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Saeid Zarei, Mahmood Niad, Hossein Raanaei
In this study, we have attempted to extract cellulose from Cystoseria myricaas algae. Nanocellulose, Fe3O4 and Fe3O4-nanocellulose compounds are synthesized by acid hydrolysis and co-precipitation as well as sol-gel methods The synthesized compounds are characterized by x-ray diffraction, transmission electron microscopy, particle size distribution (PSD), scanning electron microscopy (SEM),energy dispersive x-ray spectroscopy, vibrating sample magnetometer and Fourier transform infrared spectroscopy. The Hg (II) uptake on Fe3O4-nanocellulose is investigated by 14 isotherm models, 12 kinetic models, adsorption activation energy as well as thermodynamic of adsorption...
October 12, 2017: Journal of Hazardous Materials
Ssu-Han Yang, Tsung-Ming Yang, Hui-Ling Lin, Ying-Huang Tsai, Tien-Pei Fang, Gwo-Hwa Wan
BACKGROUND: Few studies have evaluated the size distribution of inhaled and exhaled aerosolized drugs, or the effect of heated humidification on particle size and lung deposition. The present study evaluated these aspects of bronchodilator (salbutamol/ipratropium) delivery using a lung model in the absence and presence of heat and humidification. METHODS: We positioned filters to collect and measure the initial drug, inhaled drug, and exhaled drug. Particle size distribution was evaluated using an 8-stage Marple personal cascade impactor with 0...
October 17, 2017: Pulmonary Pharmacology & Therapeutics
Vladimir Pelmenschikov, James A Birrell, Cindy C Pham, Nakul Mishra, Hongxin Wang, Constanze Sommer, Edward Reijerse, Casseday P Richers, Kenji Tamasaku, Yoshitaka Yoda, Thomas B Rauchfuss, Wolfgang Lubitz, Stephen P Cramer
[FeFe]-hydrogenases are metalloenzymes that reversibly reduce protons to molecular hydrogen at an exceptionally high rate. We have characterized the catalytically competent hydride state in the [FeFe]-hydrogenases from Chlamydomonas reinhardtii and Desulfovibrio desulfuricans using 57Fe Nuclear Resonance Vibrational Spectroscopy (NRVS) and Density Functional Theory (DFT). H/D exchange identified two Fe-H bending modes originating from the binuclear iron cofactor. DFT calculations showed that these spectral features result from an iron-bound terminal hydride, with the Fe-H vibrational frequencies highly dependent on interactions between the hydride and the pendant amine base of the adt cofactor as well as the conserved cysteine terminating the proton transfer chain to the active site...
October 20, 2017: Journal of the American Chemical Society
Antoniu-Oreste Gostian, Martin Sylvester Otte, David Pazen, Magdalene Ortmann, David Schwarz, Karl Bernd Hüttenbrink, Dirk Beutner
HYPOTHESIS: The vibration of the floating mass transducer (FMT) of a single active middle-ear implant (AMEI) is distinctly influenced by the properties of the material coupled to its back side. BACKGROUND: In round window vibroplasty, the FMT needs to be padded against the surrounding bone opposite from the round window membrane. This represents one factor influencing its performance as a round window driver. Therefore, we examined the effects of different materials linked to the back side of an FMT on its vibration range...
October 20, 2017: Clinical Otolaryngology
Ramachandran Gnanasekaran
Vibrational energy diffusivities between the residues present in Amicyanin copper protein are calculated and presented in form of communication map. From those results energy flow pathways from the copper metal ion to the inter protein residue Glu31 are identified. Our finding suggests many different pathways are possible and copper metal ion in oxidized and reduced state switches the pathways. Our finding also suggests the cooperative nature of surrounding residues and water molecules towards selecting the pathways...
October 8, 2017: Journal of Molecular Graphics & Modelling
Moon-Ki Choi, Soojin Jo, Byung Ho Lee, Min Hyeok Kim, Jae Boong Choi, Kyunghoon Kim, Moon Ki Kim
At the base of a flagellar motor, its rotational direction and speed are regulated by the interaction between rotor and stator proteins. A switching event occurs when the cytoplasmic rotor protein, called C-ring, changes its conformation in response to binding of the CheY signal protein. The C-ring structure consists of FliG, FliM, and FliN proteins and its conformational changes in FliM and FliG including HelixMC play an important role in switching the motor direction. Therefore, clarifying their dynamic properties as well as conformational changes is a key to understanding the switching mechanism of the motor protein...
October 5, 2017: Journal of Molecular Graphics & Modelling
Beom-Chan Lee, Alberto Fung, Timothy A Thrasher
A coding scheme for earlier versions of vibrotactile biofeedback systems for balance-related applications was primarily binary in nature, either off or on at a given threshold (range of postural tilt), making it unable to convey information about error magnitude. The purpose of this study was to explore the effects of two coding schemes (binary vs. continuous) for vibrotactile biofeedback during dynamic weight-shifting exercises that are common physical therapists' recommended balance exercises used in clinical settings...
October 16, 2017: IEEE Transactions on Neural Systems and Rehabilitation Engineering
Zach N Nilsson, Brian L Mandella, Kakali Sen, Demet Kekilli, Michael A Hough, Pierre Moënne-Loccoz, Richard W Strange, Colin R Andrew
Nitrite coordination to heme cofactors is a key step in the anaerobic production of the signaling molecule nitric oxide (NO). An ambidentate ligand, nitrite has the potential to coordinate via the N- (nitro) or O- (nitrito) atoms in a manner that can direct its reactivity. Distinguishing nitro vs nitrito coordination, along with the influence of the surrounding protein, is therefore of particular interest. In this study, we probed Fe(III) heme-nitrite coordination in Alcaligenes xylosoxidans cytochrome c' (AXCP), an NO carrier that excludes anions in its native state but that readily binds nitrite (Kd ∼ 0...
October 20, 2017: Inorganic Chemistry
Ángel Vidal-Vidal, Olalla Nieto Faza, Carlos Silva López
In a first step towards the rational design of macrocyclic structures optimized for CO2 capture, we have systematically explored the potential of 30 five-membered aromatic heterocycles to establish coordinating complexes with this pollutant. The interactions between the two moieties are studied in several orientations and the obtained complexes analyzed in terms of its electron density and vibrational fingerprint. The former is aided to provide an in depth knowledge of the interaction whereas the latter should help to select structural motifs that have not only good complexation properties but also diagnostic spectroscopic signals...
October 20, 2017: Journal of Physical Chemistry. A
Zheng Dong, Hongyu Zhou, Peng Tao
OBJECTIVES: PAS domains are widespread in archaea, bacteria and eukaryota, and play important roles in various functions. In this study, we aim to explore functional evolutionary relationship among proteins in the PAS domain superfamily in view of the sequence-structure-dynamics-function relationship. METHODS: We collected protein sequences and crystal structures data from RCSB Protein Data Bank of the PAS domain superfamily belonging to three biological functions (nucleotide binding, photoreceptor activity and transferase activity)...
October 20, 2017: Protein Science: a Publication of the Protein Society
Nhung H A Nguyen, Mohamed S A Darwish, Ivan Stibor, Pavel Kejzlar, Alena Ševců
The most challenging task in the preparation of magnetic poly(N-isopropylacrylamide) (Fe3O4-PNIPAAm) nanocomposites for bio-applications is to maximise their reactivity and stability. Emulsion polymerisation, in situ precipitation and physical addition were used to produce Fe3O4-PNIPAAm-1, Fe3O4-PNIPAAm-2 and Fe3O4-PNIPAAm-3, respectively. Their properties were characterised using scanning electron microscopy (morphology), zeta-potential (surface charge), thermogravimetric analysis (stability), vibrating sample magnetometry (magnetisation) and dynamic light scattering...
October 19, 2017: Nanoscale Research Letters
Satish Kumar Iyemperumal, N Aaron Deskins
Catalytic reduction of carbon dioxide to useful chemicals is a potent way to mitigate this greenhouse gas, but the challenge lies in finding active reduction catalysts. Using density functional theory we studied CO2 activation over TiO2-supported Cu clusters of size 1-4 atoms. The linear to bent transformation of CO2 is necessary for activation, and we found that all the clusters stabilized bent CO2, along with a significant gain of electrons on the CO2 (indicative of activation). On all the TiO2 supported Cu clusters, the interfacial sites were found to stabilize the bent CO2 adsorption, where the active site of adsorption on Cu dimer, trimer and tetramer was on the Cu atom farthest away from the TiO2 surface...
October 20, 2017: Physical Chemistry Chemical Physics: PCCP
William E Perreault, Nandini Mukherjee, Richard N Zare
Measurement of vector correlations in molecular scattering is an indispensable tool for mapping out interaction potentials. In a coexpanded supersonic beam, we have studied the rotationally inelastic process wherein deuterium hydride (HD) (v = 1, j = 2) collides with molecular deuterium (D2) to form HD (v = 1, j = 1), where v and j are the vibrational and rotational quantum numbers, respectively. HD (v = 1, j = 2) was prepared by Stark-induced adiabatic Raman passage, with its bond axis aligned preferentially parallel or perpendicular to the lab-fixed relative velocity...
October 20, 2017: Science
Jessalyn A DeVine, Marissa L Weichman, Benjamin Laws, Jing Chang, Mark C Babin, Garikoitz Balerdi, Changjian Xie, Christopher L Malbon, W Carl Lineberger, David R Yarkony, Robert W Field, Stephen T Gibson, Jianyi Ma, Hua Guo, Daniel M Neumark
Vinylidene-acetylene isomerization is the prototypical example of a 1,2-hydrogen shift, one of the most important classes of isomerization reactions in organic chemistry. This reaction was investigated with quantum state specificity by high-resolution photoelectron spectroscopy of the vinylidene anions H2CC- and D2CC- and quantum dynamics calculations. Peaks in the photoelectron spectra are considerably narrower than in previous work and reveal subtleties in the isomerization dynamics of neutral vinylidene, as well as vibronic coupling with an excited state of vinylidene...
October 20, 2017: Science
S Sahmani, M M Aghdam
The unique geometry with high surface ratio makes lipid micro/nano-tubules as an excellent self-assembled supramolecular structure in various biological applications such as controllable release systems and drug delivery. In the present study, the size-dependent nonlinear vibrations of axially loaded lipid micro/nano tubules associated with the both prebuckling and postbuckling domains are explored comprehensively. To accomplish this purpose, the nonlocal strain gradient theory of elasticity including simultaneously two entirely different features of size dependency is utilized within the framework of the third-order shear deformable beam model...
October 9, 2017: Journal of Biomechanics
Jiahao Jiang, Yafei Xiao, Wenjuan Huang, Peixin Gong, Shuhua Peng, Jianping He, Minmin Fan, Ke Wang
Although ionic liquids have been well established as effective solvents for the dissolution and processing of natural cellulose fibers, the detailed dissolution mechanism at the molecular level still remains unclear. Herein, the turbidimetric measurement showed that the solubility of cellulose in 1-allyl-3-methyl imidazolium chloride (AmimCl) decreased with increasing temperature. The temperature dependence of the OH stretching vibration band of cellulose in AmimCl was investigated by infrared spectroscopy...
December 15, 2017: Carbohydrate Polymers
Michael L Whittaker, Paul J M Smeets, Hasti Asayesh-Ardakani, Reza Shahbazian-Yassar, Derk Joester
We report the direct observation of amorphous barium carbonate (ABC), which transforms into a previously unknown barium carbonate hydrate we call gortatowskite within a few hundred milliseconds of formation. In situ X-ray scattering, cryo-, and low-dose electron microscopy were used to capture the transformation of nanoparticulate ABC into gortatowskite crystals, highly anisotropic sheets that are up to 1 µm in width, yet only ~10 nm in thickness. Recrystallization of gortatowskite to witherite starts within 30 seconds...
October 19, 2017: Angewandte Chemie
Fadıl Iyikanat, Ali Kandemir, Hediye Duygu Ozaydin, R T Senger, Hasan Sahin
First-principles calculations based on density-functional theory are used to investigate the effects of hydrogenation on the structural, vibrational, thermal and electronic properties of the charge density wave (CDW) phase of single-layer TiSe2 . It is found that hydrogenation of single-layer TiSe2 is possible through adsorption of a H atom on each Se site. Our total energy and phonon calculations reveal that a structural phase transition occurs from the CDW phase to the Td phase upon full hydrogenation...
October 19, 2017: Nanotechnology
Gerrit Renner, Torsten C Schmidt, Jürgen Schram
One key step studying interactions of microplastics with our ecological system is to identify plastics within environmental samples. Ageing processes and surface contamination especially with biofilms impede this characterisation. A complex and time consuming cleaning procedure is a common solution for this problem. However, it implies an artificial change of sample composition with a risk of losing important information or even damaging microplastic particles. In the present work, we introduce a new chemometric approach to identify heavily weathered and contaminated microplastics without any cleaning...
October 19, 2017: Analytical Chemistry
Andre Van Rynbach, George Schwartz, Robert F Spivey, James Joseph, Geert Vrijsen, Jungsang Kim
We have fabricated and characterized laser-ablated micromirrors on fused silica substrates for constructing stable Fabry-Perot optical cavities. We highlight several design features which allow these cavities to have lengths in the 250-300 μm range and be integrated directly with surface ion traps. We present a method to calculate the optical mode shape and losses of these micromirror cavities as functions of cavity length and mirror shape, and confirm that our simulation model is in good agreement with experimental measurements of the intracavity optical mode at a test wavelength of 780 nm...
August 10, 2017: Applied Optics
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