Interaction between dimethylsulfoxide and formamide in the liquid state

CsPbBr3-DMSO merged perovskite micro-bricks for efficient X-ray detection

Inorganic perovskite wafers with good stability and adjustable sizes are promising in X-ray detection but the high synthetic temperature is a hindrance. Herein, dimethyl sulfoxide (DMSO) is used to prepare the CsPbBr3 micro-bricks powder at room temperature. The CsPbBr3 powder has a cubic shape with few crystal defects, small charge trap density, and high crystallinity. A trace amount of DMSO attaches to the surface of the CsPbBr3 micro-bricks via Pb-O bonding, forming the CsPbBr3-DMSO adduct. During hot isostatic processing, the released DMSO vapor merges the CsPbBr3 micro-bricks, producing a compact and dense CsPbBr3 wafer with minimized grain boundaries and excellent charge transport properties. The CsPbBr3 wafer shows a large mobility-lifetime (μτ) product of 5.16 × 10-4 cm2·V-1, high sensitivity of 14,430 μC·Gyair-1·cm-2, low detection limit of 564 nGyair·s-1, as well as robust stability in X-ray detection. The results reveal a novel strategy with immense practical potential pertaining to high-contrast X-ray detection.

Electronic Supplementary Material

Supplementary material (further details of the characterization, SEM images, AFM images, KPFM images, schematic illustration, XRD patterns, XPS spectra, FTIR spectra, UPS spectra, and stability tests) is available in the online version of this article at 10.1007/s12274-023-5487-3.

Salt effect on volume phase transition of a gel

The salt effect on the phase transition of N-isopropylacrylamide (NIPA) gel was studied for alkali-metal chlorides (NaCl, KCl, and CsCl). Low-frequency Raman scattering experiment was conducted to know the dynamic state of water molecule under the presence of salt and its correlation to macroscopic phase behavior of the gel was investigated together with the thermodynamic activities of water molecule of aqueous alkali-metal chloride solutions. The series of swelling experiment reveal that the change in the gel volume phase transition strongly depends on the salt concentration and is related to the dehydration with respect to hydrophobic hydration. From the analysis of the reduced low-frequency Raman spectra in water and aqueous alkali-metal chlorides solutions by the use of the relaxation mode that takes into account the inertia and the non-white effects, the characteristic values of aqueous salt solutions (i.e., relaxation time and modulation speed) indicate that the addition of alkali-metal chloride to gel fluid affects the disruption of water molecules in the hydration shell around the NIPA gel and the formation of the hydrogen-bonded network structure of water around themselves, as a result of which the gel collapses. The chemical potential and the dynamic nature of water molecule at the transition points are well correlated: the chemical potentials at the transition points are almost constant whereas the structure of bulk water is changed by addition of alkali-metal chlorides or change in temperature. These results strongly suggest that the swelling ratio of N-isopropylacrylamide gel is a function of hydration degree, which is regulated by the chemical potential of water.

Possibility of breakdown of overdamped and narrowing limits in low-frequency Raman spectra: phenomenological band-shape analysis using the multiple-random-telegraph model

Depolarized low-frequency Raman spectra of liquid water and heavy water are investigated from 266 K to 356 K. The reduced Raman spectra below 250 cm(-1) are reproduced by a superposition of one relaxation mode and two damped harmonic oscillator modes. The multiple-random-telegraph (MRT) model, which takes into account inertia and memory effects, is applied to analyze the relaxation component. Two damped harmonic oscillators around 50 cm(-1) and 180 cm(-1) are known as a bendinglike mode and a stretchinglike mode, respectively. It is found that the intensity of the bendinglike mode in water (heavy water) gradually decreases with increasing temperature, and finally vanishes above about 296 K (306 K). The relaxation time of the MRT model is interpreted as representing the averaged lifetime of the vibrating unit. At high temperature, the relaxation time becomes short, that is to say, the vibrating unit is quickly destroyed before the 50 cm(-1) mode is oscillating sufficiently. In the present analysis, the strongly disrupted oscillation cannot be distinguished from the relaxation mode which includes the inertia and memory effects. It is found that the low-frequency Raman spectrum of liquid water at high temperature is a good example demonstrating an application of the MRT model.

Cryoprotectant toxicity and cryoprotectant toxicity reduction: in search of molecular mechanisms

Cryoprotectant toxicity is a fundamental obstacle to the full potential of artificial cryoprotection, yet it remains in general a poorly understood phenomenon. Unfortunately, most relevant biochemical studies to date have not met the basic criteria required for demonstrating mechanisms of toxicity. A model biochemical study of cryoprotectant toxicity was that of Baxter and Lathe, which demonstrated that alteration of a specific enzyme (fructose diphosphatase, or FDPase) was the cause of impaired glycolysis after treatment with and removal of dimethyl sulfoxide (D). FDPase alteration by D was reported to be preventable by the simultaneous presence of amides. This protection could be due to a "counteracting solute" effect similar to that employed by nature, but we find no meaningful correlation between the general protein stabilizing or destabilizing tendency of the cryoprotectant medium and its toxicity. Baxter and Lathe postulated that the effect of D arises from hydrogen bonding between D and the epsilon amino groups of surface lysine residues on FDPase, and it was found that molecules which resembled this group could block the alteration induced by D, presumably by competing with lysine residues for association with D. However, we find that the interaction between D and lysine in the presence of water is actually thermochemically repulsive, and that the presence of formamide does not affect the interaction between D and lysine, implying no useful complex formation between formamide and D. We were also unable to demonstrate that the blocking compounds consistently reduce toxicity when added to D rather than substituting for D, contrary to predictions based on complex formation between blocking compounds and D. In summary, it seems that present concepts of cryoprotectant toxicity are in need of serious revision.

Some emerging principles underlying the physical properties, biological actions, and utility of vitrification solutions

Vitrification solutions are aqueous cryoprotectant solutions which do not freeze when cooled at moderate rates to very low temperatures. Vitrification solutions have been used with great success for the cryopreservation of some biological systems but have been less successful or unsuccessful with other systems, and more fundamental knowledge about vitrification solutions is required. The purpose of the present survey is to show that a general understanding of the physical behavior and biological effects of vitrification solutions, as well as an understanding of the conditions under which vitrification solutions are required, is gradually emerging. Detailed nonequilibrium phase diagram information in combination with specific information on the tolerance of biological systems to ice and to cryoprotectant at subzero temperatures provides a quantitative theoretical basis for choosing between vitrification and freezing. The vitrification behavior of mixtures of cryoprotective agents during cooling is predictable from the behavior of the individual agents, and the behavior of individual agents is gradually becoming predictable from the details of their molecular structures. Progress is continuing concerning the elucidation of mechanisms and cellular sites of toxicity and mechanisms for the reduction of toxicity. Finally, important new information is rapidly emerging concerning the crystallization of previously vitrified cryoprotectant solutions during warming. It appears that vitrification tendency, toxicity, and devitrification all depend on subtle variations in the organization of water around dissolved substances.