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https://www.readbyqxmd.com/read/28654833/novel-and-economic-acid-base-indicator-based-on-p-toluidine-oligomer-synthesis-characterization-and-solvatochromism-applications
#1
M Sh Zoromba
A new (p-toluidine) oligomer (PTO) was facile synthesized and economically routed via chemical oxidative polymerization by potassium dichromate as an initiator in an acidic aqueous medium at room temperature. The characterization of (p-toluidine) oligomer (PTO) has been described by various techniques including Fourier transform infra-red (FTIR), UV-Visible measurements, Mass spectra, H NMR, and thermal gravimetric analysis (TGA). Solvatochromism of PTO was studied in different polaritiy solvents such as acetic acid, acetone, dimethyl formamide, ethanol, isopropanol, chloroform, p-xylene, dichloromethane and carbon teterachloride...
June 22, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28654809/interactions-between-stepwise-eluted-sub-fractions-of-fulvic-acids-and-protons-revealed-by-fluorescence-titration-combined-with-eem-parafac
#2
Fanhao Song, Fengchang Wu, Fei Guo, Hao Wang, Weiying Feng, Min Zhou, Yanghui Deng, Yingchen Bai, Baoshan Xing, John P Giesy
In aquatic environments, pH can control environmental behaviors of fulvic acid (FA) via regulating hydrolysis of functional groups. Sub-fractions of FA, eluted using pyrophosphate buffers with initial pHs of 3.0 (FA3), 5.0 (FA5), 7.0 (FA7), 9.0 (FA9) and 13.0 (FA13), were used to explore interactions between the various, operationally defined, FA fractions and protons, by use of EEM-PARAFAC analysis. Splitting of peaks (FA3 and FA13), merging of peaks (FA7), disappearance of peaks (FA9 and FA13), and red/blue-shifting of peaks were observed during fluorescence titration...
June 24, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28653540/iron-catalyzed-ortho-selective-c-h-borylation-of-2-phenylpyridines-and-their-analogs
#3
Yusuke Yoshigoe, Yoichiro Kuninobu
Treatment of 2-phenylpyridines (or their analogs) with a 9-bicycloboranonane dimer (9-BBN dimer) in the presence of a catalytic amount of a commercially available iron salt, FeBr3, gave ortho-borylated products in moderate to excellent yields with good functional group tolerance. The reaction proceeded in good yield, even in gram-scale, and also occurred at the C-H bond of heteroaromatic compounds. The cost of the C-H borylation is dramatically lower than that of a previously reported similar palladium-catalyzed reaction...
June 27, 2017: Organic Letters
https://www.readbyqxmd.com/read/28651130/liquefaction-of-kraft-lignin-by-hydrocracking-with-simultaneous-use-of-a-novel-dual-acid-base-catalyst-and-a-hydrogenation-catalyst
#4
Jindong Wang, Wenzhi Li, Huizhen Wang, Qiaozhi Ma, Song Li, Hou-Min Chang, Hasan Jameel
In this study, a novel catalyst, S2O8(2-)-KNO3/TiO2, which has active acidic and basic sites, was prepared and used in lignin hydrocracking with a co-catalyst, Ru/C. Ru/C is an efficient hydrogenation catalyst and S2O8(2-)-KNO3/TiO2 is a dual catalyst, which could efficiently degrade lignin. This catalytic hydrogenation system can reduce solid products to less than 1%, while giving a high liquid product yield of 93%. Catalytic hydrocracking of kraft lignin at 320°C for 6h gave 93% liquid product with 0.5% solid product...
June 8, 2017: Bioresource Technology
https://www.readbyqxmd.com/read/28650068/rational-engineering-of-p-hydroxybenzoate-hydroxylase-to-enable-efficient-gallic-acid-synthesis-via-a-novel-artificial-biosynthetic-pathway
#5
Zhenya Chen, Xiaolin Shen, Jian Wang, Jia Wang, Qipeng Yuan, Yajun Yan
Gallic acid (GA) is a naturally occurring phytochemical that has strong antioxidant and antibacterial activities. It is also used as a potential platform chemical for the synthesis of diverse high-value compounds. Hydrolytic degradation of tannins by acids, bases or microorganisms serves as a major way for GA production, which however, might cause environmental pollution and low yield and efficiency. Here, we report a novel approach for efficient microbial production of GA. First, structure-based rational engineering of PobA, a p-hydroxybenzoate hydroxylase from Pseudomonas aeruginosa, generated a new mutant, Y385F/T294A PobA, which displayed much higher activity towards 3,4-dihydroxybenzoic acid (3,4-DHBA) than the wild type and any other reported mutants...
June 26, 2017: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/28648379/targeted-protein-degradation-from-chemical-biology-to-drug-discovery
#6
REVIEW
Philipp M Cromm, Craig M Crews
Traditional pharmaceutical drug discovery is almost exclusively focused on directly controlling protein activity to cure diseases. Modulators of protein activity, especially inhibitors, are developed and applied at high concentration to achieve maximal effects. Thereby, reduced bioavailability and off-target effects can hamper compound efficacy. Nucleic acid-based strategies that control protein function by affecting expression have emerged as an alternative. However, metabolic stability and broad bioavailability represent development hurdles that remain to be overcome for these approaches...
June 10, 2017: Cell Chemical Biology
https://www.readbyqxmd.com/read/28647364/crystal-structures-of-the-isochorismatase-domains-from-vibrio-anguillarum
#7
Jiansen Du, Tian Deng, Qingjun Ma
Antibiotic resistance is becoming a global threat and overuse of antibiotics in aquaculture disease control worsens the situation. To reduce the risk of drug resistance developed in aquaculture, safer biocontrol programs are needed. Antivirulence therapy, with less chance for developing drug resistance, is a promising approach. To facilitate antivirulence inhibitor design against Vibrio anguillarum, a serious aquaculture pathogen, we present crystal structures for isochorismatase domains of AngB and VabB, which are required to synthesize siderophore, a critical virulence factor...
June 21, 2017: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/28646781/%C3%AE-potential-evidences-silanol-heterogeneity-induced-by-metal-contaminants-at-the-quartz-surface-implications-in-membrane-damage
#8
Cristina Pavan, Francesco Turci, Maura Tomatis, Mara Ghiazza, Dominique Lison, Bice Fubini
Among the physico-chemical features responsible for the so-called "variability of quartz hazard", a key role has been assigned to the silica surface charge, evaluated by means of ζ potential measurement. The ζ potential of silica describes the protonation state of silanols which, in turn, determine interactions with cell membranes. To gain a molecular understanding of the role of silanols in silica pathogenicity, we conducted a systematic investigation of the variation of the ζ potential as a function of pH (ζ plot titration curve) on a large set of respirable quartz particles with different levels of metal contaminants...
June 13, 2017: Colloids and Surfaces. B, Biointerfaces
https://www.readbyqxmd.com/read/28646298/an-on-off-on-fluorescent-probe-for-ascorbic-acid-based-on-cu-zncds-quantum-dots-and-%C3%AE-mno2-nanorods
#9
Hanbing Rao, Yao Gao, Hongwei Ge, Zhaoyi Zhang, Xin Liu, Yan Yang, Yaqin Liu, Wei Liu, Ping Zou, Yanying Wang, Xianxiang Wang, Hua He, Xianying Zeng
This work established a fluorescence approach for detecting ascorbic acid (AA) based on Cu-ZnCdS quantum dots (Cu-ZnCdS QDs) and α-MnO2 nanorods. Cu-ZnCdS QDs and α-MnO2 nanorods were characterized by high-resolution transmission electron microscopy (HRTEM), fluorescence spectroscopy, inductively coupled plasma optical emission spectroscopy (ICP-OES) and X-ray diffraction (XRD). In the presence of α-MnO2 nanorods, the fluorescence of Cu-ZnCdS QDs was greatly quenched through the inner filter effect (IFE)...
June 23, 2017: Analytical and Bioanalytical Chemistry
https://www.readbyqxmd.com/read/28645705/acid-load-and-phosphorus-homeostasis-in-ckd
#10
Pascale Khairallah, Tamara Isakova, John Asplin, Lee Hamm, Mirela Dobre, Mahboob Rahman, Kumar Sharma, Mary Leonard, Edgar Miller, Bernard Jaar, Carolyn Brecklin, Wei Yang, Xue Wang, Harold Feldman, Myles Wolf, Julia J Scialla
BACKGROUND: The kidneys maintain acid-base homeostasis through excretion of acid as either ammonium or as titratable acids that primarily use phosphate as a buffer. In chronic kidney disease (CKD), ammoniagenesis is impaired, promoting metabolic acidosis. Metabolic acidosis stimulates phosphaturic hormones, parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF-23) in vitro, possibly to increase urine titratable acid buffers, but this has not been confirmed in humans. We hypothesized that higher acid load and acidosis would associate with altered phosphorus homeostasis, including higher urinary phosphorus excretion and serum PTH and FGF-23...
June 21, 2017: American Journal of Kidney Diseases: the Official Journal of the National Kidney Foundation
https://www.readbyqxmd.com/read/28645034/formation-of-hematite-nanoparticle-monolayers-of-controlled-coverage-and-structure-at-polymeric-microparticles
#11
Marta Sadowska, Zbigniew Adamczyk, Małgorzata Nattich-Rak
The deposition of hematite nanoparticles (22nm and 29nm in diameter) on negatively charged polystyrene microspheres (820nm in diameter) was studied by micro-electrophoretic measurements and AFM. The influence of ionic strength, varied between 10(-4) and 10(-2)M, was determined. Initially, the electrophoretic mobility change of microspheres upon the addition of controlled amount of hematite nanoparticles were measured. These dependencies were quantitatively interpreted in terms of the general electrokinetic model...
June 9, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28644608/targeting-cpg-adjuvant-to-lymph-node-via-dextran-conjugate-enhances-anti-tumor-immunotherapy
#12
Weidong Zhang, Myunggi An, Jingchao Xi, Haipeng Liu
Nucleic acids based adjuvants recognized by Toll-like receptors (TLR) are potent immune system stimulants that can augment the anti-tumor immune responses in an antigen-specific manner. However, their clinical uses as vaccine adjuvants are limited primarily due to lack of accumulation in the lymph nodes, the anatomic sites where the immune responses are initiated. Here, we showed that chemical conjugation of type B CpG DNA, a TLR9 agonist to dextran polymer dramatically enhanced CpG's lymph node accumulation in mice...
June 23, 2017: Bioconjugate Chemistry
https://www.readbyqxmd.com/read/28643881/virucides-in-apiculture-persistence-of-surrogate-enterovirus-under-simulated-field-conditions
#13
Jana Prodělalová, Hana Malenovská, Romana Moutelíková, Dalibor Titěra
BACKGROUND: Honeybee viruses were recognized among the most important factors leading to colony losses worldwide. Colony food and faeces were regarded as possible source of infectious viruses able to contaminate environment and equipment of apiaries. Thus, methods for elimination of viruses are required. No cell culture assay for testing the effect of disinfectants on honeybee viruses is available yet. Therefore, surrogate virus was employed for testing of iodophor- and peracetic acid-based disinfectants efficacy in combination with six organic contaminants at +6 °C and +22 °C...
June 23, 2017: Pest Management Science
https://www.readbyqxmd.com/read/28643874/2-6-bis-diazaboryl-pyridine-a-superbasic-sterically-demanding-pyridine-ligand
#14
Tobias Böttcher, Daniel Himmel, Jan Schröder
Herein we present a convenient one-pot route to a sterically demanding superbasic pyridine. Functionalization of the 2,6-positions with the highly sigma-donating boryl-groups shifts the calculated gas phase basicity of the pyridine's nitrogen atom to 1012 kJ mol-1, which outperforms the 'proton sponge' 1,8-bis(dimethylamino)naphthalene (996 kJ mol-1). The diazaboryl groups are oriented orthogonal to the pyridine ring and do not block the N-position, resembling the geometry of commonly used N-heterocyclic carbenes...
June 23, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28643406/prussian-blue-nanocubes-with-an-open-framework-structure-coated-with-pedot-as-high-capacity-cathodes-for-lithium-sulfur-batteries
#15
Dawei Su, Michael Cortie, Hongbo Fan, Guoxiu Wang
It is shown that Prussian blue analogues (PBAs) can be a very competitive sulfur host for lithium-sulfur (Li-S) batteries. Sulfur stored in the large interstitial sites of a PBA host can take advantage of reversible and efficient insertion/extraction of both Li(+) and electrons, due to the well-trapped mobile dielectron redox centers in the well-defined host. It is demonstrated that Na2 Fe[Fe(CN)6 ] has a large open framework, and as a cathode, it both stores sulfur and acts as a polysulfide diffusion inhibitor based on the Lewis acid-base bonding effect...
June 23, 2017: Advanced Materials
https://www.readbyqxmd.com/read/28643343/alpha-beta-hydrolases-a-unique-structural-motif-coordinates-catalytic-acid-residue-in-40-protein-fold-families
#16
Polytimi S Dimitriou, Alexander Denesyuk, Seiji Takahashi, Satoshi Yamashita, Mark S Johnson, Toru Nakayama, Konstantin Denessiouk
The alpha/beta-hydrolases (ABH) are a family of acid-base-nucleophile catalytic triad enzymes with a common fold, but using a wide variety of substrates, having different pH optima, catalyzing unique catalytic reactions and often showing improved chemical and thermo stability. The ABH enzymes are prime targets for protein engineering. Here, we have classified active sites from 51 representative members of 40 structural ABH fold families into eight distinct conserved geometries. We demonstrate the occurrence of a common structural motif, the catalytic acid zone, at the catalytic triad acid turn...
June 23, 2017: Proteins
https://www.readbyqxmd.com/read/28642768/silicon-transporters-and-effects-of-silicon-amendments-in-strawberry-under-high-tunnel-and-field-conditions
#17
Samuel Ouellette, Marie-Hélène Goyette, Caroline Labbé, Joan Laur, Linda Gaudreau, André Gosselin, Martine Dorais, Rupesh K Deshmukh, Richard R Bélanger
Together with longer production periods, the commercial transition to day-neutral strawberry (Fragaria × ananassa) varieties has favored the development of diseases such as powdery mildew (Podosphaera aphanis) that thrives in late summer-early fall. In an attempt to find alternative solutions to fungicides currently employed to curb the disease, we wanted to investigate the potential of silicon (Si) amendments that have been associated with prophylactic properties against powdery mildews. To this end, our first objective was to determine if strawberry was a Si-competent species following the recent characterization of the properties of Si transporters that plants must carry to uptake silicic acid...
2017: Frontiers in Plant Science
https://www.readbyqxmd.com/read/28642298/does-acid-base-equilibrium-correlate-with-remnant-liver-volume-during-stepwise-liver-resection
#18
Mohammad Golriz, Sepehr Abbasi, Parham Fathi, Ali Majlesara, Thorsten Brenner, Arianeb Mehrabi
Small for size and flow syndrome (SFSF) is one of the most challenging complications following extended hepatectomy (EH). After EH, hepatic artery flow decreases and portal vein flow increases per 100 gram remnant liver volume (RLV). This causes hypoxia followed by metabolic acidosis. A correlation between acidosis and post-hepatectomy liver failure has been postulated, but not studied systematically in a large animal model or clinical setting. In our study, we performed stepwise liver resections on nine pigs to defined SFSF limits as follows: step 1: segment II/III resection, step 2: segment IV resection, step 3: segment V/VIII resection (RLV: 75%, 50% and 25% respectively)...
June 22, 2017: American Journal of Physiology. Gastrointestinal and Liver Physiology
https://www.readbyqxmd.com/read/28642036/transcription-factor-decoy-technology-a-therapeutic-update
#19
REVIEW
Markus Hecker, Andreas H Wagner
Targeting transcription factors represents one possibility to interfere with a known activated regulatory pathway that promotes disease. Double-stranded transcription factor decoy (TFD) oligodeoxynucleotides (ODN) are therapeutic drug candidates, which are able to specifically target and neutralize key transcription factors involved in the pathogenesis of a given disease. These short double-stranded TFD molecules mimic the consensus DNA binding site of a specific transcription factor in the promoter region of its target genes...
June 19, 2017: Biochemical Pharmacology
https://www.readbyqxmd.com/read/28641834/establishment-and-molecular-modeling-study-of-maltodextrin-based-synergistic-enantioseparation-systems-with-two-new-hydroxy-acid-chiral-ionic-liquids-as-additives-in-capillary-electrophoresis
#20
Xuan Yang, Yingxiang Du, Zijie Feng, Zongran Liu, Jingtang Li
Discovering more superior performance of ionic liquids for the separation science has triggered increasing interest. In this work, two new Hydroxy acid-based chiral ionic liquids (CILs) (tertramethylammonium-d-pantothenate (TMA-d-PAN), tertramethylammonium-d-quinate (TMA-d-QUI)) were designed and first used as additives to establish the maltodextrin-based synergistic systems for enantioseparation in capillary electrophoresis (CE). Compared to traditional single maltodextrin chiral separation system, significantly improved separations of all tested drugs in the CIL/Maltodextrin synergistic systems were obtained...
June 2, 2017: Journal of Chromatography. A
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