Search

A new type of polyhedral oligomeric silsesquioxanes bisDOPO-NH2-POSS flame retardant consisting of one polyhedral oligomeric silsesquioxane (POSS), two units of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and reactive –NH2 groups, was synthesized and characterized by FTIR, 1H NMR, and 31P NMR. It was applied to modified conventional environmentally friendly E0 grade urea formaldehyde (UF) resin to prepare flame-retardant plywood. Two other POSS structure flame retardants were used for comparison. The results showed that the addition of bisDOPO-NH2-POSS flame retardant to E0 UF resin improved bonding strength while lowering formaldehyde emission owing to the increase in cross-linking of the UF molecule chain in condensation. TGA curves showed that bisDOPO-NH2-POSS-E0 UF exhibited the highest thermal stability. The flammability characteristics of the plywood were evaluated by a cone calorimeter test (CCT), and the results indicated that the heat release and smoke production of flame-retardant plywood were lower than those of the control E0-UF plywood. Moreover, compared to E0-UF plywood, the char residue remaining after the CCT test of the flame-retardant plywood with POSS structure increased. In particular, bisDOPO-NH2-POSS-E0-plywood had a continual compact outer carbon layer, which was conducive to effectively forming a physical barrier to hinder the penetration of oxygen and heat and exhibiting the outstanding synergistic effect of phosphorous, silicon and nitrogen. [ABSTRACT FROM AUTHOR]

This study uses the structural vector autoregression (SVAR) and nonlinear autoregressive distributed lag (NARDL) models to examine the long- and short-term asymmetric effects of structural state media shocks on the Chinese stock market. The findings, obtained using Xinwen Lianbo as a stand-in for state media, indicate that attention shocks on Xinwen Lianbo have an asymmetrical impact on the aggregate stock market returns in both the short and long run. The sectoral and overall stock market results are similar, with CCTV having a stronger impact in the first half of the pandemic. Employing other COVID-19 news measurements, we validated our primary findings and discovered that the price function differs among various state media's attention to COVID-19. [ABSTRACT FROM AUTHOR]

This paper investigates the pricing issue of power exchange options with default risk, in which the dynamics of the underlying assets and the counterparty asset follow three correlated stochastic volatility models with stochastic interest rate. We assume that the volatility risk is decomposed into short-term and long-term volatility. The stochastic interest rate is driven by the CIR (Cox-Ingersoll-Ross) process. Based on the proposed model, we derive a closed-form solution for the price of power exchange option with default risk by means of Fourier transform. Besides, the price of power exchange option with default risk can be quickly computed by employing the fast Fourier transform (FFT) algorithm. The results of Monte Carlo simulations demonstrate that the FFT is fast and accurate. More importantly, the pricing model also shows that: (i) a higher long-run mean of the underlying asset price's instantaneous variance induces a higher value of power exchange option with default risk; (ii) the long-run mean of instantaneous variance in counterparty's asset value has a negative impact on the price of power exchange option with default risk; and (iii) the higher the long-run mean of stochastic interest rate, the higher the power exchange option price. [ABSTRACT FROM AUTHOR]

Many systems are required to perform a series of missions with finite breaks between any two consecutive missions. To improve the probability of system successfully completing the next mission, maintenance action is carried out on components during the breaks. In this work, a selective maintenance model with stochastic maintenance quality for multi-component systems is investigated. At each scheduled break, a set of maintenance actions with different degrees of impact are available for each component. The impact of a maintenance action is assumed to be random and follow an identified probability distribution. The corresponding maintenance cost and time are modelled based on the expected impact of the maintenance action. The objective of selective maintenance scheduling is to find the cost-optimal maintenance action for each component at every scheduled break subject to reliability and duration constraints. A simulated annealing algorithm is used to solve the complicated optimisation problem where both multiple maintenance actions and stochastic quality model are taken into account. Two illustrative numerical examples and a real case study have been solved to demonstrate the performance of the proposed approach. A comparison with deterministic maintenance shows the importance of considering the proposed stochastic quality in selective maintenance scheduling. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the observer-based event-triggered consensus problem for linear multi-agent systems (MASs) under a directed graph and denial-of-service (DoS) attacks. A type of DoS attacks launched by malicious attackers at irregular intervals is considered, which can cause communication channel disruption. A novel event-triggered secure control scheme based on a closed-loop observer is proposed to determine the scheduling of the controller update, and a separation method with less conservativeness is employed to design the controller and observer gains. Then, the frequency and duration of DoS attacks that can be tolerated are analysed for the observer-based secure consensus problem. In addition, a strictly positive minimal event-triggered time interval for each agent is designed with the help of the proposed event-triggered condition to eliminate the Zeno behaviour. Finally, a numerical simulation is given to verify the theoretical analysis. [ABSTRACT FROM AUTHOR]

Trough profile is an important structural parameter of the spiral concentrator. However, limited attention has been focused on the influence of trough profile on coal separation. In the present work, 21 sets of experiments were carried out to investigate the impact of operating parameters and trough profile on the separation performance. Results show that particles tend to transport outward with the increase of the flow rate and the solid concentration. The cut specific gravity of separation (SG50) increases with the flow rate and the solid concentration. The SG50 of the spiral concentrator with the synthetic curve is much lower than that of spiral concentrator with the ellipse or cubic parabola. Light particles prefer to be placed in the outer place of the spiral concentrator with the trough profile of ellipse. Heavy particles tend to report to the inner region of the spiral concentrator with the trough profile of cubic parabola. The spiral concentrator, with the trough profile of cubic parabola in inner place and the ellipse in outer place, is more desirable to separate the coal slime used in this paper. The findings of the present study are of great importance in trough profile optimization of the spiral concentrator. [ABSTRACT FROM AUTHOR]

Objectives: The aim of this study was to explore the predictive recurrence value of the PET/CT index and some clinical features in patients with IIB-IVA cervical cancer.Methods: This was a retrospective analysis of 84 patients with cervical cancer who underwent 18 F-FDG PET/CT scans before treatment. MTV-s is the sum of the metabolic volume of the primary cervical lesion (MTV-C) and the metabolic volume of the pelvic and abdominal paravascular metastatic lymph nodes (MTV-LN). We analyzed the relationships between clinical characteristics (age, FIGO stage, pathological pattern, degree of differentiation, tumor size, presence of LN metastasis), PET/CT index (SUVmax-C, SUVmax-LN, MTV-C, MTV-LN, MTV-s), and recurrence of cervical cancer using the chi-square test; the ROC curve was used to determine the PET/CT boundary parameters; and the COX proportional risk model was used for univariate and multivariate analysis of clinical features and the PET/CT index. The survival curve was drawn using the Kaplan-Meier method, comparing different groups by the log-rank test.Results: Eighty-four patients were included. During the observation period, 26 patients had tumor recurrence (31.0%). Univariate analysis showed that lymph node metastasis, lymph node SUVmax (SUVmax-LN), MTV-C, MTV-LN, and MTV-s were associated with PFS. MTV-s > 27.36 cm3 was an independent risk factor for PFS (P = 0.037). There were 41 patients with MTV-s > 27.36 cm3, and 19 of them had tumor recurrence (46.3%). There were 43 patients with MTV-s ≤ 27.36 cm3, 7 of whom had tumor recurrence (16.3%).Conclusion: MTV-s can predict recurrence in patients with stage IIB-IVA cervical cancer, with a critical value of 27.36 cm3. PET/CT can help clinicians judge the prognosis of patients more comprehensively. [ABSTRACT FROM AUTHOR]

This paper considers the frequency regulation and power-sharing problems for cyber-physical microgrids (MGs) under network denial-of-service (DoS) attacks and time-varying communication delays. Compared to conventional distributed controllers based on a system model with ideal communication, a distributed security control protocol is designed. Benefiting from the developed security control method, the adverse effects of network DoS attacks and communication delays can be resisted. Then, a sufficient condition, which is used to achieve the achieve frequency restoration and power-sharing, is established according to the frequency and duration of DoS attacks. By using the average dwell time method and the Lyapunov stability theory, it is theoretically proved that the proposed control scheme can guarantee the stability of the overall AC microgrid system. In order to illustrate the proposed scheme, simulation studies are carried out based on an islanded AC microgrid system with four distributed generators (DGs) built in the simulation. The results do show its effectiveness and also verify the established theoretical results. [ABSTRACT FROM AUTHOR]

Two new Cu(II)-based coordination polymers (CPs) {[Cu3(btc)2(bpfp)2(H2O)2](H2O)2}n (1, H3btc = 1,2,3-benzenetricarboxylic acid, bpfp = bis(4-pyridylformyl)piperazine) and {[Cu(cca)(bpfp)]·2H2O}n (2, H2cca = 2-carboxycinnamic acid) have been successfully prepared by reaction of Cu(NO3)2·3H2O with the bpfp ligand in the presence of different carboxylate ligands. Compounds 1 and 2 were synthesized for the evaluation of anti-cancer activity on the ovarian cancer cells CoC1. First of all, the cancer cell proliferation, migration and invasion ability were determined. Subsequently, the marker of the ovarian cancer cells-miRNA16 was also measured with real time reverse transcription-polymerase chain reaction (RT-PCR). [ABSTRACT FROM AUTHOR]

This paper considers an insurer with constant absolute risk aversion (CARA) preference and explores a reinsurance-investment optimisation problem where the insurer income is related to the historical wealth performance. The insurer can purchase proportional reinsurance contracts to transfer the claim risk and allocate the remaining liquid wealth in a savings account, a defaultable corporate zero-coupon bond and a risky asset with constant elasticity of variance (CEV) stochastic volatility. The problem is modelled using a stochastic system with delay. Under certain conditions, the analytic optimal reinsurance-investment policy is derived, and the corresponding verification theorem is provided. Finally, a sensitivity analysis is conducted on the optimal reinsurance-investment policies over different memory parameters. The results show that longer memory leads to more prudent reinsurance and investment decisions for the insurer. [ABSTRACT FROM AUTHOR]

The bi-directional duplex working mode of a transmit-receive integrated optical antenna in laser communication systems has a rigorous requirement on transmission and receiver(T/R) isolation. By using an off-axis three-mirror anastigmat (TMA) optical antenna, backscattered can be significantly reduced, thus achieving high T/R isolation. This paper proposes to design the light exit angle of 5° or larger in the off-axis TMA optical antenna and use the equivalent surface roughness (ESR) to evaluate the surface scattering characteristics of reflector in optical antenna. Therefore, by increasing the ESR of reflector, the isolation of the optical antenna can be improved. In an isolation measurement experiment, the measured isolation of the F150mm off-axis TMA optical antenna was 73 dB, which is consistent with the simulation result. The achieved T/R isolation level meets the requirements for acquiring, tracking, and communication of satellite laser communication systems. [ABSTRACT FROM AUTHOR]

Coronary artery disease is a leading cause of death in developed nations. As the disease progresses, myocardial infarction can occur leaving areas of dead tissue in the heart. To compensate, the body initiates its own repair/regenerative response in an attempt to restore function to the heart. These efforts serve as inspiration to researchers who attempt to capitalize on the natural regenerative processes to further augment repair. Thus far, researchers are exploiting these repair mechanisms in the functionalization of soft materials using a variety of growth factor-, ligand- and peptide-incorporating approaches. The goal of functionalizing soft materials is to best promote and direct the regenerative responses that are needed to restore the heart. This review summarizes the opportunities for the use of functionalized soft materials for cardiac repair and regeneration, and some of the different strategies being developed. [ABSTRACT FROM AUTHOR]

Recursive Least Square (RLS) filter has been applied to real-time lossless compression of hyperspectral imagery and been proved a high performance onboard algorithm. Recent research has revealed that the RLS filter with Adaptive-Length-Prediction (ALP) can significantly improve the compression performance. However, the prediction procedure with numerous bands slows down the run-time and is nearly impossible to be applied onboard. In this letter, we proposed a fast RLS algorithm which can accelerate the ALP stage by exploiting the feature of the projection matrix of the RLS algorithm. The experiment results illustrated that with the same compression ratio, the proposed algorithm is 100 times faster than the traditional RLS algorithm with ALP. [ABSTRACT FROM AUTHOR]

Phthalate esters (PAEs) have attracted much attention because of their ubiquity and toxicity. However, previous studies mainly focused on the occurrence of PAEs controlled by the Environmental Protection Agency and neglected most uncontrolled PAEs. In this study, the occurrence of 21 PAEs, including 6 controlled and 15 uncontrolled PAEs, was investigated in polyethylene terephthalate (PET)-bottled drinking water samples purchased from markets in Beijing. Seventeen PAEs were detected in all samples, with dibutyl phthalate, diisobutyl phthalate, and dimethyl phthalate as the predominant compounds. Correlation analysis suggested that PET bottles might be one of the potential sources of PAEs in PET-bottled drinking water. The human health risks assessments indicated little or no risks from four controlled PAEs in bottled water. In comparison, the risks of uncontrolled PAEs should be of greater concern for their ubiquities in bottled drinking water. [ABSTRACT FROM AUTHOR]

The study works on a multi-level maintenance policy combining system level and unit level under soft and hard failure modes. The system experiences system-level preventive maintenance (SLPM) when the conditional reliability of entire system exceeds SLPM threshold, and also undergoes a two-level maintenance for each single unit, which is initiated when a single unit exceeds its preventive maintenance (PM) threshold, and the other is performed simultaneously the moment when any unit is going for maintenance. The units experience both periodic inspections and aperiodic inspections provided by failures of hard-type units. To model the practical situations, two types of economic dependence have been taken into account, which are set-up cost dependence and maintenance expertise dependence due to the same technology and tool/equipment can be utilised. The optimisation problem is formulated and solved in a semi-Markov decision process framework. The objective is to find the optimal system-level threshold and unit-level thresholds by minimising the long-run expected average cost per unit time. A formula for the mean residual life is derived for the proposed multi-level maintenance policy. The method is illustrated by a real case study of feed subsystem from a boring machine, and a comparison with other policies demonstrates the effectiveness of our approach. [ABSTRACT FROM AUTHOR]

Biodiesel produced from oil-rich feedstocks is known as a green replacement for conventional petroleum diesel. Transesterification is the common method used for biodiesel production. Hence, in this contribution, neural network modeling and least square support vector machine (LSSVM) modeling were used to predict the transesterification of castor oil with methanol to form biodiesel. Also, genetic algorithm was used for the optimization of predictive model. Input and output parameter of predictive models for the prediction of biodiesel production yield and estimation of the efficiency of biodiesel production are catalyst weight (C), methanol-to-oil molar ratio (MOR), time (S), temperature (T), and fatty acid methyl ester (FAME) yield, respectively. Proposed LSSVM modeling predicts biodiesel production yield or FAME yield within ±2% relative deviation with a high value of coefficient of determination (0.99583) and a low value of absolute deviation (1.27) in which the mentioned statistical parameters represent the accuracy and robustness of the model. [ABSTRACT FROM AUTHOR]

This paper considers the distributed adaptive consensus problem for linear multi-agent systems with quantised relative information. By using a lemma in algebraic graph theory and introducing a projection operator in adaptive law, a novel distributed adaptive state feedback controller is designed with quantised relative state information. It is shown that the practical consensus for multi-agent systems with a uniform quantiser is achieved via the Lyapunov theory and the non-smooth analysis. In contrast with the existing quantised controllers, which rely on the minimum nonzero eigenvalue of the Laplacian matrix, the developed controller is only dependent on the number of nodes. Furthermore, a dynamic output feedback controller based on quantised relative output information is proposed. Finally, a simulation example is given to illustrate the effectiveness of the proposed control scheme. [ABSTRACT FROM AUTHOR]

This work investigates an optimal financing and dividend problem for an insurer whose surplus process is modulated by an observable continuous-time and finite-state Markov chain. We assume that the insurer should never go bankrupt by issuing new equity. The goal of the insurer is to maximize the expected present value of the dividends payout minus the discounted cost of equity issuance. We obtain the optimal policies and explicit expressions for the value functions when the risk reserve process is modeled by both upward jump model and its diffusion approximation. Numerical illustrations of the sensitivities of the model parameters are provided. [ABSTRACT FROM AUTHOR]

Novel diacetylene macrocycles1and2bearing dibenzylphosphine oxide were synthesised via Eglinton acetylenic intramolecular coupling. The X-ray analysis of crystals of macrocycles1and2demonstrated that the better-aligned tubular supramolecular structure was formed in macrocycle1than in macrocycle2, which provided the possibility of diacetylene topochemical polymerisation in solid state of macrocycle1. UV–vis, Raman spectroscopy and X-ray analysis indicated that the crystals of macrocycle 1 could undergo topochemical diacetylene polymerisation only on their surface by light irradiation; differential scanning calorimetry, solid-state13C NMR spectroscopy and solubility test demonstrated that the crystals of macrocycle1could undergo diacetylene topochemical polymerisation inside solid by heat. As expected, based on the topological analysis of crystal structure, the crystals of macrocycle2could not undergo diacetylene topochemical polymerisation either by light irradiation or heat. [ABSTRACT FROM PUBLISHER]

The chemotherapy of hematological cancers is challenged by its poor selectivity that leads to low therapeutic efficacy and pronounced adverse effects. Here, we report that doxorubicin encapsulated in lipoic acid-crosslinked hyaluronic acid nanoparticles (LACHA-DOX) mediate highly efficacious and targeted inhibition of human hematological cancers including LP-1 human multiple myeloma (MM) and AML-2 human acute myeloid leukemia xenografted in nude mice. LACHA-DOX had a size of ca. 183 nm and a DOX loading content of ca. 12.0 wt.%. MTT and flow cytometry assays showed that LACHA-DOX possessed a high targetability and antitumor activity toward CD44 receptor overexpressing LP-1 human MM cells and AML-2 human acute myeloid leukemia cells. Thein vivoandex vivoimages revealed that LACHA-DOX achieved a significantly enhanced accumulation in LP-1 and AML-2 tumor xenografts. Notably, LACHA-DOX effectively suppressed LP-1 as well as AML-2 tumor growth and drastically increased mice survival rate as compared to control groups receiving free DOX or PBS. Histological analyses exhibited that LACHA-DOX caused little damage to the major organs like liver and heart. This study provides a proof-of-concept that lipoic acid-crosslinked hyaluronic acid nanoparticulate drugs may offer a more safe and effective treatment modality for CD44 positive hematological malignancies. [ABSTRACT FROM AUTHOR]

Three hyperbranched polyglycerols with different molecular weight were synthesized by controlling the molar ratio of monomer and initiator. La-doped TiO2catalysts were synthesized by those HPG as a templating agent for size control of La/TiO2. The photocatalytic elimination of methanol was used as model reactions to evaluate the photocatalytic activity of the catalysts. The size of La/TiO2particles could be adjusted by changing the molecular weight of the HPG. With the molecular weight of HPG increase, the size of La/TiO2particles decrease, the photocatalytic activity of the as-prepared catalysts enhance. This catalytic reaction follows the Langmuir-Hinshellwood mechanism. [ABSTRACT FROM AUTHOR]

The N-methyl-d-aspartate (NMDA) system closely interacts with the dopaminergic system and is strongly implicated in the pathophysiological mechanisms and therapeutic paradigms of Parkinson's disease. This study aims to systematically investigate the changes of NMDA receptors in a wide range of brain structures 3 weeks after unilateral medial forebrain bundle lesion by 6-hydroxydopamine (6-OHDA). NMDA receptor distributions and alterations in the post-mortem rat brain were detected by [3H] MK-801 binding autoradiography. In the 6-OHDA-induced Parkinsonian rat model, nigrostriatal dopaminergic neuron loss significantly mediated the decreased [3H] MK-801 binding, predominantly in the hippocampus (−22.4%, p < 0.001), caudate putamen (−14.1%, p < 0.01), accumbens nucleus (−13.8%, p < 0.05), cingulate cortex (−13.4%, p < 0.001), posteromedial cortical amygdala (−14.5%, p < 0.01) and piriform cortex (−9%, p < 0.05) compared to the controls, while there was a profound reduction of tyrosine hydroxylase (TH) immunohistochemistry in the substantia nigra pars compacta. Alterations in [3H] MK-801 in the specific brain regions related to cognitive functions may indicate that cognitive dysfunctions caused by 6-OHDA lesion were via the NMDA system. The downregulation of NMDA receptor binding in the present study provides indirect evidence for plasticity in the NMDA system in the rat brain. The present study improves our understanding of the critical roles of the NMDA receptors in treating neurodegenerative disorders, and implicates NMDA receptors as a novel therapeutic target in the treatment of Parkinson's disease. [ABSTRACT FROM AUTHOR]

Injectable hydrogels are increasingly being developed for biomedical applications due to their ability to be delivered in a minimally invasive manner. One potential use for such materials is in cell delivery for cardiac regeneration. While the materials' properties are often characterized, how these properties (and in particular gelation) are affected by the addition of the therapeutic agent(s) they are designed to deliver is often overlooked. The aim of this study was to examine the interactive effects between collagen-based hydrogels and different additives (cells and microspheres). The results demonstrated that the incorporation of either cells or microspheres to a collagen hydrogel decreased its gelation time and increased its viscosity. Increased concentrations of the EDC/NHS cross-linker resulted in greater loss of cell viability. However, it was found that this cell loss could be minimized by delivering cells with the cross-linker scavenger glycine. A better understanding of how materials and cells (and other additives) respond to each other will help towards the goal of improving scaffolds being developed for regenerative therapy. [ABSTRACT FROM AUTHOR]

Applications to massive data raise two challenges to supervised learning. First, sufficient training examples to ensure the generalization ability become unavailable, since labelling by experts is expensive; second, it is impossible to load massive data into memory, and the response time is unacceptable by a serial mode. In this paper, we gracefully combine semi-supervised learning with parallel computing to meet these two challenges together. In detail, (1) the co-training style of semi-supervised learning named tri-training is exploited and revised in order to perform learning from the labelled and the unlabelled data. In particular, the co-training process is revised by introducing data editing to remove the newly mislabelled data. (2) The learning algorithm for each individual classifier and the data editing are re-formed as the MapReduce parallel pattern. Experiments on University of California, Irvine, Machine Learning Repositoy data sets and the application to CT images detection show improvement in the accuracy and the scalability to massive data. [ABSTRACT FROM AUTHOR]