Triangular Particles Research Articles

Shape-driven entropic self-assembly of an open, reconfigurable, binary host-guest colloidal crystal.

Entropically driven self-assembly of hard anisotropic particles, where particle shape gives rise to emergent valencies, provides a useful perspective for the design of nanoparticle and colloidal systems. Hard particles self-assemble into a rich variety of crystal structures, ranging in complexity from simple close-packed structures to structures with 432 particles in the unit cell. Entropic crystallization of open structures, however, is missing from this landscape. Here, we report the self-assembly of a two-dimensional binary mixture of hard particles into an open host-guest structure, where nonconvex, triangular host particles form a honeycomb lattice that encapsulates smaller guest particles. Notably, this open structure forms in the absence of enthalpic interactions by effectively splitting the structure into low- and high-entropy sublattices. This is the first such structure to be reported in a two-dimensional athermal system. We discuss the observed compartmentalization of entropy in this system, and show that the effect of the size of the guest particle on the stability of the structure gives rise to a reentrant phase behavior. This reentrance suggests the possibility for a reconfigurable colloidal material, and we provide a proof-of-concept by showing the assembly behavior while changing the size of the guest particles in situ. Our findings provide a strategy for designing open colloidal crystals, as well as binary systems that exhibit co-crystallization, which have been elusive thus far.

Production of silver nanoparticles via green method using banana raja peel extract as a reducing agent

In this study, biosynthesis of silver nanoparticles using the extract of a local banana peel (variant name: Raja) as bio-reductor was carried out. This study aimed to determine the effect of two different ratios of Banana Peel Extract (BPE)/distilled water on the synthesis of silver nanoparticles. The two of BPE/water ratios were 1% (v/v) and 5%(v/v), named as Sample A and Sample B, respectively. Whereas, the concentrations of AgNO3 solution as the precursor were varied as follows: 0.125; 0.1; 0.075; and 0.05 M. The synthesized colloidal silver nanoparticles were characterized using a UV-Vis spectrometer, while the BPE solution was analyzed using Fourier Transform Infra-Red (FT-IR) to study its functional groups. While, the solid silver nanoparticles was characterized using a Scanning Electron Microscopy (SEM) with an Energy-dispersive X-ray spectroscopy (EDX) analysis. The UV-Vis spectrometer results qualitatively showed that sample A produced better silver nanoparticles than that of sample B. All samples showed absorbance peaks at wavelength of 450 nm. It was found that the highest absorbance value (i.e. 1.59) occurred at sample A with a concentration of AgNO3 solution 0.1 M. Additionally, FT-IR analysis result showed the presence of a hydroxyl group specifically for alcohols as phenols, which indicated the possibility of polyphenol compounds. The SEM micrograph showed that some of the silver nanoparticles were in the shape of tetrahedron or triangular like particle and spherical The SEM image analysis results using ImageJ software showed that most of the silver nanoparticles produced had the size of 100-300 nm. Furthermore, the EDX analysis result showed a peak count at 3 keV, which confirmed the formation of silver nanoparticles.

Investigation of transient gas-solid flow characteristics and particle erosion in a square gate valve

As an important component in industrial pneumatic conveying pipelines, gate valves are seriously affected by gas–solid two-phase flow. Solid matter not only affects the flow resistance characteristics and flow field distribution of the gate valve, but also collides with the gate cavity and the gate plate surface, sliding friction and other effects, leading to serious wear and tear of the internal valve body, resulting in the fall off of the gate valve wall material, affecting the sealing performance of the gate valve, reducing its service life, and affecting the safety and reliability of the pipeline transportation system. Based on the consideration of gas–solid two-phase flow and particle–wall collision, combined with wear prediction model, the flow field, particle trajectory, flow resistance characteristics and wear distribution of main wall in gate valve pipeline system are studied in this paper. The accuracy of this method is verified by flow resistance experiment. The results show that the existence of groove structure at the bottom of gate valve has an important influence on the distribution of flow field inside gate valve and the wear of main wall in the flow field of pneumatic conveying pipeline. At the bottom of the groove, there is a low pressure zone, which makes the gas pressure decrease and increases the cost of pneumatic conveying when the fluid passes through the gate valve; the distribution of velocity and flow field is not uniform, resulting in swirling flow; there are different sizes of swirling flow and secondary flow, resulting in unstable flow; at the groove, particles impact on the groove perpendicular to the flow direction at a larger speed under the action of swirling flow. On the wall, the wear is the most serious here, which reduces the sealing performance of the gate valve. In the groove, the velocity distribution decreases, resulting in the accumulation of triangular particles.

Melting and solidification within an energy storage unit with triangular fin and CuO nano particles

Abstract In this attempt, the heat stored and released units with combination of copper oxide (CuO) nanoparticles and triangular fin on the process of charging and discharging in the triplex pipe has been scrutinized. The middle tube is full of RT35 and CuO was dispersed to enhance its conductivity. Water flows via the outer and inner tube. Impacts of combining nanoparticles and fin on the period of various times of the Phase Change Material (PCM) solidification and melting process were scrutinized. The outputs depicts that the existence of nanoparticles reduces the discharging process as well as melting phenomena. The results indicate that impose of triangular fins can enhance solidification rate about 40.75% and with inclusion of nanoparticles, solidification time declines about 44.88%. Temperature of PCM at end of discharging declines about 13.34% when φ = 0.02. As fraction of nanofluid augments, melting time declines from 5.616 min to 5.4 min. Temperature of PCM augments about 5.81% as time increases from 1 to 5 min for melting case. Stored energy is an increasing function of time during melting while augments of φ leads to reduction of this factor.

Microstructure and mechanical properties of WC–Ni multiphase ceramic materials with NiCl2·6H2O as a binder

Abstract High-density WC–Ni composite ceramics were prepared by cold isostatic pressing–vacuum pressureless sintering–hot isostatic pressing with tungsten carbide (WC) powder and NiCl2·6H2O as a binder. Results show that with an increase in the contents of Ni in the metal binder phase, the relative density of WC–Ni composite ceramics is improved, and the formation of the carbon-deficient W2C phase is reduced. There is no W2C generated in the WC–1 wt% Ni material. At high temperatures, the Ni phase changes into the liquid phase and enters between the WC particles, thereby promoting the close alignment of the WC particles. Moreover, the WC particles will be more closely aligned under their own surface tension and capillary action, thereby promoting the densification of WC–Ni composite ceramics. The WC–0.5 wt% Ni composite ceramics are fully dense and show the best comprehensive performance with a microhardness of 23.0 GPa, a fracture toughness of 5.28 MPa m1/2, and a flexural strength of 1,396.58 MPa. WC–Ni composite ceramics are mainly composed of elongated triangular prism WC particles and Ni phase. Transgranular fracture was the main fracture mode of WC–Ni multiphase ceramic materials with a small amount of intergranular fracture due to the existence of the Ni phase. Such a fracture mode can increase the flexural strength of the composite material.

Toxicity of composition of non-metal nanoparticles in pig kidney culture cell

The results of the study have established that the composition of iodine and sulfur nanoparticles (NPs) contains triangular particles with the size from 30 to 50 nm, circular and irregular particles with size of 60–70 nm, as well as circular and irregular aggregates of these particles ranging in size from 150 to 200 nm. Free triangular NPs having length of the side 30 nm, free irregularly shaped NPs with size from 10 to 60 nm as well as circular and irregular aggregates of these NPs sized from 150 to 200 nm have been found in the composition of selenium and iodine NPs. Threshold limit value for embryonic swine kidney cell line was 5 μg/cm3 for the composition of iodine and sulfur NPs and 0.5 μg/cm3 for the composition of selenium and iodine NPs. It has been shown that both compositions of nonmetal NPs are not toxic for white mice at the dose of 2000 mg/kg if administered orally. Nonmetal NPs show high cytotoxicity, but they are not toxic during oral administration. Relatively high cytotoxicity implies that nonmetal NPs should have high biological activity not only eukaryotic cell cultures, but also in cultures of microorganisms, while nontoxicity during oral administration implies that they should have high biocompatibility. The results of the study show that nonmetal NPs are perspective for the development of antimicrobial agents and for various applications in agriculture.

Stable and highly efficient MoS2/Si NWs hybrid heterostructure for photoelectrocatalytic hydrogen evolution reaction

We report, the fabrication of molybdenum disulphide (MoS2) wrapped silicon nanowires (Si NWs) for visible light driven water splitting applications. The morphological and elemental studies ensure the vertical alignment of Si NWs wrapped with 2D layered MoS2. The photoelectrocatalytic (PEC) results evidence the significant enhancement in performance of MoS2/Si NWs based hybrid photocathode with ~300 mV (under reversible hydrogen electrode (RHE)) anodic shift in onset potential as that of pristine Si NWs (+0.194 V vs. RHE), and the current density of −26.5 mA/cm2 was achieved at the applied bias of 0 V vs. RHE. Further, the electrochemical impedance studies ensure the interface resistance-free charge transfer between Si NWs and electrolyte via 2D MoS2 layer which provokes rapid hydrogen production. The wrapping of Si NWs with MoS2 protects the superlative photocathode from harsh acid electrolyte environment. The overgrown MoS2 triangular particles with active sulphur edge sites are found to eventually augment the solar hydrogen evolution rate. Further, the PEC performance of our MoS2/Si NWs is also comparable with stable Pt/Si NWs photoelectrode. It is note-worthy that, MoS2/Si NWs hybrid heterostructure would be a potential candidate in future large scale, low cost and day-to-day solar water splitting applications.

A simple method of growing endotaxial silver nanostructures on silicon for applications in surface enhanced Raman scattering (SERS)

Endotaxial structures are related to the growth of precipitate phases in the bulk matrix having a coherent interface with the surrounding. In general, sophisticated physical vapor deposition techniques, like molecular beam epitaxy (MBE) in ultra-high vacuum (UHV) or ion implantation followed by high-temperature annealing are used to grow endotaxial structures. Here, we have shown that a simple electroless deposition followed by rapid thermal annealing process can generate triangular-shaped endotaxial Ag nanostructures along with spherical Ag nanoparticles on the planar silicon surface. Remarkably, compared to only Ag spherical particles, a silicon surface covered with spherical plus triangular-shaped nanoparticles shows significant SERS enhancement revealing the crucial role of the endotaxial triangular Ag nanostructures in SERS. By studying the aging effect, we have demonstrated that embedded triangular endotaxial particles are structurally more stable than the spherical nanoparticles residing on the surface revealing a robust route of fabricating SERS substrate where stability is an important issue. We presume that the nanogaps between the spherical and triangular endotaxial particles act as one of the major sources of “hot spots” where the sharp edges of the triangular geometry pose favorable situation for SERS enhancement observed in the present case.

Investigation of In Vitro Antioxidant and Antibacterial Potential of Silver Nanoparticles Obtained by Biosynthesis Using Beech Bark Extract

Green synthesis is one of the rapid and best ways for silver nanoparticles (AgNP) synthesis. In the present study, synthesis and bioactivity of AgNPs has been demonstrated using water beech (Fagus sylvatica L.) bark extract. The physical and chemical factors such as time, metal ion solution, and pH, which play a vital role in the AgNPs synthesis, were assessed. The AgNPs were characterized by ultraviolet-visible (UV-Vis) spectrometry, Fourier transform infrared spectroscopy (FT-IR), and transmission electron microscopy (TEM). Antioxidant and antimicrobial activity of the obtained AgNPs was evaluated. AgNPs were characterized by color change pattern, and the broad peak obtained at 420–475 nm with UV-Vis confirmed the synthesis of AgNPs. FT-IR results confirmed that phenols and proteins of beech bark extract are mainly responsible for capping and stabilization of synthesized AgNPs. TEM micrographs showed spherical or rarely polygonal and triangular particles with an average size of 32 nm at pH = 9, and 62 nm at pH = 4. Furthermore, synthesized AgNPs were found to exhibit antioxidant activity and have antibacterial effect against Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA), Escherichia coli, and Pseudomonas aeruginosa. These results indicate that bark extract of F. sylvatica L. is suitable for synthesizing stable AgNPs, which act as an excellent antimicrobial agent.

Short-term Load Prediction of Cloud Computing Based on Fuzzy Information Granulation SVM

In order to predict the short-term load variation range and trend of cloud computing, this paper proposed a prediction model based on information granulation support vector machine (IGSVM). Taking the historical load value as a sample to do simulation training, through Gravitational Search Algorithm (GSA) to optimize the parameters of SVM, and make regression prediction to three parameters of triangular fuzzy particles, Low, R and Up, to obtain the variation range and trend of short-term load. The result is consistent with the actual situation, which verifies the validity of the model and provides the basis for actual operation and maintenance.

Second harmonic generation from complementary triangular Au metamaterials

Sub-wavelength square array of a triangular Au platelet and its complementary structure (i.e. that of a triangular hole in a square film of Au) are compared in terms of second harmonic generation efficiency for fundamental light in the near infrared and visible region of spectrum for normal incidence. Electric field strength around the convex corners of a triangular particle is at least 10 times larger than the one around the concave corners of triangular hole in the complementary structure. Nevertheless the SHG intensity at the respective resonant frequency is found to be comparable, which are numerically estimated by an overlap integral of nonlinear polarization and electric field at the SHG frequency in the nonlinear optical scattering theory originally proposed by Roke et al. (Phys. Rev. B 70, 115106 (2004)). The reason is due to the large electric field strength at the sides of the triangular hole at the resonance frequency, which compensates the suppressed electric field at the concave corners in the overlap integral.

Intelligent prediction of surrounding rock deformation of shallow buried highway tunnel and its engineering application

The potential arch crown settlement is one of the most hazardous factors in shallow-buried tunnel excavations. Therefore, accurate prediction of arch crown settlement range is essential to minimize the possible risk of damage. Considering the time series regression characteristics of deformation of surrounding rock in shallow-buried tunnels, the Support Vector Machine (SVM) information granulation method was newly applied in this study for deformation prediction of surrounding rock. First, obtain monitoring data of the tunnel arch crown settlement. Second, transform the data of three arch crown settlement into a triangular fuzzy particle. The three parameters, Low, R, and Up in the fuzzy particle represent the minimum, average and maximum value of the settlement of the arch crown in three days. Then, use the SVM to predict the Low, R, and Up values of the tunnel arch crown settlement. Finally, the established prediction model of surrounding rock with SVM information granulation method was applied to the Panlongshan tunnel on the line of the Qinglan expressway in China and prediction results agree well with practical situations, which means the method of SVM information granulation used in this study could provide relatively high accuracy when applied to deformation prediction of surrounding rock in shallow-buried tunnels. Meanwhile, the SVM information granulation method is simple, feasible and easy to implement. The presented method has been validated as an effective method of deformation prediction for surrounding rock, which also has good prospects for further engineering applications.

Second-harmonic generation from complementary Au metasurfaces with triangular resonators

We demonstrate the contribution of local electric near-field enhancement around convex and concave corners at resonant fundamental excitation to the second-harmonic (SH) emission intensity using complementary Au metasurfaces with triangular resonators (i.e., a square array of triangular particles and a square array of a thin film of Au with a triangular hole). It is demonstrated that for an electric near-field enhancement at normal incidence, the fundamental excitation around convex corners of a triangular particle is many times stronger than the one around concave corners of a complementary triangular hole. Notwithstanding, the SH emission intensity of the complementary structure is found to be comparable at their respective optimal resonant fundamental excitations. SH emission intensity is numerically estimated using mode overlap between the fundamental and SH waves. The comparable SH emission intensity is found to originate from the strong electric near-field enhancement on the sides of a triangular hole with zero curvature, which compensates for the field suppression around the concave corners of the triangular hole. In addition, the strong electric near-field enhancement around convex corners of a triangular particle (accompanied with suppression around the sides of the triangular particle) and field suppression around concave corners of a triangular hole (accompanied with strong field enhancement around the side of the triangular hole) are demonstrated using Babinet’s principle.

Magnetization Reversal of Permalloy Microparticles with the Configuration Anisotropy by Magnetic-Force Microscopy

Abstract—Magnetic force microscopy has been used to study the distribution of the magnetization in permalloy microparticles with a configurational anisotropy. The triangular particles with different degrees of concavity of the lateral sides have been studied. An analysis of the results enables us to state that the particles can be in several quasi-homogeneous stable states. It is shown that the particle magnetization reversal can occur both stepwise and also via an intermediate state in the dependence on the particle orientation. It is demonstrated that the quasi-homogeneous magnetization orientation in a particle can be changed by a magnetic-force microscope probe.

Electronic polarization of zinc nitride nanoparticles for interfacial tension reduction in enhanced oil recovery

Even though the application of nanoparticles (NPs) in enhanced oil recovery (EOR) has been reported, but the development of different novel and efficient materials and their potential in EOR still need to explore. In this work, zinc nitride (Zn3N2) were developed and explored for enhanced oil recovery. Zinc nitride (Zn3N2) nanoparticles with triangular shape morphology were synthesized using sol-gel auto combustion method. The prepared NPs were characterized using X-ray diffraction and Field emission scanning electron microscopy for crystal structure, shape and size. The results reveal the formation of Zn3N2 triangular shape particles. Zn3N2 nanofluids of different concentrations were prepared and their effect on oil-water interfacial tension (IFT) under electromagnetic waves (EM) was investigated. The reduction in IFT was observed by introducing nanoparticles. It was found that Zn3N2 nanofluid under EM waves can bring an additional reduction in IFT. The value of IFT at 0.1 wt % of Zn3N2 under EM waves of frequency 2.2 MHz was 0.55 mN/m which is 75 % reduction.

The effect of the triangular and spherical shaped CuSbS2 structure on the electrical properties of Au/CuSbS2/p-Si photodiode

CuSbS2 (Chalcostibite) crystals were synthesized by the hot-injection method as triangular and spherical shaped structures. The crystals were inserted by spin coating technique as interfacial layers between Au metal and p-Si to investigate their electrical and photoresponse properties via I-V measurements under various light intensities. The XRD measurements were performed to show the crystalline structure of the spherical and triangular CuSbS2. The TEM images confirmed the triangular and spherical particle structures of the CuSbS2 crystals. The I-V measurements were performed under dark, 20–100 mW light intensities with 20 mW interval for spherical and triangular CuSbS2 photodiodes. In addition, diode parameters were extracted and discussed in the details. The results highlighted that triangular and spherical shaped structures have good photoresponse to the illumination and can be employed in the photodiode and photodetector applications.

Emulsion Droplets Stabilized by Close-Packed Janus Regular Polygonal Particles.

In Pickering-Ramsden emulsions, the packing structure of the colloidal particles at the liquid-liquid (or liquid-gas) interface significantly affects the structure and behavior of the emulsion. Here, using a series of platelike particles with regular polygonal shapes and Janus amphiphilicity, we created emulsion droplets stabilized by close-packed polygonal particles at the interface. The systematic variation of the particle morphology shows that the geometrical features of the regular polygons in (curved) planar packing dominate over the self-assembled structures. The structures are tessellations of triangular, square, and hexagonal particles at the surface for large droplets and regular tetrahedral, cubic, and dodecahedral particle shells of triangular, square, and pentagonal particles for small droplets, respectively. This work creates the possibility of geometrically designing the structure and functionality of emulsions.

Residual stress generation in metal matrix composites after cooling

ABSTRACTEffects of reinforcements’ shapes, sizes and contents on (a) von-Mises stress along a horizontal line in MMCs, (b) directions and distributions of principal stresses inside particles, matrix and interface, and (c) distribution of thermal residual stress in MMCs were analysed in this investigation. It was found that the matrix–particle interfaces experience a sudden change of von-Mises stress which depends on the reinforcement shape. The smoothest change of stress occurred in triangle particle-reinforced MMCs. However, the highest stress was concentrated at the corners of the triangular particles. The directions of stress vectors depend on the shape of the particles. The extent of the von-Mises stress increases with the increase in reinforcement content and a decrease in particles size at constant content.

Nanoporous Ag-Au Bimetallic Triangular Nanoprisms Synthesized by Galvanic Replacement for Plasmonic Applications

Galvanic replacement is a versatile method of converting simple noble metallic nanoparticles into structurally more complex porous multimetallic nanostructures. In this work, roughened nanoporous Ag-Au bimetallic triangular nanoprisms (TNPs) are synthesized by galvanic replacement between smooth Ag triangular plates and AuCl4− ions. Transmission electron microscope and the elementary mapping measurements show that numerous protrusions and pores are formed on the {111} facets, and Ag and Au atoms are homogeneously distributed on the triangular plates. Due to the additional “hot spots” generated by the surface plasmon coupling of the newly formed protrusions and pores, the roughened nanoporous Ag-Au TNP aggregates demonstrate a higher surface-enhanced Raman scattering enhancement factor (seven times larger) and better reproducibility than that of smooth Ag triangular particle aggregates. These synthesized roughened nanoporous Ag-Au bimetallic TNPs are a promising candidate for the applications in analytical chemistry, biological diagnostics, and photothermal therapy due to their excellent plasmonic performances and good biocompatibility.

Compaction-induced stress in geosynthetic-reinforced granular base course – A discrete element model

A discrete element method (DEM) model was used to simulate the development of compaction-induced stress in a granular base course, with and without geogrid reinforcement. The granular base course was modeled as a mixture of uniformly sized triangular particles. The geogrid was modeled as a series of equally spaced balls that interact with each other through long-range interaction contacts. The long-range interaction contact was also used to simulate a deformable subgrade. The compactor was modeled as a solid cylinder rolling at a constant speed. The DEM model shows that the geogrid-reinforced granular base course gains additional compaction-induced stress due to the residual tensile stress developed in the geogrid. The residual tensile stress in the geogrid increases with the number of compaction passes. Parametric analyses were also conducted to assess the effects of geogrid stiffness and subgrade modulus on the compaction-induced stress.