Dissimilar Substrates Research Articles

Excitation of resonances in planar metamaterials at a two-layer dielectric interface for substrate integrated electronics

We theoretically investigate the origin of resonance excitation in planar metamaterials placed longitudinally at the boundary of a two-layer dissimilar dielectric substrate integrated waveguide, as an approximation of integrated circuit electronics. The two-layer filled waveguide leads to the generation of longitudinal section modes with a non-zero orientation of E field along the propagation direction that contributes to the resonance current induction in the gap of metamaterial resonators. By implementing materials with different combinations of dielectric constants and thicknesses, precise control of the frequency and intensity of metamaterial resonance is achieved. The presented work has huge potential to replace existing complex technologies in integrated electronics at millimeter-wave frequencies and to promote new substrate integrated metamaterial applications, such as absorbers, phase shifters, and attenuators, for future wireless communication networks.

Effects of low-energy impact at different temperatures on residual properties of adhesively bonded single-lap joints with composites substrates

This paper evaluates the influence of temperature, stiffness combination and impact energy on residual tensile properties of adhesive single-lap joints (SLJs) with composite substrates. High-strength steel (HSS), glass and carbon fiber reinforced plastics (GFRP and CFRP) were chosen as adherends, while Araldite® 2015 was the adhesive. The effects of four temperatures (−40, 23, 50 and 80 °C) were taken into account for the transverse impact loading with three different energy levels of 0.5, 1.5 and 2.5 J. Residual behavior and failure modes were investigated through secondary tensile tests at ambient temperature. The results indicate that impact energy and temperature both have a strong correlation with residual static properties. The degradation of mechanical strength, induced by the combined effect of low-energy impact loading and temperature, is particularly pertinent for the joints with dissimilar substrates. Furthermore, increasing the relative stiffness ratio can enhance the residual tensile strength of the SLJs with composites.

A Novel Approach to Friction Surfacing: Experimental Analysis of Deposition from Radial Surface of a Consumable Tool

The friction surfacing technique is an advanced method for creating coatings of various materials onto the surface of a similar or dissimilar material substrate. In this method, there is no external source of heat energy, and all the heat energy required in this method is generated by friction. In this paper, a novel method of friction surfacing from the side of the consumable tool is introduced. The most significant difference in this technique is that material transfer will occur from the radial surface of the consumable tool as opposed to the end of the tool as in conventional friction surfacing. In lateral friction surfacing, the side of the rotating consumable tool is pressed against the substrate surface, which generates frictional heating and shear forces at the interface between tool and substrate. A layer of tool material is transferred from the consumable rod to the substrate surface as the tool moves across. In this study, 6063 aluminum alloy and AISI 1018 carbon steel are used as the materials of consumable tool and substrate, respectively. The impact of process factors, surface roughness values, tool mass loss, and deposition thickness are discussed in detail. The experimental results of this study reveal that lateral friction surfacing produces a very smooth ultra-thin deposition with full coverage, with coating layers with roughness values in the order of 1 µm. Additionally, there is no flash formed in this technique which reduces material consumption. Moreover, temperatures at the interface between the consumable tool and workpiece were measured to be lower than for that in friction surfacing from the end of the tool, which is beneficial for the metallurgical characteristics of the deposited material.

Brazing of porous Si3N4 ceramic to Invar alloy with a novel Cu–Ti filler alloy: Microstructure and mechanical properties

Porous Si3N4 (P–Si3N4) ceramic was successfully joined to Invar alloy using a Cu–Ti active brazing alloy for the first time. The interfacial reactions between the Cu–Ti filler and two dissimilar substrates were studied. The influence of brazing process on the microstructure evolution of the joint was revealed, along with the formation of an infiltration layer that permitted the bonding of P–Si3N4 substrate. Ti reacted with Si3N4 to form TiN and Ti5Si3 compounds, resulting in the decomposition of Si3N4. In addition, the reaction and diffusion dual-layer formed at the Cu–Ti/Invar interface, which was attributed to the interaction of alloy elements between the braze filler and the Invar alloy. Fe–Ti and Ni–Ti intermetallics together with Cu solid solution (s,s) constituted the microstructure of the brazing seam. In addition, the optimal shear strength of the brazed joint was 20 MPa and the fracture propagation occurred in the P–Si3N4 ceramic substrate adjacent to the infiltration layer during the shearing tests.

The Multidrug Transporter MdfA Deviates from the Canonical Model of Alternating Access of MFS Transporters

The prototypic multidrug (Mdr) transporter MdfA from Escherichia coli efflux chemically‐ dissimilar substrates in exchange for protons. Similar to other transporters, MdfA purportedly functions by alternating access of a central substrate binding pocket to either side of the membrane. Accordingly, MdfA should open at the cytoplasmic side and/or laterally toward the membrane to enable access of drugs into its pocket. At the end of the cycle, the periplasmic side is expected to open to release drugs. Two distinct conformations of MdfA have been captured by X-ray crystallography: An outward open (Oo) conformation, stabilized by a Fab fragment, and a ligand-bound inward-facing (If) conformation, possibly stabilized by a mutation (Q131R). Here, we investigated how these structures relate to ligand-dependent conformational dynamics of MdfA in lipid bilayers. For this purpose, we combined distances measured by double electron-electron resonance (DEER) between pairs of spin labels in MdfA, reconstituted in nanodiscs, with cysteine cross-linking of natively expressed membrane-embedded MdfA variants. Our results suggest that in a membrane environment, MdfA assumes a relatively flexible, outward-closed/inward-closed (Oc/Ic) conformation. Unexpectedly, our data show that neither the substrate TPP nor protonation induces large-scale conformational changes. Rather, we identified a substrate-responsive lateral gate, which is open toward the inner leaflet of the membrane but closes upon drug binding. Together, our results suggest a modified model for the functional conformational cycle of MdfA that does not invoke canonical elements of alternating access.

3D printable tough silicone double networks

Additive manufacturing permits innovative soft device architectures with micron resolution. The processing requirements, however, restrict the available materials, and joining chemically dissimilar components remains a challenge. Here we report silicone double networks (SilDNs) that participate in orthogonal crosslinking mechanisms—photocurable thiol-ene reactions and condensation reactions—to exercise independent control over both the shape forming process (3D printing) and final mechanical properties. SilDNs simultaneously possess low elastic modulus (E100% < 700kPa) as well as large ultimate strains (dL/L0 up to ~ 400 %), toughnesses (U ~ 1.4 MJ·m−3), and strengths (σ ~ 1 MPa). Importantly, the latent condensation reaction permits cohesive bonding of printed objects to dissimilar substrates with modulus gradients that span more than seven orders of magnitude. We demonstrate soft devices relevant to a broad range of disciplines: models that simulate the geometries and mechanical properties of soft tissue systems and multimaterial assemblies for next generation wearable devices and robotics.

Multidrug transporters: recent insights from cryo-electron microscopy-derived atomic structures and animal models.

P-glycoprotein, ABCG2, and MRP1 are members of the ATP-binding cassette (ABC) transporter superfamily that utilize energy from ATP-binding and hydrolysis to efflux a broad range of chemically dissimilar substrates including anticancer drugs. As a consequence, they play an important role in the pharmacokinetics and bioavailability of many drugs; in particular, their role in multidrug resistance in cancer cells as well as at the blood–brain barrier has been the subject of studies for decades. However, the atomic structures of these transporters in the presence of substrates or modulators and at different stages of the ATP-hydrolysis cycle have only recently been resolved by using cryo-electron microscopy. In addition, new animal models have shed new light on our understanding of the role of these transporters at the blood–brain barrier. This new information should open doors for the design of novel chemotherapeutics and treatments to bypass recognition by ABC drug pumps to overcome clinical drug resistance. In this review, we discuss the most recent advances in our understanding of ligand interactions and mechanistic aspects of drug transport based on atomic structures of these transporters as well as the development of new in vivo models to study their role in clinical drug resistance in cancer.

Magnetic phase profile in La0.7Ca0.3MnO3/Pr0.58Ca0.42MnO3 superlattices: Role of substrate inherent disorders

We report the impact of dissimilar substrate inherent twinning over the structural, electrical and magnetic properties of otherwise identical ferromagnetic/antiferromagnetic La0.7Ca0.3MnO3/Pr0.58Ca0.42MnO3 (LCMO/PCMO) superlattices (SLs). 12 layers of LCMO and PCMO each ~11 nm thick were deposited and then LCMO was deposited as the top layer. The SLs were fabricated by RF magnetron sputtering method over three LaAlO3 (0 0 1) substrates embodied with different twinning disorders. Structural analysis employing high resolution X-ray diffraction (HRXRD; 2θ, ω, and ϕ scans) demonstrates that substrate twin structures exactly get imprinted over all the superlattice peaks. Transport and magnetization measurements showed coupled insulator-metal (IM)/paramagnetic-ferromagnetic (PM-FM) transition around 220 K in all the three SLs. In the high temperature PM region all the samples behave similarly however at low temperatures where long-range ferromagnetic metal (FMM) and antiferromagnetic insulating (AFMI) phases start emerging in LCMO and PCMO respectively, SLs show deviant behaviors. This is ascribed to the substrate originated microstructural disorders in SLs which are distinct for all the samples and hence perturb FMM/AFMI interfacial interactions differently. Samples with prominently large substrate FWHM = 0.683° and 0.959° respectively show a second but weak IM transition and a strong hysteretic IM transition behavior. Magnetization displays a hysteretic behavior in field cooled data measured during cooling and warming cycles. The hysteresis gets stronger with the rise in FWHM which signifies an enhancement of phase competition between FMM and AFMI phases at the interfaces. This behavior of LCMO/PCMO SLs is attributed to the interfacial exchange interactions lead magnetic reconstruction at the interfaces.

Fatigue performance of single lap joints with CFRP and aluminium substrates prior and after hygrothermal aging

AbstractAdhesive bonding has been extensively used to join composites and aluminium alloys in the automotive industry, but a deeper understanding of its fatigue behaviour is still required. This work presents a novel evaluation of the combined performance of joints manufactured with carbon fibre reinforced plastic (CFRP) and aluminium substrates subjected to fatigue loads in the unaged, hygrothermally aged, and dried after hygrothermal aging states. The experimental results allowed to conclude that the fatigue performance of joints can be affected by changes induced by the drying process or losses in the interface strength and that dissimilar combination of substrates sustains higher number of cycles to failure. The fatigue performance of joints with dissimilar substrates was found to be better than that of joints with similar substrates, which can be attributed to the lower stresses acting on the adhesive layer. The presence of water has also noticeably changed the fatigue performance of joints with dissimilar substrates.

Fabrication and thermal behavior of Al/Fe2O3 energetic composites for effective interfacial bonding between dissimilar metallic substrates

Herein, the roles of an Al/Fe2O3 energetic composites as a heat energy source and a bonding medium for interfacially bonding dissimilar Al/Cu metallic substrates are systematically investigated. Energetic material (EM)/solder material (SM) bilayer pellets are assembled and ignited between the interfacial Al/Cu substrates for bonding. The upper EM layer comprising an Al microparticle (MP)/Al nanoparticle (NP)/Fe2O3 NP composite serves as a heat source for melting the lower SM layer comprising SAC305 MP for strongly bonding the Cu substrate with the melted SM layer. The intermetallic compounds (AlxFey) formed during the aluminothermic reactions of the ignited EM layer play an important role as a bonding medium between the Al substrate and the melted EM layer. The dissimilar Al/Cu substrates are interfacially bonded using an EM layer with a fuel-to-oxidizer ratio of 1.97–4.44. The maximum mechanical strength of the bonded Al/Cu substrates increases with the increase in the fuel-to-oxidizer ratio owing to the supply of sufficient heat energy under fuel-rich conditions. The EM layer acts as an effective heat energy source and mechanical bonding medium. The proposed interfacial bonding technique is simple, easy, and versatile for welding and joining dissimilar metallic substrates for industrial applications.

Scaling growth rates for perovskite oxide virtual substrates on silicon

The availability of native substrates is a cornerstone in the development of microelectronic technologies relying on epitaxial films. If native substrates are not available, virtual substrates - crystalline buffer layers epitaxially grown on a structurally dissimilar substrate - offer a solution. Realizing commercially viable virtual substrates requires the growth of high-quality films at high growth rates for large-scale production. We report the stoichiometric growth of SrTiO3 exceeding 600 nm hr−1. This tenfold increase in growth rate compared to SrTiO3 grown on silicon by conventional methods is enabled by a self-regulated growth window accessible in hybrid molecular beam epitaxy. Overcoming the materials integration challenge for complex oxides on silicon using virtual substrates opens a path to develop new electronic devices in the More than Moore era and silicon integrated quantum computation hardware.

Comparative Characterization of the Atlantic salmon, Salmo salar L., Di/Tripeptide Transporters PepT1a and PepT1b

Amino acids and small peptides in the form of di/tripeptides are key nutrients in animal diets and essential contributors to growth. In mammals, di/tripeptides represent a highly significant fraction of dietary protein after digestion and are transported across the brush‐border membrane of the intestinal epithelium via a single transport protein, the Peptide Transporter 1 (PepT1), a member of the Solute Carrier 15 (Slc15) family. PepT1 is a low‐affinity/high‐capacity transporter that uses an inwardly‐directed proton electrochemical gradient to drive the uptake of di/tripeptides, and peptidomimetics, across the cell membrane. However, in teleost fishes two pept1 genes, namely pept1b and pept1a, have been identified. PepT1b has been studied in many teleost species, including the Atlantic (A.) salmon (Salmo salar L.), whereas PepT1a remain unexplored. The aim of our study was to characterize, the A. salmon PepT1a vs. PepT1b in terms of tissue/organ distribution and function, and possibly extrapolate their physiological role(s).Despite the extra (4th) whole genome duplication (WGD) in the Actinopterygian lineage, A. salmon has only two pept1 genes (namely pept1a and pept1b), like in other telosts that didn't undergo the extra WGD, e.g., the zebrafish (Danio rerio). At the amino acid level, the two paralogues share 77% similarity, 64% identity. Tissue distribution and relative abundance of A. salmon pept1a and pept1b revealed that both transcripts have a similar expression profile. A. salmon pept1a is highly expressed in the proximal intestine (pyloric caeca ≈ anterior midgut &gt; midgut &gt;&gt; posterior midgut), but ~5‐fold less than pept1b, which is expressed in the same gut regions. No expression signals were detected in the anterior and posterior stomach or the anterior and posterior hindgut.As assessed by heterologous expression in Xenopus laevis oocytes and Two‐Electrode Voltage Clamp measurements, A. salmon PepT1a is, like PepT1b, a low‐affinity/high‐capacity system, able to sustain an electrogenic, sodium‐independent and pH‐dependent transport of di/tripeptides. Transport associated currents show that the protein exhibits a K0.5 value for the reference dipeptide Gly‐Gln of 0.5 mM at pH 7.6 and of 0.07 mM at pH 6.5.The pre‐steady state and steady‐state transport currents analysis indicate important functional differences between A. salmon PepT1a and PepT1b transporters. The difference in expression levels and a significantly dissimilar substrate specificity for certain di/tripeptides, such as lysine‐containing peptides, supports the idea of distinct roles in peptide recognition and transport for PepT1a and PepT1b.Support or Funding InformationFunded by RFFV; 247978 SalmoFeedPlus and CargillThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Evaluation of Electromagnetic Field Data of a Designed Microstrip Patch Antenna Structure According to Type of Substrate Materials and Their Thicknesses

Abstract Substrate material used in microstrip antenna structures fully impact the performance of antenna and applications of it. In this work, simulations are carried out for microstrip antenna structure used in biomedical applications. Heart vessel structure used for determining heart diseases is modelled in Ansoft HFSS program. Simulations are implemented with and without occlusion in heart vein. Antenna structure is simulated with different substrate materials and different thicknesses of them. After simulations, various electromagnetic field data are obtained and evaluated for dissimilar substrate materials and thickness of them.

Microbial Fuel Cell: A Renewable Equipment for Bio-Power Production and Simultaneous Treatment of Industrial Wastewaters

Purpose of microbial Fuel Cells (MFCs) might symbolize a completely new come near to waste substance behaviour with construction of possessions clean energy. In recent years, researchers have shown that MFCs is wont to turn out electricity from water containing totally dissimilar substrates. Studies on electricity generation from the wastewater as substrate are in development. In this paper the first stage of investigational path, leather effluent and sewage wastewater was used without any mediator and in the second stage leather effluent and sewage wastewater was used methylene blue as a mediator. Performance of the MFCs as reported with different wastewater with mediator and without mediator is presented. The Microbial fuel cell equipment represents a substitute type of power in which wastewater are utilized for power construction. In this experiment we used sewage water, Cow manure, Effluent water, and rice washing water operated for 5 days and successfully generated a maximum power of 482(mV), which is adequate to control small power devices. It is a less expensive cooperative and a substitute basis of energy which will be adopted for the prospect. If power production in MFC can be enlarged this tools may provide a innovative scheme to compensate wastewater management plant in use costs, with less unnecessary sludge fabrication.

A strategy to identify a ketoreductase that preferentially synthesizes pharmaceutically relevant (S)-alcohols using whole-cell biotransformation

IntroductionChemical industries are constantly in search of an expeditious and environmentally benign method for producing chiral synthons. Ketoreductases have been used as catalysts for enantioselective conversion of desired prochiral ketones to their corresponding alcohol. We chose reported promiscuous ketoreductases belonging to different protein families and expressed them in E. coli to evaluate their ability as whole-cell catalysts for obtaining chiral alcohol intermediates of pharmaceutical importance. Apart from establishing a method to produce high value (S)-specific alcohols that have not been evaluated before, we propose an in silico analysis procedure to predict product chirality.ResultsSix enzymes originating from Sulfolobus sulfotaricus, Zygosaccharomyces rouxii, Hansenula polymorpha, Corynebacterium sp. ST-10, Synechococcus sp. PCC 7942 and Bacillus sp. ECU0013 with reported efficient activity for dissimilar substrates are compared here to arrive at an optimal enzyme for the method. Whole–cell catalysis of ketone intermediates for drugs like Aprepitant, Sitagliptin and Dolastatin using E. coli over-expressing these enzymes yielded (S)-specific chiral alcohols. We explain this chiral specificity for the best-performing enzyme, i.e., Z. rouxii ketoreductase using in silico modelling and MD simulations. This rationale was applied to five additional ketones that are used in the synthesis of Crizotinib, MA-20565 (an antifungal agent), Sulopenem, Rivastigmine, Talampanel and Barnidipine and predicted the yield of (S) enantiomers. Experimental evaluation matched the in silico analysis wherein ~ 95% (S)-specific alcohol with a chemical yield of 23–79% was obtained through biotransformation. Further, the cofactor re-cycling was optimized by switching the carbon source from glucose to sorbitol that improved the chemical yield to 85–99%.ConclusionsHere, we present a strategy to synthesize pharmaceutically relevant chiral alcohols by ketoreductases using a cofactor balanced whole-cell catalysis scheme that is useful for the industry. Based on the results obtained in these trials, Zygosaccharomyces rouxii ketoreductase was identified as a proficient enzyme to obtain (S)-specific alcohols from their respective ketones. The whole–cell catalyst when combined with nutrient modulation of using sorbitol as a carbon source helped obtain high enantiomeric and chemical yield.

Bacterial Multidrug Efflux Proteins: A Major Mechanism of Antimicrobial Resistance

Antimicrobial resistance is a global challenge, for which the mechanisms of resistance are varied and complicated. Bacterial multidrug efflux proteins are a major mechanism of antimicrobial resistance and therefore, targets for drug development. Gram-negative bacteria are intrinsically more resistant to many antibiotics and biocides due to their cell structure and the activity of multidrug efflux proteins. These transporters actively extrude antibiotics and other xenobiotics from the cytoplasm or surrounding membranes of cells to the external environment. Based on amino acid sequence similarity, substrate specificity and the energy source used to export their substrates, there are seven major families of distinct bacterial multidrug efflux proteins: ABC, RND, MFS, SMR, MATE, PACE, AbgT. Individual proteins may be highly specialised for one compound or highly promiscuous, transporting a broad range of structurally dissimilar substrates. Protein structural organisation in a large majority of the families, including the number of transmembrane helices, has been confirmed by highresolution structure determination for at least one member. In this paper, we review the families of bacterial multidrug efflux proteins, including basic properties, energisation, structural organisation and molecular mechanism. Using representative proteins from each family, we also performed analyses of transmembrane helices, amino acid composition and distribution of charged residues. Ongoing characterisation of structure-function relationships and regulation of bacterial multidrug efflux proteins are necessary for contributing new knowledge to assist drug development and strategies that will overcome antimicrobial resistance.

Adhesive joints using aluminium and CFRP substrates tested at low and high temperatures under quasi-static and impact conditions for the automotive industry

The use of adhesives to bond metallic and composite structural components has increased substantially over the last decades. The aim of this work is to understand and predict the behaviour of dissimilar adhesive joints, using composite and aluminium substrates, under quasi-static and impact loads. Several testing temperatures (−30 to 80 °C) were considered, following the requirements for the automotive industry. It was possible to conclude that dissimilar adhesive joints, if used in conjunction with modern crash resistant adhesives, can effectively be used for the construction of automotive structures, without significant sacrifices in joint performance, with good energy absorption capabilities under impact.

Circumventing the miscibility gap in InGaN nanowires emitting from blue to red

Widegap III-nitride alloys have enabled new classes of optoelectronic devices including light emitting diodes, lasers and solar cells, but it is admittedly challenging to extend their operating wavelength to the yellow–red band. This requires an increased In content x in InxGa1−xN, prevented by the indium segregation within the miscibility gap. Beyond the known advantage of dislocation-free growth on dissimilar substrates, nanowires may help to extend the compositional range of InGaN. However, the necessary control over the material homogeneity is still lacking. Here, we present InxGa1−xN nanowires grown by hydride vapor phase epitaxy on silicon substrates, showing rather homogeneous compositions and emitting from blue to red. The InN fraction in nanowires is tuned from x = 0.17 up to x = 0.7 by changing the growth temperature between 630 °C and 680 °C and adjusting some additional parameters. A dedicated model is presented, which attributes the wide compositional range of nanowires to the purely kinetic growth regime of self-catalyzed InGaN nanowires without macroscopic nucleation. These results may pave a new way for the controlled synthesis of indium-rich InGaN structures for optoelectronic applications in the extended spectral range.

Above bandgap thermoreflectance for non-invasive thermal characterization of GaN-based wafers

GaN devices integrated with dissimilar substrates have transformed electronic and optoelectronic applications. However, an effective thermal resistance (TBReff) exists between the GaN layer and the dissimilar substrates typically, which can potentially cause a major heat transport bottleneck. A non-invasive method for monitoring the TBReff of bare wafers is a key enabler for process monitoring and for the reduction of TBReff through design optimization. The existing TBReff measurement techniques require metal deposition on the sample surface. Here, we demonstrate a generic non-invasive transient thermoreflectance technique which does not require modification of the GaN surface and can be applied to any GaN-based wafers, regardless of the substrate material. Above-bandgap pump and probe lasers are used to avoid any interference caused by sub-surface reflections, ensuring that this technique strictly follows the fundamental principle of thermoreflectance-based methods. Several GaN wafers on common substrates (SiC, Si, diamond, and sapphire) are measured to assess the validity of this technique.

Study of mass transport in cold wire deposition for Wire Arc Additive Manufacturing

Wire Arc Additive Manufacturing (WAAM) is a combination of an electric arc and wire feeding system used extensively in building components and repair operations. The heat transfer, fluid flow and mass transport were investigated in a numerical simulation of WAAM process with dissimilar substrate. Experiments were performed to verify the numerical results. The predicted clad layer (1st layer) profile (width and height) is in good agreement with experiment. The cold wire transfer (CWT) impact on the velocity field and mass transport were predicted around the cold wire immersion inlet in the weld pool (WP). The effect of arc travel speed and wire feed rate on the homogenization process were studied. Both the numerical and experimental results show that the increase of wire feed rate leads to homogenous composition in fusion zone (FZ). The predicted composition distribution in the clad layer and measured concentrations in experiments show a well-mixed region in middle of the clad layer.