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Chao Zhong, Fang Cheng, Yingkui Zhu, Zhen Gao, Honghua Jia, Ping Wei
Quaternary ammonium hydroxide (QAH) solution has been used to dissolve cellulose and made great progress in recent years. While, its cellulose dissolution mechanism is still in unclear. Here, series of QAH with varied cationic alkyl chains were chosen for the investigation. The solubility of cellulose in QAH was measured, which allowed us to study the effect of cationic structure on cellulose dissolution. Also, the Kamlet-Taft parameters as well as 1D and 2D NMR analyses of QAH-cellulose/cellobiose system were measured...
October 15, 2017: Carbohydrate Polymers
Martin Mittendorff, Ryan J Suess, Edward Leong, Thomas E Murphy
Photoconductive antennas are widely used for time-resolved detection of THz pulses. In contrast to photothermoelectric or bolometric THz detection, the coherent detection allows direct measurement of the electric field transient of a THz pulse, which contains both, spectral and phase information. In this letter we demonstrate for the first time photoconductive detection of free-space propagating THz radiation with thin flakes of a van der Waals material. Mechanically exfoliated flakes of black phosphorus are combined with an antenna that concentrates the THz fields to the small flake (~10 μm)...
August 18, 2017: Nano Letters
Nozomi Watanabe, Keishi Suga, Hiroshi Umakoshi
Bilayer vesicles have garnered considerable research attention as molecular vehicles capable of noncovalent interaction with biomolecules via electrostatic and hydrophobic bonds, and van der Waals interactions. Guanidinium strongly interacts with phosphate groups. Thus, guanidinium modification of vesicles helps intensify the interaction between lipid membranes and nucleic acids. Here, two kinds of guanidinium derivatives, stearylguanidinium (SG) and myristoylarginine (MA), were synthesized and incorporated into 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC) vesicles...
August 18, 2017: Journal of Physical Chemistry. B
Christine E Webb, Teresa Romero, Becca Franks, Frans B M de Waal
In contrast to a wealth of human studies, little is known about the ontogeny and consistency of empathy-related capacities in other species. Consolation-post-conflict affiliation from uninvolved bystanders to distressed others-is a suggested marker of empathetic concern in non-human animals. Using longitudinal data comprising nearly a decade of observations on over 3000 conflict interactions in 44 chimpanzees (Pan troglodytes), we provide evidence for relatively stable individual differences in consolation behaviour...
August 18, 2017: Nature Communications
Himanshu Popat, Kristy P Robledo, Lucille Sebastian, Nicholas Evans, Andrew Gill, Martin Kluckow, Sanjay Sinhal, Koert de Waal, William Tarnow-Mordi, David Osborn
OBJECTIVE: Functional cardiac ultrasound measures are used clinically and in trials for assessing the haemodynamic status of newborn infants. Superior vena cava (SVC) flow and right ventricular output (RVO) are established measures of systemic blood flow on the first postnatal day. The objective was to assess image quality and interobserver agreement of these measures in preterm infants enrolled in a randomised trial of immediate versus delayed cord clamping. DESIGN AND SETTING: Image quality and interobserver agreement for SVC flow, RVO and ductus arteriosus (DA) size were assessed on measurements taken at 3-6, 6-12 and 20-28 hours for the first 10 infants enrolled at each of four sites (total 40)...
August 17, 2017: Archives of Disease in Childhood. Fetal and Neonatal Edition
Michal Brylinski
The ability to design and fine-tune non-covalent interactions between organic ligands and proteins is indispensable to rational drug development. Aromatic stacking has long been recognized as one of the key constituents of ligand-protein interfaces. In this communication, we employ a two-parameter geometric model to conduct a large-scale statistical analysis of aromatic contacts in the experimental and computer-generated structures of ligand-protein complexes, considering various combinations of aromatic amino acid residues and ligand rings...
August 17, 2017: Chemical Biology & Drug Design
Edinaldo N da Silva, Paulo A B da Silva, Angélica E Graminha, Pollyanna F de Oliveira, Jaqueline L Damasceno, Denise C Tavares, Alzir A Batista, Gustavo Von Poelhsitz
The complexes cis-[Ru(quin)(dppm)2]PF6 and cis-[Ru(kynu)(dppm)2]PF6 (quin = quinaldate; kynu = kynurenate; dppm = bis(diphenylphosphino)methane) were prepared and characterized by elemental analysis, electronic, FTIR, (1)H, and (31)P{(1)H} NMR spectroscopies. Characterization data were consistent with a cis arrangement for the dppm ligands and a bidentate coordination through carboxylate oxygens of the quin and kynu anions. These complexes were not able to intercalate CT-DNA as shown by circular dichroism spectroscopy...
2017: Bioinorganic Chemistry and Applications
M M Bumby, M C Williams, J C A Steyl, R Harrison-White, H Lutermann, G T Fosgate, P J de Waal, J Mitha, S J Clift
BACKGROUND: The pathology of spirocercosis, a disease caused by the infestation of carnivores with the nematode Spirocerca lupi, has been extensively described in domestic dogs and coyotes. However, it has not been described in wild carnivores in South Africa. The aim of this study was to evaluate whether black-backed jackals are a host for Spirocerca species and to provide a detailed description of the associated pathology. Jackals were also stratified according to age and the Spirocerca species recovered were characterized using molecular techniques...
August 16, 2017: BMC Veterinary Research
Thomas Schmaltz, Bastian Gothe, Andreas Krause, Susanne Leitherer, Hans-Georg Steinrück, Michael Thoss, Timothy Clark, Marcus Halik
Self-assembled monolayer field-effect transistors (SAMFETs) are not only a promising type of organic electronic device but also allow detailed analyses of structure-property correlations. The influence of the morphology on the charge transport is particularly pronounced, due to the confined monolayer of 2D-π-stacked organic semiconductor molecules. The morphology, in turn, is governed by relatively weak van-der-Waals interactions and is thus prone to dynamic structural fluctuations. Accordingly, combining electronic and physical characterization and time-averaged X-ray analyses with the dynamic information available at atomic resolution from simulations allows us to characterize self-assembled monolayer (SAM) based devices in great detail...
August 18, 2017: ACS Nano
Somaye Shahraki, Ali Heydari
Ligand binding studies on carrier proteins are crucial in determining the pharmacological properties of drug candidates. Here, a new palladium(II) complex was synthesized and characterized. The in vitro binding studies of this complexwith two carrier proteins, human serum albumin (HSA) and β-lactoglobulin (βLG) was investigated by employing biophysical techniques as well as computational modeling. The experimental results showed thatthe Pd(II) complex interacted with two carrier proteins with moderate binding affinity (Kb ~̴ 0...
August 16, 2017: Journal of Biomolecular Structure & Dynamics
M Gurram, S Omar, B J van Wees
We study spin transport in a fully hBN encapsulated monolayer-graphene van der Waals heterostructure at room temperature. A top-layer of bilayer-hBN is used as a tunnel barrier for spin-injection and detection in graphene with ferromagnetic cobalt electrodes. We report surprisingly large and bias-induced (differential) spin-injection (detection) polarizations up to 50% (135%) at a positive voltage bias of + 0.6 V, as well as sign inverted polarizations up to -70% (-60%) at a reverse bias of -0.4 V. This demonstrates the potential of bilayer-hBN tunnel barriers for practical graphene spintronics applications...
August 15, 2017: Nature Communications
Can Wang, Dongmei Niu, Haipeng Xie, Baoxing Liu, Shitan Wang, Menglong Zhu, Yongli Gao
The electronic structure at the organic-inorganic semiconductor interface of π-conjugated copper phthalocyanine (CuPc) on a black phosphorus (BP) crystal surface is studied with photoemission spectroscopy and density functional theory calculations. From the photoemission spectra, we observe a shift of about 0.7 eV for the highest occupied molecular orbital, which originates from the transition of phase in the organic molecular thin film (from the interface phase to the bulk phase). On the other hand, we find 0...
August 14, 2017: Journal of Chemical Physics
Aldona Minecka, Ewa Kamińska, Magdalena Tarnacka, Andrzej Dzienia, Olga Madejczyk, Patrycja Waliłko, Anna Kasprzycka, Kamil Kamiński, Marian Paluch
In this paper, broadband dielectric spectroscopy was applied to investigate molecular dynamics of 1,2,3,4,6-penta-O-(trimethylsilyl)-D-glucopyranose (S-GLU) at ambient and elevated pressures. Our studies showed that apart from the structural relaxation, one well resolved asymmetric secondary process (initially labeled as β) is observed in the spectra measured at p = 0.1 MPa. Analysis with the use of the coupling model and criterion proposed by Ngai and Capaccioli indicated that the β-process in S-GLU is probably a Johari-Goldstein relaxation of intermolecular origin...
August 14, 2017: Journal of Chemical Physics
Cijun Shuai, Hang Sun, Chengde Gao, Pei Feng, Wang Guo, Youwen Yang, Mingchun Zhao, Sheng Yang, Fulai Yuan, Shuping Peng
The inherent brittleness of bioceramics restricts their applications in load bearing implant, although they possess good biocompatibility and bioactivity. In this study, molybdenum disulfide nanoplatelets (MSNPs) were used to reinforce bioceramics (Mg2SiO4/CaSiO3) scaffolds fabricated by selective laser sintering (SLS). The fracture mode of scaffolds was transformed from transgranular to mixed trans- and intergranular. It could be explained that MSNPs could slide easily due to their weak interlayer van der Waals interactions and provide elastic deformation due to their high elastic modulus...
July 20, 2017: Journal of the Mechanical Behavior of Biomedical Materials
Siyuan Dai, Qiong Ma, Yafang Yang, Jeremy Rosenfeld, Michael D Goldflam, Alex McLeod, Zhiyuan Sun, Trond I Andersen, Zhe Fei, Mengkun Liu, Yinming Shao, Kenji Watanabe, Takashi Taniguchi, Mark Thiemens, Fritz Keilmann, Pablo Jarillo-Herrero, Michael M Fogler, D N Basov
We investigated phonon-polaritons in hexagonal boron nitride-a naturally hyperbolic van der Waals material-by means of the scattering-type scanning near-field optical microscopy. Real-space nanoimages we have obtained detail how the polaritons are launched when the light incident on a thin hexagonal boron nitride slab is scattered by various intrinsic and extrinsic inhomogeneities, including sample edges, metallic nanodisks deposited on its top surface, random defects, and surface impurities. The scanned tip of the near-field microscope is itself a polariton launcher whose efficiency proves to be superior to all the other types of polariton launchers we studied...
August 17, 2017: Nano Letters
Dmitry Vasilievich Korabel'nikov, Yuriy N Zhuravlev
The structural and electronic properties of oxyanionic crystalline hydrates, LiNO3•3H2O, LiClO4•3H2O and NaClO4•H2O, have been studied using density functional theory including van der Waals interactions. It is established that the linear compressibility of lithium perchlorate trihydrate is anisotropic (a < c) and positive, while lithium nitrate trihydrate and sodium perchlorate monohydrate demonstrate negative linear compressibility along the b and c- axes, respectively. Deformation of Ow-H•••O hydrogen bonding motifs is correlated with the negative linear compressibility...
August 14, 2017: Journal of Physical Chemistry. A
Ramin Ekhteiari Salmas, Yusuf Serhat Is, Serdar Durdagi, Matthias Stein, Mine Yurtsever
The dopamine D2 Receptor (D2R) is a member of the G-Protein Coupled Receptor (GPCR) family and plays a critical role in neurotransmission activities in the human brain. Dysfunction in dopamine receptor signaling may lead to mental health illnesses such as schizophrenia and Parkinson's disease. D2R is the target protein of the commonly used anti-psychotic drugs such as risperidone, clozapine, aripiprazole, olanzapine, ziprasidone and quetiapine. Due to their significant side effects and nonselective profiles, the discovery of novel drugs has become a challenge for researchers working in this field...
August 14, 2017: Journal of Biomolecular Structure & Dynamics
Zhepeng Zhang, Jingjing Niu, Pengfei Yang, Yue Gong, Qingqing Ji, Jianping Shi, Qiyi Fang, Shaolong Jiang, He Li, Xiebo Zhou, Lin Gu, Xiaosong Wu, Yanfeng Zhang
2D metallic transition-metal dichalcogenides (MTMDs) have recently emerged as a new class of materials for the engineering of novel electronic phases, 2D superconductors, magnets, as well as novel electronic applications. However, the mechanical exfoliation route is predominantly used to obtain such metallic 2D flakes, but the batch production remains challenging. Herein, the van der Waals epitaxial growth of monocrystalline, 1T-phase, few-layer metallic VSe2 nanosheets on an atomically flat mica substrate via a "one-step" chemical vapor deposition method is reported...
August 14, 2017: Advanced Materials
H Fashandi, C-C Lai, M Dahlqvist, J Lu, J Rosen, L Hultman, G Greczynski, M Andersson, A Lloyd Spetz, P Eklund
Incorporation of layers of noble metals in non-van der Waals layered materials may be used to form novel layered compounds. Recently, we demonstrated a high-temperature-induced exchange process of Au with Si in the layered phase Ti3SiC2, resulting in the formation of Ti3AuC2 and Ti3Au2C2. Here, we generalize this technique showing that Au/Ti2AlC and Au/Ti3AlC2 undergo an exchange reaction at 650 °C to form Ti2Au2C and Ti3Au2C2 and determine their structures by electron microscopy, X-ray diffraction, and ab initio calculations...
August 14, 2017: Chemical Communications: Chem Comm
Jun Kyun Oh, Spencer T Behmer, Richelle Marquess, Cengiz Yegin, Ethan A Scholar, Mustafa Akbulut
This study investigates the structural properties of the hind leg femur-tibia joint in adult katydids (Orthoptera: Tettigoniidae), including its tribological and mechanical properties. It is of particular interest because the orthopteran (e.g., grasshoppers, crickets, and katydids) hind leg is highly specialized for jumping. We show that the katydid hind leg femur-tibia joint had unique surfaces and textures, with a friction coefficient (μ) at its coupling surface of 0.053 ± 0.001. Importantly, the sheared surfaces at this joint showed no sign of wear or damage, even though it had undergone thousands of external shearing cycles...
August 9, 2017: Acta Biomaterialia
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