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Highly efficient proton conductors, polyoxometalate-poly(ethylene glycol) (POM-PEG) hybrid nanocomposites, have been synthesized by encapsulating a single PEG chain inside the 1D nanochannel defined by the frameworks of POMs. By employing two types of neutron scattering techniques complemented by thermal analysis, we prove that in a nanochannel a single PEG chain stays as a distorted helix. More importantly, we reveal that the PEG segments perform a localized longitudinal random walk and quantitatively show the strong correlation between the local motion of PEG and the macroscopic proton conduction of the material. On the basis of these spatial-temporal characteristics, a microscopic picture for the proton conduction process of POM-PEG hybrid materials is proposed.

Broadband dielectric spectroscopy (BDS) is used to probe the chain and segmental dynamics of A2B2 and AB2 miktoarm star copolymers based on polystyrene (PS, A block) and polyisoprene (PI, B block) that display lamellar morphologies as determined using small-angle X-ray scattering (SAXS). While no changes in the distribution of PI segmental relaxation times are observed with variation of the molecular architecture, an unexpected increase in the normalized PI chain relaxation intensity is realized for AB2 miktoarm star copolymers as well as a change in the distribution of chain relaxation rates as compared to A2B2 and AB diblock copolymer systems. This result is attributed to asymmetry in the molecular architecture near the junction point, which affects the osmotic constraint of the tethered PI chains within the interfacial region of the lamellae. The results highlight the importance of macromolecular design on fundamental chain dynamics in phase-separated thermoplastic elastomers.

Microstructure and properties of Cu/Ti laser welded joints. The optical microscopy, SEM, EDS, XRD and TEM were applied to assess the microstructure and bonding mechanism of Cu/Ti joints. When the laser beam was used to irradiate the copper side with an offset value of 0.45 mm, the welded metal and fusion line of Cu side were mainly consisted of the Cu solid solution. The intermetallic layer was formed at the titanium-welded metal interface. The thickness of IMCs was about 25 μm and consisted of the Cu solid solution, intermetallic compounds such as TiCu, TiCu2, Ti2Cu and Ti3Cu4. The tensile strength of butt joints could reach 151 MPa, i.e. 61% of the tensile strength of the copper base metal. The quasi-cleavage fracture occurred at the IMCs.

With the rapid increase of renewable energy sources and power electronic converters in the power system, the inertia of the power system is declined and the stability problem is more serious than ever before. In this paper, a virtual synchronous generator (VSG) control strategy is proposed to enable the voltage-source converter-based multiterminal high-voltage direct current (VSC-MTDC) system to damp the low-frequency oscillation modes. Both rotational inertia part and governor part are modeled in the VSG controller. The $V^2-P-\omega$ characteristic is developed based on the $V^2-P$ droop control to emulate the action of the speed governor when the frequency of ac grid deviates from the nominal value. The virtual inertia part is used to emulate the inertia response of the synchronous generator. The communication between VSC stations is unnecessary with the autonomous power allocation ability of the $V^2-P-\omega$ characteristic. Modal analysis is utilized to test the system stability and optimize the controller parameters. Two test systems which include offshore wind farms, VSC-MTDC systems, and onshore power grids are built in the DIgSIENT/PowerFactory. The simulation results verify the effectiveness of the proposed VSG strategy.

Unexpected vibrations induced by the crack fault and other unbalance factors in rotor system seriously affect the health and reliability of the generator. Here, to explore the vibration performances, a bending-torsional coupling model of the generator rotor shaft system is established, in which electromagnetic malfunction (unbalanced magnetic pull) and mechanical failures (fractional-order damping, crack and contact-rubbing) are considered. Then, the simulation is done by a modified Adams-Bashforth-Moulton algorithm. Based on the simulation, the correctness of the new coupling model is verified by comparing with previous model and experimental data. At the same time, the new coupling model is analyzed to obtain the dynamic evolutions of the generator rotor shaft system with the changes of crack depth ratio, the fractional order of damping, rotational speed ratio and mass eccentricity of rotor. In addition to this, some critical values and ranges are proposed. Finally, these results can efficiently provide a theoretical reference for the design of generator rotor system and be applied to forecasting and diagnosing vibration faults in generator rotor shaft system.

This paper proposes an adaptive droop control (ADC) strategy for the voltage source converter (VSC) based multiterminal high voltage direct current (VSC-MTDC) system, which enables the VSC-station to provide frequency regulation for onshore ac grids. A V-I-f characteristic is derived to establish the relationship between the frequency deviation and dc voltage. A VSC-station working with the V-I-f characteristic is able to adjust its dc voltage reference autonomously according to the grid frequency deviation. Thus, the power flow of the VSC-MTDC system will be redistributed and more power is going to be injected into the adjacent grid of which the frequency deviation exceeds the threshold value. The ADC strategy inherits the advantage of the traditional droop control (TDC) that there is no need for communication system. An ac/dc hybrid system that includes VSC-MTDC system, onshore grids, and offshore wind farms is built in DIgSILENT/Powerfactory. Modal analysis and nonlinear simulations are performed to obtain the optimal control parameters and demonstrate the performance of the ADC strategy.

This paper proposes a long-stroke linear switched reluctance machine (LSRM) with a primary and a secondary translator for industrial conveyance applications. The secondary one can translate according to the primary one so that linear compound motions can be achieved. Considering the fact that either one translator imposes a time-variant, nonlinear disturbance onto the other, the self-tuning position controllers are implemented for the compound machine and experimental results demonstrate that the absolute steady-state error values can fall into 0.03 mm and 0.05 mm for the secondary and primary translator, respectively. A composite absolute precision of less than 0.6 mm can be achieved under the proposed control strategy.

The heterogeneous hydrogenation of propene over supported Pd–Au bimetallic nanoparticles was investigated using NMR and the parahydrogen-induced polarization (PHIP) technique. The composition and structure of Pd–Au/TiO2 catalysts were correlated to both catalytic activity and pairwise hydrogen addition. Sol-immobilization, impregnation, and deposition–precipitation methods were used for preparation of the Pd–Au bimetallic catalysts. A strong signal enhancement was observed on the bimetallic catalyst prepared through the sol-immobilization method, up to 24-fold higher than that with the other two methods. The polyvinyl alcohol (PVA) stabilizer bound to the metal surface was responsible for the enhanced PHIP effect. The removal of the PVA ligands by water washing and calcination treatments shows a significant effect on the hydrogen pairwise addition. Increasing the Au content in the bimetallic alloy led to a promotion of the pairwise selectivity due to the ensemble effect. The pairwise selectivity could be ...

A general strategy has been developed here to co-assemble polyoxometalates (POMs) and polymers into core–shell hybrid nanoparticles via hydrogen bonding interaction. Due to the hydrogen bonds between the pyridine groups of poly(4-vinyl pyridine) (P4VP) and the hydrogen bonding donor groups on the POM surface, P4VP is stabilized by the POMs and dispersed as discrete hybrid core–shell nanoparticles in aqueous solution. For these thermodynamically stable nanoparticles, the P4VP cores are covered with hexagonal close-packed POMs. The size of the core–shell particles is controlled by the electrostatic repulsive interaction among the POMs. The introduction of extra salts screens the repulsive force among the POMs, thus increasing the size of the core–shell structures.

All-acrylic multigraft copolymers, poly(butyl acrylate)-g-poly(methyl methacrylate), synthesized using a facile grafting-through methodology, exhibit elongation at break (>1700%) and strain recovery behavior far exceeding those of any commercial acrylic (∼500%) and styrenic (∼1000%) triblock copolymers to date. One-batch anionic polymerization of methyl methacrylate (MMA) using the sec-butyl lithium/N-isopropyl-4-vinylbenzylamine (sec-BuLi/PVBA) initiation system gives PMMA macromonomers with quantitative yield, short reaction time, and using simple synthetic procedures. These new all-acrylic superelastomers and the simple synthetic approach greatly expand the range of potential applications of all-acrylic thermoplastic elastomers (TPEs).

A novel class of ortho, para-alternating linked polyarenes is synthesized via catalyst-transfer Suzuki coupling polymerization with Pd2(dba)3/t-Bu3P/p-BrC6H4COPh as initiator. Through a series of kinetic studies and MALDI-TOF analysis, the polymerization is shown to proceed in a chain-growth manner. The optical and thermal properties for the ortho, para-alternating linked polyarenes exhibit unusual molecular weight dependence. Thus, the polymer with lower molecular weight (Mn = 6300 g mol−1) emits green fluorescence whereas the one with higher molecular weight (Mn = 13 800 g mol−1) emits blue fluorescence under UV (λ = 360 nm) irradiation. Furthermore, an all-conjugated block copolymer containing a polyfluorene block and the ortho, para-alternating linked block is also successfully prepared, in a one-pot procedure. These results can provide a pathway to obtain polyarenes with precisely controlled structures, hence, desirable properties.

The increase of renewable energy generations and HVDC links with low or zero inertia will affect the dynamic behavior of power systems and stability margins. The inertia characteristics of power system is a critical factor for the analysis of the system dynamic stability when subjected to disturbances. To meet the increasing integration level of the renewable energy resources in the future, this paper proposes an inertia estimation algorithm to analyze both the regional and global inertia characteristics of power systems. It is found that the inertia estimation results are highly related to several factors, such as the grid structure, the inertia time constant of synchronous generators and the grid-interface location of the electronics, which also reveal the impact of a multi-terminal DC (MTDC) system connection. The effectiveness of the proposed method is verified and demonstrated for three networks by the simulations in the DigSILENT/PowerFactory environment.

Non-alcoholic fatty liver disease (NAFLD), mainly characterized by the accumulation of excess fat in hepatocytes, is the most prevalent liver disorder afflicting ~25% of adults worldwide. In vivo studies have shown that adult rodents with NAFLD were more sensitive to metallic nanoparticles (MNPs) than healthy MNPs. However, due to the complex interactions between various cell types in a fatty liver, it has become a major challenge to reveal the toxic effects of MNPs to specific types of liver cells such as steatotic hepatocytes. In this study, we reported the susceptibility of steatotic hepatocytes in cytotoxicity and the induction of oxidative stress to direct exposures to MNPs with different components (silver, ZrO2, and TiO2 NPs) and sizes (20–30 nm and 125 nm) in an oleic acid (OA) -induced steatotic HepG2 (sHepG2) cell model. Furthermore, the inhibitory potential of MNPs against the process of fatty acid oxidation (FAO) were obvious in sHepG2 cells, even at extremely low doses of 2 or 4 μg/mL, which was not observed in non-steatotic HepG2 (nHepG2) cells. Further experiments on the differential cell uptake of MNPs in nHepG2 and sHepG2 cells demonstrated that the susceptibility of steatotic hepatocytes to MNP exposures was in association with the higher cellular accumulation of MNPs. Overall, our study demonstrated that it is necessary and urgent to take the intracellular exposure dose into consideration when assessing the potential toxicity of environmentally exposed MNPs.

Key Points Question How can health and development indicators be estimated across micropolicy units when geographic identifiers are not available in nationally representative surveys? Findings In this cross-sectional study of 222 172 children in 3940 assembly constituencies (ACs) in India, a high degree of inequality in child undernutrition was found across ACs, with a substantial variation within states and dissimilar patterns of geographic clustering. Meaning These findings suggest that local electoral units should be considered when designing geographically targeted interventions to reduce the burden of child undernutrition., This cross-sectional study estimates health and development indicators across micropolicy units using a newly developed method., Importance Geographic targeting of public health interventions is needed in resource-constrained developing countries. Objective To develop methods for estimating health and development indicators across micropolicy units, using assembly constituencies (ACs) in India as an example. Design, Setting, and Participants This cross-sectional study included children younger than 5 years who participated in the fourth National Family and Health Survey (NFHS-4), conducted between January 2015 and December 2016. Participants lived in 36 states and union territories and 640 districts in India. Children who had valid weight and height measures were selected for stunting, underweight, and wasting analysis, and children between age 6 and 59 months with valid blood hemoglobin concentration levels were included in the anemia analysis sample. The analysis was performed between February 1 and August 15, 2020. Exposures A total of 3940 ACs were identified from the geographic location of primary sampling units in which the children’s households were surveyed in NFHS-4. Main Outcomes and Measures Stunting, underweight, and wasting were defined according to the World Health Organization Child Growth Standards. Anemia was defined as blood hemoglobin concentration less than 11.0 g/dL. Results The main analytic sample included 222 172 children (mean [SD] age, 30.03 [17.01] months; 114 902 [51.72%] boys) from 3940 ACs in the stunting, underweight, and wasting analysis and 215 593 children (mean [SD] age, 32.63 [15.47] months; 112 259 [52.07%] boys) from 3941 ACs in the anemia analysis. The burden of child undernutrition varied substantially across ACs: from 18.02% to 60.94% for stunting, with a median (IQR) of 35.56% (29.82%-42.42%); from 10.40% to 63.24% for underweight, with a median (IQR) of 32.82% (25.50%-40.96%); from 5.56% to 39.91% for wasting, with a median (IQR) of 19.91% (15.70%-24.27%); and from 18.63% to 83.05% for anemia, with a median (IQR) of 55.74% (48.41%-63.01%). The degree of inequality within states varied across states; those with high stunting, underweight, and wasting prevalence tended to have high levels of inequality. For example, Uttar Pradesh, Jharkhand, and Karnataka had high mean AC-level prevalence of child stunting (Uttar Pradesh, 45.29%; Jharkhand, 43.76%; Karnataka, 39.77%) and also large SDs (Uttar Pradesh, 6.90; Jharkhand, 6.02; Karnataka, 6.72). The Moran I indices ranged from 0.25 to 0.80, indicating varying levels of spatial autocorrelation in child undernutrition across the states in India. No substantial difference in AC-level child undernutrition prevalence was found after adjusting for possible random displacement of geographic location data. Conclusions and Relevance In this cross-sectional study, substantial inequality in child undernutrition was found across ACs in India, suggesting the importance of considering local electoral units in designing targeted interventions. The methods presented in this paper can be further applied to measuring health and development indicators in small electoral units for enhanced geographic precision of public health data in developing countries.

Owing to the intriguing capability of manipulating electromagnetic (EM) properties, the metasurface has aroused great attention of researchers and promoted its applications in EM invisibility. However, there are strong demands to provide an efficient transparent window for signals transmitting in EM invisibility devices. Here, we propose a scheme of a circular dichroism assisted metadevice to provide efficient transmission and broadband absorption in microwave frequencies. By employing chiral meta-atoms to introduce a strong asymmetric response for circularly polarized waves, a chiral metadevice for spin-selective absorption with an efficient transmission is presented. Then, we couple four chiral atoms into a polarization-insensitive atom pair, thus the achiral metadevice presents an identical high-efficiency absorption for both the x- and y-polarized wave. Here, both the chiral and achiral metadevices are realized by loading the metasurface-based absorber on a bandpass frequency selective surface. A proof-of-prototype is fabricated to verify the achiral design. The simulated and experimental results have demonstrated wideband, high-efficiency, polarization-insensitive absorption and high in-band transmission. Interestingly, the proposed paradigm can not only provide the potential for chirality-enhanced absorber design but also may trigger applications in spin-dependent systems, stealth antenna systems, and EM camouflage devices.

Autism spectrum disorder (ASD) is a neurodevelopmental disorder that can be caused by various factors. The present study aimed to determine whether prenatal hypoxia can lead to ASD and the role of hypoxia-inducible factor-1α (HIF-1α) in this process. We constructed a prenatal hypoxia model of pregnant rats by piping nitrogen and oxygen mixed gas, with an oxygen concentration of 10 ± 0.5 %, into the self-made hypoxia chamber. Rats were subjected to different extents of hypoxia treatments at different points during pregnancy. The results showed that hypoxia for 6 h on the 17th gestation day is most likely to lead to autistic behavior in offspring rats, including social deficits, repetitive behaviors, and impaired learning and memory. The mRNA expression level of TNF-α also increased in hypoxia-induced autism group and valproic acid (VPA) group. Western blotting analysis showed increased levels of hypoxia inducible factor 1 alpha (HIF-1α) and decreased levels of phosphatase and tensin homolog (PTEN) in the hypoxic-induced autism group. Meanwhile, N-methyl d -aspartate receptor subtype 2 (NR2A) and glutamate ionotropic receptor AMPA type subunit 2 (GluR2) were upregulated in the hypoxic-induced autism group. HIF-1α might play a role in hypoxia-caused autism-like behavior and its regulatory effect is likely to be achieved by regulating synaptic plasticity .

Well-crystallized Ge-free and Ge-ITQ-13 were successfully obtained by solid state synthesis method. The Ge/Si ratio and the water content that are the two important factors in the synthesis of germanosilicate zeolites were explored for the formation of ITQ-13. The effect of the mineralizing agents (NH4F and NH4Cl) on the ITQ-13 synthesis was investigated as well. The obtained pure silica ITQ-13 and Ge-ITQ-13 were characterized by one- and two-dimensional solid- state NMR techniques. One-dimensional (1D) 19F MAS, 1H→29Si CP/MAS and 19F→29Si CP/MAS NMR spectroscopy evidenced the formation of pure Si-D4R (double four ring) and Ge-D4R units, with the latter being generated by substitution of Si atom from the former units. The detailed configurations of the Ge-D4R units in ITQ-13 was revealed by two-dimensional (2D) 29Si{19F} HETCOR NMR spectroscopy. With the help of theoretical calculations on the 19F and 29Si NMR chemical shifts, six types of D4R units were determined. The formation of the specific D4R unit confirms the structural directing roles of Ge atom and F ions in the formation of the D4R units in zeolite framework. The identification of the SiOSi bonds in the D4R units that connects the layers of ITQ-13 framework provided rationale for the high stability of the ITQ-13 in the degermanation treatment.

The hydrocarbon pool (HP) species in methanol-to-olefins (MTO) reactions over zeolite H-ZSM-5 were investigated by solid-state NMR spectroscopy and GC–MS. The distribution and reactivity of retained HP species such as carbocations and methylbenzenes (MBs) were found to evolve with reaction time and their positions in the catalyst bed. The underlying mechanism of the typical S-shaped methanol conversion curve was revealed, in which the dominating reaction route was found to be dependent on the formation and reactivity of different HP species that were varied at different reaction time. During the induction period, cyclopentenyl cations served as the precursor to MBs and exhibited higher reactivity than the latter. The reaction was accelerated by the accumulation of alkenes and further enhanced by consequent involvement of the cyclopentenyl cations and aromatics, which eventually led to a steady state reaction. The interconversions of the reaction cycles based on alkenes, cyclopentenyl cations, and MBs were proposed for the formation of light olefins. The co-catalysis of HP species in the MTO reactions showed that the cyclopentenyl cations and alkenes favored propene formation, while the light MBs such as xylene and triMB facilitated ethene formation. Within the catalyst bed, both cyclopentenyl cations and MBs were dominantly formed in the upper catalyst layers. The experiments indicated that both cyclopentenyl cations and alkenes maintained high reactivity throughout the catalytic bed, while MBs exhibited high reactivity only in the upper catalyst position.

© 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved. Bicontinuous jammed emulsions (or bijels) are tortuous, interconnected structures of two immiscible liquids, kinetically trapped by colloidal particles that are irreversibly bound to the oil-water interface. A wealth of applications has been proposed for bijels in catalysis, energy storage and molecular encapsulation, but large domain sizes (on the order of 5 μm or larger) and difficulty in fabrication pose major barriers to their use. Here, we show that bijels with sub-micrometre domains can be formed via homogenization, rather than spinodal decomposition. We achieve this by using nanoparticle surfactants: polymers and nanoparticles of complementary functionality (for example, ion-pairing) that bind to one another at the oil-water interface. This allows the stabilization of the bijel far from the demixing point of the liquids, with interfacial tensions on the order of 20 mN m-1. Furthermore, our strategy is extremely versatile, as solvent, nanoparticle and ligand can all be varied.

To optimize the production of active inclusion bodies (IBs) containing human d-amino acid oxidase (hDAAO) in Escherichia coli. The optimized initial codon region combined with the coexpressed rare tRNAs, fusion of each of the N-terminal partners including cellulose-binding module, thioredoxin, glutathione S-transferase and expressivity tag, deletion of the incorporated linker, and improvement of tRNA abundance affected the production and activity for oxidizing d-alanine of the hDAAO in IBs. Compared with the optimized fusion constructs and expression host, IBs yields and activity were increased to 2.6- and 2.8-fold respectively by changing the N-terminal codon bias of the hDAAO. The insoluble hDAAO codon variant displayed the same substrate specificity as the soluble one for oxidizing d-alanine, d-serine and d-aspartic acid. The freshly prepared hDAAO codon variant was used for analyzing the l-serine racemization activity of the bacterially expressed maize serine racemase. Optimization of the N-terminal codon bias combined with the coexpression of rare tRNAs is a novel and efficient approach to produce active IBs of the hDAAO.

Poly(1-adamantyl acrylate) (PAdA) exhibits much higher glass transition and degradation temperatures than other polyacrylates. However, the quantitative evaluation of the stiffness of this polymer chain has not been reported previously. In this study, the dilute solution properties and conformational characteristics of PAdA were evaluated using viscometry and scattering techniques. The unperturbed dimensions of this polymer were evaluated using the Burchard–Stockmayer–Fixman extrapolation and the touched-bead wormlike chain model. The PAdA chain has a comparable persistence length, diameter per bead and characteristic ratio to poly(methyl methacrylate) and polystyrene. All these results indicate that PAdA is less flexible than common polyacrylates. In addition, the second virial coefficients (A2) of PAdA in different solvents obtained by static light scattering were compared. Among the solvents investigated, tetrahydrofuran is a moderate solvent. Radius of gyration of a polymer sample in the various solvents ranged from 16.8 to 30.3 nm. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017

Single-ion conducting polymer electrolytes (SCPE) are attractive candidates for high-performance energy storage devices. A star-shaped single lithium-ion conducting polymer electrolyte was synthesized by combining the “grafting to” and “grafting from” strategy utilizing a polyhedral oligomeric silsesquioxane (POSS) nanoparticle as the core. Carboxylic acid terminated polyethylene oxide (PEO) and Reversible Addition Fragmentation Chain Transfer Agent (RAFT-CTA) were attached to the POSS nanoparticle to form a POSS-cored macro RAFT CTA (PMR-CTA). The PMR-CTA was used to mediate the polymerization of potassium (styrene-4-sulfonyltrifluoromethyl-sulfonyl)imide (STF-K+) and subsequent counter ion exchange resulted in a star-shaped single lithium-ion conducting copolymer (SSCP-Li+). The grafting ratio of poly(STF-Li+) and PEO per POSS nanoparticle can be tuned by modifying the feed ratio of the two polymer components. The synthesized star-shaped SCPE-Li+ are characterized by 1H NMR, FT-IR, UV-Vis, DLS, GPC and DSC, and their ionic conductivity is studied by broadband dielectric spectroscopy. The obtained results are compared to a conventional linear homopolymer poly(STF-Li+) and block copolymer PEO-b-poly(STF-Li+), and reveal a significant “decoupling” of ion conductivity from segmental dynamics for all of the studied SCPE-Li+. Blending extra PEOs with SCPE-Li+ was also performed to improve the ionic conductivity.

In this study, four fusion proteins were designed, in which the N-terminal cellulose-binding module as the affinity tag was immobilized on the regenerated amorphous cellulose (RAC), and the release of the C-terminal colored proteins was detected easily and rapidly after on-resin cleavage using the free tobacco etch virus protease (TEVp) variant, or the immobilized cognate protease with a binding capacity of up to 220 mg protein per gram of RAC. The enhanced stability and repetitive use of the immobilized TEVp compensated slight loss of the catalytic efficiency toward the soluble protein substrate. On-resin cleavage and purity of the released target proteins are related to the context of the fusion tag, the incorporated linker composition, and the colored protein. Owing to low cost and high binding capacity of the RAC, the TEVp immobilized on the resin is an ideal alternative for removing fusion tag. The colored proteins are easily monitored in the on-resin process of fusion proteins, and rapid separation from RAC.

Based on an example of a project in Tangshan, the high-rise buildings are built in karst area and mined out affected area which is treated by high pressure grouting, and foundation is adopted the form of pile raft foundation. By long-term measured settlement of high-rise buildings, It is found that foundation settlement is linear increase with the increase of load before the building is roof-sealed, and the settlement increases slowly after the building is roof-sealed, and the curve tends to converge, and the foundation consolidation is completed. The settlement of the foundation is about 80% - 84% of the total settlement before the building is roof-sealed.Three layer BP neural network model is used to predict the settlement in the karst area and mined affected area.Compared with the measured data, the relative difference of the prediction is 0.91% - 2.08% in the karst area, and is 0.95% - 2.11% in mined affected area. The prediction results of high precision can meet the engineering requirements.

We demonstrated the facet dependence of pairwise addition of hydrogen in heterogeneous catalysis over Pd nanocrystal catalysts via NMR using para-hydrogen-induced polarization.

All acrylic-based thermoplastic elastomers (TPEs) offer potential alternatives to the widely-used styrenic TPEs. However, the high entanglement molecular weight (Me) of polyacrylates, as compared to polydienes, leads to “disappointing” mechanical performance as compared to styrenic TPEs. In this study, triblock copolymers composed of alkyl acrylates with different pendant groups and different glass transition temperatures (Tgs), i.e. 1-adamatyl acrylate (AdA) and tetrahydrofurfuryl acrylate (THFA), were synthesized via reversible addition–fragmentation chain transfer (RAFT) polymerization. Thermal characterization of the resulting polymers was performed using differential scanning calorimetry (DSC), and the Tgs of both segments were observed for the block copolymers. This indication of microphase separation behavior was further demonstrated using atomic-force microscopy (AFM) and small angle X-ray scattering (SAXS). Dynamic mechanical analysis (DMA) showed that the softening temperature of the PAdA domains is 123 °C, which is higher than that of both styrenic TPEs and commercial acrylic based TPEs with poly(methyl methacrylate) (PMMA) hard block. The resulting triblock copolymers also exhibited stress–strain behavior superior to that of conventional all acrylic-based TPEs composed of PMMA and poly(n-butyl acrylate) (PBA) made by controlled radical processes, while the tensile strength was lower than for products made by living anionic polymerization.

The carbonylation reaction of ethane with CO to produce carboxylic acid was studied over zinc-modified ZSM-5 zeolite (denoted as Zn/ZSM-5) using in situ solid-state NMR spectroscopy. 13C-isotope-labeled reactants were alternatively used to monitor the co-reaction at temperatures of 298–623 K. The NMR experimental results demonstrated that surface zinc-ethyl and methoxy species were formed and identified as key intermediates in the reaction. The reactivity of these intermediates was further explored under both oxidizing and reducing conditions by adding O2 and H2 into the reaction system. It was found that ethane was initially activated into zinc–ethyl species that show reactivity similar to that of organometallic compounds such as diethyl zinc. The interaction of zinc–ethyl species with CO2 resulting from the oxidation of CO produces propanoic acid. Side products such as aromatics were formed by dehydrogenation of zinc–ethyl species via the formed ethene intermediates. We also found that hydrogenolysis of ethane occurred and gave rise to byproduct methane, which led to the formation of acetic acid by carboxylation with CO2. Additionally, CO was converted into surface methoxy species, which could react with CO to produce acetic acid via a Koch-type carbonylation reaction.

As an important research field in data mining and machine learning, text classification has been widely used in news classification, sentiment analysis, opinion mining, and so on. It has become an important basic subtask in the field of natural language processing. In this paper, we propose a text multi-classification algorithm based on word embedding and multi-grained cascade forest, which use word embedding model to represent text, sliding windows to scan the word vectors and cascade forest to classify texts. Experiments show that this text multi-classification algorithm can greatly improve the classification accuracy compared with other traditional machine learning models. Compared with the deep neural network classification models, it can greatly improve efficiency with achieving highly competitive performance.

Fast deformation of entangled melts is known to cause chain stretching due to affinelike straining of the entanglement network. Since the chain deformation may also result in perturbations of covalent bond angles and bond length, there are always possible enthalpic effects. In this study, we first subject polystyrene and PMMA of different molecular weights to either uniaxial melt extension or planar extension and subsequently impose rapid thermal quenching to preserve the chain deformation. Then, such pre-melt-deformed samples are annealed at various temperatures below the glass transition temperature Tg. During annealing, these samples can undergo appreciable contraction on a time scale much shorter than the alpha relaxation time. Significant retractive stress is observed when such contracting samples are held fixed during the annealing. The stress level can be nearly as high as the Cauchy stress produced during melt stretching. These observations not only allowed us to investigate glassy chain dynamics as well as the molecular nature of mechanical stress but may also suggest that pre-melt-stretched polymers can cause segmental mobilization in the glassy state. The available evidence indicates that the retractive stress is enthalpic in origin, associated with the conformational distortion at the bond level produced by melt stretching.

The advanced glycation end products (AGEs) are the compounds produced by non-enzymatic glycation reaction of proteins and sugars, which can induce the generation of free radicals and the expression of inflammatory factors, thereby playing an important role in vascular dysfunction in diabetes. To investigate the effects of caffeic acid (CA) on glycation formed by glucose and protein, various spectroscopic techniques and molecular docking methods were carried out. Furthermore, the protective effects of CA on human umbilical vein endothelial cells (HUVECs) damaged by AGEs were detected. The results indicated that CA inhibited AGEs formation in vitro, decreased the expression of IL-1β, IL-18, ICAM-1, VCAM-1, NLRP3, Caspase-1 and CRP (C-reactive protein) and reduced the ROS in HUVECs exposed to AGEs. Our findings suggested that the supplementation with dietary CA could prevent and delay the AGEs-induced vascular dysfunction in diabetes.

This study was focused on the effect of duodenal-jejunal bypass (DJB) on brain inflammation, activation brain insulin signaling and POMC positive neurons in type 2 diabetic (T2DM) rats. T2DM rats were induced by high-fat diet (HFD) and low dose streptozotocin (STZ) injection. Twelve T2DM rats were randomly divided into 2 groups, DJB group (T2DM-DJB, n=6) and T2DM group (T2DM-Sham, n=6). Six health Wistar rats were used as normal control rats (Wistar-Control, n=6). The results showed DJB group was significantly reduced the HOMA-IR and increased HOMA-ISI of T2DM rats 6 weeks after surgery. The Q-RT-PCR and Western-blot results showed DJB intervene significantly decreased the expression of inflammatory factors IL-6, TNF-α, IL-1β and NF-κB in the brain. Our data also showed that DJB activated the brain insulin by increasing the expression of insulin, IRS1 and IRS2 in the brain of T2DM rats. Immunohistochemical assay showed that DJB increased the number of POMC positive neurons in brain, and increased the expression of BDNF in neurons. Those results indicated that DJB might fulfill the antidiabetic effect by increasing POMC positive neurons and decreasing the brain inflammation in T2DM rats. Disclosure H. Wang: None. B. Jiang: None. J. Li: None. W. Wang: None. N. Li: None. Q. Yan: None. Z. Gao: None. M. Qu: None. Funding National Natural Science Foundation of China (81871892, 31671208, 81500798, 81471048); Shandong Province Natural Science Foundation (ZR2015HL128); Technology Development Plan of Weifang (2018YX027)

Duodenal-Jejunal bypass (DJB) can dramatically improve type 2 diabetes independent of weight loss and food restriction, while the mechanism underlying remains unclear. The most important characteristic of diabetes is hyperglycemia due to impaired glucose homeostatic regulation, increasing evidences have demonstrated that the brain can directly initiate behavioral and metabolic responses to control energy and peripheral glucose homeostasis. This study mainly focused on exploring the role of brain insulin signaling activation and brain glucose utilization in the antidiabetic mechanism of DJB. The diabetic rats that induced by Streptozotocin (STZ) injection were grouped and proceeded with DJB or Sham operation, respectively. Basal glycemic parameters, such as fasting glucose, fasting plasmid insulin, OGTT, HOMA-IR and Hb1Ac, were detected by ELISA kits. In different treated (DJB, Sham or Control) rats models, 18F-FDG PET scanning was used to detect the glucose uptake in different organs, and of the level of insulin as well as insulin signaling pathway related proteins (InsR, IRS1/2, PI3K, AKT) and glucose utilization related proteins (HK1, PFK2) was evaluated by Q-RT-PCR, Western blot or IHC in the brain. Results showed that DJB surgery significantly improved basal glycemic parameters (Blood glucose, Insulin, HOMA-IR, HbA1c and OGTT) and reversed the decreased glucose uptake in the brain which was caused by type 2 diabetes. DJB surgery not only induced the gene expression of the brain insulin as well activated the insulin related signals, but also increased the expression of glucose utilization enzymes, such as HK1 and PFK2 in the brain. These results indicated that activation of brain insulin signaling and elevation of brain glucose metabolism might play an important role in the antidiabetic effect of DJB. Disclosure Q. Yan: None. N. Li: None. R. Pan: None. H. Wang: None. B. Jiang: None. W. Wang: None. Z. Gao: None. M. Qu: None. Funding National Natural Science Foundation of China (81871892, 31671208, 81500798, 81471048); Shandong Province Natural Science Foundation (ZR2015HL128); Technology Development Plan of Weifang (2018YX027)

The foundation pit is a three-dimensional space system with length, width and height. The current code is designed according to the plane problem. It does not consider the space effect of foundation pit. Based on the numerical model, the effects of the ratio of depth to length and the ratio of the distance of pit angle to the length of pit on the spatial effect was studied. It provides the basis for optimal design of deep foundation pit. The results are as follows, when the ratio of depth to length of foundation pit is less than 1/8, the deformation in the middle of foundation pit is close to that in plane strain design. The influence coefficient of foundation pit space changes exponentially with the ratio of the distance of pit angle to the length of pit edge. The influence coefficient of foundation pit space changes exponentially with the ratio of foundation excavation depth to pit length.

Straw retention is an effective method to conserve soil water content and improve soil carbon stocks. However, how soil carbon dynamics respond to different straw retention practices remains unclear. In this study, we investigated soil respiration and soil carbon sequestration at depths of 0-100 cm. We conducted a two-year field experiment with three crop rotation treatments and three straw retention treatments in northwest China. The straw retention treatments included no straw retention (NS), retention of half the straw (HS), and retention of the total amount of straw (TS). The crop rotations treatments included winter wheat plus summer soybean (WS), winter wheat plus summer maize (WM), and winter wheat plus summer fallow (WF). Mean soil respiration rates under WS, WM, and WF treatments were 5.14, 6.53, and 5.49 μmol·m-2·s-1; and 5.67, 5.47, and 6.03 μmol·m-2·s-1 under TS, HS, and NS treatments. The mean soil water content were 15.50%, 15.57%, and 15.74% under WS, WM, and WF rotations, and 15.81%, 15.41%, and 15.50% under TS, HS, and NS treatments. The soil organic carbon (SOC) concentration was higher with increased straw retention, and lower at deeper soil depths. Mean SOC concentrations under different rotations and straw treatments of TS, HS, and NS, respectively were as follows: WS: 6.91, 6.63, 6.39 g/kg; WM: 6.90, 6.72, 6.57 g/kg; and WF: 6.49, 6.52, 6.37 g/kg. Soil temperature was the main determinant of soil respiration rates. We conclude that WS rotation resulted in lower soil respiration, WM rotation resulted in a higher soil carbon sequestration potential, and WF rotation resulted in higher soil water content. However, continued, long-term monitoring is needed to confirm the effect of rotations and straw retention on soil respiration and carbon sequestration in dryland cropping systems in northern China.

An amplifier-less transmission of a single-wavelength 112Gb/s PAM4 signal over 40km using O-band 25G class DML and advanced DSP with a record receiver sensitivity of − 12dBm@HD-FEC is experimentally demonstrated. It also beats the KP4 FEC limit for the first time.

The development of renewable energy sources (RES) is important to promote the energy transition and address climate change. Unlike the centralized RES power plants in the north of China, the distributed RES power plants in the south of China for achieving local consumption have become an effective alternative. However, the differences between RES and hydropower consumption have become obvious in some areas. This paper investigates the key factors affecting the abandonment of RES in the south of China. To alleviate the problem of RES consumption, various measures are discussed from the aspects of evaluating the consumption capacity of power grids at different voltage levels, optimizing demand-side management, flexibly for reforming the peak-shaving power sources of thermal power plants and strengthening inter-provincial transactions. The production simulation is used to validate the analysis and discussion.

In this paper, a new technique is proposed for designing stealthy radome, especially for normal incoming wave stealth. The proposed structure is composed of a band-pass FSS and one layer of polarization conversion arrays which are separated by a foam layer. An FSS-backed polarization conversion meta-surface (PCM) can be obtained. The FSS-backed PCM is capable of providing a second-order transmission window and a wide stealthy band. In the transmission window (4.2∼4.6 GHz), the self-excited communicate electromagnetic wave can pass through freely with its same polarization state. In its stealthy band (7.0∼17.6 GHz), the external incoming wave can be efficiently reflected with its cross-polarized state. Thus, the radome is invisible for a linearly-polarized radar system even the detecting wave is reflected along its incoming direction. The proposed PCM is simulated and experimented. The measured results are in good agreement with the simulated ones. This stealth technique will be significance in the area of naval vessel radomes.

Polybenzofulvene (PBF) is a polydiene with a very high glass transition temperature (Tg), which makes it a potential candidate for use as the hard block for high-temperature thermoplastic elastomer applications. The Tgs of polydienes are known to be related to chain flexibility. However, no studies have been reported that correlate the chain flexibility to the microstructure of PBF. Herein, we present a study of solution properties of linear PBFs with narrow molacular weight dispersity and having 1,2-addition ranging from 23% to 99%. The materials were prepared by living anionic polymerization under different conditions. Specifically, the chain flexibility as defined by the Flory's characteristic ratio, C ∞ , and dependence of chain flexibility on microstructure by combined measurements of intrinsic viscosity and molecular weight using triple-detector size exclusion chromatography (SEC) is studied. The persistence lengths (lp) and chain diameters (dB) were also estimated using the touched-bead wormlike chain model. To the best of our knowledge, the characteristic ratio of PBF is found to be the highest of all polydienes that have been reported so far.

In this study, five fusion tags affecting soluble production and cleavage activity of the tobacco etch virus (TEV) protease (TEVp) variant in Escherichia coli strains BL21 (DE3) and Rosetta™ (DE3) are investigated. Combination of the augmenting rare transfer RNAs (tRNAs) and the fused expressivity tag (N-terminal seven amino acid residues of E. coli translation initiation factor II) promotes the soluble TEVp partner expressed at relatively high level. Attachment of the maltose-binding protein (MBP) tag increases soluble expression of the protease released from the fusion protein in E. coli cells, but the incorporated TEVp recognition sequence slightly decreases expressivity of the fusion construct. Except for the green fluorescent protein, the attached expressivity tag shows less efficiency than the MBP tag in enhancing expression levels of the selected five target proteins in the Rosetta™ (DE3) cells under different induction conditions. Our results identified that high-level production of the functional target protein as the fusion partner in E. coli is combined with the intrinsic property of fusion tag, fusion protein stability, inherent folding of target protein, rare tRNA abundance, and the incorporated linker. Purified TEVp fusion constructs with the N-terminal expressivity tag, as well as the MBP partner, are the ideal alternatives for removing fusion tag.

In this study, we asked participants to “describe their sexual orientation” in an open-ended measure of self-generated sexual orientation. The question was included as part of the New Zealand Attitudes and Values Study (N = 18,261) 2013/2014 wave, a national probability survey conducted shortly after the first legal same-sex marriages in New Zealand. We present a two-level classification scheme to address questions about the prevalence of, and demographic differences between, sexual orientations. At the most detailed level of the coding scheme, 49 unique categories were generated by participant responses. Of those who responded with the following, significantly more were women: bisexual (2.1 % of women, compared to 1.5 % of men), bicurious (0.7 % of women, 0.4 % of men), and asexual (0.4 % of women and less than 0.1 % of men). However, significantly fewer women than men reported being lesbian or gay (1.8 % of women, compared to 3.5 % of men). Those openly identifying as bicurious, bisexual, or lesbian/gay were significantly younger than those with a heterosexual orientation. This study shows diversity in the terms used in self-generated sexual orientations, and provides up-to-date gender, age, and prevalence estimates for the New Zealand population. Finally, results reveal that a substantial minority of participants may not have understood the question about sexual orientation.

Anionic polymerization is one of the most powerful techniques for preparation of well-defined polymers. However, this well-known and widely employed polymerization technique encounters major limitations for the polymerization of functional monomers containing heteroatoms. This work presents the anionic polymerization of 2-phenyl-5-(6-vinylpyridin-3-yl)-1,3,4-oxadiazole (VPyOzP), a heteroatom monomer that contains both oxadiazole and pyridine substituents within the same pendant group, using various initiating systems based on diphenylmethyl potassium (DPM-K) and triphenylmethyl potassium (TPM-K). Remarkably, well-defined poly(2-phenyl-5-(6-vinylpyridin-3-yl)-1,3,4-oxadiazole) (PVPyOzP) polymers having predicted molecular weights (MW) ranging from 2200 to 21 100 g/mol and polydispersity indices (PDI) ranging from 1.11 to 1.15 were prepared with TPM-K, without any additional additives, at −78 °C. The effect of temperature on the polymerization of PVPyOzP was also studied at −78, −45, 0, and 25 °C, and it wa...

The unique properties of ionic liquids (ILs) have made them promising candidates for electrochemical applications. Polymerization of the corresponding ILs results in a new class of materials called polymerized ionic liquids (PolyILs). Though PolyILs offer the possibility to combine the high conductivity of ILs and the high mechanical strength of polymers, their conductivities are typically much lower than that of the corresponding small molecule ILs. In the present work, seven PolyILs were synthesized having degrees of polymerization ranging from 1 to 333, corresponding to molecular weights (MW) from 482 to 160 400 g/mol. Depolarized dynamic light scattering, broadband dielectric spectroscopy, rheology, and differential scanning calorimetry were employed to systematically study the influence of MW on the mechanism of ionic transport and segmental dynamics in these materials. The modified Walden plot analysis reveals that the ion conductivity transforms from being closely coupled with structural relaxation...

// Qi Li 1, 2, * , Weifeng Song 1, * , Weiyu Wang 3, * , Shanshan Yao 2 , Chuan Tian 2 , Xun Cai 1 , Liwei Wang 1 1 Department of Oncology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200080, China 2 Department of Oncology, Shanghai East Hospital, Tongji University, Shanghai 200120, China 3 Department of Interventional Radiology, Affiliated Anhui Provincial Hospital, Anhui Medical University, Hefei 230001, China * These authors have contributed equally to this work Correspondence to: Qi Li, email: liqi_2016@126.com , liqisjt@126.com Keywords: Kruppel-like factor 4, epithelial-mesenchymal transition, hepatocellular carcinoma, microRNA Received: February 25, 2016 Accepted: March 29, 2016 Published: April 18, 2016 ABSTRACT Hepatocellular carcinoma (HCC) is one of the most malignant and lethal human cancers. Epithelial-mesenchymal transition (EMT) enhances the carcinogenesis of HCC, and therapies targeting EMT appear to be promising treatments. We have previously shown that Kruppel-like factor 4 (KLF4) suppressed EMT of HCC cells through downregulating EMT-associated proteins. Here, we examined the roles of microRNAs (miRNAs) in KLF4-regulated EMT in HCC cells. KLF4 induced expression of 3 miRNAs (miR-153, miR-506 and miR-200b) that targeted 3′-UTR of Snail1, Slug and ZEB1 mRNAs, respectively, to inhibit protein translation in HCC cells, which was confirmed by promoter luciferase assay. Expression of either miRNA significantly inhibited HCC cell growth and invasiveness, while the effect of combined expression of all 3 miRNAs was more pronounced. Furthermore, overexpression of antisense of all 3 miRNAs abolished the inhibitory effect of KLF4 on HCC cell growth and invasiveness. Together, our data suggest that KLF4 inhibits EMT-enhanced HCC growth and invasion, possibly through reducing EMT-related proteins Snail1, Slug and ZEB1 via increasing miR-153, miR-506 and miR-200b.

Hydrocarbon-pool chemistry is important in methanol to olefins (MTO) conversion on acidic zeolite catalysts. The hydrocarbon-pool (HP) species, such as methylbenzenes and cyclic carbocations, confined in zeolite channels during the reaction are essential in determining the reaction pathway. Herein, we experimentally demonstrate the formation of supramolecular reaction centers composed of organic hydrocarbon species and the inorganic zeolite framework in H-ZSM-5 zeolite by advanced (13)C-(27)Al double-resonance solid-state NMR spectroscopy. Methylbenzenes and cyclic carbocations located near Brønsted acid/base sites form the supramolecular reaction centers in the zeolite channel. The internuclear spatial interaction/proximity between the (13)C nuclei (associated with HP species) and the (27) Al nuclei (associated with Brønsted acid/base sites) determines the reactivity of the HP species. The closer the HP species are to the zeolite framework Al, the higher their reactivity in the MTO reaction.

Bottlebrush polymers are densely grafted polymers with long side-chains attached to a linear polymeric backbone. Their unusual structures endow them with a number of unique and potentially useful properties in solution, in thin films, and in bulk. Despite the many studies of bottlebrushes that have been reported, the structure–property relationships for this class of materials are still poorly understood. In this contribution, we report the synthesis and characterization of fluorinated bottlebrush polymers based on poly(2,2,2-trifluoroethyl methacrylate). The synthesis was achieved by atom transfer radical polymerization (ATRP) using an α-bromoisobutyryl bromide functionalized norbornene initiator, followed by ring-opening metathesis polymerization (ROMP) using a third generation Grubbs’ catalyst (G3). Rheological characterization revealed that the bottlebrush polymer backbones remained unentangled as indicated by the lack of a rubbery plateau in the modulus. By tuning the size of the backbone of the bottlebrush polymers, near-spherical and elongated particles representing single brush molecular morphologies were observed in a good solvent as evidenced by TEM imaging, suggesting a semi-flexible nature of their backbones in dilute solutions. Thin films of bottlebrush polymers exhibited noticeably higher static water contact angles as compared to that of the macromonomer reaching the hydrophobic regime, where little differences were observed between each bottlebrush polymer. Further investigation by AFM revealed that the surface of the macromonomer film was relatively smooth; in contrast, the surface of bottlebrush polymers displayed certain degrees of nano-scale roughness (Rq = 0.8–2.4 nm). The enhanced hydrophobicity of these bottlebrushes likely results from the preferential enrichment of the fluorine containing end groups at the periphery of the molecules and the film surface due to the side chain crowding effect. Our results provide key information towards the design of architecturally tailored fluorinated polymers with desirable properties.

Nitrogen fertilization significantly increases greenhouse gases (GHGs) emission, when applied from inorganic or organic sources. Minimizing GHGs from agroecosystems without compromising crop yield for stabilization of green production systems remains a challenge. Being an integral component of wheat production technology, the nitrogen (N) application deems to be indispensable. Thus, to reduce the application of N fertilizer and keep in view the minimization of GHGs emission, without compromising soil fertility and wheat production, field experiments were performed with treatments included maize straw mulch (S1: 0, S2: 4500, S3: 9000 kg ha−1) and nitrogen fertilizer (N1: 0, N2: 192 and N3: 240 kg ha−1) during 2015–17. Results showed that the cumulative CO2 and N2O emission from 9000 kg ha−1 of maize straw mulch with 192 kg N ha−1 (S3N2) significantly decreased by 0.67% and 33.7%, respectively, averaged over two years compared with that of 9000 kg ha−1 of maize straw mulch with 240 kg N ha−1 (S3N3). Likewise, the average soil moisture content significantly increased by 10% and 10.6% for S3N2 and S3N3 treatments at 0–10 cm soil depth, respectively, compared to S1N1. Similarly, the S3N2 and S3N3 treatments had lowered the soil temperature by 0.2 and 0.1 °C, respectively, over S1N1 in wheat grown fields. The grain yield of wheat was increased by 45% and 45% under S3N3 and S3N2 treatments than S1N1, respectively. The S3N2 treatment was more economical than S3N3 for wheat crop. Therefore, maize straw mulch (S3) combined with 20% less N fertilizer (N2) from commercial source were considered as a viable production technology to improve crop yield, and reduce soil CO2 and N2O emissions.

Escherichia coli (E. coli) is a common conditional pathogen that is associated with a variety of infections in humans and animals. Although there are increasing reports regarding the infection of E. coli to domestic animals and poultry, the infection of E. coli in lambs is relatively less reported, especially on meningoencephalitis. Here, we reported the isolation of an E. coli strain designated as NMGCF-19 from lambs characterized with severe diarrhea and neurological disorder, and demonstrated that NMGCF-19 as the causative agent has the ability to disrupt the blood-brain barrier (BBB) to cause the meningoencephalitis using a mouse model. Investigation on the mechanism regarding the NMGCF-19-related meningoencephalitis revealed a significant decreased expression of ZO-1 and occludin in mouse brain tissue in comparison with the control mice. Moreover, infection of NMGCF-19 increased the expression of proinflammatory cytokines TNF-α, IL-6, IL-1β and IL-18, up-regulated HMGB1 level, and activated TLR2/TLR4/MyD88 and NLRP3 inflammasome pathways. These findings indicated that NMGCF-19 likely invades the brain tissue by disrupting the tight junction (TJ) architecture and causes the meningoencephalitis via increasing inflammatory response and activating TLR2/TLR4/MyD88 and NLRP3 inflammasome pathways.

It has long been established that the coherent scattering intensity of neutrons by isotropic mixtures of hydrogenous and deuterated polymers of matching molecular weights is, to the first approximation, proportional to the single-chain structure factor of the polymer chain. The validity of this fundamental relation for equilibrium, undeformed polymer melts is well supported by the extensive experimental and theoretical investigations over the past several decades. The generalization of this relation to the case of nonequilibrium, deformed polymer melts, however, is not a trivial one. Despite its widespread usage in small-angle neutron scattering (SANS) studies of deformed polymer melts, the assumed proportionality between coherent scattering intensity and single-chain structure factor has received very little experimental scrutiny. This work quantitatively examines this issue through spherical harmonic expansion analysis of the anisotropic SANS spectra of deformed polystyrene melts of different levels of deuterium labeling. It is shown that the classical assumption works extremely well over a wide range of scattering wavevectors, where the isotropic component of the SANS spectrum and the leading term of structural anisotropy vary by more than two orders of magnitude.

Owing to the stochastic states of power systems with large-scale renewable generation, the impact of high-voltage direct current (HVDC) systems on the stability of the power system should be examined in a probabilistic manner. A probabilistic small signal stability assessment methodology to select the best locations for multi-infeed high-voltage direct current systems in alternating current (AC) grids is proposed in this paper. The Latin hypercube sampling-based Monte Carlo simulation approach is taken to generate the stochastic operation scenarios of power systems with the consideration of several stochastic factors, i.e., load demand and power generation. The damping ratio of the critical oscillation modes and the controllability of power injection to oscillation modes are analyzed by the probabilistic small signal stability. A probabilistic index is proposed to select the best locations of high-voltage direct current systems for improving the damping of the oscillation modes. The proposed methodology is applied to an IEEE 39 bus system considering the stochastic load demand and power generation. The results of probabilistic small signal stability assessment and a time-domain simulation show that the installation of a high-voltage direct current system on the selected locations can effectively improve the system damping.