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https://www.readbyqxmd.com/read/28214750/propagation-of-thickness-shear-waves-in-a-periodically-corrugated-quartz-crystal-plate-and-its-application-exploration-in-acoustic-wave-filters
#1
Peng Li, Li Cheng
The propagation of thickness shear waves in a periodically corrugated quartz crystal plate is investigated in the present paper using a power series expansion technique. In the proposed simulation model, an equivalent continuity of shear stress moment is introduced as an approximation to handle sectional interfaces with abrupt thickness changes. The Bloch theory is applied to simulate the band structures for three different thickness variation patterns. It is shown that the power series expansion method exhibits good convergence and accuracy, in agreement with results by finite element method (FEM)...
February 7, 2017: Ultrasonics
https://www.readbyqxmd.com/read/28214719/host-guest-interaction-of-3-hydroxyflavone-and-7-hydroxyflavone-with-cucurbit-7-uril-a-spectroscopic-and-calorimetric-approach
#2
Sayeed Ashique Ahmed, Banibrata Maity, Soma Seth Duley, Debabrata Seth
The modulation of photophysical behaviour of small organic molecules in the presence of macrocycles is one of the most interesting areas of research. In this work we reported the interaction of two biologically active molecules 3-hydroxyflavone and 7-hydroxyflavone with macrocyclic host cucurbit [7]uril in aqueous medium. To investigate the change of photophysical properties of these two flavones, we have used steady state absorption, fluorescence, time resolved fluorescence emission spectroscopy and isothermal titration calorimetric technique...
February 9, 2017: Journal of Photochemistry and Photobiology. B, Biology
https://www.readbyqxmd.com/read/28214627/up-conversion-luminescence-in-yb-3-er-3-tm-3-co-doped-al2o3-tio2-nano-composites
#3
Teboho Patrick Mokoena, Ella Cebisa Linganiso, Vinod Kumar, Hendrik C Swart, So-Hye Cho, Odireleng Martin Ntwaeaborwa
The sol gel method was used to prepare rare-earths (Yb(3+)-Er(3+) and Yb(3+)-Tm(3+)) co-doped Al2O3-TiO2 nano-composite powder phosphors and their up-conversion luminescence properties were investigated. Mixed oxides of titania (TiO2) rutile phase and an early stage crystallization of alumina (Al2O3) phase were confirmed from the X-ray diffraction data with the average crystallite size of ∼36nm. The rutile phase TiO2 was further confirmed by selected area diffraction analysis of the composites. Microscopy analysis showed interesting rod-like morphologies with rough surfaces indicating that a spherulitic growth process took place during the crystal growth...
February 13, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28214579/motor-training-and-the-combination-of-action-observation-and-peripheral-nerve-stimulation-reciprocally-interfere-with-the-plastic-changes-induced-in-primary-motor-cortex-excitability
#4
Ambra Bisio, Laura Avanzino, Monica Biggio, Piero Ruggeri, Marco Bove
AO-PNS is a stimulation protocol combining action observation (AO) and peripheral nerve stimulation (PNS) to induce plasticity in the primary motor cortex (M1) (increased excitability). Another method to increase M1 excitability is motor training. The combination of two protocols, which individually induce long-term potentiation (LTP)-like plasticity in overlapping neural circuits, results in a transitory occlusion or reverse of this phenomenon. This study aimed to understand the neurophysiological mechanisms underlying AO-PNS by testing whether AO-PNS and motor training induced LTP-like plasticity in, at least partially, overlapping neural networks...
February 15, 2017: Neuroscience
https://www.readbyqxmd.com/read/28214516/saturation-of-long-term-potentiation-in-the-dorsal-cochlear-nucleus-and-its-pharmacological-reversal-in-an-experimental-model-of-tinnitus
#5
Thomas Tagoe, Daniel Deeping, Martine Hamann
Animal models have demonstrated that tinnitus is a pathology of dysfunctional excitability in the central auditory system, in particular in the dorsal cochlear nucleus (DCN) of the brainstem. We used a murine model and studied whether acoustic over-exposure leading to hearing loss and tinnitus, affects long-term potentiation (LTP) at DCN multisensory synapses. Whole cell and field potential recordings were used to study the effects on release probability and synaptic plasticity, respectively in brainstem slices...
February 15, 2017: Experimental Neurology
https://www.readbyqxmd.com/read/28214428/metal-metal-bond-excitation-in-colloidal-solution-of-nbs3
#6
Sofya B Artemkina, Ekaterina D Grayfer, Mariia N Kozlova, Svetlana G Kozlova, Maxim R Ryzhikov, Igor R Shein, Vladimir E Fedorov
For the first time the comparison of the theoretical and experimental data have shown that UV-vis absorption in the region of 600nm in colloidal solution of NbS3 can be described by the d-d electronic transitions to the antibonding molecular orbital. It is proved that the process leads to excitation of metal-metal bond.
February 5, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28214378/calcium-signaling-through-l-type-calcium-channels-role-in-pathophysiology-of-spinal-nociceptive-transmission
#7
REVIEW
Olivier Roca-Lapirot, Houda Radwani, Franck Aby, Frédéric Nagy, Marc Landry Pascal Fossat
L-type voltage-gated calcium channels (VGCCs) are ubiquitous channels in the central nervous system. L-type calcium channels (LTCs) are mostly post-synaptic channels regulating neuronal firing and gene expression. They play a role in important physio-pathological processes such as learning and memory, Parkinson's disease, autism and, as recognized more recently, in the pathophysiology of pain processes. Classically, the fundamental role of these channels in cardiovascular functions has limited the use of classical molecules to treat LTC-dependent disorders...
February 18, 2017: British Journal of Pharmacology
https://www.readbyqxmd.com/read/28213950/benchmark-performance-of-global-switching-versus-local-switching-for-trajectory-surface-hopping-molecular-dynamic-simulation-cis-trans-azobenzene-photoisomerization
#8
Ling Yue, Le Yu, Chao Xu, Yibo Lei, Yajun Liu, Chaoyuan Zhu
Newly developed global switching algorithm that does not require calculation of nonadiabatic coupling vector reduces computational cost significantly. However, there is a lack of extensive checking its accuracy for this simplest nonadiabatic molecular dynamic method in comparison with conventional Tully's fewest switches. It is very necessary to demonstrate how accurate global switching algorithm is. Extensive comparison between local and global switching on-the-fly trajectory surface hopping molecular dynamics is performed for cis-to-trans (800 sampling trajectories) and trans-to-cis (600 sampling trajectories) azobenzene photoisomerization at the OM2/MRCI level...
February 18, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28213718/reprogramming-cell-fates-by-small-molecules
#9
REVIEW
Xiaojie Ma, Linghao Kong, Saiyong Zhu
Reprogramming cell fates towards pluripotent stem cells and other cell types has revolutionized our understanding of cellular plasticity. During the last decade, transcription factors and microRNAs have become powerful reprogramming factors for modulating cell fates. Recently, many efforts are focused on reprogramming cell fates by non-viral and non-integrating chemical approaches. Small molecules not only are useful in generating desired cell types in vitro for various applications, such as disease modeling and cell-based transplantation, but also hold great promise to be further developed as drugs to stimulate patients' endogenous cells to repair and regenerate in vivo...
February 17, 2017: Protein & Cell
https://www.readbyqxmd.com/read/28213571/mir-146a-b-a-family-with-shared-seeds-and-different-roots
#10
Mark Paterson, Alison J Kriegel
MicroRNAs are small, non-coding, RNAs known for their powerful modulation of molecular processes, making them a major focus for studying pathological mechanisms. The human miR-146 family of microRNAs consists of two member genes - MIR146A and MIR146B These two miRNAs are located on different chromosomes and exhibit differential regulation in many cases. However, they are nearly identical in sequence and share a seed sequence, thus they are predicted to target the same set of genes. A large proportion of the miR-146 literature focuses on its role in regulating the innate immune response in the context of various pathologies by modulating two widely studied target genes in the toll-like receptor signaling cascade...
February 17, 2017: Physiological Genomics
https://www.readbyqxmd.com/read/28213520/cholesterol-up-regulates-neuronal-g-protein-gated-inwardly-rectifying-potassium-girk-channel-activity-in-the-hippocampus
#11
Anna N Bukiya, Serdar Durdagi, Sergei Noskov, Avia Rosenhouse-Dantsker
Hypercholesterolemia is a well-known risk factor for the development of neurodegenerative disease. However, the underlying mechanisms are mostly unknown. In recent years, it has become increasingly evident that cholesterol-driven effects on physiology and pathophysiology derive from its ability to alter the function of a variety of membrane proteins including ion channels. Yet, the effect of cholesterol on G protein-gated inwardly rectifying potassium (GIRK) channels expressed in the brain is unknown. GIRK channels mediate the actions of inhibitory brain neurotransmitters...
February 17, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28213518/deficits-in-the-activity-of-presynaptic-%C3%AE-aminobutyric-acid-type-b-receptors-contribute-to-altered-neuronal-excitability-in-fragile-x-syndrome
#12
Ji-Yong Kang, Jayashree Chadchankar, Thuy N Vien, Michelle I Mighdoll, Thomas M Hyde, Robert J Mather, Tarek Z Deeb, Menelas N Pangalos, Nicholas J Brandon, John Dunlop, Stephen J Moss
The behavioral and anatomical deficits seen in Fragile X syndrome (FXS) are widely believed to result from imbalances in the relative strengths of excitatory and inhibitory neurotransmission. While modified neuronal excitability is thought to be of significance, the contribution that alterations in GABAergic inhibition play in the pathophysiology of FXS are ill-defined. Slow sustained neuronal inhibition is mediated by γ-aminobutyric acid type B (GABAB) receptors, which are heterodimeric G-protein coupled receptors constructed from R1a and R2 or R1b and R2 subunits...
February 17, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28213516/rapid-regulation-of-sialidase-activity-in-response-to-neural-activity-and-sialic-acid-removal-during-memory-processing-in-rat-hippocampus
#13
Akira Minami, Yuko Meguro, Sayaka Ishibashi, Ami Ishii, Mako Shiratori, Saki Sai, Yuuki Horii, Hirotaka Shimizu, Hokuto Fukumoto, Sumika Shinba, Risa Taguchi, Tadanobu Takahashi, Tadamune Otsubo, Kiyoshi Ikeda, Takashi Suzuki
Sialidase cleaves sialic acids on the extracellular cell surface as well as inside the cell, and is necessary for normal long-term potentiation (LTP) at MF-CA3 pyramidal cell synapses and for hippocampus-dependent spatial memory. Here, we investigated in detail the role of sialidase in memory processing. Sialidase activity measured with 4MU-Neu5Ac or X-Neu5Ac and FRV LB was increased by high K(+)-induced membrane depolarization. Sialidase activity was also increased by chemical LTP induction with forskolin and activation of BDNF signaling, non-NMDARs or NMDARs...
February 17, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28213443/changes-in-appetitive-associative-strength-modulates-nucleus-accumbens-but-not-orbitofrontal-cortex-neuronal-ensemble-excitability
#14
Joseph Ziminski, Sabine Hessler, Gabriella Margetts-Smith, Meike C Sieburg, Hans S Crombag, Eisuke Koya
Cues that predict the availability of food rewards influence motivational states and elicit food-seeking behaviors. If a cue no longer predicts food availability, animals may adapt accordingly by inhibiting food seeking responses. Sparsely activated sets of neurons, coined neuronal ensembles, have been shown to encode the strength of reward-cue associations. While alterations in intrinsic excitability have been shown to underlie many learning and memory processes, little is known about these properties specifically on cue-activated neuronal ensembles...
February 17, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28213325/carbon-dots-based-fret-for-the-detection-of-dna-damage
#15
Jiri Kudr, Lukas Richtera, Kledi Xhaxhiu, David Hynek, Zbynek Heger, Ondrej Zitka, Vojtech Adam
Here, we aimed our attention at the synthesis of carbon dots (C-dots) with the ability to interact with DNA to suggest an approach for the detection of DNA damage. Primarily, C-dots modified with amine moieties were synthesized using the one-step microwave pyrolysis of citric acid in the presence of diethylenetriamine. The C-dots showed strong photoluminescence with a quantum yield of 4%. In addition, the C-dots (2.8±0.8nm) possessed a good colloidal stability and exhibited a positive surface charge (ζ=36mV) at a neutral pH...
February 9, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28213233/silver-nanoclusters-catalyzed-luminol-chemiluminescence-for-hydrogen-peroxide-and-uric-acid-detection
#16
Yingying Sheng, Hongli Yang, Ying Wang, Lu Han, Yanjun Zhao, Aiping Fan
In the present study, four kinds of bovine serum albumin (BSA) caped silver nanoclusters (Ag NCs) were prepared using different amount of BSA as template, respectively. The diameters of the four prepared BSA-Ag NCs were all less than 4nm which were obtained using high-resolution transmission electron microscopy (HRTEM). All of the BSA-Ag NCs showed catalytic activity in luminol-H2O2 chemiluminescent (CL) reaction. It was interesting that different CL kinetic curves were obtained in different BSA-Ag NCs catalyzed CL reaction...
May 1, 2017: Talanta
https://www.readbyqxmd.com/read/28213184/forensic-applications-fluorescence-properties-of-tooth-coloured-restorative-materials-using-a-fluorescence-dslr-camera
#17
Ramya Kiran, James Chapman, Alexander Forrest, Marc Tennant, Laurence J Walsh
The objective of this study was to compare the fluorescence properties of dry and wet samples of contemporary tooth-coloured restorative materials using a fluorescence based DSLR camera and a variety of LEDs emitting different wavelengths of visible light as excitation sources. The materials examined included resin composites; ceramics and hybrid restorative materials such as ormocers, Vita Enamic™ and resin reinforced glass-ionomer cements. The levels of fluorescence for each sample under different combinations of incident light wavelengths and filters was analysed by using histogram data for colour channels from Adobe Photoshop software...
February 3, 2017: Forensic Science International
https://www.readbyqxmd.com/read/28212803/calcium-channels-in-vascular-smooth-muscle
#18
D Ghosh, A U Syed, M P Prada, M A Nystoriak, L F Santana, M Nieves-Cintrón, M F Navedo
Calcium (Ca(2+)) plays a central role in excitation, contraction, transcription, and proliferation of vascular smooth muscle cells (VSMs). Precise regulation of intracellular Ca(2+) concentration ([Ca(2+)]i) is crucial for proper physiological VSM function. Studies over the last several decades have revealed that VSMs express a variety of Ca(2+)-permeable channels that orchestrate a dynamic, yet finely tuned regulation of [Ca(2+)]i. In this review, we discuss the major Ca(2+)-permeable channels expressed in VSM and their contribution to vascular physiology and pathology...
2017: Advances in Pharmacology
https://www.readbyqxmd.com/read/28212486/highly-efficient-and-anomalous-charge-transfer-in-van-der-waals-trilayer-semiconductors
#19
Frank Ceballos, Ming-Gang Ju, Samuel D Lane, Xiao Cheng Zeng, Hui Zhao
Two dimensional materials, such as graphene and monolayer transition metal dichalcogenides, allow the fabrication of multilayer structures without lattice matching restriction. A central issue in developing such artificial materials is to understand and control the interlayer electron transfer process, which plays a key role in harvesting their emergent properties. Recent photoluminescence and transient absorption measurements revealed that the electron transfer in hetero-bilayers occurs on ultrafast time scales...
February 17, 2017: Nano Letters
https://www.readbyqxmd.com/read/28212459/structural-studies-of-nicotinoids-cotinine-vs-nicotine
#20
Iciar Uriarte, Cristóbal Pérez, Elena Caballero-Mancebo, Francisco J Basterretxea, Alberto Lesarri, José A Fernández, Emilio J Cocinero
Nicotinoids are agonists of the acetylcholine receptor (nAChR) and play important biochemical and pharmacological roles. Here we report on the structural and conformational landscape of cotinine, and compare its molecular properties with the nicotine prototype, from which it only differs in the addition of a carbonyl group. The investigation of cotinine included a theoretical survey of the effects of rotamerization of the pyridine moiety, the puckering of the pyrrolidinone ring and the internal rotation of the methyl group...
February 17, 2017: Chemistry: a European Journal
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