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161.
Jazer Jose H. Togonon Eugene A. Esparcia Jr. Prof. Julie Anne D. del Rosario Prof. Joey D. Ocon 《ChemistryOpen》2021,10(4):471-476
Biodegradable primary batteries, also known as transient batteries, are essential to realize autonomous biodegradable electronic devices with high performance and advanced functionality. In this work, magnesium, copper, iron, and zinc – metals that exist as trace elements in the human body – were tested as materials for biomedical transient electronic devices. Different full cell combinations of Mg and X (where X = Cu, Fe, and Zn and the anodized form of the metals) with phosphate buffered saline (PBS) as electrolyte were studied. To form the cathodes, metal foils were anodized galvanostatically at a current density of 2.0 mA cm−2 for 30 mins. Electrochemical measurements were then conducted for each electrode combination to evaluate full cell battery performance. Results showed that the Mg−Cuanodized chemistry has the highest power density at 0.99 mW/cm2. Nominal operating voltages of 1.26 V for the first 0.50 h and 0.63 V for the next 3.7 h were observed for Mg−Cuanodized which was discharged at a current density of 0.70 mA cm−2. Among the materials tested, Mg−Cuanodized exhibited the best discharge performance with an average specific capacity of 2.94 mAh cm−2, which is comparable to previous reports on transient batteries. 相似文献
162.
Dr. Andreas A. Bastian Dr. Maria Bastian Dr. Manuel Jäger Mark Loznik Dr. Eliza M. Warszawik Xintong Yang Dr. Nabil Tahiri Dr. Peter Fodran Prof. Dr. Martin D. Witte Anne Thoma Dr. Jens Köhler Prof. Dr. Adriaan J. Minnaard Prof. Dr. Andreas Herrmann 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(36):e202200883
The continuous emergence of antimicrobial resistance is causing a threat to patients infected by multidrug-resistant pathogens. In particular, the clinical use of aminoglycoside antibiotics, broad-spectrum antibacterials of last resort, is limited due to rising bacterial resistance. One of the major resistance mechanisms in Gram-positive and Gram-negative bacteria is phosphorylation of these amino sugars at the 3’-position by O-phosphotransferases [APH(3’)s]. Structural alteration of these antibiotics at the 3’-position would be an obvious strategy to tackle this resistance mechanism. However, the access to such derivatives requires cumbersome multi-step synthesis, which is not appealing for pharma industry in this low-return-on-investment market. To overcome this obstacle and combat bacterial resistance mediated by APH(3’)s, we introduce a novel regioselective modification of aminoglycosides in the 3’-position via palladium-catalyzed oxidation. To underline the effectiveness of our method for structural modification of aminoglycosides, we have developed two novel antibiotic candidates overcoming APH(3’)s-mediated resistance employing only four synthetic steps. 相似文献
163.
Large Zero‐Field Splittings of the Ground Spin State Arising from Antisymmetric Exchange Effects in Heterometallic Triangles 下载免费PDF全文
Samantha A. Magee Dr. Stephen Sproules Dr. Anne‐Laure Barra Dr. Grigore A. Timco Nicholas F. Chilton Prof. David Collison Prof. Richard E. P. Winpenny Prof. Eric J. L. McInnes 《Angewandte Chemie (International ed. in English)》2014,53(21):5310-5313
[Ru2Mn(O)(O2CtBu)6(py)3] has an S=5/2 ground state with a very large zero‐field splitting (ZFS) of D=2.9 cm?1, as characterized by EPR spectroscopy at 4–330 GHz. This is far too large to be due to the MnII ion (D <0.2 cm?1), as shown from the {Fe2Mn} analogue, but can be modeled by antisymmetric exchange effects. 相似文献
164.
Jacobsen AM Halling-Sørensen B Ingerslev F Hansen SH 《Journal of chromatography. A》2004,1038(1-2):157-170
The veterinary antibacterial agents chlortetracycline (CTC), oxytetracycline (OTC), sulfadiazine (SDZ), erythromycin (ERY) and tylosin (TYL A, B, C and D) were extracted from soil using pressurized liquid extraction (PLE). Citric acid (pH 4.7) and methanol was used as extraction buffer, followed by tandem-solid-phase extraction (SPE) clean-up (SAX + HLB) for all compounds. For quantification two slightly different methods were employed using LC-MS-MS with MRM detection. The soil extraction method was validated using a loamy sand soil and a sandy soil, representing two typical Danish agricultural soils. Recoveries were 50-80% for the tetracyclines (CTC and OTC) and sulfadiazine (SDZ) and 60-100% for the macrolides (TYL and ERY). Limits of detection for the soil extraction method (LOD(soil)) were 0.6-5.6 microg kg(-1) soil for CTC and OTC, 0.9-2.9 microg kg(-1) soil for SDZ and 2.4-5.5 microg kg(-1) soil for TYL A and ERY. Furthermore, the method was applied to field samples taken from two agricultural fields fertilised with liquid manure containing CTC and TYL A. These results showed a decline in the content of antibacterial agents throughout the sampling period of 155 days from 10 to 15 microg CTC kg(-1) soil and 20-55 microg TYL A kg(-1) soil to below or near the LOD(soil) listed above. Finally, the method was applied to barley grains harvested from the fields. None of the antibacterial agents were measured in grain samples, but recoveries for spiked grain samples were similar to soil recoveries. 相似文献
165.
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167.
Ariana O. Hall Se Ryeon Lee Andrea N. Bootsma Jacob W. G. Bloom Steven E. Wheeler Anne J. McNeil 《Journal of polymer science. Part A, Polymer chemistry》2017,55(9):1530-1535
Synthesizing conjugated polymers via catalyst‐transfer polymerization (CTP) has led to unprecedented control over polymer sequence and molecular weight. Yet many challenges remain, including broadening the monomer scope and narrowing the molecular weight dispersities. Broad polymer dispersities can arise from nonliving pathways as well as slow initiation. Previously, slow initiation was observed in Ni‐mediated CTP of phenylene monomers. Although precatalysts with faster initiation rates have been reported, the rates still do not exceed propagation. Herein a second‐ and third‐generation of reactive ligands are described, along with a simple method for measuring initiation rates. A precatalyst with an initiation rate that exceeds propagation is now reported, however, the resulting polymer samples still exhibit broad dispersities, suggesting that slow initiation is not the most significant contributing factor in Ni‐mediated phenylene polymerizations. In addition, initiation rates measured under authentic polymerization conditions revealed that both exogenous triphenylphosphine and an ortho‐trifluoroethoxy substituent on the reactive ligand have a strong influence. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 1530–1535 相似文献
168.
Airborne microand nanoparticles-aerosols-play an important role in many natural phenomena and in a variety of industrial processes,as well as the public health issue. They may be of natural or anthropogenic origin;their presence in an environment might be intentional or due to undesirable release. In any case,merely the particle detection and characterization,ideally in real-time,provide an insight into the potential burden allowing also controlling and abatement measures. Due to the broad size range it is ... 相似文献
169.
Sébastien Redon Anne Roly Obah Kosso Julie Broggi Patrice Vanelle 《Tetrahedron letters》2017,58(28):2771-2773
The regioselective selenocyanation of imidazoheterocycles using triselenodicyanide at room temperature is reported. The electrophilic aromatic substitution of a broad range of substrates is promoted by the triselenodicyanide obtained by oxidative coupling of malononitrile and selenium dioxide, under an air atmosphere. The major advantages of the presented method are an easy set-up, excellent yields, short reaction times, use of odorless and inexpensive reagents and easy purification of the final products. 相似文献
170.