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https://www.readbyqxmd.com/read/29792031/the-composition-in-the-interface-between-clay-mineral-surfaces-and-divalent-cation-electrolytes
#1
Stanislav Jelavić, A Rath Nielsen, S L S Stipp, N Bovet
The interfacial free energy of a solid, which determines its adsorption properties, depends on interactions between the surface and the fluid. A change in surface composition can completely change the behaviour of the solid. Decades of work have explored adsorption and its effects at solid-fluid interfaces from the macroscopic perspective and using molecular modelling so the concept of the electric double layer (EDL) is well established in the community. However, direct, molecular level, experimental observations of the composition within the interface region, and its change with time and conditions, is not abundant...
May 23, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/29792026/co-bridged-h-cluster-intermediates-in-the-catalytic-mechanism-of-fefe-hydrogenase-cai
#2
Michael W Ratzloff, Jacob H Artz, David W Mulder, Reuben T Collins, Thomas E Furtak, Paul W King
The [FeFe]-hydrogenases ([FeFe] H2 ases) catalyze reversible H2 activation at the H-cluster, which is composed of a [4Fe-4S]H subsite linked by a cysteine thiolate to a bridged, organometallic [2Fe-2S] ([2Fe]H ) subsite. Profoundly different geometric models of the H-cluster redox states that orchestrate the electron/proton transfer steps of H2 bond activation have been proposed. We have examined this question in the [FeFe] H2 ase I from Clostridium acetobutylicum (CaI) by Fourier-transform infrared (FTIR) spectroscopy with temperature annealing and H/D isotope exchange to identify the relevant redox states and define catalytic transitions...
May 23, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29782945/advances-in-the-slow-freezing-cryopreservation-of-microencapsulated-cells
#3
REVIEW
H Gurruchaga, L Saenz Del Burgo, R M Hernandez, G Orive, C Selden, B Fuller, J Ciriza, J L Pedraz
Over the past few decades, the use of cell microencapsulation technology has been promoted for a wide range of applications as sustained drug delivery systems or as cells containing biosystems for regenerative medicine. However, difficulty in their preservation and storage has limited their availability to healthcare centers. Because the preservation in cryogenic temperatures poses many biological and biophysical challenges and that the technology has not been well understood, the slow cooling cryopreservation, which is the most used technique worldwide, has not given full measure of its full potential application yet...
May 18, 2018: Journal of Controlled Release: Official Journal of the Controlled Release Society
https://www.readbyqxmd.com/read/29782797/low-temperature-synthesized-h-2-ti-3-o-7-nanotubes-with-a-high-co-2-adsorption-property-by-amine-modification
#4
Misaki Ota, Yuichiro Hirota, Yoshiaki Uchida, Yasuhiro Sakamoto, Norikazu Nishiyama
Carbon dioxide (CO2 ) capture and storage (CCS) technologies have been attracted attention in terms of tackling with global warming. To date, various CO2 capture technologies including solvents, membranes, cryogenics and solid adsorbents have been proposed. Currently, a liquid adsorption method for CO2 using amine solution (monoethanolamine) has been practically used. However, this liquid phase CO2 adsorption process requires heat regeneration, and it can cause many problems such as corrosion of equipment and degradation of the solution...
May 21, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/29782700/nonionic-dendritic-and-carbohydrate-based-amphiphiles-self-assembly-and-transport-behavior
#5
Suchita Prasad, Katharina Achazi, Boris Schade, Rainer Haag, Sunil K Sharma
Herein, a new series of non-ionic dendritic and carbohydrate based amphiphiles is synthesized employing biocompatible starting materials and studied for supramolecular aggregate formation in aqueous solution. The dendritic amphiphiles 12 and 13 possessing poly(glycerol) [G2.0] as hydrophilic unit and C-10 and C-18 hydrophobic alkyl chains, respectively, exhibit low critical aggregation concentration (CAC) in the order of 10-5 m and hydrodynamic diameters in the 8-10 nm range and supplemented by cryogenic transmission electron microscopy...
May 21, 2018: Macromolecular Bioscience
https://www.readbyqxmd.com/read/29781477/methyl-rotation-dynamics-in-metal-organic-frameworks-probed-with-terahertz-spectroscopy
#6
Qi Li, Adam J Zaczek, Timothy M Korter, J Axel Zeitler, Michael T Ruggiero
In ZIF-8 and its cobalt analogue ZIF-67, the imidazolate methyl-groups, which point directly into the void space, have been shown to freely rotate - even down to cryogenic temperatures. Using a combination of experimental terahertz time-domain spectroscopy, low-frequency Raman spectroscopy, and state-of-the-art ab initio simulations, the methyl-rotor dynamics in ZIF-8 and ZIF-67 are fully characterized within the context of a quantum-mechanical hindered-rotor model. The results lend insight into the fundamental origins of the experimentally observed methyl-rotor dynamics, and provide valuable insight into the nature of the weak interactions present within this important class of materials...
May 21, 2018: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/29779480/production-and-characterization-of-nanoparticle-based-hyaluronate-gel-containing-retinyl-palmitate-for-wound-healing
#7
Elisabetta Esposito, Alessandra Pecorelli, Maddalena Sguizzato, Markus Drechsler, Paolo Mariani, Federica Carducci, Franco Cervellati, Rita Cortesi, Giuseppe Valacchi
BACKGROUND: Wound healing is a biological process that can get in a state of pathologic inflammation, requiring the use of specific medications able to promote proper tissue repair. OBJECTIVE: The study describes the production and characterization of nanoparticle based gel for wound healing treatment designed to deliver hyaluronic acid and retinyl palmitate onto the skin. METHOD: Tristearin solid lipid nanoparticles and nanostructured lipid carriers based on a tristearin and caprylic/capric triglyceride mixture were produced and characterized...
May 18, 2018: Current Drug Delivery
https://www.readbyqxmd.com/read/29777992/18-years-of-continuous-observation-of-tritium-and-atmospheric-precipitations-in-ramnicu-valcea-romania-a-time-series-analysis
#8
Octavian G Duliu, Carmen Varlam, Muataz Dheyaa Shnawaw
To get more information on the origin of tritium and to evidence any possible presence of anthropogenic sources, between January 1999 and December 2016, the precipitation level and tritium concentration were monthly recorded and investigated by the Cryogenic Institute of Ramnicu Valcea, Romania. Compared with similar data covering a radius of about 1200 km westward, the measurements gave similar results concerning the time evolution of tritium content and precipitation level for the entire time interval excepting the period between 2009 and 2011 when the tritium concentrations showed a slight increase, most probable due to the activity of neighboring experimental pilot plant for tritium and deuterium separation...
May 16, 2018: Journal of Environmental Radioactivity
https://www.readbyqxmd.com/read/29770427/near-infrared-laser-mediated-modulation-of-ice-crystallization-by-two-dimensional-nanosheets-enables-high-survival-recovery-of-biological-cells-from-cryogenic-temperatures
#9
Fazil Panhwar, Zhongrong Chen, S M Chapal Hossain, Meng Wang, Zeeshan Haider, Kashan Memon, Pengpeng Chen, Gang Zhao
Two-dimensional (2D) graphene oxide (GO) and molybdenum disulfide (MoS2) nanosheets (NSs) have been widely used as photothermal agents and as potential carriers of antitumor drugs. Their spatial thermal effects have been extensively explored for use at physiological and hyperthermic temperatures (37 to 46 °C). Furthermore, the modulation of the spatial thermal distributions with these NSs may have even more profound applications in the microstructural control of biomaterials at cryogenic temperatures (-196 to 37 °C)...
May 17, 2018: Nanoscale
https://www.readbyqxmd.com/read/29770216/assessment-of-a-novel-cryoablation-device-for-the-endovascular-treatment-of-cardiac-tachyarrhythmias
#10
John M Baust, Anthony Robilotto, Peter Guerra, Kristi K Snyder, Robert G Van Buskirk, Marc Dubuc, John G Baust
Objectives: Cryoablation is an effective alternative treatment for cardiac arrhythmias offering shortened recovery and reduced side effects. As the use of cryoablation increases, the need for new devices and procedures has emerged. This has been driven by technological limitations including lengthy periods to generate a single lesion (3-5 min), uncertain transmurality, and differential efficacy. Furthermore, due to limited ablation capacity under high heat loads, cryo has had limited success in the treatment of ventricular arrhythmias...
2018: SAGE Open Medicine
https://www.readbyqxmd.com/read/29769577/ballasting-by-cryogenic-gypsum-enhances-carbon-export-in-a-phaeocystis-under-ice-bloom
#11
J E Wollenburg, C Katlein, G Nehrke, E-M Nöthig, J Matthiessen, D A Wolf-Gladrow, A Nikolopoulos, F Gázquez-Sanchez, L Rossmann, P Assmy, M Babin, F Bruyant, M Beaulieu, C Dybwad, I Peeken
Mineral ballasting enhances carbon export from the surface to the deep ocean; however, little is known about the role of this process in the ice-covered Arctic Ocean. Here, we propose gypsum ballasting as a new mechanism that likely facilitated enhanced vertical carbon export from an under-ice phytoplankton bloom dominated by the haptophyte Phaeocystis. In the spring 2015 abundant gypsum crystals embedded in Phaeocystis aggregates were collected throughout the water column and on the sea floor at a depth below 2 km...
May 16, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29768016/cisplatin-encapsulation-generates-morphologically-different-multi-compartments-in-the-internal-nanostructures-of-non-lamellar-liquid-crystalline-self-assemblies
#12
Intan Diana Mat Azmi, Jesper Ostergaard, Stefan Sturup, Bente Gammelgaard, Arto Urtti, Seyed Moein Moghimi, Anan Yaghmur
Cisplatin (cis-diamminedichloroplatinum (II)) is among the most potent cytotoxic agents used in cancer chemotherapy. The encapsulation of cisplatin in lipid-based drug carriers has been challenging owing to its low solubility in both aqueous and lipid phases. Here, we investigated cisplatin encapsulation in non-lamellar liquid crystalline (LC) nanodispersions formed from a ternary mixture of phytantriol (PHYT), vitamin E (Vit E) and an anionic phospholipid [either phosphatidylglycerol (DSPG) or phosphatidylserine (DPPS)]...
May 16, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/29766038/frontal-eye-field-inactivation-reduces-saccade-preparation-in-the-superior-colliculus-but-does-not-alter-how-preparatory-activity-relates-to-saccades-of-a-given-latency
#13
Suryadeep Dash, Tyler R Peel, Stephen G Lomber, Brian D Corneil
A neural correlate for saccadic reaction times (SRTs) in the gap saccade task is the level of low-frequency activity in the intermediate layers of the superior colliculus (iSC) just before visual target onset: greater levels of such preparatory iSC low-frequency activity precede shorter SRTs. The frontal eye fields (FEFs) are one likely source of iSC preparatory activity, since FEF preparatory activity is also inversely related to SRT. To better understand the FEF's role in saccade preparation, and the way in which such preparation relates to SRT, in two male rhesus monkeys, we compared iSC preparatory activity across unilateral reversible cryogenic inactivation of the FEF...
March 2018: ENeuro
https://www.readbyqxmd.com/read/29758539/bulk-and-dispersed-aqueous-behaviour-of-an-endogenous-lipid-selachyl-alcohol-effect-of-tween-80-and-pluronic-f127-on-nanostructure
#14
Mohammad Younus, Adrian Hawley, Ben J Boyd, Shakila B Rizwan
Tween 80 has been reported to provide a means of targeting drug nanocarriers to the blood- brain barrier. This study investigated the influence of addition of Tween 80 on the formation of different bulk and dispersed lyotropic liquid crystalline phases in selachyl alcohol-based systems. The effect of increasing concentrations of Tween 80 and Pluronic F127 (as a control) (0-25% w/w relative to SA) on the bulk phase behaviour and dispersions of selachyl alcohol (SA) were investigated using small angle X-ray scattering, dynamic light scattering, and cryogenic transmission electron microscopy...
May 7, 2018: Colloids and Surfaces. B, Biointerfaces
https://www.readbyqxmd.com/read/29755744/enzyme-catalysis-captured-using-multiple-structures-from-one-crystal-at-varying-temperatures
#15
Sam Horrell, Demet Kekilli, Kakali Sen, Robin L Owen, Florian S N Dworkowski, Svetlana V Antonyuk, Thomas W Keal, Chin W Yong, Robert R Eady, S Samar Hasnain, Richard W Strange, Michael A Hough
High-resolution crystal structures of enzymes in relevant redox states have transformed our understanding of enzyme catalysis. Recent developments have demonstrated that X-rays can be used, via the generation of solvated electrons, to drive reactions in crystals at cryogenic temperatures (100 K) to generate 'structural movies' of enzyme reactions. However, a serious limitation at these temperatures is that protein conformational motion can be significantly supressed. Here, the recently developed MSOX (multiple serial structures from one crystal) approach has been applied to nitrite-bound copper nitrite reductase at room temperature and at 190 K, close to the glass transition...
May 1, 2018: IUCrJ
https://www.readbyqxmd.com/read/29754486/nanoparticle-wettability-influences-nanoparticle-phospholipid-interactions
#16
Nagarjun Konduru, Flavia Damiani, Svetla Stoilova-McPhie, Jason Tresback, Georgios Pyrgiotakis, Thomas C Donaghey, Philip Demokritou, Joseph Brain, Ramon M Molina
We explored the influence of nanoparticle (NP) surface charge and hydrophobicity on nanoparticle-biomolecule interactions by measuring the composition of adsorbed phospholipids on four NPs, namely positively charged CeO2 and ZnO, and negatively charged BaSO4 and silica-coated CeO2 after exposure to bronchoalveolar lavage fluid (BALf) obtained from rats, and to a mixture of neutral dipalmitoyl phosphatidylcholine (DPPC) and negatively charged dipalmitoyl phosphatidic acid (DPPA). The resulting NP-lipid interactions were examined by cryogenic transmission electron microscopy (cryo-TEM) and by atomic force microscopy (AFM)...
May 12, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/29752974/a-study-of-cryogenic-tissue-engineered-liver-slices-in-calcium-alginate-gel-for-drug-testing
#17
Ruomeng Chen, Bo Wang, Yaxiong Liu, Rong Lin, Jiankang He, Dichen Li
To address issues such as transportation and the time-consuming nature of tissue-engineered liver for use as an effective drug metabolism and toxicity testing model, "ready-to-use" cryogenic tissue-engineered liver needs to be studied. The research developed a cryogenic tissue-engineered liver slice (TELS), which comprised of HepG2 cells and calcium alginate gel. Cell viability and liver-specific functions were examined after different cryopreservation and recovery culture times. Then, cryogenic TELSs were used as a drug-testing model and treated with Gefitinib...
May 9, 2018: Cryobiology
https://www.readbyqxmd.com/read/29751428/molecular-composition-of-raw-peat-and-humic-substances-from-permafrost-peat-soils-of-european-northeast-russia-as-climate-change-markers
#18
Roman Vasilevich, Evgeny Lodygin, Vasily Beznosikov, Evgeny Abakumov
Humic substances (HSs) from the mire peat soils of the forest-tundra zone of the European northeast part of Russia have been characterized in terms of molecular composition. This was accomplished using solid-state 13 C nuclear magnetic resonance (13 C NMR) techniques and electron spin resonance (ESR) spectroscopy. The composition depended on the intensity of cryogenic processes in the active layer, the quality of the humification precursors (the degree of peat material transformation), and the biochemical selection of aromatic fragments during humification...
February 15, 2018: Science of the Total Environment
https://www.readbyqxmd.com/read/29749974/design-of-sparse-halbach-magnet-arrays-for-portable-mri-using-a-genetic-algorithm
#19
Clarissa Zimmerman Cooley, Melissa W Haskell, Stephen F Cauley, Charlotte Sappo, Cristen D Lapierre, Christopher G Ha, Jason P Stockmann, Lawrence L Wald
Permanent magnet arrays offer several attributes attractive for the development of a low-cost portable MRI scanner for brain imaging. They offer the potential for a relatively lightweight, low to mid-field system with no cryogenics, a small fringe field, and no electrical power requirements or heat dissipation needs. The cylindrical Halbach array, however, requires external shimming or mechanical adjustments to produce B0 fields with standard MRI homogeneity levels (e.g., 0.1 ppm over FOV), particularly when constrained or truncated geometries are needed, such as a head-only magnet where the magnet length is constrained by the shoulders...
January 2018: IEEE Transactions on Magnetics
https://www.readbyqxmd.com/read/29746100/combining-ion-mobility-and-cryogenic-spectroscopy-for-structural-and-analytical-studies-of-biomolecular-ions
#20
Michael Z Kamrath, Thomas R Rizzo
Ion mobility spectrometry (IMS) has become a valuable tool in biophysical and bioanalytical chemistry because of its ability to separate and characterize the structure of gas-phase biomolecular ions on the basis of their collisional cross section (CCS). Its importance has grown with the realization that in many cases, biomolecular ions retain important structural characteristics when produced in the gas phase by electrospray ionization (ESI). While a CCS can help distinguish between structures of radically different types, one cannot expect a single number to differentiate similar conformations of a complex molecule...
May 10, 2018: Accounts of Chemical Research
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