A nonlinear piezoelectric shunt absorber with 2:1 internal resonance: experimental proof of concept

An experimental proof of concept of a new semi-passive nonlinear piezoelectric shunt absorber, introduced theoretically in a companion article, is presented in this work. This absorber is obtained by connecting, through a piezoelectric transducer, an elastic structure to a resonant circuit that includes a quadratic nonlinearity. This nonlinearity is obtained by including in the circuit a voltage source proportional to the square of the voltage across the piezoelectric transducer, thanks to an analog multiplier circuit. Then, by tuning the electric resonance of the circuit to half the value of one of the resonances of the elastic structure, a two-to-one internal resonance is at hand. As a result, a strong energy transfer occurs from the mechanical mode to be attenuated to the electrical mode of the shunt, leading to two essential features: a nonlinear antiresonance in place of the mechanical resonance and an amplitude saturation. Namely, the amplitude of the elastic structure oscillations at the antiresonance becomes, above a given threshold, independent of the forcing level, contrary to a classical linear resonant shunt. This paper presents the experimental setup, the designed nonlinear shunt circuit and the main experimental results.

Highly spatial-resolved chemical metrology on latent resist images

Patterning photoresist with extreme control over dose and placement is the first crucial step in semiconductor manufacturing. But, how to accurately measure the activation of modern complex resists components at sufficient spatial resolution? No exposed nanometre-scale resist pattern is sufficiently sturdy to unaltered withstand inspection by intense photon or electron beams, not even after processing and development. This paper presents experimental proof that Infra-Red Atomic Force Microscopy (IR-AFM) is sufficiently sensitive and gentle to chemically record the vulnerable-yet-valuable lithographic patterns in a chemically amplified resist after exposure, prior to development. Accordingly, IR-AFM metrology provides the long-sought-for insights in changes in the chemical and spatial distribution per component in a latent resist image, both directly after exposure as well as during processing. With these to-be-gained understandings, a disruptive acceleration of resist design and processing is expected.

Спонтанный спиновый магнетизм донорных электронов проводимости гибридизированных состояний кристалла, образованных системой примесных атомов 3d-элементов низкой концентрации (<1 at.%)

The given work is devoted to the experimental proof of existing the spontaneous spin polarization of the donor electron system of 3d-transition element impurity atoms of low concentration (<1 at.%) in a mercury selenide crystal. For this purpose there have been measured the dependences of the magnetization on the magnetic field strength. As a result of the analysis of the obtained dependences, there were extracted the impurity contributions, which are described by the magnetization curves typical of the ferromagnets, and by the magnetic parameters conforming to the spontaneous magnetism of the systems under study, which are unambiguously related to the donor conduction electrons of the outer d-shells of impurity atoms. By its nature, according to the developed theoretical concepts, the spontaneous spin polarization manifests itself in exchange interaction, taking place in hybridizing the electronic states of the impurity atom and the conduction band ones of the crystal.

Ice 0: the experimental proof of its existence – the result of combining approaches used in radiophysics, geology and geography

The experience of combining the efforts of researchers working at the interface of radiophysics, geology and geography is discussed. The effectiveness of such collaboration of researchers is shown by the example of the experimental proof of the existemce of a new crystalline modiciation of ice, ice 0. This kind of ice is formed at the temperature below –23 °C out of supercooled water, and, together with ice Ih and ice Ic, may be formed at the temperatures and pressures corresponding to the surface layers of the Earth’s atmosphere. For this reason, this study is of great interest for understanding the natural processes taking place in the geospheres (atmosphere, cryosphere, biosphere, and hydrosphere).

Low-Complexity Channel Codes for Reliable Molecular Communication via Diffusion

It is envisioned that healthcare systems of the future will be revolutionized with the development and integration of body-centric networks into future generations of communication systems, giving rise to the so-called “Internet of Bio-nano things”. Molecular communications (MC) emerge as the most promising way of transmitting information for in-body communications. One of the biggest challenges is how to minimize the effects of environmental noise and reduce the inter-symbol interference (ISI) which in an MC via diffusion scenario can be very high. To address this problem, channel coding is one of the most promising techniques. In this paper, we study the effects of different channel codes integrated into MC systems. We provide a study of Tomlinson, Cercas, Hughes (TCH) codes as a new attractive approach for the MC environment due to the codeword properties which enable simplified detection. Simulation results show that TCH codes are more effective for these scenarios when compared to other existing alternatives, without introducing too much complexity or processing power into the system. Furthermore, an experimental proof-of-concept macroscale test bed is described, which uses pH as the information carrier, and which demonstrates that the proposed TCH codes can improve the reliability in this type of communication channel.

Padlock Probe-Based Generation of DNAzymes for the Colorimetric Detection of Antibiotic Resistance Genes

The increasing emergence of multidrug- and pan-resistant pathogens requires rapid and cost-efficient diagnostic tools to contain their further spread in healthcare facilities and the environment. The currently established diagnostic technologies are of limited utility for efficient infection control measures because they are either cultivation-based and time-consuming or require sophisticated assays that are expensive. Furthermore, infectious diseases are unfortunately most problematic in countries with low-resource settings in their healthcare systems. In this study, we developed a cost-efficient detection technology that uses G-quadruplex DNAzymes to convert a chromogenic substrate resulting in a color change in the presence of antibiotic resistance genes. The assay is based on padlock probes capable of high-multiplex reactions and targets 27 clinically relevant antibiotic resistance genes associated with sepsis. In addition to an experimental proof-of-principle using synthetic target DNA, the assay was evaluated with multidrug-resistant clinical isolates.

Experimental Proof of a Solar-powered Heat Pump System for Permafrost Thermal Stabilization

We have suggested earlier a new sustainable method for permafrost thermal stabilization that combines passive screening of solar radiation and precipitation with active solar-powered cooling of the near-surface soil layer thus preventing heat penetration in depth. Feasibility of this method has been shown by calculations, but needed experimental proof. In this article, we are presenting the results of soil temperature measurements obtained at the experimental implementation of this method outside of the permafrost area which actually meant higher thermal loads than in Polar Regions. We have shown that near-surface soil layer is kept frozen during the whole summer, even at air temperatures exceeding +30&deg;C. Therefore, the method has been experimentally proven to be capable of sustaining soil frozen even in more extreme conditions than expected in permafrost areas. In addition to usual building and structure thermal stabilization, the method could be used to prevent the development of thermokarst, gas emission craters, and landslides; greenhouse gases, chemical, and biological pollution from the upper thawing layers at least in the area of human activities; protection against coastal erosion; and permafrost restoration after wildfires. Using commercially widely available components, the technology can be scaled up for virtually any size objects.

Genetic conversion of a split-drive into a full-drive element

Gene-drive systems offer an important new avenue for spreading beneficial traits into wild populations. Their core components, Cas9 and guide RNA (gRNA), can either be linked within a single cassette (full gene drive, fGD) or provided in two separate elements (split gene drive, sGD) wherein the gRNA-bearing element drives in the presence of an independent static source of Cas9. We previously designed a system engineered to turn split into full gene drives. Here, we provide experimental proof-of-principle for such a convertible system inserted at the spo11 locus, which is recoded to restore gene function. In multigenerational cage studies, the reconstituted spo11 fGD cassette initially drives with slower kinetics than the unlinked sGD element (using the same Mendelian vasa-Cas9 source), but eventually reaches a similar level of final introgression. Different kinetic behaviors may result from transient fitness costs associated with individuals co-inheriting Cas9 and gRNA transgenes during the drive process.

Experimental Detection and Measurement of Crack-Type Damage Features in Composite Thin-Wall Beams Using Modal Analysis

An experimental proof-of-concept for damage detection in composite beams using modal analysis has been conducted. The purpose was to demonstrate that damage features can be detected, located, and measured on the surface of a relatively complex thin-wall beam made from composite material. (1) Background: previous work has been limited to the study of simple geometries and materials. (2) Methods: damage detection in the work is based on the accurate measurement of mode shapes and an appropriate design of the detection mesh. Both a method requiring information about the healthy structure and a baseline-free method have been implemented. (3) Results: short crack-type damage features, both longitudinal and transverse, were detected reliably, and the true length of the crack can be estimated from the damage signal. Simultaneous detection of two cracks on the same sample is also possible. (4) This work demonstrates the feasibility of automated damage detection in composite beams using sensor arrays.