Specific ion effects on transient polymers: a new strategy for programmable microcapusles

Transient polymers are emerging materials that transform from macromolecules to small molecules triggered by predefined environmental stimuli. Distinct from traditional degradable polymers, transient materials undergo domino like chain unzipping reactions, leading to controlled and complete depolymerization upon one cleavage. Taking advantage of the unique feature of triggered materials transience, this dissertation focuses on developing transient polymer microcapsules for programmable payload release. In Chapter 2, a rapid solvent evaporation strategy was developed to prepare transient polymer microcapsules with a low-ceiling-temperature polymer, cyclic poly(phthalaldehyde) (cPPA), as the shell wall materials. Chapter 3 described an ion co-activation effect that modulated cPPA depolymerization rates in the presence of acid. In Chapter 4, we further investigated the ion specificity in the co-activation effect and anion solvation properties were found to significantly impact the co-activation behavior. Based on the specific ion co-activation effect, we developed programmable microcapsules whose payload release kinetics depends on the ionic species in the solutions. Chapter 5 further expanded the co-activation effect in Lewis acid solutions that achieved depolymerization in mild environment. In Chapter 6, several studies were devoted to understand the molecular and interfacial mechanisms of the ion co-activation effect. Chapter 7 reviewed current topics on the Hofmeister effect and constructed a crude model on auto-catalytic microcapsules. The thesis research offers an encapsulation strategy and ion library for triggered release microcapsules and will be of significance for designing logic gate responsive microcapsules, reversible activation-deactivation materials and self-regulating reaction networks in autonomous chemical system

Differential persuasive effects of high and low credibility sources on Singapore and China individual investors' judgement.

With the proliferation of investment information, investors are likely to have repeated exposure to similar information from sources with varying credibility. Contrary to main effects studies, psychology research has found that low credibility source may interact with other factors to be more persuasive than high credibility source. Our experimental results, using Singapore accountancy undergraduates as participants, indicate that for individual investor holding an initial negative position, negative news from a low credibility source is more persuasive than a high credibility source. Furthermore, repeating similar negative news from another low credibility source enhances the overall persuasiveness of the news regardless of whether the first exposure to the news is from a high or low credibility source, although the effect is stronger for the former. With repeated exposure from a high credibility source, we obtained weak support on the decrease in overall persuasiveness when the initial source credibility is low and opposite result when the initial source credibility is high. All the above results were obtained (except that the effects were stronger) when we replicated the experiment conditions using China participants

Programmable Payload Release from Transient Polymer Microcapsules Triggered by a Specific Ion Coactivation Effect

Stimuli-responsive materials activated by a pair of molecular or ionic species are of interest in the design of chemical logic gates and signal amplification schemes. There are relatively few materials whose coactivated response has been well-characterized. Here, we demonstrate a specific ion coactivation (SICA) effect at the interfaces of transient polymer solids and liquid solutions. We found that depolymerization of the transient polymer, cyclic poly­(phthalaldehyde) (cPPA), exhibited a SICA effect when the cPPA core–shell microcapsules were suspended in ion-containing acidic methanol solutions. Significant acceleration in cPPA depolymerization rate is triggered by the combination of acid and ion coactivators. Intriguingly, the SICA effect is related to the Hofmeister behavior. The SICA effect is primarily determined by anions, and cations exhibit a secondary effect that modulates the coactivation strength. Based on these observations, we developed cPPA programmable microcapsules whose payload release rates depend on the composition and concentration of the salt/acidic-methanol solutions

Drug Survival and Long-term Outcome of Tofacitinib in Patients with Alopecia Areata: A Retrospective Study

Several non-randomized clinical trials and retrospective studies have demonstrated encouraging efficacy and well-tolerated safety of tofacitinib in the treatment of alopecia areata. However, there are scarce data on a large cohort of patients with alopecia areata in long-term real-world practice. This single-centre, retrospective, observational cohort study included 126 patients with alopecia areata treated with tofacitinib between February 2021 and December 2022. The aims of this study are to evaluate drug survival, effectiveness and safety of tofacitinib for treatment of alopecia areata, and to identify potential factors influencing long-term outcomes. Median duration of treatment was 23.00 (interquartile range (IQR) 15.00, 47.25) weeks. Median all-cause survival time of 126 patients treated with tofacitinib was 44 weeks (95% confidence interval (95% CI) 36.3, 51.7), and the all-cause drug retention rate at 12 weeks, 24 weeks and 48 weeks were 90.0%, 66.4% and 42.3%, respectively. The most common reason for discontinuation was complete remission/satisfaction. A total of 80 patients treated with tofacitinib for over 6 months were included in the efficacy analysis, the overall complete response rate at 24 weeks was 33.8% (27/80). No life-threatening serious adverse events occurred. Sex is an independent risk factor in predicting patient outcomes. This real-world study confirmed the high effectiveness and acceptable safety profile of tofacitinib in alopecia areata, with a satisfactory drug survival rate, and provides supporting data for the clinical application of tofacitinib in Chinese patients with alopecia areata

Factors controlling Oiliness of Jurassic Lianggaoshan tight sands in central Sichuan Basin, SW China

By comprehensively analyzing oil-bearing and non-oil-bearing tight sandstone reservoir properties, pore structure characteristics and contact between source rock and reservoir, reservoir fluorescent photographs of typical wells of Jurassic Lianggaoshan Formation in central Sichuan Basin, the research tries to find out factors controlling the oiliness of the Jurassic Lianggaoshan tight sandstone reservoir. The oiliness of the Jurassic Lianggaoshan tight sandstone reservoir in central Sichuan Basin is controlled by the following factors: (1) The migration pathway between the source rock and reservoir: when there exist sandstone and mudstone transition zones with high mud content and poor physical property between the source rock and reservoir, without fracture connection, it is difficult for oil and gas to migrate into the overlying reservoir; (2) The reservoir physical property: if the reservoir contacts directly with source rock and has good physical properties, oil and gas can migrate and accumulate directly in the reservoir. (3) Development degree of fractures: when the reservoir physical properties are poor, rich fractures can improve porosity and permeability of the reservoir, oil and gas can still migrate and accumulate in the reservoir; if the reservoir physical property is poor and no fractures developed, oil and gas are difficult to migrate and accumulate in the reservoir. Based on the sedimentary and reservoir characteristics of Jurassic Lianggaoshan Formation in central Sichuan Basin and the distribution of source rocks, Yingshan-Guang'an and Hechuan-Baimiao-Luodu two favorable exploration zones are selected. Key words: central Sichuan Basin, Lianggaoshan Formation, tight oil, oiliness, migration pathway, controlling factor

Genome-Wide Identification of Cassava Glyoxalase I Genes and the Potential Function of <i>MeGLYⅠ-13</i> in Iron Toxicity Tolerance

Glyoxalase I (GLYI) is a key enzyme in the pathway of the glyoxalase system that degrades the toxic substance methylglyoxal, which plays a crucial part in plant growth, development, and stress response. A total of 19 GLYI genes were identified from the cassava genome, which distributed randomly on 11 chromosomes. These genes were named MeGLYI-1–19 and were systematically characterized. Transcriptome data analysis showed that MeGLYIs gene expression is tissue-specific, and MeGLYI-13 is the dominant gene expressed in young tissues, while MeGLYI-19 is the dominant gene expressed in mature tissues and organs. qRT-PCR analysis showed that MeGLYI-13 is upregulated under 2 h excess iron stress, but downregulated under 6, 12, and 20 h iron stress. Overexpression of MeGLYI-13 enhanced the growth ability of transgenic yeast under iron stress. The root growth of transgenic Arabidopsis seedlings was less inhibited by iron toxicity than that of the wild type (WT). Potted transgenic Arabidopsis blossomed and podded under iron stress, but flowering of the WT was significantly delayed. The GLYI activity in transgenic Arabidopsis was improved under both non-iron stress and iron stress conditions compared to the WT. The SOD activity in transgenic plants was increased under iron stress, while the POD and CAT activity and MDA content were decreased compared to that in the WT. These results provide a basis for the selection of candidate genes for iron toxicity tolerance in cassava, and lay a theoretical foundation for further studies on the functions of these MeGLYI genes