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strong ion

Kevin Breslin, John Joseph Wade, KongFatt Wong-Lin, Jim Harkin, Bronac Flanagan, Harm Van Zalinge, Steve Hall, Matthew Walker, Alexei Verkhratsky, Liam McDaid
A biophysical model that captures molecular homeostatic control of ions at the perisynaptic cradle (PsC) is of fundamental importance for understanding the interplay between astroglial and neuronal compartments. In this paper, we develop a multi-compartmental mathematical model which proposes a novel mechanism whereby the flow of cations in thin processes is restricted due to negatively charged membrane lipids which result in the formation of deep potential wells near the dipole heads. These wells restrict the flow of cations to "hopping" between adjacent wells as they transverse the process, and this surface retention of cations will be shown to give rise to the formation of potassium (K+) and sodium (Na+) microdomains at the PsC...
May 18, 2018: PLoS Computational Biology
Aline Bernardes, Giulio D C D'Oliveira, Aneta Silezin, Mónika Kuzma, Szilárd Molnár, Caridad Noda Pérez, Pál Perjési
The stereochemistry of non-enzyme catalyzed nucleophilic addition of GSH to 4'-hydroxychalcone 1 and its bis-Mannich derivative 2 was investigated at different pH values (pH 3.2, 6.1, 7.4, and 8.0). The stereochemical outcome of the reactions was evaluated by HPLC-UV-Vis method. Under strongly acidic conditions (pH 3.2), an unexpected diastereoselective addition of GSH onto the bis-Mannich derivative 2 was observed. Such a selectivity could not be observed in the similar reaction of 2 with N-acetylcysteine...
May 18, 2018: Archiv der Pharmazie
Daniel Martín-Yerga, Alejandro Pérez-Junquera, María Begoña Gonzalez-Garcia, David Hernández-Santos, Pablo Fanjul-Bolado
Spectroelectrochemical techniques are becoming increasingly versatile tools to solve a diverse range of analytical problems. Herein, the use of in situ real-time luminescence spectroelectrochemistry to quantify chloride ions is demonstrated. Utilizing the bleaching effect of chlorine-based electrogenerated products after chloride oxidation, it is shown that the fluorescence of the Rhodamine 6G dye decrease proportionally to the initial chloride concentration in solution. A strong decrease of fluorescence is observed in acidic media compared to a lower decrease in alkaline media, which suggests that Cl2 , favourably generated at low pH, could be the main species responsible of the fluorescence loss...
May 18, 2018: Analytical Chemistry
Demelza Lyons, Reece Crocker, Thanh Vinh Nguyen
Tropylium ions possess an interesting combination of structural stability and chemical reactivity due to its Hückel-aromaticity and its positively charged polyene nature, respectively. Herein we exploit the chemical versatility and unique structural properties of the tropylium ion to derive a family of novel 'push-and-pull' organic dyes with strong absorption in the visible range via simple and practical synthetic protocols. These stable organic dyes are highly stimuli-responsive, as demonstrated by their sensitivity towards solvent, pH change, redox reaction, Lewis base and counterion, which marks them as potentially useful compounds for opto-electronic applications...
May 18, 2018: Chemistry: a European Journal
Yu-Qing Zhao, Qi-Rui Ma, Biao Liu, Zhuo-Liang Yu, Meng-Qiu Cai
Ab initio simulations combined with the Berry phase method are employed to investigate ferroelectric polarization of tetragonal CsPbBr3 crystals by applying hydrostatic pressure varying from 0 to 19 GPa; we find that the object research belongs to the P4mm space group. The calculated results show that the materials undergo a paraelectric-ferroelectric phase transition when the pressure increases to a critical value 15 GPa. The polarization is strongly enhanced and attains a high value of about 23 μC cm-2, owing to the increase in the ionic and electric contributions to the polarization under compressive strain...
May 18, 2018: Physical Chemistry Chemical Physics: PCCP
Y F Wang, Y C Shao, S H Hsieh, Y K Chang, P H Yeh, H C Hsueh, J W Chiou, H T Wang, S C Ray, H M Tsai, C W Pao, C H Chen, H J Lin, J F Lee, C T Wu, J J Wu, Y M Chang, K Asokan, K H Chae, T Ohigashi, Y Takagi, T Yokoyama, N Kosugi, W F Pong
Various synchrotron radiation-based spectroscopic and microscopic techniques are used to elucidate the room-temperature ferromagnetism of carbon-doped ZnO-nanowires (ZnO-C:NW) via a mild C+ ion implantation method. The photoluminescence and magnetic hysteresis loops reveal that the implantation of C reduces the number of intrinsic surface defects and increases the saturated magnetization of ZnO-NW. The interstitial implanted C ions constitute the majority of defects in ZnO-C:NW as confirmed by the X-ray absorption spectroscopic studies...
May 17, 2018: Scientific Reports
Irina V Zueva, Sofya V Lushchekina, Patrick Masson
The role of water in oxime-mediated reactivation of phosphylated cholinesterases has been asked with recurrence. To investigate oximate water structure changes in this reaction, reactivation of paraoxon-inhibited human acetylcholinesterase (AChE) was performed by the oxime HI-6 at different pH in the presence and absence of lyotropic salts: a neutral salt (NaCl), a strong chaotropic salt (LiSCN) and strong kosmotropic salts (ammonium sulfate and phosphate HPO4 2- ). At the same time, molecular dynamic simulations of enzyme reactivation under the same conditions were performed over 100 ns...
May 17, 2018: Bioscience Reports
Jiabao Niu, Jianquan Wang, Xiaofu Dai, Ziqiang Shao, Xiaonan Huang
To develop healable hydrogels with excellent mechanical properties is still a challenge topic. In this study, a novel class of physically crosslinked polyacrylamide based nanocomposite hydrogels reinforced with cellulose nanofibers (CNF) were fabricated using radical polymerization, followed by further strengthening through ferric ions via strong ionic coordination interactions between Fe3+ and carboxyls on CNF surfaces. Then the obtained gels were characterized by FTIR, tensile and compressive measurements as well as healing experiments...
August 1, 2018: Carbohydrate Polymers
Santu Maity, Nira Parshi, Chandraday Prodhan, Keya Chaudhuri, Jhuma Ganguly
A three-dimensional fluorescent hydrogel based on chitosan, polyvinyl alcohol and 9-anthraldehyde (ChPA) has been successfully designed and synthesized for the selective detection and discrimination of Fe3+ and Fe2+ in aqueous environment. The unique characteristics of ChPA has been confirmed by the Fourier-transform infrared spectroscopy (FTIR), rheological measurement, scanning electron microscopy (SEM), thermogravimetry and differential thermogravimetry (TG-DTG), ultraviolet-visible spectroscopy (UV-vis), fluorescence studies, transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy (EDX), x-ray diffraction (XRD) and dynamic light scattering (DLS)...
August 1, 2018: Carbohydrate Polymers
Shuo Yang, Dirk Oliver Schmidt, Abhishek Khetan, Felix Schrader, Simon Jakobi, Melanie Homberger, Michael Noyong, Anja Paulus, Hans Kungl, Rüdiger-Albert Eichel, Heinz Pitsch, Ulrich Simon
LiNi0.5 Mn1.5 O₄ (LNMO) spinel has been extensively investigated as one of the most promising high-voltage cathode candidates for lithium-ion batteries. The electrochemical performance of LNMO, especially its rate performance, seems to be governed by its crystallographic structure, which is strongly influenced by the preparation methods. Conventionally, LNMO materials are prepared via solid-state reactions, which typically lead to microscaled particles with only limited control over the particle size and morphology...
May 16, 2018: Materials
Francesca E Ciraldo, Elena Boccardi, Virginia Melli, Fabian Westhauser, Aldo R Boccaccini
Bioactive glasses (BGs) are being increasingly considered for biomedical applications in bone and soft tissue replacement approaches thanks to their ability to form strong bonding with tissues. However, due to their high reactivity once in contact with water-based solutions BGs rapidly exchange ions with the surrounding environment leading in most cases to an undesired increase of the pH under static in vitro conditions (due to alkaline ion "burst release"), making difficult or even impossible to perform cell culture studies...
May 14, 2018: Acta Biomaterialia
Maria Timofeeva, Lukas Lang, Flavia Timpu, Claude Renaut, Alexei Bouravleuv, Igor V Shtrom, George Cirlin, Rachel Grange
Nonradiating electromagnetic configurations in nanostructures open new horizons for applications due to two essential features: lack of energy losses and invisibility to the propagating electromagnetic field. Such radiationless configurations form a basis for new types of nanophotonic devices, where a strong electromagnetic field confinement can be achieved together with lossless interactions between nearby components. In our work, we present a new design of free-standing disk nanoantennas with nonradiating current distributions for the optical near-infrared range...
May 17, 2018: Nano Letters
Penghui Shi, Yan Zhang, Yuhua Li, Liujiao Bian
Both the molecular recognition and interaction of metallo-β-lactamase CcrA with l-captopril were studied by the combined use of fluorescence spectra and molecular dynamic simulation. The results showed that the binding constant was 8.89 × 104  L mol-1 at 296 K. Both Zn1 and Zn2 displayed tetrahedral coordination geometries in the CcrA-Lcap complex, the S atom in l-captopril displaced the nucleophilic hydroxide in apo CcrA and occupied the fourth coordination site for each ion, resulting in a competitively inhibited CcrA enzyme...
May 17, 2018: Luminescence: the Journal of Biological and Chemical Luminescence
Bin Gao, Julie Dalziel, Simone Tanzi, Shunyi Zhu
Besides key roles in prey capture and predator defense, scorpion venom also functions as internal immune agents protecting the venom gland from infection and external immune agents cleaning saprophytic microbes from their own body surfaces. However, antimicrobials (typically antimicrobial peptides, AMPs) in the venom often exist in low abundance that might exclude their immune role alone, leaving an open question with regard to their in vivo biological function. Here, we report the bactericidal activity of seven peptides isolated from the scorpion Mesobuthus eupeus venom, including one classical α-helical AMP and five ion channel-targeted neurotoxins...
May 16, 2018: Amino Acids
Alexey S Berezin, Denis G Samsonenko, Valery K Brel, Alexander V Artem'ev
Unprecedented organic-inorganic hybrid complexes, [Mn(L)3]MnHal4, containing both four- and hexacoordinated Mn2+ ions were synthesized by reacting MnCl2 or MnBr2 with bis(phosphine oxide) ligands (L) such as dppmO2, dppeO2, and 2,3-bis(diphenylphosphinyl)-1,3-butadiene (dppbO2). In the [Mn(L)3]2+ cation of the complexes, the Mn2+ ion features a [MnO6] octahedral coordination environment (Oh), and the [MnHal4]2- anion adopts a tetrahedral geometry (Td). These "two-in-one" complexes exhibit strong long-lived luminescence (τav = 12-15 ms at 300 K) having interesting thermochromic behavior attributed to the thermal equilibrium between two emission bands...
May 17, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Soo Hyeon Lim, Youmie Park
Green strategies to synthesize gold nanoparticles have attracted a substantial amount of attention because global sustainability is a focal issue in many research areas. In the present study, rosmarinic acid was utilized as a reducing agent to reduce gold ions to gold nanoparticles. The characteristic surface plasmon resonance of gold nanoparticles was observed at 532 nm with a pink-colored colloidal solution. High-resolution transmission electron microscopy (HR-TEM) revealed the presence of spherical nanoparticles along with triangular nanoplates...
January 1, 2018: Journal of Nanoscience and Nanotechnology
Yu-Cheng Liu, Nae-Lih Wu, Wei-Ren Liu
Li-rich layered cathode materials, Li1.2Ni0.4-xAlxMn0.6O2.2-y Cly (0 ≤ x ≤ 0.03 and 0 ≤ y ≤ 0.03), were successfully synthesized through coprecipitation, and the effects of Al3+-Cl- co-substitution on their surface morphology, crystal structure, surface chemistry, and electrochemical performance were characterized through XRD, SEM, XPS, TEM, and electrochemical and charge-discharge cycling. Doping the cathodes with Al3+ and Cl- ions enhanced electrochemical performance at room temperature and at a high working temperature of 55 °C...
January 1, 2018: Journal of Nanoscience and Nanotechnology
Anna Reuß, Vadim Ksenofontov, Joshua Tapp, Dirk Wulferding, Peter Lemmens, Martin Panthöfer, Angela Möller
BaNa2 Fe[VO4 ]2 contains a Jahn-Teller active ion (FeII , 3d6 , high-spin) in an octahedral coordination. On the basis of a combination of temperature-dependent X-ray diffraction and Mössbauer and Raman spectroscopies, we demonstrate the coupling of lattice dynamics with the electronic ground state of FeII . We identify three lattice modes combined to an effective canted screw- type motion that drives the structural transition around room temperature from the high-temperature ( P3̅) via intermediate phases to the low-temperature phase ( C2/ c)...
May 16, 2018: Inorganic Chemistry
Mohammed Jaoui, Michael Lewandowski, John H Offenberg, Maribel Colon, Kenneth S Docherty, Tadeusz E Kleindienst
The analytical capabilities associated with the use of silylation reactions have been extended to a new class of organic molecules, nitroaromatic compounds (NACs). These compounds are a possible contributor to urban particulate matter of secondary origin which would make them important analytes due to their (1) detrimental health effects, (2) potential to affect aerosol optical properties, (3) and usefulness for identifying PM2.5 from biomass burning. The technique is based on derivatization of the parent NACs using N,O-bis-(trimethylsilyl)-trifluoro acetamide, one of the most prevalent derivatization reagent for analyzing hydroxylated molecules, followed by GC-MS using electron ionization (EI) and methane chemical ionization (CI)...
May 15, 2018: Journal of Mass Spectrometry: JMS
Van-Chien Bui, Thi-Huong Nguyen
Cations-induced DNA aggregation can modify the local structure of oligonucleotides and has potential applications in medicine and biotechnology. Here, we used atomic force microscopy to investigate λ-DNA aggregation on Mg2+ -treated glass (Mg2+ /glass) and in Mg2+ solution. Atomic force microscopy topography images showed that some DNA fragments were slightly stacked together on 10 mM Mg2+ /glass and stacked stronger on ≥50 mM Mg2+ /glass. They also showed that DNA aggregated stronger in Mg2+ solution than on Mg2+ /glass, ie, DNAs are strongly stacked and twisted at 10 mM Mg2+ , rolled together at 50 mM Mg2+ , and slightly aggregated to form small particles at 100 mM Mg2+ ...
May 15, 2018: Journal of Molecular Recognition: JMR
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