Enantioselective Addition of Pyrazoles in order to Dienes

A miniaturized polymerase chain reaction (PCR) system is not only important for medical applications in remote areas of developing countries, but also important for testing at ports of entry during global epidemics, such as the current outbreak of the coronavirus. Although there is a large number of PCR sensor systems available for this purpose, there is still a lack of portable digital PCR (dPCR) heating systems. Here, we first demonstrated a portable plasmonic heating-based dPCR system. The device has total dimensions of 9.7 × 5.6 × 4.1 cm and a total power consumption of 4.5 W, allowing for up to 25 dPCR experiments to be conducted on a single charge of a 20 000 mAh external battery. The dPCR system has a maximum heating rate of 10.7 °C s-1 and maximum cooling rate of 8 °C s-1. Target DNA concentrations in the range from 101 ± 1.4 copies per μL to 260 000 ± 20 000 copies per μL could be detected using a poly(dimethylsiloxane) (PDMS) microwell membrane with 22 080 well arrays (20 μm diameter). Furthermore, the heating system was demonstrated using a mass producible poly(methyl methacrylate) PMMA microwell array with 8100 microwell arrays (80 μm diameter). The PMMA microwell array could detect a concentration from 12 ± 0.7 copies per μL to 25 889 ± 737 copies per μL.Developing simple nonmagnetic methods to efficiently control spin transport across magnetic metal-magnetic semiconductor contacts plays a key role in developing high-performance nano-spintronic devices, since a magnetic field is hard to apply locally. For this purpose, based on first principles calculations, we here propose a mechanical means for manipulating the spin transport across two-dimensional magnetic metal-magnetic semiconductor van der Waals contacts formed between representative metallic Fe3GeTe2 and semiconducting CrGeTe3/CrI3 nanosheets. For such contacts, there exist four spin resolved Schottky barriers, i.e. the n/p-type Schottky barriers in the up/down spin channels, in which the dominant transport spin channel, characterized by the lowest Schottky barrier, can be selectively switched by regulating the magnetic coupling between the magnetic metal and magnetic semiconductor via interfacial sliding. In this way, single spin channel ohmic contacts with reversible spin polarization have been realized.Graphene nanoribbons' electronic transport properties strongly depend on the type of edge, armchair, zigzag or other, and on edge functionalization that can be used for band-gap engineering. For only partly hydrogenated edges interesting magnetic properties are predicted. Electric charge accumulates at edges and corners. Scanning force microscopy has so far shown the centre of graphene nanoribbons with atomic resolution using a quartz crystal tuning fork sensor of high stiffness. Weak long-range electrostatic forces related to the charge accumulation on the edges of graphene nanoribbons could not be imaged so far. Here, we show the electrostatic forces at the corners and edges of graphene nanoribbons are amenable to measurement. We use soft cantilevers and a bimodal imaging technique to combine enhanced sensitivity to weak long-range electrostatic forces with the high resolution of the second-frequency shift. Additionally, in our work the edges of the nanoribbons are mainly hydrogen-free, opening to the route to investigations of partly hydrogenated magnetic nanoribbons.Nanotechnology has a remarkable impact on the preclinical development of future medicines. However, the complicated preparation and systemic toxicity to living systems prevent them from translation to clinical applications. In the present report, we developed a polyepicatechin-based on/off switchable ultra-sensitive magnetic resonance imaging (MRI) visible theranostic nanoparticle (PEMN) for image-guided photothermal therapy (PTT) using our strategy of integrating polymerization and biomineralization into the protein template. We have exploited natural polyphenols as the near infra-red (NIR) switchable photothermal source and MnO2 for the MRI-guided theranostics. PEMN demonstrates excellent MRI contrast ability with a longitudinal relaxivity value up to 30.01 mM-1 s-1. PEMN has shown great tumor inhibition on orthotopic breast tumors and the treatment could be made switchable with an on/off interchangeable mode as needed. PEMN was found to be excretable mainly through the kidneys, avoiding potential systemic toxicity. Thus, PEMN could be extremely useful for developing on-demand therapeutics via'see it and treat it' means with distinguished MRI capability and on/off switchable photothermal properties.Real-time monitoring of volatile organic compounds (VOCs) is critical for a better understanding of chemical processes in ambient air or making minute-by-minute decisions in emergency situations. Proton transfer reaction mass spectrometry (PTR-MS) is nowadays the most commonly used technique for real-time monitoring of VOCs while membrane single photon ionization mass spectrometry (MI-SPI-MS) is a promising MS technique for online detection of trace VOCs. Here, to evaluate the potential of MI-SPI-MS as a complementary tool to PTR-MS, a comprehensive comparison has been performed between MI-SPI-MS and PTR-MS. By using two sets of standard gas mixtures TO15 and PAMS, SPI-MS shows advantages in the detection of ≥C5 alkanes, aromatics and halogens; especially for aromatics, the LODs can reach the ppt level. Edralbrutinib PTR-MS has performed better in the detection of alkenes, ketones and aldehydes. For outdoor measurements, a number of VOCs have been detected while using MI-SPI-MS and PTR-MS in parallel. Consistent temporal variations have been observed for toluene, C8-aromatics and C9-aromatics by the two instruments, with a more sensitive response from the MI-SPI-MS. Thus by measuring both standard gas mixture and complex ambient air samples, we have successfully demonstrated that MI-SPI-MS will be a helpful tool to provide important complementary information on aromatics and alkanes in air, and proper application of MI-SPI-MS will benefit the real-time monitoring of trace VOCs in relative fields.