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Olga A Yakovina, Alexander S Lisitsyn
Metal clusters with sizes below 1 nm excite great scientific interest, but the main information on their properties still comes from quantum mechanics modeling and costly physical methods of limited availability. We have studied ultradispersed Pt/γ-Al2O3 samples with TPD and complementary adsorption/desorption techniques and observed a strong influence of H2-treatment conditions (PH2 ≤ 1 bar; 200 K ≤ T ≤ 470 K) on the H2-TPD profile of Pt/γ-Al2O3. The results corroborate recent theoretical and spectroscopic studies predicting alterations in the structure of Pt nanoclusters under H2 but reveal that the restructuring needs to overcome continuous activation barriers and leads both to an increase in surface coverage and strengthening of Pt-H bonds...
October 25, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Saminathan Ramakrishnan, Sivaraman Subramaniam, Adrian Francis Stewart, Guido Grundmeier, Adrian Keller
DNA origami has become a widely used method for synthesizing well-defined nanostructures with promising applications in various areas of nanotechnology, biophysics, and medicine. Recently, the possibility to transfer the shape of single DNA origami nanostructures into different materials via molecular lithography approaches has received growing interest due to the great structural control provided by the DNA origami technique. Here, we use ordered monolayers of DNA origami nanostructures with internal cavities on mica surfaces as molecular lithography masks for the fabrication of regular protein patterns over large surface areas...
October 25, 2016: ACS Applied Materials & Interfaces
Arturo Carranza, María Guadalupe Pérez-García, Kunlin Song, George M Jeha, Zhenyu Diao, Rongying Jin, Nina Bogdanchikova, J Félix Armando Soltero, Mauricio Terrones, Qinglin Wu, John Anthony Pojman, Josue David Mota-Morales
We report an alternative green strategy based on deep-eutectic solvents (DES) to deliver multi-walled carbon nanotubes (MWCNTs) for a bottom-up approach that allowing the selective interfacial functionalization of nonaqueous poly(high internal phase emulsions), poly(HIPEs). The formation and polymerization of methacrylic and styrenic HIPEs were possible through the stabilization with nitrogen doped carbon nanotube (CNX) and surfactant mixtures using a urea-choline chloride DES as a delivering phase. Subtle changes in CNX concentration (less than 0...
October 25, 2016: ACS Applied Materials & Interfaces
Eun Ji Park, Dong Hee Na
The separation mechanism of PEGylated peptides in reversed-phase high-performance liquid chromatography (RP-HPLC) is complex, because the PEGylated molecules exhibit physicochemical properties that are different from those of the parent molecules and have heterogeneous structure. Since most separation studies have focused on the hydrophobicity of the peptide relative to poly(ethylene glycol) (PEG), the role of PEG in the separation of PEGylated peptides on RP-HPLC is not clear. To elucidate the effect of the attached PEG on the retention of PEGylated peptides on RP-HPLC, the mono-PEGylated forms of collagen pentapeptide and octreotide were fractionated drop-by-drop from the outlet of the HPLC system and each drop was subjected to matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS)...
October 25, 2016: Analytical Chemistry
Consuelo J Perez, Alessandra Tata, Michel L de Campos, Chun Peng, Demian R Ifa
Ambient mass spectrometry imaging has become an increasingly powerful technique for the direct analysis of biological tissues in the open environment with minimal sample preparation and fast analysis times. In this study, we introduce desorption electrospray ionization mass spectrometry imaging (DESI-MSI) as a novel, rapid, and sensitive approach to localize the accumulation of a mildly toxic ionic liquid (IL), AMMOENG 130 in zebrafish (Danio rerio). The work demonstrates that DESI-MSI has the potential to rapidly monitor the accumulation of IL pollutants in aquatic organisms...
October 24, 2016: Journal of the American Society for Mass Spectrometry
Garold Murdachaew, Gilbert M Nathanson, R Benny Gerber, Lauri Halonen
Deprotonation of organic acids at aqueous surfaces has important implications in atmospheric chemistry and other disciplines, yet it is not well-characterized or understood. This article explores the interactions of formic acid (FA), including ionization, in collisions at the air-water interface. Ab initio molecular dynamics simulations with dispersion-corrected density functional theory were used. The 8-50 picosecond duration trajectories all resulted in the adsorption of FA within the interfacial region, with no scattering, absorption into the bulk or desorption into the vapor...
October 25, 2016: Physical Chemistry Chemical Physics: PCCP
Chao Liu, Jinhui Peng, Aiyuan Ma, Libo Zhang, Jing Li
Kinetics of the thermal desorption of mercury from spent mercury chloride catalysts were investigated using non-isothermal thermal analysis technique. Complex mercury species absorbed on waste catalysts were revealed by sequential extraction procedure. A scheme of six reactions was applied to elucidate mercury desorption kinetics. Activation energy estimated by model-free isoconversional methods is a slightly increasing function of conversion, implying a variation in the mechanism controlling mercury desorption...
September 28, 2016: Journal of Hazardous Materials
Sang-Hee Jo, Ki-Hyun Kim, Yong-Hyun Kim
In this study, a novel quantitation method was developed to facilitate the simple and effective sampling and analysis of phthalates in air based on a sorbent tube-thermal desorption-gas chromatography-mass spectrometry system combination. The performance of the thermal desorption-based analysis was assessed using three different sorbent combinations [1]: quartz wool (QW) [2], glass wool (GW), and [3] quartz wool plus Tenax TA (QWTN) in terms of relative recovery in reference to a direct injection method. There was no significant difference in the average recovery rate for seven target phthalates based on sorbent tube type (QW, 70...
November 9, 2016: Analytica Chimica Acta
Lanling Chu, Siwei Deng, Renshan Zhao, Jianjun Deng, Xuejun Kang
The objective of this study was to compare the adsorption/desorption of target compounds on homemade electrospun nanofibers, polystyrene (PS) nanofibers, acrylic resin (AR) nanofibers and PS-AR composite nanofibers with Tenax TA. Ten volatile organic compounds (VOCs) were analyzed by preconcentration onto different sorbents followed by desorption (thermal and solvent orderly) and analysis by capillary gas chromatography. In comparison to Tenax TA, the electrospun nanofibers displayed a significant advantage in desorption efficiency and adsorption selectivity...
2016: PloS One
Tong Shu, Jianxing Wang, Lei Su, Xueji Zhang
This study describes a novel ratiometric fluorescent sensor based on chemical etching of gold nanocluster (GNCs) for label-free, separation-free determination of tris(2-carboxyethyl)phosphine (TCEP). TCEP was discovered to exhibit unusual chemical behavior toward fluorescent gold nanoclusters: it quenched the red fluorescent emission of the bovine serum album (BSA)-protected GNCs (GNCs@BSA) and simultaneously restored the blue fluorescent emission of the dityrosine (diTyr) residues of the BSA ligand. The TCEP-induced quenching of the fluorescent GNCs@BSA was investigated with the UV-vis adsorption spectrum, the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MOLDI-TOF-MS), inductively coupled plasma-mass spectrometry (ICP-MS) and X-ray photoelectron spectroscopy (XPS), revealing the chemical etching of the gold(0) core of the GNCs@BSA by TCEP...
October 24, 2016: Analytical Chemistry
Demian Marchione, Martin R S McCoustra
Desorption of benzene (C6H6) from thick methanol (CH3OH) and diethyl ether (CH3CH2OCH2CH3) ices during irradiation with 250 eV electrons is reported and compared with our previous work on C6H6 desorption from water (H2O) ice systems. C6H6 electron-promoted desorption (EPD) is seen to be sensitive to the chemical nature of the substrate reflecting both the importance of the excitations localised around the O-atom versus those involving the C-atom; and the role of hydrogen bonding interactions in transporting non-dissociative electronic excitation to the substrate/C6H6 interfaces during the electron irradiation...
October 24, 2016: Physical Chemistry Chemical Physics: PCCP
Eugenia Bertona, Adriana N De Paulis, Miguel A Gutiérrez, Victoria Santa María, Carlos A Vay, Silvia C Predari
Dermabacter hominis species is constituted by Gram-positive facultative anaerobic coryneform rods being part of the resident microbiota human skin, and exceptionally associated to infections in immunocompromised or severely debilitated patients. An immunocompetent young adult woman with a neck sebaceous cyst infected by D. hominis as unique etiologic agent is presented. Phenotypic identification of the causative agent was achieved through simple tests, based on the originally scheme proposed by Funke and Bernard, and feasible to be performed in a hospital Microbiology Laboratory...
October 20, 2016: Revista Argentina de Microbiología
Yadan Guo, Wenchao Yu, Jinquan Chen, Xuegang Wang, Bai Gao, Guanghui Wang
To overcome the drawback of low stable brought by the transformation of Ag(+) into Ag, a highly efficient and stable photocatalyst Ag3PO4/rectorite composite was successfully synthesized by ultrasound-assisted precipitation method. The as-prepared samples were characterized by field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, N2 adsorption-desorption, room-temperature photoluminescence spectra, Fourier transform infrared spectrum measurements and UV-vis diffuse reflectance spectra...
January 2017: Ultrasonics Sonochemistry
Shan Chong, Guangming Zhang, Zhongheng Wei, Nan Zhang, Ting Huang, Yucan Liu
This paper studies the sonocatalytic degradation of diclofenac in water using FeCeOx-catalyzed ultrasound. The effects of pre-adsorption and gas addition were investigated. Nitrogen adsorption/desorption, SEM, XRD, Raman and XPS analyses of FeCeOx before and after sonication were characterized. The proposed mechanism was based on the microstructure changes of FeCeOx and reactive-species-scavenging performances. The results show that FeCeOx has excellent performance in catalyzing an ultrasonic system in water, and 80% of diclofenac was removed in 30min ([Diclofenac]=20mg/L, FeCeOx amount=0...
January 2017: Ultrasonics Sonochemistry
Chengdong Zhang, Xiaoyan Chen
Dispersing carbon nanomaterials with the aid of sonication has become a widely used procedure for generating homogenous solutions. A systematic study was performed to evaluate the effects of a practical sample preparation procedure that involves mild sonication with/without low concentrations of hydrogen peroxide. Hydrogen peroxide is ubiquitously present in surface water and involved in advanced oxidation processes. Significant oxidation was observed for fullerene in the liquid phase, whereas an appreciable amount of hydrogen was covalently attached to the carbon cage of solid fullerene...
January 2017: Ultrasonics Sonochemistry
Farzaneh Shayeganfar, Rouzbeh Shahsavari
Hydrogen storage capacities have been studied on newly designed three-dimensional pillared boron nitride (PBN) and pillared graphene boron nitride (PGBN). We propose these novel materials based on the covalent connection of BNNTs and graphene sheets, which enhance the surface and free volume for storage within the nanomaterial and increase the gravimetric and volumetric hydrogen uptake capacities. Density functional theory and molecular dynamic simulations show that these lithium- and oxygen-doped pillared structures have improved gravimetric and volumetric hydrogen capacities at room temperature, with values on the order of 9...
October 23, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Tao Li, Xiufen Chen, Yajun Liu, Lulu Fan, Liqing Lin, Yu Xu, Sijia Chen, Jingwei Shao
Ursolic acid (UA) as a nature product exhibits good anti-cancer activity, low toxicity, and good liver protection features. However, the low-solubility and poor bioavailability restrict its further clinical application. To overcome this problem, a pH-sensitive prodrug delivery system (UA@MSN-UA) that incorporated acid-sensitive linkage between drug and silica-based mesoporous nanosphere (MSN) was successfully designed and synthesized. The physicochemical properties of the UA@MSN-UA nanoparticles were investigated for shape, particle size, zeta potential, nitrogen adsorption-desorption and infrared (IR) spectroscopy...
October 19, 2016: European Journal of Pharmaceutical Sciences
Jillian S Y Lau, Tony M Korman, Alex Yeung, Richard Streitberg, Michelle J Francis, Maryza Graham
Bacteroides pyogenes is part of the normal oral flora of domestic animals. There is one previous report of human infection, with B. pyogenes bacteremia following a cat bite (Madsen 2011). We report seven severe human infections where B. pyogenes was identified by Bruker matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDTI-TOF MS), but not by VITEK MS and was misidentified by VITEK ANC card.
October 19, 2016: Anaerobe
Christopher D Doern, Susan M Butler-Wu
The performance of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MS) for routine bacterial and yeast identification as well as direct-from-blood culture bottle identification has been thoroughly evaluated in the peer-reviewed literature. Microbiologists are now moving beyond these methods to apply MS to other areas of the diagnostic process. This review discusses the emergence of advanced matrix-assisted laser desorption ionization time-of-flight MS applications, including the identification of filamentous fungi and mycobacteria and the current and future state of antimicrobial resistance testing...
October 15, 2016: Journal of Molecular Diagnostics: JMD
Christopher D Doern, Susan M Butler-Wu
The performance of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MS) for routine bacterial and yeast identification as well as direct-from-blood culture bottle identification has been thoroughly evaluated in the peer-reviewed literature. Microbiologists are now moving beyond these methods to apply MS to other areas of the diagnostic process. This review discusses the emergence of advanced matrix-assisted laser desorption ionization time-of-flight MS applications, including the identification of filamentous fungi and mycobacteria and the current and future state of antimicrobial resistance testing...
November 2016: Journal of Molecular Diagnostics: JMD
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