Comparative emission analysis of low-energy and zero-emission buildings

Different designs and concepts of low-energy and zero-emission buildings (ZEBs) are being introduced into the Norwegian market. This study analyses and compares the life cycle emissions of CO₂ equivalents (CO₂e) from eight different single-family houses in the Oslo climate. Included are four ZEBs: one active house, two passive houses, and a reference house (Norwegian building code of 2010). Monthly differences in CO₂e emissions are calculated for the seasonally sensitive Norwegian context for electricity generation and consumption. This is used to supplant the previous applied symmetric weighting approach for CO₂e/kWh factors for import and export of electricity for the ZEB cases. All the ZEBs have lower use-stage emissions compared with the other buildings or the reference case. Embodied impacts are found to be 60–75% for the analysed ZEB cases, confirming the importance of embodied impacts in Norwegian ZEBs. The lowest total emissions were from the smallest ZEB, emphasizing area efficiency. The highest emissions were from the reference case. By abandoning the symmetric approach, a new perspective was developed for assessing the performance of ZEBs within the Norwegian context. One of four ZEB cases managed to balance out its annual energy-related emissions.     

Response of a proton exchange membrane fuel cell to a sinusoidal current load

The load-following capability of a proton exchange membrane fuel cell was studied by measuring the cell voltage response to a sinusoidal current load with large amplitude and varying frequency. A mathematical model was developed, incorporating mass transport and capacitive effects as well as the membrane resistance. The model was capable of separating the faradaic and capacitive currents and predicting the observed hysteresis. At frequencies of the sinusoidal current load below 1 Hz, no appreciable hysteresis in the polarisation curve was observed. When increasing the frequency above 1 Hz, a hysteresis appeared at current densities below 0.2 A cm^?2. The model related this hysteresis to capacitive effects. When using air as the cathode feed, hysteresis in the current density range 0.5 A cm^?2 and higher appeared above 1 Hz compared to 100 Hz for pure oxygen. The model revealed that hysteresis observed in this current density range was caused by oxygen transport limitations.     

GC–MS analysis of oxysterols and their formation in cultivated liver cells (HepG2)

Oxysterols play a key role in many (patho)physiological processes and they are potential biomarkers for oxidative stress in several diseases. Here we developed a rapid gas chromatographic-mass spectrometry-based method for the separation and quantification of 11 biologically relevant oxysterols bearing hydroxy, epoxy, and dihydroxy groups. Efficient chromatographic separation (resolution ≥ 1.9) was achieved using a medium polarity 35%-diphenyl/65%-dimethyl polysiloxane stationary phase material (30 m × 0.25 mm inner diameter and 0.25 μm film thickness). Based on thorough analysis of the fragmentation during electron ionization we developed a strategy to deduce structural information of the oxysterols. Optimized sample preparation includes (i) extraction with a mixture of n-hexane/iso-propanol, (ii) removal of cholesterol by solid phase extraction with unmodified silica, and (iii) trimethylsilylation. The method was successfully applied on the analysis of brain samples, showing consistent results with previous studies and a good intra- and interday precision of ≤20%. Finally, we used the method for the investigation of oxysterol formation during oxidative stress in HepG2 cells. Incubation with tert-butyl hydroperoxide led to a massive increase in free radical formed oxysterols (7-keto-chol > 7β-OH-chol >> 7α-OH-chol), while 24 h incubation with the glutathione peroxidase 4 inhibitor RSL3 showed no increase in oxidative stress based on the oxysterol pattern. Overall, the new method described here enables the robust analysis of a biologically meaningful pattern of oxysterols with high sensitivity and precision allowing us to gain new insights in the biological formation and role of oxysterols.     

Building in economic terms

The housing achievements of the Nordic countries in the past two decades are internationally recognised. Here, a distinguished Norwegian economist and former Minister argues that future policies must be based on the optimum use of resources, and one of the greatest real resources is the existing housing stock.     

Reviews

Mathew Chandrankunnel, Philosophy of Physics , reviewed by Helge Kragh
Danian Hu, China and Albert Einstein: The Reception of the Physicist and His Theory in China, 1917-1979 , reviewed by Helge Kragh     

Der Kommenter

Ohne Zusammenfassung     

Effects of visual alcohol cues on alcoholics' autonomic arousal.

Determined whether visual alcohol cues alone (slides showing drinking environments and alcohol beverage bottles) were sufficient to elicit autonomic arousal. 82 male alcoholics (aged 25–64 yrs) were shown alcohol-related or control slides while electrodermal responses were being recorded. Each slide was presented for 4 sec and interstimulus intervals varied between 20 and 30 sec. The frequency of skin conductance responses (SCRs) and the amplitude of the first SCR to each picture presentation were greater to alcohol slides than to control slides. The Ss showed slower habituation to alcohol-related slides as compared with control slides. Pictures of hard liquor yielded higher SCR amplitudes than did pictures of beer. (PsycINFO Database Record (c) 2010 APA, all rights reserved)