92 research outputs found
X-ray microcomputed imaging of wettability characterization for multiphase flow in porous media: A review
With the advent of X-ray micro-computed tomography which is now routinely used, pore- scale fluid transport and processes can be observed in three-dimensional (3D) at the micro-scale. Multiphase flow experiments that are conducted under in situ imaging scanning conditions can be utilized to study the pore-scale physics relevant to subsurface techno- logical applications. X-ray micro-tomographic imaging is a non-destructive technique for quantifying these processes in 3D within confined pores. This paper presents a review for the usage of X-ray micro-computed tomography experiments to investigate wettability effect on multiphase flow. The fundamental workflow of combining experiments with pore-scale in situ imaging scanning such as equipment requirements, apparatus design and fluid systems are firstly described. Then imaging analysis toolkit is presented for how to quantify interfacial areas, curvatures, contact angles, and fluid properties through these images. Furthermore, we show typical examples, illustrating recent studies for the wettability characterization by using X-ray micro-computed imaging.Cited as: Zou, S., Sun, C. X-ray microcomputed imaging of wettability characterization for multiphase flow in porous media: A review. Capillarity, 2020, 3(3): 36-44, doi: 10.46690/capi.2020.03.0
Dynamic Metabolic Analysis of Cupriavidus necator DSM545 Producing Poly(3‐hydroxybutyric acid) from Glycerol
Ultrafast Charge Transfer in Atomically Thin MoS2/WS2 Heterostructures
Van der Waals heterostructures have recently emerged as a new class of
materials, where quantum coupling between stacked atomically thin
two-dimensional (2D) layers, including graphene, hexagonal-boron nitride, and
transition metal dichalcogenides (MX2), give rise to fascinating new phenomena.
MX2 heterostructures are particularly exciting for novel optoelectronic and
photovoltaic applications, because 2D MX2 monolayers can have an optical
bandgap in the near-infrared to visible spectral range and exhibit extremely
strong light-matter interactions. Theory predicts that many stacked MX2
heterostructures form type-II semiconductor heterojunctions that facilitate
efficient electron-hole separation for light detection and harvesting. Here we
report the first experimental observation of ultrafast charge transfer in
photo-excited MoS2/WS2 heterostructures using both photoluminescence mapping
and femtosecond (fs) pump-probe spectroscopy. We show that hole transfer from
the MoS2 layer to the WS2 layer takes place within 50 fs after optical
excitation, a remarkable rate for van der Waals coupled 2D layers. Such
ultrafast charge transfer in van der Waals heterostructures can enable novel 2D
devices for optoelectronics and light harvesting
Amplitude- and phase-resolved nano-spectral imaging of phonon polaritons in hexagonal boron nitride
Phonon polaritons are quasiparticles resulting from strong coupling of
photons with optical phonons. Excitation and control of these quasiparticles in
2D materials offer the opportunity to confine and transport light at the
nanoscale. Here, we image the phonon polariton (PhP) spectral response in thin
hexagonal boron nitride (hBN) crystals as a representative 2D material using
amplitude- and phase-resolved near-field interferometry with broadband mid-IR
synchrotron radiation. The large spectral bandwidth enables the simultaneous
measurement of both out-of-plane (780 cm-1) and in-plane (1370 cm-1) hBN phonon
modes. In contrast to the strong and dispersive in-plane mode, the out-of-plane
mode PhP response is weak. Measurements of the PhP wavelength reveal a
proportional dependence on sample thickness for thin hBN flakes, which can be
understood by a general model describing two-dimensional polariton excitation
in ultrathin materials
The function and regulation of heat shock transcription factor in Cryptococcus
Cryptococcus species are opportunistic human fungal pathogens. Survival in a hostile environment, such as the elevated body temperatures of transmitting animals and humans, is crucial for Cryptococcus infection. Numerous intriguing investigations have shown that the Hsf family of thermotolerance transcription regulators plays a crucial role in the pathogen-host axis of Cryptococcus. Although Hsf1 is known to be a master regulator of the heat shock response through the activation of gene expression of heat shock proteins (Hsps). Hsf1 and other Hsfs are multifaceted transcription regulators that regulate the expression of genes involved in protein chaperones, metabolism, cell signal transduction, and the electron transfer chain. In Saccharomyces cerevisiae, a model organism, Hsf1’s working mechanism has been intensively examined. Nonetheless, the link between Hsfs and Cryptococcus pathogenicity remains poorly understood. This review will focus on the transcriptional regulation of Hsf function in Cryptococcus, as well as potential antifungal treatments targeting Hsf proteins
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