High-power single-frequency 1014.8 nm Yb-doped fiber amplifier working at room temperature.

A single-frequency 1014.8 nm Yb-doped fiber amplifier working at room temperature was investigated in detail with respect to gain fiber length, fiber geometry, and fiber host material, which can be frequency quadrupled to 253.7 nm for laser cooling of mercury. After optimization, an up to 8.06 W laser was achieved with a single-stage amplifier, and 19.3 W power was obtained with another boost amplifier, using polarization-maintaining Yb-doped single-mode fiber with a 10 µm core and 125 µm inner clad. The amplified spontaneous emission was 25 dB lower than the signal in the final output of the laser system. The laser has a linewidth of ~24 kHz without noticeable broadening after amplification. Further power scaling is limited by stimulated Brillouin scattering.

High power room temperature 1014.8 nm Yb fiber amplifier and frequency quadrupling to 253.7 nm for laser cooling of mercury atoms.

An 8 W continuous wave linearly-polarized single-frequency 1014.8 nm fiber amplifier working at room temperature is developed with commercial double-clad single-mode Yb-doped silica fiber. Re-absorption at the laser wavelength and amplified spontaneous emission at longer wavelength are managed by optimizing the amplifier design. The laser has a linewidth of ~24 kHz without noticeable broadening after amplification. Using two resonant cavity frequency doublers, 1.03 W laser at 507.4 nm and 75 mW laser at 253.7 nm are generated with 4 W 1014.8 nm laser. Both absorption and saturated absorption spectra of the (1)S(0) - (3)P(1) transition of atomic mercury are measured with the 253.7 nm laser.

589 nm laser generation by frequency doubling of a single-frequency Raman fiber amplifier in PPSLT.

A high-power single-frequency 1178 nm continuous-wave laser is generated in a two-stage stimulated-Brillouin-scattering-suppressed all-polarization-maintaining Raman fiber amplifier pumped by 1120 nm fiber lasers. A polarization-extinction-ratio of 30 dB is achieved due to the all-polarization-maintaining configuration and the polarization dependence gain of Raman scattering. Single-pass frequency doubling with a homemade periodically poled near-stoichiometric LiTaO(3) crystal (PPSLT) produces an up to 7 W narrow-linewidth laser at 589 nm. The thermally induced dephasing effect is found to be the key issue for improving second-harmonic efficiency.

A 100 W all-fiber linearly-polarized Yb-doped single-mode fiber laser at 1120 nm.

A 100 W-class all-fiber linearly-polarized single-mode fiber laser at 1120 nm with an optical efficiency of 50% was demonstrated. The laser consists of a 4.2 m long Yb-doped polarization maintaining fiber with a core diameter of 10 µm and a pair of FBGs written in matched passive fiber. Linearly polarized output with a polarization extinction ratio of 15 dB is achieved by a cavity that selects both wavelength and polarization. Pulsed operations with square shaped pulses varying from 100 µs to 1 ms duration are achieved without relaxation oscillation.

Stimulated-Brillouin-scattering-suppressed high-power single-frequency polarization-maintaining Raman fiber amplifier with longitudinally varied strain for laser guide star.

An up to 44 W, 1 MHz linewidth, 1178 nm CW laser is obtained by Raman amplification of a distributed feedback diode laser in a variably strained polarization-maintaining fiber with a record-high optical efficiency of 52%, pumped by a linearly polarized 1120 nm fiber laser. A polarization extinction ratio of 30 dB is achieved due to the all-polarization-maintaining configuration and the polarization dependence of Raman gain. The strain distribution is designed according to the signal power evolution along the fiber. A 20 times reduction in the effective stimulated Brillouin scattering coefficient is achieved. A 24.3 W 589 nm laser is generated by an external resonant doubling cavity with an optical efficiency of 68.5%. The laser is locked to 589.1591 nm for a laser guide star.

Tunable all-fiber dissipative-soliton laser with a multimode interference filter.

We report on a tunable all-fiber dissipative-soliton laser with a multimode interference filter that consists of a multimode fiber spliced between two single-mode fibers. By carefully selecting the fiber parameters, a filter with a central wavelength at 1032 nm and a bandwidth of 7.6 nm is constructed and used for spectral filtering in an all-normal-dispersion mode-locked ytterbium-doped fiber laser based on nonlinear polarization evolution. The laser delivers 31 mW of average output power with positively chirped 7 ps pulses. The repetition rate of the pulses is 15.3 MHz, and pulse energy is 2.1 nJ. Tunable dissipative-soliton over 12 nm is achieved by applying tension to the single-mode-multimode-single-mode filter.

Efficient linearly polarized ytterbium-doped fiber laser at 1120 nm.

We report a 20 W linearly polarized, spectrally clean Yb-doped fiber laser at 1120 nm with an optical conversion efficiency of 54%. An excellent polarization extinction ratio of more than 23 dB is obtained using fiber Bragg gratings (FBGs) polarization selection technique at all power levels. The results reveal that a Yb-doped fiber laser at 1120 nm could be a promising replacement compared to Raman fiber lasers.

High-efficiency fiber laser at 1018 nm using Yb-doped phosphosilicate fiber.

A high-efficiency fiber laser at 1018 nm using homemade Yb-doped phosphosilicate fiber is demonstrated. The fiber shows blueshifted emission spectrum compared to Yb-doped aluminosilicate fiber, and is considered favorable for the short wavelength Yb-doped fiber laser. With a 7 m gain fiber, up to 22.8 W output at 1018 nm is achieved with an optical efficiency of 53%. The amplified spontaneous emission at 1030 nm is suppressed to 50 dB below the 1018 nm laser. This work shows that highly-efficient fiber laser at 1018 nm can be obtained with Yb-doped phosphosilicate fiber.

High-Temperature Oxidation Behavior of Cr-Ni-Mo Hot-Work Die Steels.

The oxidation of 3Cr3Mo2NiW and 3CrNi3Mo steels was studied at 600 °C in air, and the test results suggest that the parabolic rate law fitted the oxidation kinetics of both steels. The microstructure, morphology, structure, and phase composition of the oxide film cross-sectional layers of the two Cr-Ni-Mo hot-work die steels were analyzed using scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), and X-ray diffraction (XRD). The influences of Cr, Ni, and Mo on the high-temperature oxidation resistance of the two Cr-Ni-Mo hot-work die steels are discussed, and the oxidation mechanism is summarized. Heat-treated samples were analyzed using electron backscattered diffraction (EBSD) to obtain inverse pole figures (IPFs) and average sample grain sizes, and the percentages of twin grain boundaries (TGBs) (θ = 60°) were also measured. After heat treatment, recrystallization was observed in both steels with a large portion of twin grain boundaries. After 10 h of oxidation, the dense chromium-rich oxide layer that formed in the inner oxide layer of 3Cr3Mo2NiW steel effectively prevented the continuation of oxidation. The inner oxide layer in 3CrNi3Mo steel formed an adhesion layer with a network structure composed mainly of Ni- and Cr-rich spinel oxide, without forming a barrier to prevent oxidation.

Rodent Area Prostriata Converges Multimodal Hierarchical Inputs and Projects to the Structures Important for Visuomotor Behaviors.

Area prostriata is a limbic structure critical to fast processing of moving stimuli in far peripheral visual field. Neural substrates underlying this function remain to be discovered. Using both retrograde and anterograde tracing methods, the present study reveals that the prostriata in rat and mouse receives inputs from multimodal hierarchical cortical areas such as primary, secondary, and association visual and auditory cortices and subcortical regions such as the anterior and midline thalamic nuclei and claustrum. Surprisingly, the prostriata also receives strong afferents directly from the rostral part of the dorsal lateral geniculate nucleus. This shortcut pathway probably serves as one of the shortest circuits for fast processing of the peripheral vision and unconscious blindsight since it bypasses the primary visual cortex. The outputs of the prostriata mainly target the presubiculum (including postsubiculum), pulvinar, ventral lateral geniculate nucleus, lateral dorsal thalamic nucleus, and zona incerta as well as the pontine and pretectal nuclei, most of which are heavily involved in subcortical visuomotor functions. Taken together, these results suggest that the prostriata is poised to quickly receive and analyze peripheral visual and other related information and timely initiates and modulates adaptive visuomotor behaviors, particularly in response to unexpected quickly looming threats.

Localization of area prostriata and its connections with primary visual cortex in rodent.

Area prostriata (Pro) has been found to play important roles in the rapid processing of moving stimuli in the far peripheral visual field. However, the specific neural substrates responsible for these functions remain unknown. In this study, we first examined the location, extent, and topography of the rodent equivalent of the primate Pro based on cytoarchitecture and molecular markers. We then identified its intimate connections with the primary visual cortex (V1) using retrograde and anterograde tracers. Our main finding is that medial V1, which receives peripheral visual information, has strong reciprocal connections with the Pro in both rat and mouse while lateral V1 has significantly fewer such connections. The direct V1 inputs to the Pro provide at least one of the shortest pathways for visual information to reach the Pro, and may be crucial to the fast processing of unexpected stimuli in the peripheral visual field.

Afferent Projections to Area Prostriata of the Mouse.

Area prostriata plays important roles in fast detection and analysis of peripheral visual information. It remains unclear whether the prostriata directly receives and integrates information from other modalities. To gain insight into this issue, we investigated brain-wide afferent projections to mouse prostriata. We find convergent projections to layer 1 of the prostriata from primary and association visual and auditory cortices; retrosplenial, lateral entorhinal, and anterior cingulate cortices; subiculum; presubiculum; and anterior thalamic nuclei. Innervation of layers 2-3 of the prostriata mainly originates from the presubiculum (including postsubiculum) and anterior midline thalamic region. Layer 5 of the prostriata mainly receives its inputs from medial entorhinal, granular retrosplenial, and medial orbitofrontal cortices and anteromedial thalamic nucleus while layer 6 gets its major inputs from ectorhinal, postrhinal, and agranular retrosplenial cortices. The claustrum, locus coeruleus, and basal forebrain provide relatively diffuse innervation to the prostriata. Moreover, Cre-dependent tracing in cortical areas reveals that the cells of origin of the prostriata inputs are located in layers 2-4 and 5 of the neocortical areas, layers 2 and 5 of the medial entorhinal cortex, and layer 5 of the retrosplenial cortex. These results indicate that the prostriata is a unique region where primary and association visual and auditory inputs directly integrate with many limbic inputs.

Homotopic Commissural Projections of Area Prostriata in Rat and Mouse: Comparison With Presubiculum and Parasubiculum.

Area prostriata in primates has recently been found to play important roles in rapid detection and processing of peripheral visual, especially fast-moving visual information. The prostriata in rodents was not discovered until recently and its connectivity is largely unknown. As a part of our efforts to reveal brain-wide connections of the prostriata in rat and mouse, this study focuses on its commissural projections in order to understand the mechanisms underlying interhemispheric integration of information, especially from peripheral visual field. Using anterograde, retrograde and Cre-dependent tracing techniques, we find a unique commissural connection pattern of the prostriata: its layers 2-3 in both hemispheres form strong homotopic commissural connections with few heterotopic projections to bilateral medial entorhinal cortex. This projection pattern is in sharp contrast to that of the presubiculum and parasubiculum, two neighbor regions of the prostriata. The latter two structures project very strongly to bilateral medial entorhinal cortex and to their contralateral counterparts. Our results also suggest the prostriata is a distinct anatomical structure from the presubiculum and parasubiculum and probably plays differential roles in interhemispheric integration and the balancing of spatial information between two hemispheres.

STIM1 overexpression in hypoxia microenvironment contributes to pancreatic carcinoma progression.

OBJECTIVE: Stromal interaction molecule 1 (STIM1) overexpression has been reported to play an important role in progression of several cancers. However, the mechanism of STIM1 overexpression and its relationship with hypoxia in pancreatic ductal adenocarcinoma (PDAC) remains unclear. METHODS: STIM1 and HIF-1α expression was tested using immunohistochemistry in tissue microarray (TMA) including pancreatic cancer and matched normal pancreatic tissues, and their relationships with clinicopathological parameters were statistically analyzed. q-PCR, Western blot, ChIP, and luciferase assay were employed to 030 analyze transcriptional regulation between HIF-1α and STIM1 in pancreatic cancer PANC-1 cells. RESULTS: Both STIM1 and HIF-1α showed higher positive rates and up-regulated expression in cancer tissues compared to that of normal tissues (P < 0.05). The Kaplan-Meier method revealed that higher HIF-1α and STIM1 expression levels were significantly correlated with decreased disease-free survival ( P = 0.025 and P = 0.029, respectively). The expression of HIF-1α showed a significant positive correlation with that of STIM1 in cancer tissues (rs = 0.3343, P = 0.0011) and pancreatic cancer cell lines. Furthermore, ChIP and luciferase assays confirmed that HIF-1α bound to the STIM1 promoter and regulated its expression in PANC-1 cells. CONCLUSIONS: In hypoxia microenvironment, up-regulated expression of STIM1 mediated by HIF-1α promotes PDAC progression. HIF-1α and STIM1 are potential prognostic markers and/or therapeutic targets for PDAC treatment.

Lambert-Eaton myasthenic syndrome in patients with small cell lung cancer: Report of five cases.

OBJECTIVE: To further evaluate the clinical characteristics of small cell lung cancer (SCLC) with Lambert-Eaton syndrome. METHODS: We reviewed the patient database of our hospital from 2001 to 2013 to evaluate and analyze the patients of SCLC with Lambert-Eaton syndrome. The clinical characteristics and prognosis of the patients were analyzed in this retrospective study. RESULTS: From reviewing our hospital database, we included 5 SCLC patients with Lambert-Eaton syndrome from 202 SCLC subjects with an incidence rate of 2.5%. The median age of the 5 patients was 52 (41-71) with 4 male and 1 female. The myasthenia symptom can be detected in 2-20 months before the pathology confirmation for small cell lung carcinoma. The general electromyography characteristics of Lambert-Eaton syndrome was reduction in action potential amplitude after repetitive peripheral never stimulation at low frequency and increased amplitude at high frequency. CONCLUSION: Lambert-Eaton syndrome was sometimes found in patients with SCLC which was useful for diagnosis of non-small cell lung carcinoma in a relatively early stage.