Boussinesq方程行波解的存在性

利用平面动力系统方法的分支理论,研究了Boussinesq方程,通过对Boussinesq方程进行行波变换,得到了相应行波系统的首次积分和平衡点,给出了不同参数条件下的相图,证实了Boussinesq方程存在孤立波解和周期波解。     

Synthetic Diphenylacetylene-Based Retinoids Induce DNA Damage in Chinese Hamster Ovary Cells without Altering Viability

All-trans-retinoic acid (ATRA), the active metabolite of vitamin A, plays a pivotal role in cell differentiation, proliferation and embryonic development. It is an effective therapy for dermatological disorders and malignancies. ATRA is prone to isomerization and oxidation, which can affect its activity and selectivity. Novel diphenylacetylene-based ATRA analogues with increased stability can help to overcome these problems and may offer significant potential as therapeutics for a variety of cancers and neurodegenerative diseases, including amyotrophic lateral sclerosis. Here, we investigated the effects of these retinoids on cell viability and genotoxicity in the widely used model system of the rapidly proliferating Chinese hamster ovary cell line. DC360 is a fluorescent ATRA analogue and DC324 is a non-active derivative of DC360. EC23, DC525, DC540, DC645, and DC712 are promising analogues with increased bioactivity. The cytotoxic activity of the compounds was evaluated by ATP assay and DNA damage was tested by comet assay. No cytotoxicity was observed in the 10⁻⁶–10⁻⁵ M concentration range. All compounds induced DNA migration similar to ATRA, but DC324, DC360 and EC23 did so to a greater extent, particularly at higher concentrations. We believe that retinoid receptor-independent genotoxicity is a general characteristic of these compounds; however, further studies are needed to identify the molecular mechanisms and understand their complex biological functions.     

Development,Validation, and Application of the UPLC-DAD Methodology for the Evaluation of the Qualitative and Quantitative Composition of Phenolic Compounds in the Fruit of American Cranberry (Vaccinium macrocarpon Aiton)

Phenolic compounds in the fruit of American cranberry (Vaccinium macrocarpon Aiton) determine the antioxidant, anti-inflammatory, anticancer, and other biological effects. The berries are used in the production of medicinal preparations and food supplements, which highlights the importance of qualitative and quantitative analysis of phenolic compounds in cranberry fruit raw material. The aim of our study was to develop and validate an efficient, cost-effective, reproducible, and fast UPLC-DAD methodology for the evaluation of the qualitative and quantitative composition of phenolic compounds in raw material and preparations of American cranberry fruit. During the development of the methodology, chlorogenic acid and the following flavonols were identified in cranberry fruit samples: myricetin-3-galactoside, quercetin-3-galactoside, quercetin-3-glucoside, quercetin-3-α-L-arabinopyranoside, quercetin-3-α-L-arabinofuranoside, quercetin-3-rhamnoside, myricetin, and quercetin. The developed and optimized UPLC-DAD methodology was validated according to the guidelines of the International Council for Harmonization (ICH), evaluating the following parameters: range, specificity, linearity (R² > 0.999), precision (%RSD < 2%), LOD (0.38–1.01 µg/mL), LOQ (0.54–3.06 µg/mL), and recovery (80–110%). The developed methodology was applied to evaluate the qualitative and quantitative composition of phenolic compounds in fruit samples of cranberry cultivars ‘Baifay’, ‘Bergman’, ‘Prolific’, and ‘Searles’, as well as ‘Bain-MC’ and ‘BL-12′ clones. In the tested samples, the majority (about 70%) of the identified flavonols were quercetin derivatives. The greatest amount of quercetin-3-galactoside (1035.35 ± 4.26 µg/g DW) was found in fruit samples of the ‘Searles’ cultivar, and the greatest amount of myricetin-3-galactoside (940.06 ± 24.91 µg/g DW) was detected in fruit samples of the ‘Woolman’ cultivar.     

INFLUENCE OF MOLECULAR WEIGHT AND PERIODATE-MODIFICATION OF β-D-GLUCANS FROM PORIA COCOS SCLEROTIUM ON ANTITUMOR ACTIVITIES*

In this work, influence of molecular weight and periodate modification ofβ-D-glucans isolated from Poria cocos sclerotium on the antitumor activities against Sar-coma 180 and Ehrlich ascites carcinoma (EAC) tumor was studied. The results show thattwo glucans PC3 (linear β-(1→3)-D-glucan) and PC4 [β-(1→3)-D-glucan with a fewof branches and glucuronic acid] are devoid of antitumor activity. However, when theglucans were modified by periodate oxidation, borohydride reduction and mild hydrolysisor partially hydrolysis, the derivatives have obvious antitumor activities. The decreasein molecular weight of glucans after periodate modification hardly affects their antitumoractions, but on the other hand, the decrease of molecular weight without periodate modi-fication could lead to an enhancement of the antitumor activities. Moreover, the glucansand these derivatives have much higher enhancement ratios of body weight of mice thanthat of 5-Fluorouracil (5-Fu), suggesting that they are less toxic than 5-Fu.     

Partial Oxidation of Methane to Synthesis Gas over Hexaaluminates LaMAl11O19-δ catalysts

A series of M-substituted hexaaluminates LaMAl11O19-δ (M=Fe, Co, Ni, Mn, and Cu)were prepared and characterized by XRD, XPS, TPR and TGA techniques, respectively. They exhibited different reducibility and catalytic activity for partial oxidation of methane (POM) to synthesis gas. Among the LaMAl11O19-δ samples, LaNiAl11O19-δ showed the best catalytic activity for the topic reaction and selectivity for synthesis gas at 780 ℃ for 2 h. The conversion of CH4 was over 99.2%, and the product selectivity for both CO and H2 was above 90.3%.     

纤维素溶剂研究进展

概述了纤维素溶剂的重要研究进展,主要包括N-甲基吗啉-N-氧化物(NMMO)在85℃以上高温可破坏纤维素分子间氢键,导致溶解;氯化锂/二甲基乙酰胺(LiCl/DMAc)在100℃以上可溶解纤维素;1-丁基-3-甲基咪唑盐酸盐([BMIM]Cl)和1-烯丙基-3-甲基咪唑盐酸盐([AMIM]Cl)离子液体,含强氢键受体Cl-离子,通过它们与纤维素羟基作用而引起溶解.氨基甲酸酯体系则是通过尿素与纤维素在100℃以上反应转变为纤维素氨基甲酸酯,然后再溶解于NaOH水溶液中;氢氧化钠/水体系,只能溶解结晶度和聚合度较低的纤维素;NaOH/尿素、NaOH/硫脲和LiOH/尿素水溶液体系,它们预冷至-5~-12℃后可迅速溶解纤维素.主要是通过低温产生小分子和大分子间新的氢键网络结构,导致纤维素分子内和分子间氢键的破坏而溶解,同时尿素或者硫脲作为包合物客体阻止纤维素分子自聚集使纤维素溶液较稳定.低温溶解技术不仅突破了加热溶解的传统方法,而且可推进化学"绿色化"进程.共引用参考文献50篇.     

电泳法制备的致密氧化锡薄膜及其在高稳定性钙钛矿太阳能电池中的应用

在平面型钙钛矿太阳能电池中常采用SnO₂作为电子传输层材料,相应的SnO₂薄膜常采用溶液旋涂法制备。但是由于前驱液中的纳米颗粒可能会发生部分团聚、基底和溶液难以完全避免灰尘等杂质颗粒混入,且最佳的SnO₂电子传输层的厚度通常仅有约20 nm,所以这种方法制备的电子传输层难以保证严格致密和无纳米针孔。在本工作中,我们报道了一种电泳沉积制备致密SnO₂薄膜的方法,并用其有效地提高了钙钛矿太阳能电池的光电转换效率和工况稳定性。通过电泳法,表面带负电荷的SnO₂纳米颗粒在电场的作用下沉积到氧化铟锡(ITO)阳极表面,这种方法得到的薄膜比旋涂法制备的更为致密。将其应用于n-i-p结构的钙钛矿太阳能电池中,能够使得暗电流降低并抑制载流子的非辐射复合,从而提高电池的短路电流和开路电压,进而实现更高的光电转换效率(从18.17%提高到19.52%),且能消除迟滞效应。更重要的是,长期工况稳定性测试表明基于电泳-旋涂法制备的器件在1个太阳的光照下、最大功率点处连续工作960 h后,仍然能够保持71%的初始效率;然而基于旋涂法制备的器件在工作100 h后即降低到初始效率的70%。本工作提供了一种全新的SnO₂电子传输层的制备方法,显著地提高了器件性能和工况稳定性,后续有望应用于制备大面积器件和电池模组。     

花椰菜状碳酸钙的"一步法"制备及表征

以碱土金属锶的硝酸盐为添加剂, 采用“一步法”制备了大小均一、 分散性良好的花椰菜状碳酸钙粒子. 考察了反应温度、 反应时间等因素对碳酸钙结晶行为的影响, 确定了最佳反应条件. 利用扫描电子显微镜(SEM)、 X射线衍射仪(XRD)、 X射线能谱仪(EDAX)等对所得产物的结构和性能进行了表征, 并探讨了其反应原理.     

Overview of the Biological Activity of Anthraquinons and Flavanoids of the Plant Rumex Species

Rumex confertus belongs to the genus Rumex and is classified as an invasive parasitic plant in agriculture. Despite other Rumex species being widely used in herbal medicine due to their antimicrobial, antioxidant, antitumor, and anti-inflammatory effects, there are almost no information about the potential of Rumex confertus for the treatment of various diseases. In this review we analyzed scientific articles revealing properties of Rumex plant’s substances against cancer, diabetes, pathogenic bacterial invasions, viruses, inflammation, and oxidative stress for the past 20 years. Compounds dominating in each composition of solvents for extraction were discussed, and common thin layer chromatography(TLC) and high performance liquid chromatography(HPLC) methods for efficient separation of the plant’s extract are included. Physico-chemical properties such as solubility, hydrophobicity (Log P), pKa of flavonoids, anthraquinones, and other derivatives are very important for modeling of pharmacokinetic and pharmacodynamics. An overview of clinical studies for abounded selected substances of Rumex species is presented.     

Photocatalytic Carboxylation of Phenyl Halides with CO2 by Metal-Organic Frameworks Materials

In this work,important commercial pharmaceutical intermediates,phenylpropionic acid compounds,are successfully obtained by catalyzing the reaction of carbon dioxide with phenyl halides using MOF-5,a typical metal-organic framework(MOF)material.The influence of temperature,pressure,catalyst type and light on the reaction is investigated,and a 90.3%selectivity towards fluorophenylpropionic acid is reached.Significantly,the catalysts are effective for varied benzyl compounds containing different substituent groups.The catalysts are stable and remain active after three cycles.