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Background and Objective. Dual-source CT (DSCT) has been used to detect coronary artery anomalies. The purpose of this study was to assess the incidence of anomalous origin of the coronary artery in Chinese adults. Methods. We summarised all patients who underwent DSCT coronary angiography (CTCA) from December 2006 to February 2008, and data of anomalous origin of the coronary artery in Chinese adults were recorded. Results. 1879 patients underwent CTCA during that period; 24 patients with an anomalous origin of the coronary artery were detected, giving an incidence of 1.3%. Fifteen patients had an anomalous origin of the right coronary artery (12 from left coronary sinus, 3 high takeoff), eight patients had an anomalous origin of the left coronary artery (LCA from posterior sinus of Valsalva in three cases, LCX from the right coronary sinus, LCX from RCA, high takeoff, LCA from right coronary sinus, and single coronary artery in one case, respectively), and one patient had an anomalous origin of both coronary arteries (high takeoff). Conclusion. The incidence of anomalous origin of the coronary artery in Chinese adults in this study is 1.3%. DSCT can clearly visualise the anomalous origin and course of the coronary artery and is a useful screening modality. (Neth Heart J 2010;18:466-70.).

We investigated the thermal stability and spectroscopic properties of the 1.53 μm emission from 4I13/2 → 4I15/2 transition of Er3+ ions in Er3+/Yb3+-codoped Ga-Bi-Pb-Ge heavy metal oxide glass for use in broadband fiber amplifiers. It was noted that the addition of GeO2 effectively enhanced the thermal stability of the heavy metal oxide glass studied. The emission peak located at approximately 1530 nm with a full width at half-maximum of approximately 58 nm. The measured lifetime and the calculated emission cross-section of this transition were ∼3.2 ms and ∼10.3×10−21 cm2, respectively. As a result, Ga-Bi-Pb-Ge heavy metal oxide glasses were assumed to be potential host material for the 1.53 μm broadband optical fiber amplifiers.

This paper reports on the optical spectroscopic properties and thermal stability of Er3+-doped antimony-borosilicate glasses for developing 1.5 microm optical amplifiers. Upon excitation at 980 nm laser diode, an intense 1.5 microm infrared fluorescence has been observed with the maximum full width at half maximum (FWHM) of 90 nm for Er3+-doped antimony-borosilicate glasses. The emission cross-section and the lifetime of the 4I13/2 level of Er3+ ions are 6.3 x 10(-21) cm2 and 0.30 ms, respectively. It is noted that the product of the emission cross-section and FWHM of the glass studied is as great as 567 x 10(-21) cm2 nm, which is comparable or higher than that of bismuthate and tellurite glasses.

This paper reports on frequency upconversion emission properties of Tm 3+ /Yb 3+ - and Ho 3+ /Yb 3+ -codoped Ga 2 O 3 –GeO 2 –Bi 2 O 3 –PbO glass upon excitation of 980 nm laser diode. The dependence of the upconversion emission intensity upon the excitation power has been examined and the involved mechanisms have also been discussed. An intense blue emission at 476 nm and two weak red emissions at 650 and 689 nm have clearly been observed in Tm 3+ /Yb 3+ -codoped samples, which are assigned to the 1 G 4 → 3 H 6 , 1 G 4 → 3 F 4 and 3 F 2,3 → 3 H 6 transitions of Tm 3+ ions. The cube-like dependence of the 476 and 650 nm emissions on the incident pump laser power, indicates three-photon contribute to the blue–red upconversion emissions, respectively. Meanwhile intense green and red emissions peaked at 545 and 660 nm in Ho 3+ /Yb 3+ -codoped samples, which are ascribed to the transitions of ( 5 F 4 , 5 S 2 ) → 5 I 8 and 5 F 5 → 5 I 8 transitions of Ho 3+ , have been confirmed that two photons contribute to these upconversion processes. The observed upconversion emission intensity as function of Yb 3+ concentration suggests that the presence of the Yb 2 O 3 plays a major role in enhancing the upconversion emission efficiency.

Er3+-doped tellurite glasses TeO2–GeO2–Nb2O5–Na2O–K2O–ZnO have been investigated for developing 1.5-μm fiber and planar amplifiers. Effects of GeO2 and Nb2O5 on the thermal stability and optical properties of Er3+-doped tellurite glasses have been discussed. It is noted that the incorporation of GeO2 or Nb2O5 increases the thermal stability of tellurite glasses significantly. Er3+-doped GeO2- and Nb2O5-modified tellurite glasses exhibit the stimulated emission cross-section as great as 10.7 × 10−21 cm2, which is significantly higher than that of silicate and phosphate glasses. In addition, the intensity of upconversion luminescence of the Er3+-doped GeO2- and Nb2O5-modified tellurite glasses decreased clearly with increasing GeO2 or Nb2O5 content. As a result, Er3+-doped tellurite glasses might be a potential candidate for developing laser or optical amplifier devices.

GdAl3(BO3)4 polycrystals co-doped with Yb3+ and Eu3+ has been synthesised by combustion method with urea. Upon the excitation at 465 nm (Eu3+/7F6-->5D2 transition), emission bands centered at 590, 613, 697 and 702 nm in the wavelength region of 550-750 nm have clearly been observed, assigned to the electronic transitions of 5D0-->7FJ (J=1, 2, 4 and 5) of Eu3+ ions, respectively. Meanwhile, an intense emission centred at 980 nm along with a shoulder at 1,040 nm has also been observed by exploiting a cross-relaxation process between the transitions of Eu3+/5D0-->7F6 and Yb3+/2F7/2-->2F5/2. On the contrary, an intense red up-conversion emission centred at 613 nm originated from the 5D0-->7F2 transition of Eu3+ has been observed upon excitation with 980 nm laser diode. The quadratic dependence of the red up-conversion intensity on the pump-laser power reveals a cooperative energy transfer mechanism from a pair of Yb3+ ions to one Eu3+ ion.

We investigate the spectroscopic properties of the 1.5-microm emission from the (4)I(13/2)--(4)I(15/2) transition of Er(3+) ions in bismuth-germanate-lead glasses for applications in broadband fiber amplifiers. The emission peak locates at 1532nm with a full width at half-maximum (FWHM) of approximately 65nm. The measured lifetime and the calculated emission cross-section of this transition are 3.3ms and 8.66x10(-21)cm(2), respectively. IR-to-green-upconversion occurs simultaneously upon excitation of the 1.5-microm emission with a commercially available 980nm laser diode. Effects of PbF(2) content on the thermal stability, structure and spectroscopic properties of Er(3+)-doped bismuth-germanate-lead glasses have been examined. We find that the substitution with PbF(2) provides a couple of potentials: shortening the UV cutoff band and decreasing the phonon energy of host glasses. Codoping of Yb(3+) significantly enhances both the green-upconversion and 1.5-microm emission intensity by means of a nonradiative Yb(3+)--Er(3+) energy transfer. Energy transfer processes and nonradiative phonon-assisted decays could account for the population of the (2)H(11/2) level, which is an emitting level of the green-upconversion of Er(3+). The results indicate the possibility towards the development of bismuth-germanate-lead based glasses as photonics devices.

This paper reports on the spectroscopic properties and energy transfer in Ga 2 O 3 –Bi 2 O 3 –PbO–GeO 2 glasses doped with Tm 3+ and/or Ho 3+ . From the optical absorption spectra of Tm 3+ , Judd–Ofelt intensity parameters, radiative transitions probabilities, fluorescence branching ratios, and radiative lifetimes have been calculated using Judd–Ofelt theory. The measured differential scanning calorimetry result shows that the glass exhibits excellent stability against devitrification with Δ T = 129 °C. The measured luminescence spectra show that the 3 H 4 → 3 F 4 transition of Tm 3+ upon 808 nm laser diode excitation possess a broad full width at half-maximum of ∼126 nm. The maximum value calculated stimulated emission cross-section and the measured lifetime of 3 H 4 level from the 1.47-μm transition are ∼4.73 × 10 −21 cm 2 and ∼0.239 ms, respectively. It is noticed that codoping of Ho 3+ could significantly enhanced the ratio of the intensity of 1.47–1.80 μm by energy transfer via Tm 3+ : 3 F 4 → Ho 3+ : 5 I 7 .

We report on 2.0-microm emission characteristic and energy transfer of Ho3+-doped tellurite glass sensitized by Tm3+ upon excitation of a conventional 808 nm laser diode. The Judd-Ofelt strength parameters, spontaneous radiative transition probabilities and radiative lifetime of Ho3+ have been calculated from the absorption spectra by using the Judd-Ofelt theory. Significant enhancement of 2.0-microm emission of Ho3+ has been observed with increasing Tm3+ doping up to 0.7 mol%. The energy transfer coefficient of the forward Tm3+--Ho3+ is approximately 17 times larger than that of the backward Tm3+--Ho3+ energy transfer. Our result indicates that the maximum gain of 2.0-microm emission, assigned to the transition of (5)I7--(5)I8 of Ho3+, might be achieved from the tellurite glass at the concentration of 0.5 mol% of Tm2O3 and 0.15 mol% of Ho2O3. The high gain coefficient and quantum efficiency (1.16) along with the large value of the product of the stimulated emission cross-section and the measured radiative lifetime (4.12 x 10(-27) m(2)s) of the Ho3+/Tm3+-codoped tellurite glasses might find potential applications in efficient 2.0-microm laser.

We report the spectroscopic properties of Tm3+-doped and Tm3+/Ho3+-codoped [Ga2O3–GeO2–Bi2O3–PbO (PbF2)] glasses for S-band optical amplifications. The Judd–Ofelt intensity parameters have been determined based on the measured absorption spectra. It is found that PbF2-modified glasses exhibit a lower Ω2 value, and the addition of PbF2 caused the chemical bond associated with Tm3+ ions to be more ionic. The PbF2-free glasses have large peak emission cross-sections in the range of 2.15–2.18 × 10−21 cm2. Meanwhile, the studied glasses exhibit broad 1.47 μm emission with the full width at half-maximum of 119–126 nm. The results indicate that these glasses are useful host material for broadband S-band fiber amplifiers.

This paper investigated on the dehydration of Er 3+ -doped phosphate glasses using O 2 + CCl 4 bubble flow method. The influence of parameters of dehydration effect was studied systemically. It was found that the dehydration rate was rather rapidly at the initial stage of bubbling. Increasing gas flow rate and temperature could drive the dehydration process toward lower OH concentration in the melts. The dehydration process was carried out in open system and analyzed by thermodynamic theory of open system, which clarified the process of eliminating of OH groups from the glass melts with bubbling time and gas flow rate. A time-dependent empirical equation about reaction rate constant was derived, and the relationships between rate constant and bubbling flow rate, and temperature were also discussed. This analytical method could be applicable to the dehydration of glass melt using other dehydration agents.

We report on the blue-green-red up-conversion spectroscopic properties of Pr 3+ /Yb 3+ -codoped oxyhalide tellurite glasses upon excitation of a conventional 980 nm laser diode (LD). Significant enhancement of the blue-green-red up-conversion emission intensity has been observed with increasing PbCl 2 doping. The up-conversion intensity has a quadratic dependence on incident pump laser power, indicating a two-photon process. The population of the Pr 3+ upper 3 P 0 emitting level was accomplished through a combination of a ground state absorption, energy transfer and excitated state absorption. 1.3-μm emission in the second telecom window originated from Pr 3+ : 1 G 4 → 3 H 5 transition has also been investigated upon excitation at 980 nm LD. The measured peak wavelength and full width at half-maximum of the fluorescent are 1335 nm and ∼100 nm, respectively. An enhanced 1.3μm emission with increasing PbCl 2 doping has also been observed. Codoping of Yb 3+ significantly enhance both the blue-green-red up-conversion emission and 1.3-μm emission intensity by way of a nonradiative Yb 3+ : 2 F 5 →Pr 3+ : 1 G 4 energy transfer.

The 2.0 μm emission originating from Ho 3+ : 5 I 7 → 5 I 8 transition in Ho 3+ /Tm 3+ -codoped gallate-bismuth-germanium-lead glasses were investigated upon excitation with 808 nm laser diode (LD). Energy transfer (ET) process between Tm 3+ : 3 F 4 level and Ho 3+ : 5 I 7 level was also discussed. It was noted that the measured peak wavelength and stimulated emission cross-section of Ho 3+ -doped bismuth-germanium-lead glasses were ∼2.02 μm and 5.1×10 −21 cm 2 , respectively. Intense emission of Ho 3+ in Tm 3+ /Ho 3+ -codoped GBPG glass were observed, which resulted from the ET between Tm 3+ : 3 F 4 and Ho 3+ : 5 I 7 level upon excitation with 808 nm LD.

Centralized control using the wide-area information has been suggested to enhance the dynamic performance of large interconnected power systems. According to the inverse system method and LQR optimal control theory, this paper presents a nonlinear hierarchical global controller based on the wide-area information including the on-line measured center of rotor angle and total unbalanced power. Moreover, it has been verified that the optimal control in the sense of linear quadratic state regulator principle for the linearized system is equivalent to an optimal control in the sense of extended quadratic output regulator performance index for the primitive nonlinear system. So, the designed controller is an optimal controller for the nonlinear system digital simulation demonstrates that the multi-machine power system under the nonlinear global control has less settling time, swing times, oscillatory peak value and more critical clearing time and better voltage stability performance than that under PID control and nonlinear decentralized control.

We investigate the spectroscopic properties of the 1.5-μm emission from the 4I13/2 → 4I15/2 transition of Er3+ ions in PbO–Bi2O3–Ga2O3–GeO2 glasses for applications in broadband fiber amplifiers. The measured emission peak locates at 1,532 nm with a full width at half-maximum of ∼45 nm. The glasses exhibit a large stimulated emission cross-section of 0.89 × 10−20 cm2 and a large $$ {\text{FWHM}} \times {\text{ $ \sigma $ }}_{{\text{e}}} ^{{{\text{peak}}}} $$ product of 40.0. Infrared-to-green upconversion occurs simultaneously upon excitation of the 1.5-μm emission with a commercially available 980 nm laser diode. The green-upconversion intensity has a quadratic dependence on incident pump laser power, indicating a two-photon process. Energy transfer processes and nonradiative phonon-assisted decays could account for the population of the 2H11/2 of Er3+. The results indicate the possibility towards the development of lead–bismuth–gallate–germanate based glasses as photonics devices.