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Paper-based cell culture platforms have emerged as a promising approach for a myriad of biomedical applications, such as tissue engineering, disease models, cancer research, biotechnology, high-throughput testing, biosensing, and diagnostics. Paper enables the generation of highly flexible, biocompatible, inexpensive, porous, and three-dimensional (3D) constructs and devices. These systems have been used to culture mammalian cells, bacteria, algae, and fungi. Studies have shown that paper is an exceptional material for applications in life sciences, materials sciences, engineering, and medicine. Paper has been employed for creating biomimetic cell culture environments by folding or stacking it into the desired 3D shapes and structures. This review discusses the use of paper-based platforms for cellular applications and provides a diverse range of examples.
It is of the uttermost interest to understand the mechanical performance and deformation mechanisms contributing to small-scale plasticity of materials in micro/nanoelectromechanical systems at their service temperatures, which are usually above room temperature. In recent years, high-temperature nanoindentation experiments have emerged as a reliable approach to characterize the deformation behavior of materials at the nano and submicron scale. In this review, we highlight the role of the temperature in nanoindentation response of a wide variety of materials, with a particular focus on the thermally-activated deformation mechanisms in crystalline and non-crystalline materials under the indenter, e.g., dislocation processes, shear transformation zone, and phase transformations. A brief survey of the temperature-dependent nanoindentation elastic modulus, hardness, and creep behavior of materials is also provided. We also discuss experimental methods for correctly measuring the mechanical properties of materials at high temperatures.
A review of the literature offers an explanation for the large anomalous electro-optic (e.o.) effect reported by Fujiwara et al. in 1994. It is based on the large e.o. coefficient of ordered water at an interface measured in recent years >1000 pm/V. More broadly, the concept of water-based photonics, where water could be a new platform material for devices and systems, is introduced, suggesting that liquid states of matter can allow ready shaping and exploitation of many processes in ways not previously considered. This paper is a commentary on the significance of this new understanding and the broader interest of water in photonics, particularly its consideration as a new platform material.
In this work, we report on the adhesion of HCT116 (human colon carcinoma cells) cultured on nanofibrillar polymethylmethacrylate (PMMA) and SU-8 micropillars substrates. Both surfaces enabled a good cell proliferation and promoted the formation of adherent interconnections with the fabricated nano- and microstructures. The three-dimensional immunofluorescence confocal characterization of the cells on nanotextured PMMA highlighted the expression of well-spread F-actin cytoskeletal networks as well as the presence of focal adhesions. This study provides thus interesting perspectives for further investigations on the force/adhesion mechanisms related to cancer cell growth and proliferation.
Nitrogen-doped graphene (N-G) is a promising non-platinum group metal catalyst for oxygen reduction reaction. A new N-G/metal organic framework (MOF) catalyst is derived by the modification of MOF on N-G catalysts to enhance the electrochemical performance of N-G by increasing the surface area and porosity in this paper. The characterization confirmed that the Brunauer–Emmett–Teller surface areas of N-G/MOF catalysts are 13–66 times larger than the original N-G catalyst. The highest current density (5.02 mA/cm2) and electron transfer number (3.93) of N-G/MOFs are higher than the N-G catalyst. The current density of N-G/MOF catalyst is even higher than 10 wt% Pt/C catalyst.
Cellular adhesion depends on the integration of numerous signaling inputs generated by the chemical and physical properties of the substrate. The complex coupling among inputs makes it challenging experimentally to deconvolve their individual contributions to the adhesion process. To address this roadblock, we have employed a combination of electron beam and optical lithographic techniques to fabricate substrates with independently tunable topographical and chemical signaling cues. Arrays of gold nanostructures were patterned atop quartz substrates, half of which were etched into gold-capped nanopillars. Individual A549 cells exposed simultaneously to Arg-Gly-Asp-functionalized etched and non-etched arrays exhibited strongly preferential adherence to the nanopillars.
In this study, the formation solid solutions of titanium dioxide- zirconium dioxide (TiO2-ZrO2) system with the supercritical fluid method is described. The particles of solid solutions in the TiO2-ZrO2 system are spherical and form agglomerates, they are amorphous and have a size from 90 to 850 nm. The X-ray patterns of samples calcined above the temperatures of crystallization (450 °C) and phase transition (750 °C) demonstrate the decomposition of the solid solutions above the crystallization temperature and formation of phases in accordance with phase ratios in the TiO2-ZrO2 system at these temperatures. The formation solid solutions of the starting materials are observed in all region of concentrations.
The preparation, screening, and characterization of affinity membranes require a deep knowledge of the behavior of all components of the affinity material. Several studies report the effect of different spacers in combination with the ligand molecule, but the effect of the spacer arm “per se” is generally disregarded. The effect of the spacer 1,2-diaminoethane on non-specific protein adsorption was recently investigated and the results were compared with the ones obtained with A2P affinity membranes. The results show that this spacer has indeed an important effect and that similar specific studies need to be performed for every spacer molecule.
We have developed a novel, facile, and reproducible synthesis of highly crystalline oleylamine-capped colloidal platinum nanocubes by microwave (MW) heating. Use of MW heating decreases reaction times, eliminates the need for dangerous reagents [e.g., Fe(CO)5], and gives efficient production of monodispersed 8 nm Pt nanocubes [MW-nanoparticles (NPs)]. We also present a study of the optical properties of these NPs, which to our knowledge has not been previously reported. Absorbance spectra of the MW-NPs show a distinct localized surface plasmon resonance band at 213 nm. This observation could be significant for developments in plasmonic photocatalysis and advanced catalytic materials.
The main challenges of developing advanced surface-enhanced Raman spectroscopy (SERS) sensors lie in the poor reproducibility, low uniformity, and the lack of molecular selectivity. In this paper, we report a facile and cost-effective approach for the large-scale patterning of graphene-encapsulated Au nanoparticles on Si substrate as efficient SERS sensors with highly-improved uniformity, reproducibility, and unique selectivity. The materials production was accomplished via an industry-applicable galvanic deposition—annealing—chemical vapor deposition approach, followed by a final plasma treatment. Our study provides a facile approach to the fabrication of uniform SERS substrate and further prompts the practical progress of SERS-based chemical sensors.
We report a new pulsed chemical vapor deposition (PCVD) process to deposit nickel (Ni) and nickel carbide (Ni3Cx) thin films, using bis(1,4-di-tert-butyl-1,3-diazabutadienyl)nickel(II) precursor and either H2 gas or H2 plasma as the coreactant, at a temperature from 140 to 250 °C. All the PCVD films are fairly pure with low levels of N and O impurities. The films deposited with H2 gas at ≤200 °C are faced centered cubic-phase Ni metal films with low C content; but at ≥220 °C, another phase of rhombohedral Ni3C is formed and the C content increases. However, when H2 plasma is used, the films are always in rhombohedral Ni3C phase for the entire temperature range.
The formation of silver nanostructures (AgNSs) with different crystals morphology in porous SiO2/p-Si templates by the electroless wet-chemical method at temperatures between 20 and 50 °C and surface-enhanced Raman scattering (SERS) was investigated. It was found that optimized dendritic silver architectures contain a significant number of localized “hot spots.” We show that well-reproducible AgNSs provide a significantly enhanced Raman signal of Nile blue dye molecules up to 10−6 M by using different excitation wavelengths (473, 532, and 633 nm). Based on our observations, the well-organized AgNSs can act as efficient surfaces for SERS as well as (bio)-sensor applications.
Magnetic field has been used to trigger biofilm formation. Iron oxide nanoparticles were attached to bacterial cells and cells were aggregated by application of magnetic field. Artificial cellular crowding triggered quorum sensing and led to the formation of biofilm at the sub-threshold population. Aggregation process was monitored by studying temporal dynamics of capacitance and conductance profiles. Capacitive profile exhibited a plateau upon introduction of magnetic field which was retained even after field was removed. This hysteresis property signified biofilm initiation in response to artificial crowding. This work demonstrates how synthetic biology is enabled by including nanoparticles in the interactome.
Detection of chlorpyrifos (CPF) using a surface plasmon resonance (SPR)-enhanced photoelectrochemical sensing system is demonstrated in this study. The presence of CPF was detected based on an increase in the short-circuit photocurrent when a sample is injected into the electrolyte at different concentrations. The short-circuit photocurrent signal was enhanced by both localized SPR of the gold nanoparticles and by the effects of grating-coupled propagating SPR. Using the hybrid SPR-enhancement system, CPF detection was achieved at concentrations as low as 7.5 nM. The proposed technique of leveraging a multifunctional photovoltaic effect can be used for a variety of sensing applications.
Forty-eight different Ag–Al–Zr ternary alloys were prepared in various compositions to determine the metallic glass region in the Ag–Al–Zr ternary system. Experimental results indicated that the metallic glass region in the Ag–Al–Zr ternary system is Ag20–30Al10–30Zr50–60. The Ag20Al30Zr50 and Ag30Al20Zr50 alloys are supposed to have the best glass-forming ability in the Ag–Al–Zr ternary system. The phase equilibria of the Ag–Al–Zr ternary system at 773 K (500 °C) were investigated and compared with the metallic glass region results in the Ag–Al–Zr ternary system. Ternary isothermal sections of the Ag–Al–Zr system at 773 K (500 °C) were established and two ternary intermetallic phases were observed in this isothermal section.
Oxoammonium cation of 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO) was used as an oxidizing dopant of triaryl amines to efficiently and almost quantitatively generate radical cations of the amines or a hole carrier. The doped-triaryl amines yielded an amorphous and homogeneous layer without any residual oxidant or neutral TEMPO molecule through its sublimination or warming the layer. The TEMPO cation-doped spiro-OMeTAD [tetrakis(dimethoxyphenylamine)spirobifluorene] produced a high hole mobility of 2 × 10−4 cm2/Vs. The perovskite solar cell fabricated with the TEMPO cation-doped or residual dopant-free spiro-OMeTAD as the hole-transporting layer displayed a photo-conversion efficiency of 20.1% with durability.
Using kerf-free wafering technologies material losses in semiconductor manufacturing processes can be reduced drastically. By the use of externally applied stress, crystalline materials can be separated along crystal planes with clearly defined thickness. Nevertheless, during this process striations caused by the crack propagation occur. These crack growth features are river and Wallner lines. In this work, we demonstrate a process for spalling that scales favorably for large-area semiconductor substrates with a diameter up to 300 mm. To get rid of the crack growth features, a laser-conditioning process with a high numerical aperture at photon energies below the material bandgap energy, using multi-photon effects is utilized. The process affords a surface roughness Ra after spalling of <1 µm.
Regions of deformation resulting from nanoindentation testing of nanoporous gold (np-Au) are characterized by cross-sectional imaging of the ligament structure directly beneath the surface, after lift-out using focused ion beam techniques. Permanent deformation of the porous structure was not exclusively confined to the region directly in contact with the indenter but extended much deeper into the sample. Implications of these observations with respect to previous measurements of the mechanical properties of np-Au are discussed. The conclusions provide initial insight into the deformation behavior of np structures during nanoindentation, as well as a basis for extending this technique to other np metals.
Different sized graphene quantum dots (GQDs) have been synthesized by an inexpensive wet chemical method using bird charcoal as a precursor. Obtained GQDs found to have luminescence and visible light absorption. These GQDs are further coupled with titanium dioxide (TiO2) to form TiO2–GQDs nanocomposites. GQD nanostructures exhibit band gap tunability and have the potential to enhance the photoabsorption in TiO2. The hybrid combination of the nanomaterials decrease the recombination of charge carriers, increase charge carrier mobility, and improve the overall photoconversion efficiency. The composites exhibit higher photocatalytic activity and rate constants value than pure TiO2.
Ternary sulfides and selenides in the distorted-perovskite structure (“chalcogenide perovskites”) are predicted by theory to be semiconductors with a band gap in the visible-to-infrared and may be useful for optical, electronic, and energy conversion technologies. Here we use computational thermodynamics to predict the pressure–temperature phase diagrams for select chalcogenide perovskites. Our calculations incorporate formation energies calculated by density functional theory, and empirical estimates of heat capacities. We highlight the windows of thermodynamic equilibrium between solid chalcogenide perovskites and the vapor phase at high temperature and very low pressure. These results can guide the adsorption-limited growth of ternary chalcogenides by molecular beam epitaxy.