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M V Sulleiro, S Quiroga, D Peña, D Pérez, E Guitián, A Criado, M Prato
A non-conventional modification of exfoliated few-layer graphene (FLG) with different arynes under microwave (MW) irradiation and solvent-free conditions is reported. The described approach allows reaching fast, efficient and mild covalent functionalization of FLG.
January 15, 2018: Chemical Communications: Chem Comm
Emanuele Mauri, Edoardo Micotti, Arianna Rossetti, Lucio Melone, Simonetta Papa, Giulia Azzolini, Stefano Rimondo, Pietro Veglianese, Carlo Punta, Filippo Rossi, Alessandro Sacchetti
Polymer functionalization strategies have recently attracted considerable attention for several applications in biomaterials science. In particular, technological advancements in medical imaging have focused on the design of polymeric matrices to improve non-invasive approaches and diagnostic accuracy. In this scenario, the use of microwave irradiation of aqueous solutions containing appropriate combinations of polymers is gaining increasing interest in the synthesis of sterile hydrogels without using monomers, eliminating the need to remove unreacted species...
January 15, 2018: Soft Matter
Eun-Sun Hwang
The effects of different cooking methods on total bioactive compound content were determined, and in vitro antioxidant activity in 80% ethanolic extracts of Brussels sprouts was evaluated by spectrophotometric methods. Compared to uncooked, steamed, and microwaved Brussels sprouts extracted with 80% ethanol contained higher amounts of total polyphenols. Uncooked Brussels sprouts contained the highest amounts of total flavonoids. Microwaved Brussels sprouts contained the highest amounts of total carotenoids (0...
December 2017: Preventive Nutrition and Food Science
James S Hyde, Richard R Mett
The dielectric tube resonator (DTR) for EPR spectroscopy is introduced. It is defined as a metallic cylindrical TE011 microwave cavity that contains a dielectric tube centered on the axis of the cylinder. Contour plots of dimensions of the metallic cylinder to achieve resonance at 9.5 GHz are shown for quartz, sapphire, and rutile tubes as a function of wall thickness and average radius. These contour plots were developed using analytical equations and confirmed by finite element modeling. They can be used in two ways: design of the metallic cylinder for use at 9...
December 2017: Applied Magnetic Resonance
X J Feng, J T Zhang, H Lin, K A Gillis, J B Mehl, M R Moldover, K Zhang, Y N Duan
We report a new determination of the Boltzmann constant kB using a cylindrical acoustic gas thermometer. We determined the length of the copper cavity from measurements of its microwave resonance frequencies. This contrasts with our previous work (Zhang et al 2011 Int. J. Thermophys.32 1297, Lin et al 2013 Metrologia50 417, Feng et al 2015 Metrologia52 S343) that determined the length of a different cavity using two-color optical interferometry. In this new study, the half-widths of the acoustic resonances are closer to their theoretical values than in our previous work...
October 2017: Metrologia
Christopher E Sunday, Dmitry Veksler, Kin C Cheung, Yaw S Obeng
Traditional metrology has been unable to adequately address the needs of the emerging integrated circuits (ICs) at the nano scale; thus, new metrology and techniques are needed. For example, the reliability challenges in fabrication need to be well understood and controlled to facilitate mass production of through-substrate-via (TSV) enabled three-dimensional integrated circuits (3D-ICs). This requires new approaches to the metrology. In this paper, we use the microwave propagation characteristics to study the reliability issues that precede the physical damage caused by electromigration in the Cu-filled TSVs...
November 7, 2017: Journal of Applied Physics
Klemens M Thaler, Andrew J Schwartz, Christoph Haisch, Reinhard Niessner, Gary M Hieftje
Matrix effects caused by Na and Al in the nitrogen Microwave-sustained, Inductively Coupled, Atmospheric-pressure Plasma (MICAP) were investigated. Easily ionizable elements, such as Na, can suppress or enhance the analyte signal; Al is shown here to produce a similar effect. The influence of these matrices was examined for 18 emission lines of 8 analyte atoms and ions having a wide range of excitation and ionization energies. The plasma operating conditions were fixed during all experiments at a total nitrogen flow of 19...
April 1, 2018: Talanta
Souvik Kumar Paul, Saikat Chakraborty
Sunn hemp fibre - a cellulose-rich crystalline non-food energy crop, containing 75.6% cellulose, 10.05% hemicellulose, 10.32% lignin, with high crystallinity (80.17%) and degree of polymerization (650) - is identified as a new non-food substrate for lignocellulosic biofuel production. Microwave irradiation is employed to rapidly rupture the cellulose's glycosidic bonds and enhance glucose yield to 78.7% at 160 °C in only 46 min. The reactants - long-chain cellulose, ionic liquid, transition metal catalyst, and water - form a polar supramolecular complex that rotates under the microwave's alternating polarity and rapidly dissipates the electromagnetic energy through molecular collisions, thus accelerating glycosidic bond breakage...
January 3, 2018: Bioresource Technology
Jiaqi Zhong, Shan Liang, Qingyu Xiong
This paper considers the temperature spectrum tracking control of microwave heating model, in the presence of asymmetrical input saturation, nonhomogeneous Neumann boundary condition and temperature-dependent permittivity. The sufficient condition for the existence of receding horizon H∞ guaranteed cost control is proposed based on the derived finite-dimensional ordinary differential equation (ODE) error model. Furthermore, by on-line updating and solving linear matrix inequalities (LMIs) optimization problem, the constrained tracking controller can be obtained in the sense of minimizing H∞ norm and satisfying the quadratic cost performance...
January 10, 2018: ISA Transactions
N D Afify, M B Sweatman
We perform a complete classical molecular dynamics study of the dielectric heating of water in the microwave (MW) region. MW frequencies ranging from 1.0 to 15.0 GHz are used together with a series of well-known empirical force fields. We show that the ability of an empirical force field to correctly predict the dielectric response of liquids to MW radiation should be evaluated on the basis of a joint comparison of the predicted and experimental static dielectric constant, frequency-dependent dielectric spectra, and heating profiles...
January 14, 2018: Journal of Chemical Physics
Yike Wu, Qiuyue Sha, Juan Du, Chang Wang, Liang Zhang, Bi-Feng Liu, Yawei Lin, Xin Liu
Robust, efficient identification and accurate quantification of N-glycans are of great significance in N-glycomics analysis. Here, a simple and rapid derivatization method, based on the combination of microwave-assisted deglycosylation and 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) labeling, was developed for the analysis of N-glycan by high performance liquid chromatography with fluorescence detection (HPLC-FLD). After optimizing various parameters affecting deglycosylation and derivatization by RNase B, the time for N-glycan labeling was shortened to 50 min with ∼10-fold enhancement in detection sensitivity comparing to conventional 2-aminobenzoic acid (2-AA) labeling method...
January 8, 2018: Journal of Chromatography. A
Halil Koyu, Aslihan Kazan, Serdar Demir, Mehmet Zeki Haznedaroglu, Ozlem Yesil-Celiktas
Morus nigra L. is a beneficial food due to rich phenolic components. While aiming higher yields for bioactive constituents, reduction in terms of raw material, solvent, time and energy gained more importance to provide a sustainable life for human and nature. Microwave assisted extraction (MAE) of Morus nigra fruits was optimized in order to elicit process parameters maximizing bioactive metabolites and tyrosinase inhibitory activity. Spectrophotometry and UPLC-DAD-ESI-MS/MS systems were utilized for quantitative analysis of total phenol, flavonoid and anthocyanin contents...
May 15, 2018: Food Chemistry
Haejoon Jung, In-Ho Lee
As an intrinsic part of the Internet of Things (IoT) ecosystem, machine-to-machine (M2M) communications are expected to provide ubiquitous connectivity between machines. Millimeter-wave (mmWave) communication is another promising technology for the future communication systems to alleviate the pressure of scarce spectrum resources. For this reason, in this paper, we consider multi-hop M2M communications, where a machine-type communication (MTC) device with the limited transmit power relays to help other devices using mmWave...
January 12, 2018: Sensors
Alma Fernanda Sánchez-Maldonado, Alvin Lee, Jeffrey M Farber
Low-moisture foods (LMFs) have been defined as those food products with a water activity (aw) less than 0.85 and are generally considered less susceptible to microbial spoilage and the growth of foodborne pathogens. However, in recent years, outbreaks linked to LMFs have increased, with Salmonella spp., Bacillus cereus, Cronobacter sakazakii, Clostridium spp., Escherichia coli O157:H7, non-O157 E. coli, and Staphylococcus aureus being the principal pathogens involved. Because of the new concerns raised as a result of recent outbreaks, new approaches need to be developed to control foodborne pathogens in LMFs...
January 12, 2018: Annual Review of Food Science and Technology
A Romanenko, D I Schuster
In niobium superconducting radio frequency (SRF) cavities for particle acceleration, a decrease of the quality factor at lower fields-a so-called low field Q slope or LFQS-has been a long-standing unexplained effect. By extending the high Q measurement techniques to ultralow fields, we discover two previously unknown features of the effect: (i) saturation at rf fields lower than E_{acc}∼0.1  MV/m; (ii) strong degradation enhancement by growing thicker niobium pentoxide. Our findings suggest that the LFQS may be caused by the two level systems in the natural niobium oxide on the inner cavity surface, thereby identifying a new source of residual resistance and providing guidance for potential nonaccelerator low-field applications of SRF cavities...
December 29, 2017: Physical Review Letters
J Zopes, K Sasaki, K S Cujia, J M Boss, K Chang, T F Segawa, K M Itoh, C L Degen
We investigate the application of amplitude-shaped control pulses for enhancing the time and frequency resolution of multipulse quantum sensing sequences. Using the electronic spin of a single nitrogen-vacancy center in diamond and up to 10 000 coherent microwave pulses with a cosine square envelope, we demonstrate 0.6-ps timing resolution for the interpulse delay. This represents a refinement by over 3 orders of magnitude compared to the 2-ns hardware sampling. We apply the method for the detection of external ac magnetic fields and nuclear magnetic resonance signals of ^{13}C spins with high spectral resolution...
December 29, 2017: Physical Review Letters
Anthony Roucou, Isabelle Kleiner, Manuel Goubet, Sabath Bteich, Gaël Mouret, Robin Bocquet, Francis Hindle, W Leo Meerts, Arnaud Cuisset
The monitoring of gas phase mononitrotoluenes is crucial for defence, civil security and environmental interests since they are used as taggant for TNT detection and in the manufacturing of industrial compounds such as dyestuffs. In this study, we have succeeded to measure and analyse at high resolution a room temperature rotationally resolved millimeter-wave spectrum of meta-nitrotoluene(3-NT). Experimental and theoretical difficulties have been overcome, in particular, those related to the low vapour pressure of 3-NT and to the presence of a CH$_3$ internal rotation in an almost free rotation regime ($V_3$=6...
January 12, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Jianjia Yi, Sawyer D Campbell, Rui Feng, Shah Nawaz Burokur, Douglas H Werner
Complex electromagnetic structures can be designed by exploiting the concept of spatial coordinate transformations. In this paper, we define a coordinate transformation scheme that enables one to taper the electric field between two waveguides of different cross-sections. The electromagnetic field launched from the wide input waveguide is compressed in the proposed field tapering device and guided into the narrow output waveguide. In closed rectangular waveguide configurations, the taper can further play the role of a mode selector due to the output waveguide's cut-off frequency...
January 8, 2018: Optics Express
Mutong Xie, Mingyang Zhao, Mingzheng Lei, Yongle Wu, Yuanan Liu, Xinlu Gao, Shanguo Huang
An optically-controlled phase-tunable microwave mixer based on a dual-drive dual-parallel Mach-Zehnder modulator (DDDP-MZM) is proposed, which supports wideband phase shift and immunity to power fading caused by chromatic dispersion. By using carrier-suppressed single side-band (CS-SSB) modulation for the local oscillator (LO) signal and carrier-suppressed double side-band (CS-DSB) modulation for the input signal, no vector superposition for the same output microwave frequency occurs, making the system immune from power fading caused by chromatic dispersion...
January 8, 2018: Optics Express
Zongmin Ma, Shaowen Zhang, Yueping Fu, Hua Yuan, Yunbo Shi, Jian Gao, Li Qin, Jun Tang, Jun Liu, Yanjun Li
Sensitivity of magnetometers that use color centers is limited by poor photon-collection and detection efficiency. In this paper, we present the details of a newly developed all-optical collection combined frequency-modulated microwave method. The proposed method achieves a high sensitivity in static magnetic-field detection both theoretically and experimentally. First, we demonstrate that this collection technique enables both a fluorescence collection as high as 40% and an efficient pump absorption. Subsequently, we exploit the optically detected magnetic resonance (ODMR) signal and quantitative magnetic detection of an ensemble of nitrogen vacancy (NV) centers, by applying a frequency-modulated (FM) microwave method followed by a lock-in technique on the resonance frequency point...
January 8, 2018: Optics Express
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