This paper introduces a new methodology for the fabrication of strain-sensor elements for MEMS and NEMS applications based on the tunneling effect in nano-granular metals. The strain-sensor elements are prepared by the maskless lithography technique of focused electron-beam-induced deposition (FEBID) employing the precursor trimethylmethylcyclopentadienyl platinum [MeCpPt(Me)3]. We use a cantilever-based deflection technique to determine the sensitivity (gauge factor) of the sensor element. We find that its sensitivity depends on the electrical conductivity and can be continuously tuned, either by the thickness of the deposit or by electron-beam irradiation leading to a distinct maximum in the sensitivity. This maximum finds a theoretical rationale in recent advances in the understanding of electronic charge transport in nano-granular metals.

Mitochondria play a critical role in generating energy to support the entire lifecycle of biological cells, yet it is still unclear how their morphological structures evolve to regulate their functionality. Conventional fluorescence microscopy can only provide ~300 nm resolution, which is insufficient to visualize mitochondrial cristae. Here, we developed an enhanced squaraine variant dye (MitoESq-635) to study the dynamic structures of mitochondrial cristae in live cells with a superresolution technique. The low saturation intensity and high photostability of MitoESq-635 make it ideal for long-term, high-resolution (stimulated emission depletion) STED nanoscopy. We performed time-lapse imaging of the mitochondrial inner membrane over 50 min (3.9 s per frame, with 71.5 s dark recovery) in living HeLa cells with a resolution of 35.2 nm. The forms of the cristae during mitochondrial fusion and fission can be clearly observed. Our study demonstrates the emerging capability of optical STED nanoscopy to investigate intracellular physiological processes with nanoscale resolution for an extended period of time.

From measurements of fluctuation spectroscopy and weak nonlinear transport on the semimetallic ferromagnet EuB6 we find direct evidence for magnetically-driven electronic phase separation consistent with the picture of percolation of magnetic polarons (MP), which form highly conducting magnetically-ordered clusters in a paramagnetic and 'poorly conducting' background. These different parts of the conducting network are probed separately by the noise spectroscopy/nonlinear transport and the conventional linear resistivity. We suggest a comprehensive and 'universal' scenario for the MP percolation, which occurs at a critical magnetization either induced by ferromagnetic order at zero field or externally applied magnetic fields in the paramagentic region.

The magnetic coupling between doped Mn atoms in clusters as well as crystals of GaN has been studied from first principles using molecular orbital theory for clusters and linearized muffin tin orbitals-tight binding formulation (LMTO-TB) for crystals. The calculations, based on density functional theory and generalized gradient approximation for exchange and correlation, reveal the coupling to be ferromagnetic with a magnetic moment ranging from 2.0 to 4.0 µ B per Mn atom depending on its environment. Mn atoms also tend to cluster and bind more strongly to N atoms than to Ga atoms. The significant binding of Mn to GaN clusters further indicates that it may be possible to increase the Mn concentration in GaN by using a porous substrate that offers substantial interior surface sites.

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A versatile twisted-intramolecular-charge-transfer (TICT)-based near-infrared (NIR) fluorescent probe (L) has been judiciously designed and synthesized that could be utilized for potential cancer diagnosis and to track lymph node(s) in mice through distinct emission signals. Essentially, the probe rendered the capability to preferentially recognize the cancer cells over the noncancer cells by polarity-guided lipid droplet specific differential bioimaging (in green emission channel) studies. The probe also exhibited selective turn-on fluorescence response toward HSA/BSA in physiological media (aqueous PBS buffer; pH 7.4) at far-red/NIR regions, because of the 1:1 chelation between the probe and HSA/BSA. Therefore, the fluorescent probe was then maneuvered to track the draining lymphatic system and sentinel lymph node in tumor mice model by fluorescence imaging (NIR/deep-red channel), wherein the accumulated albumin protein in the draining tumor lymphatic system facilitated the in situ formation of the fluorescent albumin–L complex.

Various strategies for TSQ-induced fluorophore stabilization and their application in sm-FRET as well as in super-resolution imaging microscopy are thoroughly reviewed.