Surfactant assisted processing of carbon nanotube/polypropylene composites: Impact of surfactants on the matrix polymer

Multiwalled carbon nanotubes (MWCNT) were dispersed in presence of various surfactants and introduced into isotactic polypropylene (PP) via melt blending. The effect of the surfactants on the crystallization and mechanical properties was studied on the injection molded specimens by isothermal differential scanning calorimetry and tensile tests, respectively. The results reveal that the presence of surfactants affects the mechanical and thermal properties of the nanocomposite. This information is supported by thermogravimetric analysis of the surfactants to examine their behavior at temperatures relevant for the processing of PP. In addition, they have to be taken into account as a third phase between the MWCNT and polymeric matrix, affecting the crystallization and failure behavior of PP or causing the formation of pores at elevated temperatures. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

设计师的地球工程“工具箱”：危机给予风景园林师扭转、修复和再生地球气候的机会

当前,风景园林师的气候危机（CC）教育强调“弹性”（快速恢复能力）和适应力（应对CC影响的能力）。探索并倡导缓解方案,以期从根源上解决CC问题。该实践表明,风景园林专业地位独特,在缓解及修复气候变化方面发挥着重要作用。专家一致认为,应对气候变化不能仅依靠减排或减少化石燃料消耗量。联合国政府间气候变化专门委员会（IPCC）2019年发布的《全球增暖1.5 ℃特别报告》指出,过量二氧化碳已带来诸多全球变暖的后果,必须采取其他行动减少碳排量。大气脱碳的应对方案与风景园林专业直接相关,其中陆上气候应对方案是公认途径,可减少人为诱发的二氧化碳排放量。基于地球工程学（GE）探讨了一系列方法,总结可纳入风景园林师工具箱的诸多补救措施,并通过代表案例分析各种措施的实际应用。这些工具中有许多涉及设置不同规模的自然和生物系统,且需要相对较长的时间才能发挥生态效用。因此,除了短期策略,本研究也将讨论基于前沿技术的GE工具以避免灾难性影响,并提出在必要情况下,可以采用减缓与减排相结合的方式。     

Particle concentrations and effectiveness of free-standing air filters in bedrooms of children with asthma in Detroit,Michigan

Asthma can be exacerbated by environmental factors including airborne particulate matter (PM) and environmental tobacco smoke (ETS). We report on a study designed to characterize PM levels and the effectiveness of filters on pollutant exposures of children with asthma. 126 households with an asthmatic child in Detroit, Michigan, were recruited and randomized into control or treatment groups. Both groups received asthma education; the latter also received a free-standing high efficiency air filter placed in the child’s bedroom. Information regarding the home, emission sources, and occupant activities was obtained using surveys administered to the child’s caregiver and a household inspection. Over a one week period, we measured PM, carbon dioxide (CO₂), environmental tobacco smoke (ETS) tracers, and air exchange rates (AERs). Filters were installed at midweek. Before filter installation, PM concentrations averaged 28 μg m⁻³, number concentrations averaged 70,777 and 1471 L⁻¹ in 0.3–1.0 and 1–5 μm size ranges, respectively, and the median CO₂ concentration was 1018 ppm. ETS tracers were detected in 23 of 38 homes where smoking was unrestricted and occupants included smokers and, when detected, PM concentrations were elevated by an average of 15 μg m⁻³. Filter use reduced PM concentrations by an average of 69–80%. Simulation models representing location conditions show that filter air flow, room volume and AERs are the key parameters affecting PM removal, however, filters can achieve substantial removal in even "worst" case applications. While PM levels in homes with asthmatic children can be high, levels can be dramatically reduced using filters.     

Peptides Derived from Vascular Endothelial Growth Factor B Show Potent Binding to Neuropilin-1

Vascular endothelial growth factors (VEGFs) regulate significant pathways in angiogenesis, myocardial and neuronal protection, metabolism, and cancer progression. The VEGF-B growth factor is involved in cell survival, anti-apoptotic and antioxidant mechanisms, through binding to VEGF receptor 1 and neuropilin-1 (NRP1). We employed surface plasmon resonance technology and X-ray crystallography to analyse the molecular basis of the interaction between VEGF-B and the b1 domain of NRP1, and developed VEGF-B C-terminus derived peptides to be used as chemical tools for studying VEGF-B - NRP1 related pathways. Peptide lipidation was used as a means to stabilise the peptides. VEGF-B-derived peptides containing a C-terminal arginine show potent binding to NRP1-b1. Peptide lipidation increased binding residence time and improved plasma stability. A crystal structure of a peptide with NRP1 demonstrated that VEGF-B peptides bind at the canonical C-terminal arginine binding site. VEGF-B C-terminus imparts higher affinity for NRP1 than the corresponding VEGF-A₁₆₅ region. This tight binding may impact on the activity and selectivity of the full-length protein. The VEGF-B₁₆₇ derived peptides were more effective than VEGF-A₁₆₅ peptides in blocking functional phosphorylation events. Blockers of VEGF-B function have potential applications in diabetes and non-alcoholic fatty liver disease.     

Stability of diphenylalanine peptide nanotubes in solution

Over the last couple of years, self-organizing nanotubes based on the dipeptide diphenylalanine have received much attention, mainly as possible building blocks for the next generation of biosensors and as drug delivery systems. One of the main reasons for this large interest is that these peptide nanotubes are believed to be very stable both thermally and chemically. Previously, the chemical and thermal stability of self-organizing structures has been investigated after the evaporation of the solvent. However, it was recently discovered that the stability of the structures differed significantly when the tubes were in solution. It has been shown that, in solution, the peptide nanotubes can easily be dissolved in several solvents including water. It is therefore of critical importance that the stability of the nanotubes in solution and not after solvent evaporation be investigated prior to applications in which the nanotube will be submerged in liquid. The present article reports results demonstrating the instability and suggests a possible approach to a stabilization procedure, which drastically improves the stability of the formed structures. The results presented herein provide new information regarding the stability of self-organizing diphenylalanine nanotubes in solution.