Is a Vitrimer with a High Glass Transition Temperature Available? A Case Study on Rigid Polyimides Cross-Linked with Dynamic Ester Bonds.

Vitrimers, possessing associative covalent adaptable networks, are cross-linked polymers exhibiting malleable (glass-like) feature and recyclable and reprocessable (thermoplastics-like) properties. The dynamic behaviors of vitrimer are dependent on both chain/molecular mobility (glass transition temperature, Tg) and dynamic bond-exchanging reaction rate (topology freezing transition temperature, Tv). This work aims on probing the effect of high Tg on the stress relaxation and physical recyclability of vitrimers, employing a polyimide cross-linked with dynamic ester bonds (Tg: 310 °C) as the example. Due to its high Tg and chain rigidity, the cross-linked polyimide does not exhibit a high extent of stress relaxation behavior at 320 °C (10 °C above its Tg), even though the temperature is much higher than the hypothetical Tv. While raising the processing temperature to 345 °C, the cross-linked polyimide exhibits a stress relaxation time of about 3300 s and physical malleability. Nevertheless, side reactions may occur in the recycling and reprocessing process under the harsh condition (high temperature and high pressure) to alter the thermal properties of the recycled sample. The diffusion control plays a critical role on the topography transition of a vitrimer having a high Tg. The Tg ceiling is noticeable for developments of vitrimers.

Urban/Rural Disparity in Quality of Life among the Older Adults in China: Mediation Effect of Leisure Activity.

The current study revisits the urban/rural quality of life (QOL) disparity among the older adults in China. It aims to test the potential leisure activity mechanism. Data for this study come from the 2011 and 2014 wave of Chinese Longitudinal Healthy Longevity Survey (CLHLS). Sample is restricted to the respondents who are 65 years old and older who are alive for both waves. Ordered logistic regression model is used to test the relationship between QOL and urban/rural residency. Mediation test is used to investigate the mediation effect of leisure activities. Findings from the analysis show that urban older adults have higher QOL, as well as higher frequency of participating leisure activities compare to their rural counterparts. Results also show that leisure activities, especially the cognitive stimulation activities mediate the relationship between urban/rural residency and QOL. The current study adds the role of leisure activities as an intervening variable between urban/rural residency and QOL among older adults in China. Policy application to reduce the QOL disparity through leisure activities is also discussed.

Reaction between 1,3,5-Triisopropylbenzene and Elemental Sulfur Extending the Scope of Reagents in Inverse Vulcanization.

Inverse vulcanization utilizes an organic compound as reagent for crosslinking elemental sulfur to result in corresponding polymeric material with a high sulfur content. This work, employing 1,3,5-triisopropylbenzene (TIPB) as the reagent, demonstrates the first attempt on extending the scope of crosslinking agents of inverse vulcanization to saturate compounds. Under nuclear magnetic spectroscopic analysis, the reactions between TIPB and elemental sulfur take places through ring-opening reaction of S8 resulting in sulfur radicals at sulfur chain ends, radicals transferring to isopropyl groups of TIPB, and radical coupling reactions between carbon radicals and sulfur radicals. The obtained products are similar to the sulfur polymers from conventional inverse vulcanization processes and show self-healing property.

LncRNA CARMN facilitates odontogenic differentiation of dental pulp cells by impairing EZH2.

OBJECTIVE: This study aimed to reveal the potential role of CARMN in odontogenic differentiation of dental pulp cells (DPCs). METHODS: Laser capture microdissection was used to detect Carmn in DPCs and odontoblasts in P0 mice. After manipulating CARMN expression in odontogenic differentiation induced hDPCs, the state of odontogenic differentiation was evaluated by ALP staining, ARS, and related marker expression in qRT-PCR and western blotting. The subcutaneous transplantation of HA/ß-TCP loaded with hDPCs was performed to verify CARMN's role in promoting odontogenic differentiation in vivo. RNAplex and RIP were employed to reveal potential mechanism of CARMN in hDPCs. RESULTS: CARMN expressed more abundantly in odontoblasts than DPCs in P0 mice. CARMN expression boosted during in vitro odontogenic differentiation of hDPCs. CARMN overexpression enhanced odontogenic differentiation of hDPCs in vitro, while inhibition impaired the process. CARMN overexpression in HA/ß-TCP composites promoted more mineralized nodule formation in vivo. CARMN knockdown led to soared EZH2, while CARMN overexpression brought about EZH2 inhibition. CARMN functioned via direct interaction with EZH2. CONCLUSIONS: The results uncovered CARMN as a modulator during the odontogenic differentiation of DPCs. CARMN promoted odontogenic differentiation of DPCs by impairing EZH2.

Does Religious Participation Predict Future Expectations About Health? Using a Life Course Framework to Test Multiple Mechanisms.

Though an impressive array of health outcomes has been studied, research within the field of religion and health has not yet considered how religious involvement may affect future expectations about health. This is a significant shortcoming because the teachings of many religions direct adherent's focus to the distant future, and future self-ratings of health are a known predictor of subjective life expectancy and eventual mortality risk. Recognizing the need for a life course approach to conceptualizing patterns of religious involvement, we assess how stability or change in religious attendance from childhood to adulthood structures individual expectations of future health. Drawing on data from the 2017 Values and Beliefs of the American Public Study (Baylor Religion Survey Wave 5), we find that stable high (weekly) attendance between childhood and adulthood is associated with higher future health expectations. Parametric mediation analyses conducted in the counterfactual framework suggest that this association is explained by the tendency of frequent stable attenders to have (a) higher levels of beliefs in the sense of divine control and (b) a lower likelihood of engaging in harmful health behaviors (smoking).

Sulfur Radical Transfer and Coupling Reaction to Benzoxazine Groups: A New Reaction Route for Preparation of Polymeric Materials Using Elemental Sulfur as a Feedstock.

A novel approach to preparing polymeric materials using elemental sulfur as a feedstock through the newly developed sulfur radical transfer and coupling (SRTC) reaction is reported herein. Polybenzoxazines with high sulfur contents are prepared using the SRTC reaction with benzoxazine compounds as the radical acceptors. The reactions between elemental sulfur and benzoxazine rings are analyzed with Fourier transform infrared (FTIR), 1 H NMR, and 13 C DEPT spectroscopies to elucidate the SRTC reaction mechanism. Moreover, the prepared polybenzoxazine-sulfur hybrid materials show attractive repairing properties based on the dynamic S-S linkages. An effective reaction mechanism and the prepared repairable sulfur-possessing polymeric materials are demonstrated.

Reactive Hybrid of Polyhedral Oligomeric Silsesquioxane (POSS) and Sulfur as a Building Block for Self-Healing Materials.

This work demonstrates a new reactive and functional hybrid (S-MMA-POSS) of polyhedral oligomeric silsesquioxane (POSS) and sulfur prepared with a direct reaction between a multifunctional methacrylated POSS compound (MMA-POSS) and elemental sulfur (S8 ) through the "inverse vulcanization" process. S-MMA-POSS is an effective building block for imparting self-healing ability to the corresponding thermally crosslinked POSS-containing nanocomposites through a self-curing reaction and co-curing reaction with conventional thermosetting resins. Moreover, S-MMA-POSS is also a useful precursor for preparation of materials with high transparency in mid-infrared region.

2,2,6,6-Tetramethylpiperydinyl-1-oxyl (TEMPO) Functionalized Benzoxazines Prepared with a One-Pot Synthesis for Reactive/Crosslinkable Initiators of Nitroxide Mediated Polymerization.

In this work, the incorporation of a 2,2,6,6-tetramethylpiperydinyl-1-oxyl (TEMPO) group to a benzoxazine ring is performed using a one-pot synthesis for the preparation of TEMPO-functionalized benzoxazine compounds and polymers as reactive and crosslinkable initiators for nitroxide-mediated polymerization (NMP). The TEMPO-functionalization reaction of benzoxazine, traced with 1 H NMR, is conducted with sequential radical transfer and coupling reactions. Moreover, polystyrene-grafted polybenzoxazine copolymers are prepared with the TEMPO-benzoxazine initiator and NMP of styrene. The polymerization system exhibits the characteristics of controlled radical polymerization, including controlled molecular weights of products and ability for sequential polymerization. Moreover, based on the chemical reactivity and crosslinking ability of benzoxazine groups, the synthesis route developed in this work will widen the scope of the design and synthesis of functional and high-performance polymers.

A Cocatalytic Effect between Meldrum's Acid and Benzoxazine Compounds in Preparation of High Performance Thermosetting Resins.

In this work, a cocatalytic effect between Meldrum's acid (MA) and benzoxazine (Bz) compounds has been explored to build up a self-promoting curing system. Consequently, the MA/Bz reactive blend exhibits a relatively low reaction temperature compared to the required temperatures for the cross-linking reactions of the pure MA and Bz components. This feature is attractive for energy-saving processing issues. Moreover, the thermosetting resins based on the MA/Bz reactive blends have been prepared. The MA component can generate additional free volume in the resulting resins, so as to trap air in the resin matrix and consequently to bring low dielectric constants to the resins. The MA-containing agent is an effective modifier for benzoxazine resins to reduce their dielectric constants.

Radical and Atom Transfer Halogenation (RATH): A Facile Route for Chemical and Polymer Functionalization.

This work demonstrates a new halogenation reaction through sequential radical and halogen transfer reactions, named as "radical and atom transfer halogenation" (RATH). Both benzoxazine compounds and poly(2,6-dimethyl-1,4-phenylene oxide) have been demonstrated as active species for RATH. Consequently, the halogenated compound becomes an active initiator of atom transfer radical polymerization. Combination of RATH and sequential ATRP provides an convenient and effective approach to prepare reactive and crosslinkable polymers. The RATH reaction opens a new window both to chemical synthesis and molecular design and preparation of polymeric materials.

Direct formation of S-nitroso silica nanoparticles from a single silica source.

Nitric oxide (NO) is a ubiquitous molecule in the body. Because of its multiple pathophysiologic roles, the potential for treating various diseases by the exogenous administration of NO has been under intensive investigation. However, the unstable, radical nature of NO poses a major challenge to the effective delivery of NO. Previously, silica nanoparticles synthesized by the traditional method have been developed into NO-carrying systems. In the present study, for the first time NO-carrying silica nanoparticles were prepared from a single silica precursor using a simple nanoprecipitation method. (3-Mercaptopropyl)-trimethoxysilane (MPTMS) was used as the sole silane source, which was subjected to acid-catalyzed S-nitrosation and condensation reactions in a one-pot organic phase. S-Nitroso silica nanoparticles (SNO-SiNPs) were then produced by injecting a smaller quantity of the organic phase into a larger amount of water without surfactants. Various preparation parameters were tested to obtain optimized conditions. Moreover, a phase diagram demonstrating the ouzo effect was constructed. The prepared SNO-SiNPs were spherical particles with a tunable size in the range of 100-400 nm. The nanoparticles in aqueous dispersions exhibited high colloid stability, possibly resulting from highly negatively charged surfaces. The result of solid-state (29)Si NMR shows the predominance of T(2) and T(3) silicon structures, suggesting that nanoparticles were formed from polycondensed silica species. In conclusion, NO-loaded silica nanoparticles have been directly prepared from a single silane precursor using a surfactant-free, low-energy, one-step nanoprecipitation approach. The method precludes the need for the initial formation of bare particles and subsequent functionalization steps.

Versatile synthesis of thiol- and amine-bifunctionalized silica nanoparticles based on the ouzo effect.

In this article, we report a novel, nanoprecipitation-based method for preparing silica nanoparticles with thiol and amine cofunctionalization. (3-Mercaptopropyl)trimethoxysilane (MPTMS) and 3-aminopropyltrimethoxysilane (APTMS) were used as the organosilane precursors, which were subjected to acid-catalyzed polycondensation in an organic phase containing a water-miscible solvent (e.g., dimethyl sulfoxide). A pale colloidal solution could be immediately formed when the preincubated organic phase was directly injected into water. The initial composition ratio between MPTMS and APTMS is an important factor governing the formation of nanoparticles. Specifically, large, unstable micrometer-sized particles were formed for preparation using MPTMS as the sole silane source. In contrast, when APTMS was used alone, no particles could be formed. By reducing the fraction of APTMS (or increasing that of MPTMS) in the initial mixture of organosilanes, the formation of nanometer-sized particles occurred at a critical fraction of APTMS (i.e., 25%). Remarkably, a tiny fraction (e.g., 1%) of APTMS was sufficient to produce stable nanoparticles with a hydrodynamic diameter of about 200 nm. Other factors that would also affect particle formation were determined. Moreover, an interesting temperature effect on particle formation was observed. The TEM micrographs show spherical nanospheres with mean sizes of 130-150 nm in diameter. The solid-state (29)Si NMR spectra demonstrate that the hybrid silica materials contain fully and partially condensed silicon structures. The bifunctionalized silica nanoparticles have positive zeta potentials whose magnitudes are positively correlated with the amount of APTMS. The total thiol content, however, is negatively correlated with the amount of APTMS. The cationic nanoparticles can bind an antisense oligonucleotide in a composition-dependent manner.

Depression, anxiety, and stress among vocational college students during the initial stage of post-epidemic era: A cross-sectional study.

The purpose of this study was to assess the prevalence and sociodemographic determinants of depression, anxiety, and stress among vocational college students. 1255 students participated in the cross-sectional study. The Chinese version of the 21-item the Depression Anxiety Stress Scales (DASS-21) was used. Depression was reported in 37.6% of vocational college students, anxiety in 51.6%, and stress in 38.1%. Logistic regression results showed that a higher degree of depression, anxiety, and stress was associated with female, poor and moderate self-rated health status, from other provinces, poor self-rated family financial status and living off campus (P < .05). Junior and from one-parent or parentless family were more likely to experience depression and stress (P < .05). Additionally, the likelihood of having depression was higher in non-only-child students (P < .01) and rural family location was a risk factor for stress (P < .001). A higher prevalence of depression, anxiety, and stress was found in vocational college students. Timely and targeted psychological interventions should be taken.

LARP4B promotes hepatocellular carcinoma progression and impairs sorafenib efficacy by activating SPINK1-mediated EGFR pathway.

La-related proteins (LARPs) regulate gene expression by binding to RNAs and exhibit critical effects on disease progression, including tumors. However, the role of LARP4B and its underlying mechanisms in the progression of hepatocellular carcinoma (HCC) remain largely unclear. In this study, we found that LARP4B expression is upregulated and correlates with poor prognosis in patients with HCC. Gain- and loss-of-function assays showed that LARP4B promotes stemness, proliferation, metastasis, and angiogenesis in vitro and in vivo. Furthermore, LARP4B inhibition enhances the antitumor effects of sorafenib and blocks the metastasis-enhancing effects of low sorafenib concentrations in HCC. Mechanistically, LARP4B expression is upregulated by METTL3-mediated N6-methyladenosine (m6A)-IGF2BP3-dependent modification in HCC. RNA- and RNA immunoprecipitation (RIP)- sequencing uncovered that LARP4B upregulates SPINK1 by binding to SPINK1 mRNA via the La motif and maintaining mRNA stability. LARP4B activates the SPINK1-mediated EGFR signaling pathway, which supports stemness, progression and sorafenib resistance in HCC. Additionally, a positive feedback loop with the LARP4B/SPINK1/p-AKT/C/EBP-ß axis is responsible for the sorafenib-therapeutic benefit of LARP4B depletion. Overall, this study demonstrated that LARP4B facilitates HCC progression, and LARP4B inhibition provides benefits to sorafenib treatment in HCC, suggesting that LARP4B might be a potential therapeutic target for HCC.

Photoluminescent toroids formed by temperature-driven self-assembly of rhodamine B end-capped poly(N-isopropylacrylamide).

In this paper, self-assembled polymeric toroids formed by a temperature-driven process are reported. Rhodamine B (RhB) end-capped poly(N-isopropylacrylamide) (PNIPAAm) demonstrating a lower critical solution temperature (LCST) is prepared. In a two-phase system, the polymer in the aqueous phase could move to the chloroform phase on raising the temperature above its LCST. This temperature-driven process results in the formation of polymeric toroids in the chloroform phase, and the strategy affords a new pathway to toroidal self-assembly of polymers. Moreover, the photoluminescent behavior of the RhB end-capped PNIPAAm species formed by the process is also studied and discussed.

Marital Strain and Support and Subjective Well-Being in Later Life: Ascribing a Role to Childhood Adversity.

Objectives: We integrate the life course perspective with the stress-process model to offer a framework for how childhood conditions moderate the relationship between marital support/strain and subjective well-being in older adulthood for men and women. Methods: Drawing on longitudinal data from the National Social Life, Health, and Aging Project (NSHAP), we use a series of lagged dependent-variable models and stratify the sample by gender. Results: Our results suggest that the benefits associated with greater marital support are stronger for those that did not live with both parents in childhood for men. Women raised in families that experienced financial hardship reported lower subjective well-being in the context of marital strain. Conclusion: Adverse experiences in childhood can be scarring or foster resilience related to well-being in the context of strained or supportive marriages.

Hemocompatibility of poly(vinylidene fluoride) membrane grafted with network-like and brush-like antifouling layer controlled via plasma-induced surface PEGylation.

In this work, the hemocompatibility of PEGylated poly(vinylidene fluoride) (PVDF) microporous membranes with varying grafting coverage and structures via plasma-induced surface PEGylation was studied. Network-like and brush-like PEGylated layers on PVDF membrane surfaces were achieved by low-pressure and atmospheric plasma treatment. The chemical composition, physical morphology, grafting structure, surface hydrophilicity, and hydration capability of prepared membranes were determined to illustrate the correlations between grafting qualities and hemocompatibility of PEGylated PVDF membranes in contact with human blood. Plasma protein adsorption onto different PEGylated PVDF membranes from single-protein solutions and the complex medium of 100% human plasma were measured by enzyme-linked immunosorbent assay (ELISA) with monoclonal antibodies. Hemocompatibility of the PEGylated membranes was evaluated by the antifouling property of platelet adhesion observed by scanning electron microscopy (SEM) and the anticoagulant activity of the blood coagulant determined by testing plasma-clotting time. The control of grafting structures of PEGylated layers highly regulates the PVDF membrane to resist the adsorption of plasma proteins, the adhesion of platelets, and the coagulation of human plasma. It was found that PVDF membranes grafted with brush-like PEGylated layers presented higher hydration capability with binding water molecules than with network-like PEGylated layers to improve the hemocompatible character of plasma protein and blood platelet resistance in human blood. This work suggests that the hemocompatible nature of grafted PEGylated polymers by controlling grafting structures gives them great potential in the molecular design of antithrombogenic membranes for use in human blood.

Marital Quality and Well-Being Among Older Adults: A Typology of Supportive, Aversive, Indifferent, and Ambivalent Marriages.

A large body of work has linked marital quality to the health and well-being of older adults, but there is a lack of agreement on how to best measure dimensions of marital quality. Drawing on a stress-process life course perspective, we construct a typology of marriage type that captures the synergistic relationship between positive and negative marital qualities and health. Using data from Wave 1 (2005/2006) and Wave 2 (2010/2011) of the NSHAP survey from the United States, we examine the association between supportive, aversive, ambivalent, and indifferent marriages for older adults that remained married over the study period on multiple indicators of well-being (depression, happiness, and self-rated health; N = 769 males and 461 females). Results suggest that older adults in aversive marriages reported lower happiness (men and women) and physical health (men). There was less evidence that those in ambivalent and indifferent marriages reported worse well-being.

CST1 Promoted Gastric Cancer Migration and Invasion Through Activating Wnt Pathway.

INTRODUCTION: Gastric cancer is one of the main reasons of cancer-induced death, exploring the molecular mechanisms of gastric cancer progression is critical for gastric cancer therapy. Here, we studied the role of cysteine protease inhibitor CST1 in gastric cancer progression. METHODS: Matrigel-coated or -uncoated transwell assay was used to determine the effect of CST1 on gastric cancer invasion and migration, luciferase reporter system was used to determine the effect of CST1 on Wnt pathway activity. RESULTS: CST1 had high expression levels in gastric cancer tissues and cells, patients who had high CST1 expression had poor outcome. Overexpression of CST1 increased gastric cancer migration and invasion, while knockdown of CST1 suppressed gastric cancer migration invasion. Mechanism analysis showed CST1 promoted WNT signaling pathway activity, promoted the nuclear translocation of ß-catenin and the expression of Wnt signaling targets. Inhibition of Wnt pathway in CST1 overexpression cells inhibited migration and invasion, suggesting CST1 promoted gastric cancer cell migration and invasion through activating the Wnt pathway. CONCLUSION: In summary, we found CST1 promoted gastric cancer migration and invasion through activating Wnt signaling, providing a novel target for gastric cancer therapy.

Effect on thermal stability of microstructure and morphology of thermally-modified electrospun fibers of polybenzoxazines (PBz) blended with sulfur copolymers (SDIB).

Simple modification by thermal treatment is the commonly used approach to enhance the performance of electrospun fibers. This was investigated in the thermal treatment of polybenzoxazine (PBz) fibers blended with sulfur copolymers (SDIB) to determine the effect of varying treatment conditions on the microstructure and morphology of PBz fibers with the effect of incorporating sulfur functional groups on resulting properties. Mechanical properties of PBz are greatly improved by thermally-induced ring-opening polymerization (ROP) of the oxazine ring. Blending with sulfur copolymers (SDIB) could have beneficial effects on endowed features on fibers but could also affect the resulting properties of SDIB-blended PBz fibers during crosslinking reactions. Fiber mats were fabricated by electrospinning of PBz (10 wt%) blended with SDIB (10 wt%). Physical modification with varying conditions of sequential thermal treatment were evaluated and compared to the conditions applied on pristine PBz fibers. Changes in morphology and microstructure of fibers after modification were analyzed through scanning electron microscopy (SEM) while elemental compositions were identified after varying the conditions of thermal treatment. Adjustment of treatment conditions using two-step temperature sequential thermal treatment with higher temperatures of 160 °C and 240 °C showed significant changes in microstructure and morphology of fibers. Lower temperatures of 120 °C and 160 °C exhibited microstructure and morphology of fibers which affected the fiber diameter and fiber networks. Cross-sectional SEM images also confirmed the adversed effect of high-temperature treatment conditions on fibrous structures while low-temperature treatment retained the fibrous structures with more compact and stiff fiber networks. SDIB-blended PBz fibers were also evaluated by TGA and DSC to correlate the changes in structure and morphology with the thermal stability and integrity of blended SDIB/PBz fibers as compared to pristine PBz with the effect of change in treatment conditions. Fiber strength indicated slower weight loss for blended fibers and higher onset temperature of degradation which resulted in more thermally stable fibers.