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Klaus D. Beccu wrote:
The major problem is LIFETIME
Certainly, there are ways of improving the performance of organic solar cells. But up to now the lifetime data are far from being acceptable. As well known, Mr. Graetzel at Lausanne university has worked over 20 years on this technology and "burned" millions of public money (Swiss Francs) by filing hundreds of patents and insisting that organic dyes have a bright future in the conversion of solar to electric energy, always reminding the natural mechanism of photosynthesis. But nature recreates every year the conversion system in new leafs and gets rid of the lifetime constraint. Also the expected lower cost of organic solar cells cannot compensate for the low lifetime.
Even for the more stable silicon PV cells - very expensive and therefore requiring amortisation over 10 to 15 years - lifetime considerations are becoming a serious issue after significant performance degradation was observed already after 18 months in rural areas due to the influence of methane from bovine emissions. The influence of chemicals in industrial atmospheres has never been investigated on a longterm basis. Therefore, lifetime expectancy is an important factor in obtaining acceptable return on investment. After 10 years the companies having sold and installed the panels are probably no longer there. Guarantees are void. There are unfortunate people who have installed PV panels and hope to have done an investment for 35 years - for the generation of their children. There will be a big disappointment on the energy supplied after such long time.
Battelle-Geneva. Energy R&D Center
Thu Nov 10 14:56:32 UTC 2011
BJS Administrator wrote:
Review: Gastric Band and Beyond: Maximise Your Weight Loss
This semi-autobiographical book describes the journey of a gastric band patient who also works as a specialist nurse in a bariatric clinic. Written in the style of a ‘self help’ book it is full of practical hints for those contemplating gastric band surgery. Heavily slanted towards banding, the personal preparation for surgery from the decision to have the operation to the challenges of coping with the necessary changes afterwards will resonate with those choosing any bariatric operation.
The sections describing band surgery could have more specific data on the known risks and outcomes - the phrase ‘complications are rare’ is stated or implied more than once. No comparison is made between the different available operations other than the statement that weight loss outcomes are similar for gastric banding and gastric bypass.
The book will appeal to and encourage prospective patients and they will use it as one of many aids in their decision to seek surgery. The glossary at the back is useful. It will also help bariatric trainees and members of the multidisciplinary team see a patient’s perspective and will remind them how difficult being obese is and the challenges (and rewards) of being a bariatric patient.
Thu Nov 10 14:55:21 UTC 2011
Katherine Wilkinson wrote:
Self‐expanding metallic stents for large bowel obstruction - Your View
We thank Mr Thorlacius for his interest in our article. The point raised is an important one and as mentioned seven of our patients undergoing stenting as a bridge to surgery had benign disease. As such we advised caution in interpretation of results related to adverse events in stents inserted as a bridge to surgery due to the presence of patients with benign pathology. With regard to time to stent migration we do not agree that this was related to a reduction in inflammatory swelling. Three of the stents migrated within the first few days and the other two experienced complications shortly after the first week post insertion. In our centre we no longer use stents routinely for benign obstruction in view of prior experience.
We agree that four patients with malignant disease is too small a number to draw any solid conclusions regarding utilization of stents as a bridge to surgery in malignant disease. We advised caution in interpreting our results here for the reasons outlined above. We recognize the absence of high quality evidence, in particular, randomized trials to clarify the role of self expandable metallic stents when used as a bridge to surgery in malignant disease.
Department of General Surgery, Aberdeen Royal Infirmary, Aberdeen, UK
Thu Nov 10 14:43:23 UTC 2011
Jess Tauber wrote:
Where does the 'inert pair' effect really kick in?
Question for the experts here. At what point in the PT does this happen where we can say it is less than more likely that 2 s electrons can participate in bonding easily with p,d,f? Given the 'knight's move' relation, it has to be after 3d, but where? What Z?
What I'm after here is some sort of 'balance point' dividing the PT into two parts. If it isn't at one element a range will do. Thanks.
Wed Nov 09 21:41:40 UTC 2011
Yet some triads are extremely useful in pointing out some of the 'nontraditional' relationships, since certain combinations cause these to be between, and not within, blocks. One would need to define different types of triadic relationships, as they tend to go with different structural features (for ex. nearest neighbor triads help define Mendeleev's Line). The question then arises as to how much of the periodic table can be built on these. I wonder whether this issue has been painstakingly examined in any kind of comprehensive, and mathematically plausible, manner.
Wed Nov 09 16:31:23 UTC 2011
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