Gross morphology and adhesion-associated physical properties of Drosophila larval salivary gland glue secretion.

One of the major functions of the larval salivary glands (SGs) of many Drosophila species is to produce a massive secretion during puparium formation. This so-called proteinaceous glue is exocytosed into the centrally located lumen, and subsequently expectorated, serving as an adhesive to attach the puparial case to a solid substrate during metamorphosis. Although this was first described almost 70 years ago, a detailed description of the morphology and mechanical properties of the glue is largely missing. Its main known physical property is that it is released as a watery liquid that quickly hardens into a solid cement. Here, we provide a detailed morphological and topological analysis of the solidified glue. We demonstrated that it forms a distinctive enamel-like plaque that is composed of a central fingerprint surrounded by a cascade of laterally layered terraces. The solidifying glue rapidly produces crystals of KCl on these alluvial-like terraces. Since the properties of the glue affect the adhesion of the puparium to its substrate, and so can influence the success of metamorphosis, we evaluated over 80 different materials for their ability to adhere to the glue to determine which properties favor strong adhesion. We found that the alkaline Sgs-glue adheres strongly to wettable and positively charged surfaces but not to neutral or negatively charged and hydrophobic surfaces. Puparia formed on unfavored materials can be removed easily without leaving fingerprints or cascading terraces. For successful adhesion of the Sgs-glue, the material surface must display a specific type of triboelectric charge. Interestingly, the expectorated glue can move upwards against gravity on the surface of freshly formed puparia via specific, unique and novel anatomical structures present in the puparial's lateral abdominal segments that we have named bidentia.

Negative Charge-Carrying Glycans Attached to Exosomes as Novel Liquid Biopsy Marker.

Prostate cancer (PCa) is the second most common cancer. In this paper, the isolation and properties of exosomes as potential novel liquid biopsy markers for early PCa liquid biopsy diagnosis are investigated using two prostate human cell lines, i.e., benign (control) cell line RWPE1 and carcinoma cell line 22Rv1. Exosomes produced by both cell lines are characterised by various methods including nanoparticle-tracking analysis, dynamic light scattering, scanning electron microscopy and atomic force microscopy. In addition, surface plasmon resonance (SPR) is used to study three different receptors on the exosomal surface (CD63, CD81 and prostate-specific membrane antigen-PMSA), implementing monoclonal antibodies and identifying the type of glycans present on the surface of exosomes using lectins (glycan-recognising proteins). Electrochemical analysis is used to understand the interfacial properties of exosomes. The results indicate that cancerous exosomes are smaller, are produced at higher concentrations, and exhibit more nega tive zeta potential than the control exosomes. The SPR experiments confirm that negatively charged α-2,3- and α-2,6-sialic acid-containing glycans are found in greater abundance on carcinoma exosomes, whereas bisecting and branched glycans are more abundant in the control exosomes. The SPR results also show that a sandwich antibody/exosomes/lectins configuration could be constructed for effective glycoprofiling of exosomes as a novel liquid biopsy marker.

Hybrid solder joints: the effect of nanosized ZrO2 particles on morphology of as-reflowed and thermally aged Sn-3.5Ag solder joints.

The main number of current researches has been focused on the microstructure and mechanical properties of the Sn-based Sn-Ag-Cu-based solders, while various kinds of nanosized particles have been added. The synthesis and handling of ceramic nanosized powder are much easier than of metal nanoparticles. In addition, metal nanoparticles solved in solder joints during the soldering process or by thermal aging could behave as an alloying element similar to bulk metal additions, while ceramic nanoparticles retain their chemically inactive behavior in various thermal, thermo-mechanical, and electrical constraints. In some cases, the solved metal nanosized inclusions could increase the growth kinetics of the present intermetallic phases or even create new phases, which leads to more complexity in the predictions and simulations of chemical processes in the solder joints. Based on the assertions mentioned above, ceramic nanosized particles are industrially more favorable as reinforcing inclusions. On the other hand, there is no direct comparison in the literature between Sn-based Sn-Ag-Cu and Sn-Ag solder joints with similar ceramic nanoinclusions based on microstructural features and mechanical properties. In the present research, the Cu/flux + NPs/SAC/flux + NPs/Cu solder joints were produced with a nominal amount of 0.2 wt%, 0.5 wt%, and 1.0 wt% nanosized ZrO2 powder. The solder joints prepared via the above-described method are called in the literature as hybrid solder joints. The microstructure of the as-reflowed and thermally aged samples has been studied, especially at the interface solder/substrate. It has been shown that the minor additions of ZrO2 NPs lead to a decrease in the thickness of the Cu6Sn5 interfacial layer in the as-reflowed solder joints and a reduction in the growth kinetics of this layer, while the Cu3Sn interfacial IMC layer remains practically unaffected. Similar investigations were performed in our previous study but for both the hybrid and nanocomposite Sn-3.0Ag-0.5Cu solder joints. A comparative analysis of the impact of the ZrO2 nanoinclusions on the hybrid solder joints using Sn-3.5Ag and Sn-3.0Ag-0.5Cu has been performed.

Metal deposited nanoparticles as "bridge materials" for lead-free solder nanocomposites.

An influence of carbon nanotubes and carbon nanospheres coated by Au-Pd and Pt on the microstructure of solder/copper joints at room temperature and after aging at sub-zero temperature. The carbon nanosized admixtures were mixed with ternary Sn3.0Ag0.5Cu matrix to prepare a composite solder. The microstructure of the solder joints between the nanocomposite solders and a copper substrate was studied by scanning electron microscopy. It was found that minor (0.05 wt. %) admixtures of both the carbon nanospheres and nanotubes increase the shear strength of the solder joints and reduce the growth rate of the intermetallic Cu6Sn5 layer, formed at the interface between solder and copper. This effect may be related to the adsorption of nanoinclusions on the grain surface during the solidification process. Comparative analysis suggests that exposure for 2 months at 253 K does not lead to deterioration of such an important mechanical characteristic of the solder joint as shear strength, indicating the possibility of using these nanocomposite solders in microelectronic equipment even at temperatures below 0 ℃.

Influence of Isothermal Annealing on Microstructure, Morphology and Oxidation Behavior of AlTiSiN/TiSiN Nanocomposite Coatings.

The present work investigates the influence of isothermal annealing on the microstructure and oxidation behavior of nanocomposite coatings. AlTiSiN/TiSiN coatings with TiSiN adhesive layer were deposited onto a high-speed steel substrate via physical vapor deposition. The coatings were investigated in the as-deposited state as well as after annealing in air at 700, 800, 900 and 1000 °C, respectively. The microstructure and morphology of the coatings were observed using scanning electron microscopy and transmission electron microscopy. The chemical composition and presence of oxidation products were studied by energy-dispersive X-ray spectroscopy. The phase identification was performed by means of X-ray diffraction. In the microstructure of the as-deposited coating, the (Ti1-xAlx)N particles were embedded in an amorphous Si3N4 matrix. TiO2 and SiO2 were found at all annealing temperatures, and Al2O3 was additionally identified at 1000 °C. It was found that, with increasing annealing temperature, the thickness of the oxide layer increased, and its morphology and chemical composition changed. At 700 and 800 °C, a Ti-Si-rich surface oxide layer was formed. At 900 and 1000 °C, an oxidized part of the coating was observed in addition to the surface oxide layer. Compared to the as-deposited sample, the oxidized samples exhibited considerably worse mechanical properties.

Redox features of hexaammineruthenium(III) on MXene modified interface: Three options for affinity biosensing.

In this article we describe construction of a bioreceptive interface for detection of a breast cancer biomarker carbohydrate antigen CA15-3. The conductive interface was patterned by a 2D nanomaterial MXene, to which a mixed layer containing sulfobetaine and carboxybetaine was electrochemically grafted through a diazonium moiety. Such a modified interface was then applied for covalent immobilisation of anti-CA15-3 antibody as a bioreceptive probe for detection of a breast cancer biomarker. Two different strategies were applied for final construction of an immunosensor i.e. an interface finally blocked by bovine serum albumin or an immunosensor without such modification. Finally, electrochemical reading was accomplished using a soluble redox probe Ru(NH3)63+ ion for detection of CA15-3 in a clinically relevant range up to 50 U mL-1. The results indicate that immunosensor based on non-blocked interface can be applied for biosensing using two modes of action: 1. differential pulse voltammetry (a plot of a peak current vs. analyte concentration) and 2. an electrochemical impedance spectroscopy (a plot of a charge transfer resistance vs. analyte concentration). The electrode blocked by bovine serum albumin (BSA) can be used by additional 3. mode of action: through detection of changes in the potential (a plot Epvs. c). Additionally, we reveal and explain that Ru(NH3)63+ is redox probe, which can be applied as interfacial molecular nanoscale ruler to distinguish negatively charged protein molecules present in the close proximity (≤ 6 nm) of the electrode (in our case adsorbed BSA molecules) from the negatively charged protein molecules at a larger distance (>12 nm) from the electrode (i.e. CA15-3 analyte).

Nanofriction Properties of Mono- and Double-Layer Ti3C2Tx MXenes.

Unique structure and ability to control the surface termination groups of MXenes make these materials extremely promising for solid lubrication applications. Due to the challenging delamination process, the tribological properties of two-dimensional MXenes particles have been mostly investigated as additive components in the solvents working in the macrosystem, while the understanding of the nanotribological properties of mono- and few-layer MXenes is still limited. Here, we investigate the nanotribological properties of mono- and double-layer Ti3C2Tx MXenes deposited by the Langmuir-Schaefer technique on SiO2/Si substrates. The friction of all of the samples demonstrated superior lubrication properties with respect to SiO2 substrate, while the friction force of the monolayers was found to be slightly higher compared to double- and three-layer flakes, which demonstrated similar friction. The coefficient of friction was estimated to be 0.087 ± 0.002 and 0.082 ± 0.003 for mono- and double-layer flakes, respectively. The viscous regime was suggested as the dominant friction mechanism at high scanning velocities, while the meniscus forces affected by contamination of the MXenes surface were proposed to control the friction at low sliding velocities.

EBSD investigation of Al/(Al13 Fe4 +Al2 O3 ) nanocomposites fabricated by mechanical milling and friction stir processing.

The application of ball-milling for reactant powders (Fe2 O3 +Al) to form in situ nanosized reaction products in the stir zone of 1050 aluminium alloy was examined and the evolution of microstructure, grain boundaries and microtexture of the fabricated Al/(Al13 Fe4 +Al2 O3 ) nanocomposite was investigated. The mean matrix grain size of the fabricated nanocomposites by the combination of ball milling and friction stir processing were found to be ∼3.2, 3.1 and 2.1 µm for 1, 2 and 3 h milled powder mixtures, respectively. The fraction of high-angle grain boundaries increased markedly in the stir zone indicating the occurrence of dynamic restoration of the aluminium matrix. This was also associated with increasing of the fraction of low ∑CSL boundaries. In addition, the fraction of high-angle grain boundaries increased as the reaction product increased. The developed textures were compared with the most important deformation and recrystallisation texture components of cubic close packed structure. Some of the main texture components formed due to the restoration of aluminium in the stir zone of the material with no powder addition were CubeND {001}<310>, BR {236}<385> and R (or retained S{123} <634>); these are usually found in the rolled materials. However, the presence of nanosized reaction products in the fabricated nanocomposite changed the texture components to the dominant Goss {011}<100>, P {011}<122> and R{124}<211> textures.