Three-dimensional supramolecular crystalline materials based on Keggin-based polyoxometalates and 1,2-Bis (4-pyridyl) ethylene for supercapacitor electrodes

Transition Metal Chemistry - To research the application of polyoxometalates (POMs)-based supramolecular crystalline materials in supercapacitors, two new compounds,...     

Changes in Phenols,Polysaccharides and Volatile Profiles of Noni (Morinda citrifolia L.) Juice during Fermentation

The change in phenols, polysaccharides and volatile profiles of noni juice from laboratory- and factory-scale fermentation was analyzed during a 63-day fermentation process. The phenol and polysaccharide contents and aroma characteristics clearly changed according to fermentation scale and time conditions. The flavonoid content in noni juice gradually increased with fermentation. Seventy-three volatile compounds were identified by solid-phase microextraction coupled with gas chromatography–mass spectrometry (SPME-GC-MS). Methyl hexanoate, 3-methyl-3-buten-1-ol, octanoic acid, hexanoic acid and 2-heptanone were found to be the main aroma components of fresh and fermented noni juice. A decrease in octanoic acid and hexanoic acid contents resulted in the less pungent aroma in noni juice from factory-scale fermentation. The results of principal component analysis of the electronic nose suggested that the difference in nitrogen oxide, alkanes, alcohols, and aromatic and sulfur compounds, contributed to the discrimination of noni juice from different fermentation times and scales.     

Potential Role of Melatonin as an Adjuvant for Atherosclerotic Carotid Arterial Stenosis

Carotid artery stenosis (CAS) is an atherosclerotic disease characterized by a narrowing of the artery lumen and a high risk of ischemic stroke. Risk factors of atherosclerosis, including smoking, hypertension, hyperglycemia, hyperlipidemia, aging, and disrupted circadian rhythm, may potentiate atherosclerosis in the carotid artery and further reduce the arterial lumen. Ischemic stroke due to severe CAS and cerebral ischemic/reperfusion (I/R) injury after the revascularization of CAS also adversely affect clinical outcomes. Melatonin is a pluripotent agent with potent anti-inflammatory, anti-oxidative, and neuroprotective properties. Although there is a shortage of direct clinical evidence demonstrating the benefits of melatonin in CAS patients, previous studies have shown that melatonin may be beneficial for patients with CAS in terms of reducing endothelial damage, stabilizing arterial plaque, mitigating the harm from CAS-related ischemic stroke and cerebral I/R injury, and alleviating the adverse effects of the related risk factors. Additional pre-clinical and clinical are required to confirm this speculation.     

Pseudo-mono-axial ligand fields that support high energy barriers in triangular dodecahedral Dy(iii) single-ion magnets

The synthesis of air-stable, high-performance single-molecule magnets (SMMs) is of great significance for their practical applications. Indeed, Ln complexes with high coordination numbers are satisfactorily air stable. However, such geometries easily produce spherical ligand fields that minimize magnetic anisotropy. Herein, we report the preparation of three air-stable eight-coordinate mononuclear Dy(iii) complexes with triangular dodecahedral geometries, namely, [Dy(BPA-TPA)Cl](BPh₄)₂ (1) and [Dy(BPA-TPA)(X)](BPh₄)₂·nCH₂Cl₂ (X = CH₃O⁻ and n = 1 for 2; L = PhO⁻ and n = 2 for 3), using a novel design concept in which the bulky heptadentate [2,6-bis[bis(2-pyridylmethyl)amino]methyl]-pyridine (BPA-TPA) ligand enwraps the Dy(iii) ion through weak coordinate bonds leaving only a small vacancy for a negatively charged (Cl⁻), methoxy (CH₃O⁻) or phenoxy (PhO⁻) moiety to occupy. Magnetic measurements reveal that the single-molecule magnet (SMM) property of complex 1 is actually poor, as there is almost no energy barrier. However, complexes 2 and 3 exhibit fascinating SMM behavior with high energy barriers (U_eff = 686 K for 2; 469 K for 3) and magnetic hysteresis temperatures up to 8 K, which is attributed to the pseudolinear ligand field generated by one strong, highly electrostatic Dy–O bond. Ab initio calculations were used to show the apparent difference in the magnetic dynamics of the three complexes, confirming that the pseudo-mono-axial ligand field has an important effect on high-performance SMMs compared with the local symmetry. This study not only presents the highest energy barrier for a triangular dodecahedral SMM but also highlights the enormous potential of the pseudolinear Dy–L ligand field for constructing promising SMMs.

Air-stable triangular dodecahedral Dy(iii) single-ion magnets with pseudo-mono-axial linear ligand fields exhibit high energy barrier exceeding 600 K, which represent the highest energy barrier for mononuclear SMMs with triangular dodecahedron.     

Dissipation and Residue of Metalaxyl-M and Azoxystrobin in Scallions and Cumulative Risk Assessment of Dietary Exposure to Hepatotoxicity

Metalaxyl-M and azoxystrobin have been used to control various fungal diseases on scallion and other crops. In view of the adverse toxic effects of both on the mammalian liver, it is necessary to conduct a cumulative risk assessment of their dietary exposure to consumers. The residues of metalaxyl-M and azoxystrobin on scallion were determined by a quick, easy, cheap, effective, rugged, and safe method (QuEChERS) combined with high-performance liquid chromatography tandem mass spectrometry (LC-MS/MS). The half-lives were about 1.15 and 3.89 days, respectively, and the final residues after a seven-day harvest interval were <0.001–0.088 mg/kg and 0.190–4.687 mg/kg, respectively. The cumulative dietary risk quotient of the two fungicides to Chinese consumers calculated by the probability model is 13.94%~41.25%. According to the results of the contribution analysis, the risk posed by azoxystrobin is much greater than that of metalaxyl-M. Although metalaxyl-M and azoxystrobin do not pose a cumulative risk to Chinese consumers, the risk to children and adolescents is significantly higher than that to adults. This suggests that in future research, more consideration should be given to the cumulative risk of compounds to vulnerable groups.     

ADS注入器Ⅰ高频四极场功率源系统研制

ADS注入器Ⅰ高频四极场(RFQ)功率源系统将为325 MHz RFQ提供连续波功率,使束流离开RFQ时,其能量达到几MeV。功率源系统除了补偿RFQ腔耗外,还必须提供足够的功率以保证RFQ中的加速电场。ADS注入器Ⅰ RFQ功率源系统主要包括600 kW连续波速调管、80 kV/18 A基于脉冲步进调制技术的PSM电源、环流器以及相应的波导传输系统等。根据ADS总体指标和RFQ的相关技术参数,提出了功率源的总体布局、技术指标以及设计要求等,在此基础上完成系统安装与调试,并通过专家组测试与验收。     

气体火花开关电极烧蚀研究

采用Mo,WCu和W分别作为三种气体火花开关的主电极材料,进行放电条件下电极烧蚀实验,研究开关电极烧蚀率和烧蚀形貌,分析电极烧蚀特征。结果表明,Mo,WCu和W开关的主电极烧蚀率分别为3.3210-2 C-1m-2, 2.6310-2 C-1m-2和1.710-2 C-1m-2,W开关主电极烧蚀率最小。实验后开关的主电极中心烧蚀严重,呈现明显裂纹和烧蚀坑。Mo主电极表面呈现明显熔融态,阴极表面形成大量裂纹（宽度达10 m）和孔隙（孔径达10 m）;WCu和W主电极表面形成少量圆球状W突起（粒径达20 m及以上）。开关外壳内壁沉积了喷溅颗粒。WCu开关外壳沉积颗粒较大（粒径达10 m）,Mo开关外壳沉积颗粒居中（粒径为2 m）,W开关外壳沉积颗粒最小（近1 m）。因此可优先选用具有优异抗烧蚀性能的W作为气体火花开关电极材料。     

含裂纹结构可靠度的多尺度求解

针对环境作用下金属结构从微观损伤到宏观失效的复杂过程,选用具有局部细化特征的CAS小波,先对疲劳裂纹扩展方程进行离散处理,将微分方程转化为代数方程组,然后用完全积分可靠性分析模型,对一般环境中和引入环境系数的含裂纹结构的可靠度进行求解.最后,验证了利用CAS小波多尺度方法求解复杂环境中结构疲劳破坏过程是可行的,并能很好地解决短裂纹与长裂纹扩展的光滑过渡.     

界面反射超声散斑一阶统计特性

对界面反射超声散斑场的一阶统计特性进行了理论和实验分析.在假设条件下,推导了超声散斑场的振幅分布和相位分布,实测数据显示理论与实验结果有很好的吻合,这表明理论假设是合理的并在实践中可行.这还表明,在B超影像分析中,超声扫描截面上散斑场统计特性的结果与该文的结果一致.