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We study theoretically a pulse compression method with gas-filled hollow-core fiber based on ultrafast molecular phase modulation. The simulation results show the molecular phase modulation can impart a positive or negative chirp on probe pulse and tune the central wavelength by changing the time delay between the pump and probe pulses. This approach is demonstrated to be suitable for generation of frequency-tunable few-cycle pulses with a smooth spectrum.

To describe the treatment with caspofungin of pneumocystis Carinii pneumonia (PCP) in elderly patients.A 93 year old male patient with chronic obstructive pulmonary disease (COPD) and in mechanical ventilation for 25 months. PCP was diagnosed and treated with trimethoprim-sulphamethoxazole compound (SMZ/TMP) and caspofungin.The diagnosis of PCP was confirmed by clinical features, radiographic abnormalities and sputum smear Giemsa stain PC (+) or PCR (+). SMZ/TMP was the first choice in treatment of PCP but caspofungin can be used in patients. SMZ/TMP had to be discontinued because of side effect or treatment failure. Caspofungin was effective and without any side effects in this patient.PCP is one of opportunistic infections in elderly patient admitted for long term mechanical ventilation. SMZ/TMP is the first choice for treatment but caspofungin may be an alternative.

We theoretically study the nonlinear compression of picosecond pulses with 10-mJ of input energy at the 1053-nm center wavelength by using a one-meter-long gas-filled hollow-core fiber (HCF) compressor and considering the third-order dispersion (TOD) effect. It is found that when the input pulse is about 1 ps/10 mJ, it can be compressed down to less than 20 fs with a high transmission efficiency. The gas for optimal compression is krypton gas which is filled in a HCF with a 400-μm inner diameter. When the input pulse duration is increased to 5 ps, it can also be compressed down to less than 100 fs efficiently under proper conditions. The results show that the TOD effect has little impact on picosecond pulse compression and the HCF compressor can be applied on compressing picosecond pulses efficiently with a high compression ratio, which will benefit the research of high-field laser physics.

We study theoretically the spectral intensity evolutions of the femtosecond Gaussian and parabolic pulses with different initial pulse energies and compare the nonlinear compressions of these pulses based on a meter-long hollow-core fiber filled with neon for different initial pulse durations. The pulses are first coupled into gas-filled hollow-core fiber for spectrum broadening, then compressed by the optimal chirp compensation. The parabolic pulse possesses a shorter pulse duration, larger peak power, and cleaner wings than Gaussian pulse. The properties are useful for compressing the pulses and thus generating the high-energy, short-duration pulses.

Femtosecond pulse laser with tilted intensity front demonstrates the capability of rotating the writing of nanograting in glass in 3D space. Other than the light polarization, this phenomenon is also associated with the quill-writing effect, which depends on the correlation between the sample movement and the pulse front tilt. This is because a pondermotive force, perpendicular to the tilted intensity plane, can push the excited electron plasma forward towards the pulse front. This behavior further tilts the electrical field plane and eventually result in a forced rotation of nanograting in 3D space.

A scheme to generate individually modulated femtosecond pulse string by multilayer volume holographic grating (MVHG) is proposed. Based on Kogelnik's coupled-wave theory and matrix optics, temporal and spectral expressions of diffracted field are given when a femtosecond pulse is diffracted by a MVHG. It is shown that the number of diffracted sub-pulses in the pulse string equals to the number of grating layers of the MVHG, peak intensity and duration of each diffracted sub-pulse depend on thickness of the corresponding grating layer, whereas pulse interval between adjacent sub-pulses is related to thickness of the corresponding buffer layer. Thus by modulating parameters of the MVHG, individually modulated femtosecond pulse string can be acquired. Based on Bragg selectivity of the volume grating and phase shift provided by the buffer layers, we give an explanation on these phenomena. The result is useful to design MVHG-based devices employed in optical communications, pulse shaping and processing.

A transactive memory system (TMS) refers to “a shared system that individuals in groups and organizations develop to collectively encode, store, and retrieve information or knowledge in different d...

For the Pd–Zr system, a long-range potential was constructed under the newly proposed empirical framework. Applying the constructed potential, molecular dynamics simulations were carried out to compare the relative stability of crystalline solid solution versus its disordered counterpart. Simulations reveal that the origin of metallic glass formation is the crystalline lattice collapsing while the solute concentrations exceed critical values, and further determine a composition range, within which the metallic glass formation is energetically favored. Moreover, the energy differences between the crystalline solid solutions and the disordered states, which are considered as the driving force for amorphization are computed. Thermodynamics calculations show that the glass-forming range of the Pd–Zr system is 10–90 at. % Pd, and the largest driving force exist around 50 at. % Pd. In addition, the coordinate numbers and atomic volumes of the Pd–Zr alloys were analyzed by the Voronoi tessellation method, showin...

The determinants of key new venture creation activities and choices remain largely unexplored in the entrepreneurship literature. One potential individual-level determinant involves regulatory foci, which differentially regulate the way in which individuals pursue goals based on different levels of pain avoidance and pleasure pursuit tendency. Entrepreneurs, like other individuals, tend to frame many sub-tasks in new venture creation as either gain vs. non-gain or loss vs. non-loss games. Thus, the mechanism with which regulatory foci influence individuals’ decision making and choices similarly applies to those of entrepreneurs and their startup firms. This study explores and empirically tests the links between entrepreneurial regulatory foci and key new venture creation activities and choices such as business plan completion, speed of legal entity establishment, the number or prestige of customers and strategic partners, and office rental expense. Proposed hypotheses were tested using surveys with 191 st...

Regulatory foci, a personality variable, differentially regulate the way in which individuals pursue goals based on different levels of pain avoidance and pleasure pursuit tendency. This variable i...

In this paper, we study the effect of spherical aberrations on the light intensity and the temperature distribution in the focal region in a 250-kHz femtosecond laser irradiated Ag+-doped borosilicate glass. When a focused beam goes through an interface between air and glass, spherical aberration will result in the separation of the focal point and then cause a clear change of the light intensity distribution along the incident direction. That phenomenon will further influence the longitudinal cross-section temperature distribution in glass. Here we use Ag nanoparticle formation as a marker for establishing temperature distribution and we find that the formation of nanoparticle shows a strong dependence on the temperature field and the detailed precipitation process is also discussed.

A facile one-pot method of femtosecond laser ablation in solution to synthesize hydrophilic silicon nanocrystals is presented in this communication. These silicon nanoscrystals emit colorful photoluminescence when excited at different wavelengths. This simple method has potential applications in the preparation of luminescent silicon nanocrystals passivated with different organic molecules.

We demonstrate that a surface-enhanced Raman scattering (SERS) substrate could be directly fabricated on the surface of Ag film by femtosecond laser micromachining. According to the morphology observation by SEM, an amount of nanoparticles, nanoprotrusions, and nanospikes were found to form in the ablation region and the density and size distribution of these Ag nanoparticles depended possibly on the incident laser intensity. Additionally, a large area of nanostructured region was produced by fast line scanning, and an enhancement factor of ~105 was obtained in this region after the sample was soaked in the rhodamine 6G solution for 30 min.

Proposed truncated Cu–Hf tight-binding potential was constructed by fitting the physical properties of Cu, Hf, and their stable compounds, i.e., Cu5Hf, Cu8Hf3, Cu10Hf7, and CuHf2. Based on the constructed potentials, molecular dynamics simulations were carried out to compare the relative stability of the crystalline solid solution and the disordered state. Simulation results not only reveal that the physical origin of crystal-to-amorphous transition is the crystalline lattice collapsing when the solute atoms exceeding the critical concentration, but also predict that the glass forming range (GFR) of the Cu–Hf system is 21–77 at. % Cu, which covers the GFRs determined by various metallic glass-producing techniques. Ion beam mixing experiments of the Cu–Hf system were conducted using 200 keV xenon ions and the results show that a uniform amorphous phase can be obtained in the Cu23Hf77 sample, matching well with the GFR determined by the interatomic potential, which, in turn, provides additional evidence to the relevance of the constructed Cu–Hf potential.

We report on the use of 800 nm, 250 kHz femtosecond laser pulses to precipitate Er(3+)-doped CaF(2) crystals inside oxyfluoride glass, which was confirmed with x-ray diffraction analysis. Confocal upconversion luminescence spectra show that the precipitated crystals have greatly enhanced upconversion luminescence intensity in comparison with unmodified glass. We demonstrate the possibility of three-dimensional optical data storage in the glass by the use of the confocal upconversion luminescence imaging.

Based on the projector augmented-wave method, ab initio calculations are performed for 20 representative binary Ni–Au, Ni–Cu, Ni–Zn, and Ni–Al alloys at A 3 B composition. The calculations reveal that the D0 22 Ni 3 Au, Ni 3 Cu, Ni 3 Zn, and L1 2 Ni 3 Al are more energetically stable than their respective competitive structures, indicating that the four structures may be formed in some appropriate conditions. The calculations indicate that different structures have small effects on the magnetic moments for Ni 3 Au and Ni 3 Cu alloys, while have large effects on the magnetic moments for Ni 3 Zn and Ni 3 Al alloys. It is also predicted that there is strong hybridization between Ni 3d and Cu 3d states in Ni 3 Cu and Ni 3d and Au 5d states in Ni 3 Au alloys and little hybridization in Ni 3 Al and Ni 3 Zn, which may significantly affect on structural stability and magnetism of these structures. The calculations suggest that the magnetism may increase the energetic stability of these structures. It is hoped tha...

A high efficiency organic light-emitting device (OLED) has been fabricated by using a vertical stack of two OLED units connected by Al/WO3/Ag. In the stacked OLEDs, each unit can be independently biased. It is found that the introduction of WO3 between Al and Ag enhances the electroluminescent (EL) efficiency by 3.7 cd A−1 for the top emissive unit. Meanwhile, the EL efficiency of the stacked OLED with the Al/WO3/Ag interconnecting electrode is improved by 6 cd A−1 with respect to the case of using Al/Ag as the connecting electrode. Our results indicate that Al/WO3/Ag is an excellent kind of connecting structure for the fabrication of independently controlled high efficiency stacked OLEDs.

We report on the coordination transformation of B3+ ions and migration of Na+ and O2− ions in sodium borate glasses, induced by 250kHz, 800nm femtosecond laser irradiation. Micro-Raman spectra show that the ratio of the integrated intensity of the two peaks at 806 and 774cm−1 decreases at first and then increases with increasing distance from the center of the laser modified zone. Electron dispersive x-ray spectra show that a portion of Na+ and O2− ions migrate from the vicinity of focal point after the femtosecond laser irradiation. A possible mechanism is proposed to explain the observed phenomena.

In this paper, we briefly summarize two typical morphology characteristics of the self-organized void array induced in bulk of fused silica glass by a tightly focused femtosecond laser beam, such as the key role of high numerical aperture in the void array formation and the concentric-circle-like structure indicated by the top view of the void array. By adopting a physical model which combines the nonlinear propagation of femtosecond laser pulses with the spherical aberration effect (SA) at the interface of two mediums of different refractive indices, reasonable agreements between the simulation results and the experimental results are obtained. By comparing the fluence distributions of the case with both SA and nonlinear effects included and the case with only consideration of SA, we suggest that spherical aberration, which results from the refractive index mismatch between air and fused silica glass, is the main reason for the formation of the self-organized void array.

On the basis of anatomic studies, we have devised a new method of transferring the thoracodorsal nerve to reinnervate the paralytic deltoid or biceps muscles in an old traumatic injury of the associated nerve. It has been applied to a case of musculocutaneous nerve injury and two cases of axillary nerve injury with good results. The muscle functions have returned to normal within 1 and 2 years, respectively, as shown by electromyography and the muscular contractility test.

The nonlinear optical crystal Ba2TiSi2O8 is induced three-dimensionally inside a glass by a femtosecond pulse laser with 800nm, 250kHz, and 150fs. Micro-Raman and photoluminescence spectra confirm that crystals can grow in the focal point of the laser beam. Continuous crystalline lines were written through moving the focal point of the laser beam inside the glass. The results demonstrate a convenient method to engrave three-dimensional patterns of crystals with nonlinear optical properties for integrated optical devices.

We report the self-formation of quasiperiodic void structure with the length of several hundred micrometers inside the CaF2 crystal. The quasiperiodical voids along the propagation direction of the laser beam were formed spontaneously after the irradiation of a single femtosecond laser beam which was focused at a fixed point inside the crystal sample. The length of the void array varied with the focal depth beneath the sample surface. The possible mechanism of the self-formed void structure was discussed.

We report on space-selective precipitation of nonlinear optical crystals in an Er(3+)-doped BaO-TiO(2)-SiO(2) glass by using a focused femtosecond laser with 800 nm, 250 kHz and 150 fs. An intense green emission due to upconversion luminescence is observed around the focal point of the femtosecond laser beam at the initial stage of the laser irradiation. A blue emission due to second harmonic generation begins to emerge from the irradiation region after 40 s irradiation. Micro-Raman spectra indicate that nonlinear optical crystals (Ba(2)TiSi(2)O(8)) are precipitated after the laser irradiation. The irradiation time for crystallization in Er(3+)-doped BaO-TiO(2)-SiO(2) glasses is longer than that in BaO-TiO(2)-SiO(2) glasses under the same irradiation conditions. The mechanisms responsible for the observed phenomena are discussed.