Journal: Science Advances

Article Title: Two-dimensional nuclear magnetic resonance spectroscopy with a microfluidic diamond quantum sensor

doi: 10.1126/sciadv.aaw7895

Figure Lengend Snippet: ( A ) Comparison of statistical and thermal polarization of protons in water as a function of detection volume. The room temperature water proton density is ρ = 6.7 × 10 28 m −3 . ( B ) Prepolarization concept. Analyte is prepolarized by flowing it through a permanent magnet (1.5-T Halbach array). It is subsequently shuttled to a microfluidic chip housed in a stabilized, lower magnetic field ( B 0 = 13 mT, Helmholtz coils) where it is detected by NV NMR. ( C ) Detection setup. Prepolarized analyte flows to a microfluidic chip where it is stopped via fluidic switches (not shown), and the NV NMR signal is detected using a custom-built epifluorescence microscope with a numerical aperture (NA) of ∼0.8. A set of eight gradient compensation coils is used to eliminate first- and second-order magnetic field gradients along the field direction. The field is stabilized temporally using a coil-based NMR magnetometer in combination with low-inductance feedback coils wound around the main Helmholtz coils. ( D ) Microfluidic chip setup. The chip is constructed using glass and adhesives (section SV). Two fluidic lines pass to the detection region, one consisting of water (for NMR coil magnetometer) and the other with analyte (for NV NMR). A radio frequency (RF) excitation loop, placed in between the NMR coil magnetometer and the NV NMR sensor, excites nuclear spin coherence in both channels. The NMR coil magnetometer consists of a 3-mm-diameter coil wound around a ∼10-μl water volume. The RF excitation loop and NMR coil magnetometer were placed orthogonal to one another to minimize cross-talk. Copper microwave (MW) lines, printed on the interior of the glass chip, provide spin control over NV electron spins. ( E ) NV NMR geometry. An NV-doped diamond membrane (1 mm by 1 mm by 0.035 mm) is located on the surface of a microfluidic channel (width: 2 mm, height: between 0.2 mm and 1 mm) in contact with the analyte. Laser illumination (532 nm) bounces off the printed microwave line, and fluorescence (650 to 800 nm) is detected. The effective analyte detection volume is ∼40 pL (section SXII).

Article Snippet: Helmholtz coils were driven by a HighFinesse Gmbh UCS 10/40 current source.

Techniques: Comparison, Microscopy, Construct, Control, Membrane, Fluorescence

Journal: Materials

Article Title: Workability and Mechanical Properties of Superplasticized Microfine Cement Grouts

doi: 10.3390/ma15051747

Figure Lengend Snippet: Flexural and unconfined compressive strengths of SMCG with key formulation (cement type, SP type, SP content and W/S). ( a ) Flexural strength; ( b ) Unconfined compressive strength.

Article Snippet: Although the 28-day UCS (11.0 MPa) of CEM I SMCG with 1.2% M was lower than that with 1.5% N, 0.6% PCE or 0% SP, it was acceptable.

Techniques: Formulation