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Graphical abstract Highlights • The morphology of PLA microspheres could be varied through the formation of PLA stereocomplex. • By simply changing the ratio of PLLA and PDLA in solution, the porosity of the microspheres could be varied. • The drug release rate of the PLLA/PDLA microspheres can be easily tuned from slow to fast with slight initial burst. Abstract The applications of Polylactide (PLA) microspheres in biomedical areas are greatly determined by the size, morphology and internal structure. Taking advantage of the formation of stereocomplex (SC) crystallites between poly(L-lactide) (PLLA) and poly(D-lactide) (PDLA), we propose a facile strategy to prepare PLA microspheres with tunable morphology and crystalline structure by compounding PLLA and PDLA. With increasing PDLA content, the crystallinity of SC-PLA rose gradually until the ratio of PLLA and PDLA reached 1:1 and then fell. Correspondingly, the morphology of the microspheres were varied (smooth, porous, golf-ball like, guava like) and higher crystallinity of SC-PLA would lead to a more coarse and porous structure. Finally, three typical kinds of Rifampicin-loaded microspheres with different ratio of PLLA and PDLA (7:3, 3:7, 10:0, sorted by porosity from high to low) were prepared and the release behavior was compared. At 30 h, the cumulative release of 7:3, 3:7 and 10:0 microspheres were 32.6%, 17.8% and 6.0% respectively, indicating that the release profiles were generally determined by the porosity of the microspheres. Our findings not only provide a new strategy to prepare PLA microspheres with controllable morphology but offer additional possibilities for the applications of SC-PLA products in biomedical area. [ABSTRACT FROM AUTHOR]

Three Mg–1Ca–1Zn (wt.%) alloy anodes with distinct microstructure characteristics (As-cast, water-cooled (WC) and furnace-cooled (FC)) are prepared by casting and homogenization treatment followed by different cooling methods. The relationship between microstructure and discharge behavior is systematically investigated. Due to the severe self-corrosion and discharge products adhesion caused by the formation of a large number of micro-galvanic couples, the As-cast anode shows the worst discharge performance. After homogenization treatment, the FC anode possesses an increased peak anodic efficiency of 56.6% and discharge capacity of 1250.11 mAh g−1 at 10 mA cm−2, however, the "chunk effect" induced by the linkage of discharge channels at the triple line boundary restricts cell efficiency. The WC anode exhibits the highest cell voltage at all discharge current densities, which is attributed to the high electrochemical activity and easily exfoliated discharge product layers. A novel discharge mechanism of the linear dissolution of α-Mg across grain boundaries results in uniform dissolution of the anode matrix, mitigative hydrogen evolution and smooth discharge pits. The WC anode exhibits the highest anodic efficiency of 62.9% and specific capacity of 1388.9 mA h g−1 at 10 mA cm−2, making it a promising anode material for Mg-air cells. • A novel mechanism of α-Mg linear discharge across grain boundaries. • Effect of synergy and interaction between two second-phases on discharge behavior. • Three distinct discharge mechanisms are clarified. • The WC (water-cooling state) anode shows superior anodic efficiency of 62.9%. • Loose discharge products stabilize the cell voltage. [ABSTRACT FROM AUTHOR]

As a traditional general plastic, polypropylene (PP) has been widely used in daily life. Glass fibers are often used to further reinforce the properties of PP for its application in engineering area. However, there are still some drawbacks existing for glass fibers filled polypropylene composites, such as high filler content, easy fracture of glass fibers and damage to the machines during processing. Therefore, organic fibers are considered as an ideal candidate to replace glass fibers. In this work, short Kevlar fibers (KFs) modified by ball milling in phosphoric acid and surface hydrolyzation were introduced to PP matrix to improve the interfacial interaction and mechanical properties. It is found that KFs were exfoliated into several flaky microfibers and then broken into pieces during the ball milling process. With the aid of phosphoric acid, the KFs can be split further thereby increasing specific surface area greatly. Then the original and milled KFs were hydrolyzed by NaOH aqueous solution in order to introduce OH group on the surface of KFs. The dispersion and mechanical properties of PP reinforced with various KFs, including original, ball milled, and hydrolyzed, were investigated and compared. It was found that the combination of ball milling in phosphoric acid and surface hydrolyzation is the most effective way for enhancement of interfacial reaction and mechanical properties. Adding 10 wt. % of KFs could lead to an increase of tensile strength of PP from 30 MPa to 47 MPa, which only can be achieved by adding at least of 25 wt. % of glass fibers. The tensile test shows that hydrolyze of KFs surface are a more important factor to promote the interfacial interaction between fibers and matrix. Our work demonstrates that PP can be enhanced efficiently by the introduction of hydrolyzed and microfibrillated KFs. Although KFs are expensive compared with glass fiber at this moment, their high reinforcement efficiency and toughness could make them competitive as reinforcing filler for the preparation of advanced polymer composites with excellent mechanical and processing properties. [ABSTRACT FROM AUTHOR]

There are principally two mechanisms to improve the impact resistance of polymer-based composites, intrinsic toughening and extrinsic toughening. But the interplay between them is far from being well understood. Here, glass fiber was incorporated into polypropylene to promote extrinsic toughening mechanism, while addition of elastomer and annealing were adopted for intrinsic toughening. In this way, the interaction among glass fiber, elastomer and annealing could be discussed based on various characterizations, and their combined effect on mechanical properties of the composites could be determined. The results show that the intrinsic toughening mechanism of elastomer will be suppressed by glass fiber irrespective of the support of annealing, though annealing could work synergistically with glass fiber to toughen polypropylene. The possible structure-property relations are discussed. This work will provide deeper insight into the toughening behavior of polymer composites and practical guidance for the design of composites with excellent stiffness-toughness balance. [ABSTRACT FROM AUTHOR]

Nickel is one of the most commonly used catalysts for the growth of carbon nanofibers (CNFs) by catalytic chemical vapor deposition (CVD). Nevertheless, the chemical state of nickel catalyst, which may be metallic nickel (Ni), nickel subcarbide (Ni 3 C 1-x ) and nickel carbide (Ni 3 C) during the growth process of CNFs, remains a longstanding issue. We report here the catalytic growth of CNFs by CVD at temperatures ranged from 300 to 600 °C. It is demonstrated that the nickel catalyst has different chemical states during the catalytic growth, including Ni 3 C at 300 °C, composite Ni–Ni 3 C 1-x from 400 to 500 °C and metallic Ni at 600 °C, which is clearly dependent on the growth temperature. Our findings reconcile the longstanding debate on the contradictory models (i.e. Ni-assisted growth, Ni 3 C 1-x -assisted growth and Ni 3 C-assisted growth) for the catalytic growth CNFs. [ABSTRACT FROM AUTHOR]

As a novel thermoplastic elastomer, olefin block copolymers (OBCs) show a tremendous application potential in many areas. However, the practical use of OBCs is mainly restricted to the low load-bearing environments because of its poor low-strain mechanical strength and stiffness. In this work, short Kevlar fiber was introduced into OBC matrix to improve its mechanical properties. The results show that introduction of pristine Kevlar fiber only gives rise to a slight increase in tensile strength of OBC owing to the poor interfacial strength, regardless of the presence of compatibilizer maleic anhydride-grafted polypropylene (MA-g-PP). However, a largely enhanced tensile strength can be easily obtained when hydrolyzed or polydopamine-coated Kevlar fiber was incorporated into the OBC matrix using the MA-g-PP as the reactive compatibilizer. More importantly, the tensile strength can be further enhanced with the orientation of Kevlar fiber in the composites. As compared with compression molded composites with randomly orientated fibers, injection molded composites with highly oriented fibers exhibit a significantly higher tensile strength at the same composition. Moreover, it is interesting to observe that Kevlar fiber can be easily exfoliated into several microfibers during melt-mixing with OBC, but the exfoliation has no evident effect on the reinforcement effect possibly because of the poor interfacial strength between the newly-formed microfibers and the OBC matrix. Our work demonstrates that mechanical performance of short fiber reinforced elastomer composites could be significantly improved by enhancing interfacial strength and fiber orientation using a facile surface modification strategy and conventional melt-processing technology. [ABSTRACT FROM AUTHOR]

• High temperature resistant re-crosslinkable preformed particle gel (HT-RPPG) can form a rubber-like bulky material after placement and reduce the water production. • HT-RPPG has kept thermostable at 100 to 130 ˚C for over 10 months. • A breakthrough pressure of 427 psi/ft was reached during the blocking performance test in the void-space conduit (VSC) model. Gel treatment has been widely applied to control conformance for improving oil recovery and control water production in mature oil fields. However, most of the hydrogel systems are limited when being applied in the harsh environments of high temperatures. A systematic evaluation was conducted in this study to evaluate a modified PPG product, the high temperature resistant re-crosslinkable preformed particle gel (HT-RPPG) which can re-crosslink to form a bulky material and keep thermostable in the large-opening features after placement. This material was developed to overcome the limitations of conventional PPGs in the reservoirs with large- opening features such as open fractures, void conduits, wormholes, and so on. The HT-RPPG can swell up to 18 times of its original size at room temperature (23˚C), and the swelling ratio is independent of brine concentration and types. We conducted a series of experiments to evaluate the effect of particle size, temperatures, swelling ratios, brine types on re-crosslinking time, as well as the gel strength, blocking performance and thermostability after re-crosslinking. Smaller particle sizes result in the HT-RPPGs swell and re-crosslink much faster. Higher temperatures increase the swelling and re-crosslinking rate, while the larger swelling ratios (more feeding brine) can slow down the re-crosslinking time. HT-RPPG re-crosslinking process can be delayed when the particles contact with Ca2+. Additionally, the re-crosslinking of HT-RPPG is a temperature-responsive reaction which can only start after reaching the target temperature of 100 °C or above. The HT-RPPG has kept its volume and strength stable at 100 to 130 °C for over 10 months so far. A blocking performance test was conducted by using the tubing model to simulate void-space conduit (VSC), and breakthrough pressure reached to 427 psi/ft. [ABSTRACT FROM AUTHOR]

The gut microbiota is known to be associated with the regulation of many neurological diseases and behaviors, including chronic pain. However, it is unclear whether the gut microbiota is critical to the itch sensation. In this study, we investigated the effects of gut microbiota depletion on acute itch. First, an antibiotic cocktail was orally administered to deplete the gut microbiota in male C57BL/6 mice. Then, pruritogens were intradermally injected to induce acute itch behavior. In addition, antibiotic-treated mice received transplantation of fecal microbiota from untreated mice, followed by tests for acute itch. The changes in c-Fos expression in trigeminal ganglia (TG) neurons were also investigated by immunofluorescence staining. Our results indicated that chronic antibiotic treatment significantly reduced the diversity and richness of the gut microbiota of mice. Compared to vehicle-treated mice, antibiotic-treated mice showed reductions in acute itch behavior induced by compound 48/80, chloroquine (CQ), and serotonin (5-HT), respectively. Moreover, repositioning of microbiota reversed the reductions in acute itch behavior in antibiotic-treated mice. In addition, immunofluorescence staining revealed that antibiotic-treated mice displayed decreased c-Fos expression in ipsilateral TG compared to controls. Our study, for the first time, discovered that antibiotic-induced gut microbiota depletion could reduce acute itch behavior, which may be connected with decreased TG neuronal activity. • Chronic antibiotic treatment depleted gut microbiota in mice. • Antibiotic treatment reduced acute itch behavior induced by compound 48/80, CQ and 5-HT. • Reposition of microbiota reversed the inhibition of acute itch behavior induced by antibiotic treatment. • Antibiotic treatment suppressed the increase in c-Fos expression induced by pruritogens in TG neurons. [ABSTRACT FROM AUTHOR]

Perovskite materials have outstanding optical and electronic properties. In recent years, the power conversion efficiency (PCE) of perovskite solar cells (PSCs) in the laboratory has raised rapidly from 3.8% to 25.5%. It has the potential to further improve the PCE of solar cells and approach the Shockley-Queisser (SQ) limit. For preparing high-efficiency PSCs, the chemical composition tuning and morphology improvement of the perovskite absorption layer, the energy level matching of the interface, the extraction and transport rate of carriers in the transport layer are focused widely. Many methods such as additive engineering, defect passivation, interface engineering, and transmission material optimization are suggested. This review summarizes efficiency improvement effort of perovskite solar cell from the three dimensions of perovskite absorption layer, charge transport layer and interface. [ABSTRACT FROM AUTHOR]

We investigated the complex solidification behaviour of Al 2 O 3 –Y 3 Al 5 O 12 eutectics prepared by laser engineered net shaping. Colony structure consisting of coupled irregular eutectic was dominant at interior region of as-fabricated specimens, and its growth behaviour was depicted by Magnin–Kurz model. In each deposited layer, The Y 3 Al 5 O 12 phase within irregular eutectic grew through a competitive mechanism from random to oriented, whereas the orientation of Al 2 O 3 remained unchanged. Transition from anomalous to colony coupled eutectics occurred at the bottom of each layer, and irregular to regular eutectics transition was recognized at outer region of as-built sample. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Traditional expanded graphite (EG) films exhibit excellent electric and thermal conductivities, due to weak oxidation degree induced low defect density. However, the stiff sheet structure makes EG films very brittle, which greatly limits its applications in next generation flexible electric devices. To overcome this challenge, ammonium persulfate ((NH 4) 2 S 2 O 8) is employed as both expansion agent and weak oxidation agent. As a result, the weak oxidation can effectively reduce the surface energy mismatching between EG and water, making it possible for EG to be exfoliated in water by high-speed shearing combined with sonication. Most particularly, the expansion step introduces plenty of wrinkles into the EG sheets, which notably improve the flexibility of EG films. Besides, using raw graphite with large lateral size and less (NH 4) 2 S 2 O 8 can greatly improve the final overall performances. The prepared EG films exhibit good electric and thermal conductivities of 2977 S/cm, 854 W/mK, respectively. 33.1 dB EMI shielding property is obtained with the film thickness of only 10 μm. Moreover, 800 times direct bending can be overcome without any structure break. This facial large scale and environmentally friendly method endows the films with great potential applications in flexible electric devices. Image 1 [ABSTRACT FROM AUTHOR]

The production of large graphene oxide (GO) sheets is often limited by the huge diffusion resistance for oxidizing agents caused by the structural uniformity of large raw graphite flakes. Previous methods often rely on the thermal or microwave, hydrogen peroxide (H 2 O 2) expansion to overcome the large diffusion resistance. However, the pretreatment is usually energy consuming and costs extra acid which may cause more environmental risks. Here, we discovered that adding ammonium persulfate ((NH 4) 2 S 2 O 8) to concentrated sulfuric acid as gas expansion agent for the pretreatment of graphite flakes can lead the graphite to form a porous structure and effectively improve the specific surface area of graphite, providing more contact area for graphite with oxidizing agents due to the rapid gas release. Thus, the diffusion resistance for oxidizing agents is remarkably reduced. As a result, graphite oxide with pretreatment shows higher oxidation degree (C/O ratio: 1.7) compared with graphite oxide without pretreatment (C/O ratio: 2.3). Besides, without any exfoliation method, the as obtained uniformly oxidized graphite oxide can self-exfoliate into monolayer GO sheets with a weight average size of 1263 μm2. Moreover, the vacuum filtrated GO films exhibit superior mechanical properties (Tensile strength: 80.9 MPa). Image 1 [ABSTRACT FROM AUTHOR]

Abstract Expanded graphite (EG) films are known for high electric and thermal transportation properties, due to light oxidation preparation process compared with chemical converted graphene (cGE) films. However, the poor mechanical properties and brittle nature are the major limitations for commercial applications. To meet this challenge, in this work, hydrated aramid nanofiber (HANF) with excellent mechanical properties and flexibility is introduced into EG films to enhance their mechanical properties and flexibility. As a result, only the adding of 2 wt% HANF can endow EG films with good flexibility. The best comprehensive property is achieved by adding 10% HANF (EG-10). Compared with the pure EG films (EG-0), a 223% improvement of tensile strength from 7.5 Mpa to 24.2 Mpa and a 660% enhancement of elongation at break from 0.371% to 2.82% are observed for EG-10. Besides, EG-10 maintains good electric and thermal conductivities of 215 S cm−1, 208 W m−1 K−1. Moreover, the EMI shielding property of 34.9 dB is realized when the film thickness reaches only 30 μm. The EG/HANF films can be used up to the temperature of 300 °C and show good flame resistance compared with adding other polymers thanks to the good stability of HANF. And, the excellent flexibility can be maintained even after 1000 times direct folding. The comprehensive properties of light weight films, together with their advantages of simple, cheap and facile large-scale preparation process endow the films with promising applications in next generation foldable electronic devices. [ABSTRACT FROM AUTHOR]

Summary Mannose receptor (MR, CD206) is an endocytic receptor on microphages and dendritic cells. It recognizes multiple ligands and plays important roles in regulating immune responses and maintaining glycoprotein homeostasis. However, the structure and functional mechanism of MR remain unclear. Here we determine the crystal structures of the N-terminal fragments of MR and reveal the potential binding mode of collagen on the fibronectin II domain. The SAXS and other biophysical data suggest that MR adopts an extended conformation at physiological pH and undergoes conformational changes as pH decreases, resulting in a compact conformation in an acidic environment. Moreover, biochemical data show that MR binds to collagen in a Ca 2+ -enhanced manner at physiological pH, whereas Ca 2+ has no effect on the binding at acidic pH. These results provide a model for the dynamic mechanism of MR regarding its ligand binding and release during the recycling between cell surface and endosomes. [ABSTRACT FROM AUTHOR]

Expanded graphite (EG) films with low oxidation degree exhibit excellent thermal, electric properties and electromagnetic interference (EMI) shielding. However, the mechanical brittleness is the major limitation for their applications. To meet this challenge, in this work, a small amount of flexible graphene (GE) is introduced to endow EG films with good flexibility and mechanical properties by forming simulate shell structure. Moreover, the influence of oxidation degree and sheet thickness for carbon sheets as well as the lateral size of GE on the film performance is carefully discussed. As a result, a 431% enhancement of tensile strength from 7.7 Mpa to 40.9 Mpa and little sacrifice of electric, thermal conductivities up to 1467 S cm −1 and 348 W m −1  K −1 are observed with the loading of only 10% large GE (LGE) sheets in EG films. Besides, high EMI shielding of 48.3 dB is achieved as the film thickness reaches 43 μm. The excellent flexibility of prepared EG/LGE films can be retained even after more than 1000 times of direct folding. These excellent properties of light-weight EG/LGE films, together with their advantages of environmentally friendly and facile large-scale fabrication, endow the films with great potential applications in next-generation commercial portable flexible electronics. [ABSTRACT FROM AUTHOR]

The most commonly used opioid analgesics are limited by their severe side-effects in the clinical treatment of pain. Preliminary reports indicate that the combination of classical opioids and N/OFQ receptor (NOP) ligands may be an effective strategy to reduce unwanted side-effects and improve antinociception. But the interaction of these two receptor ligands in pain regulation at the peripheral level remains unclear. In this study, the antinociception of a designed amide analogue of the mu opioid receptor (MOP) peptide agonist DAMGO, DAMGO-NH 2 , and its antinociceptive interaction with the peripherally limited NOP peptide agonist NOP01 was investigated in two mouse models of formalin pain. Our results showed that DAMGO-NH 2 acted as a MOP agonist in in vitro functional assays. Moreover, local subcutaneous or intraplantar injection of DAMGO-NH 2 exerted dose-related antinociception in both phases of the formalin orofacial and intraplantar pain, which could be mediated by the classical opioid receptor. Peripheral but not central pretreatment with the peripherally restricted opioid antagonist naloxone methiodide inhibited local DAMGO-NH 2 -induced antinociception, supporting the involvement of the peripheral opioid receptor in local DAMGO-NH 2 -induced antinociception. Furthermore, co-administration of the inactive doses of DAMGO-NH 2 and NOP01 produced effective antinociception. More importantly, isobolographic analysis indicates that the combination of DAMGO-NH 2 and NOP01 elicited supra-additive antinociception in these two models of formalin pain. In addition, the combination of DAMGO-NH 2 and NOP01 did not change motor function of mice in rotarod test. In conclusion, these data suggest that peripheral DAMGO-NH 2 and particularly its combination therapy with NOP01 may be effective for pain management. • DAMGO-NH 2 acts as a selective agonist at mu opioid receptor. • DAMGO-NH 2 could produce antinociception in formalin orofacial or intraplantar pain. • Local subcutaneous DAMGO-NH 2 could produce peripherally acting antinociception. • DAMGO-NH 2 could elicit supra-additive antinociception with NOP receptor agonist NOP01. • Combination of DAMGO-NH 2 and NOP01 does not alter the motor function of mice. [ABSTRACT FROM AUTHOR]

We present experimental and theoretical results to describe and explain processing outcomes when producing nanochannels that are a few times wider than the atomic force microscope (AFM) probe using an AFM. This is achieved when AFM tip-based machining is performed with reciprocating motion of the tip of the AFM probe. In this case, different feed directions with respect to the orientation of the AFM probe can be used. The machining outputs of interest are the chip formation process, obtained machined quality, and variation in the achieved channel depth. A three-sided pyramidal diamond probe was used under load-controlled conditions. Three feed directions were first investigated in detail. The direction parallel to and towards the probe cantilever, which is defined as “edge forward”, was then chosen for further investigation because it resulted in the best chip formation, machining quality, and material removal efficiency. To accurately reveal the machining mechanisms, several feed directions with different included angles for the pure edge-forward direction were investigated. Upon analysis of the chips and the machined nanochannels, it was found that processing with included angles in the range 0–30° led to high-quality channels and high material-removal efficiency. In this case, the cutting angles, such as the rake angle, clearance angle, and shear angle, have an important influence on the obtained results. In addition, a machining model was developed to explain the observed machined depth variation when scratching in different feed directions. [ABSTRACT FROM AUTHOR]