Non-enzymatic Hydrogen Peroxide Sensors Based on Multi-wall Carbon Nanotube/Pt Nanoparticle Nanohybrids

A novel strategy to fabricate a hydrogen peroxide (H₂O₂) sensor was developed by using platinum (Pt) electrodes modified with multi-wall carbon nanotube-platinum nanoparticle nanohybrids (MWCNTs/Pt nanohybrids). The process to synthesize MWCNTs/Pt nanohybrids was simple and effective. Pt nanoparticles (Pt NPs) were generated in situ in a potassium chloroplatinate aqueous solution in the presence of multi-wall carbon nanotubes (MWCNTs), and readily attached to the MWCNTs convex surfaces without any additional reducing reagents or irradiation treatment. The MWCNT/Pt nanohybrids were characterized by transmission electron microscope (TEM), and the redox properties of MWCNTs/Pt nanohybrids-modified Pt electrode were studied by electrochemical measurements. The MWCNTs/Pt-modified electrodes exhibited a favorable catalytic ability in the reduction of H₂O₂. The modified electrodes can be used to detect H₂O₂ in the range of 0.01–2 mM with a lower detection limit of 0.3 μM at a signal-to-noise ratio of 3. The sensitivity of the electrode to H₂O₂ was calculated to be 205.80 μA mM⁻¹ cm⁻² at working potential of 0 mV. In addition, the electrodes exhibited an excellent reusability and long-term stability as well as negligible interference from ascorbic acid, uric acid, and acetaminophen.     

Impedance Analysis and Noise Measurements on Multi Walled Carbon Nanotube Networks

The electrical impedance characteristics of multi-walled carbon nanotube (MWCNTs) networks were studied as a function of CNT concentrations in the frequency range of 1 kHz–1 MHz. The novelty of this study is that the MWCNTs were not embedded in any polymer matrix and so the response of the device to electrical measurements are attributed to the CNTs in the network without any contribution from a polymer host matrix. Devices with low MWCNT packing density (0.31–0.85 µg/cm²) exhibit a frequency independent plateau in the low-frequency regime. At higher frequencies, the AC conductivity of these devices increases following a power law, characteristic of the universal dynamic response (UDR) phenomenon. On the other hand, devices with high MWCNT concentrations (>1.0 µg/cm²) exhibit frequency independent conductivity over the entire frequency range (up to 1 MHz), indicating that conduction in these devices is due to direct contact between the CNTs in the network. A simple single-relaxation time electrical equivalent circuit with an effective resistance and capacitance is used to describe the device performance. The electrical noise measurements on devices with different MWCNT packing densities exhibit bias-dependent low-frequency 1/f noise, attributed to resistance fluctuations.     

Development of High-Performance Thermoelectric Materials by Microstructure Control of P-Type BiSbTe Based Alloys Fabricated by Water Atomization

Developing inexpensive and rapid fabrication methods for high efficiency thermoelectric alloys is a crucial challenge for the thermoelectric industry, especially for energy conversion applications. Here, we fabricated large amounts of p-type Cu_0.07Bi_0.5Sb_1.5Te₃ alloys, using water atomization to control its microstructure and improve thermoelectric performance by optimizing its initial powder size. All the water atomized powders were sieved with different aperture sizes, of 32–75 μm, 75–125 μm, 125–200 μm, and <200 μm, and subsequently consolidated using hot pressing at 490 °C. The grain sizes were found to increase with increasing powder particle size, which also increased carrier mobility due to improved carrier transport. The maximum electrical conductivity of 1457.33 Ω⁻¹ cm⁻¹ was obtained for the 125–200 μm samples due to their large grain sizes and subsequent high mobility. The Seebeck coefficient slightly increased with decreasing particle size due to scattering of carriers at fine grain boundaries. The higher power factor values of 4.20, 4.22 × 10⁻³ W/mk² were, respectively, obtained for large powder specimens, such as 125–200 μm and 75–125 μm, due to their higher electrical conductivity. In addition, thermal conductivity increased with increasing particle size due to the improvement in carriers and phonons transport. The 75–125 μm powder specimen exhibited a relatively high thermoelectric figure of merit, ZT of 1.257 due to this higher electric conductivity.     

Graphene/PVDF Composites for Ni-rich Oxide Cathodes toward High-Energy Density Li-ion Batteries

Li-ion batteries (LIBs) employ porous, composite-type electrodes, where few weight percentages of carbonaceous conducting agents and polymeric binders are required to bestow electrodes with electrical conductivity and mechanical robustness. However, the use of such inactive materials has limited enhancements of battery performance in terms of energy density and safety. In this study, we introduced graphene/polyvinylidene fluoride (Gr/PVdF) composites in Ni-rich oxide cathodes for LIBs, replacing conventional conducting agents, carbon black (CB) nanoparticles. By using Gr/PVdF suspensions, we fabricated highly dense LiNi_0.85Co_0.15Al_0.05O₂ (NCA) cathodes having a uniform distribution of conductive Gr sheets without CB nanoparticles, which was confirmed by scanning spreading resistance microscopy mode using atomic force microscopy. At a high content of 99 wt.% NCA, good cycling stability was shown with significantly improved areal capacity (Q_areal) and volumetric capacity (Q_vol), relative to the CB/PVdF-containing NCA electrode with a commercial-level of electrode parameters. The NCA electrodes using 1 wt.% Gr/PVdF (0.9:0.1) delivered a high Q_areal of ~3.7 mAh cm⁻² (~19% increment) and a high Q_vol of ~774 mAh cm⁻³ (~18% increment) at a current rate of 0.2 C, as compared to the conventional NCA electrode. Our results suggest a viable strategy for superseding conventional conducting agents (CB) and improving the electrochemical performance of Ni-rich cathodes for advanced LIBs.     

The Positive Effect of ZnS in Waste Tire Carbon as Anode for Lithium-Ion Batteries

There is great demand for high-performance, low-cost electrode materials for anodes of lithium-ion batteries (LIBs). Herein, we report the recovery of carbon materials by treating waste tire rubber via a facile one-step carbonization process. Electrochemical studies revealed that the waste tire carbon anode had a higher reversible capacity than that of commercial graphite and shows the positive effect of ZnS in the waste tire carbon. When used as the anode for LIBs, waste tire carbon shows a high specific capacity of 510.6 mAh·g⁻¹ at 100 mA·g⁻¹ with almost 97% capacity retention after 100 cycles. Even at a high rate of 1 A·g⁻¹, the carbon electrode presents an excellent cyclic capability of 255.1 mAh·g⁻¹ after 3000 cycles. This high-performance carbon material has many potential applications in LIBs and provide an alternative avenue for the recycling of waste tires.     

Electric and Dielectric Properties in Low-Frequency Fields of Composites Consisting of Silicone Rubber and Al Particles for Flexible Electronic Devices

Understanding the electrical conduction and dielectric polarization properties of elastomer-based composites is important for the design of flexible and elastic electronic devices and circuits. Five samples were manufactured by mixing silicone rubber (RTV-530) with Al particles in different volume fractions, x equal to 0%, 0.5%, 1%, 2.5% and 5.1%. Using the complex impedance measurements, the electric modulus, M, the electrical conductivity, σ, and the dielectric permittivity, ε, over the frequency range 100 Hz–200 kHz were analyzed. The electrical conductivity spectrum, σ(f), follows the Jonscher universal law and the DC conductivity of the samples, σ_DC, increases from 2.637·10⁻⁸ S/m to 5.725·10⁻⁸ S/m, with increasing x from, 0 to 5.1%. The conduction process was analyzed in terms of Mott’s variable-range-hopping (VRH) model. The hopping distance of the charge carriers, R_h decreases with increasing x, from 7.30 nm (for x = 0) to 5.92 nm (for x = 5.1%). The frequency dependence of permittivity, ε(f) = ε′(f) − iε″(f), reveals a relaxation process with the maximum of ε″(f) shifting from 301 Hz to 385 Hz and values of ε′(f) increasing with the increase of x.     

Surface Modification Using Assisting Electrodes in Wire Electrical Discharge Machining for Silicon Wafer Preparation

This paper outlines notable advances in the wire electrical discharge machining of polycrystalline silicon workpieces for wafer preparation. Our use of assisting electrodes permits the transfer of aluminum particles to the machined surface of the polycrystalline silicon workpieces, to enhance conductivity and alter surface topography regardless of the silicon’s crystallographic structure and diamond-type lattice. This in-process surface modification technique was shown to promote material removal and simultaneously preserve the integrity of the machined surfaces with preferable surface textures. In the validation experiment, the 25 mm-thick assisting electrodes deposited a notable concentration of aluminium on the machined surface (~3.87 wt %), which greatly accelerated the rate of material removal (~9.42 mg/s) with minimal surface roughness (S_a ~5.49 μm) and moderate skewness (−0.23). The parameter combination used to obtain the optimal surface roughness (S_a 2.54 μm) was as follows: open voltage (80 V), electrical resistance (1.7 Ω), pulse-on time (30 μs), and electrode thickness (15 mm). In multiple objective optimization, the preferred parameter combination (open voltage = 80 V, resistance = 1.4 Ω, pulse-on time = 60 μs, and assisting electrode thickness = 25 mm) achieved the following appreciable results: surface modification of 3.26 ± 0.61 wt %, material removal rate of 7.08 ± 2.2 mg/min, and surface roughness of S_a = 4.3 ± 1.67 μm.     

Impact of Short-Cut SWCF Yarn on Conductivity and Electrical Heatability of Silicone–MWCNT Composites

The incorporation of MWCNTs in polymer systems up to the percolation range renders them electrically conductive. However, this conductivity is not high enough for heating applications in the low-voltage range (<24 V). The combination of nanoscaled MWCNTs with microscaled short SWCNT fibers that was investigated in this study causes an abrupt rise in the conductivity of the material by more than an order of magnitude. Silicone was used as a flexible and high-temperature-resistant matrix polymer. Conductive silicone coatings and films with SWCF contents of 1.5% to 5% and constant MWCNT contents of 3% and 5% were developed, and their electrical and thermal properties in the voltage range between 6 and 48 V were investigated. The electrical conductivity of 3% MWCNT composite materials rose with a 5% addition of SWCFs. Because of this spike in conductivity, output power of 1260 W/m² was achieved, for example, for a 100 µm thick composite containing 3% MWCNT and 4% SWCF at 24 V with a line spacing of 20 cm. Thermal measurements show a temperature increase of 69 K under these conditions. These findings support the use of such conductive silicone composites for high-performance coatings and films for challenging and high-quality applications.     

Preparation of LiFePO4 Powders by Ultrasonic Spray Drying Method and Their Memory Effect

The memory effect of lithium-ion batteries (LIBs) was first discovered in LiFePO₄, but its origin and dependence are still not clear, which is essential for regulating the memory effect. In this paper, a home-made spray drying device was used to successfully synthesize LiFePO₄ with an average particle size of about 1 μm, and we studied the influence of spray drying temperature on the memory effect of LiFePO₄ in LIBs. The results showed that the increasing of spray drying temperature made the memory effect of LiFePO₄ strengthen from 1.3 mV to 2.9 mV, while the capacity decreased by approximately 6%. The XRD refinement and FTIR spectra indicate that the enhancement of memory effect can be attributed to the increment of Li–Fe dislocations. This work reveals the dependence of memory effect of LiFePO₄ on spray drying temperature, which will guide us to optimize the preparation process of electrode materials and improve the management system of LIBs.     

Scalable Synthesis and Electrochemical Properties of Porous Si-CoSi2-C Composites as an Anode for Li-ion Batteries

Si-based anodes for Li-ion batteries (LIBs) are considered to be an attractive alternative to graphite due to their higher capacity, but they have low electrical conductivity and degrade mechanically during cycling. In the current study, we report on a mass-producible porous Si-CoSi₂-C composite as a high-capacity anode material for LIBs. The composite was synthesized with two-step milling followed by a simple chemical etching process. The material conversion and porous structure were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and electron microscopy. The electrochemical test results demonstrated that the Si-CoSi₂-C composite electrode exhibits greatly improved cycle and rate performance compared with conventional Si-C composite electrodes. These results can be ascribed to the role of CoSi₂ and inside pores. The CoSi₂ synthesized in situ during high-energy mechanical milling can be well attached to the Si; its conductive phase can increase electrical connection with the carbon matrix and the Cu current collectors; and it can accommodate Si volume changes during cycling. The proposed synthesis strategy can provide a facile and cost-effective method to produce Si-based materials for commercial LIB anodes.     

Fabrication of a Flexible Photodetector Based on a Liquid Eutectic Gallium Indium

A fluidic gallium-based liquid metal (LM) is an interesting material for producing flexible and stretchable electronics. A simple and reliable method developed to facilitate the fabrication of a photodetector based on an LM is presented. A large and thin conductive eutectic gallium indium (EGaIn) film can be fabricated with compressed EGaIn microdroplets. A solution of LM microdroplets can be synthesized by ultrasonication after mixing with EGaIn and ethanol and then dried on a PDMS substrate. In this study, a conductive LM film was obtained after pressing with another substrate. The film was sufficiently conductive and stretchable, and its electrical conductivity was 2.2 × 10⁶ S/m. The thin film was patterned by a fiber laser marker, and the minimum line width of the pattern was approximately 20 μm. Using a sticky PDMS film, a Ga₂O₃ photo-responsive layer was exfoliated from the fabricated LM film. With the patterned LM electrode and the transparent photo-responsive film, a flexible photodetector was fabricated, which yielded photo-response-current ratios of 30.3%, 14.7%, and 16.1% under 254 nm ultraviolet, 365 nm ultraviolet, and visible light, respectively.     

Synthesis and Characterization of Sn/SnO2/C Nano-Composite Structure: High-Performance Negative Electrode for Lithium-Ion Batteries

Tin oxide (SnO₂) and tin-based composites along with carbon have attracted significant interest as negative electrodes for lithium-ion batteries (LIBs). However, tin-based composite electrodes have some critical drawbacks, such as high volume expansion, low capacity at high current density due to low ionic conductivity, and poor cycle stability. Moreover, complex preparation methods and high-cost carbon coating procedures are considered main challenges in the commercialization of tin-based electrodes for LIBs. In this study, we prepared a Sn/SnO₂/C nano-composite structure by employing a low-cost hydrothermal method, where Sn nanoparticles were oxidized in glucose and carboxymethyl cellulose CMC was introduced into the solution. Scanning electron microscope (SEM) and transmission electron microscope revealed the irregular structure of Sn nanoparticles and SnO₂ phases in the conductive carbon matrix. The as-prepared Sn/SnO₂/C nano-composite showed high first-cycle reversible discharge capacity (2248 mAhg⁻¹) at 100 mAg⁻¹ with a first coulombic efficiency of 70%, and also displayed 474.64 mAhg⁻¹ at the relatively high current density of about 500 mAg⁻¹ after 100 cycles. A low-cost Sn/SnO₂/C nano-composite with significant electrochemical performance could be the next generation of high-performance negative electrodes for LIBs.     

Holographic patterning of high-performance on-chip 3D lithium-ion microbatteries

As sensors, wireless communication devices, personal health monitoring systems, and autonomous microelectromechanical systems (MEMS) become distributed and smaller, there is an increasing demand for miniaturized integrated power sources. Although thin-film batteries are well-suited for on-chip integration, their energy and power per unit area are limited. Three-dimensional electrode designs have potential to offer much greater power and energy per unit area; however, efforts to date to realize 3D microbatteries have led to prototypes with solid electrodes (and therefore low power) or mesostructured electrodes not compatible with manufacturing or on-chip integration. Here, we demonstrate an on-chip compatible method to fabricate high energy density (6.5 μWh cm⁻²⋅μm⁻¹) 3D mesostructured Li-ion microbatteries based on LiMnO₂ cathodes, and NiSn anodes that possess supercapacitor-like power (3,600 μW cm⁻²⋅μm⁻¹ peak). The mesostructured electrodes are fabricated by combining 3D holographic lithography with conventional photolithography, enabling deterministic control of both the internal electrode mesostructure and the spatial distribution of the electrodes on the substrate. The resultant full cells exhibit impressive performances, for example a conventional light-emitting diode (LED) is driven with a 500-μA peak current (600-C discharge) from a 10-μm-thick microbattery with an area of 4 mm² for 200 cycles with only 12% capacity fade. A combined experimental and modeling study where the structural parameters of the battery are modulated illustrates the unique design flexibility enabled by 3D holographic lithography and provides guidance for optimization for a given application.Microscale devices typically use power supplied off-chip because of difficulties in miniaturizing energy storage technologies (1, 2). However, a miniaturized on-chip battery would be highly desirable for applications including autonomous microelectromechanical systems (MEMS)-based actuators, microscale wireless sensors, distributed monitors, and portable and implantable medical devices (3–8). For many of the applications, high energy density, high power density (charge and/or discharge), or some combination of high energy and power densities is required, all characteristics which can be difficult to achieve in a microbattery due to size and footprint restrictions, and process compatibilities with the other steps required for device fabrication. Although 2D thin-film microbatteries (typical thickness of a few micrometers) can deliver high power, they require large (often cm²) footprints to provide reasonable energies (9). Making the electrodes thicker boosts the theoretical areal energy density but the resultant increases in electron and ion diffusion lengths reduce the effective power and energy densities. Efforts to improve microbattery performance have focused on increasing the electrode surface area and active material loading in the third dimension. Electrodes based on high-aspect-ratio micropillar structures, realized via methods including electrodeposition, polymer pyrolysis, and vapor deposition techniques, have been demonstrated (10–14). Despite the improved energy density compared with 2D batteries, because the micropillar electrodes are solid, the power and effective energy density is still limited due to the resultant long ion and electron diffusion pathways. Mesostructured 3D electrodes derived from nanowires or nanotubes have potential for achieving high energy and power densities, but difficulties in synthesis and full-cell assembly have limited these electrodes to half-cell demonstrations (15–18).As we demonstrated via a colloidal templating strategy (19–21), electrodes consisting of a layer of electrolytically active materials directly grown on a mesostructured 3D porous current collector can offer both high energy and power densities by providing efficient electron pathways, short solid-state ion diffusion lengths, and a pore network for Li-ion transport. Unlike for a micropillar, all of the major internal resistances of the microbattery can be simultaneously minimized. The colloidally templated 3D mesostructured electrodes were first fabricated in a half-cell configuration, and the resulting electrode indeed delivered supercapacitor-like power (e.g., 40% energy discharge in 3 s) while maintaining battery-like energy (19). We subsequently fabricated a microbattery (full cell) with an unprecedented 2,000× increase in power compared with previous microbatteries (22) via a similar approach. However, colloidally templated microbatteries contain a number of serious limitations. From a purely practical standpoint, a fabrication approach that involves growth of a colloidal crystal from a colloidal suspension on a substrate is unlikely to be acceptable in a manufacturing environment, because it is slow, and submicrometer colloidal particles are generally unwelcome in a microfabrication facility. The mesostructure and connectivity of the colloidally templated system is severely restricted by the close-packed particles, allowing almost no freedom to alter the structure of a unit cell. Finally, all colloidal crystals contain defects (e.g., cracks), which end up in the final electrode structure as solid elements (the inverse of a crack). These solid elements locally limit ion transport and make capacity matching between anode and cathode difficult, which may in part be why the cycle life of the colloidally templated microbattery was low. In contrast with colloidal assembly and other 3D fabrication techniques such as direct laser (ink) writing (which produces 3D structures in a point-to-point or layer-by-layer fashion) (23, 24), 3D holographic lithography generates periodic, defect-free features (50∼1,000 nm) in a one-step exposure (∼ seconds) over an area that is linearly proportional to the beam size. It can create a variety of complex 3D structures by varying the beam patterns and exposure conditions. Although accurate control on the interfering optical beams is required to construct 3D holographic lithography, recent advances have significantly simplified the required optics, enabling creation of structures via a single incident beam and standard photoresist processing, making it highly scalable and compatible with microfabrication (25, 26).Here, we describe a flexible and deterministic 3D fabrication route which combines 3D holographic lithography with conventional photolithography to create microbatteries with good cycle lives, and high power and energy densities using complementary metal-oxide–semiconductor (CMOS) and microfluidic device-compatible processing steps. The holographic lithography creates a defined periodically mesostructured 3D lattice, whereas the conventional photolithography defines a set of 2D solid structures that divide the 3D lattice into an interdigitated pattern. The combination of these two lithography processes provides comprehensive control of the electrode mesostructure and spatial arrangement, enabling formation of flat-sided and topped 3D current collectors with independently deposited high-quality cathode and anode active materials. The resultant full cells exhibit energy and power densities up to 6.5 μWh cm⁻²⋅μm⁻¹ (energy-optimized electrode spacing) and 3,600 μW cm⁻²⋅μm⁻¹ (power-optimized electrode spacing), with less than 5% cell-to-cell distribution. The cells retain at least 80% of the initial capacity after cycling 100 times at various rates, and 88% of the initial capacity after driving a light-emitting diode (LED) for 200 cycles. The capacity for fast charging and discharging endues the microbattery with rather unexpected capabilities for a battery which is only 2 mm on a side and ∼10 µm thick, for example the battery could repeatedly (>200 cycles) drive a conventional LED with a 600-C peak current (∼0.5 mA). A combined experimental and modeling study where the structural parameters of the battery are modulated illustrates the unique design flexibility enabled by 3D holographic lithography and provides guidance for optimization for a given application.     

Analysis of EDM Performance,through a Thermal–Electrical Model with a Trunk-Conical Discharge Channel,Using a Steel Tool and an Aluminium Workpiece

In this article, a finite element (FE) thermal–electrical model with a trunk-conical discharge channel is employed to simulate individual EDM discharges with a time-on of 18 μs up to 320 μs, which are subsequently compared with the experimental results to validate the model. The discharge channel is a trunk-conical electrical conductor which dissipates heat by the Joule heating effect, being the correspondent factor equal to 1. Instead of the usual copper–iron electrode combination, steel (DIN CK45) and aluminium alloys (DIN 3.4365) are the implemented materials on both the tool and the workpiece, respectively. The numerical results were measured using the melting temperature of the materials as the boundary of material removal. The results obtained with the thermal–electrical model, namely the tool wear ratio, the tool wear rate, the material removal rate, and the surface roughness, are in good agreement with experimental results, showing that the new FE model is capable of predicting accurately with different materials for the electrodes.     

Preliminary In Vitro Study of Fluoride Release from Selected Ormocer Materials

The purpose of the in vitro study presented in this paper was to determine the long-term release of fluoride ions from selected ormocer materials (Admira (A), Admira Flow (AF), Admira Seal (AS)). The release of fluoride ions from these materials into a saline solution (0.9% NaCl) and deionized water was tested for 14 weeks. In a long-term study the measurements were taken after 1 and 3 h, then 1, 2, and 3 days and then at weekly intervals for 14 weeks. In a short-term study the measurements were made after 3, 24, 48, 72, 69, 168 h, i.e., within 7 days. All materials used in the test showed a constant level of fluoride release. The highest level of cumulative release of fluoride ions into deionized water was found in the AS material (23.95 ± 4.30 μg/mm²), slightly lower in the A material (23.26 ± 4.16 μg/mm²) and the lowest in the AF material (16.79 ± 2.26 μg/mm²). The highest level of cumulative release into saline solution was found in AF (8.08 ± 1.30 μg/mm²), slightly lower in AS (7.36 ± 0.30 μg/mm²) and the lowest in A (6.73 ± 1.10 μg /mm²). After 1 h of immersion of the samples in the saline solution, the highest level of fluoride was released by AF (0.57 ± 0.06 μg/mm²) followed by A (0.20 ± 0.03 μg/mm²) and AS (0.19 ± 0.02 µg/mm²). Moreover, in the 14-week study, the total amount of fluoride release into the saline, which imitates the environment of the oral cavity, was observed as the highest in the AF sample.     

Polyester and Epoxy Resins with Increased Thermal Conductivity and Reduced Surface Resistivity for Applications in Explosion-Proof Enclosures of Electrical Devices

Composite materials are still finding new applications that require the modification of various properties and are characterized by the summary impact on selected operational features. Due to the operating conditions of electrical equipment enclosures in potentially explosive atmospheres, the surface resistivity ensuring anti-electrostatic properties, i.e., below 10⁹ Ω and resistance to the flame while maintaining appropriate operational enclosure properties is very important. It is also crucial to dissipate heat while reducing weight. Currently metal or cast-iron enclosures are used for various types of electrical devices. As part of the work, a material that can be used for a composite matrix for the enclosure was developed. The study aimed to assess the influence of selected fillers and chemical modifications on the thermal conductivity coefficient, resistivity, and strength properties of matrix materials for the production of electrical device enclosures used in the mining industry. Selected resins were modified with graphite, copper, and carbon black. Tests were carried out on the coefficient of thermal conductivity, surface resistivity, flammability, and flexural strength. At the final stage of the work, a multi-criteria analysis was carried out, which allowed the selection of a composite that meets the assumed characteristics to the highest degree. It is a vinyl ester composite modified with 15 wt.% MG394 and 5 wt.% MG1596 graphite (W2). The thermal conductivity of composite W2 is 5.64 W/mK, the surface resistivity is 5.2 × 10³ Ω, the flexural strength is 50.61 MPa, and the flammability class is V0.     

Enhancement of Bentonite Materials with Cement for Gamma-Ray Shielding Capability

The gamma-ray shielding ability of various Bentonite–Cement mixed materials from northeast Egypt have been examined by determining their theoretical and experimental mass attenuation coefficients, μ_m (cm²g⁻¹), at photon energies of 59.6, 121.78, 344.28, 661.66, 964.13, 1173.23, 1332.5 and 1408.01 keV emitted from ²⁴¹Am, ¹³⁷Cs, ¹⁵²Eu and ⁶⁰Co point sources. The μ_m was theoretically calculated using the chemical compositions obtained by Energy Dispersive X-ray Analysis (EDX), while a NaI (Tl) scintillation detector was used to experimentally determine the μ_m (cm²g⁻¹) of the mixed samples. The theoretical values are in acceptable agreement with the experimental calculations of the XCom software. The linear attenuation coefficient (μ), mean free path (MFP), half-value layer (HVL) and the exposure buildup factor (EBF) were also calculated by knowing the μ_m values of the examined samples. The gamma-radiation shielding ability of the selected Bentonite–Cement mixed samples have been studied against other puplished shielding materials. Knowledge of various factors such as thermo-chemical stability, availability and water holding capacity of the bentonite–cement mixed samples can be analyzed to determine the effectiveness of the materials to shield gamma rays.     

Screen-Printed Structures from a Highly Conductive Mildly Oxidized Graphene Suspension for Flexible Electronics

In this study, the screen-printed flexible humidity sensor and supercapacitor structures from a suspension of mildly oxidized graphene (MOG) was obtained. MOG suspension with a low atomic oxygen content (~20%) was synthesized by electrochemical exfoliation of natural graphite in an aqueous solution of ammonium sulfate. MOG films (average thickness 5 μm) with a surface resistance of 10²–10³ kΩ/sq were obtained by screen printing on a flexible substrate. The thermal reduction of MOG films at 200 °C reduced the surface resistance to 1.5 kΩ/sq. The laser reduction with a 474 nm and 200 mW solid-state laser reduced the surface resistance to ~0.065 kΩ/sq. Various structures were screen-printed on a flexible substrate for a variety of flexible electronics applications. The structures representing a flat supercapacitor had an average specific capacitance of ~6 μF/cm². The tensile deformations occurring during bending reduced the capacitance by 40% at a bending radius of 2 mm. Humidity sensing structures with sensitivity of 9% were obtained.     

A Non-Flammable Zwitterionic Ionic Liquid/Ethylene Carbonate Mixed Electrolyte for Lithium-Ion Battery with Enhanced Safety

Today, the requirement for clean, highly efficient, and safe energy seems to be higher and higher due to non-renewable energy and pollution of the environment. At this moment, lithium-ion batteries (LIBs) look like a reliable solution for this dilemma since they have huge energy density. However, the flammability of the conventional electrolyte used in the LIBs is one of critical disadvantages of LIBs, which compromises the safety issue of LIBs. Herein, we reported a non-flammable zwitterionic ionic liquid-based electrolyte named TLPEC, which was fabricated by simply mixing a novel zwitterionic ionic liquid TLP (93 wt%) and ethylene carbonate (EC, 7 wt%). The TLPEC electrolyte exhibited a wide electrochemical potential window of 1.65–5.10 V and a robust ionic conductivity of 1.0 × 10⁻³ S cm⁻¹ at 20 °C, which renders TLPEC to be a suitable electrolyte for LIBs with enhanced safety performance. The LIBs, with TLPEC as the electrolyte, exhibited an excellent performance in terms of excellent rate capability, cycling stability, and high specific capacity at 25 and 60 °C, which were attributed to the stability and high ionic conductivity of TLPEC electrolyte during cycling as well as the excellent interface compatibility of TLPEC electrolyte with lithium anode.     

Uptake of bacterial lipopolysaccharide and expression of tumor necrosis factor-α-mRNA in isolated rat intrahepatic bile duct epithelial cells

AIM: To study the uptake of bacterial lipopolysaccharides (LPS) and expression of tumor necrosis factor α-mRNA (TNF-α-mRNA) with cultured rat intrahepatic bile duct epithelial cells.METHODS: By using fluorescent, immunohistochemical and in situ hybridization techniques, the uptake of Escherichia coli LPS and expression of TNF-α-mRNA with isolated rat intrahepatic bile duct epithelial cells were observed with confocal laser scanning microscopy.RESULTS: Positive reactions to LPS were found in the cytoplasm of isolated intrahepatic bile duct epithelial cells after incubation with LPS for 15 min and the FITC fluorescent intensity against LPS was significantly higher than that of the controls (121.45 μFI/μm² ± 15.62 μFI/μm² vs 32.12 μFI/μm² ± 9.64 μFI/μm², P < 0.01). After incubation with LPS for 3 h, fluorescein isocyanate (FITC) fluorescent intensities of the expression of TNF-α-mRNA with fluorescent in situ hybridization in the cytoplasm and nuclei of the cultured bile duct epithelial cells were significantly higher than those of the controls (189.15 μFI/μm² ± 21.33 μFI/μm² vs 10.00 μFI/μm² ± 8.99 μFI/μm², 64.85 μFI/μm² ± 14.99 μFI/μm² vs 21.20 μFI/μm² ± 2.04 μFI/μm², respectively (P < 0.01)). The increase of FITC fluorescent intensity of TNF-α-mRNA expression in the cytoplasm peaked at 6 h after incubation (221.38 μFI/μm² ± 22.99 μFI/μm²). At various time points after incubation with LPS, the increase of fluorescent intensities of TNF-α-mRNA in the cytoplasm were much higher than those in the nuclei (P < 0.01).CONCLUSION: LPS can act on and enter into isolated intrahepatic bile duct epithelial cells and stimulate the expression of TNF-α-mRNA.