Wide Gap Research Articles

Study on the solder flow in a narrow gap with metal surface texture

Obvious voids in the solder in a narrow gap is a common problem that greatly affects the reliability of mechanical connections. Due to its high heating rate, laser soldering causes more severe voids and even evolves into dispersion of the solder. A method of metal surface texturing is put forward, in which the texture gradient is used to directionally transport solder for lower dispersity, and the pattern design of texture is used to reduce the void rate. The directional transport of solder is realized through the differences in oxidation degree and microstructure of stainless steel surface under different ultrafast laser scanning speeds. The discharge of voids in the solder is achieved through the reservation of the central area in the solder and the oscillation during the laser heating process. Based on the present method, the aggregation of solder is achieved, with the void rate of 18 % and the joining strength of 10.4 MPa.

Single Crystal Growth and Transport Properties of Narrow Band Gap Semiconductor RhP2

Abstract Here, we report the growth of high-quality single crystals of RhP2, and systematically study its structure and physical properties by transport, magnetism, and heat capacity measurements. Single-crystal X-ray diffraction revealed RhP2 adopts a monoclinic structure with the cell parameters a=5.7347(10) Å, b=5.7804(11) Å, and c=5.8222(11) Å, space group P21/c (No. 14). The electrical resistivity ρ(T) measurements indicate that RhP2 exhibits a narrow band gap behavior with the activation energies of 223.1 m eV and 27.4 m eV for two distinct regions, respectively. The temperature-dependent Hall effect measurements show electron domain transport behavior with a low charge carrier concentration. We found that RhP2 has a high mobility μe~210 cm2v-1s-1 with carrier concentrations ne~3.3×1018 cm-3 at 300 K with a narrow band gap feature. The high mobility μe reached a maximum of approximately 340 cm2v-1s-1 with carrier concentrations ne~2×1018 cm-3 at 100 K. No magnetic phase transitions were observed from the susceptibility χ(T) and specific heat Cp(T) measurements of RhP2. Our results not only offer effective potential as a material platform for studying exotic physical properties and electron band structures but also motivate further exploration of their potential photovoltaic and optoelectronic applications.

Development of novel magnetorheological dampers with low-speed sensitivity for flying car suspensions

Abstract As urban traffic environments continue to grow in complexity, there is an urgent need for a versatile mode of transportation that seamlessly transitions between terrestrial and aerial mobility. In these conventional magnetorheological damper (CMRD), the magnetorheological (MR) fluid flowing through the narrow annular gap between the piston and cylinder in CMRD results in a damping force directly proportional to velocity. As velocity increases, the damping force rises sharply, posing a significant risk to the vehicle's mechanical structure and passenger safety. This velocity sensitivity restricts their applications primarily to standard commercial vehicle suspension systems. They face significant challenges when it comes to high-speed impact scenarios. To overcome this limitation, enhance the shock-absorbing capacity of flying cars, ensure passenger safety, and improve passenger comfort during the landing phase, this study introduces a novel magnetorheological damper (NMRD) with unique internal channel structure embedded in a circular permanent magnet. In road travel mode, flying cars equipped with NMRD can maintain a broad dynamic range. During the landing process with high-speed impact, the specialized channel activates to reduce the peak impact force effectively. This feature greatly expands the application range of magnetorheological dampers (MRD). The researches included simulations of the electromagnetic induction phenomenon within the piston, followed by numerical analyses and impact tests to compare the velocity sensitivity of these two distinct impact dampers. Experimental evaluations were conducted using a material testing system (MTS), the peak force and peak acceleration experienced by the two dampers during impact were tested using a dedicated drop hammer apparatus. These tests demonstrate that the NMRD exhibits superior impact resistance performance compared to CMRD. This highlights the promising potential for the NMRD's application within the suspension systems of flying cars.

Exploring the yield and yield contributing traits variability in dolichos bean (Lablab purpureus): A character association and path analysis approach

An experiment was conducted during 2019–20 and 2020–21 at ICAR-Central Institute for Subtropical Horticulture, Lucknow, Uttar Pradesh to evaluate the magnitude of variability in dolichos bean [Lablab purpureus (L.) Sweet] genotypes for important horticultural traits and their associations. The observed range and mean variations of the studied traits revealed a significant genetic diversity among the genotypes. The narrow gap in the genotypic (GCV) and the phenotypic coefficient of variation (PCV) for delineated characters indicated that they are governed by genetic factors, and environmental factors had little or no impact on the phenotypic expression of these traits. The traits including pod yield, days taken to first flowering, weight of pod, plant height, and pod width, showed positive GCV, indicating the presence of additive genes action. Traits such as pod weight, days taken to first flowering, and pod width displayed high heritability and moderate genetic advance, suggesting that the high heritability of these traits is due to the effects of additive genes and that genetic gain can be expected through the phenotypic selection. The higher genotypic correlations revealed an inherent association between the traits. Therefore, the selection criterion for high yield was proposed based on the strong character association between plant height, number of pods/cluster, pod width, and pod weight. The number of pods/plant, followed by the number of clusters/plant had the highest direct positive effect on yield. Consequently, pod yield may be increased through selection of heavier pods, more clusters/ plant, and more pods/cluster.

Green synthesis and studies on citrus medica leaf extract-mediated Au–ZnO nanocomposites: A sustainable approach for efficient photocatalytic degradation of rhodamine B dye in aqueous media

Abstract Incorporating narrow band gap oxide semiconductors and metals into zinc oxide (ZnO) nanostructures broadens the range of light sensitivity to include visible wavelengths. In this study, the photocatalytic degradation of rhodamine B (RhB) dye was studied as a model for environmental pollution in aqueous media. This study describes the use of photodegradation catalysts, including gold (Au), ZnO, and Au–ZnO nanocomposites (prepared in ratios of 90:10 and 95:5) using the extract of Citrus medica leaves. X-ray diffraction (XRD) findings have shown that ZnO nanoparticles (NPs) have a hexagonal wurtzite structure. Field emission-scanning electron microscopy findings have depicted that ZnO NPs have diverse shapes, including spherical, quasi-spherical, hexagonal, and anisotropic, with some clumping. Au exhibits consistent spherical shapes and sizes with even distribution. Au–ZnO (90:10) shows quasi-spherical NPs with interconnected spherical Au, forming a porous and uneven surface. Au–ZnO (95:5) has spherical gold nanoparticles (Au NPs) dispersed on a textured ZnO surface, with some clustering and size variation as evident from the transmission electron microscopy, atomic force microscopy, and diffuse reflectance UV-visible spectroscopy analysis. The characterization results have demonstrated the uniform distribution of Au across the ZnO lattice. Additionally, the XRD patterns confirmed the hexagonal wurtzite structure of ZnO. Furthermore, energy-dispersive analysis of X-ray (EDX)-mapping verified the inclusion of zinc, oxygen, and Au in the hybrid Au–ZnO nanocomposites and their effective distribution. The topological analysis revealed a rough surface for the generated nanostructures. By comparing the results of various techniques, EDX analysis using atomic and weight ratios confirmed the presence of oxygen and Au in the nanocomposite. Additionally, the surface area analysis (BET) test has reported that the adsorption and desorption of nitrogen follow a Type III isotherm. The presence of an H3-type hysteresis loop further confirms the mesoporous nature of the composites, which reports the presence of wedge-shaped pores. The Au–ZnO (90:10) nanocomposite exhibits a higher surface roughness compared to other composites. In addition, this UV-visible diffuse reflectance spectroscopy has enumerated the band gaps of various nanomaterials using UV-visible spectroscopy. Moreover, the analysis has unveiled that combining ZnO with Au NPs (doping) improved the photocatalytic performance of ZnO. This improvement is attributed to the formation of additional energy levels within the ZnO band gap due to the presence of Au ions. Experimental investigation of the breakdown of RhB dye under visible light irradiation revealed superior photocatalytic activity for the Au–ZnO (90:10) nanocomposite compared to both Au–ZnO (95:5) and pure ZnO and Au counterparts. Multiple experiments confirmed the effective photodegradation and removal of RhB dye from the aqueous medium using the nanocatalyst under visible light irradiation. Under optimal conditions (1.0 g·L−1 photocatalyst, 10 ppm RhB, and pH 10), 99% photodegradation efficiency was reached within 50 min of irradiation. Investigation of reactive species revealed that the increased effectiveness of photodegradation in Au–ZnO (90:10) stems from the presence of photogenerated holes and hydroxyl radicals. The study also analyzed the reaction kinetics and order, and the reusability of the best photocatalyst Au–ZnO (90:10)) was confirmed through five consecutive cycles, demonstrating its sustained effectiveness in photodegradation. These findings highlight the potential of Au–ZnO (90:10) nanocomposite as a promising material for photocatalytic degradation of organic dyes.

Optimization design of custom pattern based on microclimate heat transfer

PurposeThe aim of this paper is to achieve a reasonable microclimate between clothing and the human body and optimize the custom dress pattern.Design/methodology/approachAn interactive design method of 3D modeling, virtual try-on and heat transfer simulation are used. First, a 3D dress is designed with nonuniform rational B-splines curves and tried on virtually. After that, the heat transfer in the body-air-clothing microclimate and temperature distributions on the clothing surface are obtained. Based on the heat transfer in the body-air-clothing system, we design a method to improve the thermal comfort by optimizing the garment pattern digitally. Then, this paper utilized two heat transfer validating indexes to quantify the improvement of thermal comfort, and evaluate the modified model of dress.FindingsThe microclimate under the clothing is varied with the air gap distance, and the heat transfer on the area of the clavicle, bust point and front abandon are higher than other parts due to the narrow air gaps. In view of thermal comfort, the pattern optimization changes the distance ease and reforms the air circulating efficiency. The mean heat transfer and its standard variance are changing by about 10% and more than 20%. Thus, the heat transfer evaluation indexes are suitable to represent the heat transfer and thermal comfort in the microclimate system.Research limitations/implicationsIt can be concluded that the methodology proposed in this paper has the advantage of interactive design, 3D visualization and local heat transfer simulation. This technology meets the need of personalized customization and well-considered garment and has broad application prospects.Originality/valueThis study demonstrates that modifying the distance ease on body key girths based on heat transfer is a reliable way to improve thermal comfort. This method meets the consumers’ demand of the comfort of body-fit clothing under the condition of daily activities.

Synthesis and properties of an O-doped aromatic belt.

A new macrocyclic arene, dibenzofuran[3]arene, was synthesized, which could be conveniently transformed to an O-doped aromatic belt with a rigid ring-shaped structure and deep cavity. Moreover, the O-doped aromatic belt also showed a high HOMO energy and a narrow HOMO-LUMO gap experimentally and theoretically.

Facile hydrothermal synthesis of a multifunctional copper zinc tin sulfide (CZTS) nanoparticle-coated sepiolite fiber composite: structural characterization and photocatalytic properties

This work presents a facile hydrothermal synthesis method for fabricating a multifunctional composite of copper zinc tin sulfide (CZTS) nanoparticles coated onto sepiolite fibers. Morphological analysis confirms the firm attachment of approximately 10 nm CZTS nanoparticles onto the sepiolite surface. Elemental analysis verifies the presence of constituent elements from both CZTS and sepiolite, with a slight deficiency in Cu and an abundance of Zn observed. The compositional formula of CZTS in the composite is estimated as Cu1.93Zn1.05Sn0.98S4.04. Notably, the material exhibits a narrow band gap of 1.5 eV, enabling effective utilization of the entire visible light spectrum, making it promising for photocatalytic applications. BET nitrogen adsorption/desorption measurements reveal a substantial surface area of approximately 85.720 m2 /g, confirming the composite’s versatility and applicability, particularly in photocatalysis and adsorption processes. Additionally, X-ray diffraction analysis indicates reflections consistent with the crystal structures of kasterite CZTS and sepiolite, further confirming the composite’s composition. The multifunctional CZTS/Sepiolite composite demonstrates exceptional potential for simultaneous photocatalytic degradation and adsorption of organic pollutants, presenting a promising avenue for sustainable water treatment applications.

Asymmetric Coordination of Bimetallic Fe-Co Single-Atom Pairs toward Enhanced Bifunctional Activity for Rechargeable Zinc-Air Batteries.

The advancement of rechargeable zinc-air batteries (RZABs) faces challenges from the pronounced polarization and sluggish kinetics of oxygen reduction and evolution reactions (ORR and OER). Single-atom catalysts offer an effective solution, yet their insufficient or singular catalytic activity hinders their development. In this work, a dual single-atom catalyst, FeCo-SAs, was fabricated, featuring atomically dispersed N3-Fe-Co-N4 sites on N-doped graphene nanosheets for bifunctional activity. Introducing Co into Fe single-atoms and secondary pyrolysis altered Fe coordination with N, creating an asymmetric environment that promoted charge transfer and increased the density of states near the Fermi level. This catalyst achieved a narrow potential gap of 0.616 V, with a half-wave potential of 0.884 V for ORR (vs the reversible hydrogen electrode) and a low OER overpotential of 270 mV at 10 mA cm-2. Owing to the superior activity of FeCo-SAs, RZABs exhibited a peak power density of 203.36 mW cm-2 and an extended cycle life of over 550 h, exceeding the commercial Pt/C + IrO2 catalyst. Furthermore, flexible RZABs with FeCo-SAs demonstrated the promising future of bimetallic pairs in wearable energy storage devices.

MOF-on-MOF-derived Fe[sbnd]Zr bimetal oxides supported on hierarchically porous carbonized wood to promote photo-Fenton degradation of ciprofloxacin

MOF-on-MOF derivatives have served as promising heterogeneous Photo-Fenton (hetero-PF) catalysts, but its self-aggregation instability and limited photocatalytic activity inhibit the effective ciprofloxacin (CIP) removal. In this study, a novel hetero-PF catalyst, dual MOF-derived FeZr bimetal oxide embedded in a wood-converted porous carbon skeleton (ZrO2@Fe3O4/WPC), was successfully synthesized via a straightforward in-situ growth strategy combined with co-pyrolysis. The as-prepared hybrid photocatalysts, featuring a large surface area, effective porous structures, efficient light absorption and a narrow band gap demonstrated superior photo-Fenton activity, accomplishing approximately 99.1 % degradation of CIP within 120 min under neutral conditions. Furthermore, the ZrO2@Fe3O4/WPC hetero-PF system showed satisfactory performance in treating real water matrices. It can be inferred that the abundant heterojunctions, resulting from the synergistic effect of FeZr mixed oxide and the porous carbonized wood substrate, contributed to the rapid separation and migration of photogenerated electron-hole pairs. Meanwhile, the FeZr site in the graphitized carbon framework activates H2O2 to accelerate the generation of the OH and O2− radicals, leading to a heightened degradation efficiency of CIP. Besides, the photodegradation pathway of CIP is obtained by liquid chromatography-mass spectrometry (LC-MS). This study indicates that combining porous carbonized wood and heterometallic MOF derived materials provides a promising method for realizing high-efficiency photo-Fenton degradation of antibiotic water pollutions.

“Edge in-situ heterogeneous” BiOI based on defect engineering and non-noble metal deposition: Boosting visible-light photocatalytic sterilization

The inherent narrow band gap of bismuth oxyiodide (BiOI) consistently leads to the rapid recombination of photogenerated carriers, significantly constraining its practical utility. To combat this shortcoming, we devise a Bi/BiOI1−x (BB) nanosheet with edge heterostructure. It is modified by the introduction of both iodine defects and in-situ bismuth deposition through high-temperature calcination and solvothermal strategy. Notably, the in-situ deposition of bismuth enhances the visible-light absorption ability of BiOI. And the incorporation of iodine defects initiates a modification in the band position of BiOI, ultimately diminishing the electron-hole recombination rate effectively. More importantly, facilitated by the major work function of bismuth, a Schottky barrier is formed at the BB heterojunction interface, which effectively promotes the separation of photogenerated charges within BB. And the photocurrent intensity of BB is 4 times higher than that of pure BiOI. These ingenious designs result in a significant boost in the generation of reactive oxygen species (ROS) through the accumulation of electrons and holes on the surfaces of both Bi and BiOI1−x. And BB photocatalyst shows an outstanding broad-spectrum bactericidal performance. The antibacterial rates against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) are 88.01% and 90.01%, respectively, which are increased by 80.6% and 83.8% compared with BiOI. Moreover, in vivo experiments provide compelling evidence for the BB photocatalyst’s potential in promoting wound healing. The healing rate after BB treatment has already reached more than 95% on the fifth day. This work offers valuable insights on enhancing the sterilization performance of photocatalysts based on the synergistic effects of defect engineering and non-noble metal deposition.

2,2′‐Thienoviologens with Low Reduction Potential for Electrochromism and Visible‐Light‐Driven Hydrogen Evolution Using g‐C3N4‐Based Composites via Hydrogen Bonds

AbstractA series of sulfur‐bridged 2,2′‐viologens, 2,2′‐thienoviologens (2,2′‐SV2+) with propyl bridge and hydroxyl bridges, are synthesized for the first time. The 2,2′‐thienoviologens exhibited improved visible‐light absorption, narrow energy gap, more negative reduction potential (160 mV lower than 4,4′‐thienoviologens) and more stable free radical states compared with 4,4′‐thienoviologens and parent 2,2′‐viologens. The utilization of femtosecond transient absorption (fs‐TA) demonstrated that 2,2′‐thienoviologen can produce distinct charge‐separated states under visible light excitation. Due to their excellent photophysical and electrochemical properties, the 2,2′‐thienoviologens are used for electrochromic devices and combined with g‐C3N4 via hydrogen bonds for visible‐light catalytic production. Based on the advantageous electron‐donating properties of 2,2′‐SV2+, the hydrogen release efficiency of the 2,2′‐thienoviologens‐modified composites is 8542 µmol·h−1·g−1, a value that is the highest reported for hydrogen production from organic small‐molecule‐modified g‐C3N4 and 78 times higher than that of unmodified g‐C3N4. This study presents a concise method to convert solar energy and broaden the potential applications of 2,2′‐viologens in photocatalytic systems.

Near-Infrared Emission Beyond 900 nm from Stable Radicals in Nonconjugated Poly(diphenylmethane).

Organic radicals with narrow energy gaps are highly sought-after for the production of near-infrared (NIR) fluorophores. However, the current repertoire of developed organic radicals is notably limited, facing challenges related to stability and low fluorescence efficiency. This study addresses these limitations by achieving stable radicals in nonconjugated poly(diphenylmethane) (PDPM). Notably, PDPM exhibits a well-balanced structural flexibility and rigidity, resulting in a robust intra-/inter-chain through-space conjugation (TSC). The stable radicals within PDPM, coupled with strong TSC, yield a remarkable full-spectrum emission spanning from blue to NIR beyond 900 nm. This extensive tunability is achieved through careful adjustments of concentration and excitation wavelength. The findings highlight the efficacy of polymerization in stabilizing radicals and introduce a novel approach for developing nonconjugated NIR emitters based on triphenylmethane subunits.

Synergistic effects of coordinated metals and fluoridation in metal-covalent organic framework for efficient triboelectric nanogenerator

Improving the performance of triboelectric nanogenerators (TENG) depends on the development of new and effective friction electrode materials. Metal-covalent organic frameworks (MCOFs) are promising functional materials with applications in various fields owing to their structural diversity and tunability; howerver, the use of MCOFs in the preparation of TENG devices has not yet been investigated. In this study, a MCOF (Cu-COF) was designed and constructed via the post-metalation method by introducing transition metal ions through the delicate chelating structure of a CF3 substituted covalent organic framework (CF3-COF) for the first time. The constructed Cu-COF exhibited higher triboelectric nanogenerator output performance, with a peak value of short circuit current of 104.0 µA and an output voltage of 1107 V, which are 1.47 and 1.39 times those of CF3-COF, respectively. This can be attributed to the excellent charge density, improved conductivity and narrow band gap of Cu-COF. In addition, the Cu-COF-based TENG exhibits excellent stability and power density, and is capable of lighting 1440 commercial green LEDs. This study also suggests that the strategy for engineering metalation coordination environments on the skeletons of COFs could provide a novel method to fabricate TENG devices with MCOFs.

Near‐Infrared Emission Beyond 900 nm from Stable Radicals in Nonconjugated Poly(diphenylmethane)

AbstractOrganic radicals with narrow energy gaps are highly sought‐after for the production of near‐infrared (NIR) fluorophores. However, the current repertoire of developed organic radicals is notably limited, facing challenges related to stability and low fluorescence efficiency. This study addresses these limitations by achieving stable radicals in nonconjugated poly(diphenylmethane) (PDPM). Notably, PDPM exhibits a well‐balanced structural flexibility and rigidity, resulting in a robust intra‐/inter‐chain through‐space conjugation (TSC). The stable radicals within PDPM, coupled with strong TSC, yield a remarkable full‐spectrum emission spanning from blue to NIR beyond 900 nm. This extensive tunability is achieved through careful adjustments of concentration and excitation wavelength. The findings highlight the efficacy of polymerization in stabilizing radicals and introduce a novel approach for developing nonconjugated NIR emitters based on triphenylmethane subunits.

Characteristics of turbulent core–annular flow with water-lubricated high viscosity oil in a horizontal pipe

Direct numerical simulations are performed to investigate the characteristics of a turbulent core–annular flow with water-lubricated high viscosity oil in a horizontal pipe. Six different superficial velocity ratios ( $\,j_w/j_o = 0.057\unicode{x2013}0.41$ ) are examined by changing the water superficial velocity $j_w$ for a fixed oil superficial velocity $j_o$ . The pressure drops in the pipe and the shapes of the phase interface agree well with those from previous experiments. The oil core flow is almost a plug flow, and the gaps between the phase interface and pipe wall are narrow and wide near the upper and lower surfaces of the pipe, respectively, due to the buoyancy. Within a narrow gap, water is confined mostly in a valley region of the wavy phase interface and hardly goes through its crest. On the other hand, water near the phase interface at a wide gap convects downstream almost at the core speed and the flow near the wall is similar to that of single-phase wall-bounded turbulent flow. The annular flow is characterized by three different regimes depending on the clearance Reynolds number ( $Re_c$ ) based on the core velocity and local gap size: laminar Couette flow driven by the core for $Re_c \le 600$ , transitional flow for $600 < Re_c < 2500$ and turbulent flow for $Re_c \ge 2500$ . The minimum pressure drop occurs at $j_w/j_o = 0.11$ in the early transition regime. For all $j_w/j_o$ considered, the negative lift force acting on the core comes from the pressure force which balances the buoyancy.

Photo‐Assisted Bifunctional Cathodes with Lower Energy Gap and Broadened Light Absorbing Region for Lithium‐Ion Batteries – Extended Conjugation Through Customization

AbstractHigh‐performance optoelectronic bifunctional cathode materials may simultaneously seize and store solar energy in lithium‐ion batteries to boost their storage capacity. However, such photoactive cathodes with typical intrinsic features are generally limited for UV light applications and offer poor sunlight harvesting which results in lower energy density. Here, the assembly of two oligomers, poly(vat blue 6) (PVB6) and poly(vat blue 6 sulfide) (PVB6S) is reported, through polymerization to extend the conjugated structure of organic optoelectronic small molecules. These oligomers are effectively employed as photo‐assisted bifunctional cathodes for lithium‐ion batteries. The extended conjugated structure narrows the energy gap, promoting exciton dissociation and expanding the light absorption region. PVB6S possesses a narrow energy gap of 1.565 eV, and the discharge‐specific capacity of the battery with PVB6S is enhanced from 203 to 411 mAh g−1 under light illumination, which is approximately twice the original capacity. This demonstrates the extended conjugated structure and charge separation in a cell, which synergistically contributes to the rational design of photo‐assisted bifunctional cathode materials and complementary enhances the performance of lithium‐ion batteries.

Modified successive ionic layer adsorption and reaction for interconnected bismuth vanadate nanograins: Highly active visible light harvesting photoanodes

A modified successive ionic layer adsorption and reaction (SILAR) method is developed for depositing interconnected bismuth vanadate (BiVO4) nanoparticles with improved visible light harvesting activity. Facile control of preparative parameters like deposition cycles, anionic precursor, pH and deposition temperature significantly altered BiVO4 surface morphology. BiVO4 thin films prepared with Na3VO4 anionic precursor show dispersed nanoparticles type morphology and that deposited with NaVO3 precursor displays 3D interconnected nanoparticles morphology. The BiVO4 photoanodes with 3D interconnected nanoparticles morphology exhibits an excellent photocurrent density of 5.19 mA cm−2 at 1.23 V vs. RHE with superior photostability and improved applied bias photon to current efficiency (ABPE) (1.50 %) compared to dispersed nanostructured BiVO4 photoanodes. The excellent photoelectrochemical (PEC) characteristics of BiVO4 photoanodes with 3D interconnected nanoparticle morphology can be ascribed to porous morphology, optimum thickness, narrow band gap energy and favorable electronic band structure for water splitting. The current study illustrates the usefulness of the modified SILAR approach for depositing 3D interconnected BiVO4 nanoparticle morphology in a single step that is superior and efficient to previously reported multistep processes.

Unraveling the potential of heteroanionic titanium oxycarbide photocatalysts for detoxifying SARS-Cov-2 antigen rapid test kit reagent solution in water sources

In the last few years, the COVID-19 pandemic has increased the usage of antigen rapid test (ART) kits and improper disposal of these kits has led to the mixing of toxic chemical compounds present in the ART reagent solution container into drinking water sources. When consumed with drinking water, these compounds can be harmful and toxic to both humans and aquatic life. Therefore, this research presents a study on the photocatalytic degradation of the Antigen Rapid Test-Reagent solution (ART-RS) using a single-phase titanium oxycarbide - TiO0.25 C0.75 (TiOC) photocatalyst synthesized through a solid-state reaction. The synthesized samples were studied using various characterization tools to analyze their structural, morphological, and optical characteristics. In the photocatalytic experiment, it was found that the synthesized titanium oxycarbide photocatalyst exhibited superior ART-RS degradation efficiency of 77% compared to commercial titanium dioxide (22%). The improved photocatalytic degradation efficiency of ART-RS is attributed to a combination of several factors. These factors include a narrower band gap, more efficient charge transfer kinetics, enhanced absorption of visible light, and an upward shift of the valence band (VB) edge in titanium oxycarbide. These collective effects contribute to the enhanced ART-RS photocatalytic degradation activity.

Validation of the added mass effect in the narrow gaps of nuclear reactor pressure vessels

Nuclear reactor pressure vessels (RPVs) must be robust to external environmental excitations such as seismic loads. Precise numerical models that predict the dynamic responses to external loads are crucial for evaluating the safety of RPVs. Notably, in RPVs submerged in reactor coolant, it is necessary to examine the added mass effect of the fluid via fluid-structure interaction (FSI) analysis, employing either an analytical approach or a numerical analysis. The present study focuses on modeling and analyzing the added mass effect in the narrow gaps associated with the dense structural layout in the reactor. In this context, this paper validates analytical and numerical models that accurately describe the added mass effect for two cases: (i) simple concentric cylinders with a narrow gap filled with fluid and (ii) a complex small-scale RPV with narrow gaps also filled with fluid. Initially, the analytical model, employing Lagrange's equation of motion and velocity potential, and the numerical model, utilizing FE modeling in acoustic FSI through ANSYS, were validated through experimental modal testing for the added mass effect in the narrow gap between simple concentric cylinders. The analytical model for the concentric cylinders indicates that the added mass diverges to infinity as the gap approaches zero, which should be examined carefully. Through experiments for the concentric cylinders, the analytical and FEM-based added mass effects were validated with a natural frequency error of 3 %. Subsequently, based on the results for the concentric cylinders, a complex numerical model of the small-scale reactor with complex boundary conditions was developed and cross-validated through corresponding experimental modal testing of the small-scale RPV. The added mass model for the narrow gaps in the RPV was validated by substantial agreement of eight representative modes, as demonstrated by a 5 % natural frequency error.