Internal Inclusions Research Articles

Fabrication, characterization and transdermal properties of double cross-linked gel beads with 4-n-butylresorcinol

In this paper, sodium alginate (SA) -agarose double cross-linked gel beads were prepared to improve the solubility of 4-n-butylresorcinol and to reduce skin irritation. The wrappage material suitable for 4-nBR gel beads was SA-agarose double cross-linking material, and the internal inclusions were in the form of 4-n-butylresorcinol nanoemulsions (4-nBR NEs). Under the orthogonal fluorescence microscope, it was observed that the gel beads were spherical in shape, with smooth and rounded surfaces and permeable interiors. The encapsulation rate of the gel beads was 84.37 ± 3.56 %, and the average diameter was 1.93 ± 0.21 mm. Scanning electron microscopy showed that the gel beads were spherical in shape. The cumulative leakage rate of the gel beads on the 35 th day was 4.72 ± 0.06 %, suggesting that the gel beads encapsulated 4-butylresorcinol to good effect and with high stability. This proves that the gel beads wrapped with 4-nBR are highly effective and stable. In vitro skin permeability assessment verified the good skin permeability of nanoemulsions (NEs).

Crystal Growth of LiNa5Mo9O30 Crystals of High Optical Quality

The bulk of the LiNa5Mo9O30 (LNM) crystals were successfully grown in the [010] and [001] directions without internal inclusions and cracks, using the Czochralski method with a low temperature gradient. The crystal grown in the [010] direction showed a tendency to twinning. The crystal grown in the [001] direction demonstrated high structural perfection (FWHM = 13″) for the (001) plane and high optical quality Δn ≈ 2 × 10−5. The laser-induced damage threshold was measured along a, b and c axes and was 12.2, 27.0 and 27.5 J/cm2, respectively. The thermo-optical coefficient dn/dT was measured for the main crystallographic axes, which was −5.75 × 10−6, −20.2 × 10−6 and 3.65 × 10−6 K−1 along the a, b and c axes, respectively. The second harmonic generation (SHG) was conducted in the crystalline LNM sample. The maximum efficiency value of 3.5% at a pump power of 12 W was achieved.

Experimental Scattering Matrices of Martian Dust Aerosols with Narrow Particle-size Distributions

We present experimental scattering matrices of the JSC Mars-1, MMS-2, and MGS-1 simulants at 488 and 640 nm. The analogs were processed so that narrow size distributions representative of Martian dust aerosols during different dust cycles were obtained. We find that the forward peak of the phase function depends on particle size as it becomes narrower with increasing size, whereas the side- and backscattering directions depend on both composition and size so that increasing size and decreasing absorption produce a flatter curve. The position and maximum of the degree of linear polarization varies based on particle size and composition, and the negative polarization branch is more prominent for wavelength-scale particles diminishing with increasing size. The linear depolarization is strongly affected by size and composition. Finally, we compare sky-brightness curves measured by the Navcam and Hazcam engineering cameras on board the Mars Science Laboratory rover to the measured phase functions. The observations show a narrower peak at the forward direction and a flatter curve toward the side- and backscattering directions with an increasing dust load in the atmosphere, similar to what can be seen for the measured phase functions of the analogs with increasing particle size. In the case of the analogs, the flattening of the curve can be caused by an increase in multiple scattering within a particle by wavelength-scale surface roughness and/or internal inclusions. For the observed sky brightnesses, particle aggregation and multiple scattering among particles in denser dust conditions play a major role.

Investigation into the mechanisms of Corrosion-Induced rolling contact fatigue crack initiation and propagation in pearlitic rails

Corrosion stands as a pivotal causative agent for the initiation and propagation of rolling contact fatigue (RCF) cracks on rail surfaces. This study aims to scientifically delineate the corrosion fatigue behavior of U75V rails. The study identifies the presence of oxidative corrosion and graphitization on the rail surface. Carbides near the rail surface cause stress concentration, reducing the rail’s RCF residence. Oxide corrosion engenders internal oxide inclusions within cracks, expediting RCF crack propagation. Furthermore, grain refinement and discordant deformation between soft and hard grains near the rail surface give rise to sub-surface microporosity and microcracking. These findings advance our comprehension of rail RCF and offer insights for guiding rail maintenance and informing new rail design strategies.

Effect of ultrasonic surface impact on the microstructural characterization and mechanical properties of 316L austenitic stainless steel.

In the present study, effect of ultrasonic impact treatment (UIT) on the microstructural characterization and mechanical properties of 316L stainless steel (hereinafter referred to as 316L) was investigated experimentally. The fatigue fracture mechanism of 316L before and after UIT was revealed. The experimental results indicated that the martensitic grain size induced at the impact edge was about 2.00 Å. The surface modified 316L formed a gradient nanostructure and induced a martensitic phase transformation. The hardness of the surface layer of the modified 316L was twice the hardness of its matrix. The tensile strengths of 316L before and after UIT were 576 MPa and 703 MPa, respectively. The stretching stripes of 316L were more disordered after UIT. The fatigue strengths of 316L before and after UIT were 267 MPa and 327 MPa, respectively. The fatigue cracking of 316L started from the austenite grain boundaries. The fatigue fracture surface was relatively rough. The fatigue crack sources of the modified 316L came from internal inclusions. The inclusions were oxides dominated by SiO2. As the stress range increased, the crack initiation site migrated to the interior and the fatigue fracture surface became flatter.

Free vibration analysis of twin piezoelectric inclusions embedded in elastic medium

The present study is the first attempt to investigate the free vibration behavior of the rectangular plate including two equal (twin) internal parallel piezoelectric inclusions (lying width-wise in the plate) utilizing the 3D exact equations of electroelasticity theory. For the solution, the finite element method is applied. By Hamilton’s principle, the equation of motion and boundary conditions are obtained to derive the finite element equations using the electrical energy of the piezoelectric material and the mechanical energy of the structure. Lateral edge surfaces of the plate have zero electrical potential and are simply supported. Ideal contact conditions are satisfied by the interface surfaces between the elastic medium and piezoelectric (abbreviated as PZT) inclusions. After investigating the convergence and validation of the approach, the influence of various parameters on the natural frequencies of the plate behavior, such as the mutual effect of PZT inclusions, coupling effect between the electrical and mechanical fields, the effect of the size, location, material, and polled directions of the PZT inclusions, and the material of the elastic medium, is investigated.

Vacuole dynamics and popping-based motility in liquid droplets of DNA

Liquid droplets of biomolecules play key roles in organizing cellular behavior, and are also technologically relevant, yet physical studies of dynamic processes of such droplets have generally been lacking. Here, we investigate and quantify the dynamics of formation of dilute internal inclusions, i.e., vacuoles, within a model system consisting of liquid droplets of DNA ‘nanostar’ particles. When acted upon by DNA-cleaving restriction enzymes, these DNA droplets exhibit cycles of appearance, growth, and bursting of internal vacuoles. Analysis of vacuole growth shows their radius increases linearly in time. Further, vacuoles pop upon reaching the droplet interface, leading to droplet motion driven by the osmotic pressure of restriction fragments captured in the vacuole. We develop a model that accounts for the linear nature of vacuole growth, and the pressures associated with motility, by describing the dynamics of diffusing restriction fragments. The results illustrate the complex non-equilibrium dynamics possible in biomolecular condensates.

Peridynamic modeling of hydrogen-assisted white etching cracks in bearing steel under rolling contact fatigue

A coupled mechanical-diffusion peridynamic(PD) fatigue model is proposed to simulate hydrogen-assisted white etching cracks(WEC) in bearing steel under rolling contact fatigue(RCF). The PD model of microstructural alteration is established based on the dislocation-assisted carbon migration theory to simulate the formation of the dark etching region(DER) and white etching area(WEA), and its validity is demonstrated by reported experimental observations. The PD stress-assisted diffusion model is utilized to simulate the diffusion of hydrogen. Then the polycrystalline fatigue simulation is implemented to analyze the evolution of hydrogen-assisted WEC. Moreover, this study discusses the effects of contact conditions and internal inclusions on WEC evolution.

Microscope studies of symptomless growth of Botrytis cinerea in Lactuca sativa and Arabidopsis thaliana.

The grey mould pathogen Botrytis cinerea forms systemic associations in some hosts, spreading into plant organs produced a considerable time after initial infection. These infections may have no macroscopic symptoms during much of the hosts' lifetime and are at least partially within the host tissue. The aim of the studies reported here was to locate and visualize these infections at a cellular level in Lactuca sativa (lettuce) and Arabidopsis thaliana. Symptomless but infected plants were produced by dry spore inoculation of plants growing in conditions previously shown to result in fungal spread from the initial inoculation site to newly developing plant organs. Tissue taken from inoculated plants was examined using confocal laser scanning microscopy. Two B. cinerea isolates were used: B05.10 and its GFP-labelled derivative Bcgfp1-3. Spore germination on leaf surfaces was followed by development of subcuticular inclusions and plant cell damage in single infected epidermal cells and sometimes a few nearby cells. Sparsely branched long hyphae arose and spread from the inclusions, mostly on the outer surface of the epidermal layer but occasionally below the cuticle or epidermal cells, where further inclusions formed. This was consistent with the pattern in time of recovery of B. cinerea from surface-sterilized leaf tissue. In the late symptomless phase, mycelium arising from internal fungal inclusions formed mycelial networks on the surface of leaves. Symptomless exterior mycelium grew on the roots in A. thaliana.

Effect of microstructure on gigacycle fatigue and crack growth behavior of X80 grade pipeline steels

The gigacycle fatigue properties and crack growth behavior of two X80 pipeline steels with different microstructures of acicular ferrite (AF) and dual-phase (DP) were investigated. The experimental results show that the S-N curves of the two steels exhibit continuous declines over 109 cycles without fatigue limits, with fatigue strengths of 428 ± 7 MPa and 363 ± 8 MPa respectively. Most fatigue cracks in the DP steel initiated from the surface, while the fatigue fracture of the AF steel was mainly initiated in the internal inclusions. The DP steel exhibited a higher fatigue crack growth (FCG) rate than the AF steel.

Interaction mechanism of Ge, Ti, and N in diamond prepared by high pressure and high temperature conditions

In this paper, Ge-doped large single crystal diamond was synthesized under high pressure and high temperature (HPHT) conditions in NiMnCo-C and NiMnCo-Ti-C systems. The effects of Ge additives on the diamond morphology, nitrogen impurity content, and internal inclusions were investigated, and the interaction mechanism among germanium (Ge), nitrogen (N), and titanium (Ti) during the diamond growth process was discussed. The results show that the number of inclusions in diamond increase with increases in Ge addition in both systems. The N content of diamond grown in NiMnCo-C systems decreases with increases in Ge addition. However, Ge can more easily be doped into the diamond in a NiMnCo-Ti-C growth system. The experimental results show that the N can inhibit the amount of Ge entering the diamond lattice under HPHT conditions. When Ti was introduced into the system, it effectively removed N by combining with it, such that more Ge atoms could enter the diamond lattice.

Effects of Non-Metallic Inclusions and Mean Stress on Axial and Torsion Very High Cycle Fatigue of SWOSC-V Spring Steel

Inclusion-initiated fracture in high-strength spring steel is studied for axial and torsion very high cycle fatigue (VHCF) loading at load ratios of R = −1, 0.1 and 0.35. Ultrasonic S-N tests are performed with SWOSC-V steel featuring intentionally increased numbers and sizes of non-metallic inclusions. The fatigue limit for axial and torsion loading is considered the threshold for mode I cracks starting at internal inclusions. The influence of inclusion size and Vickers hardness on cyclic strength is well predicted with Murakami and Endo’s area parameter model. In the presence of similarly sized inclusions, stress biaxiality is considered by a ratio of torsion to axial fatigue strength of 0.86. Load ratio sensitivity is accounted for by the factor ((1 − R)/2)α, with α being 0.41 for axial and 0.55 for torsion loading. VHCF properties under torsion loading cannot appropriately be deduced from axial data. In contrast to axial loading, the defect sensitivity for torsion loading increases significantly with superimposed static mean load, and no inclusion-initiated fracture is found at R = −1. Size effects and the stress gradient effective under torsion loading are considered to explain smaller crack initiating inclusions found in torsion ultrasonic fatigue tests.

Computation of Optical Properties of Core-Shell Super-Spheroids Using a GPU Implementation of the Invariant Imbedding T-Matrix Method

Particles with internal inclusions or cores are ubiquitous in the atmosphere. One example is dust particles coated with water-soluble aerosols such as sulfate or nitrate. For these particles, the dust non-sphericity and the core-shell structure of the particle both fundamentally impact the optical properties. However, it is challenging to obtain an accurate and comprehensive parameterization of the optical properties of coated atmospheric particles. Recent studies have found that super-spheroids could provide a robust model for representing the non-sphericity of irregular particles, such as dust, sea salt, and ice particles. This important finding warrants further investigations on coated super-spheroids for the development of mixed-aerosol models. In this study, we developed a GPU version of the invariant imbedding T-matrix program (GPU-IITM) to improve the computational efficiency. This version allows for efficient computation of the optical properties of coated super-spheroids with extensive shape parameters and refractive indices. The GPU-IITM is 8–25 times more efficient than the conventional CPU-IITM, depending on the size parameter of the coated super-spheroids. The single-scattering properties of coated super-spheroids computed from the GPU-IITM allows for close examination of the optical differences between homogeneous and inhomogeneous particles. As an example, we present the linear depolarization ratios (LDRs) of coated super-spheroids, which have implications in active lidar remote-sensing research. We found that the LDR decreases obviously as the real part of the shell’s refractive index increases from 1.3 to 1.6. Greater LDRs occur for particles with a thin coating, while a rounder shape of the particle decreases the LDRs. However, special attention should be given to nearly spherical particles, for which the LDRs could be enhanced. In comparison to homogeneous particles, the degree of enhancement decreases or increases depending on whether the shell’s refractive index is smaller or larger than the core refractive index.

The Wormholes Within: A Study of 1, 3, 5‐Triamino‐2, 4, 6‐Trinitrobenzene Crystal Morphology by Micro and Nano‐Scale X‐Ray Computed Tomography and its Effects Upon the Shock Sensitivity of Detonation

AbstractWe understand heterogeneous‐explosive detonation only to the extent that we can first measure the salient chemical and microstructural features. Barring an inordinate amount of trial and error, we can tailor the detonation properties of our HE formulations only to the extent that we understand (at least qualitatively) the same effects. As an insensitive high explosive, 1, 3, 5‐triamino‐2, 4, 6‐trinitrobenzene (TATB) burns more heterogeneously than conventional high explosives, making its detonation properties sensitive to microstructure. The Benziger route can produce various grain morphologies depending on the amount of water used in the amination step. So‐called dry‐aminated (DA) TATB crystals are riddled with a void structure called wormholes, which are washed out ammonium chloride (NH4Cl) inclusions that form during synthesis. So‐called wet‐aminated (WA) TATB crystals do not contain NH4Cl inclusions but possess a very convoluted external structure. Using both micro and nano‐scale CT, we explore three DA‐TATB lots that reflect evolutionary processing changes, plus one WA‐TATB material. Micro CT imaged crystal collections show the exterior grain structure, revealing its roughness and providing a crude particle size measurement. The DA‐TATB lots that test most sensitively in the LANL ECOT corner‐turning test are roughest, having the appearance of being “corroded”. Nano‐scale CT reveals both internal NH4Cl inclusions and void structures. The DA‐TATB lots that tested intermediate and high sensitivity in ECOT exhibited similar wormhole structures, which were more extensive than that of the low‐sensitivity lot. The least sensitive DA‐TATB lot also retained more NH4Cl, consistent with reduced connectivity of voids to the surface.

Ultrafine-grained twinning-induced plasticity steel prepared by mechanical alloying and spark plasma sintering

A twinning-induced plasticity (TWIP) steel was prepared by mechanical alloying and spark plasma sintering (SPS), and its microstructure and mechanical behavior were examined. The ultrahigh microhardness and considerable tensile strength of the sintered bulk sample were mainly attributed to grain-size strengthening and particle strengthening by numerous Mn-rich particles dispersed in the matrix. Micropores coupled with large internal inclusions easily produced cracks in the bulk sample under uniaxial tensile stress, resulting in poor ductility with rapid intergranular brittle fracture. The ductility of the material showed significant improvement with the elongation increased from 4% to 13% after annealing the bulk sample at 850 °C for 1 h. The size of the inclusions in the annealed sample dramatically reduced and several small dimples with high densities and depths were formed, presenting a mixed fracture mode in which intergranular fracture was the dominant mechanism, whereas transgranular fracture was the supplementary mechanism.

Multi-Frequency Magnetic Induction Tomography System and Algorithm for Imaging Metallic Objects.

Magnetic induction tomography (MIT) is largely focused on applications in biomedical and industrial process engineering. MIT has a great potential for imaging metallic samples; however, there are fewer developments directed toward the testing and monitoring of metal components. Eddy-current non-destructive testing is well established, showing that corrosion, fatigue and mechanical loading are detectable in metals. Applying the same principles to MIT would provide a useful imaging tool for determining the condition of metal components. A compact MIT instrument is described, including the design aspects and system performance characterisation, assessing dynamic range and signal quality. The image rendering ability is assessed using both external and internal object inclusions. A multi-frequency MIT system has similar capabilities as transient based pulsed eddy current instruments. The forward model for frequency swap multi-frequency is solved, using a computationally efficient numerical modelling with the edge-based finite elements method. The image reconstruction for spectral imaging is done by adaptation of a spectrally correlative base algorithm, providing whole spectrum data for the conductivity or permeability.

Crystallomorphological and physical properties of apatite from carbonatites

This paper presents the results of the study of x-ray luminescence of apatite from different genetic types of apatite species in order to study its geochemical characteristics and the possibility of using as a mineral indicator the conditions of ore formation and for search purposes. Apatite Ca2Ca3(F,Cl,OH)2[PO4]3 contains impurities Gd3+, Ce3+, Eu2+, Dy3+, Sm3+, Nd3+ as well as Mn2+ and others. Syngony is hexagonal. Crystals of prismatic habit; usually ending in dipyramide or basopinacoid. Sometimes forms tabular crystals. A hexagonal prism is often preserved. Color greenish, bluish-green; pinkish-purple, gray; often white, colorless or brown. Quite often translucent due to the presence of small internal cracks and inclusions; sometimes the inclusions are arranged oriented, preferably parallel to the main axis of the crystal. Brightly luminesces in cathode, x-ray and ultraviolet rays. The intensity and color of luminescence varies widely depending on the impurities. The presence of three crystal chemical positions in the structure of apatite – two cationic and one anionic makes it possible to be realized in the mineral by a wide heterovalent substitution. The distribution of isomorphic impurities between the crystal chemical positions will depend on the type of cation, its amount, as well as anionic substitutions in apatite. To determine the luminescence intensity values of the characteristic isomorphic impurities of apatite TR3+ (Gd3+, Ce3+, Eu2+, Dy3+, Sm3+, Nd3+) and Mn2+, the X-ray luminescence method was applied. Apatites of different genetic types of the Aldan, Baltic Shields, the Baikal region (Russia), the Sette-Daban Range, and the Maimech-Kotui Province (Yakutia) and the Ukrainian Shield were investigated. The obtained values of luminescence intensity of TR3+ and Mn2+ can be used to diagnose the genetic type of apatite species, the conditions of mineral formation, the type of their mineralization and for search purposes. On the basis of factor analysis, it can be concluded that the intensity of the luminescence centers of rare earth elements in the apatites of each complex depends on the relative age position of the mineral in the groups of successively formed rocks. Analysis of apatite carbonatites from different deposits showed minimal fluctuations in the ratios of radiation intensity of X-ray centers (Ce3+, Sm3+, Mn2+, Eu2+), which may indicate a close geochemical situation and, consequently, the only source of matter in the formation of carbonates. Analysis of apatite carbonatites from different fields showed minimal fluctuations in the radiation intensity ratios of the centers of X-ray luminescence (Ce3+, Sm3+, Mn2+, Eu2+), which, in my opinion, may indicate a close geochemical situation and, as a consequence, the substance or the result.

Study on Microstructure and Fatigue Properties of Q960 High Strength Steel

The microstructure and fatigue properties of Q960 high strength steel were studied by optical microscope, conventional mechanical properties and fatigue tests. The results showed that the microstructure of Q960 high strength steel was tempered sorbite, the grain size grade 9, and the internal inclusions A1 and B1.5. The brinell hardness of Q960 high strength steel was 326.5HBW10/3000, the tensile strength more than 1000MPa, the impact energy 86.5J, which indicated good strength and toughness. In the case of high fatigue strength, the dispersion of fatigue life was low. The dispersion of fatigue life increased with the decrease of fatigue strength.

Failure analysis of overrunning clutch spring for main transmission system of helicopter

In the present work, the premature rupture of a spring used in the aviation sprag overrunning clutch of the helicopter was analyzed based on the general method for failure analysis by use of the investigations of the fracture surface, mechanical and chemical performance as well as the microstructure of the spring material. The results showed that spring breakage is mainly caused by mechanical fatigue. The cracks and fracture originated from internal surface of the spring, and the cracks extended from outside surface of the spring toward the external surface of the spring, which was consistent with the direction of tensile residual stress on the internal surface of the spring. The marks of the shot peening were obvious on the outer surface, while the inner surface had obvious metal flow lines, indicating that the residual tensile stress formed on the internal surface of spring. Moreover, the oxide inclusions were also detected on the internal surface of spring. It can be noted that the stress concentration on the spring internal surface and oxide inclusions are responsible for the fracture of the spring.

Transcriptomic analysis of cyanobacterial alkane overproduction reveals stress-related genes and inhibitors of lipid droplet formation.

The cyanobacterium Nostoc punctiforme can form lipid droplets (LDs), internal inclusions containing triacylglycerols, carotenoids and alkanes. LDs are enriched for a 17 carbon-long alkane in N. punctiforme , and it has been shown that the overexpression of the aar and ado genes results in increased LD and alkane production. To identify transcriptional adaptations associated with increased alkane production, we performed comparative transcriptomic analysis of an alkane overproduction strain. RNA-seq data identified a large number of highly upregulated genes in the overproduction strain, including genes potentially involved in rRNA processing, mycosporine-glycine production and synthesis of non-ribosomal peptides, including nostopeptolide A. Other genes encoding helical carotenoid proteins, stress-induced proteins and those for microviridin synthesis were also upregulated. Construction of N. punctiforme strains with several upregulated genes or operons on multi-copy plasmids resulted in reduced alkane accumulation, indicating possible negative regulators of alkane production. A strain containing four genes for microviridin biosynthesis completely lost the ability to synthesize LDs. This strain exhibited wild-type growth and lag phase recovery under standard conditions, and slightly faster growth under high light. The transcriptional changes associated with increased alkane production identified in this work will provide the basis for future experiments designed to use cyanobacteria as a production platform for biofuel or high-value hydrophobic products.