Mixed Chain Research Articles

Effect of chemical copolymerization and mixed chain extenders on mechanical properties of HTPB polyurethane

In this study, three kinds of polyurethane materials based on HTPB were prepared by copolymerization of hydroxyl-terminated polybutadiene (HTPB) and hydroxyl-terminated polyethylene glycol-tetrahydrofuran copolyether (HTPE) and adding mixed chain extender, polyether polyols HEP-330N and 2-hydroxyethyl disulfide (HEDS). The effects of copolymerization and mixed chain extender on the mechanical properties of polyurethane were studied by static tensile test, dynamic mechanical property analysis (DMA) and differential scanning calorimetry (DSC). Among them, compared with pure HTPB, the tensile strength and elongation at break of polyurethanes obtained by copolymerization, the polyurethanes obtained by adding mixed chain extender, and the polyurethanes obtained by both of these two methods were significantly improved, and the storage modulus and loss modulus were also improved. In addition, the glass transition temperature of polyurethane remained basically unchanged, which was in the range of -79°C to -75°C. It was much lower than the room temperature, which would make it more widely used. This effective method will provide an opportunity for the synthesis of various high-performance composites.

Synthesis, structures and magnetic properties of two new hydrazine bridged 1D cobalt(II) coordination polymers

Two new hydrazine bridged 1D CoII coordination polymers formulated as [Co(N2H4)2F]Cl (1) and Co(N2H4)(H2O)2F2 (2) have been synthesized and magnetically characterized. Compound 1 consists of one-dimensional hydrazine-fluoride mixed bridged CoII chain, while compound 2 exhibits hydrazine bridged CoII chain with fluoride as terminal ligand. Magnetic susceptibility measurements reveal that compound 1 exhibits 1D antiferromagnetic characterization with a long-range ordering at 10.2 K, while compound 2 does not show long-range ordering above 2 K with antiferromagnetic intrachain interactions.

Infinite Series of Ferrimagnetic Phases Emergent from the Gapless Spin Liquid Phase of Mixed Diamond Chains

The ground-state phases of mixed diamond chains with ($S, \tau^{(1)}, \tau^{(2)})=(1/2,1/2,1)$, where $S$ is the magnitude of vertex spins, and $\tau^{(1)}$ and $\tau^{(2)}$ are those of apical spins, are investigated. The apical spins $\tau^{(1)}$ and $\tau^{(2)}$ are connected with each other by an exchange coupling $\lambda$. Other exchange couplings are set equal to unity. This model has an infinite number of local conservation laws. For large $\lambda$, the ground state is equivalent to that of the uniform spin $1/2$ chain. Hence, the ground state is a gapless spin liquid. For $\lambda \leq 0$, the ground state is a Lieb-Mattis ferrimagnetic phase with spontaneous magnetization $m_{\rm sp}=1$ per unit cell. For intermediate $\lambda$, we find a series of ferrimagnetic phases with $m_{\rm sp}=1/p$ where $p$ takes positive integer values. The phases with $p \geq 2$ are accompanied by the spontaneous breakdown of the $p$-fold translational symmetry. It is suggested that the phase with arbitrarily large $p$, namely infinitesimal spontaneous magnetization, is allowed as $\lambda$ approaches the transition point to the gapless spin liquid phase.

Efficient sympathetic cooling in mixed barium and ytterbium ion chains

We study sympathetic cooling of the radial ion motion in a linear RF trap in mixed barium-ytterbium chains. Barium ions are Doppler-cooled, while ytterbium ions are cooled through their interaction with cold barium ions. We estimate the efficiency of sympathetic cooling by measuring the average occupation quantum numbers, and thus the temperature, of all radial normal modes of motion in the ion chain. The full set of orderings in a chain of two barium and two ytterbium ions have been probed, and we show that the average thermal occupation numbers for all chain configurations strongly depend on the trap aspect ratio. We demonstrate efficient sympathetic cooling of all radial normal modes for the trap aspect ratio of approximately 2.9.

Quantum Phase Transition of a Quantum Mixed Spin Chain by Employing Density Matrix Renormalization Group Method

AbstractThe fidelity susceptibility and trace distance in the valence‐bond‐solid (VBS) transition of a quantum mixed spin chain is investigated, which consists of unit cells arrayed as 1/2‐1/2‐1‐1 with alternating Heisenberg antiferromagnetic exchange couplings, by using the density matrix renormalization group (DMRG) method in the matrix product state (MPS) form. It is observed that the fidelity susceptibility and the first derivative of the trace distance display explicit divergence near the quantum critical point. The information about the quantum criticality, such as the quantum critical point and correlation length critical exponent, is extracted from the finite size scaling behaviors. The obtained quantum critical point is more accurate than previous work, and the existence of the scaling function of the trace distance near the critical point is observed numerically for the first time. In addition, it is also found that the trace distance between two sites can supplement the VBS picture for describing the change of the ground state as the control parameter is varied through the quantum critical point.

RETRACTED ARTICLE: Value added mechanism and organisational model optimisation of agricultural products circulation value chain from the perspective of game theory

This article has been retracted from publication in the Taylor & Francis journal, Acta Agriculturae Scandinavica, Section B — Soil & Plant Science. Following publication, concerns were raised by multiple third-parties around the content of the special issue and the decision-making process. Following an investigation by the Taylor & Francis Publishing Ethics & Integrity team in full cooperation with the Editor-in-Chief, it was confirmed that this article included in Special Issue titled “ Envisage Computer Modelling and Statistics for Agriculture”, guest edited by Gunasekaran Manogaran was not peer-reviewed appropriately, in line with the Journal's peer review standards and policy. As the stringency of the peer review process is core to the integrity of the publication process, the Editor and Publisher have decided to retract all of the articles within the above-named Special Issue. The journal has not confirmed if the authors were aware of this compromised peer review process. The journal is committed to correcting the scientific record and will fully cooperate with any institutional investigations into this matter. The authors have been informed of this decision. We have been informed in our decision-making by our policy on publishing ethics and integrity and the COPE guidelines.

Understanding interfacial segregation in polymer blend films with random and mixed side chain bottlebrush copolymer additives.

Bottlebrush polymers are complex macromolecules with tunable physical properties dependent on the chemistry and architecture of both the side chains and the backbone. Prior work has demonstrated that bottlebrush polymer additives can be used to control the interfacial properties of blends with linear polymers but has not specifically addressed the effects of bottlebrush side chain microstructures. Here, using a combination of experiments and self-consistent field theory (SCFT) simulations, we investigated the effects of side chain microstructures by comparing the segregation of bottlebrush additives having random copolymer side chains with bottlebrush additives having a mixture of two different homopolymer side chain chemistries. Specifically, we synthesized bottlebrush polymers with either poly(styrene-ran-methyl methacrylate) side chains or with a mixture of polystyrene (PS) and poly(methyl methacrylate) (PMMA) side chains. The bottlebrush additives were matched in terms of PS and PMMA compositions, and they were blended with linear PS or PMMA chains that ranged in length from shorter to longer than the bottlebrush side chains. Experiments revealed similar behaviors of the two types of bottlebrushes, with a slight preference for mixed side-chain bottlebrushes at the film surface. SCFT simulations were qualitatively consistent with experimental observations, predicting only slight differences in the segregation of bottlebrush additives driven by side chain microstructures. Specifically, these slight differences were driven by the chemistries of the bottlebrush polymer joints and side chain end-groups, which were entropically repelled and attracted to interfaces, respectively. Using SCFT, we also demonstrated that the interfacial behaviors were dominated by entropic effects with high molecular weight linear polymers, leading to enrichment of bottlebrush near interfaces. Surprisingly, the SCFT simulations showed that the chemistry of the joints connecting the bottlebrush backbones and side chains played a more significant role compared with the side chain end groups in affecting differences in surface excess of bottlebrushes with random and mixed side chains. This work provides new insights into the effects of side chain microstructure on segregation of bottlebrush polymer additives.

Optimal channel decision of retailers in the dual-channel supply chain considering consumer preference for delivery lead time

Facing competition from manufacturers' online direct channels, how retailers make sales channel decisions to increase consumer stickiness has become the core concern of the industry and academia. Empirical research showed that delivery lead time is a key factor that affects consumers' preference for online channels. To analyze the impact of consumer delivery time preference on channel selection and pricing strategy of retailers, consumer delivery lead time preference function was improved from a linear function to an exponential function and consumer demand under the mixed dual-channel supply chain of manufacturer and retailer was derived. Then, the Stackelberg game models under different channel strategies of retailer were established and solved. Results show that consumer preference for delivery lead time has four implications on the channel decision of retailers under manufacturer encroachment in the dual-channel supply chain. First, the dual retail channels strategy is the optimal choice for retailers, and the profit margins that a retailer obtains from dual retail channels supply chain and single online retail channel supply chain will increase as consumers' delivery lead time preference coefficient increases. Second, the optimal pricing of online retail channel and offline retail channel is positively related to consumers' delivery lead time preference coefficient. By contrast, the optimal pricing of online direct channel is negatively related to consumers' delivery lead time preference coefficient. Third, the optimal pricing of online retail channel is higher than that of offline retail and online direct channels. Fourth, a retailer and a manufacturer can adopt a compensation-based whole price contract to address the conflict brought about by the optimal channel choice of the retailer. This study introduces consumer delivery lead time preference into retailer channel decision making and provides a theoretical reference for retailer's mixed channel construction in practice.

Synthesis and Properties of α-1,3-Glucan with Branched and Linear Mixed Ester Side Chains

Two series of α-1,3-glucan with branched and linear mixed ester side chains, namely α-1,3-glucan pivalate hexanoate (α-1,3-glucan-Pi-Hex) and α-1,3-glucan isobutyrate hexanoate (α-1,3-glucan-iBu-He...

Equilibrium supply chain structures in the presence of asymmetric manufacturer capabilities in service efficacy and provision

In 2012, Tesla Motors announced that it would pursue company owned stores, while major automobile manufacturers, such as Ford and Honda, employ the traditional dealership model. Adding ‘service’ to the McGuire-Staelin duopoly game as another competitive instrument to ‘price’, this paper studies the role of service in shaping an equilibrium supply chain structure to show if and when a mixed supply chain structure of one integrated supply chain and one decentralized supply chain becomes an equilibrium outcome. Our model incorporates asymmetric manufacturer capabilities in service efficacy and provision, where service efficacy refers to the effectiveness of generating a higher demand for a given service level and service provision the cost-efficiency in producing service. Our results show that a mixed supply chain structure emerges as a Nash equilibrium outcome only if two products are moderately substitutable and one manufacturer is superior to the other in service provision with the former downward integrating and the latter decentralizing. Under this scenario, the superior manufacturer raises its profits by investing in service provision capabilities, widening the gap with its opponent, and furthermore, the superior manufacturer compensates for a less differentiated product if it is capable of providing service far more cheaply than its opponent.

Innovative strategy to design a mixed resilient-sustainable electricity supply chain network under uncertainty

Motivated by a real-world case, this paper deals with uncertainty issues in the resilient and sustainable electricity supply chain network design. Uncertainty is always found in electricity demand prediction and perfect foresight is not possible. The resilience of electricity networks in face of uncertainty can prevent catastrophic impacts. Besides, due to the growing concerns about social impacts, considering social measures along with the other measures is becoming critical when analyzing the network costs. In this paper, a multi-objective optimization model is developed, which consists of the total cost in the first objective, resiliency measures in the second objective, and some aspects of corporate social responsibility in the third objective. The resiliency measures minimize de-resiliency, including successive establishment, distributed generators inadequacy, congestion through electrical lines, and energy dissatisfaction level. A novel robust approach is also proposed to deal with the uncertainty of electricity demand based on the light robust programming and possibilistic theory in the fuzzy logic. By investigating a real case in Iran, the contributions of the considered measures, and the effects of uncertainty are analyzed. The analyses reveal that by applying the proposed model the decision-makers can enhance corporate social responsibility and resiliency by 50% and 20%, respectively, although it increases the total cost by 50%. Moreover, the results of applying the proposed fuzzy-robust approach show that how the decision-makers can effectively allocate the uncertainty budget and protection level to attain more robust solutions in terms of standard deviation and mean value of the total cost.

Coupling system dynamics analysis and risk aversion programming for optimizing the mixed noise-driven shale gas-water supply chains

Water management has increasingly become a hotspot in shale gas supply chains. This study develops a comprehensive modeling framework for the mixed noise-driven shale gas-water supply chains, which is integrated with techniques of system dynamics model and two-stage stochastic risk-aversion programming. White and colored noises are used for addressing stochastic characterization of shale gas productivity. Regional water resources carrying capacity is reflected based on the system dynamics model. The developed model cannot only effectively address stochastic parameters in the objective and constraints, but also offer a linkage between the pre-regulated policies and corresponding economic implications raised from improper policies. A Marcellus-based case in Pennsylvania is then performed to validate the applicability of the developed model. Results reveal that shale gas production curve is more sensitive to colored and mixed noises than white noise. High flowback and recycle rates would increase carrying capacity of shale wells by 1.8% in 2023. An increase in weighting factor (e.g., from 0 to 30) would induce a rise in system cost (e.g., from $1.22×1011 to $1.34×1011) but a reduction in conditional value-at-risk value (e.g., from $6.83×1010 to $3.83×1010). Weighting factor thus can be served as an indicator to show how much the decision makers’ attention to system risk.

Effects of mixed organic acids and medium chain fatty acids as antibiotic alternatives on the performance, serum immunity, and intestinal health of weaned piglets orally challenged with Escherichia coli K88

This study was performed to evaluate the effects of combinations of organic acids and medium chain fatty acids (OAMF) as antibiotic alternatives on the performance, serum immunity, and intestinal functions of weaned piglets orally challenged with Escherichia coli K88 (E. coli K88). A total of 150 28-day-old piglets (8.75 ± 0.14 kg) were allocated to five treatments, with five replicates (six piglets) per treatment. The treatments were NC (basal diet); PC (basal diet + E. coli); AGP (basal diet + E. coli +0.04 g/kg zinc bacitracin, 0.03 g/kg chlortetracycline, and 0.05 g/kg kitasamycin); OAMF1 (basal diet + E. coli +2 g/kg OAMF1 overall period); and OAMF2 (basal diet + E. coli +8 g/kg OAMF2 during days 1−14, and 6 g/kg during days 15−28). On day 15, piglets in the PC, AGP, OAMF1, and OAMF2 groups were orally challenged with 20 mL E. coli K88 [108 colony-forming units (CFU)/mL]. Compared with those in the NC group, piglets in the AGP and OAMF1 groups had higher body weights (BW) on day 14 and greater average daily gain (ADG) between days 1 and 14 (P < 0.05). E. coli K88 challenge significantly increased the fecal scores in the PC group (P < 0.05), and the fecal scores in the OAMF1 and OAMF2 groups were lower than that in the PC group (P < 0.05), and higher than that in the AGP group (P < 0.05). Supplementation with OAMF decreased total leukocytes and the percentage of neutrophils (P < 0.05), increased the percentage of lymphocytes (P < 0.05), and increased serum immunoglobulin M (IgM) levels on day 14 and immunoglobulin G (IgG) levels on days 14 and 21 (P < 0.05). Compared with the NC group, the OAMF2 group showed a significantly higher serum interleukin 1β (IL-1β) level on day 21 (P < 0.05). The intestinal villus height and villus height/crypt depth were increased by OAMF supplementation (P < 0.05). E. coli K88 challenge significantly increased the relative abundance of Firmicutes (P < 0.05) and decreased that of Proteobacteria (P < 0.05). Supplementation with OAMF1 decreased the relative abundance of Fusobacteria (P < 0.05) and tended to increase microbiota diversity (P = 0.078). In summary, dietary supplementation with OAMF had positive effects in reducing fecal scores, enhancing immune function, improving intestinal morphology, and stabilizing the ileal bacterial community structure. Thus, OAMF may be used as potential alternatives to AGPs in weanling piglets.

Quantum discord based on linear entropy and thermal negativity of qutrit–qubit mixed spin chain under the influence of external magnetic field

We propose a reliable analytical method to evaluate the non-classical correlations based on linear entropy for an arbitrary qudit–qubit quantum state. The linear entropy is used to overcome the difficulty of the maximization of the classical correlations encountered when the von Neumann entropy is used in determining quantum discord. The quantum discord based on linear entropy is employed to derive the amount of quantum correlations in a qutrit–qubit mixed spin system in the thermal equilibrium at temperature T. We investigate also the situation when the system is embedded in an external magnetic field. The obtained amount of quantum discord is then compared with the measurement-induced disturbance (MID) and logarithmic negativity. The analysis shows that both QD and MID are more robust than entanglement. Besides, QD and MID can be exploited to determine the critical points of quantum phase transitions in the system.

Effect of methoxy groups on liquid crystalline and self-assembling properties of 2,7,12-tris(methoxy)-3,8,13-tris(alkoxy)-5,10,15-truxenones

ABSTRACT Four truxeneones 6a-d in which three long alkoxy chains and three methoxy groups were C3 -symmetrically attached to the truxenone core have been synthesised and studied with the aim to study the effect of bulky methoxy substituents on their mesomorphism and self-assembly properties. These four compounds show enantiotropic mesophase and each has a Colh phase over a 135°C temperature range. A comparison of the side chains showed that 6a-d with mixed alkoxy chains display more complex thermotropic behaviour than reported truxenones possessing six identical long alkoxy chains. Although the methoxy groups have almost no effect on their self-assembly in solution due to the staggered face-to-face arrangement of truxenone moieties, it is confirmed that replacement of three long alkoxy chains by methoxy groups may affect the packing of molecules in the crystalline state more than that within the mesophase. The presence of methoxy groups results in lowering of both the clearing point and the temperature range of the Colh phases by maintaining high melting point. Moreover, 6a self-assembles on a solid/liquid interface into a well-ordered two-dimensional architecture which was explored using high-resolution STM that closely resembles to the proposed bulk mesomorphic three-dimensional columnar phase deduced from XRD.

Wind-electricity-heat Correlation and Potential Uncertainty Analysis Based on Copula Function

In the economic dispatch and optimal operation of power system, it is necessary and effective to consider the correlation among heat load, power load and wind power output to formulate a reasonable dispatch plan or to evaluate the reliability of the system. Therefore, based on the theory of Copula correlation analysis, a multivariate Copula analysis toolbox (MvCAT) is proposed to infer Copula parameters and estimate potential uncertainties. Firstly, the mixed evolution Markov Chain Monte Carlo (MCMC) method in Bayes framework calculates the posterior distribution of Copula parameters, evaluate their uncertainties relative to fitting, and then select the appropriate Copula function by goodness-of-fit test. Finally, a the typical daily data of a province as samples for analysis, proposed method solves the limitation that the local optimization method often falls into the local minimum, and quantitative evaluation of the correlation between the response variables and the uncertainty associated with the length of the recorded data is essential for multivariate frequency analysis.

Revisiting the role of PML protein targeting and disruption of PML bodies in human cytomegalovirus infection

Promyelocytic leukaemia (PML) bodies are nuclear organelles implicated in post-translational modification by small ubiquitin-like modifier (SUMO) proteins and in the antiviral host cell response to infection. The 72-kDa immediate-early protein 1 (IE1) is considered the principal antagonist of PML bodies encoded by the human cytomegalovirus, one of eight human herpesviruses. Previous work has suggested that the interaction between IE1 and PML proteins, the central organisers of PML bodies, and the subsequent disruption of these organelles serve a critical role in viral replication by counteracting intrinsic antiviral immunity and the induction of interferon (IFN)-stimulated genes. However, this picture has emerged largely from studying mutant IE1 proteins known or predicted to be globally misfolded und metabolically unstable. We systematically screened for stable IE1 mutants by clustered charge-to-alanine scanning. We identified a mutant protein (IE1cc172-176) selectively defective for PML interaction. Functional comparisons between the mutant and wild-type protein revealed that IE1 can undergo modification by mixed polymeric SUMO chains and that it targets PML and Sp100, the two main constituents of PML bodies, via distinct mechanisms. Unexpectedly, IE1cc172-176 supported viral replication almost as efficiently as wild-type IE1. Moreover, lower instead of higher (as expected) levels of tumor necrosis factor alpha, IFN-beta, IFN-lambda and IFN-stimulated gene expression were observed with the mutant compared to the wild-type protein and virus. These results suggest that the disruption of PML bodies is linked to induction rather than inhibition of antiviral gene expression. Our findings challenge current views regarding the role of PML bodies in viral infection.

The Effect of Mixed Chain Extender on the Hydrogen Bonding, Thermal and Mechanical Properties of TPUs

Chain extender plays a significant role in enhancing the final mechanical properties of thermoplastic polyurethane (TPUs) derived from polytetra methylene etherglycol (PTMG) and 4,4-diphenylmethane diisocyanate (MDI). In this research we focused on the effect that mixed chain extender of ethylene glycol (EG) and 1,4-butanediol (BDO) used has on the phase behavior and morphology of high hard block content TPUs. DSC, FTIR, and mechanical testing were mainly used to characterize the morphology and properties of the TPUs materials. Through this work we were able to show that mixed ratio of different chain extenders had dramatic effects on the properties of the TPUs. After mixing EG and BDO, the degree of hydrogen bonding, melting temperature, tensile strength, tear strength, and hardness of TPUs are all reduced, the glass transition temperature is increased. when the mixing ratio is 1: 1 , the elongation at break is increased to 672% . However, when the mixing ratio is n (EG): n (BDO) = 1: 2, the tensile strength is increased to 29.2 MPa, and the elongation at break is reduced to 353%.

The TeraNova platform: An integrated testbed for ultra-broadband wireless communications at true Terahertz frequencies

Terahertz (THz)-band (0.1 THz to 10 THz) communication is envisioned as a key technology to meet the demand for faster, more ubiquitous wireless communication networks. For many years, the lack of compact, fast and efficient ways to generate, modulate, detect and demodulate THz-band signals has limited the feasibility of such communication systems. Recently, major progress within different device technologies is finally closing the so-called THz gap. For the time being, communication testbeds have been developed at sub-THz frequencies, i.e., at or near the boundary with millimeter-wave communication systems. Nonetheless, higher carrier frequencies and their associated bandwidth are needed to meet the demand for much higher data rates. In this paper, the TeraNova platform, i.e., the first integrated testbed for ultra-broadband wireless communications at true THz-band frequencies, is presented. The system consists of a transmitter and a receiver based on Schottky-diode frequency multiplying and mixing chains able to up & down-convert an information-bearing intermediate frequency (IF) signal up to 40 GHz-wide between 1 and 1.05 THz, i.e., the first absorption-defined transmission window above 1 THz. Guided by the experimental characterization of the THz channel in terms of path-loss and noise, tailored framing, time synchronization, channel estimation and single- and multi-carrier modulation techniques are implemented in software and realized by a state-of-the-art arbitrary waveform generator and a digital storage oscilloscope at the transmitter and the receiver, respectively. Experimental results are presented herein to highlight the opportunities and challenges to unleash the potential of the THz band.

Experimental realization of Lieb-Mattis plateau in a quantum spin chain

Topological properties in material science have recently received tremendous attention, as exemplified by topological insulators. As for quantum spin systems, the Haldane chain with integer spins is the best known example1. The realization of a topological quantum phase in the Haldane chain is an innovative research development related to the 2016 Nobel Prize in Physics. For mixed spin chains composed of two different spins, the appearance of a topologically quantized magnetization plateau is predicted by the Lieb-Mattis theorem2 in combination with the Oshikawa-Yamanaka-Affleck criterion3. However, the actual magnetization plateau in the mixed spin chain has not yet been observed. Here, we present a model compound forming a mixed spin-(1/2, 5/2) chain. We observe a clear Lieb-Mattis plateau and well explain it quantitatively. The present results demonstrate a quantum many-body effect based on quantum topology and provide a new stage in the search for topological properties in condensed matter physics.