Electron Paramagnetic Resonance of Alkali Metal Atoms and Dimers on Ultrathin MgO.

Electron paramagnetic resonance (EPR) can provide unique insight into the chemical structure and magnetic properties of dopants in oxide and semiconducting materials that are of interest for applications in electronics, catalysis, and quantum sensing. Here, we demonstrate that EPR in combination with scanning tunneling microscopy (STM) allows for probing the bonding and charge state of alkali metal atoms on an ultrathin magnesium oxide layer on a Ag substrate. We observe a magnetic moment of 1 µB for Li2, LiNa, and Na2 dimers corresponding to spin radicals with a charge state of +1e. Single alkali atoms have the same charge state and no magnetic moment. The ionization of the adsorbates is attributed to charge transfer through the oxide to the metal substrate. Our work highlights the potential of EPR-STM to provide insight into dopant atoms that are relevant for the control of the electrical properties of surfaces and nanodevices.

A systematic review and dose-response meta-analysis on the efficacy of dapagliflozin in patients with type 1 diabetes mellitus.

Formulation of insulin analogs and its delivery are developed in over recent years but glycemic control in most patients with type-1 diabetes mellitus (DM) is not adequate yet. The aim of this meta-analysis is to evaluate the efficacy of dapagliflozin in patients with type-1 DM. The MEDLINE/PubMed, Scopus, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), and Web of Science databases were searched up to Aug 2020 to identify the potential literature. Random-effects model (DerSimonian and Laird method) was used to estimate the pooled effect size as weighted mean difference (WMD) with 95 % confidence interval (CI). Five randomized placebo-controlled trials with 11 arms were included in the quantitative analysis. The pooled results suggested a significant reduction in glycated hemoglobin A1C (HbA1C; WMD: -0.36 %, 95 % CI: -0.55, -0.18), body weight (WMD: -4.02 kg, 95 % CI: -4.78, -3.25), and total daily insulin dose (TDID; WMD: -10.36 %, 95 % CI: -13.42, -7.29), as well as an increase in 24-h urinary glucose excretion (24-h UGE; WMD: 90.02 g/24-h, 95 % CI: 72.96, 107.09) in dapagliflozin group compared to control group. Dose of dapagliflozin had a significant effect on body weight reduction (Coef = -3.7, p = 0.01) and 24-h UGE (coef = 0.85, p = 0.005). Pooled results of this meta-analysis identified a significant reduction in HbA1c levels, body weight, and TDID, and a substantial increase in 24-h UGE in patients who received dapagliflozin versus placebo.

Terahertz Spin-to-Charge Conversion by Interfacial Skew Scattering in Metallic Bilayers.

The efficient conversion of spin to charge transport and vice versa is of major relevance for the detection and generation of spin currents in spin-based electronics. Interfaces of heterostructures are known to have a marked impact on this process. Here, terahertz (THz) emission spectroscopy is used to study ultrafast spin-to-charge-current conversion (S2C) in about 50 prototypical F|N bilayers consisting of a ferromagnetic layer F (e.g., Ni81 Fe19 , Co, or Fe) and a nonmagnetic layer N with strong (Pt) or weak (Cu and Al) spin-orbit coupling. Varying the structure of the F/N interface leads to a drastic change in the amplitude and even inversion of the polarity of the THz charge current. Remarkably, when N is a material with small spin Hall angle, a dominant interface contribution to the ultrafast charge current is found. Its magnitude amounts to as much as about 20% of that found in the F|Pt reference sample. Symmetry arguments and first-principles calculations strongly suggest that the interfacial S2C arises from skew scattering of spin-polarized electrons at interface imperfections. The results highlight the potential of skew scattering for interfacial S2C and propose a promising route to enhanced S2C by tailored interfaces at all frequencies from DC to terahertz.

Preparative refolding of small monomeric outer membrane proteins.

The outer membrane of gram-negative bacteria constitutes an important hurdle for the transport of hydrophobic molecules into the cell. Mass flux is often facilitated by various outer membrane proteins. These proteins are of biotechnological importance because they could help to improve the performance of whole-cell biocatalysts or be incorporated into artificial cell-like systems. The characterization and understanding of their transport properties greatly benefits from the possibility to express and purify these proteins. We investigated folding parameters for the refolding of four small monomeric outer membrane proteins from Escherichia coli (OmpW) and different pseudomonads (AlkL, OprG and TodX). To this aim we screened a number of inexpensive detergents and detergent concentrations, folding additives as well as protein concentrations. Interestingly, detergents with a C12 chain were most effective in promoting the folding reaction, particularly the negatively charged N-Lauroylsarcosine for OmpW, OprG and TodX as well as the zwitterionic N,N-Dimethyl-n-dodecylamine N-oxide (LDAO) for AlkL. The addition of 1 M urea (AlkL, OmpW), 0.1 M glutamate (OprG) or 0.1 M glycine (TodX) could further improve the folding efficiency. In order to be able to reproducibly produce larger amounts of the proteins, we then established the folding in a miniaturized stirred-tank reactor system combined with a liquid handler. This approach led to a near-complete refolding of OprG (96%), a very good folding of AlkL (84%) and OmpW (71%), only TodX folding was more variable with a final folding efficiency of 52%, all obtained at a final protein concentration of 0.5 g/L.