Expeditious calcination of inorganic membranes by an instant temperature increment

Rapid thermal treatments potentially allow for a significant reduction in production time of ceramic multilayered membranes, in turn aiding increased industrial application of these membranes and accelerating research on their development. Two methods are proposed for the rapid thermal treatment of thin supported inorganic membrane films. Both methods involve an instant increment in temperature imposed on the membrane. In the first method, the instant temperature step is enforced by placing the membrane in a preheated environment; in the second method, the membrane is placed directly onto a hot plate. The proposed methods can be used for a diverse range of materials. Mesoporous γ-alumina and microporous silica have been selected as model membrane materials. Both rapid heating methods require ∼20 min to yield mesoporous γ-alumina membranes that are comparable to membranes made via conventional calcination (∼1 day). Selective silica membranes have been obtained after 1 h exposure to an environment of 400 or 600 °C, and after 1 h contact with a hot plate of 550 °C (compared to up to 2 days for conventional calcination). The results indicate that, although prevention of contaminations needs continuous attention, both methods proposed for rapid heat treatment can reduce cost and time in ceramic membrane productio

Thermal Imidization Kinetics of Ultrathin Films of Hybrid Poly(POSS-imide)s

In the thermal imidization of an alternating inorganic–organic hybrid network, there is an inverse relationship between the length and flexibility of the organic bridges and the extent of the layer shrinkage. The hybrid material studied here consists of polyhedral oligomeric silsesquioxanes that are covalently bridged by amic acid groups. During heat treatment, shrinkage of the materials occurs due to the removal of physically bound water, imidization of the amic acid groups, and silanol condensation. For five different bridging groups with different lengths and flexibilities, comparable mass reductions are observed. For the shorter bridging groups, the dimensional changes are hindered by the limited network mobility. Longer, more flexible bridging groups allow for much greater shrinkage. The imidization step can be described by a decelerating reaction mechanism with an onset at 150 °C and shows a higher activation energy than in the case of entirely organic polyimides. The differences in the imidization kinetics between hybrid and purely organic materials demonstrates the need for close study of the thermal processing of hybrid, hyper-cross-linked material

Kinetic Analysis of the Thermal Processing of Silica and Organosilica

The incorporation of an organic group into sol–gel-derived silica causes significant changes in the structure and properties of these materials. Therefore, the thermal treatment of organosilica materials may require a different approach. In the present paper, kinetic parameters (activation energy, pre-exponential constant, and reaction models) have been determined from mass loss data for the dehydration, dehydroxylation, and decomposition reactions that take place upon heating silica and organosilica. Parameters were obtained by employing model-free isoconversional methods to data obtained under multiple heating rates as well as by multivariate analysis of the kinetics using a multistep reaction model with distributed activation energy. For silica, it can be concluded that the reaction atmosphere (i.e., inert or thermo-oxidative) has no influence on the reaction rate of the dehydration and dehydroxylation reactions that are responsible for the densification of the material. Under inert atmosphere, full dehydration can be reached without affecting the organic moiety. Achieving complete dehydroxylation of the organosilica is practically impossible as decomposition does manifest itself under commonly employed calcination temperatures. This indicates that prudence is required in designing a heat treatment program for these hybrid materials. To aid in optimizing the thermal treatment, a predictive model was developed, which can be used to forecast the extent of dehydration, dehydroxylation, and decomposition reactions under a multitude of temperature program

Highly permeable and mechanically robust silicon carbide hollow fiber membranes

Silicon carbide (SiC) membranes have shown large potential for applications in water treatment. Being able to make these membranes in a hollow fiber geometry allows for higher surface-to-volume ratios. In this study, we present a thermal treatment procedure that is tuned to produce porous silicon carbide hollow fiber membranes with sufficient mechanical strength. Thermal treatments up to 1500 °C in either nitrogen or argon resulted in relatively strong fibers, that were still contaminated with residual carbon from the polymer binder. After treatment at a higher temperature of 1790 °C, the mechanical strength had decreased as a result of carbon removal, but after treatments at even higher temperature of 2075 °C the SiC-particles sinter together, resulting in fibers with mechanical strengths of 30–40 MPa and exceptionally high water permeabilities of 50,000 L m−2 h−1 bar−1. Combined with the unique chemical and thermal resistance of silicon carbide, these properties make the fibers suitable microfiltration membranes or as a membrane support for application under demanding condition

Search for a CP-odd light Higgs boson in J/ψ →γA⁰

Using J/ψ radiative decays from 9.0 billion J/ψ events collected by the BESIII detector, we search for di-muon decays of a CP-odd light Higgs boson (A0), predicted by many new physics models beyond the Standard Model, including the next-to-minimal supersymmetric Standard Model. No evidence for the CP-odd light Higgs production is found, and we set 90% confidence level upper limits on the product branching fraction B(J/ψ→γA0)×B(A0→μ+μ-) in the range of (1.2-778.0)×10-9 for 0.212≤mA0≤3.0 GeV/c2. The new measurement is a 6-7 times improvement over our previous measurement, and is also slightly better than the BABAR measurement in the low-mass region for tanβ=1

T1 vs. T2 weighted magnetic resonance imaging to assess total kidney volume in patients with autosomal dominant polycystic kidney disease

Purpose: In ADPKD patients total kidney volume (TKV) measurement using MRI is performed to predict rate of disease progression. Historically T1 weighted images (T1) were used, but the methodology of T2 weighted imaging (T2) has evolved. We compared the performance of both sequences. Methods: 40 ADPKD patients underwent an abdominal MRI at baseline and follow-up. TKV was measured by manual tracing with Analyze Direct 11.0 software. Three readers established intra- and interreader coefficients of variation (CV). T1 and T2 measured kidney volumes and growth rates were compared with ICC and Bland-Altman analyses. Results: Participants were 49.7 +/- 7.0 years of age, 55.0% female, with estimated GFR of 50.1 +/- 11.5 mL/min/1.73 m(2). CVs were low and comparable for T2 and T1 (intrareader: 0.83% [0.48-1.79] vs. 1.15% [0.34-1.77], P = 0.9, interreader: 2.18% [1.59-2.61] vs. 1.69% [1.07-3.87], P = 0.9). TKV was clinically similar, but statistically significantly different between T2 and T1: 1867 [1172-2721] vs. 1932 [1180-2551] mL, respectively (P = 0.006), with a bias of only 0.8% and high agreement (ICC 0.997). Percentage kidney growth during 2.2 +/- 0.3 years was similar for T2 and T1 (9.3 +/- 10.6% vs. 7.8 +/- 9.9%, P = 0.1, respectively), with a bias of 1.5% and high agreement (ICC 0.843). T2 was more often of sufficient quality for volume measurement (86.7% vs. 71.1%, P <0.001). Conclusions: In patients with ADPKD, measurement of kidney volume and growth rate performs similarly when using T2 compared to T1 weighted images, although T2 performs better on secondary outcome parameters; they are more often of sufficient quality for volume measurement and result in slightly lower intra- and interreader variability

Cavity-mediated electron-photon pairs

Quantum information, communication, and sensing rely on the generation and control of quantum correlations in complementary degrees of freedom. Free electrons coupled to photonics promise novel hybrid quantum technologies, although single-particle correlations and entanglement have yet to be shown. In this work, we demonstrate the preparation of electron-photon pair states using the phase-matched interaction of free electrons with the evanescent vacuum field of a photonic chip–based optical microresonator. Spontaneous inelastic scattering produces intracavity photons coincident with energy-shifted electrons, which we employ for noise-suppressed optical mode imaging. This parametric pair-state preparation will underpin the future development of free-electron quantum optics, providing a route to quantum-enhanced imaging, electron-photon entanglement, and heralded single-electron and Fock-state photon sources

Oscillating features in the electromagnetic structure of the neutron

The complicated structure of the neutron cannot be calculated using first-principles calculations due to the large colour charge of quarks and the self-interaction of gluons. Its simplest structure observables are the electromagnetic form factors1, which probe our understanding of the strong interaction. Until now, a small amount of data has been available for the determination of the neutron structure from the time-like kinematical range. Here we present measurements of the Born cross section of electron–positron annihilation reactions into a neutron and anti-neutron pair, and determine the neutron’s effective form factor. The data were recorded with the BESIII experiment at centre-of-mass energies between 2.00 and 3.08 GeV using an integrated luminosity of 647.9 pb−1. Our results improve the statistics on the neutron form factor by more than a factor of 60 over previous measurements, demonstrating that the neutron form factor data from annihilation in the time-like regime is on par with that from electron scattering experiments. The effective form factor of the neutron shows a periodic behaviour, similar to earlier observations of the proton form factor. Future works—both theoretical and experimental—will help illuminate the origin of this oscillation of the electromagnetic structure observables of the nucleon

Measurement of the branching fraction of leptonic decay D⁺_s → τ⁺ν_τ via τ⁺→ π⁺π⁰¯ν_τ

By analyzing 6.32  fb−1 of e+e− annihilation data collected at the center-of-mass energies between 4.178 and 4.226 GeV with the BESIII detector, we determine the branching fraction of the leptonic decay D+s→τ+ντ, with τ+→π+π0¯ντ, to be BD+s→τ+ντ=(5.29±0.25stat±0.20syst)%. We estimate the product of the Cabibbo-Kobayashi-Maskawa matrix element |Vcs| and the D+s decay constant fD+s to be fD+s|Vcs|=(244.8±5.8stat±4.8syst)  MeV, using the known values of the τ+ and D+s masses as well as the D+s lifetime, together with our branching fraction measurement. Combining the value of |Vcs| obtained from a global fit in the standard model and fD+s from lattice quantum chromodynamics, we obtain fD+s=(251.6±5.9stat±4.9syst)  MeV and |Vcs|=0.980±0.023stat±0.019syst. Using the branching fraction of BD+s→μ+νμ=(5.35±0.21)×10−3, we obtain the ratio of the branching fractions BD+s→τ+ντ/BD+s→μ+νμ=9.89±0.71, which is consistent with the standard model prediction of lepton flavor universality

Integrated photonics enables continuous-beam electron phase modulation

Integrated photonics facilitates extensive control over fundamental light–matter interactions in manifold quantum systems including atoms1, trapped ions2,3, quantum dots4 and defect centres5. Ultrafast electron microscopy has recently made free-electron beams the subject of laser-based quantum manipulation and characterization6,7,8,9,10,11, enabling the observation of free-electron quantum walks12,13,14, attosecond electron pulses10,15,16,17 and holographic electromagnetic imaging18. Chip-based photonics19,20 promises unique applications in nanoscale quantum control and sensing but remains to be realized in electron microscopy. Here we merge integrated photonics with electron microscopy, demonstrating coherent phase modulation of a continuous electron beam using a silicon nitride microresonator. The high-finesse (Q0 ≈ 106) cavity enhancement and a waveguide designed for phase matching lead to efficient electron–light scattering at extremely low, continuous-wave optical powers. Specifically, we fully deplete the initial electron state at a cavity-coupled power of only 5.35 microwatts and generate >500 electron energy sidebands for several milliwatts. Moreover, we probe unidirectional intracavity fields with microelectronvolt resolution in electron-energy-gain spectroscopy21. The fibre-coupled photonic structures feature single-optical-mode electron–light interaction with full control over the input and output light. This approach establishes a versatile and highly efficient framework for enhanced electron beam control in the context of laser phase plates22, beam modulators and continuous-wave attosecond pulse trains23, resonantly enhanced spectroscopy24,25,26 and dielectric laser acceleration19,20,27. Our work introduces a universal platform for exploring free-electron quantum optics28,29,30,31, with potential future developments in strong coupling, local quantum probing and electron–photon entanglement