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https://www.readbyqxmd.com/read/29155787/synthesis-of-core-shell-lanthanide-doped-upconversion-nanocrystals-for-cellular-applications
#1
Xiangzhao Ai, Linna Lyu, Jing Mu, Ming Hu, Zhimin Wang, Bengang Xing
Lanthanide-doped upconversion nanocrystals (UCNs) have attracted much attention in recent years based on their promising and controllable optical properties, which allow for the absorption of near-infrared (NIR) light and can subsequently convert it into multiplexed emissions that span over a broad range of regions from the UV to the visible to the NIR. This article presents detailed experimental procedures for high-temperature co-precipitation synthesis of core-shell UCNs that incorporate different lanthanide ions into nanocrystals for efficiently converting deep-tissue penetrable NIR excitation (808 nm) into a strong blue emission at 480 nm...
November 10, 2017: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/29155589/the-reaction-mechanism-of-isopentenyl-phosphate-kinase-a-qm-mm-study
#2
James McClory, David J Timson, Warispreet Singh, Jian Zhang, Meilan Huang
Isopentenyl phosphate kinase (IPK) catalyzes the Mg2+-ATP dependent phosphorylation reactions to produce isopentenyl diphosphate, an important precursor in the synthesis of isopentenols. However, the position of the divalent metal ion in the crystal structures of IPK in complex with ATP and its native substrate IP has not been definitively resolved, and as a result ambiguity surrounds the catalytic mechanism of IP, limiting its exploitation as a biofuel and in drug design. Here we report the conformational change caused by substrate binding and the catalytically competent structure in complex with the metal ion Mg2+ using molecular dynamic simulations and density functional theory-based quantum mechanics/molecular mechanics calculations (B97d/AMBER99)...
November 20, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/29155417/growth-of-rutile-tio2-nanorods-in-ti-and-cu-ion-sequentially-implanted-sio2-and-the-involved-mechanisms
#3
Xiaoyu Mu, Xiaoyu Liu, Xiaohu Wang, Hai Tao Dai, Changlong Liu
TiO2 in nanoscale exhibits unique physicochemical and optoelectronic properties and has attracted much more interest of the researchers. In this work, TiO2 nanostructures are synthesized in amorphous SiO2 slices by implanting Ti ions, or sequentially implanting Ti and Cu ions combined with annealing at high temperature. The morphology, structure, spatial distribution and optical properties of the formed nanostructures have been investigated in detail. Our results clearly show that the thermal growth of TiO2 nanostructures in SiO2 substrate is significantly enhanced by presence of post Cu ion implantation, which depends strongly on the applied Cu ion fluence, as well as the annealing atmosphere...
November 20, 2017: Nanotechnology
https://www.readbyqxmd.com/read/29154952/in-vitro-mechanisms-of-beauvericin-toxicity-a-review
#4
REVIEW
Beatriz Mallebrera, Alessandra Prosperini, Guillermina Font, Maria-Jose Ruiz
Beauvericin (BEA) is a mycotoxin produced by many species of fungus Fusarium and by Beauveria bassiana; BEA is a natural contaminant of cereals and cereals based products and possesses a wide variety of biological properties. The mechanism of action seems to be related to its ionophoric activity, that increases ion permeability in biological membranes. As a consequence, BEA causes cytotoxicity in several cell lines and is capable to produce oxidative stress at molecular level. Moreover, BEA is genotoxic (produces DNA fragmentation, chromosomal aberrations and micronucleus) and causes apoptosis with the involvement of mitochondrial pathway...
November 15, 2017: Food and Chemical Toxicology
https://www.readbyqxmd.com/read/29154855/identification-and-characterization-of-a-calcium-dependent-lily-type-lectin-from-black-rockfish-sebastes-schlegelii-molecular-antennas-are-involved-in-host-defense-via-pathogen-recognition
#5
Roopasingam Kugapreethan, Qiang Wan, Jehanathan Nilojan, Jehee Lee
Lily-type lectins (LTLs) are soluble pathogen recognition receptors (PRRs) that contain one or more characteristic carbohydrate recognition domains (CRDs), through which LTLs bind reversibly and specifically to cognate sugar moieties present on the invading pathogen membrane and trigger the host innate immune responses. In this study, we identified a LTL homolog (SsLTL) from black rockfish (Sebastes schlegelii) transcriptome database and its functional roles in innate immunity was investigated in vitro and in vivo...
November 14, 2017: Developmental and Comparative Immunology
https://www.readbyqxmd.com/read/29154026/inhibitors-of-metallo-%C3%AE-lactamases
#6
REVIEW
Caitlyn M Rotondo, Gerard D Wright
The β-lactams are the most successful class of antibiotic drugs but they are vulnerable to inactivation by a growing cadre of β-lactamases that now number more than a thousand variants. β-Lactamases operate by one of two general chemical mechanisms either catalyzing β-lactam ring hydrolysis via a covalent enzyme intermediate through the aegis of an active site serine residue or through a noncovalent Zn-dependent mechanism. The Ser-β-lactamases are currently dominant in the clinic and consequently, there has been great effort to identify inhibitors and to co-formulate these with β-lactam antibiotics...
November 15, 2017: Current Opinion in Microbiology
https://www.readbyqxmd.com/read/29153714/polyphosphonate-ligands-from-synthesis-to-design-of-hybrid-pegylated-nanoparticles-toward-phototherapy-studies
#7
Maelle Monteil, Hanane Moustaoui, Gennaro Picardi, Fatima Aouidat, Nadia Djaker, Marc Lamy de La Chapelle, Marc Lecouvey, Jolanda Spadavecchia
The use of phosphonate ligands to modify the nanoparticle (NPs) surface has attracted a strong interest in the last years for the design of highly functional hybrid materials. Here, we applied a methodology to synthesize bisphosphonates having functionalized PEG side chains with a specific length in order to design a novel class of hybrid nanomaterials composed by tetraphosphonate-complex-gold COOH-terminated PEG-coated NPs (Bis-PO-PEG-AuNPs). The synthetic approach consist in three steps: (1) Complexation between new phosphonate ligands (Bis PO) and tetrachloroauric acid (HAuCl4) to form gold clusters; (2) adsorption of COOH-terminated PEG molecules (PEG) onto Bis PO-Au complex; (3) reduction of metal ions in that vicinity, growth of gold particles and colloidal stabilization...
November 2, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/29152626/specific-recognition-of-cr-3-under-physiological-conditions-by-allyl-substituted-appendage-rhodamine-and-its-cell-imaging-studies
#8
Anup Kumar Bhanja, Snehasis Mishra, Kaushik Naskar, Suvendu Maity, Krishna Das Saha, Chittaranjan Sinha
An allyloxynitrophenylimio-propylhydroxyl appended rhodamine (RD-3) specifically recognises Cr(3+) in aqueous buffer medium at pH 7.4. The visible light excitable reagent (λex 505 nm) on selective binding to Cr(3+) exhibited a strong fluorescence turn-on response with powerful emission at 557 nm and the tail of this luminescence band is extended to ∼650 nm. Interference studies confirm that other metal ions (27 ions) do not hamper the detection process of Cr(3+). The sensing mechanism is studied by absorption, fluorescence, Job's plot, and (1)H NMR titration studies...
November 20, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/29152559/fasciola-hepatica-esps-could-indistinctly-activate-or-block-multiple-toll-like-receptors-in-a-human-monocyte-cell-line
#9
Olgary Figueroa-Santiago, Ana M Espino
Fasciola hepatica is a parasitic helminth that induces Th2/Treg responses in its mammalian host. Some reports have suggested that ESPs achieve these polarized immune responses by delaying the activation of dendritic cells and macrophages during the early stages of innate immunity, a process that is mediated by TLR4. The present study aimed to investigate whether TLRs other than TLR4 could also be targeted by F. hepatica ESPs. To achieve this aim a screening system was optimized using THP1-Blue CD14 cells. ESPs were first separated based on their molecular weight and according their net charge by ion exchange chromatography (IEC)...
2017: Ann Clin Pathol
https://www.readbyqxmd.com/read/29150617/carbon-contamination-during-ion-irradiation-accurate-detection-and-characterization-of-its-effect-on-microstructure-of-ferritic-martensitic-steels
#10
Jing Wang, Mychailo B Toloczko, Karen Kruska, Daniel K Schreiber, Danny J Edwards, Zihua Zhu, Jiandong Zhang
Accelerator-based ion beam irradiation techniques have been used to study radiation effects in materials for decades. Although carbon contamination induced by ion beams in target materials is a well-known issue in some material systems, it has not been fully characterized nor quantified for studies in ferritic/martensitic (F/M) steels that are candidate materials for applications such as core structural components in advanced nuclear reactors. It is an especially important issue for this class of material because of the strong effect of carbon level on precipitate formation...
November 17, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29149555/mapping-the-reactions-in-a-single-zero-valent-iron-nanoparticle
#11
Lan Ling, Xiao-Yue Huang, Meirong Li, Wei-Xian Zhang
Nanoscale zero-valent iron (nZVI) posseses unique functionalities for metal-metalloid removal and sequestration. So far, direct evidence on the heavy metal-iron reactions in the solid phase is still limited due to low concentration of heavy metals and small size of nanoparticles. In this work, angstrom-resolution spectral mappings on the reactions of nZVI with chromate, arsenate, nickel, silver, cesium, and zinc ions are presented. This work was achieved with spherical aberration-corrected scanning transmission electron microscopy integrated with high-sensitivity X-ray energy-dispersive spectroscopy scanning transmission electron microscopy (XEDS-STEM)...
November 17, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/29149423/structural-and-visible-near%C3%A2-infrared-optical-properties-of-cr-doped-tio2-for-colored-cool-pigments
#12
Le Yuan, Xiaolong Weng, Ming Zhou, Qingyong Zhang, Longjiang Deng
Chromium-doped TiO2 pigments were synthesized via a solid-state reaction method and studied with X-ray diffraction, SEM, XPS, and UV-VIS-NIR reflectance spectroscopy. The incorporation of Cr(3+) accelerates the transition from the anatase phase to the rutile phase and compresses the crystal lattice. Moreover, the particle morphology, energy gap, and reflectance spectrum of Cr-doped TiO2 pigments is affected by the crystal structure and doping concentration. For the rutile samples, some of the Cr(3+) ions are oxidized to Cr(4+) after sintering at a high temperature, which leads to a strong near-infrared absorption band due to the (3)A2 → (3) T1 electric dipole-allowed transitions of Cr(4+)...
November 17, 2017: Nanoscale Research Letters
https://www.readbyqxmd.com/read/29149176/a-simple-way-for-targeted-delivery-of-an-antibiotic-in-vitro-evaluation-of-a-nanoclay-based-composite
#13
Leslie Valdés, Irela Pérez, Louis Charles de Ménorval, Ernesto Altshuler, Jon Otto Fossum, Aramis Rivera
The sodium-modified form of fluorohectorite nanoclay (NaFh) is introduced as a potential drug carrier, demonstrating its ability for the controlled release of the broad-spectrum antibiotic Ciprofloxacin through in vitro tests. The new clay-drug composite is designed to target the local infections in the large intestine, where it delivers most of the incorporated drug thanks to its pH-sensitive behavior. The composite has been conceived to avoid the use of coating technology and to decrease the side-effects commonly associated to the burst-release of the ciprofloxacin at the stomach level...
2017: PloS One
https://www.readbyqxmd.com/read/29148736/formation-of-metal-cyanide-complexes-in-deliquescent-airborne-particles-a-new-possible-sink-for-hcn-in-urban-environments
#14
Chiara Giorio, Daniele Marton, Gianni Formenton, Andrea Tapparo
Hydrogen cyanide is a ubiquitous gas in the atmosphere and a biomass burning tracer. Reactive gasses can be adsorbed onto aerosol particles where they can promote heterogeneous chemistry. In the present study, we report for the first time on the measurement and speciation of cyanides in atmospheric aerosol. Filter samples were collected at an urban background site in the city center of Padua (Italy), extracted and analyzed with headspace gas chromatography and nitrogen-phosphorous detection. The results showed that strongly bound cyanides were present in all aerosol samples at a concentration ranging between 0...
November 17, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/29148143/leaf-cell-membrane-stability-based-mechanisms-of-zinc-nutrient-in-mitigation-of-salinity-stress-in-rice
#15
Abdullah Tufail, Hong Li, Asif Naeem, Tingxian Li
Excess salts affect about 955 million ha of total arable lands worldwide and 49% of agricultural lands are Zn deficient. Soil salinity and zinc deficiency can intensify plant abiotic stress. The mechanisms by which Zn nutrients can mitigate salinity effects on plant functions are not well understood. We conducted an experiment to determine the zinc and salinity effects on rice plant retention of Zn, macronutrient potassium (K) and salt ion Na, chlorophyll formation, leaf cell membrane stability and grain yield, and to examine the mechanisms of zinc nutrition in mitigating salinity stress on plant physiological and nutritional aspects...
November 16, 2017: Plant Biology
https://www.readbyqxmd.com/read/29148097/ce3-sensitized-tm3-mn2-doped-nayf4-colloidal-nanocrystals-intense-cool-white-light-from-phosphor-coated-uv-led
#16
Venkataramanan Mahalingam, Venkata N K B Adusumalli, Heramba V S R M Koppisetti
Intense white light emission is observed from colloidal single component NaYF4:Ce3+/Tm3+/Mn2+ nanocrystals. This combination is interesting as it uses Mn2+ ions instead of green and red emitting Ln3+ ions which are expensive and less abundant. The single band blue emission of Tm3+ ions was combined with the broadband greenish yellow emission of Mn2+ ions to produce strong white light emission using Ce3+ ions as excitation source. Interestingly, there is hardly any re-absorption of blue emission by Mn2+ ions and the spectrum matches the commercial Ce3+-doped YAG phosphor coated over blue LED...
November 17, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/29147699/strain-relaxation-and-ambipolar-electrical-transport-in-gaas-insb-core-shell-nanowires
#17
Torsten Rieger, Patrick Zellekens, Natalia Demarina, Ali Al Hassan, Franz Josef Hackemüller, Hans Lüth, Ullrich Pietsch, Thomas Schäpers, Detlev Grützmacher, Mihail Ion Lepsa
The growth, crystal structure, strain relaxation and room temperature transport characteristics of GaAs/InSb core-shell nanowires grown using molecular beam epitaxy are investigated. Due to the large lattice mismatch between GaAs and InSb of 14%, a transition from island-based to layer-like growth occurs during the formation of the shell. High resolution transmission electron microscopy in combination with geometric phase analyses as well as X-ray diffraction with synchrotron radiation are used to investigate the strain relaxation and prove the existence of different dislocations relaxing the strain on zinc blende and wurtzite core-shell nanowire segments...
November 17, 2017: Nanoscale
https://www.readbyqxmd.com/read/29146422/numerical-study-of-the-effect-of-soft-layer-properties-on-bacterial-electroporation
#18
Jeffrey L Moran, Naga Neehar Dingari, Paulo A Garcia, Cullen R Buie
We present a numerical model of electroporation in a gram-positive bacterium, which accounts for the presence of a negatively charged soft polyelectrolyte layer (which may include a periplasmic space, peptidoglycan layer, cilia, flagella, and other surface appendages) surrounding its plasma membrane. We model the ion transport within and outside the soft layer using the soft layer electrokinetics-based Poisson-Nernst-Planck formalism. Additionally, we model the electroporation dynamics on the plasma membrane using the pore nucleation-based electroporation formalism developed by Krassowska and Filev...
September 18, 2017: Bioelectrochemistry
https://www.readbyqxmd.com/read/29145111/a-novel-protein-tyrosine-phosphatase-like-phytase-from-lactobacillus-fermentum-nkn51-cloning-characterization-and-application-in-mineral-release-for-food-technology-applications
#19
Rekha Sharma, Piyush Kumar, Vandana Kaushal, Rahul Das, Naveen Kumar Navani
A novel protein tyrosine phosphatase like phytase (PTPLP), designated as PhyLf from probiotic bacterium Lactobacillus fermentum NKN51 was identified, cloned, expressed and characterized. The recombinant PhyLf showed specific activity of 174.5 U/mg. PhyLf exhibited strict specificity towards phytate and optimum temperature at 60 °C, pH 5.0 and ionic strength of 100 mM. Km and Kcat of PhyLf for phytate were 0.773 mM and 84.31 s(-1), respectively. PhyLf exhibited high resistance against oxidative inactivation...
November 4, 2017: Bioresource Technology
https://www.readbyqxmd.com/read/29144182/plasma-lyte-148-vs-hartmann-s-solution-for-cardiopulmonary-bypass-pump-prime-a-prospective-double-blind-randomized-trial
#20
Laurence Weinberg, Elizabeth Chiam, James Hooper, Frank Liskaser, Angela Kim Hawkins, Denise Massie, Andrew Ellis, Chong O Tan, David Story, Rinaldo Bellomo
BACKGROUND: The mechanisms of acid-base changes during cardiopulmonary bypass (CPB) remain unclear. We tested the hypothesis that, when used as CPB pump prime solutions, Plasma-Lyte 148 (PL) and Hartmann's solution (HS) have differential mechanisms of action in their contribution to acid-base changes. METHODS: We performed a prospective, double-blind, randomized trial in adult patients undergoing elective cardiac surgery with CPB. Participants received a CPB prime solution of 2000 mL, with either PL or HS...
November 1, 2017: Perfusion
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