Ultraviolet photodissociation action spectroscopy of the N-pyridinium cation

© 2015 AIP Publishing LLC. The S1←S0 electronic transition of the N-pyridinium ion (C5H5NH+) is investigated using ultraviolet photodissociation (PD) spectroscopy of the bare ion and also the N2-tagged complex. Gas-phase N-pyridinium ions photodissociate by the loss of molecular hydrogen (H2) in the photon energy range 37 000-45 000 cm-1 with structurally diagnostic ion-molecule reactions identifying the 2-pyridinylium ion as the exclusive co-product. The photodissociation action spectra reveal vibronic details that, with the aid of electronic structure calculations, support the proposal that dissociation occurs through an intramolecular rearrangement on the ground electronic state following internal conversion. Quantum chemical calculations are used to analyze the measured spectra. Most of the vibronic features are attributed to progressions of totally symmetric ring deformation modes and out-of-plane modes active in the isomerization of the planar excited state towards the non-planar excited state global minimum

Investigation of the microbial communities colonizing prepainted steel used for roofing and walling

© 2016 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd. Microbial colonization of prepainted steel, commonly used in roofing applications, impacts their aesthetics, durability, and functionality. Understanding the relevant organisms and the mechanisms by which colonization occurs would provide valuable information that can be subsequently used to design fouling prevention strategies. Here, next-generation sequencing and microbial community finger printing (T-RFLP) were used to study the community composition of microbes colonizing prepainted steel roofing materials at Burrawang, Australia and Kapar, Malaysia over a 52-week period. Community diversity was low and was dominated by Bacillus spp., cyanobacteria, actinobacteria, Cladosporium sp., Epicoccum nigrum, and Teratosphaeriaceae sp. Cultivation-based methods isolated approximately 20 different fungi and bacteria, some of which, such as E. nigrum and Cladosporium sp., were represented in the community sequence data. Fluorescence in situ hybridization imaging showed that fungi were the most dominant organisms present. Analysis of the sequence and T-RFLP data indicated that the microbial communities differed significantly between locations and changed significantly over time. The study demonstrates the utility of molecular ecology tools to identify and characterize microbial communities associated with the fouling of painted steel surfaces and ultimately can enable the targeted development of control strategies based on the dominant species responsible for fouling

A Flexible LDPC/Turbo Decoder Architecture

Low-density parity-check (LDPC) codes and convolutional Turbo codes are two of the most powerful error correcting codes that are widely used in modern communication systems. In a multi-mode baseband receiver, both LDPC and Turbo decoders may be required. However, the different decoding approaches for LDPC and Turbo codes usually lead to different hardware architectures. In this paper we propose a unified message passing algorithm for LDPC and Turbo codes and introduce a flexible soft-input soft-output (SISO) module to handle LDPC/Turbo decoding. We employ the trellis-based maximum a posteriori (MAP) algorithm as a bridge between LDPC and Turbo codes decoding. We view the LDPC code as a concatenation of n super-codes where each super-code has a simpler trellis structure so that the MAP algorithm can be easily applied to it. We propose a flexible functional unit (FFU) for MAP processing of LDPC and Turbo codes with a low hardware overhead (about 15% area and timing overhead). Based on the FFU, we propose an area-efficient flexible SISO decoder architecture to support LDPC/Turbo codes decoding. Multiple such SISO modules can be embedded into a parallel decoder for higher decoding throughput. As a case study, a flexible LDPC/Turbo decoder has been synthesized on a TSMC 90 nm CMOS technology with a core area of 3.2 mm2. The decoder can support IEEE 802.16e LDPC codes, IEEE 802.11n LDPC codes, and 3GPP LTE Turbo codes. Running at 500 MHz clock frequency, the decoder can sustain up to 600 Mbps LDPC decoding or 450 Mbps Turbo decoding.NokiaNokia Siemens Networks (NSN)XilinxTexas InstrumentsNational Science Foundatio

LipidXplorer: A Software for Consensual Cross-Platform Lipidomics

LipidXplorer is the open source software that supports the quantitative characterization of complex lipidomes by interpreting large datasets of shotgun mass spectra. LipidXplorer processes spectra acquired on any type of tandem mass spectrometers; it identifies and quantifies molecular species of any ionizable lipid class by considering any known or assumed molecular fragmentation pathway independently of any resource of reference mass spectra. It also supports any shotgun profiling routine, from high throughput top-down screening for molecular diagnostic and biomarker discovery to the targeted absolute quantification of low abundant lipid species. Full documentation on installation and operation of LipidXplorer, including tutorial, collection of spectra interpretation scripts, FAQ and user forum are available through the wiki site at: https://wiki.mpi-cbg.de/wiki/lipidx/index.php/Main_Page

Valorisation of Biowastes for the Production of Green Materials Using Chemical Methods

With crude oil reserves dwindling, the hunt for a sustainable alternative feedstock for fuels and materials for our society continues to expand. The biorefinery concept has enjoyed both a surge in popularity and also vocal opposition to the idea of diverting food-grade land and crops for this purpose. The idea of using the inevitable wastes arising from biomass processing, particularly farming and food production, is, therefore, gaining more attention as the feedstock for the biorefinery. For the three main components of biomass—carbohydrates, lipids, and proteins—there are long-established processes for using some of these by-products. However, the recent advances in chemical technologies are expanding both the feedstocks available for processing and the products that be obtained. Herein, this review presents some of the more recent developments in processing these molecules for green materials, as well as case studies that bring these technologies and materials together into final products for applied usage

Reactions of a distonic peroxyl radical anion influenced by SOMO-HOMO conversion: an example of anion-directed channel switching

In free radicals the singly occupied molecular orbital (SOMO) typically has the highest energy. Recent examples of distonic radical anions were found, however, to disobey the usual orbital configuration, with the singly occupied molecular orbital buried energetically underneath doubly occupied orbitals. This unusual ordering of electrons, which contradicts the aufbau principle, has been characterized as SOMO–HOMO orbital conversion and is expected to perturb radical anion reactivity by branching toward anion-driven over radical-driven processes. Here, we use ion trap mass spectrometry and ab initio calculations to demonstrate that SOMO–HOMO orbital conversion influences the reactivity of a distonic peroxyl radical anion. Experimentally, we generated a distonic radical anion of β-hydroxy glutaric acid, ˙CH2CH(OH)CH2C(O)O−, and investigated its subsequent reaction with O2 in the gas phase. Theoretical calculations predict that reactions proceed through five isomeric C4H6O5˙− intermediates, two of which exhibit SOMO–HOMO conversion. The detected product ions, corresponding to loss of ˙OH + CO2, ˙OH + HCHO, HO2˙, and HO2˙ + CO2 from the peroxyl radical, can all be reconciled by the proposed reaction mechanism. Finally, we compare the oxygen recombination reaction of the distonic radical ion to the corresponding neutral radical (i.e., ˙CH2CH(OH)CH2C(O)OH). These calculations demonstrate that SOMO–HOMO conversion results in channel switching in the distonic radical anion, suppressing radical-driven mechanisms and promoting pathways that directly involve the anion site

Evaluation of hindered amine light stabilisers and their N-chlorinated derivatives as antibacterial and antifungal additives for thermoset surface coatings

© 2016 Elsevier B.V. N-Halogenated amines or ‘halamines’ have attracted recent attention as potential biocides for materials and surface coatings application. Facile N-chlorination of the hindered amine light stabiliser (HALS) Tinuvin®770, bis-(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, was achieved by reaction with sodium dichloroisocyanurate. The chlorinated product was incorporated into a polyester-based paint formulated for coil coating, applied to test panels and subjected to high temperature curing conditions characteristic of the coil coating process (55 s at 262 °C). Rapid detection of N-chlorinated Tinuvin®770 in the cured coating was confirmed, using liquid extraction surface analysis-mass spectrometry, by the characteristic fragmentation patterns of the halamines observed upon collision-induced dissociation. Antimicrobial activity of the coating was determined by testing against the bacterium Pseudomonas aeruginosa and the fungus Cladosporium sp., two organisms that are known to colonise both internal and external surfaces in building and cladding applications. The activity of HALS and halamine containing coatings were compared against a commercial product containing an antimicrobial additive as well as control surfaces without additives. Significant activity against the bacterium, but not against the fungus was demonstrated for the parent HALS and halamine containing coatings. The possibility of regeneration of the halamines was also tested and confirmed by mass spectrometry, post-chlorination of samples showed no significant differences in activity between corresponding pairs of samples