Dialing in single-site reactivity of a supported calixarene-protected tetrairidium cluster catalyst.

A closed Ir4 carbonyl cluster, 1, comprising a tetrahedral metal frame and three sterically bulky tert-butyl-calix[4]arene(OPr)3(OCH2PPh2) (Ph = phenyl; Pr = propyl) ligands at the basal plane, was characterized with variable-temperature 13C NMR spectroscopy, which show the absence of scrambling of the CO ligands at temperatures up to 313 K. This demonstration of distinct sites for the CO ligands was found to extend to the reactivity and catalytic properties, as shown by selective decarbonylation in a reaction with trimethylamine N-oxide (TMAO) as an oxidant, which, reacting in the presence of ethylene, leads to the selective bonding of an ethyl ligand at the apical Ir site. These clusters were supported intact on porous silica and found to catalyze ethylene hydrogenation, and a comparison of the kinetics of the single-hydrogenation reaction and steady-state hydrogenation catalysis demonstrates a unique single-site catalyst-with each site having the same catalytic activity. Reaction orders in the catalytic ethylene hydrogenation reaction of approximately 1/2 and 0 for H2 and C2H4, respectively, nearly match those for conventional noble-metal catalysts. In contrast to oxidative decarbonylation, thermal desorption of CO from silica-supported cluster 1 occurred exclusively at the basal plane, giving rise to sites that do not react with ethylene and are catalytically inactive for ethylene hydrogenation. The evidence of distinctive sites on the cluster catalyst leads to a model that links to hydrogen-transfer catalysis on metals-involving some surface sites that bond to both hydrocarbon and hydrogen and are catalytically engaged (so-called "*" sites) and others, at the basal plane, which bond hydrogen and CO but not hydrocarbon and are reservoir sites (so-called "S" sites)

LC3 and STRAP regulate actin filament assembly by JMY during autophagosome formation.

During autophagy, actin filament networks move and remodel cellular membranes to form autophagosomes that enclose and metabolize cytoplasmic contents. Two actin regulators, WHAMM and JMY, participate in autophagosome formation, but the signals linking autophagy to actin assembly are poorly understood. We show that, in nonstarved cells, cytoplasmic JMY colocalizes with STRAP, a regulator of JMY's nuclear functions, on nonmotile vesicles with no associated actin networks. Upon starvation, JMY shifts to motile, LC3-containing membranes that move on actin comet tails. LC3 enhances JMY's de novo actin nucleation activity via a cryptic actin-binding sequence near JMY's N terminus, and STRAP inhibits JMY's ability to nucleate actin and activate the Arp2/3 complex. Cytoplasmic STRAP negatively regulates autophagy. Finally, we use purified proteins to reconstitute LC3- and JMY-dependent actin network formation on membranes and inhibition of network formation by STRAP. We conclude that LC3 and STRAP regulate JMY's actin assembly activities in trans during autophagy

Phase separation of signaling molecules promotes T cell receptor signal transduction

Author Posting. © The Author(s), 2016. This is the author's version of the work. It is posted here by permission of American Association for the Advancement of Science for personal use, not for redistribution. The definitive version was published in Science 352 (2016): 595-599, doi:10.1126/science.aad9964.Activation of various cell surface receptors triggers the reorganization of downstream signaling molecules into micron- or submicron-sized clusters. However, the functional consequences of such clustering has been unclear. We biochemically reconstituted a 12-component signaling pathway on model membranes, beginning with T cell receptor (TCR) activation and ending with actin assembly. When TCR phoshophorylation was triggered, downstream signaling proteins spontaneously separated into liquid-like clusters that promoted signaling outputs both in vitro and in human Jurkat T cells. Reconstituted clusters were enriched in kinases but excluded phosphatases, and enhanced actin filament assembly by recruiting and organizing actin regulators. These results demonstrate that protein phase separation can create a distinct physical and biochemical compartment that facilitates signaling.This work was supported by the HCIA program of HHMI, the NIH (R01-GM56322 to M.K.R.) and Welch Foundation (I–1544 to M.K.R.). X.S. was supported by CRI Irvington postdoctoral fellowship. J.A.D. was supported by NRSA F32 award 5-F32-DK101188. E.H. was supported as a fellow of the Leukemia and Lymphoma Society. J.O. was supported by funds from Tobacco-Related Disease Research Program of the University of California (19FT-0090).2016-10-0

Ionische Flüssigkeiten als Reaktionsmedium zur Darstellung neuartiger Festkörper

Im Rahmen der vorliegenden Arbeit wurde die Eignung Ionischer Flüssigkeiten (IFs) als Diffusionshilfsmittel in der Festkörpersynthese untersucht. Dabei wurde sie IF [NMeBu3][N(Tf)2] verwendet. Es gelang die Synthese von verschiedenen Verbindungen, u.a. [NMeBu3][Bi3I12] mit dem hier erstmals beschriebenen cis-[Bi3I12]3- Anion oder [P(o-tolyl)3Br]2[Cu2Br6](Br2), eine Verbindung, die molekulares Brom enthält. Es konnte gezeigt werden, dass die Verbindungen ohne Einsatz der IF nicht gebildet werden

Selective molecular recognition by nanoscale environments in a supported iridium cluster catalyst

The active sites of enzymes are contained within nanoscale environments that exhibit exquisite levels of specificity to particular molecules. The development of such nanoscale environments on synthetic surfaces, which would be capable of discriminating between molecules that would nominally bind in a similar way to the surface, could be of use in nanosensing, selective catalysis and gas separation. However, mimicking such subtle behaviour, even crudely, with a synthetic system remains a significant challenge. Here, we show that the reactive sites on the surface of a tetrairidium cluster can be controlled by using three calixarene–phosphine ligands to create a selective nanoscale environment at the metal surface. Each ligand is 1.4 nm in length and envelopes the cluster core in a manner that discriminates between the reactivities of the basal-plane and apical iridium atoms. CO ligands are initially present on the clusters and can be selectively removed from the basal-plane sites by thermal dissociation and from the apical sites by reactive decarbonylation with the bulky reactant trimethylamine-N-oxide. Both steps lead to the creation of metal sites that can bind CO molecules, but only the reactive decarbonylation step creates vacancies that are also able to bond to ethylene, and catalyse its hydrogenation

Effect of inter-row spacing and plant stand per hill on the yield of cowpea.

F.ield experiments were conducted to determine whether change in inter-row spacing and plant stand per blllaffeds grain yreld of the new improved cowpea lines. Yield was used to determined the best inter-row spacing and plant stand per bill for three new improved high yieldlng cowpea Vigna unguicuJata lines at Serere Agricultural and Animal P.roduction Research Institute (SAARI). Three inter-row spacing (30 x 30, 45 x 30, and 75 x 30 em) wen compared with the recommended spacing of 60 x 30 em, while one plant per bill compared with two plants per hill. The widest inter-row spacing (75 x 30 em) gave the lowest yield in the three lines. The same trend was observed in both fint and second rainy seasons. The highest yield Was obtained at a spacing of45 X 30 em. UM!er this spacing (45 X 30 em) one plant per hill r~ulted in bigber yields, while under 75 x 30 em, spacing two plants per hole gave the highest yield. Thus a spacing of 45 x 30 em appears to be the optimal for the three cowpea lines, with one pla.nt per hill instead of two plants. Line DVTB consistently out yielded DVTA and DVT. Lighter rains of second rains of 1997 favoured cowpea grain yield resulting in highest yields obtained in this season. The effect of seasons on the three lines was not consistent

Catalytic consequences of open and closed grafted Al(III)-calix[4]arene complexes for hydride and oxo transfer reactions

An approach for the control and understanding of supported molecular catalysts is demonstrated with the design and synthesis of open and closed variants of a grafted Lewis acid active site, consisting of Al(III)-calix[4]arene complexes on the surface of silica. The calixarene acts as a molecular template that enforces open and closed resting-state coordination geometries surrounding the metal active sites, due to its lower-rim substituents as well as site isolation by virtue of its steric bulk. These sites are characterized and used to elucidate mechanistic details and connectivity requirements for reactions involving hydride and oxo transfer. The consequence of controlling open versus closed configurations of the grafted Lewis acid site is demonstrated by the complete lack of observed activity of the closed site for Meerwein-Ponndorf-Verley (MPV) reduction; whereas, the open variant of this catalyst has an MPV reduction activity that is virtually identical to previously reported soluble molecular Al(III)-calix[4]arene catalysts. In contrast, for olefin epoxidation using tert-butyl-hydroperoxide as oxidant, the open and closed catalysts exhibit similar activity. This observation suggests that for olefin epoxidation catalysis using Lewis acids as catalyst and organic hydroperoxide as oxidant, covalent binding of the hydroperoxide is not required, and instead dative coordination to the Lewis acid center is sufficient for catalytic oxo transfer. This latter result is supported by density functional theory calculations of the transition state for olefin epoxidation catalysis, using molecular analogs of the open and closed catalysts

SSZ-70 borosilicate delamination without sonication: effect of framework topology on olefin epoxidation catalysis

We report a scalable delamination procedure for a SSZ-70-framework layered-zeolite precursor, which for the first time does not involve either sonication or long-chain surfactants. Our approach instead relies on the mild heating of layered zeolite precursor B-SSZ-70(P) in an aqueous solution containing Zn(NO_3)_2 and tetrabutylammonium fluoride. Powder X-ray diffraction data are consistent with a loss of long-range order along the z-direction, while ^(29)Si MAS NMR spectroscopy demonstrates preservation of the zeolite framework crystallinity during delamination. The resulting delaminated material, DZ-2, possesses 1.4-fold higher external surface area relative to the nondelaminated three-dimensional zeolite B-SSZ-70, based on N2 physisorption data at 77 K. DZ-2 was functionalized with cationic Ti heteroatoms to synthesize Ti-DZ-2 via exchange with framework B. Ti-DZ-2 contains isolated titanium centers in its crystalline framework, as shown by UV-Vis spectroscopy. The generality of the synthetic delamination approach and catalyst synthesis is demonstrated with the synthesis of delaminated material DZ-3, which is derived from layered zeolite precursor ERB-1(P) with MWW framework topology. Upon catalytic testing for the epoxidation of 1-octene with ethylbenzene hydroperoxide as oxidant, under harsh tail-end conditions that deactivate amorphous Ti-silica-based catalysts, Ti-DZ-2 exhibits the highest per-Ti-site activity, selectivity, and stability for 1-octene epoxidation of all catalysts investigated. This testing includes the prior benchmark delaminated zeolite catalyst in this area, Ti-UCB-4, which possesses similar external surface area to Ti-DZ-2 but requires sonication and long-chain surfactants for its synthesis. The synthesis of DZ-2 is the first example of an economical delamination of layered zeolite precursor SSZ-70(P) and opens up new doors to the development of delaminated zeolites as commercial catalysts

АЛГАРЫТМЫ ІДЭНТЫФІКАЦЫІ РЭПЛІК СА СЛОВАМІ АЎТАРА Ў ЭЛЕКТРОННЫХ ТЭКСТАХ НА БЕЛАРУСКАЙ МОВЕ

The main stages of algorithms for characters’ gender identification in Belarusian electronic texts are described. The algorithms are based on punctuation marking and gender indicators detection, such as past tense verbs and nouns with gender attributes. For indicators, special dictionaries are developed, thus making the algorithms more language-independent and allowing to create dictionaries for cognate languages. Testing showed the following results: the mean harmonic quantity for masculine gender detection makes up 92,2 %, and for feminine gender detection – 90,4%.Разглядаюцца асноўныя этапы стварэння аўтаматызаваных алгарытмаў для ідэнтыфікацыі рэплік зустаўкамі слоў аўтара, прапаноўваецца іх дапрацоўка ў мованезалежным напрамку. Прыводзяцца вынікі ацэнкі працы распрацаваных мадэляў на трэніровачным і тэставым тэкстах з дакладнасцю ў тэрмінах сярэдняй гарманічнай меры больш за 90 %