Homogeneous Distribution Research Articles

Silk fibroin nanoparticles for locoregional cancer therapy: Preliminary biodistribution in a murine model and microfluidic GMP-like production

Silk fibroin nanoparticles (SFNs) have been widely investigated for drug delivery, but their clinical application still faces technical (large-scale and GMP-compliant manufacturing), economic (cost-effectiveness in comparison to other polymer-based nanoparticles), and biological (biodistribution assessments) challenges. To address biodistribution challenge, we provide a straightforward desolvation method (in acetone) to produce homogeneous SFNs incorporating increasing amounts of Fe2O3 (SFNs-Fe), detectable by Magnetic Resonance Imaging (MRI), and loaded with curcumin as a model lipophilic drug. SFNs-Fe were characterized by a homogeneous distribution of the combined materials and showed an actual Fe2O3 loading close to the theoretical one. The amount of Fe2O3 incorporated affected the physical-chemical properties of SFNs-Fe, such as polymer matrix compactness, mean diameter and drug release mechanism. All formulations were cytocompatible; curcumin encapsulation mitigated its cytotoxicity, and iron oxide incorporation did not impact cell metabolic activity but affected cellular uptake in vitro. SFNs-Fe proved optimal for biodistribution studies, as MRI showed significant nanoparticle retention at the administration site, supporting their potential for locoregional cancer therapy. Finally, technical and economic challenges in SFN production were overcome using a GMP-compliant microfluidic scalable technology, which optimized preparation to produce smaller particle sizes compared to manual methods and reduced acetone usage, thus offering environmental and economic benefits. Moreover, enabling large-scale production of GMP-like SFNs, this represents a considerable step forward for their application in the clinic.

Silver doping effect on the electrochromic performance of the WO3 thin films produced by thermal evaporation in vacuum

Ag doped WO3 thin films are successfully fabricated by thermal evaporation method in vacuum as precursor, and then annealed at 450 °C in nitrogen gases atmosphere. Cyclic voltammetry, repeating chronoamperometry, chronocolumetry and optical transmittance are recorded in 1 M LiClO4/propylene carbonate electrolyte. The color of the WO3 thin films changes from transparent to the blue under the applied potential of -1.8 and +1.9 V. XRD studies show that all the films have a polycrystalline structure of WO3. The molecular formation is also confirmed by Raman and X-Ray photoelectron spectroscopy (XPS). The EDS elemental mappings clearly confirm the homogeneous distribution of Ag, W and O elements into the WO3 network. From the optical studies, indirect band gap energy of the WO3 decreases as Ag doping level increases. The best coloration and bleaching times (2.33 and 1.25 s) are obtained for the Ag(2%):WO3 thin films, compared to the pure WO3 (3.79 and 1.96 s). The produced WO3 films exhibit high reversibility (39.6/69.1%), high coloration efficiency values (26.3/141.2 cm2/C), and good cycling stability. From the EIS measurements, the charge-transfer resistance is Ag(2%):WO3 < the pure WO3 < Ag(5%):WO3 < Ag(8%):WO3, which means that Ag(2%):WO3 has the biggest electrochemically active surface area. Electronic energy levels of the pure WO3 and the Ag:WO3 thin films are also given. From the Mott-Schottky studies, it is determined that the donor concentration of the materials is of the order of 1014-1015 cm−3. In the literature, there are very limited studies related to electrochromic thin films by thermal evaporation in vacuum. In this sense, the reported results in this study are promising for the electrochromic applications.

Structural and optical properties of Eu-doped ZnO epitaxial thin films grown by pulsed-laser deposition

Pulsed-laser deposition was utilized to fabricate Eu-doped ZnO epitaxial films on c-plane sapphire substrates with Eu concentrations ranging from 0.5 to 4.0 at. %. The structural properties were analyzed using x-ray diffraction surface normal radial scans and azimuthal cone scans, which confirmed the epitaxy of the film samples. Reciprocal space mapping was performed on ZnO(101̄1) to visualize the effect of Eu incorporation. X-ray fluorescence mapping confirmed the homogeneous distribution of Zn and Eu, and x-ray absorption near-edge structure spectra directly confirmed the trivalent state of Eu ions. The optical properties were assessed using temperature-dependent photoluminescence (PL). Various defects were identified. With increasing Eu dopant concentration, PL emissions from defects and the Eu 4f-intraband transitions gradually became the predominant features in the PL spectra at low temperatures. Furthermore, PL analysis suggested that Eu ions substituted Zn, occupying sites with lower C3v symmetry due to the distortion caused by Eu incorporation.

Synergic effect of nano sized ceramic powder of titanium dioxide and silver on AZ91D composites fabricated by friction stir processing

This study aims to observe the synergic effects of AgNPs/TiO2 on AZ91D hybrid composite fabricated via friction stir process. Nano-sized particles of titanium-di-oxide (TiO2) and silver (AgNPs) in powder form were utilized as reinforcement materials for fabricating mono and hybrid composites. The average size of the reinforcements was 80 nm. Friction stir processing (FSP) technique was done at constant parametric settings. Investigating the microstructure of the composites by optical microscope(OM) analysis showed a homogenous distribution of the incorporated particles in the AZ91D matrix. Scanning electron microscopy (SEM) analysis was done for fractography, which indicates ductile facture in all the specimens despite having any composition of reinforcements. However, rate of ductile fracture decreased with weight fraction of TiO2. Tensile strength and Micro-hardness measurements revealed enhancement in tensile properties i.e. ultimate tensile strength (UTS), yield strength(YS), percentage elongation(EL) and microhardness in all samples. The contribution of various strengthening mechanisms, i.e. Hall-patch, Orowan strengthening and thermal mismatch, were calculated for all samples and compared with actual values. Among strengthening mechanisms, Orowan strengthening is the most dominant. The modified Clyne method estimates the collective effect of various strengthening mechanisms to evaluate the theoretical YS for all samples. The maximum value of Yield strength (YS) is 175.612 MPa obtained for T-50-A-50. The maximum value for microhardness is obtained as 140.08 HV on Vickers scale for T-100-A-0 attributed to uniform dispersion of hard ceramic (TiO2) particles.

L12 strengthening of WC-CoNiFe cemented carbides by spark plasma sintering

Binder phase has very significant effect on the growth of WC grains, grain morphology, the microstructure and properties of cemented carbide. In this paper, Co, Fe and Ni were used as binder phase, cemented carbides with different sintering temperatures were prepared by spark plasma sintering. The differences in the microstructure and properties of 10Co and 8Co-3NiFe were analyzed. The results showed that the 8Co-3NiFe cemented carbide generated the highly ordered FeNi3 phase with FCC of L12. The addition of Fe and Ni decreases the melting point of 8Co-3NiFe, makes the grain morphology of WC more rounded and more homogeneous distribution of the cemented carbide microstructure. The WC grain sizes of the 10Co and 8Co-3NiFe cemented carbides are very similar, but the 8Co-3NiFe cemented carbide shows a slight increase in grain size. Low-temperature densification of the 8Co-3NiFe cemented carbide can be achieved at sintering temperature of 1050°C. The fracture toughness of the 8Co-3NiFe cemented carbide improves by about 10% compared to the 10Co cemented carbide.

Single layered Ag/NiO plasmonic nanocoatings: A new green synthesis method for selective solar absorber

This study presents the synthesis of environmentally benign, single-layered spectrally selective Ag/NiO nanocoating absorbers using a green synthesis method. Various characterization techniques, including Rutherford backscattering spectroscopy (RBS), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM), were used to examine the effects of plasmonic Ag concentration on the structural, chemical composition, and surface morphology of the nanocomposites. The optical properties of the deposited nanocoatings were investigated using a UV–Vis-NIR spectrophotometer in the solar spectrum region (300–2500 nm) and an FT-IR spectrophotometer in the infrared wavelength region (3000–20,000 nm). XRD results confirmed the coexistence of a face-centered cubic phase of Ag and NiO in the Ag/NiO nanocermet thin films. SEM and TEM topography revealed uniformly distributed nanosphere NiO thin films and cubic Ag metal with better dispersibility and crystallization. The RBS spectrum of the samples showed a homogeneous distribution of Ni, Ag, and O atoms throughout the coatings. Ag/NiO nanocoatings deposited with 8 wt% Ag content exhibited excellent solar absorptance (α) = 0.95 and thermal emittance of (ɛ) of 0.08. This enhancement is primarily attributed to the localized surface plasmon resonance (LSPR) effect associated with the embedded Ag nanoparticles, which facilitates more effective utilization of light.

The effect of cryogenic treatment on a high Co bearing DIN 1.2888 steel used as die in hot forging process

Abstract Hot work steels used as dies in metal forming processes must endure harsh conditions, typically achieved through a martensitic structure. However, retained austenite can persist after martensitic transformation, negatively impacting mechanical properties. Cryogenic treatment (CT) refines martensite, reduces retained austenite, and increases fine carbide density, thus enhancing performance. DIN 1.2888, a hot work tool steel with high cobalt content (~10%) and low carbon content (~0.2%), is less studied concerning the effects of CT. The objective of this study was to investigate how cryogenic treatment affects the mechanical and microstructural properties of DIN 1.2888 steel. Samples underwent conventional heat treatment (HT) and CT at -100, -140, and -180°C for 6 hours, followed by double tempering. Various analytical methods, including X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), and Vickers Microhardness tests, were used to examine the samples. Wear mechanisms were evaluated through pin-on-disc tests under different loads, and impact toughness was measured both at room temperature and the working temperature of dies (350°C). Results indicated that lowering the cryogenic treatment temperature resulted in a slight increase in hardness values from 507HV for the heat-treated sample to 529HV for the sample treated at -180°C. Additionally, the impact toughness improved significantly, with values rising from 12.35J for the heat-treated sample to 23.44J at 350°C for the cryogenically treated sample at -180°C. Wear rates also decreased by approximately 50%, particularly at higher cryogenic treatment temperatures. The improvement in wear resistance was attributed to finer carbide precipitation and a more homogeneous distribution of carbides. These findings suggest that deep cryogenic treatment has a positive effect on DIN 1.2888 steel by decreasing retained austenite and increasing fine carbide density, leading to enhanced mechanical properties and extending the lifespan of the steel in die applications.

Effect of grain size and orientation on magnetron sputtering yield of tantalum

The electron beam melting (EBM) technique was employed to prepare ultra-highly pure (99.999 wt%) Tantalum (Ta) cast ingot for application in chips. Subsequently, the Ta cast ingot were forged, rolled, and annealed with different durations to gain three different grain sizes (centimeter scale, 99.8 μm, and 36.7 μm). Sputtering experiments conducted under identical conditions revealed that the rolled target (36.7 μm) film deposition rate was increased by 60.6 % compared to the cast ingot target with a centimeter-scale grain size (columnar crystal). Ta targets with a fine grain size and homogeneous distribution demonstrate superior film deposition performance. The sputtering rate is directly related to the atomic packing density of grains. The (111)-oriented grains of BCC targets (Ta target) exhibit sputtering resistance, and the order of sputtering rate of Ta atoms was S(101) > S(001) > S(111).

The Influence of Video Editing Applications in Improving Student Learning Achievement in Fiqh Subjects at MTS MTI Pariangan

This research aims to determine how video editing applications improve learning achievement in Fiqh subjects at MTs MTI Pariangan. This type of research is quantitative and uses experimental methods. The population in this study were all class VIII students. Meanwhile, the sample for this research consisted of 46 students, namely class VIII. 1 (as the control class) and class VIII. 2 (as the experimental class). The sampling technique uses cluster random sampling. The results of this study show that the average score between the experimental and control classes is different. Namely, the experimental class is 92.3, and the control class is 69.42. Therefore, it can be seen that the experimental class score is higher than the score of the control class students, and after testing, The prerequisite for normality and homogeneity is that the two samples are declared to have a standard or homogeneous distribution so that research can be carried out in the control class and experimental class. Learning using learning videos edited through video editing applications on prostration of gratitude, prostration of recitations and prostration of sahwi is significantly superior to learning using conventional models. Therefore, video editing applications influence improving student learning achievement.

Macroscopic observation of a first order one-dimensional swelling-deswelling transition in a nanolayered material

AbstractThe high purity and superior quality of the synthetic clay mineral fluorohectorite allows for studies of phenomena that are masked by imperfections and the inhomogeneous charge distribution in the case of natural clay minerals. We have exploited this opportunity offered by synthetic fluorohectorite and report here digital optical microscopy observations of salinity controlled macroscopic swelling and deswelling behavior of extra-large nanolamellar clay mineral particle accordions of various sizes. We find that clay particle accordions, immersed in a saline solution, at sufficiently high salinity, are in their crystalline swelling region, with only a few water layers hydrating the accordion interlayer nano-spaces, corresponding to an interlayer spacing of about 1.5 nm. Using a micropipette as a micro-tweezer and thereby transferring accordions carefully back and forth between high and low salinity solutions, we observe well defined macroscopic accordion transitions between the crystalline swelling regime and an osmotic swelling regime where the interlayer spacings reach tens of nanometers, calculated from accordion thicknesses measured by digital imaging. The transitions display a clear first order character as evidenced by threshold salinity levels for their abrupt onsets as well as clear hysteresis with retention of crystalline or osmotic state memory, as salinity is increased or lowered. The experimental observations are supported by a theoretical model of the accordion interlayer spacing based on a Donnan equilibrium originating from the salinity gradient between the embedding saline solution and the ionic strength in the clay interlayers in the osmotic swelling regime.

Maximizing transmission capacity in optical communication systems utilizing a microresonator comb laser source with adaptive modulation and bandwidth allocation strategies

Traditional optical communication systems employ bulky laser arrays that lack coherence and are prone to severe frequency drift. Dissipative Kerr soliton microcombs offer numerous evenly spaced optical carriers with a high optical signal-to-noise ratio (OSNR) and coherence in chip-scale packages, potentially addressing the limitations of traditional wavelength division multiplexing (WDM) sources. However, soliton microcombs exhibit inhomogeneous OSNR and linewidth distributions across the spectra, leading to variable communication performance under uniform modulation schemes. Here, we demonstrate, for the first time, to our knowledge, the application of adaptive modulation and bandwidth allocation strategies in optical frequency comb (OFC) communication systems to optimize modulation schemes based on OSNR, linewidth, and channel bandwidth, thereby maximizing capacity. Experimental verification demonstrates that the method enhances spectral efficiency from 1.6 to 2.31 bit ⋅ s−1 ⋅ Hz−1, signifying a 44.58% augmentation. Using a single-soliton microcomb as the light source, we achieve a maximum communication capacity of 10.68 Tbps after 40 km of transmission in the C-band, with the maximum single-channel capacity reaching 432 Gbps. The projected combined transmission capacity for the C- and L-bands could surpass 20 Tbps. The proposed strategies demonstrate promising potential of utilizing soliton microcombs as future light sources in next-generation optical communication.

EVALUATION OF PHYSICAL AND MECHANICAL PROPERTIES OF BN REINFORCED AL7079 METAL MATRIX COMPOSITES

Metal matrix composites (MMCs) are regarded as viable alternatives to conventional materials such as metals, plastics, and ceramics in structural applications due to their properties, including lightweight, high specific stiffness, elevated elastic modulus, enhanced specific strength, and excellent wear resistance. Among the many metal composites, aluminum metal matrix composites (MMCs) have emerged as sophisticated engineering materials for several prospective applications in engineering industries due to their superior qualities compared to typical aluminum alloys. Ceramic particles are the most extensively utilized reinforcements in MMCs due to their superior wear resistance, thermal stability, and exceptional bonding with the matrix. This research work has been conducted to develop ceramic particle-reinforced aluminum matrix composites and to evaluate their physical and mechanical properties. Al7079 alloy and Boron Nitride (BN) are selected as the matrix and reinforcement for the study respectively. The stir casting technique was utilized to fabricate the composites.Al7079-BN composites are prepared by varying the percentage of BN reinforcement particles from 0 to 8% by volume, with an increment of 2%. Test specimens were machined from the produced composites for the evaluation of microstructural, physical, mechanical properties according to ASTM standards. The microstructural analysis of the produced samples was conducted using scanning electron microscopy (SEM). The density of the composite was assessed empirically using Archimedes principle and theoretically through the rule of mixture. Microstructural analysis reveals a homogeneous distribution of BN particles throughout the matrix without any agglomeration, and it also demonstrates excellent bonding. The density of the composites decreased by approximately 4.6% with the incorporation of BN reinforcement up to 8%, attributed to the lower density of BN particles. The mechanical properties such as hardness, tensile strength, Youngs modulus, and compressive strength of the composite increases significantly.

Numerical Study of Detonation Waves in Gas Suspensions with Spatially Inhomogeneous Particle Concentration Distribution in Sharply Expanding Pipes

The article presents some results of a numerical study of detonation waves in gas suspensions with a spatially inhomogeneous distribution of particle concentration in sharply expanding pipes obtained by the large particle method. The purpose of the research is to study the influence of pipeline geometry and longitudinally spatially inhomogeneous distribution of particle concentration on the propagation of detonation waves in gas suspensions. It is shown that the size of the narrow and wide parts of the pipeline, as well as, the spatially inhomogeneous distribution of particle concentrations, qualitatively and quantitatively affect this process. Three detonation modes have been identified: continuous wave propagation, complete cessation, and partial disruption with subsequent recovery. It has been established that, at a fixed total mass of suspension, a layer with a linearly decreasing law of change in the concentration of unitary fuel particles better attenuates detonation waves than with a linearly increasing and homogeneous one.

Spin angular momentum and optical chirality of Poincaré vector vortex beams

Abstract The optical chirality and spin angular momentum of structured scalar vortex beams has been intensively studied in recent years. The pseudoscalar topological charge $\ell$ of these beams is responsible for their unique properties. Constructed from a superposition of scalar vortex beams with topological charges $\ell_\text{A}$ and $\ell_\text{B}$, cylindrical vector vortex beams are higher-order Poincar'e modes which possess a spatially inhomogeneous polarization distribution. Here we highlight the highly tailorable and exotic spatial distributions of the optical spin and chirality densities of these higher-order structured beams under both paraxial (weak focusing) and non-paraxial (tight focusing) conditions. Our analytical theory can yield the spin angular momentum and optical chirality of each point on any higher-order or hybrid-order Poincar'e sphere. It is shown that the tunable Pancharatnam topological charge $\ell_{\text{P}} = (\ell_\text{A} + \ell_\text{B})/2$ and polarization index $m = (\ell_\text{B} -\ell_\text{A})/2$ of the vector vortex beam plays a decisive role in customizing their spin and chirality spatial distributions. We also provide the correct analytical equations to describe a focused, non-paraxial scalar Bessel beam.

Study of Electron Beam Irradiated Palladium on Carbon Catalysts for Transfer Hydrogenation Reactions of Nitroarenes Compounds

Palladium-catalyzed hydrogenation is considered a crucial stage in the entire synthesis of difficult natural products as well as a crucial step in the manufacturing of fine compounds used in pharmaceuticals. When it comes to the reaction rate and simplicity of work-up, using Pd/C as heterogeneous catalyst is one of the best choice for process efficiency. In this study, nitroarenes compounds viz. 3-bromo nitrobenzene, 4-fluoro nitrobenzene, 3-methyl nitrobenzene, 4-hydroxy nitrobenzene reduced by using macro 10% Pd/C and micro 10% Pd/C to 3-bromo aniline, 4-fluoro aniline, 3-methyl aniline, 4-hydroxy aniline respectively and verified from 1H NMR studies. The reduction reactions were similar conditions using electron beam irradiated 250 kGy macro and micro 10% Pd/C catalyst. The effectiveness of commercial sources of palladium on carbon (Pd/C) varies widely, leading to the appreciable variations in the reaction times. The decrease in reaction time has been attributed to the higher dispersion of Pd particles upon irradiation. The physico-chemical characteristics of effective hydrogenation catalysts were determined to be: (i) small Pd particle size and (ii) homogeneous distribution of Pd on the carbon support. With no significant loss of catalytic activity, the electron beam-irradiated catalyst can be used again for five runs. These days, chemists can determine as well as forecast the effectiveness of catalysts before investing time and money in expensive synthetic materials.

Biocompatible Zn-Phthalocyanine/Gelatin Nanofiber Membrane for Antibacterial Therapy.

In this study, the fabrication and characterization of Zn-phthalocyanine/gelatin nanofibrous membranes is reported using the electrospinning technique. The membranes exhibit a homogeneous distribution of Zn-phthalocyanine within the gelatin matrix, maintaining the structural integrity and photosensitizing properties of the phthalocyanine. Scanning electron microscopy revealed that the electrospun fibers possess diameters ranging results as 100-300, 200-700, and 300-800nm for Gel, ZnPc/Gel 1, and ZnPc/Gel 2, respectively. The addition of ZnPc does not decrease the hydrophilicity of the Gel membrane. The nanofibrous membranes showed good cytocompatibility, as indicated by the high viability of Vero cells exposed to membrane extracts. Furthermore, these composites supported cell adhesion and proliferation on their surfaces. The two Zn-phthalocyanine/gelatin nanofiber formulations exhibited significant antimicrobial activity toward Escherichia Coli (E. Coli) and Staphylococcus Aureus (S. Aureus) under visible light illumination, achieving reductions of 3.4 log10 and 3.6 log10 CFUmL-1 for E. coli, and 3.9 log10 and 4.1 log10 CFUmL-1 for S. aureus. These results demonstrate the potential of Zn-phthalocyanine/gelatin nanofibrous membranes as effective agents in antibacterial photodynamic therapy, providing a promising solution to control bacterial infections and antibiotic resistance.

Improving compositional homogeneity of CF53 steel products by modifying their solidification structure and F-EMS intensity

In this article, based on the mechanism of stirring induced solute washing, the solidification characteristics of CF53 steel for camshafts were systematically studied through industrial casting tests and numerical simulations, focusing on the impact of solidification structure and final electromagnetic stirring (F-EMS) on solute distribution homogeneity in the core area of the bloom casting. The results indicate that excessive columnar crystal development, coupled with inappropriate use of F-EMS, can lead to significant negative segregation in the bloom, resulting in the formation of “white bands” in the following rolling bar products. Compared with weak stirring, strong stirring can affect solutes at deeper levels between dendrites. By reducing superheat and casting speed, expanding the equiaxed crystal zone in the bloom's centre, and carefully controlling the stirring intensity of F-EMS to position the molten steel washing in the equiaxed crystal zone, along with maintaining a maximum tangential velocity of 0.0041 m/s, a substantial improvement in solute distribution homogeneity within the bloom's core area was achieved. The carbon range can be reduced from 0.093% to 0.032%. These findings offer a theoretical foundation and practical suggestions for enhancing the quality of CF53 steel bloom castings and their hot-rolled bar products used in camshaft manufacture.

Evaluation of the use and performance of natural filler based polypropylene/leonardite composites

The use of polypropylene (PP), which has reached a considerably high level in the last century and is one of the polymers whose properties have been investigated and studied in much more detail with the use of various additives, can be obtained as composite structures with the use of both inorganic and organic additives, and the desired properties can be modified according to the desired purpose. In this study, it was aimed to evaluate the behavior of leonardite, a rich source of humic acid, with PP composite structures, whose performance with thermoplastic materials has never been investigated before, although there are studies on its use in different sectors. To evaluate the effects of different ratios of leonardite additives on PP polymer, the composites were prepared with a twin screw extruder, and the test specimens were produced using an injection molding device. Spectroscopic, density, microscopic, mechanical (tensile, impact, flexural), thermal and color analyses of composites containing leonardite at 0, 0.5, 1, 3, 5, and 10 wt% were carried out. As the amount of leonardite in the composite increased, a slight increase was observed in the density values of the composites, with a maximum of 4.7%. In microstructure analysis, a homogeneous distribution of the filler was observed in composites reinforced up to 1 wt%, while agglomeration occurred at higher rates. While the highest tensile strength and flexural strength values were found for the 5 wt% leonardite filled composite, it was observed that these values increased from 31.8 MPa to 32.7 MPa and from 32.84 MPa to 37.84 MPa compared to the pure PP, respectively. The highest Izod impact strength value was determined for the 10 wt% leonardite filled composite and an increase in this value was obtained from 2.47 kJ/m2 to 2.85 kJ/m2. The nucleation effect explains the decrease in supercooling temperature observed in the thermal analysis results. Furthermore, an increase of the thermal stability of PP/leonardite composite structures was demonstrated. When the color analysis results were examined, it was seen that the leonardite additive caused the color of the composite to darken, as expected.

A Comprehensive Study of Open Cluster Chemical Homogeneity Using APOGEE and Milky Way Mapper Abundances

Stars in an open cluster are assumed to have formed from a broadly homogeneous distribution of gas, implying that they should be chemically homogeneous. Quantifying the level to which open clusters are chemically homogeneous can therefore tell us about interstellar medium pollution and gas mixing in progenitor molecular clouds. Using Sloan Digital Sky Survey (SDSS)-V Milky Way Mapper and SDSS-IV Apache Point Observatory Galaxy Evolution Experiment DR17 abundances, we test this assumption by quantifying intrinsic chemical scatter in up to 20 different chemical abundances across 26 Milky Way open clusters. We find that we can place 3σ upper limits on open cluster homogeneity within 0.02 dex or less in the majority of elements, while for neutron capture elements, as well as those elements having weak lines, we place limits on their homogeneity within 0.2 dex. Finally, we find that giant stars in open clusters are ∼0.01 dex more homogeneous than a matched sample of field stars.

Analysis of Stress Corrosion Cracking Growth Rate in the Heat-Affected Zone of 316L Based on the Heterogeneity of the Mechanical Properties

The heterogeneity of the microstructure and mechanical properties of safe-end dissimilar metal welded joints (DMWJs) presents a challenge to the quantitative prediction of the stress corrosion cracking (SCC) growth rate directly from laboratory data. This study investigates the effect of the heterogeneity of the mechanical properties of the 316L-welded heat-affected zone (HAZ) in safe-end DWMJs on the SCC tip stress-strain field and the SCC growth rate. First, based on the analysis of microstructures in localized regions within the 316L-welded HAZ and the acquisition of material mechanical properties through microhardness testing, a user-defined material subroutine was developed to characterize the heterogeneous material properties within the 316L-welded HAZ. Then, using this finite element model with an inhomogeneous distribution of the mechanical properties of the material, the crack tip strain rates (CTSRs) at different locations within the 316L-welded HAZ were obtained. In conjunction with the FRI model, the SCC growth rates at various locations within the HAZ were determined. The results show that the closer to the 52Mw/316L fusion boundary within the 316L-welded HAZ, the greater the yield strength of the material and the higher the CTSR and predicted SCC growth rates at the characteristic distance.