From ether to acid: a plausible degradation pathway of glycerol dialkyl glycerol tetraethers

Glycerol dialkyl glycerol tetraethers (GDGTs) are ubiquitous microbial lipids with extensive demonstrated and potential roles as paleoenvironmental proxies. Despite the great attention they receive, comparatively little is known regarding their diagenetic fate. Putative degradation products of GDGTs, identified as hydroxyl and carboxyl derivatives, were detected in lipid extracts of marine sediment, seep carbonate, hot spring sediment and cells of the marine thaumarchaeon Nitrosopumilus maritimus. The distribution of GDGT degradation products in environmental samples suggests that both biotic and abiotic processes act as sinks for GDGTs. More than a hundred newly recognized degradation products afford a view of the stepwise degradation of GDGT via (1) ether bond hydrolysis yielding hydroxyl isoprenoids, namely, GDGTol (glycerol dialkyl glycerol triether alcohol), GMGD (glycerol monobiphytanyl glycerol diether), GDD (glycerol dibiphytanol diether), GMM (glycerol monobiphytanol monoether) and bpdiol (biphytanic diol); (2) oxidation of isoprenoidal alcohols into corresponding carboxyl derivatives and (3) chain shortening to yield C39and smaller isoprenoids. This plausible GDGT degradation pathway from glycerol ethers to isoprenoidal fatty acids provides the link to commonly detected head-to-head linked long chain isoprenoidal hydrocarbons in petroleum and sediment samples. The problematic C80to C82tetraacids that cause naphthenate deposits in some oil production facilities can be generated from H-shaped glycerol monoalkyl glycerol tetraethers (GMGTs) following the same process, as indicated by the distribution of related derivatives in hydrothermally influenced sediments.Seventh Framework Programme (European Commission) (ERC Grant 247153

Polymerisation of lignosulfonates by the laccase-HBT (1-hydroxybenzotriazole) system improves dispersibility

Prasetyo, Endry Nugroho et al.--The ability of laccases from Trametes villosa (TvL), Myceliophthora thermophila (MtL), Trametes hirsuta (ThL) and Bacillus subtilis (BsL) to improve the dispersion properties of calcium lignosulfonates 398 in the presence of HBT as a mediator was investigated. Size exclusion chromatography showed an extensive increase in molecular weight of the samples incubated with TvL and ThL by 107% and 572% from 28400 Da after 17 h of incubation, respectively. Interestingly, FTIR spectroscopy, 13C NMR and Py-GC/MS analysis of the treated samples suggested no substantial changes in the aromatic signal of the lignosulfonates, a good indication of the ability of TvL/ThL-HBT systems to limit their effect on functional groups without degrading the lignin backbone. Further, the enzymatic treatments led to a general increase in the dispersion properties, indeed a welcome development for its application in polymer blends.Financial support from the BIORENEW EU-project (NMP2-CT-2006-26456), Austrian Academic Exchange Programme (ÖEAD) and the Spanish projects BIO2007-28720-E, BIO2008-01533, and AGL2008-00709 is acknowledged.Peer reviewe

Polymerization of lignosulfonates by the laccase-HBT (1-hydroxybenzotriazole) system improves dispersibility

The ability of laccases from Trametes villosa (TvL), Myceliophthora thermophila (MtL), Trametes hirsuta (ThL) and Bacillus subtilis (BsL) to improve the dispersion properties of calcium lignosulfonates 398 in the presence of HBT as a mediator was investigated. Size exclusion chromatography showed an extensive increase in molecular weight of the samples incubated with TvL and ThL by 107% and 572% from 28400 Da after 17 h of incubation, respectively. Interestingly, FTIR spectroscopy, 13C NMR and Py-GC/MS analysis of the treated samples suggested no substantial changes in the aromatic signal of the lignosulfonates, a good indication of the ability of TvL/ThL-HBT systems to limit their effect on functional groups without degrading the lignin backbone. Further, the enzymatic treatments led to a general increase in the dispersion properties, indeed a welcome development for its application in polymer blends.Financial support from the BIORENEW EU-project (NMP2-CT-2006-26456), Austrian Academic Exchange Programme (OEAD) and the Spanish projects BIO2007-28720-E, BIO2008-01533, and AGL2008-00709 is acknowledged

Removal and Reconstitution of the Carotenoid Antenna of Xanthorhodopsin

Salinixanthin, a C40-carotenoid acyl glycoside, serves as a light-harvesting antenna in the retinal-based proton pump xanthorhodopsin of Salinibacter ruber. In the crystallographic structure of this protein, the conjugated chain of salinixanthin is located at the protein–lipid boundary and interacts with residues of helices E and F. Its ring, with a 4-keto group, is rotated relative to the plane of the π-system of the carotenoid polyene chain and immobilized in a binding site near the β-ionone retinal ring. We show here that the carotenoid can be removed by oxidation with ammonium persulfate, with little effect on the other chromophore, retinal. The characteristic CD bands attributed to bound salinixanthin are now absent. The kinetics of the photocycle is only slightly perturbed, showing a 1.5-fold decrease in the overall turnover rate. The carotenoid-free protein can be reconstituted with salinixanthin extracted from the cell membrane of S. ruber. Reconstitution is accompanied by restoration of the characteristic vibronic structure of the absorption spectrum of the antenna carotenoid, its chirality, and the excited-state energy transfer to the retinal. Minor modification of salinixanthin, by reducing the carbonyl C=O double bond in the ring to a C-OH, suppresses its binding to the protein and eliminates the antenna function. This indicates that the presence of the 4-keto group is critical for carotenoid binding and efficient energy transfer

Beamforming in 5G mm-wave radionetworks : Importance of frequency multiplexing for users in urban macro environments

5G brings a few key technological improvements compared to previous generations in telecommunications. These include, but are not limited to, greater speeds, increased capacity and lower latency. These improvements are in part due to using high band frequencies, where increased capacity is found. By advancements in various technologies, mobile broadband traffic has become increasingly chatty, i.e. more small packets are being sent. From a capacity standpoint this characteristic poses a challenge for early 5G millimeter-wave advanced antenna systems. This thesis investigates if network performance of 5G millimetre-wave systems can be improved by increasing the utilisation of the bandwidth by using adaptive beamforming. Two adaptive codebook approaches are proposed; a single- beam and a multi-beam approach. The simulations are performed in an outdoor urban macro scenario. The results show that for a small packet scenario with good coverage the ability to frequency multiplex users is important for good network performance

Beamforming in 5G mm-wave radionetworks : Importance of frequency multiplexing for users in urban macro environments

5G brings a few key technological improvements compared to previous generations in telecommunications. These include, but are not limited to, greater speeds, increased capacity and lower latency. These improvements are in part due to using high band frequencies, where increased capacity is found. By advancements in various technologies, mobile broadband traffic has become increasingly chatty, i.e. more small packets are being sent. From a capacity standpoint this characteristic poses a challenge for early 5G millimeter-wave advanced antenna systems. This thesis investigates if network performance of 5G millimetre-wave systems can be improved by increasing the utilisation of the bandwidth by using adaptive beamforming. Two adaptive codebook approaches are proposed; a single- beam and a multi-beam approach. The simulations are performed in an outdoor urban macro scenario. The results show that for a small packet scenario with good coverage the ability to frequency multiplex users is important for good network performance

Probability of Positive Identification with an IFF E-scan System

Both military and civil aircrafts depend on a built-in identification system called SSR on a daily basis. IFF is the military adaption of the system for use by fighter jets in order to separate friendly aircrafts from foes but also to coexist with commercial aircrafts. The system is built around two devices, an interrogator on the own aircraft and a transponder on the target. The aim is to be able to perform an interrogation with as high probability of correct identification as possible. There are several factors that can compromise or prohibit a friendly aircraft from answering to an interrogation and it should therefore not be classified as a foe. In this master thesis work, the ability of identification for Saab AB’s new fighter jet Gripen E has been investigated. A system model has been created using Simulink and Matlab, mirroring a full link connection between the IFF E-scan system on Gripen E and a target aircraft. The model includes six subsystems, covering the fighter jet’s antenna array system in both transmitter and receiver mode, the transponder equipment, link budgets and signal propagation. Different data sets with main and control beam antenna patterns for the Gripen E IFF system are loaded into the model via user selected beam steering.. It has been found that the model simulates the environmental effects on the transmitted patetrns at different distances well. It can be used to investigate how the antenna coverage changes when applying beam steering to the E-scan system and at which distances identification is possible for a chosen steering angle.

Probability of Positive Identification with an IFF E-scan System

Both military and civil aircrafts depend on a built-in identification system called SSR on a daily basis. IFF is the military adaption of the system for use by fighter jets in order to separate friendly aircrafts from foes but also to coexist with commercial aircrafts. The system is built around two devices, an interrogator on the own aircraft and a transponder on the target. The aim is to be able to perform an interrogation with as high probability of correct identification as possible. There are several factors that can compromise or prohibit a friendly aircraft from answering to an interrogation and it should therefore not be classified as a foe. In this master thesis work, the ability of identification for Saab AB’s new fighter jet Gripen E has been investigated. A system model has been created using Simulink and Matlab, mirroring a full link connection between the IFF E-scan system on Gripen E and a target aircraft. The model includes six subsystems, covering the fighter jet’s antenna array system in both transmitter and receiver mode, the transponder equipment, link budgets and signal propagation. Different data sets with main and control beam antenna patterns for the Gripen E IFF system are loaded into the model via user selected beam steering.. It has been found that the model simulates the environmental effects on the transmitted patetrns at different distances well. It can be used to investigate how the antenna coverage changes when applying beam steering to the E-scan system and at which distances identification is possible for a chosen steering angle.