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https://www.readbyqxmd.com/read/29457972/a-stable-metal-organic-framework-featuring-local-buffer-environment-for-carbon-dioxide-fixation
#1
Hongming He, Qi Sun, Wenyang Gao, Jason A Perman, Fuxing Sun, Guangshan Zhu, Briana Aguila, Katherine Forrest, Brian Space, Shengqian Ma
A majority of metal-organic frameworks (MOFs) fail to preserve their physical and chemical properties after exposure to acidic, neutral, or alkaline aqueous solutions, therefore limiting their practical applications in many areas. The strategy demonstrated herein is the design and synthesis of an organic ligand that behaves as a buffer to drastically boost the aqueous stability of a porous MOF (JUC-1000), which maintains its structural integrity at low and high pH values. The local buffer environment resulting from the weak acid-base pairs of the custom-designed organic ligand also greatly facilitates the performance of JUC-1000 in the chemical fixation of carbon dioxide under ambient conditions, outperforming a series of benchmark catalysts...
February 19, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/29455092/internet-pseudoscience-testing-opioid-containing-formulations-with-tampering-potential
#2
Jennifer P Pascali, Paolo Fais, Fabio Vaiano, Nicola Pigaiani, Stefano D'Errico, Sandra Furlanetto, Diego Palumbo, Elisabetta Bertol
Drug tampering practices, with the aim to increase availability of drug delivery and/or enhance drug effects, are accessible on Internet and are practiced by some portion of recreational drug users. Not rarely, recreational misuse may result in toxic and even fatal results. The aim of the present study was to assess the tampering risk of medicaments containing different formulations of an opioid in combination with paracetamol or dexketoprofen, following the procedures reported in dedicated forums on the web...
February 10, 2018: Journal of Pharmaceutical and Biomedical Analysis
https://www.readbyqxmd.com/read/29453414/chemisorption-of-polysulfides-through-redox-reactions-with-organic-molecules-for-lithium-sulfur-batteries
#3
Ge Li, Xiaolei Wang, Min Ho Seo, Matthew Li, Lu Ma, Yifei Yuan, Tianpin Wu, Aiping Yu, Shun Wang, Jun Lu, Zhongwei Chen
Lithium-sulfur battery possesses high energy density but suffers from severe capacity fading due to the dissolution of lithium polysulfides. Novel design and mechanisms to encapsulate lithium polysulfides are greatly desired by high-performance lithium-sulfur batteries towards practical applications. Herein, we report a strategy of utilizing anthraquinone, a natural abundant organic molecule, to suppress dissolution and diffusion of polysulfides species through redox reactions during cycling. The keto groups of anthraquinone play a critical role in forming strong Lewis acid-based chemical bonding...
February 16, 2018: Nature Communications
https://www.readbyqxmd.com/read/29453105/highly-efficient-and-selective-removal-of-n-heterocyclic-aromatic-contaminants-from-liquid-fuels-in-a-ag-i-functionalized-metal-organic-framework-contribution-of-multiple-interaction-sites
#4
Haiying She, Xiaochen Ma, Ganggang Chang
An adsorbent with multiple interaction sites for the adsorption of nitrogen-containing compounds (NCCs) has been realized in a silver ion functionalized Cr 3+ based metal-organic framework (Cr)-MIL-101-SO 3 Ag. The adsorptive denitrogenation performance of (Cr)-MIL-101-SO 3 Ag was evaluated in a batch adsorption system in terms of both its adsorption capacity and selectivity, of which, quinoline and indole were selected as representative organonitrogen contaminants in liquid fuels. (Cr)-MIL-101-SO 3 Ag could interact with NCCs through multiple ways simultaneously, which exhibited about 50% higher adsorption capacity compared to (Cr)-MIL-101-SO 3 H, and a still high level of adsorption amount could be remained even in a model fuel where toluene (15% v) was added as a co-solvent and benzothiophene (BT) was added as a competitive adsorbate...
February 2, 2018: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/29451728/phosphinic-acid-based-linkers-new-building-block-in-mof-chemistry
#5
Jan Hynek, Petr Brázda, Jan Rohlíček, Michael G S Londesborough, Jan Demel
Metal-organic frameworks (MOFs) are a chemically and topologically diverse family of materials composed of inorganic nodes and organic linkers bound together by coordination bonds. In this contribution we present two significant innovations in this field. The first is the use of a new coordination group in phenylene-1,4-bis(methylphosphinic acid) (PBPA), a phosphinic acid analogue of commonly-used terephtalic acid. We show that the use of this new linker group leads to the formation of a hydrothermally stable permanently porous MOF structure...
February 16, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/29450805/ph-responsive-cap-co-poly-methacrylic-acid-based-hydrogel-as-an-efficient-platform-for-controlled-gastrointestinal-delivery-fabrication-characterization-in-vitro-and-in-vivo-toxicity-evaluation
#6
Syed Ahmed Shah, Muhammad Sohail, Muhammad Usman Minhas, Nisar-Ur-Rehman, Shahzeb Khan, Zahid Hussain, Mudassir, Arshad Mahmood, Mubeen Kousar, Asif Mahmood
Cellulose acetate phthalate-based pH-responsive hydrogel was synthesized for fabrication of polymeric matrix tablets for gastro-protective delivery of loxoprofen sodium. Cellulose acetate phthalate (CAP) was cross-linked with methacrylic acid (MAA) using free radical polymerization technique. Fourier transform infrared (FTIR) spectra confirmed the formation of cross-linked structure of CAP-co-poly(methacrylic acid). Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) confirmed the thermal stability of polymeric networks, and scanning electron microscopy (SEM) and energy-dispersive X-ray spectrum (EDS) images unveiled that the prepared formulations were porous in nature and thus the developed formulations had shown better diffusibility...
February 15, 2018: Drug Delivery and Translational Research
https://www.readbyqxmd.com/read/29450666/recent-advances-in-hyaluronic-acid-based-therapy-for-osteoarthritis
#7
REVIEW
Steven Bowman, Mohamed E Awad, Mark W Hamrick, Monte Hunter, Sadanand Fulzele
Osteoarthritis is a debilitating disease that has increased in prevalence across the world due to the aging population. Currently, physicians use a plethora of treatment strategies to try and slow down the progression of the disease, but none have been shown to ubiquitously treat and cure the disease. One of the strategies uses the high molecular weight molecule hyaluronic acid as either an injectable or oral supplement for treatment. Hyaluronic acid (HA) is a relatively new treatment that has shown varied results through several clinical trials...
February 16, 2018: Clinical and Translational Medicine
https://www.readbyqxmd.com/read/29442773/boehmite-an-efficient-and-recyclable-acid-base-bifunctional-catalyst-for-aldol-condensation-reaction
#8
P C Rajan Reshma, Sekar Vikneshvaran, Sivan Velmathi
In this work boehmite was used as an acid-base bifunctional catalyst for aldol condensation reactions of aromatic aldehydes and ketones. The catalyst was prepared by simple sol-gel method using Al(NO3)3·9H2O and NH4OH as precursors. The catalyst has been characterized by X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM), UV-visible spectroscopy (DRS), BET surface area analyses. Boehmite is successfully applied as catalyst for the condensation reaction between 4-nitrobenzaldehyde and acetone as a model substrate giving α, β-unsaturated ketones without any side product...
June 1, 2018: Journal of Nanoscience and Nanotechnology
https://www.readbyqxmd.com/read/29442497/electrospun-poly-lactic-acid-based-fibrous-nanocomposite-reinforced-by-cellulose-nanocrystals-impact-of-fiber-uniaxial-alignment-on-microstructure-and-mechanical-properties
#9
Siqi Huan, Guoxiang Liu, Guangping Han, Long Bai
Uniform PLA/CNC nanofibrous mats composed of either random or aligned fibers reinforced with up to 20 wt% cellulose nanocrystals (CNCs) were successfully produced by two different electrospinning processes. Various concentrations of CNCs could be stably dispersed in PLA solution prior to nanofiber manufacture. The microstructure of produced fibrous mats, regardless of random or aligned orientation, was transformed from smooth to nanoporous surface by changing CNC loading levels. Aligning process through secondary stretching during high-speed collecting can also affect the porous structure of fibers...
February 14, 2018: Biomacromolecules
https://www.readbyqxmd.com/read/29442224/vitamin-c-and-sodium-bicarbonate-enhance-the-antioxidant-ability-of-h9c2-cells-and-induce-hsps-to-relieve-heat-stress
#10
Bin Yin, Shu Tang, Jiarui Sun, Xiaohui Zhang, Jiao Xu, Liangjiao Di, Zhihong Li, Yurong Hu, Endong Bao
Heat stress is exacerbated by global warming and affects human and animal health, leading to heart damage caused by imbalances in reactive oxygen species (ROS) and the antioxidant system, acid-base chemistry, electrolytes and respiratory alkalosis. Vitamin C scavenges excess ROS, and sodium bicarbonate maintains acid-base and electrolyte balance, and alleviates respiratory alkalosis. Herein, we explored the ability of vitamin C alone and in combination with equimolar sodium bicarbonate (Vitamin C-Na) to stimulate endogenous antioxidants and heat shock proteins (HSPs) to relieve heat stress in H9C2 cells...
February 13, 2018: Cell Stress & Chaperones
https://www.readbyqxmd.com/read/29442018/a-new-model-to-determine-lipophilicity-of-1-2-ethanediamine-n-n-di-2-3-cyclohexyl-propanoic-acid-and-1-3-propanediamine-n-n-di-2-3-cyclohexyl-propanoic-acid-derivatives-with-antiproliferative-activity-by-combining-shake-flask-procedure-and-uhplc-ms-method
#11
B Tubić, B Marković, S Vladimirov, S Savić, J Poljarević, T Sabo
Fourteen compounds representing ester derivatives of (S,S)-1,2-ethanediamine-N,N'-di-2-(3-cyclohexyl) propanoic and (S,S)-1,3-propanediamine-N,N'-di-2-(3-cyclohexyl)propanoic acids, expressing antiproliferative activity in vitro were examined. The objective of this study was to determinate their lipophilicity data, and also to ensure a mathematical model for prediction lipophilicity data of potential in vivo metabolites and new derivatives of (S,S)-1,2-ethanediamine-N,N'-di-2-(3-cyclohexyl)propanoic acid, based on chromatographic parameters...
June 1, 2017: Die Pharmazie
https://www.readbyqxmd.com/read/29437283/dynamic-kinetic-resolution-of-heterobiaryl-ketones-via-zn-catalyzed-asymmetric-hydrosilylation
#12
José M Lassaletta, Valentín Hornillos, Jose Alberto Carmona, Abel Ros, Javier Iglesias-Sigüenza, Rosario Fernández, Joaquín López-Serrano
A diastereo and highly enantioselective dynamic kinetic resolution (DKR) of configurationally labile heterobiaryl ketones is described. The DKR proceeds by zinc-catalyzed hydrosilylation of the carbonyl group, leading to secondary alcohols bearing axial and central chirality. The strategy relies on the labilization of the stereogenic axis that takes place thanks to a Lewis acid-base interaction between a nitrogen atom in the heterocycle and the ketone carbonyl. The synthetic utility of the methodology is demonstrated through racemization-free, stereospecific transformations into N,N-ligands or appealing axially chiral, bifunctional thiourea organocatalysts...
February 13, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/29436821/ph-sensitive-compounds-for-selective-inhibition-of-acid-producing-bacteria
#13
Yin Yang, Vytas Reipa, Guo Liu, Yuan Meng, Xiaohong Wang, Kenneth P Mineart, Vivek M Prabhu, Wenyuan Shi, Nancy J Lin, Xuesong He, Jirun Sun
Stimuli-responsive compounds that provide on-site, controlled antimicrobial activity promise an effective approach to prevent infections, reducing the need for systemic antibiotics. We present one novel pH-sensitive quaternary pyridinium salt (QPS) whose antibacterial activity is boosted by low pH and controlled by adjusting the pH between 4 and 8. Particularly, this compound selectively inhibits growth of acid-producing bacteria within a multispecies community. The successful antibacterial action of this QPS maintains the environmental pH above 5...
February 13, 2018: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29435780/protein-ligand-interfaces-are-polarized-discovery-of-a-strong-trend-for-intermolecular-hydrogen-bonds-to-favor-donors-on-the-protein-side-with-implications-for-predicting-and-designing-ligand-complexes
#14
Sebastian Raschka, Alex J Wolf, Joseph Bemister-Buffington, Leslie A Kuhn
Understanding how proteins encode ligand specificity is fascinating and similar in importance to deciphering the genetic code. For protein-ligand recognition, the combination of an almost infinite variety of interfacial shapes and patterns of chemical groups makes the problem especially challenging. Here we analyze data across non-homologous proteins in complex with small biological ligands to address observations made in our inhibitor discovery projects: that proteins favor donating H-bonds to ligands and avoid using groups with both H-bond donor and acceptor capacity...
February 12, 2018: Journal of Computer-aided Molecular Design
https://www.readbyqxmd.com/read/29435283/targeted-immunotherapy-of-high-grade-cervical-intra-epithelial-neoplasia-expectations-from-clinical-trials
#15
Jean-Luc Brun, José Rajaonarison, Nicolas Nocart, Laura Hoarau, Stéphanie Brun, Isabelle Garrigue
Targeted immunotherapy of high-grade cervical intra-epithelial neoplasia (CIN) has been developed as an alternative to conization, to preserve future reproductive outcomes and avoid human papillomavirus (HPV) persistence. The objectives of the review are to present drugs according to their process of development and to examine their potential future use. A search for key words associated with CIN and targeted immunotherapy was carried out in the Cochrane library, Pubmed, Embase, and ClinicalTrials.gov from 1990 to 2016...
February 2018: Molecular and Clinical Oncology
https://www.readbyqxmd.com/read/29434114/droplet-counting-microtitration-system-for-precise-on-site-analysis
#16
Susumu Kawakubo, Taichi Omori, Yasutada Suzuki, Ikuo Ueta
A new microtitration system based on the counting of titrant droplets has been developed for precise on-site analysis. The dropping rate was controlled by inserting a capillary tube as a flow resistance in a laboratory-made micropipette. The error of titration was 3% in a simulated titration with 20 droplets. The pre-addition of a titrant was proposed for precise titration within an error of 0.5%. The analytical performances were evaluated for chelate titration, redox titration and acid-base titration.
2018: Analytical Sciences: the International Journal of the Japan Society for Analytical Chemistry
https://www.readbyqxmd.com/read/29433310/quantifying-the-average-number-of-nucleic-acid-therapeutics-per-nanocarrier-by-single-particle-tracking-microscopy
#17
Elisa Zagato, Lotte Vermeulen, Heleen Dewitte, Griet Van Imschoot, Roosmarijn E Vandenbroucke, Jo Demeester, Stefaan C De Schmedt, Kristiaan Neyts, Katrien Remaut, Kevin Braeckmans
Nucleic acid biopharmaceuticals are being investigated as potential therapeutics. They need to be incorporated into a bio-compatible carrier so as to overcome several biological barriers. Rational development of suitable nanocarriers requires high quality characterization techniques. While size, concentration and stability can be very well measured these days, even in complex biological fluids, a method to accurately quantify the number of nucleic acid therapeutics encapsulated in nanocarriers is still missing...
February 12, 2018: Molecular Pharmaceutics
https://www.readbyqxmd.com/read/29432695/single-step-in-situ-assembling-routes-for-the-shape-control-of-polymer-nanoparticles
#18
Nikunjkumar R Visaveliya, J Michael Köhler
Controlling shapes of polymer nanoparticles via single-step process is a challenge due to their amorphous chemical nature. Precise regulation of interfacial interactions, electrical charging and reaction dynamics during ongoing polymerization process provides an environment where uniform nucleation, growth and in-situ assembling can be realized, and hence nanoparticles of complex shapes can be obtained. In this work, it is investigated how in-situ assembling of the growing nanoparticles succeeds and specifically in different manners by using cationic, anionic, poly-ionic, and non-ionic surface-active agents in a time-dependent blended form...
February 12, 2018: Biomacromolecules
https://www.readbyqxmd.com/read/29431998/mechanism-and-rate-determining-factors-of-amide-bond-formation-through-acyl-transfer-of-mixed-carboxylic-carbamic-anhydrides-a-computational-study
#19
Yuan-Ye Jiang, Tian-Tian Liu, Rui-Xue Zhang, Zhong-Yan Xu, Xue Sun, Siwei Bi
Acyl transfer of in-situ generated mixed anhydrides is an important method for the amide bond formation from short linkages with the easily-removed by-product CO2. To enrich the understanding of the inherently-difficult acyl transfer hindered by the large ring strain, a density functional theory (DFT) study was performed herein. The calculations indicate that the amidation of activated -aminoesters and N-protected amino acids is more likely to proceed via the self-catalytic nucleophilic substitution of the two substrates and the subsequent 1,3-acyl transfer...
February 12, 2018: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29431825/unequal-coordination-environment-in-complexes-of-the-type-au2ag2-r-4-l-2-n-an-immiscible-solvent-mixture-as-a-key-point-in-the-control-of-ligand-replacement
#20
José M López-de-Luzuriaga, Miguel Monge, M Elena Olmos, Javier Quintana, María Rodríguez-Castillo
Following an acid-base strategy, based on the reaction between gold(i) basic fragments and acid silver salts, it is possible to obtain heterometallic polymers of the general formula [Au2Ag2(R)4(L)2]n (R = C6Cl2F3; L = pyrimidine). Using this new heterometallic complex [Au2Ag2(C6Cl2F3)4(pym)2]n (1) as a starting material, and a good coordinating solvent such as acetonitrile, it is possible to modify the arrangement of the ligands connected to the silver centres and to obtain three different tetranuclear Au2Ag2 building blocks leading to the new polymer [Au6Ag6(C6Cl2F3)12(μ2-pym)2(NCMe)6]n (2)...
February 12, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
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