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Thomas Meier, Saiana Khandarkhaeva, Sylvain Petitgirard, Thomas Körber, Alexander Lauerer, Ernst Rössler, Leonid Dubrovinsky
The past 15 years have seen an astonishing increase in Nuclear Magnetic Resonance (NMR) sensitivity and accessible pressure range in high-pressure NMR experiments, owing to a series of new developments of NMR spectroscopy applied to the diamond anvil cell (DAC). Recently, with the application of electro-magnetic lenses, so-called Lenz lenses, in toroidal diamond indenter cells, pressures of up to 72 GPa with NMR spin sensitivities of about 1012  spin/Hz1/2 has been achieved. Here, we describe the implementation of a refined NMR resonator structure using a pair of double stage Lenz lenses driven by a Helmholtz coil within a standard DAC, allowing to measure sample volumes as small as 100 pl prior to compression...
May 14, 2018: Journal of Magnetic Resonance
Amalia Maria Paschou, Maria Katsikini, Dimitrios Christofilos, John Arvanitidis, Sotirios Ves
The high pressure response of type-I collagen from bovine Achilles tendon is investigated with micro-Raman spectroscopy. Fluorinert™ and methanol-ethanol mixtures were used as pressure transmitting media (PTM) in a diamond anvil cell. The Raman spectrum of collagen is dominated by three bands centred at approximately 1450, 1660 and 2930 cm-1 , attributed to C-H deformation, C=O stretching of the peptide bond (amide-I band) and C-H stretching modes, respectively. Upon pressure increase, using Fluorinert™ as PTM, a shift towards higher frequencies of the C-H stretching and deformation peaks is observed...
May 18, 2018: FEBS Journal
Maxim Bykov, Elena Bykova, Egor Koemets, Timofey Fedotenko, Georgios Aprilis, Konstantin Glazyrin, Hanns-Peter Liermann, Alena V Ponomareva, Johan Tidholm, Ferenc Tasnádi, Igor A Abrikosov, Natalia Dubrovinskaia, Leonid Dubrovinsky
A novel nitrogen-rich compound, ReN8·xN2, was synthesized via a direct reaction between rhenium and nitrogen at high pressure and high temperature in a laser-heated diamond anvil cell. Single-crystal X-ray diffraction revealed that the crystal structure, which is based on the ReN8 framework, has rectangular-shaped channels that accommodate nitrogen molecules. Thus, despite a very high synthesis pressure, exceeding 100 GPa, ReN8·xN2 is an inclusion compound. The amount of trapped nitrogen (x) depends on the synthesis conditions...
May 18, 2018: Angewandte Chemie
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
Ambika Mathur, Annmarie Cano, Michael Kohl, Nisansala S Muthunayake, Prassanna Vaidyanathan, Mary E Wood, Mustafa Ziyad
It has long been thought that biomedical doctoral students pursue careers primarily as tenure-track/tenured faculty at research institutions. Recent reports showed, however, that the majority of biomedical doctoral alumni engage in a variety of careers. Wayne State University (WSU) undertook a project to understand the career trajectories of its biomedical doctoral alumni to create programs to better prepare its students for careers in multiple pathways. Data were collected on career outcomes of WSU's biomedical doctoral alumni who graduated in a 15-year period from 1999-2014...
2018: PloS One
Chan Gao, Xueyong Zhang, Chuanchao Zhang, Zhilei Sui, Meng Hou, Rucheng Dai, Zhongping Wang, Xianxu Zheng, Zengming Zhang
Herein, pressure-induced phase transitions of RDX up to 50 GPa were systematically studied under different compression conditions. Precise phase transition points were obtained based on high-quality Raman spectra with small pressure intervals. This favors the correctness of the theoretical formula for detonation and the design of a precision weapon. The experimental results indicated that α-RDX immediately transformed to γ-RDX at 3.5 GPa due to hydrostatic conditions and possible interaction between the penetrating helium and RDX, with helium gas as the pressure-transmitting medium (PTM)...
May 17, 2018: Physical Chemistry Chemical Physics: PCCP
Shasha Li, Chen Wang, Yue Chen
Phonon-phonon coupling in body centered cubic (bcc) sodium is studied from first-principles to investigate its anharmonic lattice dynamics under high pressures. The renormalization of the phonon frequencies of the transverse acoustic (TA) modes along the Γ-N direction is found to be distinctly different compared with other phonon modes. We find that these TA modes firstly stiffen with increasing external pressure below 30 GPa; however, at higher pressures, these TA modes exhibit a nonmonotonic behavior and soften unexpectedly...
May 17, 2018: Physical Chemistry Chemical Physics: PCCP
A Kurnosov, H Marquardt, D J Frost, T Boffa Ballaran, L Ziberna
In Extended Data Table 1 of this Letter, some of the elastic constants were reported incorrectly. This occurred as a result of an error in the script used to generate the numbers. The values of the elastic constants at room pressure cited in the manuscript on page 544 were derived using the same erroneous script, and the correct values and 1σ-uncertainties in the last given digit are C11 = 461.3(17) GPa instead of 462.7(17) GPa; C22 = 509.7(26) GPa instead of 504.9(26) GPa; C33 = 425.7(5) GPa instead of 426...
May 16, 2018: Nature
Omar Irfan, Haris Khan, Zarrar Khan, Alina Ashraf, Rimsha Ahmed, Javaid Ahmad Khan, Ali Bin Sarwar Zubairi
OBJECTIVE: Granulomatosis with Polyangiitis (GPA) is an autoimmune, multi-system, small and medium vessel vasculitis with granulomatous inflammation. Aim of this study was to assess the clinical and radiological presentations of patients with GPA amongst the Pakistani population. It is a single centre retrospective single observation study. RESULTS: Study was conducted at the Aga Khan University Hospital, Karachi with records were reviewed from January 2000 to December 2017...
May 16, 2018: BMC Research Notes
Tokushi Kizuka, Kou Watanabe, Daisuke Matsuura, Toshio Konno, Shuichi Shimomura, Takatsugu Wakahara, Kun'ichi Miyazawa
Crystalline nanowhiskers (NWs) composed of fullerene C60 and C70 molecules, i.e., alloy NWs, were synthesized by a liquid-liquid interfacial precipitation method. The nominal composition of C70 ranged from 0 to 40 mass%. The bending tests of the alloy NWs were performed inside a high-resolution transmission electron microscope, and the deformation behavior was observed in situ. The bending force acting on the NWs were measured simultaneously by an optical deflection method, and the Young's modulus was estimated from the resulting force-flexure curves...
January 1, 2018: Journal of Nanoscience and Nanotechnology
Kristine F Frederiksen, Kacper Januchta, Nerea Mascaraque, Randall E Youngman, Mathieu Bauchy, Sylwester J Rzoska, Michal Bockowski, Morten M Smedskjaer
Alkali aluminoborate glasses have recently been shown to exhibit a very high threshold for indentation cracking compared to other bulk oxide glasses. However, to enable the use of these materials in engineering applications, there is a need to improve their hardness by tuning the chemical composition. In this study, we substitute alkaline earth for alkali network-modifying species at fixed aluminoborate base glass composition and correlate it with changes in structure, mechanical properties, and densification behavior...
May 16, 2018: Journal of Physical Chemistry. B
Dezhi Gao, Jie Jing, Jincheng Yu, Xue Guo, Yubai Zhang, Hongyu Gong, Yujun Zhang
B4 C ceramics with different contents of graphene platelets (GPL) were synthesized by a pressureless process in Ar atmosphere. The influences of GPL on mechanical properties, thermal conductivity and electrical resistivity of the B4 C ceramics were investigated. Mechanical properties ran up to optimal condition with hardness of 29.1 GPa, bending strength of 383.9 GPa and fracture toughness of 5.72 MPa m1/2 with 0.8 wt% GPL separately. Thermal conductivity and electrical resistivity reached extreme values of 26...
April 2018: Royal Society Open Science
Akitoshi Nakano, Kento Sugawara, Shinya Tamura, Naoyuki Katayama, Kazuyuki Matsubayashi, Taku Okada, Yoshiya Uwatoko, Kouji Munakata, Akiko Nakao, Hajime Sagayama, Reiji Kumai, Kunihisa Sugimoto, Naoyuki Maejima, Akihiko Machida, Tetsu Watanuki, Hiroshi Sawa
The crystal structure of the excitonic insulator Ta2 NiSe5 has been investigated under a range of pressures, as determined by the complementary analysis of both single-crystal and powder synchrotron X-ray diffraction measurements. The monoclinic ambient-pressure excitonic insulator phase II transforms upon warming or under a modest pressure to give the semiconducting C -centred orthorhombic phase I. At higher pressures ( i.e. >3 GPa), transformation to the primitive orthorhombic semimetal phase III occurs...
March 1, 2018: IUCrJ
Yonggang Wang, Jianjun Ying, Zhengyang Zhou, Junliang Sun, Ting Wen, Yannan Zhou, Nana Li, Qian Zhang, Fei Han, Yuming Xiao, Paul Chow, Wenge Yang, Viktor V Struzhkin, Yusheng Zhao, Ho-Kwang Mao
The discovery of iron-based superconductors (FeSCs), with the highest transition temperature (Tc ) up to 55 K, has attracted worldwide research efforts over the past ten years. So far, all these FeSCs structurally adopt FeSe-type layers with a square iron lattice and superconductivity can be generated by either chemical doping or external pressure. Herein, we report the observation of superconductivity in an iron-based honeycomb lattice via pressure-driven spin-crossover. Under compression, the layered FePX3 (X = S, Se) simultaneously undergo large in-plane lattice collapses, abrupt spin-crossovers, and insulator-metal transitions...
May 15, 2018: Nature Communications
Qingqing Xu, Sujit S Sansgiry
INTRODUCTION: The physical activity (PA) behavior and its association with academic performance has not been examined among professional pharmacy (PharmD) students in didactic years. METHODS: A survey was administered to a cohort of PharmD students at University of Houston that collected information related to each student's PA and grade point average (GPA). Correlation analyses and multiple regression were performed to evaluate factors associated with GPA. RESULTS: The response rate was 58...
March 2018: Currents in Pharmacy Teaching & Learning
Federico A Gorelli, Simone De Panfilis, Taras Bryk, Lorenzo Ulivi, Gaston Garbarino, Paraskevas Parisiades, Mario Santoro
We investigated the atomic structure of liquid Rb along an isothermal path at 573 K, up to 23 GPa, by x-ray diffraction measurements. By rising pressure, we observed a liquid-liquid transformation between a simple metallic liquid, to a complex one. The transition occurs at 7.5 ± 1 GPa which is slightly above the first maximum of the T-P melting line. This transformation is traced back to the density induced hybridization of highest electronic orbitals leading to the accumulation of valence electrons between Rb atoms and to the formation of interstitial atomic shells, a behavior that Rb shares with Cs and is likely to be common to all alkali metals...
May 15, 2018: Journal of Physical Chemistry Letters
Chunye Zhu, Wenjun Zhu, Yanqiang Yang
Searching for high-energy-density materials is of great interest in scientific research and for industrial applications. Using an unbiased structure prediction method and first-principles calculations, we investigated the phase stability of LiBN2 from 0 to100 GPa. Two new structures with space groups P4̅21 m and Pnma were discovered. The theoretical calculations revealed that Pnma LiBN2 is stable with respect to a mixture of 1 /3 Li3 N, BN, and 1 /3 N2 above 22 GPa. The electronic band structure revealed that Pnma LiBN2 has an indirect band gap of 2...
May 15, 2018: Inorganic Chemistry
Xu Zhen, Guangbin Cheng, Hongwei Yang, Jiaheng Zhang, Jean'ne M Shreeve
3-Nitro-4-(5-nitro-1,2,4-triazol-3-yl)furazan (2), N,N'-bis(trinitroethyl)-3,5'-diamino-4-(1,2,4-triazol-3-yl)furazan (3), N,N'-bis(trinitroethyl)-3,5'-dinitramino-4-(1,2,4-triazol-3-yl)furazan (4) and eighteen nitrogen-rich salts (5a, 5b,5d⁓5i, 5g-1, 6a⁓6i) were designed and synthesized. These 4-(1,2,4-triazole-5-yl)furazan derivatives were fully characterized by IR and NMR spectra, elemental analysis, and differential scanning calorimetry (DSC). The solid-state structures of 2, 5d, 5e, 5h, 5g-1, 6g, and 6i were confirmed via single crystal X-ray analysis...
May 15, 2018: Chemistry: a European Journal
Yunxiang Bai, Rufan Zhang, Xuan Ye, Zhenxing Zhu, Huanhuan Xie, Boyuan Shen, Dali Cai, Bofei Liu, Chenxi Zhang, Zhao Jia, Shenli Zhang, Xide Li, Fei Wei
Carbon nanotubes (CNTs) are one of the strongest known materials. When assembled into fibres, however, their strength becomes impaired by defects, impurities, random orientations and discontinuous lengths. Fabricating CNT fibres with strength reaching that of a single CNT has been an enduring challenge. Here, we demonstrate the fabrication of CNT bundles (CNTBs) that are centimetres long with tensile strength over 80 GPa using ultralong defect-free CNTs. The tensile strength of CNTBs is controlled by the Daniels effect owing to the non-uniformity of the initial strains in the components...
May 14, 2018: Nature Nanotechnology
Zachary S Wallace, Rachel Wallwork, Yuqing Zhang, Na Lu, Frank Cortazar, John L Niles, Eliot Heher, John H Stone, Hyon K Choi
BACKGROUND: Renal transplantation is the optimal treatment for selected patients with end-stage renal disease (ESRD). However, the survival benefit of renal transplantation among patients with ESRD attributed to granulomatosis with polyangiitis (GPA) is unknown. METHODS: We identified patients from the United States Renal Data System with ESRD due to GPA (ESRD-GPA) between 1995 and 2014. We restricted our analysis to waitlisted subjects to evaluate the impact of transplantation on mortality...
May 14, 2018: Annals of the Rheumatic Diseases
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