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https://www.readbyqxmd.com/read/28239970/atmospheric-pressure-chemical-ionization-of-explosives-induced-by-soft-x-radiation-in-ion-mobility-spectrometry-mass-spectrometric-investigation-of-the-ionization-reactions-of-drift-gasses-dopants-and-alkyl-nitrates
#1
Daniel Riebe, Alexander Erler, Thomas Ritschel, Toralf Beitz, Hans-Gerd Löhmannsröben, Andreas Beil, Michael Blaschke, Thomas Ludwig
A promising replacement for the radioactive sources commonly encountered in ion mobility spectrometers is a miniaturized, energy-efficient photoionization source that produce the reactant ions via soft X-radiation (2.8 keV). In order to successfully apply the photoionization source, it is imperative to know the spectrum of reactant ions and the subsequent ionization reactions leading to the detection of analytes. To that end, an ionization chamber based on the photoionization source that reproduces the ionization processes in the ion mobility spectrometer and facilitates efficient transfer of the product ions into a mass spectrometer was developed...
August 2016: Journal of Mass Spectrometry: JMS
https://www.readbyqxmd.com/read/28239969/quantum-chemical-mass-spectrometry-ab-initio-prediction-of-electron-ionization-mass-spectra-and-identification-of-new-fragmentation-pathways
#2
Julie Cautereels, Magda Claeys, Davy Geldof, Frank Blockhuys
The electron ionization mass spectra of four organic compounds are predicted based on the results of quantum chemical calculations at the DFT/B3LYP/6-311 + G* level of theory. This prediction is performed 'ab initio', i.e. without any prior knowledge of the thermodynamics or kinetics of the reactions under consideration. Using a set of rules determining which routes will be followed, the fragmentation of the molecules' bonds and the complete resulting fragmentation pathways are studied. The most likely fragmentation pathways are identified based on calculated reaction energies ΔE when bond cleavage is considered and on activation energies ΔE(‡) when rearrangements are taken into account; the final intensities of the peaks in the spectrum are estimated from these values...
August 2016: Journal of Mass Spectrometry: JMS
https://www.readbyqxmd.com/read/28239727/twist-it-the-acid-dependent-isomerization-of-homoleptic-carbenic-iridium-iii-complexes
#3
Jaroslaw G Osiak, Tobias Setzer, Peter G Jones, Christian Lennartz, Andreas Dreuw, Wolfgang Kowalsky, Hans-Hermann Johannes
The first successful meridional to facial isomerization of homoleptic carbenic iridium(iii) complexes is presented. The Brønsted-acid-mediated procedure allows the conversion of large amounts of material and additionally provides an in situ purification because of precipitation of the target material during the reaction. The pronounced acid-dependency of the reaction yield observed for tris(N-phenyl,N-methyl-benzimidazol-2-yl)iridium(iii) and tris(N-phenyl,N-benzyl-benzimidazol-2-yl)iridium(iii) was investigated by labelling experiments and quantum chemical calculations...
February 27, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28239705/chemical-communication-and-dynamics-of-droplet-emulsions-in-networks-of-belousov-zhabotinsky-micro-oscillators-produced-by-microfluidics
#4
Kristian Torbensen, Federico Rossi, Sandra Ristori, Ali Abou-Hassan
Chemical communication leading to synchronization and collective behaviour of dynamic elements, such as cell colonies, is a widespread phenomenon with biological, physical and chemical importance. Such synchronization between elements proceeds via chemical communication by emmision, interdiffusion and reception of specific messenger molecules. On a lab scale, these phenomena can be modeled by encapsulating an oscillating chemical reaction, which serves as a signal (information) sender/receiver element, inside microcompartments such as droplet emulsions, liposomes and polymersomes...
February 27, 2017: Lab on a Chip
https://www.readbyqxmd.com/read/28239429/future-challenges-in-heterogeneous-catalysis-understanding-catalysts-under-dynamic-reaction-conditions
#5
Kai F Kalz, Ralph Kraehnert, Muslim Dvoyashkin, Roland Dittmeyer, Roger Gläser, Ulrike Krewer, Karsten Reuter, Jan-Dierk Grunwaldt
In the future, (electro-)chemical catalysts will have to be more tolerant towards a varying supply of energy and raw materials. This is mainly due to the fluctuating nature of renewable energies. For example, power-to-chemical processes require a shift from steady-state operation towards operation under dynamic reaction conditions. This brings along a number of demands for the design of both catalysts and reactors, because it is well-known that the structure of catalysts is very dynamic. However, in-depth studies of catalysts and catalytic reactors under such transient conditions have only started recently...
January 9, 2017: ChemCatChem
https://www.readbyqxmd.com/read/28239299/synthetic-curcumin-derivative-dk1-possessed-g2-m-arrest-and-induced-apoptosis-through-accumulation-of-intracellular-ros-in-mcf-7-breast-cancer-cells
#6
Norlaily Mohd Ali, Swee Keong Yeap, Nadiah Abu, Kian Lam Lim, Huynh Ky, Ahmad Zaim Mat Pauzi, Wan Yong Ho, Sheau Wei Tan, Han Kiat Alan-Ong, Seema Zareen, Noorjahan Banu Alitheen, M Nadeem Akhtar
AIMS: Curcumin is a lead compound of the rhizomes of Curcuma longa and possess a broad range of pharmacological activities. Chemically, curcumin is 1,3-dicarbonyl class of compound, which exhibits keto-enol tautomerism. Despite of its strong biological properties, curcumin has yet been recommended as a therapeutic agent because of its poor bioavailability. MAIN METHODS: A curcumin derivative (Z)-3-hydroxy-1-(2-hydroxyphenyl)-3-phenylprop-2-en-1-one (DK1) was synthesized and its cytotoxicity was tested on breast cancer cell MCF-7 and normal cell MCF-10A using MTT assay...
2017: Cancer Cell International
https://www.readbyqxmd.com/read/28239226/temperature-and-moisture-dependent-studies-on-alunogen-and-the-crystal-structure-of-meta-alunogen-determined-from-laboratory-powder-diffraction-data
#7
Volker Kahlenberg, Doris E Braun, Hannes Krüger, Daniela Schmidmair, Maria Orlova
Starting from a synthetic sample with composition Al2(SO4)3·16.6H2O, the high-temperature- and moisture-dependent behavior of alunogen has been unraveled by TGA measurements, in situ powder X-ray diffraction as well as by gravimetric moisture sorption/desorption studies. Heating experiments using the different techniques show that alunogen undergoes a first dehydration process already starting at temperatures slightly above 40 °C. The crystalline product of the temperature-induced dehydration corresponds to the synthetic equivalent of meta-alunogen and has the following chemical composition: Al2(SO4)3·13...
2017: Physics and Chemistry of Minerals
https://www.readbyqxmd.com/read/28238759/in-vitro-metabolic-engineering-for-the-production-of-%C3%AE-ketoglutarate
#8
Barbara Beer, André Pick, Volker Sieber
α-Ketoglutarate (aKG) represents a central intermediate of cell metabolism. It is used for medical treatments and as a chemical building block. Enzymatic cascade reactions have the potential to sustainably synthesize this natural product. Here we report a systems biocatalysis approach for an in vitro reaction set-up to produce aKG from glucuronate using the oxidative pathway of uronic acids. Because of two dehydrations, a decarboxylation, and reaction conditions favoring oxidation, the pathway is driven thermodynamically towards complete product formation...
February 22, 2017: Metabolic Engineering
https://www.readbyqxmd.com/read/28237221/performance-analysis-of-a-continuous-serpentine-flow-reactor-for-electrochemical-oxidation-of-synthetic-and-real-textile-wastewater-energy-consumption-mass-transfer-coefficient-and-economic-analysis
#9
Indu M Sasidharan Pillai, Ashok K Gupta
A continuous flow electrochemical reactor was developed, and its application was tested for the treatment of textile wastewater. A parallel plate configuration with serpentine flow was chosen for the continuous flow reactor. Uniparameter optimization was carried out for electrochemical oxidation of synthetic and real textile wastewater (collected from the inlet of the effluent treatment plant). Chemical Oxygen Demand (COD) removal efficiency of 90% was achieved for synthetic textile wastewater (initial COD - 780 mg L(-1)) at a flow rate of 500 mL h(-1) (retention time of 6 h) and a current density of 1...
February 23, 2017: Journal of Environmental Management
https://www.readbyqxmd.com/read/28237092/response-to-antiseptic-agents-of-periodontal-pathogens-in-in-vitro-biofilms-on-titanium-and-zirconium-surfaces
#10
M C Sánchez, E Fernández, A Llama-Palacios, E Figuero, D Herrera, M Sanz
OBJECTIVE: The aim of this study was to develop in vitro biofilms on SLA titanium (Ti-SLA) and zirconium oxide (ZrO2) surfaces and to evaluate the effect of antiseptic agents on the number of putative periodontal pathogenic species. METHODS: An in vitro biofilm model was developed on sterile discs of Ti-SLA and ZrO2. Three antiseptic agents [chlorhexidine and cetyl-pyridinium-chloride (CHX/CPC), essential oils (EEOOs) and cetyl-peridinium-chloride (CPC)] were applied to 72-h biofilms, immersing discs during 1min in the antiseptic solution, either with or without mechanical disruption...
February 22, 2017: Dental Materials: Official Publication of the Academy of Dental Materials
https://www.readbyqxmd.com/read/28236787/apigenin-7-o-glucoside-oxidation-catalyzed-by-p450-bioinspired-systems
#11
Lucas B Bolzon, Joicy S Dos Santos, Denise B Silva, Eduardo J Crevelin, Luiz A B Moraes, Norberto P Lopes, Marilda D Assis
Apigenin-7-O-glucoside (A7G) is the main flavonoid of Bidens gardneri Bak., a Brazilian plant with wide application in folk medicine. Despite the popular use of this plant, its biological effects are not completely known. This work tested the 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin iron(III) and manganese(III) chloride (Fe(TFPP)Cl and Mn(TFPP)Cl), and Jacobsen's catalyst as P450-bioinspired catalysts for A7G oxidation by different oxidants (PhIO, H2O2, m-CPBA, and t-BuOOH). Up to nine different products were detected by HPLC analysis; Reactions with metalloporphyrin/PhIO systems afforded high catalytic conversions (58-89%)...
February 20, 2017: Journal of Inorganic Biochemistry
https://www.readbyqxmd.com/read/28236711/mechanisms-of-hydrogen-sulfide-removal-by-ground-granulated-blast-furnace-slag-amended-soil
#12
Mengyao Xie, Anthony Kwan Leung, Charles Wang Wai Ng
Ground granulated blast furnace slag (GGBS) amended soil has been found able to remove gaseous hydrogen sulfide (H2S). However, how H2S is removed by GGBS amended soil and why GGBS amended soil can be regenerated to remove H2S are not fully understood. In this study, laboratory column tests together with chemical analysis were conducted to investigate and reveal the mechanisms of H2S removal process in GGBS amended soil. Sulfur products formed on the surface of soil particle and in pore water were quantified...
February 6, 2017: Chemosphere
https://www.readbyqxmd.com/read/28236666/the-epsilon-motif-of-hepatitis-b-virus-rna-exhibits-a-potassium-dependent-ribonucleolytic-activity
#13
Dibyajnan Chakraborty, Sagarmoy Ghosh
Fourteen different classes of ribozymes are known that catalyze a range of diverse chemical reactions. We report here a novel potassium-dependent nucleolytic activity present in Hepatitis B Virus (HBV) RNA. A short RNA region (53 nt) with enzymatic properties released itself from the viral sequence by cis cleavages and could subsequently act in trans. The released region encompassed the epsilon motif present in the HBV RNA. The 3' end of the liberated fragment was within the non-canonical polyadenylation signal (UAUAAA) of the viral RNA while cleavages at about 53 nt upstream sites released the fragment...
February 25, 2017: FEBS Journal
https://www.readbyqxmd.com/read/28236581/single-simultaneous-and-sequential-applications-of-ultrasonic-frequencies-for-the-elimination-of-ibuprofen-in-water
#14
Asu Ziylan-Yavas, Nilsun H Ince
The study is about the assessment of single and multi-frequency operations for the overall degradation of a widely consumed analgesic pharmaceutical-ibuprofen (IBP). The selected frequencies were in the range of 20-1130kHz emissions coming from probes, baths and piezo-electric transducers attached to plate-type devices. Multi-frequency operations were applied either simultaneously as "duals", or sequentially at fixed time intervals; and the total reaction time in all operations was 30-min. The work also covers evaluation of the effect of zero-valent iron (ZVI) on the efficiency of the degradation process and the performance of the reaction systems...
January 26, 2017: Ultrasonics Sonochemistry
https://www.readbyqxmd.com/read/28235460/tyrozine-d-oxidation-and-redox-equilibrium-in-photosystem-ii
#15
Nigar Ahmadova, Felix Ho, Stenbjorn Styring, Fikret Mamedov
Tyrosine D (TyrD) is an auxiliary redox active tyrosine residue in photosystem II (PsiI). The mechanism of TyrD oxidation was investigated by EPR spectroscopy, flash-induced fluorescence decay and thermoluminescence measurements in PsiI enriched membranes from spinach. PsiI membranes were chemically treated with 3mM ascorbate and 1mM diaminodurene and subsequent washing, leading to the complete reduction of TyrD. TyrD oxidation kinetics and competing recombination reactions were measured after a single saturating flash in the absence and presence of DCMU (inhibitor of the QB-site) in the pH range of 4...
February 21, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28231608/quantitative-analysis-of-malondialdehyde-guanine-adducts-in-genomic-dna-samples-by-liquid-chromatography-tandem-mass-spectrometry
#16
S A Yates, N M Dempster, M F Murphy, S A Moore
RATIONALE: The lipid peroxidation product malondialdehyde forms M1 dG adducts with guanine bases in genomic DNA. The analysis of these adducts is important as a biomarker of lipid peroxidation, oxidative stress and inflammation which may be linked to disease risk or exposure to a range of chemicals. METHODS: Genomic DNA samples were subjected to acid hydrolysis to release the adducts in the base form (M1 G) alongside the other purines. A liquid chromatography-mass spectrometry method was optimised for the quantitation of the M1 G adducts in genomic DNA samples using product ion and multiple reaction mode scans...
February 23, 2017: Rapid Communications in Mass Spectrometry: RCM
https://www.readbyqxmd.com/read/28231539/a-new-model-to-predict-diffusive-self-heating-during-composting-incorporating-the-reaction-engineering-approach-rea-framework
#17
Aditya Putranto, Xiao Dong Chen
During composting, self-heating may occur due to the exothermicities of the chemical and biological reactions. An accurate model for predicting maximum temperature is useful in predicting whether the phenomena would occur and to what extent it would have undergone. Elevated temperatures would lead to undesirable situations such as the release of large amount of toxic gases or sometimes would even lead to spontaneous combustion. In this paper, we report a new model for predicting the profiles of temperature, concentration of oxygen, moisture content and concentration of water vapor during composting...
February 1, 2017: Bioresource Technology
https://www.readbyqxmd.com/read/28231432/dismantling-the-red-wall-of-colloidal-perovskites-highly-luminescent-formamidinium-and-formamidinium-cesium-lead-iodide-nanocrystals
#18
Loredana Protesescu, Sergii Yakunin, Sudhir Kumar, Janine Bär, Federica Bertolotti, Norberto Masciocchi, Antonietta Guagliardi, Matthias Grotevent, Ivan Shorubalko, Maryna I Bodnarchuk, Chih-Jen Shih, Maksym V Kovalenko
Colloidal nanocrystals (NCs) of APbX3-type lead halide perovskites [A=Cs+, CH3NH3+ (methylammonium or MA+) or CH(NH2)2+ (formamidinium or FA+); X=Cl-, Br-, I-] have recently emerged as highly versatile photonic sources for applications ranging from simple photoluminescence down-conversion (e.g., for display backlighting) to light emitting diodes. From the perspective of spectral coverage, a formidable challenge facing the use of these materials is how to obtain stable emissions in the red and infrared spectral regions covered by the iodide-based compositions...
February 23, 2017: ACS Nano
https://www.readbyqxmd.com/read/28231160/sourdough-based-biotechnologies-for-the-production-of-gluten-free-foods
#19
REVIEW
Luana Nionelli, Carlo Giuseppe Rizzello
Sourdough fermentation, a traditional biotechnology for making leavened baked goods, was almost completely replaced by the use of baker's yeast and chemical leavening agents in the last century. Recently, it has been rediscovered by the scientific community, consumers, and producers, thanks to several effects on organoleptic, technological, nutritional, and functional features of cereal-based products. Acidification, proteolysis, and activation of endogenous enzymes cause several changes during sourdough fermentation, carried out by lactic acid bacteria and yeasts, which positively affect the overall quality of the baked goods...
September 20, 2016: Foods (Basel, Switzerland)
https://www.readbyqxmd.com/read/28231014/cyclombandakamines-a1-and-a2-oxygen-bridged-naphthylisoquinoline-dimers-from-a-congolese-ancistrocladus-liana
#20
Blaise Kimbadi Lombe, Torsten Bruhn, Doris Feineis, Virima Mudogo, Reto Brun, Gerhard Bringmann
Cyclombandakamines A1 (1) and A2 (2), both with an unprecedented pyrane-cyclohexenone-dihydrofuran sequence and six stereocenters and two chiral axes, are the first oxygen-bridged dimeric naphthylisoquinoline alkaloids. They were isolated from the leaves of an as yet unidentified Congolese Ancistrocladus species. Their stereostructures were established by spectroscopic, chemical, and chiroptical methods in combination with DFT and TDDFT calculations. They apparently originate from a cascade of oxidative cyclization reactions of "open-chain" naphthylisoquinoline dimers and exhibit significant antiprotozoal activities...
February 23, 2017: Organic Letters
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