Toward ICP-SIFT mass spectrometry and atomic cation ligation as a probe of relativistic effects—A personal journey

The ICP–SIFT mass spectrometer at York University, a derivative of flowing afterglow (FA) and selected-ion flow tube (SIFT) mass spectrometers, has provided a powerful technique to measure the chemistry and kinetics of atomic cation–molecule reactions. Here, I focus on periodic trends in the kinetics of ligation reactions of atomic ions with small molecules. I examine trends in ammonia ligation kinetics across the first two rows of the atomic transition metal cations and their correlation with ligand bond enthalpies and ligand field stabilization energies. Also explored are trends down Groups 1 and 2 in the kinetics of noncovalent electrostatic ligand bonding and the tendency for s electron solvation of the atomic alkaline-earth cations with ammonia. Finally, I briefly review trends observed with 12 different ligands in the ligation rate down the periodic table with Group 9–12 transition atomic metal cations. These trends provide a compelling probe for the presence of relativistic effects that influence the strengths of the metal-ion ligand bonds that are formed. There is a clear third-row rate enhancement with Ir⁺, Pt⁺, Au⁺, and Hg⁺, the extent of which depends on the nature of the ligand. This large set of kinetic data provides an unprecedented broad perspective of relativistic effects in ligand bonding. With CS₂ as a ligand, the third-row relativistic effect is apparent in the formation of both the first and the second ligand bond with the Groups 10 and 11 atomic cations as predicted by our quantum chemical calculations of ligation energies.     

Characterization of the absorption of histidine and lead by Juglan regia L., Platanus L., and Pinus nigra L. using high-performance liquid chromatography–mass spectrometry and inductively coupled plasma–mass spectrometry

High-performance liquid chromatography–mass spectrometry and inductively coupled plasma – mass spectrometry were used for the determination of histidine and lead in Juglan regia L., Platanus L., and Pinus nigra L. leaves from industrial areas including Gaziantep City and Bursa City, Turkey. Distilled water was used for the extraction of histidine from plant material at 90°C for 30 min. The flow rate of the mobile phase, fragmentation potential, injection volume, and column temperature were optimized to be 0.2 mL min^?1, 70 V, 15 µL, and 20°C for the determination of histidine. The concentrations of histidine were from 7–9 mg kg^?1 for Juglan regia L., 2–5 mg kg^?1 for Platanus L., and 1–7 mg kg^?1 for Pinus nigra L. The concentrations of Pb were from 1–42 mg kg^?1 for Juglan regia L., 1–4 mg kg^?1 for Platanus L., and 1–62 mg kg^?1 for Pinus nigra L.     

Analysis of environmental organic matters by Ultrahigh-Resolution mass spectrometry—A review on the development of analytical methods

Owing to the increasing environmental and climate changes globally, there is an increasing interest in the molecular-level understanding of environmental organic compound mixtures, that is, the pursuit of complete and detailed knowledge of the chemical compositions and related chemical reactions. Environmental organic molecule mixtures, including those in air, soil, rivers, and oceans, have extremely complex and heterogeneous chemical compositions. For their analyses, ultrahigh-resolution and sub-ppb level mass accuracy, achievable using Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS), are important. FT-ICR MS has been successfully used to analyze complex environmental organic molecule mixtures such as natural, soil, particulate, and dissolved organic matter. Despite its success, many limitations still need to be overcome. Sample preparation, ionization, structural identification, chromatographic separation, and data interpretation are some key areas that have been the focus of numerous studies. This review describes key developments in analytical techniques in these areas to aid researchers seeking to start or continue investigations for the molecular-level understanding of environmental organic compound mixtures.     

Inverse determination of Johnson–Cook model constants of ultra-fine-grained titanium based on chip formation model and iterative gradient search

In this paper, a systematic approach on how to predict kinematic errors based on tolerance of machine tools’ guideways is introduced. Firstly, the truncated Fourier series function is applied to fit curve of guideways surface. Since geometric profile errors are regarded as a bridge between tolerance and kinematic errors of machine tools’ guideways, the mapping relationship between tolerance and geometric profile errors of machine tools’ guideways is formulated, and the mapping relationship between geometric profile errors and kinematic errors of guideways is established. Then, kinematic errors prediction model based on tolerance of guideways is subsequently proposed. Finally, simulation verification is conducted with this method. Simulation results show the range of the predicted kinematic errors (positioning error, y direction and z direction straightness error, roll error, pitch error, and yaw error) is 17.12 μm, 56.57 μm, 70.71 μm, 28.28 μrad, 141.42 μrad, and 113.14 μrad, respectively. In order to verify the feasibility and effectiveness of the presented method, a measuring experiment is carried out on guideways of a gantry-type five-axis milling machine tools by using a dual-frequency laser interferometer. The measured and identified discrete data can be fitted precisely by Fourier curve fitting method. The fitting results show the range of the measured kinematic errors is 16.96 μm, 59.43 μm, 68.63 μm, 28.65 μrad, 135.40 μrad, and 111.58 μrad, respectively. The maximum residual errors between the predicted and measured values of kinematic errors are 1.67 μm, 5.19 μm, 5.50 μm, 1.87 μrad, 9.81 μrad, and 7.07μrad, respectively. Comparing with the measured results of kinematic errors, residual errors are considerably small and can be neglected. Therefore, there is no doubt that this method is effective enough for predicting kinematic errors and can be used to replace the measurement of kinematic errors. In the design stage of machine tools, this approach is convenient for engineers to derive the distribution of kinematic errors. And its basic idea can be applied to other type of machine tools’ guideways.     

Note: Laser-induced acoustic desorption∕synchrotron vacuum ultraviolet photoionization mass spectrometry for analysis of fragile compounds and heavy oils

In this work, we coupled synchrotron vacuum ultraviolet photoionization (SVUV PI) method with the laser-induced acoustic desorption (LIAD) technique for mass spectrometric analysis. The LIAD technique is a "soft" desorption method, which could avoid the degradation of analytes during desorption process. Meanwhile, SVUV PI is an efficient "soft" ionization source. The new combination of the "soft" desorption technique and "soft" photoionization method is well suitable to reduce the difficulty for interpreting the mass spectra of the fragile compounds and heavy oils.     

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2017–2018

This review is the tenth update of the original article published in 1999 on the application of matrix-assisted laser desorption/ionization mass spectrometry (MALDI) mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2018. Also included are papers that describe methods appropriate to glycan and glycoprotein analysis by MALDI, such as sample preparation techniques, even though the ionization method is not MALDI. Topics covered in the first part of the review include general aspects such as theory of the MALDI process, new methods, matrices, derivatization, MALDI imaging, fragmentation and the use of arrays. The second part of the review is devoted to applications to various structural types such as oligo- and poly-saccharides, glycoproteins, glycolipids, glycosides, and biopharmaceuticals. Most of the applications are presented in tabular form. The third part of the review covers medical and industrial applications of the technique, studies of enzyme reactions, and applications to chemical synthesis. The reported work shows increasing use of combined new techniques such as ion mobility and highlights the impact that MALDI imaging is having across a range of diciplines. MALDI is still an ideal technique for carbohydrate analysis and advancements in the technique and the range of applications continue steady progress.     

Design and analysis of a new AUV’s sliding control system based on dynamic boundary layer

The new AUV driven by multi-vectored thrusters not only has unique kinematic characteristics during the actual cruise but also exists uncertain factors such as hydrodynamic coefficients perturbation and unknown interference of tail fluid,which bring difficult to the stability of the AUV’s control system.In order to solve the nonlinear term and unmodeled dynamics existing in the new AUV’s attitude control and the disturbances caused by the external marine environment,a second-order sliding mode controller with double-loop structure that considering the dynamic characteristics of the rudder actuators is designed,which improves the robustness of the system and avoids the control failure caused by the problem that the design theory of the sliding mode controller does not match with the actual application conditions.In order to avoid the loss of the sliding mode caused by the amplitude and rate constraints of the rudder actuator in the new AUV’s attitude control,the dynamic boundary layer method is used to adjust the sliding boundary layer thickness so as to obtain the best anti-chattering effects.Then the impacts of system parameters,rudder actuator’s constraints and boundary layer on the sliding mode controller are computed and analyzed to verify the effectiveness and robustness of the sliding mode controller based on dynamic boundary layer.The computational results show that the original divergent second-order sliding mode controller can still effectively implement the AUV’s attitude control through dynamically adjusting the sliding boundary layer thickness.The dynamic boundary layer method ensures the stability of the system and does not exceed the amplitude constraint of the rudder actuator,which provides a theoretical guidance and technical support for the control system design of the new AUV in real complex sea conditions.     

Friction and wear characteristics of organic thiophosphoro derivatives — a critical appraisal

The friction- and wear-reducing characteristics of a number of oil soluble sulphurised and phosphosulphurised derivatives for automotive and industrial applications have been reviewed. A critical appraisal of the suggested causes and mechanism of friction reduction and antiwear characteristics has been made. A review of the investigations carried out so far indicates that the creation of in situ films of simple inorganic salts, such as molybdenum disulphide, iron sulphide or phosphates of low shear strength and lamellar structures, does not appear to be the primary cause of low friction and wear. The authors have, therefore, undertaken a programme to synthesise and study the chemistry and tribochemical reactions in relation to friction and wear characteristics of hydrocarbon-soluble thiophosphoro derivatives of alkyl phenol, alcohols and fatty esters, in order to establish relationships between the reactivity, chemical nature and crystal structure of films formed on rubbing surfaces, and antifriction and antiwear characteristics. Molybdenum salts of various phosphorothio derivatives of pentadecylphenol and lauryl oleate of specific structures have been synthesised, and the friction and wear properties of their blends in mineral oil base stock have been studied. It can be clearly inferred from the results that type of bonding between sulphur, phosphorus and molybdenum, and reactivity of these derivatives with rubbing surfaces, determine their friction-reducing and antiwear characteristics. Their reactivity with iron and the nature of films formed are under investigation.     

Geographic analysis of the cultivation region of Ai pian derived from Blumea balsamifera through the determination of volatiles in the medicinal product and blood of treated mice by gas chromatography – mass spectrometry (GC-MS)

Abstract

Ai pian, derived from Blumea balsamifera (L.) DC. has various medicinal effects and a complex composition. The goal of this study was to analyze the chemical composition of Ai pian by using samples from different regions to explore differences between the chemical composition and its blood composition from treated mice to clarify whether its efficacy is related to synergism of multiple components to provide references for rational quality control. Gas chromatography – mass spectrometry (GC-MS) was used to determine and compare chemical compositions of blank and Ai pian containing serum of mice after 30?min of oral administration of Ai pian of seven batches from Zhenfeng, Wangmo and Luodian Counties; Guizhou Province; and Tian’e County; and Guangxi Province. Sixteen to twenty-two compounds of Ai pian were identified, with fourteen common compounds including L-borneol, L-camphor, borneol acetate, L-linalool, α-gurjunene, and 3-t-butyl-1, 2-dimethoxybenzene. Four to seven compounds were identified as blood components of Ai pian, and L-borneol, L-camphor, and borneol acetate were common prototypes with relative compositions from 13.720 to 36.509%, 2.336 to 5.219%, and 0.401 to 1.188%, respectively. Methyl oleate was a common metabolic component with a relative concentration of 0.021 to 0.446%. The chemical composition and blood components of Ai pian were complex, and its efficacy was related to synergism between several components including L-borneol, L-camphor, and borneol acetate. Therefore, detecting multiple index components of Ai pian is essential for quality control.     

Analysis of precision deburring using a laser —An experimental study and FEM simulation

The purpose of this study is to develop an effective methods for automated deburring of precision components. A high power laser is proposed as a deburring tool for complex part edges and burrs. For the laser experiments, rectangular-shaped carbon steel and stainless steel machined specimens with burr along one side were prepared. A 1500 Watts CO₂ laser was used to remove burrs on the workpieces. The prediction of the heat affected zone (HAZ) and cutting profile of laser-deburred parts using finite element method is presented and compared with the experimental results. This study shows that the finite element method (FEM) analysis can effectively predict the thermal affected zone of the material and that the technique can be applied to precision components.     

Anisotropy of machined surfaces involved in the ultra-precision turning of single-crystal silicon—a simulation and experimental study

A new method was proposed for simulating the anisotropic surface quality of machined single-crystal silicon. This represents the first time that not only the mechanical properties of silicon, but also the crystal orientation, which is closely linked to the turning process, have been given consideration. In this paper, the crystallographic relationship between machined crystal planes and slip planes involved in ultra-precision turning was analyzed. The elasticity, plasticity, and brittleness properties of silicon in different crystal orientations were calculated. Based on the brittle–ductile transition mechanism of ultra-precision turning of single-crystal silicon, the orientation dependence of the surface quality of (111), (110), and (100) crystal planes were investigated via computer simulation. According to the simulation results, the surface quality of all machined planes showed an obvious crystallographic orientation dependence while the (111) crystal plane displayed better machinability than the other planes. The anisotropic surface properties of the (111) plane resulted from the continuous change of the cutting direction, which causes a change of actual angle between the slip/cleavage plane and machined plane. Anisotropic surface properties of planes (100) and (110) result from anisotropy of mechanical properties and the continuous changes of the cutting direction, causing the actual angle between slip/cleavage plane and machined plane to change simultaneously. A series of cutting experiments were carried out on the (111) and (100) crystal planes to verify the simulation results. The experimental results showed that cutting force fluctuation features and surface roughness are consistent with the anisotropy characteristics of the machined surface as revealed in simulation studies.     

Dynamic performance of a cable with an inspection robot — analysis, simulation, and experiments

A special cable inspection robot is designed to inspect automatically the cables of a cable-stayed bridge. The free vibration equation of the cable-robot system is derived firstly to study the dynamic characteristics and safety performance of the system. Then, the effect of the robot on the cable natural frequency is discussed, and the dynamic response equation when a robot is climbing at a constant speed is deduced. Furthermore, the effect of the cable vibration on the robot’s climbing ability is studied. The natural frequency characteristics of the robot are analyzed and optimized to avoid the resonance between the cable and the robot, using a finite element model. Additionally, dynamic cable responses are simulated under different conditions wherein the robot mass are 10 and 200 kg, and the speeds are 0.2 and 0.3 m/s, respectively. At last, to demonstrate further the dynamic characteristics of the cable-robot system experimentally, cables are set up on the Junshan highway bridge over the Yangtze river. Similar experimental models of these cables are constructed, and vibration experiments are conducted to validate the theoretical calculation. The results show that a light robot has little effects on the cable vibration amplitude and vibration acceleration; this confirms the safety of the cable.     

Automated ultratrace determination of musty odiferous compounds from environmental waters by online purge and trap (P&T) gas chromatography–mass spectrometry (GC–MS)

Abstract

Odoriferous compounds are troublesome in natural waters in many parts of the world. The simultaneous determination of these complex compounds due to their low sample concentration and odor thresholds has been difficult. A simple, sensitive and automated technique for the determination of eight odoriferous compounds from aqueous samples was developed using online purge and trap (P&T) coupled to gas chromatography with mass spectrometry. P&T was selected to extract and purify the water samples. Several parameters that affect the extraction and concentration performance were investigated, including the trap sorbent, ionic strength, purge time, sample temperature and desorption time. Under the optimal conditions, the adsorption capacity for the Tenax TA sorbent to 2-isopropyl-3-methoxypyrazine, 4-chloroanisole, 2-isobutyl-3-methoxypyrazine, 2-methylisoborneol, 2-tert-butylphenol, 2,4-dichloroanisole, 2,4,6-trichloroanisole and geosmin reached an equilibration when sample volume was 25?ml at a concentration of 150.0?μg/l. The method provided good linearity in the range from 1.0 to1000?ng/l and the limits of detection were from 0.1 to 0.3?ng/l, which are below the odor thresholds for most of these compounds. The proposed method was applied to the determination of eight odoriferous compounds in surface and tap waters with recoveries from 74.7% to 112.8% and relative standard deviations from 2.6% to 10.8%. This method may be widely employed for monitoring odoriferous compounds in water samples.     

Thermogravimetric analysis of carbon black and engine soot—Towards a more robust oil analysis method

This work examined the thermal behaviour of diesel engine produced soot and commercial carbon black using thermogravimetric analysis (TGA). It was found that during TGA analysis of the carbon matrices (at a temperature range commonly used for soot-in-oil content determination), a gradual mass loss occurred. This was attributed to pyrolysis effects and combustion processes occurring due to poor hydrodynamic design of some commercial thermobalances. This process resulted in a significant mass loss of the carbon during TGA. This finding may strongly effect soot-in-oil analysis conducted using current methods. Experiments were conducted using a range of soot-in-oil mixtures according to the widely used thermogravimetric standard method ASTM 5967-08 which showed a significant underestimation of the soot content in the oil as a result of carbon mass loss due to combustion and/or pyrolysis effects. An improved oil analysis method is proposed which provides a significantly increased accuracy of soot determination in lubricant oils.     

Effect of in-situ processing parameters on microstructure and mechanical properties of TiC particulate reinforced Al–4.5Cu alloy MMC fabricated by stir-casting technique – Optimization using grey based differential evolution algorithm

Fabrication of metal matrix composite materials by using the traditional casting process is a very promising task of developing near net shape products at a very low cost. Among these casting processes, the stir-casting technique has fine microstructures because of fast cooling, less porosity and good quality bonding among particle and the base matrix alloy. The major aim of this present paper is to fabricate titanium carbide reinforced metal matrix composite (MMC) by using micron sized activated charcoal powder, to get react with titanium material for producing TiC intermetallic particles in the Al–4.5%Cu matrix by in-situ technique so as to produce Al–4.5%Cu–5%TiC MMC, with the intention of finding the optimum processing parameter i.e. pouring temperature, stirring speed in liquid melt-stirring process, reaction time with the aim of achieving better microstructure and mechanical properties, i.e. micro-hardness, toughness and ultimate tensile strength by using an efficient grey based differential evolution algorithm. Mechanical properties of optimum processing condition are verified by doing confirmation tests. ANOVA analysis is performed to analyze the role of each factor on multiple performance characteristics and it was found that stirrer rotational speed and reaction time is playing a key role in affecting the mechanical property. Additionally, to predict the response parameters regression equations were developed and the validity of regression model is tested by plotting scatter diagram. Finally microstructure study has been performed for the optimal sample by using optical microscope.     

Non-stationary signal analysis based on general parameterized time–frequency transform and its application in the feature extraction of a rotary machine

With the development of large rotary machines for faster and more integrated performance, the condition monitoring and fault diagnosis for them are becoming more challenging. Since the time-frequency (TF) pattern of the vibration signal from the rotary machine often contains condition information and fault feature, the methods based on TF analysis have been widely-used to solve these two problems in the industrial community. This article introduces an effective non-stationary signal analysis method based on the general parameterized time–frequency transform (GPTFT). The GPTFT is achieved by inserting a rotation operator and a shift operator in the short-time Fourier transform. This method can produce a high-concentrated TF pattern with a general kernel. A multi-component instantaneous frequency (IF) extraction method is proposed based on it. The estimation for the IF of every component is accomplished by defining a spectrum concentration index (SCI). Moreover, such an IF estimation process is iteratively operated until all the components are extracted. The tests on three simulation examples and a real vibration signal demonstrate the effectiveness and superiority of our method.     

Development of a high-voltage waveguide photodetector comprised of Schottky diodes and based on the Ge–Si structure with Ge quantum dots for portable thermophotovoltaic converters

This paper demontstrates the possibility of developing a high-voltage waveguide photodetector comprised of Schottky diodes and based on a Au/Ge — Si structure with Ge quantum dots pseudomorphic to a silicon matrix, which ensures an increase in the external quantum yield and open-circuit voltage. It is shown on this photodetector that there is a great increase and broadening in sensitivity up to λ = 2.1 μm, which coincides with the main radiation range of a black (gray) body at the emitter temperatures from 1200 to 1700 °C, practically used in thermophotovoltaic converters. This state of the ensemble of Ge quantum dots by means of molecular beam epitaxy can be obtained only under the condition of low growth temperature (250–300 °C). It is established that, below the Si absorption edge, photoresponse on the photodetectors under consideration is determined by two main mechanisms: absorption on the ensemble of Ge quantum dots and Fowler emission. It is shown by the analysis of the Raman scattering spectra on the optical photons of Ge–Si structures that the quantum efficiency of photodetectors based on them in the first case is due to the degree of nonuniform stress relaxation in the array of Ge quantum dots. The photoresponse directly associated with the Ge quantum dots is manifested on Schottky diodes with a superthin intermediate oxide layer SiO₂, which eliminates the second mechanism. In further development, the proposed photodetector architecture with pseudomorphic Ge quantum dots can be used both for portable thermophotovoltaic converters and fiber-optic data transmission systems at wavelengths corresponding to basic telecommunication standards (λ = 0.85, 1.3 and 1.55, 1.3, and 1.55 μm) on the basis of silicon technologies.