3D-Printing inside the glovebox: a versatile tool for inert-gas chemistry combined with spectroscopy

3D-Printing with the well-established ‘Fused Deposition Modeling’ technology was used to print totally gas-tight reaction vessels, combined with printed cuvettes, inside the inert-gas atmosphere of a glovebox. During pauses of the print, the reaction flasks out of acrylonitrile butadiene styrene were filled with various reactants. After the basic test reactions to proof the oxygen tightness and investigations of the influence of printing within an inert-gas atmosphere, scope and limitations of the method are presented by syntheses of new compounds with highly reactive reagents, such as trimethylaluminium, and reaction monitoring via UV/VIS, IR, and NMR spectroscopy. The applicable temperature range, the choice of solvents, the reaction times, and the analytical methods have been investigated in detail. A set of reaction flasks is presented, which allow routine inert-gas syntheses and combined spectroscopy without modifications of the glovebox, the 3D-printer, or the spectrometers. Overall, this demonstrates the potential of 3D-printed reaction cuvettes to become a complementary standard method in inert-gas chemistry

Borane adducts of punicine and of its dehydroxy derivatives (pyridinium-1-yl)-2-and 3-phenolates

The natural product punicine (Punica granatum) exists in two tautomeric forms, the cross-conjugated mesomeric betaine 1-(pyridinium-1-yl)-2-hydroxy-phenyl-5-olate and the conjugated mesomeric betaine 1-(pyridinium-1-yl)-5-hydroxy-phenyl-2-olate. Punicine as well as its picoline derivatives reacted with tris(pentafluorophenyl)borane exclusively at the 2'-olate group to form zwitterionic borates. Correspondingly, the 5'-dehydroxy derivate of punicine, the conjugated heterocyclic mesomeric betaine 1-(pyridinium-1-yl)-phenyl-2-olate and its picoline derivatives also gave borates, whereas analogous reactions of the cross-conjugated isomer 2'-dehydroxypunicine [1-(pyridinium-1-yl)-phenyl-3-olatel did not result in the formation of stable adducts. (C) 2020 Elsevier Ltd. All rights reserved.Peer reviewe

Characterization of encapsulated graphene layers using extreme ultraviolet coherence tomography

Many applications of two-dimensional materials such as graphene require the encapsulation in bulk material. While a variety of methods exist for the structural and functional characterization of uncovered 2D materials, there is a need for methods that image encapsulated 2D materials as well as the surrounding matter. In this work, we use extreme ultraviolet coherence tomography to image graphene flakes buried beneath 200 nm of silicon. We show that we can identify mono-, bi-, and trilayers of graphene and quantify the thickness of the silicon bulk on top by measuring the depth-resolved reflectivity. Furthermore, we estimate the quality of the graphene interface by incorporating a model that includes the interface roughness. These results are verified by atomic force microscopy and prove that extreme ultraviolet coherence tomography is a suitable tool for imaging 2D materials embedded in bulk materials

Mouse models for hereditary spastic paraplegia uncover a role of PI4K2A in autophagic lysosome reformation

Hereditary spastic paraplegia (HSP) denotes genetically heterogeneous disorders characterized by leg spasticity due to degeneration of corticospinal axons. SPG11 and SPG15 have a similar clinical course and together are the most prevalent autosomal recessive HSP entity. The respective proteins play a role for macroautophagy/autophagy and autophagic lysosome reformation (ALR). Here, we report that spg11 and zfyve26 KO mice developed motor impairments within the same course of time. This correlated with enhanced accumulation of autofluorescent material in neurons and progressive neuron loss. In agreement with defective ALR, tubulation events were diminished in starved KO mouse embryonic fibroblasts (MEFs) and lysosomes decreased in neurons of KO brain sections. Confirming that both proteins act in the same molecular pathway, the pathologies were not aggravated upon simultaneous disruption of both. We further show that PI4K2A (phosphatidylinositol 4-kinase type 2 alpha), which phosphorylates phosphatidylinositol to phosphatidylinositol-4-phosphate (PtdIns4P), accumulated in autofluorescent deposits isolated from KO but not WT brains. Elevated PI4K2A abundance was already found at autolysosomes of neurons of presymptomatic KO mice. Immunolabelings further suggested higher levels of PtdIns4P at LAMP1-positive structures in starved KO MEFs. An increased association with LAMP1-positive structures was also observed for clathrin and DNM2/dynamin 2, which are important effectors of ALR recruited by phospholipids. Because PI4K2A overexpression impaired ALR, while its knockdown increased tubulation, we conclude that PI4K2A modulates phosphoinositide levels at autolysosomes and thus the recruitment of downstream effectors of ALR. Therefore, PI4K2A may play an important role in the pathogenesis of SPG11 and SPG15. Abbreviations: ALR: autophagic lysosome reformation; AP-5: adaptor protein complex 5; BFP: blue fluorescent protein; dKO: double knockout; EBSS: Earle’s balanced salt solution; FBA: foot base angle; GFP: green fluorescent protein; HSP: hereditary spastic paraplegia; KO: knockout; LAMP1: lysosomal-associated membrane protein 1; MAP1LC3B/LC3: microtubule-associated protein 1 light chain 3 beta; MEF: mouse embryonic fibroblast; SQSTM1/p62: sequestosome 1; PI4K2A: phosphatidylinositol 4-kinase type 2 alpha; PtdIns3P: phosphatidylinositol-3-phosphate; PtdIns4P: phosphatidylinositol-4-phosphate; RFP: red fluorescent protein; SPG: spastic paraplegia gene; TGN: trans-Golgi network; WT: wild typ

A high resolution extreme ultraviolet spectrometer system optimized for harmonic spectroscopy and XUV beam analysis

We present a modular extreme ultraviolet (XUV) spectrometer system optimized for a broad spectral range of 12-41 nm (30-99 eV) with a high spectral resolution of λ/Δλ 784 ± 89. The spectrometer system has several operation modes for (1) XUV beam inspection, (2) angular spectral analysis, and (3) imaging spectroscopy. These options allow for a versatile use in high harmonic spectroscopy and XUV beam analysis. The high performance of the spectrometer is demonstrated using a novel cross-sectional imaging method called XUV coherence tomography. © 2019 Author(s)

Absolute EUV reflectivity measurements using a broadband high-harmonic source and an in situ single exposure reference scheme

We present a tabletop setup for extreme ultraviolet (EUV) reflection spectroscopy in the spectral range from 40 to 100 eV by using high-harmonic radiation. The simultaneous measurements of reference and sample spectra with high energy resolution provide precise and robust absolute reflectivity measurements, even when operating with spectrally fluctuating EUV sources. The stability and sensitivity of EUV reflectivity measurements are crucial factors for many applications in attosecond science, EUV spectroscopy, and nano-scale tomography. We show that the accuracy and stability of our in situ referencing scheme are almost one order of magnitude better in comparison to subsequent reference measurements. We demonstrate the performance of the setup by reflective near-edge x-ray absorption fine structure measurements of the aluminum L2/3 absorption edge in α-Al2O3 and compare the results to synchrotron measurements