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.     

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.     

Defect prediction from static code features: current results,limitations, new approaches

Building quality software is expensive and software quality assurance (QA) budgets are limited. Data miners can learn defect predictors from static code features which can be used to control QA resources; e.g. to focus on the parts of the code predicted to be more defective.     

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.     

Chemically Functionalized Reduced Graphene Oxide as Additives in Polyethylene Composites for Space Applications

The discovery of radiation-shielding materials remains a critical technology to enable long-term space travel and extraterrestrial colonization. Hydrocarbon polymers, such as high-density polyethylene (HDPE), are among the best radiation attenuators due to their rich H content and lightweight. Due to their simple chemical structure that lacks larger heteroatoms, HDPE is also resistant to numerous radiation-induced degradation pathways that often limit the applicability of more sophisticated polymers. One drawback of hydrocarbon polymers is their inferior mechanical properties, such as tensile strength and impact toughness, relative to metals and other high-performance polymer systems. In this report, we develop an alkylated reduced graphene oxide that is used as an additive to enhance the storage and tensile moduli of HDPE by 10–15% across the lunar temperature range. These additives outperform unmodified reduced graphene oxide by 30% due to better dispersion through the polymer matrix as observed by cross-sectional scanning electron microscopy. POLYM. ENG. SCI., 60:86–94, 2020. © 2019 Society of Plastics Engineers     

Effect of macromer synthesis time on the properties of the resulting poly(β‐amino ester) degradable hydrogel

Poly(β‐amino ester) biodegradable hydrogels are common in biomedical applications because of their tunable properties and similarities to natural soft tissue. Previous work has shown property adjustments through the choice of monomers, the ratio between monomers and the addition of a crosslinking component. Here, we show that the reaction time for the creation of the macromer can affect the resulting hydrogel properties, and thus provides another method of tuning properties. Macromer was created through the reaction of isobutylamine with poly(ethylene glycol) diacrylate (n = 400). The reaction progress was analyzed using IR and GPC analysis. Hydrogels were created through UV photopolymerization from macromers synthesized for 24, 36, and 48 h. The degradation, compressive moduli, and swelling were measured in an aqueous solution. All showed significant differences between hydrogels of different macromer synthesis times. These differences likely stem from the incomplete macromer synthesis reaction and resulting PEG‐rich regions in hydrogels from shorter synthesis times. These regions will not readily degrade, but do increase the mechanical properties and extent of swelling. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

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.