Gasification of silicone fluids under external thermal radiation. Part I. Gasification rate and global heat of gasification

Transient gasification rates and fluid temperatures were measured for polydimethylsiloxane fluids ranging in viscosity from 0.65 cS to 60 000 cS in a nitrogen atmosphere at external radiant fluxes from 20 kW/m² to 70 kW/m². A detailed energy balance for each fluid sample was conducted to determine its global heat of vaporization. Two major energy loss corrections were identified and quantified. The absorption of incident radiation by the volatile products from short chain oligomers was measured and found to substantially reduce the incident flux to the sample surface; the energy loss due to re-radiation was determined to be a substantial factor in reducing the net heat flux to the sample for long chain length fluids. Other energy losses, e.g. heat loss to the substrate, were observed but were less significant. The average gasification rate for each fluid increased linearly with increasing external radiant flux. The global heat of gasification increases with an increase in the chain length (molecular weight) for the siloxane oligomers. These agreed well with calculated values. The global heat of gasification for 50 cS fluid is about 1200 kJ/kg and its value remains nearly constant for all higher molecular weight dimethylsiloxanes. Pyrolysis rates for siloxane fluids are very sensitive to trace catalysts. Measurements of the global heat of gasification for ultra-clean polymers resulted in significantly higher values (3000 kJ/kg). The gasification of siloxanes occurs via two modes or combinations thereof: (1) volatilization of molecular species native to the polymer, and (2) volatilization of thermal degradation products. The former process dominates for low molecular weight siloxanes (η<10 cS) and the latter process dominates for high molecular weight siloxanes (η>1000 cS). For the intermediate molecular weight siloxanes, both volatilization and degradation processes occur. © 1998 John Wiley & Sons, Ltd.     

Endocytosis and vacuolar morphology in Saccharomyces cerevisiae are altered in response to ethanol stress or heat shock

The vital lipophilic dye N‐(3‐triethylammoniumpropyl)‐4‐[6‐(4‐(diethylamino)phenyl]hexatrienyl) pyridinium dibromide (FM 4‐64) was used to study the effect of ethanol stress and heat shock on endocytosis in the yeast Saccharomyces cerevisiae. Yeast cells stained with FM 4‐64 were placed in a culture chamber and the internalization of the dye was monitored by fluorescence microscopy during perfusion of the cells with fresh growth medium. In the absence of ethanol in the perfusion medium, the internalization of FM 4‐64 from the plasma membrane to the vacuolar membrane by yeast cells harvested from the exponential phase of growth was completed in 30 min. The presence of 6% (v/v) ethanol in the perfusion medium had no obvious effect on the internalization of FM 4‐64 from the plasma membrane, but did lead to an accumulation of the dye in endocytic intermediates. Consequently, vacuolar membrane staining was delayed. Cells stained with FM 4‐64 and subjected to heat shock displayed a similar effect, with endocytic intermediates becoming more prominent with the severity of the heat shock. For both ethanol stress and heat shock, vacuolar morphology altered from segregated structures to a single, large organelle. The findings of this study reinforce previous observations that ethanol stress and heat shock induce similar responses in yeast. Copyright © 1999 John Wiley & Sons, Ltd.     

Fusion of Mitochondria to 3-D Networks,Autophagy and Increased Organelle Contacts are Important Subcellular Hallmarks during Cold Stress in Plants

Low temperature stress has a severe impact on the distribution, physiology, and survival of plants in their natural habitats. While numerous studies have focused on the physiological and molecular adjustments to low temperatures, this study provides evidence that cold induced physiological responses coincide with distinct ultrastructural alterations. Three plants from different evolutionary levels and habitats were investigated: The freshwater alga Micrasterias denticulata, the aquatic plant Lemna sp., and the nival plant Ranunculus glacialis. Ultrastructural alterations during low temperature stress were determined by the employment of 2-D transmission electron microscopy and 3-D reconstructions from focused ion beam–scanning electron microscopic series. With decreasing temperatures, increasing numbers of organelle contacts and particularly the fusion of mitochondria to 3-dimensional networks were observed. We assume that the increase or at least maintenance of respiration during low temperature stress is likely to be based on these mitochondrial interconnections. Moreover, it is shown that autophagy and degeneration processes accompany freezing stress in Lemna and R. glacialis. This might be an essential mechanism to recycle damaged cytoplasmic constituents to maintain the cellular metabolism during freezing stress.     

The effects of highways on school segregation

The purpose of this paper is to investigate the effects of interstate highway building on school segregation in US cities. The simple ordinary least squares (OLS) model might suffer from endogeneity bias and therefore an instrumental variables (IV) model is employed to account for endogeneity of highway routes. Dissimilarity and interaction indices are used to measure segregation and the results of the OLS and IV models indicate that school segregation increased due to the additions to the highway system. The estimates suggest that highways can explain 7–10% of the variation in school segregation.     

Optimization of Drug Candidates That Inhibit the D-Loop Activity of RAD51

RAD51 is the central protein in homologous recombination (HR) repair, where it first binds ssDNA and then catalyzes strand invasion via a D-loop intermediate. Additionally, RAD51 plays a role in faithful DNA replication by protecting stalled replication forks; this requires RAD51 to bind DNA but may not require the strand invasion activity of RAD51. We previously described a small-molecule inhibitor of RAD51 named RI(dl)-2 (RAD51 inhibitor of D-loop formation #2, hereafter called 2 h ), which inhibits D-loop activity while sparing ssDNA binding. However, 2 h is limited in its ability to inhibit HR in vivo, preventing only about 50 % of total HR events in cells. We sought to improve upon this by performing a structure–activity relationship (SAR) campaign for more potent analogues of 2 h . Most compounds were prepared from 1-(2-aminophenyl)pyrroles by forming the quinoxaline moiety either by condensation with aldehydes, then dehydrogenation of the resulting 4,5-dihydro intermediates, or by condensation with N,N′-carbonyldiimidazole, chlorination, and installation of the 4-substituent through Suzuki–Miyaura coupling. Many analogues exhibited enhanced activity against human RAD51, but in several of these compounds the increased inhibition was due to the introduction of dsDNA intercalation activity. We developed a sensitive assay to measure dsDNA intercalation, and identified two analogues of 2 h that promote complete HR inhibition in cells while exerting minimal intercalation activity.     

Stability to thermal treatment of dipeptidyl peptidase-IV inhibitory activity of a boarfish (Capros aper) protein hydrolysate when incorporated into tomato-based products

Biofunctional peptide ingredients should retain their stability following standard processing operations in food-based delivery vehicles. A boarfish protein hydrolysate, exhibiting anti-diabetic activity, was subjected to a range of thermal treatments following incorporation into tomato-based soup and juice products. The dipeptidyl peptidase-IV (DPP-IV) inhibitory activity and peptide profile of the hydrolysate within the products were assessed before and after thermal treatment. The treatments applied had no effect on the DPP-IV inhibitory activity or peptide profile of the protein hydrolysate. The heat-treated (90 °C × 1 min and 121 °C × 42 s) juice-fortified beverage had microbial counts within the acceptable limits for consumption when stored at 4 °C for 30 days. Furthermore, the hydrolysate within the beverage products was resistant to simulated gastrointestinal digestion (SGID) regardless of whether it was heat- or non-heat-treated, or stored for 30 days at 4 °C. Therefore, tomato-based beverages are suitable delivery vehicles for biofunctional peptide ingredients.     

Making Room for the River

Abstract

Problem, research strategy, and findings: In this study we analyze plan integration for flood resilience in the city of Nijmegen, the site of the largest Room for the River project in The Netherlands. Little is known about the degree to which local and regional plans are coordinated with the national Room for the River program or about the cumulative influence of plans on flood vulnerability. To effectively investigate these issues, we use and build upon the Plan Integration for Resilience Scorecard (PIRS) concept and method, which analyzes the consistency and effects of networks of plans on community vulnerability. We expand the scope to include plans from multiple administrative scales and the focus to include environmental vulnerability. Using a three-phase evaluation process, we demonstrate that Room for the River policies are well integrated in Nijmegen’s network of plans, particularly with respect to flood safety and natural protection. However, we also find that policies at different administrative scales lack consistency in some places, some socially vulnerable neighborhoods receive comparatively little policy attention, and local plans often prioritize development over flood resilience, though higher tier plans sometimes make up for these policy gaps. Flood resilience is still finding its way in the Dutch planning system.

Takeaway for practice: The PIRS offers planning practitioners a method to assess how networks of plans influence community vulnerability and, as demonstrated in this analysis, to determine the degree to which plans at multiple administrative scales target the most physically, socially, and environmentally vulnerable geographic areas. It can be used to support the ambitious goals of a program like Room for the River and align them with local development priorities.