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https://www.readbyqxmd.com/read/28107705/incorporation-of-antimicrobial-peptides-in-nanostructured-lipid-membrane-mimetic-bilayer-cubosomes
#1
Thomas G Meikle, Alexandru Zabara, Lynne J Waddington, Frances Separovic, Calum J Drummond, Charlotte E Conn
The inverse bicontinuous lipidic cubic phase offers a simple and robust membrane mimetic with the ability to encapsulate peptides, potentially increasing bioavailability, while also offering a platform from which functionalized, targeted nanoparticles can be developed. Herein we have investigated the use of a number of cubic phase nanoparticle systems with encapsulated antimicrobial peptides gramicidin A', melittin, and alamethicin. The optimal peptide loading ranges, over which cubic symmetry was retained, were determined using small angle X-ray scattering...
January 8, 2017: Colloids and Surfaces. B, Biointerfaces
https://www.readbyqxmd.com/read/28106271/mapping-the-intermediate-digestion-phases-of-human-healthy-intestinal-contents-from-distal-ileum-and-caecum-at-fasted-and-fed-state-conditions
#2
Thuy Tran, Dimitrios G Fatouros, Maria Vertzoni, Christos Reppas, Anette Müllertz
OBJECTIVES: To investigate at the ultrastructural level, the colloidal phases formed in the lumen of the distal ileum and caecum of healthy adults. METHODS: Cryogenic transmission electron microscopy (Cryo-TEM) was employed to image the intermediate colloidal phases of human intestinal contents collected from distal ileum and caecum of two healthy volunteers under fasted and fed state conditions. KEY FINDINGS: In samples collected both in the fasted and fed states, Cryo-TEM study revealed the presence of large spherical unilamellar and occasionally bi-lamellar and oligolamellar vesicles with diameters ranging from 50 to 200 nm for both volunteers in distal ileum and caecum...
January 20, 2017: Journal of Pharmacy and Pharmacology
https://www.readbyqxmd.com/read/28098305/phase-behaviour-and-temperature-responsive-properties-of-a-gemini-surfactant-brij-30-water-system
#3
Chuanhong Han, Yan Guo, Xiaoxiao Chen, Meihuan Yao, Yingtian Zhang, Qirui Zhang, Xilian Wei
The phase behaviour of a ternary system composed of cationic gemini surfactant 2-hydroxypropyl-1,3-bis(myristyldimethylammonium chloride) (14-3(OH)-14(2Cl)), nonionic surfactant polyoxyethylene laurel ether (C12H25(OCH2CH2)10OH, Brij-30) and H2O was studied and its phase diagram was determined. In several different phase regions identified in the phase diagram, the viscoelastic worm-like micellar solution region was investigated. The focus of the investigation was the increase in the viscosity of the micellar solution with the temperature and the Brij-30 content, as suggested by a partial region of the triangular phase diagram...
January 18, 2017: Soft Matter
https://www.readbyqxmd.com/read/28094898/polyelectrolyte-oil-core-nanocarriers-for-localized-and-sustained-delivery-of-daunorubicin-to-colon-carcinoma-mc38-cells-the-case-of-polysaccharide-multilayer-film-in-relation-to-peg-ylated-shell
#4
Urszula Bazylińska, Jadwiga Pietkiewicz, Joanna Rossowska, Grzegorz Chodaczek, Andrzej Gamian, Kazimiera A Wilk
The authors examine properties of daunorubicin (DNR)-loaded oil-core multilayer nanocapsules prepared via layer-by-layer approach with different polyelectrolyte (PE) coatings such as a standard one (containing polysodium 4-styrenesulphonate/poly(diallyldimethyl-ammonium) chloride) and a polysaccharide-based shell (dextran/chitosan), in regard to the outer layer of poly-l-glutamic acid (PGA) grafted with polyethylene glycol (PGA-g-PEG). The nanocarriers are obtained on a cationic nanoemulsion template (stabilized by dicephalic-type surfactant, N,N-bis[3,30-(trimethylammonio)propyl]-dodecanamide dimethylsulfate) and layered with the PE shell of different thicknesses resulting in average size of 150 nm in diameter (as shown by dynamic light scattering, scanning electron microscopy and cryogenic-transmission electron microscopy, and atomic force microscopy)...
January 17, 2017: Macromolecular Bioscience
https://www.readbyqxmd.com/read/28094515/nanoporous-materials-for-the-onboard-storage-of-natural-gas
#5
K Vasanth Kumar, Kathrin Preuss, Maria-Magdalena Titirici, Francisco Rodríguez-Reinoso
Climate change, global warming, urban air pollution, energy supply uncertainty and depletion, and rising costs of conventional energy sources are, among others, potential socioeconomic threats that our community faces today. Transportation is one of the primary sectors contributing to oil consumption and global warming, and natural gas (NG) is considered to be a relatively clean transportation fuel that can significantly improve local air quality, reduce greenhouse-gas emissions, and decrease the energy dependency on oil sources...
January 17, 2017: Chemical Reviews
https://www.readbyqxmd.com/read/28088857/methane-activation-by-tantalum-carbide-cluster-anions-ta2c4
#6
Hai-Fang Li, Yan-Xia Zhao, Zhen Yuan, Qing-Yu Liu, Zi-Yu Li, Xiao-Na Li, Chuan-Gang Ning, Shenggui He
Methane activation by transition metals is of fundamental interest and practical importance, as this process is extensively involved in the natural gas conversion to fuels and value-added chemicals. While single-metal centers have been well recognized as active sites for methane activation, the active center composed of two or more metal atoms is rarely addressed and the detailed reaction mechanism remains unclear. Here, by using state-of-the-art time-of-flight mass spectrometry, cryogenic anion photoelectron imaging spectroscopy, and quantum chemical calculations, the cooperation of the two Ta atoms in a dinuclear carbide cluster Ta2C4- for methane activation has been identified...
January 16, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28078764/photoisomerization-of-a-chiral-imine-molecular-switch-followed-by-matrix-isolation-vcd-spectroscopy
#7
Corina H Pollok, Tim Riesebeck, Christian Merten
Characterizing the stereochemistry of transient photoisomerization products remains a big challenge for the design of molecular machines, such as unidirectional molecular motors. Often these states are not stable long enough to be characterized in detail using conventional spectroscopic tools. The structurally simple camphorquinone imine 1 serves to illustrate the advantage of combining the matrix-isolation technique with vibrational circular dichroism (VCD) spectroscopy for the investigation of photoisomerizations of chiral molecules...
January 12, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28074625/heterocumulene-sulfinyl-radical-ocnso
#8
Zhuang Wu, Qifan Liu, Jian Xu, Hailong Sun, Dingqing Li, Chao Song, Diego M Andrada, Gernot Frenking, Tarek Trabelsi, Joseph S Francisco, Xiaoqing Zeng
Neutral five-atomic cumulenes formally consisting of two pseudohalogens (e.g., NCO, NNN, NSO) by sharing the central nitrogen atom are exotic species that have been barely studied. Through flash vacuum pyrolysis of CF3 S(O)NCO at ca. 1200 K, sulfinyl isocyanate, bearing resonance structures of O=C-N=S=O and O=C=N-S=O, has been generated in the gas phase and subsequently characterized in cryogenic matrices (Ar and N2 ). Its reversible conformational (syn and anti) interconversion and photodecomposition were observed...
January 11, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28071777/radical-recombination-in-interstellar-ices-a-not-so-simple-mechanism
#9
Teddy Butscher, Fabrice Duvernay, Albert Rimola, Mireia Segado-Centellas, Thierry Chiavassa
Many complex organic molecules (hereafter COMs) have been detected in different regions of the interstellar medium (ISM). In each region, different energetic processes - UV irradiation, atom bombardments, etc. - that could be linked to the formation of detected COMs may occur depending on the environment. Several formation mechanisms were proposed but increasing attention is paid to radical recombination reactions. Previous studies showed that glycolaldehyde (HC(O)CH2OH) and ethylene glycol (HOCH2CH2OH) are formed by radical recombination between HC˙O and ˙CH2OH, and by ˙CH2OH dimerisation, respectively...
January 10, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28068518/impact-of-space-environment-on-stability-of-medicines-challenges-and-prospects
#10
REVIEW
Priti Mehta, Dhara Bhayani
To upkeep health of astronauts in a unique, isolated, and extreme environment of space is the primary goal for a successful space mission, hence, safe and efficacious medications are essential for the wellness of astronauts. Space medication has been challenged with problems related to efficacy. Along with altered physiology, one of the possible reasons could be instability of space medications in the presence of harsh spaceflight environmental conditions. Altered physical and chemical stability can result in reduced potency which can result in reduced efficacy...
January 3, 2017: Journal of Pharmaceutical and Biomedical Analysis
https://www.readbyqxmd.com/read/28068317/cryogenic-optical-localization-provides-3d-protein-structure-data-with-angstrom-resolution
#11
Siegfried Weisenburger, Daniel Boening, Benjamin Schomburg, Karin Giller, Stefan Becker, Christian Griesinger, Vahid Sandoghdar
We introduce Cryogenic Optical Localization in 3D (COLD), a method to localize multiple fluorescent sites within a single small protein with Angstrom resolution. We demonstrate COLD by determining the conformational state of the cytosolic Per-ARNT-Sim domain from the histidine kinase CitA of Geobacillus thermodenitrificans and resolving the four biotin sites of streptavidin. COLD provides quantitative 3D information about small- to medium-sized biomolecules on the Angstrom scale and complements other techniques in structural biology...
January 9, 2017: Nature Methods
https://www.readbyqxmd.com/read/28063960/effect-of-trehalose-as-an-additive-to-dimethyl-sulfoxide-solutions-on-ice-formation-cellular-viability-and-metabolism
#12
Jason Solocinski, Quinn Osgood, Mian Wang, Aaron Connolly, Michael A Menze, Nilay Chakraborty
Cryopreservation is the only established method for long-term preservation of cells and cellular material. This technique involves preservation of cells and cellular components in the presence of cryoprotective agents (CPAs) at liquid nitrogen temperatures (-196 °C). The organic solvent dimethyl sulfoxide (Me2SO) is one of the most commonly utilized CPAs and has been used with various levels of success depending on the type of cells. In recent years, to improve cryogenic outcomes, the non-reducing disaccharide trehalose has been used as an additive to Me2SO-based freezing solutions...
January 4, 2017: Cryobiology
https://www.readbyqxmd.com/read/28060705/cross-spectrum-pm-noise-measurements-thermal-energy-and-metamaterial-filters
#13
Yannick Gruson, Vincent Giordano, Ulrich L Rohde, Ajay Kumar Poddar, Enrico Rubiola
Virtually all commercial instruments for the measurement of the oscillator PM noise make use of the Cross Spectrum method (arXiv:1004.5539 [physics.ins-det], 2010). High sensitivity is achieved by correlation and averaging on two equal channels which measure the same input, and reject the background of the instrument. We show that a systematic error is always present if the thermal energy of the input power splitter is not accounted for. Such error can result in noise under estimation up to a few dB in the lowest-noise quartz oscillators, and in an invalid measurement in the case of cryogenic oscillators...
January 4, 2017: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://www.readbyqxmd.com/read/28060510/coordination-dependent-spectroscopic-signatures-of-divalent-metal-ion-binding-to-carboxylate-head-groups-h2-and-he-tagged-vibrational-spectra-of-m-2-%C3%A2-rco2%C3%A2-m-mg-and-ca-r-cd3-cd2cd3-complexes
#14
Joseph W DePalma, Patrick J Kelleher, Laís C Tavares, Mark A Johnson
We explore the intramolecular distortions present in divalent metal ion-carboxylate ion pairs using vibrational spectroscopy of the cryogenically cooled, mass-selected species isolated in the gas phase. The spectral signatures of the C-O stretching modes are identified using the perdeutero isotopologues of the acetate and propionate anions to avoid congestion arising from the CH2 fundamentals. Both Ca(2+) and Mg(2+) are observed to bind in a symmetrical, so-called "bidentate" arrangement to the -CO2¯ group...
January 19, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28059424/interactions-of-methanol-ethanol-and-1-propanol-with-polar-and-nonpolar-species-in-water-at-cryogenic-temperatures
#15
Ryutaro Souda
Methanol is known as a strong inhibitor of hydrate formation, but clathrate hydrates of ethanol and 1-propanol can be formed in the presence of help gases. To elucidate the hydrophilic and hydrophobic effects of alcohols, their interactions with simple solute species are investigated in glassy, liquid, and crystalline water using temperature-programmed desorption and time-of-flight secondary ion mass spectrometry. Nonpolar solute species embedded underneath amorphous solid water films are released during crystallization, but they tend to withstand water crystallization under the coexistence of methanol additives...
January 18, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28059385/investigation-of-hollow-cylindrical-metal-terahertz-waveguides-suitable-for-cryogenic-environments
#16
R Wallis, R Degl Innocenti, D S Jessop, O Mitrofanov, C M Bledt, J E Melzer, J A Harrington, H E Beere, D A Ritchie
The field of terahertz (THz) waveguides continues to grow rapidly, with many being tailored to suit the specific demands of a particular final application. Here, we explore waveguides capable of enabling efficient and accurate power delivery within cryogenic environments (< 4 K). The performance of extruded hollow cylindrical metal waveguides made of un-annealed and annealed copper, as well as stainless steel, have been investigated for bore diameters between 1.75 - 4.6 mm, and at frequencies of 2.0, 2.85 and 3...
December 26, 2016: Optics Express
https://www.readbyqxmd.com/read/28055037/advances-in-the-field-of-single-particle-cryo-electron-microscopy-over-the-last-decade
#17
Joachim Frank
In single-particle cryo-electron microscopy (cryo-EM), molecules suspended in a thin aqueous layer are rapidly frozen and imaged at cryogenic temperature in the transmission electron microscope. From the random projection views, a three-dimensional image is reconstructed, enabling the structure of the molecule to be obtained. In this article I discuss technological progress over the past decade, which has, in my own field of study, culminated in the determination of ribosome structure at 2.5-Å resolution. I also discuss likely future improvements in methodology...
February 2017: Nature Protocols
https://www.readbyqxmd.com/read/28054680/interfacial-water-on-organic-substrates-at-cryogenic-temperatures-hydrogen-bonding-and-quantification-in-the-submonolayer-regime
#18
D Houdoux, J Houplin, L Amiaud, A Lafosse, C Dablemont
Water molecules were used to probe the physical and chemical properties of a model hydrophilic organic organized layer. To this end, H2O adsorption on mercaptoundecanoic acid self-assembled monolayers (SAMs) was investigated at the molecular level under ultra-high vacuum by high resolution electron energy loss spectroscopy (HREELS), through the sensitivity of the water OH stretching modes to the molecular environment. The water interfacial layer formation and structure were studied upon deposition at 28 K. A direct sensitive quantification in the submonolayer regime (10-80% of completion) was achieved by the sole measurement of the OH stretching mode frequencies, and the dominant basic (-COO(-))/acidic (-COOH) forms of the terminal functions could be probed...
January 18, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28050956/the-effects-of-storing-and-transporting-cryopreserved-semen-samples-on-dry-ice
#19
David Til, Vera L L Amaral, Rafael A Salvador, Alfred Senn, Thais S de Paula
OBJECTIVE: This study aimed to test the effects on sperm viability of transporting cryopreserved semen samples on dry ice. METHODS: Twenty normozoospermic semen samples were cryopreserved and divided into five groups. The samples in Group 1 were immersed in liquid nitrogen throughout the experiment in cryogenic storage tanks; the cryopreserved straws in Group 2 were placed in a Styrofoam box containing dry ice and kept under these conditions for 48 hours; the samples in Group 3 were kept for 48 hours on dry ice under the same conditions as the Group 2 samples, and were then moved to a storage tank filled with liquid nitrogen; Group 4 samples were also kept for 48 hours in dry ice storage, and the Styrofoam box containing the samples was shipped by plane to assess the effects of shipping; the samples in Group 5 were shipped together with the Group 4 samples and were placed in a storage tank with liquid nitrogen after spending 48 hours stored on dry ice...
December 1, 2016: JBRA Assisted Reproduction
https://www.readbyqxmd.com/read/28049777/preparing-fission-yeast-for-electron-microscopy
#20
Thomas H Giddings, Mary K Morphew, J Richard McIntosh
Freezing samples while simultaneously subjecting them to a rapid increase in pressure, which inhibits ice crystal formation, is a reliable method for cryofixing fission yeast. The procedure consists simply of harvesting cells and loading them into a high-pressure freezer (HPF), and then operating the device. If equipment for high-pressure freezing is not available, fission yeast can be frozen by plunging a monolayer of cells into a liquid cryogen, usually ethane or propane. Unlike the HPF, where relatively large volumes of cells can be frozen in a single run, plunge freezing requires cells to be dispersed in a layer <20 µm thick...
January 3, 2017: Cold Spring Harbor Protocols
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