranes with nearly complete surface coverage by PAA, even when the graft copolymer represented only 8 wt% of the membrane's composition. The hydrophilized membranes exhibited increased water flux and even pH-responsive water flow without adversely affecting their mechanical properties. In addition, these hydrophilic membranes exhibited long-term stability. Therefore, this novel binary amphiphilic graft copolymer-based approach for membrane modification may be of commercial value.

Combined with the focusing schlieren and dynamic pressure measurement technology, the flow field and nozzle wall pressure were experimentally measured, under the different nozzle pressure ratios (NPR) of the single expansion ramp nozzle (SERN). Time and frequency domain analysis provide unsteady flow characteristics within the nozzle. The results show that the flow field structure inside SERN is asymmetry. The flow separation mode on the upper wall of the nozzle is restricted shock separation (RSS), while on the lower wall is free shock separation (FSS); in RSS mode, the pressure on the wall near the outlet sharply oscillated relative to FSS mode. Near separation point, the shock motion exhibits obvious low-frequency characteristics, and the separated shear layer has an influence on the wall pressure near the nozzle exit.

Under the conditions of nozzle pressure ratio (NPR) of 2.79, 2.82 and 2.95, the flow field was observed by dynamic pressure measurement and focusing schlieren technique, and the flow separation characteristics of a planar convergent-divergent nozzle were studied. The results show that as the NPR increases, the nozzle flow structure changes from asymmetric to a symmetrical configuration. Under the condition of NPR=2.79, the flow in the nozzle goes obviously downward to the bottom wall of the nozzle, and the restricted shock separation (RSS) occurs on the bottom wall; under the condition of NPR=2.82 and NPR=2.95, the flow in the nozzle tends to be symmetrical, RSS appears on both the top and bottom walls. Based on spectrum analysis, it is found that there is obvious low-frequency oscillation characteristics near the separation point.

Poly(N-isopropyl acrylamide) (PNIPAAm)-graft-poly(ethylene oxide) (PEO) hydrogels crosslinked by poly(ϵ-caprolactone) diacrylate were prepared, and their microstructures were investigated. The swelling/deswelling kinetics and compression strength were measured. The relationship between the structure and properties of hydrogel are discussed. It was found that the PEO comb-type grafted structure reduced the thermosensitivity and increased the compression strength. The addition of poly(ϵ-caprolactone) (PCL) accelerated the deswelling rate of the hydrogels. Meanwhile, the entanglement of PCL chains restrained the further swelling of the network of gels. The PCL crosslinking agent and PEO comb-type grafted structure made the behavior of the hydrogels deviate from the rubber elasticity equations. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

A novel functional material was fabricated by combining levofloxacin microspheres with viscose nonwoven fabrics. The complex microspheres were made by w/o emulsion crosslinking technique. The morphologies of both microspheres and fabric composite were investigated by SEM. The drug release property was evaluated by UV. The antibacterial activity and cytotoxicity were tested by spread plate and cell culture method. The results showed that the microspheres had spherical shape and could be embedded into the viscose fabrics. The levofloxacin was released gradually within 168 hours and its release kinetics corresponded to diffusion-relaxation model. In addition, the antibacterial activity of the fabric was increased with prolonged drug releasing time and the complex fabrics had no obvious cytotoxicity. The functional material has great potential to be used as a wound dressing with antibacterial property.

The aim of the study was to investigate the grafting process of β-cyclodextrin onto chitosan fibers via epichlorohydrin as a crosslinking agent. The parameters influencing the efficiency of the grafting reaction were studied by L9 (34) orthogonal test. The amounts of β-cyclodextrin grafting onto the treated fibers were estimated in terms of levofloxacin content. The optimum process was found to be epichlorohydrin 0.64 ml, temperature25°C, post-reaction time 48h, pre-reaction time 4.5h when chitosan fibers were 0.48g. In the case, the inclusion amount of levofloxacin was 1.792mg/g, and the releasing amount was 0.845mg/g at 35°C. The modified and unmodified fibers were characterized by FTIR Spectroscopy , which indicated that β-CD grafted with chitosan fibers were prepared successfully.

The bond length of 4HeH+ resulting from collision-induced destruction is measured at 1.4420 MeV using the Coulomb Explosion Technique. The measured bond length of 4HeH+ is 0.094±0.003nm. The bond length of 4HeH+ obtained with our radio frequency (RF) ion source is larger than that obtained with a duoplasmatron ion source at Argonne National Laboratory (ANL), but the bond lengths of H2+ and H3+obtained separately by ANL and by us with the two different ion sources are consistent with each other, which implies that there exists an ion source effect on the bond length of 4HeH+. The main reason why the 4HeH+ bond lengths obtained by the two different ion sources are different is also discussed.

This paper presents a microfluidic mixing module array developed for bio-fluid/chemical delivery and mixing. Vortex micropumps, microchannels and pillared-surface diaphragm (PSD) active micromixers were successfully integrated into a single polymer-based microfluidic chip, consisting of three mixing modules. The pumping characteristics of the vortex micropump were investigated with both analytical and experimental results. Experiments were also conducted to examine the factors affecting the PSD-based mixing. The integrated mixing module further demonstrated the feasibility of chemical mixing and concentration control. An integrated fluidic system was shown successfully to deliver bio-fluid for real-time SPR based detection. A computer-controlled fluid manipulation system is also proposed for the real-time microfluidic operation control. The digitally controllability of the pumping and mixing operations could potentially improve the accuracy and efficiency, and hence, the functionality of the integrated microfluidic system.

We report here a simple and reproducible strategy for fabricating highly durable and robust superhydrophobic cotton fabrics (SCFs) from a series of functional diblock copolymers. These diblock copolymers consisted of both poly(glycidyl methacrylate) (PGMA) and poly(2,2,2-trifluoroethyl methacrylate) (PTFEMA) blocks that were synthesized via sequential atom transfer radical polymerization (ATRP). While the PTFEMA block provides the low surface free energy, the PGMA block serves as an anchor and forms covalent bonds with the surfaces of cotton fibers. These covalent bonds are formed via the epoxy ring-opening reaction between the epoxy groups of the PGMA block and the hydroxyl groups on the surface of the cotton fiber, and self-crosslinking of epoxy groups from PGMA chains. Structures exhibiting nano- and microscale roughness were created in one-step by combining copolymer-based nanobumps onto surfaces of micro-sized fibers of the cotton fabric, as confirmed by SEM and AFM analysis. The modified cotton fabrics show excellent water repellency with water contact angles (WCAs) of ∼163° and water sliding angles (WSAs) of ∼3° under optimized conditions. Since the low-fluorinated PTFEMA chains are chemically bound to the cotton fibers, the SCFs possess long-term stability, ultra-high durability and robustness. In particular, these SCFs withstood mechanical abrasion by sandpaper, strong laundering conditions, ultrasonication treatment in tetrahydrofuran (THF) or trifluorotoluene (TFT), soaking in a wide range of organic solvents, as well as acidic and basic aqueous solutions, exposure to UV-irradiation and even refluxing in TFT or THF.

The structure of surface layer of monocrystalline Si by implanting nitrogen cluster ions N+10 was transformed directly the nanocrystalline, which led to the change in optical properties of monocrystalline Si. Excited by the ultraviolet light of 250—320nm, the sample showed a clear luminescence band of 330—500nm and an extra intensive spectral peak with good monochromaticity around 360nm. The intensity of the peak were 5 times high as the intensity of the substrate or N+ implantation samples and 1.5 times high at the N+2 implantation samples, respectively. It was also found there were two other stable luminescence bands around 730nm in the visible region and around 830nm in the infrared region, respectively. The preliminary study indicated that an excellent photoluminescence material was formed in the implanted layer.