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A simple and specific quantitative analysis method has been developed and validated for the determination of Argatroban Intermediate and its related substance. This method uses reversed-phase high performance liquid chromatography (RP-HPLC) to analyze the Argatroban Intermediate and its six related substance. Chromatographic conditions for RP-HPLC with UV detector were as follows: column, Agela Venusil MP, 250mm×4.6mm, 5μm; column temperature, 45°C; mobile phase, a 65: 35 (v/v) mixture of ammonium acetate buffer: methanol; flow rate, 1.0 mL/min. The detection wavelength was UV 272 nm. Under these conditions, excellent linearity was obtained (r2>0.9995) in the concentration range of 0.47~4.71μg/ml for Argatroban Intermediate, 0.30~5.04μg/ ml for impurity A, 0.12~4.93μg/ml for impurity B, 0.29~4.81μg/ ml for impurity C, 0.30~4.96μg/ml for impurity D,0.12~4.77μg/ ml for impurity E and 0.12~4.86μg/ml for impurity F, respectively. The LOQ was 0.5μg/ml for Argatroban Intermediate, 0.3μg/ml for impurity A, 0.125μg/ml for impurity B, 0.3μg/ml for impurity C,0.3μg/ml for impurity D, 0.125μg/ml for impurity E and 0.125μg/ ml for impurity F. The maximum R.S.D.(%) of the content of Argatroban Intermediate and its each impurity was 5.3% under the deliberate variations in method parameters.

In this study, the problem of guiding a small fixed-wing unmanned aerial vehicle (UAV) toward a predefined horizontal path is studied. A stable nonlinear guidance law, which is a function of the inertial positions and velocities of the UAV and the predefined path, is designed using Lyapunov stability arguments. The concept of the nonlinear model predictive control (NMPC) technique was applied to optimize a key parameter of the guidance law to improve the performance of the controller (PFC_NMPC), where the stability of the relative nonlinear system is maintained. The proposed method was verified in the MATLAB/Simulink environment to realize following the straight-line, square and circular paths. The path- following performance of the proposed method is compared with those of the guidance laws with parameter fixed (PFC) or tuned by fuzzy logic (PFC_FL). With the predictive ability, the proposed method can make the UAV fly more on the desired square and circular paths than the other two methods, PFC and PFC_FL. The error overshoot by using PFC_NMPC is much smaller than those by using the PFC and PFC_FL methods in the presence of wind at 8m/s.

A distributed multi-missile cooperative guidance law based on the finite time theory is proposed to solve the terminal guidance problem of three-dimensional multi-missiles cooperative interception of large maneuvering target. According to the finite time consistency theory, an adaptive guidance law based on the integral sliding mode is designed to ensure that all missiles can reach the target at the same time in the terminal guidance process. The longitudinal and lateral acceleration of the line of sight are based on the guidance law of the fast terminal sliding mode surface. The terminal attack angle is constrained, so that the terminal attack Angle can reach the expected value in finite time. The simulation results show that the designed guidance law can achieve the cooperative attack on the maneuvering targets.

Neuroinflammation is one of the most significant factors involved in the initiation and progression of Parkinson’s disease. PD is a neurodegenerative disorder with a motor disability linked with various complex and diversified risk factors. These factors trigger myriads of cellular and molecular processes, such as misfolding defective proteins, oxidative stress, mitochondrial dysfunction, and neurotoxic substances that induce selective neurodegeneration of dopamine neurons. This neuronal damage activates the neuronal immune system, including glial cells and inflammatory cytokines, to trigger neuroinflammation. The transition of acute to chronic neuroinflammation enhances the susceptibility of inflammation-induced dopaminergic neuron damage, forming a vicious cycle and prompting an individual to PD development. Epigenetic mechanisms recently have been at the forefront of the regulation of neuroinflammatory factors in PD, proposing a new dawn for breaking this vicious cycle. This review examined the core epigenetic mechanisms involved in the activation and phenotypic transformation of glial cells mediated neuroinflammation in PD. We found that epigenetic mechanisms do not work independently, despite being coordinated with each other to activate neuroinflammatory pathways. In this regard, we attempted to find the synergic correlation and contribution of these epigenetic modifications with various neuroinflammatory pathways to broaden the canvas of underlying pathological mechanisms involved in PD development. Moreover, this study highlighted the dual characteristics (neuroprotective/neurotoxic) of these epigenetic marks, which may counteract PD pathogenesis and make them potential candidates for devising future PD diagnosis and treatment.

Cardiovascular diseases are increasingly threating the global human health, hypertension is the most important risk factor for cardiovascular and cerebrovascular diseases. To improve the antihypertensive activity and cardiovascular protective effect of natural product (±)-7,8-dihydroxy-3-methyl-isochroman-4-one [(±)-XJP], a series of novel H

The aeroelastic response to time-dependent gusts or turbulence should be considered in airplane design. A robust generalized predictive control law for gust response alleviation is designed and simulated on an aircraft model by using the real wind tunnel response and approximated gust input. Based on the open-loop response of an aircraft model at different test conditions, a nominal Auto Regressive (AR) model with parameter uncertainty is identified. Singular Value Decomposition is designed to reduce the dimension of the uncertainty matrix. Afterwards, with the identified online aeroelastic model and its uncertainty, a robust generalized predictive control (GPC) is applied to alleviate the wing tip acceleration at all test conditions, including varying flow velocities and varying gust frequencies. Finally, the alleviation effect of gust response at different test conditions is estimated based on the comparison of simulated closed-loop acceleration with an experimental open-loop one. The comparison indicates that after robust gust response alleviation control, the wing tip acceleration response can be reduced by up to 70% under all test conditions. Remarkably, the control law is robust to the parameter uncertainties and input uncertainties, which is applicable to the gust alleviation wind tunnel test.

7,8 Dihydroxy 3 methyl isochromanone 4 XJP is a polyphenolic natural product with moderate antihypertensive activity. T o obtain new agents with stronger potency and safer profile , we employed XJP and naftopidil as the lead compound s t o design and synth esize a novel class of hybrids as antihypertensive candidates, In the present study, a series of hybrids ( 6a r ) of XJP bearing arylpiperazine moiety, which is identified as the pharmacophore of naftopidil, were designed and synthesized as novel ? 1 adrenergic receptor antagonists. The biological evaluation showed that target compounds 6c , 6e , 6f , 6g , 6h , 6m and 6q possessed potent in vitro vasodilation potency and ? 1 adrenergic receptor antagonistic activity . Furthermore, the most potent compound 6e significantly reduced the systolic and diastolic blood pressure in spontaneously hypertensive rats (SHRs),which was comparable to that of naftopidil, and it had no observable effects on the basal heart rate, suggesting that 6e deserves to be further investigated as a potential clinical candidate for the treatment of hypertension.

Based on WorldView-2 remote sensing images and other survey materials, we analysis the spatio-temporal characteristics of land cover change in Liangjiang New District during 2010 to 2018. The results are summarized as follows: 1) Land cover pattern changed dramatically, with the built-up increase, while the crop land, forest and grass land decrease. 2) Change in land cover types showed marked fluctuations over the three stages (2010-2012, 2012-2015, 2015-2018). Districts with the most obvious change of CL and FGS concentrated in the East and north of the Liangjiang New District. 3) There were significant differences in the intensity of land use dynamic degree change among different regions. The relative change land use dynamic degree of Lijia Street is the biggest, followed by Yuelai Street, Fusheng Town and Longxing Town.

A series of novel 4-isochromanone hybrids bearing N-benzyl pyridinium moiety as dual binding site acetylcholinesterase inhibitors have been designed and synthesized. The screening results showed that most of the compounds exhibited potent anti-AChE activity in the range of nM concentrations. The 1-(4-fluorobenzyl) substituted derivative 9d exhibited the most potent anti-AChE activity with IC50 value of 8.9 nM and high AChE/BuChE selectivity (SI>230). Kinetic and molecular modeling studies suggested that compound 9d was mixed-type inhibitor, binding simultaneously to CAS and PAS of AChE. Besides, the preliminary structure-activity relationships were discussed.

The synthesis of 4-isochromanones via Parham-type cyclization with Weinreb amide as the internal electrophilic group, t-BuLi as the lithium reagent was described. The reaction was efficient and could be completed in one minute. The application scope of this new protocol was investigated and the desired products could be obtained in good to excellent yields. Besides, the synthetic potential of this method was further demonstrated by the synthesis of natural product (±)-XJP, which was obtained in six steps with overall yield up to 54%.

Three-axis spacecraft simulators are widely used to verify spacecraft control strategies. Designing a simulator whose moment of inertia are similar to the spacecraft's is important for control research. Moreover, to reduce the disturbance of gravity torque, the centre of mass of the simulator attitude stage must be exactly aligned with the centre of rotation. Various sensors and actuators are on the simulator. An optimisation method for the locations of these devices on the simulator is presented. In this method, these devices are described as rectangles and circles. Their spatial relationship are expressed by a series of inequalities. The total inertia parameters of these devices are optimised.

Path following is a fundamental problem for unmanned air vehicles (UAVs). In this paper, a Lyapunov stable path guidance law is designed to generate the course control command for a small UAV. The control parameters of the guidance law is optimized by the nonlinear model predictive control (NMPC) techinque. The relative simulations with the three different approaches: Lyapunov stable controller with parameters optimizated (LC_NMPC), the normal NMPC and the Lyapunov stable controller with constant parameters (LC) are compared with each other. The simulation results show that the LC_NMPC can reach good path following performance with shorter rise time and zero steady error.

To ensure the effectiveness of the RF(Radio Frequency) guided HILS(Hardware-In-the-Loop Simulation) system, the credibility evaluation was necessary. At present, most of the methods were applied in the case of the simulation system input being consistent with the real system input, which is difficult to achieve in some subsystem of the RF guided HILS system. In this paper, the relative complete system reliability evaluation index system was established. Subsystems were classified, for different categories of subsystem, corresponding reliability assessment methods were studied. In particular, reliability evaluation methods based on performance level were put forward, when certain subsystems cannot be evaluated by consistency analysis methods. A simple example was given to show the evaluation process.

Purpose – The purpose of this paper is to present a Rao–Blackwellized particle filter (RBPF) approach for the visual simultaneous localization and mapping (SLAM) of small unmanned aerial vehicles (UAVs). Design/methodology/approach – Measurements from inertial measurement unit, barometric altimeter and monocular camera are fused to estimate the state of the vehicle while building a feature map. In this SLAM framework, an extra factorization method is proposed to partition the vehicle model into subspaces as the internal and external states. The internal state is estimated by an extended Kalman filter (EKF). A particle filter is employed for the external state estimation and parallel EKFs are for the map management. Findings – Simulation results indicate that the proposed approach is more stable and accurate than other existing marginalized particle filter-based SLAM algorithms. Experiments are also carried out to verify the effectiveness of this SLAM method by comparing with a referential global positioning system/inertial navigation system. Originality/value – The main contribution of this paper is the theoretical derivation and experimental application of the Rao–Blackwellized visual SLAM algorithm with vehicle model partition for small UAVs.

New metal-free organic sensitizers containing a fluorene unit as a π-conjugated system, a diphenylamine as an electron donor, and a cyanoacrylic acid moiety as an electron acceptor were synthesized and used for dye-sensitized solar cells. The photophysical and electrochemical properties of these dyes were investigated, and their performances as sensitizers in solar cells were measured. One solar cell containing the n -hexyl group in the fluorene unit produced an η of 5.15% ( J sc = 9.69 mA cm −2 , V oc = 0.77 V, and ff = 0.70) under 100 mW cm −2 simulated AM 1.5 G solar irradiation (100 mW cm −2 ).

Five kinds of triphenylamine-based organic dyes with different electron acceptors were designed and synthesized as sensitizers for dye-sensitized solar cells (DSSCs). The photophysical and electrochemical properties of these dyes were investigated and their performance as sensitizers in DSSCs was measured. The dye with cyanoacrylic acid electron acceptor exhibits the highest solar-to-electrical energy conversion efficiency of 4.93% (short-circuit photocurrent density J sc = 8.59 mA cm −2 , open-circuit photovoltage V oc = 0.77 V, and fill factor ff = 0.75) under 100 mW cm −2 -simulated AM 1.5 G solar irradiation.

New metal-free organic sensitizers containing a benzo[d]thiazole or phenyl unit as the π-conjugated system, a triphenylamine as an electron donor, and a cyanoacrylic acid moiety as an electron acceptor were synthesized and used for dye-sensitized solar cells. Photophysical and electrochemical properties of these dyes were investigated, and their performances as sensitizers in solar cells were measured. The introduction of a benzo[d]thiazole unit into the molecular structure resulted in a high incident photon-to-current conversion efficiency (more than 70%) from 340 nm to 600 nm. One solar cell containing a benzo[d]thiazole unit, produced a η of 5.85% (JSC = 10.63 mA cm−2, VOC = 0.72 V, and ff = 0.77) under 100 mW cm−2 simulated AM 1.5 G solar irradiation.

Novel polymer gel electrolytes (PGEs) with high ionic conductivity based on polyvinyl (acetate-co-methyl methacrylate) [P(VA-co-MMA)] were prepared by soaking porous copolymers in an organic electrolyte solution [acetonitrile (ACN) or 3-Methoxypropionitrile (MPN)] that contained an I 3 − /I − as redox couple. Quasi-solid-state dye-sensitized solar cells (QS-DSSCs) were fabricated with the PGEs, and the best PGE was selected and optimized. Using the best PGE and under 100 mW cm −2 light illumination (AM1.5), the QS-DSSC achieved a high photovoltaic conversion efficiency of 9.10%, nearly the same as that for the DSSC based on the original liquid electrolyte. Introduction of TiO 2 nanoparticles into the PGEs further enhanced PGEs ionic conductivity and the conversion efficiency to 9.40%. Subsequent results revealed that our QS-DSSC had a better stability because it could maintain 96.7% of its initial efficiency after long-time (1000 h) exposure to simulative sunlight. Besides, for the first time, large-area QS-DSSCs were fabricated by screen printing of PGE, other than the traditional vacuum injection that was infeasible for the viscous gel electrolyte. Finally, our 5 cm × 7 cm QS-DSSC sub-module exhibited a conversion efficiency higher than 4%.

This paper proposes a nonlinear controller that allows the unmanned air vehicle (UAV) to follow a predefined path. The controller only needs the information of the inertial speed of the UAV and the distance between the vehicle and the desired path. In order to improve the performance of the controller, a parameter of the controller is optimized by using the concept of model predictive control (MPC). Lyapunov stability arguments are used to demonstrate that the path following error will be regulated to zero, even in the presence of wind disturbances. Simulation results in Matlab are given to show the effectiveness of the controller. The simulation results show that the proposed path following controller with parameter optimized by MPC (PLC_MPC) which takes the advantages of the predictive ability of the MPC and the simple structure of the normal path following controller (PLC) has better path following performance than that by using the PLC method.

The highly soluble polyvinyl acetate (PVAc) was synthesized by simple solution polymerization, which was used to prepare the gel-state dye-sensitized solar cells (DSCs) for the first time. The values for open-circuit photovoltage (Voc), short-circuit photocurrent density (Jsc), and fill factor (FF) of gel electrolyte-based DSCs were 0.712 V, 16.78 mA cm–2, and 68%, respectively, yielding an overall photovoltaic conversion efficiency (PCE) of 8.18%, which is comparable to a liquid electrolyte-based one with a value of 8.27%. The results of the electrochemical impedance spectra (EIS) revealed that the large charge transfer resistances at the TiO2/dye/electrolyte interface and the large diffusion resistances of the redox couple in the electrolyte are responsible for similar PCEs of gel and liquid electrolytes. The long-term stability test revealed that the PCE of the gel electrolyte-based DSC did not decay after 1000 h under AM1.5 simulated solar illumination at 60 °C and 40–50% humidity, which is superior t...

In this study, a composite fight control method for the path following of a small unmanned helicopter is proposed. The control system design adopts the hierarchical control architecture that is composed of an inner-loop, an outer-loop and a planning layer. The inner-loop controller design is based on the setpoint tracking linear quadratic Gaussian control technique which can not only stabilise the dynamics of the helicopter, but also track the reference control signals provided by the outer-loop controller well. The core part of the outer-loop controller design is based on the notion of vector field, which is used for generating the desired heading rate command. Lyapunov stability arguments are applied to demonstrate the asymptotic approximation to the desired path in the presence of wind disturbance. Experimental results are presented to verify the validity of the method.

In this paper, analytical techniques and fuzzy logic method are applied to the dynamic modeling and efficient swimming control of a robotic fish. The bioinspired robotic fish, which follows an exact replica of a live mackerel (Scomber scombrus), is modeled by treating the undulating body and flapping tail independently using analytical methods. Comparing the results of simulations and experiments shows the feasibility of the dynamic model. Using this model, we found that the harmonic control of the Strouhal number and caudal fin angle of attack is a principal mechanism through which the robotic fish can obtain high thrust efficiency while swimming. The fuzzy control method, which is based on the knowledge of the robotic fish's dynamic behavior, has successfully utilized this principal mechanism. By comparing the thrust performance of the robotic fish with different control methods via simulation, we established that the fuzzy controller was able to achieve faster acceleration and smaller steady-state error than what could be achieved from an open-loop and conventional proportional-integral-derivative controller. The thrust efficiency during steady state was superior to that with conventional control methods. We also found that, when using the fuzzy control method, robotic fish can always swim near a “universal” Strouhal number that approximates to the swimming of live fish.

The enantioselective formal synthesis of (+)-englerin A and the total synthesis of (-)-orientalol F were successfully accomplished via a triene. The success enabled establishment of the relative as well as absolute stereochemistry of the organocatalytic [4+3]-cycloaddition reaction.

A concise enantioselective synthesis of diversely functionalized advanced intermediates comprising the tricyclic skeleton of englerin A and related oxygen-bridged guaianes has been successfully accomplished, which features a Harmata organocatalytic [4+3] cycloaddition reaction. (C) 2010 Elsevier Ltd. All rights reserved.

The synthesis of 4-isochromanones via Parham-type cyclization with Weinreb amide as the internal electrophilic group, t-BuLi as the lithium reagent was described. The reaction was efficient and could be completed in one minute. The application scope of this new protocol was investigated and the desired products could be obtained in good to excellent yields. Besides, the synthetic potential of this method was further demonstrated by the synthesis of natural product (±)-XJP, which was obtained in six steps with overall yield up to 54%.

This paper has presented an implementation of visual based non-GNSS navigation method for small VTOL (Vertically Taking-off and Landing) UAV (Unmanned Aerial Vehicle). A novel method of constructing landmarks is described in detail. It uses a pair of landmarks instead of the general landmark which usually is a single geometry or coding image. The paired-landmark method inherits general landmark methods' advantages of low-cost, high-efficiency and the ability of absolute positioning. And it also solves the problem of requiring too much different characteristic landmarks when handling large area navigation. The paired-landmark method has been verified by a real parameter simulation environment. Real flight experiment is also carried out to test the effectiveness and performance of the paired-landmark navigation method. It can be concluded that, besides achieved the expected positioning precision, the proposed system also reduced the consumption of calculation and memory space.

The first asymmetric total synthesis of antihypertensive natural products S-(+)-XJP and R-(−)-XJP has been achieved in 8 steps starting from commercially available 6-bromo-2-hydroxy-3-methoxybenzaldehyde. Key steps included intramolecular Heck reaction and oxidative ozonolysis reaction with the retention of stereochemistry. A latent functionality strategy was implemented to circumvent the racemization in this endeavor. The protocol described here provided a fast and easily accessible synthetic method to obtain optically pure isochroman-4-one derivatives. Furthermore, the in vivo antihypertensive effects of (±)-XJP, S-(+)-XJP and R-(−)-XJP were investigated on spontaneously hypertensive rats. The obtained results could provide valuable information to identify a promising lead for further chemical modification research.