Diet-Induced Gut Barrier Dysfunction Is Exacerbated in Mice Lacking Cannabinoid 1 Receptors in the Intestinal Epithelium

The gut barrier provides protection from pathogens and its function is compromised in diet-induced obesity (DIO). The endocannabinoid system in the gut is dysregulated in DIO and participates in gut barrier function; however, whether its activity is protective or detrimental for gut barrier integrity is unclear. We used mice conditionally deficient in cannabinoid receptor subtype-1 (CB₁R) in the intestinal epithelium (intCB1−/−) to test the hypothesis that CB₁Rs in intestinal epithelial cells provide protection from diet-induced gut barrier dysfunction. Control and intCB1−/− mice were placed for eight weeks on a high-fat/sucrose Western-style diet (WD) or a low-fat/no-sucrose diet. Endocannabinoid levels and activity of their metabolic enzymes were measured in the large-intestinal epithelium (LI). Paracellular permeability was tested in vivo, and expression of genes for gut barrier components and inflammatory markers were analyzed. Mice fed WD had (i) reduced levels of endocannabinoids in the LI due to lower activity of their biosynthetic enzymes, and (ii) increased permeability that was exacerbated in intCB1−/− mice. Moreover, intCB1−/− mice fed WD had decreased expression of genes for tight junction proteins and increased expression of inflammatory markers in LI. These results suggest that CB₁Rs in the intestinal epithelium serve a protective role in gut barrier function in DIO.     

COD测定方法的研究动态

从采用不同的氧化剂测定、寻找新的催化剂、样品消解方法的改进、在线监测仪器及与其他综合指标的相关关系等几个方面论述了化学需氧量测定方法的发展与研究现状.     

酚醛泡沫的燃烧行为及阻燃研究进展

酚醛泡沫因兼具优异的保温性能和阻燃性能在工程领域得到广泛应用,但其经高温燃烧后质量残留率很低,炭层疏松、强度低,离开火焰后还易出现阴燃现象。目前有关酚醛泡沫燃烧行为的研究大多集中在如何进一步提高酚醛泡沫塑料的阻燃等级或在改善其脆性的同时不降低固有的阻燃性能,还未见关于酚醛泡沫燃烧全过程行为的综述报道。文章介绍了酚醛泡沫在明火燃烧和阴燃状态的燃烧行为,分析了影响酚醛泡沫燃烧行为的因素,并总结了现有酚醛泡沫阻燃研究的进展。目前酚醛泡沫的燃烧行为及阻燃研究主要集中在泡沫的明火燃烧,对酚醛泡沫阴燃问题的研究重视不足,缺乏针对酚醛泡沫燃烧全过程的行为和机理探究。因此,提出应加大对酚醛泡沫阴燃行为的研究投入,注重对酚醛泡沫燃烧全过程的机理探索与阻燃方案研究,设计并研发出解决酚醛泡沫燃烧全过程问题的有效途径。     

TiAl基羰基硫水解催化剂的中毒机制与抗氧性能研究

高炉煤气脱硫是实现钢铁行业多工序全流程超低排放的关键。高炉煤气中主要有机硫组分是羰基硫（COS）,常用γ-Al₂O₃基催化剂水解脱除,但是其抗氧性能有待提高。采用共沉淀法制备了Ti_0.5Al和K_0.2Ti_0.5Al催化剂,考察了催化剂在含氧气氛下的COS水解催化性能,并分析了氧体积分数对COS转化率和H₂S产率的影响规律。活性测试结果表明,Ti_0.5Al催化剂的初始COS转化率接近90%,随着反应时间增长效率逐渐降低至60%以下;K_0.2Ti_0.5Al催化剂在0.5% （体积分数） O₂的气氛下持续反应22 h后,其COS转化率仍可保持在93.44%。表征结果显示,催化剂失活后比表面积大幅减小,表面碱性显著减弱。此外,活性中心Al原子硫酸化是导致催化剂失活的主要原因,而硫酸盐的沉积为次要原因。原位红外结果表明,K的引入可显著减弱O₂在催化剂表面的吸附,并且阻断中间过渡物种的氧化,这是K提高催化剂抗氧性能的关键。     

Hyperthermia Enhances Doxorubicin Therapeutic Efficacy against A375 and MNT-1 Melanoma Cells

Melanoma is the deadliest form of skin cancer, and its incidence has alarmingly increased in the last few decades, creating a need for novel treatment approaches. Thus, we evaluated the combinatorial effect of doxorubicin (DOX) and hyperthermia on A375 and MNT-1 human melanoma cell lines. Cells were treated with DOX for 24, 48, and 72 h and their viabilities were assessed. The effect of DOX IC10 and IC20 (combined at 43 °C for 30, 60, and 120 min) on cell viability was further analyzed. Interference on cell cycle dynamics, reactive oxygen species (ROS) production, and apoptosis upon treatment (with 30 min at 43 °C and DOX at the IC20 for 48 h) were analyzed by flow cytometry. Combined treatment significantly decreased cell viability, but not in all tested conditions, suggesting that the effect depends on the drug concentration and heat treatment duration. Combined treatment also mediated a G2/M phase arrest in both cell lines, as well as increasing ROS levels. Additionally, it induced early apoptosis in MNT-1 cells, while in A375 cells this effect was similar to the one caused by hyperthermia alone. These findings demonstrate that hyperthermia enhances DOX effect through cell cycle arrest, oxidative stress, and apoptotic cell death.     

有氧条件下生物过滤法脱氮研究

采用生物过滤法,以醋酸钠为外加碳源,探讨了有氧条件下反硝化脱氮的可行性。研究表明,通过向配制水中通入由N2 O2组成的合成气体,能方便地控制水体中溶解氧的浓度。在向配制水中通入含有少量O2的合成气后,系统中的溶解氧浓度下降比不通任何气体时下降还快。随着溶解氧含量逐渐提升,系统反硝化脱氮效果并未受到明显影响。当溶解氧达到6.4mg/L时,系统仍然具有反硝化作用,只是硝酸盐浓度下降速度比低溶解氧条件下缓慢,但是脱氮效率仍然可达85%左右。结果显示,采用生物过滤系统以及实验室培养得到的两种微生物,在一定溶解氧条件下,溶解氧对系统反硝化脱氮能力影响有限。     

CaO-MgO-Al2O3-SiO2 corrosion behavior of SrZrO3-La2Ce2O7 composite ceramics

In this work, the corrosion behavior, interaction products, and the corrosion mechanism of (1-x)SrZrO₃-xLa2Ce2O7(x = 0.3, S7L3; x = 0.5, S5L5; x = 0.7, S3L7) composite bulks after CaO-MgO-Al₂O₃-SiO₂ (CMAS) attack at 1250°C for 1, 4, and 12 h were investigated, respectively. The molten CMAS and the bulks rapidly interacted and generated a dense reaction layer, which mainly composed of La-Ce apatite, Ce₂Zr₂O_7.04, ZrO₂ with some Ce, Ca, Si, Mg, and Al elements preventing CMAS from continuous penetration effectively. The formation of CMAS self-crystallizing products such as Ca₂Al₂SiO₇ gehlenite and Mg-Al spinel with high melting points increased the viscosity of CMAS. The elements in the ceramic also diffused into the molten CMAS and formed Ce₂Zr₂O_7.04 and La₂Ce₂O₇, increasing the melt viscosity and blocking the penetration channel of the molten CMAS. The S5L5 bulk has the best corrosion resistance against CMAS attacks.     

Enhanced calcium–magnesium–aluminosilicate (CMAS) resistance of GdAlO3 (GAP) for composite thermal barrier coatings

The impact of calcium–magnesium–alumino-silicate (CMAS) degradation is a critical factor for development of new thermal and environmental barrier coatings. Several methods of preventing damage have been explored in the literature, with formation of an infiltration inhibiting reaction layer generally given the most attention. Gd₂Zr₂O₇ (GZO) exemplifies this reaction with the rapid precipitation of apatite when in contact with CMAS. The present study compares the CMAS behavior of GZO to an alternative thermal barrier coating (TBC) material, GdAlO₃ (GAP), which possesses high temperature phase stability through its melting point as well as a significantly higher toughness compared with GZO. The UCSB laboratory CMAS (35CaO–10MgO–7Al₂O₃–48SiO₂) was utilized to explore equilibrium behavior with 50:50 mol% TBC:CMAS ratios at 1200, 1300, and 1400°C for various times. In addition, 8 and 35 mg/cm² CMAS surface exposures were performed at 1425°C on dense pellets of each material to evaluate the infiltration and reaction in a more dynamic test. In the equilibrium tests, it was found that GAP appears to dissolve slower than GZO while producing an equivalent or higher amount of pore blocking apatite. In addition, GAP induces the intrinsic crystallization of the CMAS into a gehlenite phase, due in part to the participation of the Al₂O₃ from GAP. In surface exposures, GAP experienced a substantially thinner reaction zone compared with GZO after 10 h (87 ± 10 vs. 138 ± 4 μm) and a lack of strong sensitivity to CMAS loading when tested at 35 mg/cm² after 10 h (85 ± 13 versus 246 ± 10 μm). The smaller reaction zone, loading agnostic behavior, and intrinsic crystallization of the glass suggest this material warrants further evaluation as a potential CMAS barrier and inclusion into composite TBCs.     

Phase evolution and thermophysical properties of high-entropy RE2(Y0.2Yb0.2Nb0.2Ta0.2Ce0.2)2O7 oxides

Pursuing novel thermal barrier–coating materials with lower thermal conductivity and high-temperature stability can simultaneously improve the working efficiency and service temperature of a gas turbine. In this study, a series of high-entropy RE₂(Y_0.2Yb_0.2Nb_0.2Ta_0.2Ce_0.2)₂O₇ (RE = La, Nd, Sm, Gd, Dy, and Er) oxides were prepared though solid-state reaction. Through tuning the rare-earth cations, an order–disorder transition occurs from certain partially ordered weberite structure (C222₁) to disordered defective fluorite structure (Fm$\overline{3}$m). All the high-entropy RE₂(Y_0.2Yb_0.2Nb_0.2Ta_0.2Ce_0.2)₂O₇ oxides possess low thermal conductivity in the range of 0.91–1.34 W m⁻¹ K⁻¹ at room temperature, which can be attributed to increased lattice anharmonicity and disorder, resulting in additional phonon scattering. Herein, we proved that the incorporation of heterovalent cations at B-sites in high-entropy A₂B₂O₇ crystals is an effective strategy to reduce the thermal conductivity without compromising the decrease of oxygen vacancy. Moreover, the high-entropy RE₂(Y_0.2Yb_0.2Nb_0.2Ta_0.2Ce_0.2)₂O₇ oxides show the relatively higher thermal expansion coefficients of 10.3–10.7 × 10⁻⁶°C⁻¹ and excellent phase stability at elevated temperatures.     

Thermal shock resistance of thermal barrier coatings modified by selective laser remelting and alloying techniques

Aiming to improve the thermal shock resistance of thermal barrier coatings (TBCs), the plasma-sprayed 7YSZ TBCs were modified by selective laser remelting and selective laser alloying, respectively, in this study. A self-healing agent TiAl₃ was introduced into the 7YSZ TBCs by selective laser alloying to fill cracks during thermal cycling. The thermal shock experiments of the plasma-sprayed, laser-remelted, and laser-alloyed TBCs were conducted by a means of heating and water-quenching method. Results revealed that some segmented microcracks were distributed on the surface of the laser-remelted and the laser-alloyed zones, showing a dense columnar crystal structure. After thermal shock tests, the numbers of segmented microcracks on the laser-remelted coating increased, whereas, in the laser-alloyed condition, some irregular particles formed, leading to the decreased numbers of segmented microcracks. The laser-alloyed coating exhibited the best thermal shock resistance, followed by the laser-remelted condition, with the thermal shock lifetime 3.3 and 2.7 times higher than that of the as-sprayed coating, respectively. On the one hand, both columnar grains and segmented microcracks in the laser-treated zone could effectively improve the strain tolerance of coatings. On the other hand, the oxidation products of TiAl₃ under high-temperature condition could seal the microcracks to postpone the crack connection. Thus, the thermal shock resistance of the laser-treated coatings was significantly improved.