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Tao Yu, Maohua Lin, Bo Wu, Jintian Wang, Chi-Tay Tsai
On the basis of the framework of cubic gauche nitrogen (cg-N), six one-eighth methanetriyl groups (>CH-) substitutes and fifteen one-fourth >CH- substitutes were optimized using the first-principle calculations based on density functional theory (DFT). Both one-eighth and one-fourth substitutes still keep the gauche structures with the simple formula CHN7 and CHN3 , respectively. The most thermodynamic stable gauche CHN7 and CHN3 are P21 qtg-C2 H2 N14 I and P21 qtg-C4 H4 N12 III, respectively. No probability density of C-C single bonds and high probability densities of C-N-C structures were found in the two substitutes...
May 16, 2018: Journal of Molecular Graphics & Modelling
Imran Uddin
Interaction of nanoparticles with biological systems turns out to be vibrant for their efficient application in biomedical field. Here, we have shown antibiotic amakicin loaded nanoparticles are responsible for the dual role as reducing and stabilizing the silver nanoparticles without the use of any undesired chemicals. Synthesized nanoparticles are well-dispersed having quasi spherical morphology with an average particle size around 10-11 nm. Crystallinity of nanoparticles was measured using selected area electron diffraction (SAED) and powder XRD analysis which show that particles are perfectly crystalline with cubic phase of geometry...
May 16, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Tadayoshi Watanabe, Ryo Nakamura, Yuta Takase, Etsuo A Susaki, Hiroki R Ueda, Ryosuke Tadokoro, Yoshiko Takahashi
Although the basic schema of the body plan is similar among different species of amniotes (mammals, birds, and reptiles), the lung is an exception. Here, anatomy and physiology are considerably different, particularly between mammals and birds. In mammals, inhaled and exhaled airs mix in the airways, whereas in birds the inspired air flows unidirectionally without mixing with the expired air. This bird-specific respiration system is enabled by the complex tubular structures called parabronchi where gas exchange takes place, and also by the bellow-like air sacs appended to the main part of the lung...
May 21, 2018: Developmental Biology
Nadezhda B Bolotina, Alexander P Dudka, Olga N Khrykina, Vladimir N Krasnorussky, Natalya Yu Shitsevalova, Volodymyr B Filipov, Nikolay E Sluchanko
High-quality single crystals of LuB12 are grown using the induction zone melting method. The X-ray data are collected at temperatures 293, 135, 95, 50 K. The crystal structure of LuB12 can be refined with record low R-factor in the cubic Fm-3m symmetry group despite reiterated observations of the cubic symmetry distortions both in the unit-cell values and in the physical properties. A peculiar computing strategy is developed to resolve this contradiction. True symmetry of the electron-density distribution in LuB12 is proved to be much lower than cubic as a result, which correlates very accurately with anisotropy of transport properties of LuB12...
May 23, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Abhijit Nag, Papri Chakraborty, Mohammad Bodiuzzaman, Tripti Ahuja, Sudhadevi Antharjanam, Thalappil Pradeep
We present the first example of polymorphism (cubic & trigonal) in single crystals of an atomically precise monolayer protected cluster, Ag29(BDT)12(TPP)43-. We demonstrate that C-Hπ interactions of the secondary ligands (TPP) are dominant in a cubic lattice compared to a trigonal lattice, resulting in a greater rigidity of the structure, which in turn, results in a higher luminescence efficiency in it.
May 23, 2018: Nanoscale
Bin Zhao, Huan-Cheng Hu
A new concept for constructing metal-organic frameworks (MOFs) based on multicentre-bonded [MI]8 (M = Mn, Zn) clusters with cubic aromaticity is discussed. In principle, intermolecular/intramolecular hydrogen-bonding, π***π stacking, coordinated covalent bonding and ionic bonding usually account for the structures of MOFs, and multicentered bonds generally exist in cation, anion, neutral and zwitterionic radicals, while rarely appear in MOFs. Meanwhile, aromaticity became one of the most vexing yet fascinating key concepts in chemistry since the proposition of the structure of benzene molecule in 1865...
May 23, 2018: Chemistry: a European Journal
Wei Wu, Shuyang Zhang, Yuchao Guo, Ruifeng Liu, Zhujun Shen, Xueqing Zhu, Zhenyu Liu
BACKGROUND: The precise relationship between increased thrombolysis in myocardial infarction (TIMI) frame counts and the topographical extent of isolated coronary artery ectasia (CAE) has not been fully explained. New parameters of linear dimension (LD) and the estimated ectatic area (EEA) together with the diameter and ectasia ratio may be associated with the corrected TIMI frame count (CTFC) in isolated CAE patients. METHODS: The topographical parameters of ectatic coronary arteries and/or segments of 77 isolated CAE patients were consecutively studied...
May 22, 2018: BMC Cardiovascular Disorders
Rita Galeiras, Mónica Mourelo, María Teresa Bouza, María Teresa Seoane, María Elena Ferreiro, Antonio Montoto, Sebastián Salvador, Leticia Seoane, David Freire
INTRODUCTION: To determine the optimal moment to carry out a tracheostomy in a patient requiring anterior cervical fixation. METHODS: A retrospective observational study was carried out over an 18-year period on 56 patients who had been admitted to the ICU with acute spinal cord injury (SCI), and who underwent a tracheostomy and surgical fixation. The sample was divided into two groups: An at-risk group (31 patients, who had undergone a tracheostomy prior to the cervical surgery or <4 days after the procedure), and a not at-risk group (25 patients, who had undergone a tracheostomy >4 day following the fixation surgery)...
May 19, 2018: World Neurosurgery
Markus Gross, Fathollah Varnik
Flow behavior of a single-component yield stress fluid is addressed on the hydrodynamic level. A basic ingredient of the model is a coupling between fluctuations of density and velocity gradient via a Herschel-Bulkley-type constitutive model. Focusing on the limit of low shear rates and high densities, the model approximates well-but is not limited to-gently sheared hard sphere colloidal glasses, where solvent effects are negligible. A detailed analysis of the linearized hydrodynamic equations for fluctuations and the resulting cubic dispersion relation reveals the existence of a range of densities and shear rates with growing flow heterogeneity...
May 22, 2018: Soft Matter
Forrest H Kaatz, Adhemar Bultheel
Au-Cu and Pt-M (M = Fe, Co, and Ni) nanocluster alloys are currently being investigated world-wide by many researchers for their interesting catalytic and nanophase properties. The low temperature behavior of the phase diagrams is not well understood for alloys with nanometer sizes and shapes. We consider two models for low temperature ordering in the phase diagrams of Au-Cu and Pt-M nanocluster alloys. These models are valid for sizes ∼ 5 nm and approach bulk values for sizes ∼ 20 nm. We study the phase transitions in nanoclusters with cubic, octahedral, and cuboctahedral shapes, covering the compositions of interest...
May 22, 2018: Nanotechnology
Shenggen Yao, Thomas G Meikle, Ashish Sethi, Frances Separovic, Jeffrey J Babon, David W Keizer
Pulsed-field gradient nuclear magnetic resonance has seen an increase in applications spanning a broad range of disciplines where molecular translational diffusion properties are of interest. The current study introduces and experimentally evaluates the measurement of translational diffusion coefficients of 15 N-enriched biomolecules using a 1 H-15 N HMQC-filtered band-selective excitation short transient (BEST) sequence as an alternative to the previously described SOFAST-XSTE sequence. The results demonstrate that accurate translational diffusion coefficients of 15 N-labelled peptides and proteins can be obtained using this alternative 1 H-15 N HMQC-filtered BEST sequence which is implementable on NMR spectrometers equipped with probes fitted with a single-axis field gradient, including most cryoprobes dedicated to bio-NMR...
May 21, 2018: European Biophysics Journal: EBJ
Wen Liu, Guo-Hui Pan, Zhendong Hao, Liangliang Zhang, Xia Zhang, Yongshi Luo, Haifeng Zhao, Huajun Wu, Jiahua Zhang
Developing optical temperature sensors with a wider range, higher sensitivity and repeatability based on Er3+/Yb3+ doped upconverting phosphors has always been at the forefront of temperature measurement technologies. Here, we report the intense green upconversion luminescence in Er3+/Yb3+ doped δ-Sc4Zr3O12 for the first time and its temperature sensing performance is investigated. The structure of δ-Sc4Zr3O12 is given by Rietveld refinement of XRD data and the site occupancy of Er3+ ions has been determined...
May 22, 2018: Physical Chemistry Chemical Physics: PCCP
Maja Mielke, Jan Wölfer, Patrick Arnold, Anneke H van Heteren, Eli Amson, John A Nyakatura
Background: Sciuromorpha (squirrels and close relatives) are diverse in terms of body size and locomotor behavior. Individual species are specialized to perform climbing, gliding or digging behavior, the latter being the result of multiple independent evolutionary acquisitions. Each lifestyle involves characteristic loading patterns acting on the bones of sciuromorphs. Trabecular bone, as part of the bone inner structure, adapts to such loading patterns. This network of thin bony struts is subject to bone modeling, and therefore reflects habitual loading throughout lifetime...
2018: Zoological Letters
Fredi Alexander Diaz-Quijano
PURPOSE: In large-scale surveys, it is often necessary to distribute a preset sample size among a number of strata. Researchers must make a decision between prioritizing overall representativeness or precision of stratum estimates. Hence, I evaluated different sample allocation strategies based on stratum size. METHODS: The strategies evaluated herein included allocation proportional to stratum population; equal sample for all strata; and proportional to the natural logarithm, cubic root, and square root of the stratum population...
May 7, 2018: Annals of Epidemiology
Zhiyu Qu, Fuxin Qu, Changbo Hou, Fulong Jing
In an inverse synthetic aperture radar (ISAR) imaging system for targets with complex motion, the azimuth echo signals of the target are always modeled as multicomponent quadratic frequency modulation (QFM) signals. The chirp rate (CR) and quadratic chirp rate (QCR) estimation of QFM signals is very important to solve the ISAR image defocus problem. For multicomponent QFM (multi-QFM) signals, the conventional QR and QCR estimation algorithms suffer from the cross-term and poor anti-noise ability. This paper proposes a novel estimation algorithm called a two-dimensional product modified parameterized chirp rate-quadratic chirp rate distribution (2D-PMPCRD) for QFM signals parameter estimation...
May 19, 2018: Sensors
Panos Tsakiropoulos
The development of Nb-silicide based alloys is frustrated by the lack of composition-process-microstructure-property data for the new alloys, and by the shortage of and/or disagreement between thermodynamic data for key binary and ternary systems that are essential for designing (selecting) alloys to meet property goals. Recent publications have discussed the importance of the parameters δ (related to atomic size), Δχ (related to electronegativity) and valence electron concentration (VEC) (number of valence electrons per atom filled into the valence band) for the alloying behavior of Nb-silicide based alloys (J Alloys Compd 748 (2018) 569), their solid solutions (J Alloys Compd 708 (2017) 961), the tetragonal Nb₅Si₃ (Materials 11 (2018) 69), and hexagonal C14-NbCr₂ and cubic A15-Nb₃X phases (Materials 11 (2018) 395) and eutectics with Nbss and Nb₅Si₃ (Materials 11 (2018) 592)...
May 18, 2018: Materials
Tomasz Durejko, Justyna Aniszewska, Michał Ziętala, Anna Antolak-Dudka, Tomasz Czujko, Robert A Varin, Vlad Paserin
The water-atomized ATOMET 28, 1001, 4701, and 4801 powders, manufactured by Rio Tinto Metal Powders, were used for additive manufacturing by a laser engineered net shaping (LENS) technique. Their overall morphology was globular and rounded with a size distribution from about 20 to 200 µm. Only the ATOMET 28 powder was characterized by a strong inhomogeneity of particle size and irregular polyhedral shape of powder particles with sharp edges. The powders were pre-sieved to a size distribution from 40 to 150 µm before LENS processing...
May 18, 2018: Materials
Franziska D H Wilke, Georg Schettler, Andrea Vieth-Hillebrand, Michael Kühn, Heike Rothe
The production of gas from unconventional resources became an important position in the world energy economics. In 2012, the European Commission's Joint Research Centre estimate 16 trillion cubic meters (Tcm) of technically recoverable shale gas in Europe. Taking into account that the exploitation of unconventional gas can be accompanied by serious health risks due to the release of toxic chemical components and natural occurring radionuclides into the return flow water and their near-surface accumulation in secondary precipitates, we investigated the release of U, Th and Ra from black shales by interaction with drilling fluids containing additives that are commonly employed for shale gas exploitation...
May 18, 2018: Journal of Environmental Radioactivity
Xiuying Zhang, Wuting Zhang, Xuehe Lu, Xuejun Liu, Dongmei Chen, Lei Liu, Xianjin Huang
This study detected the long-term trends in NO2 concentrations in China from 1997 to 2016 based on the NO2 columns from GOME, SCIAMACHY, and GOME-2A. Both differences in the time-overlapped NO2 columns from GOME vs. SCIAMACHAY and SCIAMACHAY vs. GOME-2A showed seasonal variations, and the annual NO2 columns from GOME were 0.9% higher than those from SCIAMACHY, which exceeded that from GOME-2A by 14%. The long-term trends of the NO2 columns on a provincial scale could be simulated by cubic models (0.60 < R2  < 0...
May 18, 2018: Science of the Total Environment
Mario Castro, Jonathan Corren, Ian D Pavord, Jorge Maspero, Sally Wenzel, Klaus F Rabe, William W Busse, Linda Ford, Lawrence Sher, J Mark FitzGerald, Constance Katelaris, Yuji Tohda, Bingzhi Zhang, Heribert Staudinger, Gianluca Pirozzi, Nikhil Amin, Marcella Ruddy, Bolanle Akinlade, Asif Khan, Jingdong Chao, Renata Martincova, Neil M H Graham, Jennifer D Hamilton, Brian N Swanson, Neil Stahl, George D Yancopoulos, Ariel Teper
Background Dupilumab is a fully human anti-interleukin-4 receptor α monoclonal antibody that blocks both interleukin-4 and interleukin-13 signaling. We assessed its efficacy and safety in patients with uncontrolled asthma. Methods We randomly assigned 1902 patients 12 years of age or older with uncontrolled asthma in a 2:2:1:1 ratio to receive add-on subcutaneous dupilumab at a dose of 200 or 300 mg every 2 weeks or matched-volume placebos for 52 weeks. The primary end points were the annualized rate of severe asthma exacerbations and the absolute change from baseline to week 12 in the forced expiratory volume in 1 second (FEV1 ) before bronchodilator use in the overall trial population...
May 21, 2018: New England Journal of Medicine
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