Specific Properties Research Articles

Enhanced surface finish and reduced porosity of TiC nanoparticles reinforced 2219 aluminum alloy deposit fabricated via oscillating laser-arc hybrid additive manufacturing

Additive manufacturing (AM) of ceramic particle reinforced aluminum alloy has drawn increasing attention due to the refined microstructure and improved mechanical properties in as-deposited condition. However, it is still challenging to make defect-free ceramic particle reinforced aluminum alloy deposit with desirable surface finish using wire-based AM technique because of the special thermophysical properties of the incorporated ceramic particles. In this work, a novel oscillating laser-arc hybrid additive manufacturing (OLHAM) technique was developed to fabricate TiC nanoparticles reinforced 2219 aluminum alloy deposit. The surface finish and porosity were evaluated using optical microscope and 3D XCT, respectively. Compared with wire-arc additively manufactured (WAAMed) deposit, the surface roughness and volume porosity of OLHAMed deposit decreased by 46.0 % and 88.3 %, respectively. In-situ high-speed photography was used to observe the arc and molten pool behaviors to understand the mechanism of enhanced surface finish and reduced porosity. The enhanced surface finish was attributed to smaller layer width fluctuation and higher arc stability, which resulted from the action of the hybrid heat source. The elimination of large droplet transfer, which caused pores in the WAAMed deposit, and the promotion of molten pool fluidity resulted in much lower porosity of the OLHAMed deposit.

Constructing chaotic oscillators with memory components

Memory components, including memristors, meminductors and memcapacitors, have special nonlinear dynamical properties and thus applicable for constructing a compact chaotic circuit in parallel or in series. By selecting the restriction of a memory component, chaos control can also be achieved using a single circuit parameter. In this work, three different types of circuit structures are designed to implement memory components for chaos generation. With the help of a voltage-control or a current-control memristor, within a series or a parallel structure, a memristive chaotic oscillator with partial control is built based on the variable boostable systems. The two constructed structures are equivalent and can be mutually tuned, achieving partial amplitude control as well as offset boosting. By constructing a magnetic-control meminductor or a charge-control memcapacitor, the equivalent parallel circuit is built with a meminductor, a capacitor and a resistor, corresponding to the series circuit with a memcapacitor, an inductor and a resistor. It can be applied to realizing the hypogenetic chaotic jerk system even with conditional symmetry. All the designed circuits are physically realized based on PCB, proving the effectiveness of memory components for chaos generation.

Two-step modification strategy enhances carbon fiber/old corrugated container fiber flexible conductive film

Carbon fiber (CF) possesses inherent properties of low density, high strength, and environmental stability. Its high aspect ratio and knittability enable the formation of flexible conductive networks. Old corrugated container (OCC) is rich in cellulose and hemicellulose, rendering them flexible and exhibiting a low coefficient of thermal expansion. In this paper, CF/OCC/PVA flexible conductive films were prepared using polyvinyl alcohol (PVA) as the matrix, CF as the conductive filler and OCC as the flexible support material. Firstly, the coupling agent was grafted on the surface of CF to enhance their surface activity, improve the dispersion of CF in solution and the chemical bonding of CF to the matrix. Subsequently, sizing nanoparticles were applied to increase the roughness of the CF surface. This served to increase the volume of the conductive network and enhance the mechanical interlocking between CF and PVA. The results show that the two-step combined modification strategy have a significant positive impact on the interfacial chemical activity, contact angle, and roughness of CF. Moreover, it leads to notable improvements in various properties of the conductive film materials. This finding is relevant for the preparation of CF reinforced other matrix materials as well as for expanding the special properties and application value of CF conductive thin film materials.

Efficient synthesis of benzyl-protected cyclic lysine on Pt/m-Al2O3 catalysts and its application in functional nylon-6 copolymers production

Functional nylon-6 polymers, particularly those with special properties such as antibacterial, flame retardant, and specialized thermal properties, have a wide range of applications. However, the efficient synthesis of these polymer monomers has long remained a challenge. Benzyl-protected cyclic lysine (BCL) is a potentially functional monomer, and this article proposes an efficient method for the synthesis of benzyl-protected cyclic lysine on a supported platinum catalyst. Compared to existing techniques, this approach offers higher synthesis efficiency and sustainability. Pt/m-Al2O3 (microspherical Al2O3) catalysts were prepared using a vacuum impregnation method and showed good activity and selectivity in the production of benzyl-protected cyclic lysine. The conversion rate of α-amino-ε-caprolactam (α-ACL) was 100%, and the selectivity of BCL was 96.0%. The Pt/m-Al2O3 catalyst maintained good stability over multiple reaction cycles. The reaction mechanism and thermodynamics of functionalized α-ACL were also investigated. The copolymer synthesized with the prepared BCL showed similar structure and thermal stability to pure nylon-6, indicating possible unique functional properties. This study provides a route for the synthesis of cyclic lysine protected with various groups and its potential applications in the field of polymer chemistry.

Constructing Two-Dimensional Heterostructure Channels with Engineered Biomembrane and Graphene for Precise Scandium Sieving.

The special properties of rare earth elements have effectively broadened their application fields. How to accurately recognize and efficiently separate target rare earth ions with similar radii and chemical properties remains a formidable challenge. Here, we constructed precise two-dimensional (2D) heterogeneous channels using engineered E. coli membranes between graphene oxidse (GO) layers. The difference in binding ability and corresponding conformational change between Lanmodulin (LanM) and rare earth ions in the heterogeneous channel allow for precisely recognizing and sieving of scandium ions (Sc3+). The engineered E. coli membranes not only can protect the integrity of structure and functionality of LanM, the rich lipids and sugars but also help the E. coli membranes closely tile on the GO nanosheets through interaction, preventing swelling and controlling interlayer spacing accurately down to the sub-nanometer. Apparently, the 2D heterogeneous channels showcase excellent selectivity for trivalent ions (SFFe 3+ /Sc 3+≈3), especially for Sc3+ ions in rare earth elements with a high selectivity (SFCe/Sc≈167, SFLa/Sc≈103). The long-term stability and tensile strain tests verify the membrane's outstanding stability. Thus, this simple, efficient, and cost-effective work provides a suggestion for constructing two-dimensional interlayer heterogeneous channels for precise sieving, and the valuable strategy is proposed for the efficient extraction of Sc. This article is protected by copyright. All rights reserved.

Human amniotic epithelial stem cell is a cell therapy candidate for preventing acute graft-versus-host disease.

Graft-versus-host disease (GVHD), an immunological disorder that arises from donor T cell activation through recognition of host alloantigens, is the major limitation in the application of allogeneic hematopoietic stem cell transplantation (allo-HSCT). Traditional immunosuppressive agents can relieve GVHD, but they induce serious side effects. It is highly required to explore alternative therapeutic strategy. Human amniotic epithelial stem cells (hAESCs) were recently considered as an ideal source for cell therapy with special immune regulatory property. In this study, we evaluated the therapeutic role of hAESCs in the treatment of GVHD, based on our previous developed cGMP-grade hAESCs product. Humanized mouse model of acute GVHD (aGVHD) was established by injection of huPBMCs via the tail vein. For prevention or treatment of aGVHD, hAESCs were injected to the mice on day -1 or on day 7 post-PBMC infusion, respectively. We showed that hAESCs infusion significantly alleviated the disease phenotype, increased the survival rate of aGVHD mice, and ameliorated pathological injuries in aGVHD target organs. We demonstrated that hAESCs directly induced CD4+ T cell polarization, in which Th1 and Th17 subsets were downregulated, and Treg subset was elevated. Correspondingly, the levels of a series of pro-inflammatory cytokines were reduced while the levels of the anti-inflammatory cytokines were upregulated in the presence of hAESCs. We found that hAESCs regulated CD4+ subset polarization in a paracrine mode, in which TGFβ and PGE2 were selectively secreted to mediate Treg elevation and Th1/Th17 inhibition, respectively. In addition, transplanted hAESCs preserved the graft-versus-leukemia (GVL) effect by inhibiting leukemia cell growth. More intriguingly, hAESCs infusion in HSCT patients displayed potential anti-GVHD effect with no safety concerns and confirmed the immunoregulatory mechanisms in the preclinical study. We conclude that hAESCs infusion is a promising therapeutic strategy for post-HSCT GVHD without compromising the GVL effect. The clinical trial was registered at www.clinicaltrials.gov as #NCT03764228.

Advancing Aquatic Food Safety Detection Using Highly Sensitive Graphene Oxide and Reduced Graphene Oxide (GO/r-GO) Fluorescent Sensors

AbstractWith the increasing demand for aquatic products, the requirement for the safety detection of aquatic products is also increasing. In the past decade, graphene oxide (GO) and reduced graphene oxide (r-GO) have become hot topics in many fields due to their special physical and chemical properties. With their excellent conductivity, a variety of electrochemical sensors have been developed in the fields of biology, food and chemistry. However, the unique optical properties of GO/r-GO have not yet been widely utilized. With the deepening of research, the fluorescence quenching performance of GO/r-GO has been proven to have excellent potential for building fluorescent sensors, and GO/r-GO fluorescent sensors have thus become an inevitable trend in sensor development. This review summarizes the main preparation methods of GO/r-GO and the principles of GO/r-GO fluorescent sensors comprehensively. Additionally, recent advances in utilizing GO/r-GO fluorescent sensors to detect aquatic food are discussed, including the application for the detection of harmful chemicals, microorganisms, and endogenous substances in aquatic products, such as pesticides, antibiotics and heavy metals. It is hoped that this review will help accelerate the progress in the field of analysis, and promote the establishment of an aquatic food supervision system.

Soliton structures for the (3 + 1)-dimensional Painlevé integrable equation in fluid mediums

The (3 + 1)-dimensional Painlevé integrable equation are a class of nonlinear differential equations with special properties, which play an important role in nonlinear science and are of great significance in solving various practical problems, such as many important models in fields such as quantum mechanics, statistical physics, nonlinear optics, and celestial mechanics. In this work, we utilize the Hirota bilinear form and Mathematica software to formally obtain the interaction solution among lump wave, solitary wave and periodic wave, which has not yet appeared in other literature. Additionally, using the (G′/G)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(G'/G)$$\\end{document}-expansion method, we provide a rich set of exact solutions for the (3 + 1)-dimensional Painlevé integrable equation, which includes two functions with arbitrary values. This method is the first to be applied to the (3 + 1)-dimensional Painlevé integrable equation. By giving some 3D graphics and density maps, the dynamic properties are analyzed and demonstrated, which is beneficial for promoting understanding and application of the (3 + 1)-dimensional Painlevé integrable equation.

Detection of Ascorbic Acid by Two-Dimensional Conductive Metal-Organic Framework-Based Electrochemical Sensors

The realization of efficient and accurate detection of biomolecules has become a key scientific issue in the field of life sciences. With the rapid development of nanotechnology, electrochemical sensors constructed from the superior physical and chemical properties of nanomaterials show faster and more accurate detection. Among nanomaterials, two-dimensional conductive MOF (2D cMOF) is considered to be a star material in electrochemical sensors due to its remarkable conductivity, high porosity, and stability. In this paper, a Cu3(HHTP)2/SPE electrochemical sensor for the detection of ascorbic acid (AA) was constructed by modifying 2D cMOF (Cu3(HHTP)2) on the surface of the screen-printed electrode (SPE). The sensor exhibited excellent catalytic activity in the detection of AA, with a lower detection limit of 2.4 μmol/L (S/N = 3) and a wide linear range of 25–1645 μmol/L. This high catalytic activity can be attributed to the abundant catalytic sites in Cu3(HHTP)2 and the rapid electron transfer between Cu+ and Cu2+, which accelerates the oxidation of AA. This work lays a foundation for the subsequent development of MOFs with special electrochemical catalytic properties and the integration of 2D cMOF into intelligent electrical analysis devices.

Super-slippery silicone-based gel coating with a regenerative oil layer for long-term prevention of surface contamination

Polymer-based gel-type coatings, in which oil molecules are absorbed within polymer networks, have drawn attention as functional coatings to address fouling problems. However, surface drought caused by lubricant depletion limits the longevity of conventional gel-type coatings. In this study, a super-slippery long-chain entangled polydimethylsiloxane (LEP) gel that can self-regenerate its low-viscosity oil layer is proposed to enhance its long-term anti-fouling performance in both indoor and marine habitats. The proposed LEP gel coating can effectively prevent contamination from numerous liquids and protect aluminum surfaces from corrosion in seawater. Even when it was incubated with Porphyridium purpureum, marine red algae that readily stick to the surface, no biofilm was formed on the coated samples for 37 weeks. In field tests, no biological adhesion was observed on the coating surface which was applied to port structures and left for two summer months. This enhanced anti-contamination performance is mainly attributed to the dual protective barrier comprising the underlying polymer layer and regenerative oil layer. Due to special property of continuous self-regeneration of oil layer, the proposed LEP gel surface demonstrates much enhanced sustainability, compared to conventional gel-type coatings. Consequently, the long-term anti-contamination performance of the super-slippery LEP gel coating would pave the way for novel approach to its practical applications.

Novel routes for synthesis of rare earth oxychlorides

Rare earth oxychlorides (REOCl) have received significant interest for their potential applications in chloride ion conductors, catalysts, luminescent materials due to their unique and special properties. Many synthesis methods were reported for their production including solid-state, flux-assisted, and sol-gel techniques. The present study introduces two straightforward solid state synthesis routes for synthesizing desired oxychlorides. In the first route, REOCl is prepared by roasting of a mixture of hydrous rare earth chloride (RECl3.xH2O) and rare earth oxide (RE2O3) powder. The second route involves, initial curing followed by roasting a portion of RE2O3 with hydrochloric acid (HCl) for production of the oxychlorides. For both routes, the optimal process conditions were first defined for LaOCl synthesis. Subsequently, the refined conditions of second method were successfully applied to the synthesis of NdOCl and SmOCl. The thorough mineralogical and morphological analysis of the obtained products under these conditions provides valuable insights into their characteristics and potential applications.

Verification of Long‐Term Ensemble Evapotranspiration Hindcast Using a Conditional Nonlinear Optimal Parameter Perturbation Ensemble Prediction Method on the Tibetan Plateau

AbstractIn this research, a conditional nonlinear optimal perturbation related to parameters (CNOP‐P) method is employed to propose an ensemble prediction method titled as the conditional nonlinear optimal perturbation related to parameters ensemble prediction (CNOP‐PEP) method. Within the CNOP‐PEP method, all ensemble members are generated by the CNOP‐P method. To explore the operability and validity of the CNOP‐PEP method, long‐term evapotranspiration (ET) hindcast skill is evaluated at 13 sites on the Tibetan Plateau (TP) during the period of 2001–2018 with a land surface model. Two traditional ensemble prediction methods (the stochastically perturbed parameters (SPP) method and the one‐at‐a‐time (OAT) method) are also applied to assess the ET hindcast skills. The numerical results indicate that the CNOP‐PEP method shows the best hindcast skill for estimated ET at 13 stations on the TP among the three methods (CNOP‐PEP, OAT, and SPP methods) during the period of 2001–2018. This suggests that the CNOP‐PEP method is helpful and effective for long‐term and interannual hydrological predictions, such as long‐term and interannual ET predictions. The numerical results also indicate that ensemble members with certain special properties of fast‐growing types should be selected to implement ensemble prediction compared to these ordinary and traditional samples. The CNOP‐PEP method could supply special samples to improve the ensemble prediction and hindcast skill of hydrological cycle.

Characterization of tensile properties of chain stitch structure fabric with negative Poisson’s ratio yarn

Negative Poisson’s ratio textiles have expanded deformation behavior and special mechanical properties under tension. According to the previous research, the negative Poisson’s ratio effect of fabrics was always lower than yarns. The main reason was that negative Poisson’s ratio yarns showed little structural deformation because of the fabric structures. In this study, chain stitch structure fabrics with negative Poisson’s ratio yarns as inserted weft yarns were designed and prepared. The effect of inserted weft yarns, symmetrical and parallelization arrangement and density on the Poisson’s ratio of chain stitch fabrics were tested and analyzed. The results showed that the negative Poisson’s ratio effect of fabrics was as similar as yarns and yarns in fabric. When the knitting loops provided fixation role in the fabrics, the negative Poisson’s yarns could also present obvious deformation behavior to successfully improve the expand effect of fabrics. Poisson’s ratio and porosity of fabrics under cyclic stretching were carried out to study the structure and property stability. The chain stitch structure fabrics with negative Poisson’s ratio are expected to provide more choices for improving the property and applicability.

Boron Nitride Nanosheets: Thickness‐Related Properties and Applications

AbstractOwing to its exceptional properties and wide‐ranging potential applications from aerospace to medicine, hexagonal boron nitride (h‐BN) has garnered considerable attention over the past decades. Boron nitride nanosheets (BNNSs), atomically thin h‐BN, not only inherit most of the outstanding properties of h‐BN but also exhibit superior characteristics compared to their bulk counterpart due to their reduced thickness, such as special adsorption behaviors and enhanced thermal conductivity. Furthermore, BNNSs display distinct thickness‐dependent properties from graphene and other 2D materials, such as unique mechanical response under indentation. This feature article provides an overview of the thickness‐related special properties of BNNSs, primarily derived from mechanically exfoliated h‐BN single crystals. These properties span various domains, including Raman signatures, molecule adsorption‐induced conformational changes, mechanical properties, thermal conductivity, and thermal expansion coefficients. Moreover, the feature article explores the underlying mechanisms governing these atomic‐scale thickness effects. Leveraging their unique properties, the feature article investigates diverse applications of BNNSs, encompassing surface‐enhanced Raman spectroscopy, metal‐enhanced fluorescence, and isotropic thermal management.

Robust reverse 1-center problems on trees with interval costs

This paper concerns the problem of reducing the edge lengths of a tree in a minimum cost way such that the 1-center function at a predetermined vertex is at most a given threshold value. Moreover, it is assumed that the costs of reducing edge lengths are not exactly determined, but they are estimated within intervals and their total deviation is limited within a given bound. This problem is called the robust reverse 1-center problem on trees with interval costs. We first reformulate the problem as a Stackelberg game and translate it into a univariate optimization problem. Based on the special properties of the feasible set, we can state the corresponding problem as a parameterized minimum cost flow problem. Then we develop an algorithm that solves the problem in O ( n 2 log ⁡ n ) time due to the convexity of the univariate objective function. We finally discuss the problem of improving the international transportation network in Iran as a real-life application.

Replacing a Cysteine Ligand by Selenocysteine in a [NiFe]-Hydrogenase Unlocks Hydrogen Production Activity and Addresses the Role of Concerted Proton-Coupled Electron Transfer in Electrocatalytic Reversibility.

Hydrogenases catalyze hydrogen/proton interconversion that is normally electrochemically reversible (having minimal overpotential requirement), a special property otherwise almost exclusive to platinum metals. The mechanism of [NiFe]-hydrogenases includes a long-range proton-coupled electron-transfer process involving a specific Ni-coordinated cysteine and the carboxylate of a nearby glutamate. A variant in which this cysteine has been exchanged for selenocysteine displays two distinct changes in electrocatalytic properties, as determined by protein film voltammetry. First, proton reduction, even in the presence of H2 (a strong product inhibitor), is greatly enhanced relative to H2 oxidation: this result parallels a characteristic of natural [NiFeSe]-hydrogenases which are superior H2 production catalysts. Second, an inflection (an S-shaped "twist" in the trace) appears around the formal potential, the small overpotentials introduced in each direction (oxidation and reduction) signaling a departure from electrocatalytic reversibility. Concerted proton-electron transfer offers a lower energy pathway compared to stepwise transfers. Given the much lower proton affinity of Se compared to that of S, the inflection provides compelling evidence that concerted proton-electron transfer is important in determining why [NiFe]-hydrogenases are reversible electrocatalysts.

Investigating the Research Path from the Past to the Future of the Common Field of Nanotechnology and Fungi: A Bibliometric Study

Nanoparticles have been considered in many fields such as medicine and industry due to their very small size and their special physicochemical properties. Biosynthesis of nanoparticles has advantages over other methods. This paper examines the bibliography of the relationship between nanotechnology and fungi from 1985 to 2021. Data were collected from three databases consisting of Web of Science, Scopus, and Dimensions. The number and type of documents were examined and then the analysis was continued using VOSviewer and Bibliometrix-package on the documents of the Scopus database. Analysis of 1203 documents from this database showed an upward trend in the publication in recent years. The term “Fungi” was also identified as the keyword index and India as the country with the most published documents. Future research is likely to be on using modern techniques in the study of nanoparticles as well as focusing on other genera of fungi.

Gd and Ni co-doped BiFeO3 ferrite/r-GO nanocomposite for photocatalytic environmental remediation applications

Synergistic effects of the co-doping of rare earth and transition metals on the structural, electrical and optical, in multi-ferroic BiFeO3 nanoferrites (NFs) combined with reduced graphene oxide (r-GO) nanosheets, photocatalytic degradation properties can be boosted. In this current study gadolinium and nickel-co-doped Bi1-xGdxFe1-yNiyO3 were synthesised via the tartaric acid-assisted sol-gel method and their composite Bi1-xGdxFe1-yNiyO3/r-GO with 10 % reduced graphene oxide (r-GO) via the ultra-sonication route. Phase and structural investigation were carried out using x-ray diffraction (P-XRD), Raman scattering, and Fourier transform infrared (FTIR) analysis, which confirms the successful fabrication of co-doping in the rhombohedral geometry of the perovskite-type Bi1-xGdxFe1-yNiyO3. Electrical conductivity of the fabricated composite material was observed to increase because of the co-doping and the addition of r-GO. Photoluminescence (PL) spectra of co-doped and r-GO composite material exhibited a decline in PL intensity because optical bandgap energies exhibited narrowing of 1.99 eV and 1.91 eV respectively, which indicates the excellent separation and stabilization of photo-excited charge pairs. Special conduction properties of r-GO nanosheets improved electrical and optical properties, a well-porous nature, large surface area, lower bandgap, and increased dye degradation in the Bi1-xGdxFe1-yNiyO3/r-GO photocatalyst showing excellent photo-degradation of cationic malachite green (M.G.) dye, achieving a degradation efficiency of 96.4 % under natural solar light. Hence, the photocatalyst shows excellent stability where quenching of radicals using selective scavengers shows that OH* radicals and e−/h+ pairs are primarily involved in the mechanism of photo-degradation in a basic pH medium, making the as-fabricated material a potential material for photo-catalytic environmental remediation.

On Inter‐bubble Hydrodynamics and Cluster Formation in Non‐Newtonian Bubbly Columns: A Review

AbstractA comprehensive understanding of the inter‐bubble dynamics and the cluster formations in non‐Newtonian fluids is pivotal for chemical and biomedical engineering applications. In this review, we summarize current research efforts to provide a fundamental understanding and engineering principles of the interactions between bubbles and the dynamics of bubble clusters in non‐Newtonian fluids. Although the majority of research is still predominantly conducted through experimentation, the significance of computational fluid dynamics in elucidating interaction mechanisms has become increasingly prominent in recent years. Moreover, the gas‐liquid systems reviewed in this paper are driven by gravity, which is closer to the actual industrial processes. We indicate the effects of non‐Newtonian fluid special rheological properties (especially viscoelasticity and shear‐dependent viscosity) on the interaction between multiple bubbles and the formation of clusters. We summarize the main empirical correlations in related research, which are useful for the optimization of industry. Ultimately, we address the current trends, limitations, and future directions in this research field.

Turbulent Rayleigh–Bénard convection in a supercritical [formula omitted]-based binary mixture with cross-diffusion effects

CO2-based binary mixtures are promising in energy engineering to improve efficiencies of thermodynamic cycles where supercritical CO2 prevails. Indeed, under supercritical pressure and transcritical temperature conditions, special thermophysical properties of binary mixtures make the heat transfer process accompanied by enhanced cross-diffusion effects, i.e., the Soret effect and the Dufour effect. Their influences on heat transfer have not been well understood yet. This paper numerically investigates turbulent Rayleigh–Bénard convection in CO2-C2H6 binary mixture. Calculations are performed based on a spectral element method solver considering various temperature differences and pressures. Results indicate that the flow field presents a double-vortex structure. The thickness of the boundary layer is negatively correlated with the flow intensity. Under a positive separation ratio, the concentration gradient induced by cross-diffusion effects enhances buoyancy, which in turn reinforces the natural convection and heat transfer. The enhancement becomes stronger as the critical pressure is approached. Turbulent fluctuations are also strengthened by cross-diffusion effects, except for temperature fluctuations. The unusual reduction in temperature fluctuations is attributed to the increased size of the thermal plume caused by the Dufour effect.