Hasil untuk "Microscopy"

J. Miao, P. Charalambous, J. Kirz et al.

Tsuyoshi Shimaoka, Hazuki Maezono, Shunka Ono et al.

Abstract Oral biofilms contribute to apical periodontitis, a major cause of tooth loss. This study evaluated the potential of an on-demand aqueous chlorine dioxide solution, “matching transformation system” (MA-T), as a safer alternative to conventional root canal irrigants. The antibacterial activity of MA-T was assessed against mono-species biofilms (Enterococcus faecalis, Parvimonas micra, Fusobacterium nucleatum), polymicrobial biofilms derived from human supragingival plaque, and an in vitro infected root canal model using E. faecalis. Antibacterial efficacy was evaluated using viable cell counting and confocal laser scanning microscopy (CLSM) to quantify the reduction in bacterial load. Biofilm mass was assessed by crystal violet (CV) staining. Cytotoxicity was evaluated by treating rat osteoblasts and human periodontal ligament fibroblasts with MA-T or NaOCl, followed by assessment of ATP levels and morphological integrity. MA-T eradicated planktonic bacteria, inhibited biofilm formation, and significantly reduced viable bacteria in established biofilms without affecting the total amount of biofilm biomass time-dependently. The infected root canal model showed a substantial decrease in bacterial load. Compared with NaOCl, MA-T-treated cells retained higher ATP levels and normal morphology. MA-T could be a promising root canal irrigant offering effective disinfection and superior biocompatibility, making it a potential alternative to traditional root canal irrigants as NaOCl.

Manuel G. Pinedo-Cuba, José M. Caicedo-Roque, Jessica Padilla-Pantoja et al.

Magnetic shape memory alloys have attracted considerable attention due to their multifunctional properties. Among these materials, Ni-Mn-Ga alloys are distinguished by their ability to achieve up to 10% strain when exposed to a magnetic field, a characteristic predominantly observed in single-crystal samples. Consequently, it is essential to develop nanomaterials with a crystal structure closely resembling that of a single crystal. In this study, an epitaxial Ni-Mn-Ga thin film was fabricated using Pulsed Laser Deposition on an Al₂O₃ <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>(</mo><mn>11</mn><mover accent="true"><mn>2</mn><mo stretchy="false">¯</mo></mover><mn>0</mn><mo>)</mo></mrow></semantics></math></inline-formula> single-crystal substrate. The crystal structure was characterised through X-ray diffraction methodologies, such as symmetrical <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>2</mn><mi>θ</mi><mo>−</mo><mi>ω</mi></mrow></semantics></math></inline-formula> scans, pole figures, and reciprocal space maps. The results indicated that the sample was mainly in a slightly distorted cubic austenite phase, and some incipient martensite phase also appeared. A detailed microstructural analysis, performed by transmission electron microscopy, confirmed that certain regions of the sample exhibited an incipient transformation to the martensite phase. Regions closer to the substrate retained the austenite phase, suggesting that the constraint imposed by the substrate inhibits the phase transition. These results indicate that it is possible to grow high crystalline quality thin films of Ni-Mn-Ga by Pulsed Laser Deposition.

Seungsoo Lee, Dan Bee Lee, Hyun Jung Lee et al.

Primary localized amyloidosis confined to the urinary tract is uncommon and frequently misinterpreted due to clinical and radiologic overlap with more prevalent conditions. We describe a 69-year-old woman who experienced recurrent gross hematuria over 2 years and underwent initial transurethral resection based on a presumptive diagnosis of chronic cystitis. Subsequent evaluation revealed a left ureteral mass with hydronephrosis, raising concern for malignancy. Histopathologic examination of both bladder and ureteral specimens demonstrated amorphous eosinophilic deposits that stained positive with Congo red and showed apple-green birefringence under polarized microscopy. Immunofluorescence confirmed λ-light-chain predominance, establishing AL (amyloid light chain)-type amyloidosis without systemic involvement. The patient underwent complete endoscopic resection and remains asymptomatic during ongoing surveillance. This case highlights the diagnostic challenges posed by localized urinary amyloidosis and underscores the importance of histologic confirmation in atypical inflammatory lesions.

Houman Kholafazad, Mahdiyeh Pazhuhi, Mohammad Hasanzadeh et al.

Microneedles (MNs) have emerged as a cutting-edge sensing approach due to their enhanced surface area, improved sample penetration, localized detection, and potential for enhanced sensitivity. However, some MN manufacturing methods involve complex procedures, costly equipment, and non-biocompatible materials. Additionally, challenges in integrating MNs into existing technologies hinders their application in rapid and low-cost sensor technology. This study reports the development of innovative MNs fabricated using readily available cellulosic-based paper fibers, in which fibers from Whatman paper mixed with 1 % polyvinyl alcohol (PVA) were shaped using a polydimethylsiloxane (PDMS) mold. The MNs operate based on both physical penetration force and fluidic absorption via capillary action in the porous cellulosic matrix. The MNs exhibit low reagent and sample volume requirements along with flexibility and ease of penetration into samples, and filtration capabilities that allow efficient detection with minimal interference. The structure of MNs was investigated by field emission scanning electron microscopy (FE-SEM), revealing a conical shape with an average height of ∼750 µm and a diameter of ∼500 µm. The performance of the MN sensors was validated by colorimetric detection of heavy metals in fish, demonstrating linear ranges of 0.6 to 8 mg/L, 0.2 to 4 mg/L, and 0.3 to 6 mg/L for copper Cu(II), chromium Cr(VI), and nickel Ni(II), respectively. The colorimetric detection, combined with smartphone-based digital image analysis, exhibited lower limit of quantification (LLOQ) of 0.6, 0.2, and 0.3 mg/L for Cu(II), Cr(VI), and Ni(II), respectively, with no significant interference in the presence of potential interfering ions.

Lishuai Jiang, Ye Zhao, Xin He et al.

Conducting laboratory tests on natural rocks has significant value for the scientific and practical advancement of various types of rock engineering. The investigation of a rock-like materials that is similar in characteristics and structure to natural rock is key to the further advancement of laboratory rock experiments. The rapid development of sand powder 3D printing technology in recent years has provided a solution for fabricating rock-like materials. However, the low strength and elastic modulus of sand powder 3D-printed materials limit their application in simulating natural rocks. Therefore, this paper proposes a method to enhance the mechanical properties of sand powder 3D-printed materials utilizing glass fiber reinforcement by incorporating glass fiber into sand powder 3D-printed rock-like specimens. The mechanical properties and microstructural variations of the specimens with varying glass fiber contents are investigated utilizing mechanical testing, acoustic emission, scanning electron microscopy, etc. The results indicate that (1) it is feasible to utilize glass fiber to enhance the mechanical properties of sand powder 3D-printed materials; (2) The mechanical properties of sand powder 3D printing materials are significantly enhanced by the addition of glass fiber; and (3) the mechanisms controlling the reinforcement effect of glass fiber addition on sand powder 3D-printed specimens are determined by analyzing the microstructural characteristics of the specimens. This study improves the applicability of sand powder 3D-printed materials in simulating natural rock, thereby promoting the further application of 3D printing in the field of rock mechanics.

Tianzhen Liu, Wei Zhao, Yongtao Yao et al.

Triply periodic minimal surface (TPMS) structures with excellent properties of stable energy absorption, light weight, and high specific strength could potentially spark immense interest for novel and programmable functions by combining smart materials, e.g. shape memory polymers (SMPs). This work proposes TPMS lattices with hybrid configurations and materials that are composed of viscoelastic and shape-memory materials with the aim to bring temperature-dependent mechanical properties and additional dissipation mechanisms. Different configurations and diverse materials of polylactic acid (PLA), fiber-reinforced PLA, and polydimethylsiloxane (PDMS) are induced, generating five types of TPMS lattices, including (Schoen’s I-WP) IWP uniform lattice, IWP lattice with density gradient, hybrid configurations, hybrid materials, and filled PDMS, which are fabricated by 3D printing. The fracture morphologies and the distribution of carbon fibers are demonstrated via scanning electron microscopy with a focus on the influence of carbon fiber on shape-memory and mechanical properties. Shape recovery tests are conducted, which proves good shape memory properties and reusable capability of TPMS lattice. The combined methods of experiments and numerical simulation are adopted to evaluate mechanical properties, which presents multi-stage energy absorption ability and tunable vibration isolation performances associated with temperature and hybridization designs. This work can promote extensive research and provide substantial opportunities for TPMS lattices in the development of functional applications.

Houda Taher Elhmali, Cristina Serpa, Vesna Radojevic et al.

The microstructure–property relationship in poly(methyl methacrylate) PMMA composites is very important for understanding interface phenomena and the future prediction of properties that further help in designing improved materials. In this research, field emission scanning electron microscopy (FESEM) images of denture PMMA composites with SrTiO₃, MnO₂ and SrTiO₃/MnO₂ were used for fractal reconstructions of particle agglomerates in the polymer matrix. Fractal analysis represents a valuable mathematical tool for the characterization of the microstructure and finding correlation between microstructural features and mechanical properties. Utilizing the mathematical affine fractal regression model, the <i>Fractal Real Finder</i> software was employed to reconstruct agglomerate shapes and estimate the Hausdorff dimensions (HD). Controlled energy impact and tensile tests were used to evaluate the mechanical performance of PMMA-MnO₂, PMMA-SrTiO₃ and PMMA-SrTiO₃/MnO₂ composites. It was determined that PMMA-SrTiO₃/MnO₂ had the highest total absorbed energy value (E_tot), corresponding to the lowest HD value of 1.03637 calculated for SrTiO₃/MnO₂ agglomerates. On the other hand, the highest HD value of 1.21521 was calculated for MnO₂ agglomerates, while the PMMA-MnO₂ showed the lowest E_tot. The linear correlation between the total absorbed impact energy of composites and the HD of the corresponding agglomerates was determined, with an R² value of 0.99486, showing the potential use of this approach in the optimization of composite materials’ microstructure–property relationship.

Chun Xue, Tingzhuang Han, Bo Gao et al.

At present, there are few studies on the phase transition during the thermocompression plastic deformation of magnesium alloy. In this study, the evolution model of thermal compression plastic of AZ31 magnesium alloy was constructed by molecular dynamics, and the phase transition relationship between HCP and FCC at different thermal compression rates was studied. By combining GLEEBLE thermal compression experiment with transmission electron microscopy experiment, high-resolution transmission electron microscopy images were taken to analyze the transition rules between HCP and FCC during plastic deformation at different thermal compression rates, and the accuracy of molecular dynamics analysis was verified. It is found that the slip of Shockley's incomplete dislocation produces obvious HCP →FCC phase transition at low strain rate and base plane dislocation at high strain rate, which makes the amorphous phase transition of HCP→OTHER more obvious, which provides theoretical guidance for the formulation of forming mechanism and preparation process of magnesium alloy.

J. W. Edington

J. Slot, H. Geuze

Gold particles in colloidal solutions often vary considerably in size. The finest sols (diameter less than 15 nm), especially, are very heterogeneous, as is indicated by coefficients of variance (CV) of 25- 35%. We have complexed staphylococcal protein A with gold particles (PA/Au) and then fractionated the preparations by glycerol or sucrose gradient centrifugation into very homogeneous subfractions. In this way, PA/Au probes of almost any size between 4.5 and 15 nm could be prepared. The variation of the gold particles in these fractions resulted in CV's between 9 and 16%. The reactivity of the PA/Au complex was not affected by the gradient procedure, as was shown by single- and double-labeling immunocytochemistry of ultrathin cryosections of rat pancreatic tissue.

A. L. Weisenhorn, P. Hansma, T. Albrecht et al.

Tianlong Jiang, Guanghai Shi, Danning Ye et al.

The recently discovered Mida nephrite deposit, located in the East Kunlun Mountains, Qiemo County, Xinjiang, Northwest China, contains new types of white and greenish white nephrite formed by limestone replacement, which shows microstructures, macroscopic features and country rocks typologies that are quite different from those of the other deposits along the Kunlun–Altyn Tagh Mountains. The gemological and mineralogical characteristics of Mida nephrite are presented here. These nephrites show an ivory white color and a porcelain-like appearance, with semitranslucent-to-opaque transparency and a porcelain-to-greasy luster. Petrographic study, electron probe microanalysis (EPMA) data and scanning electron microscopy (SEM) images have indicated that the nephrite is composed of tremolite, accompanied by minor quartz, calcite and diopside. Tremolite aggregates have shown different textures, like flaky, granular, fibrous–felted, bundle, radial and metasomatic relict textures. Quartz has appeared in granular or disseminated form, dispersed in the tremolite matrix. Calcite has shown a metasomatic relict texture in the white nephrite samples. Diopside has shown euhedral grains, with some distributed with a certain geometric appearance. Based on our observations, it is suggested that the quartz in the nephrite originated from Si-rich hydrothermal fluids. We propose that the substantial size difference of mineral grains, together with uncompacted grains with inter-particle pores, are the main reasons for the internal reflection and refraction under transmitted light, which allow less transmitted light to pass through the nephrite body and generate the appearance of a semitranslucent-to-opaque transparency, ivory white color and porcelain luster. Our study has unveiled that the Mida nephrite is not typical of the two known types (D-type: dolomite-related; S-type: serpentinite-related) and is overlapped by quartz grains dispersed throughout the less compact tremolite matrix. These observations would help set it apart from the majority of nephrite jades found in the Kunlun Mountains region and provide valuable insights for enhancing comprehension of the diversity of the nephrite deposits.

E. Mohan, G. Anbuchezhiyan, R. Pugazhenthi et al.

Abstract The current investigation presents the wear-worn surface analysis of a silicon carbide-reinforced brass-based composite synthesized by stir casting. Wear behavior of the brass composite pin was analyzed by disc tribometer. Wear characterization studies and confirmation of elemental composition are investigated through scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) respectively. The worn surface of the synthesized brass composite was analyzed using atomic force microscopy (AFM). The aim of the investigation is to examine the surface morphology of the worn specimen. Based on the input constraints, the wear rate ranges from 0.0135 to 0.0893 mm3/min. The applied load is the predominant factor in the wear rate (83.75%). Sliding velocity has a minor effect on wear rate (1.06%). The improved surface roughness of 15.27 nm was produced on the worn surface. The novelty of the research work is to study the various surface parameters of the worn surface, such as roughness average, root mean square roughness, maximum height of the roughness, skewness, and kurtosis. These parameters were analyzed at different wear-worn surfaces of the synthesized brass composite. The wear-worn surface was deeply investigated and incorporated with SEM and AFM analysis.

Nancy Quaranta, Marta Caligaris, Miguel Unsen et al.

The present work studies the use of pistachio shells as a porosity-forming raw material in the manufacture of ceramic bricks. It focuses on the characteristics of the ceramic pieces obtained with different residual biomass contents (from 5 to 20% by volume). The specimens were shaped by uniaxial pressure of 25 MPa, and then were treated at 950°C for 3h. Based on the results obtained it is possible to conclude that the use of this residual biomass, as a pore former in the ceramic industry is feasible. The proportion of added biomass that generates the best characteristics and properties in the final product is 10%. Up to this percentage of aggregate, ceramic pieces with very good macroscopic and microscopic characteristics are obtained, with porosity and flexural strength values that meet market requirements for this type of product. Optical microscopy technique has been used to carry out a detailed analysis of the shape and size of the formed pores, which is a specific objective of this work. It has been observed that for contents of 5 and 10% biomass, the shape of pores is similar to the shape of the particles of added pistachio shells, while for higher contents (15 and 20%) it is different with elongated characteristics. In relation with the size of the pores, at lower contents is around 60% of the original particles size, and for the higher percentages of biomass, they are larger, indicating that agglomerates of particles are formed and when combusted, produce that porosity characteristics.

Suhas Kowshik, Manjunath Shettar, Nikhil Rangaswamy et al.

Automobile bodywork, wall insulation, bridges, and ship hulls, to name a few, are among the many applications for glass fiber-epoxy composites. To manufacture lightweight products for aforesaid applications, the properties of glass fiber-epoxy composites must be improved. The present work aims to fabricate and characterize nanoclay epoxy composites (NECs) and nanoclay glass fiber epoxy composites (NGFEC) by varying nanoclay weight percentages (i.e., 0, 2, and 4 wt.%). NECs are fabricated by a general-casting technique, and NGFECs are fabricated by hand layup technique. Flexural, impact, flammability, and water absorption tests are conducted to evaluate the properties of NECs and NGFECs in accordance with ASTM standards. The addition of nanoclay increases the flexural and impact strengths of NECs and NGFECs by 8 to 14% and 16 to 29%, respectively. Also, nanoclay additions decline the burning rate and water uptake (%) of NECs and NGFECs by 6 to 23% and 6 to 30%, respectively. The impact strength of pure epoxy, NECs, GFEC, and NGFEC is diminished by 7 to 25% at the end of 70 days of water absorption. Scanning electron microscopy images are employed to learn the causes of specimen failure under an impact load for as-made and water absorbed conditions. Crack deflection, pinning, and arresting, fiber pull-out, crazing and matrix rupturing, shear leaps are observed in the SEM images.

D. Agard

B. Hecht, H. Bielefeldt, Y. Inouye et al.

L. Loeber, O. Sutton, J. Morel et al.

Paula Ramos, Raquel Carvalho, Fernanda Rosa et al.

Some pouting caught off the Atlantic coast of Portugal are discarded as unmarketable due to a dark discolouration of the skin and muscle. This study investigates the cause of this condition, describes the new parasite species responsible, and highlights the importance of educating those in charge of premarket inspection of food fish in order to reduce likelihood that consumers will eat infected fish. Macroscopically, infected fish showed considerable heterogeneity in darkening of the skin and hypaxial and epaxial muscles. Microscopical observation revealed bipolar nematode eggs in varying stages of development arranged in a linear pattern along muscle fibers. Histopathology confirmed the presence of eggs of a nematode of the genus Huffmanela Moravec, 1987 as the cause of muscle darkening and established a relationship between infection intensity and consequent darkened appearance of the tissues. The eggs are oval or barrel-shaped, with a smooth surface and polar plugs at opposite ends. The thin outer vitelline membrane is smooth and lacks ornamentation. Under light microscopy, the main eggshell of older eggs exhibits the outermost delicate and smooth vitelline membrane, and a thicker layer, correspondent to chitinous and chondroitin proteoglycan layers. Scanning electron microscopy of eggs confirmed light microscopic studies, namely the presence of a smooth vitelline membrane surrounding the egg. Microscopic and ultrastructural characteristics of eggs, and a new host family in a new geographic area, all suggest that a new species, herein named Huffmanela lusitana sp. n. is involved. Keywords: Trisopterus luscus, Dark muscle, Huffmanela lusitana sp. n., Nematode, Portuguese coast, Marketed infected food-fish