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https://www.readbyqxmd.com/read/28742961/solid-solid-phase-transitions-and-t-butyl-and-methyl-group-rotation-in-an-organic-solid-x-ray-diffractometry-differential-scanning-calorimetry-and-solid-state-1h-nuclear-spin-relaxation
#1
Peter A Beckmann, Andrew R McGhie, Arnold L Rheingold, Gilbert J Sloan, Steven T Szewczyk
Using solid state 1H nuclear magnetic resonance (NMR) spin-lattice relaxation experiments, we have investigated the effects of several solid-solid phase transitions on t-butyl group and methyl group rotation in solid 1,3,5-tri-t-butylbenzene. The goal is to relate the dynamics of the t-butyl groups and their constituent methyl groups to properties of the solid determined using single-crystal X-ray diffraction and differential scanning calorimetry (DSC). On cooling, the DSC experiments see a first-order, solid-solid phase transition at either 268 K or 155 K (but not both) depending on thermal history...
July 25, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28742345/syntheses-structures-and-comparisons-of-heterometallic-uranyl-iodobenzoates-with-monovalent-cations
#2
Mark Kalaj, Korey P Carter, Anton V Savchenkov, Mikaela M Pyrch, Christopher L Cahill
The syntheses and crystal structures of six new heterometallic compounds containing the UO2(2+) cation, o-, m-, and p-iodobenzoic acid ligands, and Tl(+), Rb(+), and Cs(+) cations which adopt the role of both charge balancing cation and secondary metal center are described, as are the luminescent properties for Tl(+) containing compounds 1, 4, and 6. The structures of compounds 1-3 are isomorphous and contain uranyl monomers bound by o-iodobenzoic acid ligands with Tl(+), Rb(+), and Cs(+) cations acting as secondary metal centers...
July 25, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28742054/laue-lens-for-radiotherapy-applications-through-a-focused-hard-x-ray-beam-a-feasibility-study-on-requirements-and-tolerances
#3
Riccardo Camattari
Focusing a hard X-ray beam would represent an innovative technique for tumour treatment, since such a beam may deliver a dose to a tumour located at a given depth under the skin, sparing the surrounding healthy cells. A detailed study of a focusing system for hard X-ray aimed at radiotherapy is here presented. Such a focusing system, named Laue lens, exploits X-ray diffraction and consists of a series of crystals disposed as concentric rings capable of concentrating a flux of X-rays toward a focusing point...
July 25, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28741932/tailor-made-luminescent-polymers-through-unusual-metallophilic-interaction-arrays-au%C3%A2-%C3%A2-%C3%A2-au%C3%A2-%C3%A2-%C3%A2-ag%C3%A2-%C3%A2-%C3%A2-ag
#4
María Gil-Moles, M Concepción Gimeno, José M López-de-Luzuriaga, Miguel Monge, M Elena Olmos, David Pascual
A novel and efficient strategy for the synthesis of luminescent polymers bearing metallophilic interactions with unprecedented charge sequences has been designed. For this end suitable basic gold units such as [AuR2](-), bearing perhalophenyl derivatives, and dinuclear acid silver terpyridine species, [Ag2(terpy)2](CF3SO3)2, have been chosen. Their combination originates the polymeric derivatives [{AuR2}2Ag2(terpy)2]n (R = C6F5, C6Cl2F3) or [{Au(C6Cl5)2}Ag(terpy)]n. The change of the perhalophenyl group in the gold complex modulates the strength in the metallophilic contacts and, consequently, the polymer arrays and luminescent properties...
July 25, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28741594/polar-phase-transitions-in-heteroepitaxial-stabilized-la-sub-0-5-sub-y-sub-0-5-sub-alo-sub-3-sub-thin-films
#5
Shenghua Liu, Chunfeng Zhang, Mengya Zhu, Qian He, Jak Chakhalian, Xiaoran Liu, Albina Borisevich, Xiaoyong Wang, Min Xiao
We report on the fabrication of epitaxial La0.5Y0.5AlO3 ultrathin films on (001) LaAlO3 substrates. Structural characterizations by scanning transmission electron microscopy and X-ray diffraction confirm the high quality of the film with AlO6 octahedral tilt pattern. Unlike either of the nonpolar parent compound, LaAlO3 and YAlO3, second harmonic generation measurements on the thin films suggest a nonpolar - polar phase transition at Tc near 500 K, and a polar - polar phase transition at Ta near 160 K. By fitting the angular dependence of the second harmonic intensities, we further propose that the two polar structures can be assigned to the Pmc21 and Pmn21 space group, while the high temperature nonpolar structure belongs to the Pbnm space group...
July 25, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28741139/characterization-of-a-liquid-crystal-system-for-sustained-release-of-a-peptide-bms-686117
#6
Yan Xu, Vivian Li, Jinjiang Li, Duohai Pan, Gerd Langenbucher, Neil Mathias
Liquid crystal lipid-based formulations are an effective approach to prolong pharmacokinetics and reduce burst release of a drug on subcutaneous delivery. The objective of this paper was to investigate the influence of phase structures of a lipid-based liquid crystal delivery system and its associated mechanical properties on the release profile of a peptide. It was hypothesized that release of drug molecules are closely related to the mechanical properties that are controlled by phase structures. Experimentally, the relationship between phase structures of lipid liquid crystal system-soy phosphatidyl choline (SPC) and glycerol dioleate (GDO) in water were characterized by polarized light microscopy and small angle X-ray diffraction...
July 24, 2017: AAPS PharmSciTech
https://www.readbyqxmd.com/read/28741064/injectable-sustained-release-depots-of-plga-microspheres-for-insoluble-drugs-prepared-by-hot-melt-extrusion
#7
Yuting Guo, Yunning Yang, Luying He, Rong Sun, Chenguang Pu, Bin Xie, Haibing He, Yu Zhang, Tian Yin, Yanjiao Wang, Xing Tang
PURPOSE: Progesterone (PRG) was selected as a model drug to develop a long-acting injection system for poorly water-soluble drugs. METHODS: Microspheres with high density-low porosity were prepared by hot-melt extrusion (HME) combined with wet-milling as the representative formulation, and a microcrystal suspension was also studied as a comparison. The morphology, particle size and distribution, polymorphism, drug distribution, density and porosity were characterized by scanning electron microscopy, laser diffraction particle size analyzer, power X-ray diffraction and DSC respectively...
July 24, 2017: Pharmaceutical Research
https://www.readbyqxmd.com/read/28740983/combining-epr-spectroscopy-and-x-ray-crystallography-to-elucidate-the-structure-and-dynamics-of-conformationally-constrained-spin-labels-in-t4-lysozyme-single-crystals
#8
Philipp Consentius, Ulrich Gohlke, Bernhard Loll, Claudia Alings, Udo Heinemann, Markus C Wahl, Thomas Risse
Electron paramagnetic resonance (EPR) spectroscopy in combination with site-directed spin labeling is used to investigate the structure and dynamics of conformationally constrained spin labels in T4 lysozyme single crystals. Within a single crystal, the oriented ensemble of spin bearing moieties results in a strong angle dependence of the EPR spectra. A quantitative description of the EPR spectra requires the determination of the unit cell orientation with respect to the sample tube and the orientation of the spin bearing moieties within the crystal lattice...
July 25, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28740561/edta-assisted-phase-conversion-synthesis-of-gd0-95re0-05-po4-nanowires-re-eu-tb-and-investigation-of-photoluminescence
#9
Zhihao Wang, Ji-Guang Li, Qi Zhu, Zhengrong Ai, Xiaodong Li, Xudong Sun, Byung-Nam Kim, Yoshio Sakka
Hexagonal (Gd0.95RE0.05)PO4·nH2O nanowires ~300 nm in length and ~10 nm in diameter have been converted from (Gd0.95RE0.05)2(OH)5NO3·nH2O nanosheets (RE = Eu, Tb) in the presence of monoammonium phosphate (NH4H2PO4) and ethylene diamine tetraacetic acid (EDTA). They were characterized by X-ray diffraction, thermogravimetry, electron microscopy, and Fourier transform infrared and photoluminescence spectroscopies. It is shown that EDTA played an essential role in the morphology development of the nanowires...
2017: Science and Technology of Advanced Materials
https://www.readbyqxmd.com/read/28740381/chitosan-coated-diacerein-nanosuspensions-as-a-platform-for-enhancing-bioavailability-and-lowering-side-effects-preparation-characterization-and-ex-vivo-in-vivo-evaluation
#10
Ahmed N Allam, Sherif I Hamdallah, Ossama Y Abdallah
Nanodrug delivery systems have been widely reviewed for their use in several drug formulations to improve bioavailability, sustain effect, and decrease side effects of many candidate drugs. The objective of this study was to evaluate the potential of chitosan (CS)-coated nanosuspensions to enhance bioavailability and reduce the diarrheal side effect of diacerein (DCN) after oral administration. DCN nanosuspensions (DNS) were prepared by sonoprecipitation technique using different stabilizers at three different concentrations...
2017: International Journal of Nanomedicine
https://www.readbyqxmd.com/read/28739411/impact-of-heat-moisture-and-annealing-treatments-on-physicochemical-properties-and-digestibility-of-starches-from-different-colored-sweet-potato-varieties
#11
Phan Thanh Bao Trung, Luu Bui Bao Ngoc, Phan Ngoc Hoa, Nguyen Ngoc Thanh Tien, Pham Van Hung
The objective of this study is to investigate the change in physicochemical properties and digestibility of starches isolated from colored sweet potato varieties under heat-moisture treatment (HMT) or annealing treatment (ANN). The results showed that morphology and X-ray diffraction patterns of the sweet potato starches remained unchanged after the HMT or ANN. The HMT significantly reduced peak viscosity, breakdown and setback and significantly increased pasting temperature, trough and final viscosities of the sweet potato starches...
July 21, 2017: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/28739409/fabrication-of-au-iii-ion-imprinted-polymer-based-on-thiol-modified-chitosan
#12
M Monier, D A Abdel-Latif
Au(III) ions were selectively extracted from aqueous media using Au(III) ion-imprinted bio-adsorbent based on modified chitosan (Au-CMB). First, 2-mercaptobenzaldehyde-chitosan Schiff base was prepared and interacted with Au(III) ions. The obtained polymeric Au(III) complex was then cross-linked by epichlorohydrin (ECH) before leaching the template Au(III) ions out of the cross-linked matrix. During the synthetic procedures, the obtained chitosan derivatives were characterized by Elemental analysis, FTIR and NMR spectra...
July 21, 2017: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/28738658/an-ultrasensitive-chemiluminescence-aptasensor-for-thrombin-detection-based-on-iron-porphyrin-catalyzing-luminescence-desorbed-from-chitosan-modified-magnetic-oxide-graphene-composite
#13
Yuanling Sun, Yanhui Wang, Jianbo Li, Chaofan Ding, Yanna Lin, Weiyan Sun, Chuannan Luo
In this work, an ultrasensitive chemiluminescence (CL) aptasensor was prepared for thrombin detection based on iron porphyrin catalyzing luminol - hydrogen peroxide luminescence under alkaline conditions, and iron porphyrin was desorbed from chitosan modified magnetic oxide graphene composite (CS@Fe3O4@GO). Firstly, CS@Fe3O4@GO was prepared. CS@Fe3O4@GO has advantages of the good biocompatibility and positively charged on its surface of CS, the large specific surface area of GO and the easy separation characteristics of Fe3O4...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738619/simultaneous-and-sensitive-electrochemical-detection-of-dihydroxybenzene-isomers-with-uio-66-metal-organic-framework-mesoporous-carbon
#14
Min Deng, Shourui Lin, Xiangjie Bo, Liping Guo
The zirconium-based MOF (UiO-66)/mesoporous carbon (MC) composite was synthesized using conventional hydrothermal method for the first time. The surface morphology and structure of UiO-66/MC composite were characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). A novel electrochemical sensor based on UiO-66/MC was constructed for simultaneous and sensitive determination of dihydroxybenzene isomers (DBIs) of hydroquinone (HQ), catechol (CT) and resorcinol (RS)...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738559/a-novel-dianionic-amino-acid-ionic-liquid-coated-peg-4000-modified-fe3o4-nanocomposite-for-the-magnetic-solid-phase-extraction-of-trypsin
#15
Qin Yang, Yuzhi Wang, Hongmei Zhang, Kaijia Xu, Xiaoxiao Wei, Panli Xu, Yigang Zhou
A novel magnetic extractant, PEG 4000 modified Fe3O4nanomaterial that coated with dianionic amino acid ionic liquid (Fe3O4@PEG@DAAAIL), was successfully synthesized and characterized. X-ray diffraction (XRD), transmission electron microscope (TEM), vibrating sample magnetometer (VSM), fourier transform infrared spectrometry (FT-IR), thermal gravimetric analysis (TGA) and zeta potentials were used to confirm that the novel nanocomposite was successfully synthesized. Subsequently, the prepared Fe3O4@PEG@DAAAIL nanocomposite was used as the extractant for trypsin coupled with magnetic solid-phase extraction (MSPE)...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738278/well-dispersed-rhenium-nanoparticles-on-three-dimensional-carbon-nanostructures-efficient-catalysts-for-the-reduction-of-aromatic-nitro-compounds
#16
Pitchaimani Veerakumar, Pounraj Thanasekaran, King-Chuen Lin, Shang-Bin Liu
Rhenium nanoparticles (ReNPs) supported on ordered mesoporous carbon (OMC) as a catalyst (Re/OMC) through a solvent-evaporation induced self-assembly (ELSA) method were prepared. The synthesized heterogonous catalyst was fully characterized using X-ray diffraction, field emission transmission electron microscopy, N2 sorption, metal dispersion, thermogravimetric analysis, Raman, Fourier-transform infrared, and X-ray photon spectroscopies. In addition, the catalyst was applied to reduce the aromatic nitro compounds (ANCs) for the first time in aqueous media and the reactions were monitored by following the intensity changes in the UV-vis absorption spectra with respect to time...
July 18, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28738251/quantification-of-some-elements-of-nuclear-and-industrial-interest-from-zircon-mineral-using-neutron-activation-analysis-and-passive-gamma-ray-spectroscopy
#17
M F Attallah, M A Hilal, S I Moussa
A combined of various nuclear and analytical techniques were used for characterization of Egyptian zircon ore. Neutron activation analysis has been used for determination of the major, minor and trace elements from zircon ore. Non-destructive gamma-ray technique is also used for the radiometric analysis of zircon ore to quantify the natural radionuclides such as (238)U, (235)U, (232)Th, (226)Ra and (40)K. Zircon ore has been characterized by different analytical tools such as Fourier transformer infrared (FTIR), X-ray fluorescence (XRF), powder X-ray diffraction (XRD), and scanning electron microscopy (SEM)...
July 14, 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/28738241/annotinolide-f-and-lycoannotines-a-i-further-lycopodium-alkaloids-from-lycopodium-annotinum
#18
Yu Tang, Juan Xiong, Yike Zou, Wei Wang, Chao Huang, Hai-Yan Zhang, Jin-Feng Hu
Seven lycopodine-type (annotinolide F and lycoannotines A-F), two lycodine-type (lycoannotines G and H), and one fawcettimine-type (lycoannotine I) previously undescribed naturally occurring Lycopodium alkaloids together with thirteen known ones were isolated from the whole plant of Lycopodium annotinum. Their structures and absolute configurations were determined by extensive spectroscopic methods, single-crystal X-ray diffraction, chemical transformation, and electronic circular dichroism (ECD) calculations...
July 21, 2017: Phytochemistry
https://www.readbyqxmd.com/read/28738146/high-throughput-structural-and-functional-characterization-of-the-thin-film-materials-system-ni-co-al
#19
Peer Decker, Dennis Naujoks, Dennis Langenkaemper, Christoph Somsen, Alfred Ludwig
High-throughput methods were used to investigate a Ni-Co-Al thin film materials library. This material system is of interest for superalloys and shape memory alloys. High resolution grazing incidence x-ray diffraction (XRD) measurements were carried out to identify the library's phase regions; d-spacing maps, based on peak fitting, were used to determine more precisely the compositional existence regions of phases. Thin film texture, which was observed in XRD, was also addressed. Finally, magneto-optical measurements were performed to confirm the results of the XRD measurements...
July 24, 2017: ACS Combinatorial Science
https://www.readbyqxmd.com/read/28737819/insertion-reactions-of-small-unsaturated-molecules-in-the-n-b-bonds-of-boron-guanidinates
#20
Alberto Ramos, Antonio Antiñolo, Fernando Carrillo-Hermosilla, Rafael Fernández-Galán, María Del Pilar Montero-Rama, Elena Villaseñor, Antonio Rodríguez-Diéguez, Daniel García-Vivó
We report here 1,1- and 1,2-insertion reactions of small unsaturated molecules in the N-B bonds of two boron guanidinates, (Me2N)C(N(i)Pr)2BCy2 (1) and {(i)Pr(H)N}C(N(i)Pr){N(p-(t)Bu-C6H4)}BCy2 (2), and two bisboron guanidinates(2-), {(i)Pr(BCy2)N}C(N(i)Pr){N(p-(t)Bu-C6H4)}BCy2 (3) and {(i)Pr(C8H14B)N}C(N(i)Pr){N(p-Me-C6H4)}BC8H14 (4), the latter being prepared for the first time by double deprotonation of the corresponding guanidine with the 9-borabicyclo[3.3.1]nonane dimer, (H-BC8H14)2. Compounds 1-4 easily insert aromatic isonitriles, XylNC (Xyl = 2,6-Me2-C6H3) and (p-MeO-C6H4)NC, to give the expected diazaboroles 5-12, some of them being structurally characterised by X-ray diffraction...
July 24, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
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