Water of Hydration Dynamics in Minerals Gypsum and Bassanite: Ultrafast 2D IR Spectroscopy of Rocks

Water of hydration plays an important role in minerals, determining their crystal structures and physical properties. Here ultrafast nonlinear infrared (IR) techniques, two-dimensional infrared (2D IR) and polarization selective pump–probe (PSPP) spectroscopies, were used to measure the dynamics and disorder of water of hydration in two minerals, gypsum (CaSO₄·2H₂O) and bassanite (CaSO₄·0.5H₂O). 2D IR spectra revealed that water arrangement in freshly precipitated gypsum contained a small amount of inhomogeneity. Following annealing at 348 K, water molecules became highly ordered; the 2D IR spectrum became homogeneously broadened (motional narrowed). PSPP measurements observed only inertial orientational relaxation. In contrast, water in bassanite’s tubular channels is dynamically disordered. 2D IR spectra showed a significant amount of inhomogeneous broadening caused by a range of water configurations. At 298 K, water dynamics cause spectral diffusion that sampled a portion of the inhomogeneous line width on the time scale of ∼30 ps, while the rest of inhomogeneity is static on the time scale of the measurements. At higher temperature, the dynamics become faster. Spectral diffusion accelerates, and a portion of the lower temperature spectral diffusion became motionally narrowed. At sufficiently high temperature, all of the dynamics that produced spectral diffusion at lower temperatures became motionally narrowed, and only homogeneous broadening and static inhomogeneity were observed. Water angular motions in bassanite exhibit temperature-dependent diffusive orientational relaxation in a restricted cone of angles. The experiments were made possible by eliminating the vast amount of scattered light produced by the granulated powder samples using phase cycling methods

Structural Influences on the Fast Dynamics of Alkylsiloxane Monolayers on SiO₂ Surfaces Measured with 2D IR Spectroscopy

There is widespread interest in alkyl chain surface monolayers and their applications. In many applications, alkyl monolayers are functionalized with active headgroups. Here we report the impact of major structural variations on the fast dynamics of alkylsiloxane monolayers. The monolayers were deposited with controlled structures on flat amorphous silica surfaces, and the terminal sites were functionalized with a metal carbonyl headgroup. The CO symmetric stretching mode of the headgroup served as a vibrational probe for detecting the fast structural dynamics of the monolayers using two-dimensional infrared vibrational echo spectroscopy (2D IR) to measure spectral diffusion, which is made quantitative by determining the frequency–frequency correlation function (FFCF) from the time-dependent data. Two methods of functionalizing the surface, independent attachment via a single Si–O bond formed with alkylmonochlorosilane precursors and network attachment via siloxane networks (−Si–O–Si–O−) formed with alkyltrichlorosilane precursors, were compared for several chain lengths. The two types of monolayers produced chain dynamics and structures that were independent of the manner of attachment. For densely packed monolayers, the FFCF decayed mildly slower when the alkyl chain length was decreased from C11 (chain with 11 methylenes) to C4. However, when the chain length was further reduced by one more methylene to C3, substantially slower dynamics were observed. When the chain density was reduced below 50% of fully packed monolayers, the single-component nature of the dynamics changed to a fast component plus an extremely slow component, possibly because of the collapse and entanglement of loosely packed alkyl chains

Water Dynamics in Polyacrylamide Hydrogels

Polymeric hydrogels have wide applications including electrophoresis, biocompatible materials, water superadsorbents, and contact lenses. The properties of hydrogels involve the poorly characterized molecular dynamics of water and solutes trapped within the three-dimensional cross-linked polymer networks. Here we apply ultrafast two-dimensional infrared (2D IR) vibrational echo and polarization-selective pump–probe (PSPP) spectroscopies to investigate the ultrafast molecular dynamics of water and a small molecular anion solute, selenocyanate (SeCN^–), in polyacrylamide hydrogels. For all mass concentrations of polymer studied (5% and above), the hydrogen-bonding network reorganization (spectral diffusion) dynamics and reorientation dynamics reported by both water and SeCN^– solvated by water are significantly slower than in bulk water. As the polymer mass concentration increases, molecular dynamics in the hydrogels slow further. The magnitudes of the slowing, measured with both water and SeCN^–, are similar. However, the entire hydrogen-bonding network of water molecules appears to slow down as a single ensemble, without a difference between the core water population and the interface water population at the polymer–water surface. In contrast, the dissolved SeCN^– do exhibit two-component dynamics, where the major component is assigned to the anions fully solvated in the confined water nanopools. The slower component has a small amplitude which is correlated with the polymer mass concentration and is assigned to adsorbed anions strongly interacting with the polymer fiber networks

MOESM1 of Area asymmetry of heart rate variability signal

Additional file 1. Simulation tests and additional figures

Light-Bias-Dependent External Quantum Efficiency of Kesterite Cu₂ZnSnS₄ Solar Cells

The light-bias-dependent behavior of external quantum efficiency (EQE) in kesterite Cu₂ZnSnS₄ solar cells utilizing different buffers has been reported. Under red light bias, the blue EQE can be enhanced significantly, exceeding unity in magnitude due to photoconductivity of buffers increasing depletion region width and thereby increasing collection efficiency. Under blue light bias, the red EQE increases only in devices with a hybrid buffer. It stays constant with a CdS buffer due to saturated photoconductivity and even decreases with an In₂S₃ buffer due to optical injection of blue photons through the more transparent In₂S₃ into the absorber. Under white illumination, the enhancement can be observed only with unsaturated buffers such as In₂S₃ and the hybrid buffer, while the red EQE reduces due to optical injection. This light-bias-dependent behavior in EQE (including EQE exceeding unity) can be attributed to two key factors: photoconductivity of the buffer layers combined with low minority carrier lifetime of absorber. The effect leads to disagreement between <i>J</i>_sc measured under a simulator and that calculated from the integral of the EQE, revealing the necessity for light bias dependence investigation when verifying the consistency between them. Improving the minority carrier lifetime in absorber and majority carrier concentration in buffer to boost the device electrical property and performance is suggested based on this investigation

MOESM1 of Chiral polymer modified nanoparticles selectively induce autophagy of cancer cells for tumor ablation

Additional file 1: Figure S1. Stability in different solutions as indicated of l-PAV-AuNPs and d-PAV-AuNPs. (a) Photos and (b) UV–Vis-NIR of l-PAV-AuNPs or d-PAV-AuNPs in different solutions including saline, PBS, cell medium, fetal bovine serum and dilution of whole blood of the mice for 3 days. Figure S2. The toxicity study of l/d-PAV-AuNPs. (a) Dose- and chirality-dependent cytotoxicity of l/d-PAV-AuNPs in MDA-MB-231 cells, 3T3 fibroblasts and HBL-100 cells respectively. (b) Apoptosis rates of the MDA-MB-231 cells, 3T3 fibroblasts and HBL-100 cells treated with PAV-AuNPs, respectively. FCM analysis was tested via Annexin V-FITC and PI as probes. (c) Expression levels of LC3 in MDA-MB-231 cells, 3T3 fibroblasts and HBL-100 cells with PAV-AuNPs treatment, separately. GAPDH was used as a loading control. Figure S3. Biodistribution of PAV-AuNPs in vivo. The in vivo biodistribution of PAV-AuNPs was analyzed by testing the Au content in main organs (liver, kidneys, spleen, heart, and lung) of mice at 1 and 30 days post intravenous injection, separately. * and ** present p < 0.05 and p < 0.01, respectively

Low-Temperature Solution Processed Random Silver Nanowire as a Promising Replacement for Indium Tin Oxide

A low-temperature solution-based process for depositing silver nanowire (AgNW) networks for use as transparent conductive top electrode is demonstrated. These AgNWs when applied to Cu₂ZnSnS₄ solar cells outperformed indium tin oxide as the top electrode. Thinner nanowires allow the use of lower temperatures during processing, while longer wires allow lowered sheet resistance for the same surface coverage of NWs, enhancing the transmittance/conductance trade-off. Conductive atomic force microscopy and percolation theory were used to study the quality of the NW network at the microscale. Our optimized network yielded a sheet resistance of 18 Ω/□ and ∼95% transmission across the entire wavelength range of interest for a deposition temperature as low as of 60 °C. Our results show that AgNWs can be used for low-temperature cell fabrication using cheap solution-based processes that could also be promising for other solar cells constrained to low processing temperatures such as organic and perovskite solar cells

CSCs display cell-autonomous resistance to chemotherapy.

<p>(A, B) Cell death analysis of CSCs and non-CSCs from XhCRC or SW620 cells was assessed by CCK-8 activity assay upon chemotherapeutic treatment (5-Fu or OXA).**<i>P</i>< 0.01, ***<i>P</i>< 0.001. (C, D) Enrichment of CSCs in bulk cells from XhCRC (C) and SW620 cells (D) was assessed by FACS analysis based on CD133 expression upon chemotherapy. (E, F) Sphere-forming capacity of bulk cells (XhCRC or SW620 cells) pre-treated by chemotherapeutic agents or DMSO (Ctrl). **<i>P</i>< 0.01, ***<i>P</i>< 0.001.</p

Multidimensional Widefield Infrared-Encoded Spontaneous Emission Microscopy: Distinguishing Chromophores by Ultrashort Infrared Pulses

Photoluminescence (PL) imaging has broad applications in visualizing biological activities, detecting chemical species, and characterizing materials. However, the chemical information encoded in the PL images is often limited by the overlapping emission spectra of chromophores. Here, we report a PL microscopy based on the nonlinear interactions between mid-infrared and visible excitations on matters, which we termed MultiDimensional Widefield Infrared-encoded Spontaneous Emission (MD-WISE) microscopy. MD-WISE microscopy can distinguish chromophores that possess nearly identical emission spectra via conditions in a multidimensional space formed by three independent variables: the temporal delay between the infrared and the visible pulses (t), the wavelength of visible pulses (λvis), and the frequencies of the infrared pulses (ωIR). This method is enabled by two mechanisms: (1) modulating the optical absorption cross sections of molecular dyes by exciting specific vibrational functional groups and (2) reducing the PL quantum yield of semiconductor nanocrystals, which was achieved through strong field ionization of excitons. Importantly, MD-WISE microscopy operates under widefield imaging conditions with a field of view of tens of microns, other than the confocal configuration adopted by most nonlinear optical microscopies, which require focusing the optical beams tightly. By demonstrating the capacity of registering multidimensional information into PL images, MD-WISE microscopy has the potential of expanding the number of species and processes that can be simultaneously tracked in high-speed widefield imaging applications

CD133 identifies CSCs in colorectal cancer.

<p>(A)Schematic of CD133⁺ and CD133^-/lo tumor cells sorting from dissociated colorectal xenograft tumor by FACS. (B) A representative example of post-sorting analysis of the sorted CD133⁺ and CD133^-/lo XhCRC cells.(C) Tumor-initiating frequency of CD133⁺ and CD133^-/lo CRC cells in immunodeficient mice (D-G)Serial sphere formation assays for purified CD133⁺ and CD133^-/loCRC cells (i.e., XhCRC and SW620). Spheres were enumerated (D, F) and representative images are shown (E, G).Scale bars, 100μm.***<i>P</i>< 0.001.</p