Accurate acidity studies of different families of substrates in a pure protic ionic liquid (PIL) show that solute ions in the PIL are free from specific ion associations and the solvation behaviour of PILs is closely related to the number of dissociable protons.
PILs are promising solvent systems for CO2 absorption and transformations. Although previously tremendous work has been paid to synthesize functionalized PILs to achieve a high-performance absorption, the underlying mechanisms are far less investigated and still not clear. In this work, a series of DBU-based PILs, i.e., [DBUH][X], with anions of various basicities were synthesized. The basicities of the anions were accurately measured in [DBUH][OTf] or extrapolated from the known linear correlations. The apparent kinetics as well as the capacities for CO2 absorption in these PILs were studied systematically. The results show that the absorption rate and capacity in [DBUH][X] are in proportional to the basicity of PIL, i.e., a more basic PIL leads to a faster absorption rate and a higher absorption capacity. In addition, the spectroscopic evidences and correlation analysis indicate that the capacity and mechanism of CO2 absorption in [DBUH][X] are essentially dictated by the basicities of anions of these PILs.
A new chiral HBD system, N-tert-butyl sulfinyl squaramide, was designed and synthesized. The core N-tert-butyl sulfinyl squaramide with an 1-aminoindan-2-ol skeleton was found to be an efficient catalyst in the enantioselective Friedel-Crafts alkylation of indoles and acyl phosphonates.
The
equilibrium acidities for several series of structural and
electronic different organic acids were measured in 3-pyrrolidinium-based
aprotic and protic ionic liquid (IL) analogues, that is, [Bmpy][NTf2], [BpyH][NTf2], and [PyH2][NTf2], by the UV–Vis method. The acidities of neutral acids
are found to be much stronger in the protic ILs (PILs) than aprotic
ILs (AILs), and the acidifying effect in the two PILs roughly increases
proportionally to the number of protons in the cation of the PIL.
On the other hand, interestingly, the cationic N+–H
acids exhibit similar acidities in [Bmpy][NTf2] and [BpyH][NTf2] but much weaker than those in [PyH2][NTf2]. The Hammett ρ values for the acidic dissociation
of para-substituted benzoic acids in two PILs are about the same as
that in water (1.00) but significantly smaller than that in the AIL
[Bmpy][NTf2] (2.66). The correlations between the acidities
in the PILs and water show double-linear relationships with different
slopes and intercepts for the neutral and cationic acids. These, together
with previous observations in the PILs [DBUH][OTf] (DBU = 1,5-diazabicyclo(5.4.0)-5-undecene)
and EAN (ethylammonium nitrate), clearly indicate that the structure
of the cation plays a subtle but a crucial role on sensing the electronic
nature of solutes and strongly affects the solvation behaviors of
PILs.
Background
Optical coherence tomography (OCT) is widely used in ophthalmology for viewing the morphology of the retina, which is important for disease detection and assessing therapeutic effect. The diagnosis of retinal diseases is based primarily on the subjective analysis of OCT images by trained ophthalmologists. This paper describes an OCT images automatic analysis method for computer-aided disease diagnosis and it is a critical part of the eye fundus diagnosis.
Methods
This study analyzed 300 OCT images acquired by Optovue Avanti RTVue XR (Optovue Corp., Fremont, CA). Firstly, the normal retinal reference model based on retinal boundaries was presented. Subsequently, two kinds of quantitative methods based on geometric features and morphological features were proposed. This paper put forward a retinal abnormal grading decision-making method which was used in actual analysis and evaluation of multiple OCT images.
Results
This paper showed detailed analysis process by four retinal OCT images with different abnormal degrees. The final grading results verified that the analysis method can distinguish abnormal severity and lesion regions. This paper presented the simulation of the 150 test images, where the results of analysis of retinal status showed that the sensitivity was 0.94 and specificity was 0.92.The proposed method can speed up diagnostic process and objectively evaluate the retinal status.
Conclusions
This paper aims on studies of retinal status automatic analysis method based on feature extraction and quantitative grading in OCT images. The proposed method can obtain the parameters and the features that are associated with retinal morphology. Quantitative analysis and evaluation of these features are combined with reference model which can realize the target image abnormal judgment and provide a reference for disease diagnosis.
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