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Colour patterns based on micro-nano structure have attracted enormous research interests due to unique optical switches and smart surface applications in photonic crystal, superhydrophobic surface modification, controlled adhesion, inkjet printing, biological detection, supramolecular self-assembly, anti-counterfeiting, optical device and other fields. In traditional methods, many patterns of micro-nano structure are derived from changes of refractive index or lattice parameters. Generally, the refractive index and lattice parameters of photonic crystals are processed by common solvents, salts or reactive monomers under specific electric, magnetic and stress conditions. This review focuses on the recent developments in the fabrication of micro-nano structures for patterns including styles, materials, methods and characteristics. It summarized the advantages and disadvantages of inkjet printing, angle-independent photonic crystal, self-assembled photonic crystals by magnetic field force, gravity, electric field, inverse opal photonic crystal, electron beam etching, ion beam etching, laser holographic lithography, imprinting technology and surface wrinkle technology, etc. This review will provide a summary on designing micro-nano patterns and details on patterns composed of photonic crystals by surface wrinkles technology and plasmonic micro-nano technology. In addition, colour patterns as switches are fabricated with good stability and reproducibility in anti-counterfeiting application. Finally, there will be a conclusion and an outlook on future perspectives. [ABSTRACT FROM AUTHOR]

A donor-acceptor (D-A) conjugated copolymer PSBT-FTT , incorporating alkylthiophenylthienyl ( SBT ) side chains on benzo[1,2- b :4,5- b ']dithiophene units (BDT), was designed and synthesized. Compared to the analogical polymer PSB-FTT with alkylthiophenyl ( SB ) side chains, PSBT-FTT exhibits stronger interchain π-π interaction, more redshifted absorption spectrum, stronger absorption coefficient, better compatibility with (7,7)-phenyl-C 71 -butyric acid methyl ester (PC 71 BM), more effective exciton dissociation and higher hole mobility. Therefore, the PSBT-FTT -based bulk heterojunction polymer solar cells (PSCs) achieved a PCE value of 7.06% that is almost 50% higher than 4.83% of the PSB-FTT based PSCs. The result indicates that the introducing SBT side chains is an excellent strategy for designing high performance photovoltaic polymers. [ABSTRACT FROM AUTHOR]

A trilobal non-fullerene electron acceptor, BTT-3PDI , incorporating benzo[1,2- b :3,4- b ′:5,6- b ″]trithiophene (BTT) as the core and three bay-substituted perylenediimides (PDIs) as the arms, was designed and synthetized. It shows a high electron mobility of 3.69 × 10 −3 cm 2 V −1 s −1 because it is a crystalline semiconductor for the partially conjugated structure between PDI units and BTT core. BTT-3PDI shows a matched energy levels and a complementary absorption spectrum with PTB7-Th. The conventional polymer solar cells were fabricated without any processing additive or posttreatment. It showed a power conversion efficiency (PCE) of 1.35% because the unconspicuous microphase separation of the blend film leads to low electron mobility (1.67 × 10 −5 cm 2 V −1 s −1 ) and hole mobility (2.80 × 10 −5 cm 2 V −1 s −1 ). The study provides a proof that the crystalline PDI derivative with small dihedral angles between a core and PDI units can also avoid serious molecular aggregation and large phase separation in the active layer. [ABSTRACT FROM AUTHOR]

Two novel acceptor pended push–pull conjugated polymers PTT–DTBT and PT–DTTBT ，incorporating thieno[3,2– b ] thiophene in the backbone chain and conjugated side chains respectively, were designed and synthesized. The effects of the location of thieno[3,2– b ]thiophene units on the thermal, photophysical, electrochemical and photovoltaic properties of the polymers were investigated. Compared to the polymer PTT–DTBT , the polymer PT–DTTBT with thieno[3,2– b ]thiophene units in the side chains shows more broadened and red–shifted absorption, smaller band gap and higher hole mobility. Bulk heterojunction solar cells with the polymers as electron donors and (6,6)–phenyl–C 61 –butyric acidmethyl ester as the electron acceptor were fabricated, and the PT–DTTBT –based device exhibits a higher power conversion efficiency of 4.07% than that of the PTT–DTBT –based device (3.05%) without any processing additives or posttreatments. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ternary polymerization was firstly used to design eco-friendly acceptors. • PTer-N25 showed high performance in the IDTIC-based polymeric acceptors. • The all-PSC, fabricated by o -xylene solution, achieved a high PCE of 11.94%. • 2-Methylnaphthalene was firstly used as the additive to fabricate all-PSCs. The terpolymers based on indacenodithiophene dicyanindenone derivative, named as PTer-N10 , PTer-N25 and PTer-N50 , were designed and synthesized by incorporating naphthalenediimide derivative with 10%, 25% and 50% molar ratios as another electron-withdrawing unit, respectively. These terpolymers were used as the acceptors to prepare all-polymer solar cells (all-PSCs) with o -xylene as the solvent and 2-methylnaphthalene as the additive without any annealing treatment, which showed high power conversion efficiency (PCE). The terpolymer PTer-N25 possesses the highest light harvest, the best morphology, the highest and most balanced charge mobilities in blend film, so the all-PSC based on PM6: PTer-N25 achieved the highest PCE of 11.94%. This study indicates that ternary polymerization is an efficient strategy to obtain green-solvent processing polymeric acceptors, which can achieve high-performance all-PSCs. [ABSTRACT FROM AUTHOR]

In chemical looping gasification (CLG), as one of the most commonly used oxygen carrier (OC), agglomeration is one of the most crucial triggers of Fe 2 O 3 /Al 2 O 3 OC deactivation. However, the formation mechanism of agglomeration is not clear due to the complexity of the interaction between biomass and OC. In this study, we investigated agglomeration process of Fe 2 O 3 /Al 2 O 3 OC in CLG from two dimensions of time and space. The results showed that in the time dimension, after ten cycles, the DT (deformation temperature) of the spent OC decreased by 5.39%, showing melting point was lower after cycles. Meanwhile, it caused the significant increase of the average particle size (59.73%) and the agglomeration degree (120.13%), indicating more severe agglomeration. Further, it led an obvious decrease in the CLG performance of efficiencies and gas yield. In the space dimension, when agglomeration occurred, low melting point K and Na compounds would first melt on the OC surface to form the K–Na inner layer (KAlSi 2 O 6 and NaAlSiO 4). As the reaction continued, high melting point Ca and Mg compounds would also be adhered to the surface of inner layer to form the Ca–Mg outer layer (CaAl 2 Si 2 O 8 and Mg 4 Al 10 Si 2 O 23), resulting in the continuous increase of OC particle size. In addition, more molten substances of KAlSi 2 O 6 and NaAlSiO 4 would lead to more adhesion between the OC particles. [Display omitted] • The molten layer on the OC surface thickened as the number of cycles increased. • The agglomeration of OC could be divided into the inner and outer layer. • K and Na compounds would first melt on the OC surface to form the K–Na inner layer. • Ca and Mg compounds would be adhered to form the Ca–Mg outer layer. • More molten substances would lead to more adhesion between the OC particles. [ABSTRACT FROM AUTHOR]

Mutation testing is a fault‐based technique to test the quality of test suites by inducing artificial syntactic faults or mutants in a source program. However, some mutants have the same semantics as original program and cannot be detected by any test suite input known as equivalent mutants. Equivalent mutant problem (EMP) is undecidable as it requires manual human effort to identify a mutant as equivalent or killable. The constraint‐based testing (CBT) theory suggests the use of mathematical constraints which can help reveal some equivalent mutants using mutant features. In this paper, we consider three metrics of CBT theory, ie, reachability, necessity, and sufficiency to extract feature constraints from mutant programs. Constraints are extracted using program dependency graphs. Other features such as degree of significance, semantic distance, and information entropy of mutants are also extracted to build a binary classification model. Machine learning algorithms such as Random Forest, GBT, and SVM are applied under two application scenarios (split‐project and cross‐project) on ten Java programs to predict equivalent mutants. The analysis of the study demonstrates that that the proposed techniques not only improves the efficiency of the equivalent mutant detection but also reduces the effort required to perform it with small accuracy loss. [ABSTRACT FROM AUTHOR]

[Display omitted] • We report a novel ternary nanocomposite hydrogel based on the CMCS, GO and gelatin. • CMCS-GO-Gelatin hydrogel exhibited excellent physical and chemical properties. • CMCS-GO-Gelatin hydrogel exhibited outstanding in vitro drug release property. Hydrogels have received immense interest for various biomedical applications owing to their hydrated environment and outstanding properties. However, challenges still exist regarding utilizing hydrogels in the application of drug delivery and release, because of the lack of controllability, actuation and quick-response properties. Here, the functionalized carboxymethyl chitosan-graphene oxide-gelatin composite hydrogel with excellent swelling property, high biocompatibility and drug delivery efficiency was prepared by ionic crosslinking. Our study found that the carboxymethyl chitosan-graphene oxide-gelatin composite hydrogel exhibited porous structures and the pores distribute randomly but arrange regularly in the cross section. In addition, the thermal stability and excellent swelling ratio of the carboxymethyl chitosan-graphene oxide-gelatin composite hydrogel were improved. As a consequence, the CMCS-GO-Gelatin-3 exhibited the maximum cumulative release rate and the cumulative release amount of this composite hydrogel was 74.6 under the condition of buffer solution pH = 6.5 PBS and 89.1 under the condition of buffer solution pH = 7.4 PBS. Therefore, this composite hydrogel showed improved drug delivery efficiency and achieved drug prolonged administration to 24 h. This work highlights that carboxymethyl chitosan-graphene oxide-gelatin composite hydrogel will be a promising candidate for the applications in biomedical engineering. [ABSTRACT FROM AUTHOR]

Two conjugated polymers have been designed and synthesized by introducing benzothienoisoindigo as electron-withdrawing moieties on side chains. PBDTT-TBID based on alkylthienyl-substituted benzo[1,2- b :4,5- b ']dithiophene (BDT) derivative as electron-donating moieties possesses a low-lying highest occupied molecular orbital energy level of −5.38 eV, so its polymer solar cells (PSCs) shows a high open-circuit voltage (V oc) of 0.96 V, which is one of the highest V oc values among benzothienoisoindigo-based polymers. PBDT-TBID based on alkoxyl-substituted BDT derivative possesses better molecular coplanarity, stronger intramolecular charge transfer, stronger intermolecular π-π stacking, more suitable microphase separation with PC 71 BM, more effective exciton dissociation, and higher hole mobility than PBDTT-TBID , which lead to higher short-circuit current density (J sc = 11.81 mA cm−2), fill factor (FF = 0.58) and power conversion efficiency (PCE = 5.87%) values than those based on PBDTT-TBID. The PCE value is still higher than those of the reported benzothienoisoindigo-based polymers though it lags behind those of recent non-fullerene PSCs. Image 1 • Benzothienoisoindigo-based polymer achieves a V oc of 0.96 V. • PBDT-TBID shows the best photovoltaic performance in benzothienoisoindigo -based polymers. • The effects of the side chains on the properties of the polymers are studied. [ABSTRACT FROM AUTHOR]

Highlights: [•] Amphiphilic fluoropolymer prepared by sequential ATRP and ring-opening of epoxy groups. [•] The copolymerization kinetic showed a linear first-order relationship. [•] Fluorinated copolymers had higher surface free energy than its homopolymer. [•] The self-assembly morphology of ring-opened polymer in solution was microsphere. [Copyright &y& Elsevier]

The development of invisible patterns via programmable patterning can lead to promising applications in optical encryption. This study reports a facile method for building responsive photonic crystal patterns. Commercially printed patterns were used as a mask to induce invisible patterns revealed by wetting. The masked areas exhibit different swelling kinetics, leading to strong structural colors in the masked area and transparent features in the unmasked area. The contrast could disappear through different wetting behavior, providing a unique and reversible wetting feature. This programmable printing is expected to become an environmentally friendly technique for scalable invisible optical anti-counterfeiting technology. [ABSTRACT FROM AUTHOR]