水杨酸处理诱导采后甜瓜抗坏血酸-还原型谷胱甘肽循环代谢清除过氧化氢的作用及机制

目的：研究抗坏血酸（ascorbic acid，AsA）-还原型谷胱甘肽（reduced glutathione，GSH）循环代谢在水杨酸处理采后甜瓜诱导的过量H2O2清除过程中的作用。方法：用4 mmol/L水杨酸浸泡‘玉金香’厚皮甜瓜10 min，测定处理后果实常温贮藏过程中丙二醛（malondialdehyde，MDA）含量，分析活性氧的积累水平、超氧化物歧化酶（superoxide dismutase，SOD）和过氧化氢酶（catalase，CAT）活力，以及AsA-GSH循环过程相关酶活力及产物和底物含量。结果：水杨酸处理降低了果实MDA含量，第10天处理组MDA含量较对照组降低14.6%；显著提高了果实O2－·的产生速率和H2O2含量（P＜0.05），其中处理后第2天O2－·的产生速率高出同期对照组的1.9 倍，第6天H2O2含量高出对照组果实29.7%；提高了果实SOD活力，但抑制了CAT活力，说明H2O2的清除可能是依赖于除酶促系统外的其他系统。此外，水杨酸处理提高了果实抗坏血酸过氧化物酶、单脱氢抗坏血酸过氧化物酶、脱氢抗坏血酸还原酶和谷胱甘肽还原酶的活力，增加了AsA和氧化型谷胱甘肽的含量，降低了脱氢抗坏血酸和GSH的含量。结论：水杨酸处理诱导了厚皮甜瓜果实的氧爆，抑制了MDA产生，由水杨酸诱导产生的过量H2O2主要依靠AsA-GSH循环系统清除。     

Plant Copper Amine Oxidases: Key Players in Hormone Signaling Leading to Stress-Induced Phenotypic Plasticity

Polyamines are ubiquitous, low-molecular-weight aliphatic compounds, present in living organisms and essential for cell growth and differentiation. Copper amine oxidases (CuAOs) oxidize polyamines to aminoaldehydes releasing ammonium and hydrogen peroxide, which participates in the complex network of reactive oxygen species acting as signaling molecules involved in responses to biotic and abiotic stresses. CuAOs have been identified and characterized in different plant species, but the most extensive study on a CuAO gene family has been carried out in Arabidopsis thaliana. Growing attention has been devoted in the last years to the investigation of the CuAO expression pattern during development and in response to an array of stress and stress-related hormones, events in which recent studies have highlighted CuAOs to play a key role by modulation of a multilevel phenotypic plasticity expression. In this review, the attention will be focused on the involvement of different AtCuAOs in the IAA/JA/ABA signal transduction pathways which mediate stress-induced phenotypic plasticity events.     

Granulation Tissue Enhanced with Aspirin and Omega-3 PUFAs as a Local Adjunct to the Surgical Treatment of Periodontitis

The topical application of aspirin and omega-3 polyunsaturated fatty acids (PUFAs) may trigger the resolution of inflammation by inducing the biosynthesis of pro-resolvers such as lipoxins and resolvins while also avoiding the side effects of systemic aspirin intake. This study assessed the effect of enhanced granulation tissue (EGT) on periodontal tissue regeneration through the local application of aspirin and omega-3 PUFAs directly to granulation tissue (GT) during periodontal surgery. This randomized controlled experiment assesses 38 pockets in 19 patients. In every patient, two similar intrabony periodontal defects are treated with an open flap debridement, one with EGT (GT extracted, enhanced with aspirin and omega-3 PUFAs, and replaced) and the other with standard GT removal. Clinical attachment level (CAL) and probing pocket depth (PPD) are assessed at baseline and 2 and 6 months after surgery. The experimental protocol (EGT) results in a greater CAL gain as compared to that in the controls at 6 months (p < 0.05), while PPD reduction is not affected. The retained GT does not compromise healing. EGT is proposed as a promising, inexpensive, and simple method that may improve the outcome of periodontal regenerative treatment. However, the described protocol requires optimization and further assessment. Practical Applications : The biosynthesis of mediators including resolvins and lipoxins triggered by aspirin and omega-3 PUFAs promote the resolution of inflammation, eventually leading to faster regeneration of inflamed tissues. While granulation tissue is a necessary component in wound healing, enhancing granulation tissue with aspirin and omega-3 PUFAs results in CAL gain in the surgical treatment of periodontal defects. Retained granulation tissue does not compromise periodontal healing. The EGT strategy is an inexpensive and simple method that may improve the clinical outcomes of regenerative periodontal procedures.     

Effect of low temperature crystallization on 58S bioactive glass sintering and compressive strength

Mesoporous glass 58S (60SiO₂, 36CaO, 4P₂O₅ mol.%) has excellent bioactivity, biocompatibility, and forms strong bonds with bone making it attractive for implants. Mesoporous bioactive glass 58S powder is typically consolidated through sintering in order to produce an implant with sufficient strength to withstand the in vivo loads. However, heating the glass often leads to crystallinity, which is undesirable because it can reduce bioactivity. Hence, there is a trade-off between minimising crystallinity and maximising glass strength. Even at relatively low temperatures, it has been suggested that segregation of calcium and phosphate from silica within the glass can lead to crystallization. In this work, we confirm the occurrence of low temperature segregation in bioactive glass 58S using electron microscopy with elemental mapping. We probe how segregation affects the material properties of post-sintered glasses via comparison to a glass where phase separation is prevented via addition citric acid to the parent sol.     

Phytic acid-assisted fabrication of superhydrophilic Ru 3D electrode for electrocatalytic hydrogenation of p-Nitrophenol

A superhydrophilic Ru-based 3D electrode, denoted as Ru-PA/NF, was fabricated under the assistance of phytic acid (PA) for electrocatalytic hydrogenation of p-Nitrophenol. PA serves as a multifunctional modulator to facilitate the dispersion of active Ru species in porous nickel foam (NF), meanwhile enhance the surface wettability as well as adjust the micromorphology. In alkaline media, the Ru-PA/NF electrode shows the PNP conversion of 94.68% and the PAP selectivity of 99% after 9 h, accompanied by the faraday efficiency (FE) of 73.15%. Over the superhydrophilic Ru-PA/NF the rate constant of PNP conversion into PAP is 2.62-times higher than that over the hydrophobic Ru/NF prepared without the aid of PA, and FE of Ru-PA/NF is 1.28-times higher than Ru/NF. This can be ascribed to intriguing features of Ru-PA/NF involving higher Ru loading, more exposed sites, superior electrolyte wetting along with faster charge transfer rate.     

Metal chlorides-promoted ammonia absorption of deep eutectic solvent

Ammonia is considered as a promising hydrogen or energy carrier. Ammonia absorption or adsorption is an important aspect for both ammonia removal, storage and separation applications. To these ends, a wide range of solid and liquid sorbents have been investigated. Among these, the deep eutectic solvent (DES) is emerging as a promising class of ammonia absorbers. Herein, we report a novel type of DES, i.e., metal-containing DESs for ammonia absorption. Specifically, the NH₃ absorption capacity is enhanced by ca. 18.1–36.9% when a small amount of metal chlorides, such as MgCl₂, MnCl₂ etc., are added into a DES composed of resorcinol (Res) and ethylene glycol (EG). To our knowledge, the MgCl₂/Res/EG (0.1:1:2) DES outperforms most of the reported DESs. The excellent NH₃ absorption performances of metal–containing DESs have been attributed to the synergy of Lewis acid–base and hydrogen bonding interactions. Additionally, good reversibility and high NH₃/CO₂ selectivity are achieved over the MgCl₂/Res/EG (0.1:1:2) DES, which enables it to be a potential NH₃ absorber for further investigations.     

Examining the Impact of Squaric Acid as a Crosslinking Agent on the Properties of Chitosan-Based Films

Hydrogels based on chitosan are very versatile materials which can be used for tissue engineering as well as in controlled drug delivery systems. One of the methods for obtaining a chitosan-based hydrogel is crosslinking by applying different components. The objective of the present study was to obtain a series of new crosslinked chitosan-based films by means of solvent casting method. Squaric acid—3,4-dihydroxy-3-cyclobutene-1,2-dione—was used as a safe crosslinking agent. The effect of the squaric acid on the structural, mechanical, thermal, and swelling properties of the formed films was determined. It was established that the addition of the squaric acid significantly improved Young’s modulus, tensile strength, and thermal stability of the obtained materials. Moreover, it should be stressed that the samples consisting of chitosan and squaric acid were characterized by a higher swelling than pure chitosan. The detailed characterization proved that squaric acid could be used as a new effective crosslinking agent.     

Material encapsulation in poly(methyl methacrylate) shell: A review

Material encapsulation is a relatively new technique for coating a micro/nanosize particle or droplet with polymeric or inorganic shell. Encapsulation technology has many applications in various fields including drug delivery, cosmetic, agriculture, thermal energy storage, textile, and self-healing polymers. Poly(methyl methacrylate) (PMMA) is widely used as shell material in encapsulation due to its high chemical stability, biocompatibility, nontoxicity, and good mechanical properties. The main approach for micro/nanoencapsulation of materials using PMMA as shell comprises emulsion-based techniques such as emulsion polymerization and solvent evaporation from oil-in-water emulsion. In the present review, we first focus on the encapsulation techniques of liquid materials with PMMA shell by analyzing the effective processing parameters influencing the preparation of PMMA micro/nanocapsules. We then describe the morphology of PMMA capsules in emulsion systems according to thermodynamic relations. The techniques to investigation of mechanical properties of capsule shell and the release mechanisms of core material from PMMA capsules were also investigated. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48039.     

硫磷混合酸溶样重铬酸钾容量法测定全铁

介绍了硫磷混合酸溶样重铬酸钾容量法测定矿石中铁含量的方法和步骤。重点讨论了一线生产中的质量控制。