3,308 research outputs found
A covalent organic/inorganic hybrid proton exchange polymeric membrane: synthesis and characterization
Commercial polyetheretherketone (Victrex PEEK) was sulfonated up to 90% degree of sulfonation (DS), then reacted with SiCl4 to obtain
a hybrid polymer. The product was characterized by 29-Si NMR and ATR/FTIR spectroscopies demonstrating the formation of covalent bonds
between the organic and inorganic components. No dispersed inorganic silicon was present in the product as evidenced by the lack of any
resonance at 100 ppm. Despite the high DS the physicochemical properties of the hybrid were suitable for the preparation of
membranes exhibiting high and stable conductivity values (10K2 S/cm), hence suitable for application as ion exchange membrane
A Perspective on Development Flight Instrumentation and Flight Test Analysis Plans for Ares I-X
NASA. s Constellation Program will take a significant step toward completion of the Ares I crew launch vehicle with the flight test of Ares I-X and completion of the Ares I-X post-flight evaluation. The Ares I-X flight test vehicle is an ascent development flight test that will acquire flight data early enough to impact the design and development of the Ares I. As the primary customer for flight data from the Ares I-X mission, Ares I has been the major driver in the definition of the Development Flight Instrumentation (DFI). This paper focuses on the DFI development process and the plans for post-flight evaluation of the resulting data to impact the Ares I design. Efforts for determining the DFI for Ares I-X began in the fall of 2005, and significant effort to refine and implement the Ares I-X DFI has been expended since that time. This paper will present a perspective in the development and implementation of the DFI. Emphasis will be placed on the process by which the list was established and changes were made to that list due to imposed constraints. The paper will also discuss the plans for the analysis of the DFI data following the flight and a summary of flight evaluation tasks to be performed in support of tools and models validation for design and development
Analysis of the human Y-chromosome haplogroup Q characterizes ancient population movements in Eurasia and the Americas
Background: Recent genome studies of modern and ancient samples have proposed that Native Americans derive from a subset of the Eurasian gene pool carried to America by an ancestral Beringian population, from which two well-differentiated components originated and subsequently mixed in different proportion during their spread in the Americas. To assess the timing, places of origin and extent of admixture between these components, we performed an analysis of the Y-chromosome haplogroup Q, which is the only Pan-American haplogroup and accounts for virtually all Native American Y chromosomes in Mesoamerica and South America. Results: Our analyses of 1.5 Mb of 152 Y chromosomes, 34 re-sequenced in this work, support a "coastal and inland routes scenario" for the first entrance of modern humans in North America. We show a major phase of male population growth in the Americas after 15 thousand years ago (kya), followed by a period of constant population size from 8 to 3 kya, after which a secondary sign of growth was registered. The estimated dates of the first expansion in Mesoamerica and the Isthmo-Colombian Area, mainly revealed by haplogroup Q-Z780, suggest an entrance in South America prior to 15 kya. During the global constant population size phase, local South American hints of growth were registered by different Q-M848 sub-clades. These expansion events, which started during the Holocene with the improvement of climatic conditions, can be ascribed to multiple cultural changes rather than a steady population growth and a single cohesive culture diffusion as it occurred in Europe. Conclusions: We established and dated a detailed haplogroup Q phylogeny that provides new insights into the geographic distribution of its Eurasian and American branches in modern and ancient samples
Ion uptake and YSL1 gene identification in tomato
Tomato breeder are using wild tomato relatives, even non-cross compatibles ones, in order to
obtain cultivars with highly commercial values bearing new traits. However, the introgression of a
wild genome into the cultivated one produces a new gene combinations that may lead to the
expression of undeliverable traits, perhaps not so easy to recognise; even more, phenotypic
variations may escape during the selection procedure when minor genes or non-abnormal
phenotypes are involved. In the frame of the “GenoPom” project funded by MIUR, we have
focused our interest on the alteration of heavy metals uptake from the soil and their loading into
edible organs in commercial lines coming from Solanum interspecific crosses. Our final aim is to
put together data coming from ion homeostasis and gene expression analyses, thus obtaining a
ionomic map of tomato. To pursue our goal, we have started to study the cv M82 of Solanum
lycopersicon, the wild relative Solanum pennelli and their introgression lines IL. Regarding the
experiments on ion homeostasis, S. lycopersicon M82 and the introgression line IL 6-4-2 were
grown in hydroponics under controlled environmental conditions. Twenty day-old plants were left
to grow for 10 days in the presence of non-toxic concentration of Cd (10 mM), Pb (3 mM), Zn (100
mM) given separately or combined. Control and treated roots and leaves were then harvested and
stored at -80°C for ionic and gene expression analyses. Ions analysis of Solanum lycopersicon M82
and IL 6-4-2 showed that traits correlated to ionic homeostasis is significantly modified in response
to all metals and to the genotype. The analysis of ions data, obtained by ICP-MS, give a pictures of
the different responses performed both to different stress and to combined stress, probably
correlated to the up-regulation and/or down regulation of metal uptake proteins. Performed
experiments demonstrate that the introgression of the wild genome into the cultivated one produces
a new phenotype, perhaps due to the expression of traits linked to uptake, translocation and
accumulation of useful and/or toxic metal into plant tissues and organs.
Regarding the functional genomics approach for gaining insight into gene networks involved
in mineral-ion accumulation in tomato plants, in literature has been reported that at least 25 major
family genes are involved for metal homeostasis in plants. Among them, the genes ysl, hma, mtp,
znt, zrt have been already studied at least in the plant species Arabidopsis thaliana, A. halleri and
Thlaspi caerulescens. So far, no such genes have been reported to be cloned in Solanum species.
We have focused our study on the genes YSL1, ZNT1 and MTP1 responsible for uptake,
translocation and accumulation of metal such as zinc, cadmium, and iron into plant compartment.
For all of them, consensous sequences from nucleotide multialignment have been obtained. Then,
each of those were blasted in a Solanum EST collection databank and an assembled UniGene
sequence was obtained.. Finally, we have designed primers and performed PCR analysis on S.
lycopersicon and S. pennelli genomic DNA. So far, we have cloned a putative ysl1 sequence from
tomato, that has shown that a very high percentage of identity (92%) with whole ysl1 gene of
Nicotiana tabacum; the in silico translated sequence of this sequence has shown a 89% of identity
with the same tobacco protein
On the tree-transformation power of XSLT
XSLT is a standard rule-based programming language for expressing
transformations of XML data. The language is currently in transition from
version 1.0 to 2.0. In order to understand the computational consequences of
this transition, we restrict XSLT to its pure tree-transformation capabilities.
Under this focus, we observe that XSLT~1.0 was not yet a computationally
complete tree-transformation language: every 1.0 program can be implemented in
exponential time. A crucial new feature of version~2.0, however, which allows
nodesets over temporary trees, yields completeness. We provide a formal
operational semantics for XSLT programs, and establish confluence for this
semantics
Effects of milk, pasteurized milk, and milk replacer on health and productivity of dairy calves
Dairy Research, 2014 is known as Dairy Day, 2014Our objectives were to determine the health and blood parameters before, during, and
after weaning of 114 Holstein heifers fed either accelerated milk replacer (MR; 28%
CP, 18% fat) or non-saleable milk (3.59 ± 0.28% true protein; 4.12 ± 0.37% fat) that
was either pasteurized (PM) or raw (RM; refrigerated and fed <24 h after collection).
Calves were randomly assigned to feeding treatments at birth. Colostrum (1 L) was fed
less than 14 hours after birth (MR and PM = pasteurized colostrum; RM = raw colostrum).
All calves were bottle-fed 1.8 ± 0.20 L, 3 times daily; all calves were provided
fresh water and grain ad libitum throughout the experiment. Calves began step-down
weaning at age 5 weeks and completed weaning at age 6 weeks. Blood samples were collected
at ages 3, 5, and 7 weeks and were analyzed for complete blood counts (CBC) using
a Procyte Idexx Analyzer (IDEXX Laboratories, Inc., Westbrook, ME). Fecal scores
were observed twice daily, on a 1 to 3 scale (FS1 = normal, FS2 = loose, FS3 = scours).
Results showed that MR-fed calves had more (P < 0.01) observations (%obs) with
FS > 2 than the PM- and RM-fed calves (2.3 vs. 1.6 and 1.7 ± 0.2 %obs, respectively).
In addition, there were no differences in body weight or shoulder or hip height between
treatments, but a treatment × week interaction (P = 0.05) occurred for grain consumed,
with a noticeably higher increase between 6 and 7 weeks of age for MR calves.
When CBC was considered, there were no differences in blood cell types, but MR-fed
calves had greater mean corpuscular volume (MCV) than the other calves (P < 0.01),
leading to higher resistance for iron deficiency anemia. In conclusion, these findings
suggest that calf performance and feed intake are not affected by the administration of
raw milk, pasteurized milk, or milk replacer. Moreover, CBC health parameters showed
no significant changes due to administration of the different types of milk sources
Compactness in Groups of Group-Valued Mappings
We introduce the concepts of extended equimeasurability and extended uniform quasiboundedness in groups of group-valued mappings endowed with a topology that generalizes the topology of convergence in measure. Quantitative characteristics modeled on these concepts allow us to estimate the Hausdorff measure of noncompactness in such a contest. Our results extend and encompass some generalizations of Frechet-Smulian and Ascoli-Arzela compactness criteria found in the literature
Rearrangement and Convergence in Spaces of Measurable Functions
We prove that the convergence of a sequence of functions in the space of measurable functions, with respect to the topology of convergence in measure, implies the convergence -almost everywhere ( denotes the Lebesgue measure) of the sequence of rearrangements. We obtain nonexpansivity of rearrangement on the space , and also on Orlicz spaces with respect to a finitely additive extended real-valued set function. In the space and in the space , of finite elements of an Orlicz space of a -additive set function, we introduce some parameters which estimate the Hausdorff measure of noncompactness. We obtain some relations involving these parameters when passing from a bounded set of , or , to the set of rearrangements
Regular measures of noncompactness and Ascoli-Arzela type compactness criteria in spaces of vector-valued functions
In this paper we estimate the Kuratowski and the Hausdorff measures of noncompactness of bounded subsets of spaces of vector-valued bounded functions and of vector-valued bounded differentiable functions. To this end, we use a quantitative characteristic modeled on a new equicontinuity-type concept and classical quantitative characteristics related to pointwise relative compactness. We obtain new regular measures of noncompactness in the spaces taken into consideration. The established inequalities reduce to precise formulas in some classes of subsets. We derive Ascoli-Arzela type compactness criteria
Sphingosine 1-phosphate modulates antigen capture by murine langerhans cells via the S1P2 receptor subtype
Dendritic cells (DCs) play a pivotal role in the development of cutaneous contact hypersensitivity (CHS) and atopic dermatitis as they capture and process antigen and present it to T lymphocytes in the lymphoid organs. Recently, it has been indicated that a topical application of the sphingolipid sphingosine 1-phosphate (S1P) prevents the inflammatory response in CHS, but the molecular mechanism is not fully elucidated. Here we indicate that treatment of mice with S1P is connected with an impaired antigen uptake by Langerhans cells (LCs), the initial step of CHS. Most of the known actions of S1P are mediated by a family of five specific G protein-coupled receptors. Our results indicate that S1P inhibits macropinocytosis of the murine LC line XS52 via S1P2 receptor stimulation followed by a reduced phosphatidylinositol 3-kinase (PI3K) activity. As down-regulation of S1P2 not only diminished S1P-mediated action but also enhanced the basal activity of LCs on antigen capture, an autocrine action of S1P has been assumed. Actually, S1P is continuously produced by LCs and secreted via the ATP binding cassette transporter ABCC1 to the extracellular environment. Consequently, inhibition of ABCC1, which decreased extracellular S1P levels, markedly increased the antigen uptake by LCs. Moreover, stimulation of sphingosine kinase activity, the crucial enzyme for S1P formation, is connected not only with enhanced S1P levels but also with diminished antigen capture. These results indicate that S1P is essential in LC homeostasis and influences skin immunity. This is of importance as previous reports suggested an alteration of S1P levels in atopic skin lesions
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