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https://www.readbyqxmd.com/read/28926259/dual-photochemical-reaction-pathway-in-flavin-based-photoreceptor-lov-domain-a-combined-quantum-mechanics-molecular-mechanics-investigation
#1
Setsuko Nakagawa, Oliver Weingart, Christel M Marian
The primary photochemical reaction of the light, oxygen, and voltage (LOV) domain of the blue-light photo-sensor YtvA of Bacillus subtilis were investigated using high-level QM(DFT/MRCI)/MM methods. After blue-light excitation, the Sγ atom of the reactive cysteine forms a covalent bond with the C4a of the flavin mononucleotide (FMN) ring. Two conformations for the side chain of reactive cysteine with occupancies of 70% (conf A) and 30% (conf B) are observed in the X-ray crystallographic structures of the YtvA-LOV (Möglich, A...
September 19, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28926077/low-temperature-growth-of-fully-covered-single-layer-graphene-using-a-cocu-catalyst
#2
Hisashi Sugime, Lorenzo D'Arsié, Santiago Esconjauregui, Guofang Zhong, Xingyi Wu, Eugen Hildebrandt, Hikmet Sezen, Matteo Amati, Luca Gregoratti, Robert S Weatherup, John Robertson
A bimetallic CoCu alloy thin-film catalyst is developed that enables the growth of uniform, high-quality graphene at 750 °C in 3 min by chemical vapour deposition. The growth outcome is found to vary significantly as the Cu concentration is varied, with ∼1 at% Cu added to Co yielding complete coverage single-layer graphene growth for the conditions used. The suppression of multilayer formation is attributable to Cu decoration of high reactivity sites on the Co surface which otherwise serve as preferential nucleation sites for multilayer graphene...
September 19, 2017: Nanoscale
https://www.readbyqxmd.com/read/28925004/size-dependent-reactivity-of-nano-sized-neutral-manganese-oxide-clusters-toward-ethylene
#3
Jiao-Jiao Chen, Ting Zhang, Mei-Qi Zhang, Qing-Yu Liu, Xiao-Na Li, Sheng-Gui He
Neutral manganese oxide clusters Mn2NO3N+x (N = 2-22; x = -1, 0, 1) with dimensions up to a nanosize were prepared by laser ablation and reacted with C2H4 in a fast flow reactor. The size-dependent reactivity of C2H4 adsorption on these clusters was experimentally identified and the adsorption reactivity decreases generally with the increase of cluster size. Density functional theory calculations were performed to study the geometrical and electronic structures of Mn2NO3N (N = 1-6) clusters. The calculated results indicated that the coordination number and the charge distribution of the metal centers are responsible for the experimentally observed size-dependent reactivity...
September 19, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28924832/influence-of-linkage-stereochemistry-and-protecting-groups-on-glycosidic-bond-stability-of-sodium-cationized-glycosyl-phosphates
#4
Y Zhu, Zhihua Yang, M T Rodgers
Energy-resolved collision-induced dissociation (ER-CID) experiments of sodium cationized glycosyl phosphate complexes, [GP x +Na](+), are performed to elucidate the effects of linkage stereochemistry (α versus β), the geometry of the leaving groups (1,2-cis versus 1,2-trans), and protecting groups (cyclic versus non-cyclic) on the stability of the glycosyl phosphate linkage via survival yield analyses. A four parameter logistic dynamic fitting model is used to determine CID50% values, which correspond to the level of rf excitation required to produce 50% dissociation of the precursor ion complexes...
September 18, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28923702/zinc-oxide-nanoparticles-synthesis-antiseptic-activity-and-toxicity-mechanism
#5
REVIEW
A Król, P Pomastowski, K Rafińska, V Railean-Plugaru, B Buszewski
Zinc oxide (ZnO), as a material with attractive properties, has attracted great interest worldwide, particularly owing to the implementation of the synthesis of nano-sized particles. High luminescent efficiency, a wide band gap (3.36eV), and a large exciton binding energy (60meV) has triggered intense research on the production of nanoparticles using different synthesis methods and on their future applications. ZnO nanomaterials can be used in industry as nano-optical and nano-electrical devices, in food packaging and in medicine as antimicrobial and antitumor agents...
August 26, 2017: Advances in Colloid and Interface Science
https://www.readbyqxmd.com/read/28922530/a-space-charge-treatment-of-the-increased-concentration-of-reactive-species-at-the-surface-of-a-ceria-solid-solution
#6
Alexander F Zurhelle, Xiaorui Tong, Andreas Klein, David S Mebane, Roger A De Souza
We apply a space-charge theory applicable to concentrated solid solutions-Poisson-Cahn theory-to describe quantitatively as a function of temperature and oxygen partial pressure published data obtained by in situ X-ray photoelectron spectroscopy (XPS) for the concentration of Ce3+ (the reactive species) at the surface of the oxide catalyst Ce0.8Sm0.2O1.9. In contrast to previous theoretical treatments, our calculations clearly indicate that the surface is positively charged and compensated by an attendant negative space-charge zone...
September 18, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28921964/versatile-synthetic-route-for-%C3%AE-functionalized-chlorins-and-porphyrins-by-varying-the-size-of-michael-donors-syntheses-photophysical-and-electrochemical-redox-properties
#7
Nivedita Chaudhri, Nitika Grover, Muniappan Sankar
One-pot facile synthesis and characterization of novel β-substituted meso-tetraphenylporphyrins and/or chlorins were described. The high regioselective reactivity of active methylene compounds in Michael addition reaction was reported to access β-substituted trans-chlorins. Size-dependent approach was applied for the fine-tuning of product formation from porphyrins to chlorins. Notably, we were able to isolate mono/trisubstituted porphyrin and/or di/tetra-substituted chlorin from one-pot synthesis for the first time in porphyrin chemistry...
September 18, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28921684/generation-of-stable-ruthenium-iv-ketimido-complexes-via-oxidative-addition-of-oxime-esters-to-ruthenium-ii-reactivity-studies-based-on-electronic-properties-of-the-ru-n-bond
#8
Takuya Shimbayashi, Kazuhiro Okamoto, Kouichi Ohe
The reaction of an oxime ester with RuX2(PPh3)3 proceeded smoothly at room temperature to afford a stable Ru(IV)-ketimido complex as an oxidative adduct. The structure of the complex was unambiguously determined by X-ray crystallographic analysis, which showed an almost linear Ru-N-C array. The electronic properties of the nitrogen atom were estimated by density functional theory (DFT) calculations, and results suggested the double-bond character of the Ru-N bond. Kinetic studies combined with consideration of the substituent effect on the oxime ester led to proposing the reaction mechanism involving oxidative addition, which could proceed via N,O-chelate coordination to the Ru center prior to N-O bond cleavage...
September 16, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28920673/work-function-control-of-germanium-through-carborane-carboxylic-acid-surface-passivation
#9
Andrew C Serino, Mary E Anderson, Liban M A Saleh, Rafal Miroslaw Dziedzic, Harrison Mills, Liv K Heidenreich, Alexander M Spokoyny, Paul S Weiss
Self-assembled monolayers (SAMs) of carborane isomers with different dipole moments passivate germanium to modulate surface work function while maintaining chemical environment and surface energy. To identify head groups capable of monolayer formation on germanium surfaces, we studied thiol-, hydroxyl-, and carboxyl-terminated carboranes. These films were successfully formed with carboxylic acid head groups instead of the archetypal thiol, suggesting that the carborane cluster significantly affects head group reactivity...
September 18, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28920600/quantum-state-selected-integral-cross-sections-for-the-charge-transfer-collision-of-o2-a-4-%C3%AE-u5-2-3-2-1-2-1-2-v-1-2-j-o2-x-2-%C3%AE-g3-2-1-2-v-22-23-j-ar-at-center-of-mass-collision-energies-of-0-05-10-00-ev
#10
Bo Xiong, Yih-Chung Chang, Cheuk-Yiu Ng
By employing the sequential electric field pulsing scheme for vacuum ultraviolet (VUV) laser pulsed field ionization-photoion (PFI-PI) detection, we have successfully recorded the spin-orbit and rovibronic state resolved VUV-PFI-PI spectra for O2(+)(a(4)Πu5/2,3/2,1/2,-1/2: ν(+) = 0-2; J(+)) and O2(+)(X(2)Πg3/2,1/2: ν(+) = 21-23; J(+)), indicating that O2(+)(a(4)Πu) and O2(+)(X(2)Πg) ions in these spin-orbit and rovibronic states can be prepared for ion-molecule collision studies. The present experiment is concerned with the measurement of absolute integral cross sections (σ's) of the charge transfer reactions, O2(+)(a(4)Πu5/2,3/2,1/2,-1/2: ν(+) = 1, 2; J(+)) [O2(+)(X(2)Πg1/2,3/2: ν(+) = 22, 23)] + Ar → Ar(+) + O2...
September 18, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28919752/zinc-oxide-nanoparticles-induce-apoptosis-and-autophagy-in-human-ovarian-cancer-cells
#11
Ding-Ping Bai, Xi-Feng Zhang, Guo-Liang Zhang, Yi-Fan Huang, Sangiliyandi Gurunathan
BACKGROUND: Zinc oxide nanoparticles (ZnO NPs) are frequently used in industrial products such as paint, surface coating, and cosmetics, and recently, they have been explored in biologic and biomedical applications. Therefore, this study was undertaken to investigate the effect of ZnO NPs on cytotoxicity, apoptosis, and autophagy in human ovarian cancer cells (SKOV3). METHODS: ZnO NPs with a crystalline size of 20 nm were characterized with various analytical techniques, including ultraviolet-visible spectroscopy, X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, and atomic force microscopy...
2017: International Journal of Nanomedicine
https://www.readbyqxmd.com/read/28919740/low-toxic-maghemite-nanoparticles-for-theranostic-applications
#12
Elena A Kuchma, Peter V Zolotukhin, Anna A Belanova, Mikhail A Soldatov, Tatiana A Lastovina, Stanislav P Kubrin, Anatoliy V Nikolsky, Lidia I Mirmikova, Alexander V Soldatov
BACKGROUND: Iron oxide nanoparticles have numerous and versatile biological properties, ranging from direct and immediate biochemical effects to prolonged influences on tissues. Most applications have strict requirements with respect to the chemical and physical properties of such agents. Therefore, developing rational design methods of synthesis of iron oxide nanoparticles remains of vital importance in nanobiomedicine. METHODS: Low toxic superparamagnetic iron oxide nanoparticles (SPIONs) for theranostic applications in oncology having spherical shape and maghemite structure were produced using the fast microwave synthesis technique and were fully characterized by several complementary methods (transmission electron microscopy [TEM], X-ray diffraction [XRD], dynamic light scattering [DLS], X-ray photoelectron spectroscopy [XPS], X-ray absorption near edge structure [XANES], Mossbauer spectroscopy, and HeLa cells toxicity testing)...
2017: International Journal of Nanomedicine
https://www.readbyqxmd.com/read/28917902/an-unexpected-reactivity-during-periodate-oxidation-of-chitosan-and-the-affinity-of-its-2-3-di-aldehyde-toward-sulfa-drugs
#13
Sherif M A S Keshk, Ahmed M Ramadan, Abdullah G Al-Sehemi, Ahmad Irfan, Samir Bondock
In an attempt to determine the reactivity during the periodate oxidation of the vicinal amino sugar, chitosan was oxidized by KIO4 in a neutral medium. The reactivity was unexpectedly found to be low. The formation of di-aldehyde chitosan (DACT) might cause the low reactivity of chitosan oxidation. Therefore, density functional theory (DFT) calculations were carried out, which revealed that the greater stability of the cyclic amino iodate intermediate might retard the ring opening to form DACT. Furthermore, the affinity of the formation of two novel Schiff bases from the interaction of delivered DACT with two sulfa drugs [sulfanilamide and sulfathiazole] was also investigated using aldehyde content estimation...
November 1, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28916419/development-of-an-indirect-enzyme-linked-immunosorbent-assay-elisa-to-differentiate-antibodies-against-wild-type-porcine-reproductive-and-respiratory-syndrome-from-the-vaccine-strain-tjm-f92-based-on-a-recombinant-nsp2-protein
#14
X X Wang, F X Wang, Z G Li, Y J Wen, X Wang, N Song, H Wu
An accurate ELISA method to differentiate pigs infected with wild-type porcine reproductive and respiratory syndrome (PRRSV) strains from vaccinated ones would help to monitor PRRSV vaccination compliance. The recombinant protein GST-d120aa derived from the continuous deletion of 120 amino acids in the non-structural protein 2 region of the modified-live vaccine strain TJM-F92 was used to develop an indirect enzyme-linked immunosorbent assay (d120-ELISA) for differentiating serum antibodies against TJM-F92 from other PRRSV strains...
September 12, 2017: Journal of Virological Methods
https://www.readbyqxmd.com/read/28915037/reactivity-of-a-fes-surface-under-room-temperature-exposure-to-nitrogen-and-h2s
#15
Miguel Angel Angel Niño, Eduardo Flores, Carlos Sanchez, Juan M Rojo
The reactivity of an iron monosulfide surface exposed at room temperature to molecular nitrogen and hydrogen sulfide has been investigated using X-ray photoemission spectroscopy (XPS) and thermal desorption spectroscopy (TDS). We have observed adsorption of nitrogen at room temperature that depends on the surface nanostructure and on the electronic state of nitrogen. The subsequent reaction of this adsorbed nitrogen with hydrogen sulfide results in depletion of the nitrogen surface content which can be interpreted in terms of ammonia formation...
September 15, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28911649/long-chain-bases-from-sea-cucumber-mitigate-endoplasmic-reticulum-stress-and-inflammation-in-obesity-mice
#16
Shiwei Hu, Jinhui Wang, Jingfeng Wang, Changhu Xue, Yuming Wang
Endoplasmic reticulum (ER) stress and inflammation can induce hyperglycemia. Long-chain bases (LCBs) from sea cucumber exhibit antihyperglycemic activities. However, their effects on ER stress and inflammation are unknown. We investigated the effects of LCBs on ER stress and inflammatory response in high-fat, fructose diet-induced obesity mice. Reactive oxygen species and free fatty acids were measured. Inflammatory cytokines in serum and their mRNA expressions in epididymal adipose tissues were investigated...
July 2017: Journal of Food and Drug Analysis
https://www.readbyqxmd.com/read/28904021/bap-exposure-causes-oocyte-meiotic-arrest-and-fertilization-failure-to-weaken-female-fertility
#17
Mianqun Zhang, Yilong Miao, Qian Chen, Meng Cai, Wenkang Dong, Xiaoxin Dai, Yajuan Lu, Changyin Zhou, Zhaokang Cui, Bo Xiong
Benzo[a]pyrene (BaP) is a ubiquitous environmental pollutant and carcinogen that is frequently found in particulate matter, with a diameter of ≤2.5 μm (PM2.5). It has been reported to interrupt the normal reproductive system, but the exact molecular basis has not been clearly defined. To understand the underlying mechanisms regarding how BaP exposure disrupts female fertility, we evaluated oocyte quality by assessing the critical regulators and events during oocyte meiotic maturation and fertilization. We found that BaP exposure compromised the mouse oocyte meiotic progression by disrupting normal spindle assembly, chromosome alignment, and kinetochore-microtubule attachment, consequently leading to the generation of aneuploid eggs...
September 13, 2017: FASEB Journal: Official Publication of the Federation of American Societies for Experimental Biology
https://www.readbyqxmd.com/read/28901762/synthesis-structure-and-reactivity-of-a-terminal-magnesium-hydride-compound-with-a-carbatrane-motif-tism-pr-i-benz-mgh-a-multifunctional-catalyst-for-hydrosilylation-and-hydroboration
#18
Michael Rauch, Serge Ruccolo, Gerard Parkin
The tris[(1-isopropylbenzimidazol-2-yl)dimethylsilyl)]methyl ligand, [Tism(Pr(i)Benz)], has been employed to form the magnesium carbatrane compound, [Tism(Pr(i)Benz)]MgH, which possesses a terminal hydride ligand. Specifically, [Tism(Pr(i)Benz)]MgH is obtained via the reaction of [Tism(Pr(i)Benz)]MgMe with PhSiH3. The reactivity of [Tism(Pr(i)Benz)]MgMe and [Tism(Pr(i)Benz)]MgH allows access to a variety of other structurally characterized carbatrane derivatives, including [Tism(Pr(i)Benz)]MgX [X = F, Cl, Br, I, SH, N(H)Ph, CH(Me)Ph, O2CMe, S2CMe]...
September 13, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28901511/n%C3%A2-acetylcysteine-induces-apoptosis-via-the-mitochondria%C3%A2-dependent-pathway-but-not-via-endoplasmic-reticulum-stress-in-h9c2-cells
#19
Yuyong Liu, Ke Liu, Nian Wang, Huali Zhang
N‑acetylcysteine (NAC), a precursor of glutathione, is a widely used thiol‑containing antioxidant and modulator of the intracellular redox state. Our previous study demonstrated that excess reduced glutathione (GSH) from NAC treatment paradoxically led to a reduction in glutathione redox potential, increased mitochondrial oxidation and caused cytotoxicity at lower reactive oxygen species levels in H9c2 cells. However, no detailed data are available on the molecular mechanisms of NAC‑induced cytotoxicity on H9c2 cells...
September 8, 2017: Molecular Medicine Reports
https://www.readbyqxmd.com/read/28901386/aloin-promotes-a549-cell-apoptosis-via-the-reactive-oxygen-species%C3%A2-mitogen-activated-protein-kinase-signaling-pathway-and-p53-phosphorylation
#20
Li Wan, Lin Zhang, Kai Fan, Jianjun Wang
Aloin has the potential to be a novel anticancer agent in cancer therapies. However, the detailed anticancer effect of Aloin remains to be fully elucidated. The present study analyzed the p53‑dependent mechanisms in response to Aloin treatment. Using the p53‑proficient A549 cells, an Aloin‑induced apoptotic cell model was established, which was used to evaluate the potential underlying molecular mechanisms. The results demonstrated that 200, 300 and 400 µM Aloin induced intrinsic cell apoptosis, which was further confirmed by disruption of the mitochondrial membrane potential, elevation of cytosolic Ca2+ levels, and activation of B‑cell lymphoma 2 (Bcl‑2) homologous antagonist killer, Bcl‑2 X‑associated protein, p53 upregulated modulator of apoptosis and phorbol‑12‑myristate‑13‑acetate‑induced protein 1...
August 29, 2017: Molecular Medicine Reports
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