Growth Of Layer Research Articles

Isolation and Molecular Characterisation of Chlorogonium sp. from Industrial Wastewater

Microalgae are photosynthetic, unicellular microorganisms also known as phytoplankton. They are small plant-like entities. In this research, the sample were collected from cement factory in a sterilised 20L container wrapped with foil paper and were transported down to Federal University, Wukari where it was kept in refrigerator at biochemistry laboratory. Blue-Green media (BG-11) was prepared. Wastewater containing Microalgae obtained from cement wastewater pond were cultivated in BG-11 medium to determine the growth of the organism. BG-11 medium contained macronutrients, trace metals and some vitamins which aid the growth of the organism. The wastewater sample containing with suspected microalgae was inoculated (inoculum ratio = 25%) and incubated under atmospheric CO2 at room temperature (30±2°C) in our laboratory for two to three weeks during the incubation period. In order to purify the isolates, the upper growth layer was first decanted into a freshly produced medium and then plated on BG-11 media that had been solidified with 1% agar-agar. For several of the cultures, growth on the agar plates continued for around three weeks. Following repeated sub-culturing, the emerging greenish colonies were re-emerged into a sterile BG-11 agar medium. In isolation of organism from the industrial cement waste water, the isolate was identified by morphological and molecular identification by extracting the DNA, run the electrophoretic analysis and PCR using primers for 18S rRNA eukaryotic microalgal and then run the sequence analysis. The results of this study obtained, indicated that, the electrophoretic result show the band has 1800-2000base pair and the organism isolated from the industrial cement waste water were chlorogonium sp. with a percent similarity of 78.65% and accession number of OR886595 based on data Gene Bank blast results.

Enhanced response and recovery performance of α-hexathiophene sensors for NO2 gas by dual heterogeneous interface

Organic semiconductor gas sensors of α-hexathiophene (α-6 T) films as active layers with dual heterogeneous interface layers of p-hexabiphenyl and pentacene films are prepared by continuous vacuum evaporation method. The enhanced properties of sensors are achieved by modulating the thickness of the α-6 T films. The sensitivity of 1373 %/ ppm and a theoretical low detection limit of 361 ppb are obtained. The sensors demonstrate fast response and recovery properties of 1.05 and 1.51 min for NO2 gas of 20 ppm. The improved performance is attributed to the continuity of the interface layers and high adsorption of island-like growth. This approach is effective to improve organic sensors by introducing dual heterogeneous interface and tuning the growth of active layers.

Insights on the pulsed-DC powder-pack boriding process: Kinetic, statistic, and electric field dynamics in low and medium temperatures

This study presents novel insights into the Pulsed-DC Powder-pack Boriding (PDCPB) process applied to AISI 1018 steel at low (700 °C) and medium (750–850 °C) temperatures for 1, 2, and 3 h of exposure. The electric field, induced with periodic polarity inversion half-cycles of 10 s under 5–10 A, promoted a constant B+ flux, ensuring a uniform boride layer thickness. The growth of the boride layers was estimated using Dybkov's Chemical Interaction Model (DCIM) and analysis of variance (ANOVA). DCIM established the B activation energies in FeB and Fe2B phases, while ANOVA determined the influence of treatment parameters on the total layer thickness.The results demonstrated a reduction of B activation energies in FeB and Fe2B by up to ∼ 23 % and ∼ 15 %, respectively, compared to conventional powder-pack boriding. These reductions were attributed to electromigration and Joule heating phenomena. ANOVA results indicated that temperature was the most significant parameter (77 %) for total (FeB + Fe2B) layer thickness. At the lowest treatment temperature (700 °C), the highest average boriding media resistance (∼ 3.06 Ω) was measured, and the maximal electric field magnitude (3098 V m−1) was determined through computational analysis.

Promotion of silicon–oxygen control and green sustainable recovery from diamond wire saw silicon powder waste based on the viscous flow mechanism

Diamond wire saw silicon powder (DWSSP) waste is a highly promising secondary resource for recycling high-purity silicon, which is crucial for the sustainable development of the photovoltaic (PV) industry. However, because DWSSP is prone to oxidation, the purity and yield of the recovered silicon are generally low. In this study, the oxidation mechanism of DWSSP in water was systematically investigated, and kinetics analysis and microstructure analysis were conducted to determine the relationship between water diffusion and the growth of the oxide layer. The results indicated that oxidation was determined by the kinetic parameter b in the Reisman model. At T < 328 K and particle size > 1.56 μm, b was less than 1, indicating that the oxidation process was governed by the diffusion of H2O molecules. Through temperature regulation to achieve b < 1, the oxidation was inhibited, which could enhance recovery efficiency. Overall, this study demonstrated the feasibility of inhibiting oxidation by regulating the viscous flow of SiO2 molecules to promote the recycling of silicon resources and support sustainable development.

Evaluation of titanium dioxide and tantalum pentoxide nanoparticles for coating NiTi archwires in orthodontics: An in vitro study

Background: This study aims to enhance the biocompatibility of Nickel–Titanium (NiTi) alloy by developing a new coating using titanium dioxide (TiO2) and titanium pentoxide (Ta2O5) through direct current (DC) reactive sputtering technology. Materials and methods: Two distinct coating materials, namely, TiO2 and Ta2O5, were used to fabricate NiTi orthodontic archwires with improved surface properties. TiO2 nanoparticles, with thickness ranging from 21.90 nm to 31.93 nm, were deposited onto NiTi alloy substrates through DC reactive sputtering deposition under different power conditions. Results: X-ray diffraction and field emission scanning electron microscopy validated the uniformity and morphology of the coatings. Immersion tests in simulated body fluid (SBF) revealed significant hydroxyapatite layer growth on TiO2-coated NiTi, especially at a sputtering power of 240 W. Reduced nickel ion release was observed on TiO2 nanoparticles with a thickness of 21.90 nm at 50 W sputtering power compared with 31.93 nm-thick nanoparticles at 240 W. Ta2O5 thin films were deposited on NiTi substrates through DC magnetron reactive sputtering at ~100 °C with a deposition power of 50 W. Structural and morphological analyses through optical microscopy and X-ray diffraction, atomic force microscopy, and scanning electron microscopy revealed the homogeneity and low roughness of the coatings. Biocompatibility assessments in artificial saliva and SBF solutions established that Ta2O5-coated NiTi alloys exhibited superior electrochemical behavior, enhanced corrosion resistance, and diminished Ni ion release compared with uncoated specimens. Conclusion: TiO2 and Ta2O5 coatings not only improved the biocompatibility of NiTi orthodontic archwires but also presented a promising path for advanced biomedical applications. These coatings have potential in improving the cellular behavior and performance of NiTi-based orthodontic devices.

Effect of irradiation on the corrosion of 304 stainless steel in pressurized water reactor (PWR) simulated water chemistry

In this study, the corrosion behavior of pre-ion-irradiated 304 SS is compared to that of un-irradiated 304 SS in simulated Pressurized Water Reactor (PWR) conditions for both early stages of corrosion and longer exposure times. Transmission electron microscopy is used to characterize the oxide scale. The study shows that although the pre-irradiated microstructure does not change the nature of the oxide and its dual-layer structure (i.e. inner/outer oxide layers) formed on 304 SS, the path of growth of the inner oxide layer is affected by the irradiated microstructure resulting in oxide protrusions into the matrix; a mechanism is proposed.

Interfacial characteristics and thermal stability of polymer-derived SiCf/Ti composite fabricated by powder hot isostatic pressing

The novel SiCf/Ti composite is prepared by hot isostatic pressing (HIP) with polymer-derived (PD) SiC fiber and powder titanium alloy as raw materials in this work. The interfacial characteristics and thermal stability of the PD SiCf/Ti composite have been systematically investigated. The interfacial properties of the PD SiCf/Ti composites are quantified to discuss the interfacial reaction mechanisms and kinetics. The results show that with the proposed HIP process, the powder matrix can be near-fully dense, and the matrix and SiC fiber are well bonded with a uniform interfacial layer. The major interfacial products are C-Ti compounds and Si-Ti compounds, which are formed by atomic diffusion reaction. During subsequent thermal exposure conditions, the interfacial layer growth is temperature-dependent and diffusion-controlled, following the parabolic relation and Arrhenius law. The frequency factor k0 is 102–103 times lower than that in the chemical vapor deposition (CVD) SiCf/Ti composites, showing better interfacial thermal stability. After thermal exposure, the element diffusion becomes significant, and the microhardness of the near-interface zone is noticeably greater than the matrix microhardness because of the atomic diffusion of C. The microhardness of both the matrix and near-interface zone reaches the highest value after 900 °C/9 h thermal exposure. It is concluded that the PD SiCf/Ti composites with good thermal stability can be successfully fabricated by powder HIP.

Facilitating superior electrochemical efficacy and ultra rapid kinetic in Co/Ni-free layered oxides for sodium-ion batteries with phosphate-growing layer fast ion conductors

Co/Ni-free layered oxides have garnered significant interest due to their environmental friendliness and facile synthesis methodologies, while facing major challenges of inferior cycling stability and rate capability. Addressing these drawbacks necessitates the enhancement of the surface properties of Co/Ni-free layered oxides. This work introduces a Co/Ni-free layered oxide, Na0.67Mn0.65Fe0.3Al0.05O2 (NMFA), which has been subjected to phosphate-based surface engineering. This targeted surface modification aims to augment the specific surface area and establish a protective layer on NMFA. Such improvements are critical for expanding the effective electrochemical reaction zone, broadening sodium ion diffusion pathways, curtailing the P2-OP4 phase transition, and reducing the activation energy for interfacial charge transfer. This multifaceted surface treatment epitomizes the ingenious design and realization of advanced Co/Ni-free layered oxide cathode materials through straightforward processing techniques. Notably, the NMFA subjected to 3%-AlPO4 surface modification demonstrated an initial discharge capacity of 189.1 mAh/g at 0.1C, maintaining its capacity after 500 cycles at 10C. Additionally, DFT calculations corroborate that such surface growth can bolster electrical conductivity, restrain oxygen liberation and foster sodium ion migration. This elucidates that the phosphate growth layer serves as the oxygen reservoir. Accordingly, this investigation propounds a promising avenue to circumvent the challenges confronting Co/Ni-free layered oxides, thus paving the way for the development of high-performance cathode materials.

Vertical Profile Climatology of Polarimetric Radar Variables and Retrieved Microphysical Parameters in Synoptic and Lake Effect Snowstorms

AbstractThis study derives polarimetric radar vertical profiles and microphysical retrievals for 25 Synoptic Snow (SS) and 23 Lake Effect Snow (LES) cases using the Range‐Defined Quasi‐Vertical Profiles (RD‐QVP), Columnar Vertical Profiles (CVP), and Process‐oriented Vertical Profiles (POVP) methods. For all vertical profile techniques, SS cases exhibit a near‐linear increase in reflectivity from −30 to 0°C whereas ZDR and Kdp locally peak in the dendritic growth layer. LES cases universally exhibit negative ZDR, rather high Z, negligible Kdp, and near‐unity ρhv. Ground measurements from the past OWLeS campaign provide direct evidence that conical graupel may strongly affect these polarimetric measurements in LES bands. Aggregation efficiencies for SS cases are estimated by optimizing the theoretical number concentration (Nt) and mean volume diameter (Dm) steady‐state vertical profiles against radar‐retrieved profiles derived from 20 of the 25 synoptic storm RD‐QVPs. The median estimated aggregation efficiency is approximately 0.15 with a relatively narrow interquartile range that spans from 0.1 to just over 0.2. Values of optimized aggregation efficiencies are nearly independent of the assumed gamma distribution shape parameter. These results are used to derive temperature‐dependent, climatological steady‐state relations for vertical profiles of Nt, Dm, and liquid‐equivalent snowfall rates. These results can be used in numerical weather prediction model aggregation parameterizations and can also provide climatologically representative vertical profiles of radar and microphysical quantities.

Carbon Nitride Nanosheets as an Adhesive Layer for Stable Growth of Vertically-Ordered Mesoporous Silica Film on a Glassy Carbon Electrode and Their Application for CA15-3 Immunosensor.

Vertically ordered mesoporous silica films (VMSF) are a class of porous materials composed of ultrasmall pores and ultrathin perpendicular nanochannels, which are attractive in the areas of electroanalytical sensors and molecular separation. However, VMSF easily falls off from the carbonaceous electrodes and thereby impacts their broad applications. Herein, carbon nitride nanosheets (CNNS) were served as an adhesive layer for stable growth of VMSF on the glassy carbon electrode (GCE). CNNS bearing plentiful oxygen-containing groups can covalently bind with silanol groups of VMSF, effectively promoting the stability of VMSF on the GCE surface. Benefiting from numerous open nanopores of VMSF, modification of VMSF's external surface with carbohydrate antigen 15-3 (CA15-3)-specific antibody allows the target-controlled transport of electrochemical probes through the internal silica nanochannels, yielding sensitive quantitative detection of CA15-3 with a broad detection range of 1 mU/mL to 1000 U/mL and a low limit of detection of 0.47 mU/mL. Furthermore, the proposed VMSF/CNNS/GCE immunosensor is capable of highly selective and accurate determination of CA15-3 in spiked serum samples, which offers a simple and effective electrochemical strategy for detection of various practical biomarkers in complicated biological specimens.

Conductivity and corrosion resistance of TiSiC/MeN multilayer films

TiSiC/MeN (where Me represents Zr, Ti, and Cr) multilayer films were deposited onto 316LSS substrates for proton exchange membrane fuel cells via magnetron sputtering. A comparative investigation of the microstructures and corrosion resistances of the films was conducted. The results indicate that the incorporation of the MeN interlayers interrupts the continuous growth of the columnar TiSiC layer. The TiSiC/MeN multilayer coated 316LSS exhibits better resistance to corrosion and higher electrical conductivity compared to the TiSiC monolayer. The film porosity dominates the corrosion resistance while the electrical conductivity depends on both the phase structure and oxygen concentrations of the films. The multilayer structure suppresses ion diffusion in the etchant solution and decreases the film porosity. However, interfacial delamination caused by the interaction of the solution with the substrate produces the failure of the monolayer TiSiC.

Growth Conditions and Interfacial Misfit Array in SnTe (111) Films Grown on InP (111)A Substrates by Molecular Beam Epitaxy.

Tin telluride (SnTe) is an IV-VI semiconductor with a topological crystalline insulator band structure, high thermoelectric performance, and in-plane ferroelectricity. Despite its many applications, there has been little work focused on understanding the growth mechanisms of SnTe thin films. In this manuscript, we investigate the molecular beam epitaxy synthesis of SnTe (111) thin films on InP (111)A substrates. We explore the effect of substrate temperature, Te/Sn flux ratio, and growth rate on the film quality. Using a substrate temperature of 340 °C, a Te/Sn flux ratio of 3, and a growth rate of 0.48 Å/s, fully coalesced and single crystalline SnTe (111) epitaxial layers with X-ray rocking curve full-width-at-half-maxima of 0.09° and root-mean-square surface roughness as low as 0.2 nm have been obtained. Despite the 7.5% lattice mismatch between the SnTe (111) film and the InP (111)A substrate, reciprocal space mapping indicates that the 15 nm SnTe layer is fully relaxed. We show that a periodic interfacial misfit (IMF) dislocation array forms at the SnTe/InP heterointerface, where each IMF dislocation is separated by 14 InP lattice sites/13 SnTe lattice sites, providing rapid strain relaxation and yielding the high quality SnTe layer. This is the first report of an IMF array forming in a rock-salt on zinc-blende material system and at an IV-VI on III-V heterointerface, and highlights the potential for SnTe as a buffer layer for epitaxial telluride film growth. This work represents an important milestone in enabling the heterointegration between IV-VI and III-V semiconductors to create multifunctional devices.

Seriation of Enzyme-Functionalized Multilayers for the Design of Scalable Biomimetic Mineralized Structures.

Biomimetic hydroxyapatites are widely explored for their potential applications in the repair of mineralized tissues, particularly dental enamel, which is acellular and, thus, not naturally reformed after damage. Enamel is formed with a highly-controlled hierarchical structure, which is difficult to replicate up to the macroscale. A biomimetic approach is thus warranted, based on the same principles that drive biomineralization in vivo. Herein, a strategy for the design of enamel-like architectures is described, utilizing enzymes embedded in polyelectrolyte multilayers to generate inorganic phosphate locally, and provide a favorable chemical environment for the nucleation and growth of minerals. Moreover, a method is proposed to build up seriated mineral layers with scalable thicknesses, continuous mineral growth, and tunable morphology. Results show the outstanding growth of cohesive mineral layers, yielding macroscopic standalone fluoride and/or carbonate-substituted hydroxyapatite materials with comparable crystal structure and composition to native human mineralized tissues. This strategy presents a promising path forward for the biomimetic design of biomineral materials, particularly relevant for restorative applications, with an exquisite level of synthetic control over multiple orders of magnitude.

Self‐Powered Cs3Bi2I9/ZnO Heterojunction Photodetector with Dual‐Band Photoresponse

AbstractCs3Bi2I9/ZnO heterostructures are constructed by the growth of Cs3Bi2I9 layer onto the spin‐coated ZnO films by a modified antisolvent recrystallization method, a series of Cs3Bi2I9/ZnO heterojunction photodetectors (PDs) with varied growth times of Cs3Bi2I9 layer are fabricated. The construction of Cs3Bi2I9/ZnO heterojunction contributes to their improved photoelectric performance compared to ZnO‐based PD, and the Cs3Bi2I9 layer thickness plays an important role in tuning the photoelectric performance of these PDs. At 405 nm and 0 V bias, the optimized 6‐Cs3Bi2I9/ZnO PD generates a high photocurrent of −3.03 µA, a medium on/off ratio of 144.3, and a short response time of 16.4 ms/16.8 ms. It also exhibits superior dual‐band self‐powered photoresponse with two responsivity and detectivity peaks at 380 nm in the UV region and at 430 nm in the visible light region. At 380 nm, this PD presents the highest responsivity of 33.2 mA W−1 and detectivity of 1.07 × 1010 Jones. It is believed that the optimized growth of the Cs3Bi2I9 layer generates a depletion layer with suitable thickness near the interface, and the as‐promoted charge‐carrier separation and transport result in improved self‐powered properties. The rational construction of perovskite‐based heterojunction has proved as an efficient way to achieve self‐powered photodetection.

Effect of cap layer and post growth on-site hydride passivation on the surface and interface quality of InAsP/InP hetero and QW structures

The performance of devices made from III-V compound semiconductors relies heavily on their surface and interface properties. The InAsP/InP material system is recently gaining interest due to its suitability for the next generation of long-haul classical and quantum communication applications. Researchers are studying how surface and interface properties affect the efficiency of the device and concludes that the epitaxial growth conditions responsible for creating surface and interface states require further improvement. To address this, we have studied the effect of the top (cap) layer and post-growth on-site hydride passivation on the properties of InAsP/InP hetero-structures grown using metal-organic vapor phase epitaxy technique. The flow rate and flux ratios of the hydrides significantly affect the surface reaction rates and gas-phase diffusion coefficients, which in turn impact the As↔P exchange mechanisms. Our findings suggest that post-growth on-site arsine passivation encourages the As↔P substitutions at the vicinity of the desorption sites of phosphorus, leading to the arsenic-rich surface of InAsP with the diffused hetero-interfaces. The activation energy for such As↔P exchange reaction mechanism is evaluated as ∼ (1.4 ± 0.3) eV. On the other hand, it has been observed that the thin cap layer of InP protects the surface of the InAsP epilayer and thereby preserving the sharp interface. Further, surface photovoltage and photoluminescence spectroscopy is employed to examine the role of the diffused and sharp interface of InAsP/InP hetero-structures in charge carrier transport, their redistribution and recombination process. Our analysis of the energy transitions occurring in the surface photovoltage and photoluminescence spectrum reveal that the energy band alignment and the subsequent charge carrier redistribution processes is influenced by the surface and interface states. These changes in the surface photovoltage phase spectra of InAsP/InP system also support the role of surface and interface states in the generation and separation of the charge carriers. The study provides insights into the effects of As↔P exchange on surface and interfacial quality, highlighting the implications for optoelectronic device development using InAsP/InP material system.

Enhancement of Wear and Corrosion Resistance of Ti6Al4V Alloy through Hollow Cathode Discharge-Assisted Plasma Nitriding.

In order to improve the wear and corrosion resistance of Ti6Al4V alloy, a Ti-N compound layer was formed on the alloy by plasma nitriding at a relatively low temperature (750 °C) and within an economical processing duration (4 h), in a mixture of NH3 and N2 gases with varying ratios. The influence of the gas mixture on the microstructure, phase composition, and properties of the Ti-N layer was investigated. The results indicated that the thickness of the nitrided layer achieved in a mixed atmosphere with optimal proportions of NH3 and N2 (with a ratio of 1:2) was substantially greater than that obtained in an atmosphere of pure NH3. This suggests that appropriately increasing the proportion of N2 in the nitriding atmosphere is beneficial for the growth of the nitrided layer. The experiments demonstrated that the formation of the surface nitrided layer significantly enhances the corrosion and wear resistance of the titanium alloys.

An optimized live imaging and multiple cell layer growth analysis approach using Arabidopsis sepals.

Arabidopsis thaliana sepals are excellent models for analyzing growth of entire organs due to their relatively small size, which can be captured at a cellular resolution under a confocal microscope. To investigate how differential growth of connected cell layers generate unique organ morphologies, it is necessary to live-image deep into the tissue. However, imaging deep cell layers of the sepal (or plant tissues in general) is practically challenging. Image processing is also difficult due to the low signal-to-noise ratio of the deeper tissue layers, an issue mainly associated with live imaging datasets. Addressing some of these challenges, we provide an optimized methodology for live imaging sepals, and subsequent image processing. For live imaging early-stage sepals, we found that the use of a bright fluorescent membrane marker, coupled with increased laser intensity and an enhanced Z- resolution produces high-quality images suitable for downstream image processing. Our optimized parameters allowed us to image the bottommost cell layer of the sepal (inner epidermal layer) without compromising viability. We used a 'voxel removal' technique to visualize the inner epidermal layer in MorphoGraphX image processing software. We also describe the MorphoGraphX parameters for creating a 2.5D mesh surface for the inner epidermis. Our parameters allow for the segmentation and parent tracking of individual cells through multiple time points, despite the weak signal of the inner epidermal cells. While we have used sepals to illustrate our approach, the methodology will be useful for researchers intending to live-image and track growth of deeper cell layers in 2.5D for any plant tissue.

Investigation of turbulence and interfacial exchange features of the gap area within the fully developed Shallow-Submerged canopy flow

The flow patterns within a longitudinal gap area formed by discontinuous distributions of submerged canopy, as well as the momentum and mass exchange characteristics between the gap area and the overlying free-flow, were studied using high-resolution Large Eddy Simulation (LES). The gap area is located within the fully developed region of submerged canopy flow. The simulations considered four aspect ratios of the gap area, L/h (ranging from 1 to 4), where L and h represent the span of the gap area and the height of the canopy, respectively, and two canopy densities, ϕ = 0.08 and 0.15. Results indicate that recirculation vortices appear only at ϕ = 0.15 and penetrate the downstream canopy patches to varying extents, with the distance of invasion decreasing as L/h increases. Influenced by the recirculation vortices, the bed shear stress in the downstream part of the gap area and the initial section of the downstream canopy patch is significantly increased compared to the fully developed region of the upstream canopy patch. Within the parameter range covered, vertical penetration of the mixing layer into the gap area always occurs, consistently falling into the shear layer growth regime, with significant enhancement of turbulence within the gap area even at L/h = 1. The high momentum entrainment elevates longitudinal velocity and turbulence intensity in the upper corner regions of the downstream canopy patch’s leading edge, combined with localized increases in bed shear stress, potentially destabilizing plants at the forefront of the downstream canopy patch. Although the total momentum exchange across the interface between the gap area and the upper free-flow layer is approximately independent of L/h, larger canopy densities lead to stronger momentum transport, and turbulent transport always dominates. Mass exchange generally increases with L/h, with more efficient vertical mass exchange in ϕ = 0.15 cases at L/h = 3 and 4.

Study of ultrasonic parameters for quality monitoring of plate heat exchanger

Abstract Heat exchangers are crucial heat transfer devices widely used in energy industries such as power generation, oil production, and engine cooling. The plate heat exchanger is one of the most economical and efficient types of exchangers. It transfers heat using metal plates and has a high heat transfer efficiency because the fluid is exposed to a higher plate surface area. However, due to the presence of dissolved or suspended particles in the heat-exchanging fluids, a layer of deposit (fouling layer) is formed on the heat exchanger plates. It results in reduced efficiency of the device. Thus, a common cleaning method, such as chemical-based or manual methods, is employed. However, it always poses a risk of over-cleaning or removal of the protective oxide layer. Thus, an efficient mechanism to monitor the onset of the fouling layer would greatly help to achieve increased efficiency and cost reduction in the cleaning of the plates. Recent advances show ultrasound as one of the promising non-destructive inspection techniques to monitor the growth of the fouling layer. However, the variation in heat-exchanging fluid temperature affects the investigated acoustical parameter measurement. Thus, this research aims to study the linear and nonlinear ultrasonic parameters incorporating temperature-dependent effects from the fluid to provide an accurate real-time monitoring tool. The nonlinear acoustics analysis is experimentally employed in the research using the Second harmonic generation method (SHGM). The proposed research will help design ultrasound-assisted plate heat exchangers for maximum heat transfer efficiency.

Robotic Technology Enables Automated Nondestructive Weld Inspection in Subsea Zone

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 215588, “Automated Nondestructive Weld Inspection in Splash/Subsea Zone,” by Karsten Husby, Magnus Bjerkeng, and Jens T. Thieleman, SINTEF, et al. The paper has not been peer reviewed. _ Jacket structures all over the world are now reaching the limit of their estimated service life, but new discoveries and improved production methods require lifetime extension of the assets. The complete paper presents an automated underwater robot and a nondestructive testing (NDT) eddy-current probe for alternating-current field-measurement analysis of jacket main welds. This robot makes integrity testing, which often is required for lifetime extensions, possible. Introduction Jacket lifetime calculations are based on long service intervals. Some welded braces in the splash zone often are considered unserviceable because of the hostile environment. Thus, divers or remotely operated vehicles cannot be used under normal weather conditions and wave heights. Structural integrity is ensured with long service intervals, often long enough for the lifetime of the jacket. However, multiple jacket platforms are approaching their certified lifespan limit. The question, then, is whether they should be decommissioned, reused, or have their lifespan extended. New discoveries and improved production methods make extended operation desirable for certain fields. For other platforms, repurposing for offshore wind, aquaculture, or geothermal energy may be a cost-effective alternative. Regardless, before any action can be taken, the integrity of the jackets must be tested. There is, therefore, a growing need for subsea condition monitoring of aging offshore jacket steel platforms. To speed up operations and to handle complicated health, safety, and environment (HSE) issues in the splash zone, robots can be used. A robot for NDT inspection in the hostile splash zone is pictured in Fig. 1. The robot clamps itself to the circular braces and is equipped with 3D vision camera, kinematics algorithms, and an NDT probe. Integrity Testing Under Rough Conditions Testing for integrity of critical infrastructure often is performed by different NDT methods. In this study, eddy-current testing was chosen as the preferred method because it is fast and can penetrate layers of marine growth on the surface. The normal procedure is to use lightweight hand-held equipment. The splash zone, however, is often inaccessible under modern HSE standards. In this project, an automated NDT robot helped conduct efficient NDT testing for longer periods in challenging conditions. This robot offloads the NDT operator and makes testing more efficient.