Ionization-induced electron trapping in ultrarelativistic plasma wakes

The onset of trapping of electrons born inside a highly relativistic, 3D beam-driven plasma wake is investigated. Trapping occurs in the transition regions of a Li plasma confined by He gas. Li plasma electrons support the wake, and higher ionization potential He atoms are ionized as the beam is focused by Li ions and can be trapped. As the wake amplitude is increased, the onset of trapping is observed. Some electrons gain up to 7.6 GeV in a 30.5 cm plasma. The experimentally inferred trapping threshold is at a wake amplitude of 36 GV/m, in good agreement with an analytical model and PIC simulations.     

Coherent control of the lattice dynamics of bismuth near the lindemann stability limit

The relative contributions of the anharmonicity of the lattice potential and the nonequilibrium concentration of charge carriers to the time dependence of the coherent A _1g phonon frequency in bismuth excited by high-energy ultrashort laser pulses are studied by the coherent control method. The contributions are separated by the pump-probe method in which excitation is performed by two pulses with a controlled time delay. It is shown that, depending on the relative delay between the pump pulses, both correlation and anticorrelation between the amplitude and the initial frequency of oscillations are observed while the chirp and the initial frequency of the coherent phonon are anticorrelated. In addition, it has been found that the contributions of the lattice and the electronic subsystem are always anticorrelated. Therefore, a certain phase can be assigned to an electronic excitation and it may be suggested that the time dependence of the phonon frequency is determined not only by instantaneous values of the lattice and electronic response but also by the phase relations between them.     

Precision measurement of the refractive index of carbon dioxide with a frequency comb

We report a higher precision measurement of the refractive index of carbon dioxide using a frequency comb as the light source in a Mach-Zehnder interferometer setup. The experimental sensitivity can reach the level of 8.8x10(-9). Taking into account the measurement accuracy of temperature and pressure, the experimental accuracy has a value of 1.2x10(-8). The measurement result has a deviation from the commonly quoted result [Old , J. Opt. Soc. Am.61, 89 (1971)] by 6.4x10(-7) at 800 nm.     

First-principles study of fundamental properties and electronic structure of alloys

We have performed first-principles calculations using full-potential augmented-plane-wave method to investigate the fundamental properties of the Cd_1–xZn_xTe alloys. The composition dependence of the lattice constant and the bulk modulus have been estimated from total energy calculations. By means of the analytical fitting the band structures in the vicinity of the Brillouin center a complete set of effective electron- and hole-masses have also been derived. In order to further understand the effects of the chemical bonding on the above macroscopic properties we then studied the relaxation behaviors and the changes of the electronic states upon alloying for x=0.25 system. The results presented here yield a general understanding of the fundamental properties for the Cd_1–xZn_xTe crystals studies.     

1H NMR Reassignment for Z/E-Benzomalvins B and Absolute Configuration of Benzomalvin C

Chemistry of Natural Compounds - Benzomalvins B, C, and E (1, 2, and 3) were simultaneously obtained from the marine fungus Aspergillus sp. isolated from the soft coral Sinularia sp., collected...     

Effect of Protective Measures on Eye Exposure to Solar Ultraviolet Radiation

In this study, ocular biologically effective exposure to solar ultraviolet radiation (UVBE) is investigated with six kinds of sun protective measures (spectacle lenses, sunglasses, cap, bonnet, straw hat and under parasol). Ocular UV exposure measurements were performed on manikins during the summer period in Shenyang city (41.64° N, 123.50° E, 66 m a.s.l.), China. The measurements include the ocular UV exposure of an unprotected eye and the ambient UV as a control concurrently. Based on the relative spectral weighting factors of the International Commission on Non‐Ionizing Radiation Protection (ICNIRP), the ocular biologically effective UV is calculated and compared with the 8‐h exposure limits of ICNIRP (30 J m^?2). The UV index (UVI) of the measurement days is 0–8, and the 8‐h (8:00–16:00 China Standard Time, CST) cumulated UVBE of the unprotected eye is 452.0 J m^?2. The 8‐h cumulated UVBE of the eye with spectacle lenses, sunglasses, cap, bonnet, straw hat and under parasol are 364.2, 69.1, 51.4, 49.0, 56.8 and 110.2 J m^?2, respectively. Importantly, it should be noted that the eye could be exposed to risk despite protective measures. The 8‐h cumulated UVBE of the eye with protection is ca 1.6–15.1 times the exposure limit, respectively. As indicated in the present study, during summer months, high exposure to the sun for more than 30 min without eye protection and more than 1 h with eye protection is not advisable. The protection measures could effectively reduce the UVBE reaching the eye, yet there is still a high degree of risk when compared with the ICNIRP 8‐h exposure limits.     

Efficient domino strategy for synthesis of 3-substituted 1,5-dihydro-4H-pyrrolo[3,2-c]pyridin-4-one derivatives

A series of 1,5-dihydro-4H-pyrrolo[3,2-c]pyridin-4-one derivatives with 3-(4-hydroxy-2-oxo-2H-pyran-3-yl) groups were synthesized via a one-pot three-component reaction of 4-aminopyridin-2(1H)-ones, 2,2-dihydroxy-1-arylethan-1-ones, and 4-hydroxy-2H-pyran-2-ones in water. This strategy not only provides a valuable tool in the design and synthesis of new hydrogenated pyrrolo[3,2-c]pyridines but also has the advantages of inexpensive starting materials, atom and step economy, environmental friendliness, good to excellent yields, and operational simplicity. A total of 14 examples were examined to show a broad substrate scope and high yields.     

Direct immobilization of iodine-loaded silver-coated silica gel with silicate glass powders at low temperature

Journal of Radioanalytical and Nuclear Chemistry - To long-term immobilization of secondary iodine-waste, iodine loaded silver-coated silica-gel (AgIs), glass-powder was used to directly solidify...     

A copper-based coordination polymer formed through synergistic bridging of 1,2,4-triazole and acetate anions: synthesis,crystal structure and magnetic properties

Transition Metal Chemistry - A Cu(II) coordination polymer, [Cu2(pztrz)2(μ-CH3COO)(CH3COO)]·3H2O (1), derived from mono-substituted 1,2,4-triazole derivative 3-(pyrazinyl)-1,2,4-triazole...