Concave Defects Research Articles

The pulmonary-vascular-stump filling defect on CT post lung tumor resection: a predictor of cancer progression

BackgroundTo explore the pulmonary-vascular-stump filling-defect on CT and investigate its association with cancer progression.MethodsRecords in our institutional database from 2018 to 2022 were retrospectively analyzed to identify filling-defects in the pulmonary-vascular-stump after lung cancer resection and collect imaging and clinical data of patients.ResultsAmong the 1714 patients analyzed, 95 cases of filling-defects in the vascular stump after lung cancer resection were identified. After excluding lost-to-follow-up cases, a total of 77 cases were included in the final study. Morphologically, the filling-defects were dichotomized as 46 convex-shape and 31 concave-shape cases. Concave defects exhibited a higher incidence of increase compared to convex defects (51.7% v. 9.4%, P = 0.001). Among 61 filling defects in the pulmonary arterial stump, four (6.5%) increasing concave defects showed the nuclide concentration on PET and extravascular extension. The progression-free survival (PFS) time differed significantly among the concave, convex, and non-filling-defect groups (log-rank P < 0.0001), with concave defects having the shortest survival time. Multivariate Cox proportional hazards analysis indicated that the shape of filling-defects independently predicted PFS in early onset on CT (HR: 0.46; 95% CI: 0.39–1.99; P = 0.04). In follow-ups, the growth of filling-effects was an independent predictor of PFS (HR: 0.26; 95% CI: 0.11–0.65; P = 0.004).ConclusionsCertain filling-defects in the pulmonary-arterial-stump post lung tumor resection exhibit malignant growth. In the early onset of filling-defects on CT, the concave-shape independently predicted cancer-progression, while during the subsequent follow-up, the growth of filling-defects could be used independently to forecast cancer-progression.

Improved Performance of QDSSCs Can Be Achieved by Constructing a Transparent Anatase TiO2@MWCNT Photoanode Based on the Bionic Mountain Lotus.

In this research, the structural characteristics of the mountain holly leaf were emulated. It was observed that after the initially uneven surface of the petals is filled with infiltrated water, it exhibits a distinctive transparent beauty after rainfall. Furthermore, the presence of leaf veins enhances the structural strength of the petals and facilitates nutrient transport. Inspired by previous studies on double-layer spin-coated films, we further developed and designed the TA TiO2@MWCNT photocathode thin film. This innovative film incorporates multiwalled carbon nanotubes (MWCNT) into a previously established TA TiO2 photocathode thin film. The inclusion of MWCNT results in the formation of a three-dimensional highway structure, where MWCNT intertwines within the TA TiO2 film. Under the operational state of immersion in the electrolyte, it maintains a level of transparency similar to that of the TA TiO2 photoanode thin film. The high-temperature sintering process results in the oxidation and depletion of MWCNTs on the surface of the film, leaving behind uniformly dispersed concave defects, thereby greatly enhancing the specific surface area. The findings demonstrate that the optoelectrode of high transparency and high specific surface area, TA TiO2@MWCNT, comprehensively enhances the performance of the solar cells. The transparent QDSSC surpasses its counterparts for the first time, achieving a power conversion efficiency (PCE) of 6.335%. This sets the stage for new materials and innovative approaches in the field of solar cells and other titanium dioxide film-related areas.

Constructing surface concave defects on NiFe layered double hydroxides by electrochemical reduction for efficient oxygen evolution reaction

NiFe-LDH has been proved to be one of the most effective non-noble metals electrocatalysts for oxygen evolution reaction, but inadequate exposure of the active sites prevents its performance from being comparable to noble metal catalysts. Herein, we prepare 3D nanoflower-like NiFe-LDH composed of bumpy, thin nanosheets by hydrothermal combined with electrochemical reduction method. Various characterization results reveal that the nanosheets of NiFe-LDH are partial exfoliated and reduced by the atomic H* and H2 in the electrochemical reduction process, which results in the generation of surface oxygen vacancies (Vos), forming plenty concave defects in the surface of nanosheets. The optimized partially surface reduced NiFe-LDH exhibits an outstanding catalytic activity for OER with long-term stability. The overpotential is only 185 mV at 100 mA cm−2 with no obvious deterioration in 100 h operation process. The enhanced activity is attributed to the more exposure and the adjustment of electron density of metal active sites. This work provides a universality method to strip nanosheets and induce oxygen vacancies on oxygenated catalysts.

Forming characteristics and mechanisms of micro-arc oxidation coatings on magnesium alloys based on different types of single electrolyte solutions

To systematically investigates the forming ability and properties of micro-arc oxidation (MAO) coatings on magnesium alloys using different types of single electrolytes and further enhance the understanding of the coating formation mechanism from multiple perspectives. MAO treatments were performed in three types of single electrolyte solutions containing either sodium silicate, potassium fluoride, or sodium hydroxide, which were severally designed in terms of main salts, additives, and alkaline substances. The results show that MAO coatings could still be formed in the three single electrolyte solutions; however, the sparks and observable phenomena on the sample surface differed obviously from those in multicomponent electrolytes. In potassium fluoride and sodium hydroxide electrolytes, sparks occurred continuously at fixed positions on the sample surface, forming concave defects with uneven distributions of Mg, F, and O on the coating surface. In addition, a larger response current was observed in the sodium hydroxide electrolyte during MAO; this is disadvantageous in reducing energy consumption. The coating obtained in the potassium fluoride electrolyte had the highest thickness and number of micropores because of the synergy between the electrochemical process and the spark state on the sample surface. In contrast, the coating prepared in the sodium silicate electrolyte exhibited better corrosion resistance because of a certain thickness and good compactness.

Simulations and Experiments on the Micro-Milling Process of a Thin-Walled Structure of Al6061-T6.

Aluminum alloy (Al6061-T6) is an alloy with strong corrosion resistance, excellent disassembly, and moderate strength, which is widely used in the fields of construction, automobile, shipping, and aerospace manufacturing. Researching on the influence of machining precision and surface quality on the micro-milling process of thin-walled structures of Al6061 is highly significant. Combined with the two simulations (DEFORM-3D simulation and interactive finite element numerical simulation (FEM)) and milling experimental verification, the deformations, errors, and surface quality of milling thin-walled Al6061 were analyzed. The simulations and experimental results show that the deformation of milling a micro thin-walled structure was caused by the vertical stiffness of the thin-walled structure and the cutting force. Surface micromorphology further characterized and showed a poorer quality area, top burr, and concave defects, which directly affect machining quality. It is necessary to improve the surface quality, reduce the surface defects, and increase the stiffness at the top of thin-walled structures in future work.

A case of bipartite patella and vastus notch from Kneževići hillfort - Malo Libinje, Croatia

Here we present six adult patellae with superolateral concave defects observed amongst the remains of at least 28 individuals retrieved from four Late Iron Age burials from Kneževići hillfort - Malo Libinje, Croatia. The right patella of an adult individual displays a rough-edged concave defect on superolateral side of the bone called bipartite patella. Other five patellae show concave defects with smooth edges also located on superolateral side; a defect known as vastus notch. Though physically similar, the two conditions are etiologically distinct. A large amount of observed cases of vastus notch in this assemblage may indicate that these individuals frequently performed activities involving kneeling and/or squatting. This is the first documented case of joint occurrence of bipartite patella and vastus notch in a Croatian skeletal assemblage, but also the largest amount of patellae with vastus notch in an archaeological population from Croatia recorded so far.

Study of surface topography detection and analysis methods of direct laser deposition 24CrNiMo alloy steel

The precise laser displacement sensor monitoring system during direct laser deposition process was established. The two-dimensional and three-dimensional topography images were acquired through data analysis and point cloud reconstruction method. The results of monitoring system show that with the increasing of scanning speed from 2 mm/s to 6 mm/s, the width of single track deposition kept stable due to the laser energy distribution, and the height of deposition decreased from 1.59 mm to 0.33 mm. The relationship between scanning speed and deposited 24CrNiMo alloy topography was established through data fitting. Deposition surface convex and concave defects can be distinguished through the feature of three dimensional images, uneven surface mainly existed in the deposition sides, which was represented by blank zone of acquired images. With the scanning speed increasing, the surface quality of deposited samples improved while the depositing efficiency decreased. The formation of surface defects is related to the solidification speed of molten pool, the phase structure of single track deposition was martensite owing to the high solidification speed, and the martensite has strain along the block boundary. The solidification rate increased with scanning speed increased, which led to the less time in forming surface defects.

Predicting outcomes following second intent healing of periocular surgical defects.

Traditionally, second intent healing (SIH) in the periocular region is reserved for small and/or concave defects, particularly those located on the medial canthus. The purpose of this study was to identify factors impacting outcomes of SIH for periocular tumors following Mohs micrographic surgery (MMS). Retrospective analysis was performed of all periocular lesions treated with MMS followed by SIH from a single academic surgical center over a 5-year period. Data regarding tumor characteristics and follow-up was recorded. The modified Manchester scale was utilized to evaluate scar outcomes. Of the 39 tumors included, 14 (35.9%) were located on the lower eyelid, 12 (30.8%) on the upper eyelid, 6 (15.4%) on the lateral canthus, and 7 (17.9%) on the medial canthus. Involvement of the eyelid margin was seen in 11 (28.2%) of cases. The average defect diameter and area were 1.3cm and 1.04cm-squared. Twenty-three cases (59.0%) healed with optimal results. Larger defects were significantly associated with poorer outcomes of SIH (odds ratio 0.205, p = 0.017 by multivariate analysis). Anatomic location, involvement of the lid margin, age, and follow-up interval were not significant factors; however, medial canthus defects were least likely to heal with optimal results. On average, medial canthal lesions were larger in size (mean diameter 1.76cm, mean area 1.97cm-squared). This retrospective study suggests that periorbital defects in all locations with area less than 1.04 cm2 heal well by SIH. In this cohort, larger lesions on the medial canthus healed with worse outcomes.

Cause Analysis of Flat Concave Defects on the Inner Surface at the end of T91 Alloy-Steel Tubes

The concave defects on the inner surface at the end of T91 alloy-steel tubes were analysed by macroscopic morphology analysis, electron microscope scanning and energy spectrum analysis, metallographic analysis and anion analysis of corrosion products. The composition of water sample and oil sample of finned winding and oil immersion treatment was also analysed. It was found that this kind of defect was not caused by the preservation environment of steel tube, the treatment of finned winding and oil immersion. The defect should be related to the quality of steel tube blank or the processing technology of steel tube.

FE analysis of extrusion defect and optimization of metal flow in porthole die for complex hollow aluminium profile

Abstract To solve the defects of bottom concave appearing in the extrusion experiments of complex hollow aluminium profiles, a 3D finite element model for simulating steady-state porthole die extrusion process was established based on HyperXtrude software using Arbitrary Lagrangian–Eulerian (ALE) algorithm. The velocity distribution on the cross-section of the extrudate at the die exit and pressure distribution at different heights in the welding chamber were quantitatively analyzed. To obtain an uniformity of metal flow velocity at the die exit, the porthole die structure was optimized by adding baffle plates. After optimization, maximum displacement in the Y direction at the bottom of profile decreases from 1.1 to 0.15 mm, and the concave defects are remarkably improved. The research method provides an effective guidance for improving extrusion defects and optimizing the metal flow of complex hollow aluminium profiles during porthole die extrusion.

Corrosion behaviors of 316LN stainless steel joints brazed with Sn-plated silver filler metals

AgCuZnSn filler metals were prepared from the BAg34CuZnSn filler metal by a combinative process of brush plating and thermal diffusion, and the prepared filler metals were applied to the induction brazing of the 316LN stainless steel. The corrosion behaviors of the brazed joints was evaluated based on local corrosion analyses, where the morphology of the joints was analyzed by scanning electron microscopy (SEM) after immersion in a 3.5 wt.% NaCl aqueous solution and electrolytic etching in a 10 vol.% oxalic acid solution. The microstructure of the brazed joints with the Sn-plated filler mainly consisted of the Ag phase, Cu phase, CuZn phase, Cu5Zn8 phase, Cu[Formula: see text]Sn[Formula: see text] phase and Ag3Sn phase. The local corrosion analysis results indicated that galvanic corrosion occurred near the interface between the stainless steel base metal and the brazing seam. With increasing local corrosion time, the corrosion rates of both the brazing seam and the base metal first exhibited an increasing trend, followed by a decreasing trend, and the corrosion rate of the brazing seam was slightly greater than that of the base metal. The corrosion behaviors analysis indicated that the corrosion resistance of the brazing seam was reduced, and concave defects emerged after electrolytic etching for 90 s.

鋼管表面の熱間における凹凸欠陥検出を目的とした「ツイン投光差分方式」の開発

鋼管表面の熱間における凹凸欠陥検出を目的とした「ツイン投光差分方式」の開発

Design and Testing of a Micro Thermal Sensor for Non-Contact Surface Defect Detection

This paper presents an experimental study on a new concept of a surface defect detection method, in which surface defects will be detected by monitoring a change in heat flow between a micro thermal sensor and a smoothly-finished measuring surface such as magnetic disks, sapphire substrates and so on. In the proposed method, the micro thermal sensor is designed to detect surface defects without any contacts in between them. Since the change in heat flow across the gap is utilized, the method is expected to find out both the convex and concave defects. Searching for the possibility of the non-contact surface defect detection by the micro thermal sensor, in this paper, a simple heat transfer model is established to estimate the change in heat flow due to the change in gap between the measuring surface and the sensor surface. Some basic experiments are also carried out by using prototype micro thermal sensors, each of which is composed of a pair of electrodes and a thin metal film resistor, fabricated on both the silicon and glass substrates.

Constructing an Atomic Layer Pt Electrocatalyst with a Concave Curved Surface for the Oxygen Reduction Reaction

AbstractOne of the strategic objectives in fuel cell technologies is to develop oxygen reduction reaction (ORR) catalysts with high activity, stability and, moreover, a low Pt loading. Computational results have indicated that surfaces or nanostructures with concave defects exhibit higher ORR activity than convex ones. Here, atomic layers of Pt were epitaxially coated on nanoporous gold (NPG) for the unique surface structure, both with convex or concave curvatures of the NPG. Outstanding ORR activities were revealed on Pt overlayers who copied the substrate's surface features. Furthermore, ascribed to the adverse impacts of tensile Pt lattice on gold, an optimized specific activity has been found as a function of the increasing Pt atomic layers. Pt coating with three atomic layers on NPG (NPG−Pt3) shows the best specific activity with an approximate 9‐fold improvement with respect to commercial Pt/C, as well as a 10‐fold enhancement in mass activity at 0.9 V versus a reversible hydrogen electrode.

Simultaneous Improvements in Performance and Durability of an Octahedral PtNix/C Electrocatalyst for Next-Generation Fuel Cells by Continuous, Compressive, and Concave Pt Skin Layers

Simultaneous improvements in oxygen reduction reaction (ORR) activity and long-term durability of Pt-based cathode catalysts are indispensable for the development of next-generation polymer electrolyte fuel cells but are still a major dilemma. We present a robust octahedral core–shell PtNix/C electrocatalyst with high ORR performance (mass activity and surface specific activity 6.8–16.9 and 20.3–24.0 times larger than those of Pt/C, respectively) and durability (negligible loss after 10000 accelerated durability test (ADT) cycles). The key factors of the robust octahedral nanostructure (core–shell Pt73Ni27/C) responsible for the remarkable activity and durability were found to be three continuous Pt skin layers with 2.0–3.6% compressive strain, concave facet arrangements (concave defects and high coordination), a symmetric Pt/Ni distribution, and a Pt67Ni33 intermetallic core, as found by STEM-EDS, in situ XAFS, XPS, etc. The robust core–shell Pt73Ni27/C was produced by the partial release of the stress, ...

The Effect of Surface Defect on EHL Point Contact

In this paper, the lubrication of three-dimensional EHL point contact with surface defect was solved, the lubrication film shape and film pressure distribution were presented and the characteristics of EHL point contact with defect were analyzed, the effect of surface defect on EHL point contact was studied. The results were presented that convex defect could lead to film pressure peak increasing, there was obvious micro-EHL effect, concave defect could lead to film pressure hollow and peak, film pressure peak was also increasing. The results also shown that convex and concave defects would have negative impact on EHL lubrication, there was great influence of surface defect on EHL lubrication pressure, the significant fluctuation of local film pressure was caused by surface defect, and generating greater pressure peak, maximum film pressure was rapid growth with the defect size increasing, so any kind defect should be to avoid in EHL lubrication.

High Frequency Guided Wave for Detection and Depth Sizing of Concave Defects on Internal Surface of Pipes

It is time-consuming to inspect long pipes in power generation facilities using conventional ultrasonic testing techniques because scanning is necessary. Ultrasonic guided waves potentially provide an attractive solution to this problem because they can propagate several meters once they are excited at one location on the structure. This paper addresses the propagation of high frequency guided wave in a plate and in a pipe, and its interaction with localized wall-thinning on internal surface due to corrosion or erosion. Guided waves were generated in a stainless steel plate and a carbon steel pipe with thickness of 10mm, respectively. The pipe whose diameter is 318 mm contains artificial concave defects with different sizes in order to simulate localized wall-thinning on internal surface. A 2D finite element model was used to simulate wave propagation within the plate, and the characteristics of guided waves were also studied using a 2 MHz conventional transducer. The high frequency guided waves were explored for their capability of detecting and sizing defects.

The Research of Chemical Plating of Pd/Sn on Graphite Anode Surface and its Electro-Catalytic Properties

The Pd/Sn catalytic coating on graphite electrode had been synthesized by chemical plating in this paper. Scanning electron microscope(SEM)and Electrochemical workstation(EW)were used to analyze the coating surface topography and electro-catalytic properties of modified graphite electrode with and without the coating. Results show that Pd and Sn are in the form of spherical particle and completely cover the surface of graphite electrode includes concave defects. Most Pd and Sn particles are dispersive ones of size of about 70 nm and few of which are polymerized in island forms. The peak value of current density increases with scanning speed, which goes positive potential scanning. Further more, the peak current increases with the concentration of NaOH solution, which shows nonlinear relationship between peak current and solution concentration, The peak current increases more rapidly with solution concentration increases in low NaOH concentration solution than that in high NaOH concentration solution.

Morphological control and cross-flow filtration of microfiltration membranes prepared via a sacrificial-layer approach

Abstract The main parameters in controlling the polysulfone (PSf) membrane morphology via a co-casting sacrificial approach were investigated. PEI/NMP and PSf/PVPK90/NMP were used as the coating and supporting solutions, respectively. The effect of PSf concentration, PVP concentration, PEI layer thickness and the coagulation bath temperature were studied. Scanning Electron Microscopy, pore size, porosity, pure water permeability and cross-flow filtration of suspension were utilized to characterize the membranes. Increase in PSf concentration efficiently avoided the concave defects in top surface with the penalty of significantly low permeability, small pore size and compact matrix structure. On increasing the PVP concentration from 0 wt.% to 10 wt.%, the membrane surface transformed from with a dense skin to a more open one. Further increase of PVP concentration to 20 wt.% led to a decline in the surface porosity. At higher coagulant temperature and thicker PEI coating, PSf membranes showed higher permeability and larger pore size. In cross-flow filtration of CaCO 3 suspensions, very high rejection rates were found for particles of 5.7 μm; a stable membrane permeability of 3000–6000 l m −2 h −1 bar −1 was obtained.

Detection of Small Convex and Concave Defects on Optical Films by Patterned Illumination (3rd Report)

This paper describes an optimum designing method of optical system for convex and concave defect detection, which uses patterned illumination. “Reaching Range of the Ray(RRR)”, which is calculated numerically based on the defect shape, is defined. RRR indicates width of effective area on the patterned illumination that contributes to observation of the defect. It is used as guidance for sensitivity of defect detection. Determination method of illumination pattern and optical alignment by using detection sensitivity based on RRR is shown. This paper also described an estimation method of observation images of defects and a selection method of defect detection algorithm for various shapes of defects.