Anti-Cracking TEOS-Based Hybrid Materials as Reinforcement Agents for Paper Relics.

Tetraethoxysilane (TEOS) is the most commonly used silicon-based reinforcement agent for conserving art relics due to its cost-effectiveness and commercial maturity. However, the resulting silica gel phase is prone to developing cracks as the gel shrinks during the sol-gel process, potentially causing severe damage to the objects being treated. In this study, dodecyltrimethoxysilane (DTMS) was introduced into TEOS to minimize this shrinkage by adding elastic long chains to weaken the capillary forces. The gel formed from the DTMS/TEOS hybrid material was transparent and crack-free, featuring a dense microstructure without mesopores or micropores. It exhibited excellent thermal stability, with a glass transition temperature of up to 109.64 °C. Evaluation experiments were conducted on artificially aged, handmade bamboo paper. The TEOS-based hybrid material effectively combined with the paper fibers through the sol-gel process, polymerizing into a network structure that enveloped the paper surface or penetrated between the fibers. The surface of the treated paper displayed excellent hydrophobic properties, with no significant changes in appearance, color, or air permeability. The mechanical properties of the treated bamboo paper improved significantly, with longitudinal and transverse tensile strengths increasing by up to 36.63% and 44.25%, respectively. These research findings demonstrate the promising potential for the application of DTMS/TEOS hybrid materials in reinforcing paper relics.

Lycium barbarum polysaccharides attenuate cardiovascular oxidative stress injury by enhancing the Keap1/Nrf2 signaling pathway in exhaustive exercise rats.

Moderate exercise is beneficial to physical and mental health. When the amount of exercise and exercise intensity exceeds a certain limit and reaches the state of exhaustion, oxidative stress levels in the body increase, which can lead to oxidative stress­associated damage. Lycium barbarum polysaccharide (LBP) is one of the primary active ingredients extracted from wolfberry. Following exhausting exercise in rats, LBP supplements decrease damage to the myocardium and blood vessels, indicating that LBP exerts a protective effect on the cardiovascular system. The Kelch­like ECH­associated protein 1 (Keap1)/NF­E2­related factor 2 (Nrf2) anti­oxidative stress signaling pathway improves total oxidizing ability; anti­apoptosis and other aspects serve a vital role. In the present study, LBP intervention was performed in vivo and in vitro to observe its effect on the Keap1/Nrf2 pathway and oxidative stress­associated indicators in order to clarify its protective mechanism. For the in vivo experiments, 60 male Sprague­Dawley rats were randomly divided into normal control and aerobic, exhaustive and exhaustive exercise + LBP (200 mg/kg/day) groups. For the in vitro experiments, a rat thoracic aortic endothelial cell (RTAEC) oxidative stress model was established using angiotensin II (AngII) and divided into blank control, LBP (3,200 µg/ml), AngII (1x10­4 mol/l) and AngII + LBP groups. For in vitro experiments, small interfering (si)RNA (50 nmol) was used to transfect RTAEC and induce gene silencing of Nrf2. ELISA, hematoxylin and eosin staining, TUNEL, immunofluorescence, western blotting, immunohistochemistry and reverse transcription­quantitative PCR were used to evaluate and verify the effect of LBP on oxidative stress indicators and the expression of Keap1/Nrf2 antioxidative stress signaling pathway. The in vivo experiments showed that LBP decreased the expression of serum malondialdehyde (MDA) and AngII, as well as apoptosis of blood vessels and cardiomyocytes and expression of TNF­α in rats following exhaustive exercise. Meanwhile, LBP enhanced expression of the Keap1/Nrf2 signaling pathway and downstream associated protein glutamyl­cysteine synthetase catalytic subunit (GCLC), quinone oxidoreductase 1 (NQO1) and glutamate­cysteine ligase modified subunit (GCLM) in the thoracic aorta and myocardium of rats following exhaustive exercise. In RTAEC in vitro, LBP decreased the expression of MDA and TNF­α in the supernatant, promoted the nuclear translocation of Nrf2 and increased expression levels of GCLC, NQO1 and GCLM. Following siNrf2 transfection into endothelial cells, the anti­inflammatory and antioxidant stress effects of LBP were decreased. LBP was found to enhance the expression of the Keap1/Nrf2 antioxidant stress signaling pathway in endothelial cells, decreasing oxidative stress and the inflammatory response. Moreover, LBP improved the antioxidant stress ability of endothelial cells and alleviated injury of myocardial vascular tissue, thereby protecting the cardiovascular system.

Effects of varying intensities of heat stress on neuropeptide Y and proopiomelanocortin mRNA expression in rats.

The aim of the present study was to investigate the effects of varying intensities of heat stress on the mRNA expression levels of neuropeptide Y (NPY), proopiomelanocortin (POMC) and stress hormones in rats. To establish a rat model of heat stress, the temperature and time were adjusted in a specialized heating chamber. Sprague-Dawley (SD) rats were randomly divided into four groups; control (CN; temperature, 24±1˚C); moderate strength 6 h (MS6; temperature, 32±1˚C time, 6 h), moderate strength 24 h (MS24; temperature, 32±1˚C; time, 24 h) and high strength 6 h (HS6; temperature, 38±1˚C; time, 6 h) groups. SD rats were exposed to heat for 14 consecutive days. The levels of heat stress-related factors, including corticotropin-releasing hormone (CRH), cortisol (COR), epinephrine (EPI) and heat shock protein 70 (HSP70), were measured in the rat blood using ELISA. In addition, the weight of the spleen, thymus, hypophysis and hypothalamus were determined. The mRNA expressions levels of NPY and POMC were detected using quantitative PCR. The results showed that the CRH, COR and HSP70 levels were increased in the three heat stress groups compared with the CN group. Notably, the levels of CRH, EPI and HSP70 were increased in the HS6 group compared with the CN and MS6 groups (P<0.05). Furthermore, the weights of the hypophysis and hypothalamus in the HS6 group were significantly lower compared with the CN group (P<0.05). In addition, NPY and POMC expression levels were downregulated in the MS24 group compared with the CN group. The mRNA expression levels of NPY and POMC were altered in response to different intensities of heat stress. Therefore, their levels were downregulated and upregulated following long-time and moderate-time heat exposure, respectively. The results of the present study suggested that the reduced mRNA expression levels of NPY may be partially responsible for the heat-induced injuries in rats following long-time heat exposure.