Prerequisites for a Cc/Cs-corrected ultrahigh-resolution TEM

After the introduction of a corrector to compensate for the spherical aberration of a TEM and the acceptance of this new instrumentation for high-resolution CTEM (conventional transmission electron microscope) and STEM (scanning transmission electron microscope) by the electron microscopy community, a demand for even higher resolution far below 1A has emerged. As a consequence several projects around the world have been launched to make these new instruments available and to further push the resolution limits down toward fractions of 1A. For this purpose the so-called TEAM (transmission electron aberration-corrected microscope) has been initiated and is currently under development. With the present paper we give a detailed assessment of the stability required for the base instrument and the electric stability, the manufacturing precision, and feasible semi-automatic alignment procedures for a novel C(c)/C(s)-corrector in order to achieve aberration-free imaging with an information limit of 0.5A at an acceleration voltage of 200 kV according to the goals for the first TEAM instrument. This new aberration corrector, a so-called Achroplanat, in combination with a very stable high-resolution TEM leads to an imaging device with unprecedented resolving power and imaging properties.     

Contour superresolved imaging of static ground targets using satellite platform

We propose a method for increasing the contour resolution of static ground targets and to overcome the diffraction limit of an optical system installed on top of a satellite. The resolution improvement is obtained by using a sequence of low-resolution images taken from different angles realized by the movement of the satellite platform. The superresolving process is obtained by the generation of relative movement between the inspected object and the a priori known high-resolution background. The relative movement is caused because the images are taken from different angles. The captured set of low-resolution images are decoded by the a priori known high-resolution background obtained from a set of reference images taken only once by a high-resolution camera. The proposed concept is demonstrated via Matlab simulation and laboratory experiments.     

Nucleotide-Driven Molecular Sensing of Monkeypox Virus Through Hierarchical Self-Assembly of 2D Hafnium Disulfide Nanoplatelets and Gold Nanospheres

Liquid interfaces facilitate the organization of nanometer-scale biomaterials with plasmonic properties suitable for molecular diagnostics. Using hierarchical assemblage of 2D hafnium disulfide nanoplatelets and zero-dimensional spherical gold nanoparticles, the design of a multifunctional material is reported. When the target analyte is present, the nanocomposites’ self-assembling pattern changes, altering their plasmonic response. Using monkeypox virus (MPXV) as an example, the findings reveal that adding genomic DNA to the nanocomposite surface increases the agglomeration between gold nanoparticles and decreases the π-stacking distance between hafnium disulfide nanoplatelets. Further, this self-assembled nanomaterial is found to have minimal cross-reactivity toward other pathogens and a limit of detection of 7.6 pg µL⁻¹ (i.e., 3.57 × 10⁴ copies µL⁻¹) toward MPXV. Overall, this study helped to gain a better understanding of the genomic organization of MPXV to chemically design and develop targeted nucleotides. The study has been validated by UV–vis spectroscopy, X-ray diffraction, scanning transmission electron microscopy, surface-enhanced Raman microscopy and electromagnetic simulation studies. To the best knowledge, this is the first study in literature reporting selective molecular detection of MPXV within a few minutes and without the use of any high-end instrumental techniques like polymerase chain reactions.     

Multifunctional temperature-responsive polymers as advanced biomaterials and beyond

The versatility and applicability of thermoresponsive polymeric systems have led to great interest and a multitude of publications. Of particular significance, multifunctional poly(N-isopropylacrylamide) (PNIPAAm) systems based on PNIPAAm copolymerized with various functional comonomers or based on PNIPAAm combined with nanomaterials exhibiting unique properties. These multifunctional PNIPAAm systems have revolutionized several biomedical fields such as controlled drug delivery, tissue engineering, self-healing materials, and beyond (e.g., environmental treatment applications). Here, we review these multifunctional PNIPAAm-based systems with various cofunctionalities, as well as highlight their unique applications. For instance, addition of hydrophilic or hydrophobic comonomers can allow for polymer lower critical solution temperature modification, which is especially helpful for physiological applications. Natural comonomers with desirable functionalities have also drawn significant attention as pressure surmounts to develop greener, more sustainable materials. Typically, these systems also tend to be more biocompatible and biodegradable and can be advantageous for use in biopharmaceutical and environmental applications. PNIPAAm-based polymeric nanocomposites are reviewed as well, where incorporation of inorganic or carbon nanomaterials creates synergistic systems that tend to be more robust and widely applicable than the individual components. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48770.     

Analysis of coiled-tube heat exchangers to improve heat transfer rate with spirally corrugated wall

Steady heat transfer enhancement has been studied in helically coiled-tube heat exchangers. The outer side of the wall of the heat exchanger contains a helical corrugation which makes a helical rib on the inner side of the tube wall to induce additional swirling motion of fluid particles. Numerical calculations have been carried out to examine different geometrical parameters and the impact of flow and thermal boundary conditions for the heat transfer rate in laminar and transitional flow regimes. Calculated results have been compared to existing empirical formulas and experimental tests to investigate the validity of the numerical results in case of common helical tube heat exchanger and additionally results of the numerical computation of corrugated straight tubes for laminar and transition flow have been validated with experimental tests available in the literature. Comparison of the flow and temperature fields in case of common helical tube and the coil with spirally corrugated wall configuration are discussed. Heat exchanger coils with helically corrugated wall configuration show 80–100% increase for the inner side heat transfer rate due to the additionally developed swirling motion while the relative pressure drop is 10–600% larger compared to the common helically coiled heat exchangers. New empirical correlation has been proposed for the fully developed inner side heat transfer prediction in case of helically corrugated wall configuration.     

Sunlight-proof optical distance measurements with a dual-line lock-in time-of-flight sensor

This work describes time-of-flight distance measurements with a line sensor based on the correlation principle. It is capable of suppressing maximum bright sunlight and even more electronically in each pixel autonomously without using any optical filters. The optical fill factor of a pixel is 58% embodying a 100 × 100 μm2 photodiode. Working principle of the pixel circuit and the mechanism for suppression of ambient illumination as well as physical limitation of accuracy are discussed. Characterizations of the single-pixel performance with 650 nm laser and 850 nm LED sources with optical output powers of 1 mW and 900 mW, respectively, are presented. Finally, measured characteristics of the line sensor for distances up to 3.2 m are shown. The standard deviation is below 2 cm up to 1.2 m at a measurement time of 50 ms per distance point and the near-infrared LED illumination.     

An 11-bit successive approximation analog-to-digital converter based on a combined capacitor-resistor network

Within this work an 11-bit integrated Successive Approximation Register (SAR) Analog-to-Digital Converter (ADC) based on a combined capacitor and resistor network is presented. Utilizing this approach, the chip area is reduced by the factor of 2⁴ compared to conventional solutions without any interpolation and it occupies only 0.3 mm². Furthermore, the equivalent capacitance is decreased by connecting two capacitors in series, whereby the matching and the power consumption are improved. The measured Differential Non-Linearity (DNL) and the Integral Non-Linearity (INL) are below 0.3 and 0.5 LSBs, respectively. The calculated Effective Number Of Bits (ENOB) accounts to 10.72 bits. The chip is produced in 0.6 μm CMOS technology.     

Basic considerations and topologies of switched-mode assistedlinear power amplifiers

This paper presents a combined power amplifier system consisting of a linear amplifier unit with a switched-mode (class D) current dumping stage arranged in parallel. With this topology, the fundamental drawback of conventional linear power amplifiers-the high loss-is avoided. Compared to a pure class D (switching) amplifier, the presented system needs no output filter to reduce the switching frequency harmonics. This filter (usually of multistage type) generally deteriorates the transient response of the system and impairs the feedback loop design. Furthermore, the low-frequency distortions of switching amplifiers caused by the interlock delay of their power transistors are avoided with the presented switched-mode assisted linear amplifier system. This can be considered as a master-slave system with a guiding linear amplifier and a supporting class D slave unit. The paper describes the operating principle of the system, analyzes the fundamental relationships for the circuit design, and presents simulation results. Finally, various further topologies of switched-mode assisted linear amplifiers are given     

Electroplate and lift lithography for patterned micro/nanowires using ultrananocrystalline diamond (UNCD) as a reusable template

A fast, simple, scalable technique is described for the controlled, solution-based, electrochemical synthesis of patterned metallic and semiconducting nanowires from reusable, nonsacrificial, ultrananocrystalline diamond (UNCD) templates. This enables the repeated fabrication of arrays of complex patterns of nanowires, potentially made of any electrochemically depositable material. Unlike all other methods of patterning nanowires, this benchtop technique quickly mass-produces patterned nanowires whose diameters are not predefined by the template, without requiring intervening vacuum or clean room processing. This technique opens a pathway for studying nanoscale phenomena with minimal equipment, allowing the process-scale development of a new generation of nanowire-based devices.