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https://www.readbyqxmd.com/read/28637278/functional-and-structural-analysis-of-at-specific-minor-groove-binders-that-disrupt-dna-protein-interactions-and-cause-disintegration-of-the-trypanosoma-brucei-kinetoplast
#1
Cinthia R Millan, Francisco J Acosta-Reyes, Laura Lagartera, Godwin U Ebiloma, Leandro Lemgruber, J Jonathan Nué Martínez, Núria Saperas, Christophe Dardonville, Harry P de Koning, J Lourdes Campos
Trypanosoma brucei, the causative agent of sleeping sickness (Human African Trypanosomiasis, HAT), contains a kinetoplast with the mitochondrial DNA (kDNA), comprising of >70% AT base pairs. This has prompted studies of drugs interacting with AT-rich DNA, such as the N-phenylbenzamide bis(2-aminoimidazoline) derivatives 1 [4-((4,5-dihydro-1H-imidazol-2-yl)amino)-N-(4-((4,5-dihydro-1H-imidazol-2-yl)amino)phenyl)benzamide dihydrochloride] and 2 [N-(3-chloro-4-((4,5-dihydro-1H-imidazol-2-yl)amino)phenyl)-4-((4,5-dihydro-1H-imidazol-2-yl)amino)benzamide] as potential drugs for HAT...
June 16, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/28636921/characterizing-intracellular-ice-formation-of%C3%A2-lymphoblasts-using-low-temperature-raman%C3%A2-spectroscopy
#2
Guanglin Yu, Yan Rou Yap, Kathryn Pollock, Allison Hubel
Raman microspectroscopy was used to quantify freezing response of cells to various cooling rates and solution compositions. The distribution pattern of cytochrome c in individual cells was used as a measure of cell viability in the frozen state and this metric agreed well with the population-averaged viability and trypan blue staining experiments. Raman imaging of cells demonstrated that intracellular ice formation (IIF) was common and did not necessarily result in cell death. The amount of intracellular ice as well as ice crystal size played a role in determining whether or not ice inside the cell was a lethal event...
June 20, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28636907/epr-spectroscopy-targets-structural-changes-in-the-e-%C3%A2-coli-membrane-fusion-cusb-upon-cu-i-binding
#3
Aviv Meir, Ahmad Abdelhai, Yoni Moskovitz, Sharon Ruthstein
Bacterial cells have developed sophisticated systems to deal with the toxicity of metal ions. Escherichia coli CusCFBA is a complex efflux system, responsible for transferring Cu(I) and Ag(I) ions; this system, located in the periplasm, involves four proteins, CusA, CusB, CusC, and CusF. CusA, CusB, and CusC are connected to one another in an oligomerization ratio of 3:6:3 CusA/CusB/CusC to form the CusCBA periplasm membrane transporter. CusB is an adaptor protein that connects the two membrane proteins CusA (inner membrane) and CusC (outer membrane)...
June 20, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28636815/accurate-characterization-of-the-pore-volume-in-microporous-crystalline-materials
#4
Daniele Ongari, Peter G Boyd, Senja Barthel, Matthew Witman, Maciej Haranczyk, Berend Smit
Pore volume is one of the main properties for the characterization of microporous crystals. It is experimentally measurable and it can also be obtained from the refined unit cell by a number of computational techniques. In this work we assess the accuracy and the discrepancies between the different computational methods which are commonly used for this purpose, i.e, geometric, helium and probe center pore volume, by studying a database of more than 5000 frameworks. We developed a new technique to fully characterize the internal void of a microporous material and to compute the probe accessible and occupiable pore volume...
June 21, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28636690/opioid-use-in-trauma-combating-the-opidemic-through-thoughtful-prescribing-practices
#5
Crystal Webb, Amalia Cochran
No abstract text is available yet for this article.
June 21, 2017: JAMA Surgery
https://www.readbyqxmd.com/read/28636680/unifying-the-microscopic-picture-of-his-containing-turns-from-gas-phase-model-peptides-to-crystallized-proteins
#6
Woon Yong Sohn, Sana Habka, Eric Gloaguen, Michel Mons
The presence in crystallized proteins of a local anchoring between the side chain of a His residue, located in the central position of a γ- or β-turn, and its local main chain environment, was assessed by the comparison of protein structures with relevant isolated model peptides. Gas phase laser spectroscopy, combined with relevant quantum chemistry methods, was used to characterize the γ- and β-turn structures in these model peptides. A conformer-selective NH stretch infrared study provided evidence for the formation in vacuo of two types of short-range H-bonded motifs, labelled ε-6(δ) and δ-(δ)7/π(H), bridging the His side chain (in its gauche+ rotamer) to the neighbouring NH(i) and CO(i) sites of the backbone; each side chain-backbone motif was found to be specific of the tautomer (ε or δ) adopted by the His side chain in its neutral form...
June 21, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28636601/crystal-structure-of-the-potassium-importing-kdpfabc-membrane-complex
#7
Ching-Shin Huang, Bjørn Panyella Pedersen, David L Stokes
Cellular potassium import systems play a fundamental role in osmoregulation, pH homeostasis and membrane potential in all domains of life. In bacteria, the kdp operon encodes a four-subunit potassium pump that maintains intracellular homeostasis, cell shape and turgor under conditions in which potassium is limiting. This membrane complex, called KdpFABC, has one channel-like subunit (KdpA) belonging to the superfamily of potassium transporters and another pump-like subunit (KdpB) belonging to the superfamily of P-type ATPases...
June 21, 2017: Nature
https://www.readbyqxmd.com/read/28636479/decrements-in-knee-extensor-and-flexor-strength-are-associated-with-performance-fatigue-during-simulated-basketball-game-play-in-adolescent-male-players
#8
Aaron T Scanlan, Jordan L Fox, Nattai R Borges, Anne Delextrat, Tania Spiteri, Vincent J Dalbo, Robert Stanton, Crystal O Kean
This study quantified lower-limb strength decrements and assessed the relationships between strength decrements and performance fatigue during simulated basketball. Ten adolescent, male basketball players completed a circuit-based, basketball simulation. Sprint and jump performance were assessed during each circuit, with knee flexion and extension peak concentric torques measured at baseline, half-time, and full-time. Decrement scores were calculated for all measures. Mean knee flexor strength decrement was significantly (P < 0...
June 21, 2017: Journal of Sports Sciences
https://www.readbyqxmd.com/read/28636388/correlation-between-photoluminescence-and-carrier-transport-and-a-simple-in-situ-passivation-method-for-high-bandgap-hybrid-perovskites
#9
Ryan J Stoddard, Felix T Eickemeyer, John K Katahara, Hugh W Hillhouse
High bandgap mixed-halide hybrid perovskites have higher open-circuit voltage deficits and lower carrier diffusion lengths than their lower-bandgap counterparts. We have developed a Ligand-Assisted Crystallization (LAC) technique that introduces additives in-situ during the solvent wash and developed a new method to dynamically measure the absolute-intensity steady-state photoluminescence and the mean carrier diffusion length simultaneously. The measurements reveal four distinct regimes of material changes and show that photoluminescence brightening often coincides with losses in carrier transport, such as in degradation or phase segregation...
June 21, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28636384/role-of-crystal-structure-and-chalcogenide-redox-properties-on-the-oxidative-assembly-of-cadmium-chalcogenide-nanocrystals
#10
Jessica Davis, Aaron M Chalifoux, Stephanie L Brock
Oxidative assembly of metal chalcogenide nanocrystals (NCs) enables formation of 2-D (dense) and 3-D porous structures without the presence of intervening ligands between particles that can moderate transport properties. This route has been demonstrated successful for a range of single component structures including CdQ, PbQ and ZnQ (Q = S, Se, Te). En route to controllable assembly of multicomponent nanostructures, the roles of Q redox properties (2Q2-  Q22- + 2e), responsible for particle crosslinking, and the native structure (cubic zinc blende vs...
June 21, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28636376/on-the-mechanism-of-the-iodide-triiodide-exchange-reaction-in-a-solid-state-ionic-liquid
#11
Joás Grossi, Jorge J Kohanoff, Niall J English, Eduardo M Bringa, Mario G Del Pópolo
Efficient charge transport has been observed in iodide-based room-temperature ionic liquids when doped with iodine. To investigate preferred pathways for the iodide (I(-))-to-triiodide (I3(-)) exchange reaction and to clarify the origin of this high ionic conductivity, we have conducted electronic structure calculations in the crystal state of 1-butyl-3-methylimidazolium iodide ([BMIM][I]). Energy barriers for the different stages of the iodine-swapping process, including the reorientation of the I(-)···I3(-) moiety, were determined from minimum energy paths as a function of a reaction coordinate...
June 21, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28636344/ruthenium-complexes-are-ph-activated-metallo-prodrugs-phamps-with-light-triggered-selective-toxicity-toward-cancer-cells
#12
Fengrui Qu, Seungjo Park, Kristina Martinez, Jessica L Gray, Fathima Shazna Thowfeik, John A Lundeen, Ashley E Kuhn, David J Charboneau, Deidra L Gerlach, Molly M Lockart, James A Law, Katherine L Jernigan, Nicole Chambers, Matthias Zeller, Nicholas A Piro, W Scott Kassel, Russell H Schmehl, Jared J Paul, Edward J Merino, Yonghyun Kim, Elizabeth T Papish
Metallo prodrugs that take advantage of the inherent acidity surrounding cancer cells have yet to be developed. We report a new class of pH-activated metallo prodrugs (pHAMPs) that are activated by light- and pH-triggered ligand dissociation. These ruthenium complexes take advantage of a key characteristic of cancer cells and hypoxic solid tumors (acidity) that can be exploited to lessen the side effects of chemotherapy. Five ruthenium complexes of the type [(N,N)2Ru(PL)](2+) were synthesized, fully characterized, and tested for cytotoxicity in cell culture (1A: N,N = 2,2'-bipyridine (bipy) and PL, the photolabile ligand, = 6,6'-dihydroxybipyridine (6,6'-dhbp); 2A: N,N = 1,10-phenanthroline (phen) and PL = 6,6'-dhbp; 3A: N,N = 2,3-dihydro-[1,4]dioxino[2,3-f][1,10]phenanthroline (dop) and PL = 6,6'-dhbp; 4A: N,N = bipy and PL = 4,4'-dimethyl-6,6'-dihydroxybipyridine (dmdhbp); 5A: N,N = 1,10-phenanthroline (phen) and PL = 4,4'-dihydroxybipyridine (4,4'-dhbp)...
June 21, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28636342/charge-transfer-properties-of-triarylamine-integrated-dimolybdenum-dyads
#13
Lu Chen, Suman Mallick, Ying Ning Tan, Miao Meng, Chun Y Liu
Three quadruply bonded dimolybdenum complexes equipped with a triarylamine pendant, [(DAniF)3Mo2(μ-O2CC6H4N(C6H4CH3)2] (DAniF = N,N'-di(p-anisyl)formamidinate; [OO-ph-N]), [(DAniF)3Mo2(μ-OSCC6H4N(C6H4CH3)2] ([OS-ph-N]), and [(DAniF)3Mo2(μ-S2CC6H4N(C6H4CH3)2] ([SS-ph-N]), have been synthesized and characterized by single crystal X-ray diffraction. In electrochemical measurements, the redox couple for the organic amine group becomes irreversible, reflecting the substantially strong electronic interaction between the dimetal center and organic redox site...
June 21, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28636340/three-dimensional-modeling-of-quasicrystal-structures-from-x-ray-diffraction-an-icosahedral-al-cu-fe-alloy
#14
Seung-Tae Hong
Quasicrystals (QCs) are well-ordered but aperiodic crystals with classically forbidden symmetries (such as 5-fold). High-dimensional (HD) crystallography is a standard method to locate atom positions explicitly. However, in practice, it is still challenging because of its complexity. Here, we report a new simple approach to three-dimensional (3D) atomic modeling derived from X-ray diffraction data, and apply it to the icosahedral QC Al0.63Cu0.25Fe0.12. Electron density maps were calculated directly from 3D diffraction data indexed with noninteger (fractional) numbers as measured, with proper phases; each of 2(5) = 32 possible phase assignments for the five strongest reflections was used for Fourier synthesis...
June 21, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28636337/thermal-annealing-to-modulate-the-shape-memory-behavior-of-a-biobased-and-biocompatible-triblock-copolymer-scaffold-in-the-human-body-temperature-range
#15
Andrea Merlettini, Matteo Gigli, Martina Ramella, Chiara Gualandi, Michelina Soccio, Francesca Boccafoschi, Andrea Munari, Nadia Lotti, Maria Letizia Focarete
A biodegradable and biocompatible electrospun scaffold with shape memory behavior in the physiological temperature range is here presented. It was obtained starting from a specifically designed, biobased PLLA-based triblock copolymer, where the central block is poly(propylene azelate-co-propylene sebacate), (P(PAz60PSeb40)) random copolymer. Shape memory properties are determined by the contemporary presence of the low melting crystals of the P(PAz60PSeb40) block, acting as switching segment, and of the high melting crystal phase of PLLA blocks, acting as physical network...
June 21, 2017: Biomacromolecules
https://www.readbyqxmd.com/read/28636317/downsizing-proto-oncogene-cfos-to-short-helix-constrained-peptides-that-bind-jun
#16
Daniel Baxter, Samuel R Perry, Timothy A Hill, W Mei Kok, Nathan R Zaccai, R Leo Brady, David P Fairlie, Jody M Mason
The oncogenic transcription factor activator protein-1 (AP-1) is a DNA-binding protein that assembles through dimerization of Fos and Jun protein subunits, their leucine-rich helical sequences entwining into a coiled-coil structure. This study reports on downsizing the proto-oncogene cFos protein (380 residues) to shorter peptides (37-25 residues) modified with helix-inducing constraints to enhance binding to Jun. A crystal structure is reported for a 37-residue Fos-derived peptide (FosW) bound to Jun. This guided iterative downsizing of FosW to shorter peptide sequences that were constrained into stable water-soluble α-helices by connecting amino acid side chains to form cyclic pentapeptide components...
June 21, 2017: ACS Chemical Biology
https://www.readbyqxmd.com/read/28636311/insights-into-integrated-lead-generation-and-target-identification-in-malaria-and-tuberculosis-drug-discovery
#17
John Okombo, Kelly Chibale
New, safe and effective drugs are urgently needed to treat and control malaria and tuberculosis, which affect millions of people annually. However, financial return on investment in the poor settings where these diseases are mostly prevalent is very minimal to support market-driven drug discovery and development. Moreover, the imminent loss of therapeutic lifespan of existing therapies due to evolution and spread of drug resistance further compounds the urgency to identify novel effective drugs. However, the advent of new public-private partnerships focused on tropical diseases and the recent release of large data sets by pharmaceutical companies on antimalarial and antituberculosis compounds derived from phenotypic whole cell high throughput screening have spurred renewed interest and opened new frontiers in malaria and tuberculosis drug discovery...
June 21, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28636267/strontium-releasing-fluorapatite-glass-ceramics-crystallization-behavior-microstructure-and-solubility
#18
Isabelle Denry, Ourania-Menti Goudouri, Jeffrey D Harless, E M Hubbard, Julie A Holloway
The purpose of this work was to investigate the effect of strontium partial replacement for calcium on the crystallization behavior, microstructure and solubility of fluorapatite glass-ceramics. Four glass compositions were prepared with increasing amounts of strontium partially replacing calcium. The crystallization behavior was analyzed by differential scanning calorimetry and X-ray diffraction (XRD). The microstructure was investigated by scanning electron microscopy. The chemical solubility was quantified according to ISO standard 10993-14...
June 21, 2017: Journal of Biomedical Materials Research. Part B, Applied Biomaterials
https://www.readbyqxmd.com/read/28636148/magneto-structural-characterization-of-oxalamide-dihalo-bridged-copper-dimers-intra-and-interdimer-interactions-studied-by-single-crystal-esr-spectroscopy
#19
Dijana Zilic, Debdeep Maity, Mario Cetina, Kresimir Molcanov, Zoran Dzolic, Mirta Herak
The detailed single crystal electron spin resonance (ESR) analysis of oxalamide complexes with halogen-bridged copper dimers, supported by X-ray, magnetic susceptibility and powder ESR studies, is reported. Four complexes with two different ligands were synthesized: [CuLA(μ-X)]₂ and [CuLV(μ-X)]₂, where LA = N-(L-alanine methyl ester)-N'-((2-pyridine-2-yl)methyl)oxalamide and LV=N-(L-valine methyl ester)-N'-((2-pyridine-2-yl)methyl)oxalamide, while X=Cl or Br. X-ray analysis shows that geometry at each copper(II) ion is square pyramidal while two pyramids share one base-to-apex edge with parallel basal planes...
June 21, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28636049/neutral-mixed-metal-coordination-polymers-based-on-a-ditopic-acetylacetonate-mg-ii-and-ag-i-syntheses-characterization-and-solvent-dependent-topologies
#20
Qianqian Guo, Ulli Englert
The complex [Mg(acacCN)2(H2O)2] (acacCN = 3-cyanoacetylacetonate) has been synthesized in good yield and fully characterized. It represents a versatile labile precursor for an anionic tris(ligand) complex which is crosslinked with Ag(i) to five different neutral bimetallic networks; all of them are solvates. Four of these extended structures share the same framework stoichiometry Ag[Mg(acacCN)3] and only differ in their solvent content. The co-crystallized solvent molecules decide the topological outcome of the crosslinking: the four compounds can be classified into two isomorphous 3D networks and two non-isomorphous but related 2D layer structures...
June 21, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
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