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Propionylated cellulose acetate (PCA) with different propionyl substitution degrees (DSPr) was synthesized, and the corresponding optical films were prepared by solution casting. The birefringence and its wavelength dispersion of PCA films stretched at 10°C above and below the glass transition temperature (Tg) with different draw ratios (DR) were studied. The introduction of propionyl group at different substitution sites present different contribution to birefringence and its wavelength dispersion. The propionyl group at C-2 and C-3 sites have a larger positive orientation birefringence with stronger inverse wavelength dispersion, while that at the C-6 site shows a higher negative orientation birefringence with weaker normal wavelength dispersion compared with the acetyl group. Compared with CA film, the introduction of the propionyl group weakens the orientation birefringence of PCA film. With the increase of DSPr from 0.023 to 0.303, the occurrence of propionyl substitution only at the C-6 site turns to C-2, C-3 and C-6 sites and the wavelength dispersion of in-plane birefringence (Δnin) decreases. When DSPr is further increased to 0.537, the Δnin and out-of-plane birefringence (Δnth) of PCA films at different DR show a very weak wavelength dispersion with the relative horizontal curves. Current results indicate that when the substitution degree of the propionyl group and acetyl group is suitable, the wavelength dispersion of PCA film can be eliminated.

Brain transcriptional regulatory network for behavior demonstrates that brain gene expression in the honey bee can be accurately predicted from the expression transcription factors (TFs), but roles for specific TFs are less understood. Mushroom bodies (MBs) are important for learning, memory and sensory integration in the honey bee brain. A transcription factor, Mblk-1, expressed preferentially in the large-type Kenyon cells of the honeybee MBs is predicted to be involved in brain function by regulating transcription of its target genes in honey bee. However its function and the mechanism of regulation in behavior of honey bee is still obscure. Here we show that Mblk-1 had significantly higher expression in the brains of forager bees relative to nurse bees. Mblk-1 was significantly inhibited in bees fed siRNA. In addition, inhibition of Mblk-1 decreased sucrose responsiveness in foragers. Finally, we determined that Mblk-1 regulated the mRNA of AmGR1. These findings suggest that Mblk-1 may target AmGR1 to regulate the sucrose responsiveness of foragers. This article is protected by copyright. All rights reserved.

We propose a unified thermodynamic model of flow-induced crystallization of polymer (uFIC), which incorporates not only the conformational entropy reduction but also the contributions of flow-induced chain orientation, the interaction of ordered segments, and the free energy of crystal nucleus and crystal morphology. Specifically, it clarifies the determining parameters of the critical crystal nucleus size, and is able to account for the acceleration of nucleation, the emergence of precursor, different crystal morphologies and structures induced by flow. Based on the nucleation barrier under flow, we analyze at which condition precursor may occur and how flow affects the competition among different crystal forms such as orthorhombic and hexagonal phases of polyethylene. According to the uFIC model, the different crystal morphologies and structures in the flow-temperature space have been clarified, which give a good agreement with experiments of FIC.

Summary Thermo-responsive polymeric metamaterials have become indispensable because of their wide applications to human-machine interaction, soft robots, wearable devices, augmented/virtual reality, etc. Polymer network-regulated sensing materials could present higher flexibility and adaptability compared to those with rigid structures or silicon-based materials, and their responses to thermal stimulation are more easily triggered and implemented compared to other stimuli, such as light, electricity, etc. Progress relies on the development of programmable materials with tunable thermal expansion on the micro-/macroscale, sheds light on this direction, and facilitates devices that exhibit unprecedented adaptation, sensitivity, and agility. and facilitates devices that exhibit unprecedented adaptation, sensitivity, and agility. This review refines the perceptual elements of positive, negative, anisotropic, tunable, and zero thermal expansion behaviors of polymers and further summarizes corresponding mechanisms, materials design, tuning methods, and related applications to flexible perceptual devices, including 2D response as sensor, 2D/3D/4D response as actuator, and insensitive response as stabilizator. The framework of research progress is presented from a single perceptual element to an integrated perceptual system, from microscopic regulation to macroscopic response. We present an overview of the current research status, which will be an important guide for future development in this field, and simultaneously provide a reference for the broader scientific community.

The molting hormone 20-hydroxyecdysone (20E) plays a key role in insect development, metamorphosis, and reproduction. Previous studies have shown that ecdysteroid metabolism is regulated by a series of CYP genes in most of the insect species. However, the roles of these CYP genes in a Coleopteran beetle, Aethina tumida (small hive beetle, SHB) have not yet been explored.In the current study, we identified seven CYP genes (six Halloween genes and one AtCYP18A1 gene) related to 20E metabolism. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) showed that AtCYP307A1 and AtCYP307B1 were primarily expressed in the embryonic stage and in the cephalothorax of larvae. RNA interference (RNAi) screening revealed that suppression of AtCYP307A1 expression caused a lethal phenotype during the larval-pupal metamorphosis. Furthermore, Hematoxylin and Eosin staining of the integument showed that the RNAi of AtCYP307A1 inhibited the apolysis and degradation of the old cuticle. In addition, silencing of AtCYP307A1 resulted in significant down-regulation of 20E titers and the expression levels of 20E signaling pathway genes. Finally, the AtCYP307A1 RNAi phenotype was rescued by topical application of 20E.Our studies suggest that AtCYP307A1 involved in 20E synthesis is indispensable during the larval-pupal metamorphosis of beetles, which could serve as a putative insecticide target for pest control. © 2022 Society of Chemical Industry.

The cyanobacterium Arthrospira platensis plays a unique role in the food industry and is a promising and valuable natural source of bioactive compounds. The culture density of A. platensis should be further increased to improve biomass production and productivity, resulting in high conversion efficiency and reducing the cost of production. In this work we utilize a series of methods to increase the biomass yield from 2.26 to 21.57 g L−1. By screening live algae filaments and removing dead algal mass via filtration before cultivation, the biomass production increased from 2.26 to 2.77 g L−1. Using response surface monitoring methodology to optimize the light intensity and initial culture density further improved biomass production to 5.97 g L−1. We also evaluated the feasibility of fed-batch and turbidostatic cultivation for enhancing biomass production of A. platensis GMPA7. The results showed that fed-batch cultivation can increase the biomass production to 15.56 g L−1. Finally, turbidostatic cultivation can further improve the biomass production to 21.57 g L−1, which is a more than eightfold increase compared to the starting culture. Therefore, the turbidostatic cultivation strategy can be further exploited for large-scale and long-term cultivation.

Cellulose acetate (CA) based films are widely used in liquid crystal displays due to their outstanding transparency, and a certain orientation birefringence of CA films is required when they are used as retardation films. The regulation of orientation birefringence is usually from the perspective of stretch-induced orientation, while the effects of crystallization behaviors of CA films remain obscure. In this study, the roles of crystallization and orientation on the orientation birefringence of CA films were elucidated. For cellulose diacetate films, the orientation birefringence is dominated by the orientation degree. In comparison, apart from the orientation degree, crystallinity is another key variable to regulate the orientation birefringence of cellulose triacetate and plasticized cellulose triacetate films, originating from the birefringence heterogeneity of the crystalline and amorphous phases. These results provide valuable guidelines for the production of CA-based optical films with excellent optical performance.

The sun (∼6,000 K) and outer space (∼3 K) are two significant renewable thermodynamic resources for human beings on Earth. The solar thermal conversion by photothermal (PT) and harvesting the coldness of outer space by radiative cooling (RC) have already attracted tremendous interest. However, most of the PT and RC approaches are static and monofunctional, which can only provide heating or cooling respectively under sunlight or darkness. Herein, a spectrally self-adaptive absorber/emitter (SSA/E) with strong solar absorption and switchable emissivity within the atmospheric window (i.e., 8 to 13 μm) was developed for the dynamic combination of PT and RC, corresponding to continuously efficient energy harvesting from the sun and rejecting energy to the universe. The as-fabricated SSA/E not only can be heated to ∼170 °C above ambient temperature under sunshine but also be cooled to 20 °C below ambient temperature, and thermal modeling captures the high energy harvesting efficiency of the SSA/E, enabling new technological capabilities.

Numerical experiments on phase field modeling of the fracture in pre-strained hyperelastic materials reveal that the classical mechanical-based dynamic phase field model is ineffective in the framework of non-linear deformation. The aspiration to gain insight into rapid fracture instability motivated us to develop a novel dynamic phase field model characterized by wave velocity invariance, enabling crack propagation at a velocity approach to the asymptotic limit. Given that the numerical treatment of rapid fractures involves extremely high spatiotemporal resolution, robust explicit dynamics and a tried-and-tested multi-level hybrid adaptive mesh algorithm are invoked. More crucially, an original adaptive distorted mesh removal scheme (ADMR) was developed to cope with the intractable finite element mesh distortion problem in large deformation fractures. The detailed numerical implementation for entire procedures is outlined, and its reliability is verified by two quasi-static fracture benchmarks. Utilizing the proposed model and innovative algorithms, the arresting ultrahigh-speed crack oscillation and tip-splitting instabilities captured in the fracture experiments of brittle gels were successfully reproduced. The critical crack velocity at the onset of the instability is also identified, close to the experimental measurements.

Polymer chains in both dilute solutions and melts undergo cyclic rotation and retraction, which is known as tumbling, under steady shear flow. However, it is still not known how the individual molecules in melts rotate freely under the constraints caused by surrounding chains. In this work, a Brownian dynamics simulation is used to investigate the influences of the interchain interactions on the polymer chain motions in both dilute solutions and melts under steady shear flow. Compared with previous simulation studies, a greater number of similarities and differences between tumbling in dilute solutions and melts are addressed, and the results explicitly suggest the critical role of the entanglements in melts during shear flow. Three components of the gyration radius in different directions [flow direction ( ⟨ R g x 2 ⟩ ), gradient direction ( ⟨ R g y 2 ⟩ ), and vorticity direction ( ⟨ R g z 2 ⟩ )] are shown to exhibit different dependencies on the shear rate depending on whether dilute solutions or melts are being examined. However, the characteristic tumbling times τ r in both cases are proportional to γ ˙ − 2 / 3. The distributions P ( T ) of time T that the chains spend in each tumbling cycle show that both states exhibit an exponential decay of P ( T / τ r ) in the high- T region. In the low- T region, P ( T / τ r ) in the melts with variable shear rates are coincident with each other, while P ( T / τ r ) in dilute solutions show different shapes. With respect to the distributions of chain orientation, both cases show the same scaling relationships for shear rates and chain lengths. Based on these findings, main conclusions are as follows. The entanglements still restrict the evolutions of polymer chain configurations despite the number of entanglements decreasing with increased flow strength. The tumbling motion in melts can occur inside the tube, and the chain behaviors inside the confining tubes are rather similar to those in dilute solutions.

By employing a variational phase field model, we investigated the dynamic brittle fracture of poly (methyl methacrylate) (PMMA) through computer simulation. Without the explicit fracture criterion, current simulations not only successfully reproduced the crucial experimental observations on crack propagation, such as crack patterns, velocity evolutions and limit crack velocity but also discovered some new features not reported in the experimental study yet. Through quantifying the energy flux into the crack tip and fracture energy, we observed that the crack bifurcation of PMMA always occurs with the energy flux into the crack tip exceeding a critical value and proposed that crack bifurcation obeys an energy criterion. Based on this criterion, the long-standing challenge of limit crack velocity in experiments is successfully predicted by continuum theory, which unveils that crack bifurcation sets the upper limit for crack velocity. Combining the crack bifurcation criterion and continuum theory provides a rational explanation for complex path selection of cracks.

Stretch-induced crystallization (SIC) and structural transitions of poly(dimethylsiloxane) (PDMS) filled with different contents of nanosilica were studied with an in situ synchrotron radiation wid...

The stretch-induced structural evolution mechanism is a long-standing scientific question in the post-stretching processing of polymer films. X-ray scattering, especially a combination of small- and wide-angle X-ray scattering (SAXS/WAXS), provides a powerful method to study the hierarchical structure of polymer films. Recent advances in synchrotron radiation (SR) light sources and detection techniques allow one to measure the structural evolution of polymer films during post-stretching processing in real time with ultrahigh time resolution, which benefits the understanding on this topic. This review summarizes some recent investigations on post-stretching processing of polymer films, which combine in situ X-ray scattering techniques with purposely designed tensile apparatus in terms of three aspects: uniaxial stretching, biaxial stretching and stretching with chemical reactions. Concerning the polymer bulk, traditional deformation mechanisms like stretch-induced crystallization (SIC), crystal slipping, phase transition and melting-recrystallization are discussed for the uniaxial and biaxial post-stretching of polymer films. New deformation models have been developed to focus on the structural evolution on the length scale of lamellar stacks, which consider the potential microphase separation of the interlamellar amorphous phase and microbuckling. For solution systems, the coupled effects of the mechanical work from external force and the chemical potential from possible chemical reactions are taken into account for the structural evolution during stretching in solution. Roadmaps of structural and morphological evolution in the processing parameter space (i.e., temperature, stress, strain and the concentration of additive in the bath solution) are eventually constructed for precursor films. The accumulation of a structural evolution database for post-stretching processing of polymer films can be expected to provide a helpful guide for industrial processing for high-performance polymers in the near future.

The hierarchical structural evolution of natural rubber (NR) filled with different contents of nanoscale carbon black (CB) (10 phr-CB10 and 50 phr-CB50) after first loading and recovering for different times was investigated by X-ray nano-CT, wide-angle X-ray scattering (WAXS) and solid state NMR techniques. The CB filler structures as captured by X-ray nano-CT recover gradually with increasing recovering time, but the filler network with different CB contents shows dramatically different structure evolution. For CB10, limited by the filling content, CB particles mainly induces a hydrodynamic effect in spite of deformation or recovering. For CB50, the CB filler forms a 3D connected network, partially destructed during deformation, and the destructed part can be partially recovered during recovery. This suggests that the connected CB filler structure mainly acts as a network reinforcement, whereas the destructed part can induce a hydrodynamic effect. The different effects induced by different CB filling contents are also reflected by the NR matrix, which is reflected by the onset strains εc of strain-induced crystallization (SIC) of NR as captured by WAXS. For CB10, εc remains almost constant, i.e. εc = ca. 1.49, while that of NR with CB50 slightly decreases from initial ca. 1.12 to 0.96 with increasing recovering time up to 50 h. Also, the bound rubber fraction and entangled rubber network remain unchanged after deformation and under different recovery time as detected by the magic sandwich echo (MSE) FID and proton multiple quantum (MQ) NMR. These results demonstrate the key role of the CB filler network in determining the stress-softening behavior of reinforced rubber.

U, Sr, Pb, Nd, and Hf isotope ratios can provide basic and important information of nuclear materials. We established a simple and efficient column chemistry method using nano-NaBiO

A biaxial stretching device is designed and developed for the real-time structural measurements of polymer films. This device adopts a vertical layout to perform real-time x-ray scattering measurements. It has a maximum stretching ratio of 8 × 8 in two perpendicular directions. Its maximum experimental temperature and stretching rate are 250 °C and 100 mm/s, respectively. The control accuracies of the experimental temperature and stretching rate are ±1 °C and 0.01 mm, respectively. All the parameters related to film biaxial processing, such as stretching speed, stretching ratio, and temperature, can be independently set. The device feasibility is demonstrated via a real-time experiment in a synchrotron radiation beamline. Wide-angle x-ray diffraction, small-angle x-ray scattering, and stress–strain data can be simultaneously obtained during various stretching modes. The proposed device fills the gap between the synchrotron radiation x-ray scattering technique and the biaxial stretching processing of polymer films. This device will play an important role in improving the understanding of the physics behind biaxial polymer processing.

The general aspects of polymer crystallization under external flow, i.e., flow-induced crystallization (FIC) from fundamental theoretical background to multi-scale characterization and modeling results are presented. FIC is crucial for modern polymer processing, such as blowing, casting, and injection modeling, as two-third of daily-used polymers is crystalline, and nearly all of them need to be processed before final applications. For academics, the FIC is intrinsically far from equilibrium, where the polymer crystallization behavior is different from that in quiescent conditions. The continuous investigation of crystallization contributes to a better understanding on the general non-equilibrium ordering in condensed physics. In the current review, the general theories related to polymer nucleation under flow (FIN) were summarized first as a preliminary knowledge. Various theories and models, i.e., coil–stretch transition and entropy reduction model, are briefly presented together with the modified versions. Subsequently, the multi-step ordering process of FIC is discussed in detail, including chain extension, conformational ordering, density fluctuation, and final perfection of the polymer crystalline. These achievements for a thorough understanding of the fundamental basis of FIC benefit from the development of various hyphenated rheometer, i.e., rheo-optical spectroscopy, rheo-IR, and rheo-x-ray scattering. The selected experimental results are introduced to present efforts on elucidating the multi-step and hierarchical structure transition during FIC. Then, the multi-scale modeling methods are summarized, including micro/meso scale simulation and macroscopic continuum modeling. At last, we briefly describe our personal opinions related to the future directions of this field, aiming to ultimately establish the unified theory of FIC and promote building of the more applicable models in the polymer processing.

Cost-effective, representative and spatial coverage sampling designs are required to monitor the effects of potentially toxic elements (PTEs) in the soil. This study aims to evaluate the minimum sample sizes and placement of soil sampling designs to monitor and characterize the spatial variation of the PTEs (Cu, Zn, Cd, Cr, Pb, and Ni) in the soils. However, there is no standardized approach for evaluating the optimum soil sample size and monitoring location because of the spatial heterogeneity of PTEs in the soil. As a result, three broad techniques were applied. The first step was to use Global Moran's I and q-statistic values to describe the variability of soil PTEs and select appropriate evaluation methods. Second, using simple random sampling (SRS), ordinary kriging (OK), and Mean of Surface with Non-homogeneity (MSN), we estimated and evaluated soil PTEs in the current soil sampling schemes. Finally, MSN and spatial simulated annealing (SSA) optimization techniques were used to assess the required sample sizes and placements in the existing designs. Method performance was evaluated using a standard error (SE) and a relative standard error of the mean (RSE). Except for Zn and Cd, all PTEs tested showed heterogeneous distributions over the area. The MSN lowered the predicted SE by 79-86 % compared with SRS. The OK approach also outperformed the SRS method regarding mean estimated values of soil PTEs by 42-57 %. After SSA refined the initial design, the predicted SE by MSN of Cr and Zn was lowered by 13 % and 39 %, respectively. The MSN was effective with small sample sizes, reducing sample sizes and surveying costs by 39 % after SSA optimized the existing sample numbers. Thus, integrating various sampling strategies may be efficient for building optimal sample designs to monitor PTEs in the soil.

We study the process e^+e^− → π^+π^−ηγ, where the photon is radiated from the initial state. About 8000 fully reconstructed events of this process are selected from the BABAR data sample with an integrated luminosity of 469 fb^(-1). Using the π^+π^−η invariant mass spectrum, we measure the e^+e^− → π^+π^−η cross section in the e^+e^− center-of-mass energy range from 1.15 to 3.5 GeV. The cross section is well described by the Vector-Meson dominance model with four ρ-like states. We observe 49±9 events of the J/ψ decay to π^+π^−η and measure the product Γ_(J/Ψ → e^+e^−)B_(J/Ψ → π^+π^−η) = 2.34 ± 0.43_(stat) ± 0.16_(syst) eV.

Simple Summary The small hive beetle is a destructive pest of honeybees, causing severe economic damage to the apiculture industry. Chemosensory genes play key roles in insect behavior, such as foraging and mating partners. However, the chemosensory genes are lacking in the small hive beetle. In order to better understand its chemosensory process at the molecular level, a total of 130 chemosensory genes, including 38 odorant receptors, 24 ionotropic receptors, 14 gustatory receptors, 3 sensory neuron membrane proteins, 29 odorant binding proteins, and 22 chemosensory proteins were identified from the transcriptomic data of antennae and forelegs. Reverse-transcription PCR showed that 3 OBPs (AtumOBP3, 26 and 28) and 3 CSPs (AtumCSP7, 8 and 21) were highly expressed in antennae. Overall, this study could provide a basis for elucidating functions of these chemosensory genes at the molecular level. Abstract Aethina tumida is a parasite and predator of honeybee causing severe loss to the bee industry. No effective and environmentally friendly methods are available to control this pest at present. Chemosensory genes play key roles in insect behavior which can potentially be used as targets for developing environmentally friendly pest control agents. In this study, the putative chemosensory genes in antennae and forelegs of A. tumida involved in olfaction or contact chemical communication of adults were investigated using RNA transcriptome sequencing and PCR methods. Based on transcriptomic data, unigenes encoding 38 odorant receptors (ORs), 24 ionotropic receptors (IRs), 14 gustatory receptors (GRs), 3 sensory neuron membrane proteins (SNMPs), 29 odorant binding proteins (OBPs), and 22 chemosensory proteins (CSPs) were identified. The analyses of tissue expression profiles revealed that genes encoding 38 ORs, 13 antennal IRs, 11 GRs, 1 SNMP, 24 OBPs, and 12 CSPs were predominately expressed in antennae. No significant differences in expression levels of these genes were found between males and females. Genes encoding 5 non-NMDA iGluRs, 3 GRs, 2 SNMPs, 5 OBPs, and 12 CSPs were predominately expressed in forelegs. RT-PCR assays for SNMPs, OBPs and CSPs further revealed that 3 OBPs (AtumOBP3, 26 and 28) and 3 CSPs (AtumCSP7, 8 and 21) were highly expressed in antennae. Our results enrich the gene inventory of A. tumida and facilitate the discovery of potential novel targets for developing new pest control measures.