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This article presents a dual‐band filtering power amplifier (DB‐FPA) with extended passband bandwidths and wide stopband rejection, which is helpful in reducing the number of microwave components in the dual‐band radio frequency front end, resulting in compact circuit size and low loss. In the designed DB‐FPA, a wideband low‐pass filter is applied as the input matching network (IMN) to provide wideband impedance matching and good stopband rejection, while a dual‐band filtering impedance transformation is adopted as the output matching network (OMN) to provide dual‐band impedance matchings and filtering responses simultaneously. Specifically, the IMN is constructed by high‐impedance transmission‐line sections and low‐impedance open‐circuit stubs. The OMN is designed based on the specific external quality factors and coupling coefficients during two bands, resulting in dual‐band impedance transformations and dual‐band filtering responses. Then, based on the above IMN and OMN, the design procedure of the presented DB‐FPA is summarised. To verify the proposed idea, a novel DB‐FPA has been fabricated and measured. During the two frequency bands, the measured maximum power added efficiencies are 55.11% and 47.78% within 33.0 dBm input power, while the measured peak gains are 15.4 and 14.0 dB within 15.0 dBm input power. [ABSTRACT FROM AUTHOR]

A filtering push–pull power amplifier (PPPA) is presented based on the multifunctional impedance matching network (MIMN), which is constructed by coupled lines and open-circuited transmission lines. Due to the symmetry of designed MIMN, the even-and odd-mode method is employed to analyze the operating mechanisms, which reveal that designed MIMN can achieve high common mode suppression under the even-mode excitation, while provide good impedance transformation and filtering response under the odd-mode excitation. Finally, a filtering PPPA based on the MIMN is designed as well as measured, and the measured operating frequencies are ranging from 1.85 to 2.03 GHz. The measured maximum gain and peak power-added efficiency are 13.9 dB and 57.8%, while the measured upper stopband extends to 4.1f0 with the suppression level of 20 dB. [ABSTRACT FROM AUTHOR]

Liquid gates can provide an effective method to control the release of substances. However, the size of liquid gates and the control methods limit their broad applications. The controllable large deformation of liquid metals (LMs) makes it possible to be used in liquid gate design with simple actuation methods. Here an LM gate that can be easily driven under moderate conditions is proposed, on demand opening at mild electrical voltage (2–5 V) and closing at an oscillating mechanical force (≈0.05 N) in a wide range of pH (2–12). The gating mechanism relies on the large surface tension alteration at these conditions, which directly changes the shape of the LM from a flat film to a contracted meniscus to one side of the copper gate‐frame. As demonstrated, this gate can be applied to release substances such as liquid (ink), biomolecule (insulin) by free diffusion. Moreover, single‐channel and multichannel gates can be realized for high throughput control. The biocompatibility of the whole gate is also proved by cytotoxicity assays. Above all, a novel LM gate is offered with simple structure and easy control, which may bring inspiration to applications in controlled substance release and separation. [ABSTRACT FROM AUTHOR]

In this article, the particular importance of nanotechnology-enabled materials associated with additive manufacturing techniques for the realization of radio-frequency (RF) components and modules for Internet of Things (IoT) and millimeter-wave (mm-wave) applications is discussed. [ABSTRACT FROM AUTHOR]

The peptides identified by phage display biopanning have induced the rapid, room-temperature formation of tetragonal barium metatitanate (BaTi[O.sub.3]) from an aqueous precursor solution at near neutral pH. The ability of peptides to promote the rapid formation of functional crystalline multicomponent ceramics has provided new opportunities for the integration of functional materials with low-temperature.

A facile, environmentally-friendly, low-cost, and scalable deposition process has been developed and automated to apply polyelectrolyte multilayers (PEMs) on flexible Kapton HN substrates. Two weak polyelectrolytes, poly(acrylic acid) and polyethylenimine, were deposited in an alternating, layer-by-layer fashion under controlled pH and ionic strength. Compared to strong polyelectrolytes, weak electrolytes can control the properties of the PEMs more systmatically and simply. To our knowledge, this work on surface modification of Kapton is not only the first to use only weak polyelectrolytes, but is also the first to take advantage of the surface properties of calcium-bearing additive particles present in Kapton HN. The resulting surface-modified Kapton HN substrate allowed for the inkjet printing of water-based graphene oxide (GO) inks and organic solvent-based inks with good adhesion and with desired printability. While the deposition of a single PEM layer on a Kapton substrate significantly reduced the water contact angle and allowed for the inkjet-printing of GO inks, the deposition of additional PEM layers was required to maintain the adhesion during post-printing chemical treatments. As a conceptual demonstration of the general applicability of this PEM surface modification approach, a flexible, robust, single-layered gas sensor prototype was fully inkjet printed with both water- and ethanol-based inks and tested for its sensitivity to diethyl ethylphosphonate (DEEP), a simulant for G-series nerve agents. The electrical conductivity and morphology of the sensor were found to be insensitive to repeated bending around a 1 cm radius. [ABSTRACT FROM AUTHOR]

We present a rapid, low-power testbed for the detection and imaging of fluorescent probes utilizing two-photon excitation fluorescence (2PEF). The 2PEF signal from fluorophores commonly used in biological imaging have been enhanced using plasmonic substrates that have been designed to have a high plasmonic resonance over a narrow band that matches the source. The samples were illuminated and imaged using a low-power, in-house multiphoton microscope. A green fluorescent protein (bfloGFPa1), chlorophyll, or rhodamine 6G were deposited onto the plasmonic substrates and their 2PEF signals were measured relative to planar samples. The fluorescence intensities from the green fluorescent protein, chlorophyll, and rhodamine were enhanced by factors of 50, 8, and 4, respectively, with the structured substrates (relative to the planar substrates). [ABSTRACT FROM PUBLISHER]

Hierarchically-porous, rigid inorganic structures have attracted appreciable interest in a wide range of applications, including catalysis, filtration, sensing, and energy storage/harvesting. Naturally-occurring, hierarchically-porous, rigid assemblies with a wide range of three-dimensional (3D) structures are generated by diatoms (photosynthetic aquatic microorganisms); that is, each of the tens of thousands of diatom species forms a macro-to-mesoporous, silica-bearing cell wall (frustule) with a particular, highly-reproducible 3D morphology. We have recently demonstrated that such intricate biosilica structures can be converted, without loss of 3D morphology, into high surface area (>1300 m2/g) macro-to-microporous carbon. Here we demonstrate, for the first time, how the chemical tailoring of such hierarchically-porous, carbon-converted, 3D biogenic structures can result in a high degree of enzyme loading for rapid flow-through catalysis. Two approaches have been developed for enriching such structures with carboxylic acid groups: i) dendritic amplification of partially-oxidized C replicas, and ii) electrochemical Au deposition followed by self-assembly of a carboxylic acid-bearing surface layer. The terminal carboxylic acid groups were then used for electrostatic attachment of a protamine (PA) modified derivative of the model enzyme, glucose oxidase (GOx-PA). In a flow-through system, the GOx-PA-loaded, diatom-derived microscale structures displayed a glucose consumption rate more than 80% faster than for GOx-PA-loaded C black and Au nanoparticles. The rapid flow-through catalysis of the carbon and gold-bearing frustule replicas was enabled by the open 3D morphology of the starting diatom silica templates, along with the enhanced surface area and high enzyme loading resulting from the chemical conversion and surface functionalization processes. [ABSTRACT FROM AUTHOR]

Inspired by biomineralization, biomimetic approaches utilize biomolecules and synthetic analogs to produce materials of controlled chemistry, morphology, and function under relatively benign conditions. A common characteristic of biological and biomimetic mineral-forming processes is the generation of mineral/biomolecule nanocomposites. In this work, it is demonstrated that a facile chemical reaction may be utilized to halogenate the nitrogen-containing moieties of the organics entrapped within bio-inorganic composites to yield halamine compounds. This process provides rapid and potent bactericidal activity to biomimetically and biologically produced materials that otherwise lack such functionality. Additionally, bio-inorganic composites containing the chlorinated peptide protamine are effective in rapidly neutralizing Bacillus spores (≥99.97% reduction in colony forming units within 10 min). The straightforward nature of the described process, and the efficacy of halamine compounds in neutralizing biological and chemical agents, provide new applicability to biogenic and biomimetic materials. [ABSTRACT FROM AUTHOR]

Abstract: Long chain fatty acids (LCFAs), a major source of cellular energy, are solubilized and transported in the blood by binding to serum albumin. Changes in human serum albumin''s (HSA''s) UV absorption and characteristic reactivity with pyridoxal-5′-phosphate appear to reflect a concerted change in its structure upon binding five equivalents of myristate. Isothermal titrations with myristate and other LCFA anions are also consistent with the presence of five strong, interacting, binding sites. Although HSA is usually thought to have many independent LCFA anion binding sites, just five interacting sites appear to account for the changes in structure that accompany its binding of myristate. [Copyright &y& Elsevier]

A bio-enabled, environmentally-friendly, and maximally mild layer-by-layer approach has been developed to surface modify inherently hydrophobic Kapton HN substrates to allow for great printability of both water- and organic solvent-based inks thus facilitating the full-inkjet-printing of flexible electronic devices. Different from the traditional Kapton surface modification approaches which are structure-compromising and use harsh conditions to target, and oxidize and/or remove part of, the surface polyimide of Kapton, the present Kapton surface modification approach targeted the surface electric charges borne by its additive particles, and was not only the first to utilize environmentally-friendly clinical biomolecules to build up a thin film of protamine-heparin complex on Kapton, but also the first to be conducted under minimally destructive and maximally mild conditions. Besides, for electrically charged ink particles, the present surface modification method can enhance the uniformity of the inkjet-printed films by reducing the 'coffee ring effect'. As a proof-of-concept demonstration, reduced graphene oxide-based gas sensors, which were flexible, ultra-lightweight, and miniature-sized, were fully-inkjet-printed on surface modified Kapton HN films and tested for their sensitivity to dimethyl methylphosphonate (a nerve agent simulant). Such fabricated sensors survived a Scotch-tape peel test and were found insensitive to repeated bending to a small 0.5 cm radius. [ABSTRACT FROM AUTHOR]

On page 4236, bio‐inorganic composite materials are functionalized under benign reaction conditions by R. R. Naik and co‐workers. The nitrogen moieties associated with the biopolymers within the composite are chlorinated to yield halamine compounds. Bacterial spores are localized on the surfaces of these chlorinated Coscinodiscus granii frustules, and then the release of oxidizing halogens from their surfaces is capable of killing bacteria and inactivating the spores. [ABSTRACT FROM AUTHOR]

This work describes a facile, mild and general wet chemical method to change the material and the geometry of inkjet-printed interdigitated electrodes (IDEs) thus drastically enhancing the sensitivity of chemiresistive sensors. A novel layer-by-layer chemical method was developed and used to uniformly deposit semiconducting single-wall carbon nanotube (SWCNT)-based sensing elements on a Kapton ® substrate. Flexible chemiresistive sensors were then fabricated by inkjet-printing fine-featured silver IDEs on top of the sensing elements. A mild and facile two-step process was employed to convert the inkjet-printed dense silver IDEs into their highly porous gold counterparts under ambient conditions without losing the IDE-substrate adhesion. A proof-of-concept gas sensor equipped with the resulting porous gold IDEs featured a sensitivity to diethyl ethylphosphonate (DEEP, a simulant of the nerve agent sarin) of at least 5 times higher than a similar sensor equipped with the original dense silver IDEs, which suggested that the electrode material and/or the Schottky contacts between the electrodes and the SWCNTs might have played an important role in the gas sensing process.

We report on the fabrication and performance of polymer-based inverted solar cells utilizing amorphous indium zinc oxide (a-IZO) as the electron-collecting electrode. Amorphous IZO films of 200 nm thickness were deposited by room temperature sputtering in a high-purity argon atmosphere. The films possessed a high optical transmittance in the visible region (≥ 80%), a low resistivity (3.3 × 10⁻⁴ Ωcm), a low surface roughness (root mean square = 0.68 nm), and a low work function (4.46 ± 0.02 eV). Inverted solar cells with the structure a-IZO/P3HT: PCBM/PEDOT:PSS/Ag exhibited a power conversion efficiency of 3% estimated for AM 1.5G, 100 mW/cm² illumination.