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https://www.readbyqxmd.com/read/29662211/synthesis-structure-and-reaction-chemistry-of-a-nucleophilic-aluminyl-anion
#1
Jamie Hicks, Petra Vasko, Jose M Goicoechea, Simon Aldridge
The reactivity of aluminium compounds is dominated by their electron deficiency and consequent electrophilicity; these compounds are archetypal Lewis acids (electron-pair acceptors). The main industrial roles of aluminium, and classical methods of synthesizing aluminium-element bonds (for example, hydroalumination and metathesis), draw on the electron deficiency of species of the type AlR3 and AlCl3 1,2 . Whereas aluminates, [AlR4 ]- , are well known, the idea of reversing polarity and using an aluminium reagent as the nucleophilic partner in bond-forming substitution reactions is unprecedented, owing to the fact that low-valent aluminium anions analogous to nitrogen-, carbon- and boron-centred reagents of the types [NX2 ]- , [CX3 ]- and [BX2 ]- are unknown3-5 ...
April 16, 2018: Nature
https://www.readbyqxmd.com/read/29660071/assessing-effects-of-yeast-cell-wall-supplementation-on-threonine-requirements-in-broilers-as-measured-by-performance-and-intestinal-morphology
#2
Raghad A Abdaljaleel, Morouj Al-Ajeeli, Yasser Jameel, Mohammed M Hashim, Christopher A Bailey
The objective of this study was to evaluate whether or not the use of a prebiotic yeast cell wall (YCW) affects threonine requirements in starter broilers. Two hundred and forty 1-d-old Ross 308 broiler chickens were distributed among 2 Petersime battery brooder units (48 pens; 5 birds per pen). Different threonine to lysine ratios (0.60, 0.65, and 0.70 to 1.0) with 1.22% available lysine with and without YCW at 250 ppm was fed to the chickens in order to evaluate performance and intestinal morphology over a 21-d trial...
April 11, 2018: Poultry Science
https://www.readbyqxmd.com/read/29587236/ciprofloxacin-metal-complexes-stability-and-toxicity-tests-in-the-presence-of-humic-substances
#3
Agnieszka Cuprys, Rama Pulicharla, Joanna Lecka, Satinder Kaur Brar, Patrick Drogui, R Y Surampalli
The co-contamination of ciprofloxacin (CIP) with metal ions results in alteration of CIP mobility, antimicrobial activity and distribution/development of the antibiotic-resistance genes. In this study, the stability of five CIP-Me complexes [Me = Al(III), Co(II), Cu(II), Fe(III), Mg] was investigated in the presence of humic substances (HS) at two temperatures 18 ± 2 °C and 4 ± 1 °C for seven days period. The most stable complexes were CIP-Al, CIP-Cu, and CIP-Co with the stability constants (K) at 18 °C 35...
March 20, 2018: Chemosphere
https://www.readbyqxmd.com/read/29568477/md-simulations-and-qm-mm-calculations-show-that-single-site-mutations-of-cytochrome-p450-bm3-alter-the-active-site-s-complexity-and-the-chemoselectivity-of-oxidation-without-changing-the-active-species
#4
Kshatresh Dutta Dubey, Binju Wang, Manu Vajpai, Sason Shaik
It is a long-standing mechanistic consensus that the mutation of the proton-shuttle mediator Threonine (T) in Cytochrome P450 enzymes severs the water channel and thereby quenches the formation of the active species: the high-valent iron(iv)-oxo porphyrin π-cation radical species, compound I (Cpd I). Using MD simulations and hybrid QM/MM calculations of P450BM3 we demonstrate that this is not the case. Thus, while the original water channel is disrupted in the T268A mutant of the enzyme, a new channel is formed that generates Cpd I...
August 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/29553256/synthesis-and-characterization-of-neutral-ligand-%C3%AE-diimine-complexes-of-aluminum-with-tunable-redox-energetics
#5
Henry H Wilson, Connor A Koellner, Zain M Hannan, Caroline B Endy, Mark W Bezpalko, Nicholas A Piro, W Scott Kassel, Matthew D Sonntag, Christopher R Graves
The synthesis and full characterization of a series of neutral ligand α-diimine complexes of aluminum are reported. The compounds [Al(LAr )2 Cl2 )][AlCl4 ] [LAr = N, N'-bis(4-R-C6 H4 )-2,3-dimethyl-1,4-diazabutadiene] are structurally analogous, as determined by multinuclear NMR spectroscopy and solid-state X-ray diffraction, across a range of electron-donating [R = Me (2),t Bu (3), OMe (4), and NMe2 (5)] and electron-withdrawing [R = Cl (6), CF3 (7), and NO2 (8)] substituents in the aryl side arm of the ligand...
March 19, 2018: Inorganic Chemistry
https://www.readbyqxmd.com/read/29485174/co-oxidative-coupling-to-dimethyl-oxalate-over-pd-me-me-cu-al-catalysts-a-combined-dft-and-kinetic-study
#6
Bingying Han, Xue Feng, Lixia Ling, Maohong Fan, Ping Liu, Riguang Zhang, Baojun Wang
CO oxidative coupling to dimethyl oxalate (DMO) on Pd(111), Pd-Cu(111) and Pd-Al(111) surfaces was systematically investigated by means of density functional theory (DFT) together with periodic slab models and micro-kinetic modeling. The binding energy results show that Cu and Al can be fine substrates to stably support Pd. The favorable pathway for DMO synthesis on these catalysts starts from the formation of two COOCH3 intermediates, followed by the coupling to each other, and the catalytic activity follows the trend of Pd-Al(111) > Pd(111) > Pd-Cu(111)...
February 27, 2018: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29462959/controlled-and-efficient-polymerization-of-conjugated-polar-alkenes-by-lewis-pairs-based-on-sterically-hindered-aryloxide-substituted-alkylaluminumitle
#7
Xiaojun Wang, Yixin Zhang, Miao Hong
Reported herein is the development of an effective strategy for controlled and efficient Lewis pair polymerization of conjugated polar alkenes, including methyl methacrylate (MMA), n -butyl methacrylate (n BuMA), and γ-methyl-α-methylene-γ-butyrolactone (γMMBL), by the utilization of sterically encumbered Al(BHT)₂Me (BHT: 2,6-di- tert -butyl-4-methylphenol) as a Lewis acid that shuts down intramolecular backbiting termination. In combination with a selected N -heterocyclic carbene (NHC) as a Lewis base, the polymerization of MMA exhibited activity up to 3000 h-1 TOF and an acceptable initiation efficiency of 60...
February 17, 2018: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/29454232/effects-of-mine-tailing-and-mixed-contamination-on-metals-trace-elements-accumulation-and-histopathology-of-the-chub-squalius-cephalus-tissues-evidence-from-three-differently-contaminated-sites-in-serbia
#8
Božidar Rašković, Vesna Poleksić, Stefan Skorić, Katarina Jovičić, Slađana Spasić, Aleksandar Hegediš, Nebojša Vasić, Mirjana Lenhardt
Chub (Squalius cephalus) specimens were collected in Korenita River seven months after spillover from the waste water of antimony mine tailing pond and compared with chub living in Kruščica reservoir (intended for water supply) and Međuvršje reservoir (influenced by intense emission of industrial, urban and rural wastewater). Concentrations of 15 elements (Al, As, B, Ba, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Si, Sr, Zn) were determined in muscle, liver and gills of chub by inductively coupled plasma optical spectrometry (ICP-OES) and histopathological alterations in liver and gills were assessed...
February 14, 2018: Ecotoxicology and Environmental Safety
https://www.readbyqxmd.com/read/29452227/age-and-experience-dependent-changes-in-egr-1-expression-during-the-ontogeny-of-the-context-preexposure-facilitation-effect-cpfe
#9
P A Robinson-Drummer, T Chakraborty, N A Heroux, J B Rosen, M E Stanton
The context preexposure facilitation effect (CPFE) is a variant of contextual fear conditioning in which acquisition of the contextual representation and association of the retrieved contextual memory with an immediate foots-hock are separated by 24hrs. During the CPFE, learning- related expression patterns of the early growth response -1 gene (Egr-1) vary based on training phase and brain sub-region in adult and adolescent rats (Asok, Schreiber, Jablonski, Rosen, & Stanton, 2013; Shreiber et al., 2014; Chakraborty, Asok, Stanton, & Rosen, 2016)...
February 13, 2018: Neurobiology of Learning and Memory
https://www.readbyqxmd.com/read/29450815/factors-affecting-reproductive-performance-in-dromedary-camel-herds-in-saudi-arabia
#10
Ahmed Ali, Derar Derar, Abdulhadi Alsharari, Assaf Alsharari, Rashid Khalil, Tariq I Almundarij, Yaser Alboti, Fahd Al-Sobayil
A survey of 7122 dromedary camels in 115 herds in Saudi Arabia was used to estimate the effects of herd size (HZ; < 25 vs. 25-49 vs. 50-100 vs. > 100 camels), herder/camels ratio (H/C; 1:< 25 vs. 1:25-50 vs. 1:> 50), manager experience (ME; < 5 vs. 5-10 vs. > 10 years), male/females ratio (M/F), housing system (HS; free vs. closed vs. mixed), length of the breeding season (winter vs. winter and spring vs. fall, winter and spring), age at first mating (3 vs. > 3 years), and time of mating after parturition (≤ 3 vs...
February 15, 2018: Tropical Animal Health and Production
https://www.readbyqxmd.com/read/29448798/effect-of-alkaline-metal-cations-on-the-ionic-structure-of-cryolite-melts-ab-initio-npt-md-study
#11
Tomáš Bučko, František Šimko
Ab initio molecular dynamics simulations in an NpT ensemble have been performed to study the role of alkaline metal cations (Me = Li, Na, K, Rb) on the structure and vibrational properties of melts of Me-cryolites (Me 3 AlF 6 ) at T = 1300 K. In all melts examined in this work, the species AlF 5 2- has been found to be formed at the highest abundance [from 58% (Li) to 70% (Na)] among the Al-containing anionic clusters. The concentration of clusters AlF 4 - increases with the size of cations while that of anions AlF 6 3- follows the opposite trend and it becomes negligible in the melts of the K- and Rb-cryolites...
February 14, 2018: Journal of Chemical Physics
https://www.readbyqxmd.com/read/29423492/dft-methods-applied-to-answer-the-question-how-accurate-is-the-ligand-acidity-constant-method-for-estimating-the-pka-of-transition-metal-hydride-complexes-mhxl4-when-x-is-varied
#12
Jan P Unsleber, Johannes Neugebauer, Robert H Morris
Density functional theory (DFT) is used to calculate the relative free energies of deprotonation of the isomers of iron-group hydride complexes MHXL4 where M = Fe, Ru, Os, L4 = (CO)4 or (PMe2CH2CH2PMe2)2 for a wide range of anionic ligands X. The free energies of the most stable isomers are used to calculate relative pKa values where Ka refers to the acid dissociation constant for the equilibrium MHXL4 → [MXL4]- + H+. These are used to test the proposal that the pKa for a given metal complex in THF can be simply calculated by adding the contributions to the total pKa value from each ligand L; these are called ligand acidity constants (LAC) AL used in the LAC equation [R...
February 9, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/29399829/hydride-triel-bonds
#13
Mirosław Jabłoński
In this article, we present the results of our comprehensive studies of 72 dimers of the R3XXH⋯YR3Y type (X = Si, Ge; Y = B, Al, Ga; RX  = H, Cl, Me; RY  = H, F, Cl, Me) and featuring hydride-triel bonds (i.e., charge-inverted hydrogen bonds). Influence of X and Y atoms as well as RX and RY substituents on various properties of these dimers is investigated in detail. In particular the strength of the H⋯Y hydride-triel bonds is paid a close attention and it is shown that hydride-triel bonds can be strong enough to considerably determine structure and properties of molecular systems...
February 5, 2018: Journal of Computational Chemistry
https://www.readbyqxmd.com/read/29351837/try-me-promiscuous-inhibitors-still-allow-for-selective-targeted-protein-degradation
#14
Matthias P Müller, Daniel Rauh
In this issue of Cell Chemical Biology, Bondeson et al. (2018), Burslem et al. (2018), and Huang et al. (2018) systematically characterize proteolysis-targeting chimeras (PROTACs) regarding their specificity and general advantages of targeted proteolysis of cellular proteins and provide interesting insights into possible future developments.
January 18, 2018: Cell Chemical Biology
https://www.readbyqxmd.com/read/29351260/fatty-acid-based-microemulsions-to-combat-ophthalmia-neonatorum-caused-by-neisseria-gonorrhoeae-and-staphylococcus-aureus
#15
Ummara Butt, Amr ElShaer, Lori A S Snyder, Ali A Al-Kinani, Adam Le Gresley, Raid G Alany
The bacterial species Neisseria gonorrhoeae ( N. gonorrhoeae ) and Staphylococcus aureus ( S. aureus ) are amongst the main microorganisms that cause ophthalmia neonatorum. The current treatment involves the use of various antibiotics such as ciprofloxacin, cephalosporin, ceftriaxone and cefotaxime. However, this treatment strategy is becoming more ineffective due to the antibiotic resistance in N. gonorrhoeae. The current study explores the potential use of fatty acid based microemulsions (ME) to prevent N...
January 19, 2018: Nanomaterials
https://www.readbyqxmd.com/read/29332246/an-historical-perspective-of-the-discovery-of-titin-filaments-part-2
#16
REVIEW
Cristobal G Dos Remedios
In 2017, a Special Issue of Biophysical Reviews was devoted to "Titin and Its Binding Partners. The issue contained a review: "An historical perspective of the discovery of titin filaments" by dos Remedios and Gilmour that was intended to be a history of the discovery of the giant protein titin, previously named connectin. The review took readers back to the earliest discovery of the so-called third filament component of skeletal and cardiac muscle sarcomeres and ended in 1969. Recently, my colleague Shin'ichi Ishiwata gently reminded me of two papers published in 1990 and 1993 that were unwittingly omitted from the original historical perspective...
January 13, 2018: Biophysical Reviews
https://www.readbyqxmd.com/read/29314851/organometallic-zirconium-compounds-in-an-oxygen-rich-coordination-environment-synthesis-and-structural-characterization-of-tris-oxoimidazolyl-hydroboratozirconium-compounds
#17
Ahmed Al-Harbi, Matthew J Hammond, Gerard Parkin
A series of tris(oxoimidazolyl)hydroborato ligands, which serve as L2 X [O3 ] donors, have been employed to obtain organometallic zirconium compounds in an uncommon oxygen-rich coordination environment. For example, Cp[ToMeBenz ]ZrCl2 has been synthesized via the reaction of [ToMeBenz ]Na with CpZrCl3 and bears a structural resemblance to the bent metallocene dichloride derivative Cp2 ZrCl2 . In addition, the half-sandwich counterparts [ToMeBenz ]ZrCl3 and [ToBut ]ZrCl3 have been obtained by metathesis of ZrCl4 with [ToMeBenz ]Na and [ToBut ]Na, respectively...
February 5, 2018: Inorganic Chemistry
https://www.readbyqxmd.com/read/29237725/abin-1-negatively-regulates-%C3%AE-opioid-receptor-function
#18
Peilan Zhou, Jiebing Jiang, Hui Yan, Yulei Li, Junru Zhao, Xiao Wang, Ruibin Su, Zehui Gong
The μ -opioid receptor (MOR) is a Gi/o protein-coupled receptor that mediates analgesic, euphoric, and reward effects. Using a bacterial two-hybrid screen, we reported that the carboxyl tail of the rat MOR associates with A20-binding inhibitor of nuclear factor κ B (ABIN-1). This interaction was confirmed by direct protein-protein binding and coimmunoprecipitation of MOR and ABIN-1 proteins in cell lysates. Saturation binding studies showed that ABIN-1 had no effect on MOR binding. However, the interaction of ABIN-1 and MOR inhibited the activation of G proteins induced by DAMGO ([d-Ala2,N-Me-Phe4,Gly5-ol]-Enkephalin)...
February 2018: Molecular Pharmacology
https://www.readbyqxmd.com/read/29210574/bis-and-tris-2-oxobenzimidazolyl-hydroborato-complexes-of-sodium-and-thallium-new-classes-of-bidentate-and-tridentate-oxygen-donor-ligands
#19
Ahmed Al-Harbi, Benjamin Kriegel, Shivani Gulati, Matthew J Hammond, Gerard Parkin
A series of bis- and tris(oxobenzimidazolyl)hydroborato compounds, namely, [BoRBenz ]Na and [ToRBenz ]-Na (R = Me, But , Ad), which feature uncommon sterically demanding LX [O2 ] and L2 X [O3 ] donor ligands, have been obtained via the reactions of NaBH4 with 1-R-1,3-dihydro-2H-benzimidazol-2-ones. Evidence that the alkyl substituents are suitably located to have a significant impact on the coordination environment is provided by the observation that the methyl derivative [ToMeBenz ]Na(κ3 -diglyme) exhibits κ3 -coordination of the diglyme, whereas the t-butyl and adamantyl derivatives, [ToBut Benz ]Na(κ2 -diglyme) and [ToAdBenz ]Na(κ2 -diglyme), exhibit κ2 -coordination...
December 18, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/29154481/bayesian-word-learning-in-multiple-language-environments
#20
Benjamin D Zinszer, Sebi V Rolotti, Fan Li, Ping Li
Infant language learners are faced with the difficult inductive problem of determining how new words map to novel or known objects in their environment. Bayesian inference models have been successful at using the sparse information available in natural child-directed speech to build candidate lexicons and infer speakers' referential intentions. We begin by asking how a Bayesian model optimized for monolingual input (the Intentional Model; Frank et al., 2009) generalizes to new monolingual or bilingual corpora and find that, especially in the case of the bilingual input, the model shows a significant decrease in performance...
November 20, 2017: Cognitive Science
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