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We demonstrate the structure, spectroscopy, and laser performance of an Er3+ and Pr3+ co-doped LuYSGG crystal grown by the Cz method. The XRD result shows that it belongs to the cubic system with the space group Ia3¯d. A refractive index curve in the range of 320–3000 nm is obtained by fitting the Sellmeier equation. The lifetimes of the 4I13/2 and 4I11/2 levels are 0.871 and 0.728 ms, and the ratio is reduced obviously from 3.4 to 1.2 due to the doping of deactivator Pr3+. In CW mode, a maximum output power of 1059 mW is achieved with a slope efficiency of 17.58% and laser center wavelength of ∼2.8 μm. Beam quality factors of 1.40/1.34 are achieved. The results suggest that the Er,Pr:LuYSGG crystal is a potential candidate for generating a high-power mid-infrared laser and can be applied in irradiation environments. [ABSTRACT FROM AUTHOR]

We demonstrate the temperature distribution, optical and laser performances of a YAP/Tm:YAP/YAP composite crystal fabricated by thermal bonding technology. The thermal distribution simulations show that the bonded crystal possesses a higher thermal dissipation efficiency than that of the unbonded one. The wavefront distortion of the bonded YAP/Tm:YAP crystal is close to the unbonded Tm:YAP, indicating a high bonding quality. The optical transmission spectra and absorption loss suggest that the bonding region is a uniform transition and almost without scattering interface. Moreover, compared with the un-bonded Tm:YAP crystal, a maximum average output power of 41.2 W and slope efficiency of 49.5% are achieved on the bonded crystal, which are increased by 28.4% and 21.0%, respectively. Therefore, the 1.94 μm laser performance can be effectively improved by combining pure YAP crystals on the Tm:YAP crystal as end-caps. [ABSTRACT FROM AUTHOR]

In this study, we demonstrate the laser performance of LD end-pumped LuYSGG/Er:LuYSGG composite crystal. Thermal distribution simulations by varying the pump spot size indicate that the suitable pump power density is a key factor affecting the laser performance, which is consistent with the experimental result. The maximum output power and slope efficiency achieved were 1266 mW and 24.3% in CW mode, which increased by 39.3% and 12.5%, respectively, compared with unbonded Er:LuYSGG crystal. The laser wavelength location was at 2797.6 nm, and the power fluctuation was about 5.1%. Moreover, the beam quality factors Mx2 and My2 improved to 1.33 and 1.42 from 1.78 and 1.83, respectively. The results suggested that an LD end-pumped LuYSGG/Er:LuYSGG composite crystal with a high beam quality can be applied as a seed source in the mid-infrared (MIR) multi-stage amplification laser apparatus. [ABSTRACT FROM AUTHOR]

Single crystals of Dy:GdScO3 and Dy,Tb:GdScO3 have been successfully grown by the Czochralski method. High crystalline quality of both crystals was determined via X-ray rocking curves. Effective segregation coefficients of Dy3+ and Tb3+ ions in GdScO3 host were calculated to be ∼0.7 and 1.03, respectively. The large FWHMs and absorption cross-sections of Dy:GdScO3 and Dy,Tb:GdScO3 crystals at 452 nm indicate that they can be efficiently pumped by the commercial blue GaN laser diodes. Both Dy:GdScO3 and Dy,Tb:GdScO3 exhibit relatively large stimulated emission cross-sections at 578 nm and relatively long fluorescence lifetimes. In particular, Dy,Tb:GdScO3 shows an enhanced yellow emission at around 578 nm. The energy transfer between Dy3+ and Tb3+ ions is beneficial for realizing population inversion by depopulating the population of the lower laser level of Dy3+ and has negligible influence on the upper laser level. Additionally, the defects and thermal properties of Dy:GdScO3 were investigated since they are very important for crystal growth and laser applications. Collectively, these results suggest that Dy:GdScO3 and Dy,Tb:GdScO3 can be regarded as promising candidates for realizing 578 nm laser output. [ABSTRACT FROM AUTHOR]

A new laser crystal from Lu2.4Y0.6Al5O12 (LuYAG) co-doped with Cr3+, Tm3+, Ho3+, and Pr3+ ions was grown successfully by the Czochralski method for the first time. The structure parameters of the Cr,Tm,Ho,Pr:LuYAG crystal are determined by the X-ray Rietveld refinement method. The main absorption bands are observed near 426 and 782 nm, and the fluorescence spectrum excited by a 450 nm or 783 nm LD presents an emission band near 2.911 μm, indicating that the co-doped Cr3+ and Tm3+ ions can be utilized as sensitizers for the Ho3+ ions. The lifetimes of the 5I6 and 5I7 levels of the Ho3+ ions were measured and fitted to be 0.070 ms and 1.852 ms, respectively. The energy transfer efficiencies of the processes 5I6 (Ho3+) →3F3,4 (Pr3+) and 5I7 (Ho3+) →3F2 (Pr3+) + 3H6 (Pr3+) were calculated, showing that the Pr3+ ions can play the role of a deactivator for the Ho3+ ions. Furthermore, the energy transfer mechanisms among the Cr3+, Tm3+, Ho3+, and Pr3+ ions were studied. The results suggest that the Cr,Tm,Ho,Pr:LuYAG crystal is a new promising laser medium operating at around 2.9 μm under flash lamp or 783 nm LD pumping. [ABSTRACT FROM AUTHOR]

Mesoporous silica nanoparticles (MSNs) that can stably load therapeutic drugs and release them in response to a specific trigger are of great interest in disease diagnosis and treatment. However, the controlled-release of gaseous drug molecules such as hydrogen sulfide (H2S) from a long-range and stable MSN-based system still presents a great challenge. Herein, a MSN-based glutathione (GSH)-triggered controlled-release H2S system has been fabricated with high entrapment efficiency (99.0 ± 0.3%) and loading content (44.2 ± 0.1%) of diallyl trisulfide (DATS). After the addition of GSH (2 mM), DATS-MSN (100 μg mL−1) steadily releases moderate amounts of H2S (peaking at the 4th hour, ∼60 μM) in phosphate buffer solution (PBS). The release of H2S in plasma is similar to a physiological process (peaking at the 4th hour) and the DATS-MSN remains in the plasma of a rat's system over 9 hours without significantly affecting the blood pressure, heart rate and cardiac function. Moderate quantities of nanoparticles can be taken up by cardiomyocytes in vitro, while in vivo study shows that nanoparticles mainly accumulate in the liver and spleen, affecting the H2S level in these organs. Furthermore, DATS-MSN shows excellent biocompatibility, as well as superior cytoprotection and an isolated heart protection effect of H2S under ischemic/reperfusion injury. This study provides a new insight into controlled-release applications of MSN-based H2S releasing systems both in vitro and in vivo. [ABSTRACT FROM AUTHOR]

Future energy systems must call upon clean and renewable sources capable of reducing associated CO 2 emissions. The present research opens new perspectives for renewable energy-based hydrogen production by water splitting using metal oxide oxidation/reduction reactants. An earlier multicriteria assessment defined top priorities, with MnFe 2 O 4 /Na 2 CO 3 /H 2 O and Mn 3 O 4 /MnO/NaMnO 2 /H 2 O multistep redox cycles having the highest potential. The latter redox system was previously assessed and proven difficult to be conducted. The former redox system was hence experimentally investigated in the present research at the 0.5 to 250 g scale in isothermal thermogravimetry, an electrically heated furnace, and a concentrated solar reactor. Over 30 successive oxidation/reduction cycles were assessed, and the H 2 production efficiencies exceeded 98 % for the coprecipitated reactant after these multiple cycles. Tentative economics using a coprecipitated reactant revealed that 120 cycles are needed to achieve a 1 € per kg H 2 cost. Improving the cheaper ball-milled reactant could reduce costs by approximately 30 %. The initial results confirm that future research is important., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)