Academic Journals

Synthesis and characterization of gold-conjugated Backhousia citriodora nanoparticles and their anticancer activity against MCF-7 breast and HepG2 liver cancer cell lines

The Psychological Record - Thu, 03/01/2018 - 00:00
Abstract

Environmentally benign-synthesized gold nanoparticles (Au-NPs) have received substantial attention owing to their biomedical applications, particularly in cancer therapy. In the current study, Backhousia citriodora (B. citriodora) leaf extract was applied as a reducing agent for one-pot synthesis of controlled size Au-NPs. The effect of various parameters such as reaction time, pH, and B. citriodora leaf boiling time on the synthesis of Au-NPs was studied. The characterization of the Au-NPs synthesized at 15.0-min incubation time showed colour change because of the surface plasma resonance band around 530.0 nm. TEM photographs showed spherical morphologies with an average size of 8.40 ± 0.084 nm and zeta potential value was − 29.74 mV, indicating stability of the nanoparticles. The biomedical properties of Au-NPs and B. citriodora leaf extract showed strong DPPH radical scavenging. The in vitro anticancer activity determined using MTT assay exhibited that Au-NPs showed a significant dose-dependent reduction in the viability of the MCF-7 breast cancer cell line and the HepG2 liver cancer cell line with IC50 values of 116.65 and 108.21 µg, respectively.

Categories: Academic Journals

Inorganic–organic hybrid wood in response to visible light

The Psychological Record - Thu, 03/01/2018 - 00:00
Abstract

The inorganic–organic hybrid photoresponsive wood was fabricated by incorporating the phosphomolybdic acid (PMA)/polyvinylpyrrolidone (PVP) composites into the multi-scale hierarchical structure of wood using a simple pressure impregnation method. The as-prepared PMA-/PVP-coated wood (PPW) can change their colors in response to visible light. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy demonstrated that the PMA/PVP composites were coated on the wood surfaces successfully and the wood structures were still clearly visible. The atomic force microscopy images confirmed that the surface topography of the samples was changed after visible light irradiation, which was ascribed to the formation of heteropoly blues. The analysis of the color parameters proved that as-prepared PPW possessed the excellent photoresponsive property. The ultraviolet–visible spectra (UV–Vis) and X-ray photoelectron spectroscopy were conducted in order to explore the photoresponsive mechanism, which confirmed the photoreduction reaction occurred, producing the heteropoly blues during the process of visible light irradiation.

Categories: Academic Journals

Innovative synthesis of black zeolites-based kaolin and their adsorption behavior in the removal of methylene blue from water

The Psychological Record - Thu, 03/01/2018 - 00:00
Abstract

An innovative method for preparation of carbon-coated zeolites (black zeolites) has been developed. The method involves dehydration of sucrose on kaolin surfaces followed by hydrothermal treatment. Raw and dealuminated kaolins were used to prepare black zeolites (CZ1 and CZ2, respectively). Characteristics of the black zeolites were influenced by the criteria of the used kaolin. Analyses indicate the formation of Na-A and Na-P zeolites in CZ1. However, Na-A, Na-X, and Na-P zeolites were found in CZ2. Surface areas and pore volume values of CZ2 are lower than the corresponding bare zeolite (Z2). Meanwhile, these values remain approximately the same in case of CZ1 when compared with the corresponding bare zeolite (Z1). Carbon is probably trapped in the wide pores of CZ2 during the preparation process. Contrarily, carbon mainly coats the external surface of CZ1. The adsorption capacities of CZ1 and CZ2 using methylene blue (MB) were determined to be 48.33 and 57.64 mg/g, respectively. The higher estimated value of CZ2 is attributed to its higher surface area. Moreover, the adsorption capacities of black zeolites were much higher than the corresponding uncoated zeolites and the unsupported carbon. These indicate that the supported carbon on zeolites possesses higher exposed surfaces to MB.

Categories: Academic Journals

A biogenic TiO 2 -C-O nanohybrid grown from a Ti 4+ -polymer complex in green tissues of chilis, interface bonding, and tailored photocatalytic properties

The Psychological Record - Thu, 03/01/2018 - 00:00
Abstract

A nanostructured a-TiO2 (anatase) is well known to be a promising material for harvesting photocatalysis in ultraviolet–visible light for its applications. In this article, we report a simple biosynthesis of a stable compound a-TiO2-C-O of small core–shells by a hydrothermal reaction of titanium tetrabutoxide in small tissues (proteins, lipids, or carbohydrates) of green chili (hot) at moderate temperature followed by burning out the organics in a flame in camphor in open air. In a proposed microscopic model, the a-TiO2 is shown to be growing preferentially in support of an inbuilt biogenic 2D layer C–sp 2 (template) in the coherent (101) facets in a controlled shape of small cuboids (8–15 nm sizes), with a joint C–sp 2 charge/spin layer in an a-TiO2-C-O hybrid composite phase. A thin residual ‘Ti4+ -O-C’ surface layer lasts, with a rocking of a ‘C-O cage’ on the Ti4+ ions of 285 cm−1 frequency, in the samples heated at ≤ 600 °C in air. It is found to be promoting a markedly enhanced photocatalytic response in degrading methylene blue dye and 2-chlorophenol under a visible light irradiation. The results are described with N2 sorption hysteresis, microscopic images, Raman/XPS (X-ray photoelectron spectroscopy) bands, and ultraviolet–visible light absorption/emission spectra in the samples prepared of varied microscopic surface layers.

Categories: Academic Journals

A self-assembled smart architecture against drilling predation in a Pinctada maxima shell: protective mechanisms

The Psychological Record - Thu, 03/01/2018 - 00:00
Abstract

The aim of this study is to examine the response of Pinctada maxima shell to drilling predation, focusing on the underlying protective mechanisms. The shell exhibits a self-assembled smart architecture with a highly multilayered structure. The outer layer is composed of a prismatic structure, and the inner nacreous layer consists of several sub-layers that contain normal brick-like platelets and unique convex lens-like platelets, with myostracal layers laying in between them. Such a smart architecture provides several fundamental protective mechanisms against drilling penetration. First, the occurrence of multiple microcracking and the deformability of platelets in the nacre structure with brick-like platelets can effectively lock the damage locally during drilling penetration. Second, a few myostracal layers embedded within the nacre structure as a disguise of fresh body may induce the driller to inject the toxic salivary secretions, thus protecting the platelets at the bottom of the hole. Third, a new type of platelets with a convex lens-like shape is observed for the first time to be positioned in the internal part of the shell. This layer can effectively prevent the final attack due to its remarkable plastic deformation capacity or bendability via converting a part of tensile stresses into compressive stresses through interfacial sliding and rotation among the convex lens-like platelets. The findings of the present study can pave the way for the development of bioinspired advanced engineering structures with superior protectability against the penetration.

Categories: Academic Journals

Manufacturing process of AA5083/nano-γAl 2 O 3 localized composite metal foam fabricated by friction stir processing route (FSP) and microstructural characterization

The Psychological Record - Thu, 03/01/2018 - 00:00
Abstract

The aluminum alloy AA5083 is a technologically important structural alloy as it is lightweight, with outstanding weldability and formability, moderate corrosion resistance and strength, making it suitable for a wide range of marine and transportation applications. In the present study, AA5083/nano-γAl2O3 composite metal foam was fabricated using a friction stir processing route (FSP). More precisely, the paper presents a first attempt to use grooves for the integration of the foaming and stabilizing agent on the metal foam precursor by FSP. The implementation of grooves allows to control the amount of foaming, integrates the stabilizing particles within the precursor and permits the production of localized metal foams. Unlike the commonly used manufacturing processes, only one plate is required for the production of the precursor sample in the proposed process. Therefore, this process can be easily implemented in the industrial sector. Furthermore, γ-Al2O3 nanostructured reinforcement, which is characterized by increased interfacial energy, was utilized as a stabilizing agent. The precursor specimens were manufactured by mixing blowing agent powder (0.4% w/w TiH2) and stabilization agent nanopowder (2% w/w γ-Al2O3) into the 5083 aluminum alloy matrix using FSP. The effects of the number of FSP passes and the foaming conditions (holding temperature and time) on the pore density, morphology and distribution were investigated. The microstructure and porosity evolution of the so-obtained metal foam was also examined and analyzed. Results indicate that, following the foaming procedure, a porosity of 60% and an equivalent pore diameter ranging from 0.2 to 3.3 mm can be achieved. Moreover, the microstructure was found to be closely related to microhardness distribution perpendicular to the traversing direction of the FSP tool for both precursor and foamed specimens.

Categories: Academic Journals

Fabrication of periodically micropatterned magnetite nanoparticles by laser-interference-controlled electrodeposition

The Psychological Record - Thu, 03/01/2018 - 00:00
Abstract

This paper introduces a laser-interference-controlled electrochemical deposition method for direct fabrication of periodically micropatterned magnetite (Fe3O4) nanoparticles (NPs). In this work, Fe3O4 NPs were controllably synthesized on the areas where the photoconductive electrode was exposed to the periodically patterned interferometric laser irradiation during the electrodeposition. Thus, the micropattern of Fe3O4 NPs was controlled by interferometric laser pattern, and the crystallization of the particles was controlled by laser interference intensity and electrochemical deposition conditions. The bottom-up electrochemical approach was combined with a top-down laser interference methodology. This maskless method allows for in situ fabrication of periodically patterned magnetite NPs on the microscale by electrodeposition under room temperature and atmospheric pressure conditions. In the experiment, Fe3O4 NPs with the mean grain size below 100 nm in the pattern of 5-μm line array were achieved within the deposition time of 100 s. The experiment results have shown that the proposed method is a one-step approach in fabricating large areas of periodically micropatterned magnetite NPs.

Categories: Academic Journals

Ion imprinting approach for the fabrication of an electrochemical sensor and sorbent for lead ions in real samples using modified multiwalled carbon nanotubes

The Psychological Record - Thu, 03/01/2018 - 00:00
Abstract

A highly selective electrochemical sensor for lead ions was fabricated using mutiwalled carbon nanotube as the backbone. The binding sites for lead ions were sculpted with lead ion as template and NNMBA-crosslinked polyacrylamide as the solid matrix on MWCNTs (MWCNT-IIP) on lead ion sensing and selectivity. System without lead ions was also synthesized (MWCNT-NIP). To check the role of the MWCNT, ion-imprinted polymer (IIP) and non-imprinted polymer (NIP) without MWCNT were also synthesized. In both systems, the ion-imprinted polymer showed high specificity towards lead ion. The developed materials were characterized using various analytical techniques. The sites left by the lead ions in MWCNT-IIP are highly selective to lead ions and resulted in electrochemical response when a platinum electrode was modified with this nanostructure. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were employed to explore the features of the developed electrochemical sensor towards lead ions. The developed material could sense Pb(II) ions in the presence of other metal ions, and the limit of detection was found to be 2 × 10−2 μM. The sensing system could successfully discriminate Pb(II) ions from different real samples which includes environmental sample such as lake water, mining effluent, food sample and cosmetics. Also the same was exploited for the extraction of Pb(II) ions. The recoveries from various samples using MWCNT-IIP were > 99%. But those of MWCNT-NIP were in the range 62–68%.

Categories: Academic Journals

Microwave absorption performance of iron oxide/multiwalled carbon nanotubes nanohybrids prepared by electrostatic attraction

The Psychological Record - Thu, 03/01/2018 - 00:00
Abstract

Designing the structure with dielectric loss and magnetic loss integrated contributes to expansion of microwave absorption bandwidth. Nanohybrid materials composed of iron oxide (Fe3O4) and multiwalled carbon nanotubes (MWCNTs) were prepared through a newly electrostatic attraction method as high-performance microwave absorbers in the 2–18 GHz band. The nanohybrids are characterized by transmission electron microscopy, X-ray diffraction, and vector network analysis. Microstructural analysis showed that Fe3O4 and MWCNTs were well-connected through electrostatic interaction in the nanohybrids. The experimental results indicated that MWCNTs/PEDOT: PSS/Fe3O4 possessed higher reflection loss and broader absorption bandwidth than MWCNTs. MWCNTs/SDBS/Fe3O4 had better matching of dielectric loss and magnetic loss, the absorption bandwidth below − 10 dB was up to 8 GHz. This work further reveals that the novel electrostatic attraction method could be efficiently enlarged electromagnetic wave attenuation performance in absorb materials.

Categories: Academic Journals

Efficient and selective separation of U(VI) and Th(IV) from rare earths using functionalized hierarchically mesoporous silica

The Psychological Record - Thu, 03/01/2018 - 00:00
Abstract

The separation and recovery of U(VI) and Th(IV) from rare earths are very important to avoid environmental pollution. A functional fibrous hierarchically bimodal mesoporous silica (F-SiO2-DP) as an high efficient adsorbent for selective adsorption of uranium and thorium, which had hierarchically bimodal mesoporous structure and specific surface area of ca. 474.1 m2 g−1, was prepared by post-modification method using 2,9-diamide-1,10-phenanthroline. The synthesized adsorbent was characterized by HR-TEM, SEM, FT-IR, N2 adsorption–desorption, TGA techniques, XRD and NMR spectroscopy. The effects of pH, contact time, initial U(VI) and Th(IV) concentration, temperature and the presence of competitive metal ions on U(VI) and Th(IV) adsorption behavior were studied in detail. The hierarchically bimodal mesoporous structure endows F-SiO2-DP with faster adsorption rate, which can reach equilibrium within 10 min, as well as higher adsorption capacities for U(VI) and Th(IV) compared with unimodal mesoporous silica like MCM-41 functionalized with 2,9-diamide-1,10-phenanthroline. The maximum adsorption capacities reach 416 mg g−1 for U(VI) at pH 5.0 and 277 mg g−1 for Th(IV) at pH 3.8, which are much higher than most of previously reported mesoporous silica-based adsorbents. The selectivity coefficient of U(VI) and Th(IV) over Ce(III), Nd(III), Sm(III), Eu(III), Gd(III), Y(III) and Yb(III) is all larger than 9 at pH 3.8, indicating that F-SiO2-DP possesses a good simultaneously selective adsorption performance for U(VI) and Th(IV). This work demonstrates that F-SiO2-DP with hierarchically bimodal mesoporous structure has promising application in adsorption and separation of actinides from lanthanides, which is crucial to the environmental protection.

Categories: Academic Journals

Characterization of hollow silica–polyelectrolyte composite nanoparticles by small-angle X-ray scattering

The Psychological Record - Thu, 03/01/2018 - 00:00
Abstract

Hollow silica–polyelectrolyte composite nanoparticles were prepared using templates of spherical polyelectrolyte brushes which consist of a polystyrene (PS) core and a densely grafted linear poly(acrylic acid) shell. The obtained hollow particles were systematically studied by small-angle X-ray scattering (SAXS) in combination with other characterization methods such as transmission electron microscopy and dynamic light scattering. The hollow structure formed by dissolving the PS core was confirmed by the reduction of electron density to zero in the cavity through fitting SAXS data. SAXS revealed both the inward and outward expansions of the hollow silica–polyelectrolyte composite particles upon increasing pH from 3 to 9, while further increasing pH led to the partial dissolution of silica layer and even destruction of the hollow structure. SAXS was confirmed to be a unique and powerful characterization method to observe hollow silica nanoparticles, which should be ideal candidates for controlled drug delivery.

Categories: Academic Journals

Toughening mechanisms of low transformation temperature deposited metals with martensite–austenite dual phases

The Psychological Record - Thu, 03/01/2018 - 00:00
Abstract

Four groups of low transformation temperature (LTT) deposited metals with different Ni contents were prepared, and their microstructures were characterized by scanning electron microscopy, X-ray diffraction, transmission electron microscopy, and electron backscattered diffraction techniques. The relationship between the microstructures of the mixed martensite–retained austenite (RA) phases and their impact toughness were investigated; it was found that the impact toughness of the LTT deposited metals increased with increasing volume fraction of RA. In particular, its magnitude was higher for the specimens containing the lath martensite, interlath RA, and intercellular RA phases than for those composed of the lath martensite and interlath RA. The toughness of the lath martensite–RA mixed microstructure was primarily determined by the presence of the soft RA phase (containing film interlath RA and stringer intercellular RA), while lath martensite phase characterized by a high density of tangled dislocations and relatively small amount of twinned substructures resulted in the embrittlement of the LTT deposited metals. The dislocation absorption by the retained austenite and transformation-induced plasticity (TRIP) effects of RA were found to be main reasons for the improvement in materials toughness during crack initiation stage. The subsequent crack propagation proceeds via the TRIP and the transformation-induced crack termination mechanisms; it is also significantly affected by the increased fraction of martensite/RA boundaries. The optimization of the RA fraction in the martensite–RA dual structure is a potentially effective method for the toughness enhancement of the LTT deposited metals containing martensite–RA dual phases.

Categories: Academic Journals

Improving the high-frequency magnetic properties of as-deposited CoFe films by ultra-low gas pressure

The Psychological Record - Thu, 03/01/2018 - 00:00
Abstract

CoFe films without buffer layers were deposited at different ultra-low argon pressures ranging from 0.085 to 0.847 mTorr. This pressure range was one to two orders lower than the normal sputtering pressure. As a consequence, the static magnetic properties, including coercivity and magnetic anisotropy field, were improved with decrease argon pressure. The high-frequency permeability spectra showed that the resonance frequency and the damping factor of the films also reached optimal values at ultra-low pressure. Basing on atomic force microscopy observations, we attributed the excellent properties to the improved morphologies of the films and released internal stress.

Categories: Academic Journals

A cobalt porphyrin-based metal organic framework/multi-walled carbon nanotube composite electrocatalyst for oxygen reduction and evolution reactions

The Behavior Analyst - Thu, 03/01/2018 - 00:00
Abstract

We report the synthesis of a composite from cobalt porphyrin-based metal organic framework (MOF) and multi-walled carbon nanotube (MWCNT), possessing good catalytic activity toward oxygen reduction (OR) and oxygen evolution (OE) processes. A 3-D porous coordination network (PCN) with 3-D nanochannels was synthesized using ultrastable Zr6 clusters and tetrakis(4-carboxyphenyl)porphyrin cobalt(II). Located in the backbone of MOF, cobalt porphyrins as the active centers are easily accessible to the reactants. The composite exhibits smaller overpotentials and higher current for OR and OE reactions compared to the commercial Pt/C catalyst. A proton-coupled electron transfer mechanism has been suggested due to the pH dependence of water oxidation on the electrocatalyst. Furthermore, the stability of the catalyst has been verified by various techniques. Our designed heterogeneous, inexpensive, and stable electrocatalyst is a proper candidate for acidic fuel cells and water splitting devices under near neutral condition without requirement of pyrolysis process.

Categories: Academic Journals

High-temperature stress-dependent piezoelectric and dielectric coefficient of soft Pb(Zr,Ti)O 3

The Behavior Analyst - Thu, 03/01/2018 - 00:00
Abstract

The dielectric constant and the direct piezoelectric coefficient as well as the macroscopic ferroelastic behavior of co-doped Pb(Zr,Ti)O3 were characterized from 25 to 350 °C as a function of uniaxial compressive stress. Experimental results show a decrease in the small signal piezoelectric coefficient and the permittivity with stress, although there exists a uniaxial compressive stress that significantly reduces the variation of the piezoelectric coefficient with increasing temperature, making it a possible method for sensors that operate over a large temperature range. In the vicinity of the depolarization temperature, the piezoelectric response rapidly decreases. This temperature, however, was observed well below the temperature at maximum permittivity. Experimental results reveal that uniaxial compressive stress shifts the temperature at maximum permittivity, giving insight into the effect of stress on the phase transition behavior in Pb(Zr,Ti)O3, but does not apparently influence the depolarization temperature.

Categories: Academic Journals

Synthesis and characterization of gold-conjugated Backhousia citriodora nanoparticles and their anticancer activity against MCF-7 breast and HepG2 liver cancer cell lines

The Behavior Analyst - Thu, 03/01/2018 - 00:00
Abstract

Environmentally benign-synthesized gold nanoparticles (Au-NPs) have received substantial attention owing to their biomedical applications, particularly in cancer therapy. In the current study, Backhousia citriodora (B. citriodora) leaf extract was applied as a reducing agent for one-pot synthesis of controlled size Au-NPs. The effect of various parameters such as reaction time, pH, and B. citriodora leaf boiling time on the synthesis of Au-NPs was studied. The characterization of the Au-NPs synthesized at 15.0-min incubation time showed colour change because of the surface plasma resonance band around 530.0 nm. TEM photographs showed spherical morphologies with an average size of 8.40 ± 0.084 nm and zeta potential value was − 29.74 mV, indicating stability of the nanoparticles. The biomedical properties of Au-NPs and B. citriodora leaf extract showed strong DPPH radical scavenging. The in vitro anticancer activity determined using MTT assay exhibited that Au-NPs showed a significant dose-dependent reduction in the viability of the MCF-7 breast cancer cell line and the HepG2 liver cancer cell line with IC50 values of 116.65 and 108.21 µg, respectively.

Categories: Academic Journals

Inorganic–organic hybrid wood in response to visible light

The Behavior Analyst - Thu, 03/01/2018 - 00:00
Abstract

The inorganic–organic hybrid photoresponsive wood was fabricated by incorporating the phosphomolybdic acid (PMA)/polyvinylpyrrolidone (PVP) composites into the multi-scale hierarchical structure of wood using a simple pressure impregnation method. The as-prepared PMA-/PVP-coated wood (PPW) can change their colors in response to visible light. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy demonstrated that the PMA/PVP composites were coated on the wood surfaces successfully and the wood structures were still clearly visible. The atomic force microscopy images confirmed that the surface topography of the samples was changed after visible light irradiation, which was ascribed to the formation of heteropoly blues. The analysis of the color parameters proved that as-prepared PPW possessed the excellent photoresponsive property. The ultraviolet–visible spectra (UV–Vis) and X-ray photoelectron spectroscopy were conducted in order to explore the photoresponsive mechanism, which confirmed the photoreduction reaction occurred, producing the heteropoly blues during the process of visible light irradiation.

Categories: Academic Journals

Innovative synthesis of black zeolites-based kaolin and their adsorption behavior in the removal of methylene blue from water

The Behavior Analyst - Thu, 03/01/2018 - 00:00
Abstract

An innovative method for preparation of carbon-coated zeolites (black zeolites) has been developed. The method involves dehydration of sucrose on kaolin surfaces followed by hydrothermal treatment. Raw and dealuminated kaolins were used to prepare black zeolites (CZ1 and CZ2, respectively). Characteristics of the black zeolites were influenced by the criteria of the used kaolin. Analyses indicate the formation of Na-A and Na-P zeolites in CZ1. However, Na-A, Na-X, and Na-P zeolites were found in CZ2. Surface areas and pore volume values of CZ2 are lower than the corresponding bare zeolite (Z2). Meanwhile, these values remain approximately the same in case of CZ1 when compared with the corresponding bare zeolite (Z1). Carbon is probably trapped in the wide pores of CZ2 during the preparation process. Contrarily, carbon mainly coats the external surface of CZ1. The adsorption capacities of CZ1 and CZ2 using methylene blue (MB) were determined to be 48.33 and 57.64 mg/g, respectively. The higher estimated value of CZ2 is attributed to its higher surface area. Moreover, the adsorption capacities of black zeolites were much higher than the corresponding uncoated zeolites and the unsupported carbon. These indicate that the supported carbon on zeolites possesses higher exposed surfaces to MB.

Categories: Academic Journals

A biogenic TiO 2 -C-O nanohybrid grown from a Ti 4+ -polymer complex in green tissues of chilis, interface bonding, and tailored photocatalytic properties

The Behavior Analyst - Thu, 03/01/2018 - 00:00
Abstract

A nanostructured a-TiO2 (anatase) is well known to be a promising material for harvesting photocatalysis in ultraviolet–visible light for its applications. In this article, we report a simple biosynthesis of a stable compound a-TiO2-C-O of small core–shells by a hydrothermal reaction of titanium tetrabutoxide in small tissues (proteins, lipids, or carbohydrates) of green chili (hot) at moderate temperature followed by burning out the organics in a flame in camphor in open air. In a proposed microscopic model, the a-TiO2 is shown to be growing preferentially in support of an inbuilt biogenic 2D layer C–sp 2 (template) in the coherent (101) facets in a controlled shape of small cuboids (8–15 nm sizes), with a joint C–sp 2 charge/spin layer in an a-TiO2-C-O hybrid composite phase. A thin residual ‘Ti4+ -O-C’ surface layer lasts, with a rocking of a ‘C-O cage’ on the Ti4+ ions of 285 cm−1 frequency, in the samples heated at ≤ 600 °C in air. It is found to be promoting a markedly enhanced photocatalytic response in degrading methylene blue dye and 2-chlorophenol under a visible light irradiation. The results are described with N2 sorption hysteresis, microscopic images, Raman/XPS (X-ray photoelectron spectroscopy) bands, and ultraviolet–visible light absorption/emission spectra in the samples prepared of varied microscopic surface layers.

Categories: Academic Journals

A self-assembled smart architecture against drilling predation in a Pinctada maxima shell: protective mechanisms

The Behavior Analyst - Thu, 03/01/2018 - 00:00
Abstract

The aim of this study is to examine the response of Pinctada maxima shell to drilling predation, focusing on the underlying protective mechanisms. The shell exhibits a self-assembled smart architecture with a highly multilayered structure. The outer layer is composed of a prismatic structure, and the inner nacreous layer consists of several sub-layers that contain normal brick-like platelets and unique convex lens-like platelets, with myostracal layers laying in between them. Such a smart architecture provides several fundamental protective mechanisms against drilling penetration. First, the occurrence of multiple microcracking and the deformability of platelets in the nacre structure with brick-like platelets can effectively lock the damage locally during drilling penetration. Second, a few myostracal layers embedded within the nacre structure as a disguise of fresh body may induce the driller to inject the toxic salivary secretions, thus protecting the platelets at the bottom of the hole. Third, a new type of platelets with a convex lens-like shape is observed for the first time to be positioned in the internal part of the shell. This layer can effectively prevent the final attack due to its remarkable plastic deformation capacity or bendability via converting a part of tensile stresses into compressive stresses through interfacial sliding and rotation among the convex lens-like platelets. The findings of the present study can pave the way for the development of bioinspired advanced engineering structures with superior protectability against the penetration.

Categories: Academic Journals

Pages

Subscribe to Kentucky Association for Behavior Analysis aggregator - Academic Journals