Effects of C5-substituent group on the hydrogen peroxide-mediated tautomerisation of protonated cytosine: a theoretical perspective

The direct tautomerism (path A) and H₂O₂ as a catalyst (path B) have been studied in conversion of Cyt2t⁺ into CytN3⁺ isomer. The protonated 5-carboxycytosine (5-caCyt) is represented and has been further explored in the presence of H₂O₂ (path C). In going from a four-membered-ring transition state in the case of the direct tautomerism to the six-membered ring for H₂O₂, the H₂O₂ significantly contributes to decreasing the free energy barrier of tautomerisation. Although the carboxylic substituent of 5-carboxycytosine has certain affected on the electron distribution of the pyrimidine ring, the six-membered-ring transition state has not changed. This result illustrates that the C5-carboxylation has no significant effect on the H₂O₂-mediated isomerisation of Cyt2t⁺ to CytN3⁺ isomer. Meanwhile, these paths A–C have been further explored in the presence of two water molecules. Use of implicit solvent models (PCM) does not significantly alter the energetics of water-mediated paths A–C compared to those in gas phase. Furthermore, the rate constant with Wigner tunnelling correction of path A is obviously smaller than those of paths B and C. Finally, the lifetime τ_99.9% of paths B and C is 10^?5 s, which is implemented by the mechanism of the concerted synchronous double proton transfer.     

Intracellular signaling cascades following light irradiation

Low‐level light therapy (LLLT) using red to near‐infrared (NIR) (630–1000 nm) light has gained attention in recent years as a therapy in ophthalmology, neurology, dermatology, dentology, and regenerative medicine. Advancement in the basic science fields of photobiology has propelled LLLT into the therapeutic revolution. The potential mechanisms on LLLT‐induced biological effects have been investigated by numerous researchers throughout the world. This article reviews the current intracellular signaling cascades in photobiology and photomedicine under the influence of red to NIR light on mammalian cells. Specifically, mitochondrial retrograde signaling initiated by cytochrome c oxidase photomodulation is discussed in detail in the treatment of indications using LLLT, such as vitiligo management, retinal protection, and tumor therapy. The pathways through activating receptor tyrosine kinases are also highlighted in LLLT‐induced neuroprotection, wound healing, and skeletal muscle regeneration. The understanding of the LLLT‐induced biological reactions in cellular and subcellular levels is crucial for the advancement of LLLT in treatment of diseases.     

Fabrication of macroporous titanium dioxide film using PMMA microspheres as template

We determined the effects of emulsifier concentration and temperature on the distribution of gallic acid (GA) in a food-grade emulsion composed of 1:9 vol:vol stripped corn oil, acidic water and Tween 20. The distribution of GA can be defined by the partition constant between the aqueous and the interfacial regions, P(W)(I), which was determined by using a kinetic method and the pseudophase kinetic model. Once P(W)(I) is known, determining the distribution of GA is straightforward. Our results show that at least 40% of the total GA is located in the interfacial region of the emulsion at 0.005 volume fraction of Tween 20, and this percentage increases to ca. 85% of the total GA at 0.04 volume fraction of Tween 20. The variation of P(W)(I) with the temperature was used to estimate the thermodynamic parameters for the GA transfer from the aqueous to the interfacial region of the emulsion and the activation parameters for the reaction between 16-ArN(2)(+) and GA in the interfacial region. The free energy of transfer from the aqueous to the interfacial region, ΔG(T)(0,W→I), is negative, the enthalpy of transfer is small and negative, but the entropy of transfer is large and positive. Our results demonstrate that the partitioning of GA in acidic emulsions between aqueous and interfacial regions depends primarily on droplet concentration and is only slightly dependent on temperature.     

化学燃烧法制备Bi-2212前驱粉末

高质量的前驱粉是制备高性能Bi-2212线材的基础.本文采用化学燃烧法制备纳米级Bi-2212前驱粉末,分析了Bi-2212纳米粉末的成相过程以及微观形貌,结果表明可以成功制备尺寸小于100 nm的氧化粉末,经过热处理后得到纯的Bi-2212成相粉.与传统共沉淀方法的前驱粉末相比,纳米生粉反应活性更高,Bi-2212成相温度降低,转化效率更高.该方法有利于实现高质量的Bi-2212前驱粉末的批量制备.     

Dual pH-responsive and CD44 receptor targeted multifunctional nanoparticles for anticancer intracellular delivery

Journal of Nanoparticle Research - Photochemical synthesis of selected multicomponent compounds, namely cadmium or magnesium zinc oxides doped with Ga3+ ions—Zn1?x Cd x (Mg x...     

化肥成分分析系列标准物质研制

研制了尿素、磷酸氢二铵、氯化钾、高氮磷低氯复合肥、高氮低氯复合肥、高钾硫基复合肥、高钾中氯复合肥、高磷低氯复合肥和平衡型硫基复合肥系列化肥标准物质,样品严格按照相关标准要求进行采集、加工制备、均匀性检验、稳定性检验,由15家不同行业的权威实验室进行协作定值,并对不确定度进行评定。结果表明,样品粒度分布满足样品加工要求,具有良好的均匀性和稳定性。本系列化肥标准物质共定值45项元素(指标),包括N、P₂O₅、水溶性P₂O₅、有效性P₂O₅、K₂O、S、Cl、As、Hg、Cr、Cd、Cu、Pb、Zn、Ni、B、Se、Ge、Fe、Na、Ca、Mg、Al、Ti、V、Mn、Co、Sr、Mo、Ba、Y、La、Ce、Pr、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu,量值准确可靠、不确定度范围评估合理,符合国家一级标准物质的要求。研制的9个化肥化学成分标准物质定值的元素含量梯度范围合理,填补了国内复合肥料标准物质空白,可为化肥样品...     

Ultrasonic-Assisted Enzymolysis Extraction and Protective Effect on Injured Cardiomyocytes in Mice of Flavonoids from Prunus mume Blossom

Prunus mume blossom is an edible flower that has been used in traditional Chinese medicine for thousands of years. Flavonoids are one of the most active substances in Prunus mume blossoms. The optimal ultrasonic-assisted enzymatic extraction of flavonoids from Prunus mume blossom (FPMB), the components of FPMB, and its protective effect on injured cardiomyocytes were investigated in this study. According to our results, the optimal extraction process for FPMB is as follows: cellulase at 2.0%, ultrasonic power at 300 W, ultrasonic enzymolysis for 30 min, and an enzymolysis temperature of 40 °C. FPMB significantly promoted the survival rate of cardiomyocytes and reduced the concentration of reactive oxygen species (ROS). FPMB also improved the activities of proteases caspase-3, caspase-8, and caspase-9 in cardiomyocytes. The cardiomyocyte apoptosis rate in mice was significantly reduced by exposure to FPMB. These results suggest that the extraction rate of FPMB may be improved by an ultrasonic-assisted enzymatic method. FPMB has a protective effect on the injured cardiomyocytes.