901 research outputs found

    Unambiguous identification of esters as oligomers in secondary organic aerosol formed from cyclohexene and cyclohexene/α-pinene ozonolysis

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    The build-up of oligomeric compounds during secondary organic aerosol (SOA) formation is subject of atmospheric research since several years. New particle formation and especially the SOA mass yield might be influenced significantly by oligomer formation. However, the chemical nature of observed oligomers and their formation pathways are still unclear. In this paper, the structural characterization of certain dimeric compounds (esters) formed during the ozonolysis of cyclohexene and cyclohexene/α-pinene mixtures are presented. The identification is based on the comparison of the mass spectra and the retention times (LC) of the oligomeric products with synthesized reference compounds. Cyclohexene is used here as a model compound for terpenes as globally most important SOA precursors, since it possesses a simpler structure than the biogenic alkenes and therefore offers the possibility to get access to reference compounds for certain of its oxidation products. In addition to cyclohexene, the formation of esters could also be observed in experiments with α-pinene as reactant

    Photodissociation of Conformer-Selected Ubiquitin Ions Reveals Site-Specific Cis/Trans Isomerization of Proline Peptide Bonds

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    Ultraviolet photodissociation (UVPD) of gas-phase proteins has attracted increased attention in recent years. This growing interest is largely based on the fact that, in contrast to slow heating techniques such as collision induced dissociation (CID), the cleavage propensity after absorption of UV light is distributed over the entire protein sequence, which can lead to a very high sequence coverage as required in typical top-down proteomics applications. However, in the gas phase, proteins can adopt a multitude of distinct and sometimes coexisting conformations, and it is not clear how this three-dimensional structure affects the UVPD fragmentation behavior. Using ion mobility–UVPD–mass spectrometry in conjunction with molecular dynamics simulations, we provide the first experimental evidence that UVPD is sensitive to the higher order structure of gas-phase proteins. Distinct UVPD spectra were obtained for different extended conformations of 11+ ubiquitin ions. Assignment of the fragments showed that the majority of differences arise from cis/trans isomerization of one particular proline peptide bond. Seen from a broader perspective, these data highlight the potential of UVPD to be used for the structural analysis of proteins in the gas phas

    З історії озброєння козацького війська першої половини 18 ст.

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    В низці реформ, які спіткали у 18 ст. військо гетьманського регіменту, та їхня невелика частина, котра стосувалася озброєння є чи не найменше відомою не тільки широкому загалу істориків, але й вузьким спеціалістам з періоду. Перші спроби прищеплення козакам “регулярства” ще з часів Петра І були спрямовані головним чином, на впровадження адміністративних і організаційних новацій, впорядкування фінансування й забезпечення при одночасному нехтуванні власне озброєнням і бойовою підготовкою війська. Втім, саме вони після Північної війни і “Низових” походів, які виявили всі недоліки, притаманні становій організації збройних сил, дуже гостро поставили питання боєздатності козацьких полків. Наріжною проблемою була якість озброєння реєстрових козаків. Як відомо, для цієї частини гетьманського війська традиційно не існувало жодних регламентацій, що б визначали види й перелік озброєння, термін його служби, навчання застосування тощо. Виняток становили лише наймані формування, забезпечення яких вогнепальною й деякими іншими видами зброї, а також боєприпасами, перебрала на себе держава [1]. На початку 18 ст. комплекс озброєння лівобережного козацтва загалом мало чим відрізнявся від попереднього століття, складаючись з традиційних піки, шаблі, різноманітних видів рушниць й іноді – пістолів і луків зі стрілами [2]. Кожен козак мусив власним коштом купувати необхідну йому амуніцію та зброю, вряди-годи дістаючи зі скарбу лише боєприпаси до неї. В умовах постійно прогресуючої майнової диференціації козацтва це призводило з одного боку до того, що частина збіднілого товариства взагалі не могла відбувати воєнну службу, а та, що була спроможною оплачувати спорядження, озброювалася відповідно не до воєнних потреб, а своїх матеріальних можливостей і бажання. Так, при підготовці кампанії 1707 р., Петро І наказував Мазепі виправити до діючої армії виборних козаків і компанійців, “которые б имели добрые кони и ружье”, дорікаючи за минулорічні бої в яких у козаків “почитай что ни у кого сабли не видали, кроме пищалей и сайдаков” [3]. Стан озброєності істотно погіршився ще й внаслідок поразок гетьманського війська у битвах зі шведами, виснажливих чергувань на форпостах і походів на Каспій. Годі й говорити, що за таких умов будь-яка уніфікація козацького озброєння була справою бажаною, але надзвичайно складною. Скарб Гетьманщини після численних реформ Малоросійської колегії й хронічної децентралізованості фінансового господарства навряд чи зміг би подужати проведення подібних заходів. Окрім того, в Україні практично не існувало ані необхідної сировинної бази, ані мережі зброярських підприємств мануфактурного типу, котрі б працювали на державне замовлення й могли б виконувати великі замовлення. Розвиток численних рудень Лівобережжя, котрі були зобовязані віддавати частину продукованого ними заліза на потребу війська, як відомо, не призвів до їх перетворення на металургійні заводи

    Expert Opinion on Benefits of Long-Chain Omega-3 Fatty Acids (DHA and EPA) in Aging and Clinical Nutrition

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    Life expectancy is increasing and so is the prevalence of age-related non-communicable diseases (NCDs). Consequently, older people and patients present with multi-morbidities and more complex needs, putting significant pressure on healthcare systems. Effective nutrition interventions could be an important tool to address patient needs, improve clinical outcomes and reduce healthcare costs. Inflammation plays a central role in NCDs, so targeting it is relevant to disease prevention and treatment. The long-chain omega-3 polyunsaturated fatty acids (omega-3 LCPUFAs) docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are known to reduce inflammation and promote its resolution, suggesting a beneficial role in various therapeutic areas. An expert group reviewed the data on omega-3 LCPUFAs in specific patient populations and medical conditions. Evidence for benefits in cognitive health, age- and disease-related decline in muscle mass, cancer treatment, surgical patients and critical illness was identified. Use of DHA and EPA in some conditions is already included in some relevant guidelines. However, it is important to note that data on the effects of omega-3 LCPUFAs are still inconsistent in many areas (e.g., cognitive decline) due to a range of factors that vary amongst the trials performed to date; these factors include dose, timing and duration; baseline omega-3 LCPUFA status; and intake of other nutrients. Well-designed intervention studies are required to optimize the effects of DHA and EPA in specific patient populations and to develop more personalized strategies for their use.<br/

    Native like helices in a specially designed β peptide in the gas phase

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    In the natural peptides, helices are stabilized by hydrogen bonds that point backward along the sequence direction. Until now, there is only little evidence for the existence of analogous structures in oligomers of conformationally unrestricted β amino acids. We specifically designed the β peptide Ac-(β2hAla)6-LysH+ to form native like helical structures in the gas phase. The design follows the known properties of the peptide Ac-Ala6-LysH+ that forms a α helix in isolation. We perform ion-mobility mass-spectrometry and vibrational spectroscopy in the gas phase, combined with state-of-the-art density-functional theory simulations of these molecular systems in order to characterize their structure. We can show that the straightforward exchange of alanine residues for the homologous β amino acids generates a system that is generally capable of adopting native like helices with backward oriented H-bonds. By pushing the limits of theory and experiments, we show that one cannot assign a single preferred structure type due to the densely populated energy landscape and present an interpretation of the data that suggests an equilibrium of three helical structures

    Acute Disseminated Encephalomyelitis with Seizures and Myocarditis: A Fatal Triad.

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    Autoimmune pathology of acute disseminated encephalomyelitis (ADEM) is generally restricted to the brain. Our objective is to expand the phenotype of ADEM. A four-year-old girl was admitted to the pediatric emergency room of a university medical center five days after a common upper respiratory tract infection. Acute symptoms were fever, leg pain, and headaches. She developed meningeal signs, and her level of consciousness dropped rapidly. Epileptic seizure activity started, and she became comatose, requiring intubation and mechanical ventilation. Serial brain magnetic resonance imaging (MRI) illustrated the fulminant development of ADEM. Treatment escalation with high-dose corticosteroids, immunoglobulins, and plasma exchange did not lead to clinical improvement. On day ten, the patient developed treatment-refractory cardiogenic shock and passed away. The postmortem assessment confirmed ADEM and revealed acute lymphocytic myocarditis, likely explaining the acute cardiac failure. Human metapneumovirus and picornavirus were detected in the tracheal secrete by PCR. Data sources-medical chart of the patient. This case is consistent with evidence from experimental findings of an association of ADEM with myocarditis as a postinfectious systemic autoimmune response, with life-threatening involvement of the brain and heart

    Genetic and metabolic predictors of chemosensitivity in oligodendroglial neoplasms

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    The −1p/−19q genotype predicts chemosensitivity in oligodendroglial neoplasms, but some with intact 1p/19q also respond and not all with 1p/19q loss derive durable benefit from chemotherapy. We have evaluated the predictive and prognostic significance of pretherapy 201Tl and 18F-FDG SPECT and genotype in 38 primary and 10 recurrent oligodendroglial neoplasms following PCV chemotherapy. 1p/19q loss was seen in 8/15 OII, 6/15 OAII, 7/7 OIII, 3/11 OAIII and was associated with response (Fisher-Exact: P=0.000) and prolonged progression-free (log-rank: P=0.002) and overall survival (OS) (log-rank: P=0.0048). Response was unrelated to metabolism, with tumours with high or low metabolism showing response. Increased 18F-FDG or 201Tl uptake predicted shorter progression-free survival (PFS) in the series (log-rank: 201Tl P=0.0097, 18F-FDG P=0.0170) and in cases with or without the −1p/−19q genotype. Elevated metabolism was associated with shorter OS in cases with intact 1p/19q (log-rank: 18F-FDG P=0.0077; 201Tl P=0.0004) and shorter PFS in responders (log-rank: 18F-FDG P=0.005; 201Tl P=0.0132). 201Tl uptake and 1p/19q loss were independent predictors of survival in multivariate analysis. In this initial study, 201Tl and 18F-FDG uptake did not predict response to PCV, but may be associated with poor survival following therapy irrespective of genotype. This may be clinically useful warranting further study

    Identification of Quantitative Trait Loci for Flowering Time in a Field-Grown \u3cem\u3eLolium Perene x Lolium Multiflorum\u3c/em\u3e Mapping Population

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    Perennial ryegrass (L. perenne) and annual, or Italian, ryegrass (L. multiflorum) are considered to be separate species by the seed trade, and are used and bred for distinct purposes. However, the two species are cross-fertile. Seed producers rely on the different flowering times of the two species to produce pure seed. Flowering times can overlap, leading to genetic mixing. Contamination of perennial ryegrass seed lots with annual types is an expensive problem for grass seed producers in western Oregon, USA
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