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When the self-assembly of block copolymers (BCPs) occurs within organic emulsion droplets in the aqueous phase, the strong structural frustration of BCP chains causes the formation of a series of well-regulated BCP particles that cannot be obtained from the self-assembly of BCPs in the bulk state or solution. In this Perspective, we review the recent progress of the self-assembly of BCPs confined in emulsion droplets. The governing factors of the structure and morphology of the as-prepared BCP particles are summarized. In addition, the applications of the as-prepared BCP particles in photonic crystals and drug release are discussed. Finally, we also give a forward-looking perspective on future challenges in this field.

Integrating structural anisotropy, excellent mechanical properties, and superior sensing capability into conductive hydrogels is of great importance to wearable flexible electronics yet challenging. Herein, inspired from the aligned structure of human muscle, we proposed a facile and universal method to construct an anisotropic hydrogel composed of polyacrylamide and sodium alginate by pre-stretching in a confined geometry and subsequent ionic cross-linking. The designed hydrogels showed extraordinary mechanical performances, such as ultrahigh stretchability, a comparable modulus to that of human tissues, and good toughness, ascribed to their anisotropically aligned polymer networks. Additionally, the hydrogel possessed anisotropic conductivity due to the anisotropy in ion transport channels. The hydrogel along the vertical direction was further cut and assembled into a flexible strain sensor, exhibiting a low detection limit (0.1%), wide strain range (1585%), rapid response (123 ms), distinct resilience, good stability, and repeatability, thereby being capable of monitoring and discriminating different human movements. In addition, the relatively high ionic conductivity and superior sensitivity enabled the anisotropic hydrogel sensor to be used for wireless human-machine interaction. More interestingly, the Ca

Bioinspired by the interlocked geometry between the epidermal-dermal layers of natural skin, here we design a flexible and transparent (94.2%) skin-like sensor with an interlocked hexagonal microcolumn array structure based on ionogels of ionic liquids (ILs) and thermoplastic polyurethane (TPU) assisted by laser-etched silicon wafers. Attributed to the bioinspired microstructure, the resulting interlocked TPU@IL ionogel sensor exhibits outstanding pressure-sensing properties, which has an ultralow detection limit (∼10 Pa) and ultrafast responsiveness (∼24 ms). Interestingly, it is worth noting that the interlocked TPU@IL ionogel sensor also has high temperature-sensing performance because of the dependence of the ionic conductivity of ILs on the temperature, which can accurately detect a slight temperature change (0.1 °C). Moreover, the interlocked TPU@IL ionogel sensor can also serve as the strain sensor in the strain range of 0.1-10%. Attributed to the intrinsically antibacterial effect of ILs, the interlocked TPU@IL ionogel sensor possesses an antibacterial function, which is a desired merit of wearable electronics and devices. The current study provides a novel strategy to manufacture transparent, flexible, and antimicrobial e-skin sensors with multiple sensing capabilities, which may inspire more future research studies for e-skins.

Wearable strain and temperature sensors are desired for human-machine interfaces, health monitoring, and human motion monitoring. Herein, the fibrous mat with aligned nanofibers of ionic liquid (IL)/thermoplastic polyurethane (TPU) ionogels is fabricated via an electrospinning technique. The resultant fibrous mat is cut into a rectangle specimen and electrodes are loaded along the direction perpendicular to the nanofiber orientation to design a high-performance multimodal sensor based on an ionic conducting mechanism. As a strain sensor, the obtained sensor exhibits a wide strain working range (0-200%), a fast response and recovery (119 ms), a low detection limit (0.1%), and good reproducibility because of the reversible and deformable ionic conductive pathways of the sensor. Moreover, the sensor also exhibits excellent temperature-sensing behaviors, including a monotonic thermal response, high sensitivity (2.75% °C-1), high accuracy (0.1 °C), a fast response time (2.46 s), and remarkable repeatability, attributable to the negative temperature coefficient behavior of the IL/TPU fibrous mat. More interestingly, the IL/TPU fibrous sensor possesses good breathability, which is desired for wearable electronics. Because of these excellent sensing capabilities in strain and temperature, the sensor can not only monitor tiny and large human motions but also detect respiration and proximity, exhibiting enormous potential in wearable electronics.

Confined self-assembly of block copolymers (BCPs) is effective to manipulate various shapes of particles. In emulsion confined self-assembly, reversibly light-trigged switchable BCP particles are extremely expected, yet rarely reported. Herein, a novel strategy is developed to realize reversibly light-responsive shape-transformation of BCP particles by constructing functional surfactants with light-active azobenzene (azo) groups in the confined self-assembly of BCPs within emulsion droplet. Ultraviolet and visible lights can reversibly modulate the amphiphilicity and interfacial affinity of the surfactants to different blocks, triggering the reversible microphase structure transformation of BCP particles with high temporal-spatial resolution. We can realize shape and morphological transitions of BCP particles from onion-shaped spherical particles to striped ellipsoids and, ultimately, to inverse onion-like particles by ultraviolet irradiation. More importantly, this shape transformation is reversible by the irradiation of visible light, attributed to the reversible

Stretchable strain sensors have received intensive attention recently due to their widespread potentials in the fields of healthcare monitoring, soft robotics, and electronic skin. Besides high stretchability and excellent sensing properties, the transparency of the sensor is another important parameter when designing multi-functional sensors in reality. In this review paper, we mainly focused on the different strategies to realize the transparency of stretchable strain sensor. Some typical advances in different types of stretchable and transparent strain sensors as well as their mechanisms, sensing properties, and applications are summarized. Finally, the open question and possible solution in this field have also been showcased.

Stretchable strain sensor and temperature sensor are two essential components in e-skins and wearable electronics. Although great progress has been made in this field recently, some challenges like the linear sensitivity of the output signal to stimuli and transparency of the sensor have still not been overcome. Herein, we select the ionic liquid to replace the traditional solid conductive nanoparticles as the sensing components to be encapsulated in the tailored cavity inside the stretchable polydimethylsiloxane thin film to design the stretchable and transparent multifunctional sensors. This sensor exhibits various merits, such as high flexibility, transparency, highly sensitive to strain and temperature, and outstanding monotonicity and linearity of the outputted signals, which can be the promising candidate of stretchable strain sensor and temperature sensor in various fields. More interestingly, a feature of this sensor is that the resistance is only slightly increased under large tensile strain, which makes it possible for serving as the stretchable conductor simultaneously. This work proposes a new strategy that allows the creation of multifunctional sensor with high transparency, high sensitivity, and excellent linearity of the signal.

End functionalization of homopolymers by noncovalent binding units is a straightforward approach to prepare supramolecular polymers with a broad application scope as stimuli-responsive functional m...

Stretchable strain sensors have promising applications in many fields, including soft robotic skin, health monitoring, wearable electronics, and so on. Among the various properties of stretchable strain sensors, the low detection limit and wide sensing range are the two most critical properties that determine their practical application in the above fields. However, it is still a great challenge to achieve both an ultralow detection limit and ultrawide sensing range at the same time, and there often needs to be a tradeoff between them. Herein, we propose a simple route to design a stretchable strain sensor with both an ultralow detection limit and an ultrawide sensing range by the combination of the electrospinning technique and ultrasonication anchoring technique. Specifically, thermoplastic polyurethane (TPU) is fabricated into a highly stretchable porous film and carbon nanotubes (CNTs) are anchored onto the surface of TPU nanofibers assisted by ultrasonication, and then assembled with two Cu electrodes to fabricate the strain sensor. Attributed to the multiscale evolution of the conductive network under stretching, the designed strain sensor exhibits many outstanding merits, such as an ultra-low detection limit (0.05%), an ultrawide sensing range from 0.05% to 600%, a fast response time of 75 ms, and excellent durability. Because of these outstanding merits, the TPU@CNT strain sensor can detect both the subtle strain change caused by the sound of a piano and the large strain change caused by the large-scale motions of joints. Moreover, it is found that TPU@CNT sensor responds to temperature and humidity, which has great potential in temperature sensors and humidity sensors.

In this work, we proposed an effective route, i.e., three-dimensional (3D) confined co-assembly of block copolymers (BCPs) and inorganic nanoparticles (NPs) within organic emulsion droplets, to efficiently encapsulate high-density and large-size NPs into the wall of BCP vesicles. Attributed to the interfacial instability, the aqueous phase could spontaneously enter into the organic emulsion droplets, thus inducing the formation of BCP vesicles encapsulated with NPs. Moreover, it is found that the encapsulation of NPs into the vesicle wall is mainly dominated by the ratio (DN/dw0) of the NP diameter (DN) to the layer thickness of the affinitive blocks (dw0). Utilizing the 3D confined co-assembly of polystyrene-block-poly(4-vinylpyridine) and PS-coated gold nanoparticles (AuNPs) with different diameters, the high-efficiency encapsulation of AuNPs in the BCP vesicle wall at a DN/dw0 value of 0.66 can be achieved, which is greater than the previous reported critical value (i.e., DN/dw0 ≈ 0.5). Although the conformational entropy loss of the polymer chains increases with the introduction of AuNPs, the NPs can still be successfully encapsulated into the vesicle wall because the oil–water interface can suppress the diffusion of NPs to the aqueous phase. However, as the DN/dw0 value is further increased to 1.04, AuNPs will be repelled out of the vesicles because of the extremely strong entropic repulsion arising from the drastic loss in conformational entropy of PS blocks, thus forming some spherical hybrid micelles independently. Our results provide a new and facile route to realize the efficient encapsulation of large size NPs into polymeric vesicles.

Fiber-shaped stretchable strain and temperature sensors are highly desirable for wearable electronics due to their excellent flexibility, comfort, air permeability, and easiness to be weaved into fabric. Herein, we prepare a smart ionogel-based fiber composed of thermoplastic polyurethane (TPU) and ionic liquid (IL) by the facile and scalable wet-spinning technique, which can serve as a wearable strain sensor with good linearity (a correlation coefficient of 0.997) in an ultrawide sensing range (up to 700%), ultralow-detection limit (0.05%), fast response (173 ms) and recovery (120 ms), and high reproducibility. Attributed to these outstanding strain sensing performances, the designed TPU/IL ionogel fiber-shaped sensor is able to monitor both subtle physiological activities and large human motions. More interestingly, because of the fast response and high resolution to strain, the fiber-shaped sensor can be sewn into the fabric to secretly encrypt and wirelessly translate message according to the principle of Morse code. More importantly, a wearable strain-insensitive temperature sensor can be obtained from the ionogel fiber if it is designed into an "S" shape, which can effectively eliminate the interference of strain on temperature sense. It is found that the inaccuracy of temperature sense is within 0.15 °C when the sensor is subjected to 30% tensile strain simultaneously. Moreover, this strain-insensitive temperature sensor shows a monotonic temperature response over a wide temperature range (-15 to 100 °C) with an ultrahigh detecting accuracy of 0.1 °C and good reliability, owing to the fast and stable thermal response of IL. This temperature sensor can realize the detection of thermal radiation, proximity, and respiration, exhibiting enormous potential in smart skin, personal healthcare, and wearable electronics. This work proposes a simple but effective strategy to realize the essential strain and temperature sensing capabilities of wearable electronics and smart fabrics without mutual interference.

Thermoresponsive polymers that exhibit a cloud point temperature (Tcp) are an important class of stimuli-responsive polymers that have great potential for biomedical applications. Precise tuning of the Tcp is of fundamental importance for designing thermoresponsive polymers. However, tuning the Tcp generally requires sophisticated control over the chemical and assembled structures of thermoresponsive polymers. Here, we report a simple yet effective method to tune the Tcp of thermoresponsive polymers only by mixing and varying the mixing ratios of amphiphilic copolymer pair that contains l- and d-configured hydrophobic blocks in a dilute solution. Stereocomplex (SC) crystallization of the l- and d-configured blocks led to form core–shell micelles with a larger size, a bigger core, and a higher aggregation number, which facilitated the intermicellar aggregation upon heating due to improved intermicellar attractions. SC crystallization of the hydrophobic blocks improved the separation efficacy of the thermor...

Nutrient stimulation is considered effective for improving biogenic coalbed methane production potential. However, our knowledge of the microbial assembly process for profuse and rare microbial communities in coals under nutrient stimulation is still limited. This study collected 16S rRNA gene data from 59 microbial communities in coals for a meta-analysis. Among these communities, 116 genera were identified as profuse taxa, and the remaining 1,637 genera were identified as rare taxa. Nutrient stimulation increased the Chao1 richness of profuse and rare genera and changed the compositions of profuse and rare genera based on nonmetric multidimensional scaling with Bray-Curtis dissimilarities. In addition, many profuse and rare genera belonging to Proteobacteria and Acidobacteria were reduced, whereas those belonging to Euryarchaeota and Firmicutes were increased under nutrient stimulation. Concomitantly, the microbial co-occurrence relationship network was also altered by nutrient addition, and many rare genera mainly belonging to Firmicutes, Bacteroides, and Euryarchaeota also comprised the key microorganisms. In addition, the compositions of most of the profuse and rare genera in communities were driven by stochastic processes, and nutrient stimulation increased the relative contribution of dispersal limitation for both profuse and rare microbial community assemblages and that of variable selection for rare microbial community assemblages. In summary, this study strengthened our knowledge regarding the mechanistic responses of coal microbial diversity and community composition to nutrient stimulation, which are of great importance for understanding the microbial ecology of coals and the sustainability of methane production stimulated by nutrients.

Shape-controlled block copolymer (BCP) particles that respond to light stimulus have drawn great attention due to their promising applications in smart materials, yet polymeric particles with light-triggered controllable sequential shape transformation (SST) are still rarely reported. By confined co-assembly of polystyrene

Constructing noncovalent interactions has been a benign method to tune the stimuli responsivity and assembled structure of polymers in solution; this is essential for controlling the functions and properties of stimuli-responsive materials. Herein, we demonstrate a novel supramolecular strategy to manipulate the cloud point (

We report the formation and structure of poly(lactic acid) (PLA) nanofiber shish kebabs (NFSKs) containing stereocomplex crystal (SC) shish and SC/homocrystal (HC) kebabs. PLA-based NFSKs were obtained by combining electrospinning and controlled polymer crystallization in order to investigate the interplay between PLA SC and HC formation. Nanofibers were produced by electrospinning poly(l-lactic acid)/poly(d-lactic acid) (PLLA/PDLA) blends and were used as the shish. A secondary polymer (either PDLA or PLLA/PDLA blends) was decorated on the nanofiber by an incubation method to form kebab lamellae. We show that both SC and HC kebab crystals can be formed using a SC shish following a soft epitaxy mechanism, while the subtle morphological differences in the resultant NFSKs reveal the propensity of SC nuclei in SC/HC crystallization.

Clipping noise estimation and cancellation are essential in orthogonal frequency division multiplexing (OFDM) systems when clipping is performed to reduce the peak-to-average power ratio (PAPR). Motivated by the richer representational capacity of complex numbers and the fact that communication is a complex-valued problem, a novel clipping noise estimation scheme based on deep complex neural network is proposed in this paper. Specifically, the clipping noise is determined by a deep complex network, namely clipping noise estimation network (CNE-Net), such that the mean square error (MSE) and the sparsity of the estimated clipping noise are jointly optimized. Besides, an ordering based zero-forcing scheme is utilized to further ensure the sparsity of the estimated clipping noise. Simulation results show that the proposed CNE-Net shows comparable performance with the conventional decision-aided reconstruction (DAR) scheme and can achieve better performance than the one-iteration DAR scheme when the clipping noise is not sparse enough. In summary, the CNE-Net has a good capability to estimate the clipping noise from noise-affected features.

For OFDM systems, to cope with the remain problems of high complexity and low performance in conventional clipping noise cancellation methods, a robust scheme based on location-aware compressed sensing (CS) and phase correction is proposed in this paper. Based on CS theory, a simple and configurable selection criterion is utilized to choose reliable observations for the clipping noise reconstruction. The transceiver is redesigned to transmit both the data and the clipping location. With the aid of clipping location information and phase information from the receiver, the proposed scheme improves both the accuracy and computational complexity. Simulation results show that the proposed scheme achieves excellent performance even in low signal-to-noise ratio (SNR) environments. Besides, due to the low computational complexity and excellent adaptivity, the proposed scheme is more feasible in practical engineering applications than other CS-based methods.

Circular RNAs (circRNAs) has been shown to be involved in the progression of various malignancies. Nevertheless, the mechanism of dysregulated circRNAs in gastric cancer (GC) remains to be understood. CircRNA microarray was utilized for identifying circRNA expression profiles in GC tissues. Circ-ATAD1 expression was measured by qRT-PCR. The clinical significance of circ-ATAD1 was analyzed by Fisher's exact test, Kaplan-Meier plots, and Cox regression model. The function of circ-ATAD1 was explored by using CCK-8, clone formation, flow cytometric and transwell experiments. RNA sequencing, bioinformatics, RNA pulldown, chromatin immunoprecipitation followed by sequencing, and dual-luciferase reporter assays were applied to determine the regulatory networks of circ-ATAD1 in GC cells. Circ-ATAD1 expression was increased in cancerous tissues. The prognostic value of circ-ATAD1 was identified in GC patients. For GC cells, circ-ATAD1 increased cell progression by sponging miR-140-3p to upregulate YY1. Additionally, YY1 directly bound to the promoter of PCIF1, thereby activating its transcription. Collectively, circ-ATAD1 plays an important role in GC tumorigenesis and progression and might be an important biomarker/therapeutic target for GC.

Stereocomplexation of complementary chiral blocks has been a feasible way to prepare thermoresponsive physical gels (or thermogels). Understanding the thermoresponsive phase behavior of stereocomplexable amphiphilic copolymers in water is essential to prepare thermogels with tunable physical properties. Herein, we use an enantiomeric mixture of the poly(D-lactic acid) (PDLA)/poly(ethylene glycol) (PEG) diblock copolymer and the poly(L-lactic acid) (PLLA)/PEG triblock copolymer as a stereocomplexable system and report a novel thermogel that exhibits unique gel–sol–gel multiple transitions upon heating. The thermally-induced phase transition of the PEG–PDLA/PLLA–PEG–PLLA thermogel was governed by the copolymer composition and the stereocomplexation of PLLA/PDLA segments. The molecular motion of PEG segments enhances during the gel–sol transition but slows down in the subsequent sol–gel transition. The gel–sol and sol–gel transitions that occurred at low and high temperatures are driven by the increased mobility of PEG segments and micelles and the promoted PLLA/PDLA stereocomplexation, respectively. PEG–PDLA/PLLA–PEG–PLLA gels can be used to capsulate and release a hydrophobic drug; the drug release rate increases as the content of hydrophilic blocks increases.

Skin-like sensor has recently emerged for its promising applications in human motion monitoring and healthcare. However, it is challenging to develop flexible skin-like sensors multifunctionally coupled with high transparency and strain sensitivity, accurate thermosensation, and good antibacterial activity. Herein, we fabricate flexible and transparent (94.3%) ionogels by facilely mixing ionic liquid (IL) and thermal-plastic polyurethane (TPU) to be as skin-like sensors. The prepared TPU@IL ionogel-based sensor exhibits wide strain range (0.1–500%) and fast response (96 ms) to strain stimuli. Attributed to the temperature-dependent conductivity and low freezing point of IL, the ionogels can be served as stretchable temperature sensor, containing wide operating temperature window (−40-100 °C) and high detecting accuracy (0.1 °C). Moreover, the ionogels exhibit excellent antibacterial activity. This work may inspire future research to design full-featured skin-like sensors.

Stretchable strain sensor and temperature sensor are two essential components for the integration of wearable electronics and electrical skins, which have great potentials in healthcare monitoring, human motion monitoring and human-machine interfaces. Up to now, it is still a challenge to fabricate the stretchable and multifunctional sensor with both the capabilities of strain sensing and temperature sensing by an effective and economical method. Herein, a simple route is provided to design multifunctional sensors with high sensing performances for strain and temperature, which combines the electrospun technique and ultrasonication anchoring technique. Specifically, fibrous thermoplastic polyurethane (TPU) film is fabricated by electrospun technique at first, and then is saturated by ionic liquid (IL) to design the stretchable sensor. Attributed to the stable response and fast reconstruction of conductive pathways of ionic liquid under the stretching-releasing process, the TPU/IL sensor can serve as strain sensor, which exhibits various merits, including fast response time of 67 ms, ultra-low detection limit (0.1%), ultra-wide sensing range from 0.1% to 400% and excellent durability for long-term usage. In addition, it is noteworthy that TPU/IL sensor has great advantages in temperature sensing, which possesses a lowest temperature accuracy of 0.5 °C. This work provides a novel route for manufacturing stretchable multifunctional sensor with both temperature and strain sensing functions, which may accelerate the development of the emerging wearable electronics and electrical skins.

Supramolecular polymers (SMPs) have quite different crystallization behavior from the conventional polymers, because of the confinement effects of supramolecular units. Crystallization of SMPs undergoes in a “confined” and “dynamic” manner. Herein, we selected the 2-ureido-4[1H]-pyrimidione (UPy)-bonded poly(l-lactic acid) (PLLA) as a model SMP and investigated the crystallization kinetics, polymorphic crystalline structure and phase transition of supramolecular PLLAs (SM-PLLAs). SM-PLLAs were synthesized by the end functionalization of hydroxyl-terminated 2- and 3-arm PLLA precursors with different molecular weights. Crystallization rate and crystallinity of SM-PLLAs are strongly depressed in both nonisothermal and isothermal crystallizations, as compared to the nonfunctionalized PLLA precursors. Crystalline structure of SM-PLLAs is sensitive to the crystallization temperature (Tc). A low Tc (75–95 °C) facilitates the formation of metastable β crystals of PLLA in SM-PLLAs; while a high Tc (100–130 °C) fa...

Precipitation (or solvent displacement) method has been a simple yet efficient way to prepare the micro- and nanoparticles of polymers. However, control over the particle morphology of semicrystalline polymer is extremely challenging in the precipitation method, due to the interplay of polymer crystallization with liquid–liquid phase separation in solution. This limits the preparation of polymer particles with well-controlled morphology. Herein we report on the preparation of flower-shaped and spherical biodegradable polymer particles by precipitating the ureido-4[1H]-pyrimidione-functionalized supramolecular poly(lactic acid) (PLA) from a good solvent to an antisolvent. Morphology of PLA particles was successfully manipulated by the solution crystallization, molecular weight, and intermolecular interactions of polymer precursors. Homocrystallization of supramolecular poly(l-lactic acid) yielded the flower-shaped particles in precipitation; yet stereocomplex crystallization of PLA supramolecular copolymer...

Physical hydrogels crosslinked by non-covalent interactions have attained increasing attention due to their good mechanical properties and processability. However, the use of feasible and controllable non-covalent interactions is highly essential for preparing such hydrogels. In this article, we report on stereocomplexed physical hydrogels prepared by simple casting and swelling of amphiphilic graft copolymers bearing a poly(acrylic acid) (PAA) backbone and poly(l-lactic acid) (PLLA) or poly(d-lactic acid) (PDLA) stereocomplexable side chains. The microstructure, swelling behavior, and mechanical and shape memory properties of the obtained hydrogels can be tuned by varying the copolymer composition and stereocomplex (SC) crystallization of PLLA/PDLA enantiomeric chains. The long PLLA or PDLA chains segregate to form hydrophobic, crystallized domains in water, serving as physical crosslinking junctions for hydrogels. SC crystallization between PLLA and PDLA further enhances the number density of physical crosslinkers of enantiomerically mixed hydrogels. The SC content increases as the PLLA/PDLA ratio approaches 1/1 in enantiomerically mixed hydrogels. The average distance between crosslinking junctions declines for the hydrogels with a high PLLA (or PDLA) mass fraction (MPLA) and SC content, due to the increased number density of physical crosslinkers. Accordingly, the tensile strength and the Young's modulus increase but the swelling ratio and the elongation-at-break of the hydrogels decrease with an increase in MPLA and SC content. The hydrogels exhibit shape memory behavior; the shape fixing ability is enhanced by the SC crystallization of PLLA/PDLA side chains in the hydrogels.

Thermoresponsive block copolymer (BCP) micelles have attracted increasing attentions due to their potential in biological applications. Many studies have investigated facile strategies to tune the cloud point (Tcp) of thermoresponsive polymer, such as changing hydrophobic/hydrophilic block ratio, micelle concentration and addition of salt. Considering the dependence of properties and functions of BCPs on thermal-induced structural transition, it is necessary to understand the universal mechanism of structural changes during temperature-induced phase transition; whereas it is challenging to achieve precise structure and properties of BCP micelles with Tcp changes. Herein, we choose thermoresponsive poly (L-lactide-co-glycolide)-poly (ethylene glycol)-poly (L-lactide-co-glycolide) (PLGA-PEG-PLGA) block copolymer as a model system and utilize synchrotron-radiation small-angle X-ray scattering (SAXS) technique to systematically investigate the assembled structure of PLGA-PEG-PLGA and the mechanism for thermally induced structural transition of BCP micelle. With the increase of PLGA hydrophobic block, the Tcp significantly decreases, ascribed to the enhancement of the core size, aggregation number, as well as the packing density of PLGA in micelle core. Moreover, the increase of micelle concentration and the addition of salt also decreases the Tcp. Furthermore, temperature-induced drug release is also investigated, the release rate is much faster at above Tcp.

Thymine-terminated poly(lactic acid) (PLA-THY) and diaminotriazine-terminated poly(ethylene glycol) (PEG-DAT) are synthesized and they can form the supramolecular amphiphilic diblock copolymers in solution through the thymine/diaminotriazine complementary hydrogen bonding interactions. Such supramolecular copolymers self-assemble into the stimuli-responsive micelles in aqueous solution. Micelle size, crystalline state, stimuli responsibility, drug loading and release behavior of the supramolecular micelles can be readily tuned from the block length, stereostructure, homo and stereocomplex crystallizations of hydrophobic PLA blocks. The enantiomerically-mixed supramolecular copolymers with both poly( l -lactic acid) (PLLA) and poly( d -lactic acid) (PDLA) blocks assemble into the stereocomplexed micelles, while those having the isotactic PLLA (or PDLA) and atactic poly( d , l -lactic acid) (PDLLA) blocks form the homocrystalline and amorphous micelles, respectively. The stereocomplexed and amorphous micelles exhibit smaller size than their homocrystalline analogs, all of which are much larger than the micelles formed from the conventional covalently-bonded diblock copolymers. The supramolecular micelles are sensitive to the external stimuli such as pH and ion. The homocrystalline and stereocomplexed micelles undergo fast aggregation in the acidic and salted solutions due to the disassociation of complementary hydrogen bonds. The stereocomplexed micelles exhibit larger drug loading content and slower drug release rate than the amorphous and homocrystalline ones, because of the larger polymer/drug interactions and tighter chain packing inside the micelle cores.

This paper proposes a non-uniform quantization algorithm of soft information based on density evolution for the decoding of low-density parity check (LDPC) codes, which applies a non-linear transform function to soft information, and provides good block error rate performance. The transform function is obtained by minimizing weighted mean square quantization error for every combination of modulation type and LDPC codes and has an analytical expression of distribution of soft information. It can be realized as look-up table via quantization of transform function and has low complexity of implementation. Simulation results show that the error performance of proposed algorithm is close to no quantization condition and has a gain of around 0.3 dB compared to uniform quantization algorithm for 5G’s rate 2/3 LDPC codes with APSK modulation over additive white Gaussian noise (AWGN) channel.

Purpose – The purpose of this paper is to study the closed-loop guidance algorithm for launch vehicles in an atmospheric ascent phase and present a numerical trajectory reconstruction algorithm to satisfy the real-time requirement of generating the guidance commands. Design/methodology/approach – An optimal control model for an atmospheric ascent guidance system is established directly; following that, the detailed process for necessary conditions of the optimal control problem is re-derived based on the calculus of variations. As a result, the trajectory optimization problem can be reduced to a root-finding problem of algebraic equations based on the finite element method (FEM). To obtain an accurate solution, the Newton method is introduced to solve the roots in a guidance update cycle. Findings – The presented approach can accurately and efficiently solve the trajectory optimization problems. A moderate number of unknowns can yield a good optimal solution, which is well suited for the open-loop guidanc...

Promoting the stereocomplexation ability of high-molecular-weight poly(l-lactic acid) (PLLA) and poly(d-lactic acid) (PDLA) is an efficient way to improve the thermal resistance of the resulting materials. Herein, we studied the competing crystallization kinetics, polymorphic crystalline structure, and lamellae structure of the PLLA/PDLA component in its miscible blends with poly(vinyl acetate) (PVAc) and proposed a method to improve the stereocomplexation ability of PLLA and PDLA through miscible blending with the other polymer. Crystallization of the PLLA/PDLA component is suppressed after the addition of PVAc, due to the dilution effect. The stereocomplexation ability of PLLA and PDLA is enhanced by blending with PVAc; this becomes more obvious at a high PVAc content (≥50 wt %) but less significant with the further increase of PLLA, PDLA molecular weights. Almost exclusive formation of SCs is achieved for PLLA and PDLA after blending with a large proportion of PVAc (e.g., 75 wt %). Incorporation of PVAc also facilitates the HC-to-SC structural reorganization upon heating. The increased chain mobility, decreased equilibrium melting point, and enhanced intermolecular interactions may account for the preferential stereocomplexation in PLLA/PDLA/PVAc blends.

Constructing dual or multiple noncovalent crosslinks is highly effective to improve the mechanical and stimuli-responsive properties of supramolecular physical hydrogels, due to the synergistic effects of different noncovalent bonds. Herein, a series of tough physical hydrogels are prepared by solution casting and subsequently swelling the films of poly(ureidopyrimidone methacrylate-co-stearyl acrylate-co-acrylic acid). The hydrophobic interactions between crystallizable alkyl chains and the quadruple hydrogen bonds between ureidopyrimidone (UPy) motifs serve as the dual crosslinks of hydrogels. Synergistic effects between the hydrophobic interactions and hydrogen bonds render the hydrogels excellent mechanical properties, with tensile breaking stress up to 4.6 MPa and breaking strain up to 680%. The UPy motifs promote the crystallization of alkyl chains and the hydrophobic alkyl chains also stabilize UPy-UPy hydrogen bonding. The resultant hydrogels are responsive to multiple external stimuli, such as temperature, pH, and ion; therefore, they show the thermal-induced dual and metal ion-induced triple shape memory behaviors.

Geodynamic studies have shown that mantle convection is like a giant blender to make the original heterogeneous mantle mixing and homogenizing. However, some models, especially from geochemical data show that the modern mantle may still contain a number of reservoir bodies with different chemical composition. Then, the modern mantle is homogeneous? Authors have defined a box replacement degree of convective mantle mixing and pervasion degree of convective mantle mixing (that equals to initial density of tracing elements divided by final density of tracing elements) to investigate the mantle mixing. The previous results have shown that after four billion years the mantle is basic uniform and the box replacement of the convective mantle is more than 80% in steady-state convection models. This paper calculates and discusses the pervasion degree of convective mantle mixing in detail. For the initial state we will set some 10°×10° (spacing 0.25°) tracing boxes, which includes 1 681 tracer, at the top and bottom of the mantle, and then track the motions of these tracers, and investigate the convective mixed pervasions. The results show that at the initial stage though the convective mixing pervasions are very different from mode to mode, after running for some time, the convective mixing pervasions for most modes are going to be a constant and the tracers are more evenly distributed in the whole mantle.

In this paper, two types of autonomous navigation method based on the Sun line-of-sight (LOS) vector are proposed for the problem of orbit determination of deep space probe. The radial velocity of the spacecraft relative to the Sun is measured by a spectrometer, and the LOS vector of the reference celestial body relative to the spacecraft is measured by the onboard camera. Then, two kinds of observation scheme, one is based on the Sun information and the other is based on the line-of-sight information, are constructed combined with the LOS vector from the spacecraft to the Sun. The fundamental of the observation schemes are analyzed and the observation equations are educed in detail. The orbit parameters of the spacecraft are estimated by utilizing extended Kalman filter. Finally, the autonomous navigation methods presented are verified by the practical data of Deep Impact mission.

In this paper, an autonomous navigation scheme for interplanetary spacecraft based on the Sun line-of-sight vector measurement is proposed. In order to prove that the directional data alone can completely determine the spacecraft orbit, an analytical observability analysis is implemented through the partial derivative of the measurement equation. Then, a numerical local observability analysis is derived from the Lie derivative. Also presented is a global observability analysis by introducing the condition number of the measurement matrix. Finally, simulation results demonstrate the validity of the proposed navigation algorithm.