Intermedium Layer Research Articles

A promising strategy of multicomponent alloy intermedium for enhancing the mechanical performance of inertia friction welding joints of Inconel 718 alloys

A strategy of using multicomponent alloy (MCA) intermedium for inertia friction welding of IN718 alloys was proposed in this work. Exceptional metallurgic bonding was attained between the IN718 and non-equiatomic CoCrNi–AlTa MCA layer, and the as-received weld joint was absent of any defects like micro-cracks or voids. Compared with the counterpart without an intermedium layer (∼530 MPa), the yield strength of the IN718-MCA weld joint was increased to ∼610 MPa. Moreover, by conducting a two-step ageing treatment, the yield strength of the weld joint was further improved to over 1360 MPa with prominent strain hardening behavior. Noteworthily, the fracture along the interface boundary between the two materials initially observed in the unaged weld joint was fully eliminated, indicating that the ageing treatment efficiently improved the bonding of the interfacial region and further enhanced the reliability of the weld zone. Moreover, the significant strengthening effect of the aged dissimilar weld joint was found to originate from the enhanced atomic diffusion and extra back-stress hardening from geometric necessary dislocations (GNDs) produced within the interfacial regions, as well as the high density of nano-sized dispersive precipitates (for IN718) and ordered structures (for MCA) generated in the alloy matrix at elevated temperatures. The result verifies that the present strategy of adding an MCA intermedium layer can efficiently improve the mechanical performance of the weld joint for IN718 alloys, which is promising for real applications in aerospace engineering.

Expanded graphite (EG)/Ni@Melamine foam (MF)/EG sandwich-structured flexible bipolar plate with excellent electrical conductivity, mechanical properties, and gas permeability

The bipolar plate is an important component of the fuel cell. Composite graphite-based bipolar plates with adjustable properties are potential candidates to realize the high performance of the cell. However, simultaneously improving the electrical and mechanical properties of the plate is always the focus and difficulty of the research since they tend to behave with mutual inhibition. Here in this work, we report a laminating strategy to prepare composite bipolar plates with the (EG)/Ni@Melamine foam (MF)/EG sandwiched structure. The highly porous MF sponge provides enough space for epoxy immersion and the Nickel plating improves the electrical conductivity. Both the electrical conductivity (320 S/cm) and the flexural strength (56 MPa) are improved compared to the original EG plate. The enriched resin amount in the intermedium layer also ensures lower gas permeability (2.16 × 10−9 cm3cm−2s−1). In addition, owing to the residual resin on the surface of the developed plate, there is a smaller, indicating better wettability. Further practical performance tests proved that the developed plate has favorable performance under actual working conditions compared to commercialized carbon graphite plate.

Supercritical-CO2 electroless nickel plating enhanced anti-corrosion properties of micro-arc oxidized AZ31 magnesium alloy

Magnesium alloys which perform low density, high strength-to-weight ratio and excellent mechanical properties have received extensive attention especially in the weight-constrained components in aerospace and automotive industries. Nevertheless, magnesium alloys generally exhibit poor corrosion and wear resistance, which seriously limit their lifespan and developments. Regarding the aforementioned issues, we selected an AZ31 magnesium alloy as the controlled specimen, on which a designed multilayer structure was fabricated to be the surface protective coating. The multilayer coating consisted of an oxide layer prepared by micro-arc oxidation (MAO), a sputtered Ag intermedium layer and a Ni-based anti-corrosion coating deposited by supercritical CO 2 assisted electroless deposition (SC-EL-Ni). The Ag/MAO interlayer performed an excellent compatibility between the Ni coating and Mg substrate, leading to a good coating adhesion. Moreover, the as-prepared amorphous SC-EL-Ni layer exhibited a dense and uniform surface, which can effectively prevent the intergranular corrosion and galvanic corrosion. Therefore, the obtained SC-EL-Ni/Ag/MAO sample presented a much better corrosion resistance compared with the Mg alloy and the porous MAO-treated sample. • Surface properties of SC-EL-Ni/Ag/MAO coating have been systematically analyzed. • Sputtered Ag layer performed excellent compatibility between Ni and MAO coating. • Amorphous Ni film with dense and uniform surface was obtained. • SC-EL-Ni exhibited outstanding anti-corrosion property.

Web-based prototype system for flood simulation and forecasting based on the HEC-HMS model

This study addresses Hydrologic Engineering Center Hydrologic Modeling System (HEC-HMS) model simulation issues in web environments and identifies key model parameters to facilitate practical flood forecasting. Jython scripts serving as an intermedium layer between the web-based forecast system and HEC-HMS model were created to enable HEC-DSS database writing and reading and HEC-HMS model execution as a background process. Empirical relationships between model parameters and time series characteristics were established to mitigate the difficulty in determining event-dependent model parameters. An open-source web-based prototype system for flood simulation and forecasting (WSFF) based on the HEC-HMS was built by incorporating these methods and parameter knowledge into the model and knowledge subsystem. The WSFF performance was evaluated via a case study involving 12 historical flood events in the Chuanchang watershed, southeastern China. Among these 12 events, nine events served as calibration events to establish WSFF parameter knowledge, and three events were used to verify the WSFF performance. A consistent and satisfactory performance in terms of peak flow, total flood volume, peak flow timing and overall hydrograph fitting effect was found. The average Nash–Sutcliffe efficiency (NSE) for the validation events reached 0.81 versus 0.82 for the calibration events. The relative error in peak flow (REP) and relative error in flood volume (REV) indicated a reasonable flood forecasting accuracy, with an REP within 15% and RET within 1 h. Developed as open-source software, the WSFF could serve as a useful basis for the hydrological community regarding HEC-HMS adoption in flood forecasting.

Multilayer Si@SiOx@void@C anode materials synthesized via simultaneously carbonization and redox for Li-ion batteries

In the development of high-performance lithium-ion batteries (LIBs), the composition and structure of electrode materials are of critical importance. Silicon has a theoretical specific capacity 10 times that of graphite, nonetheless, its application as an anode material confronts challenge as it undergoes huge volume change and pulverization amidst the alloying and dealloying processes. Herein, a novel method to prepare a multilayer Si-based anode was proposed. Three layers, SiO2, nickel and triethylene glycol (TEG), were coated successively on Si nanoparticles, which served respectively as the sources of SiOx, sacrificial templates and carbon. Nickel can not only serve as a hollow template, but also play a catalytic role, which makes carbonization and redox reactions occur synchronously under a mild condition. Amid the carbonization process of TEG at 450 °C, several-nm-thick SiO2 layer can react with the as-derived carbon to form a silicon suboxides (SiOx (0 < x < 2)) intermedium layer. After removing the nickel template, a micro-nano scaled Si@SiOx@void@C with conformal multilayer-structure can be obtained. The BET specific surface area and pore volume of powders were increased dramatically because of the derivation of abundant voids, which can not only buffer the swelling effect of silicon, but also provide richer ionic conductivity. The as-assembled half-cell with Si@SiOx@void@C as the anode material possesses high capacity (∼1000 mAh g−1 at 3 A g−1), long cycle life (300 cycles with 77% capacity retention) and good rate performance (558 mAh g−1 at 5 A g−1).

Hierarchical architectures of Ag clusters deposited biomimetic membrane: Synthesis, emulsion separation, catalytic and antibacterial performance

The synthesis of high-performance materials for purifying oily wastewater, especially stable oil-in-water emulsions that aromatic pollutants present in water, is of growing scientific and technological significance. Novel hierarchical architectures of Ag clusters deposited biomimetic membrane have been synthesized by ingeniously selecting the mussel-inspired polydopamine coatings as an intermedium layer followed by a facile wet chemical reduction method. The target micro-scaled Ag clusters which are composed of innumerable nanoparticles, firmly load on the surface of sub-micrometer polydopamine spheres (PDSs) benefiting from the chelating capacity and benign reduction ability of PDSs. The resultant Ag@PDSs deposited membrane with enormous specific surface area exhibits superhydrophilicity and underwater superoleophobicity, making it highly promising for efficient separation of various surfactant-stabilized oil-in-water emulsions and synchronously excellent catalytic reduction of water-soluble aromatic dyes. Moreover, such a construction mode can effectively prevent the aggregation and possible leaching of Ag particles, which greatly contributes to the outstanding cyclic performance and good antibacterial activity. All these features demonstrate that the two-step strategy is a facile approach to design and exploit the deposited Ag@PDSs composites for diverse actual applications in oil/water emulsion separation, catalysis and antibacterial agent.

Epithelial Cdc42 Deletion Induced Enamel Organ Defects and Cystogenesis

Cdc42, a Rho family small GTPase, regulates cytoskeleton organization, vesicle trafficking, and other cellular processes in development and homeostasis. However, Cdc42’s roles in prenatal tooth development remain elusive. Here, we investigated Cdc42 functions in mouse enamel organ. Cdc42 showed highly dynamic temporospatial patterns in the developing enamel organ, with robust expression in the outer enamel epithelium, stellate reticulum (SR), and stratum intermedium layers. Strikingly, epithelium-specific Cdc42 deletion resulted in cystic lesions in the enamel organ. Cystic lesions were first noted at embryonic day 15.5 and progressively enlarged during gestation. At birth, cystic lesions occupied the bulk of the entire enamel organ, with intracystic erythrocyte accumulation. Ameloblast differentiation was retarded upon epithelial Cdc42 deletion. Apoptosis occurred in the Cdc42 mutant enamel organ prior to and synchronously with cystogenesis. Transmission electron microscopy examination showed disrupted actin assemblies, aberrant desmosomes, and significantly fewer cell junctions in the SR cells of Cdc42 mutants than littermate controls. Autophagosomes were present in the SR cells of Cdc42 mutants relative to the virtual absence of autophagosome in the SR cells of littermate controls. Epithelium-specific Cdc42 deletion attenuated Wnt/β-catenin and Shh signaling in dental epithelium and induced aberrant Sox2 expression in the secondary enamel knot. These findings suggest that excessive cell death and disrupted cell-cell connections may be among multiple factors responsible for the observed cystic lesions in Cdc42 mutant enamel organs. Taken together, Cdc42 exerts multidimensional and pivotal roles in enamel organ development and is particularly required for cell survival and tooth morphogenesis.

Maxillary Calcifying Epithelial Odontogenic Tumor Presenting at a Postextraction Site: A Case Report and Brief Review of Literature

Calcifying epithelial odontogenic tumor (CEOT) was described as an entity by Danish pathologist Jens J. Pindborg in 1955. It is a rare benign odontogenic neoplasm forming 0.4–3.0% of all intraosseous tumors. Also known as Pindborg tumor, it is traditionally described as an uncommon, benign neoplasm of exclusively epithelial tissue of origin. Much of controversy exists in the nature of origin of this tumor; there is no consensus on the originating cells of CEOT. Some pathologists suggest that it is derived from stratum intermedium layer of enamel organ in the tooth development stage; others favor a different hypothesis in which this tumor may arise from the remnants of primitive dental lamina in the initial stages of odontogenesis. Most of the cases reported involve the posterior mandible than the maxilla in the ratio of 3:1. The mean age is 30–40 years with no gender predilection. The present case throws highlight on the unusual site of the lesion, i.e. presenting in the maxillary molar region as an ulcerated area in the area of extraction socket. The study also attempts to briefly emphasize the concepts of CEOT and also revives the review of literature.

Tooth development in a model reptile: functional and null generation teeth in the gecko Paroedura picta.

This paper describes tooth development in a basal squamate, Paroedura picta. Due to its reproductive strategy, mode of development and position within the reptiles, this gecko represents an excellent model organism for the study of reptile development. Here we document the dental pattern and development of non-functional (null generation) and functional generations of teeth during embryonic development. Tooth development is followed from initiation to cytodifferentiation and ankylosis, as the tooth germs develop from bud, through cap to bell stages. The fate of the single generation of non-functional (null generation) teeth is shown to be variable, with some teeth being expelled from the oral cavity, while others are incorporated into the functional bone and teeth, or are absorbed. Fate appears to depend on the initiation site within the oral cavity, with the first null generation teeth forming before formation of the dental lamina. We show evidence for a stratum intermedium layer in the enamel epithelium of functional teeth and show that the bicuspid shape of the teeth is created by asymmetrical deposition of enamel, and not by folding of the inner dental epithelium as observed in mammals.

Bending behavior of FGM-coated and FGM-undercoated plates with two simply supported opposite edges and two free edges

Abstract This investigation analyzes laminated plates with two simply supported opposite edges and two free edges subjected to transverse loads. Two situations are considered. The first involves a two-layer plate in which an FGM layer is coated on a homogeneous substrate, simply called an FGM-coated plate; the other involves a three-layer plate in which an FGM is employed for the inter-medium layer and different homogeneous materials are in the top and bottom layers; this is called an FGM-undercoated plate. The Young’s modulus of FGM plates is assumed to vary in the thickness direction and the Poisson’s ratio to remain constant throughout the FGM plate. The material gradations in FGM portion of the laminate structures follow sigmoid functions. Even though the FGM-coated or undercoated plates are formed from composite materials, the bending and in-plane problems in these FGM plates with constant Poisson’s ratio and varying Young’s modulus in the thickness direction under transverse loads only are uncoupled. For the multi-layer structures of interest, the calculations of the quantities, A 11 , B 11 , C 11 , Q 11 , S 11 , defined herein become very complex. Therefore this study proposes an alternative approach for easily and efficiently calculating them. The results reveal that the analytical solution to the bending problem of FGM plates obtained using a Fourier series expanding is strongly consistent with the finite element calculation. The deflections, strains, and stresses of FGM-coated and undercoated plates are evaluated and under discussion. The differences between the flexibility behaviors of FGM-coated and undercoated plates are investigated.

Sonic Hedgehog Functions as a Mitogen During Bell Stage of Odontogenesis

Epithelial-mesenchymal interactions are required for tissue growth and gene expression patterns during odontogenesis. We showed previously that Sonic hedgehog (SHH) is detectable in both dental epithelium and mesenchyme, while Shh transcripts are present in dental epithelium only, suggesting that SHH functions as an autocrine signal in epithelium and a paracrine signal in mesenchyme. This hypothesis was tested here. We found by in situ hybridization that the SHH autocrine receptor Ptch-2 is indeed expressed in dental epithelium whereas the paracrine receptor Ptc is expressed in mesenchyme. Bovine bell stage tooth germs were microsurgically separated into epithelial and mesenchymal portions and the resulting tissue fragments were organ-cultured. In epithelium fragments cultured by themselves, gene expression of Shh and Gli-1 (a putative transcriptional mediator of hedgehog signaling) was significantly decreased in both inner dental epithelium and stratum intermedium layers; this was accompanied by a sharp drop in epithelial cell proliferation. However, in companion control tissue fragments containing both epithelium and mesenchyme, Shh and Gli-1 expression as well as cell proliferation were maintained. Treatment of dental epithelial or mesenchymal cell populations in monolayer cultures with exogenous recombinant SHH stimulated cell proliferation. Together, the data provide clear evidence that Shh is synthesized by dental epithelium, reaches the underlying mesenchyme, and appears to act as an autocrine mitogen for epithelial cells and a paracrine mitogen for mesenchymal cells, thus exerting crucial functions in tooth germ growth, morphogenesis, and tissue-tissue interactions of bell stage of odontogenesis.

Sonic Hedgehog Functions as a Mitogen During Bell Stage of Odontogenesis

Epithelial-mesenchymal interactions are required for tissue growth and gene expression patterns during odontogenesis. We showed previously that Sonic hedgehog (SHH) is detectable in both dental epithelium and mesenchyme, while Shh transcripts are present in dental epithelium only, suggesting that SHH functions as an autocrine signal in epithelium and a paracrine signal in mesenchyme. This hypothesis was tested here. We found by in situ hybridization that the SHH autocrine receptor Ptch-2 is indeed expressed in dental epithelium whereas the paracrine receptor Ptc is expressed in mesenchyme. Bovine bell stage tooth germs were microsurgically separated into epithelial and mesenchymal portions and the resulting tissue fragments were organ-cultured. In epithelium fragments cultured by themselves, gene expression of Shh and Gli-1 (a putative transcriptional mediator of hedgehog signaling) was significantly decreased in both inner dental epithelium and stratum intermedium layers; this was accompanied by a sharp drop in epithelial cell proliferation. However, in companion control tissue fragments containing both epithelium and mesenchyme, Shh and Gli-1 expression as well as cell proliferation were maintained. Treatment of dental epithelial or mesenchymal cell populations in monolayer cultures with exogenous recombinant SHH stimulated cell proliferation. Together, the data provide clear evidence that Shh is synthesized by dental epithelium, reaches the underlying mesenchyme, and appears to act as an autocrine mitogen for epithelial cells and a paracrine mitogen for mesenchymal cells, thus exerting crucial functions in tooth germ growth, morphogenesis, and tissue-tissue interactions of bell stage of odontogenesis.

Flexible metal film with micro- and nanopatterns transferred by electrochemical deposition

A new method for patterning microstructure on metal film by electrochemical deposition is provided. The metal film with micropattern can be peeled off after the deposition by inter-medium layer of resistant molecules such as triglyceride. We can use the technology of electrochemical deposition to make the metal film possess different functions such as soft and bendable properties. We also give an example to get the protein pattern transferred on the metal film. So, this method can also provide a way for the fabrication of protein pattern on the chip.

Histologic and electron microscopic characterization of the antiperinuclear factor antigen

The presence of the antiperinuclear factor, an autoantibody that recognizes cytoplasmic antigens, was detected in sera from patients with rheumatoid arthritis (59%), seronegative rheumatoid arthritis (36%), systemic lupus erythematosus (46%), systemic sclerosis (26%), and in nonautoimmune controls (10%). The antigenic perinuclear granules were found in the stratum intermedium layer of the buccal mucosa. Granules exhibited histologic features of nucleoproteins, stained for ribonucleoprotein, and showed the ultrastructural characteristics of aggregated rough endoplasmic reticulum. The antiperinuclear factor may recognize a common autoantigen in connective tissue disease.

Succinate dehydrogenase activity in the developing molar of the Mongolian gerbil Meriones unguiculatus.

The distribution of succinate dehydrogenase in the odontogenic tissues in the Mongolian gerbil, ranging in age from 18 days prenatal to 8 days postnatal, was studied. Activity levels were designated negative, trace, slight, moderate, strong and very, dependent upon visual observations. The results indicated increased levels of activity as the tissue layers differentiated from the lamina stage through early apposition. The cell layer displaying the most succinate dehydrogenase activity was the ameloblastic layer while the stratum intermedium layer was the next most active cell layer. Succinate dehydrogenase activity appeared to be related to the degree of differentiation and functional competency of the odontogenic tissues in the Mongolian gerbil.