Promises of Main Group Metal–Based Nanostructured Materials for Electrochemical CO2 Reduction to Formate

Selective CO₂ reduction to formic acid or formate is the most technologically and economically viable approach to realize electrochemical CO₂ valorization. Main group metal–based (Sn, Bi, In, Pb, and Sb) nanostructured materials hold great promise, but are still confronted with several challenges. Here, the current status, challenges, and future opportunities of main group metal–based nanostructured materials for electrochemical CO₂ reduction to formate are reviewed. Firstly, the fundamentals of electrochemical CO₂ reduction are presented, including the technoeconomic viability of different products, possible reaction pathways, standard experimental procedure, and performance figures of merit. This is then followed by detailed discussions about different types of main group metal–based electrocatalyst materials, with an emphasis on underlying material design principles for promoting the reaction activity, selectivity, and stability. Subsequently, recent efforts on flow cells and membrane electrode assembly cells are reviewed so as to promote the current density as well as mechanistic studies using in situ characterization techniques. To conclude a short perspective is offered about the future opportunities and directions of this exciting field.     

森林景观变化的地理环境因素整合分析——以伊洛河流域洛宁县为例

运用景观生态学的基本原理,借助于地理信息系统技术,整合分析了地理环境因素对伊洛河流域洛宁县森林景观动态变化的影响。结果显示,应用地理环境因素影响指数可以很好地从整体上分析地理环境因素,如高程、坡度、距离居民点中心的距离、与森林边缘距离等地理环境因子对区域森林景观动态变化的影响。1983和1999年,伊洛河流域洛宁县森林景观在地理环境因素影响指数上的优势分布区间(Pie1)分别为1230和1030,即在中高地理环境因素影响指数分布区间内,且有向低地理环境因素影响指数分布区间略为移动的趋势。森林景观类型保持不变部分、森林景观转化为非森林景观类型部分和非森林景观转化为森林景观类型部分所对应的在地理环境因素影响指数上的优势分布区间(Pie1)分别为1130、18和613。通过建立森林景观动态变化与地理环境因素影响指数的相互关系,表明森林景观动态变化与地理环境因素影响指数(特别是在地理环境因素影响指数的优势分布区间内)有显著相关关系。     

FTY720-enhanced T cell homing is dependent on CCR2, CCR5, CCR7, and CXCR4: evidence for distinct chemokine compartments

FTY720 stimulates CCR7-driven T cell homing to peripheral lymph nodes (LN) by direct activation of sphingosine 1-phosphate receptors, along with the participation of multidrug transporters, 5-lipoxygenase, and G protein-coupled receptors for chemokines. In this study, we demonstrate that FTY720 also directly stimulates in vitro T cell chemotaxis to CCR2-CCL2, but not to a variety of other chemokines, including CCR5-CCL3/4/5 and CXCR4-CXCL12. FTY720 influences CCR2-CCL2-driven migration through activation of the multidrug transporters, Abcb1 and Abcc1, and through 5-lipoxygenase activity. In vivo administration of FTY720 induces chemokine-dependent migration of T cells in the thymus, peripheral blood, LN, and spleen. The CCR7 and CCR2 chemokine ligands are required for both T cell sequestration in LN and thymic T cell egress following FTY720 administration. Furthermore, FTY720 administration uncovers a requirement for CXCR4 ligands for LN homing, but not for thymic egress, and CCR5 for thymic egress, but not LN homing. FTY720-driven splenic and peripheral blood T cell egress are both independent of CCR2, CCR5, CCR7, or CXCR4. These results indicate that FTY720- and sphingosine 1-phosphate receptor-stimulated T cell migration are dependent on the restricted usage of chemokine receptor-ligand pairs within discrete anatomic compartments.     

New 2(3-->20)abeotaxane and 3,11-cyclotaxane from needles of Taxus cuspidata

Two new taxoid metabolites, 2alpha,7beta,10beta-triacetoxy-5alpha,13alpha-dihydroxy-2(3-->20)abeotaxa-4(20),11-dien-9-one (1) and 2alpha-acetoxy-5alpha-cinnamoyloxy-9alpha,10beta-dihydroxy-3,11-cyclotax-4(20)-en-13-one (2), were isolated from the methanol extract of needles of the Japanese yew, Taxus cuspidata.     

金露梅与格桑花

青藏高原的格桑花是什么植物或者说是什么植物的花,存在广泛争议,困扰着想一探究竟的人们。格桑花作为一种精神存在于藏族百姓心中,是他们追求幸福吉祥和美好生活的情感象征,是重要的雪域文化标识,认识熟知并开发利用好它,将有助于推动藏区生态、文化和产业振兴。金露梅是青藏高原分布最广的树木,按集生羽状复叶小叶数可分为5叶金露梅和7叶金露梅,《中国植物志》对它们的记载分别是金露梅（Potentilla fruticosa L.）和小叶金露梅（P.parvifolia Fisch.）。通过对青藏高原植被和历史文化景观考察,结合当地藏民描述及地方传说,本研究认为格桑花就是金露梅,其分布海拔可以拓展到5200 m的高寒恶劣环境。金露梅生性强健,耐寒、耐旱、耐瘠薄、耐强光,象征着藏族同胞刚毅、坚强、勤劳质朴、不畏严寒、生命力顽强的品格。     

Activation of antifreeze proteins from larvae of the beetle Dendroides canadensis

Summary Purified antifreeze proteins (AFPs) from the larvae of the beetle Dendroides canadensis do not produce the high levels of antifreeze activity seen in the hemolymph of overwintering larvae, even when the purified AFPs are assayed at very high concentrations. However, addition of certain proteins or agar (at concentrations sufficiently low that the gel state does not result) to the Dendroides AFP resulted in a 2–3-fold increase in activity. A 70-kDa protein with AFP-activating capabilities was purified from Dendroides larvae. Addition of this endogenous activator protein to a 4 mg·ml^-1 solution of AFP increased the activity of the AFPs to values comparable to those of the hemolymph of overwintering larvae. Data derived from a modified immunoblot technique demonstrate that the activators bind to the AFP, or vice versa. Formation of this association must allow the AFP to block ice crystal growth by binding to the surface of potential seed crystals in the normal fashion. However, because the AFP-activator complex is much larger than the AFP alone, the complex probably blocks a greater surface area of the crystal and is thus a more efficient antifreeze.Abbreviations AFP antifreeze protein - BSA bovine serum albumine - DEAE diethylaminoethyl - Ig immunoglubolin - LPIN lipoprotein ice nucleator - PIN protein ice nucleator - SDS sodium dodecyl sulfate - PAGE polyacrylamide gel electrophoresis - TH thermal hysteresis     

Carriers of Loss-of-Function Mutations in EXT Display Impaired Pancreatic Beta-Cell Reserve Due to Smaller Pancreas Volume

Exotosin (EXT) proteins are involved in the chain elongation step of heparan sulfate (HS) biosynthesis, which is intricately involved in organ development. Loss of function mutations (LOF) in EXT1 and EXT2 result in hereditary exostoses (HME). Interestingly, HS plays a role in pancreas development and beta-cell function, and genetic variations in EXT2 are associated with an increased risk for type 2 diabetes mellitus. We hypothesized that loss of function of EXT1 or EXT2 in subjects with hereditary multiple exostoses (HME) affects pancreatic insulin secretion capacity and development. We performed an oral glucose tolerance test (OGTT) followed by hyperglycemic clamps to investigate first-phase glucose-stimulated insulin secretion (GSIS) in HME patients and age and gender matched non-affected relatives. Pancreas volume was assessed with magnetic resonance imaging (MRI). OGTT did not reveal significant differences in glucose disposal, but there was a markedly lower GSIS in HME subjects during hyperglycemic clamp (iAUC HME: 0.72 [0.46–1.16] vs. controls 1.53 [0.69–3.36] nmol·l⁻¹·min⁻¹, p<0.05). Maximal insulin response following arginine challenge was also significantly attenuated (iAUC HME: 7.14 [4.22–10.5] vs. controls 10.2 [7.91–12.70] nmol·l⁻¹·min⁻¹ p<0.05), indicative of an impaired beta-cell reserve. MRI revealed a significantly smaller pancreatic volume in HME subjects (HME: 72.0±15.8 vs. controls 96.5±26.0 cm³ p = 0.04). In conclusion, loss of function of EXT proteins may affect beta-cell mass and insulin secretion capacity in humans, and render subjects at a higher risk of developing type 2 diabetes when exposed to environmental risk factors.     

Antidepressant treatment normalizes white matter volume in patients with major depression

Objective

To investigate white matter volume abnormalities in patients with major depression and the effects of antidepressant treatment on white matter volume.

Method

Magnetic resonance imaging (MRI) was performed on 32 treatment-naïve depressed patients, 17 recovered patients who had received antidepressant treatment and subsequently achieved clinical recovery and 34 matched controls.

Results

Relative to the healthy controls, the treatment-naïve depressed patients showed increased white matter volumes in the left dorsolateral prefrontal cortex (DLPFC) and left putamen and reduced white matter volumes in the left cerebellum posterior lobe and left inferior parietal lobule. For the treatment-naïve patients, the length in months of the current depressive episode was positively correlated with the white matter volumes in both the left DLPFC and left putamen. In the recovered patients, the differences in white matter volume were no longer statistically significant relative to healthy controls. No significant difference was found in the total white matter volume among the three groups.

Conclusions

This study demonstrates that there were alterations in the white matter volumes of depressed patients, which might disrupt the neural circuits that are involved in emotional and cognitive function and thus contribute to the pathophysiology of depression. The finding of the significant correlations between refractoriness and the white matter volumes in the left DLPFC and left putamen combined with the finding that antidepressant treatment normalized the white matter volume of recovered patients, suggests that a quantitative, structural MRI measurement could act as a potential biomarker in depression therapy for individual subjects.     

A New Functional Site W115 in CdtA Is Critical for Aggregatibacter actinomycetemcomitans Cytolethal Distending Toxin

Aggregatibacter actinomycetemcomitans, a specific pathogen of localized aggressive periodontitis, produces a cytolethal distending toxin (CDT) that arrests eukaryotic cells irreversibly in G0/G1 or G2/M phase of the cell cycle. Although structural studies show that the aromatic patch region of CdtA plays an important role in its biological activity, the functional sites of CdtA have not been firmly established. In this study, site-specific mutagenesis strategy was employed for cdtA point mutations construction so as to examine the contributions of individual amino acids to receptor binding and the biological activity of holotoxin. The binding ability was reduced in CdtA^Y181ABC holotoxin and the biological function of CDT was not weaken in CdtA^Y105ABC, CdtA^Y125ABC, CdtA^F109ABC and CdtA^S106NBC holotoxin suggesting that these sites were not critical to CDT. But the binding activity and cell cycle arrest ability of holotoxin complexes were inhibited in CdtA^W115GBC. And this site did not affect the holotoxin assembly by size exclusion chromatography. Therefore, W115 might be a critical site of CdtA binding ability. These findings suggest that the functional sites of CdtA are not only in the aromatic patch region. W115, the new functional site is critical for receptor binding and cell cycle arrest, which provides potential targets for pharmacological disruption of CDT activity.