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With the goal of developing an accurate and fast image reconstruction algorithm for ultrasound computed tomography, we combine elements of model- and data-driven approaches and propose a learned method which addresses the disadvantages of both approaches. We design a deep neural network which accounts for a nonlinear forward operator and primal-dual algorithm by its inherent network architecture. The network is trained end-to-end, with ultrasound pressure field data as input to get directly an optimized reconstruction of speed of sound and attenuation images. The training and test data are based on a set of Optical and Acoustic Breast Phantom Database, where we use the image as ground truth and simulate pressure field data according to our forward model. Extensive experiments show that our method achieves significant improvements over state-of-the-art reconstruction methods in this field. Experiments show that the proposed algorithm improves the measures structural similarity measure (SSIM) from 0.74 to 0.95 and root mean squared error (RMSE) from 0.13 to 0.09 on average concerning the speed of sound reconstruction, while it improves the SSIM from 0.60 to 0.94 and RMSE from 0.24 to 0.10 on average in attenuation reconstruction.

Hexokinases (HXKs) have determined to be multifaceted proteins, and they are the only ones able to phosphorylate glucose in plants. However, the binding mode for ATP to plant HXKs remains unclear. Here, we report the crystal structures of rice hexokinase 6 (OsHXK6) in four different forms: (i) apo-form, (ii) binary complex with D-Glc, (iii) quaternary complex with ADP, PO4 and Mg2+, and (iv) pentanary complex with D-Glc, ADP, PO4, and Mg2+. The apo form is in the open state conformation, and the three others are in the closed state, indicating that glucose and ADP-PO4 binding induces a large conformational change by domain rearrangement. The quaternary complex is a novel intermediate during the catalytic reaction we trapped for the first time, which provides a new evidence for the enzymatic mechanism of HXKs. In addition, the latter two complexes reveal the binding mode for ADP-PO4 to plant HXKs, which provide the structural explanation for the dual-function of OsHXK6. In addition, we identified that residues Gly112, Thr261, Gly262, and Gly450 are essential to the binding between ADP-PO4 and OsHXK6 by a series of single mutations and enzymatic assays. Our study provide structural basis for the other functional studies of OsHXK6 in rice.

Based on our recent work on the three-dimensional graphene fillers (3DGF) reinforced epoxy (EP) composite, here commercially available graphite platelets (GP) were incorporated together with 3DGF to modify EP in order to further improve the thermal conduction and wear resistance of the EP composites. Remarkably, only 0.14 vol% 3DGF was needed to enhance the thermal conduction of EP by 170%, in contrast with the fact that 37 times content of graphite fillers were required to achieve almost the same enhancement. Moreover, in the presence of both 5.38 vol% GP and 0.14 vol% 3DGF, the thermal conductivity of EP was further enhanced by 258%. Meanwhile, the tribological test results revealed the advantage of 3DGF over GP. The ternary EP composite modified with both 0.28 vol% of 3DGF and 5.38 vol% GP had much lower specific wear rate and coefficient of friction than those binary composites with either 3DGF or GP.

A series of reduced lipophilic N-benzylic imidazo[1,2-a]pyridine carboxamides (IPAs) with various side chains were designed and synthesized as new anti-TB agents in this work. Five derivatives A2, A3, A4, B1 and B9 exhibit excellent in vitro activity (MIC:0.035 μM) against the drug susceptive Mycobacterium tuberculosis H37Rv strain and two clinically isolated multidrug-resistant strains, and acceptable PK properties. Compound B1 bearing a cyclohexylmethyl piperazine moiety, the same side chain of PBTZ169, was found to have obviously greater AUC

We report herein the design and synthesis of a series of novel nitrobenzamide derivatives. Results reveal that many of them display considerable in vitro antitubercular activity. Four N-benzyl or N-(pyridine-2-yl)methyl 3,5-dinitrobenzamides A6, A11, C1 and C4 have not only the same excellent MIC values of 1500), opening a new direction for further development.

Covalent organic framework (COF) is an emergent class of ordered porous materials with high stability. The fabrication of thin and continuous COF membrane for small molecule separation remains challenging due to the relatively large pore size of COF materials and weak COF-substrate interfacial interaction. Herein, a two-dimensional COF layer was spin-coated on a porous substrate followed by constructing a bio-inspired calcium alginate (Alg-Ca) layer to obtain a dual-layer membrane with a thickness less than 100 nm. The Alg-Ca layer afforded a superhydrophilic surface to capture water molecules, and the porous COF layer rendered selective water channels. The dual-layer membrane synergistically strenthened the solution-diffusion mechanism through the manipulation of the membrane structure and transport process. The synergy of two layers endowed the membrane with superior water-selective performance with permeation flux of 3614 g/(m2h) and water content in permeate of 99.7 wt% for n-butanol dehydration. The fabrication of dual-layer membrane in this study may offer a new strategy for highly efficient separation of liquid small molecule mixtures.

Constructing mass transfer highways in polymer membranes via fillers with hierarchical porous and/or hollow structure is an effective approach to enhance their separation performance. In this study, novel hierarchical porous organosilica nanotubes (HPSiNT) were designed and incorporated into Pebax matrix to fabricate hybrid membranes for organic solvent separation. The HPSiNT, with plenty of micropores (∼1.6 nm) on the wall of nanotubes and atomically smooth meso-inner channels (∼6 nm), offer abundant entrances and rapid diffusion pathways for penetrant molecules, thus endowing the hybrid membranes with superior separation performance. Employing thiophene/ n -octane feed solution as a model system, the hybrid membrane that consists of 2 wt% HPSiNT exhibited a high permeation flux of 19.0 kg/(m 2 h) (increased by 66.8% compared with pure Pebax membrane) and thiophene/ n -octane enrichment factor of 5.5 (increased by 11.7% compared with pure Pebax membrane), respectively. Introducing hierarchical nano-channels in polymeric matrices could open a new avenue to designing hybrid membranes with high permeation flux.

Hybrid membranes with 2D vertical continuous channels are expected to achieve high separation performance, but remain unexplored. In this study, 2D vertical continuous channels from layered double hydroxide (LDH) array were constructed in hybrid membranes for pervaporation dehydration. Vertically aligned LDH array that anchored onto the polyacrylonitrile substrate via in situ hydrothermal synthesis was employed to provide intrinsic continuous channels with an interlayer distance between water and ethanol. Sodium alginate impregnated into interstitial space of LDH array ensured a leakage-free and mechanical strength of membranes. The height of LDH array within hybrid membranes could be facilely manipulated from 1.5 μm to 3.6 μm through altering the hydrothermal reaction time and Co2+/Al3+ ratio. Comparing hybrid membranes with randomly oriented LDH, the hybrid membrane with vertically aligned LDH array exhibites optimal water permeability of 7742 Barrer together with a desirable selectivity of 1903 when the reaction time is 10 h, and Co2+/Al3+ ratio is 2. This study provided an innovative avenue to fabricating high-performance hybrid membranes with 2D vertical continuous channels.

A simple method to fabricate three-dimensional graphene fillers (3DGFs) modified epoxy resin (EP) composite was developed in this study. This method offers a flexible fabrication process and the polymer composites obtained preserve to some extent the advantages of the traditional 3D graphene foam structure. The thermal conductivity of 3DGF/EP composites was increased successfully to 0.52 W/mK with only 0.14 vol% (0.27 wt%) graphene loading which is 1.74 times higher than that of the neat epoxy. This remarkable improvement normalized by graphene loading (i.e., the thermal conductivity enhancement efficiency) is amongst the highest reported values of carbon-based nanofiller-epoxy composites. The unique hollow 3D structure, defect-free feature and large length-thickness ratio of 3DGF compared to conventional graphene sheets are responsible for the high thermal conductivity of the epoxy composite. Further, finite element analyses also confirmed the positive effect of the filler length-thickness ratio on the thermal conductivity of 3DGF/EP composites which agreed well with experimental results. Moreover, the tribological performance of the composites was also improved by incorporation of 3DGFs.

The existence of drug resistance is the main reason for chemotherapeutic failure in malignancies. Long non-coding RNA (lncRNA) maternally expressed gene 3 (MEG3) is implicated with tumorigenesis and chemoresistance. In the present study, we aimed to identify the role of MEG3 in oxaliplatin-resistant colorectal cancer (CRC) and its potential mechanisms. MEG3 was down-regulated in oxaliplatin-resistant CRC tissues and cell lines. Low MEG3 expression was correlated with poor prognosis of CRC patients. Overexpression of MEG3 improved oxaliplatin sensitivity of HT29/OXA and HCT116/OXA cells. MEG3 suppressed miR-141 expression in HCT116/OXA cells. Moreover, MEG3 elevated PDCD4 expression through targeting miR-141, acting as a competing endogenous RNA (ceRNA). miR-141 inhibition or PDCD4 up-regulation could mimic the functional role in oxaliplatin resistance, which was counteracted by overexpression of MEG3. Collectively, MEG3 facilitated the sensitivity of CRC cells to oxaliplatin by regulating miR-141/PDCD4 axis, providing a novel therapeutic strategy for CRC.

Graphene oxide quantum dots (GOQDs), which inherit the monolayer of sp2 carbon atoms structure and hydrophilic groups as graphene oxide (GO) sheets, but with a quantum lateral size less than 100 nm, may hold great promise in membrane preparation. In this study, a novel nanocomposite membrane by mixing GOQDs with sodium alginate (SA) matrix was prepared for ethanol dehydration. GOQDs with an average lateral dimension around 3.9 nm provided additional shorter and less tortuous transport pathways for water molecules to penetrate the membrane compared to microsized GO sheets. Benefiting from the nanosize and high hydrophilicity of GOQDs, the nanocomposite membrane exhibited favorable ethanol dehydration performance with a total permeation flux of 2432 ± 58 g m−2 h−1, which was 60% higher than that of pristine alginate membrane, and a separation factor of 1152 ± 48. Incorporating GOQDs into the membranes can be an effective approach to improving the water permeation for water-permselective pervaporation membranes.

Sandwich composite panels (SCPs) with carbon fibre reinforced plastic (CFRP) facings are usually vulnerable to low-velocity transverse impact loading. In this study, a method is presented to improve the impact resistance and energy absorption capacity of CFRP-faced SCPs by filling them with a concentrated styrene/acrylate particle based shear thickening fluid (STF). First, for the STF alone, aspects of mechanical performance, namely rheological and low-velocity impact behaviours, were systematically examined. It was found that the critical shear stress of the STF was lower than that of silica particle based STF with a similar particle size and volume fraction, indicating that shear thickening was more easily achieved in the styrene/acrylate particle based STF. In addition, the STF exhibited much higher energy absorption capacity than an aluminium foam. Finally, low-velocity transverse impact experiments were performed on STF-filled SCPs with two core thicknesses, 7.2 mm and 12.7 mm. It was shown that the absorbed energy of the SCPs with a thin core increased by up to 99.3%, while the impact damage of SCPs with a thick core could be effectively suppressed on the back surface of the SCPs. The impact mechanism of the STF-filled SCPs is also discussed. This study provides a new method for the design of impact-resistant SCPs.

Molybdenum disulfide (MoS2), as an emerging kind of two-dimensional (2D) materials with large hydrophobic surface and superior mechanical property, holds great promise in preparing high-performance hybrid membranes. In this study, MoS2 nanosheets were embedded within sodium alginate (SA) for ethanol/water separation. Morphology, structure, mechanical and thermal properties of the membranes were characterized. The incorporation of MoS2 nanosheets affected the microstructure of the membranes. The Young’s modulus of the as-fabricated hybrid membrane was enhanced by 57%, and the swelling degree was reduced by 33% compared to SA pure membrane. Besides, the ordered stacking of MoS2 nanosheets, as well as their interlayer spacings, provided transport channels for water molecules. The fast transport of water molecules on the MoS2 surface is the reason that an optimum ethanol dehydration performance was achieved when the MoS2 content was 2 wt%. In ethanol/water (90/10 wt%) solution at 350 K, the permeation flux was 1839 g/(m2 h) (54% higher than that of SA/PAN pure membrane), and the separation factor was 1229 (85% greater than that of SA/PAN pure membrane). Moreover, the hybrid membrane exhibited good long-term operation stability.

Crack detection in welded structures of dissimilar material using guided waves is not well developed. This paper scrutinizes the effect of material discontinuity in plate structures and the excessive plastic deformation, within friction stir welded (FSW) joints, on the propagation behavior of guided waves toward their application in weld assessment. Quantifying the scattering, attenuation and group velocities of the guided waves when they propagate across different media, as well as determining the elastic properties of the material within the weld will provide rich information about the behavior of ultrasonic waves. Three pristine defect free friction stir welded plates were used in this study. The first specimen was a weld of dissimilar materials aluminum/magnesium alloy (AA6061-T6/AZ31B), the second was of dissimilar aluminum alloy grades (AA6060/AA7020-T651), and the third was of the same aluminum grade (AA7020-T651/AA7020-T651). The elastic properties across all the welds were extrapolated using nano-indentation technique. Ultrasonic guided waves were excited and measured using piezoelectric wafers and laser Doppler vibrometer (LDV). Additionally, a sensor network design was implemented on the three specimens using piezoelectric transducers. Wave reflections, based on the LDV results and the information collected from the sensor network, were observed at the weld zone of the AA6061-T6/AZ31B FSW plate, while no reflections were detected at the weld zones in the AA7020-T651/AA7020-T651 and AA6060/AA7020-T651 plates. The results were correlated with the measurements obtained from the nano-indentation experiment, where a sharp change in the elastic properties of the base metals in the AA6061-T6/AZ31B welded joint were detected, unlike the other two plates that showed constant elastic properties across the weld zones. The results showed that the amount of scattering at the joints is a function of the wave propagation direction. It was noticed that the average wave reflection generated when the wave crossed from the AZ31B to the AA6061-T6 base metal was around 35% of the incident signal, but it reduced to 25% when the wave propagation direction was reversed. Characterizing ultrasonic waves in FSWs and the behavior of the incident and reflected waves in the welded zones will further improve on the technology used for inspection and monitoring of solid state welded joints.

A novel approach, continuous needleless electrospinning from the tips of magnetization-induced self-assembling PVA/ferrofluid cone array, was proposed to prepare magnetic nanofibers. A PVA/ferrofluid was synthesized, the needleless electrospinning process was observed, and the morphology and magnetic properties of magnetic nanofibers were investigated. The results showed that the PVA/ferrofluid could remain stable and homogeneous for 21 days under the magnetic field gradient (2.2 mT/mm). “Taylor cone” array of PVA/ferrofluid was self-assembled under both the magnetic and electric fields. As the electric voltage reached 25 kV, the jets were emitted from the “Taylor cone” array, resulting in needleless electrospinning of magnetic nanofibers. Magnetic nanofibers were homogeneous and continuous with an average diameter of 73.6 nm. Magnetic nanofibers showed a good magnetic response property and relatively high saturated magnetization (1.71 emu/g), which is expected to be applied in the biomedical field.

It’s highly desired to design and fabricate effective Z-scheme photocatalysts by promoting the charge transfer and separation. Herein, we firstly fabricated the ratio-optimized g-C3N4/α-Fe2O3 nanocomposites by adjusting the mass ratio between two components through a simple wet-chemical process. The resulting nanocomposites display much high photocatalytic activities for CO2 conversion and phenol degradation compared to bare α-Fe2O3 and g-C3N4. Noteworthily, the photocatalytic activities are further improved by constructing Al O bridges, by 4-time enhancement compared to those of α-Fe2O3. Based on the steady-state surface photovoltage spectra, transient-state surface photovoltage responses, photoelectrochemical I-t curves and the evaluation of produced OH amounts, the exceptional photoactivities of Al O bridged g-C3N4/α-Fe2O3 nanocomposites are attributed to the significantly promoted charge transfer and separation by constructing the g-C3N4/α-Fe2O3 heterojunctions and the Al O bridges. Moreover, the charge transfer and separation of this photocatalyst have been confirmed to obey the Z-scheme mechanism, as supported by the single-wavelength photocurrent action spectra and single-wavelength photoactivities for CO2 conversion. Furthermore, the mechanism of the photocatalytic CO2 conversion has been elaborately elucidated through the electrochemical reduction and the photocatalytic experiments especially with isotope 13CO2 and D2O, that the produced H atoms as intermediate radicals would dominantly induce the conversion of CO2 to CO and CH4.

Covalent organic frameworks (COFs) with well-ordered pore structures and versatile functionalities hold tremendous promise as membrane building blocks. The facile and controllable fabrication of COF membranes remains a critical challenge. Herein, we presented a one-step vapor-liquid interfacial polymerization (VLIP) method to in-situ fabricate COF membranes on substrates under mild conditions. This VLIP method features controllable COF growth at the vapor-liquid interface, acquiring COF membranes with tunable physicochemical structure. The time-dependent amorphous-to-crystalline COF growth improved the crystallinity of COF membranes, thus improving the molecular sieving property. The increased monomer concentration endowed COF membranes with higher hydrophilicity, intensifying the water sorption ability. The resultant COF membranes conferred numerous hydrophilic pathways for water-selective transport, exhibited a high and stable n-butanol dehydration performance with permeation flux of 8160 g m−2 h−1 and separation factor of 1023 over 14 days. This VLIP method may evolve into a generic platform technique to fabricate COF membranes for efficient molecular separation.

COF (covalent organic framework)-based composite membranes offer the opportunity for breakthroughs in separation performance through endowing COFs with easy film-forming properties. However, tough challenges of poor filler dispersity, limited functionality and interfacial compatibility severely restrict the development of COF-based composite membranes. Therefore, the careful design of physical and chemical structures for COFs is urgently needed. Here, a geometry transformation strategy, i.e. converting FCTF-1 (fluorinated covalent triazine frameworks) from 2D nanosheets to 0D quantum dots (QDs), is implemented to overcome some of the challenges. The greatly decreased filler size increases the solvent dispersibility and processability of FCTF-1 quantum dots (QD-FCTF-1), giving rise to thorough mixing between the polymer matrix and quantum dot filler. Apart from the changes in physical characteristics of filler, the geometry transformation using piranha solution introduces chemical functionality at the quantum dot edges, further strengthens the interfacial compatibility through the hydrogen bond interactions between polar hydroxy and amidine groups of QD-FCTF-1 and nitrile groups of PIM-1 (polymer of intrinsic microporosity). Moreover, these edge polar groups intensify favorable gas sorption due to their high affinity to CO2 molecules and thus significantly improve membrane gas pair selectivity. This work broadens the scope of framework-based materials and offers a new avenue for molecular separation.

In the present work, continuous carbon fibre (CCF) reinforced polyamide 6 (PA6) composites were fabricated using the Fused Filament Fabrication (FFF) 3D printing technique. The sliding friction and wear behaviour of the printed CCF/PA6 composites was investigated as a function of varying fibre orientations (i.e. normal, parallel, and anti-parallel) and layer deposition directions (i.e. parallel and perpendicular) with respect to the sliding direction. It emerged that fibre orientation played a key role in determining the wear resistance of 3D printed composites. Severe fibre breakage was observed when the orientation of fibre was in normal direction against the sliding direction, associated with a higher wear rate than that obtained in parallel or anti-parallel direction. To better understand the effects of voids on wear mechanism, tribo-tests were further carried out with the specimens that underwent compression moulding (CM) post-treatment process. The results confirmed that the internal defects could cause adverse impacts on wear performance, depending on the fibre orientations. In particular, it was found that fibre distribution, as well as the fibre/matrix interface within the filament, was the crucial parameter affecting the overall tribological performance of the printed structures. The findings add to our understanding of designing and fabricating wear-resistant polymer composites using 3D printing technologies.

This work investigates the drilling responses of carbon fibre reinforced plastic (CFRP) composite sandwich panels (CSPs). First, the effects of drill geometries, feed rates and support conditions on the peak thrust force and delamination area of the CSPs with different core thicknesses were experimentally studied. Then, finite element analysis (FEA) was performed to model the intra-laminar damage and inter-laminar delamination of the CFRP face sheets, as well as the failure of the adhesive and honeycomb core. The FEA models were validated by experiments in terms of drilling responses and damage behaviours. The results show that the maximum errors of the peak thrust force in between the FEA-predicted and experimental results are 12.5% and 7.5% for the CFRP and CSPs, respectively. Finally, the damage mechanism analysis and parametric study for the CSPs under drilling were examined.

Rock fracture toughness is an important parameter for the engineering geological design. In this present study, chevron straight-notched semi-circular bend (CSNSCB) specimens with wide-flat liner chevron ligament (Type-A) and long-narrow liner chevron ligament (Type-B) were designed and prepared using wire cutting method. Mode-I fracture toughness KIC values and dimensionless stress intensity factor Y* were calculated. Moreover, these two types rock failure properties and KIC values variation features were both analyzed. The obtained results indicate that the width of precast artificial crack is small which can ensure the flatness and symmetry of cutting plane and then the tested Stress Intensity Factor (SIF) which has smaller deviation is more accurate and reliable. The Y* values for each type of configuration were calculated using Finite Element Method (FEM) and Slice Synthesis Method (SSM) and they firstly had a decreased trend and then an increased trend with the increasing of normalized crack length α, which represent the transition from stable crack propagation (α > αm) to unstable crack propagation (α

Cyanobacterial blooms have become an urgent threat to the aquatic ecosystem, but early warning of the blooms is still challenging for the research community. In this paper, a method based on polarized light scattering and powered by machine learning is proposed to in-situ early warn the cyanobacterial blooms. In this work, the wild types of Microcystis are treated and the cells are individually measured to obtain their polarization parameters. The experimental results show that machine learning algorithms can be used to well identify the states of the Microcystis cells, and the compositions of the mixed samples can be effectively retrieved by this method. Subsequently, one application strategy is suggested to early warn the blooms, which is potential and powerful to achieve the in-situ early warning of cyanobacterial blooms in the future.

Tribological behaviour of poly ether-ether ketone (PEEK) loaded with different amount of titanium oxide (TiO 2 ) nanoparticles were investigated by pin-on-disk test followed by the characterization of associated transfer film layer (TFL) with the help of nanoindentation. PEEK loaded with 5% TiO 2 nanoparticles exhibit lowest specific wear rate in both dry and water lubricated conditions mainly due to the formation of characteristic transfer film layers and water lubrication, respectively. Intrinsic molecular structure of PEEK synergise tribological responses when reinforced with nano-particles. The inbuilt nature of PEEK in contact with water cause matrix relaxation which in turn overshadows the benefit of nanoparticles addition beyond 5% in PEEK composite and overall outcome is the inferior wear-rate of PEEK composites compared to dry tests condition.

Extraordinary mass transfer phenomenon is usually found when the small molecules pass through a confined structure, whose effective size is commensurate with the mean free path of the molecules. Small changes in the confined mass transfer structure (including size, morphology and properties) will lead to significant fluctuations of the mass transfer coefficient. The mass transfer of the penetrant molecules in the dense membranes for pervaporation, gas separation and so on, is located in the scope of confined mass transfer. Incorporating nanofillers into polymer matrix to construct mixed matrix membranes (MMMs) is an effective approach to tune the confined mass transfer structure and enhance the performance of the widely used polymeric membranes. This review focuses on the construction and manipulation of the confined structure in the polymeric membranes via incorporating one-dimensional (1D), two-dimensional (2D) and three-dimensional (3D) fillers. The comparison of the MMMs for pervaporation is summarized, and the research prospective of the MMMs is provided.

Objective Oral lichen planus (OLP) presents with large numbers of T lymphocytes accumulating beneath the epithelium of the oral mucosa; however, its aetiology remains obscure. A potential role for an emerging novel T cell subset, Th9, in OLP has recently been suggested but remains to be clarified. The current aim was to investigate the expression and potential clinical significance of Th9 cells in distinct subtypes of OLP. Materials and methods Peripheral blood samples were collected from 41 OLP patients and 18 healthy controls (HCs). Flow cytometric analysis was used to detect the CD4+ T helper subset Th9 (IL-9+IL-17−CD4+ Th cells) and Th17 (IL-9−IL-17+CD4+ Th cells) expression levels. Results Flow cytometry results showed significantly elevated levels of Th9 cells in reticular and erosive OLP compared to HCs. Th9 expression in erosive OLP was less than in reticular OLP, indicating that Th9 but not Th17 cells may play a predominant role in reticular disease. However, in erosive OLP patients, we found much higher levels of Th17 cells compared to reticular OLP patients and HCs, indicating that Th17 dominates in erosive OLP. Statistical analysis showed positive correlations of Th9 cells and Th17 cells in patients with reticular or erosive OLP but none in HCs. Conclusions Th9 and Th17 cells may take the predominant roles in reticular and erosive OLP respectively, and their numbers were positively correlated in reticular and erosive OLP patients. Elevated circulating Th9 cells may help maintain immune balance in OLP immunopathogenesis, which requires further investigation.

Covalent organic frameworks (COFs) have gained tremendous interest as membrane building blocks owing to rigid, long-range ordered and easily functionalized skeletons. The facile, controllable and task-specific construction of COF membranes lies in the frontier of membrane technology. Herein, we explored a post-synthetic linker exchange (PLE) method to engineer COF membranes for efficient alcohol dehydration. The proposed PLE method, utilizing the reversible breaking-reformation basis between pristine COF membranes and post-introduced linkers, narrowed the effective pore size to intensify molecular sieving property. Moreover, the PLE method also endowed COF membranes with more hydrophilic groups, thus improving the water sorption ability of COF membranes. The resultant COF membranes exhibited superior n-butanol dehydration performances with 3620 of selectivity, 11.35 kg m−2 h−1 of total flux and remained stable in 15-day operation. This PLE method may flourish the library of engineering COF membranes for efficient molecular separations.

A firm trades off information transfer costs and agency costs to determine the distribution of decision rights to lower-level management. Using the replacement of municipal officials as an exogenous shock of political uncertainty, we find a business group is more likely to delegate decision rights of cash resources to subsidiaries when political uncertainty is high. The association is only evident among non-state-owned-enterprises (non-SOEs) and not SOEs. Additional tests show that the delegation of decision rights is more pronounced among firms with weak internal control and those located in cities where local governments have replaced their party secretary. We also find that firm decentralization can enhance investment efficiency and the marginal value of cash in the presence of high political uncertainty. Overall, our findings support the decentralization theory, and provide causal evidence on how political uncertainty influences allocation of decision rights among listed firms in an emerging economy with large state ownership.

Nanoplastics have been found in marine biological habitats. There is now an urgent need to effectively detect these nanoplastics. Due to the small size of these plastics, it is challenging to directly measure the total abundance while in a suspension. In this study, a backward 120° polarized light scattering device was used to measure the polarization parameters of Phaeodactylum tricornutum, before and after the adsorption of nanoplastics. The polarization parameters were observed to be affected by the adsorption of nanoplastics, with different concentrations and sizes. Moreover, the polarization parameter X changed with time after mixing the nanoplastics with the microalgae, which showed the details of the adsorption of nanoplastics by the microalgae, and was further confirmed by a scanning electron microscope image. The simulation results demonstrated how the polarization parameter X of the scatterers (e.g. microalgae) were affected by the adsorption of the nanoplastics. The results of this work indicate that the polarization scattering method can be used to probe the concentration and size of nanoplastics adsorbed by microalgae in water.

This paper proposes a method based on the improved genetic algorithm for cooperative collision avoidance by multiple unmanned surface vehicles (hereinafter referred to as multiple USVs). In the multiple USVs collaborative task mode in a complex environment featuring obstacles, we establish models of the multiple USVs system and sensor detection; divide scenarios involving multiple USVs encounters and design corresponding collision avoidance strategies; and calculate the motion parameters and risk of collision to determine whether to take measures to avoid collisions. Following this, we choose the genetic algorithm (GA) as core algorithm to plan for collision avoidance, improve it through retention, deletion, and replacement, use the analytic hierarchy process to build a fitness, iteratively optimize the adjustment of velocity and heading, and calculate the current best path for collision avoidance for multiple USVs. Finally, we built a simulation platform for multiple USVs collision avoidance planning based on the QT software, and designed typical cases to verify the proposed method with and without communication conditions. The results show that the proposed method can be used for the safe operation of multiple USVs.