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Additional file 1. Supporting Information.

Full drive-by-wire electric vehicles (FDWEV) with X-by-wire technology can achieve independent driving, braking, and steering of each wheel, providing a good application platform for autonomous driving technology. Path planning and tracking control, in particular, are critical components of autonomous driving. However, It is challenging to comprehensively design an robust control algorithm by integrating vehicle path planning in a complicated unstructured scenario for FDWEV. To address the above issue, this paper first proposes the artificial potential field (APF) method for path planning in the prescribed park with different static obstacles to generate the reference path information, where speed planning is incorporated considering kinematics and dynamic constraints. Second, two tracking control methods, curvature calculation (CC-based) and model predictive control (MPC-based) methods with the lateral dynamics model, are proposed to track the desired path under different driving conditions, in which a forward-looking behavior model of the driver with variable preview distance is designed based on fuzzy control theory. CarSim-AMESim-Simulink co-simulation is conducted with the existence of obstacles. The simulation results show that the proposed two control approaches are effective for many driving scenarios and the MPC-based path-tracking controller enhances dynamic tracking performance and ensures good maneuverability under high-dynamic driving conditions.

Additional file 1. Supporting information.

For surveys in areas with difficult access, ground-based electromagnetic (EM) systems are difficult to operate, time-consuming, and expensive, whereas airborne EM (AEM) systems are unsafe and uneconomic for small survey areas. We have developed a new frequency-domain airborne electromagnetic (FAEM) system called the ground-airborne frequency-domain EM (GAFEM) system to achieve rapid data acquisition in complex terrains with high safety and low cost. The system consists of a grounded electrical source and an airborne receiver carried by an unmanned rotorcraft. The grounded electrical source transmits a [Formula: see text] pseudorandom series obtaining signals at [Formula: see text] frequencies in one flight, which can maintain the resolution without reducing efficiency. The airborne receiver based on the unmanned rotorcraft makes the system flexible, convenient, and economical to operate in areas with difficult access. The system can conduct surveys in far- and non-far-field regions and can obtain the apparent resistivity to present a quick overview of the subsurface structure. To demonstrate the GAFEM system’s effectiveness and practical detection potential, we have performed two field surveys that revealed the shallow structure with tunnels and the deep structure at source-receiver distances of 3 and 6 km, respectively. The GAFEM system effectively revealed the apparent-resistivity difference with a sufficient investigation depth at large source-receiver distances. Thus, the system can be extended to various important applications for rapid surveys or deep investigations in areas with difficult access.

Nanotechnology offers exciting and innovative therapeutic strategies in the fight against cancer. Nano-scale hydroxyapatite, the inorganic constituent of the hard tissues of humans and animals, is not only an ideal carrier for the delivery of drugs but also exerts selective inhibitory effects on tumor cells. To perform the dual functions, we propose polyglutamic acid-coordinated hydroxyapatite nanoparticles (HA-PGA NP) as both DOX delivery vehicle and sustained calcium flow supplier to achieve a synergistic, tumor-specific therapy in this study. With PGA as the coordinator, the HA-PGA NPs were easily assembled into spherical nano-clusters with low crystallinity. The excellent dispersibility and solubility in the tumor environment endowed the HA-PGA NPs with an improved internalization into the tumor cells, thereby causing a dramatic elevation in the intracellular calcium influx by about 40%, which further induced a cascade of mitochondrial membrane damage, ATP content reduction, and reinforced sensitivity to chemotherapy. After the encapsulation of the model drug DOX, a pH-responsive release profile was achieved via the degradation of the nanoparticles and the deprotonation of PGA in the acidic tumor micro-environment. Consequently, the hybrid system, with the synergistic effects of sustained DOX and calcium overload, exhibited selectively intensified toxicity to tumor cells. The in vivo test further confirmed that the current system exhibited highly selective tumor inhibition and reduced heart toxicity, thus representing an effective anti-tumor platform.

The objectives of this study were to obtain the optimal technical parameters of steam explosion for rapeseed and investigate the effects of pretreatment on the bioactive components and characteristics of three diverse samples of Brassica seed (Brassica napus, B. juncea and B. rapa) and their products. Under the optimal conditions, Brassica napus formed the largest amount of canolol, namely, 1210.10 mg/kg; B. rapa formed the smallest amount, namely, 82.70 mg/kg; and the canolol content was 2110.00 mg/kg in Brassica napus oil. Meanwhile, compared to the traditional cold-pressed rapeseed oil, the total tocopherol and phytosterol contents in Brassica napus, B. rapa and B. juncea oil increased by 5.3%, 4.8%, and 7.4% and 2.1%, 3.2%, and 5.1%, respectively. Steam explosion pretreatment also significantly affected the total phenolic contents and antioxidant capacities of the three types of rapeseeds and their processed products (P

Uncontrolled hemorrhage is one of the leading cause for death in both civilian and military trauma. The zeolite-based hemostatic agent currently available in clinic exhibits great exothermic reaction and poor biodegradability. To overcome these limitations, in this study, we developed a novel mesoporous silica (MS)-based calcium alginate nanohybrid granule (p-MS/CA) for hemorrhage control. The p-MS/CA was prepared by an in situ pore-forming, droplet process and the granule prepared was 2-3 mm in size with rough and macroporous surface. The p-MS/CA could significantly accelerate water absorption and block off the damaged tissue, and thereby efficiently promoted platelet and plasma protein adhesion, enhanced wound adherence, facilitated the contact activation pathway of coagulation cascade with desirable hemostasis. Hemostasis test demonstrated that the p-MS/CA granule could reduce about 50% hemostatic time both in vitro and vivo and decrease blood loss. Meanwhile, the nanocomposite of p-MS/CA exhibited excellent cell viability and did not induce hemolysis. Furthermore, the preparation process for multipore p-MS/CA is low-cost, quick and easy to achieve large-scale production. Owing to the superior hemostatic performance and simple preparation process, we believe that this study will provide an alternative approach for hemorrhage control in some specific injury types, and have immense potential for commercial and clinical application.

The study investigated the volatile compounds of sesame oil and the effects of microwave processing (0-8 min with 1-min intervals), mainly focusing on the integral flavor characteristics and individual aroma-active compounds. A total of 82 characteristic odors were identified using GC×GC-TOF/MS. Fifteen volatile compounds with the highest odor activity values (OAV > 100) were selected as the key odors contributing to the flavor profile of microwaved sesame oil, including 2-methyl-propanal (pungent, malt, green), 2-methyl-butanal (cocoa, almond), furaneol (caramel), 1-octen-3-one (mushroom), 4-methyl-3-penten-2-one (sweet), 1-nonanol (fat, citrus, green), 2-methyl-phenol (phenol), 2-methoxy-phenol (smoke, sweet), 2-methoxy-4-vinylphenol (clove, curry), 2,5-dimethyl-pyrazine (cocoa, roasted nut, roast beef), 2-furfurylthiol (coffee, roast), 2-thiophenemethanethiol (sulfur), methanethiol (gasoline, garlic), methional (cooked potato), and dimethyl trisulfide (fish, cabbage). The OAVs significantly increased with a longer microwave process. Meanwhile, PCA results based on E-nose and cluster analysis results based on GC×GC-TOF/MS were similar to distinguish flavor formation during the microwave process. PRACTICAL APPLICATIONS: Sesame oils were prepared by a microwave process. Aroma-active compounds with the highest OAVs in sesame oils were not clear. Identification of key aroma compounds of sesame oils could adopt a comprehensive assessment method in combination with E-nose and individual odors detection. Microwave pretreatment as a new processing technology for sesame oil extraction could reduce the time consumption and produce a unique fragrant flavor compared to the traditional roasting process.

With the rapid development of information technology, information overload has become an important challenge of Internet. In order to alleviate the growing contradiction between users and massive data, the researchers proposed the concept of the cross-harmonic recommender system. By analyzing characteristic of datasets, recommendation algorithms and method for weight calculation, we introduced a fast and general engine for large-scale data processing and implemented the cross-harmonic recommender system based on Spark, aiming at improving accuracy, diversity and efficiency of the recommender system.

Traditional degumming techniques used in the edible oil industry require high temperatures and consume more energy. As a result, green refining techniques are required to be developed. Rapeseed oil is one of the preferred edible oils used in southwest China because of its unique flavor. However, the dark color of the oil is an element of concern. It is important to find a refining method that can improve the color of the oil while retaining its flavor. The main purpose of this study was to evaluate a low-energy consumption degumming method that used different dosages (0.5%, 1.5%, 2.5%, and 3.5% w/w) of silicon dioxide when applied to rapeseed oil. The concentration of phospholipids, total phenolic content including that of canolol, and the color, flavor profile, acid value, chlorophyll content, and oxidative stability of the rapeseed oil were analyzed to evaluate the degumming effect of silicon dioxide. It was observed that the adsorption by silicon dioxide eliminated up to 85% of phospholipids from crude rapeseed oil, retained up to 96% of the total phenolic content, and had little effect on the amount of canolol, which is the dominant phenolic compound in rapeseed oil. In addition, the method improved the color of rapeseed oil by increasing the L∗/neutral value and decreasing the a∗/red values, and had little effect on the flavor according to E-nose. Using silicon dioxide as the adsorbent reduced the acid value and chlorophyll content of the oil, apart from largely shortening its induction period. When the recommended silicon dioxide dosage of 1.5% (w/w) was used, phospholipids, total phenolic content, a∗, and red values decreased by 81%, 5%, 38.2%, and 12.7%, while the L∗ and neutral values increased by 9.8% and 28.6%. This technology is economical and environmentally friendly due to its mild reaction conditions and zero wastewater production. It provided a new strategy and showed a great potential in the degumming of rapeseed oil.

Microwave pretreatment has been considered to improve the quality of rapeseed oil for canolol generation. Canolol is assumed to be formed by the decarboxylation of sinapic acid (SA). In this work, sinapic acid derivatives in 39 microwave-pretreated rapeseeds and their roles in the enhanced oxidative stability of rapeseed oils were investigated. The average contents of sinapic acid derivatives in rapeseeds, including (from high to low) sinapine, sinapoyl glucoside (SG), disinapoyl gentiobioside (DSG), quercetin-sinapoyl-di-hexosepentose (QSDG), sinapoyl malate (SM), disinapoyl glucoside (DDSG) and SA, were determined. After microwave pretreatment, the canolol content in rapeseed increased from nil to 6.16–76.1 mg/100 g, while sinapic acid derivatives contents decreased. The degradation rates of SG, DDSG, DSG, SM, SA and sinapine were 59.1%, 40.2%, 33.7%, 27.4%, 14.4% and 11.3%, respectively. There was no correlation relationship between sinapine and canolol. However, SG, DSG, SM and DDSG were regarded to be the precursor substances of canolol. Additionally, the tocopherols, sterols and canolol contents, along with the induction period (IP) of microwaved rapeseed oil increased by 3.79%, 10.0%, 76.8 times and 38.7%, respectively. There was a significant positive correlation between IP and canolol content. These findings clarify the precursor substances of canolol and provide a theoretical support for the development and utilization of canolol.

The working device weight of hydraulic excavators far exceeds that of its lifted material, requiring a large amount of energy to maintain the frequent motion of lifting and lowering. Recovering and utilizing this energy is an effective means of energy-saving for excavators. The existing electric recovery method faces disadvantages which include excessive energy conversion, a complicated system, and high cost. In this paper, an energy alternate recovery and utilization system (EARUS) based on multiple hydraulic cylinders is proposed. The concept of weight-balanced is applied to match the weight of the working device with the pressure of the hydraulic accumulator. Energy alternate recovery and utilization are realized in different hydraulic cylinders, so that the weight-balanced circuit and the original system perform the necessary oil exchange, overcoming the reliability problem of the existing isolated weight-balanced system with long-term operation. The efficiency of EARUS is comprehensively analyzed through simulation and an experiment using the methodology of energy flow decomposition. The working device motion characteristics of EARUS are then quantitatively analyzed. Results show that, compared with the original system, the energy recovery efficiency of EARUS is 65.9%, and the comprehensive energy-saving rate is 41.6%. The boom single-action time is shortened by 2.6 s, and the velocity fluctuation of the boom cylinder at the start of lowering decreases by 75%. The research findings provide an important framework for the engineering applications of this new system.

An oil sample was prepared by cold-pressing from untreated (UTRO) and microwave-treated (MWRO) rapeseed, and tertiary butyl-hydroquinone (TBHQ) was added to another oil from untreated rapeseed. Microwave pretreatment significantly increased the total phenolics and canolol contents, as well as the initial acid value (AV), peroxide value (PV), and p-anisidine value (pAV) of oil (p UTRO + TBHQ > MWRO. During storage, significant linear correlations (p

Rapeseeds were treated with microwaves under 800 W for 0, 1, 2, 3, 4, 5, 6, 7, and 8 min at a frequency of 2450 MHz, and oil was extracted with a press to investigate the influence on phenolic compounds, including sinapine, the main free phenolic acids, and canolol content in the rapeseeds and oil from them. The results indicated that sinapine and sinapic acid was the main phenolic compound and free phenolic acid in the rapeseed, respectively, and canolol was the main phenolic compound in the oil from rapeseed by cold press. Microwave treatment significantly influenced phenolic compounds content in the rapeseeds and oil from them. The sinapine, sinapic acid, and canolol content in rapeseed first increased and then decreased depending on the period of microwave radiation (p < 0.05). The canolol content of 7 min microwave pretreatment rapeseed increased to the maximum and was approximately six times greater than that of the unroasted rapeseed. The amount of canolol formed was significantly correlated with the content of sinapic acid and sinapine (for sinapic acid, r = -0.950, p < 0.001, for sinapine, r = -0.828, p < 0.05) and also the loss of sinapic acid and sinapine (for sinapic acid, r = 0.997, p < 0.001, for sinapine, r = 0.952, p < 0.05) during roasting. There were differences in the transfer rate of difference phenolic compounds to the oil extracted by press. Almost all of the sinapine remained in the cold-pressed cake and only 1.4-2.7% of the sinapic acid, whereas approximately 56-83% of the canolol was transferred to the oil. The transfer ratio of canolol significantly increased with microwave radiation time (p < 0.001). Microwave pretreatment of rapeseed benefited improving the oxidative stability of oil.

The contents of the minor components and induction period (IP) of cold-pressed oils from 203 rapeseed varieties from the Yangtze River Valley in China were determined. The average contents of total phenolics, phytosterols, tocopherols, β-carotene, lutein and chlorophyll of the samples were 36 mg/100 g, 826 mg/100 g, 378 mg/kg, 2.4 mg/kg, 104 mg/kg and 8.2 mg/kg, respectively. There were significant differences (p

Rapeseeds were adjusted to moisture contents of 9, 11, 13, and 15 % and treated with microwaves under 800 W for 0, 1, 2, 3, 4, 5, 6, and 7 min at a frequency of 2,450 MHz and oil was extracted with a press to investigate possibility of enhancing oil extraction yield by press, minor component content, and oxidative stability of the pressed oil. The results indicated that microwave pretreatment of rapeseed could increase the oil extraction yield, and both microwave time and initial moisture content of rapeseed had significant effects on the oil extraction yield (p 0.05). Phytosterol and polyphenol contents increased with increasing microwave time and with decreasing initial moisture content of rapeseeds (p

The linseed gum/cellulose composite hydrogels were successfully fabricated by mixing cellulose and linseed gum solutions dissolved in the NaOH/urea aqueous system and cross-linked with epichlorohydrin. The morphology and structure of the composite hydrogels were investigated by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffractometry (XRD) and thermogravimetric analysis (TGA). The swelling ratio and water retention properties were investigated. The results revealed that linseed gum mainly contributed to water adsorption, whereas the cellulose acted as a backbone to strengthen the porous structure. This work provided a simple way to prepare cellulose-based superabsorbent hydrogels, which could be potentially applied as an effective water conservation material in agriculture.

Rheological behavior of six crude rapeseed oils with different extraction methods including hot-pressing, solvent-extraction and cold-pressing were studied. Viscosities of the oils were measured with shear rates ranging from 0.1 to 200 s−1 at three different temperatures. The Casson model was used to fit the experimental data and the Arrhenius equation was applied to estimate the energy of activation for viscosity (E a). The extraction methods affected the total tocopherol, total phytosterols, total phenols, phosphorus and fatty acid composition. The hot-pressed medium-erucic rapeseed oil (HMRO) had the greatest viscosity, and the cold-pressed low-erucic rapeseed oil (CLRO) had the lowest viscosity among all the oils with shear rates >5 s−1 at 10 °C. The crude rapeseed oils exhibited Newtonian behavior at higher shear rates. The significant difference of viscosity of the six oils was reduced with increasing temperature, and there was no significant change (P > 0.01) among the oils with a shear rate of 100 s−1 at 50 °C. According to the values of E a, the following order of a change in viscosity was obtained as follows: CMRO > SMRO > HMRO > CLRO > SLRO > HLRO(C, cold pressed; S, solvent extracted; H, hot pressed; M, medium erucic; L, low erucic; RO, rapeseed oil). Minor components may be the contributing factors for the values of E a of rapeseed oils. The higher shear limiting viscosity (ηc) values calculated by the Casson model decreased as the temperature increased, but no significant change (P > 0.01) was observed for ηc by using different extraction methods at 50 °C.

This study compared the oxidative stability of cold-pressed rapeseed oil (CPRO) and dehulled cold-pressed rapeseed oil (DCPRO) in the dark at 60 °C and monitored the evolution of minor constituents (tocopherols, phytosterols, phenolics). The results showed that dehulling significantly influenced the oxidative stability of the oils, the DCPRO was more easily oxidized. During the autoxidation, the peroxide value (PV) and anisidine value (p-AV) of the DCPRO ranged from 2.38 to 95.97 mequiv O2 kg−1 and from 1.20 to 30.75, whereas those of the CPRO ranged from 3.80 to 46.17 mequiv O2 kg−1and from 2.69 to 14.87, respectively. Dehulling affected the contents and the rates of decrease of tocopherols and phytosterols of the cold-pressed oils, and the rates of decrease of tocopherols and phytosterols of the CPRO were lower than those of the DCPRO (10% less, on average). The rancimat induction periods (IPs) were positively correlated with the concentrations of the total tocopherols (For DCPRO, R 2 = 0.9622, For CPRO, R 2 = 0.8334). The total phenolics contents as determined by spectrophotometry first increased and then decreased. Tocopherols and phytosterols had a greater effect on oxidative stability of the rapeseed oils during the first 30 days, and phenolics had a greater effect in the 30–40 day period.

The nano-sized particles of anatase titanium oxide (TiO2) were obtained by hydrolysis of titanium ester (TNB) in basic media and dehydrated in acid media. And then the anatase titanium oxide was treated with nitrogen plasma. The effect of nitrogen plasma treating time on the activity of photo-catalytic reduction of the Cr2O72− for sample obtained was investigated. The samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Transmission Electron Microscope (TEM) and Ultraviolet (UV). A peak of 396 eV in the N 1 s XPS spectra of sample obtained with nitrogen plasma treated TiO2 showed that nitrogen-doped titanium oxide (TiO2−xNx) has been obtained. The spectra of UV showed that the light absorption of TiO2−xNx obtained by nitrogen plasma treated TiO2 for 10min. had moved to the visible region. The picture of TEM and spectra of XRD indicated that the crystallographic forms and particle dimension had no apparent change for both the modified and the unmodified TiO2. When the TiO2 sample was treated for 7 min with nitrogen plasma, it exhibited best photo-catalytic activity.

Wire behaves plastically in its elastic range. Without considering the wire plastic deformation, the calculation results of wire stress in overload condition will be conservative. So this paper established the state equation of stress changes based on wire strain curves when the wire is ice overloaded and the produced stress exceeds the limit. Considering the wire strain curves, a new calculating method of the stress was introduced when the wire's stress beyond the tensile strength. Simulation result shows that the method is valid.

A bispectral cloud classification method based on man-computer interactive way, i.e. a unit feature space classification method (UFSCM), has been presented in this paper. Apart from land and water, six types of clouds including cumulonimbus, multilayer cloud system, thin / think cirrus, middle and low level clouds are recognized. The method has been tested by using more than two hundred samples, with total accuracy reaching 87.1 %.

This paper designed a controlling model based on internet technology connecting to grid according to the characteristic that biogas power generator connecting to grid system needs a relatively high response speed and accuracy when processing real-time data. By connecting with the processing characteristics of biogas power generator connecting to grid, the model designed an internet network with a three-tier network structure. There are special tasks for each one. In accordance with each task contents, the model applies to corresponding network technology. Besides, it can meet the system demands and make use of the following four kinds of typical technologies effectively: distributed sensor technology, real-time data transmission technology, communication technology and information identification technology.

The effect of thickness on transformation temperature of the NiTi thin films has been studied by X-ray diffraction and X-ray photoelectron spectroscopy. Results show that the crystallization temperature for 3?μm-thick film is higher than that for 18?μm thick film at the same growth temperature and post annealing. With the substrate temperature increasing, the start temperature （As） of austenite phase is lowered after annealing at 763 K for 1?h. There is an oxide layer （TiO2） on the film surface, which prevents the Ni atom from coming onto the surface. There is an oxide layer of a mixture Ti2O3 with NiO on the film /substrate interface. The oxide layers affect the transformation temperature by changing the Ni atomic content in the interior of the film.

A first principles plane-wave method is utilized to investigate the bulk properties of the NiTi alloy，such as the lattice parameters, formation energy and cohesive energy and the elastic constant. The results are in good agreement with experimental and other theoretical results.Furthermore,we have studied the geometric and electronic structures of NiTi (100) and(110)surfaces. As to the surface geometry, there are different relaxations in the surface layers. As for the cleaned NiTi(110) surface, outermost surface layer shows a large rippled relaxation in which Ni atoms contract into the bulk by 0.198? and Ti atoms expand to the vacuum by 0.122?. The calculation of the surface electronic structure shows that Ti-terminated surface is more reactive than Ni-terminated surface on (100) surface and the NiTi (110) surface is inert.

The material composed of a definite amount of nanocrystalline phase α-Fe(Si) with a double-phase structure was produced by laser irradiation on the amorphous Fe 735 Cu 1 Nb 3 Si 135 B 9 alloy with a laser power ranging from 50 to 300W, scanning speed 20mm/s, laser beam spot 20mm. Hyperfine structures of the nanocrystallized samples were analyzed by Mssbauer spectra. Experimental result shows that after the CO 2 laser irradiated on the amorphous allo y Fe 735 Cu 1 Nb 3 Si 135 B 9 , its hyperfine magnetic field dist ribution transformed from a single peak to double peaks with the change of laser power. When irradiated at a high laser power, it formed a double-peak structure and the peaks moved to a high field position. Nanocrystallization of amorphous Fe 7 35 Cu 1 Nb 3 Si 135 B 9 ir radiated by a higher laser power produces fou r hyperfine structures, i.e. two primary crystal phases with relatively small hy perfine magnetic field and two nanocrystalline phases with a relatively large hy perfine magnetic field. The major crystal phase is the α-Fe(Si) phase of DO 3 whose hyperfine magnetic field is comparatively larger (17—25MA/m).

Microcrystalline phases were produced by laser irradiation on the Fe73.5Cu1Nb3Si13.5B9 amorphous ribbon with a power ranging from 40 to 170W,scaning speed 10mm/s,laser beam spot 20mm. Hyperfine structures of the original and crystallized samples were analyzed by transmission Mssbauer spectros copy. We discovered that the basic parameters of the Mssbauer spectra——isome r shift（IS）, quadrupole splitting（QS） and hyperfine magnetic field（Hhf） ch ange with the laser power. Experimental results show that the magnetic moment re organization of Fe73.5Cu1Nb3Si13.5 B9 amorphous phases has take n place and the atom magnetic moment direction maintains a preferred in-plane or ientation, The average hyperfine magnetic field of the amorphous phase is improv ed because of the microcrystalline phase. The crystallized phase was Fe-Si alloy with a DO3 structure, and the area of its spectral lines is about 2% —3.4%. This is caused by the jump of one electron in Fe atom 3d6 shell int o Si atom 3p2 shell, forming a stability electron group.

Xanthen-9-one 8 was converted into 9-(4-methoxyphenyl)-, 9-(4-methylphenyl)- and 9-[3(trifluoromethyl)phenyl]-xanthen-9-ol (10; R1= OMe, R2= H, 10; R1= Me, R2= H, and 10; R1= H, R2= CF3, respectively). The corresponding 5′-protected thymidine derivatives (13; R1= OMe, R2= H, 13; R1= Me, R2= H and 13; R1= H, R2= CF3) were obtained in satisfactory yields from thymidine 12 and the appropriate 9-chloro compounds (11; R1= OMe, R2= H, 11; R1= Me, R2= H and 11; R1= H, R2= CF3). In the same way, 2,7-dibromoxanthen-9-one 14 was converted into two 9-aryl-2,7-dibromoxanthen-9-ols (compounds 15a and 15b). Reaction between thymidine 12 and the corresponding 9-chlorocompounds gave the 5′-protected thymidine derivatives 16a and 16b, also in satisfactory yields. The rates of acid-catalysed cleavage of the above five 5′-protected thymidine derivatives (13; R1= OMe, R2= H, 13; R1= Me, R2= H and 13; R1= H, R2= CF3), 16a and 16b were compared with those of 5′-O-(9-phenylxanthen-9-yl)thymidine 13; R1= R2= H and 5′-O-(triphenylmethyl)thymidine 3a; B = thymin-1-yl under the same conditions.

A new method for measuring the density, temperature and velocity of N2 gas flow by laser induced biacetyl phosphorescence is proposed. The characteristics of the laser induced phosphorescence of biacetyl mixed with N2 are investigated both in static gas and in one-dimensional flow along a pipe with constant cross section. The theoretical and experimental investigations show that the temperature and density of N2 gas flow could be measured by observing the phosphorescence lifetime and initial intensity of biacetyl triplet (3Au) respectively. The velocity could be measured by observing the time-of-flight of the phosphorescent gas after pulsed laser excitation. The prospect of this method is also discussed.

Experimental results of laser induced phosphorescence of biacetyl triplet3Au in a mixture of biacetyl and N2 show that: the lifetime of phosphorescence is a function of temperature and independent of density and concentration; the initial phosphorescence intensity is a linear function of density and insensitive to the variation of temperature. The temperature and density distribution of gas flow could be measured by observing the phosphorescence lifetime and initial intensity of biacetyl mixed with N2 respectively. The velocity distribution could be measured by observing the time-of-flight of the gaseous phosphorescent spot under pulsed laser excitation. Compared with Doppler anemometer, it, to a great extent, avoids the particle lag problem in flow field with large velocity gradient. The phosphorescence decay mechanism is also analysed and the analytical results agree with experimental ones.

An infrared broadband angle-scanning method for remote sensing of the temperature profile in the boundary layer at ground is suggested. Numerical analysis shows that it gives acceptable retrieval when using a set of well-chosen zenith angles. Retrieval error can be minimized by using the average measurements which are taken in a very short time. The retrieving during inversion and correction of water vapour absorption is discussed.

NOAA-9 AVHRR data on May 24, 1985 were used in the paper. Two regions, each about 4°×4° longitude by latitude, centered on 39.4°N, 113.0°E and 44.6°N, 112.0°E are selected for analysis. Two-dimensional histogram and dynamic clustering are made for these two regions. The cloud top temperature, emissivity and optical depth of those clusters are retrieved. Synoptic map at the same time are shown for comparison.