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Efficient electromagnetic waves (EMWs) absorbing materials play a vital role in the electronic era. In traditional research on microwave absorbing (MA) materials, the synergistic modulation of material dispersion and structural dispersion of EMWs by incorporating multi‐scale effects has frequently been overlooked, resulting in an untapped absorption potential. In this study, the material dispersion customization method based on biomass carbon is determined by quantitative analysis. The study carries out thermodynamic modulation of carbon skeleton, micro‐nano porous engineering, and phosphorus atom donor doping in turn. The dielectric properties are improved step by step. In terms of structural dispersion design, inspired by the theory of antenna reciprocity, a Vivaldi antenna‐like absorber is innovatively proposed. With the effective combination of material dispersion and structural dispersion engineering by 3D printing technology, the ultra‐wideband absorption of 36.8 GHz and the angular stability of close to 60 ° under dual polarization are successfully realized. The work breaks the deadlock of mutual constraints between wave impedance and attenuation rate through the dispersion modulation methods on multiple scales, unlocking the potential for designing next‐generation broadband wide‐angle absorbers. [ABSTRACT FROM AUTHOR]

In this work, we construct a fifth‐order weighted essentially non‐oscillatory (WENO) scheme with exponential approximation space for solving dispersive equations. A conservative third‐order derivative formulation is developed directly using WENO spatial reconstruction procedure, and third‐order TVD Runge–Kutta scheme is used for the evaluation of time derivative. This exponential approximation space consists a tension parameter that may be optimized to fit the specific feature of the characteristic data, yielding better results without spurious oscillations compared to the polynomial approximation space. A detailed formulation is presented for the construction of conservative flux approximation, smoothness indicators, nonlinear weights, and verified that the proposed scheme provides the required fifth convergence order. One‐ and two‐dimensional numerical examples are presented to support the theoretical claims. [ABSTRACT FROM AUTHOR]

To improve the mess-specific activity of Co supported on zeolite catalysts in Fischer–Tropsch (FT) synthesis, the Co-MCM-22 catalyst was prepared by simply grinding the MCM-22 with nanosized Co3O4 prefabricated by the thermal decomposition of the Co(II)-glycine complex. It is found that this novel strategy is effective for improving the mess-specific activity of Co catalysts in FT synthesis compared to the impregnation method. Moreover, the ion exchange and calcination sequence of MCM-22 has a significant influence on the dispersion, particle size distribution, and reduction degree of Co. The Co-MCM-22 prepared by the physical grinding of prefabricated Co3O4 and H+-type MCM-22 without a further calcination process exhibits a moderate interaction between Co3O4 and MCM-22, which results in the higher reduction degree, higher dispersion, and higher mess-specific activity of Co. Thus, the newly developed method is more controllable and promising for the synthesis of metal-supported catalysts. [ABSTRACT FROM AUTHOR]

The inherent π–π interfacial interaction between carbon nanotubes (CNTs) and polystyrene (PS) makes the CNT/PS composite a representative thermoplastic nanocomposite. However, the strong van der Waals force among CNTs poses challenges to achieving effective dispersion. This review provides an overview of various CNT functionalization methods for CNT/PS composites, encompassing covalent grafting with PS-related polymers and non-covalent modification. A focus in this section involves the pre-introduction surface modification of CNTs with PS or PS-related polymers, substantially enhancing both CNT dispersibility and interfacial compatibility within the PS matrix. Furthermore, a comprehensive summary of the mechanical, electrical, thermal, and electromagnetic shielding properties of CNT/PS nanocomposites is provided, offering an overall understanding of this material. The surface modification methods of CNTs reviewed in this paper can be extended to carbon material/aromatic polymer composites, assisting researchers in customizing the optimal surface modification methods for CNTs, maximizing their dispersibility, and fully unleashing the various properties of CNTs/polymer composites. Additionally, high-performance CNTs/PS composites prepared using appropriate CNT modification methods have potential applications in areas such as electronic devices, sensors, and energy storage and conversion. [ABSTRACT FROM AUTHOR]

The pyrolytic reforming of toluene to hydrogen and CNTs over the commercial and self-prepared Al 2 O 3 loaded with Fe through the impregnation method is investigated in a fixed bed reactor under the temperature from 600 °C to 800 °C. The physicochemical properties of Fe–Al 2 O 3 catalysts and Al 2 O 3 supports were characterized by XPS, H 2 -TPR, HRTEM and H 2 -pulse chemisorption. The reforming process over the catalyst of Fe loaded on self-prepared Al 2 O 3 gives the excellent H 2 yield of 27.8 mmol/(g-Fe) and graphite yield of 82.6 wt%, which is much higher than those from that over the catalyst of Fe loaded on the commercial Al 2 O 3. It is evidenced by H 2 -pulse chemisorption that 5.1 % of Fe0+ dispersion over the commercial Al 2 O 3 with mainly-exposed (110) facet while 11.2 % of Fe0+ dispersion over self-prepared Al 2 O 3 with mainly-exposed (111) facet were obtained. The adsorption energy of iron cluster (Fe 4) with Al 2 O 3 (111) facet was estimated to be −14.5 eV through the DFT simulation, which is notably higher than that of iron cluster (Fe 4) with Al 2 O 3 (110) facet as −9.1 eV. With regard to the MD simulation along with XRD analysis of the Fe 3 C crystallite, Fe0+ particles can be prominently molten at the high Fe0+ dispersion over Al 2 O 3 facet, promoting the carbon solubility for the assembly of multi-wall CNTs without the deposition of unwanted amorphous carbon. [Display omitted] • The influence of γ-Al 2 O 3 on Fe–Al 2 O 3 catalytic performance was investigated. • The crystal-facet effect of γ-Al 2 O 3 on metal Fe dispersion was evidenced. • The melting process over Fe nanoparticles with different sizes was simulated. • The interaction between γ-Al 2 O 3 and Fe 4 cluster was calculated via DFT theory. [ABSTRACT FROM AUTHOR]

To overcome challenges in pigment dispersion, especially for difficult‐to‐disperse pigments like phthalocyanine blue, the structure of dispersants has been studied in recent years. Herein, we present the development and performance evaluation of a structured polymer dispersant for efficient dispersion of phthalocyanine blue and color paste preparation. The dispersant was synthesized using a two‐step free radical polymerization process, allowing precise control over its structure. The study investigates the impact of key factors on dispersion, including the molecular weight of the hydrophilic long‐chain poly(ethylene glycol) monomethyl ether (MPEG), the ratio of anchoring groups styrene (St) and dimethylaminoethyl methacrylate (DMAEMA), and the dispersant dosage. Optimal stability was achieved with MPEG‐400 as the hydrophilic long chain and a St:DMAEMA ratio of 1:1, along with a MPEG‐400AA:AA ratio of 0.5:1 at 2000 r min−1. At a dispersant dosage of 25%, the particle size of the color paste measured 340 nm, with viscosity reaching 600 mPa·s. The structured dispersant effectively synergized spatial potential resistance and electrostatic effects to achieve stable pigment dispersion. These findings offer promising prospects for advancing dispersant technologies, with implications for improving color‐based applications across various industries, such as paints, coatings, and inks. [ABSTRACT FROM AUTHOR]

Results of studying the process of producing reactive alumina in the presence of a complex additive, including polycarboxylate ester (PCE) and polyethylene glycol (PEG), are presented. The effect of such reactive alumina on rheotechnological properties of matrix systems and low-cement refractory castables is evaluated. The synergetic effect of combined introduction of PEG and PCE during fine milling of raw alumina is established. It is shown that the deflocculating effect of polycarboxylate ester and the intensity of the milling process are strengthened. [ABSTRACT FROM AUTHOR]

Optoacoustics is a metrology widely used for material characterisation. In this study, a measurement setup for the selective determination of the frequency-resolved phase velocities and attenuations of longitudinal waves over a wide frequency range (3–55 MHz) is presented. The ultrasonic waves in this setup were excited by a pulsed laser within an absorption layer in the thermoelastic regime and directed through a layer of water onto a sample. The acoustic waves were detected using a self-built adaptive interferometer with a photorefractive crystal. The instrument transmits compression waves only, is low-contact, non-destructive, and has a sample-independent excitation. The limitations of the approach were studied both by simulation and experiments to determine how the frequency range and precision can be improved. It was shown that measurements are possible for all investigated materials (silicon, silicone, aluminium, and water) and that the relative error for the phase velocity is less than 0.2%. [ABSTRACT FROM AUTHOR]

Carbon dioxide is a suffocating gas resulting either from industrial activities from combustion or explosion. There may also be carbon dioxide deposits under pressure, quartered in porous geological formations. This gas can show slow or violent releases with accumulation at ground level. Carbon dioxide is a gas that is both toxic and asphyxiating. This gas can accumulate in closed spaces and when it exceeds the concentration of 12% vol. it becomes lethal. For the protection of working personnel, it is necessary to identify and apply the most effective preventive measures. This requires an understanding of carbon dioxide's behaviour during the build-up phase. The research gives a CFD analysis for determining the dynamics of carbon dioxide dispersion in a confined enclosure. [ABSTRACT FROM AUTHOR]

Human society is in full development. Proportionately, the industrial activity continuously develops and diversifies. Various technological processes also bring with them specific risks such as the one generated by the presence of carbon dioxide in closed premises. The effect of this gas on the human body is destructive and can reach situations incompatible with life. Preventive measures presuppose a good knowledge of how this gas disperses. This paper details the experimentation carried out to identify how carbon dioxide disperses. [ABSTRACT FROM AUTHOR]

Lead-based water pipelines pose a significant public health risk in the US. The challenge lies in locating these pipelines, as current identification technologies have limitations. This study discusses potential and challenges of identifying the water Service Line (SL) material through a stress wave propagation methodology. Since buried service lines are surrounded by soil and contain water, the stress wave propagation is non trivial. This work presents numerical simulations to investigate the applicability of the proposed method. First, authors consider wave propagation properties that could be used in a stress wave approach to identify buried lead based pipelines. For instance, dispersion curves are quite different for steel, copper, Lead, and PVC pipes filled with water. While the soil surrounding pipes causes a decrease in wave propagation energy due to the energy leakage into the soil medium, this phenomenon can enable the detection of leaked waves with sufficiently sensitive sensors installed near the soil surface. The received signals vary for different types of pipe materials, allowing to differentiate among service line materials. This study's numerical simulations and lab experiments suggest that stress wave propagation could become a valuable tool for identifying buried lead-based water SL materials. [ABSTRACT FROM AUTHOR]

A hierarchy of asymptotic models governing long-wave low-frequency in-plane motion of a fluid-loaded elastic layer is established. In contrast to a layer with traction-free faces, modelled by Neumann boundary conditions, a fluid-loaded one assumes more involved conditions along the interfaces, dictating a special asymptotic scaling. The latter corresponds to a fluid-borne bending wave, controlled by elastic stiffness of the layer and fluid inertia. In this case, the transverse inertia of the layer and fluid compressibility do not appear at zero-order approximation. The first-order approximation is associated with a Kirchhoff plate, immersed into incompressible fluid. In the studied free vibration setup, the fluid compressibility has to be taken into account only at third order, along with elastic rotary inertia. Transverse shear deformation enters the second-order approximation along with a few other corrections. The conventional impenetrability condition has to be also refined at second order. Dispersion relations corresponding to the developed asymptotic models are compared with the polynomial expansions of the full dispersion relation, obtained from the plane-strain problem of linear elasticity. [ABSTRACT FROM AUTHOR]

Two-dimensional nano graphene oxide (GO) has attracted the attention of researchers due to its excellent high aspect ratio and intrinsic strength. However, its effectiveness in improving cement composite's performance is significantly dependent on the uniform dispersion of GO in the host matrix. In recent years, the use of pozzolans, such as fly ash, silica fume, and metakaolin, to enhance the dispersion of GO in cement medium has become a focus of research. This study considered the effect of rice husk ash (RHA) on the GO dispersion quality in simulated cement pore solution (SCPS). The findings obtained were validated by the compressive and flexural strengths of cement paste samples. According to ultraviolet–visible (UV-vis) spectroscopy, zeta potential analysis, and other measurements, this research demonstrated that the addition of RHA to SCPS minimizes the size of GO agglomerations and considerably enhances dispersion. The compressive and flexural strength results of cement paste samples incorporating RHA-GO after 56 days of curing improved by 46.7% and 38.7%, respectively, compared with those of the reference samples. The results of this study could pave the way for application of binary GO-pozzolans containing cementitious nanocomposites. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) has promising applications in improving the microstructure and mechanical properties of cementitious materials due to its excellent properties. However, the enhancement effect of GO is largely dependent on its dispersion in the cement matrix. This paper summarizes the research results of GO in cementitious materials in recent years, focusing on the review of GO dispersion methods, dispersion mechanisms, and the corresponding mechanical property improvement mechanisms, comparing the advantages and disadvantages of different GO dispersion methods, and analyzing the effects on the microstructure and mechanical properties of cementitious materials before and after GO dispersion. The problems of the current research are pointed out, and an outlook on future research trends is provided, aiming to provide a basis for subsequent GO in cementitious materials for stable applications, in order to promote the preparation of highly functionalized GO cementitious composite reinforced materials. [ABSTRACT FROM AUTHOR]

The false blister beetle tribe Stenostomatini includes only the genus Stenostoma , with four species showing an intriguing distribution: Stenostoma lowei (Madeira), Stenostoma cossyrense (Pantelleria), Stenostoma melitense (Malta and southern Sicily) and Stenostoma rostratum, widely distributed along the Mediterranean and North Atlantic coasts. The evolutionary history leading to this distribution has not been investigated. Here, we explore the phylogeny and evolutionary history of the tribe, adopting an integrative approach that combines morphological and molecular data (mitochondrial COI and nuclear CAD and 28S). Moreover, we propose a new key for species identification and update the knowledge on adult and larval ecology. Finally, we propose the following explanation for the current distribution of the species. The genus originated in the Miocene, with S. lowei belonging to the oldest lineage. The remaining species share a common ancestor, dating to the Messinian Salinity Crisis. Stenostoma melitense and S. cossyrense are well differentiated according to morphology, but not according to molecular analysis. The wide distribution of S. rostratum might be related to its strategy of laying eggs within beached driftwood, where larvae develop, easily transported by the currents. Given that neither morphological nor molecular differentiation was detected between the two subspecies of S. rostratum , we propose the new synonymy Stenostoma rostratum septentrionale Švihla, 2005  =  Stenostoma rostratum (Fabricius, 1787) syn. nov. [ABSTRACT FROM AUTHOR]

In recent years, coal gasification slag has been widely used as an adsorbent in many countries worldwide. To better understand remediation of soil heavy metal pollution by coal gasification slag, it is necessary to examine and analyze the influence mechanism of the adsorption characteristics of coal gasification slag on the migration of heavy metal ions in the soil. In this study, we used a soil water movement model and convection-dispersion equation and constructed a model of heavy metal migration after soil improvement by coal gasification slag; then, we evaluated and predicted the influence of heavy metal infiltration with liquid on groundwater after soil improvement. Combined with the soil column experiment, HYDRUS-1D software was used to predict the migration behavior of heavy metals in the soil. The results showed that the dispersion of the sample with coal gasification slag was smaller than that of the original soil sample, and the permeability coefficient of the soil was reduced by 59.34%; after adding coal gasification slag, the adsorption rates of Cd2+ and Pb2+ on the soil samples were higher than 95% and 99% respectively. The constructed heavy metal migration model was fitted well and predicted the migration behavior of heavy metals in the soil satisfactorily. The addition of coal gasification slag can effectively prevent the infiltration of Cd2+ and Pb2+ in the soil and can mitigate groundwater pollution. Therefore, using the adsorption characteristics of coal gasification slag to study the migration behavior of Cd2+ and Pb2+ in soil has important practical significance for soil adsorption and provides a new idea for the comprehensive utilization of coal gasification slag. [ABSTRACT FROM AUTHOR]

Integrated photonics have been growing at an exponential rate. The related technologies are advancing with numerous research works on integrated devices offering Complementary Metal–Oxide–Semiconductor (CMOS) compatibility. Various compact waveguides are also exploited for different applications. In this paper, we report an unconventional 5 mm long air-clad SiN suspended core channel waveguide that is CMOS compatible. The hollowed-out Silica (SiO2) rectangular substrate serves as the lower cladding for the Silicon Nitride slab on which the rectangular core is suspended. The envisioned waveguide is engineered to be numerically pumped at 1.55 μm wavelength with a pulse that is 20 kW in power and 50 fs in duration. The generated Supercontinuum spanning from 0.8 to 6 μm has a great potential in bio-medical and imaging applications. [ABSTRACT FROM AUTHOR]

In this paper, benzene-core photonic crystal fibers (B-PCFs) with non-uniform air holes for the square lattice are studied by controlling the air-filling factor of the air holes in the first ring and increasing those up to a maximum for external holes. Commercial Mode Solutions software is used to study the influence of structural parameters on the nonlinear coefficient, dispersion, effective mode area, and attenuation. It can be seen that this design affects the linear and nonlinear properties at the same time. In other words, it has a crucial effect on either the near-zero flatness of dispersion or going up the nonlinearity and falling the loss of the B-PCFs. The above benefits make the optimized fibers suitable for supercontinuum (SC) generation applications. [ABSTRACT FROM AUTHOR]

Copyright of SHILAP Revista de Lepidopterologia is the property of Sociedad Hispano-Luso-Americana de Lepidopterologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The rheological characterization of STFs plays an essential role in understanding the suspension's stability and the structural changes that occur under the impact of shear forces. This study aims to investigate the rheological behavior of STF after adding titanium diboride (TiB2) as an additive. STF modified with 2 % w/W TiB2 compared to other concentrations (1 %, 1.25 %, and 3 %) showed a maximum rise in viscosity (max), i.e., 18,484 Pa s during steady state rheology, as compared to untreated STF. In dynamic rheology, the same sample demonstrated maximum values of G′ and G″ at a constant frequency of 30 rad/s, G′ and G″ improved by 25 and 11 times, respectively, over unmodified STF. Furthermore, for constant strain amplitudes, the maximum values of G′ and G″ were observed at a strain amplitude of 700 %. G′ and G″ improved by approximately 6.5 and 6 times over unmodified STF, respectively. The findings of the dynamic and steady-state rheological analyses demonstrated that integrating TiB2 into the STF improved the ST behavior. [ABSTRACT FROM AUTHOR]

A metamaterial wave absorber (MWA) optimized for high-performance absorbers to harvest electromagnetic energy is designed for operation within the terahertz (THz) frequency range using renewable palm oil frond graphitic carbon (POFGC). The structural composition of the MWA consists of double split-ring resonators configured in rotational symmetry. The fundamental component of the design has three distinct layers: (1) the bottom layer, composed of a metallic substance with gold that exhibits a lossy metal characteristic; (2) the middle layer, made of a lossy dielectric material referred to as silicon dioxide (SiO2); and (3) the top layer crafted from POFGC. The findings reveal that the absorber achieves a broad absorption spectrum, with simulated results from CST software indicating absorption peaks at 414, 708, 981, and 1242 THz. These results demonstrate high absorption levels of 99.989, 99.999, 99.988, and 99.999% for typical incident electromagnetic waves. The structural dimensions (590 × 590 nm2) are designed to deliver remarkable performance across the visible spectrum and infrared frequency ranges. The energy harvester exhibits independent polarization at various angles, including 0°, 45°, 90°, 135°, 180°, and 225°. It has excellent harvesting capabilities across multiple angles of incidence from 0° to 80°, including the whole operational spectrum. A comparative investigation of the circuit indicates enhanced performance of the metamaterial wave absorber, demonstrating its potential for exceptional functionality inside the advanced design system (ADS) software. Furthermore, the structures under consideration, which were simulated using the HFSS (high-frequency structure simulator) tool, demonstrate strong agreement with the highest level of absorption seen at each resonance peak in the CST simulation outcomes. This paper introduces an alternative protocol, expressed in terms of the phase velocity of the mode, for use with the restricted asymmetric structure to find optimum dispersion. The study highlights the exceptional properties of POFGC, including its high absorption capacity, insensitivity to angles, and effective dispersion properties. [ABSTRACT FROM AUTHOR]

Soil sodification is a soil degradation process that commonly occurs in the irrigated soils of arid and semi-arid lands, resulting in a significant decrease in productivity. Assessing the impacts of different types of water (irrigation water, groundwater, and rainfall) on soil drainage is important for achieving sustainable land management of irrigated areas. We investigated the changes in soil saturated hydraulic conductivity (HC) under different salt treatments by separating the effects of swelling and dispersion. The salt treatments were conducted at different salt compositions (SAR∞, SAR10, SARO; SAR=Na/(Ca/2)1/2 (cations: mol, L-1)) and concentrations (0.05, 0.01, 0.001 N) on Indian soil (sandy clay loam). The soil columns were continuously leached with each treatment solution and changes in the HC were plotted against the cumulative amount of leaching solution. Furthermore, the effects of swelling and dispersion by Na on the drainage properties were observed separately. Our results support the existing findings that dispersion is triggered at concentrations below the critical coagulation concentration (CCC), which further varies with the degree of sodification in a single mineralogy. The distinct manner of HC reduction between SAR10- and SAR∞-treated soils could imply different behaviors of the dispersed particles, which form a soil crust or cause soil erosion. Finally, we present the preliminary results of our experiments and discuss future research on the CCC reset mechanisms. [ABSTRACT FROM AUTHOR]

Copyright of Baghdad Science Journal is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Cardiac involvement in systemic sclerosis (SSc) is significant cause of SSc-related mortality. The objective of the study was to assess cardiac arrhythmias, P wave and QT dispersion in SSc patients. 40 SSc patients and 40 healthy participants who had similar sociodemographic characteristics with the patients were enrolled in the study. P wave dispersion (Pd), QT dispersion (QTd), and corrected QT (QTc) dispersion (QTcd) were calculated by measuring maximum (max) and minimum (min) of P wave, QT interval, QTc in 12-leads electrocardiography (ECG). Cardiac arrhythmias and conduction disorders were assessed by ECG and Holter-ECG. The mean age of SSc patients (92.5% of females) was 50.9±13.9 years similar with the healthy group (51.4±8.9). Abnormal ECG findings were found in 27.5% of SSc patients and remarkably higher in comparison to the healthy participants (p=0.019). The most frequently reported abnormal ECG findings were left anterior fascicular block (15%), ventricular premature beat (10%) and first-degree atrioventricular heart block (5%). The comparison of dispersion showed no statistically important difference in Pd between two groups (p=0.69) while QTd, QTc, QTcd, QTc min, and QTc max were markedly prolonged in patients with SSc (p=0.039; p<0.001; p=0.021; p<0.001; p<0.001, respectively). The assessment of Holter-ECG demonstrated that supraventricular tachycardia was frequently detected in patients with SSc (22.5% vs 2.5%; p=0.007). This study indicated a significantly elevated incidence of abnormal ECG results and SVT, an arrhythmia not typically identifiable through standard ECG but detectable via Holter monitoring, in patients with SSc. In the study, QTd, QTc, and QTcd intervals were significantly longer in SSc patients, which may indicate a susceptibility to arrhythmias. [ABSTRACT FROM AUTHOR]

We prove upper and lower bounds on the minimal spherical dispersion, improving upon previous estimates obtained by Rote and Tichy in (Anz Österreich Akad Wiss Math Nat Kl 132:3–10, 1995). In particular, we see that the inverse N (ε , d) of the minimal spherical dispersion is, for fixed ε > 0 , linear in the dimension d of the ambient space. We also derive upper and lower bounds on the expected dispersion for points chosen independently and uniformly at random from the Euclidean unit sphere. In terms of the corresponding inverse N ~ (ε , d) , our bounds are optimal with respect to the dependence on ε . [ABSTRACT FROM AUTHOR]

In order to enhance dispersity and compatibility of the carbon nanomaterials in polar/non polar solutions and polymers, carbon nanotube and graphene were modified using ethyl acetate as a monomer by free radical polymerization. The effects of coatings on carbon nanomaterials were characterized by infrared spectra, thermogravimetric analysis, scanning electron microscope, and Raman spectrum. Through infrared spectra, the coated carbon nanomaterial exhibited a characteristic absorption peak of vinyl acetate, and a significant weight loss occurred at 170~240 °C in the thermogravimetric curves. From Raman spectrum, the ID/IG of the modified carbon nanotubes and graphene decreased from 1.730 and 1.040 to 1.090 and 0.985, respectively, indicating an increase in the degree of graphitization. The results indicate the success of vinyl acetate modified carbon nanomaterials. Dispersity and compatibility of modified carbon nanomaterials were assayed by ultraviolet spectra, discovering that the coated carbon nanomaterials exhibit excellent dispersibility and stability. The results indicated that the surfaces of carbon nanomaterials were coated by polyvinyl acetate via in-situ polymerization. The structures of carbon materials were not destroyed by coating process and their properties were kept. When the mass ratios of polyvinyl acetate to carbon materials were 1:1 and 2:1, the results of coating were excellent. Furthermore, the modified carbon nanomaterials possessed the perfect dispersity and stability. [ABSTRACT FROM AUTHOR]

The modeling of reactive transport through porous media is a challenging numerical problem. Methods of solution have leveraged the stoichiometry of chemical reactions to address the transport of multiple aqueous species by expressing them in terms of an equivalent, linearly independent variable (component). This approach effectively decouples advection‐dispersion transport from the source terms associated with equilibrium reactions. A common assumption found in the literature is that all species disperse with the same transport coefficients. Recent experimental studies have discussed that this is not necessarily the case, particularly for transverse mixing, which is limited by the species‐specific molecular diffusion. This article presents a formulation of multicomponent reactive transport that takes into account the differences in dispersion coefficients. These differences lead to a nonlinear transport equation for the components, from where an expression for evaluating reaction rates is derived. It is demonstrated that this expression simplifies to the well‐known equations assuming the same dispersion for all species. Numerical simulations of a binary chemical system under diffusion‐ and advection‐dominated transport conditions are used to evaluate the influence that differential transport coefficients have upon the output of chemical reactions. Results indicate that differences in transport coefficients are particularly relevant when the chemical signature of the input solutions is not strongly dominated by one of the species in the component. Unexpectedly, this opens the possibility to mineral dissolution coexisting with precipitation during the mixing of two waters in equilibrium. This phenomenon can be explained by nonlinear mixing processes proportional to the differences in transport coefficients. Key Points: New formulation of multicomponent reactive transport with species‐specific dispersion properties and nonlinear transport for the componentsA general expression for evaluating reaction rates is derived considering the transport properties of all speciesDifferences in coefficients can lead to dissolution coexisting with precipitation for a equilibrium binary reaction in dilute systems [ABSTRACT FROM AUTHOR]

Perhydro-dibenzyltoluene (18H-DBT) have been paid more attention as liquid organic hydrogen carriers (LOHCs) because of its high hydrogen storage, easy transportation, low price and other advantages. The 18H-DBT dehydrogenation reaction rate is the key point of the hydrogen storage. In this work, the relationship between the Pt dispersion, the average coordinated number and the total catalyst activity for 18H-DBT dehydrogenation reaction was studied. Al 2 O 3 with the large specific surface area was synthesized by the sol–gel method and Pt/Al 2 O 3 catalysts were prepared by incipient wetness impregnation. Their catalytic performance was tested by 18H-DBT dehydrogenation reaction. It was found that the relationship between the Pt dispersion and the catalytic performance is a volcano curve. The optimal dispersion of Pt for dehydrogenation reaction is 11.16 %. That's because that there exists a balance between the Pt dispersion and the average coordinated number in order to obtain the best total catalyst activity. The experiments and characterization results show that the increasing of Pt dispersion will increase the active site number but the average coordinated number will decrease. DFT calculation results further confirm that the catalytic activity of the single active site would decline with the decreasing average coordinated number. [Display omitted] • Al 2 O 3 with a large specific surface area (436 m2 g−1) was successfully synthesized. • The highest degree of dehydrogenation and TOF for 18H-DBT dehydrogenation is 63.84 % and 1.31 min−1, respectively. • When the Pt dispersion increase, the average coordinated number of active sites will decrease. • The catalytic activity of the single active site will decrease with the average coordinated number decreasing. [ABSTRACT FROM AUTHOR]

The effect of colloidal nanoparticles on the phase changes of the amphiphilic AB linear diblock, A1A2B, and A2B heteroarm star copolymers confined between two polymer brush substrates was investigated by using a real-space self-consistent field theory. By changing the concentrations of nanoparticles and polymer brushes, the phase structure of the amphiphilic AB copolymer transforms from lamellar to core-shell hexagonal phase to cylinder phase. The pattern of A2B heteroarm star copolymer changes from core-shell hexagonal phases to lamellar phases and the layer decreases when increasing the density of the polymer brushes. The results showed that the phase behavior of the system is strongly influenced by the polymer brush architecture and the colloidal nanoparticle numbers. The colloidal nanoparticles and the soft confined surface of polymer brushes make amphiphilic AB copolymers easier to form ordered structures. The dispersion of the nanoparticles was also investigated in detail. The soft surfaces of polymer brushes and the conformation of the block copolymers work together to force the nanoparticles to disperse evenly. It will give helpful guidance for making some new functional materials by nano etching technology, nano photoresist, and nanoprinting. [ABSTRACT FROM AUTHOR]

Organisms that immigrate into a recipient habitat generate a movement pattern that affects local population dynamics and the environment. Spillover is the pattern of unidirectional movement from a donor habitat to a different, adjacent recipient habitat. However, ecological definitions are often generalized to include any cross-habitat movement, which limits within- and cross-discipline collaboration. To assess spillover nomenclature, we reviewed 337 studies within the agriculture, disease, fisheries and habitat fragmentation disciplines. Each study's definition of spillover and the methods used were analysed. We identified four descriptors (movement, habitat type and arrangement, and effect) used that differentiate spillover from other cross-habitat movement patterns (dispersal, foray loops and edge movement). Studies often define spillover as movement (45%) but rarely measure it as such (4%), particularly in disease and habitat fragmentation disciplines. Consequently, 98% of studies could not distinguish linear from returning movement out of a donor habitat, which can overestimate movement distance. Overall, few studies (12%) included methods that matched their own definition, revealing a distinct mismatch. Because theory shows that long-term impacts of the different movement patterns can vary, differentiating spillover from other movement patterns is necessary for effective long-term and inter-disciplinary management of organisms that use heterogeneous landscapes. [ABSTRACT FROM AUTHOR]

For the dispersion of soluble matter in solvent flowing through a tube as investigated originally by G.I. Taylor, a streamwise dispersion theory is developed from a Lagrangian perspective for the whole process with multi-scale effects. By means of a convected coordinate system to decouple convection from diffusion, a diffusion-type governing equation is presented to reflect superposable diffusion processes with a multi-scale time-dependent anisotropic diffusivity tensor. A short-time benchmark, complementing the existing Taylor-Aris solution, is obtained to reveal novel statistical and physical features of mean concentration for an initial phase with isotropic molecular diffusion. For long times, effective streamwise diffusion prevails asymptotically corresponding to the overall enhanced diffusion in Taylor's classical theory. By inverse integral expansions of local concentration moments, a general streamwise dispersion model is devised to match the short- and long-time asymptotic solutions. Analytical solutions are provided for most typical cases of point and area sources in a Poiseuille tube flow, predicting persistent long tails and skewed platforms. The theoretical findings are substantiated through Monte Carlo simulations, from the initial release to the Taylor dispersion regime. Asymmetries of concentration distribution in a circular tube are certified as originated from (a) initial non-uniformity, (b) unidirectional flow convection, and (c) non-penetration boundary effect. Peculiar peaks in the concentration cloud, enhanced streamwise dispersivity and asymmetric collective phenomena of concentration distributions are illustrated heuristically and characterised to depict the non-equilibrium dispersion. The streamwise perspective could advance our understanding of macro-transport processes of both passive solutes and active suspensions. [ABSTRACT FROM AUTHOR]

Diagnosing unsuccessful population outcomes for endangered species requires understanding relationships among vital rates, ecological conditions, and management variables, including unintended consequences of management actions. The federally threatened Piping Plover (Charadrius melodus) has remained below recovery goals, despite intensive management, including the use of nest exclosures to protect eggs from predation. We studied ecological factors and management actions affecting nest success, survival, site fidelity, and dispersal of the New Jersey, USA population of Piping Plovers over a 7-yr period, focused on evaluating the impact of exclosures on demography. While exclosures increased nest success by 62% over a 34-day period, exclosed nests were 4.7 times more likely to be abandoned, which was likely a consequence of adult mortality. Abandoned nests were associated with lower adult survival, particularly for males, but there was evidence that site fidelity was greater for birds whose last nest was exclosed vs. unexclosed. Regardless of exclosure status, females who abandoned their first nesting attempt dispersed 10 times farther between attempts than those whose first nest attempts were lost to other causes. Moreover, females that abandoned their last nesting attempts dispersed farther than females that lost their last nest to predation or flooding. This difference was more substantial for males. Our results corroborate studies documenting adverse impacts of exclosures on survival, and, for the first time, demonstrate that surviving mates (particularly females) emigrate from the breeding site, resulting in a realized loss of a local breeding pair. Further, we used an online population project model (i.e., PiperEx) to demonstrate that exclosures are not expected to improve growth rates in New Jersey. We conclude that there is a trade-off among increased nest survival, reduced adult survival and increased emigration rates, and we encourage managers to consider whether exclosures are worth the protection of eggs from predators using online decision support tools. [ABSTRACT FROM AUTHOR]

Objectives: Darkening has been an issue of concern for foundation products. The secretion of sebum plays a significant role in the process of foundation darkening, but the underlying mechanisms and solutions have been rarely reported. The aim of this study was to explore the relationship between sebum secretion and liquid foundation darkening and to provide possible solutions for reducing sebum‐induced darkening in liquid foundation. Methods: Artificial sebum in different concentrations was added to a basic liquid foundation to simulate different stages of sebum secretion. The colour of the mixture was then measured by a spectrophotometer on the standard opacity chart. Potential technical solutions for anti‐darkening were applied to a basic liquid foundation, and its ability to anti‐darkening was further verified in vivo. Results: (1) The influences of sebum addition on liquid foundation darkening had a significant positive correlation with the increase in transmissivities (R2 = 0.852, p < 0.01). (2) A certain range of sebum addition can reduce the darkening of volatile foundations. (3) The liquid foundations using pigments with high dispersibility in sebum were less influenced by sebum. (4) The replacement of pigments with oil‐fixing ability could effectively reduce the darkening of liquid foundations induced by sebum (p < 0.01). Conclusion: The effect of sebum on the darkening of liquid foundation was accompanied by a greater transmissivity as its pigment concentration decreased. Balanced volatility, the addition of powders with higher sebum dispersibility and the replacement of oil‐fixing powders could reduce the darkening of the liquid foundation caused by sebum secretion. [ABSTRACT FROM AUTHOR]

This study investigates instantaneous and continuous sources as point, line, and area sources. Gaussian concentration in the case of the puff model with an instantaneous point source inhomogeneous longitudinal diffusion is investigated. The concentration is calculated using different dispersion parameters to get the proposed normalized concentration of the puff model at ground level around the centerline, which is compared with observed data by the Copenhagen experiment and previous work [1]. Also, the continuous point source is used to get the Gaussian plume model in three dimensions using dispersion parameters to compare with the observed concentration data measured by the Egyptian Atomic Energy Authority for Iodine-135 (I135) in an unstable condition. [ABSTRACT FROM AUTHOR]

[Display omitted] Aqueous graphene dispersions are usually obtainable by treating the surface of graphene chemically or physically. In these dispersions, the rheological properties (e.g., viscosity) are governed by a direct coupling to the graphene concentration, which limits their applicability. An alternative approach for dispersing graphene is trapping them in a viscoelastic-network formed by a co-dispersed charged fibrous-clay, Sepiolite. Contrary to surface treatment, the rheological properties of these dispersions are set by the clay particles. The rheology of charged-colloidal dispersions is governed by various parameters, including interparticle interactions. Hence, the rheology of the dispersion could be modulated by changing the clay surface charge without compromising the dispersed graphene concentration. The surface charge of Sepiolite was modulated either by charge-screening (by NaCl added to the solution) or by surface-charging (by attachment of highly charged ions, e.g., HexaMetaPhosphate, HMP−) and the effect on rheology and graphene concentration was assessed. In particular, loading the dispersion with HMP− yielded low viscosity, storage, and loss moduli (two orders of magnitude lower than the corresponding HMP−-free dispersion) while the graphene concentration was maintained. We demonstrate that by this charge-modulation approach, reaching the rheological requirements of different applications without compromising on graphene concentration is plausible. [ABSTRACT FROM AUTHOR]

The classical two-scale asymptotic paradigm provides macroscopic and microscopic analyses for the elastodynamic homogenization of periodic composites based on the spatial or/and temporal variable, which offers an approximate framework for the asymptotic homogenization analysis of the motion equation. However, in this framework, the growing complexity of the homogenization formulation gradually becomes an obstacle as the asymptotic order increases. In such a context, a compact, fast, and accurate asymptotic paradigm is developed. This work reviews the high-order spatial two-scale asymptotic paradigm with the effective displacement field representation and optimizes the implementation by symmetrizing the tensor to be determined. Remarkably, the modified implementation gets rid of the excessive memory consumption required for computing the high-order tensor, which is demonstrated by representative one- and two-dimensional cases. The numerical results show that (1) the contrast of the material parameters between media in composites directly affects the convergence rate of the asymptotic results for the homogenization of periodic composites, (2) the convergence error of the asymptotic results mainly comes from the truncation error of the modified asymptotic homogenized motion equation, and (3) the excessive norm of the normalized wavenumber vector in the two-dimensional inclusion case may lead to a non-convergence of the asymptotic results. [ABSTRACT FROM AUTHOR]