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https://www.readbyqxmd.com/read/28535036/reversible-bond-cation-coupled-electron-transfer-on-phenylenediamine-based-rhodamine-b-and-its-application-on-electrochromism
#1
Xiaojun Wang, Shuo Wang, Chang Gu, Weiran Zhang, Hongzhi Zheng, Jingjing Zhang, Geyu Lu, Yu-Mo Zhang, Minjie Li, Sean Xiao-An Zhang
A bio-mimetic system on reversible bond coupled electron transfer (BCET) has been proposed and investigated in a switchable Rh-N molecule with redox active subunits. We discover that energy barrier of C-N bond breaking is reduced dramatically to less than 1/7 (from 40.4 kcal/mol to 5.5 kcal/mol), and 1/3 of the oxidation potential has been simultaneously lowered (from 0.67 V to 0.43 V) with the oxidation of Rh-N. The concept, cation coupled electron transfer (CCET), is highly recommended by analyzing existing proton coupled electron transfer (PCET) and metal coupled electron transfer (MCET) along with aforementioned BCET, which have same characteristic of transferring positive charges, such as proton, metal ion, and organic cation...
May 23, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28535030/sulfonated-holey-graphene-oxide-shgo-filled-sulfonated-poly-ether-ether-ketone-membrane-the-role-of-holes-in-the-shgo-in-improving-its-performance-as-proton-exchange-membrane-for-direct-methanol-fuel-cells
#2
Zhong-Jie Jiang, Zhongqing Jiang, Xiaoning Na Tian, Lijuan Luo, Meilin Liu
Sulfonated holey graphene oxides (SHGOs) have synthesized by the etching of sulfonated graphene oxides with concentrated HNO3 under the assistance of ultrasonication. These SHGOs could be used as the fillers for the sulfonated aromatic poly(ether ether ketone) (SPEEK) membrane. The obtained SHGO incorporated SPEEK membrane has a uniform and dense structure, exhibiting the higher performance as proton exchange membranes (PEMs), for instance, higher proton conductivity, lower activation energy for proton conduction, and comparable methanol permeability, as compared to Nafion® 112...
May 23, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28534953/proteomic-analysis-of-differentially-expressed-proteins-in-kidneys-of-brain-dead-rabbits
#3
Ling Li, Ning Li, Chongxiang He, Wei Huang, Xiaoli Fan, Zibiao Zhong, Yanfeng Wang, Qifa Ye
A large number of previous clinical studies have reported a delayed graft function for brain dead donors, when compared with living relatives or cadaveric organ transplantations. However, there is no accurate method for the quality evaluation of kidneys from brain‑dead donors. In the present study, two‑dimensional gel electrophoresis and MALDI‑TOF MS‑based comparative proteomic analysis were conducted to profile the differentially‑expressed proteins between brain death and the control group renal tissues...
May 19, 2017: Molecular Medicine Reports
https://www.readbyqxmd.com/read/28534813/synthesis-and-characterization-of-dual-sensitive-fluorescent-nanogels-for-enhancing-drug-delivery-and-tracking-intracellular-drug-delivery
#4
Szu-Yuan Wu, Tilahun Ayane Debele, Yu-Chih Kao, Hsieh-Chih Tsai
Here, dual-sensitive fluorescent branched alginate-polyethyleneimine copolymer (bAPSC) nanogels were synthesized from thiolated alginate and stearoyl-derivatized branched polyethyleneimine. The formation of bAPSC conjugates was confirmed through proton nuclear magnetic resonance and Fourier transform infrared spectroscopy, whereas dynamic light scattering was used to measure the particle size and ζ potential of the nanogels. The fluorescent properties of the nanogels were confirmed through fluorescent spectroscopy and microscopy...
May 19, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/28534631/photochemical-formation-of-anthracene-quinone-methide-derivatives
#5
Djani Skalamera, Kata Mlinarić-Majerski, Irena Martin Kleiner, Marijeta Kralj, Jessy Oake, Peter Wan, Cornelia Bohne, Nikola Basaric
Anthrols 2-7 were synthesized and their photochemical reactivity investigated by irradiations in aq. CH3OH. Upon excitation with visible light (λ > 400 nm) in methanolic solutions they undergo photodehydration or photodeamination and deliver methyl ethers, most probably via quinone methides (QMs), with methanolysis quantum efficiencies ΦR = 0.02-0.3. Photophysical properties of 2-7 were determined by steady-state fluorescence and time-correlated single photon counting. Generally, anthrols 2-7 are highly fluorescent in aprotic solvents (ΦF = 0...
May 23, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28534620/hydrogen-atom-transfer-hat-processes-promoted-by-the-quinolinimide-n-oxyl-radical-a-kinetic-and-theoretical-study
#6
Gino A DiLabio, Paola Franchi, Osvaldo Lanzalunga, Andrea Lapi, Fiorella Lucarini, Marco Lucarini, Marco Mazzonna, Viki Kumar Prasad, Barbara Ticconi
A kinetic study of the hydrogen atom transfer (HAT) reactions from a series of organic compounds to the quinolinimide-N-oxyl radical (QINO) has been carried out in CH3CN. The HAT rate constants are significantly higher than those observed with the phthalimide-N-oxyl radical (PINO) as a result of enthalpic and polar effects due to the presence of the N-heteroaromatic ring in QINO. The relevance of polar effects is supported by theoretical calculations carried out for the reactions of the two N-oxyl radicals with toluene which indicate that the HAT process is characterized by a significant degree of charge transfer enabled by the pi-stacking that occurs in the transition state structures between the toluene and the N-oxyl aromatic rings...
May 23, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28534618/microsecond-timescale-proton-rotating-frame-relaxation-under-magic-angle-spinning
#7
Petra Rovó, Rasmus Linser
This paper deals with the theoretical foundation of proton magic-angle-spinning rotating-frame relaxation (R1ρ) and establishes the range of validity and accuracy of the presented approach to describe low-amplitude microsecond timescale motion in the solid state. Beside heteronuclear dipolar and chemical shift anisotropy interactions, a major source of relaxation for protons is the homonuclear dipolar interaction. For this latter relaxation process no general analytical equation has been published until now which would describe the R1ρ relaxation at any spinning-speed, spin-lock field, or tilt-angle...
May 23, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28534389/coadministration-of-proton-pump-inhibitors-may-decrease-the-efficacy-of-capecitabine-in-metastatic-breast-cancer-patients
#8
Kadri Altundag
No abstract text is available yet for this article.
March 2017: Journal of B.U.ON.: Official Journal of the Balkan Union of Oncology
https://www.readbyqxmd.com/read/28534162/applying-protein-based-amide-proton-transfer-mr-imaging-to-distinguish-solitary-brain-metastases-from-glioblastoma
#9
Hao Yu, Huiling Lou, Tianyu Zou, Xianlong Wang, Shanshan Jiang, Zhongqing Huang, Yongxing Du, Chunxiu Jiang, Ling Ma, Jianbin Zhu, Wen He, Qihong Rui, Jianyuan Zhou, Zhibo Wen
OBJECTIVES: To determine the utility of amide proton transfer-weighted (APTw) MR imaging in distinguishing solitary brain metastases (SBMs) from glioblastomas (GBMs). METHODS: Forty-five patients with SBMs and 43 patients with GBMs underwent conventional and APT-weighted sequences before clinical intervention. The APTw parameters and relative APTw (rAPTw) parameters in the tumour core and the peritumoral brain zone (PBZ) were obtained and compared between SBMs and GBMs...
May 22, 2017: European Radiology
https://www.readbyqxmd.com/read/28533674/impact-of-gastroesophageal-reflux-control-through-tailored-proton-pump-inhibition-therapy-or-fundoplication-in-patients-with-barrett-s-esophagus
#10
Francisco Baldaque-Silva, Michael Vieth, Mumen Debel, Bengt Håkanson, Anders Thorell, Nuno Lunet, Huan Song, Miguel Mascarenhas-Saraiva, Gisela Pereira, Lars Lundell, Hanns-Ulrich Marschall
AIM: To determine the impact of upwards titration of proton pump inhibition (PPI) on acid reflux, symptom scores and histology, compared to clinically successful fundoplication. METHODS: Two cohorts of long-segment Barrett's esophagus (BE) patients were studied. In group 1 (n = 24), increasing doses of PPI were administered in 8-wk intervals until acid reflux normalization. At each assessment, ambulatory 24 h pH recording, endoscopy with biopsies and symptom scoring (by a gastroesophageal reflux disease health related quality of life questionnaire, GERD/HRLQ) were performed...
May 7, 2017: World Journal of Gastroenterology: WJG
https://www.readbyqxmd.com/read/28533401/evolutionary-steps-involving-counterion-displacement-in-a-tunicate-opsin
#11
Keiichi Kojima, Takahiro Yamashita, Yasushi Imamoto, Takehiro G Kusakabe, Motoyuki Tsuda, Yoshinori Shichida
Ci-opsin1 is a visible light-sensitive opsin present in the larval ocellus of an ascidian, Ciona intestinalis This invertebrate opsin belongs to the vertebrate visual and nonvisual opsin groups in the opsin phylogenetic tree. Ci-opsin1 contains candidate counterions (glutamic acid residues) at positions 113 and 181; the former is a newly acquired position in the vertebrate visual opsin lineage, whereas the latter is an ancestral position widely conserved among invertebrate opsins. Here, we show that Glu113 and Glu181 in Ci-opsin1 act synergistically as counterions, which imparts molecular properties to Ci-opsin1 intermediate between those of vertebrate- and invertebrate-type opsins...
May 22, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28533185/the-small-molecule-iitr08027-restores-the-antibacterial-activity-of-fluoroquinolones-against-multidrug-resistant-acinetobacter-baumannii-by-efflux-inhibition
#12
Tapas Bhattacharyya, Atin Sharma, Jawed Akhter, Ranjana Pathania
Efflux pumps are one of the major determinants of multiple drug resistance. In this study, AbeM, a multidrug efflux pump in Acinetobacter baumannii, was cloned into a multicopy plasmid (pUC18) and was transformed into an efflux-deficient mutant of Escherichia coli (KAM32). The elevated resistance profile of the recombinant E. coli for ciprofloxacin was utilised to screen a small-molecule library of 8000 molecules to identify IITR08027, a small molecule that is not inhibitory on its own but that could potentiate the activity of ciprofloxacin...
May 19, 2017: International Journal of Antimicrobial Agents
https://www.readbyqxmd.com/read/28532094/electrochemical-sensing-of-doxorubicin-in-unprocessed-whole-blood-cell-lysate-and-human-plasma-samples-using-thin-film-of-poly-arginine-modified-glassy-carbon-electrode
#13
Jafar Soleymani, Mohammad Hasanzadeh, Morteza Eskandani, Maryam Khoubnasabjafari, Nasrin Shadjou, Abolghasem Jouyban
A thin film of poly-arginine fabricated on glassy carbon electrode by one step electrodeposition method is applied for detection of doxorubicin hydrochloride in whole blood, cell lysate, and untreated-plasma samples. Cyclic voltammetry results indicated that the doxorubicin is oxidized via two electrons and two protons at physiological pH (pH=7.4) using poly-arginine thin film modified glassy carbon. More importantly, electrostatic repulsion takes place between the prepared polymer film-modified electrode and selected drug resulting in the signal amplification on oxidation of doxorubicin and lowering its over potential and thereby selective detection of doxorubicin in real samples...
August 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28531794/binding-of-the-anticancer-drug-bi-2536-to-human-serum-albumin-a-spectroscopic-and-theoretical-study
#14
Jesús Fernández-Sainz, Pedro J Pacheco-Liñán, José M Granadino-Roldán, Iván Bravo, Andrés Garzón, Jaime Rubio-Martínez, José Albaladejo
BI-2536 is a potent Polo-like kinase inhibitor which induces apoptosis in diverse human cancer cell lines. The binding affinity of BI-2536 for human serum albumin (HSA) protein may define its pharmacokinetic and pharmacodynamic profile. We have studied the binding of BI-2536 to HSA by means of different spectroscopic techniques and docking calculations. We have experimentally observed that the affinity of BI-2536 for HSA is higher than that of other common HSA binding drugs. Therefore, it can be postulated that the drug dose should be increased to achieve a certain concentration of free drug in plasma, although BI-2536 could also reach tumour tissues by uptaking HSA/BI-2536 complex...
May 12, 2017: Journal of Photochemistry and Photobiology. B, Biology
https://www.readbyqxmd.com/read/28531352/conformational-complexity-in-the-lh2-antenna-of-the-purple-sulfur-bacterium-allochromatium-vinosum-revealed-by-hole-burning-spectroscopy
#15
Adam Kell, Mahboobe Jassas, Khem Acharya, Kirsty Hacking, Richard J Cogdell, Ryszard J Jankowiak
This work discusses the protein conformational complexity of the B800-850 LH2 complexes from the purple sulfur bacterium Allochromatium vinosum, focusing on the spectral characteristics of the B850 chromophores. Low-temperature B850 absorption and the split B800 band shift blue and red, respectively, at elevated temperatures, revealing isosbestic points. The latter indicates the presence of two (unresolved) conformations of B850 bacteriochlorophylls (BChls), referred to as conformations 1 and 2, and two conformations of B800 BChls, denoted as B800R and B800B...
May 22, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28531106/fully-polymeric-ph-sensor-realized-by-means-of-a-single-step-soft-embossing-technique
#16
Paola Fanzio, Chi-Tung Chang, Maciej Skolimowski, Simone Tanzi, Luigi Sasso
We present here an electrochemical sensor microsystem for the monitoring of pH. The all-polymeric device is comprised of a cyclic olefin copolymer substrate, a 200 nm-thin patterned layer of conductive polymer (PEDOT), and a 70 nm electropolymerized layer of a pH sensitive conductive polymer (polyaniline). The patterning of the fluidic (microfluidic channels) and conductive (wiring and electrodes) functional elements was achieved with a single soft PDMS mold via a single embossing step process. A post-processing treatment with ethylene glycol assured the functional enhancement of the electrodes, as demonstrated via an electrical and electrochemical characterization...
May 20, 2017: Sensors
https://www.readbyqxmd.com/read/28531096/the-lys-asp-tyr-triad-within-the-mite-allergen-der-p-1-propeptide-is-a-critical-structural-element-for-the-ph-dependent-initiation-of-the-protease-maturation
#17
Andy Chevigné, Vincenzo Campizi, Martyna Szpakowska, David Bourry, Marie-Eve Dumez, José C Martins, André Matagne, Moreno Galleni, Alain Jacquet
The major house dust mite allergen, Der p 1, is a papain-like cysteine protease expressed as an inactive precursor, proDer p 1, carrying an N-terminal propeptide with a unique structure. The maturation of the zymogen into an enzymatically-active form of Der p 1 is a multistep autocatalytic process initiated under acidic conditions through conformational changes of the propeptide, leading to the loss of its inhibitory ability and its subsequent gradual cleavage. The aims of this study were to characterize the residues present in the Der p 1 propeptide involved in the initiation of the zymogen maturation process, but also to assess the impact of acidic pH on the propeptide structure, the activity of Der p 1 and the fate of the propeptide...
May 20, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/28531093/development-of-a-low-energy-x-ray-camera-for-the-imaging-of-secondary-electron-bremsstrahlung-x-ray-emitted-during-proton-irradiation-for-range-estimation
#18
Koki Ando, Mitsutaka Yamaguchi, Seiichi Yamamoto, Toshiyuki Toshito, Naoki Kawachi
Imaging of secondary electron bremsstrahlung x-ray emitted during proton irradiation is a possible method for measurement of the proton beam distribution in phantom. However, it is not clear that the method is used for range estimation of protons. For this purpose, we developed a low-energy x-ray camera and conducted imaging of the bremsstrahlung x-ray produced during irradiation of proton beams. We used a 20 mm  ×  20 mm  ×  1 mm finely grooved GAGG scintillator that was optically coupled to a one-inch square high quantum efficiency (HQE)-type position-sensitive photomultiplier tube to form an imaging detector...
May 22, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28530822/synthesis-and-membrane-properties-of-sulfonated-poly-arylene-ether-sulfone-statistical-copolymers-for-electrolysis-of-water-influence-of-meta-and-para-substituted-comonomers
#19
Amin Daryaei, Gregory C Miller, Jason Willey, Shreya Roy-Choudhury, Britannia Vondrasek, Dana Kazerooni, Matthew Russell Burtner, Cortney Kenneth Mittelsteadt, John J Lesko, Judy S Riffle, James E McGrath
Two series of high molecular weight disulfonated poly(arylene ether sulfone) random copolymers were synthesized as proton exchange membranes for high temperature water electrolyzers. These copolymers differ based on the position of the ether bonds on the aromatic rings. One series is comprised of fully para-substituted hydroquinone comonomer and the other series incorporated 25 mole % of a meta-substituted comonomer, resorcinol, and 75 mole % hydroquinone. The influence of the substitution position on water uptake and electrochemical properties of the membranes were investigated and compared to that of the state-of-the-art membrane, Nafion™...
May 22, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28530798/heterogeneous-molecular-catalysis-of-electrochemical-reactions-volcano-plots-and-catalytic-tafel-plots
#20
Cyrille Costentin, Jean-Michel Savéant
We analyze here, in the framework of heterogeneous mo-lecular catalysis the reasons of occurrence or non-occurrence of volcanoes upon plotting the kinetics of the catalytic reaction versus the stabilization free energy of the primary intermediate of the catalytic process. As in the case of homogeneous molecular catalysis or catalysis by surface active metallic sites, a strong motivation of such studies relates to modern energy challenges, particularly those involving small molecules such as water, hydrogen, oxygen, proton and carbon dioxide...
May 22, 2017: ACS Applied Materials & Interfaces
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