White Layer Research Articles

Rolling Element Bearing Damage in the Presence of Applied Electric Current

Modern wind turbines and battery electric vehicles have bearings in close proximity to electrical generators, motors, and inverters. These systems have motivated new research focused on damage mechanisms associated with low- and high-level electric currents in rolling element bearings. This work presents a study on the influence of applied electric current and lubricant selection on bearing surface damage. Direct current was applied to a rotating tapered roller bearing with axial load and oil lubrication. Tests were conducted with various levels of applied current and two different oils (additized and non-additized). Micropitting, white etching cracking (WEC), and the formation of a surface white layer were investigated using both optical microscopy and scanning electron microscopy. Some of the tested bearings had black oxide surface treatment on their rollers and raceways. The black oxide was evaluated with regard to the prevention of the WEC damage mode. The occurrence of the described damage modes depended on the type of oil used and the application of electric current. Higher electric currents increased bearing surface damage in these tests.

Revisiting the microsurgical anatomy of the sagittal stratum and surgical implications: fiber microdissection and tractography study.

The term "sagittal stratum" was coined by Heinrich Sachs in 1892 to define a parasagittally oriented white matter layer at the temporo-occipital cortex. Although this term has been widely used for more than 100 years, the description, classification, borders, and involved fibers of the structure vary among authors and remain imprecise. Through fiber microdissection and tractography, the authors aimed to define the sagittal stratum and resolve the uncertainty by revealing the relationship of this structure to other cerebral white matter pathways and the orientation of fibers in it. Twenty postmortem human cerebral hemispheres were prepared according to Klingler's method. Fiber dissections were performed under a surgical microscope and with microsurgical techniques. The results of dissection at each step were photographed with 2D and 3D imaging techniques, and 3D photogrammetry techniques were used to create a 360° model. Diffusion tensor imaging and 7T high-resolution MRI were used to confirm the findings. This study revisited the 3D organization of white matter tracts in the sagittal stratum through fiber microdissection and tractography. The microneuroanatomical structure of the sagittal stratum and its special organization with fibers from all three fiber systems are demonstrated. The authors' findings revealed that the sagittal stratum has two layers consisting of four different fiber tracts. Its external layer consists of a long association fiber and a commissural fiber, while its internal layer consists of intertwined projection fibers, including temporo-parieto-occipitopontine fibers and the posterior thalamic peduncle. Detailed microdissection also showed the location of the posterior thalamic peduncle in the most medial site of all posterior hemispheric projection fibers. The structure of the sagittal stratum is distinctive in that it contains all three main fiber systems: association, commissural, and projection. Because of its expansive location in the temporal and occipital lobes, it can be damaged by most neurosurgical pathologies and procedures. The authors emphasize the significance of preserving the sagittal stratum during surgical interventions while also challenging the notion of a "silent" brain, suggesting that the current inability to fully comprehend cerebral function contributes to this misconception. Detailed knowledge of the complex white matter anatomy of the sagittal stratum can guide neurosurgeons in surgical planning and the selection of appropriate surgical approaches with intraoperative orientation for safe surgery and less comorbidity.

Analytical Study of Polychrome Clay Sculptures in the Five-Dragon Taoist Palace of Wudang, China

During the Ming Dynasty, the Five-Dragon Palace functioned as a royal Taoist temple set atop one of China’s holiest Taoist mountains, Wudang Mountain. Two tower polychrome sculptures with exquisite craftsmanship have remained over the centuries. In this study, the painting materials and the techniques used to construct these sculptures were analyzed through multiple characterization methods, including optical microscope (OM) observations, micro-Raman spectroscopy, scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM−EDS), X-ray diffraction (XRD), micro-Fourier-transform infrared spectroscopy (μ−FTIR), and pyrolysis–gas chromatography/mass spectrometry (Py−GC/MS). The results revealed that the pigments used in these sculptures included red pigments, which were composed of mercury (II) sulfide (cinnabar or vermillion), minium (Pb3O4), and hematite (Fe2O3); green pigments, which included atacamite and botallackite (Cu2Cl(OH)3), and blue pigments, which comprised smalt (CoO·nSiO2) and azurite (Cu3(CO3)2(OH)2). The white base layer was composed of quartz and mica minerals combined with gypsum or plant fiber, and the gold foil was adhered to the surface using heated tung oil. In addition, a special multi−layer technique was applied, with red under the golden gilding, white under the blue layer, and gray and black under the green layer. Drying oil was used as a binder for lead-containing pigments. This study offers substantial proof of reliable techniques to use in the continuing conservation of these sculptures, and it also serves as a foundation to determine if they can be dated to the late Ming or early Qing Dynasty (17th century).

In vivo 3-photon fluorescence microscopy of white matter in mouse brain excited at the 1700 nm window

White matter, a densely packed collection of myelinated axons, plays an essential part in neural networks. With high spatial resolution and deep penetration, multi-photon microscopy (MPM) is promising for white matter imaging in animal models in vivo. The third harmonic generation (THG) signal can be generated from white matter, but the bottom part of the white matter layer generates weak THG due to its high scattering. Here, we demonstrate an in vivo labeling and imaging technology, capable of visualizing the white matter layer in the mouse brain, combining fluorescence labeling with MitoTracker Red and three-photon fluorescence (3PF) microscopy excited at the 1700 nm window. 3PF signals are several times higher than THG signals, resulting in deeper imaging of the white matter layer with the former. Our results indicate that 3PF microscopy is a promising technology for white matter imaging in the deep brain in vivo.

Comparative performance evaluation and economic assessment between traditional and vibration assisted EDM during machining of Inconel 718

Nickel based superalloy, Inconel 718 offers extensive applications in aerospace and gas turbine industries because of its outstanding properties, enabling high performance in various critical components. Despite the wide application of electric discharge machining (EDM) for difficult-to-cut conductive materials, the process becomes less productive due to unstable arcing and inadequate debris flushing during machining, leading to reduced operational efficiency. This research focuses on comparative performance evaluation and economic assessment between conventional-EDM and vibration assisted EDM (VA-EDM) while machining Inconel 718 with copper electrode. The workpiece was excited to vibrate with low frequency by employing unbalanced mass attached in a rotary motor with the aim of enhancing EDM performance. Material removal rate MRR, surface integrity (surface crack density SCD, surface roughness Ra, white (recast) layer thickness WLT) and tool wear rate TWR are analyzed to determine machining performance in comprehensive analysis. The results of the performance comparison show that vibration assisted is superior to the conventional-EDM process concerning enhanced material removal rate, and surface morphology with minimum surface crack density, tool wear rate and white layer thickness. The mean value ratios for Ra EDM/ Ra VA-EDM, TWR EDM/ TWR VA-EDM, WLT EDM/ WLT VA-EDM, and SCD EDM/ SCD VA-EDM are 1.35, 1.52, 1.21, and 1.74, respectively. Additionally, the surface integrity was enhanced using vibration-assisted EDM because it (a) increases the plasma flushing efficiency and the gap pressure gradient; (b) raises the energy of electrically charged plasma particles; (c) increases the effective flow of dielectric in the gap; (d) minimizes the number of ineffective pulses (short-circuiting and arching) on the surface; and (e) improves the dielectric flushing conditions in sparking gap. According to the findings, the overall machining expenditure per part under VA-EDM in Indian rupees (INR) 534 is lowered by 8% than expenditure under conventional-EDM (INR 576.60). The outcomes of this research have the potential to benefit numerous industries that deal with difficult-to-cut materials.

Effect of carbon black from Ageratina adenophora and various other carbon anode plate additives on the performance of lead acid batteries

The incorporation of carbon materials in batteries serves to enhance its performance by improving conductivity, achieving uniform active material distribution, increasing capacity, mitigating sulfation, extending cycle life, and considering potential environmental benefits. Even though several possible mechanisms were reported, how exactly carbon works is not fully understood. In the present study a new form of carbon black was prepared from Ageratina adenophora (CBAa) and investigated for its impact on the electrical conductivity of the negative active material in 2 V lead acid cell. The performance was compared with other commercially available carbons like Graphite PG-10, Carbon N550, Carbon N330 and Carbon Vulcan. The carbon was characterised by XRD, SEM and grain size analysis. The initial capacity of the cell was consistently higher and remained stable at 4.6 W∙h; in the life cycle analysis, the cells showed 290 cycles. The post-life cycle test analysis showed that only a white layer on multiple plates indicating the onset of sulfation and there is no corrosion. The performance of the CBAa prepared in the present work was found to be better when compared with the commercially available carbons.

Evaluation of Cleaning Soiled Deposits and Crusts from Archaeological Glass Using Laser Treatment with Ag/Au Nanoparticles

The study aims to evaluate the effect of silver and gold nanoparticles during the laser cleaning process of glass artifacts. It is the first time that nanoparticles have been used to clean antique glass, as far as the authors are aware. In the context of this study, work was done on glass samples extracted from excavations that suffer from dense layers of corrosion products, soil deposits, brittle, easy to break, and cannot bear pressure. To characterize the investigated glass shards and assess the cleaning procedure, a variety of analytical techniques, including the transmission electron microscope (TEM), digital microscope, stereomicroscope, scanning electron microscope (SEM-EDX), X-ray diffraction (XRD), and color change measurement, have been used. The XRD analysis revealed different minerals such as ferrosilite, hillebrandite, and jacobsite, in the black corrosion layer, and calcite, syngenite, and arcanite in the white crust layer. The results of the microscopic examination employed in the evaluation procedure demonstrated that using Ag NPs with laser perfectly removed the tough crust layers without scratching the surface. The cleaned surface became smooth, homogenous and more transparent. The elemental analysis results by (SEM-EDX) revealed a significant reduction in the proportion elements of the (Al, Fe, p, and Mg) in the corrosion layer and their loss in the cleaned areas. Measurement of color change indicated that laser-treated glass samples with the addition of Ag NPs gave higher (ΔE*), confirming the influential role of this method in cleaning archaeological glass. It was also observed that the effect of Ag NPs with Laser assistance decreases the required time for the cleaning process. Thus the heat generated by the laser-treated was reduced, so the laser-treated with Ag NPs is recommended for use in the archaeological glass cleaning process.

Supplemental phosphorus can be completely replaced with microbial phytase in White Leghorn layer diets

ABSTRACT 1. A study was conducted to assess the possibility of totally replacing supplemental phosphorus sources in White Leghorn (WL) layer diets (aged 28 to 45 weeks of age) with microbial phytase supplementation. One thousand commercial layers (HyLine White) of 28 weeks of age were housed in California cages fitted in open-sided poultry shed at the rate of 20 layers in each replicate. Ten replicates were randomly allotted to each treatment, and the respective diet was fed from 28 to 45 weeks of age. 2. A control diet (CD) containing the recommended levels of non-phytate phosphorus (3.6 g/kg NPP) and four other test diets (2–5) having sub-optimal levels of NPP (2.4, 2.0, 1.6 and 1.2 g/kg), but with supplemental microbial phytase (600 FTU/kg) were prepared and fed for the trial duration. 3. The layers fed with lower levels of NPP with phytase had the same laying performance as the group fed the CD. Egg production, feed efficiency, egg mass, shell defects, egg density, shell weight, shell thickness, ash content and breaking strength of the tibia and sternum were not affected by feeding the lowest concentration of NPP (1.2 g/kg) plus microbial phytase. 4. Phytase supplementation in diets with sub-optimal levels of NPP (2.4, 2 and 1.6 g/kg) significantly improved the Haugh unit score compared to those fed the CD. 5. It was concluded that supplemental phosphorus can be completely replaced with microbial phytase (600 FTU/kg) in a diet without affecting egg production, shell quality or bone mineral variables in WL layers (28 to 45 weeks).

On the identification of the performance characteristics laws in EDM of biomedical Ti-6Al-4 V alloy with different tool electrode materials

The generation of performance characteristics laws may improve the reliability of EDM models, thus limiting experimentation and the resulting ecological effects and waste. In the present research, a finite element (FE) computational approach combined with experiment and regression analysis is employed to identify the laws relating power density and removal efficiency to the process settings in EDM of Ti-6Al-4 V alloy with various tool electrode materials. The experimental results for material removal rate (MRR), tool wear rate (TWR) and white layer thickness (WTL) are used as input data for the identification procedure. It was found that the performance characteristics are strongly affected by the machining parameters and tool-anode material. The power fraction going to the cathode varies between 7 and 30 % depending on the machining conditions and tool electrode materials studied. When employing a graphite electrode as opposed to copper or aluminum electrodes, the removal efficiency is maximized, at 51 %. Thus, the highest and lowest values of performance characteristics are obtained under the same processing conditions, irrespective of the tool material. The performance characteristics laws of the cathode are generated through a regression analysis. The established laws were validated by comparing the erosion ratio from the numerical simulation with the experiment. Qualitatively, the results of such a confrontation are deemed satisfactory. The established laws may be helpful in modeling the EDM process to predict the EDMed Ti-6Al-4 V surface integrity in the biomedical and aerospace sectors.

Research on the Symbolic Meaning of White Cranes — A Case Study of Fly with the Crane

Fly with the Crane is a feature film directed by Chinese filmmaker Li Ruijun in 2012, adapted from the short story of the same name by Su Tong. Set against a family backdrop, the film explores the emotional conflicts and collisions of life philosophies between the elderly and their family members when facing life and death decisions. Cranes play a significant symbolic role in the film, reflecting the characters’ inner emotions and their different understandings of life, death, and destiny. From the crane pattern on the coffin to the real white cranes in the film, and to the crane in the heart of the protagonist, five types of white cranes present different layers of symbolic meanings, enriching the depth and connotation of the film. At the same time, the film also reflects the current reality of scarce land resources, conflicts in resource allocation, and changes in people’s consciousness, indicating that the “crane culture” may gradually disappear.

Elaborate Report of Allium sativum Clove Brown Rot Caused by Fusarium solani in China.

In September 2023, brown rot disease was observed on cloves of garlic (Allium sativum) variety "Zipi-1" (purple skin) collected from Jinxiang County, China during scientific research at the Beijing Academy of Agricultural and Forestry Sciences after being planted in nutrient soil for approximately 2 weeks in a growth chamber maintaining 22℃, 60% relative humidity, and 16 hours of light. Out of the 90 garlic cloves investigated, 18 showed signs of decay, characterized by a brown color and rot, with the surface covered in blue and white mold layers. Six symptomatic cloves were collected for isolating the pathogen using the method described in a previous study (Wu et al. 2021). After 2 d of incubation, individual spores were harvested from the fungal colonies and recultured. Single-spore cultures growing on PDA medium appeared white and flocculent when viewed from the top, and yellowish-brown when viewed from the bottom. After 5 d of cultivation, the colonies had a diameter of approximately 5.8 cm and microscopic examination revealed that the mycelium had a diameter of about 9-13 µm (Fig. S1a, b and c). Isolate As1 produced three types of spores: oval-shaped chlamydospores with a diameter of approximately 6 µm, while spindle-shaped microconidia and sickle-shaped macroconidia measuring approximately 6-7 × 20-30 µm and 8 × 50 µm, respectively (Fig. S1d and e). The mycelial characteristics and reproductive structures of the isolates fit the morphological description of Fusarium solani (Xie et al. 2022). To confirm the identification, TEF1, RPB1 and RPB2 regions of the genome were amplified from three separate isolates (As1, As2, and As3) using EF1/EF2, RPB1-Fa/G2R, RPB2-5F2/7cR, and RPB2-7cF/11aR primer pairs (O'Donnell et al. 2022). The results indicated that the sequences of the three isolates were completely identical. Furthermore, the BLASTn comparison results of the TEF1 (OR916018, 710bp, 100%), RPB1 (OR916019, 1797bp, 99.8%), and RPB2 (OR916020, 1874bp, 100%) sequences in the FUSARIUM-ID v.3.0 database revealed that As1 was identified as F. solani species complex 5 (O'Donnell et al. 2022). To assess the pathogenicity of As1, the surface of healthy garlic cloves (n = 30) was spread with 106 microconidia/mL As1 suspension, while a control group (n = 30) was inoculated with sterile water. All inoculated cloves were placed in an artificial climate chamber under same conditions described above. After 10 d, all inoculated cloves exhibited rot symptoms consistent with those of the initially infected cloves identified in September 2023, while the control plant cloves remained asymptomatic (Fig. S2). Based on morphological and molecular characters (TEF1, RPB1, and RPB2), the reisolated pathogen from diseased plants was identical to the As1 isolate used for inoculation, and the disease assays were repeated twice. Fusarium spp. has been reported as the causal agent of garlic rot disease in several countries such as Mexico, America, and Russia (Gálvez and Palmero 2022). Tai (1979) previously published a report on the presence of F. solani in garlic; however, the content in the book is rather basic, lacking detailed information on the isolation, identification, and the potential for causing garlic diseases, whether postharvest or during growth. Our research can be considered a supplement and improvement to the study by Tai (1979) and lays the groundwork for future studies on management strategies to combat plant diseases caused by F. solani.

A two-step Bayesian network approach to identify key SNPs associated to multiple phenotypic traits in four purebred laying hen lines.

When purebred laying hen chicks hatch, they remain at a rearing farm until approximately 17 weeks of age, after which they are transferred to a laying farm. Chicks or pullets are removed from the flocks during these 17 weeks if they display any rearing abnormality. The aim of this study was to investigate associations between single nucleotide polymorphisms (SNPs) and rearing success of 4 purebred White Leghorns layer lines by implementing a Bayesian network approach. Phenotypic traits and SNPs of four purebred genetic White Leghorn layer lines were available for 23,000 rearing batches obtained between 2010 and 2020. Associations between incubation traits (clutch size, embryo mortality), rearing traits (genetic line, first week mortality, rearing abnormalities, natural death, rearing success, pullet flock age, and season) and SNPs were analyzed, using a two-step Bayesian Network (BN) approach. Furthermore, the SNPs were connected to their corresponding genes, which were further explored in bioinformatics databases. BN analysis revealed a total of 28 SNPs associated with some of the traits: ten SNPs were associated with clutch size, another 10 with rearing abnormalities, a single SNP with natural death, and seven SNPs with first week mortality. Exploration via bioinformatics databases showed that one of the SNPs (ENAH) had a protein predicted network composed of 11 other proteins. The major hub of this SNP was CDC42 protein, which has a role in egg production and reproduction. The results highlight the power of BNs in knowledge discovery and how their application in complex biological systems can help getting a deeper understanding of functionality underlying genetic variation of rearing success in laying hens. Improved welfare and production might result from the identified SNPs. Selecting for these SNPs through breeding could reduce stress and increase livability during rearing.

Study of Wear Resistance of Cylindrical Parts by Electromechanical Surface Hardening

The work scientifically substantiates the use of an effective technology for increasing the wear resistance of cylindrical parts, using the example of protective sleeves of cantilever pumps, due to electromechanical surface hardening. A review of research was carried out and it was established that the achievement of the highest values of microhardness of the surface layer at a depth of up to 1.2 mm is possible during electromechanical processing of protective sleeves of cantilever pumps. The application of various modes and schemes of electromechanical surface hardening (EMSH) is accompanied by a change in structure and, as a result, an increase in the hardness of the surface layer of the bushings. The actual contact area of the tool roller with the processed surface and the depth of the temperature-deformation effect depend on the physical and mechanical properties of the materials and the pressing force. The formation of a temperature gradient in the hardened zone at a depth of up to 1.2 mm from the surface has been proven. Metallographic analysis of the surfaces of the sleeves treated by EMSH shows the formation of a white layer with reduced etchability and increased hardness in the hardening zones. The results of the X-ray structural analysis confirmed the formation of the martensite phase in the hardening zone. The microhardness of the hardened steel zone increased by 2.6...3.6 times compared to the initial values at a depth of up to 1 mm from the surface, depending on the materials. In the case of their overlap, the alternation of a fully hardened zone, a partially hardened zone, and a self-relief zone is observed. At the same time, the microhardness of steels along the surface depends on the hardening scheme.
 Wear tests under friction conditions of parts of cantilever pumps paired with stuffing boxes showed that the wear resistance of protective sleeves after EMSH increased by 3.1 times for 45 steel, 1.9 times for U8 steel, 2.5 times for SHKH15 steel, for cast iron by 1.9 times compared to the initial values. The use of U8 steel samples after EMSH, instead of serial bushings made of steel 45, allows to increase the wear resistance of parts by 6.1 times, which allows us to recommend U8 steel for use in the manufacture of protective bushings for console pumps. On the basis of the research, recommendations are given for the application of EMSH for the formation of a surface layer with increased wear resistance of protective sleeves during their production and during repair of console pumps in workshops or service centers of agribusiness companies.

Microstructural study of the Praid Salt Diapir (Transylvanian basin, Romania) and its implication on deformation history and hydrogen storage potential

The Transylvanian basin is one of the major Tertiary sedimentary basins in the Carpathian-Pannonian region. Its thick sedimentary fill contains prominent Middle Miocene age salt that forms major diapir structures at the basin margins. The microstructural characteristics of the rock salt represent one of the main factors that determines the potential of a salt body for storage of hydrogen. The main aim of this study is to extend our understanding of the deformation mechanism of Praid rock salt located at the eastern margin of the Transylvanian basin. Based on petrography, we identified two types of rock salt: (1) layered salt with rather uniform grain size distribution showing alternation of greyish (clay mineral bearing) and white (clear halite) layers, and (2) massive grey salt with large, elongated halite crystals, accompanied by sub-micrometer size grains of halite. To shed light on the microstructure of the rock salt, we performed electron backscatter diffraction (EBSD) mapping, and studied gamma-irradiated samples both in the massive and layered salt samples. Dislocation creep and pressure solution creep were identified which acted concurrently in the Praid rock salt. The total strain rate falls between 1.2 and 1.3×10−10 s−1. The results of this study reveal a complex deformation history of the salt body where coexisting and migrating fluids have played an important role. The outcome of this project contributes to the hydrogen storage potential assessment for the Transylvanian salt and to a better understanding of the structural evolution of the Transylvanian basin.

Исследование электроэрозионной обработки криогенно обработанных бериллиево-медных сплавов (BeCu)

Introduction. In modern manufacturing world, industries should adapt technological advancements for precision machining of difficult-to-machine metals, especially for beryllium copper (BeCu) alloys. The electrical discharge machining of alloys has proven its viability. The purpose of the work. A literature review indicated that the investigation of electrical discharge machining of BeCu alloys is still in its infancy. Furthermore, the cryogenic treatment of workpieces and electrodes in electrical discharge machining has not received much attention from researchers. Moreover, the impact of magnetic field strength on surface integrity and productivity during electrical discharge machining has not attracted much attention from researchers. The methods of investigation. This paper describes the use of electrolytic copper with different gap current values, pulse on periods, and external magnetic strength for electrical discharge machining of BeCu alloys. This paper examines how the material removal rate, the thickness of the white layer, and the formation of surface cracks are affected by cryogenic treatment of the workpiece and tool, pulse-on time, gap current, and magnetic strength. Results and Discussion. The combination of the cryogenically treated BeCu workpiece and the untreated Cu electrode had the highest material removal rate among all the combinations of workpieces and tools used in this study. The pulse on-time and the strength of the magnetic field had little influence on material removal rate, whereas the gap current had the greatest effect. The maximum achieved material removal rate was 11.807 mm3/min. At a high material removal rate, the observed thickness of the white layer on the horizontal surface ranged from 12.92 µm to 14.24 µm. In the same way, the maximum and minimum values for the vertical surface were determined to be 15.58 µm and 11.67 µm, respectively. According to scanning electron microscopy, the layer thickness was less than 20 µm, and barely noticeable surface cracks were observed in specimens with low, medium and high material removal rates. Obviously, due to the cryogenic processing of the workpiece and the external magnetic strength, there was a slight cracking of the surface and the formation of a white layer.

Feasibility Tests of a Fish Farm Integrating the Breeding of Poultry and a Fly

A locally improvised poultry house built with pure local material called bamboo and covered with dried treated grasses (roof) known as sana which housed 300 laying birds was built near 20m X 20m earthen fish pond with an underground spring water as source of intake with a flow through system and stocked with an improved catfish clarias geripinus juveniles 2000 in number. The floor of the poultry house was cemented to prevent leakages of water and permanently coveted with thick nylon white rubber and layer were placed at high level above the floor on top of bamboo tree having gaps in between them. The usage of these gaps created was to allow layers (chicken) dropping directly on the rubber which eventually served as breeding places for maggot. The maggot was collected washed thoroughly and processed to serve as feed to the fishes. The processed maggot reduces about 40% of total cost of feed in raising the fishes. The birds produced 70piecers of eggs per day 7½ crates and a crate is sold for N2,700 per crate. The fishes were harvested after six (6) months of stocking with a total piece of 1,680 with an average of 800g (1344kg) and is sold at N1500 per kg. The revenue realized took care of both capital and recurrent cost with a working force of three (3) people. The experiment contribute significantly (P<0.05) in reducing the level of poverty and also contribute to food security, transformation agenda of Federal government of Nigeria.

Microstructure gradients across the white etching and transition layers of a heavy haul pearlitic steel

This study delves into the frequent surface cracking observed in severely damaged pearlitic carbon steel rails, a phenomenon often attributed to the challenging characteristics of the white etching layer (WEL) formed during railway operations. To explore this issue, a severely damaged rail cross-section featuring a substantial WEL layer measuring 600 μm in depth was analyzed. The WEL's size was initially determined through optical microscopy and characterized via nano-hardness testing, which revealed an impressive hardness of up to 12 GPa. High-energy synchrotron X-ray diffraction (HESXRD) analysis was employed to uncover the crystalline structure diversity gradient that resulted from railway use. The results unveiled that cumulative high-temperature surface damage leads to the formation of both the WEL and a transitional layer. Within this transitional layer, a gradual reduction in retained austenite is observed, coupled with an increase in the presence of cementite and ferrite as one approaches the base metal. Remarkably, very shallow depths from the surface display tempered martensite characteristics, characterized by high nanohardness, lower dislocation density, and an initially smaller, then increasing austenite fraction. The use of site-resolved synchrotron radiation diffraction at different depths from the surface to the interior of the damaged rail cross-section allowed a unique insight into the phase transformations, microstrain developments, and compositional evolution.

Full-angle chip scale package of mini LEDs with a V-shape packaging structure.

The light distribution of light-emitting diodes (LEDs) generally resembles that of a Lambertian light source. When used as large-area light sources, the light distribution angle of LEDs must be modified through secondary optics design to achieve uniformity and minimize the number of light sources. However, secondary optical components pose several challenges such as demanding alignment accuracy, material aging, detachment, and lower reliability. Therefore, this paper proposes a primary optical design approach to achieve full-angle emission in LEDs without the need for lenses. The design employs a flip-chip as the light source and incorporates a V-shaped packaged structure, including a white wall layer, optical structure layers, and a V-shaped diffuse structure. With this design, the LEDs achieve full-angle emission without relying on lenses. Our experimental results demonstrated a peak intensity angle of 77.7°, a 20.3% decrease in the intensity of the central point ratio, and a full width at half maximum (FWHM) of the light distribution of 175.5°. This design is particularly suitable for thin, large-area, and flexible backlight light sources. Moreover, the absence of secondary optical components allows for a thinner light source module.

Endothelialization of PTFE-covered stents for aneurysms and arteriovenous fistulas created in canine carotid arteries

To investigate the endothelialization of covered and bare stents deployed in the canine carotid arteries and subclavian arteries for treating experimental aneurysms and arteriovenous fistulas, twenty aneurysms were created in 10 dogs, and 20 fistulas in another 10 dogs. The Willis balloon-expandable covered stent and a self-expandable covered stent were used to treat these lesions, and a self-expandable bare stent was deployed in the subclavian artery for comparison. Followed up for up to 12 months, the gross observation, pathological staining, and scanning electronic microscopic data were analyzed. Two weeks after creation of animal model, thirty self-expandable covered stents and ten balloon-expandable covered stents were deployed. Fifteen bare stents were deployed within the left subclavian arteries. Twenty days after stenting, the aneurysm significantly shrank. At 6 months, the thrombi within the aneurysm cavity were organized. Three to 12 months later, most covered and bare stents were covered by a thin transparent or white layer of endothelial intima. Layers of intima or pseudomembrane were formed on the stent 20–40 days after stent deployment. Over three months, the pseudomembrane became organized, thinner, and merged into the vascular wall. Under scanning electronic microscopy, the surface of covered and bare stents had only deposition of collagen fibers and rare endothelial cells 20–40 days after stenting. From three to ten months, the endothelial cells on the internal surface of stent became mature, with spindle, stripe-like or quasi round morphology along the blood flow direction. Over time, the endothelial cells became mature. In conclusion, three months after deployment in canines’ arteries, the self-expandable bare and covered stents have mostly been covered by endothelial cells which become maturer over time, whereas the balloon-expandable covered stents do not have complete coverage of endothelial cells at three months, especially for protruding stent struts and areas. Over time, the endothelialization will become mature.

Comparison of Viability of the Preserved Autologous Aspirated Fat Tissue Transfer in Refrigerated and Frozen Specimens.

Fat graft surgery is one of the most effective procedures in plastic surgery, and since some patients request multiple surgeries and these cases sometimes take hours, it endangers the viability of the fat graft. In this study, we intend to evaluate the viability of adipose tissue aspirated with a syringe at refrigerator (4°C) and freezer (-20 °C) temperatures. This was a cross-sectional study. After receiving the ethics committee's approval (IR.MUMS.MEDICAL.REC.1401.423), 17 volunteers entered the study. The harvested fat tissue sample was divided into 3 parts, and each of them was transferred to 3 separate sterile tubes. The first tube was sent to the laboratory for preliminary examination of fresh fat, and the second tube was transferred to a 4°C refrigerator for 72 hours. The sample from the third tube was first passed through a strainer and after drying, it was transferred to a -20°C freezer for 72 hours. After treatment with trypsin, we placed the sample inside the centrifuge using the Coleman method. Finally, 3 layers were formed, and the white middle layer was extracted as a fat cell suspension. Tissue samples were stained with trypan blue, and the percentage of viable cells was calculated using an optical microscope. There was a significant difference between the mean number and percentage of viable cells in all 3 groups. Samples in the 4°C refrigerator had significantly more cellular viability than those in the -20°C freezer (mean difference, 72.842%; P < 0.001). Our findings showed that after 72 hours at 4°C, adipose tissue has significantly higher survival than at -20°C (98.93% vs 75.31%). Since the survival of fat cells is one of the direct determinants of fat retention, it can affect the results after surgery. The present study recommends fresh adipose tissue for immediate transplantation unless there is an urgent need for cold storage.