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G V Brown, P Beiersdorfer, N Hell, E Magee
We have used the EBIT-I electron beam ion trap at the Lawrence Livermore National Laboratory and a duplicate Orion High Resolution X-ray Spectrometer (OHREX) to measure the relative efficiency of a spherically bent quartz (101̄1) crystal (2d = 6.687 Å) and a spherically bent germanium (111) crystal (2d = 6.532 Å). L-shell X-ray photons from highly charged molybdenum ions generated in EBIT-I were simultaneously focussed and Bragg reflected by each crystal, both housed in a single spectrometer, onto a single CCD X-ray detector...
November 2016: Review of Scientific Instruments
P Beiersdorfer, E W Magee, N Hell, G V Brown
We describe a crystal spectrometer implemented on the Livermore electron beam ion traps that employ two spherically bent quartz crystals and a cryogenically cooled back-illuminated charge-coupled device detector to measure x rays with a nominal resolving power of λ/Δλ ≥ 10 000. Its focusing properties allow us to record x rays either with the plane of dispersion perpendicular or parallel to the electron beam and, thus, to preferentially select one of the two linear x-ray polarization components. Moreover, by choice of dispersion plane and focussing conditions, we use the instrument either to image the distribution of the ions within the 2 cm long trap region, or to concentrate x rays of a given energy to a point on the detector, which optimizes the signal-to-noise ratio...
November 2016: Review of Scientific Instruments
F Scotti, V A Soukhanovskii, M E Weller
A comprehensive set of spectroscopic diagnostics is planned in the National Spherical Torus Experiment Upgrade to connect measurements of molybdenum and tungsten divertor sources to scrape-off layer (SOL) and core impurity transport, supporting the installation of high-Z plasma facing components which is scheduled to begin with a row of molybdenum tiles. Imaging with narrow-bandpass interference filters and high-resolution spectroscopy will be coupled to estimate divertor impurity influxes. Vacuum ultraviolet and extreme ultraviolet spectrometers will allow connecting high-Z sources to SOL transport and core impurity content...
November 2016: Review of Scientific Instruments
M Gumiela, J Dudek, A Bilewicz
Technetium-99m is the most widely used radionuclide in nuclear medicine. This work describes the method to separate (99m)Tc from irradiated (100)Mo target. For this purpose we utilized formation of ammonium molybdenum phosphate (AMP) and have optimized the four parameters of the process. The proposed process is promising and allows fast separation of macroamounts of molybdenum without co-precipitation of (99m)Tc. The concentration of molybdenum in solution after precipitation of AMP was lower than 300 µg ml(-1)...
2016: Journal of Radioanalytical and Nuclear Chemistry
Na Wu, Yadong Yu, Tao Li, Xiaojun Ji, Ling Jiang, Jiajun Zong, He Huang
Molybdenum disulfide, a type of two-dimensional layered material with unique properties, has been widely used in many fields. However, an exact understanding of its toxicity remains elusive, let alone its effects on the environmental microbial community. In this study, we utilized metabolomics technology to explore the effects of different concentrations of molybdenum disulfide nanosheets on Escherichia coli for the first time. The results showed that with increasing concentration of molybdenum disulfide nanosheets, the survival rate of Escherichia coli was decreased and the release of lactic dehydrogenase was increased...
2016: PloS One
César J Lockhart de la Rosa, Amirhasan Nourbakhsh, Markus Heyne, Inge Asselberghs, Cedric Huyghebaert, Iuliana Radu, Marc Heyns, Stefan De Gendt
Despite rapid progress in 2D molybdenum disulfide (MoS2) research in recent years, MoS2 field-effect transistors (FETs) still suffer from a high metal-to-MoS2 contact resistance and low intrinsic mobility, which are major hindrances to their future application. We report an efficient technique to dope thin-film MoS2 FETs using a poly(vinyl-alcohol) (PVA) polymeric coating. This results in a reduction of the contact resistance by up to 30% as well as a reduction in the channel resistance to 20 kΩ sq(-1). Using a dehydration process, we were able to effectively control the surface interactions between MoS2 and the more electropositive hydroxyl groups (-OH) of PVA, which provided a controllable and yet reversible increase in the charge carrier density to a value of 8...
December 1, 2016: Nanoscale
J H Du, H Jin, Z K Zhang, D D Zhang, S Jia, L P Ma, W C Ren, H M Cheng, P L Burn
The large surface roughness, low work function and high cost of transparent electrodes using multilayer graphene films can limit their application in organic photovoltaic (OPV) cells. Here, we develop single layer graphene (SLG) films as transparent anodes for OPV cells that contain light-absorbing layers comprised of the evaporable molecular organic semiconductor materials, zinc phthalocyanine (ZnPc)/fullerene (C60), as well as a molybdenum oxide (MoOx) interfacial layer. In addition to an increase in the optical transmittance, the SLG anodes had a significant decrease in surface roughness compared to two and four layer graphene (TLG and FLG) anodes fabricated by multiple transfer and stacking of SLGs...
December 1, 2016: Nanoscale
G Deokar, N S Rajput, P Vancsó, F Ravaux, M Jouiad, D Vignaud, F Cecchet, J-F Colomer
Vertically aligned MoS2 nanosheets (NSs) with exposed edges were successfully synthesized over a large area (∼2 cm(2)). The NSs were grown using an ambient pressure chemical vapor deposition technique via rapid sulfurization of sputter deposited thick molybdenum films. Extensive characterization of the grown MoS2 NSs has been carried out using high resolution scanning and transmission electron microscopy (SEM & TEM). A special care was given to the TEM lamella preparation process by means of a focused ion beam to preserve the NS growth direction...
December 1, 2016: Nanoscale
Di Liu, Le Yu, Xiao Xiong, Lei Yang, Yan Li, Ming Li, Hai-Ou Li, Gang Cao, Ming Xiao, Bin Xiang, Chang-Jun Min, Guang-Can Guo, Xi-Feng Ren, Guo-Ping Guo
Monolayer transition-metal dichalcogenides (TMDs) have grown as fantastic building blocks for optoelectronic applications, owing to their direct band gap, transparency, and mechanical flexibility. Since the luminescence of monolayer TMDs suffers from low light absorption and emission, surface plasmons, which confine light at subwavelength and enhance the local electric field, are utilized to boost both excitation and emission fields of TMDs, enabling strong light-matter interaction at the nano-scale. Meanwhile, radially-polarized beams (RPBs) as new and attractive excitation source have found many applications in surface plasmon polaritons, optical tweezer and so on...
November 28, 2016: Optics Express
Katherine Connelly, Calum Stevenson, Holger Kneuper, Frank Sargent
Salmonella enterica serovar Typhimurium is a Gram negative bacterium with a flexible respiratory capability. Under anaerobic conditions, S. enterica can utilise a range of terminal electron acceptors to sustain respiratory electron transport chains, including the potentially toxic compound selenate. The S. enterica selenate reductase is a membrane-bound enzyme encoded by the ynfEFGH-dmsD operon. The active enzyme is predicted to comprise at least three subunits where YnfE is a molybdenum-containing catalytic subunit...
October 20, 2016: Microbiology
Eugenii N Kukaev, Alexey S Kononikhin, Natalia L Starodubtseva, Yury I Kostyukevich, Igor A Popova, Vitaliy Chagovets, Konstantin O Nagornov, Eugene N Nikolaev
A novel atmospheric pressure thermal ionization (APTI) ion source was developed for the analysis of liquid samples. The feasibility of the ion source was demonstrated on peptides using two configurations-assisted by hot wire or hot surface. Microalloyed molybdenum, used as a thermal ion- emitter, notably facilitated the formation of multiply-charged ions, but fragmentation products were still observed. Peptide fragmentation accompanying thermal ionization can be used for peptide identification. The described method is promising for studies of biological samples with minimal pre-treatment...
2016: European Journal of Mass Spectrometry
Jiajia Lv, Sen Zhao, Shijia Wu, Zhouping Wang
Water safety is one of the most pervasive problems afflicting people throughout the world. Microcystin-LR (MC-LR), a representative toxin released by cyanobacteria, poses an increasing and serious threat to water safety. In order to develop facile, specific and sensitive detection methods for MC-LR, we fabricated an ultrasensitive fluorescence aptasensor using the enhanced fluorescence of UCNP and the effective quenching ability, high affinity toward single strand DNA (ssDNA) of MoS2 (termed as FAUM). This assay specifically determined MC-LR in the linear range of 0...
October 4, 2016: Biosensors & Bioelectronics
Jixing Lin, Sertan Ozan, Yuncang Li, Dehai Ping, Xian Tong, Guangyu Li, Cuie Wen
Titanium alloys are receiving increasing research interest for the development of metallic stent materials due to their excellent biocompatibility, corrosion resistance, non-magnetism and radiopacity. In this study, a new series of Ti-Ta-Hf-Zr (TTHZ) alloys including Ti-37Ta-26Hf-13Zr, Ti-40Ta-22Hf-11.7Zr and Ti-45Ta-18.4Hf-10Zr (wt.%) were designed using the d-electron theory combined with electron to atom ratio (e/a) and molybdenum equivalence (Moeq) approaches. The microstructure of the TTHZ alloys were investigated using optical microscopy, XRD, SEM and TEM and the mechanical properties were tested using a Vickers micro-indenter, compression and tensile testing machines...
November 29, 2016: Scientific Reports
Yu Lin Hsu, Chris H Chang, W Eugene Roberts
A 12-year-old girl presented with a Class II Division 1 malocclusion, complicated by a complete transposition of the maxillary left canine into the position normally occupied by the left lateral incisor. Dental and medical histories were noncontributory. Brackets were bonded on all maxillary teeth, from first molar to first molar, except for the left lateral incisor. Because the lateral incisor was not engaged on the archwire, the tooth was free to physiologically move out of the path of canine root movement...
December 2016: American Journal of Orthodontics and Dentofacial Orthopedics
Johannes G Rebelein, Martin T Stiebritz, Chi Chung Lee, Yilin Hu
The iron (Fe) proteins of molybdenum (Mo) and vanadium (V) nitrogenases mimic carbon monoxide (CO) dehydrogenase in catalyzing the interconversion between CO2 and CO under ambient conditions. Catalytic reduction of CO2 to CO is achieved in vitro and in vivo upon redox changes of the Fe-protein-associated [Fe4S4] clusters. These observations establish the Fe protein as a model for investigation of CO2 activation while suggesting its biotechnological adaptability for recycling the greenhouse gas into useful products...
November 28, 2016: Nature Chemical Biology
Ningli Zhu, Matthew T Cole, William I Milne, Jing Chen
In this work we report on the fabrication of inductively coupled plasma (ICP) etched, diode-type, bulk molybdenum field emitter arrays. Emitter etching conditions as a function of etch mask geometry and process conditions were systematically investigated. For optimized uniformity, aspect ratios of >10 were achieved, with 25.5 nm-radius tips realised for masks consisting of aperture arrays some 4.45 μm in diameter and whose field electron emission performance has been herein assessed.
November 28, 2016: Physical Chemistry Chemical Physics: PCCP
Arūnas Jagminas, Gediminas Niaura, Rokas Žalnėravičius, Romualdas Trusovas, Gediminas Račiukaitis, Vitalija Jasulaitiene
One-pot hydrothermal synthesis of MoS2 nanoplatelet arrays on various substrates is perhaps the most promising approach to fabricate efficient electrocatalysts for hydrogen evolution reaction. However, the main challenges in this synthesis remain the purity and crystallinity of MoS2. In this study, we show for the first time that irradiation of amorphous, defect-rich MoS2 nanoplatelets with a green nanosecond laser at a proper irradiation dose, ca ≤0.35 J cm(-2), can significantly improve the crystallinity and purity of MoS2 nanoplatelets...
November 28, 2016: Scientific Reports
Rodrigo Arias-Cartin, Pierre Ceccaldi, Barbara Schoepp-Cothenet, Klaudia Frick, Jean-Michel Blanc, Bruno Guigliarelli, Anne Walburger, Stéphane Grimaldi, Thorsten Friedrich, Véronique Receveur-Brechot, Axel Magalon
A major gap of knowledge in metalloproteins is the identity of the prefolded state of the protein before cofactor insertion. This holds for molybdoenzymes serving multiple purposes for life, especially in energy harvesting. This large group of prokaryotic enzymes allows for coordination of molybdenum or tungsten cofactors (Mo/W-bisPGD) and Fe/S clusters. Here we report the structural data on a cofactor-less enzyme, the nitrate reductase respiratory complex and characterize the conformational changes accompanying Mo/W-bisPGD and Fe/S cofactors insertion...
November 25, 2016: Scientific Reports
Kathrin Rousk, Jefferson Degboe, Anders Michelsen, Robert Bradley, Jean-Philippe Bellenger
Biological nitrogen fixation (BNF) performed by moss-associated cyanobacteria is one of the main sources of new nitrogen (N) input in pristine, high-latitude ecosystems. Yet, the nutrients that limit BNF remain elusive. Here, we tested whether this important ecosystem function is limited by the availability of molybdenum (Mo), phosphorus (P), or both. BNF in dominant mosses was measured with the acetylene reduction assay (ARA) at different time intervals following Mo and P additions, in both laboratory microcosms with mosses from a boreal spruce forest and field plots in subarctic tundra...
November 24, 2016: New Phytologist
Xiumin Li, Xuli Ma, Xiao Du, Junlan Zheng, Xiaogang Hao, Abuliti Abudula, Guoqing Guan
A hybrid catalyst composed of silver (Ag) doped wire-like molybdenum carbide (MoxCy) with pure β-phase and carbon nanotubes (CNTs) was coated well on a carbon rod electrode for the hydrogen evolution reaction (HER). The effects of Ag loading amount and carbonization temperature on the crystal form of MoxCy were investigated in detail. It is found that the MoxCy crystal form can be tuned by adjusting the preparation conditions, and nanostructured wire-like Mo2C with pure β-phase was obtained at a temperature over 750 °C...
November 23, 2016: Physical Chemistry Chemical Physics: PCCP
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