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Research examining the antecedents of recalls, instead of their consequences, is relatively sparse and has not considered whether firms' likelihood to recall products is influenced by legal changes that could induce managerial opportunism, such as those reducing shareholder litigation risk. To examine this question, the authors exploit the staggered adoption of universal demand (UD) laws across several U.S. states as a quasi-natural experiment. UD laws aim to prevent frivolous litigation from disrupting a firm's normal business operations by making it more difficult for shareholders to sue managers for neglecting their fiduciary duties and hold them personally liable. Although UD laws are well-intended, the reduced threat of shareholder litigation disciplining a firm's managers could have unintended negative consequences. Indeed, using a difference-in-differences analysis, the authors find that following the adoption of UD laws, affected firms become less likely to recall products. This effect is weaker in the presence of organizational mechanisms constraining managers' self-interest-seeking behavior, such as a corporate culture focused on customer needs and interests or the exercise of normative control through monitoring by institutional investors. The authors do not find support for a potential alternative explanation of operational improvement and therefore higher product quality driving their findings. [ABSTRACT FROM AUTHOR]

Atom-to-atom maps (AAMs) are bijections that establish the correspondence of reactant and product atoms across chemical reactions. They capture crucial features of the reaction mechanism and thus play a central role in modeling chemistry at the level of graph transformations. AAMs are equivalent to so-called "imaginary transition state" (ITS) graphs, making it possible to reduce tasks such as the computational comparison of AAMs to testing graph isomorphisms. In many application scenarios, nonetheless, only partial information is available, i.e., only partial maps or, equivalently, only subgraphs of the ITS graphs, are known. Here, we investigate whether and how, and to what extent, such partial chemical data can be completed and compared. The focus of this contribution is entirely on the development of a solid mathematical foundation for the analysis of partial AAMs and their associated partial ITS graphs. [ABSTRACT FROM AUTHOR]

Purpose: Reaction databases are a key resource for a wide variety of applications in computational chemistry and biochemistry, including Computer-aided Synthesis Planning (CASP) and the large-scale analysis of metabolic networks. The full potential of these resources can only be realized if datasets are accurate and complete. Missing co-reactants and co-products, i.e., unbalanced reactions, however, are the rule rather than the exception. The curation and correction of such incomplete entries is thus an urgent need. Methods: The SynRBL framework addresses this issue with a dual-strategy: a rule-based method for non-carbon compounds, using atomic symbols and counts for prediction, alongside a Maximum Common Subgraph (MCS)-based technique for carbon compounds, aimed at aligning reactants and products to infer missing entities. Results: The rule-based method exceeded 99% accuracy, while MCS-based accuracy varied from 81.19 to 99.33%, depending on reaction properties. Furthermore, an applicability domain and a machine learning scoring function were devised to quantify prediction confidence. The overall efficacy of this framework was delineated through its success rate and accuracy metrics, which spanned from 89.83 to 99.75% and 90.85 to 99.05%, respectively. Conclusion: The SynRBL framework offers a novel solution for recalibrating chemical reactions, significantly enhancing reaction completeness. With rigorous validation, it achieved groundbreaking accuracy in reaction rebalancing. This sets the stage for future improvement in particular of atom-atom mapping techniques as well as of downstream tasks such as automated synthesis planning. Scientific Contribution: SynRBL features a novel computational approach to correcting unbalanced entries in chemical reaction databases. By combining heuristic rules for inferring non-carbon compounds and common subgraph searches to address carbon unbalance, SynRBL successfully addresses most instances of this problem, which affects the majority of data in most large-scale resources. Compared to alternative solutions, SynRBL achieves a dramatic increase in both success rate and accurary, and provides the first freely available open source solution for this problem. [ABSTRACT FROM AUTHOR]

With the continuous increase in ship size combined with the generally slower increase in the sizes of waterways, the need for the prediction of ship maneuvering in shallow waterways continues to attract attention from the international scientific community. Ship behavior in shallow water is relevant in seabed effects that result in changing the hydrodynamic forces acting on a ship. In this study, the maneuvering characteristics of a container ship with four degrees of freedom in shallow water are analyzed. The Reynolds-Averaged Navier Stokes approach in Ansys Fluent code is used to produce the maneuvering coefficients through the simulations of forward running, static drift, static heel, circular motion, the combined motions, and the pure roll motion of the KRISO container ship. The maneuvering characteristics of the ship are estimated for evaluating the ship behaviors in shallow-water conditions. The obtained results show that the roll has a significant decrease and the ship's turning diameter has a significant increase when the ship operates in a shallow waterway. The predicted maneuvering characteristics of the ship are in good agreement with those of free-running model tests, indicating that the numerical simulation based on the Computational Fluid Dynamics method has good capability to predict the maneuvering derivatives and the four-DOF ship maneuvering motion in shallow water as well. [ABSTRACT FROM AUTHOR]

This study presents the predicted hydrodynamic characteristics of different rudder plane configurations on the stern of a full-scale submarine in deep water, which are obtained using the Reynolds-Averaged Navier–Stokes method in Ansys Fluent Solver. First, the results obtained for the X-rudder plane configuration are verified according to previous numerical and experimental results in order to assess the accuracy of the simulation procedure. The X-rudder plane, Y-rudder plane, and Cross-rudder plane configurations in deep water with deflection angles ranging from −21 degrees to +21 degrees are then simulated. Next, the hydrodynamic forces and moments of the Cross-plane, X-plane, and Y-plane rudder configurations obtained through simulation are analyzed using Taylor's expansion to estimate the hydrodynamic coefficients. The obtained results demonstrate that the X-force of the X-plane rudder configuration is larger than the corresponding forces acting on the Cross-plane rudder and Y-plane rudder configurations. Meanwhile, the Y-force and Z-force of the X-plane rudder configuration are significantly greater than the corresponding forces of the left configurations. The same tendency can be seen in the moment of the X-plane rudder about the y- and z-axes. However, the roll moment induced by the Y-plane and Cross-plane rudder configurations is significantly larger than that under the X-plane rudder configuration. [ABSTRACT FROM AUTHOR]

Purpose: This paper examines how a firm's hierarchical complexity, which is determined by the way it organizes its subsidiaries across the hierarchical levels, can impact its stock price crash risk. Design/methodology/approach: The authors employ a measure of hierarchical complexity that captures the depth and breadth of how subsidiaries are organized within a firm. This measure is calculated using information about firms' subsidiaries extracted from the Bureau van Dijk (BvD) database that allows the authors to construct each firm's hierarchical structure. The data sample includes 2,461 USA firms for the period from 2012 to 2017 (11,006 firm-year observations). Univariate tests and panel regression are used for the main analysis. Two-stage-least-squares (2SLS) instrumental variable regression and various other tests are employed for robustness check. Findings: The results show a positive relationship between hierarchical complexity and stock price crash risk. This relationship is amplified in firms with a greater number of subsidiaries that are hierarchically distanced from the parent company as well as in firms with a greater number of foreign subsidiaries in countries with weaker rule of law. Originality/value: This paper is the first to investigate the impact hierarchical complexity has on crash risk. The results highlight the role that a firm's organizational structure can have on asset pricing behavior. [ABSTRACT FROM AUTHOR]

An artificial recharge test was performed in Ho Chi Minh City, Vietnam to see the geochemical response of a saline coastal plain aquifer to the injected rainwater. The results show that the rainwater injection can cause mobilization of heavy metals due to pyrite oxidation and this phenomenon can persist even after the full recovery of the injected water. In this study, a 30-m-deep well was installed in a confined aquifer. Pyrite framboids were observed in the sediment samples collected during the well drilling. A total of 400 L rainwater was injected into the well for 70 min. After waiting 63 h, the well was extracted at a pump speed of 2.7 L/min and the chemistry of the pumped groundwater was monitored for 10 h. The groundwater showed geochemical features close to rainwater at the early stage of pumping and gradually changed to those of the background waters, especially, in electrical conductivity and Cl− concentration, as the pumping proceeded. However, the groundwater pumped in the later stage showed much increased concentrations in SO42−, total iron (FeT), AsT, Ni, Mn and Zn relative to the calculated mixing concentrations due to pyrite oxidation even though NO3−, the pyrite oxidant, already had disappeared. It was revealed from the geochemical modeling that the persistent pyrite oxidation was the result of the reaction with ferrihydrite, which precipitated in pores of the sediment by the injection of aerated water. We believe our study is a good example showing the importance of careful design of the artificial recharge systems to avoid or minimize the geochemical disturbance of aquifer. [ABSTRACT FROM AUTHOR]

The combination of two dielectric-magnetic components in the same composite has been shown to significantly improve the effectiveness of electromagnetic (EM) shielding and microwave absorption (MWA) because they have both a combination of high dielectric and magnetic losses and good impedance matching. The novel Bi1/2(Na0.8K0.2)1/2TiO3/Fe3O4 (BNKT/Fe3O4) composite has been successfully synthesized by a two-step method with wide effective absorption bandwidth (EAB = 16 GHz) in the high-frequency (2-18 GHz). It was evident that the MWA efficiency of the BNKT/Fe3O4 composite has been significantly improved compared with pure Bi1/2(Na0.8K0.2)1/2TiO3 or Fe3O4 materials. In addition, the BNKT/Fe3O4 composite could achieve reflection loss (RL = -39.41 dB, ~99.99% at 10.16 GHz) with a sample thickness optimal (d = 4.7 mm). This work shows that the novel BNKT/Fe3O4 composite has excellent MWA properties, all contributing to a potential candidate in the electromagnetic wave absorption and shielding fields. [ABSTRACT FROM AUTHOR]

Among the recently discovered 2D intrinsic van der Waals (vdW) magnets, Fe3GeTe2 (FGT) has emerged as a strong candidate for spintronics applications, due to its high Curie temperature (130 – 220 K) and magnetic tunability in response to external stimuli (electrical field, light, strain). Theory predicts that the magnetism of FGT can be significantly modulated by an external strain. However, experimental evidence is needed to validate this prediction and understand the underlying mechanism of strain‐mediated vdW magnetism in this system. Here, the effects of pressure (0 – 20 GPa) are elucidated on the magnetic and structural properties of Fe3GeTe2 by means of synchrotron Mössbauer source spectroscopy, X‐ray powder diffraction and Raman spectroscopy over a wide temperature range of 10 – 290 K. A strong suppression of ferromagnetic ordering is observed with increasing pressure, and a paramagnetic ground state emerges when pressure exceeds a critical value, PPM ≈ 15 GPa. The anomalous pressure dependence of structural parameters and vibrational modes is observed at PC ≈ 7 GPa and attributed to an isostructural phase transformation. Density functional theory calculations complement these experimental findings. This study highlights pressure as a driving force for magnetic quantum criticality in layered vdW magnetic systems. [ABSTRACT FROM AUTHOR]

Aerodynamic drag reduction is required with new stringent constraints on pollutant emissions and fuel efficiency of ground vehicles. In this context, active flow control is a promising approach to achieve this target. This study focuses on applying different flow control strategies on the square-back Ahmed model to reduce aerodynamic drag. A steady blowing jet, a synthetic jet and an unsteady jet are located at the back edges of the model as flow control devices. A numerical study based on the 3D WMLES simulation was performed to evaluate the drag reduction capabilities of these devices at different operating conditions. The results showed that a maximum aerodynamic drag reduction of 26.51% was achieved when using a steady blowing jet, and 17.27% with an unsteady jet. In contrast, the effect of the synthetic jet on the aerodynamic drag of the model is solely at high control frequencies. [ABSTRACT FROM AUTHOR]

As the defining urban features of Hồ Chí Minh City, Việt Nam, the alleyway represents an important nexus of intervention for climate change adaptation as well as urban renovation to improve inhabitants' daily lives. This article aims to lay the theoretical groundwork for looking at the alley space as a concept belonging to structural-functional school in order to identify its features and functions with particular attention to its role in the context of climate change and rapid urbanization. The concept is examined through the study of the alley space via primary research consisting of a description of the alleyways in Gò Vấp District and interviews of inhabitants and users of these spaces on the condition of the alleyways. Additionally, secondary research on the renovation and adaptation of alleyways in other context was conducted in order to identify possible policy grafting to Vietnam. Results show that many alleyways have insufficient infrastructure, vegetation, and safety standards as shown through both observation and participants' responses. The planning of these spaces remain deficient in involving the local communities, especially when compared to international experience. It is concluded that the alley space is quintessential feature of the city's urban landscape but its adaptation to ongoing developmental pressures have been inadequate. Adapting these spaces to the modern context while incorporating community voices in planning and implementation is not only, it is essential to the survival of the city. [ABSTRACT FROM AUTHOR]

Purpose: Drawing on the conservation of resources theory, this study aims to apply a mixed-method to enrich the literature by investigating interrelationships among training, environmental triggers (environmental knowledge, awareness and concern) and employees' intention to carry out environmental activities. Design/methodology/approach: This research applied a mixed-method carried out in Vietnam. By using the time-lagged data, Study 1 (quantitative research) was employed to test hypotheses. With Study 2 (qualitative research), four in-depth interviews were conducted to gain insight into a few unexpected findings from Study 1. Findings: Study 1 indicates that environmental training is critical to directly boost not only the three environmental triggers but also employees' intention to engage in environmental activities. The findings further point out that environmental concern and awareness mediate the relationship between environmental training and employees' intention to engage in environmental activities. Unexpectedly, connections from environmental concern and awareness to employees' intentions were not moderated by environmental knowledge. The findings of Study 2 shed light on the role of environmental knowledge. Originality/value: Based on the conservation of resources and social exchange theories, the research contributes to the existing literature by providing a better understanding of how environmental training stimulates employees' intention to implement environmental activities. The findings may be helpful for managers to encourage employees to contribute to organizations' green objectives. [ABSTRACT FROM AUTHOR]

Controlling material structure and its electromagnetic properties, including complex permittivity and permeability, could enhance the microwave absorption performance of the material in terms of reflection loss and effective absorption bandwidth. In this study, La‐substituted barium hexaferrite, Ba3−xLaxCo2Fe24O41 (x = 0, 0.1, 0.3, and 0.5) compounds were successfully prepared using the solid‐state reaction method, and their corresponding microstructures, static magnetic properties, and electromagnetic features in 2–18 GHz were investigated. The doping of La content increased saturation magnetization, coercivity, and remnant magnetization. The Ba2.7La0.3Co2Fe24O41 epoxied sample with 3.5 mm thickness possessed an excellent microwave absorption of −47.3 dB at 3.52 GHz, and its corresponding effective absorption bandwidths were 3.75 GHz (2.25–6 GHz) and 0.57 GHz (17.43–18 GHz). It is shown that doping with various La concentrations on Ba3Co2Fe24O41 can be used as an effective technique to tune the performance of microwave absorbers based on barium hexaferrite. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to explore the intention–action relationship of small and medium-sized (SMEs) firms with knowledge capital that declare their intention to internationalize from their inception. Design/methodology/approach: The authors apply the theory of planned behavior and hand-collect a database of Chinese born globals, purely domestic firms and traditional exporting firms. The authors' hypothesis is that Chinese born globals [or young aspiring globals (YAGs)] will strive to acquire domestic and international patents at an early stage to institutionally protect their knowledge-capital via intellectual property rights as they enter the competitive global marketplace. Findings: The results confirm that knowledge-focused YAGs apply for patents at an earlier stage than purely domestic and traditional exporting firms. However, in the long run, these firms are neither demonstrating increased knowledge capital by being more innovative nor producing more valuable innovations than their counterparts. Originality/value: This study tests the intention–action relationship in the context of SMEs internationalization. It contributes to the internationalization literature by identifying the internationalization pattern of born globals (YAGs) from emerging markets and providing an explanation for what happens to these firms as they mature. [ABSTRACT FROM AUTHOR]

Anchoring on the Stimulus–Organism–Response (SOR) and Ability-Motivation-Opportunity (AMO) theories, this research aims to investigate the mechanism through which three green AMO components (i.e. green ability, green motivation, green opportunity) affect green electronic word-of-mouth (green eWOM). A mediation and moderation model that integrates the green AMO components with green attitudes and green eWOM was developed and then validated with data from 600 tourists in an emerging market. Multivariate data analysis reveals that the three green AMO components affect tourists' green eWOM directly and also indirectly via green attitudes. Moreover, green ability positively moderates the green motivation-green eWOM relationship. [ABSTRACT FROM AUTHOR]

An illustrated description of a new species of the free-living marine nematode, Daptonema paramonovi Phan Ke Long, Nguyen Dinh Tu et Gagarin sp. n., found in a mangrove forest in Vietnam, is given. In body size, D. paramonovi sp. n. is close to D. elongatum Gagarin et Nguyen Thi Thu 2008, D. communis Gagarin et Nguyen Vu Thanh 2014 and D. rectangulatum Pastor de Ward 1985, but shows a different shape of the pharyngostoma and a different structure of the gubernaculum. In the new species, the pharyngostoma is larger and consists of two departments. In the three species compared, the pharyngostoma is small and funnel-shaped. The male gubernaculum of the new species is in the form of a simple gutter. The male gubernacula of the species compared are complex, consisting of the main body and claw-shaped dorsal processes. [ABSTRACT FROM AUTHOR]

In this paper, we present a way to create fuzzy controller from LQR method by using ANFIS toolbox of Matlab. First, after proving the ability of stability of this SIMO system under LQR method in Matlab/Simulink, we create a fuzzy controller through ANFIS toolbox of Matlab. The data, which is used to train, is collected from responses of system under LQR controller. Also, we present a hardware platform of ball and beam system. Under this fuzzy controller, control quality of ball and beam is better than under LQR controller in both simulation and experiment. [ABSTRACT FROM AUTHOR]

The present work presented a synthesis of silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) using the aqueous extract of waste banana stem (WBS), Musa paradisiaca Linn. The reduction and formation of MNPs have been characterized by several analysis techniques such as X-ray diffraction (XRD), Fourier transmission infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM). The techniques showed that average particle size of WBS-AgNPs and WBS-AuNPs in crystalline nature was in ranges of 7–13 nm and 11–14 nm, respectively. The synthesized nanoparticles were used to evaluate antibacterial activity and catalysis. The WBS-AgNPs showed strong antibacterial activity against B. subtilis and E. coli. The largest zone of inhibition against B. subtilis (14.2 mm) and E. coli (9.3 mm) was found at concentrations of 4.0 ppm and 2.0 ppm, respectively. The excellent catalytic application of both the nanoparticles for the reduction of 4-nitrophenol was confirmed via study on their kinetics. The normalized kinetic constants (knor) of WBS-AgNPs and WBS-AuNPs were found to be 1.72 × 10–3 s−1 mg−1 and 2.45 × 10–3 s−1 mg−1, respectively. [ABSTRACT FROM AUTHOR]

We prepared Ba3−xYxCo2Fe24O41 (Y‐Co2Z, x = 0, 0.2, and 0.4) by the solid‐state reaction method. Y‐Co2Z and polyaniline (PANI) composites (named as Y‐P0, Y‐P2, and Y‐P4) were prepared by using the in‐situ polymerization method. The Y‐doping played an important role in the variation of lattice parameters, a and c. The combination of Y‐doping and PANI modified the magnetic properties of the composites, which could be observed by the changing of the saturation magnetization and coercivity. This combination had also affected the electromagnetic properties of composites through the measurements of complex permittivity and permeability. Using the transmission line theory, we calculated refection loss (RL) of composites with the variation thickness of 1.00–2.50 mm. Our composites tuned the minimum RL from the X band (RL = −29.6 dB at 11.4 GHz for Y‐P2) to Ku band (RL = −16.3 dB at 15.7 GHz for Y‐P4 and RL = −26.4 dB at 16.6 GHz for Y‐P4). For maximum effective bandwidth, our composites covered a huge range from the S and C bands (Y‐P0 with 3.9 GHz in the range of 3.4–7.3 GHz) through the X band (Y‐P2 with 3.9 GHz in the range of 9.0–12.9 GHz) to the Ku band (Y‐P4 with 4.0 GHz in the range of 13.8–17.8 GHz). Those properties proved that the composites could act as promising absorbers in the S, C, X, and Ku bands. [ABSTRACT FROM AUTHOR]

The electrostatic potential profile of a spherical soft particle is derived by solving the Poisson-Boltzmann equations on a spherical system both numerically and analytically. The soft particle is assumed to consist of an ion-permeable charged outer layer and a non-permeable charged core with constant charged density. The contribution of the core to the potential profile is calculated for different charges and dielectric constants. Our results show that the charged core heavily influences the local potential within the soft particle. By contrast, the potential distribution outside the particle in the salt solution is found to be weakly dependent on the core features. These findings are consistent with previous experiments showing the minor impact of the core of the MS2 virus on its overall electrical properties. Our studies also indicate that while a change in temperature from 290 K to 310 K only slightly varies the potential, the ionic strength in the range of 1-600 mM has a significant effect on the potential profile. Our studies would provide good understanding for experimental research in the field of biophysics and nanomedicine. [ABSTRACT FROM AUTHOR]

The radiative heat transfer between gold nanoparticle layers is presented using the coupled dipole method. Gold nanoparticles are modelled as effective electric and magnetic dipoles interacting via electromagnetic fluctuations. The effect of higher-order multipoles is implemented in the expression of electric polarizability to calculate the interactions at short distances. Our findings show that the near-field radiation reduces as the radius of the nanoparticles is increased. Also, the magnetic dipole contribution to the heat exchange becomes more important for larger particles. When one layer is displayed in parallel with respect to the other layer, the near-field heat transfer exhibits oscillatory-like features due to the influence of the individual nanostructures. Further details about the effect of the nanoparticles size are also discussed. [ABSTRACT FROM AUTHOR]

The van der Waals interaction between a lipid membrane and a substrate covered by a graphene sheet is investigated using the Lifshitz theory. The reflection coefficients are obtained for a layered planar system submerged in water. The dielectric response properties of the involved materials are also specified and discussed. Our calculations show that a graphene covered substrate can repel the biological membrane in water. This is attributed to the significant changes in the response properties of the system due to the monolayer graphene. It is also found that the van der Waals interaction is mostly dominated by the presence of graphene, while the role of the particular substrate is secondary. [ABSTRACT FROM AUTHOR]

We report magnetic properties and magnetocaloric (MC) effect in Fe90-xNixZr10 (x = 0, 5, 10, and 15) alloy ribbons prepared by rapid-quenching method. We found the Curie temperature (TC) of the alloy ribbons depends strongly on Ni-doping concentration (x) increasing from 245 K for (x = 0), through 306 K (for x = 5) up to TC = 403 (for x = 15). Also, the dependence of the maximum magnetic entropy change (|ΔSmax|) on Ni content was readily apparent. Indeed, for the x = 0 and 5 samples that have TC around room temperature, the |ΔSmax| values increment under magnetic field changes of 10, 20, and 40 kOe was found to be as high as 0.87, 1.76, and 3.04 J·kg-1·K-1 for x = 0, and 1.03, 1.90, and 3.26 J·kg-1·K-1 for x = 5, respectively. These values correspond to refrigerant capacity in the range of 86-334 J·kg-1 and are comparable to other known MC materials. High magnetocaloric performance in rare-earth-free non-expensive metallic alloys indicates that these materials could be competitive candidate for active magnetic refrigeration at room temperature. [ABSTRACT FROM AUTHOR]

This paper examines the effect time‐to‐maturity has on how sensitive futures prices are to news flows. Unscheduled daily news flows that relate to the underlying asset of a futures contract are related to the daily realized volatility of futures to calculate a price‐news sensitivity ratio. The observed pattern follows an inverted U‐shape relationship and has a bearing on whether the maturity effect will be noticeable in a futures contract. This paper also shows that by examining the peak‐to‐maturity of the price sensitivity to news pattern, it is possible to better identify which contracts are more likely to yield higher volatility. [ABSTRACT FROM AUTHOR]

We have systematically investigated the compositional dependence of the magnetic and magnetocaloric properties of La0.7-xPrxSr0.3MnO3 (LPSMO). Polycrystalline samples of LPSMO with 0.02 ≤ x ≤ 0.30 were prepared by a standard solid-state reaction method with phase purity and structure confirmed using x-ray diffraction. Temperature dependent magnetization measurements and Arrott analysis reveal second order ferromagnetic transitions in each sample with Curie temperature decreasing progressively with increasing Pr content from ∼350 K for x = 0.02 to ∼295 K for x = 0.30. Magnetic entropy change (ΔSM) was calculated by applying the thermodynamic Maxwell equation to a series of isothermal field dependent magnetization curves. In the sample with x = 0.30, the maximum value of -ΔSM reaches ∼2.08 J/kg K at 295 K for a field change of 1.5 T. Reduced Pr content corresponds to larger values of entropy change, reaching -ΔSM ∼2.79 J/kg K for the x = 0.02 doping. The refrigeration capacity for each composition reached sizable values of 33-48 J/kg for a small applied field of 1.5 T. [ABSTRACT FROM AUTHOR]

Having based on x-ray absorption spectroscopy, we point out structural phase separation in polycrystalline Zn1-xMnxO ceramics prepared by solid-state reaction. The samples are single phase in the wurtzite structure as x < 0.04. A Mn-concentration increase with x ≥ 0.04 results in the formation of a secondary phase of tetragonal ZnMn2O4 spinel. The feature of x-ray absorption spectra for the Mn K edge reveals an existence of Mn2+ and Mn3+ ions in Zn1-xMnxO, which are responsible for room-temperature paramagnetism. Particularly, when Mn content is increased, there is a chemical shift of the absorption edge toward higher energies, indicating an increase in concentration of Mn3+ ions. Fourier analyses for the spectra of extended x-ray absorption fine structure (EXAFS) shows up the substitution of Mn for Zn sites in the ZnO host lattice. The parameters related to the local structure have been determined and discussed in detail. [ABSTRACT FROM AUTHOR]

Polycrystalline BaTi1-xFexO3 ceramics have been prepared by conventional solid-state reaction. Their structural, optical and magnetic properties are then studied by means of x-ray diffraction (XRD), Raman scattering (RS) and absorption spectrometers, and a physical properties measurement system. Detailed analyses of XRD patterns and RS spectra reveal the phase separation of the tetragonal-hexagonal structure at a threshold concentration of x = 0.005. The increase in the Fe-doping content (x) leads to development of the hexagonal phase. Magnetic measurements prove that many BaTi1-xFexO3 samples exhibit the room-temperature ferromagnetic order, excepting the samples with x = 0.02-0.06. The ferromagnetism depends strongly on concentration of Fe impurities. The nature of this ferromagnetism is discussed by means of the results of structural analyses and optical absorption spectra. [ABSTRACT FROM AUTHOR]

We prepared Zn1-xMnxO nanorods by thermal diffusion. These samples were then studied the structural, optical, and magnetic properties. The structural analyses basing on x-ray diffraction and transmission electron microscope revealed the absence of Mn-related secondary phases. The study of photoluminescence spectra revealed the blueshift in the UV emission when the Mn doping concentration was increased, as a consequence of the extension of the band gap energy. Besides this situation, the increase in emission intensity associated with extrinsic defects at about 680 nm also took place. Concerning the Raman scattering spectra, apart from conventional phonon modes related to the ZnO wurtize-type structure, there were some additional modes introduced by the doping. Their origin was assessed carefully. Particularly, the shift in peak position of E2(high) toward low frequencies due to the increase in the Mn doping concentration could be explained well by means of the spatial correlation model. Magnetic measurements proved the samples with Mn concentrations above 1.15 at. % exhibiting the weak-ferromagnetic order at low temperatures. The nature of the ferromagnetism was discussed by means of the results of the structural and optical investigations. [ABSTRACT FROM AUTHOR]

Southern Vietnam is known as one of the most vulnerable areas to climate change in the world due to its low elevation and flat topography, heavy groundwater use, and dense population. This paper introduces hydrogeological conditions and critically reviews groundwater issues that southern Vietnam faces by summarizing previous literatures. Issues that this paper covers include groundwater use and associated phenomenon, acid sulfate soils, the occurrence of saline groundwaters, seawater intrusion, land subsidence, groundwater acidification, and groundwater contamination by nitrate, ammonium, and trace metals such as As, Fe, Mn, Al, Cd, and Pb. This paper shows that most of these issues are inter-related and essentially linked with the unique hydrogeological setting of the study area. However, many of these problems have also been triggered or aggravated by human activities that use water resources and land. Issues such as those of As contamination and groundwater acidification are connected with the aquifer characteristics that are generally confined and rich in organics and pyrite. However, groundwater salinization, acidification, groundwater level declining, land subsidence, and high heavy metal concentrations are in large part caused by human activities such as well installation and heavy groundwater abstraction. While previous studies have proposed artificial recharge as a promising means of mitigating groundwater issues in the study area, the development of techniques that help minimizing aquifer disturbances is also likely required. [ABSTRACT FROM AUTHOR]

The rigid polyurethane foams (RPUFs) filled with organoclay cloisite 20A and expandable graphite (EG) were prepared by the one-step expanding foam method. Flame behavior, mechanical properties, and thermal conductivity of the composites were investigated. The vertical burning test (UL-94V) and limiting oxygen index (LOI) showed that the flame retardancy was increased proportionally with the content of EG in PU composite. However, the presence of EG filler impaired the thermal insulation and the compressive strength of the composite. In this report, we proved that organoclay could improve the compressive strength, thermal insulation, and flame retardancy of EG/polyurethane composites. This work can contribute to the development of environment-friendly flame-retardant products for green growth. [ABSTRACT FROM AUTHOR]

In the present work, the influence of annealing on structure, electron spin resonance (ESR), and Raman scattering (RS) spectra of x at. % Mn-doped ZnO (x=4 and 8) ceramic compounds has been systematically investigated. The samples were annealed at temperatures (Tan) between 400 and 1000 °C for 12 h. The obtained results revealed the strong dependence of x-ray diffraction, ESR, and RS spectra on the annealing temperature Tan. Mn2+ ions did not substitute into Zn2+ sites in samples annealed in the range of 400–600 °C but started to substitute into Zn2+ sites for annealing temperatures Tan>600 °C. The results of this investigation provide further insights into the physical processes occurring in Mn-doped ZnO materials due to annealing. [ABSTRACT FROM AUTHOR]

Two new wide-bandgap conjugated copolymers, T-3MT and 2T-3MT, containing methyl-3-thiophenecarboxylate (3MT) as a weak accepting unit and indacenodithiophene (IDT) or indacenodithienothiophene (IDTT) as ladder-type donating units, were synthesized through Stille coupling polymerization. The effects of the IDT and IDTT units on the physical, optical, and electrochemical properties of these copolymers were investigated. Polymer solar cells (PSCs) were constructed using these new copolymers and different acceptor molecules for inter-comparative analysis of their performance. The PSCs bearing the as-cast active layers with 2,2′-((2Z,2′Z)-((4,4,9,9-tetrakis(4-hexylphenyl)-4,9-dihydro-s-indaceno[1,2-b:5,6-b′] dithiophene-2,7-diyl)bis(methanylylidene))bis(3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile (IM-IDT) displayed the highest PCEs of 3.78−3.96%, mainly owing to the predominant face-on orientation of blend film, and the relatively high open circuit voltage exceeding 1.0 V. [ABSTRACT FROM AUTHOR]

ABSTRACT: Two new random terpolymers containing 4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)benzo[1,2‐b:4,5‐b′]dithiophene (BDT) as a donating unit, methyl‐3‐thiophenecarboxylate (3MT) as a weak accepting unit, and the more electron‐deficient benzo[c][1,2,5]thiadiazole (BTz) or 5,5′‐bis(2‐ethylhexyl)‐4H,4′H‐1,1′‐bithieno[3,4‐c]pyrrole‐4,4′,6,6′(5H,5′H)‐tetraone (BiTPD) unit as a third monomer (respectively yielding 3MTB and 3MTT) were synthesized in order to achieve improved physical and optoelectronic properties relative to the 3MT‐Th copolymer bearing only BDT and 3MT. The UV–vis absorption spectra and optical bandgap energies of these terpolymers were broader and smaller than those of the 3MT‐Th copolymer. In thin films, the terpolymers displayed the face‐on polymer chain orientation, indicating that the BTz or BiTPD unit in the terpolymer backbones did not affect the molecular arrangement on the substrate. In comparison with 3MT‐Th‐based polymer solar cells (PSCs) as control devices, the PSCs employing blend films of these terpolymers as the donor and 2,2′‐[[6,6,12,12‐Tetrakis(4‐hexylphenyl)‐6,12‐dihydrodithieno[2,3‐d:2′,3′‐d′]‐s‐indaceno[1,2‐b:5,6‐b′]dithiophene‐2,8‐diyl]bis[methylidyne(3‐oxo‐1H‐indene‐2,1(3H)‐diylidene)]]bis[propanedinitrile] (ITIC) as the acceptor exhibited higher power conversion efficiencies (>8.0%) for the same device configuration. In addition, the 3MTB‐ and 3MTT‐based PSC devices displayed excellent shelf‐life even after aging for over 1000 h. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 1528–1535 [ABSTRACT FROM AUTHOR]

Abstract: Polycrystalline Ca2Fe2−xAlxO5 (x = 0‐1.4) samples were prepared by conventional solid‐state reactions. Their crystalline/electronic structures and magnetic properties were characterized in detail. Powder X‐ray diffraction analyses revealed that the samples crystallized in orthorhombic brownmillerite‐type structures with the occurrence of the Pcmn‐Ibm2 phase separation in the region between x = 0.4 and 0.6. The results obtained from analyzing Raman scattering and X‐ray‐absorption fine‐structure spectra also indicated this phase separation. Although x in Ca2Fe2−xAlxO5 varies in a wide range from 0 to 1.4, the +3 oxidation state of Fe remained almost unchanged. Magnetization measurements revealed that all Ca2Fe2−xAlxO5 samples have weak ferromagnetic order, and both the saturation magnetization and coercive force are dependent on the temperature, x, and structure phases. [ABSTRACT FROM AUTHOR]

In this work, we point out that the width and the nature of the magnetic phase transition, TC value, and as well as magnetocaloric effect in La0.7-xSmxCa0.3MnO3 compounds can be easily modified through Sm-doped into La-site. With an increasing Sm concentration, a systematic decrease in the magnetization, TC, and magnetic entropy change (ΔSm) are observed. The Arrott-plot proveds that the samples with x = 0 and 0.1 undergoing a first-order phase transition. Meanwhile, sample x = 0.2 undergoes a second-order phase transition, which exhibits a high value of the relative cooling power (81.5 J/kg at ΔH = 10 kOe). An analysis of the critical behavior based on the modified Arrott plots method has been done for sample x = 0.2. The results proved a coexistence of the long- and short-range interactions in La0.5Sm0.2Ca0.3MnO3 compound. [ABSTRACT FROM AUTHOR]

Abstract: This study reports the fabrication of a Petri dish patterned with cylindrical micro‐cavities that are produced using a one‐step solvent‐immersion phase‐separation process. The developed 3D honeycomb Petri dish is coated with a Au film through a sputtering method to be an efficient Au‐coated FTO‐free electrode for quantum‐dot‐sensitized solar cells. Due to the high specific active surface area of the electrode with the Au‐coated honeycomb structure, the energy conversion efficiency of devices that use this electrode is 5.2 % compared to 4.4 and 4.7 % by devices using an Au‐coated flat Petri dish and an Au‐coated FTO electrode, respectively. This design strategy offers excellent potential for the fabrication of highly efficient counter electrodes with FTO‐free substrates of flexible photovoltaic devices. [ABSTRACT FROM AUTHOR]

An illustrated description of the nematode Bolbolaimus obesus sp. n. from a mangrove forest of the Yen River estuary, Vietnam is given. Bolbolaimus obesus sp. n. is close to B. abebei Muthumbi et Vincx 1999 and B. bahari Muthumbi et Vincx 1999, but differs from both by the shorter body, strongly sclerotized body walls of the cheilostoma, a different position of the amphidial fovea, and longer gubernaculum. [ABSTRACT FROM AUTHOR]

La0.7Ca0.3Mn0.5Fe0.5O3(LCMFO) ceramic samples were prepared by conventional solid-state reaction. X-Ray diffraction investigations show that samples have orthorhombic space group Pnma (a = 5.447(2) Ǻ, b = 7.709(3) Ǻ, c = 5.467(3) Ǻ). During the neutron powder diffraction measurements of LCMFO in the temperature range of 10 ÷ 300 K the antiferromagnetic long-range ordering of G-type was seen. It has been established that 50% substitution of Mn/Fe leads to a complete suppression of the ferromagnetism in LCMFO samples. Investigations of temperature dependence of the magnetization, M(T), suggests the frustration of magnetic ground state and the existence of a spin-glass or a cluster-glass phase below the magnetic transition temperature close to 350 K. The temperature dependences of conductivity for La0.7Ca0.3Mn0.5Fe0.5O3sample investigated in magnetic fields B = 0 and 1 T. According to the research, the mechanisms of hopping conductivity were established. Micro parameters in density of localized states were calculated for LCMFO samples. The width of the Coulomb gap Δ = 0.67 eV, rigid gap δ = 0.324 eV and the localization radii of charge carriers were estimated. [ABSTRACT FROM PUBLISHER]

In this work, we present a detailed study on the magnetocaloric effect and the critical behaviors of an amorphous FeGdZr alloy ribbon prepared by using a rapid quenching method. We point out that the value of maximum magnetic entropy change (|∆ S|) of amorphous FeGdZr alloy ribbon appeared at near room temperature and versus Δ H obeys a power law, |∆ S| = a·Δ H. In addition, all Δ S( T, Δ H) data measured at different Δ H values are collapsed onto a universal master curve. Interestingly, M versus H/ M curves prove amorphous FeGdZr ribbon exhibitied a second-order magnetic phase transition. The critical exponents ( β, γ, and δ) obtained from the modified Arrott plots and the Kouvel-Fisher methods, and critical isotherm analysis are very close to those expected for the 3D-Heisenberg model, proving ferromagnetic short-range interactions exist in amorphous FeGdZr ribbon. [ABSTRACT FROM AUTHOR]

The crystal structure of iron-doped barium titanate BaTiFeO is studied by neutron diffraction in the range of 0 ≤ x ≤ 0.12. At low concentrations of iron, x < 0.01, and at room temperature, these compounds have a polar structure with tetragonal symmetry with space group P4 mm. The temperature of the transition of the tetragonal ferroelectric phase into the cubic paraelectric phase with space group Pm $$\bar 3$$ m for an iron concentration of x = 0.01 is 390 K (for pure BaTiO, it is 410 K). At an iron concentration of x = 0.07, the crystal structure of the studied compounds varies, and it is described by the centrosymmetric hexagonal space group P6/ mmc. The structural parameters of various phases of compound BaTiFeO are determined from the experimental data. [ABSTRACT FROM AUTHOR]