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Despite several studies on corporate social responsibility (CSR) and innovation on firm performance, the extent to which different CSR practices interacts with distinct innovation types in enhancing firm performance remains underexplored. We draw on contingency theory to examine how internal and external CSR interacts with exploitative and explorative innovation to improve firm performance. We discuss the interaction effects using a panel dataset of 1156 publicly listed Chinese firms that disclosed CSR and innovation information from 2008 to 2019. The results indicate that firms with high‐internal CSR benefit to a greater extent from explorative innovation than from exploitative innovation as a means of enhancing performance. In contrast, firms with high‐external CSR benefit to a greater extent from exploitative innovation than from explorative innovation to improve performance. We contribute to strategy and CSR literature by revealing how firms match specific CSR practices with distinct innovation types to enhance firm performance. [ABSTRACT FROM AUTHOR]

We study the existence of fixed points, local stability analysis, bifurcation sets at fixed points, codimension‐one and codimension‐two bifurcation analysis, and chaos control in a predator‐prey model with Holling types I and III functional responses. It is proven that the model has a trivial equilibrium point for all involved parameters but interior and semitrivial equilibrium solutions under certain model parameter conditions. Furthermore, local stability at trivial, semitrivial, and interior equilibria using the theory of linear stability is investigated. We have also explored the bifurcation sets for trivial, semitrivial, and interior equilibria and proved that flip bifurcation occurs at semitrivial equilibrium. Furthermore, it is also proven that Neimark–Sacker bifurcation as well as flip bifurcation occurs at an interior equilibrium solution, and in addition, at the same equilibrium solution, we also studied codimension‐two 1 : 2 strong resonance bifurcation. Then, OGY and hybrid control strategies are employed to manage chaos in the model under study, which arises from Neimark–Sacker and flip bifurcations, respectively. We have also examined the preservation of the positive solution of the understudied model. Finally, numerical simulations are given to verify the theoretical results. [ABSTRACT FROM AUTHOR]

Spider silk, possessing exceptional combination properties, is classified as a bio‐gel fiber. Thereby, it serves as a valuable origin of inspiration for the advancement of various artificial gel fiber materials with distinct functionalities. Gel fibers exhibit promising potential for utilization in diverse fields, including smart textiles, artificial muscle, tissue engineering, and strain sensing. However, there are still numerous challenges in improving the performance and functionalizing applications of spider silk‐inspired artificial gel fibers. Thus, to gain a penetrating insight into bioinspired artificial gel fibers, this review provided a comprehensive overview encompassing three key aspects: the fundamental design concepts and implementing strategies of gel fibers, the properties and strengthening strategies of gel fibers, and the functionalities and application prospects of gel fibers. In particular, multiple strengthening and toughening mechanisms were introduced at micro, nano, and molecular‐level structures of gel fibers. Additionally, the existing challenges of gel fibers are summarized. This review aims to offer significant guidance for the development and application of artificial gel fibers and inspire further research in the field of high‐performance gel fibers. [ABSTRACT FROM AUTHOR]

To address the rising energy demands in industrial and public sectors, integrating zero‐carbon emission energy sources into the power grid is crucial. Smart grids, equipped with advanced sensing, computing, and communication technologies, offer an efficient way to incorporate renewable energy resources and manage power systems effectively. However, improving solar energy efficiency, which currently contributes around 3.6% to global electricity, is a challenge in smart grid infrastructures. This research tackles this issue by deploying machine learning models, specifically recurrent neural network (RNN), long short‐term memory (LSTM), and gate recurrent unit (GRU), to predict measurements that could enhance solar power generation in smart grids. The objective is to boost both performance and accuracy of solar power generation in the smart grid. The study conducts experimental analyses and performance evaluations of these models in smart grid environments, considering factors like power output, irradiance, and performance ratio. The results, presented through graphical visualizations, show notable improvements, particularly with the LSTM model, which achieves a 97% accuracy, outperforming the RNN and GRU models. This outcome highlights the LSTM model's effectiveness in accurately predicting measurements, thereby advancing solar power generation efficiency in the smart grid framework. [ABSTRACT FROM AUTHOR]

It is highly desirable to develop fiber materials with high strength and toughness while increasing fiber strength always results in a decrease in toughness. Spider silk is a natural fiber material with an excellent combination of high strength and toughness, which is produced from the spinning dope solution by gelation and drawing spinning process. This encourages people to prepare artificial fibers by mimicking the material, structure, and spinning of natural spider silk. In this review, we first summarized the preparation of artificial spider silk prepared via such a gelation process from different types of materials, including nonrecombinant proteins, recombinant proteins, polypeptides, synthetic polymers, and polymer nanocomposites. In addition, different spinning approaches for spinning artificial spider silk are also summarized. In the third section, some novel application scenarios of the artificial spider silk were summarized, such as artificial muscles, sensing, and smart fibers. [ABSTRACT FROM AUTHOR]

We examine the unboundedness, persistence, boundedness, uniqueness, and existence of non‐negative equilibrium of an exponential difference equations system. Furthermore, we will discuss asymptotic global and local stability and the convergence rate of this system. Ultimately, to check our theoretical results, we set out some numerical explanations. [ABSTRACT FROM AUTHOR]

A novel boron‐containing hyperbranched benzoxazine (HB‐B) was synthesized from the reaction of triethanolamine borate (BAE), bisphenol‐A, and paraformaldehyde via Mannich condensation. The chemical structures of BAE and HB‐B were characterized by Fourier transform infrared (FT‐IR) and hydrogen nuclear magnetic resonance (1H NMR). Afterward, the boron‐containing hyperbranched benzoxazine/epoxy resin copolymers (E51/HB‐B) were prepared. The curing behavior of ‐B and E51/HB‐B was studied by FT‐IR and differential scanning calorimeter (DSC). The thermal stability and flame retardancy properties of the cured HB‐B and E51/HB‐B were evaluated by thermogravimetric analyzer (TGA), limited oxygen index (LOI), UL94 rating test, and microscale combustibility calorimeter experiments (MCC). The initial thermal decomposition temperature and glass transition temperature steadily dropped with increasing HB‐B content, while the char yield kept rising. The LOI value of the E51/HB‐B‐12 wt% was 31.8%, meeting the UL94 V‐0 specification. The result of heat release capacity (HRC) decreased by 20.4%. Moreover, the mechanical properties were also improved, and the tensile strength of E51/HB‐B copolymer was increased by 88.5%. Finally, the fracture morphology of E51/HB‐B was characterized by SEM. [ABSTRACT FROM AUTHOR]

Arthropods can be either large or too small to be seen from the microscope. Their legs are jointed and perform a specific function in the soil. Several arthropods have been identified to date. Therefore, it is essential to identify them in a different type of soil. An experiment to quantify the soil arthropods in the urban forests of D.G. Khan was conducted at the Zoology lab of Ghazi University on four tree plants, i.e., neem (Azadirachta indica), mango (Mangifera indica), guava (Psidium guajava), and phalsa (Grewia asiatica). Soil samples were taken from different areas and on different months. The diversity of arthropods was analyzed through the Shannon index. The results were all significant. The total number of arthropods found in the experiment was 5151, with the following distributions: millipedes were 132 in neem, 133 in guava, 113 in mango, and 121 in phalsa; centipedes were 136 in neem, 142 in guava, 118 in mango, and 132 in phalsa; springtails were 138 in neem, 130 in guava, 120 in mango, and 134 in phalsa. There were a total of 12 different species of arthropods found. Neem (Azadirachta indica) have mites, centipede, and ants; guava (Psidium guajava) have centipedes and ants. Mango (Mangifera indica) have millipedes, centipedes, mites, springtail, and ants, and phalsa (Grewia asiatica) have mites, ants, and centipedes. The study reveals that millipedes, centipedes, springtails, and ants were found abundantly in the urban forest area of D.G. Khan, resulting in increased organic matter decomposition and appropriate distribution of nutrients through the soil having beneficial effects on the terrestrial ecosystem. [ABSTRACT FROM AUTHOR]

The local dynamics, chaos, and bifurcations of a discrete Brusselator system are investigated. It is shown that a discrete Brusselator system has an interior fixed point P 1 , r if r > 0. Then, by linear stability theory, local dynamical characteristics are explored at interior fixed point P 1 , r . Furthermore, for the discrete Brusselator system, the existence of periodic points is investigated. The existence of bifurcations around an interior fixed point is also investigated and proved that the discrete Brusselator model undergoes hopf and flip bifurcations if r , h ∈ ℋℬ | P 1 , r = r , h , h = 2 − r and r , h ∈ ℱℬ | P 1 , r = r , h , h = 4 / 2 − r − r 2 − 4 r , respectively. The next feedback control method is utilized to stabilize the chaos that exists in the discrete Brusselator system. Finally, obtained results are verified numerically. [ABSTRACT FROM AUTHOR]

The randomly‐oriented glass fibers (GF) reinforced composites with Bisphenol A–amine based benzoxazine (BA‐a) and bio‐based eugenol‐based phthalonitrile (EPN) copolymer were developed by an isothermal compression molding technique. The silane coupling agent‐treated GF (TGF) reinforced composites showed much better impact strength as compared to as‐received GF reinforced composites. A rise of 95.2 MPa, 5.5GPa, 69.1 MPa, and 2.5GPa in flexural strength, flexural modulus, tensile strength, and Young's modulus were observed, respectively. The DMA results confirmed that the storage modulus (E') and glass transition temperature (Tg) were gradually increased and the damping factor decreased as the TGF reinforcement was raised from 0 to 40 wt%. E' and Tg values were 3.09 GPa and 27°C, respectively, higher than the recorded values for the neat copolymer. The 40 wt% TGF reinforced poly(BA‐a/EPN) composite showed the maximum thermal stability values of 475.4, 507.3°C, and 75.43% for T5, T10, and Yc, respectively. The LOI values confirm that the TGF/copolymer composites have self‐extinguishing properties. [ABSTRACT FROM AUTHOR]

In this work, hazelnut shell (HS) particles were added to the bisphenol‐A aniline‐based benzoxazine (BA‐a) matrix and micro‐sized HS particles of varying weight percent (5%, 10%, 15%, 20%, 25%) were successfully blended with BA‐a resin. The effects of reinforcing HS particles to the neat matrix were studied. The curing behavior, mechanical properties, and thermal degradation of the composites were performed using differential scanning calorimetry, tensile and impact tests, and thermogravimetric analysis. Glass transition temperature (Tg) was lowered to 16°C which is 4% less than the neat matrix, increase in char yield (Yc) was recorded in composites. Tensile and impact strength of the prepared composites was improved significantly. There was 82.6% increase in Young's modulus and 74.1% increase in the tensile stress for the BA‐a/HS composite containing 25 wt% HS particles. Meanwhile, the impact strength of the composites was elevated, and a maximum of 207% increase in impact strength was observed without sacrificing other properties of the matrix. Additionally, finite element analysis was carried out on a cantilever beam designed in CATIA V5 with the properties of neat BA‐a and HS filled composites. The stress analysis was observed on different HS filled composites, showing better results for HS filled composites as compared to neat polymer. [ABSTRACT FROM AUTHOR]

A novel autocatalytic phthalonitrile monomer [4,4′‐(((((oxy‐bis [4,1‐phenylene]) bis (azanediyl)) bis (methylene)) bis (2‐methoxy‐4,1‐phenylene)) bis (oxy)) diphthalonitrile, OPD] is obtained by nucleophilic substitution of 4‐nitro‐phthalonitrile and bisphenol compound [4,4′‐(((oxy bis [4,1‐phenylene]) bis (azanylylidene)) bis (methanylylidene)) bis (2‐methoxyphenol)]. Bisphenol compound is a reductant with secondary amine groups of Schiff base derived from the reaction of vanillin and 4,4′‐diaminodiphenylether. The OPD monomer has a self‐catalytic polymerizing reaction. OPD monomer has good processability, and the processing window was 130°C. Moreover, OPD polymer [poly(OPD)] shows higher glass‐transition temperature (345°C). The 5% and 10% thermal decomposition temperatures of poly(OPD) and char yield at 800°C are 407, 451°C, and 69%, respectively. To further improve the properties of poly(OPD), the OPD monomer was modified by multi‐functional fluorene‐based benzoxazine monomers (MFFB) due to their excellent reaction activities. The results showed that OPD/MFFB systems had high reaction activities. The similar thermal stabilities between OPD and MFFB can give stable and excellent thermal stability to the poly(OPD/MFFB). Compared with poly(OPD), the Tg values of poly(OPD/MFFB) were significantly increased, and their stiffness values were reduced. The tensile, flexural, and impact properties for poly(OPD/MFFB) were improved significantly. [ABSTRACT FROM AUTHOR]

In the current study, three different curing kinetics models were used to analyze the curing kinetics of hyperbranched benzoxazine (HB‐PED230) and monofunctional benzoxazine (P‐a) modified cyanate ester (CE) resin by non‐isothermal differential scanning calorimeter. Moreover, the effects of two benzoxazines on the copolymerization behavior, thermal stability, and mechanical properties of CE resin were studied. Compared with the P‐a modified CE resin, HB‐PED230 greatly reduces the curing temperature of the copolymer, while improving the bending strength and impact strength. The curing temperature of HB‐PED230 modified CE resin was 79°C lower than neat CE resin, while the CE/P‐a blended resin only reduce 48°C. As the amount of HB‐PED230 increased, the flexural strength and flexural modulus of the copolymers were improved. Surprisingly, when 7 wt% of HB‐PED230 was added, the impact strength of the copolymer was increased by 177.6%, implying that the toughness of CE resin had been greatly improved. Moreover, the fracture morphology of the copolymers was observed by scanning electron microscope. In summary, a small amount of HB‐PED230 blending can effectively improve the overall performance of CE resin. [ABSTRACT FROM AUTHOR]

The growing need for high thermal and mechanical resistant lightweight syntactic foams demands the designing of new materials. Herein, we report the successful fabrication of lightweight and high thermal resistance syntactic foams with excellent thermal and good mechanical properties. For this end, 10–50 wt% hollow glass microsphere (HGMS) containing polybenzoxazine based syntactic foams were prepared by using bisphenol‐A‐aniline (BA‐a) and phenol‐diaminodiphenylmethane (P‐ddm) benzoxazine via curing at 10 MPa compression molding. The curing behavior, tensile, flexural, compressive, and impact strength, thermal properties, and fracture morphology of the syntactic foams were studied by DSC, universal material testing machine, and drop hammer impact testing machine, TGA, and SEM, respectively. The curing temperatures of BA‐a and P‐ddm benzoxazine resins were slightly increased after blending the HGMS. The highest decline (59%) in the density and highest void contains (13.17%) was recorded for the poly(P‐ddm/HGMS50) sample. The excellent specific mechanical properties of the syntactic foams were observed on the 30 wt% HGMS loading. The thermal conductivity of the foams was gradually decreased and the lowest values of 0.106 and 0.0985 W/m.K were observed for poly(BA‐a/HMGS50) and poly(P‐ddm/HGMS50) sample, respectively. Furthermore, a gradual improvement in the thermal properties was observed as the loading of HGMS increased. [ABSTRACT FROM AUTHOR]

Spider silk is a natural polymeric fiber with high tensile strength, toughness, and has distinct thermal, optical, and biocompatible properties. The mechanical properties of spider silk are ascribed to its hierarchical structure, including primary and secondary structures of the spidroins (spider silk proteins), the nanofibril, the "core–shell", and the "nano‐fishnet" structures. In addition, spider silk also exhibits remarkable properties regarding humidity/water response, water collection, light transmission, thermal conductance, and shape‐memory effect. This motivates researchers to prepare artificial functional fibers mimicking spider silk. In this review, the authors summarize the study of the structure and properties of natural spider silk, and the biomimetic preparation of artificial fibers from different types of molecules and polymers by taking some examples of artificial fibers exhibiting these interesting properties. In conclusion, biomimetic studies have yielded several noteworthy findings in artificial fibers with different functions, and this review aims to provide indications for biomimetic studies of functional fibers that approach and exceed the properties of natural spider silk. [ABSTRACT FROM AUTHOR]

According to the literature review, microbial degradation of polyethylene terephthalate by PETases has been detected effective and eco‐friendly. However, the number of microorganisms capable of such feats is limited with some undesirable bioprospecting results. BTA‐hydrolase has been already reported capable of degrading polyethylene terephthalate. Therefore, mutation by in silico site‐directed mutagenesis means to introduce current isomer of PETase for polyethylene terephthalate degradative capability as a better approach to resolve this issue. This study aimed to use in silico site‐directed mutagenesis to convert a carboxylesterase from Archaeoglobus fulgidus to BTA‐hydrolase from Thermobifida fusca by replacing six amino acids in specific locations. This work was followed by molecular docking analysis with polyethylene terephthalate and polypropylene to compare their interactions. The best‐docked enzyme‐substrate complex was further subjected to molecular dynamics simulation to gauge the binding quality of the BTA‐hydrolase, wild‐type and mutant‐carboxylesterase with only polyethylene terephthalate as a substrate. Results of molecular docking revealed lowest binding energy for the wild‐type carboxylesterase‐polypropylene complex (‐7.5 kcal/mol). The root‐mean‐square deviation value was observed stable for BTA‐hydrolase. Meanwhile, root‐mean‐square fluctuation was assessed with higher fluctuation for the mutated residue Lys178. Consequently, the Rg value for BTA‐hydrolase‐ligand complex (∼1.68 nm) was the lowest compared to the mutant and wild‐type carboxylesterase. The collective data conveyed that mutations imparted a minimal change in the ability of the mutant carboxylesterase to bind to polyethylene terephthalate. [ABSTRACT FROM AUTHOR]

In this paper, we explore the global dynamical characteristics, boundedness, and rate of convergence of certain higher-order discrete systems of difference equations. More precisely, it is proved that for all involved respective parameters, discrete systems have a trivial fixed point. We have studied local and global dynamical characteristics at trivial fixed point and proved that trivial fixed point of the discrete systems is globally stable under respective definite parametric conditions. We have also studied boundedness and rate of convergence for under consideration discrete systems. Finally, theoretical results are confirmed numerically. Our findings in this paper are considerably extended and improve existing results in the literature. [ABSTRACT FROM AUTHOR]

In this work, we derive the solution formulas and study their behaviors for the difference equations x n + 1 = α x n x n − 3 / − β x n − 3 + γ x n − 2 , n ∈ ℕ 0 and x n + 1 = α x n x n − 3 / β x n − 3 − γ x n − 2 , n ∈ ℕ 0 with real initials and positive parameters. We show that there exist periodic solutions for the second equation under certain conditions when β 2 < 4 α γ. Finally, we give some illustrative examples. [ABSTRACT FROM AUTHOR]

In the current study, 1 wt%, NaOH treated pine cone (ATPC) particles composites with bisphenol‐A aniline based benzoxazine (BA‐a) matrix were prepared by isothermal compression method. Ultimate impacts of ATPC reinforcement on the thermomechanical, tensile, flexural, and impact properties of the composites were studied by using a dynamic mechanical analyzer (DMA), a Universal testing machine, and a Tinius‐Olsen impact device, respectively. The thermal stability of ATPC particles was remarkably increased, TGA confirmed that particles will not be degraded during the curing. The DMA results of 30 wt% ATPC reinforced composites confirmed that the glass transition temperature, storage modulus, and loss modulus were 22°C, 2510, and 250 MPa higher than the neat matrix, respectively. In addition, the impact strength of the 30 wt% ATPC reinforced composites was nearly 3 times higher than the neat matrix, which confirmed that the matrix's brittleness is reduced, similar observation was confirmed by the Brostow and coworkers empirical model. Moreover, a gradual rise in the tensile and flexural properties was also recorded. We can easily conclude from the studied parameters that the ATPC particles can be used as a sustainable agro‐waste in polymeric composites. [ABSTRACT FROM AUTHOR]

In this paper, we explore local stability, attractor, periodicity character, and boundedness solutions of the second-order nonlinear difference equation. Finally, obtained results are verified numerically. [ABSTRACT FROM AUTHOR]

In this article, 9, 9‐bis (4‐aminophenyl)‐2, 7‐dihydroxy‐fluorene (BADHF) was synthesized using methylsulfonic acid as catalyzer by direct condensation. Two kinds of novel multifunctional benzoxazine monomers containing fluorenyl groups and hydroxyl groups (MB‐FH) were obtained from the chemical reaction of BADHF, salicylaldehyde, paraformaldehyde, and ethanolamine (or diethyleneglycolamine) through the adoption of o‐hydroxy‐benzylamine method and one‐step Mannich condensation reaction method. In the traditional three‐step synthesis method, the double bond reduction process took 8–12 h, but in this article, it only took 15 min. The structures of MB‐FH monomers and their intermediates were characterized by Fourier transform infrared spectroscopy (FTIR), 1H nuclear magnetic resonance (1H NMR). The curing behaviors, curing kinetics, and thermal properties of MB‐FH monomers were tested by using a dynamic rheometer, differential scanning calorimeter (DSC), FTIR, dynamic mechanical analysis (DMA), and thermogravimetric analyzer (TGA). The curing induction time can be apparently shortened by the introduction of hydroxyl groups into benzoxazine monomers, and it can catalyze the ring‐opening polymerization of oxazine rings at lower temperatures, and improve the interaction of hydrogen bonds in the structure of polybenzoxazine. [ABSTRACT FROM AUTHOR]

Novel quinoxaline‐based trismaleimide (2,3‐di[3‐maleimido]phenyl‐6‐ maleimidoquinoxaline, namely TQMI) and its polymer alloys with 3‐phenyl‐3,4‐dihydro‐2H‐1,3‐benzoxazine (P‐a) were successfully prepared and characterized. Differential scanning calorimetry investigation of TQMI exhibited distinct double exothermic peaks, which implied that the curing behavior of different type of maleimide group was discrepant. The curing temperature of P‐a/TQMI prepolymers was lower than that of both neat TQMI and P‐a monomer. The temperatures at 5% (T5) and 10% (T10) weight loss and the char yield (Yc) of cured TQMI at 800°C reached 513°C, 524°C, and 63.5%, respectively, which were much higher than the record of traditional 4,4′‐bismaleimideodiphenylmethane (BMDPM) resin as well as most of other reported bismaleimide resins. Moreover, the addition of TQMI enhanced thermal stability, glass transition temperature (Tg), and limiting oxygen index of benzoxazine resin dramatically. Attractively, the Tg value of P‐a/TQMI copolymer at 30 wt% TQMI loadings was approximately 20°C higher than that of P‐a/BMDPM copolymer owing to the bulky quinoxaline group. [ABSTRACT FROM AUTHOR]

A high performance copolymer was prepared by using epoxy (EP) resin as matrix and 3,10,17,24‐tetra‐aminoethoxy lead phthalocyanine (APbPc) as additive with dicyandiamide as curing agent. Fourier‐transform infrared spectroscopy, dynamic mechanical analysis (DMA), differential scanning calorimetric analysis (DSC), and thermogravimetric analysis (TGA) were used to study the curing behavior, curing kinetics, dynamic mechanical properties, impact and tensile strength, and thermal stability of EP/APbPc blends. The experimental results show that APbPc, as a synergistic curing agent, can effectively reduce the curing temperature of epoxy resin. The curing kinetics of the copolymer was investigated by non‐isothermal DSC to determine kinetic data and measurement of the activation energy. DMA, impact, and tensile strength tests proved that phthalocyanine can significantly improve the toughness and stiffness of epoxy resin. Highest values were seen on the 20 wt% loading of APbPc in the copolymers, energy storage modulus, and impact strength increased respectively 388.46 MPa and 3.6 kJ/m2, Tg decreased 19.46°C. TGA curves indicated that the cured copolymers also exhibit excellent thermal properties. [ABSTRACT FROM AUTHOR]

We explore the local dynamics, N‐S bifurcation, and hybrid control in a discrete‐time Lotka‐Volterra predator‐prey model in R+2. It is shown that ∀ parametric values, model has two boundary equilibria: P00(0,0) and Px0(1,0), and a unique positive equilibrium point: Pxy+dc,rc−dbc if c>d. We explored the local dynamics along with different topological classifications about equilibria: P00(0,0), Px0(1,0), and Pxy+dc,rc−dbc of the model. It is proved that model cannot undergo any bifurcation about P00(0,0) and Px0(1,0) but it undergoes an N‐S bifurcation when parameters vary in a small neighborhood of Pxy+dc,rc−dbc by using a center manifold theorem and bifurcation theory and meanwhile, invariant close curves appears. The appearance of these curves implies that there exist a periodic or quasiperiodic oscillations between predator and prey populations. Further, theoretical results are verified numerically. Finally, the hybrid control strategy is applied to control N‐S bifurcation in the discrete‐time model. [ABSTRACT FROM AUTHOR]

We study the dynamical properties about fixed points, the existence of prime period and periodic points, and transcritical bifurcation of a one‐dimensional laser model in R+. For the special case, we explore the global dynamics about fixed points, boundedness of positive solution, construction of invariant rectangle, existence of prime period‐2 solution, construction of forbidden set, the existence of a prime period and periodic points, and transcritical bifurcation of the discrete‐time laser model. Finally, theoretical results are illustrated using numerical simulations. [ABSTRACT FROM AUTHOR]

Environmental and technical issues associated with hydraulic fracturing fluid leak‐off and its low recovery in clay‐rich shale reservoirs has challenged the energy sector. One of the main hypothesized mechanisms for the uptake of fracturing fluid is fluid imbibition due to capillary forces that are a strong function of the rock's wettability. However, shale wettability estimated by contact angle and spontaneous imbibition experiments are highly inconsistent throughout the literature. It is therefore critical to shed light on the possible reasons for such discrepancies and identify the superior technique. In order to characterize the physical processes from microscale to macroscale, the contact angles and spontaneous imbibition characteristics of shale samples were measured using aqueous ionic solutions (NaCl, KCl, CaCl2, and MgCl2) at different concentrations (0, 0.1, and 0.5 M) and oil (Soltrol‐130). The internal structure of the samples exposed to deionized water was imaged by three‐dimensional X‐ray micro‐computed tomography before and after spontaneous imbibition at both unconfined and confined stress states. Additionally, the structure of all samples exposed to each ionic solution was analyzed via environmental scanning electron microscopy. Experimental observations were further substantiated by combining digital image correlation with Poisson‐Boltzmann analysis to assess the hydration‐induced strains. It was shown that while spontaneous imbibition is a more realistic measurement for liquids, results obtained under unconfined condition can be highly biased due to additional forces acting (e.g., osmotic or hydration forces) and also potential microstructural alterations. Thus, spontaneous imbibition measured under reservoir stress condition is strongly recommended for shale wettability estimation. Key Points: Imbibition‐based wettability is only reliable under reservoir stress condition that prevents bias due to microstructural changesChemistry‐driven differences between imbibed and in situ liquids directly influence the liquid uptake leading to wettability judgment biasThe Poisson‐Boltzmann theory is used to explain the experimental observations [ABSTRACT FROM AUTHOR]

This article, titled "Outside Back Cover: Volume 4 Issue 6" from the journal SmartMat, discusses the potential applications of artificial spider silk and functional gel fibers in various technological and industrial sectors. The authors highlight the high strength and toughness of spider silk and the interest in mimicking its material, structure, and spinning process to create artificial fibers. The article summarizes recent developments in this field and suggests potential uses in areas such as biomedical, manufacturing, artificial muscles, sensing, and smart fibers. The authors of the article are Abdul Qadeer Khan, Muhammad Shafiq, Jiatian Li, Kaiqing Yu, Zunfeng Liu, Xiang Zhou, and Meifang Zhu. [Extracted from the article]

This work relates for the first time ever the use of natural fibers to reinforce the high performance phthalonitrile resins. The excellent thermal stability of the basalt fibers (BFs) allows them to be the only natural fibers resisting the high curing temperatures of the phthalonitrile resins. Based on this promising combination, high performance polymer composites were prepared and their performances were scrutinized in terms of mechanical properties and nuclear shielding efficiency. The BFs which initially underwent a silane surface modification provided materials with metal equivalent tensile and flexural properties. For instance, the composite containing 15 plies of treated fibers achieved the tensile and flexural strengths of 700 and 780 MPa, respectively. Additionally, the same composite stopped 36% of the incident highly ionizing gamma rays. Meanwhile, morphological investigations further confirmed the enhancement seen in the mechanical properties. Overall, the studied composites can be used as advanced materials in extremely exigent applications. POLYM. COMPOS., 40:E912–E919, 2019. © 2018 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

A new kind of nanocomposites was prepared from a high performance phthalonitrile resin and Ti3SiC2 MAX phase ceramic nanoparticles. The synergistic combination of both phases led to nanocomposites with improved thermal and mechanical properties. For instance, the thermal conductivity and tensile properties of the neat resin were highly enhanced on adding more nanofillers contents. Moreover, the phthalonitrile resin toughness was enhanced by 123% at the maximum nanoparticles loading of 15 vol.%. The experimental investigations were also compared with predictions from Series, Halpin‐Tsai, and Kerner models and a full discussion was provided. A high resolution transmission electron microscope confirmed the ability of the MAX phase to create a conductive network, especially at high nanofillers amounts. SEM analyses of the tensile fractured surfaces revealed positive changes in the morphology, such as an increase in the roughness and amount of hackling as well as the formation of multiple micro‐cracks. The MAX phase also enhanced the thermal stability, stiffness, and glass transition temperature of the neat resin. This work confirms the superiority of the MAX phase ceramics over the traditional ones in enhancing the properties of the phthalonitrile resin and opens the way for further research in the field. POLYM. COMPOS., 39:3705–3711, 2018. © 2017 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

ABSTRACT: A new high‐performance copolymer was successfully obtained via concerted catalysis polymerization of mono‐functional benzoxazine (P‐a) and self‐promoted 4‐aminophenoxy phthalonitrile (4‐APN) monomers. The FTIR and DSC curves of the P‐a/4‐APN in different blend ratios suggested that the monomer blends can be completely cured without the addition of curing additive. The P‐a/4‐APN copolymers were cured at relatively lower curing temperatures and time. The TGA curves revealed that the P‐a/4‐APN copolymers have good thermal stability in terms of T5, T10, and char yield. A gradual increase in the glass transition temperature (Tg) values and decline were seen in the storage modulus as the loading of 4‐APN was increased from 10 to 30 wt % in the copolymer. The SEM analyses showed that copolymer's fracture surface is dendritic, showing the stress has been dispersed to a certain extent. The study revealed that the poly(P‐a/4‐APN) copolymer have much better thermal stabilities than the poly(P‐a), and the prepared copolymer can be used as a high‐performance thermosetting resin. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46578. [ABSTRACT FROM AUTHOR]

This present article investigates the effect of silane‐treated basalt fibers (TBFs) on the morphological, mechanical and thermal properties of cyanate ester/benzoxazine (CE/BOZ) resin composites. The characterization was made using a scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), flexural test, impact strength (IS) test, microhardness test, dynamic scanning calorimetry, and thermogravimetric analysis. The mechanical test results inferred the distinctive improvements in the values of the flexural strength and modulus, IS, and microhardness of the CE/BOZ composites. The thermal stabilities in terms of the Tg, T5%, T10%, and THRI were appreciably improved and were higher than those of the pure CE/BOZ resin. Data from the SEM and FTIR tests ascertained the good dispersion and adhesion between the TBFs and the resin matrix, which might be behind the significant enhancement in the ultimate performances of the composites, with respect to the distinguished properties of BFs. [ABSTRACT FROM AUTHOR]

In this paper, stability and bifurcation of a two-dimensional ratio-dependence predator-prey model has been studied in the close first quadrant [ABSTRACT FROM AUTHOR]

Pyrotechnics are used to produce some special effects in various military and civilian applications. High temperatures and elevated humidity levels influence the thermal decomposition and kinetic behaviour of pyrotechnics. The present work describes the effect of ageing on SR-562 military pyrotechnic composition. The composition contains magnesium, sodium nitrate and calcium oxalate and it is used as a flare. The composition was aged for 30 days at a temperature of 70 °C and relative humidity (RH) of 70%. The experimental results show noteworthy variations in the thermal cum kinetic behaviour as well as in the morphology of the aged composition. Activation energy of the aged composition decreased to 189 kJ mol−1 from 239 kJ mol−1 for the fresh composition. Thermal decomposition temperature was found to increase by 51 °C after the ageing. X-ray diffraction results confirm the presence of magnesium hydroxide in the aged composition showing that some of the magnesium reacted with water vapours at high temperatures. Some micro sized cracks have been seen in the scanning electron microscopy micrographs of the aged composition. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Khan and Qureshi explored that positive solution of the system is bounded, and moreover, fixed point HT ht is globally stable if HT ht . [Extracted from the article]

Graphite was exfoliated to graphene by tip sonic using sodium cholate as a surfactant in the presence of Millipore water as a medium. The use of water as a solvent for exfoliation purposes is very important due to its environmentally friendly nature and almost no cost, contrary to organic media. Two different concentration ratios of surfactants are used in the present work. As a result, graphene dispersions with two different concentrations of 5 mg/ml and about 7 mg/ml respectively were obtained in aqueous media. It was observed that the optimum concentration of surfactant has an effective role in the exfoliation of graphite to graphene. Concentrations of graphene dispersions were studied through UV spectroscopy, while Raman spectroscopy, Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) were used to study the quality of the exfoliated graphene flakes. [ABSTRACT FROM AUTHOR]

The bisphthalonitrile (PN) thermosets series (poly(Baph), poly(Bafph), and poly(Bzph)) were prepared and subjected to 100 and 500 kGy γ‐ray irradiation dose from cobalt‐60 (60Co) as a source. The main objective of this present study was to investigate the effects of gamma irradiation on the chemical structure, thermomechanical, mechanical, and thermal stabilities, which were studied by using a Fourier transform infrared (FTIR), dynamic mechanical analysis, bending test, and thermogravimetric analysis, respectively. The PN resins characteristics bands, namely, nitrile, triazine ring, and phthalocyanine, were not affected on γ‐ray irradiation. However, remarkable changes were observed in the chemical structures of benzene, alkyl and CF3, which indeed slightly declined the thermal stabilities, thermomechanical and flexural properties. The decrease in properties could be ascribed to the scission of molecular chains and rupture of chemical bonds of PN resin as confirmed by the FTIR. The poly(Bafph) showed a maximum decline in the thermal stabilities and mechanical properties due to the existence of CF3 in the polymer skeleton, which could not be crosslinked again once scission occurs under radiation. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48313. [ABSTRACT FROM AUTHOR]

The cardanol‐based phthalonitrile (PN) monomer was successfully produced via the nucleophilic substitution reaction of cardanol with 4‐nitrophthalonitrile in potassium carbonate media. The conventional methods were employed to predict the chemical structure. The influence of long alkyl chains of cardanol was observed on the thermomechanical properties, recorded values were much below than the poly(Baph) standards. However, the thermal stabilities were recorded in good agreement to PN resin values. Furthermore, the 100 kGy dose of Co60 irradiation does not show any remarkable changes in the studied properties. The copolymers from P‐a benzoxazine and cardanol‐based PN (CPN) on the different wt % blending were prepared. The curing behavior and mechanism of the monomer blends were analyzed. The curing of CPN was improved in the presence of active hydrogen produced from the P‐a polymerization. The Tg and thermal properties of the copolymer were much better than the neat poly(P‐a). © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47505. [ABSTRACT FROM AUTHOR]