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As a high-resulotion biological imaging technology, photoacoustic microscopy (PAM) is difficult to use in real-time imaging due to the long data acquisition time. Herein, a fast data acquisition and image recovery method named sparse PAM based on a low-rank matrix approximation is proposed. Specifically, the process to recover the final image from incomplete data is formulated into a low-rank matrix completion framework, and the “Go Decomposition” algorithm is utilized to solve the problem. Finally, both simulated and real PAM experiments are conducted to verify the performance of the proposed method and demonstrate clinical potential for many biological diseases.

In this study, the Richardson–Lucy (R–L) iteration, Tikhonov (T–K) regularization, and fast iterative shrinkage-thresholding algorithm (FISTA) are first used to deblur streak images. The deblur performances of these three methods are compared with that of Wiener deconvolution. The spatial resolutions of Wiener deconvolution, R–L iteration, T–K regularization, and FISTA improved from 9 mm to 4.5, 5, 5, and 5 mm, respectively. The root-mean-square errors (RMSE) of one -, two -, and three-plane targets decreased effectively using these three deblur methods. The R–L iteration performs the best in terms of the RMSE for the two-plane target. The effects of the parameters used in each method are investigated.

A diode side-pumping gain module designed and optimized to provide even fluorescence distribution is demonstrated. Heat effects of lasers using the optimized module are considerably lower comparing with that using the unoptimized commercial module. In the master oscillator power amplifier operation, the output pulse energy reaches 4.4 mJ at the repetition rate of 1 kHz with the pulse width of 900 ps; and the thermal focal length is ~50% longer than that of the unoptimized module under the same condition.

The implementation of coal-to-gas shift in rural households for meeting people's heating and cooking demands can reduce pollutant emissions, improve indoor air quality and increase climate, health and economic co-benefits. In rural Baoding and Langfang regions of Hebei Province, China, approximately 1.25 million households have shifted from coal to natural gas combustion. Field-based emission factors, modified combustion efficiency, and thermal efficiency of typical gas stoves were measured to evaluate the contribution of this shift to local air pollution control. Natural gas burning in stoves produced much lower air pollution than coal or other popular fuel/stove combinations due to its good fuel properties and high combustion efficiency. All tested gas stoves were rated at excellent tiers according to Chinese national standards. Through the adoption of coal-to-gas shift during a complete winter heating season, the total emissions of carbon monoxide (CO), carbon dioxide (CO2), sulfur dioxide (SO2), nitric oxide (NO), methane (CH4), particles with an aerodynamic diameter of ≤2.5 μm (PM2.5) and ≤10 μm (PM10) were reduced by 98%, 56%, 33%, 80%, 82%, 99% and 99% in rural Baoding region, and by 99%, 37%, 25%, 83%, 71%, 99% and 99% in rural Langfang region, respectively. Correspondingly, GWC100 values decreased from 11 396 to 4 554 and from 13 408 to 7 881 ktCO2e·heat season−1·city−1 for the two cities, respectively. The estimated 7 083, 1 142, 8 834, 3 422, and 2 464 all-cause mortality cases resulting from the intakes of CO, NO, SO2, PM2.5 and PM10 were avoided in rural Baoding region, and 5 771, 467, 7 432, 2 762 and 1 987 cases were avoided in rural Langfang region, among which cardiopulmonary death was the primary reduced mortality. The average economic benefits were 10.40 and 9.98 billion CNY (Chinese Yuan), which was equivalent to 3.19% and 3.22% of the local GDPs.

An all-diode-pumped Nd:YAG burst-mode laser was demonstrated. A diode-laser-side-pumped Nd:YAG laser with Qswitcher, as laser oscillator, was employed to produce burst pulse directly. When the diode-laser worked at 10Hz and Qswitcher was operated at 10kHz, a maximum burst energy of 456mJ was obtained in the master oscillator with the highest optical efficiency of ~30%. Each burst included 19 pulses in the pumping duration of 2ms. A master oscillator and power amplifier architecture was adapted to scale the burst energy to meet PLIF system applications. The burst energy of 456mJ obtained from laser oscillator was amplified to 2.2J by use of three diode-laser-side-pumped Nd:YAG modules as laser amplifiers. The energy extraction efficiency of each stage was achieved to ~13%, ~22% and ~24%, respectively. The single pulse energy of 1064nm laser at 10 kHz reached to ~116 mJ with pulse width of 9.8 ns and a peak power of ~11.8 MW. The performances of pulse-burst laser we constructed can be better and improved greatly by use of more amplifiers.

Planar laser induced fluorescence (PLIF) diagnosis technology has been widely applied in flow field study and combustion diagnosis. Due to the complexity of the experimental environment of practical PLIF applications, The PLIF diagnostic system needs a good environment adaptation. In this paper, we reported a high energy Nd:YAG MOPA laser with repetition rate of 500Hz, which was applied in PLIF diagnostic system. A diode-laser side-pumped Nd:YAG module, which was pumped from five directions and optimized for better gain distribution, was employed to build a EO Q-switched Nd:YAG oscillator. A stable structure design of oscillator resonant cavity was used to improve the environmental adaptability of Nd:YAG laser. In our environmental adaptation experimentation, the laser oscillator has an energy fluctuation of

Microenvironmental factors such as oxygen concentration mediate key effects on the biology of mesenchymal stromal cells (MSCs). Herein, we performed an in-depth characterization of the metabolic behavior of MSCs derived from the placenta, umbilical cord, and adipose tissue (termed hPMSCs, UC-MSCs, and AD-MSCs, respectively) at physiological (hypoxic; 5% oxygen [O2]) and standardized (normoxic; 21% O2) O2 concentrations using chemical isotope labeling liquid chromatography-mass spectrometry. 12C- and 13C-isotope dansylation (Dns) labeling was used to analyze the amine/phenol submetabolome, and 2574 peak pairs or metabolites were detected and quantified, from which 52 metabolites were positively identified using a library of 275 Dns-metabolite standards; 2189 metabolites were putatively identified. Next, we identified six metabolites using the Dns library, as well as 14 hypoxic biomarkers from the human metabolome database out of 96 altered metabolites. Ultimately, metabolic pathway analyses were performed to evaluate the associated pathways. Based on pathways identified using the Kyoto Encyclopedia of Genes and Genomes, we identified significant changes in the metabolic profiles of MSCs in response to different O2 concentrations. These results collectively suggest that O2 concentration has the strongest influence on hPMSCs metabolic characteristics, and that 5% O2 promotes arginine and proline metabolism in hPMSCs and UC-MSCs but decreases gluconeogenesis (alanine-glucose) rates in hPMSCs and AD-MSCs. These changes indicate that MSCs derived from different sources exhibit distinct metabolic profiles.

We demonstrated an 879-nm-diode-pumped Nd:Gd

The placenta resides in a physiologically low oxygen microenvironment of the body. Hypoxia induces a wide range of stem cell cellular activities. Here, we report a workflow for exploring the role of physiological (hypoxic, 5% oxygen) and original cell culture (normoxic, 21% oxygen) oxygen concentrations in regulating the metabolic status of human placenta-derived mesenchymal stem cells (hPMSCs). The general biological characteristics of hPMSCs were assessed via a variety of approaches such as cell counts, flow cytometry and differentiation study. A sensitive 13C/12C-dansyl labeling liquid chromatography–mass spectrometry (LC–MS) method targeting the amine/phenol submetabolome was used for metabolic profiling of the cell and corresponding culture supernatant. Multivariate and univariate statistical analyses were used to analyze the metabolomics data. hPMSCs cultured in hypoxia display smaller size, higher proliferation, greater differentiation ability and no difference in immunophenotype. Overall, 2987 and...

A laser-diode-pumped broadband and continuously frequency-tuned all-solid-state Nd:YVO

Background Severe fever with thrombocytopenia syndrome (SFTS) is a severe viral disease caused by SFTSV. It is important to estimate the rate of missed SFTS diagnosis and to further understand the actual incidence in high endemic areas in China. Methods This study was conducted in two high SFTS endemic provinces in 2015. Patients hospitalized in 2014 or within 1 year before investigation were selected after considering their clinical manifestations, specifically, fever, platelet, and white blood cell. During retrospective investigation, sera were collected to detect SFTSV antibodies to assess SFTSV infection. To further understand SFTSV infection, acute phase sera were detected; SFTSV infection rate among a healthy population was also investigated to determine the basic infection level. Results In total, 246 hospitalized cases were included, including 83 cases (33.7%) with fever, thrombocytopenia and leukopenia, 38 cases (15.4%) with fever and thrombocytopenia but without leukopenia, and 125 cases (50.8%) without fever but with thrombocytopenia and leukopenia. In total, 13 patients (5.3%) were SFTSV IgM antibody-positive, 48 (19.5%) were IgG-positive. Of the 13 IgM-positive cases, 11 (84.6%) were IgG-positive (9 with titres ≥1:400). Seropositive rates of antibodies were high (8.4% for IgM and 30.1% for IgG) in patients with fever, thrombocytopenia and leukopenia. Furthermore, among IgG-positive cases in this group, 76% (19/25) of patients’ IgG antibody titres were ≥1:400. Additionally, 28 of 246 cases were initially diagnosed with suspected SFTS and were then excluded, and 218 patients were never diagnosed with SFTS; the seropositive rates of IgM and IgG in these two groups were 25% and 67.9% and 2.8% and 13.3%, respectively. These rates were 64.3% and 21.4% in 14 sera collected during acute phase of the 28 cases mentioned above. Seropositive rate of SFTSV IgG was only 1.3% in the patient-matched healthy group, and no IgM antibody was detected. A preliminary estimate of 8.3% of SFTS cases were missed in SFTS high endemic provinces. Conclusions The actual SFTS incidence was underestimated. Effective measures such as adding a new SFTS case category - “SFTS clinical diagnosis cases” or using serological detection methods during acute phase should be considered to avoid missed diagnoses. Electronic supplementary material The online version of this article (10.1186/s12879-018-2970-7) contains supplementary material, which is available to authorized users.

We demonstrated a Nd:YAG based Q-switched burst-mode MOPA laser with ultraviolet output by nonlinear harmonic generation. Single-pulse energy of 13.4 mJ at 355 nm, 10 kHz was obtained. The pulse width reached 10 ns.

A continuously frequency-tuned laser diode end-pumped Nd:YVO

Early detection is vital to improve the overall survival rate of bladder cancer (BCa) patients, yet there is a lack of a reliable urine-based assay for early detection of BCa. Urine metabolites represented a potential rich source of biomarkers for BCa. This study aimed to develop a metabolomics approach for high coverage discovery and identification of metabolites in urine samples. Urine samples from 23 early stage BCa patients and 21 healthy volunteers with minimum sample preparations were analyzed by a short 30 min UPLC-HRMS method. We detected and quantified over 9000 unique UPLC-HRMS features, which is more than four times than about 2000 features detected in previous urine metabolomic studies. Furthermore, multivariate OPLS-DA classification models were established to differentiate urine samples from bladder cancer cohort and normal health cohort. We identified three BCa-upregulated metabolites: nicotinuric acid, trehalose, AspAspGlyTrp, and three BCa-downregulated metabolites: inosinic acid, ureidosuccinic acid, GlyCysAlaLys. Finally, analysis of six post-surgery BCa urine samples showed that these BCa-metabolomic features reverted to normal state after tumor removal, suggesting that they reflected metabolomic features associated with BCa. ROC analyses using two linear regression models to combine the identified markers showed a high diagnostic performance for detecting BCa with AUC (area under the ROC curve) values of 0.919 to 0.934. In summary, we developed a high coverage metabolomic approach that has potential for biomarker discovery in cancers.

Femtosecond time-resolved coherent anti-Stokes Raman spectroscopy (CARS) is utilized to study the ultrafast vibrational dynamics in ethanol at room temperature. The beat wavenumbers between Raman modes of C H stretch modes (from 2800 cm−1 to 3000 cm−1) in ethanol are excited and detected by varying wavelengths of the laser pulses and detection window. The coherence relaxation times of the C H stretch mode in ethanol are measured.

Human fecal samples contain endogenous human metabolites, gut microbiota metabolites, and other compounds. Profiling the fecal metabolome can produce metabolic information that may be used not only for disease biomarker discovery, but also for providing an insight about the relationship of the gut microbiome and human health. In this work, we report a chemical isotope labeling liquid chromatography-mass spectrometry (LC-MS) method for comprehensive and quantitative analysis of the amine- and phenol-containing metabolites in fecal samples. Differential (13)C2/(12)C2-dansyl labeling of the amines and phenols was used to improve LC separation efficiency and MS detection sensitivity. Water, methanol, and acetonitrile were examined as an extraction solvent, and a sequential water-acetonitrile extraction method was found to be optimal. A step-gradient LC-UV setup and a fast LC-MS method were evaluated for measuring the total concentration of dansyl labeled metabolites that could be used for normalizing the sample amounts of individual samples for quantitative metabolomics. Knowing the total concentration was also useful for optimizing the sample injection amount into LC-MS to maximize the number of metabolites detectable while avoiding sample overloading. For the first time, dansylation isotope labeling LC-MS was performed in a simple time-of-flight mass spectrometer, instead of high-end equipment, demonstrating the feasibility of using a low-cost instrument for chemical isotope labeling metabolomics. The developed method was applied for profiling the amine/phenol submetabolome of fecal samples collected from three families. An average of 1785 peak pairs or putative metabolites were found from a 30 min LC-MS run. From 243 LC-MS runs of all the fecal samples, a total of 6200 peak pairs were detected. Among them, 67 could be positively identified based on the mass and retention time match to a dansyl standard library, while 581 and 3197 peak pairs could be putatively identified based on mass match using MyCompoundID against a Human Metabolome Database and an Evidence-based Metabolome Library, respectively. This represents the most comprehensive profile of the amine/phenol submetabolome ever detected in human fecal samples. The quantitative metabolome profiles of individual samples were shown to be useful to separate different groups of samples, illustrating the possibility of using this method for fecal metabolomics studies.

Femtosecond time-resolved coherent anti-Stokes Raman spectroscopy is utilized to study the ultrafast vibrational dynamics in BBO crystals at room temperature. The beat wavenumbers between Raman modes and coherence decay rates of Raman modes (at 1214 cm −1 and 1437 cm −1 ) in BBO crystals are excited and detected. The intensities of vibrational modes in BBO crystals are found that they can be controlled by geometrical configuration.

We demonstrated a cavity-dumped burst-mode 1.06 μm side-pumped Nd:YAG laser and its dual-stage dual-pass amplified laser performance. The cavity dumping process has been theoretically studied and the output performance has been experimentally investigated. At the pumping duration of 2 ms and pumping frequency of 10 Hz, burst energy, peak power and pulse width of the amplified laser reached 1.89 J, 2.87 MW and 3.1 ± 0.3 ns, respectively, at the Q-switch repetition rate of 100 kHz. The maximum energy extraction efficiency reaches to 30%.

We demonstrate a linearly frequency-modulated laser from a laser diode (LD) pumped Nd:YVO

Classification of pork soft tissues, including skin, fat, loin, tenderloin and ham muscles, was achieved using combination of laser-induced breakdown spectroscopy, principal component analysis and k nearest neighbors classification.

A high-efficiency, high-repetition-rate burst-mode 1064 nm laser under pulsed 878.6 nm laser diode pumping is demonstrated. Pulses at repetition rates ranging from 10 kHz to 100 kHz are produced during the time period of 1 ms pumping duration by using an acousto-optical Q-switch. The maximum pulse burst energy of 44 mJ at 10 kHz is obtained at the incident pump power of 108.5 mJ, yielding an optical-to-optical efficiency of 40.5%. The shortest pulse width at 10 kHz is 9.4 ns at the maximum pump energy of 108.5 mJ. The peak powers are estimated to be ~468.1 kW and 30.1 kW at 10 kHz and 100 kHz in the burst-mode oscillator.

Waveform sampling LiDAR is a hot topic in LiDAR technique due to its high precision geodesy and multi-layer target detection ability. Especially, the LiDAR systems applying streak tube have encouraging application due to their special properties about high-sensitivity and full waveform sampling ability. This paper describes a kind of LiDAR system applying the full waveform sampling stripe principle array. Basing on the planar fitting of square object, the elevation error of points cloud got from flight experiment is analyzed. The statistical properties of elevation error are got.

We demonstrated a high-energy burst-mode Nd:YVO 4 /Nd:YAG MOPA laser. A LD pumped Nd:YVO 4 acousto-optically Q-switched laser works as oscillator and three side pumped Nd:YAG modules as the amplifiers. During the burst duration of 1ms, maximum pulse burst energy of 730 mJ at 10 kHz is obtained with single pulse energy of 73 mJ and a pulse width of 9.3 ns.

We demonstrated a cavity-dumped burst-mode 1.06μm laser and its amplified laser performances. At pumping duration of 2ms, burst energy, peak power and pulse width reached 1.89J, 2.87MW and 3.1±0.3ns, respectively, at Q-switch repetition rate 100kHz.

Laser-induced plasma ignition of a premixed methane/air flame was investigated with different repetition rates. Flame stabilization in terms of flame kernel catch-up was achieved. Temporal evolution of the flame kernels at different repetition rates was investigated.

This article gave a brief research about solid-state dye laser based on PMMA polymer doped with different laser dye through pre-polymerization method, and showed good fluorescence and laser characteristics in experimental research.

The incidence and mortality rate of biliary tract cancer have been increasing worldwide; however, its diagnosis and prognosis have not improved in recent years. A novel approach, termed 'metabolomics', may have the potential to be developed as an effective diagnostic tool. The present study prospectively obtained bile samples from 115 individuals, including 32 patients with biliary tract cancer, 61 patients with benign biliary tract diseases and 22 normal controls. A liquid chromatography/mass spectrometry (LC/MS)‑based approach was used to investigate the differences in bile samples between the three groups, followed by multivariate statistical analysis, which included partial least squares projection to latent structures with discriminant analysis (PLS‑DA) and orthogonal projection to latent structures with discriminant analysis (OPLS‑DA). The metabolomic 2D score plot and 3D plot revealed clear separation between the cancer, benign and normal control groups by PLS‑DA. To further address the significant difficulties in clinically differentiating between biliary tract cancer and benign biliary tract diseases, OPLS‑DA was performed to distinguish between the two disease groups and to select potential biomarkers. The cancer and benign groups were well differentiated. The metabolic analysis revealed significantly lower levels of lysophosphatidylcholine, phenylalanine, 2‑octenoylcarnitine, tryptophan and significantly higher levels of taurine‑ and glycine‑conjugated bile acids in the bile from patients with biliary tract cancer compared with those in the bile from patients with benign biliary tract disease. The present study suggested that an LC/MS‑based metabolomic investigation provides a potent and promising approach for discriminating biliary tract cancer from benign biliary tract diseases and the identified specific metabolites may offer potential as novel biomarkers for the early detection of biliary tract cancer.

We utilized femtosecond time-resolved coherent anti-Stokes Raman spectroscopy (CARS) to study the ultrafast vibrational dynamics in distilled water at room temperature. The CARS signals from the broad OH-stretching modes between 3100 cm−1 and 3700 cm−1 were obtained and analyzed. The dephasing times of four Raman modes in water were detected and compared.

Spectrally dispersed femtosecond time-resolved coherent anti-Stokes Raman spectroscopy is applied to study the ultrafast vibrational dynamics in ethanol at room temperature. The anti-Stokes intensities were monitored as a function of delay time and wavenumber. By simply changing the timing of the laser pulses, the vibrational dynamics between the excited Raman transitions in ethanol molecules can be tracked and detected. Copyright © 2014 John Wiley & Sons, Ltd.

Spectrally dispersed femtosecond time-resolved coherent anti-Stokes Raman spectroscopy is utilized to study the ultrafast vibrational dynamics in rhodamine B dye in solution at room temperature. The anti-Stokes intensities are monitored as a function of time and wavenumber. By simply changing the timing of laser pulses, the vibrational dynamics of excited Raman transitions in rhodamine B molecules can be tracked and detected.

We report on the harmonics radiation and spectrum properties in the Xe–Ar gas mixture by using tight focusing laser pulses. The cutoff position is extended from the harmonic H33–H37 in mixed gases. The extended orders are attributed to the harmonic radiation from Xe+. We observe that the harmonics are decreased in the plateau region. The result is attributed to the destructive interference of the harmonics generated from the different atoms. Our results suggest that using the Xe–Ar mixture as nonlinear can obtain the coherent XUV source.

Metabonomics has emerged as an important technology for exploring the underlying mechanisms of diseases and screening for biomarkers. In this investigation, to comprehensively assess metabolite changes in D-galactosamine (GalN)-induced liver injury in Chinese miniature pigs and to increase our understanding of physiological changes in normal and pathological states, we used ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS) to analyze metabolites and identify biomarkers in serum. Blood samples were collected both from 18 h after GalN treatment group and control group pigs. We performed multivariate analyses on the metabolite profiles to identify potential biomarkers of acute liver injury, which were then confirmed by tandem MS. Based on "variable of importance in the project" (VIP) values and S-plots, four groups of biomarkers were identified--namely conjugated bile acids, lysophosphatidylcholines (LPCs), phosphatidylcholines (PCs) and fatty acid amides (FAAs)--that were present at significantly different levels in the control and GalN-induced groups. LPCs, PCs, and FAAs showed marked decreases in the GalN-treated group, whereas conjugated bile acids in the treated group showed considerable increases. Taken together, our results suggested that obvious metabolic disturbances occur during acute liver injury, which provided novel insights into the molecular mechanism(s) of D-galactosamine (GalN)-induced liver injury, and will facilitate future research and management of liver injury.

We experimentally study the harmonics from a Xe-He gas mixture using tight-focusing femtosecond laser pulses. The spectrum in the mixed gases exhibits an extended cutoff region from the harmonic H21 to H27. The potential explanation is that the harmonics photons from Xe contribute the electrons of He atoms to transmit into the excited-state. Therefore, the harmonics are emitted from He atoms easily. Furthermore, we show that there are the suppressed harmonics H15 and H17 in the mixed gases. The underlying mechanism is the destructive interference between harmonics generated from different atoms. Our results indicate that HHG from Xe-He gas mixture is an efficient method of obtaining the coherent soft X-ray source.

In this paper, solid dye samples were prepared by codoping laser dyes Pyrromethene 567 (PM567) as the energy donor and Rhodamine 610 (Rh610) as the energy acceptor into the ethanol modified poly (methyl methacrylate) matrix (MPMMA) to enhance the properties of the solid dye lasers. The fluorescence intensity of the acceptor was enhanced by up to 9 fold with the introduction of the donor molecules. The laser efficiency of the dye mixture doped samples was improved by up to 8 times relative to that of the samples solely doped with the acceptor, and the highest slope efficiency was obtained as 70.4%. The radiative and nonradiative energy transfer rate constants ( K R and K NR ) were calculated using the Stern–Volmer plots and the acceptor concentration dependence of the radiative and nonradiative transfer efficiencies were also obtained. The K R was three orders of magnitude higher than the K NR , indicating the dominance of the radiative energy transfer mechanism in the present system. The deviation of the Stern–Volmer plot from the linearity demonstrated that both the dynamic and transient quenching mechanism exist in the present energy transfer system.

Metabonomics has become a highly sensitive and powerful tool for screening of biomarkers and elucidation of biochemical processes. Recently, we reported beneficial therapeutic effect of human placenta mesenchymal stem cells (hPMSCs) transplantation on d-galactosamine (GalN)-induced liver injury in Chinese miniature pigs. However, the underlying mechanism remains largely unclear. Here, UPLC/TOF/MS-based metabonomics approach was employed to analyze serum from GalN-treated pigs with the goal of identifying potential biomarkers for acute liver injury. Our results showed that obvious metabolic disturbance occurred during acute liver failure (ALF), which can be ameliorated by the hPMSCs transplantation. The metabolic profiles of the hPMSCs transplantation group returned back to the original state 5 weeks after the hPMSCs transplantation. In addition, the result obtained from metabolic trajectory analysis correlated well with those from biochemical analysis and histological examination. Serum levels of several metabolites including glycoursodeoxycholic acid, glycochenodeoxycholic acid, aromatic amino acids, phosphatidylcholine, lysophosphatidylcholine and sphingomyelin, were significantly modified during the process of ALF and cell treatment. Taken together, our study has gained new insight into the molecular mechanism on how hPMSCs administration facilitates the recovery of ALF, and provided strong support for treating liver diseases with stem cell-based therapies.

We improve the performance of an acousto-optical Q-switched Nd:YAG 946 nm laser using a convex–plane cavity. We obtain the highest output average power of 2.3 W with a pulse width of 15.3 ns in a 10 kHz 946 nm laser with a convex–plane cavity. The maximum peak power 15.0 kW is about three times higher than that in a plane–plane cavity. Also we investigate the output performances of the pulsed 946 nm laser with the convex–plane cavity at 20 and 50 kHz.

The effects of thermal treatment on infrared optical properties of SiO 2 films on Si substrates by ion beam sputtering technology were investigated. Complex refractive index of SiO 2 films was calculated from Fourier transform infrared transmission spectrum from 400 to 4000 cm − 1 . Absorption band properties associated with Si-O-Si stretching, bending, rocking mode at about 1080 cm − 1 , 816 cm − 1 , 460 cm − 1 were analyzed. With the increase of thermal annealing temperature, the absorption peak with Si-O-Si stretching, rocking mode shift to long wave number, but the bending mode shifts to short. After thermal treatment, the infrared optical constants are close to the value of the more stabilized thermal grown SiO 2 . So, it can be concluded that the structure of Si-O-Si network in SiO 2 films deposited on Si was modified to the stable structure of thermal grown SiO 2 .

We report the temperature influence on the voltage-controlled diffractive property of Mn-doped potassium sodium tantalate niobate crystal. The crystal was grown by the top seeded solution growth method. Its quadratic electro-optic coefficients achieved as high as R11 = 3.50 × 10−15 m2/V2 and R12 = −0.44 × 10−15 m2/V2 near the Curie temperature, while they declined with the increasing temperature. The external electric field which correspond to the maximum diffraction efficiency of photorefractive grating moved from 166 V/mm to 512 V/mm as the temperature increased from 25 °C to 32.5 °C. The maximum diffraction efficiencies all reached the maximum value of 60% at different temperatures. The results were discussed and compared with the theoretical equations.

The energy transfer upconversion and the ground state absorption are considered in solving the rate equations for an active Q-switched quasi-three-level laser. The dependence of output pulse characters on the laser parameters is investigated by solving the rate equations. The influence of the energy transfer upconversion on the pulsed laser performance is illustrated and discussed. By this model, the optimal parameters could be achieved for arbitrary quasi-three-level Q-switched lasers. An acousto-optical Q-switched Nd:YAG 946 nm laser is constructed and the reliability of the theoretical model is demonstrated.

In radar cross section (RCS) calculation of a rough surface, the model can be simplified into the scattering of geometrically idealized bosses on a surface. Thus the problem of the RCS calculation of a rough surface is changed to the RCS calculation of the semicircular boss. The RCS measurement of scale model can help save time and money. The utilization of terahertz in RCS is attractive because of its special properties: the wavelength of the terahertz wave can help limit the size of the model in a suitable range in the measurement of the scale model and get more detailed data in the measurement of the real object. However, usually the incident beam of a terahertz source is a Gaussian beam; in the theoretical RCS estimation, usually a plane wave is assumed as the incident beam for sake of simplicity which may lead to an error between the measurement and calculation results. In this paper, the method of images is used to calculate the RCS of a semicircular boss at 2.52 THz and the results are compared to the one calculated when the incident beam is a plane wave.

Single crystal paraelectric K 0.99 Li 0.01 Ta 0.60 Nb 0.40 O 3 is grown with a room-temperature Curie temperature ( T c ). The parameters of the Sellmeier dispersion equation were determined. A large quadratic electro-optic (QEO) effect was observed. The QEO coefficient R 11 reaches as high as 2.48 × 10 −15 m 2 V −2 around T c . The induced refractive index change under an electric field of 500 V/mm is 40 times bigger than that of commonly used LiNbO 3 . The large QEO coefficient makes single crystal K 0.99 Li 0.01 Ta 0.60 Nb 0.40 O 3 a promising candidate in optical devices.

Changes in membrane lipid composition play multiple roles in plant adaptation and survival in the face of chilling and freezing damage. The ultra-performance liquid chromatography/quadrupole-TOF-MS (UPLC/Q-TOF-MS)-based approach was developed for investigating the lipid changes during cold exposure in Stephanodiscus sp. followed by multivariate statistical analysis including principal components analysis, partial least squares discriminant analysis and orthogonal projection on latent structure discriminant analysis for data classification and potential biomarkers selection. The analysis demonstrated dramatic lipid alterations take place in both extraplastidic and plastidic membranes. Thirty-eight lipid molecules were selected and identified as putative biomarkers, including chlorophyll a degradation products, triacylglycerol, phosphatidylcholine, phosphatidylglycerol, sulfo-quinovosyldiacylglycerol, monogalactosyldiacylglyceroll, lyso-phosphatidylglycerol, lyso-phosphatidylcholine, lyso-monogalactosyldiacylglycerol and lyso-sulfoquinovosyldiacylglycerol. These metabolites have been shown previously to function in energy storage, membrane stability and photosynthesis efficiency. This study is the first one using UPLC/Q-TOF-MS-based lipidomic profiling with multivariate statistical analysis to explore the lipidomic changes of microalgae in response to stress conditions, which promotes better understanding of their physiology and ecology.

We present the results of a comprehensive study of the thermal effect in a Nd:GdVO quasi-three-level 912 nm CW laser. The thermal focal length is measured by the interferometry method and then the fractional thermal loading is estimated to be about 0.36. Our results demonstrate the energy-transfer up-conversion, and absorption effects of the excited state cannot be ignored due to their influence on the heat generation of the quasi-three-level 912 nm laser operation.

The effects of pressure and laser energy on the excitation temperature, electron number density and spark energy of laser induced plasmas (LIPs) in nitrogen were investigated using an ungated spectrometer with an electron multiplying charge-coupled device (EMCCD) camera as the detector. The plasmas were generated in nitrogen of 1.2×104 Pa to 1.0×105 Pa by 532 nm output of a 10 Hz Q-switched Nd:YAG laser with pulse energy ranging from 20 mJ to 100 mJ. The excitation temperatures were found around 3 eV, and varied little with pressure and laser energy. The electron number densities increased from 5.8×1017 cm−3 to 4.7×1018 cm−3 when the pressure was increased from 1.2×104 Pa to 1.0×105 Pa, but varied little with laser energy. The spark energy increased linearly with the input laser energy, and saturated at 35–60% of the input energy. Comparisons with results of time-resolved measurements and of other authors indicate that the ungated spectrometer can give reasonable results on excitation temperature and electron number density of LIPs, although it suffers intrinsic limitations involved with its inability to be time-resolved, and can serve as an option to lower systematic cost for practical applications of laser induced plasmas.

In RCS measurement, usually the incident beam is a Gaussian beam or a similar beam source; however, in the theoretical RCS estimation, usually a plane wave is assumed as the incident beam for sake of simplicity. In this paper, the RCS of an infinite perfect conducting cylinder is estimated. In the estimation, the influence of a 2.52 THz laser beam on RCS is studied and the RCS in dependence with scattering angle and some other factors is obtained after the change of RCS equation; meanwhile, comparisons of RCS when the incident beam is a plane wave and a Gaussian beam respectively, are also given. The estimation results show, when the cylinder radius is 10 mm, choosing a beam width of 40 mm can keep the relative error less than 0.48 dB.