Search

Xiao-Dong Li,1–3 Zheng Wang,1,2 Xin-Rui Wang,4 Dan Shao,1 Xi Zhang,5 Li Li,1 Ming-Feng Ge,1 Zhi-Min Chang,1 Wen-Fei Dong11CAS Key Laboratory of Bio-Medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou 215163, People’s Republic of China; 2University of Chinese Academy of Sciences, Beijing 100049, People’s Republic of China; 3Department of Echocardiography, The First Hospital of Jilin University, Changchun 130021, People’s Republic of China; 4Department of Hepatology, The First Hospital of Jilin University, Changchun 130021, People’s Republic of China; 5Department of Rheumatology, Third Affiliated Hospital of Sun Yat-sen University, Guangzhou 510630, People’s Republic of ChinaBackground: The combination of chemotherapy with radiotherapy serves as a common therapeutic strategy in clinics. However, it is unsatisfactory due to its poor therapeutic efficiency and severe side-effects originating from chemotherapy-exerted systemic toxicity as well as radiation-induced injury.Purpose: Hence, Berberine (Ber), an isoquinolin alkaloid with low toxicity and protective effects against radiotherapy, was used as a novel chemotherapeutic agent for chemo-radiotherapy of liver cancer.Patients and methods: We preloaded Ber into folic acid targeting Janus gold mesoporous silica nanocarriers (FA-JGMSNs) for overcoming the poor bioavailability of Ber. Furthermore, FA-JGMSNs were not only employed as radiosensitizers for expanding radiotherapeutic effect, but also used as photothermal agents for supplementing chemo-radiotherapeutic effect by local photothermal therapy.Results: In vitro and in vivo experiemtal results demonstrated the highly efficient anti-tumor effect, good biosafety as well as the effective protection of normal tissue of this nanoplatform.Conclusion: Based on its superb performance, we believe our work provided a feasible strategy for triple-therapies of liver cancer.Keywords: Berberine, chemotherapy, radio-sensitization, Au MSNs, Janus, photothermal therapy

This paper investigates the fixed-time cluster formation tracking (CFT) problem for networked perturbed robotic systems (NPRSs) under directed graph information interaction, considering parametric uncertainties, external perturbations, and actuator input deadzone. To address this complex problem, a novel hierarchical fixed-time neural adaptive control algorithm is proposed based on a hierarchical fixed-time framework and a neural adaptive control strategy. The objective of this study is to achieve accurate CFT of NPRSs within a fixed time. Specifically, we design a distributed observer algorithm to estimate the states of the virtual leader within a fixed time accurately. By using these observers, a neural adaptive fixed-time controller is developed in the local control layer to ensure rapid and reliable system performance. Through the use of the Lyapunov argument, we derive sufficient conditions on the control parameters to guarantee the fixed-time stability of NPRSs. The theoretical results are eventually validated through numerical simulations, demonstrating the effectiveness and robustness of the proposed approach., (© 2024. The Author(s).)

This research delves into the challenges of achieving secure consensus tracking within multi-agent systems characterized by directed hypergraph topologies, in the face of hybrid deception attacks. The hybrid discrete and continuous deception attacks are targeted at the controller communication channels and the hyperedges, respectively. To overcome these threats, an impulsive control mechanism based on hypergraph theory are introduced, and sufficient conditions are established, under which consensus can be maintained in a mean-square bounded sense, supported by rigorous mathematical proofs. Furthermore, the investigation quantifies the relationship between the mean-square bounded consensus of the multi-agent system and the intensity of the deception attacks, delineating a specific range for this error metric. The robustness and effectiveness of the proposed control method are verified through comprehensive simulation experiments, demonstrating its applicability in varied scenarios influenced by these sophisticated attacks. This study underscores the potential of hypergraph-based strategies in enhancing system resilience against complex hybrid attacks., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

This paper investigates the teleoperation problem of networked disturbed mobile manipulators (NDMMs), in which the human operator remotely controls multiple slave mobile manipulators through a master manipulator. Each individual of the slave ones consisted of a nonholonomic mobile platform and a holonomic constrained manipulator that is mounted on the nonholonomic mobile platform. The cooperative control objective of the considered teleoperation problem includes: (1) synchronizing the states of the slave manipulators to the human-controlled master one; (2) forcing the mobile platforms of the slave ones to form a user-defined formation; (3) controlling the geometric center of all the platforms to track a reference trajectory. We present a hierarchical finite-time cooperative control (HFTCC) framework to achieve the cooperative control goal in a finite time. The presented framework includes the distributed estimator, the weight regulator and the adaptive local controller, where the estimator generates the estimated states of the desired formation and trajectory, the regulator selects the slave robot that the master one needs to track, as well as the presented adaptive local controller guarantees the finite-time convergence of the controlled states with model uncertainties and disturbances. Additionally, for improving the telepresence, a novel super twisting observer is presented to reconstruct the interaction force between the salve mobile manipulators and the remote operating environment on the master (i.e., the human) side. Finally, the effectiveness of the proposed control framework is demonstrated by several simulation results., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 ISA. Published by Elsevier Ltd. All rights reserved.)

In this paper, a flexible shape generator (FSG) is designed to achieve the divinable transformation process of the time-varying formation, and consider the FSG-based time-varying formation tracking (TVFT) problem of multiple Lagrangian agents with unknown disturbances and directed graphs. A hierarchical control algorithm is newly designed to achieve the control goal without using the prior information of the system model and bounded disturbances, and the specific implementation of the proposed hierarchical algorithms is also provided. By using the Hurwitz criterion and adaptive system theory, the sufficient conditions are derived and the stability analysis show that the formation tracking errors of the considered system are uniform ultimate bounded. Several simulation examples are performed on five two-degree-of-freedom mechanical arms to show the effectiveness of theoretical results., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 ISA. Published by Elsevier Ltd. All rights reserved.)

This article studies the lag-bipartite formation tracking (LBFT) problem of the networked robotic systems (NRSs) with directed matrix-weighted signed graphs. Unlike the traditional formation tracking problems with only cooperative interactions, solving the LBFT problem implies that: 1) the robots of the NRS are divided into two complementary subgroups according to the signed graph, describing the coexistence of cooperative and antagonistic interactions; 2) the states of each subgroup form a desired geometric pattern asymptotically in the local coordinate; and 3) the geometric center of each subgroup is forced to track the same leader trajectory with different plus-minus signs and a time lag. A new hierarchical control algorithm is designed to address this challenging problem. Based on the Lyapunov stability argument and the property of the matrix-weighted Laplacian, some sufficient criteria are derived for solving the LBFT problem. Finally, simulation examples are proposed to validate the effectiveness of the main results.

In this article, the consensus of networked underactuated robotic systems subject to fixed and switched communication networks is discussed by developing some novel event-triggered control algorithms, which can synchronously guarantee the convergence of the active states, the boundedness of the velocities of passive actuators, and the exclusion of Zeno behaviors. In the cases of fixed networks, the sufficient criteria are established for the presented distributed event-triggered mechanisms with and without using neighbors' velocities, in order to achieve a better tradeoff between the communication load and system performance. Besides, in the situation of switched networks, the sufficient criterion is established by assuming that the union of the network has a spanning tree. A distributed sampled-data rule is constructed to decide when to update its own and neighbors' estimated positions, and thus further reduces the unnecessary control cost. Finally, by further extending the main results to three other sampled-data control algorithms, several examples with performance comparisons are provided to validate the efficiency and advantages of the theoretical results.

This paper presents a design of a 3DOF XYZ bi-directional motion platform based on Z-shaped flexure hinges. In the presented platform, bridge-type mechanisms and Z-shaped flexure hinges are adopted to amplify its output displacement. Bi-direction motion along the X-axis and Y-axis follows the famous differential moving principle DMP, and the bi-directional motion along the Z-axis is realized by using the reverse arrangement of the Z-shaped flexure hinges along the X-axis and Y-axis. Statics analysis of the proposed platform is carried out by the energy method, compliance matrix method, and force balance principle. Meanwhile, the Lagrange method is used to analyze the dynamics of the platform. A series of simulations are conducted to demonstrate the effectiveness of the proposed design. The simulation results show that the average displacements of the platform in the XYZ-axis are ±125.58 μm, ±126.37 μm and ±568.45 μm, respectively.

This paper investigates the quasi-synchronization problem of the stochastic heterogeneous complex dynamical networks with impulsive couplings and multiple time-varying delays. It is shown that this kind of dynamical networks can achieve exponential quasi-synchronization by exerting impulsive control added on only one chosen pinning node. By employing the Lyapunov stability theory, some sufficient criteria on quasi-synchronization for this dynamical network are established, revealing the relationship between the quasi-synchronization performance and the stochastic perturbations as well as the frequency and strength of impulsive coupling. Finally, some numerical examples are used to illustrate the effectiveness of the main results., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

This article investigates the finite-time output multiformation tracking (OMFT) problem of networked heterogeneous robotic systems (NHRSs), where each robot model involves external disturbances, parametric uncertainties, and possible kinematic redundancy. Besides, the interactions among robotic systems are described as a directed graph with an acyclic partition. Then, several novel practical finite-time hierarchical control (FTHC) algorithms are designed. The convergence analysis of the closed-loop dynamics is extremely difficult due to the lack of effective analysis methods. Based on the mathematics induction and reductio ad absurdum, a new nonsmooth Lyapunov function is proposed to derive the sufficient conditions and settling time functions. Finally, numerical simulations are performed on the NHRS to verify the main results.

This article addresses two kinds of formation tracking problems, namely: 1) the practical formation tracking (PFT) problem and 2) the zero-error formation tracking (ZEFT) problem for multiple Euler-Lagrange systems with input disturbances and unknown models. In these problems, the bounded input constraint, which can be possibly caused by actuator saturation and power limitations, is taken into consideration. Then, the two classes of model-independent distributed control approaches, in which the prior information (i.e., the structures and features) of the system model is not used, are proposed correspondingly. Based on the nonsmooth analysis and Lyapunov stability theory, several novel criteria for achieving PFT and ZEFT of multiple Euler-Lagrange systems are derived. Finally, numerical simulations and comparisons are presented to verify the validity and effectiveness of the proposed control approaches.

This paper investigates the second-order bipartite consensus (BC) problems for networked robotic systems (NRSs) subject to model uncertainties and external disturbances over signed directed graphs. We have newly presented two classes of hierarchical control algorithms (HCAs) to solve the BC problems for NRSs in a more practical and challenging case of quantized-data interactions (QDIs) and time-varying transmission delays (TVTDs). By using Hurwitz criterion and Lyapunov stability argument, several sufficient conditions on control parameters are obtained and the BC performance of the regulated system is analyzed. Three examples validate the presented theoretical findings., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 ISA. Published by Elsevier Ltd. All rights reserved.)

Recently, the design of metamaterial guided by transformation optics (TO) has emerged as an effective method to hide objects from optical detection, based on arranging a bended light beam to detour. However, this TO-based solution involves fabrication of material with complicated distribution of permittivity and permeability, and the device falls short of tunability after fabrication. In this work, we propose an optofluidic model employing the method of streamline tracing-based transformation optofluidics (STTOF) to hydrodynamically reconfigure light propagation in a given flow field for object-cloaking purposes. The proof-of-concept is demonstrated and tested on an optofluidic chip to validate our proposed theory. Experimental results show that our proposed STTOF method can be used to successfully detour the light path from the object under cloaking in a mathematically pre-defined manner.

This paper proposes several hierarchical controller-estimator algorithms (HCEAs) to solve the coordination problem of networked Euler-Lagrange systems (NELSs) with sampled-data interactions and switching interaction topologies, where the cases with both discontinuous and continuous signals are successfully addressed in a unified framework. The HCEAs comprise two main layers (i.e., a control layer and an estimator layer) and one optional layer (i.e., a filter layer), in which the coordination problem is tackled in the main layers and the transient response can be optionally smoothed in the filter layer. For stabilizing the corresponding cascade closed-loop systems, several sufficient conditions on the upper bound of the aperiodic sampling intervals and the lower bound of the control parameters are established. In addition, the HCEAs are extended to address the task-space coordination problem of networked heterogeneous robotic systems, which shows the versatility of the HCEAs. Finally, comparison studies and simulation results are provided to demonstrate the effectiveness, significance, and advantages of the presented algorithms.

Hysteresis behaviors are inherent characteristics of piezoelectric ceramic actuators. The classical Duhem model (CDM) as a popular hysteresis model has been widely used, but cannot precisely describe rate-dependent hysteresis behaviors at high-frequency and high-amplitude excitations. To describe such behaviors more precisely, this paper presents a modified Duhem model (MDM) by introducing trigonometric functions based on the analysis of the existing experimental data. The MDM parameters are also identified by using the nonlinear least squares method. Six groups of experiments with different frequencies or amplitudes are conducted to evaluate the MDM performance. The research results demonstrate that the MDM can more precisely characterize the rate-dependent hysteresis behaviors comparing with the CDM at high-frequency and high-amplitude excitations., Competing Interests: The authors declare no conflict of interest.

Radiation dosage constraints and hypoxia-associated resistance lead to the failure of radiotherapy (RT), especially in hypoxic liver cancer. Therefore, the intricate use of combined strategies for potentiating and complementing RT is especially important. In this work, we fabricated multifunctional Janus-structured gold triangle-mesoporous silica nanoparticles (NPs) as multifunctional platforms to deliver the hypoxia-activated prodrug tirapazamine (TPZ) for extrinsic radiosensitization, local photothermal therapy, and hypoxia-specific chemotherapy. The subsequent conjugation of folic acid-linked poly(ethylene glycol) provided the Janus nanoplatforms with liver cancer targeting and minimized opsonization properties. In vitro and in vivo experiments revealed the combined radiosensitive and photothermal antitumor effects of the Janus nanoplatforms. Importantly, the TPZ-loaded Janus nanoplatforms exhibited pH-responsive release behavior, which effectively improved the cellular internalization and therapeutic efficiency in hypoxic rather than normoxic liver cancer cells. Hypoxia-specific chemotherapy supplemented the ineffectiveness of radio-photothermal therapy in hypoxic tumor tissues, resulting in remarkable tumor growth inhibition without systematic toxicity. Therefore, our Janus nanoplatforms integrated radio-chemo-photothermal therapy in a hypoxia-activated manner, providing an efficient and safe strategy for treating liver cancer.

The hydropower generator unit (HGU) is a vital piece of equipment for frequency and peaking modulation in the power grid. Its vibration signal contains a wealth of information and status characteristics. Therefore, it is important to predict the vibration tendency of HGUs using collected real-time data, and achieve predictive maintenance as well. In previous studies, most prediction methods have only focused on enhancing the stability or accuracy. However, it is insufficient to consider only one criterion (stability or accuracy) in vibration tendency prediction. In this paper, an intelligence vibration tendency prediction method is proposed to simultaneously achieve strong stability and high accuracy, where vibration signal preprocessing, feature selection and prediction methods are integrated in a multi-objective optimization framework. Firstly, raw sensor signals are decomposed into several modes by empirical wavelet transform (EWT). Subsequently, the refactored modes can be obtained by the sample entropy-based reconstruction strategy. Then, important input features are selected using the Gram-Schmidt orthogonal (GSO) process. Later, the refactored modes are predicted through kernel extreme learning machine (KELM). Finally, the parameters of GSO and KELM are synchronously optimized by the multi-objective salp swarm algorithm. A case study and analysis of the mixed-flow HGU data in China was conducted, and the results show that the proposed model performs better in terms of predicting stability and accuracy.

This paper deals with the stabilization problem of memristive recurrent neural networks with inertial items, discrete delays, bounded and unbounded distributed delays. First, for inertial memristive recurrent neural networks (IMRNNs) with second-order derivatives of states, an appropriate variable substitution method is invoked to transfer IMRNNs into a first-order differential form. Then, based on nonsmooth analysis theory, several algebraic criteria are established for the global stabilizability of IMRNNs under proposed feedback control, where the cases with both bounded and unbounded distributed delays are successfully addressed. Finally, the theoretical results are illustrated via the numerical simulations., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

This paper investigates the optimal modified tracking performance of multi-input multi-output (MIMO) networked control systems (NCSs) with packet dropouts and bandwidth constraints. Some explicit expressions are obtained by using co-prime factorization and the spectral decomposition technique. The obtained results show that the optimal modified tracking performance is related to the intrinsic properties of a given plant such as non-minimum phase (NMP) zeros, unstable poles, and their directions. Furthermore, the modified factor, packet dropouts probability and bandwidth also impact the optimal modified tracking performance of the NCSs. The optimal modified tracking performance with channel input power constraint is obtained by searching through all stabilizing two-parameter compensator. Finally, some typical examples are given to illustrate the effectiveness of the theoretical results., (Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.)

Atmospheric aerosols are usually complex mixtures of inorganic and organic compounds. The hygroscopicity of mixed particles is closely related to their chemical composition and interactions between components, which is still poorly understood. In this study, the hygroscopic properties of submicron particles composed of NaCl and dicarboxylic acids including oxalic acid (OA), malonic acid (MA), and succinic acid (SA) with various mass ratios are investigated with a hygroscopicity tandem differential mobility analyzer (HTDMA) system. Both the Zdanovskii-Stokes-Robinson (ZSR) method and extended aerosol inorganics model (E-AIM) are applied to predict the water uptake behaviors of sodium chloride/dicarboxylic acid mixtures. For NaCl/OA mixed particles, the measured growth factors were significantly lower than predictions from the model methods, indicating a change in particle composition caused by chloride depletion. The hygroscopic growth of NaCl/MA particles was well described by E-AIM, and that of NaCl/SA particles was dependent upon mixing ratio. Compared with model predictions, it was determined that water uptake of the NaCl/OA mixture could be enhanced and could be closer to the predictions by addition of levoglucosan or malonic acid, which retained water even at low relative humidity (RH), leading to inhibition of HCl evaporation during dehydration. These results demonstrate that the coexisting hygroscopic species have a strong influence on the phase state of particles, thus affecting chemical interactions between inorganic and organic compounds as well as the overall hygroscopicity of mixed particles.

Vanadium oxide cluster anions Vm(16)On(-) and Vm(18)On(-) were prepared by laser ablation and reacted with hydrogen sulfide (H2S) in a fast flow reactor under thermal collision conditions. A time-of-flight mass spectrometer was used to detect the cluster distributions before and after the interactions with H2S. The experiments suggest that the oxygen-for-sulfur (O/S) exchange reaction to release water was evidenced in the reactor for most of the cluster anions: VmOn(-) + H2S → VmOn-1S(-) + H2O. For reactions of clusters VO3(-) and VO4(-) with H2S, consecutive O/S exchange reactions led to the generation of sulfur containing vanadium oxide cluster anions VO3-kSk(-) (k = 1-3) and VO4-kSk(-) (k = 1-4). Density functional theory calculations were performed for the reactions of VO3-4(-) with H2S, and the results indicate that the O/S exchange reactions are both thermodynamically and kinetically favorable, which supports the experimental observations. The reactions of VmOn(+) cluster cations with H2S have been reported previously (Jia, M.-Y.; Xu, B.; Ding, X.-L.; Zhao, Y.-X.; He, S.-G.; Ge, M.-F. J. Phys. Chem. C 2012, 116, 9043), and this study of cluster anions provides further new insights into the transformations of H2S over vanadium oxides at the molecular level.

We present here a study of gas-phase reactivity of cobalt sulfide cluster anions Co(m)S(n)(-) with molecular oxygen. Nascent Co(m)S(n)(-) clusters were prepared via a laser ablation source and reacted with oxygen in a fast flow reactor under thermal collision conditions. We chose (18)O2 in place of (16)O2 to avoid mass degeneration with sulfur, and a time-of-flight (TOF) mass spectrometer was used to detect the cluster distributions in the absence and presence of the reactant. It was found that oxygen-sulfur exchange occurs in the reactions for those with specific compositions (CoS)(n)(-) and (CoS)(n)S(-) (n = 2-5) according to a consistent pathway, "Co(m)S(n)(-) + (18)O2 → Co(m)S(n-1)(18)O(-) + S(18)O". Typically, for "Co2S2(-) + (18)O2" we have calculated the reaction coordinates by employing the density functional theory (DFT), where both the oxygen-sulfur exchange and SO molecule release are thermodynamically and kinetically favorable. It is noteworthy that the reaction with molecular oxygen (triplet ground state) needs to overcome a spin excitation as well as a large O-O activation energy. This study sheds light on the activation of molecular oxygen by cobalt sulfides on one hand and also provides insight into the regeneration mechanism of cobalt oxides from the counterpart sulfides in the presence of oxygen gas on the other hand.

Transition metal oxide cluster anions M(m)(18)O(n)(-) (M = Fe, Co, Ni, Cu, and Zn) were prepared by laser ablation and reacted with H2S in a fast flow reactor under thermal collision conditions. A time-of-flight mass spectrometer was used to detect the cluster distributions before and after the interactions with H2S. The experiments reveal a suite of oxygen/sulfur (O/S) exchange and oxygen/sulfydryl (O/SH) exchange reactions. The O/S exchange reaction to release water was evidenced for all of the MO2(-) cluster anions: MO2(-) + H2S → MOS(-) + H2O, whereas the O/SH exchange reaction to derive MOSH(-) and OH species was only observed for reactions of NiO2(-), CuO2(-), and ZnO2(-). Density functional theory calculations were performed for reaction mechanisms of MO2(-) + H2S (M = Fe, Co, Ni, Cu, and Zn). The computational results are generally in good agreement with the experimental results. This gas-phase study provides an insight into the metal dependent reactivity in the removal of H2S over metal oxides.

The molecular and crystal structure of two dithiolactones (formally dimers of ε-caprothiolactone and ω-hexadecathiolactone) have been determined by X-ray diffraction at low temperature, revealing that the thioester group is planar with a synperiplanar orientation of the C═O double bond with respect to the S-C single bond. This conformational behavior is in contrast to that found for the smaller cyclic members of this family, where the antiperiplanar conformation is enforced. It is hypothesized that strain effects play a major role for the energy balance in the conformational preference. In this context, the molecular, vibrational (infrared and Raman), and electronic properties of ε-caprothiolactone have also been analyzed by using a combined experimental, including gas-phase helium I photoelectron spectroscopy, and computational approach.

Heterogeneous reactions on mineral aerosols remain an important subject in atmospheric chemistry because of their role in altering the properties of particles and the budget of trace gases. Yet, the role of coadsorption of trace gases onto mineral aerosols and potential synergistic effects are largely uncertain, especially synergistic effects between inorganic and organic gas-phase pollutants. In this study, synergistic effects between HCOOH and SO2 were investigated for the first time using in situ diffuse-reflectance infrared Fourier transform spectroscopy (DRIFTS). It was found that the heterogeneous reaction of HCOOH is hindered significantly by coexisting SO2. The total amount of formate decreased, whereas the total amount of sulfate was not affected during coadsorption on the surface of α-Fe2O3. Futhermore, part of the formate on the surface was catalytically decomposed to CO2 by α-Fe2O3 with the help of SO2. These results suggest a possible mechanism for the observed correlations between sulfate and carboxylate in the atmosphere.

Despite increased awareness of the role played by heterogeneous reactions of formic acid on mineral aerosol, the experimental determination of how these atmospheric reaction rates vary with temperature remain a crucially important part of atmosphere science. Here we report the first measurement of heterogeneous uptake of formic acid on α-Al(2)O(3) as a function of temperature (T = 240-298 K) at ambient pressure using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). From the analysis of the spectral features, crystalline HCOOH was identified at low temperature besides common product (formate ions) on the surface. It was also interesting to find that crystalline HCOOH can continue to react with α-Al(2)O(3). The reaction mechanisms at both room and low temperature were discussed. Furthermore, the reactive uptake coefficients were acquired and found to increase with decreasing temperature. Finally, the atmospheric lifetime of formic acid because of heterogeneous loss on mineral aerosol was estimated at temperatures related to the upper troposphere.

Two novel adsorbents to remove excess arsenate and arsenite in the drinking water were prepared for the first time by grafting monoamine and diamine, respectively, and then coordinating Fe(3+) on silica gel that was obtained using sol-gel method with two-step acid-base catalysis. It was found that both adsorbents had mesoporous structure, large specific surface, and high amino and iron content according to N(2) adsorption isotherms, FTIR, XPS, and NMR analysis. The removal ability and adsorption rate of the adsorbents were very high for both As(V) and As(III). Langmuir and Freundlich models were used to fit the adsorption isotherm and investigate the adsorption mechanism. The effects of chloride and sulfate anion on the removal of arsenate and arsenite for the two adsorbents were also studied., (Copyright © 2012 Elsevier B.V. All rights reserved.)

The heterogeneous kinetic processes of hydrogen peroxide on silicon dioxide (SiO2) and calcium carbonate (CaCO3) have been studied over the temperature range from 253 to 313 K using a Knudsen cell reactor, and the functions of temperature were obtained. The kinetic study indicates that the initial uptake coefficients increase evidently with a temperature decrease. They can be calculated by the equations γBET(SiO2) = [exp(934.5/T - 12.7)]/[1 + exp(934.5/T - 12.7)] and γBET(CaCO3) = [exp(1193.0/T - 11.9)]/[1 + exp(1193.0/T - 11.9)]. On the basis of the temperature dependence of uptake coefficients, the enthalpy (ΔHobs) and entropy (ΔSobs) of uptake progresses were determined to be -(7.77 ± 1.55) KJ mol(-1) and -(105.8 ± 21.2) J K mol(-1) for SiO2 and -(9.92 ± 1.98) KJ mol(-1) and -(98.6 ± 19.7) J K mol(-1) for CaCO3. The activation energies for desorption (Edes) of H2O2 on CaCO3 and SiO2 were calculated to be (5.9 ± 0.9) KJ mol(-1) and (9.15 ± 1.1) KJ mol(-1). The results suggest that hydrogen peroxide could mainly be adsorbed on SiO2 and CaCO3 reversibly in this temperature region, and the quick uptake on these mineral aerosols, especially at low temperature, provides an active surface for further complex reactions.

Multiphase acid-catalyzed oxidation by hydrogen peroxide has been suggested to be a potential route to secondary organic aerosol (SOA) formation from isoprene and its gas-phase oxidation products, but the kinetics and chemical mechanism remain largely uncertain. Here we report the first measurement of uptake of methacrolein into aqueous solutions of sulfuric acid and hydrogen peroxide in the temperature range of 253-293 K. The steady-state uptake coefficients were acquired and increased quickly with increasing sulfuric acid concentration and decreasing temperature. Propyne, acetone, and 2,3-dihydroxymethacrylic acid were suggested as the products. The chemical mechanism is proposed to be the oxidation of carbonyl group and C═C double bonds by peroxide hydrogen in acidic environment, which could explain the large content of polyhydroxyl compounds in atmospheric fine particles. These results indicate that multiphase acid-catalyzed oxidation of methacrolein by hydrogen peroxide can contribute to SOA mass in the atmosphere, especially in the upper troposphere.

Highly ordered mesoporous aluminas and calcium-doped aluminas were synthesized through a facile and reproducible method. Their fluoride adsorption characteristics, including adsorption isotherms, adsorption kinetics, the effect of pH and co-existing anions were investigated. These materials exhibited strong affinity to fluoride ions and extremely high defluoridation capacities. The highest defluoridation capacity value reached 450 mg/g. These materials also showed superb arsenic removal ability. 1g of mesoporous alumina was able to treat 200 kg of arsenic contaminated water with a pH value of 7, reducing the concentration of arsenate from 100 ppb to 1 ppb., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Kinetics of the reaction of NO3 radicals with tetrahydrofuran, 1, 3-dioxolane and 1, 4-dioxane at 298 K +/- 1 K and 1.01 x 10(5) Pa were investigated using a relative rate method in a self-made Teflon chamber. The objective of this study was to assess the possible impact of these volatile organic compounds (VOCs) on the environment by studying their atmospheric degradation kinetics. Using gas chromatograph with a flame ionization detector(GC/FID), the measured reaction rate constant for NO3 with tetrahydrofuran was (5.36 +/- 1.93) x 10(-3) cm (molecule x s)(-1), which is in good agreement with the reported values, indicating the reliability of our experiment setup and methods. The reactions of NO3 radicals with 1, 3-dioxolane and 1, 4-dioxane were studied for the first time and the measured rate constants were (1.84 +/- 0.70) x 10(-15) cm3 x (molecule x s)(-1) and (3.20 +/- 0.67) x 10(16) cm3 x (molecule x s)(-1), respectively. The atmospheric lifetimes of these compounds have also been estimated based on the measured rate constants, which indicate that emissions of these compounds may have an impact on regional atmospheric environment.

Multiphase acid-catalyzed oxidation with hydrogen peroxide (H2O2) has been suggested recently to be a potential route to SOA formation, but the kinetics and chemical mechanism of this process have not been well-known yet. In this work, the uptake of 3-methyl-3-buten-1-ol (MBO331) into aqueous mixed solutions of H2O2, and sulfuric acid (H2SO4) was performed using a rotated wetted-wall reactor coupled to a VUV single-photon ionization time of flight mass spectrometer (VUV-SPI-TOFMS). The reactive uptake coefficients (gamma) were acquired for the first time and the reaction pathways were deduced according to products information. The uptake of MBO331 into H2SO4/H2O2 was fast, resulting in gamma reaching 2.52 x 10(-4)-1.05 x 10(-2) for 40%-60% H2SO4. Acetaldehyde, acetone and 3-methyl-3, 4-expoxybutane-1-ol were suggested as gas-phase products in this process. 3-methyl-3,4-expoxybutane-1-ol can transform into polyhydroxy compounds while the further reactions of the carbonyl products can occur in acidic solution, which may play a role in SOA formation. Thus, the heterogeneous acid-catalyzed oxidation of MBO331 with H2O2 might be a significant contributor to SOA loading.

Objective: To evaluate the value of wavelet index (WLI) in general anesthesia through a comparison of WLI with bispectral index (BIS)., Methods: A total of 53 patients scheduled for elective surgery with ASA (American Society of Anesthesiologists) I-II were selected to undergo general anesthesia. The monitoring probes of BIS, WLI and muscle relaxation were connected in awaking patients. The values of WLI and BIS were recorded at 10 min (T₁) entering OR (operating room), immediate before anesthesia induction (T₂), when the OAA/S (observer's assessment of alertness/sedation) score declined gradually to 5(T₃), 4(T₄), 3(T₅), 2(T₆), 1(T₇) after the infusion of propofol, after vecuronium given when the TOF value decreased to 100 (T₈), 75(T₉), 50 (T₁₀), 25 (T₁₁), 0 (T₁₂) after the injection of vecuronium, tracheal intubation (T₁₃), 1 min (T₁₄), 3 min (T₁₅) and 5 min (T₁₆) after the completion of tracheal intubation, immediate before initiating surgical procedure (T₁₇), beginning the operation (T₁₈), 1 min (T₁₉), 3 min (T₂₀), 5 min (T₂₁) post-operation, skin suturing (T₂₂), end of surgery (T₂₃), tracheal extubation (T₂₄), 1 min (T₂₅) and 5 min (T₂₆)cd post-extubation, immediate before exiting OR (T₂₇)., Results: The value of WLI at T₁₀-T₁₃, T₂₂-T₂₇ was more than BIS (P < 0.05). The Bland-Altman analysis showed that WLI was accepted comparing with BIS during the period of anesthesia. The bias was -2.99, 95% limits of agreement -29.97% to 21.56%. The correlation coefficients of OAA/S score with BIS and WLI were: r(BIS) = 0.884, r(WLI) = 0.757 (P = 0.000)., Conclusion: WLI index is feasible for monitoring the depth of general anesthesia.

ClC(O)SSCl was prepared by an improved method by the reaction of [(CH(3))(2)CHOC(S)](2)S with SO(2)Cl(2) in hexane. The photoelectron spectra in the gas phase present four distinct regions, corresponding to ionizations from electrons formally located at the S, O, and Cl atoms and at the C═O bond. The vibrational IR and Raman spectra of the liquid were interpreted in terms of the most stable syn-gauche conformer (the O═C double bond syn with respect to the S-S single bond and the C-S single bond gauche with respect to the S-Cl single bond) in equilibrium with the less stable anti-gauche form, both occurring in two enantiomeric forms. The randomization process between the conformers was induced by broad-band UV-visible irradiation in matrix conditions, and several photoproducts were identified by FTIR spectroscopy. The experimental results were complemented by theoretical calculations., (© 2011 American Chemical Society)

The bioorganic carbon contents and chemical element compositions in six kinds of cereals: paddy (rice), wheat (flour), soybean, millet, sorghum and corn were determined by X-ray fluorescence (XRF) spectrum, meanwhile a new method was established to probe their protein contents. In the cereals, the average bioorganic carbon content is about 440%. The highest protein content is 42.74% from soybean, and other protein content is 28.56% in millet, 27.57% in wheat, 24.99% in corn, 22.21% in sorghum, but only 20.31% in rice. Based on our new definition of carbon chemical circulation presented in the current work, the authors have found that in 2009 humankind used bioorganic carbon to discharge CO2 into the earth's atmosphere that accounts for one percent of the total CO2 discharge, and consumed organic carbon to release CO2 into the earth's atmosphere, accounting for 10.73% of the total CO2 discharge. The clear definition of carbon chemical circulation and the discharged CO2 content from the distinct types of carbon compounds would advance the study on carbon chemical circulation and the atmospheric CO2 greenhouse effect. Our work further found that it takes eight years to circulate the total earth's atmospheric CO2. The short period shows the sensitivity for CO2 to keep its dynamical equilibrium in the earth's atmosphere. However, no experimental data has been reported to prove a heavy destructive greenhouse effect of CO2 existing in the earth's atmosphere.

The crystal structure of the six-member heterocyclic δ-valerothiolactone (1-thiocycloalkan-2-one) compound has been determined by X-ray diffraction at low temperature, revealing that its skeleton adopts a half-chair conformation. The conformation around the thioester group is almost planar with an anti orientation of the C=O double bond with respect the S-C single bond [C(2)-S(1)-C(6)-O(1) = 176.26(8)°]. The skeletal parameters, especially valence angles [∠C5-C6-S = 121.19(6)°, ∠O=C6-C5 = 122.25(8)°, ∠C6-S-C2 = 106.80(4)°], differ from those typically found in acyclic thioester compounds, symptomatic of the presence of strain effects. The conventional ring strain energy was determined to be 7.5 kcal/mol at the MP2/6-311++G(d,p) level of calculation within the hyperhomodesmotic model approximation. Moreover, the valence electronic structure was investigated by HeI photoelectron spectroscopy assisted by quantum chemical calculations at the OVGF/6-311++G(d,p) level of theory. The first three bands at 9.35, 9.50, and 11.53 eV denote ionizations related with the n(S), n(O), and π(C=O) orbitals, respectively, demonstrating the importance of the -SC(O)- group in the outermost electronic properties.

Two-dimensional coordination polymers, [M(C₈H₁₂O₄)(C₁₀H₈N₂)]·H₂O [M=Co (1), Cd (2); C₁₀H₈N₂ = 4,4-bipyridine, C₈H₁₄O₄=subaric acid] were obtained from the reaction of the metal salts, bipy and subaric acid at 180°C and characterized by elemental analysis, infrared spectrum, and single-crystal X-ray diffraction and surface photovoltage spectrum (SPS). The single-crystal X-ray diffraction showed that the subaric ligand in the two complexes exhibits two types of modes coordinating to transition metal ions, resulting in the formation of a 1D infinite chain along the c-axis. In addition, the results of SPS for complexes 1 and 2 indicate that these two complexes exhibit positive surface photovoltage responses in the range of 300-800 nm, which can be assigned to LMCT and MLCT, respectively. And the SPS of complex 1 also can be assigned to the d→d* electronic transition. The SPS spectra of the two complexes are consistent with their UV-vis spectra., (Copyright © 2010 Elsevier B.V. All rights reserved.)

The five-membered heterocyclic gamma-butyrothiolactone was isolated in a low-temperature, inert Ar matrix, and the UV-visible (200

Pure methoxycarbonylsulfenyl cyanide, CH(3)OC(O)SCN (I), and methoxycarbonylsulfenyl thiocyanate, CH(3)OC(O)SSCN (II), were prepared by reacting liquid CH(3)OC(O)SCl with either AgCN or AgSCN, respectively. Compounds I and II were characterized by (1)H NMR, CG-MS, and vibrational (FTIR and FT-Raman) techniques. The conformational properties have been studied by using vibrational spectroscopy [infrared (gaseous, liquid, and Ar matrix isolated), Raman (liquid) spectroscopy] together with quantum chemical calculations at the B3LYP and MP2 methods with the extended 6-311++G** and aug-cc-pVTZ basis sets. Compound I exhibits a conformational equilibrium at room temperature having the most stable form C(s) symmetry with a synperiplanar (syn) orientation of the carbonyl double bond (C=O) with respect to both the CH(3)O- and -SCN groups (syn-syn). Several bands assigned to a second conformer have been observed in the IR matrix spectra. This rotamer presents an antiperiplanar orientation of the thiocyanate group (syn-anti). Evaluating the equilibrium compositions at different temperatures by quenching the gas phase mixtures as Ar matrices allowed us to determine the conformational enthalpy difference DeltaH(0) = H(0)((syn-anti)) - H(0)((syn-syn)) = 0.80(18) kcal mol(-1). A similar conformational behavior has been determined for compound II. Thermodynamic properties were also computed at the high-level G2MP2 and G3 model chemistry methods. The importance of mesomeric (resonance) and anomeric (hyperconjugation) electronic interaction in the conformational behavior is evaluated by using the NBO approach for both species.

Reactions of small cationic iron oxide clusters (Fe(2)O(4-6)(+)) with N(2) are investigated by experiments and first principle calculations. The cationic iron oxide clusters are generated by reaction of laser ablated iron plasma with O(2) in a supersonic expansion, and are reacted with N(2) in a fast flow reactor at near room temperature conditions. Cluster cations are detected by a time-of-flight mass spectrometer. The substitution reaction Fe(2)O(n)(+) + N(2) --> Fe(2)O(n-2)N(2)(+) + O(2) is observed for n = 5 but not for n = 4 and 6. Density functional theory calculations predict that the low-lying energy structures of Fe(2)O(4-6)(+) are with side-on (eta(1)-O(2)) or end-on (eta(2)-O(2)) bonded molecular oxygen unit(s). The calculations further predict that the substitution of eta(1)-O(2) and eta(2)-O(2) in Fe(2)O(4,6)(+) clusters by N(2) is exothermic and subject to negative and positive overall reaction barriers, respectively, at room temperature. We thus propose that the ground state structures of Fe(2)O(4)(+) and Fe(2)O(6)(+) contain eta(2)-O(2). In contrast, both the experiment and theory favor a eta(1)-O(2) in the ground state structure of Fe(2)O(5)(+).

The four-membered heterocyclic beta-propiothiolactone compound was isolated in a low-temperature inert Ar matrix, and the UV-visible (200 < or = lambda < or = 800 nm) induced photochemistry was studied. On the basis of the IR spectra, the formation of methylketene (CH(3)CHCO) was identified as the main channel of photodecomposition. The formation of ethene and thiirane, with the concomitant elimination of OCS and CO, respectively, was also observed as minor decomposition channels. The valence electronic structure was investigated by HeI photoelectron spectroscopy assisted by quantum chemical calculations at the OVGF/6-311++G(d,p) level of theory. The first three bands at 9.73, 9.87, and 12.06 eV are ascribed to the n''(S), n'(O), and pi''(CO) orbitals, respectively, denoting the importance of the -SC(O)- group in the outermost electronic properties. Additionally, the structure of a single crystal, grown in situ, was determined by X-ray diffraction analysis at low temperature. The crystalline solid [monoclinic system, P21/c, a = 8.1062(1) A, b = 10.3069(2) A, c = 10.2734(1) A, beta = 107.628(1) degrees, and Z = 8] consists of planar molecules arranged in layers. The skeletal parameters, especially the valence angles [angleC2-C1-S = 94.55(7) degrees, angleOC-C = 134.20(11) degrees, angleC-S-C = 77.27(5) degrees], differ from those typically found in acyclic thioester compounds, suggesting the presence of strong strain effects. The conventional ring strain energy was determined to be 16.4 kcal/mol at the G2MP2 level of calculation within the hyperhomodesmotic model.

Density functional theory (DFT) calculations have been used to investigate acetylene cyclotrimerization catalyzed by titanium and vanadium dioxides. The calculated results illustrate that the overall process is highly favorable at room temperature from both thermodynamic and kinetic points of view. The mechanism of C2H2 cyclotrimerization over MO2 (M = Ti, V) can be understood as four steps: (1) a four-membered ring (-O-M-C=C-) formation that coordinates and activates the first C2H2 molecule; (2) the second C2H2 insertion into the M-C bond to form a six-membered ring (-O-M-C=C-C=C-); (3) the third C2H2 insertion into the M-C bond to form an eight-membered ring (-O-M-C=C-C=C-C=C-); and (4) contraction of the eight-membered ring and benzene formation and desorption. All of the reaction steps are overall barrierless with respect to the separated reactants (MO2C2xH2x + C2H2, x = 0, 1, 2). This theoretical study predicts that the M=O double bond in MO2 is very catalytic toward the C2H2 cyclotrimerization. The metal center in this study can be considered always in the same +4 oxidation state (Ti4+ and V4+). In contrast, two-electron cycling of the metal center is present in the documented mechanism for the C2H2 cyclotrimerization. The C2H2 cyclotrimerization over the Ti atom and TiO molecule is also studied, and the documented mechanism applies in this case. The new mechanism is suggested to apply to reactions using titanium and vanadium oxides as catalysts.

A series of Cu(II) complexes Cu(2)[micro-pz](2)[HB(pz)(3)](2) (1), Cu[H(2)B(pz)(2)](2) (2), Cu[HB(pz)(3)](2) (3), Cu[HB(pz(Me2))(3)](2) (4), Cu[B(pz)(4)](2) (5) (pz=pyrazole), have been synthesized and characterized by elemental analysis, IR, UV-vis, X-ray diffraction, thermal analysis and theoretical analysis. The IR spectra give the Cu-N vibration modes at 322, 366, 344, 387, and 380 cm(-1) in complexes 1-5, respectively. The UV spectra show all the complexes have same UV absorption at 232 nm; there is another band at 332 nm for complexes 1, 2 and 4, while for complexes 3 and 5, the bands are at 272 and 308 nm, respectively. Complex 1 has a binuclear structure in which two pyrazole ligands bridge two Cu-Tp units. In 2-5, the Cu(II) centers are coordinated with dihydrobis(pyrazolyl)borate (Bp), hydrotris(pyrazolyl)borate (Tp), hydrotris(3,5-Me2pyrazolyl)borate (Tp'), tetrakis(pyrazolyl)borate (Tkp) respectively to form a mononuclear structure. The results of thermal analysis for complexes 1-5 are discussed too.

A series of characteristic experiments were conducted in a self-made photochemical smog chamber, which was used to simulate atmospheric photochemical reactions of acetylene and NO(x) under room temperature of (20 +/- 1) degrees C. The effect of acetylene and NO(x) on ozone production by photochemical reactions was discussed. The wall decay of O3 and NO2 were determined, which were 5.80 x 10(-6) s(-1) and 2.41 x 10(-6) s(-1), respectively. Such decay should be omitted relative to O3 and NO2 in simulative experiments. The effective light intensity for a single black lamp of 40 W was determined to be 0.64 x 10(-3) s(-1), which was expressed by the photolysis rate of NO2. The effect of different light intensity, initial concentrations of acetylene and NO(x) on O3 production was discussed after correction of background O3 from purified air. The incremental reactivity (IR) of acetylene were calculated. For four different experiments, the maximum values of IR are 1.76 x 10(-2), 2.68 x 10(-2), 2.04 x 10(-2) and 2.84 x 10(-2), respectively. It is found that there are close relationships between IR and initial acetylene concentrations, and between IR and irradiation intensity, and that there is no significant relation between IR and initial NO(x) concentrations.

A continuous tert-butoxy (CH3)+CO* radical beam is produced in situ by respective pyrolysis of both (CH3)3CONO at 115(+/-0.5) degrees C and (CH3)3COOC(CH3)3 at 87(+/- 0.5) degrees C. By combining the HeI photoelectron (PE) spectrum with the improved density function theory (DFT) calculations, we have concluded that the (CH3)3CO* radical has C3V symmetry and X2E ground state. The study does not only provide the ionization energies of different ionic states of the (CH3)3CO* radical for the first time, but also the first example in which there have been similar vibrational structures in different ionic states caused by removal of the electron on an orbital. It is also pointed out that (CH3)3CONO is a good source for obtaining the (CH3)3CO* radical beam, and that NO is a stable regent for the active radical. The results will promote the studies in electron spin resonance (ESR) research on the mechanisms of both the initiation of the formation of a new radical and the radical-chain polymerization in which the (CH3)3CO* radical participates.