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A flow-controlled microfluidic device for parallel and combinatorial screening of crystalline materials can profoundly impact the discovery and development of active pharmaceutical ingredients and other crystalline materials. While the existing continuous-flow microfluidic devices allow crystals to nucleate under controlled conditions in the channels, their growth consumes solute from the solution leading to variation in the downstream composition. The materials screened under such varying conditions are less reproducible in large-scale synthesis. There exists no continuous-flow microfluidic device that traps and grows crystals under controlled conditions for parallel screening. Here we show a blueprint of such a microfluidic device that has parallel-connected micromixers to trap and grow crystals under multiple conditions simultaneously. The efficacy of a multi-well microfluidic device is demonstrated to screen polymorphs, morphology, and growth rates of l-histidine via antisolvent crystallization at eight different solution conditions, including variation in molar concentration, vol% of ethanol, and supersaturation. The overall screening time for l-histidine using the multi-well microfluidic device is ∼30 min, which is at least eight times shorter than the sequential screening process. The screening results are also compared with the conventional 96-well microtiter device, which significantly overestimates the fraction of stable form as compared to metastable form and shows high uncertainty in measuring growth rates. The multi-well microfluidic device paves the way for next-generation microfluidic devices that are amenable to automation for high-throughput screening of crystalline materials.

To intelligently control the parameters of a semiconductor pulsed seed source, a novel scheme is presented involving commercial electronic chips as switching devices to drive a semiconductor laser (SL). By combining theoretical analysis and rate-equation theory, we construct a mathematical model of the SL. Further, a pulsed laser module with real-time tunable optical pulse parameters is designed and implemented. The tunable pulse width ranges from 90 ps (PS) to continuous wave, and the tunable pulse repetition rate is 0–10 MHz. the SL temperature drift is less than 0.07 °C. The experimental results verify the feasibility of the design scheme, and the theoretical analysis and simulation results guide the generation of high-quality optical pulses.

Narrow line-width fiber lasers are useful in gas-sensing, but systems that are both tunable and stable are rare. Here, we describe a single-wavelength ring cavity erbium-doped photonic crystal fiber laser (ED-PCFL) that can align the acetylene (C2H2) gas absorption peak with high precision and a maximum deviation less than 0.012 nm. Rather than using a combination of erbium-doped fiber and a strong nonlinear fiber, ED-PCF was used as a gain medium to achieve a stable single-wavelength output based on the non-linear polarization rotation effect (NPR). This was selected because ED-PCF has a strong nonlinear effect. We added the dual polarization controllers (PCs) to weaken the homogeneous broadening based on the traditional tunable filter (TF) filtering structure. The results show that these steps improve the tunability of the laser wavelength and enhance the stability of the light source. The final laser had a side-mode suppression ratio as high as 60 dB over 45 nm with a maximum fluctuation in wavelength less than 6 pm. The peak power standard deviation was ∼0.03 dB during the 2 h experimental time. The peak power response of ED-PCFL was studied as a function of C2H2 concentrations, and the calculated R-squared value was 0.993. This means that the ED-PCFL is suitable for C2H2 sensing.

Millimeter wave technology is one of the technologies developed rapidly in recent years. The research was mainly to study the transmission of millimeter wave through textile material named silk fabric. We observed the phenomenon of sub-millimeter-wave transmission and reflection of the silk fabric, and concluded that with the number of silk fabric layers increasing, effect of scattering and absorption of the millimeter wave enhanced. The conclusion could be further employed in millimeter wave and THz imaging, dangerous goods inspection and other security application.

Development of non-noble metal catalyst for low-temperature methane oxidation is extremely important yet is still a challenge. Here, we construct a defective N-doped Co3O4 by a facial N2 plasma engraving method. The obtained catalyst exhibits excellent catalytic activity with methane conversion rate of 6.5 μmol g−1 s-1 at reaction temperature of 342 °C and space velocity of 46,800 mL g−1 h−1, which is about 7.3 times that of pristine Co3O4, and is among the highest active non-noble metal catalyst. The catalyst also shows high stability under hydrothermal environment. By systematic characterization and theory calculations, the superior performance could be attributed to the defective structure, enhanced redox property and highly exposed active sites. Meanwhile, N doping plays significant role in activating Co3O4 by improving the electrophilicity of surface oxygen and lowering C–H bond activation energy. The study will bring significative insight into the design of advanced Co3O4 catalysts for methane oxidation.

A kind of erbium-doped photonic crystal fiber (EDPCF) designed for superfluorescent fiber source is reported. The proposed EDPCF is composed of an erbium-doped core and a cladding with seven rings of air holes arranged in a circular structure. The full-vector finite-element model of the EDPCF has been established and the relevant characteristics have been demonstrated via simulations. Using anisotropic perfectly matched layer as an absorbing boundary condition, the confinement loss 5.27×10−12dB/m has been calculated, which is far below the level of 0.01dB/km. Furthermore, the splice losses between the EDPCF and the two types step-index fibers have been estimated and it implies that the design fulfills low splice loss conditions theoretically. The designed EDPCF had been fabricated successfully. The experiment had been carried out to evaluate the splice losses between the EDPCF and the common single mode fibers. It is turned out that using manual aligning mode of the fiber fusion splicer can obtain lower splice loss than using automatic aligning mode for PCF splice. The EDPCF has already been applied in the superfluorescent light source as the gain medium.

ZnO/Ni3ZnC0.7/x% CNT (x = 0, 2, 5, 10) urchin-like structures have been synthesized using a facile method based on metal-organic frameworks (MOFs) and applied as the electromagnetic absorber. The results of the experiments demonstrate that the content of multi-wall carbon nanotubes (MWCNT) has a great influence on the absorbing performance of the hybrid material. Conduction loss, interfacial polarization and ferromagnetic resonance all contribute to the electromagnetic absorption. The urchin-like ZnO/Ni3ZnC0.7/5% CNT composite presents excellent absorbing properties. When the filler loading of ZnO/Ni3ZnC0.7/5% CNT composite in paraffin matrix is only 10 wt.%, a minimum reflection loss of &minus, 33.2 dB is achieved at a layer thickness of 4.9 mm.

A fiber ring resonator (FRR) constructed using a Panda polarization-maintaining fiber does not effectively solve the problem of temperature-related polarization fluctuation, which considerably limits the detection accuracy of the resonant fiber optic gyro. The polarization-maintaining photonic crystal fiber (PM-PCF) can improve the thermal stability of the FRR. In this study, a structure that can simultaneously detect the polarization fluctuation of two FRRs is designed. We analyzed and verified the polarization phase shift errors of these two types of fibers, which are caused by the thermally induced birefringence changes. Theoretical simulation and experimental results confirm that a PM-PCF can be used to optimize the FRR, which can effectively suppress the polarization fluctuation.

The radiation effects of three Er3+-doped superfluorescent fiber sources (SFSs), which are based on three segments of Er-doped fibers with different lengths, are studied experimentally. We observed that the radiation-induced attenuation of the signal light of the 1530 nm band for an SFS is less than that of the 1560 nm band. Thus, the trimming technique of the Gauss-like spectra is investigated to reduce the mean wavelength drift. A filter was customized and used in superfluorescent fiber sources. To further reduce output power loss, the method with feedback control of pump power was adopted in the SFS. Then, the trimming spectral SFS with pump feedback control was tested under irradiation environment at the dose rate of 2.988 Gy/h. The experimental results demonstrate that the mean wavelength drift is &lt, 40 ppm and the loss of output power is &lt, 0.2 dB under a total dose higher than 1000 Gy. These findings confirm the significance of the method in improving radiation-resistant capabilities of fiber sources under irradiation environments.

The radiation effects of two erbium-doped superfluorescent fiber sources (SFSs) are studied in gamma ray environment. Two types of output spectrum profile (twin-peaked spectrum and single-peaked spectrum) of SFSs are constructed by different configuration and parameters. The dependence of radiation-induced power loss and spectra evolution on the dosage is revealed. The results show that the amplitudes of radiation-induced power decrease are quite similar in two SFSs. But the mean wavelength variation of the single-peaked spectrum SFS is approximately 25 times smaller than that of the twin-peaked spectrum SFS. Compared to the twin-peaked spectrum SFS, the single-peaked spectrum SFS presents better radiation tolerance, which should have potential advantages in space applications.

A double-pass forward configuration superfluorescent fiber source (SFS) based on erbium-doped photonic crystal fiber (EDPCF) with a high intrinsic mean wavelength stability is presented. The main factors of SFS instability with temperature variation are analyzed. Optimization of the high-stable SFS is achieved by combining high-performance EDPCF, optimal fiber length, and source structure with fine-tuning pump power. The temperature dependence of the SFS mean wavelength has been reduced to below 0.077 ppm/°C with temperature variation from 70 to −40 °C. To the best of our knowledge, this value is the closest to 0 ppm/°C in the reported references, and these new developments probably constitute an important step for high-accuracy interferometric fiber-optic gyroscope sources.

A facile method was developed to synthesizeγ-MnO2with different structures and surface properties in this paper.γ-MnO2was prepared by oxidation of MnSO4with Na2S2O8at90°C for 2.0 h.γ-MnO2formed at initial pH 1.0 (M1) and 8.5 (M2) was composed of MnO1.93·0.23H2O and MnO1.96·0.18H2O, respectively. The higher ratio of pyrolusite in M2 (Pr=43.90%) than that in M1 (Pr=24.86%) indicated that compared with M1, M2 would absorb more protons since the planar oxygen atoms in pyrolusite were incompletely coordinated and liable to absorb the protons. Meanwhile, the higher oxidation valence of Mn in M2 than that in M1 revealed that the Mn atoms in M2 were more liable to draw the electron density from the surface oxygen atoms in hydroxyl groups. The structural and compositional differences between M1 and M2 were the major reasons why M2 possessed a higher surface potential and a weaker ability to absorb Zn2+ions.

The influence of sodium dodecyl sulfonate (SDSN) on the formation of ZnO nanorods fromε-Zn(OH)2was investigated in this paper. Theε-Zn(OH)2precursor was prepared at room temperature using ZnSO4and NaOH as the reactants and then converted to ZnO nanorods after aging at 80°C in NaOH solution containing a minor amount of sodium dodecyl sulfonate (SDSN). The experimental results and the molecular simulation revealed that the influence of SDSN on the formation of ZnO fromε-Zn(OH)2should be attributed to the adsorption of SDSN onε-Zn(OH)2surfaces, which inhibited the dissolution ofε-Zn(OH)2in NaOH solution, leading to the formation of the ZnO nanorods with a diameter of 50–200 nm, a length of 3.0–15.0 μm, and an aspect ratio of 30–100.

A superfluorescent fiber source (SFS) with the low Ge-doped and Er/Ce codoped photonic crystal fiber (ECPCF) is proposed to improve the radiation resistance of SFS. The radiation effects of SFSs for an Er/Ce codoped conventional fiber (ECF) and a low Ge-doped and ECPCF are investigated in a Co60 gamma-ray environment. Results show that the low Ge-doped photonic crystal fiber exhibits better radiation tolerance than its counterpart in the Er/Ce codoped fibers, and the attenuation of the power of ECPCF-SFS is significantly smaller than that of ECF-SFS. In addition, the radiation-induced spectral variation of ECPCF-SFS with increased radiation dose is less than that of ECF-SFS. ECPCF-SFS simultaneously exhibits higher recovery performance than ECF-SFS.

High reflectivity ( > 93.5%) distributed Bragg reflectors (DBRs) have been successfully produced using the AlGaN/AlN multilayer stacks materials system by metal-organic chemical vapor deposition (MOCVD). The peak reflectance of the DBRs was located at 320 nm. The nominal Al composition is 30%, and the layer thicknesses of the different periods stack were designed for a target wavelength of 330 nm. We present reflectivity, SEM, AFM and XRD data of Al x Ga 1− x N/AlN Bragg reflectors grown on (0 0 0 1)-oriented sapphire. The surface of the AlN/AlGaN DBRs was found to grow in quasi-two-dimensional (2D) mode, which was indicated by the atomic force microscopy (AFM). The DBR has very smooth surface and the interface was distinct.

The m-plane GaN (1 1¯ 0 0) epilayers have been grown on LiAlO2 (1 0 0) substrate by a two-step growth method using a metal-organic chemical vapor deposition (MOCVD) system. The GaN buffer layer is introduced to overcome the drawbacks of thermal instability of LiAlO2 (LAO), and to relieve the strains due to large thermal mismatch between LAO and GaN. The results of X-ray diffraction (XRD) and polarized Raman scattering spectra demonstrate that the GaN (1 1¯ 0 0) epilayer is single crystal as the growth temperature of the buffer layer is in the range of 850–950 °C. Moreover, it is found that the surface nitridation process on LAO substrate can result in the formation of the GaN poly-crystalline films, which is due to the unintentional growth of a thin layer of c-phase AlN on LAO surface.

AlN/Al 0.3 Ga 0.7 N distributed Bragg reflectors (DBRs) are grown on sapphire (0 0 0 1) by metal-organic chemical vapor deposition (MOCVD). The number of stacks of the DBRs varies between 6 and 30. The thickness of the quarter-wave layers is designed such that the target peak reflectance locating at the wavelength of 330 nm. The GaN or AlGaN templates are employed for growing the AlN/AlGaN DBRs. It is found that the templates intensively influence on the surface roughness and the interfacial properties of AlN/AlGaN DBRs. The result of atomic force microscopy indicates that the AlN/AlGaN DBRs grow on GaN template under quasi-two-dimensional mode. And the good interfaces of AlN/AlGaN not only clearly observed by cross-sectional scanning electron microscopy, but also concluded from narrow width and high orders of satellite peaks detected by high-resolution X-ray diffraction. The peak reflectance of 20 stacks DBRs on GaN template reaches up to 82% located at 326 nm.While those DBRs grown on AlGaN template do not show such structural and optical properties due to the rough surface of AlGaN template and the poor interfaces of AlN/AlGaN.

The radiation resistance effect of two superfluorescent fiber sources using Er-doped photonic crystal fiber is studied under 500 Gy gamma-ray irradiation. One is trimmed into a quasi-Gaussian spectrum by a filter and the other is not trimmed. The results show that the SFS with spectrum trimming has a smaller radiation induced attenuation and a higher mean wavelength stability (2.616 dB and 24.803 ppm) than that of the SFS without spectrum trimming (3.187 dB and 611.766 ppm). Therefore, this method has practical use for improving radiation resistance in space environment.

To determine the lethal effect of combining fast neutron with photon radiation on the OS-732 cell line. We examined the effect of irradiation by fast neutrons, photons and a mixed beam (fast neutrons plus photons) on the lethality and colony forming ability of the OS-732 cell line at different times. Following a single irradiation close, the lethality was markedly strong at 24, 48 and 72 h in the group treated with fast neutrons alone and in the mixed beam group in which there was a high proportion of fast neutrons. The lethal effect of a fast neutron and mixed beam with a high proportion of fast neutrons on the OS-732 cell line is highly significant. These studies provide guidance for the clinical application of fast neutrons for osteosarcoma treatment.

A high-stability erbium-doped superfluorescent photonic crystal fiber source (SPCFS) is presented. Optimization of the high-stable SPCFS is achieved by combining high-performance EDPCF, optimal fiber length, and source structure with suitable pump power. The result shows a 56.979 ppm mean wavelength stability of a prototype SPCFS is demonstrated with the temperature varied in the range of −40 °C—70 °C. Especially, in the room temperature, the mean wavelength stability of a prototype SPCFS is less than 2.59 ppm, which will be approaching the requirement for inertial-grade fiber optic gyroscopes.

Polarization maintaining (PM) photonic crystal fiber (PCF) and Er-doped PCF technologies are investigated for interferometer fiber optic gyroscope (IFOG) applications. A PM-PCF optimized to achieve low-loss and high polarization extinction splice-joints with conventional PM fiber pigtails of a multifunction integrated optical circuit (MIOC) was drawn and tested under different temperature conditions. The loss and polarization crosstalk properties of a fiber coil made from the PM PCF were measured and compared with conventional PM fiber. An erbium-doped PCF was designed and fabricated, with which a superfluorescent fiber source (SFS) was made and tested. The results show that an IFOG with the PM-PCF coil and the Er-doped PCF source could achieve better temperature performance. An experimental PCF-based prototype IFOG was built and tested , and preliminary results was obtained. © (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

A quasi-Gaussian erbium-doped superfluorescent photonic crystal fiber source was proposed for improving the mean wavelength stability of conventional superfluorescent fiber source. A 28.2 ppm wavelength stability is achieved with the temperature change of 50 °C.

A high-stable and broadband single-pass backward configuration superfluorescent fiber source based on erbium-doped photonic crystal fiber (EDPCF) is proposed. With the proper EDPCF length, pump power, and a gain flattening filter, we demonstrate that it is possible to create a high-stable and broadband erbium-doped superfluorescent photonic crystal fiber source (SPCFS). This was accomplished by replacing the conventional erbium-doped fiber with the EDPCF, the intrinsic thermal coefficient of which is four times less than the measured conventional erbium-doped fibers. The SPCFS showed that the total output power stability was less than 0.0337%, the 3-dB spectral width was broader than 42 nm, the output spectrum flatness was less than 1 dB, and the mean wavelength stability was less than 2.58 ppm over 6 h at temperatures from 24.3°C to 25.5°C, which approached the requirement for inertial-grade fiber optic gyroscopes.

A superfluorescent fiber source (SFS) based on an Er3+-doped photonic crystal fiber (EDPCF) is reported. Owing to the temperature insensitivity of the EDPCF, we show that it is possible to improve the mean wavelength stability of an SFS. Using single-backward configuration, the EDPCF SFS mean wavelength variation at temperatures from −40°C to 60°C is less than 100 ppm, indicating that the thermal coefficient of the EDPCF is smaller than 1 ppm/°C and 3–6 times smaller than those of two conventional Er3+-doped fibers under the same experimental conditions. The best performance of the EDPCF-based SFS is obtained between 0°C and 60°C, at which the change in the mean wavelength is only 17.445 ppm.

A single-pass backward configuration superfluorescent fiber source (SFS) based on erbium-doped photonic crystal fiber (EDPCF) with a high mean wavelength stability was proposed. The EDPCF was used to improve the intrinsic temperature dependence of the SFS. Using the optimal EDPCF length of 24.2 m and pump power of 204 mW, a 20.7 ppm mean wavelength stability of a prototype SFS was demonstrated with increased temperature from -40 °C to 60 °C. The mean wavelength had an ultra stability of 10.3 ppm with increased temperature from -20 °C to 60 °C.