4 mm mas probe

High-resolution ¹³C solid-state spectra for both riparin I batches were recorded using the ramp CP/MAS sequence with proton decoupling during acquisition. The solid-state NMR experiments were performed at room temperature in a Bruker Avance II spectrometer (Bruker, Karisruhe, Germany) operating at 300.13 MHz for protons and equipped with a 4-mm MAS probe. The operating frequency for carbon was 75.46 MHz. Adamantane was used as an external reference for the ¹³C spectra and to set the Harmann–Hahn matching condition in the cross-polarization experiments. The spinning rate was 10 kHz. All spectra were recorded at ambient temperature and chemical shifts were externally referenced to tetramethylsilane.

The UMONT material was heated to 393
K to remove the nanoconfined water and then rehydrated in a saturated
environment containing ¹⁷O labeled water. All solid-state
NMR experiments were performed on a Bruker AVANCE 500 solid-state
NMR spectrometer equipped with an 11.74 T magnet and a Bruker 4 mm
MAS probe. The resonance frequency was 67.8 MHz for ¹⁷O.
Room temperature ¹⁷O magic angle spinning (MAS) NMR experiment
was performed by employing a single 30° pulse sequence with a
recycle delay time of 0.1 s and 15 kHz of spinning speed. The data
were averaged over 20,548 scans and processed with 100 Hz of exponential
line broadening. Static ¹⁷O NMR data were collected by
using a Hahn Echo pulse sequence with a solid 90° pulse length
of 1.37 μs. The interpulse delay time was varied from 14 to
24 μs, and 22 μs was optimal for echo formation and signal
intensity. The recycle delay time was also varied from 0.05 to 1 s,
but there was no significant difference of the signal intensities
between the qualities of 0.1 and 1 s. The final parameters used for
data acquisition were 0.1 s of recycle delay time and 22 μs
of interpulse delay time. Static ¹⁷O NMR data were collected
in the temperature range of 293–193 K and temperatures were
calibrated by ²⁰⁷Pb NMR spectra.^{60 (link)} The chemical shift was referenced to tap water (0 ppm) for the ¹⁷O NMR.

Initial characterization of the surgical masks occurred through solid‐state NMR spectroscopy. Data have been acquired using a 9.4 T Avance III Bruker spectrometer using a 4 mm MAS probe. ¹H spectra were collected with a single‐pulse sequence adopting a π/2 pulse of 2.5 ms and averaging over 128 scans under MAS condition (10 kHz). ¹³C spectra were acquired with ¹H‐¹³C CPMAS sequence under the same MAS condition. The ¹H π/2 pulse was 2.5 ms, the delay time 5–200 s depending on the sample, as previously determined with ¹H experiments, the contact time 2.5 ms, and the signals were averaged over 4–8k scans. High‐power ¹H decoupling (HPDEC) ¹³C spectra have been collected averaging over 1k scans with a delay time of 50 s and pulse of 4 ms.

The scanning electron microscopy (SEM) images and energy-dispersive X-ray spectroscopy (EDS) of the synthesized zeolites were obtained using Auriga 60 CrossBeam (FIB/FE-SEM) microscopes, operating at an acceleration voltage of 1.5–3 keV and a current of 10 μA.
The X-ray powder diffraction (XRD) patterns were collected at room temperature on a Philips X'Pert Panalytical powder diffractometer using Cu Kα radiation (λ = 1.5418 Å). The data were collected in a stepwise fashion of 2θ ranging from 5.0° to 40.0° with a step size of 0.02° and 2 s per step.
The micropore volume and surface area of the zeolite samples were measured using N₂ adsorption isotherms at 77 K with a Micromeritics ASAP 2020 device. Before the adsorption measurements, each sample was degassed at a temperature of 350°C for 6 h. The specific surface area (S_BET) and microporous volume (V_micro) were calculated using the BET and t-plot methods, respectively.
²⁹Si and ²⁷Al magic angle spinning nuclear magnetic resonance (MAS NMR) spectra were recorded on a Bruker AVIII-500 solid-state NMR spectrometer and a Bruker 4 mm MAS probe. The spectral operating frequencies were 500.1 MHz, 130.3 MHz, and 99.3 MHz for ¹H, ²⁷Al, and ²⁹Si nuclei, respectively.

²H quadrupole echo experiments47 (link) for samples containing POPG-d31 were performed at 61.46 MHz on a Bruker Avance 400 NMR spectrometer using a 4 mm MAS probe, spectral width of 100 KHz and with recycle delay, echo delay, acquisition time and 90° pulse lengths of 0.25 s, 100 μs, 2.6 ms and 3 μs respectively. The temperature was maintained at 310 K to keep the bilayers in their liquid-crystalline phase. During processing the first 10 points were removed in order to start Fourier-transformation at the beginning of the echo. Spectra were zero filled to 1 k points and 50 Hz exponential line-broadening was applied. Smoothed deuterium order parameter profiles were obtained from symmetrised and dePaked ²H-NMR powder spectra of POPG-d31 using published procedures48 49 50 (link).