Diameter Of Spherical Particles Research Articles

Low-cost preparation and characterization of new CuO/ZnO and Cu3N/ZnO nanocomposites

CuO/ZnO and Cu3N/ZnO nanocomposites were prepared in a three-step synthesis consisting of the co-precipitation of Cu2+ and Zn2+ hydroxide carbonates (Cu/Zn-Carb) followed by their thermal treatment first in air and second in gaseous ammonia. The morphology and phase composition of the hydroxide carbonates were determined by the Cu:Zn molar ratio and the presence of polyvinylpyrrolidone (PVP) acting as a capping agent, respectively. The Cu/Zn-carbonates could be annealed in the air at 550 °C either as powders or as thin films. The latter were deposited on a silicon substrate using a choice of spin- or dip-coating techniques. The resulting CuO/ZnO samples were heated under gaseous ammonia at 300 °C in the final step of the process to form Cu3N/ZnO nanocomposites. The fabricated samples were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) with energy dispersive X-ray analysis (EDX), X-ray photoelectron spectroscopy (XPS), thermogravimetric − differential thermal analysis (TG-DTA) and infrared spectroscopy (IR). SEM and XRD analysis indicates that the average diameter of spherical particles was about 130 nm (CuO/ZnO) and 100 nm (Cu3N/ZnO), composed of crystallites with 10–20 nm sizes. The thermal treatment under air and NH3 did not affect the morphology of the composites. The implication is, therefore, that the shape and size of CuO/ZnO oxide and Cu3N/ZnO nitride/oxide composite nanostructures are determined at the point of hydroxide carbonate coprecipitation and can be controlled during precursor synthesis. This has significant ramifications for the reproducible fabrication of nanocomposite films of precise stoichiometry and bespoke morphology.

Part I: determination of a structure/property transformation mechanism responsible for changes in the point of zero change of anatase titania with decreasing particle size.

Below a diameter of approximately 28 nm, the surface crystal structure of anatase titania is known to change. These changes include surface bond lengths and crystal lattice parameter expansion/contractions. Concurrent with these structure changes, the materials point of zero charge (PZC) has been observed to shift toward lower pH values. Therefore, the objective of this work was to determine if a correlation exists between these known structural changes and the shift in the materials PZC values with decreasing particle size. To achieve this a method was developed to identify and minimize the effect of all known variables, save particle size, affecting the materials pHPZC. This led to the discovery of two regions for point of zero charge. Above the average spherical primary particle diameter ≅ 29 nm for anatase titania, denoted as Region I, PZC values remain constant. In Region I the materials surface crystal structure and properties were also found to remain constant. Below the average spherical primary particle diameter ≅29 nm is the second zone, defined as Region II, where pHPZC values decrease almost linearly. An examination of possible surface structure factors and properties responsible for the shift in these PZC values (Region II) identified three underlying causes. These being changes in the materials band gap (i.e. surface bond lengths), lattice parameters and bond ionic content.

In-situ formation of Azo dye capped-silver nanoparticles and their nanocomposite with reduced graphene oxide for dye degradation

This work entails a novel and simple chemical method for preparation of silver and reduced graphene oxide nanocomposite (Ag@rGO NCs). In nanocomposite fabrication, the silver salt was reduced through Eriochrome Black T (EBT) and Methylene Orange (MO) respectively in the presence of graphene oxide. The mechanism of interaction was understood by simulating the system using first-principle Density Functional Theory approach. The formation of silver nanoparticles was confirmed through UV–visible spectroscopy by observing the plasmonic peak. By X-Ray Diffraction (XRD) analysis, the crystallite size of silver nanoparticles was calculated to be 9.83 nm and 12.5 nm respectively, for two nanocomposites. Statistically, spherical surface morphology and average particles diameter of silver was assessed to be 38 nm and 42 nm from scanning electron microscopy (SEM) analysis. Energy dispersive spectroscopy (EDS) confirmed the presence of silver in the nanocomposites. Fourier Transform Infrared (FTIR) and RAMAN Spectroscopy confirmed the interaction mechanism of GO and Ag NPs by changes in surface groups. In photocatalysis, the dye degradation efficiency of Ag@rGO NCs have been studied against Methylene Blue (MB) and found to be 69.7% and 87.9% approximately.

Preparation of Yb–Sb co-doped Ti/SnO2 electrode for electrocatalytic degradation of sulfamethoxazole (SMX)

To efficiently break down residual sulfonamide antibiotics in environmental water, Yb–Sb co-doped Ti/SnO2 electrodes were fabricated using a solvothermal method. The effect of different amounts of Yb doping on the properties of the electrodes was studied. When the atom ratio of Sn: Yb is 100 : 7.5 in the preparation, the as-obtained coral-like electrodes (denoted as Yb 7.5%) possessed the smallest diameter of spherical particles on the surfaces, to result in the denser surface, highest electrocatalytic activity and smallest resistance of the electrode. As anode for electrocatalytic degradation of sulfamethoxazole, the Yb 7.5% electrode showed a degradation rate of 92% in 90 min, which was much higher than that of Yb 0% electrode (62.7% degradation rate). The electrocatalytic degradation of sulfamethoxazole was investigated with varying current densities and initial concentrations. Results indicated that the degradation process followed pseudo-first-order kinetics, and the degradation rate constants for Yb 7.5% and Yb 0% electrodes were 0.0278 min−1 and 0.0114 min−1, respectively. Furthermore, the service life of Ti/SnO2 electrodes was significantly improved after Yb doping, as demonstrated by accelerated life testing. Yb 7.5% exhibited a service life that was 2.7 times longer than that of Yb 0%. This work offers a new approach to construct Yb–Sb co-doped Ti/SnO2 electrodes with excellent electrooxidation activity and high stability for the electrochemical oxidation degradation of sulfamethoxazole.

Structure-Property Relationships of CO2 Absorbing Core-Shell Microparticles with Encapsulated Ionic Liquid.

The demand for new ionic liquid (IL)-based systems to selectively sequester carbon dioxide from gas mixtures has prompted the development of individual components involving the tailored design of IL themselves or solid-supported materials that provide excellent gas permeability of the overall material as well as the ability to incorporate large amounts of ionic liquid. In this work, novel IL-encapsulated microparticles comprising a cross-linked copolymer shell of β-myrcene and styrene and a hydrophilic core of the ionic liquid 1-ethyl-3-methylimidazolium dicyanamide ([EMIM][DCA]) are proposed as viable materials for CO2 capture. Water-in-oil (w/o) emulsion polymerization of different mass ratios of β-myrcene to styrene (i.e. 100/0, 70/30, 50/50, 0/100) yielded IL-encapsulated microparticles, where the encapsulation efficiency of [EMIM][DCA] was dependent on the copolymer shell composition. Thermal analysis using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) revealed that both thermal stability and glass transition temperatures depend on the mass ratio of β-myrcene to styrene. Images from scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to observe the microparticle shell morphology as well as measure the particle size perimeter. Particle sizes were found to be between 5 and 44 μm. CO2 sorption experiments were conducted gravimetrically using TGA instrumentation. Interestingly, a trade-off between CO2 absorption capacity and ionic liquid encapsulation was observed. While increasing the β-myrcene content within the microparticle shell increases the amount of encapsulated [EMIM][DCA], the observed CO2 absorption capacity did not increase as expected due to reduced porosity compared to microparticles with higher styrene content in the microparticle shell. [EMIM][DCA] microcapsules with a 50/50 weight ratio of β-myrcene/styrene showed the best synergistic effect between spherical particle diameter (32.2 μm), pore size (0.75 μm), and high CO2 sorption capacity of ∼0.5 mmol CO2/g sample within a short absorption period of 20 min. Therefore, core-shell microcapsules composed of β-myrcene and styrene are envisioned as a promising material for CO2 sequestration applications.

Evaluation of Absorbed Energy in High-Velocity Particle Impact for Aero-Engine Materials

A single particle impact testing system was developed to estimate an absorbed energy in particle perforation process of aero-engine materials. Thin target plates of 0.1-1 mm thickness were impacted by a 3 mm diameter spherical particle. A wide range of impact velocities from 50-375 m/s was covered using a compressed gas gun. First, particle impact tests were conducted on aluminum and copper plates to evaluate the validity of the experimental system. The experimental results show that there is no significant difference in the effect of the particle impact velocity on the absorbed energy of aluminum and copper, and the ballistic limit can be reasonably estimated based on a simple energy balance equation. Second, impact tests were conducted on TiAl alloys and Ni-based alloys. There was no clear ballistic limit for the TiAl alloys, and the absorbed energy tended to increase as the particle impact velocity increased. The absorbed energy of the TiAl alloy was half that of the Ni-based alloy for specimens of the same thickness. Radial and petal-shaped cracks were observed in the Ni-based alloys after impact tests, while brittle cracks, fractures, and scattering of debris were observed at the periphery of the penetration hole in the TiAl alloys.

Silver nanoparticles and cellulose microfiber micro-composite from banana (Musa acuminata) waste: green synthesis, antioxidant property and antimicrobial capacity

The green chemistry promotes the synthesis of nanomaterials from plant extracts as a new climate intelligent alternative to the use of conventional protocols based on costly and toxic chemicals. Therefore, this research was undertaken to analyses the efficiency of banana (peels and rachis) waste extracts in the production of a micro-composite composed by silver nanoparticles (AgNPs) and cellulose microfibers (CMF) respectively. Results showed the synthesis of 24 nm diameter spherical particles AgNPs, with a peak of absorbance at 410 nm, in (v/v) water:ethanol extracts of banana peels at a final dilution of 3.10-2. Concomitantly, 50-350 µm in length and 5-10 µm of diameter CMF were obtained via the oxalic acid hydrolysis of the oven-dried banana rachis. The micro-composite (AgNPs-CMF) and AgNPs displayed an active reducing capacity over 60% determined by the DPPH test, and active bacterial activity against E. Coli and S. aureus in Petri dishes. Overall results support the use of banana waste for the synthesis of AgNPs and CMF for industrial purposes.

Validation of the local thermal equilibrium assumption for free convection boundary layer flow over a horizontal cylinder embedded in an infinite saturated porous medium

This study numerically investigated the validity of the local thermal equilibrium model for free convection over a horizontal cylinder embedded in an infinitely packed bed of spherical particles saturated with Newtonian fluid. The local thermal non-equilibrium and Forchhemimer-Brinkman extended Darcy model were used by considering the boundary-layer theory assumptions and were solved with the implicit Keller box finite difference scheme. The governing parameters considered are the porosity, thermal conductivity ratio, Rayleigh number, Prandtl number, the ratio of cylinder diameter to spherical particle diameter and Biot number. The results showed the two parameters of conductivity ratio and Biot number can significantly affect the other parameters. For low Biot number and conduction coefficient ratio, the local thermal non-equilibrium assumption was inapplicable in almost all cases. Significantly, for high values of the conductivity ratio and Biot number, the assumption that the fluid and solid matrix are isothermal, could be used in almost all cases studied. Furthermore, increasing the amount of Rayleigh number, Porosity and Prandtl increased the temperature difference between the solid and fluid phases. In addition, increasing the ratio of cylinder diameter to particle diameter reduced the temperature difference between the two phases. The average temperature difference between fluid and solid can have the most changes as follows: It can experience 200% growth when the Prandtl number changes from 2 to 7. Also, it can reduce by 33% by increasing the Bio number from 0.01 to 10. In addition, the temperature difference of two phases can be increased by 7 and 0.5 times by increasing the porosity from 0.25 to 0.85 and increasing the ratio of cylinder diameter to particle diameter from 20 to 100, respectively.

A Tool for Rapid Analysis Using Image Processing and Artificial Intelligence: Automated Interoperable Characterization Data of Metal Powder for Additive Manufacturing with SEM Case

A methodology for the automated analysis of metal powder scanning electron microscope (SEM) images towards material characterization is developed and presented. This software-based tool takes advantage of a combination of recent artificial intelligence advances (mask R-CNN), conventional image processing techniques, and SEM characterization domain knowledge to assess metal powder quality for additive manufacturing applications. SEM is being used for characterizing metal powder alloys, specifically by quantifying the diameter and number of spherical particles, which are key characteristics for assessing the quality of the analyzed powder. Usually, SEM images are manually analyzed using third-party analysis software, which can be time-consuming and often introduces user bias into the measurements. In addition, only a few non-statistically significant samples are taken into consideration for the material characterization. Thus, a method that can overcome the above challenges utilizing state-of-the-art instance segmentation models is introduced. The final proposed model achieved a total mask average precision (mAP50) 67.2 at an intersection over union of 0.5 and with prediction confidence threshold of 0.4. Finally, the predicted instance masks are further used to provide a statistical analysis that includes important metrics such as the particle size distinction.

Halloysite based geopolymers filled with wax microparticles as sustainable building materials with enhanced thermo-mechanical performances

This work proposes a novel protocol for the fabrication of halloysite based geopolymers filled with beeswax microparticles obtained from Pickering emulsions. The actual filling of the microwax into the geopolymers has been demonstrated by using several techniques, including thermal analyses, spectroscopies, microscopies and contact angle experiments. According to the morphological and structural investigations, microwax spherical particles (diameter ranging between ca. 3 and 5 µm) have been homogeneously dispersed within the geopolymeric network conferring excellent properties to the hybrid geopolymers in terms of mechanical performances and heat storage capacity although their low content in the hybrid material. For comparison, we have prepared and characterized hybrid geopolymers obtained by the loading of variable amounts of beeswax within the geopolymeric matrix. Reliable enhancements of the flexural characteristics and heat absorption capacity have been achieved only with a large content of beeswax. Moreover, the removal of microvax and wax from the hybrid geopolymers has been obtained by rinsing with ethanol. The washed geopolymers have been characterized by wettability and water vapour permeability experiments, which have been proved that the beeswax has been removed and the porosity of the materials can be controlled by the initial composition of the hybrid geopolymers.In conclusion, this paper puts forward an easy strategy to fabricate composite geopolymers with heat storage capacity due to presence of phase change materials (microwax particles) confined in the geopolymeric network. Their enhanced flexural performances make the hybrid geoppolymers suitable as building materials.

Continuous flow synthesis of plasmonic gold patches and nearly-complete nanoshells on polystyrene core particles

We describe the development of a T-mixer based continuous flow process for the coating of 86–500 nm diameter spherical polystyrene particles with thin gold patches by heterogeneous nucleation and growth. After establishing a suitable flow rate for good mixing and sufficiently uniform product morphology we systematically investigate the main reaction parameters. This reveals a considerable tunability of the patch morphology and, by virtue of the localized surface plasmon resonance of gold, the optical properties of the product dispersions. In order to further widen the range of nanostructures accessible by our process, a second T-mixer was added. This introduced new gold precursor, leading to further growth of the patches that were formed after the first mixer. By this approach, nearly-complete gold nanoshells could be produced in high yield on both small and large core particles, without the unwanted production of free-standing gold nanoparticles. Due to the pronounced optical properties of nearly-complete gold nanoshells on small core particles, we could estimate from electrodynamic simulations the equivalent shell thickness to be as low as 8.6 nm. This is significantly thinner than can be routinely achieved using the standard seeded growth approach to synthesise gold nanoshells. Our results are therefore highly promising for the gram-scale synthesis of plasmon resonant nanostructures with designed optical properties.

Diamond and methane formation from the chemical decomposition of polyethylene at high pressures and temperatures

Polyethylene (C2H4)n was compressed to pressures between 10 and 30 GPa in a diamond anvil cell (DAC) and laser heated above 2500 K for approximately one second. This resulted in the chemical decomposition of the polymer into carbon and hydrocarbon reaction products. After quenching to ambient temperature, the decomposition products were measured in the DAC at pressures ranging from ambient to 29 GPa using a combination of x-ray diffraction (XRD) and small angle x-ray scattering (SAXS). XRD identified cubic diamond and methane as the predominant product species with their pressure–volume relationships exhibiting strong correlations to the diamond and methane equations of state. Length scales associated with the diamond products, obtained from SAXS measurements, indicate the formation of nanodiamonds with a radius of gyration between 12 and 35 nm consistent with 32–90 nm diameter spherical particles. These results are in good agreement with the predicted product composition under thermodynamic and chemical equilibrium.

Inverse effect of packing density on shear wave velocity of binary mixed soils with varying size ratios

This study evaluates the dependency of shear wave velocity (Vs) on packing density of binary mixed soils with varying size ratios of the small to large particles. 4 mixtures with different size ratios (sr = median grain size of small particles / median grain size of large particles) of 0.699, 0.282, 0.157, and 0.014 were prepared, bender element tests were then carried out to examine the variation of Vs according to the void ratio or relative density. The results demonstrate that when sr > 0.414 (the theoretical pore size ratio, which is the ratio between the diameter of interstitial sphere and the diameter of spherical particles, for simple cubic packing) and when sr < 0.155 (the theoretical pore size ratio for cubic tetrahedral packing), the measured Vs increases with increasing packing density due to the increase in interparticle coordination. However, when 0.155 < sr < 0.414 and the finer fraction < threshold finer fraction, the Vs of the tested mixture decreases with increasing packing density. This inverse impact of packing density on Vs may be attributed to the decrease in pore size between large particles in this situation and the consequent active disruption of direct contacts between large particles.

Morphological study of the particle-to-fiber transition threshold during electrohydrodynamic processing of chitosan solution

In this work, solutions of low molecular weight chitosan with the concentration of 4 and 5 wt.% were subjected to electrohydrodynamic forming at the feed rate of 0.1 and 0.2 ml/h. Using a statistical analysis of the electron scanning microscopy data, it was shown that at the concentration of 4 wt.%, spherical particles of two types are formed: most of the particles are with the average diameter about of 260 nm, and particles with a larger diameter of about 480 nm. A transition through the particle-to-fiber threshold was observed with an increase in the concentration of the solution to 5 wt.%. This led to the formation of both spherical particles with a monomodal distribution and average diameter of 207 nm and elongated particles of a fiber-like shape with diameter of 157 nm and length of 1401 nm. At the same time, an increase in the solution feed rate resulted in a strong decrease in the average diameter of spherical particles to 150 nm and an elongation of fiber-like objects by 1.5 times. The particle-to-fiber threshold can be observed when the dynamic viscosity of the solution changes in the range of about 10–14 cP.

Nickel-doped monoclinic WO3 as high performance anode material for rechargeable lithium ion battery

• Monoclinic WO 3 nanoparticles are successfully doped by 10 wt% of Nickel element. • The N10mWO 3 delivers 1st /2nd discharge capacities of 1287/1012 mAh g −1 at 100 mA g −1 . • The N10mWO 3 exhibits the capacity retention of 79.60% at 100 mA g −1 after 500 cycles. • The N10mWO 3 shows high rate capability, 650.2 mAh g −1 even at 1000 mA g −1 . The anode materials are one of the critical components in rechargeable lithium ion batteries (LIBs). The monoclinic tungsten trioxide (mWO 3 ) is introduced as interesting anode electrode for LIBs due to its good structure for intercalation and de-intercalation of lithium ions, high abundance and various oxidation state of tungsten and etc. In this study, we prepare and investigate the effect of various amounts of nickel dopant on characteristics and electrochemical properties of the mWO 3 as the anode electrode in a rechargeable LIB. The experimental investigations confirm that the number of nickel atoms has a remarkable effect on controlling spherical particle diameter, crystallite size, and electrochemical properties of mWO 3 . The electrochemical results demonstrate that the 10 wt% nickel dopant leads to make the highest improvements for electrochemical behaviors of mWO 3 . The sample exhibits higher 1 st /2 nd electrochemical capacities (1287/1012 mAh g −1 at 100 mA g −1 ), good cycle life (capacity retention of 79.60% after 500 cycles at 100 mA g −1 ), and better rate capability (650.2 mAh g −1 even at 1000 mA g −1 ) among un-doped and doped mWO 3 samples, including 5 and 20 wt% nickel atoms. These improvements can be related to the spherical morphology of nanoparticles and high electrical conductivity making by nickel dopant, which is beneficial to enhance lithium-ion diffusion and electron transfer in the monoclinic structure of WO 3 . The anode electrode reported here exhibits excellent properties in LIBs for various energy storage applications..

Settling of Spherical Particles in High Viscosity Friction Reducer Fracture Fluids

Investigating the key factors that impact fluid rheology and proppant static settling velocity in high viscosity friction reducers (HVFRs) is a critical aspect for successful proppant transport in hydraulic fracture treatment. In this study, the rheological properties of HVFRs were tested at various temperature ranges (i.e., 25, 50, 75, and 100 °C) and different HVFR concentrations (i.e., 1, 2, 4, and 8 gpt). Three sizes of spherical particle diameters (i.e., 2, 4, and 6 mm) were selected to measure the static settling velocity. The fracture fluid was tested in two fracture models: an unconfined glass model and a confined rectangular model with two fracture widths (7 and 10 mm). The settling velocity in the confined and unconfined models was measured using an advanced video camera. HVFR results exhibited acceptable thermal stability even at higher temperatures, also the viscosity and elasticity increased considerably with increasing concentration. Increasing the temperature cut the friction reducer efficiency to suspend the spherical particles for a significant time, and that was observed clearly at temperatures that reached 75 °C. Spherical particles freely settled in the unconfined model due to the absence of the wall effect, and the settling velocity decreased significantly as the HVFR concentration increased. Additionally, the fracture angularity substantially slowed the proppant settling velocity due to both the wall effect and several types of friction. This research provides insights into the rheological parameters of a high viscosity friction reducer as a fracturing fluid and its efficiency in transporting particles in bounded and unbounded fracture networks.

Processing of Alumina Reinforced Copper Metal Matrix Composite by Selective Laser Melting Technology

For the development of the additive technologies it is necessary to expand the range of the used materials. One of the most promising directions is the creation of products from composite materials. In this work copper-alumina composite powder was prepared by ball milling, and used in selective laser melting, to produce a composite material. The raw powder materials consisted of the gas atomized Cu powder (with the regular spherical shape and mean particle diameter of 32 μm) and alumina powder, produced by condensation of vapor on electrostatic filter (average particle size is about 220 nm). The alumina weight ratio was 5%. Four 30x10x6 mm copper-alumina specimens were manufactured. The scanning electron microscopy was used for the analysis of composite microstructure. Obtained copper-alumina composite material has higher hardness, in comparison with cast copper (HRB is 60 and 45, respectively).

Shape anisotropy-governed locomotion of surface microrollers on vessel-like microtopographies against physiological flows

Surface microrollers are promising microrobotic systems for controlled navigation in the circulatory system thanks to their fast speeds and decreased flow velocities at the vessel walls. While surface propulsion on the vessel walls helps minimize the effect of strong fluidic forces, three-dimensional (3D) surface microtopography, comparable to the size scale of a microrobot, due to cellular morphology and organization emerges as a major challenge. Here, we show that microroller shape anisotropy determines the surface locomotion capability of microrollers on vessel-like 3D surface microtopographies against physiological flow conditions. The isotropic (single, 8.5 µm diameter spherical particle) and anisotropic (doublet, two 4 µm diameter spherical particle chain) magnetic microrollers generated similar translational velocities on flat surfaces, whereas the isotropic microrollers failed to translate on most of the 3D-printed vessel-like microtopographies. The computational fluid dynamics analyses revealed larger flow fields generated around isotropic microrollers causing larger resistive forces near the microtopographies, in comparison to anisotropic microrollers, and impairing their translation. The superior surface-rolling capability of the anisotropic doublet microrollers on microtopographical surfaces against the fluid flow was further validated in a vessel-on-a-chip system mimicking microvasculature. The findings reported here establish the design principles of surface microrollers for robust locomotion on vessel walls against physiological flows.

A novel covalent triazine framework developed for efficient determination of 1-naphthol in water.

Covalent triazine frameworks (CTFs) are an exciting new class of porous organic materials with excellent chemical stability and easy functionalization. In recent years, CTFs have gained increasing attention in electrochemical detection of environmental contaminants. Herein, a novel CTF material was successfully synthesized by the solvothermal condensation of 1,3,5-tris-(4-aminophenyl)triazine (TAPT) and 2,3,6,7-tetrabromonapthalene dianhydride (TBNDA) for determination of 1-naphthol in water. The obtained CTF, denoted here as TATB, comprised uniformly sized spherical particles (diameter 0.5-2 μm) with a highly conjugated structure that benefited electron transfer processes when applied to a glassy carbon electrode (GCE). A TATB/GCE working electrode showed excellent catalytic activity for the oxidation of 1-naphthol, with the oxidation peak current being directly proportional to the 1-naphthol concentration in the range of 0.01-10.0 μM, with a detection limit of 5.0 nM (S/N = 3). In addition, the TATB/GCE sensor possesses excellent reproducibility, sensitivity, and selectivity for 1-naphthol determination in aqueous solution. This work highlights the potential of CTFs in electrochemical sensing, whilst also demonstrating a sensitive and stable sensor platform for 1-naphthol detection in water.

Dimensionless critical shear stress for sediment particles under varying slope conditions

One of the most fundamental and practical issues in sedimentology is making predictions on initial sediment motion. Many widely used bedload sediment-transport models are based on the concept that sediment transport either begins at or can be scaled by, a constant value of the dimensionless critical shear stress. Flume experiments were conducted for three different diameters of spherical particles under varying channel slope. A model is presented to determine the dimensionless critical shear stress for the incipient motion of spherical particles on nonhorizontal slopes. The findings of the study have been illustrated with mathematical relationships and graphical representations for various combinations of input variables.