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https://www.readbyqxmd.com/read/28640617/5-methylhydantoin-from-isolated-molecules-in-a-low-temperature-argon-matrix-to-solid-state-polymorphs-characterization
#1
Bernardo A Nogueira, Gulce O Ildiz, João Canotilho, M Ermelinda S Eusébio, Marta Sofia C Henriques, José A Paixão, Rui Fausto
The molecular structure, vibrational spectra and photochemistry of 5-methylhydantoin (C4H6N2O2; 5-MH) were studied by matrix isolation infrared spectroscopy and theoretical calculations at the DFT(B3LYP)/6-311++G(d,p) theory level. The Natural Bond Orbital (NBO) analysis approach was used to study in detail the electronic structure of the minimum energy structure of 5-MH, namely the specific characteristics of the σ and π electronic systems of the molecule, and the stabilizing orbital interactions. UV irradiation of 5-MH isolated in argon matrix resulted in its photofragmentation through a single photochemical pathway, yielding isocyanic acid, ethanimine and carbon monoxide, thus following a pattern already observed before for the parent hydantoin and 1-methylhydantoin molecules...
June 22, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28636012/does-h4so5-exist
#2
Fernando Murillo, Alba Vargas-Caamal, Sudip Pan, José Luis Cabellos, Miguel J Mora-Fonz, Alvaro Muñoz-Castro, Albeiro Restrepo, Gabriel Merino
The possible existence of H4SO5 in aqueous sulfuric acid is analyzed in detail. For bare H4SO5, the computed free energy barrier for the exergonic transformation of H4SO5 into the H2SO4H2O complex is only 3.8 kcal mol(-1). The presence of water or sulfuric acid catalyzes the dehydration to such an extent that it becomes almost a barrierless process. In the gas phase, dehydration of H4SO5 is an autocatalytic reaction as the water molecule produced by the decomposition of one H4SO5 molecule induces further dissociation...
June 21, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28633825/structural-evolution-growth-mechanism-and-photoluminescence-properties-of-cuwo4-nanocrystals
#3
E L S Souza, J C Sczancoski, I C Nogueira, M A P Almeida, M O Orlandi, M S Li, R A S Luz, M G R Filho, E Longo, L S Cavalcante
Copper tungstate (CuWO4) crystals were synthesized by the sonochemistry (SC) method, and then, heat treated in a conventional furnace at different temperatures for 1h. The structural evolution, growth mechanism and photoluminescence (PL) properties of these crystals were thoroughly investigated. X-ray diffraction patterns, micro-Raman spectra and Fourier transformed infrared spectra indicated that crystals heat treated and 100°C and 200°C have water molecules in their lattice (copper tungstate dihydrate (CuWO4·2H2O) with monoclinic structure), when the crystals are calcinated at 300°C have the presence of two phase (CuWO4·2H2O and CuWO4), while the others heat treated at 400°C and 500°C have a single CuWO4 triclinic structure...
September 2017: Ultrasonics Sonochemistry
https://www.readbyqxmd.com/read/28632254/osteogenic-potential-of-gingival-mesenchymal-stem-cells-over-titanium-machined-surfaces
#4
Julio A Carrion, Junaid Rajani, Mohamed Al Bahrawy, Xiaojun Chan, Tae Jin Kim, Srinivas Myneni, Vincent J Iacono
PURPOSE: To evaluate the biochemical composition of bone nodules deposited by gingival mesenchymal stem cells (GMSCs) over titanium machined surfaces in vitro. MATERIALS AND METHODS: GMSCs were isolated from healthy gingival tissues of patients undergoing crown-lengthening surgical procedures. GMSCs were characterized following the International Society for Cellular Therapy guidelines. After incubation of the GMSCs with titanium discs, osteogenic differentiation was induced for 28 days...
June 20, 2017: International Journal of Oral & Maxillofacial Implants
https://www.readbyqxmd.com/read/28629070/fabrication-of-chitosan-graphene-oxide-polymer-nanofiber-and-its-biocompatibility-for-cartilage-tissue-engineering
#5
Lei Cao, Fei Zhang, Qiugen Wang, Xiaofeng Wu
In this work, Chitosan/Poly(vinyl alcohol) (PVA)/graphene oxide (GO) composite nanofibers were fabricated by electrospinning technique. The prepared nanofibers were characterized by using various spectroscopic and microscopic techniques. FESEM images have confirmed the uniform distributions of graphene oxide nanosheets in the nanofibers with self-assembly with chitosan/PVA chains. Additionally, the results of raman spectra confirmed the existence of GO sheets in the nanofibers. The tensile strength experiments revealed that the incorporation of GO increased the mechanical properties of nanofibers...
October 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28629008/multi-walled-carbon-nanotubes-graphene-oxide-hybrid-and-nanohydroxyapatite-composite-a-novel-coating-to-prevent-dentin-erosion
#6
Sídnei Nahorny, Hudson Zanin, Vinie Abreu Christino, Fernanda Roberta Marciano, Anderson Oliveira Lobo, Luís Eduardo Silva Soares
To date is emergent the development of novel coatings to protect erosion, especially to preventive dentistry and restorative dentistry. Here, for the first time we report the effectiveness of multi-walled carbon nanotube/graphene oxide hybrid carbon-base material (MWCNTO-GO) combined with nanohydroxyapatite (nHAp) as a protective coating for dentin erosion. Fourier transform Raman spectroscopy (FT-Raman), scanning electron (SEM), and transmission electron (TEM) microscopy were used to investigated the coatings and the effect of acidulated phosphate fluoride gel (APF) treatment on bovine teeth root dentin before and after erosion...
October 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28628320/dynamics-of-charge-injection-and-charge-recombination-in-dna-mini-hairpins
#7
Ashutosh Kumar Mishra, Michelle A Harris, Ryan M Young, Michael R Wasielewski, Frederick D Lewis
Steady state spectroscopy, femtosecond transient absorption spectroscopy (fsTA), and femtosecond stimulated Raman spectroscopy (FSRS) of DNA mini-hairpins possessing a diphenylacetylenedicarboxamide (DPA) linker and 1-3 adenine-thymine (A-T) or guanine-cytosine (G-C) base pairs have been investigated. Ultraviolet and circular dichroism (UV and CD) spectra are consistent with ground state conformations that are predominantly base-paired and -stacked for conjugates possessing two or three base pairs; however, they offer no information concerning the conformation of conjugates possessing a single base pair...
June 19, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28627878/tilted-two-dimensional-array-multi-focus-confocal-raman-microspectroscopy
#8
Sohshi Yabumoto, Hiro-O Hamaguchi
A simple and efficient two-dimensional multi-focus confocal Raman microspectroscopy featuring the tilted-array technique is demonstrated. Raman scattering from a 4×4 square foci array passing through a 4×4 confocal pinhole array is tilted with a periscope. The tilted array of Raman scattering signals is dispersed by an imaging spectrograph onto a CCD detector, giving 16 independent Raman spectra formed as 16 bands with different heights on the sensor. Use of a state-of-the-art imaging spectrograph enables high-precision wavenumber duplicability of the 16 spectra...
June 19, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28622726/efficient-covalent-modification-of-multiwalled-carbon-nanotubes-with-diazotized-dyes-in-water-at-room-temperature
#9
Asma Bensghaïer, Stephanie Lau-Truong, Mahamadou Seydou, Aazdine Lamouri, Eric Leroy, Matej Micusik, Klaudia Forro, Mohamed Beji, Jean Pinson, Maria Omastova, Mohamed Mehdi Chehimi
Tetrafluoroborate salts of diazotized Azure A (AA-N2+), Neutral Red (NR-N2+) and Congo Red (CR-N2+) dyes were prepared and reacted with multiwalled carbon nanotubes (MWCNTs) at room temperature, in water without any reducing agent. The as-modified MWCNTs were examined by IRATR, Raman spectroscopy, XPS, TGA, TEM and cyclic voltammetry. The diazonium band located at 2350 cm-1 in the diazotized dye IR spectra vanished after attachment to the nanotubes whilst Raman D/G peak ratio slightly increased after dye covalent attachment at high initial diazonium/CNT mass ratio...
June 16, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28622639/an-investigation-into-the-rapid-removal-of-tetracycline-using-multilayered-graphene-phase-biochar-derived-from-waste-chicken-feather
#10
Huiqin Li, Jingtao Hu, Yue Meng, Jinhua Su, Xiaojing Wang
This study investigated the removal of tetracycline (TC) using multilayered graphene-phase biochar (MGB) derived from waste chicken feather. MGB was produced through a two-stage carbonization and KOH-activation method. MGB was characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM), Fourier transform infrared (FT-IR), Raman spectra, Zeta potential and elemental analysis. Various chemical functional groups were demonstrated on the surface of MGB. MGB was featured by a very large BET surface area of 1838m(2)/g...
June 13, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28620762/using-raman-spectroscopy-in-studying-the-effect-of-propylene-glycol-oleic-acid-and-their-combination-on-the-rat-skin
#11
Eman Atef, Njoud Altuwaijri
The permeability enhancement effect of oleic acid (OA) and propylene glycol (PG) as well as their (1:1 v/v) combined mixture was studied using rat skin. The percutaneous drug administration is a challenge and an opportunity for drug delivery. To date, there is limited research that illustrates the mechanism of penetration enhancers and their combinations on the skin. This project aims to explore the skin diffusion and penetration enhancement of PG, OA, and a combination of PG-OA (1:1 v/v) on rat skin and to identify the potential synergistic effect of the two enhancers utilizing Raman spectroscopy...
June 15, 2017: AAPS PharmSciTech
https://www.readbyqxmd.com/read/28620179/ferroelectric-assisted-gold-nanoparticles-array-for-centimeter-scale-highly-reproducible-sers-substrates
#12
Xiaoyan Liu, Minoru Osada, Kenji Kitamura, Takahiro Nagata, Donghui Si
Assemble metal nanoparticles into various ordered structures with scale up to centimeter area is required to meet diverse needs of lab-on-a-chips and analytic components. Here, we present the uniform and high-yield fabrication of centimeter-scale gold nanoparticles (AuNPs) array for SERS substrates. Ferroelectric-assisted assembly of AuNPs line array is successfully fabricated by using a periodically poled LiNbO3 (PPLN) single crystal as a template. SNOM-Raman shows that the uniform assembly of AuNPs exhibits a high density of "hot spots" arising from strong electromagnetic (EM) field coupling induced by adjacent AuNPs...
June 15, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28617599/effects-of-adulteration-technique-on-the-nir-detection-of-melamine-in-milk-powder
#13
Peter F Scholl, Marti M Bergana, Betsy Jean Yakes, Zhuohong Xie, Steven Zbylut, Gerard Downey, Magdi M Mossoba, Joseph Edward Jablonski, Robert Magaletta, Stephen E Holroyd, Martin Buehler, Jianwei Qin, William Jeffrey Hurst, Joseph H LaPointe, Dean E Roberts, Carol Zrybko, Andrew Mackey, Jason D Holton, Greg A Israelson, Anitra Payne, Moon S Kim, Kuanglin Chao, Jeffrey C Moore
The U.S. Pharmacopeia has led an international collaborative project to develop a tool-box of screening methods and reference standards for the detection of milk powder adulteration. During the development of adulterated milk powder reference standards, blending methods used to combine melamine and milk had unanticipated strong effects on the NIR spectrum of melamine. The prominent absorbance band at 1468 nm of melamine was retained when it was dry-blended with skim milk powder but disappeared in wet-blended mixtures, where spray dried milk powder samples were prepared from solution...
June 15, 2017: Journal of Agricultural and Food Chemistry
https://www.readbyqxmd.com/read/28617245/efficient-mixed-solvent-exfoliation-of-few-quintuple-layer-bi2s3-and-its-photoelectric-response
#14
Yaohui Guo, Qiyi Zhao, Zehan Yao, Keyu Si, Yixuan Zhou, Xinlong Xu
A scalable liquid exfoliation of layered Bi2S3 with a mixed-solvent strategy was used for the fabrication of Bi2S3 nanosheets. We found that 10% deionized water in 90% isopropyl alcohol are the best mixed solvent for the efficient and effective exfoliation of layered Bi2S3. The results are consistent with the absorptivity spectra and the enthalpy of mixing theory. The obtained Bi2S3 nanosheets were few-quintuple layers investigated by TEM and Raman spectroscopy. These Bi2S3 nanosheets can be used to fabricate large scale thin film by filtration method, which demonstrated sensitive photoelectric response with the rising and decay response of photocurrent on the scale of sub-second under the visible light excitation...
June 15, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28614750/2d-cos-of-in-situ-%C3%AE-raman-and-in-situ-ir-spectra-for-structure-evolution-characterisation-of-nep-deposited-cobalt-oxide-catalyst-during-n-nonane-combustion
#15
Damian K Chlebda, Przemysław J Jodłowski, Roman J Jędrzejczyk, Joanna Łojewska
New catalytic systems are still in development to meet the challenge of regulations concerning the emission of volatile organic compounds (VOCs). This is because such compounds have a significant impact on air quality and some of them are toxic to the environment and human beings. The catalytic combustion process of VOCs over non-noble metal catalysts is of great interest to researchers. The high conversion parameters and cost effective preparation makes them a valuable alternative to monoliths and noble metal catalysts...
June 6, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28607973/role-of-electrochemically-in-house-synthesized-and-functionalized-graphene-nanofillers-in-the-structural-performance-of-epoxy-matrix-composites
#16
Sumanta Kumar Sahoo, Bankim Chandra Ray, Archana Mallik
The present study focuses on the intriguing enhancement in the mechanical properties of an epoxy-based composite structure resulting from the incorporation of in-house synthesized functionalized graphene nanosheets (f-GNSs) as nanofillers. The f-GNSs were obtained by anionic electrochemical intercalation and exfoliation with 2 M H2SO4, HClO4, and HNO3 protic electrolytes. The structural properties of the as-synthesized GNSs were analyzed by XRD and Raman spectroscopy. The (002) and (001) lattice planes of graphene and graphene oxide are observed at around 24...
June 21, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28605911/aluminate-red-phosphor-in-light-emitting-diodes-theoretical-calculations-charge-varieties-and-high-pressure-luminescence-analysis
#17
Niumiao Zhang, Yi-Ting Tsai, Mu-Huai Fang, Chong-Geng Ma, Agata Lazarowska, Sebastian Mahlik, Marek Grinberg, Chang-Yang Chiang, Wuzong Zhou, Jauyn Grace Lin, Jyh-Fu Lee, Jiming Zheng, Chongfeng Guo, Ru-Shi Liu
Searching for a non-rare earth-based oxide red-emitting phosphor is crucial for phosphor-converted light-emitting diodes (LEDs). In this study, we optimized a blue and UV-light excited Sr4Al14O25:Mn phosphor exhibiting red emission peaked at ~653 nm, which was successfully synthesized by solid-state reaction. The crystal structure, micromorphology, and luminescent properties of Sr4Al14O25:Mn phosphors were characterized by X-ray Rietveld refinement, high-resolution transmission electron microscopy, and photoluminescence spectra...
June 13, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28605686/solid-state-cocrystal-formation-between-acyclovir-and-fumaric-acid-terahertz-and-raman-vibrational-spectroscopic-studies
#18
Qiang Cai, Jiadan Xue, Qiqi Wang, Yong Du
The vibrational spectra of solid-state acyclovir, fumaric acid and their cocrystal have been investigated by using terahertz time-domain spectroscopy (THz-TDS) and Raman spectroscopy at room temperature. In experimental THz spectra, the cocrystal has absorption peaks in 0.65, 0.94 and 1.10THz respectively, while the raw materials are absolutely different in this region. Raman spectra also show similar results about differences between the cocrystal and raw materials. Density functional theory (DFT) was performed to simulate vibrational modes of different theoretical forms between acyclovir and fumaric acid...
June 9, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28601997/degradation-and-regeneration-of-feather-keratin-in-nmmo-solution
#19
Bomou Ma, Qisong Sun, Jing Yang, Jakpa Wizi, Xiuliang Hou, Yiqi Yang
Chicken feather, a potential source of keratin, is often disposed as waste material. Although some methods, i.e., hydrolysis, reduction, and oxidation, have been developed to isolate keratin for composites, it has been limited due to the rising environmental concerns. In this work, a green solvent N-methylmorpholine N-oxide (NMMO) was used to extract keratin from chicken feather waste. Eighty-nine percent of keratin was extracted using 75% NMMO solution. However, the result from size exclusion HPLC showed that most of the keratin degraded into polypeptide with molecular weight of 2189 and only 25...
June 10, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28599237/surface-enhanced-raman-spectroscopy-study-on-the-structure-changes-of-4-mercaptophenylboronic-acid-under-different-ph-conditions
#20
REVIEW
Hongyang Su, Yue Wang, Zhi Yu, Yawen Liu, Xiaolei Zhang, Xiaolei Wang, Huimin Sui, Chengbin Sun, Bing Zhao
4-Mercaptophenylboronic Acid (4-MPBA) plays pivotal role in various fields. The orientation and existing form of the 4-MPBA strongly depend on the pH value of the media. The general aim of this work is to obtain information about the structure changes of 4-MPBA absorbed on Ag nanoparticles in different pH environment. Surface-enhanced Raman spectroscopy (SERS) technique is a simple and rapid method to study adsorption phenomena at molecule level. The investigation is done by means of SERS. In order to interpret the experimental information, a series of SERS spectra is carried out...
May 31, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
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