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Adam J Matzger, Ren A Wiscons, Nagula Rajesh Goud, Joshua T Damron
Ferroelectric materials exhibit switchable remanent polarization due to reversible symmetry breaking under an applied electric field. Previous research has leveraged temperature-induced neutral-ionic transitions in charge-transfer (CT) cocrystals to access ferroelectrics that operate through displacement of molecules under an applied field. However, displacive ferroelectric behavior is rare in organic CT cocrystals and achieving a Curie temperature (TC) above ambient has been elusive. Here a cocrystal between acenaphthene and 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane is presented that shows switchable remanent polarization at room temperature (TC = 68°C)...
May 22, 2018: Angewandte Chemie
Maocong Hu, Zhenhua Yao, Lili Li, Yung-Hao Tsou, Liyuan Kuang, Xiaoyang Xu, Wen Zhang, Xianqin Wang
A series of boron-doped graphene-supported Pt (Pt/BG) nanosheets were designed and synthesized using a one-step facile hydrothermal method. ICP, XPS, and TPD results confirmed that boron atoms were successfully embedded into the graphene matrix. The selective catalytic reduction of nitric oxide with hydrogen (H2-SCR) was tested over Pt/BG catalysts. The multi-roles of doped-boron were investigated by Raman, BET, CO-chemisorption, H2-TPD, XPS, and NO-TPD. Boron doping led to a higher dispersion and smaller size of Pt nanoparticles, facilitated hydrogen spillover, promoted more metallic Pt formation, and increased both H2 and NO chemisorption, which were attributed to an enhanced Pt nucleation rate over doped-boron, electron donation from boron to Pt, and extra chemisorption sites...
May 22, 2018: Nanoscale
Young-Kyun Lim, Choong-Hyun Lee, Eung-Seok Lee, Dae-Soon Lim
In the study, a hollow boron-doped diamond (BDD) nanostructure electrode is fabricated to increase the reactive surface area for electrochemical applications. Tungsten oxide nanorods are deposited on the silicon substrate as a template by the hot filament chemical vapor deposition (HFCVD) method. The template is coated with a 100 nm BDD layer deposited by HFCVD to form a core-shell nanostructure. The WOx core is finally electrochemically dissolved to form hollow BDD nanostructure. The fabricated hollow BDD nanostructure electrode is investigated via scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopy...
May 22, 2018: Nanotechnology
Zhen Tan, Pengwan Chen, Qiang Zhou, Jianjun Liu, Xiaofeng Mei, Bi Wang, Naifu Cui
The phase transformation behavior of anatase and rutile titanium dioxide with particle sizes of 60 nm and 150 nm under shock compression have been investigated. To increase the shock pressure and reduce the shock temperature, copper powder and a small amount of paraffin were mixed with the TiO2 powder. The shock recovered samples were characterized by X-ray diffraction, Raman spectroscopy, and transmission electron microscope. The results indicate that both anatase and rutile TiO2 can transform to α-PbO2 phase TiO2 through shock-induced phase transition...
May 22, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Huifang Ma, Peng Chen, Bo Li, Jia Li, Ruoqi Ai, Zhengwei Zhang, Guangzhuang Sun, Kangkang Yao, Zhaoyang Lin, Bei Zhao, Ruixia Wu, Xuwan Tang, Xidong Duan, Xiangfeng Duan
The recent discovery of topological semimetals has stimulated extensive research interest due to their unique electronic properties and novel transport properties related to a chiral anomaly. However, the studies to date are largely limited to bulk crystals and exfoliated flakes. Here, we report the controllable synthesis of ultrathin two-dimensional (2D) platinum telluride (PtTe2 ) nanosheets with tunable thickness and investigate the thickness-dependent electronic properties. We show that PtTe2 nanosheets can be readily grown, using a chemical vapor deposition approach, with a hexagonal or triangular geometry and a lateral dimension of up to 80 μm, and the thickness of the nanosheets can be systematically tailored from over 20 to 1...
May 22, 2018: Nano Letters
Wen Luo, Jiahui Chen, Limin Li, Xueyi Ren, Tian Cheng, Shiyi Lu, Raman Akinyanju Lawal, Qinghua Nie, Xiquan Zhang, Olivier Hanotte
The transcription factor c-Myc is an important regulator of cellular proliferation, differentiation and embryogenesis. While c-Myc can inhibit myoblast differentiation, the underlying mechanisms remain poorly understood. Here, we found that c-Myc does not only inhibits myoblast differentiation but also promotes myoblast proliferation and muscle fibre hypertrophy. By performing chromatin immunoprecipitation and high-throughput sequencing (ChIP-seq), we identified the genome-wide binding profile of c-Myc in skeletal muscle cells...
May 21, 2018: Cell Death and Differentiation
Moteb M Alqahtani, Atif M Ali, Farid A Harraz, M Faisal, Adel A Ismail, Mahmoud A Sayed, M S Al-Assiri
Mesoporous α-Fe2 O3 has been synthesized via a simple sol-gel procedure in the presence of Pluronic (F-127) triblock copolymer as structure directing agent. Silver (Ag) nanoparticles were deposited onto α-Fe2 O3 matrix by the photochemical reduction approach. Morphological analysis revealed the formation of Ag nanoparticles with small sizes < 20 nm onto the mesoporous structure of α-Fe2 O3 possessing < 50 nm semi-spherical shape. The XRD, FTIR, Raman, UV-vis, PL, and N2 sorption isotherm studies confirmed the high crystallinity, mesoporosity, and optical characteristics of the synthesized product...
May 21, 2018: Nanoscale Research Letters
Zamyla Morgan Chan, Daniil A Kitchaev, Johanna Nelson Weker, Christoph Schnedermann, Kipil Lim, Gerbrand Ceder, William Tumas, Michael F Toney, Daniel G Nocera
Electrodeposited manganese oxide films are promising catalysts for promoting the oxygen evolution reaction (OER), especially in acidic solutions. The activity of these catalysts is known to be enhanced by the introduction of Mn3+ We present in situ electrochemical and X-ray absorption spectroscopic studies, which reveal that Mn3+ may be introduced into MnO2 by an electrochemically induced comproportionation reaction with Mn2+ and that Mn3+ persists in OER active films. Extended X-ray absorption fine structure (EXAFS) spectra of the Mn3+ -activated films indicate a decrease in the Mn-O coordination number, and Raman microspectroscopy reveals the presence of distorted Mn-O environments...
May 21, 2018: Proceedings of the National Academy of Sciences of the United States of America
E Dumont, C De Bleye, J Cailletaud, P-Y Sacré, P-B Van Lerberghe, B Rogister, G A Rance, J W Aylott, Ph Hubert, E Ziemons
The analysis of serum samples by surface-enhanced Raman spectroscopy (SERS) has gained ground over the last few years. However, the stabilisation of colloids by the proteins contained in these samples has restricted their use in common practice, unless antibodies or aptamers are used. Therefore, this work was dedicated to the development of a SERS methodology allowing the analysis of serum samples in a simple and easy-to-implement way. This approach was based on the pre-aggregation of the colloid with a salt solution...
August 15, 2018: Talanta
Daniel Wiktelius, Linnea Ahlinder, Andreas Larsson, Karin Höjer Holmgren, Rikard Norlin, Per Ola Andersson
Collecting data under field conditions for forensic investigations of chemical warfare agents calls for the use of portable instruments. In this study, a set of aged, crude preparations of sulfur mustard were characterized spectroscopically without any sample preparation using handheld Raman and portable IR instruments. The spectral data was used to construct Random Forest multivariate models for the attribution of test set samples to the synthetic method used for their production. Colored and fluorescent samples were included in the study, which made Raman spectroscopy challenging although fluorescence was diminished by using an excitation wavelength of 1064 nm...
August 15, 2018: Talanta
Sumeng Zou, Lingwei Ma, Jianghao Li, Zheng Xie, Dongliang Zhao, Yunhan Ling, Zhengjun Zhang
The chemical quantitative analysis at trace level has been widely explored by means of various techniques. While it still remains challenging to achieve ultrasensitive but facile, rapid, and inexpensive detection methods. In this paper, the possibility of employing surface-enhanced Raman scattering technique on a portable Raman system for rapid and accurate quantitative analysis of target chemicals in unknown systems was investigated. This detection approach contains 3 steps: (1) adding target chemicals with different amount to the initial unknown solution, leading to new solutions with target molecules of various concentrations; (2) Obtaining different samples' SERS spectra and capturing featured SERS peaks whose intensity grew up with the addition of target chemicals; (3) examining the relationship between featured peak intensity increment after adding target chemicals and its corresponding addition amount, and thus we could perform quantitative analysis of the chemical in an unknown solution and obtain its initial concentration...
August 15, 2018: Talanta
Melina Yarbakht, Maryam Nikkhah, Ahmad Moshaii, Karina Weber, Christian Matthäus, Dana Cialla-May, Jürgen Popp
Nowadays, cancer is one of the most dangerous and deadly disease all around the world. Cancer that is diagnosed at early stages is more likely to be treated successfully. Treatment of progressed cancer is very difficult, and generally surviving rates are much lower. Therefore, much research has been focused on developing non-invasive methods for detection of cancer and monitoring of its progress. Within this contribution, we present a novel strategy for selective isolation and detection of breast cancer cell lines (MCF-7 and BT-20) based on surface enhanced Raman scattering (SERS)...
August 15, 2018: Talanta
Borong Yu, Chentai Cao, Pan Li, Mei Mao, Qiwen Xie, Liangbao Yang
Morphine, a kind of illicit drugs, is also one of the main heroin metabolites. In consideration of a noninvasive way to monitor and identify drug abuse during forensic cases, the urine samples are usually detected. Here, colloidal gold nanorods (Au NRs) were introduced to act as active substrate, because of the strong optical extinction and spectral tunability of the longitudinal surface plasmon resonance (SPR). Thus, well surface-enhanced Raman spectra of morphine even at low concentrations could be obtained by portable Raman spectrometer...
August 15, 2018: Talanta
Shuxia Guo, Olga Chernavskaia, Jürgen Popp, Thomas Bocklitz
Fluorescence emission is one of the major obstacles to apply Raman spectroscopy in biological investigations. It is usually several orders more intense than Raman scattering and hampers further analysis. In cases where the fluorescence emission is too intense to be efficiently removed via routine mathematical baseline correction algorithms, an alternative approach is needed. One alternative approach is shifted-excitation Raman difference spectroscopy (SERDS), where two Raman spectra are recorded with two slightly different excitation wavelengths...
August 15, 2018: Talanta
Cláudia A Teixeira Dos Santos, Ricardo N M J Páscoa, Patrícia A L S Porto, António L Cerdeira, J M González-Sáiz, C Pizarro, João A Lopes
Routine wine analysis are commonly employed to ensure the quality and safety standards, and to meet consumers' demands and legal requirements. In the last decades, efforts have been done in order to replace the traditional analytical techniques by vibrational spectroscopic techniques such as near infrared (NIR) and mid infrared (MIR) spectroscopy. The potential of these techniques has already been proved by several studies that revealed their ability for the determination of several wine parameters with high levels of precision and accuracy...
August 15, 2018: Talanta
Lu-Lu Qu, Na Wang, Gen Zhu, T P Yadav, Xinting Shuai, Dandan Bao, Guohai Yang, Dawei Li, Haitao Li
A bi-functional ternary nanocomposite was developed by decorating TiO2 and gold nanoparticles on the reduced graphene oxide nanosheets (TiO2 -Au-rGO) for recyclable surface enhanced Raman scattering (SERS) detection. TiO2 -Au-rGO nanocomposites have been shown to demonstrate the superior SERS performances, which can be used for highly sensitive detection of rhodamine 6 G with a limit of detection of 1.2 × 10-10 M. Subsequently, the surface can be cleaned automatically by the photocatalytic degradation of the adsorbed analytes into inorganic small molecules under visible light irradiation...
August 15, 2018: Talanta
Marwa R El-Zahry
A comparative study of two types of silver nanoparticles was investigated. The effect of the surface chemistry of the studied silver nanoparticles (AgNPs) on their localized surface plasmon resonance was utilized for the quantitative determination of muscle relaxant tizanidine drug. The studied AgNPs are classified according to the type of stabilizing agent used in their synthesis into electrostatically and sterically stabilized AgNPs. The electrostatically-stabilized AgNPs (AA AgNPs) were prepared using ascorbic acid as both reducing and protective agents in alkaline medium...
August 15, 2018: Talanta
Eric Kian-Shiun Shim, Soo-Ying Lee
The edible bird's nest (EBN) of the swiftlet Aerodramus fuciphagus, a mucin glycoprotein, is usually white in color, but there also exist the more desirable red or 'blood' EBN. The basis of the red color has been a puzzle for a long time. Here, we show that the nitration of the tyrosyl residue to the 3-nitrotyrosyl (3-NTyr) residue in the glycoprotein is the cause of the red color. Evidences for the 3-NTyr residue come from: (a) the quantitative analysis of 3-NTyr in EBN by ELISA, (b) the UV-Vis absorption spectra of red EBN as a function of pH being similar to 3-nitrotyrosine (3-NT), (c) the change in the color of red EBN from yellow at low pH to red at high pH just like 3-NT, and (d) strong Raman nitro bands at 1330 cm-1 (symmetric -NO2 stretch) and 825 cm-1 (-NO2 scissoring bend) for red EBN...
May 22, 2018: Journal of Agricultural and Food Chemistry
Zdeněk Pilát, Silvie Bernatová, Jan Ježek, Johanna Kirchhoff, Astrid Tannert, Ute Neugebauer, Ota Samek, Pavel Zemánek
Analyzing the cells in various body fluids can greatly deepen the understanding of the mechanisms governing the cellular physiology. Due to the variability of physiological and metabolic states, it is important to be able to perform such studies on individual cells. Therefore, we developed an optofluidic system in which we precisely manipulated and monitored individual cells of Escherichia coli . We tested optical micromanipulation in a microfluidic chamber chip by transferring individual bacteria into the chambers...
May 18, 2018: Sensors
Alejandra Ruiz-Clavijo, Olga Caballero-Calero, Marisol Martín-González
Self-standing Bi₂Te₃ networks of interconnected nanowires were fabricated in three-dimensional porous anodic alumina templates (3D⁻AAO) with a porous structure spreading in all three spatial dimensions. Pulsed electrodeposition parameters were optimized to grow highly oriented Bi₂Te₃ interconnected nanowires with stoichiometric composition inside those 3D⁻AAO templates. The nanowire networks were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and Raman spectroscopy...
May 18, 2018: Nanomaterials
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