Different Types Of Inclusions Research Articles

Pit initiation on biomedical alloys-A review.

Biomedical alloys, like many engineering alloys, have chemical or physical heterogeneities at the surface, and such heterogeneities can potentially act as sites for pit initiation. Alloys of particular interest are 316/316L (and 316LVM) stainless steel, nitinol, and CoCr alloys. This review focuses on the sites-generally inclusions-that have been associated with pitting in various studies of biomedical alloys in simulated physiological solutions. The effect of these sites is discussed in relation to factors such as type and size. For both 316/316L stainless steel and nitinol, pitting has been found to initiate at two different types of inclusions: sulfide and oxide inclusions in stainless steel, and carbide and oxide inclusions in nitinol. Sulfide inclusions tend to be the predominant sites for pitting on 316/316L stainless steel, while there is some evidence to suggest that carbide inclusions may be more effective than oxide inclusions for pitting on nitinol. CoCrMo alloys differ from the other two alloys in that, although particles can be present in the form of carbides, the carbides typically do not provide sites for pit initiation except possibly for alloys with a high-C content, certain heat treatments, and when anodically polarized to high potentials. CoNiCrMo differs further in that TiN inclusions can be present in the vicinity of pits and might be associated with them, but irrespective of the initiation site, any pits are unlikely to grow because of repassivation.

Mathematical micro–macro modeling of fully coupled nonlinear magneto-elastic reinforced composites

In this paper, integral equation formulations and field-dependent micromechanical modeling of global nonlinear magneto-mechanical behavior of magneto-elastic composites under high strain and magnetic field are elaborated. The modeling is obtained based on an extension of micro–macro transition inclusion problem to nonlinear behavior using field-dependent and highly nonlinear localization tensors. A methodological procedure is elaborated based on newly introduced strain and magnetic field-dependent Green tensors, strain and magnetic field-dependent integral equations linked to tensors of Eshelby and micromechanical approaches. The field-dependent global moduli are predicted based on the Mori–Tanaka approach and self-consistent method. Iterative incremental schemes based on the Newton–Raphson and fixed-point algorithms are examined and established precise semi-analytic equations of the effective magneto-elastic properties of composites that are dependent on the magnetic-strain field for different types of inclusions. A numerical code is elaborated for numerical predictions and the obtained field-dependent effective magneto-elastic coefficients are obtained and presented for various volume fractions of inclusion, types and shapes of the reinforced nonlinear composites.

Effect of La Content on Inclusion Morphology in Automobile Sulfur‐Containing Gear Steel SCr420H

The inclusion morphology of sulfur‐containing gear steel with different La addition (0, 0.08, 0.5, and 1%) is investigated in laboratory experiments. The La and S concentrations in steel melt significantly decrease with the holding time after La addition increases, leading to different types of inclusions with specific shapes. Inclusion transformation routes with the holding time increased under different La addition are summarized as follows: 1) 0%La addition: cluster‐like Al2O3 + cluster‐like MnS → irregular block‐like MgAl2O4 + cluster‐like MnS; 2) 0.08%La addition: cluster‐like LaAlO3 + spherical‐like La‐Al‐O‐S‐(MnS) → spherical‐like La‐Al‐O‐S‐(MnS) + spherical‐like La‐Al‐O‐S‐(MgO)‐(MnS) + cluster‐like MnS; 3) 0.5%La addition: flower‐like La‐O + spherical‐like La‐O‐S → spherical‐like La‐O‐S; and 4) 1%La addition: flower‐like La‐O + spherical‐like La‐O‐S → spherical‐like La‐O‐S + cubic‐like La‐O‐S‐N‐As. The results of hot compression suggest that La‐containing inclusions are less prone to the shape change than MnS; moreover, microcracks are formed at the surface of La‐containing inclusions. The nanoindentation test demonstrates that the hardness of La‐O‐S is higher than MnS. The high La addition has a remarkable effect on refractory degradation. For 0.5% and 1% La, dissolved La reacts with the MgAl2O4 phase in the MgO‐MgAl2O4 dual‐phase refractory and changes into LaAlO3.

Development of Mid-Infrared Absorption Spectroscopy for Gemstone Analysis

Absorption spectroscopy has been widely used in gemstone societies as it enables the identification of the origin and post-treatment of gemstones in a non-destructive way. The infrared (IR) range is critical for studies of gemstones such as corundum, emerald, and diamond. Regarding the corundum sample, absorption peaks related to the -OH bond could be used as an index for heat-treatment detection, and different types of inclusions could be identified by analyzing the IR absorption spectrum. The most widely used method for measuring IR absorptions is Fourier-transform infrared spectroscopy (FTIR), which was designed based on the working of the Michelson interferometer. However, FTIR has a few limitations, such as a long measurement time and difficulty in sample placement, which limits its full automation capability. In this study, a mid-infrared (MIR) spectrometer relying on the upconversion phenomenon of non-linear crystals was used to measure the absorption spectra. Corundum with heat treatment features and/or with different common types of inclusions were measured by both transmission and reflection modes. After comparison with the FTIR spectra captured on the same sample set, the same target peaks could be captured with a shorter measurement time and easier operation. The developed MIR spectrometer could directly measure the absorption spectrum in the 2–4.5 µm (2200–5000 cm−1) range within a few seconds. Meanwhile, as both transmission and reflection modes were available, both loose and mounted gemstones could be measured, supporting the widespread use of this device in large-scale production and its ability to achieve full automation.

Fatigue cracking criterion of high-strength steels induced by inclusions under high-cycle fatigue

Fatigue properties of high-strength steels become more and more sensitive to inclusions with enhancing the ultimate tensile strength (UTS) because the inclusions often cause a relatively low fatigue strength and a large scatter of fatigue lives. In this work, four S–N curves and more than 200 fatigue fracture morphologies were comprehensively investigated with a special focus on the size and type of inclusions at the fatigue cracking origin in GCr15 steel with a wide strength range by different heat treatments after high-cycle fatigue (HCF). It is found that the percentage of fatigue failure induced by the inclusion including Al2O3 and TiN gradually increases with increasing the UTS, while the percentage of failure at sample surfaces decreases conversely and the fatigue strength first increases and then decreases. Besides, it is interestingly noted that the inclusion sizes at the cracking origin for TiN are smaller than that for Al2O3 because the stress concentration factor for TiN is larger than that for Al2O3 based on the finite element simulation. For the first time, a new fatigue cracking criterion including the isometric inclusion size line in the strength-toughness coordinate system with specific physical meaning was established to reveal the relationship among the UTS, fracture toughness, and the critical inclusion size considering different types of inclusions based on the fracture mechanics. And the critical inclusion size of Al2O3 is about 1.33 times of TiN. The fatigue cracking criterion could be used to judge whether fatigue fracture occurred at inclusions or not and provides a theoretical basis for controlling the scale of different inclusion types for high-strength steels. Our work may offer a new perspective on the critical inclusion size in terms of the inclusion types, which is of scientific interest and has great merit to industrial metallurgical control for anti-fatigue design.

Dynamic fracture analysis of sandstone specimens containing different inclusions

Infilling materials are commonly distributed in natural rocks, which play a key role in the stability of rock engineering. To reveal the enhancing mechanism of inclusions, dynamic uniaxial compressive tests were carried out on sandstone specimens containing double elliptical flaws using a split Hopkinson pressure bar (SHPB) system and the digital image correlation (DIC) technique, and three inclusion conditions (R1, R2 and R3) and three flaw inclination angles (0°, 45° and 90°) were taken into consideration. The results indicate that the inclusions (R2 and R3) with a similar wave impedance to sandstone matrix can maximally enhance the dynamic strength of flawed specimens by 46.82% and 42.83%, respectively. The crack initiation and propagation behavior were significantly changed after the flaws were filled with different types of inclusions. The dominant crack in the bridge area can be identified by strain histories and stress intensity factors (SIFs) at the inner inclusion tips. The findings are projected to deepen the understanding of interaction mechanism of rock matrix and inclusions.

Asymptotic analysis for non-local problems in composites with different imperfect contact conditions

We consider a composite material made up of a hosting medium containing an ε-periodic array of perfect thermal conductors. Comparing with the previous contributions in the literature, in the present paper, the inclusions are completely disconnected and form two families with dissimilar physical behaviour. More specifically, the imperfect contact between the hosting medium and the inclusions obeys two different laws, according to the two different types of inclusions. The contact conditions involve the small parameter ε and two positive constants . We investigate the homogenization limit and the limits for going to 0 or , taken in any order, with the aim to find out the cases in which the two limits commute.

Inclusion Engineering in Medium Mn Steels: Effect of Hot-Rolling Process on the Deformation Behaviors of Oxide and Sulfide Inclusions

Medium Mn steel (MMS) is a new category of the third-generation advanced high strength steel (3rd AHSS) which is developed in the recent 1-2 decades due to a unique trade-off of strength and ductility. Thus, this steel grade has a wide application potential in different fields of industry. The current work provides a fundamental study of the effect of hot-rolling on the inclusion deformation in MMS including a varied 7 to 9 mass pct Mn. Specifically, the deformation behavior of different types of inclusions (i.e., Mn(S,Se), liquid oxide (MnSiO3), MnAl2O4, and complex oxy-sulfide) was investigated. The results show that both MnSiO3 and Mn(S,Se) are soft inclusions which are able to be deformed during the hot-rolling process but MnAl2O4 does not. The aspect ratio of soft inclusions increases significantly from as-cast to hot-rolling conditions. When the maximum size of different inclusions is similar, Mn(S,Se) deforms more than MnSiO3 does. This is due to a joint influence of physical parameters including Young’s modulus, coefficient of thermal expansion (α), etc. However, when the maximum size of one type of inclusion (e.g., MnSiO3) is much larger than another one (e.g., Mn(S,Se)), this maximum size of soft inclusions plays a dominant role than other factors. In addition, the deformation behavior of dual-phase inclusion depends on the major phase, i.e., either oxide or sulfide. Last but not least, empirical correlations between the reduction ratio of the thickness of plate, grain size, and aspect ratio of oxide and sulfide inclusions after hot-rolling are provided quantitatively. This work aims to contribute to the ‘inclusion engineering’ concept in the manufacturing of new generation AHSS.

Dissolution Behavior of Different Inclusions in High Al Steel Reacted with Refining Slags

Al2O3, Al2O3·TiN, Al2O3·MgO, and CaO·2Al2O3 are four different types of inclusions in high Al steels. To improve the steel cleanness level, the effective removal of such inclusions during secondary refining is very important, so these inclusions should be removed effectively via inclusion dissolution in the slag. The dissolution behavior of Al2O3, Al2O3·TiN, Al2O3·MgO, and CaO·2Al2O3 in CaO-SiO2-Al2O3-MgO slags, as well as the steel-slag reaction, was investigated using laser scanning confocal microscopy (LSCM) and high-temperature furnace experiments, and thermodynamic calculations for the inclusion in steel were carried out by FactSage 7.1. The results showed that Al2O3·TiN was observed to be completely different from the other oxides. The composite oxides dissolved quickly in the slags, and the dissolution time of the inclusions increased as their melting point increased. SiO2 and B2O3 in the slag were almost completely reacted with [Al] in steel, so the slags without SiO2 showed a positive effect for avoiding the formation of Al2O3 system inclusions and promoting inclusions dissolution as compared with SiO2-rich slags. The steel-slag reaction was also found to influence the inclusion types in steel significantly. Because of the rapid absorption of different inclusions in the slag, it was found that the dissolution time of inclusions mainly depends on the diffusion in the molten slag.

Mineralization of the Shangjiazhuang Mo deposit in the Jiaodong peninsula, China: Constraints from S–H–O isotopes and fluid inclusions

The Shangjiazhuang Mo deposit is located in the east of Shandong Peninsula, which is tectonically the eastern extends of the Dabie-Sulu orogenic belt. The ore bodies occur in the Early Cretaceous Yashan porphyritic granodiorite, which are stratiform, vein-like and lentoid. The orebodies are controlled by the fractures with NW direction, and have similar orientations, with strike of 337°–344° and dips of 20°–26° to the northeast. The potassic alteration, biotitization, silicification, sericitization, chloritization, and carbonatization are developed in the country rock. According to the relationship of mineral symbiotic assemblage and the cutting relationship of the hydrothermal veins, the hydrothermal metallogenic period of Shangjiazhuang Mo deposit can be divided into three stages: quartz-molybdenite (early stage), quartz-chalcopyrite and molybdenite (middle stage) and quartz-pyrite (late stage). We studied S–H–O isotopes, fluid inclusions and mineralization age of the Shangjiazhuang Mo deposit, aiming to clarify the genesis mechanism for the Mo deposits in the eastern Jiaodong Peninsula. The δ34S value of molybdenite and chalcopyrite in the main metallogenic stage range from 4.5‰ to 5.0‰, which is consistent with magmatic sulfur. The δ18OH2O valve decrease gradually from the early metallogenic stage (4.5‰–5.0‰) to the late metallogenic stage (0.39‰–1.48‰), indicating that the ore-forming fluids were mainly magmatic water at the early stage and a mixture of meteoric and magmatic water at the late stage. The ore-forming fluids evolved from moderate temperature, CO2-rich and high salinity at the early stage to low temperature, CO2-poor with nearly constant salinity in the late stage. Different types of inclusions with similar temperature and different salinity coexist in the main metallogenic period, indicating that as temperature drops, fluids in the system were either immiscible or boiling, leading to CO2 escape, and finally leads to the precipitation and enrichment of ore-forming elements.

Effect of LCFeCr Alloy Additions on the Non-metallic Inclusion Characteristics in Ti-Containing Ferritic Stainless Steel

The influence of commercial low carbon ferrochromium (LCFeCr) additions on the inclusion characteristics in Ti-containing ferritic stainless steel was studied by laboratory experiment in this work. The inclusions in steel before and after the FeCr alloy additions were investigated through systematic samplings and microscopy investigations of the liquid steel. Different types of inclusions in the FeCr alloy and steel were detected and the evolution of the inclusion characteristics (e.g., composition, size, morphology, and number density) were investigated. The results showed that the Ti content decreased after the FeCr alloy additions. Furthermore, MnCr2O4 spinel inclusions originating from the FeCr alloys transformed into Ti2O3–Cr2O3-based liquid inclusions and Ti2O3-rich solid inclusions. They were formed due to the reactions between MnCr2O4 and TiN inclusions or dissolved Ti in molten steel. The ratio of Ti/Al in the steel melt has a direct influence on the evolution of inclusions from thermodynamic calculations. The addition of FeCr alloys caused an increased number density of these Ti2O3-containing inclusions and TiN inclusions up to 8 minutes from the time of alloy addition. The increased Cr content from 16 to 24 mass pct due to the FeCr additions can increase the critical N content to form TiN inclusions at a specific Ti content. Overall, this study has contributed to the understanding the behavior of inclusions from LCFeCr alloy during the alloying process in Ti-containing steel.

A comparative fracture analysis on as-received and electrochemically hydrogen charged API X60 and API X60SS pipeline steels subjected to tensile testing

In this study, a comparative analysis of fracture surfaces in API X60 and API X60SS pipeline steels is carried out after hydrogen charging followed by tensile testing. The JIS test setup is also utilized in order to measure the amount of discharged hydrogen through the microstructure of both steels. EBSD measurements are also done on as-received and hydrogen charged specimens in order to observed the HIC propagation. The results show that a considerable amount of hydrogen is able to diffuse through the microstructure of both steels. The tensile testing after hydrogen charging proves that hydrogen embrittlement occurs significantly in both steels. At the center of cross section in both steels, the fracture occurs by micro-voids formation, their growth and coalescence around the different types of inclusions. In charged specimens, dimples are shallower in both specimens compared with the dimples in the fracture surfaces of as-received specimens. Comparatively, hydrogen embrittlement in API X60 steel is more noticeable and its surface is more flat than the API X60SS steel. In hydrogen-charged API X60 steel, EBSD map shows a crack stepwise jumping with 45° from one crack traction line to another, with both intergranular and transgranular crack propagation mechanisms. Moreover, the crack propagates intergranularly along gains with mismatch Taylor values, while transgranular propagation mostly observed within the hard grains with high amount of dislocation density and internal energy associated with KAM map. In the case of API X60SS steel, no evidence of HIC crack was observed.

Effects of inclusion types on the high-cycle fatigue properties of high-strength steel

The high-cycle fatigue fracture behavior induced by different types of inclusions for high-strength steels was investigated. It is found that fatigue cracking of high carbon chromium bearing steel mainly originated from the interface between the matrix and the oxide inclusions while from the inside for nitride inclusions in the fatigue failure origin, respectively. The two fatigue cracking modes induced by different types of inclusions often result in a great difference in the fatigue lives even though considering the stress amplitude as well as the inclusion size. Therefore, an inclusion type factor was established for the first time to unify the effects of the inclusion types on the fatigue properties and the modified stress intensity factor could well predict the fatigue lives. These results distinguish the differences of the inclusion types in the fatigue performance and the role in trace elements control in metallurgy for the high-strength steels.

Inclusion of Social Economy Topics into the Higher Education Business Study Programmes in Slovenia

The author is addressing the problem of systematic inclusion of the topics of social economy into the accredited higher education study programmes in Slovenia. To support the actuality of the research problem, education in social economy is shown as public policies priority on national and European level. The paper aims to answers the question of existence of social economy courses in the study programmes on business (and business-related management) and the question about correspondence of the content of these courses to the needs for competences of actors in the sector of social economy. The paper also presents different types of inclusion of the topics of social economy into the systems of higher education in Europe with the purpose to show possible directions for further development of social economy education in higher education system in Slovenia. The results of the research aim to have didactical, developmental and advocacy value and applicability.

The role of inclusion-matrix boundaries in steels fracture processes

The features of the fracture of the interphase inclusion-matrix boundaries under various thermal-deformation and aggressive actions are investigated. The reasons and conditions for the formation of cracks as a result of decohesion of the inclusion-matrix boundaries associated with the concentration of interfacial thermal and deformation stresses are discussed. It was found that the character of decohesion of the inclusion-matrix boundaries (rupture of interatomic bonds of a nonmetallic inclusion and a steel matrix) caused by interphase thermal stresses is due to the conditions of heating and cooling, depending on the type of processing (conventional heating, laser or electromagnetic treatment), which determines the possibility of passing relaxation processes associated with the redistribution of interfacial defects within the specified boundaries. The mechanisms and features of decohesion of the interphase inclusion-matrix boundaries at different methods and temperatures of deformation are discussed. It is shown that the decomposition of the inclusion-matrix boundaries upon deformation occurs in cases of certain types of nonmetallic inclusions (oxides, spinels, some sulfides). For different types of inclusions and steels, parameters have been determined that characterize the cohesive strength of the inclusion-matrix interface depending on the loading conditions. It is shown that decohesion (fracture) of the inclusion-matrix boundary into two free surfaces can be considered as the transformation of interphase misfit dislocations into surface steps as a result of loss of conjugation. The role of inclusion-matrix boundaries in the formation of cracks of fatigue and fatigue-corrosion origin is considered. It is shown that under the influence of aggressive media and cyclic stresses, the structure of the inclusion-matrix interphase boundaries degrades, which is associated not only with the accumulation of interfacial stresses, but also with the facilitation of the penetration of surfactant atoms from the environment along these boundaries. As a result, fatigue-corrosion destruction of the inclusion-matrix boundaries occurs, and the effect of an adsorptive decrease in their strength is manifested.

Numerical study of shrinkage and heating induced cracking in concrete materials and influence of inclusion stiffness with Peridynamics method

This paper is devoted to numerical modelling of cracking in concrete-like materials by explicitly taking into account microscopic heterogeneities. A numerical method based on peridynamics theory is proposed. The formulation and implementation of the numerical method are first presented. Its efficiency in modelling the initiation and propagation of multiple cracks in heterogeneous materials is then demonstrated. The proposed method is further applied to the description of cracking process induced by drying shrinkage and temperature change in concrete composites containing different types of inclusions. The emphasis is put on the effect of inclusion stiffness on cracking patterns. A series of numerical simulations are performed. Comparisons between numerical results and experimental observations are presented.

Anthropogenic temperversusgeological and pedological inclusions: grog temper as a possible chrono-cultural marker for the Late Ceramic Age in the pre-Columbian Lesser Antilles

In order to compare pre-Columbian cultural affiliations in the Lesser Antilles, we studied three ceramic series from Guadeloupe (F.W.I.) from well-dated Troumassoid sites between AD 1000 and 1300 (radiometric ages) attributed to the Late Ceramic Age (AD 1000–1500). The significance of the different types of inclusions in these ceramics is discussed through a petrographic study using optical and electron microscopy, that we subsequently compared with the local geological contexts. Two of the studied sites are located in the volcanic part of Guadeloupe (Basse-Terre), while the third one is situated in an area dominated by the sedimentary substratum of Grande-Terre and its silty cover. The petrographic analysis shows either the use of local heterogeneous materials: natural, geological or pedological aplastic inclusions (volcanic sands and cinders, ferruginous soils), and the addition of grog (anthropogenic temper). At each of the three sites studied, the presence of grog was demonstrated for several modal series. Comparison of the compositions of the pastes with the ceramic chrono-typology allow us to explore the proposition presented by Donahueet al.(1990), suggesting that the use of grog may infer a difference between Troumassoid and pre-Troumassoid assemblages. We also hypothesize a progressive diffusion of the use of grog temper into the Lesser Antilles, from the Guianas. This idea defies the commonly accepted idea that Troumassoid developed smoothly out of a locally present Saladoid ceramic series without external influence.

Experimental Validation of the Attenuation Properties in the Sonic Range of Metaconcrete Containing Two Types of Resonant Inclusions

BackgroundMetaconcrete is a new concept of concrete, showing marked attenuation properties under impact and blast loading, where traditional aggregates are partially replaced by resonant bi-material inclusions. In a departure from conventional mechanical metamaterials, the inclusions are dispersed randomly as cast in the material. The behavior of metaconcrete at supersonic frequencies has been investigated theoretically and numerically and confirmed experimentally.ObjectiveThe feasibility of metaconcrete to achieve wave attenuation at low frequencies demands further experimental validation. The present study is directed at characterizing dynamically, in the range of the low sonic frequencies, the—possibly synergistic—effect of combinations of different types of inclusions on the attenuation properties of metaconcrete.MethodsDynamic tests are conducted on cylindrical metaconcrete specimens cast with two types of spherical inclusions, made of a steel core and a polymeric coating. The two inclusions differ in terms of size and coating material: type 1 inclusions are 22 mm diameter with 1.35 mm PDMS coating; type 2 inclusions are 24 mm diameter with 2 mm layer natural rubber coating. Linear frequency sweeps in the low sonic range (< 10 kHz), tuned to numerically estimated inclusion eigenfrequencies, are applied to the specimens through a mechanical actuator. The transmitted waves are recorded by transducers and Fast-Fourier transformed (FFT) to bring the attenuation spectrum of the material into full display.ResultsAmplitude reductions of transmitted signals are markedly visible for any metaconcrete specimens in the range of the inclusion resonant frequencies, namely, 3,400-3,500 Hz for the PDMS coating inclusions and near 3,200 Hz for the natural rubber coating inclusions. Specimens with mixed inclusions provide a rather uniform attenuation in a limited range of frequencies, independently of the inclusion density, while specimens with a single inclusion type are effective over larger frequency ranges. With respect to conventional concrete, metaconcrete reduces up to 90% the amplitude of the transmitted signal within the attenuation bands.ConclusionsRelative to conventional concrete, metaconcrete strongly attenuates waves over frequency bands determined by the resonant frequencies of the inclusions. The present dynamical tests conducted in the sonic range of frequencies quantify the attenuation properties of the metaconcrete cast with two types inclusions, providing location, range and intensity of the attenuation bands, which are dependent on the physical-geometric features of the inclusions.

Polystyrene-Based Nanocomposites with Different Fillers: Fabrication and Mechanical Properties.

The paper presents a comprehensive analysis of the elastic properties of polystyrene-based nanocomposites filled with different types of inclusions: small spherical particles (SiO2 and Al2O3), alumosilicates (montmorillonite, halloysite natural tubules and mica), and carbon nanofillers (carbon black and multi-walled carbon nanotubes). Block samples of composites with different filler concentrations were fabricated by melt technology, and their linear and non-linear elastic properties were studied. The introduction of more rigid particles led to a more profound increase in the elastic modulus of a composite, with the highest rise of about 80% obtained with carbon fillers. Non-linear elastic moduli of composites were shown to be more sensitive to addition of filler particles to the polymer matrix than linear ones. A non-linearity modulus βs comprising the combination of linear and non-linear elastic moduli of a material demonstrated considerable changes correlating with those of the Young’s modulus. The changes in non-linear elasticity of fabricated composites were compared with parameters of bulk non-linear strain waves propagating in them. Variations of wave velocity and decay decrement correlated with the observed enhancement of materials’ non-linearity.

Characterization of two types of intranuclear hepatocellular inclusions in NAFLD

Nuclear inclusions (NI) are a common finding in hepatocytes from patients with liver disease especially in diabetes mellitus and non-alcoholic fatty liver disease (NAFLD) but studies examining the shape and content of these inclusions in detail are lacking. In this study we define two distinct types of NI in NAFLD: inclusions bounded by the nuclear membrane, containing degenerative cell organelles and heterolysosomes (type1) and inclusions with deposits of glycogen but without any kind of organelles and delimiting membrane (type2). NI in 77 paraffin-embedded patients of NAFLD including NAFL and non-alcoholic steatohepatitis (NASH) were analyzed. In 4–12% of type1 NI immunopositivity for the autophagy-associated proteins LC3B, ubiquitin, p62/sequestosome1, cathepsin D and cathepsin B were detected with co-localizations of ubiquitin and p62; type2 NI showed no immunoreactivity. Three-dimensional reconstructions of isolated nuclei revealed that NI type1 are completely enclosed within the nucleus, suggesting that NI, although probably derived from cytoplasmic invaginations, are not just simple invaginations. Our study demonstrates two morphologically different types of inclusions in NAFLD, whereby both gained significantly in number in advanced stages. We suggest that the presence of autophagy-associated proteins and degenerated organelles within type1 NI plays a role in disease progression.