The moving die rheometer technique (MDR) is used to measure the elastic and viscous components of rubber. The analysis of the rheometry and the kinetic behavior can be used to obtain mathematical models to predict the viscosity of elastomers as a function of the temperature, the time and the degree of curing. These predictions allow the control, the optimization and the design of the process. In this research the phenomenological model of Kamal-Sourour was used to describe the curing kinetics, while the Carreau Macosko model was used to describe the viscous behavior of an ethylene - propylene diene industrial type compound (EPDM). The mathematical parameters for each model where determined by using non-linear regression techniques. Since the viscosity increases significantly while the curing rate decreases, we proposed a mathematical model based on the Carreau expression in order to consider the influence of the kinetic of curing in the apparent viscosity behavior. It was found that after the curing rate reaches its maximum the viscosity tends to infinity; that is, the chemical transition process known as fluidity point or gel point occurs in the vicinity of maximum curing rate. According to the results, it is concluded that rubber viscosity is well described by considering the curing variations; the fluidity point in the vulcanization process can also be obtained by the practical method of phenomenological approach.

With their abilities of self-renewal and pluripotency to differentiate into all three germ layers, human induced pluripotent stem cells (hiPSCs) are a promising cell source for cell-based drug and implant testing. However, the large-scale expansion and maintenance of hiPSCs requires following strict protocols. There is high demand for advanced cell culture systems capable of generating high-quality hiPSCs to meet application requirements. In this study, we probe the possibility of modifying polymeric substrates for maintaining the self-renewal and pluripotency of hiPSCs. Here, polydopamine (PDA) was employed to immobilize the Laminin 521 (LN521) onto the surface of polyethylene terephthalate (PET). An aqueous solution of dopamine with concentrations ranging from 0 to 2.0 mg/mL was applied on PET surfaces. These PDA-modified surfaces were further functionalized with LN521. Surface wettability was evaluated by measuring the water contact angle (WCA) and surface properties of the modified substrate were analyzed using an atomic force microscope (AFM). Initial hiPSC attachment (1h after seeding) and cell proliferation were evaluated by counting the total cell number. The maintenance of pluripotency was evaluated at designed time points. WCA of the PDA-LN521 surfaces gradually decreased from 62.1°±6.3° to 8.1°±2.9°. The maximum peak-to-valley height roughness (Rt) of those surfaces determined by AFM increased in a dopamine-concentration-dependent manner, ranging from 43.9±1.6 nm to 126.7±7.6 nm. The Young’s modulus of these surfaces was substantially increased from 0.98±0.36 GPa to 4.81±2.41 GPa. There was a significant enhancement (13.0±7.2% and 24.2±8.1%) of hiPSC adhesion on PDA-LN521 (dopamine concentration at 0.125 and 0.25 mg/mL). When increasing the dopamine concentration to 0.5 and 1.0 mg/mL, there was no further increase in hiPSC adhesion on PDA-LN521 surfaces. Moreover, hiPSC proliferation was remarkably enhanced on PDA-LN521 surface (dopamine solution at concentration from 0.125 to 1.0 mg/mL). Pluripotency of hiPSCs was not affected by PDA treatment. In conclusion, PDA-mediated surface modification is an effective approach for the robust expansion and maintenance of hiPSCs on polymer substrates.

We report a novel strategy to render stainless steel (SS) a more versatile material that is suitable to be used as the substrate for preparing electrodes for efficient hydrogen evolution by interface engineering. Our strategy involves the growth of carbon nanotubes (CNTs) by atmospheric pressure chemical vapor deposition (APCVD) as the interface material on the surface of SS. We optimized the procedure to prepare CNTs/SS and demonstrate a higher activity of the CNTs/SS prepared at 700 °C for the hydrogen evolution reaction (HER) when compared to samples prepared at other temperatures. This can be attributed to the higher number of defects and the higher content of pyrrolic N obtained at this temperature. Our strategy offers a new approach to employ SS as a substrate for the preparation of highly efficient electrodes and has the potential to be widely used in electrochemistry.

The dissolution of the United Kingdom’s vitrified high-level-waste simulant, CaZn MW28, was investigated following the Product Consistency Test-B protocol for 112 d at 90 °C and in ultra-high-quality water. Residual rate dissolution (stage II) and rate resumption (stage III), after 28 d, was observed. Thermodynamic modelling suggested that solutions were saturated with respect to Mg- and Zn-bearing phases, and the presence of Mg- and Zn-smectite clays was tentatively observed. The formation of these phases was concurrent with a significant increase in the dissolution rate, similar to Stage III behavior seen in other nuclear waste simulant glass materials, indicating that the addition of Mg and Zn to high-level-waste glass (7.3 wt. % combined) significantly influences the dissolution rate.

In recent years, investigations of the phase transition behavior of semiconducting nanoparticles under high pressure has attracted increasing attention due to their potential applications in sensors, electronics, and optics. However, current understanding of how the size of nanoparticles influences this pressure-dependent property is somewhat lacking. In particular, phase behaviors of semiconducting CdS nanoparticles under high pressure have not been extensively reported. Therefore, in this work, CdS nanoparticles of different sizes are used as a model system to investigate particle size effects on high-pressure-induced phase transition behaviors. In particular, 7.5, 10.6, and 39.7 nm spherical CdS nanoparticles are synthesized and subjected to controlled high pressures up to 15 GPa in a diamond anvil cell. Analysis of all three nanoparticles using in-situ synchrotron wide-angle X-ray scattering (WAXS) data shows that phase transitions from wurtzite to rocksalt occur at higher pressures than for bulk material. Bulk modulus calculations not only show that the wurtzite CdS nanomaterial is more compressible than rocksalt, but also that the compressibility of CdS nanoparticles depends on their particle size. Furthermore, sintering of spherical nanoparticles into nanorods was observed for the 7.5 nm CdS nanoparticles. Our results provide new insights into the fundamental properties of nanoparticles under high pressure that will inform designs of new nanomaterial structures for emerging applications.

Any material inherently comes with its physical and chemical properties. The material scientists and allied engineers work on these properties in order to unearth newer findings. The change in the properties of a material through various process directly affects its characteristics and behaviour. Significant research on material science and metallurgical engineering have been done based on physical properties of the substance. Out of many physical characteristics of materials, this paper focuses on optical properties based on human visual perception. The particular research aims at an interdisciplinary approach to investigate how visual perception plays an important role in design and analysis of materials. Two particular cases have been analysed for this purpose, one in the domain of micro structure analysis and the other relating to the external physical visual characteristics of a material. Through this analysis a generic process framework is evolved which could be applied in material research as a theoretical discourse. Additionally an expert opinion survey reinforces the establishment of the evolved process framework. It would help scientists and engineers adapt and relate to a process so far as designing of new materials or comparative assessment of materials are concerned based on human visual perception.

We describe how the development of advanced materials via high-throughput experimentation at Intermolecular® is accelerated using guidance from modelling, machine learning (ML) and other data-driven approaches. Focusing on rapid development of materials for the semiconductor industry at a reasonable cost, we review the strengths and the limitations of data-driven methods. ML applied to the experimental data accelerates the development of record-breaking materials, but needs a supply of physically meaningful descriptors to succeed in a practical setting. Theoretical materials design greatly benefits from the external modelling ecosystems that have arisen over the last decade, enabling a rapid theoretical screening of materials, including additional material layers introduced to improve the performance of the material stack as a whole, “dopants” to stabilize a given phase of a polymorphic material, etc. We discuss the relative importance of different approaches, and note that the success rates for seemingly similar problems can be drastically different. We then discuss the methods that assist experimentation by providing better phase identification. Finally, we compare the strengths of different approaches, using as an example the problem of identifying regions of thermodynamic stability in multicomponent systems.

LiNi0.5Mn1.5O4 cathode material, which has a higher working voltage (4.7 v) than NCM and a moderate specific capacity (148 mAh/g theoretical), has been studied to understand the source of capacity fade during the first 100 cycles in a half cell. The work mainly consisted of high resolution TEM observations and analysis of the surface microstructural properties, before and after cycling. We found that the pristine material consisted almost entirely of large FCC spinal domains but with cycling appears small simple cubic spinel domains at the surface. It is proposed that these small changes of the surface microstructure leads to impedance rise that results in the premature arrival to the upper cutoff voltage of 4.85V during charging and the subsequent loss of capacity with cycling.

The {100}-oriented (CaxSr1-x)Si2 thin films have been prepared by co-sputtering method at various deposition temperatures. Constituent phase of the films primarily depends on the deposition temperature and the composition x. Although CaSi2 films consisted of layered structure regardless of deposition temperature, the phase was changed by the deposition temperature: the majority phases of the film deposited at 600°C, 650°C and 700°C were 1T layered structure, 1T layered structure + 2H layered structure and 1T layered structure + 6R layered structure, respectively. When the (CaxSr1-x)Si2 films deposited at 700°C, the α-SrSi2-type phase was mainly confirmed below x = 0.17, which is the most stable phase of SrSi2. However, the main phase of all CaxSr1-xSi2 films deposited at 600°C changed to be 1T-type layered structure. Substitution with Ca below x = 0.50 in the film deposited at 600°C led to the decrease in the electrical resistivity compared with that of pure SrSi2.

For a material to be used as energy, understanding its combustion behavior is crucial. Biomass is one such material that is increasingly gaining traction. Biomass may be utilized by direct combustion or transformation into fluid or solid biomass-based fuels. In this work, slow pyrolysis of groundnut shells, bagasse, rice husks and coffee husks was done to produce briquettes with cassava starch binder. Thermogravimetric analysis (TGA) was carried out using an Eltra Thermostep thermogravimetric analyzer. The samples were heated from ambient to 920 deg. Celsius. This analysis provided combustion explanations in terms of the weight loss, burning rates, peak temperatures, char residues and mean reactivity. TGA results showed that binder inclusion reduced the amount of fixed carbon present in the developed briquettes, thus slightly reducing their calorific values. Rice husks briquettes yielded the least weight loss (20.9% and 24.7% for 30g and 50g binder incorporations respectively) compared to others, owing to former’s higher ash contents. Increase in binder contents reduced the amount of char residues, caused by reducing ash contents in the developed briquettes. Peak temperatures and char residues generally increased with increasing binder content. This signifies increasing thermal stabilities of the developed briquettes. Highest char residues were obtained by briquettes developed with rice husks at 30g binder while briquettes developed with bagasse briquettes developed at 50g binder had the least char residues. The highest mean reactivities were obtained in briquettes developed from bagasse and coffee husks while briquettes developed from rice husks had lowest mean reactivities. Briquettes developed in this study showed sufficient combustion properties suitable to provide energy for domestic and industrial applications.

Formulated, processed, and dried Aloe polysaccharides thin film sandwiched between ITO as bottom electrode and Au as top electrode has been adopted as an artificial synapse to emulate behavior of neuromorphic computing. The synaptic plasticity or weight has been modulated with this simple metal-insulator-metal structure by applying voltage sweep and voltage pulse, with excitatory postsynaptic current being monitored. Synaptic potentiation and depression has been demonstrated by applying 6 consecutive sweeps of voltage in positive and negative polarity, respectively. By varying number (10 – 50) of voltage pulses, variable synaptic weight has been measured with paired pulse facilitation and post-tetanic potentiation indexes of 2.61x10-6and 1.45x10-4, respectively. The short-term plasticity and long-term potentiation can be clearly revealed when applying 40 pulses and beyond, with extracted time constants of approximately 28 s at 40 pulses and 90 s at 50 pulses.

Sodium-ion batteries (SIBs) have emerged as a promising alternative for energy storage. In this work, it has been synthesized a nanocomposite material of SbxSbySz/Carbon nanofibers (CNFs) using low-cost synthesizing methods. First, CNFs have been obtained by electrospinning method with subsequent carbonation at 700°C. Afterward, a SbxSbySz thin coating is deposited on the CNFs by chemical bath deposition technique to obtain the SbxSbySz/CNFs. In order to obtain the SnSb2S4 crystalline phase, the composite is heated at 300°C in nitrogen atmosphere. The evaluation of this nanocomposite as the anode for SIBs has a reversible discharge capacity of 180 mAh g-1 and a columbic efficiency of 61.4% after 9 cycles. On the other hand, the resistance associated to the charge transfer to the CNFs decreases from 115.03 Ω to 77.86 Ω due to the incorporation of SnxSbySz. Finally, an easy and inexpensive route has been proposed for the synthesis of SbxSbySz/CNFs composite with great potential to be used as anode material for SIBs.

The environmental problems caused by the persistence and improper disposal of single use plastics, have led the worldwide authorities to migrate into a sustainable production of bio-based materials, whose components need to be studied for proving their nature and to confirm their degradability. For this reason, the identification and monitoring degradation of five single use straws were assessed through FT-IR, TGA/DTA and SEM techniques which demonstrate that the straws tagged as biodegradable contain polymers of fossil origin in their formulation. Degradation of them was found to be influenced by polar groups, such as ester and glycosidic bonds of the biodegradable phase. The thermal stability decreased and the morphological characteristics as cracks and holes were detected after biodegradation.

Lead halide perovskite nanocrystals (NCs) are promising for applications in light emitting devices owing to a strong emission spectrum that is tunable throughout the visible region by altering halide composition. However, in mixed-halide perovskite systems photoinduced migration drives formation of halide-segregated domains, altering the emission spectrum. The mechanism by which this segregation occurs is currently the subject of intense investigation. Processes involving the perovskite surface are expected to be of enhanced prevalence in NCs due to their large surface area to volume ratio. In this work, we use transient absorption spectroscopy to probe the excited-state dynamics of NCs before and after halide segregation. Comparison of global fit spectra of the measured signals suggests the accumulation of iodide at the surface, resulting in a redshifted emission spectrum.

Polytetrafluoroethylene (PTFE) film is observed to increase surface roughness during annealing. Longer annealing times leads to greater surface roughness. The coefficient of friction of PTFE film is affected by the shape of microscale sized particles on the film surface. In this study, we investigate the coefficient of friction of PTFE films using a coarse-grained molecular dynamics model based on experimental observations. We observe how the variation in PTFE chain length and film density affect the topography of PTFE films. We also investigate how these properties of PTFE, and the indenter radius affect the coefficient of friction observed during surface scratch. We find that short PTFE chain lengths create a dense film with greater particle spacing, but longer chains form a mesh structure which reduces the density and creates overlapping portions of particles in the film. We develop a convolutional neural network to classify PTFE film surface and predict the coefficient of friction of a modeled film based solely on the equilibrated film topography. The accuracy of the network was seen to increase when the density and images of internal fiber orientation were added as input features. These results indicate that the coefficient of friction of PTFE films in part is governed by the internal structure of the film.

Nanoparticles of high-refractive-index materials like semiconductors can achieve confinement of light at the subwavelength scale because of the excitation of Mie resonances. The nanostructures out of high-refractive-index materials have extensively been studied theoretically and realized in experiments exploring a wide range of photonic applications. Recently, transition metal dichalcogenides (TMDCs) from the family of van der Waals layered materials have been shown to exhibit tailorable optical properties along with high refractive index and strong anisotropy. We envision that TMDCs are a promising material platform for designing metasurfaces and ultra-thin optical elements: these van der Waals materials show a strong spectral response on light excitations in visible and near-infrared ranges, and metasurface properties can be controlled by nanoantenna dimensions and their arrangement. In this work, we investigate a periodic array of disk-shaped nanoantennas made of a TMDC material, tungsten disulfide WS2, placed on top of a silicon layer and oxide substrate. We show that the nanostructure resonance in TMDC disk-shaped nanoantenna array can be controlled by the variation in silicon layer thickness and have a dependence on the presence of index-match superstrate cover. We also report on the spectral features in absorption and reflection profiles of the same structure with different surrounding index.

Dilute aqueous solutions of dopamine buffered to an alkaline pH and in the presence of dissolved oxygen undergo to a series of autoxidation and rearrangement reactions that lead to the formation of a dark insoluble material called polydopamine (PDA) with melanin reminiscent properties. In this work we carried out this reaction in the presence of the photosynthetic reaction center (RC), a transmembrane pigment-protein complex responsible for the first light-induced reactions in the photosynthetic process. We have found that PDA grows in colloidal form around the RC and in the appropriate conditions the protein is entrapped in the PDA matrix without loss of functionality. The protein is still capable to perform its natural photocycle leading to the generation of photocurrents and the ubiquinone acceptor complex function is modulated by the PDA/RC ratio.

Light Detection and Ranging (LiDAR) is a primary sensor for autonomous vehicles to recognize surroundings. It detects near-infrared (NIR) light pulses, typically at 905nm, which is emitted and reflected by surrounding objects. Here, the fact of the matter is that conventional black or dark-tone cars with extremely low NIR reflection are hard to be detected by LiDAR and endanger the future highway. In this work, we propose to use platelet-shaped effect pigments with visible absorption and NIR reflectivity. Copper(Ⅱ) oxide and Silicon dioxide multilayer are theoretically investigated with different numbers of layers and thicknesses. The optimized structures appear various dark-tone colors with high NIR-reflectivity over 90%.

Plasmonic near-perfect absorbers, comprising metal films with a periodic array of subwavelength openings, were deposited on the surface of pyroelectric materials to create wavelength-selective far-infrared detectors. The detectors fabricated and investigated were based on one of two pyroelectric materials: (i) z-cut monocrystalline lithium tantalate (LiTaO3) wafers or, (ii) reactively sputtered aluminum nitride (AlN), with absorbers fabricated by contact photolithography. Spectrally selective absorption resonances were demonstrated by Fourier-transform spectroscopy. Spectrally-selective photoresponse was demonstrated with a tunable THz backward wave oscillator. Responsivity was estimated using a black body source to be ∼ 1 mV/W for AlN samples and ∼ 100 mV/W for LiTaO3 samples. Most similar work has focused on detectors for mid-wave and long-wave infrared spectral regions. Our focus on THz wavelengths beyond 20 μm is motivated by specific security and contraband sensing applications.

Single crystal gold clusters (10 nm in size) have been collectively manipulated on mono- and bi-layered MoS2 islands (up to 20 µm) grown on SiO2 using AFM. On the monolayer the clusters tend to move in a direction corresponding to the zigzag alignment of the Mo and S atoms, and assemble into long striation patterns parallel to the scan direction. The distance between consecutive stripes is inversely proportional to the cluster concentration and size. A more detailed observation based on SEM shows that within each stripe the clusters remain separated by gaps of few nm in width possibly caused by electrostatic repulsion and/or the roughness of the SiO2 substrate (~2 nm). The stripes also proved to be thermally stable, preserving their superstructures up to 823 K. On the bilayer gold clusters are much less prone to move and assemble into stripes. These results suggest that the formation of nanostructures resulting from collective manipulation of metal clusters can be oriented by a properly chosen scan path in a rather straightforward way (as compared to one-by-one displacement of single clusters). The goal of forming µm-long but nm-thin wires with a geometrically defined shape could be easily reached with the use of smoother substrates or TMD materials with lesser charge transfer to metals adsorbed on them.