Synthese und Strukturen von Bis(amino)germa- und -stanna-Chalkogeniden

Das cyclische Bis(amino)germylen 1 sowie das -stannylen 2 reagieren mit elementarem S, Se oder Te zu Oxidationsprodukten der allgemeinen Formel Me2Si(NtBu)2MEl2M(NtBu)2SiMe2 (M = Ge, El = S (4), El = Se (5), El = Te (6); M = Sn, El = Se (9), El = Te (10)). Nach Röntgenstrukturanalysen (4, 5, 6, 9, 10) bestehen alle Verbindungen aus drei spirocyclisch verbundenen Vierringen SiN2M (2x) und MEl2M, die weitgehend orthogonal zueinander stehen. Die Germanium- und Zinnatome sind folglich verzerrt tetraedrisch koordiniert, während die Chalkogenatome jeweils zwei Nachbaratome unter spitzem Winkel besitzen. Setzt man 1 mit Trimethylamin-N-oxid um, so wird der Sauerstoff an das Germanium übergeben unter Bildung von [Me2Si(NtBu)2GeO]3 (3). Im Gegensatz zu den anderen Verbindungen kann 3 formal als Trimeres aufgefaßt werden: an einem zentralen weitgehend planaren Ge3O3-Sechsring sind spirocyclisch an den Germaniumatomen jeweils drei GeN2Si Vierringe geknüpft (Röntgenstrukturanalyse von 3). In den zentralen Vierringen von 4, 5, 6, 9 und 10 bestehen keine transanularen Wechselwirkungen zwischen den Chalkogenatomen, obwohl diese einen kurzen Abstand untereinander aufweisen. Die gemittelten MEl Abstände betragen: GeO 1,762(5), GeS 2,226(3), GeSe 2,363(3), GeTe 2,592(5), SnSe 2,536(3), SnTe 2,741(3) Å

Axonal Transport, Phase-Separated Compartments, and Neuron Mechanics - A New Approach to Investigate Neurodegenerative Diseases

Many molecular and cellular pathogenic mechanisms of neurodegenerative diseases have been revealed. However, it is unclear what role a putatively impaired neuronal transport with respect to altered mechanical properties of neurons play in the initiation and progression of such diseases. The biochemical aspects of intracellular axonal transport, which is important for molecular movements through the cytoplasm, e.g., mitochondrial movement, has already been studied. Interestingly, transport deficiencies are associated with the emergence of the affliction and potentially linked to disease transmission. Transport along the axon depends on the normal function of the neuronal cytoskeleton, which is also a major contributor to neuronal mechanical properties. By contrast, little attention has been paid to the mechanical properties of neurons and axons impaired by neurodegeneration, and of membraneless, phase-separated organelles such as stress granules (SGs) within neurons. Mechanical changes may indicate cytoskeleton reorganization and function, and thus give information about the transport and other system impairment. Nowadays, several techniques to investigate cellular mechanical properties are available. In this review, we discuss how select biophysical methods to probe material properties could contribute to the general understanding of mechanisms underlying neurodegenerative diseases

Ella versus Simoa Serum Neurofilament Assessment to Monitor Treatment Response in Highly Active Multiple Sclerosis Patients

The measurement of serum neurofilament light chain (sNfL) is of growing importance in the field of neurology. In the management of multiple sclerosis, it can serve as a useful marker to assess disease activity and treatment response. This paper compares two available methods, namely the Single Molecule Array (Simoa) and the Ella microfluid platform, to measure longitudinal sNfL levels of 42 highly active multiple sclerosis patients treated with alemtuzumab over a period of 36 months. In order to assess the methods agreement, Bland–Altman plots and Passing–Bablok regression were analyzed. Here, we show that despite the fact that Ella measures around 24% higher values than Simoa, both are equally suitable for longitudinal sNfL monitoring

Silicon Doped with Lithium and Magnesium from the Melt for Terahertz Laser Application

Silicon crystals, doped with moderate concentration of magnesium or lithium, have been grown for application as optically pumped donor silicon lasers for the terahertz spectral region. The pedestal growth technique accompanied with axial-loaded dopant pills enabled manufacturing of large silicon crystals with a homogeneous donor distribution in the range from 10^14 to 10^16 cm^-3, as required for intracenter silicon lasers. Terahertz-range photoluminescence from the grown crystals has been observed

Label‑free imaging flow cytometry for analysis and sorting of enzymatically dissociated tissues

Biomedical research relies on identification and isolation of specific cell types using molecular biomarkers and sorting methods such as fluorescence or magnetic activated cell sorting. Labelling processes potentially alter the cells’ properties and should be avoided, especially when purifying cells for clinical applications. A promising alternative is the label-free identification of cells based on physical properties. Sorting real-time deformability cytometry (soRT-DC) is a microfluidic technique for label-free analysis and sorting of single cells. In soRT-FDC, bright-field images of cells are analyzed by a deep neural net (DNN) to obtain a sorting decision, but sorting was so far only demonstrated for blood cells which show clear morphological differences and are naturally in suspension. Most cells, however, grow in tissues, requiring dissociation before cell sorting which is associated with challenges including changes in morphology, or presence of aggregates. Here, we introduce methods to improve robustness of analysis and sorting of single cells from nervous tissue and provide DNNs which can distinguish visually similar cells. We employ the DNN for image-based sorting to enrich photoreceptor cells from dissociated retina for transplantation into the mouse eye

Room-temperature continuous wave lasing in deep-subwavelength metallic cavities under electrical injection

Plasmonic nanolasers and spasers continue to attract a great deal of interest from the physics and nanophotonics community, with the experimental observation of lasing as a focus of research. We report the observation of continuous wave lasing in metallic cavities of deep subwavelength sizes under electrical injection, operating at room temperature. The volume of the nanolaser is as small as 0.42¿3, where ¿ = 1.55 µm is the lasing wavelength. This demonstration will help answer the question of how small a nanolaser can be made, and will likely stimulate a wide range of fundamental studies in basic laser physics and quantum optics on truly subwavelength scales. In addition, such nanolasers may lead to many potential applications, such as on-chip integrated photonic systems for communication, computing, and detection

Electrical injection, continuous wave operation of subwavelength-metallic-cavity lasers at 260K

We report continuous wave lasing operation at T = 260 K of subwavelength-metallic-cavities with semiconductor core encapsulated in silver under electric injection. The physical cavity volumes of the two lasers presented are 0.96¿3 (¿ = 1563.4 nm) and 0.78¿3 (¿ = 1488.7 nm), respectively. Longitudinal modes observed in one of lasers correspond to the Fabry–Perot cavity in the length direction. Such record high temperature operation of a subwavelength laser is of great importance for the development of small light sources in future integrated photonic circuits and other on-chip applications