Internal Surface Research Articles

Surface-Area Enhanced Raman Spectroscopy of DNA in Porous Silica: A Quantitative and Reproducible Alternative to Plasmonic-Based SERS.

Despite the success of surface-enhanced Raman spectroscopy (SERS) for detecting DNA immobilized on plasmonic metal surfaces, its quantitative response is limited by the rapid falloff of enhancement with distance from the metal surface and variations in sensitivity that depend on orientation and proximity to plasmonic "hot spots". In this work, we assess an alternative approach for enhancing detection by immobilizing DNA on the interior surfaces of porous silica particles. These substrates provide over a 1000-fold greater surface area for detection compared to a planar support. The porous silica substrate is a purely dielectric material with randomly oriented internal surfaces, where scattering is independent of proximity and orientation of oligonucleotides relative to the silica surface. We characterize the quantitative response of Raman scattering from DNA in porous silica particles with sequences used in previous SERS investigations of DNA for comparison. The results show that Raman scattering of DNA in porous silica is independent of distance of nucleotides from the silica surface, allowing detection of longer DNA strands with constant sensitivity. The surface area enhancement within particles is reproducible (<4% particle-to-particle variation) owing to the uniform internal pore structure and surface chemistry of the silica support. DNA immobilization with a bis-thiosuccinimide linker provides a Raman-active internal standard for quantitative interpretation of Raman scattering results. Despite the high (30 mM) concentrations of immobilized DNA within porous silica particles, they can be used to measure nanomolar binding affinities of target molecules to DNA by equilibrating a very small number of particles with a sufficiently large volume of low-concentration solution of target molecules.

Sustainable high-strength alkali-activated slag concrete is achieved by recycling emulsified waste cooking oil

To mitigate the shrinkage of high-strength alkali-activated slag concrete (AASC), this paper introduces emulsified cooking oil (ECO) and emulsified waste cooking oil (EWCO) into the AASC system. The effects of admixing ECO and EWCO on the compressive strength, drying shrinkage, autogenous shrinkage, carbonation, and sulfuric acid resistance of the AASC are systematically explored. The optimization mechanism is also proposed based on the surface tension and microstructural analysis. The experimental results show that the admixing ECO and EWCO slightly reduce the compressive strength of the AASC by 7.8%. Interestingly, the admixing ECO and EWCO significantly reduce the drying shrinkage and autogenous shrinkage, simultaneously improving the resistance to carbonation and sulfuric acid of the AASC. Specifically, the introduction of 2 wt.% ECO and EWCO can reduce the autogenous shrinkage of the AASC by 66.7% and 41.0%, respectively. Microstructural observations reveal that the addition of ECO and EWCO can reduce the internal surface tension of the AASC, improve the transport and diffusion of the pore solution, and increase the absorbable free water of the slag, which in turn reduces the shrinkage of the composites. It also increases the ionic concentration in the pore solution, resulting in a more complete reaction of the AASC, which can optimize the pore structure and thus improve the durability of the AASC. This study proposes a promising way to develop sustainable alkali-activated slag concrete achieved by recycling waste materials.

Quantifying Contributions of External Forcing and Internal Variability to Arctic Warming During 1900–2021

AbstractArctic warming has significant environmental and social impacts. Arctic long‐term warming trend is modulated by decadal‐to‐multidecadal variations. Improved understanding of how different external forcings and internal variability affect Arctic surface air temperature (SAT) is crucial for explaining and predicting Arctic climate changes. We analyze multiple observational data sets and large ensembles of climate model simulations to quantify the contributions of specific external forcings and various modes of internal variability to Arctic SAT changes during 1900–2021. We find that the long‐term trend and total variance in Arctic‐mean SAT since 1900 are largely forced responses, including warming due to greenhouse gases and natural forcings and cooling due to anthropogenic aerosols. In contrast, internal variability dominates the early 20th century Arctic warming and mid‐20th century Arctic cooling. Internal variability also explains ∼40% of the recent Arctic warming from 1979 to 2021. Unforced changes in Arctic SAT are largely attributed to two leading modes. The first is pan‐Arctic warming with stronger loading over the Eurasian sector, accounting for 70% of the unforced variance and closely related to the positive phase of the unforced Atlantic Multidecadal Oscillation (AMO). The second mode exhibits relatively weak warming averaged over the entire Arctic with warming over the North American‐Pacific sector and cooling over the Atlantic sector, explaining 10% of the unforced variance and likely caused by the positive phase of the unforced Interdecadal Pacific Oscillation (IPO). The AMO‐related changes dominate the unforced Arctic warming since 1979, while the IPO‐related changes contribute to the decadal SAT changes over the North American‐Pacific Arctic.

Identification of a myofibroblast differentiation program during neonatal lung development.

Alveologenesis is the final stage of lung development in which the internal surface area of the lung is increased to facilitate efficient gas exchange in the mature organism. The first phase of alveologenesis involves the formation of septal ridges (secondary septae) and the second phase involves thinning of the alveolar septa. Within secondary septa, mesenchymal cells include a transient population of alveolar myofibroblasts (MyoFBs) and a stable but poorly described population of lipid-rich cells that have been referred to as lipofibroblasts or matrix fibroblasts (MatFBs). Using a unique Fgf18CreER lineage trace mouse line, cell sorting, single-cell RNA sequencing and primary cell culture, we have identified multiple subtypes of mesenchymal cells in the neonatal lung, including an immature progenitor cell that gives rise to mature MyoFB. We also show that the endogenous and targeted ROSA26 locus serves as a sensitive reporter for MyoFB maturation. These studies identify a MyoFB differentiation program that is distinct from other mesenchymal cell types and increases the known repertoire of mesenchymal cell types in the neonatal lung.

Stress mitigation of a thermal engine head block using the bioinspired BGM-FEM method

Structural optimization plays a pivotal role in the design and development of engine heads, as it directly affects the performance, efficiency, and durability of internal combustion engines. In this paper, we propose a novel approach for the thermo-structural optimization of the internal surfaces of the engine heads, using the Biological Growth Method (BGM). The BGM is a bio-inspired technique that mimics the growth patterns observed in some biological organisms, able to achieve superior structural efficiency thus generating optimal designs. The effectiveness of the BGM methodology, coupled with mesh morphing techniques based on Radial Basis Functions (RBF), is in this work demonstrated for several districts, effectively reducing material usage and enhancing structural performance.

Synthesis and toxicity evaluation of a spray consisting of silver nanoparticles, ethylenediaminetetraacetic acid, methylsulfonylmethane, and xylitol on vero cell line

Abstract Introduction: Dental plaque is a biofilm or an accumulation of bacteria that grows in the internal surfaces of the mouth and can be observed as a white to pale yellow layer over or between teeth. The continuous formation and accumulation of dental plaque lead to oral diseases. As a result, it is necessary to prevent the aggregation of dental plaque and clean it daily. Recently, ethylenediaminetetraacetic acid (EDTA) has been utilized in toothpaste to prevent plaque formation as an EDTA-transporting enhancer, methylsulfonylmethane (MSM) can effectively increase its local effect. Xylitol decreases the Streptococcus mutans count by changing the metabolic pathways. Aims: In the present study, we synthesized a solution containing silver nanoparticles, EDTA, MSM, and xylitol and evaluated its toxicity on the Vero cell line through the MTT assay. Materials and Methods: To produce silver nanoparticles, we dissolved silver nitrate in sodium citrate. Then we used a solution of distilled water and polyvinylpyrrolidone, which resulted in the encapsulation and stabilization of silver nanoparticles, and the solution was made by mixing other ingredients. We evaluated the cytotoxicity of this spray using the Vero cell line. We cultured the cells in the 10% FBS-containing RPMI culture medium. For performing the cytotoxicity test, we put 10,000 cells in each well of the 96-well plate, and the next day added the synthesized solution to each well at dilutions 0.05%, 0.1%, 0.2%, 0.5%, 1%, 2%, 5%, and 10%. As the control group, we used 4 wells containing live Vero cells without adding the solution. After 24, 48, and 72 h, we added the MTT solution to each well and incubated the plates at 37°C for 4 h. Finally, we evaluated the rate of living cells by reading the absorbance with an ELISA device at 570 nm. Results and Discussion: We used the Mann–Whitney nonparametric test to evaluate the cytotoxicity of different concentrations of the synthesized spray solution and compare the cell viability rate of groups with the controls in various periods. According to the cytotoxicity results of different concentrations of the spray solution on the Vero cell line, there was no significant difference in cytotoxicity between the 0.05%, 0.1%, 0.2%, and 0.5%, and control groups at 24, 48, and 72 h (P &gt; 0.05). No significant difference existed in cytotoxicity between 1% and 2% concentrations and the controls 24 h after exposure; this became significant after 48 and 72 h (P = 0.014). However, a significant difference existed in cytotoxicity between 5% concentration and the controls 24, 48, and 72 h after exposure (P = 0.014). The CC50 of the spray solution was calculated at 3.51%. Conclusion: The findings of this study showed that the synthesized solution is nontoxic; therefore, this spray solution can be used safely as an oral mouthwash and spray.

Structural Analysis &amp; Effect of Impingement Cooling Flow in the Internal Surface on Temperature Distribution of a Vane in Gas Turbine Using Taguchi Technique

Abstract: Gas turbine always consider one of the most important systems in the modern engineering applications, because it has continuous ability to generate electric power. In gas turbines the major portion of performance dependency lies upon turbine blade design ,the blades are considered one of the important and expensive parts in the gas turbines , where the blades of first stage from failure .The blades of the gas turbine suffer from tensile stresses due to centrifugal forces resulting from the high rotational speed and because of the loading of densegasses at a high temperature and speed ,as the centrifugal force is one of the problems that thedesigner of the turbine blades faces , as the designer aims to reduce stresses within the permissible limit. CFD study was carried out for evaluating the performance of a utility Steam Turbine. The flow in a turbine blade passage is complex and involves understanding of energy conversion in three dimensional geometries. The performance of turbine depends on efficient energy conversion and analyzing the flow path behavior in the various componentsof Steam Turbine. This study seeks the optimization of an axial turbine from a small gas turbine engine developed by ITA using Computational Fluid Dynamics (CFD) and Multi- Objective Optimization techniques focused on geometry changes to maximize the turbine performance. The simulation process will be done through the use of the commercial software SolidWorks.

Ведение ВХР с применением реагентов ВТИАМИН на ТЭЦ с сезонным режимом работы

The main equipment of the thermal power plant (TPP) includes a E-120-7.0-500GM steam boiler produced by LLC “Belenergomash – BZEM” with a single-stage evaporation circuit. The operating mode of the thermal power plant has seasonal characteristics. During the period of February to the end of August the equipment is stopped as a reserve. Dosing of AMINAT PK-3 does not provide the required pH level in steam and feed water, so the reagent for water-chemical regime and preservation has been substituted with VTIAMIN KR-33. The complex reagent VTIAMIN KR-33 ensures both the maintenance of the required quality indicators of the coolant along the path and promotes the formation of a protective barrier film on the internal heating surfaces. To check water-chemical regime, the existing automatic chemical control system has been updated. Panels have been installed for automatic chemical control of pH value, electrical conductivity of direct and H-cationized samples. The filter material has been replaced and the mechanical filters have been connected. The first stage of the filter has been replaced, the second stage of the filter and final purification filters Н-OH have been installed. The authors have demonstrated the possibility to use boilers with seasonal operating modes and measuring the electrical conductivity of cooled water and steam samples as a chemical control of water chemistry. It is found out that dosing the VTIAMIN KR-33 reagent with periodic dosing of the VTIAMIN D-8 reagent into the boiler water prevent the precipitation of hardness salts and other impurities coming with the return condensate. Analysis of the indicators of the water chemistry regime at the thermal power plant when dosing the VTIAMIN KR-33 reagent at two points has shown that the pH value of the feed water is in the range of 8,8–9,0 and the indicators of the water chemistry regime in terms of the content of iron, silicic acid and sodium are also within the norm limits. The composition of the reagents is selected. Flexibility of water chemistry management is ensured. It has been shown that the dosage of the amine-containing reagent VTIAMIN neutralizes the negative effects of aggressive gases (carbon dioxide and oxygen) due to their binding and the formation of a protective film of the magnetite-amine type on heating surfaces. Introduction of the water chemical regime when the equipment is stopped as a reserve does not require additional preservation measures.

PENELLOPE. VI. Searching the PENELLOPE/UVES sample with spectro-astrometry: Two new microjets of Sz 103 and XXCha

The physical mechanism leading to the formation of the blue loop in the Hertzsprung-Russell (HR) diagram is not satisfactorily explained by the evolutionary track of single stars. Rapid rotation and low metallicity drastically modify the internal structures and surface compositions of stars. Therefore, they provide a very significant pattern to investigate the evolutionary properties of the blue loop. In this paper, we mainly explore how rapid rotation and low metallicity have an important impact on the occurrence and extension of the blue loop. To this end, we implemented the rotating stellar evolution model, including the angular momentum transportation and chemical element mixing. We incorporated several initial rotational velocities and two characteristic metallicities in various models to explore the blue loop extension. The blue loop can occur when the hydrogen burning shell merges with the hydrogen--helium abundance discontinuity. We find that the blue loop extension strongly depends on the amplitude and gradient of the hydrogen--helium discontinuity. The hydrogen--helium discontinuity is created by the intermediate convective region or the convective dredge-up. A steeper hydrogen gradient in association with a greater amplitude of the hydrogen abundance discontinuity may favour a hotter star. Both the low metallicity and rapid rotation tend to restrain the development of the outer convective envelope and thus disfavour the occurrence and extension of the blue loop. There are three main reasons for this occurrence. Firstly, the helium core and its core potential can be enlarged by rotational mixing or low metallicity. Secondly, rapid rotation reduces the convective dredge-up depth in the star with $ Z=0.014$ and the mass extension of the intermediate convective region in the star with $ Z=0.0008$. Both of these phenomena lead to a reduction of the amplitude of the hydrogen abundance gradient. Thirdly, strong rotational mixing in the model (i.e. $ ini =350$ Km/s) with $ Z=0.0008$ reduces the energy generation rate from the hydrogen burning shell. Without bending towards higher effective temperature in the HR diagram, the additional helium brought near the H-burning shell associated with the larger He core can cause the star to expand towards becoming a red giant star directly after the core hydrogen burning. Rapid rotation and low metallicity tend to produce surface enrichment of the ratio of nitrogen to carbon and reduce the $ C$ left in the core; this has an important influence on the stellar compactness of the supernovae progenitor.

Validity of Pleuroscopy in Evaluating Pleural Effusions of Uncertain Etiology at the Cardiothoracic Unit of Minia University Hospital, Egypt.

Pleural effusion is a medical condition where an excessive amount of fluid accumulates in the pleural space. This can be caused by inflammation or malignant growth in the body. Doctors use medical thoracoscopy for both diagnostic and therapeutic purposes. This technique allows them to view the internal pleural surfaces and take biopsies of any abnormal lesions within the pleural cavity. This work aimed to evaluate the diagnostic value of pleuroscopy in patients with undiagnosed exudative pleural effusion. A study was conducted on 61 patients who had undiagnosed exudative pleural effusion and were admitted to the chest department at the cardiothoracic unit of the Minia University Hospital. All patients provided written consent and underwent a complete history and clinical examination. Standard laboratory tests, including routine liver and kidney function tests, a complete blood count, and a coagulation profile, were conducted on all patients, along with chest X-rays. If necessary, a chest CT scan was also performed. Diagnostic thoracentesis was done, and the pleural fluid was analyzed for sugar, protein, and lactate dehydrogenase and sent for bacteriological analysis (Gram stain, culture, and acid-fast bacilli smear) and cytopathological examination. Medical thoracoscopy was performed in cases where an etiological diagnosis was not established. A total of 61 patients with undiagnosed exudative pleural effusions were included. A definitive etiological diagnosis was reached in 58 (95%) patients. In 47 (77%) of the studied group, malignant etiology was confirmed; nine (14.8%) had tuberculous pleurisy, one (1.6%) had empyema, and one (1.6%) had inflammatory/autoimmune pleurisy. A definite diagnosis was not reached in three (5%) patients. The malignant pathology was caused by bronchogenic carcinoma in 20 (42.5%) cases, malignant mesothelioma in 10 (21.3%) cases, metastatic malignant deposits from other organs in six (12.7%) cases, and lymphoma in three (6.5%) cases. No serious adverse events related to the procedure were recorded. The most common minor complications were transient chest pain in 34 (55.7%) patients, followed by surgical emphysema in 10 (16.4%) patients. Pleuroscopy is an effective diagnostic tool for identifying the cause of pleural effusion when it is unclear. It is a minimally invasive and straightforward procedure associated with high diagnostic accuracy and low complication rates.

Optimization of tracheoesophageal fistula model established with T-shaped magnet system based on magnetic compression technique.

The magnetic compression technique has been used to establish an animal model of tracheoesophageal fistula (TEF), but the commonly shaped magnets present limitations of poor homogeneity of TEF and poor model control. We designed a T-shaped magnet system to overcome these problems and verified its effectiveness via animal experiments. To investigate the effectiveness of a T-shaped magnet system for establishing a TEF model in beagle dogs. Twelve beagles were randomly assigned to groups in which magnets of the T-shaped scheme (study group, n = 6) or normal magnets (control group, n = 6) were implanted into the trachea and esophagus separately under gastroscopy. Operation time, operation success rate, and accidental injury were recorded. After operation, the presence and timing of cough and the time of magnet shedding were observed. Dogs in the control group were euthanized after X-ray and gastroscopy to confirm establishment of TEFs after coughing, and gross specimens of TEFs were obtained. Dogs in the study group were euthanized after X-ray and gastroscopy 2 wk after surgery, and gross specimens were obtained. Fistula size was measured in all animals, and then harvested fistula specimens were examined by hematoxylin and eosin (HE) and Masson trichrome staining. The operation success rate was 100% for both groups. Operation time did not differ between the study group (5.25 min ± 1.29 min) and the control group (4.75 min ± 1.70 min; P = 0.331). No bleeding, perforation, or unplanned magnet attraction occurred in any animal during the operation. In the early postoperative period, all dogs ate freely and were generally in good condition. Dogs in the control group had severe cough after drinking water at 6-9 d after surgery. X-ray indicated that the magnets had entered the stomach, and gastroscopy showed TEF formation. Gross specimens of TEFs from the control group showed the formation of fistulas with a diameter of 4.94 mm ± 1.29 mm (range, 3.52-6.56 mm). HE and Masson trichrome staining showed scar tissue formation and hierarchical structural disorder at the fistulas. Dogs in the study group did not exhibit obvious coughing after surgery. X-ray examination 2 wk after surgery indicated fixed magnet positioning, and gastroscopy showed no change in magnet positioning. The magnets were removed using a snare under endoscopy, and TEF was observed. Gross specimens showed well-formed fistulas with a diameter of 6.11 mm ± 0.16 mm (range, 5.92-6.36 mm), which exceeded that in the control group (P < 0.001). Scar formation was observed on the internal surface of fistulas by HE and Masson trichrome staining, and the structure was more regular than that in the control group. Use of the modified T-shaped magnet scheme is safe and feasible for establishing TEF and can achieve a more stable and uniform fistula size compared with ordinary magnets. Most importantly, this model offers better controllability, which improves the flexibility of follow-up studies.

The Relevance of Surface Resistances on the Conductive Thermal Resistance of Lightweight Steel-Framed Walls: A Numerical Simulation Study

The accurate evaluation of the thermal performance of building envelope components (e.g., facade walls) is crucial for the reliable evaluation of their energy efficiency. There are several methods available to quantify their thermal resistance, such as analytical formulations (e.g., ISO 6946 simplified calculation method), numerical simulations (e.g., using finite element method), experimental measurements under lab-controlled conditions or in situ. Regarding measurements, when using the heat flow meter (HFM) method, very often, the measured value is based on surface conditions (e.g., temperature and heat flux), achieving in this way the so-called surface-to-surface or conductive thermal resistance (Rcond). When the building components are made of homogeneous layers, their Rcond values are constant, regardless of their internal and external surface boundary conditions. However, whenever this element is composed of inhomogeneous layers, such as in lightweight steel-framed (LSF) walls, their Rcond values are no longer constant, depending on their thermal surface resistance. In the literature, such systematic research into how these Rcond values vary is not available. In this study, the values of four LSF walls were computed, with different levels of thermal conductivity inhomogeneity, making use of four finite elements’ numerical simulation tools. Six external thermal surface resistances (Rse) were modelled, ranging from 0.00 up to 0.20 m2·K/W. The average temperature of the partition LSF walls is 15 °C, while for the facade LSF walls it is 10 °C. It was found that the accuracy values of all evaluated numerical software are very high and similar, the Rcond values being nearly constant for walls with homogeneous layers, as expected. However, the variation in the Rcond value depends on the level of inhomogeneity in the LSF wall layers, increasing up to 8%, i.e., +0.123 m2·K/W, for the evaluated Rse values.

Drosophila hydei as a Potential Vector of Ceratocystis fimbriata, the Causal Agent of Sweetpotato Black Rot, in Storage Facilities.

Ceratocystis fimbriata, the causal agent of sweetpotato black rot, is a pathogen capable of developing and spreading within postharvest settings. A survey of North Carolina sweetpotato storage facilities was conducted to determine the arthropods present and identify potential vectors of C. fimbriata. Sixteen taxonomic categories were recovered, and the genus Drosophila (Diptera: Drosophilidae) accounted for 79% of individuals sampled, with Drosophila hydei being the most abundant species. Behavioral assays were conducted to determine if D. hydei is attracted to C. fimbriata-inoculated roots and if the pathogen could be recovered from external or internal surfaces of the insect. Flies were released in insect-trapping pitchers containing either C. fimbriata-inoculated or noninoculated roots or Petri dishes. No significant differences in fly number were detected in sweetpotato-baited pitchers; however, significant differences were found in the pitcher baited with a mature C. fimbriata culture. Flies were subjected to washes to determine if viable C. fimbriata was present (internally or externally); washes were plated onto carrot agar plates and observed for the presence of C. fimbriata colonies. Both external and internal washes had viable C. fimbriata inocula with no significant differences, and inoculated sweetpotatoes had a significantly higher number of flies carrying C. fimbriata. This study suggests that D. hydei can carry C. fimbriata from infected sweetpotatoes and move viable C. fimbriata inocula both externally and internally, making this the first report of any Drosophila sp. serving as a potential vector for the Ceratocystis genus.

Prompted by surface-engineered honeycomb Turing nanostructures: Reflections on polyamide structure, growth and performance

The robust correlation between the performance of thin-film composite (TFC) reverse osmosis membranes and the polyamide (PA) active layer determines the necessity of precise design of the PA layer, and this regulation primarily involves the surface morphology and internal characteristics of the PA layer. In this study, we fabricated honeycomb Turing structure or nanovoid-rich TFC series membranes using polar/nonpolar organic phase additives. Characterization and simulation results confirmed that the enhancement of membrane performance relied more on the abundant nanovoids within the PA layer rather than the ordered honeycomb lattice surface. Notably, the TFC-nDCE membrane with multilayer nanovoids exhibited an approximately 89 % improvement in water permeability while maintaining satisfactory salt rejection (98.29 %). We emphasized the significant role of nanovoids in the diffusion process of amine monomers and investigated the potential relationship between nanovoids and the degree of surface cross-linking. Building upon this, a new insight into the formation of nanovoids induced by PA anisotropic growth was presented through a careful analysis of the amine monomer diffusion rate and the morphological evolution of nanovoids. The structure-property relationship between internal structures, surface morphologies, and performances was systematically and thoroughly investigated, pointing out the direction for the rational design of TFC membranes.

Coupled surface-internal deformation monitoring in three-dimensional space for freezing-thawing soil

Soil frost deformation significantly influences engineering projects in cold regions. The anisotropic behavior of soil, involving surface and internal deformation in three dimensions (3D), introduces inaccuracies in evaluating freeze–thaw geological hazards. To explore the relationship between internal strain and surface displacement of soil in a 3D space during the freezing-thawing process, a platform for monitoring coupled surface-internal deformation in 3D were developed using binocular recognition technology and a novel 3D strain rosette. Subsequently, a freezing-thawing model test of soil in Dalian Offshore Airport filling is conducted using the platform. The results show that, the internal strain of soil is closely associated with the boundary conditions of the test unit. During freezing test, the vertical strain exhibits a more significant increase in comparison to the horizontal strain. Surface displacements in soil primarily occur during the initial freezing and thawing stages. The variation of surface horizontal displacement in each direction is minimal throughout the freezing-thawing process. A surface freezing boundary leads to an increment in internal strain, while the deep frozen stress relief causes the soil surface expand during thawing. This study provides a suggestion for the control of the cold source in cold region engineering.

Correction on stress intensity factor of root within pipeline girth weld considering various geometric parameters

The study focuses on the stress intensity correction factor (Mk) for internal surface cracks located at the girth pipe root toe. To assess the impact of various parameters on Mk, three-dimensional finite element models are developed. These models take different types of misalignment, a range of variable-wall-thickness ratios, and initial crack depths into account. The findings reveal that the stress intensity correction factor Mk tends to increase with the rise in misalignment and variable-wall-thickness ratio. Conversely, an increase in the initial crack depth leads to a decrease in Mk. The study demonstrates that the Mk values, when accounting for different geometric factors, are significantly higher than those calculated using BS 7910. This suggests that the BS 7910 standard may provide overly optimistic predictions. As a result, a revised Mk formula is proposed, which generally maintains an error margin of less than 10 %. This modified formula offers a significant enhancement to prevailing codes and standards, furnishing a more dependable benchmark for the assessment of structural integrity in pipeline laying procedures.

Experimental and numerical investigation of jet impingement cooling onto a rib roughened concave internal passage for leading edge cooling of a gas turbine blade

Considered is thermal protection of the concave surface within an internal passage, which models the leading edge cavity of vanes or blades of stationary or aero engine gas turbines. Included along the internal surface are different arrangements of V-shaped ribs to further augment surface cooling heat transfer rates. Impingement jets are employed for the cooling, which are configured so that associated cooling air exits the cavity through a crossflow outlet and an array of staggered film cooling holes. The curved part of the asymmetric, concave target plate features a constant radius and connects to straight lines on the pressure and suction sides. Addressed are H/Djet values of 2.7 and 4.0, and Reynolds number Re values of 18,000, 24,000, and 30,000. A maximum crossflow configuration is utilized wherein the coolant flow exits the cooling passage through the film cooling holes and from one end of the passage, as the opposite end is blocked. Different surface configurations are investigated, including 4 V-ribs in four different positions, 8 V-ribs in one position, and a smooth surface of the leading edge cavity. Each V-rib geometry consists of a regular V-rib pointing upstream. A transient thermochromic liquid crystal (TLC) technique is employed to obtain spatially-resolved surface heat transfer data on the internal wall of the leading edge cavity. Resulting experimental heat transfer data are used to validate and verify CFD simulations. Employed for this purpose are steady-state 3D RANS simulations obtained using the OpenFOAM Version 7 numerical code with a kω-shear-stress-transport (SST) turbulence model. Experimentally-measured surface Nusselt number results indicate significant local enhancements adjacent to rib wakes, provided local crossflow velocity values are substantial. Local surface Nusselt number enhancements thus depend upon rib position, but local surface heat transfer increases are most strongly tied to magnitudes of local crossflow velocity. In contrast to these experimental results, CFD simulation results do not show significant variations as rib position is altered. The best thermal performance is associated with 4 V-rib arrangements in two positions, and 8 V-ribs in one position.

On the Post‐Processing of Complex Additive Manufactured Metallic Parts: A Review

Additive manufacturing (AM) is gaining more attention due to its capability to produce customized and complex geometries. However, one significant drawback of AM is the rough surface finish of the as‐built parts, necessitating post‐processing for achieving the desired surface quality that meets application requirements. Post‐processing of complex geometries, such as parts with internal holes, lattice structures, and free‐form surfaces, poses unique challenges compared to other components. This review classifies various post‐processing methods employed for complex AM parts, presenting the experimental conditions for each treatment alongside the resulting improvement in surface roughness as a success criterion. The post‐processing methods are categorized into four groups: electrochemical polishing (ECP), chemical polishing (CP), mechanical polishing, and hybrid methods. Notably, mechanical methods exhibit the highest roughness improvement at 69.9%, followed by ECP (59.9%), hybrid methods (47.4%), and CP (49.5%). Nevertheless, mechanical post‐processing techniques are less frequently utilized for lattice parts, making chemical or electrochemical methods more promising alternatives. In summary, all four categories of post‐processing methods can improve the internal surfaces quality of AM holes. While mechanical methods offer the most substantial roughness improvement overall, chemical and electrochemical methods show particular potential for addressing the challenges associated with complex geometries.

In-situ 3D measurements of water films on the natural grain surface of porous rocks

During fluid displacement, e.g. in aquifers or other fluid reservoirs such as CO2 or H2 storage sites or hydrocarbon reservoirs, water films are expected to form along the internal pore surface due to its wetting properties and capillarity. Near connate water saturation, these water films would dominate the macroscopic multiphase flow behaviour when e.g. water penetrates the porous medium. We use Atomic Force Microscopy (AFM) to study the sub-pore scale configuration of microscale water films on the rough pore surface of Ketton and Estaillades rocks, after drainage of the medium with decane. Then, we compare the results with a numerical simulation and use a film flow model to estimate the relative permeability through these films, which can be potentially used to link the water film configuration to pore- and core-scale responses. We find that the surface coverage and connectivity of the water films varies substantially with capillary pressure. This can affect the permeability of the films up to several orders of magnitude and thus potentially dictate the displacement efficiency at the onset of imbibition, when the brine phase re-enters the pore space. The novel experimental workflow proposed in this study may help future digital assessment of multiphase flow behaviour near connate saturation.

Effective enrichment and separation of three flavonoids from Ohwia caudata (Thunberg) H. Ohashi using magnetic layered double hydroxide/ZIF-8 composites and pCEC

In this study, Fe3O4@ZnCr–layered double hydroxide/zeolitic imidazolate frameworks-8 (MLDH/ZIF-8) magnetically functionalized composites were synthesized by co-precipitation and in situ growth based on the advantages of LDHs and ZIF-8 using Fe3O4 nanoparticles as a magnetic substrate to obtain adsorbents with excellent performance. Moreover, the composite was used for the efficient enrichment of flavonoids in Chinese herbal medicines. The internal structures and surface properties were characterized by SEM, Fourier transform infrared spectroscopy, X-ray diffraction and so on. MLDH/ZIF-8 exhibited a large specific surface area and good paramagnetic properties. The MLDH/ZIF-8 magnetic composite was used as a magnetic solid-phase extraction (MSPE) adsorbent, and a MLDH/ZIF-8 MSPE–pressurized capillary electrochromatography coupling method was developed for the separation and detection of flavonoids (luteolin, kaempferol and apigenin) in a sample of the Chinese herb Ohwia caudata (Thunberg) H. Ohashi. The relevant parameters affecting the extraction efficiency were optimized to determine the ideal conditions for MSPE. 5 mg of adsorbent in sample solution at pH 6, vortex extraction for 5 min, elution with 1.5 mL of ethyl acetate for 15 min. The method showed good linearity in the concentration range of 3–50 μg mL−1 with correlation coefficients of 0.9934–0.9981, and displayed a relatively LODs of 0.07–0.09 μg mL−1. The spiked recoveries of all analytes ranged from 84.5% to 122.0% with RSDs (n=3) between 4.5% and 7.7%. This method is straightforward and efficient, with promising potential in the separation and analysis of active ingredients in various Chinese herbal medicines.