A one‐flask reaction sequence comprising ring closing metathesis (RCM) of butenoates derived from allylic alcohols and a base‐mediated ring opening gives 2Z,4E‐configured dienoic acids in high yields ...and stereoselectivities. Application of the method to the synthesis of the natural product fusanolide A suggests that the originally published structure was erroneously assigned and should be revised.
Ring closing metathesis (RCM) of butenoates derived from allylic alcohols can be combined with base‐induced ring opening in a one‐flask sequence. In this way, dienoic acids become accessible in an operationally simple procedure in very high yields and excellent stereoselectivities, with the tether remaining in the product as a valuable functional group for further transformations.
Allylphosphonates of allylic alcohols were converted to conjugated dienyl phosphonates in a one-flask reaction, comprising a ring-closing metathesis (RCM), a base-induced ring-opening, and an ...alkylation. The ring-opening proceeds with very high diastereoselectivity, giving exclusively the (1Z,3E)-configured dienes. Single diastereomers and mixtures of diastereomers can be used as starting materials without noticeable effect on the diastereoselectivity of the sequence.
The successful application of
and
in brewery fermentations has highlighted the potential of wild
yeasts for brewing, and prompted investigation into the application potential of other members of the ...genus. Here, we evaluate, for the first time, the brewing potential of
. The newly isolated strain from an ash tree (
) in Upper Bavaria, Germany, close to the river Isar, was used to ferment a 12°P wort at 15°C. Performance was compared directly with that of a reference lager strain (TUM 34/70) and the
type strain. Both wild yeast rapidly depleted simple sugars and thereafter exhibited a lag phase before maltose utilization. This phase lasted for 4 and 10 days for
and
, respectively.
utilized fully the available maltose but, consistent with previous reports, did not use maltotriose.
, in contrast, utilized approximately 50% of the maltotriose available, making this the first report of maltotriose utilization in a wild
species. Maltotriose use was directly related to alcohol yield with 5.5, 4.9, and 4.5% ABV produced by
,
, and
. Beers also differed with respect to aroma volatiles, with a high level (0.4 mg/L) of the apple/aniseed aroma ethyl hexanoate in
beers, while
beers had a high level of phenylethanol (100 mg/L). A trained panel rated all beers as being of high quality, but noted clear differences. A phenolic spice/clove note was prominent in
beer. This was less pronounced in the
beers, despite analytical levels of 4-vinylguaiacol being similar. Tropical fruit notes were pronounced in
beers, possibly resulting from the high level of ethyl hexanoate. Herein, we present results from the first intentional application of
as a yeast for beer fermentation (at the time of submission) and compare its fermentation performance to other species of the genus. Results indicate considerable potential for
application in brewing, with clear advantages compared to other wild
species.
Starting from the conveniently available ex-chiral pool building block (
R
,
R
)-hexa-1,5-diene-3,4-diol, the ten-membered ring lactones stagonolide E and curvulide A were synthesized using a ...bidirectional olefin-metathesis functionalization of the terminal double bonds. Key steps are (i) a site-selective cross metathesis, (ii) a highly diastereoselective extended tethered RCM to furnish a (
Z
,
E
)-configured dienyl carboxylic acid and (iii) a Ru–lipase-catalyzed dynamic kinetic resolution to establish the desired configuration at C9. Ring closure was accomplished by macrolactonization. Curvulide A was synthesized from stagonolide E through Sharpless epoxidation.
The hydrogen plasma passivation of thin film polycrystalline silicon (pc-Si) was investigated in conjunction with plasma texturing process to make efficient heterojunction solar cells. The pc-Si ...layers were first treated using direct and remote hydrogen plasma technologies. The heterojunction solar cells were then fabricated by subsequent deposition of i/n+ a-Si:H. Hydrogenation at high temperature (610°C) results in enhanced dissolution and diffusion of hydrogen in pc-Si by a factor of about 3 and 4, respectively, in comparison with those at low temperature (420°C). The hydrogen atoms in the pc-Si layer mainly bond to the silicon dangling bonds and form complexes with dopant atoms. In addition, platelets defects are generated by the hydrogen plasma in the sub-surface region of pc-Si hydrogenated at 420°C and cause higher saturation current in the space charge region whilst they form in the region deeper than 1μm at 610°C. Removal of the platelets using SF6/N2O plasma post-texturing after low-temperature hydrogenation not only enhances the short circuit current but also improves the open circuit voltage and the fill factor simultaneously. Combining plasma pre-texturing with high-temperature hydrogenation, the best 2µm-thick pc-Si heterojunction solar cell reaches an efficiency of 8.54%.
Display omitted The passivation of thin film polycrystalline silicon solar cells is investigated using direct and remote hydrogen plasma. The relationship between the hydrogen induced defects and the recombination within the space charge region of the heterojunction solar cells is established. Simultaneous enhancement of the voltage and the current and 8.54% efficiency are achieved with synergistic plasma texturing.
•Direct and remote plasma hydrogenation were investigated for the thin film polycrystalline silicon (pc-Si) heterojunction solar cells.•High temperature remote hydrogen plasma facilitates the passivation of defects in pc-Si.•Hydrogenation can induce platelet defects in the sub-surface of pc-Si layer, leading to increased recombination in the space charge region.•Plasma texturing realises defect removal and light trapping at the same time.•8.54% efficiency was achieved using remote hydrogenation at 610°C and pre-passivation texturing.
To operate photovoltaic power plants at maximum capacity, it is desirable to identify cell or module failures in the field at the earliest possible stage. Currently used field inspection methods ...cannot detect many of the electronic defects that can be revealed with luminescence‐based techniques. In this work, photoluminescence images are acquired using the sun as the sole illumination source by separating the weak luminescence signal from the much stronger ambient sunlight signal. This is done by using an appropriate choice of optical filtering and modulation of the cells' bias between the normal operating point and open circuit condition. The switching is achieved by periodically changing the optical generation rate of at least one cell within the module. This changes the biasing condition of all other cells that are connected to the same bypass diode. This method has the advantage that it can deliver high quality images revealing electrical defects in individual cells and entire modules, without requiring any changes to the electrical connections of the photovoltaic system.
High resolution outdoor photoluminescence image of photovoltaic module was obtained under full sunlight using contactless modulation method (Figure A) that can identify various defects that lead to power loss. This image was compared to the indoor electroluminescence image (Figure B). The contactless luminescence modulation is achieved by periodically changing the optical generation rate of at least one cell within the module, which in turn changes the biasing condition of all other cells that are connected to the same bypass diode.
Monitoring the performance of solar modules in a photovoltaic system is critical in order to understand the health of the system. Existing methods for field inspection have limited capability of ...detecting various electronic defects that can, however, be identified with luminescence‐based methods. A contactless outdoor photoluminescence‐imaging based measurement method that uses the sun as the excitation source was presented in our earlier work. This paper extends our previous work and presents two unique applications to (a) identify and quantify local areas of high series resistance within the cells and (b) identify bypass diodes that have failed in open‐circuit. The paper also discusses specific technical considerations of this method. The main merit of this method is that it can be used when the module is under normal operation in the field, without requiring changing of the electrical wiring of the photovoltaic array.
Photovoltaic (PV) electricity generation is the fastest growing energy source globally and also humanity's best opportunity to achieve the urgently required deep decarbonisation of the energy sector. ...As PV enters the terawatt scale, with millions of modules in a single PV power plant, quality testing of installed PV modules becomes indispensable to guarantee PV as a reliable long‐term source of electricity. We present a method that extends the use of photoluminescence (PL) imaging to field‐deployed solar modules in full sunlight. The method takes advantage of sunlight absorption in the Earth's atmosphere in a narrow spectral range around 1,135‐nm wavelength and recent developments in ultranarrow bandpass optical filter technology. The technical principles and experimental data are provided. This method lays the foundations for PL imaging, a powerful inspection method for the PV industry and research, to be applied to routine high‐volume inspection of fielded PV modules on large‐scale solar power plants.
We present a method that extends the use of photoluminescence (PL) imaging to field‐deployed solar modules in full sunlight. The method takes advantage of sunlight absorption in the Earth's atmosphere in a narrow spectral range around 1,135‐nm wavelength and recent developments in ultranarrow bandpass optical filter technology. This method lays the foundations for PL imaging, a powerful inspection method for the PV industry and research, to be applied to routine high‐volume inspection of fielded PV modules on large‐scale solar power plants.
Cover Image Rey, Germain; Kunz, Oliver; Green, Martin ...
Progress in photovoltaics,
September 2022, Volume:
30, Issue:
9
Journal Article
Peer reviewed
The cover image is based on the Research Article Luminescence imaging of solar modules in full sunlight using ultranarrow bandpass filters by Germain Rey et al., https://doi.org/10.1002/pip.3563.
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