Design and analysis of a mobile robot with novel caster mechanism for high step-overcoming capability.

The mobile robot market is experiencing rapid growth, playing a pivotal role in various human-centric environments like restaurants, offices, hotels, hospitals, apartments, and factories. However, current differential-driven mobile robots, employing conventional casters and wheel motors, encounter limitations in surmounting uneven surfaces and high steps due to constraints caused by wheel and caster dimensions. While some robots address these challenges by incorporating optimized wheel shapes and additional motors, this invariably leads to an increase in both size and cost. This research introduces an innovative solution; a novel caster-wheel mechanism designed to enhance the high-step overcoming capability of mobile robots without necessitating alterations to their overall size and structure. By incorporating a sub-wheel linked to a passive joint, the driving force is effeciently converted into a vertical force, thereby empowering the mobile robot to navigate obstacles 85% larger than its caster-wheel radius. Crucially, this innovative caster can be seamlessly manufactured and integrated, offering the potential for widespread adoption as a replacement for conventional casters. Validation through comprehensive simulations and experiments conducted on a prototype robot has been presented in this article, demonstrating its effectiveness even at a robot velocity of 0.1 m/s. This pioneering solution holds significant promise for diverse applications across various mobile robot configurations, presenting a compelling avenue for further exploration and implementation in the field.

Experimental design of 4-point supported belt robot for sanding large convex surfaces.

In general, sanding robots that move as if drawing a line along a surface are mainly used when sanding objects with a large area; however, they require a long working time, and it is difficult to secure a uniform sanded area. This study focuses on large-area sanding robots, such as those for ships, storage tanks, and tank lorries, and proposes an adaptive belt tension robot equipped with a 4-point supported belt mechanism capable of sanding variable curved surfaces. In addition, a sanding normal force prediction formula is proposed to describe the sanding performance of the contact surface. This equation consists of the concentrated load function due to the belt movement and the normal force due to the vertical and horizontal elongation of the belt. A video image analysis was performed to calculate the sanding area. Therefore, we determined whether the area was uniformly sanded. The dimensions of the test bench (W × D × H) were 1700 mm × 1450 mm × 900 mm. Experiments were performed using the proposed techniques on convex specimens with radii of 725, 1000, and 2100 mm. The sanding performance was improved by 43 % compared with that of a general belt-sanding robot.

Activity-Stability Trends of the Sb-SnO2@RuOx Heterostructure toward Acidic Water Oxidation.

Accomplishments of enhanced activity and durability are a major concern in the design of catalysts for acidic water oxidation. To date, most studied supported metal catalysts undergo fast degradation in strongly acidic and oxidative environments due to improper controlling of the interface stability caused by their lattice mismatches. Here, we evaluate the activity-stability trends of in situ crystallized antimony-doped tin oxide (Sb-SnO2)@RuOx (Sb-SnO2@RuOx) heterostructure nanosheets (NSs) for acidic water oxidation. The catalyst prepared by atomic layer deposition of a conformal Ru film on antimony-doped tin sulfide (Sb-SnS2) NSs followed by heat treatment highlights comparable activity but longer stability than that of the ex situ catalyst (where Ru was deposited on Sb-SnO2 followed by heating). Air calcination for in situ crystallization allows the formation of hierarchical mesoporous Sb-SnO2 NSs from as-prepared Sb-SnS2 NSs and parallel in situ transformation from Ru to RuOx, resulting in a compact heterostructure. The significance of this approach significantly resists corrosive dissolution, which is justified by the enhanced oxygen evolution reaction (OER) stability of the catalyst compared to most of the state-of-the-art ruthenium-based catalysts including Carbon@RuOx (which shows ∼10 times higher dissolution) as well as Sb-SnO2@Com. RuOx and Com. RuO2. This study demonstrates the controlled interface stability of heterostructure catalysts toward enhancing OER activity and stability.

Hierarchical Nanoporous BiVO4 Photoanodes with High Charge Separation and Transport Efficiency for Water Oxidation.

To fabricate high efficiency photoanodes for water oxidation, it is highly required to engineer their nanoporous architecture and interface to improve the charge separation and transport efficiency. By focusing on this aspect, we developed hierarchical nanoporous BiVO4 (BV) from solution processed two-dimensional BiOI (BI) crystals. The orientation of the BI crystals was controlled by changing the solvent volume ratios of ethylene glycol (EG) to ethanol (ET), which resulted in different hierarchical and planar BV morphologies through a chemical treatment followed by thermal heating. The morphology with optimal particle dimension, connectivity, and porosity can offer a highly enhanced electrochemically active surface area (ECSA). The hierarchical BV owning a maximum ECSA showed the best photoelectrochemical (PEC) performance in terms of the highest photocurrent density and charge separation efficiency. However, to further improve the performance of the electrode, conformal and ultrathin SnO2 underlayers were deposited by a powerful atomic layer deposition technique at the interface to effectively block the defect density, which significantly improved the photocurrents as high as 3.25 mA/cm2 for sulfite oxidation and 2.55 mA/cm2 for water oxidation at 0.6 V versus the reversible hydrogen electrode (RHE). The electrode possessed record charge separation efficiency of 97.1% and charge transfer efficiency of 90.1% at 1.23 VRHE among to-date reported BiVO4-based photoanodes for water oxidation. Furthermore, a maximum applied bias photon-to-current efficiency (ABPE) of 1.61% was found at a potential as low as 0.6 VRHE, which is highly promising to make a tandem cell. These results indicate that the construction of the hierarchical nanoporous photoanode with an enhanced ECSA and its proper interface engineering can significantly improve the PEC performance.

Plasma-Enhanced Atomic Layer Deposition of TiN Thin Films as an Effective Se Diffusion Barrier for CIGS Solar Cells.

Plasma-enhanced atomic layer deposition (PEALD) of TiN thin films were investigated as an effective Se diffusion barrier layer for Cu (In, Ga) Se2 (CIGS) solar cells. Before the deposition of TiN thin film on CIGS solar cells, a saturated growth rate of 0.67 Å/cycle was confirmed using tetrakis(dimethylamido)titanium (TDMAT) and N2 plasma at 200 °C. Then, a Mo (≈30 nm)/PEALD-TiN (≈5 nm)/Mo (≈600 nm) back contact stack was fabricated to investigate the effects of PEALD-TiN thin films on the Se diffusion. After the selenization process, it was revealed that ≈5 nm-thick TiN thin films can effectively block Se diffusion and that only the top Mo layer prepared on the TiN thin films reacted with Se to form a MoSe2 layer. Without the TiN diffusion barrier layer, however, Se continuously diffused along the grain boundaries of the entire Mo back contact electrode. Finally, the adoption of a TiN diffusion barrier layer improved the photovoltaic efficiency of the CIGS solar cell by approximately 10%.

Effect of ZnO and SnO2 Nanolayers at Grain Boundaries on Thermoelectric Properties of Polycrystalline Skutterudites.

Nanostructuring is considered one of the key approaches to achieve highly efficient thermoelectric alloys by reducing thermal conductivity. In this study, we investigated the effect of oxide (ZnO and SnO2) nanolayers at the grain boundaries of polycrystalline In0.2Yb0.1Co4Sb12 skutterudites on their electrical and thermal transport properties. Skutterudite powders with oxide nanolayers were prepared by atomic layer deposition method, and the number of deposition cycles was varied to control the coating thickness. The coated powders were consolidated by spark plasma sintering. With increasing number of deposition cycle, the electrical conductivity gradually decreased, while the Seebeck coefficient changed insignificantly; this indicates that the carrier mobility decreased due to the oxide nanolayers. In contrast, the lattice thermal conductivity increased with an increase in the number of deposition cycles, demonstrating the reduction in phonon scattering by grain boundaries owing to the oxide nanolayers. Thus, we could easily control the thermoelectric properties of skutterudite materials through adjusting the oxide nanolayer by atomic layer deposition method.

Atomic Layer Deposition Seeded Growth of Rutile SnO2 Nanowires on Versatile Conducting Substrates.

Extended and oriented rutile nanowires (NWs) hold great promise for numerous applications because of their various tunable physicochemical properties in air and/or solution media, but their direct synthesis on a wide range of conducting substrates remains a significant challenge. Their device performance is governed by relevant NW geometries that cannot be fully controlled to date by varying bulk synthetic conditions. Herein, orientation engineering of rutile SnO2 NWs on a variety of conducting substrates by atomic layer deposition (ALD) seeding has been investigated. The seeded growth controls the nucleation event of the NW, and thicknesses and crystallographic properties of seed layers are the key parameters toward tuning the NW characteristics. The seed layers on carbon cloth produce NWs with highly enhanced electrochemically active surface area, which would show efficient electrochemical CO2 reduction. In addition, the hierarchical architecture resulted from the seeded growth of NWs on SnO2 nanosheets allows thin layers of BiVO4, forming a heterojunction photoanode, which shows a record charge separation efficiency of 96.6% and a charge-transfer efficiency of 90.2% at 1.23 V versus the reversible hydrogen electrode among, to date, the reported BiVO4-based photoanodes for water oxidation. Our study illustrates that such a versatile interfacial engineering effort by the ALD technique would be promising for further wide range of practical applications.

Dataset for TiN Thin Films Prepared by Plasma-Enhanced Atomic Layer Deposition Using Tetrakis(dimethylamino)titanium (TDMAT) and Titanium Tetrachloride (TiCl4) Precursor.

A dataset in this report is regarding an article "Ultrathin Effective TiN Protective Films Prepared by Plasma-Enhanced Atomic Layer Deposition for High Performance Metallic Bipolar Plates of Polymer Electrolyte Membrane Fuel Cells" [1]. TiN (Titanium Nitride) thin films were deposited by Plasma-Enhanced Atomic Layer Deposition (PEALD) method using well known two types of precursor: using tetrakis(dimethylamino)titanium (TDMAT) and titanium tetrachloride (TiCl4), and plasma. Summarized reports, growth characteristics (growth rate as a function of each precursor pulse time, plasma power, precursor and plasma purge time, thickness depending on the number of PEALD cycles), each precursor structural information and the atomic force micrographs (AFM) data are herein demonstrated. For TDMAT-TiN, N2 plasma was used as a reactant whereas, H2+N2 plasma was used as TiCl4-TiN reactant. To apply the bipolar plate substrate, two types of TiN thin films were introduced into Stainless steel (SUS) 316L.

In vitro anti-inflammatory activity of Pothos scandens extract in RAW 264.7 cells.

Pothos scandens, an edible plant, has been traditionally used for reducing swelling and treating wounds, muscle catches, sprains, bone fractures, blisters, and diarrhea. P. scandens ethanol extract (PSE) was evaluated for its anti-inflammatory potential in lipopolysaccharide-stimulated murine RAW 264.7 cells. Present studies showed that PSE reduced the mRNA expression of inducible nitric oxide synthase and cyclooxygenase-2, followed by a decrease in production of nitric oxide and prostaglandin E2. In addition, the secretion of pro-inflammatory cytokines such as interleukin (IL)-6 and IL-1ß was suppressed by PSE treatment. Immunoblotting analyses demonstrated that PSE inhibited the phosphorylation of extracellular signal-regulated kinase and signal transducer and activator of transcription 3 protein, without altering the phosphorylation of inhibitor of κBα, c-Jun N-terminal kinase, and p38 protein kinase. In conclusion, this study demonstrated that P. scandens exhibited anti-inflammatory activity, which might be useful for the development of anti-inflammatory agents.

Signal-Conditioning Block of a 1 × 200 CMOS Detector Array for a Terahertz Real-Time Imaging System.

A signal conditioning block of a 1 × 200 Complementary Metal-Oxide-Semiconductor (CMOS) detector array is proposed to be employed with a real-time 0.2 THz imaging system for inspecting large areas. The plasmonic CMOS detector array whose pixel size including an integrated antenna is comparable to the wavelength of the THz wave for the imaging system, inevitably carries wide pixel-to-pixel variation. To make the variant outputs from the array uniform, the proposed signal conditioning block calibrates the responsivity of each pixel by controlling the gate bias of each detector and the voltage gain of the lock-in amplifiers in the block. The gate bias of each detector is modulated to 1 MHz to improve the signal-to-noise ratio of the imaging system via the electrical modulation by the conditioning block. In addition, direct current (DC) offsets of the detectors in the array are cancelled by initializing the output voltage level from the block. Real-time imaging using the proposed signal conditioning block is demonstrated by obtaining images at the rate of 19.2 frame-per-sec of an object moving on the conveyor belt with a scan width of 20 cm and a scan speed of 25 cm/s.

Anoxic gas recirculation system for fouling control in anoxic membrane reactor.

Anoxic gas recirculation system was applied to control the membrane fouling in pilot-scale 4-stage anoxic membrane bioreactor (MBR). In the anaerobic-anoxic-anoxic-aerobic flow scheme, hydrophilic polytetrafluoroethylene (PTFE) membrane (0.2 µm, 7.2 m(2)/module) was submerged in the second anoxic zone. During 8 months operation, the average flux of the membrane was 21.3 L/(m(2)·hr). Chemical cleaning of the membrane was conducted only once with sodium hydroxide and sodium hypochlorite. Dissolved oxygen (DO) concentration in the second anoxic zone was maintained with an average of 0.19 ± 0.05 mg/L. Gas chromatography analysis showed that the headspace gas in the second anoxic reactor was mainly consisted of N2 (93.0% ± 2.5%), O2 (3.8% ± 0.6%), and CO2 (3.0% ± 0.5%), where the saturation DO concentration in liquid phase was 1.57 mg/L. Atmospheric O2 content (20.5% ± 0.8%) was significantly reduced in the anoxic gas. The average pH in the reactor was 7.2 ± 0.4. As a result, the recirculation of the anoxic gas was successfully applied to control the membrane fouling in the anoxic MBR.