Monomolecular Skeletal Isomerization of 1-Butene over Selective Zeolite Catalysts

The mechanism of the 1-butene skeletal isomerization catalyzed by zeolites has remained elusive. We present direct evidence that even the initial isobutene formation over H-ferrierite, the best-known isomerization catalyst, is monomolecular in nature, whereas a bimolecular pathway is significant over the unselective H-ZSM-5. We also report that medium-pore high-silica H-HPM-1 outperforms H-ferrierite in selectively forming isobutene. This new catalyst displays a high activity and selectivity from the onset of the reaction, as well as an excellent resistance to deactivation, thanks to its anomalously weak acidity and low acid site density, together with an ability to effectively isolate reactant molecules from one another.X111612Ysciescopu

Characterising terrestrial influences on Antarctic air masses using Radon-222 measurements at King George Island

We report on one year of high-precision direct hourly radon observations at King Sejong Station (King George Island) beginning in February 2013. Findings are compared with historic and ongoing radon measurements from other Antarctic sites. Monthly median concentrations reduced from 72 mBq m−3 in late-summer to 44 mBq m−3 in late winter and early spring. Monthly 10th percentiles, ranging from 29 to 49 mBq m−3, were typical of oceanic baseline values. Diurnal cycles were rarely evident and local influences were minor, consistent with regional radon flux estimates one tenth of the global average for ice-free land. The predominant fetch region for terrestrially influenced air masses was South America (47–53° S), with minor influences also attributed to aged Australian air masses and local sources. Plume dilution factors of 2.8–4.0 were estimated for the most terrestrially influenced (South American) air masses, and a seasonal cycle in terrestrial influence on tropospheric air descending at the pole was identified and characterised. © Author(s) 201

High level expression of Acidothermus cellulolyticus β-1, 4-endoglucanase in transgenic rice enhances the hydrolysis of its straw by cultured cow gastric fluid

<p>Abstract</p> <p>Background</p> <p>Large-scale production of effective cellulose hydrolytic enzymes is the key to the bioconversion of agricultural residues to ethanol. The goal of this study was to develop a rice plant as a bioreactor for the large-scale production of cellulose hydrolytic enzymes via genetic transformation, and to simultaneously improve rice straw as an efficient biomass feedstock for conversion of cellulose to glucose.</p> <p>Results</p> <p>In this study, the cellulose hydrolytic enzyme β-1, 4-endoglucanase (<it>E1</it>) gene, from the thermophilic bacterium <it>Acidothermus cellulolyticus</it>, was overexpressed in rice through <it>Agrobacterium</it>-mediated transformation. The expression of the bacterial <it>E1 </it>gene in rice was driven by the constitutive Mac promoter, a hybrid promoter of Ti plasmid mannopine synthetase promoter and cauliflower mosaic virus 35S promoter enhancer, with the signal peptide of tobacco pathogenesis-related protein for targeting the E1 protein to the apoplastic compartment for storage. A total of 52 transgenic rice plants from six independent lines expressing the bacterial E1 enzyme were obtained that expressed the gene at high levels without severely impairing plant growth and development. However, some transgenic plants exhibited a shorter stature and flowered earlier than the wild type plants. The E1 specific activities in the leaves of the highest expressing transgenic rice lines were about 20-fold higher than those of various transgenic plants obtained in previous studies and the protein amounts accounted for up to 6.1% of the total leaf soluble protein. A zymogram and temperature-dependent activity analyses demonstrated the thermostability of the E1 enzyme and its substrate specificity against cellulose, and a simple heat treatment can be used to purify the protein. In addition, hydrolysis of transgenic rice straw with cultured cow gastric fluid for one hour at 39°C and another hour at 81°C yielded 43% more reducing sugars than wild type rice straw.</p> <p>Conclusion</p> <p>Taken together, these data suggest that transgenic rice can effectively serve as a bioreactor for the large-scale production of active, thermostable cellulose hydrolytic enzymes. As a feedstock, direct expression of large amount of cellulases in transgenic rice may also facilitate saccharification of cellulose in rice straw and significantly reduce the costs for hydrolytic enzymes.</p

Crystallization of a nonreplicating rotavirus vaccine candidate.

Nonreplicating rotavirus vaccine (NRRV) candidates are being developed with the aim of serving the needs of developing countries. A significant proportion of the cost of manufacturing such vaccines is the purification in multiple chromatography steps. Crystallization has the potential to reduce purification costs and provide new product storage modality, improved operational flexibility, and reduced facility footprints. This communication describes a systematic approach for the design of the crystallization of an NRRV candidate, VP8 subunit proteins fused to the P2 epitope of tetanus toxin, using first-principles models and preliminary experimental data. The first-principles models are applied to literature data to obtain feasible crystallization conditions and lower bounds for nucleation and growth rates. Crystallization is then performed in a hanging-drop vapor diffusion system, resulting in the nucleation and growth of NRRV crystals. The crystals obtained in a scaled-up evaporative crystallization contain proteins truncated in the P2 region, but have no significant differences with the original samples in terms of antibody binding and overall conformational stability. These results demonstrate the promise of evaporative crystallization of the NRRV

KACC: An identification and characterization for microbial resources in Korea

Korean Agricultural Culture Collection (KACC) is an authorized organizer and the official depository for microbial resources in Korea. The KACC has developed a web-based database system to provide integrated information about microbial resources. It includes not only simple text information onindividual microbe but also morphological images and DNA sequence data for the strain. The KACC now provides the characterization information which maintains 7,433 cultures of microorganisms including 2,687 strains of bacteria, 3535 fungi, 476 actinomycetes, 64 yeasts, and 671 others (mushrooms, gene clones, etc)

New taxa of Neosartorya and Aspergillus in Aspergillus section Fumigati

Three new species of Neosartorya and one new Aspergillus of section Fumigati are proposed using a polyphasic approach based on morphology, extrolite production and partial β-tubulin, calmodulin, and actin gene sequences. The phylogenetic analyses using the three genes clearly show that the taxa grouped separately from the known species and confirmed the phenotypic differences. Neosartorya denticulata is characterized by its unique denticulate ascospores with a prominent equatorial furrow; N. assulata by well developed flaps on the convex surface of the ascospores which in addition have two distinct equatorial crests and N. galapagensis by a funiculose colony morphology, short and narrow conidiophores and ascospores with two wide equatorial crests with a microtuberculate convex surface. Aspergillus turcosus can be distinguished by velvety, gray turquoise colonies and short, loosely columnar conidial heads. The four new taxa also have unique extrolite profiles, which contain the mycotoxins gliotoxin and viriditoxin in N. denticulate; apolar compounds provisionally named NEPS in N. assulata and gregatins in N. galapagensis. A. turcosus produced kotanins. N.denticulata sp. nov., N. assulata sp. nov., N. galapagensis sp. nov., and A. turcosus sp. nov. are described and illustrated

Charge density mismatch synthesis of MEI- and BPH-type zeolites in the TEA+–TMA+–Li+–Sr2+ mixed-structure-directing agent system

Nanocrystalline MEI- and BPH-type zeolites, denoted as PST-11 and PST-12, respectively, have been synthesized using both tetraethylammonium and tetramethylammonium ions, the two simplest alkyl-ammonium species, in the presence of Li+ and Sr2+. PST-12 formation is the first example of a combination of forced and multiple cooperative structure-directions in the charge density mismatch synthesis of zeolites.open1166sciescopu

Chromatin establishes an immature version of neuronal protocadherin selection during the naive-to-primed conversion of pluripotent stem cells.

In the mammalian genome, the clustered protocadherin (cPCDH) locus provides a paradigm for stochastic gene expression with the potential to generate a unique cPCDH combination in every neuron. Here we report a chromatin-based mechanism that emerges during the transition from the naive to the primed states of cell pluripotency and reduces, by orders of magnitude, the combinatorial potential in the human cPCDH locus. This mechanism selectively increases the frequency of stochastic selection of a small subset of cPCDH genes after neuronal differentiation in monolayers, 10-month-old cortical organoids and engrafted cells in the spinal cords of rats. Signs of these frequent selections can be observed in the brain throughout fetal development and disappear after birth, except in conditions of delayed maturation such as Down's syndrome. We therefore propose that a pattern of limited cPCDH-gene expression diversity is maintained while human neurons still retain fetal-like levels of maturation

Microstructural Imaging in Temporal Lobe Epilepsy: Diffusion Imaging Changes Relate to Reduced Neurite Density

Purpose: Previous imaging studies in patients with refractory temporal lobe epilepsy (TLE) have examined the spatial distribution of changes in imaging parameters such as diffusion tensor imaging (DTI) metrics and cortical thickness. Multi-compartment models offer greater specificity with parameters more directly related to known changes in TLE such as altered neuronal density and myelination. We studied the spatial distribution of conventional and novel metrics including neurite density derived from NODDI (Neurite Orientation Dispersion and Density Imaging) and myelin water fraction (MWF) derived from mcDESPOT (Multi-Compartment Driven Equilibrium Single Pulse Observation of T1/T2)] to infer the underlying neurobiology of changes in conventional metrics. / Methods: 20 patients with TLE and 20 matched controls underwent magnetic resonance imaging including a volumetric T1-weighted sequence, multi-shell diffusion from which DTI and NODDI metrics were derived and a protocol suitable for mcDESPOT fitting. Models of the grey matter-white matter and grey matter-CSF surfaces were automatically generated from the T1-weighted MRI. Conventional diffusion and novel metrics of neurite density and MWF were sampled from intracortical grey matter and subcortical white matter surfaces and cortical thickness was measured. / Results: In intracortical grey matter, diffusivity was increased in the ipsilateral temporal and frontopolar cortices with more restricted areas of reduced neurite density. Diffusivity increases were largely related to reductions in neurite density, and to a lesser extent CSF partial volume effects, but not MWF. In subcortical white matter, widespread bilateral reductions in fractional anisotropy and increases in radial diffusivity were seen. These were primarily related to reduced neurite density, with an additional relationship to reduced MWF in the temporal pole and anterolateral temporal neocortex. Changes were greater with increasing epilepsy duration. Bilaterally reduced cortical thickness in the mesial temporal lobe and centroparietal cortices was unrelated to neurite density and MWF. / Conclusions: Diffusivity changes in grey and white matter are primarily related to reduced neurite density with an additional relationship to reduced MWF in the temporal pole. Neurite density may represent a more sensitive and specific biomarker of progressive neuronal damage in refractory TLE that deserves further study

Linear confinement without dilaton in bottom-up holography for walking technicolour

In PRD78(2008)055005 [arXiv:0805.1503 [hep-ph]] and PRD79(2009)075004 [arXiv:0809.1324 [hep-ph]], we constructed a holographic description of walking technicolour theories using both a hard- and a soft-wall model. Here, we show that the dilaton field becomes phenomenologically irrelevant for the spectrum of spin-one resonances once a term is included in the Lagrangian that mixes the Goldstone bosons and the longitudinal components of the axial vector mesons. We show how this mixing affects our previous results and we make predictions about how this description of technicolour can be tested.Comment: 7 pages, no figure