BINA

The analysis of thin layers deposited on various substrates is widely employed in thickness monitoring, materials research and development and quality control. Measurements are often performed based on changes to acoustic resonance frequencies of quartz micro-balance devices. The technique is extremely sensitive, but it is restricted to hundreds of MHz frequencies and requires electrical connectivity. In this work we propose and demonstrate the analysis of elastic properties of thin layers deposited on surface acoustic wave-photonic devices in standard silicon-on-insulator. The devices operate at 2.4 GHz frequency, and their interfaces are fiber-optic. The radio-frequency transfer functions of the devices are modified by sub-percent level changes to the group velocity of surface acoustic waves following deposition of layers. Layers of aluminum oxide and germanium sulfide of thickness between 10-80 nm are characterized. The analysis provides estimates for Young’s modulus of the layers.

In the vicinity of a narrow Feshbach resonances Efimov features are expected to be characterized by the resonance's properties rather than the van der Waals length of the interatomic potential. Although this theoretical prediction is well-established by now, it still lacks experimental confirmation. Here, we apply our recently developed three-channel model [Yudkin and Khaykovich, Phys. Rev. A 103, 063303 (2021)] to the experimental result obtained in a mass-imbalanced Li-Cs mixture in the vicinity of the narrowest resonance explored to date [Johansen at. al. Nat. Phys. 13, 731 (2017)]. We confirm that the observed position of the Efimov resonance is dictated mainly by the resonance physics while the influence of the van der Waals tail of the interatomic potential is minor. We show that the resonance position is strongly influenced by the presence of another Feshbach resonance which significantly alters the effective background scattering length at the narrow resonance position.

Open microcavities (OMCs) enable tuning of the optical resonances of a system and insertion of different materials between the mirrors. They are of large scientific interest due to their many potential applications. Using OMCs, we can observe strong light–matter coupling while tuning the cavity wavelength. Typically, dielectric Bragg reflectors (DBRs) and Au mirrors are used to form microcavities and observe vibrational strong coupling (VSC) in the middle-infrared (MIR) spectral region. Here, we make the mirrors of the OMC using thin film coatings of the semiconducting material germanium (Ge) and demonstrate VSC in the MIR region. We deposited a uniform coating of poly(methyl methacrylate) (PMMA) on one of the OMC mirrors’ inner surfaces, and then we tuned the cavity to the carbonyl stretch mode resonance at 1731 cm–1. Comparing VSC using Ge mirrors to DBRs or Au mirrors, we achieve enhanced optical …

The papers in this volume were part of the technical conference cited on the cover and title page. Papers were selected and subject to review by the editors and conference program committee. Some conference presentations may not be available for publication. Additional papers and presentation recordings may be available online in the SPIE Digital Library at SPIEDigitalLibrary. org.

Abnormal cellular copper levels have been clearly implicated in genetic diseases, cancer, and neurodegeneration. Ctr1, a high affinity copper transporter, is an homotrimeric integral membrane protein that provides the main route for cellular copper uptake. Together with a sophisticated copper transport system, Ctr1 regulates Cu(I) metabolism in eukaryotes. Despite its pivotal role in normal cell function, the molecular mechanism of copper uptake and transport via Ctr1 remains elusive. In this study, electron paramagnetic resonance (EPR), UV-visible spectroscopy, and all-atom simulations were employed to explore Cu(I) binding to full-length human Ctr1 (hCtr1), thereby elucidating how metal binding at multiple distinct sites affects the hCtr1 conformational dynamics. We demonstrate that each hCtr1 monomer binds up to 5 Cu(I) ions and that progressive Cu(I) binding triggers a marked structural rearrangement in the …

Coral reefs are in global decline due to climate change and anthropogenic influences (Hughes et al., 2013). Near coastal cities or other densely populated areas, coral reefs face a range of additional challenges. While considerable progress has been made in understanding coral responses to acute individual stressors (Dominoni et al., 2020), the impacts of chronic exposure to varying combinations of sensory pollutants are largely unknown. To investigate the impacts of urban proximity on corals, we conducted a year‐long in‐natura study ‐ incorporating sampling at diel, monthly, and seasonal time points – in which we compared corals from an Urban area to corals from a proximal Non‐Urban area. Here we reveal that despite appearing relatively healthy, natural biorhythms and environmental sensory systems were extensively disturbed in corals from the Urban environment. Transcriptomic data indicated poor …

Distinguishing between d and l enantiomers is of important scientific interest, especially for the pharmaceutical industry. Enantiomeric differentiation in the solid form is repeatedly presented as a challenge in the research community. Raman spectroscopy is a nondestructive tool, widely used for the characterization of different materials by probing their vibrational modes. The low-frequency region of the Raman spectrum reveals lattice-level interactions and global fluctuations in the molecule. Lower frequencies correspond to vibrations arising from weaker bonds and long-range interactions and hence are very susceptible to polarization changes. This work presents low-frequency Raman (LFR) spectroscopy as a facile technique to identify enantiomers. The optical setup of conventional Raman spectroscopy is engineered such that the excitation and collection geometries use an asymmetrical focal cone. In addition, a …

Frequency domain Analysis of FI and FA decays and S2. Mathematical formulation of FI and FA decays

Metastatic breast cancer (MBC) remains incurable due to inevitable development of therapeutic resistance. Although tumor cell intrinsic mechanisms of resistance in MBC are beginning to be elucidated by bulk sequencing studies, the roles of the tumor microenvironment and intratumor heterogeneity in therapeutic resistance remain underexplored due to both technological barriers and limited availability of samples. To comprehensively capture these characteristics we have adapted a research biopsy protocol to collect tissue for an array of single-cell and spatio-molecular assays whose performance we have optimized for MBC, including single-cell and single-nucleus RNA sequencing, Slide-Seq, Multiplexed Error-Robust FISH (MERFISH), Expansion Sequencing (ExSEQ), Co-detection by Indexing (CODEX) and Multiplexed Ion Beam Imaging (MIBI). To date, we have successfully performed single-cell or single …

Optical imaging (OI) has become the most used alternative imaging tool for pre-clinical studies. Among all molecular imaging modalities, fluorescence optical imaging is central thanks to its high sensitivity, the numerous molecular probes available (either endogenous or exogenous) and its ability to simultaneously image multiple biomarkers or biological processes at various spatio-temporal scales. Especially, fluorescence lifetime imaging (FLI) has become an increasingly popular method, as it provides unique insights into the cellular micro-environment by non-invasively examining numerous intracellular parameters such as metabolic status, reactive oxygen species and intracellular pH. Moreover, FLI’s exploitation of native fluorescent signatures has been extensively investigated for enhanced diagnostic of numerous pathologies. However, to perform such measurements in intact, live specimen, it is required to …

We present an experimental study of local magnetic imaging in order to visualize the current flow in superconducting networks. We track the evolution of the spatial distribution of the current flow as the network is driven from fully superconducting to fully normal phases. Our results highlight the factors that contribute to the disordered flow in superconducting networks during their collapse, and demonstrate that the current is never uniformly distributed in the network. These results can assist the design and development of circuits based on superconductors and Josephson junctions.

The virial theorem, and the equipartition theorem in the case of quadratic degrees of freedom, are handy constraints on the statistics of equilibrium systems. Their violation is instrumental in determining how far from equilibrium a driven system might be. We extend the virial theorem to nonequilibrium conditions for Langevin dynamics with nonlinear friction and multiplicative noise. In particular, we generalize it for confined laser-cooled atoms in the semiclassical regime. The resulting relation between the lowest moments of the atom position and velocity allows to measure in experiments how dissipative the cooling mechanism is. Moreover, its violation can reveal the departure from a strictly harmonic confinement or from the semiclassical regime.

Single-molecule FRET (smFRET) is a powerful biophysical tool for measuring intramolecular distances in biomolecules, however FRET is only effective over a 3-10nm scale. In this work we advance a quenching based method which uses Cy3B and Atto647N, a common dye pair used for smFRET. The quenching effect arising from this dye pair is sensitive to distance changes below 3nm, which is significantly lower than its R0 of 6.2 nm. It has previously been used to measure binary on/off transitions, such as local DNA melting in polymerase complexes. However, by using a series of DNAs labelled at various positions we have shown that we can quantitatively distinguish between slight changes in labelling separation. This quenching method is sufficiently sensitive to distinguish between DNAs labelled with dyes 1bp 3′ of each other from those labelled 5′ of each other. Additionally, this effect has been validated …

Quantum Dots (QDs) are being employed in a wide range of biological application due to their superior fluorescence characteristics. Biocompatibility of QDs is usually achieved by exchange of as-synthesized surface ligands with ligands that impart the particle with water solubility properties. An alternative approach for surface functionalization is ligand adsorption. This approach is based on weak interactions between the alkane chains of the as-synthesized surface ligands and a hydrophobic element of an adsorbed ligand with a functional head group/s. There are several advantages for this approach.(i) The photophysical properties stay intact and (ii) the weak association allows for potential adaptive re-distribution of the ligands in response to environment changes. Membrane targeting introduces another layer of complexity and requires precise control of QD’surface properties to control the mode of interaction …

$$\frac {{\partial}^{2}\phi}{\partial {x}^{2}}=-\frac {\partial E}{\partial x}=-\frac {\rho}{\epsilon}\Rightarrow\phi (x)-\phi (0)=-\underset {0}{\overset {x}{\int}} Edx=-\frac {1}{\epsilon}\underset {0}{\overset {x}{\int}}\underset {0}{\overset {{x}^{{\prime}}}{\int}}\rho d {x}^{{\prime}} d {x}^{{\prime}} $$

Tuesday, February 22, 2022 359a and replication processes. Due to its importance, RdRp is one of the main targets for therapeutic approaches. We developed an in-vitro, single-molecule based assay to detect the polymerization activity of the RdRp complex. Using this assay, we optimized the activity of the minimal SARS-CoV-2 RdRp (composed of nsp12, nsp7, and nsp8) by testing various conditions such as different concentrations of salt, molecular crowding agents, and divalent metal ions. The broad compatibility of our activity assay will enable the study of SARS-CoV-2 transcription and replication mechanisms and will be useful in the development of antiviral agents that inhibit the COVID-19 RdRp and potentially many other viral RdRps.

Bacterial membrane potential changes (Δψ) play an important role in bacterial metabolism and cellular processes as well as cell to cell communications in a biofilm. However, existing tools for reading Δψ quantitatively in individual bacterial cells as well as in bacterial communities are limited. A fluorescence lifetime imaging microscopy (FLIM) technique in combination with photo-induced electron transfer (PeT) based small molecule voltage sensitive dyes have been employed to quantify absolute resting membrane potential for individual Bacillus subtilis cells. The local electrostatic potential affects the relative extent of PeT in these dyes and thus alters fluorescence quantum yield (and hence fluorescence intensity as well as fluorescence lifetime). When localized into the bacterial cell membrane, the extent of PeT gets modulated by the resting membrane potential of the system. The suitability and voltage sensitivity of …

Advances in the development of precious-group metal-free (PGM-free) catalysts for the oxygen reduction reaction (ORR) in fuel cell cathodes have produced active catalysts that reduce the performance gap to the incumbent Pt-based materials. However, utilization of state-of-the-art PGM-free catalysts for commercial applications is currently impeded by their relatively low durability. Methods designed to study catalyst degradation in the operation of fuel cells are therefore critical for understanding durability issues and, ultimately, their solutions. Here we report the use of Fourier-transform alternating current voltammetry as an electrochemical method for accurate quantification of the electrochemically active site density of PGM-free cathode catalysts, and to follow their degradation in situ during the operation of polymer electrolyte fuel cells. Using this method, we were able to quantify the electrochemical active site …

A polarizer transistor sharing a groove filtering aperture was developed. In the device, entitled Silicon-On-Insulator Photo-Polarized Activated Modulator (SOIP2AM), one could think that the larger the V-groove, the higher is the absorbed illumination, and consequently the higher is the amount of new generated pairs of electrons-holes inside the device. In fact, the higher the illumination, the higher the destructive interference points inside the V-groove. Establishing a strong correlation between electrical and optical phenomena, two physical assumptions are presented. The first one is that observed “hot spots” (i.e. intense electrical field areas), are in fact the mirror of optical constructive interferences near the walls of the V-groove. The second assumption is that the closer the hot spots near the wall, the higher the generation of pairs of electrons-holes, since more absorbed photons. A new method, based on analytical …

Transition-metal di-chalcogenides (TMDCs) are van der Waals (vdW) layered materials with unique properties, important for the semiconductor industry. Generally, MX2 (where M = metal and X = chalcogen atoms, such as S, Se, or Te) type TMDCs contain easily exfoliable layers, turning to essentially 2D materials. Planar structural defects, such as stacking faults (SFs), change the atomic arrangement, further improving electronic properties, making these materials useful for various applications (optoelectronic devices, spintronics, gas sensing, catalysis, energy storage, thermoelectrics, etc.) Previous reports on TMDC synthesis with specific SFs highlight the challenge in obtaining them. Even more, for a successful application, these SFs should be stable and consistent under experimental conditions. Our previous work on facile preparation of 2H-WSe2 on W foil in an ambient-pressure chemical vapor deposition …