Fourier transform ion cyclotron resonance mass spectrometry at the true cyclotron frequency

Ion cyclotron resonance (ICR) cells provide stability and coherence of ion oscillations in crossed electric and magnetic fields over extended periods of time. Using the Fourier transform enables precise measurements of ion oscillation frequencies. These precisely measured frequencies are converted into highly accurate mass-to-charge ratios of the analyte ions by calibration procedures. In terms of resolution and mass accuracy, Fourier transform ICR mass spectrometry (FT-ICR MS) offers the highest performance of any MS technology. This is reflected in its wide range of applications. However, in the most challenging MS application, for example, imaging, enhancements in the mass accuracy of fluctuating ion fluxes are required to continue advancing the field. One approach is to shift the ion signal power into the peak corresponding to the true cyclotron frequency instead of the reduced cyclotron frequency peak. The benefits of measuring the true cyclotron frequency include increased tolerance to electric fields within the ICR cell, which enhances frequency measurement precision. As a result, many attempts to implement this mode of FT-ICR MS operation have occurred. Examples of true cyclotron frequency measurements include detection of magnetron inter-harmonics of the reduced cyclotron frequency (i.e., the sidebands), trapping field-free (i.e., screened) ICR cells, and hyperbolic ICR cells with quadrupolar ion detection. More recently, ICR cells with spatially distributed ion clouds have demonstrated attractive performance characteristics for true cyclotron frequency ion detection. Here, we review the corresponding developments in FT-ICR MS over the past 40 years.     

Susceptibility of chloride ion concentration,temperature, and surface roughness on pitting corrosion of CoCrFeNi medium-entropy alloy

The influence and susceptibility of chloride ion concentration, temperature, and surface roughness on corrosion behavior of single-phase CoCrFeNi medium-entropy alloy (MEA) was examined in NaCl solution. Potentiodynamic polarization results revealed that the corrosion performance of the sample deteriorated with an increase of the chloride ion concentration, temperature, and surface roughness. The pitting potential decreased drastically for samples with higher surface roughness. According to electrochemical impedance spectroscopy, the charge transfer resistance decreased when chloride ion concentration, temperature, and surface roughness increased. Scanning electron micrographs also indicated an increased extent of corrosion damage, especially for the sample with higher surface roughness. It is found that the corrosion resistance is closely related to the wettability of samples, and the surface with the highest roughness shows higher hydrophilicity. The combined results suggested that the pitting damage is more sensitive to surface roughness. Our findings provide a further understanding of the corrosion mechanism of MEAs and guide their applications as structural materials.     

放射性废离子交换树脂高温裂解处理技术研究

通过热重实验以及台架试验,进行了废阴/阳离子交换树脂的高温裂解处理技术研究。结果表明,通过电磁感应加热反应器中的金属球并辅助搅拌,可以实现树脂的高温裂解。相比于氮气和水蒸气,空气是更合适的反应气氛。在空气氛围下,当树脂处理量为1 kg/h时,设定空气流量2 m³/h,反应温度600 ℃～700 ℃,添加剂选择CuSO₄·5H₂O,阴/阳离子交换树脂经本裂解工艺处理,废物残留率分别为8%和12%左右,两种树脂最终的裂解残留率可以达到3%～5%左右,可以实现较为彻底的裂解反应。阴离子和阳离子交换树脂的裂解反应有明显的区别,其中阴离子交换树脂热敏性更高,裂解需要的温度和空气流量更低,但反应更剧烈,烟气量更大。     

One‐Step Construction of N,P‐Codoped Porous Carbon Sheets/CoP Hybrids with Enhanced Lithium and Potassium Storage

Despite the desirable advancement in synthesizing transition‐metal phosphides (TMPs)‐based hybrid structures, most methods depend on foreign‐template‐based multistep procedures for tailoring the specific structure. Herein, a self‐template and recrystallization–self‐assembly strategy for the one‐step synthesis of core–shell‐like cobalt phosphide (CoP) nanoparticles embedded into nitrogen and phosphorus codoped porous carbon sheets (CoP?NPPCS), is first proposed. Relying on the unusual coordination ability of melamine with metal ions and the cooperative hydrogen bonding of melamine and phytic acid to form a 2D network, a self‐synthesized single precursor can be attained. Importantly, this approach can be easily expanded to synthesize other TMPs?NPPCS. Due to the unique compositional and structural characteristics, these CoP?NPPCSs manifest outstanding electrochemical performances as anode materials for both lithium‐ and potassium‐ion batteries. The unusual hybrid architecture, the high specific surface area, and porous features make the CoP?NPPCS attractive for other potential applications, such as supercapacitors and electrocatalysis.     

Experimental and optimization of material synthesis process parameters for improving capacity of lithium‐ion battery

New methods for synthesis of active materials have been developed to improve capacity and cycle life performance of lithium‐ion batteries. Past studies have focused on routes of development of materials and new processes, which might not be economical for large‐scale production. In this regard, this study examines a widely employed carbothermal reduction technology for the synthesis of lithium‐iron phosphate (LiFePO₄/C) and investigates effects of process conditions during this synthesis on final battery performance. An experimental combined genetic programming approach is used to model the effects of crucial process conditions (sintering time, the carbon content, and the sintering temperature) on the discharge capacity of the assembled battery. Experiments are conducted to collect the discharge capacity data based on varying LiFePO₄/C synthesis conditions, and genetic programming is employed to develop a suitable functional relationship between them. The results show that the battery discharge capacity is controlled significantly by adjusting sintering temperature and carbon content, while the effect of sintering time is found to be insignificant. Further, the interaction effect of the sintering time and carbon content is much more obvious than that of the sintering time and the sintering temperature. The findings from the study pave the way for the optimum design of the synthesis process of LiFePO₄/C for a higher battery performance.     

Determination of chlorine ions in raw milk by pulsed amperometric detection in a flow injection system

Chloride ion concentration in milk was determined by pulsed amperometric detection in a flow injection system. Results showed that the Au electrode lost 3 electrons at 1.10 V and formed chloroaurate ions (AuCl₄^?) by combining with chloride ions, after which AuCl₄^? was partly reduced to Au at 0.6 V. Based on the electrochemical process, a triple waveform with detection potential of 1.15 V, detection time of 150 ms, oxidation potential of 1.4 V, oxidation time of 550 ms, reduction potential of 0 V, and reduction time of 400 ms was applied to the Au electrode for detecting chloride ion concentration in milk. The approach is rapid and automatic and features a detection limit of 0.005 g/L. The relative standard deviation obtained by 60 repetitive injections reached 1.48% at 2 g/L of NaCl. The method developed using the Au electrode without modification was used to analyze the chloride ion concentration in raw milk without preprocessing. The method showed good agreement with potentiometric titration.     

The Un(f)told Story of General Anesthesia

Inhalational anesthetics are routinely employed in clinical practice to accomplish general anesthesia. Concerns have recently emerged regarding the deleterious impact of these volatile agents on cognitive performance, immune functions, and tumor recurrence and metastasis. These agents have been shown to modify the gene‐expression pattern as well as cell signaling in tumor cells, but the underlying molecular mechanisms remain a matter of conjecture. Regulatory/signaling proteins either of cytosolic or membrane origin abundantly contain intrinsically disordered sequences, the conformational pliability of which is pivotal in their biological functions. It is well known that chloroform (an anesthetic itself), trifluoroethanol, hexafluoroisopropanol, and related haloalcohols markedly affect the structure of disordered proteins and protein regions by inducing folding, misfolding, or even aggregation. Taking into consideration the physicochemical similarities and protein interaction modes of these volatile solvents and inhaled anesthetics, it is postulated that administration of these drugs can also modify the secondary structure of disordered protein segments. Accordingly, pharmacological effects of anesthetics may, at least in part, be mediated by conformational perturbations of intrinsic disorder‐based regulatory protein networks of cells.     

Scandium recovery from raffinate copper leach solution as potential new source with ion exchange method

Raffinate copper leach solution of the Iran Sarcheshmeh copper complex has up to 3 mg/L scandium (Sc), which is significantly better than many existing sources, making it a possible source for the recovery of Sc using the ion exchange method. Visual Minteq software was employed to ascertain the ionic species likely to be formed under operational conditions in the mine and for selecting the suitable ion exchange resin. The cationic resin thus chosen was employed statically with ions-bearing synthesized solutions and statically/dynamically for actual copper mining raffinate solution. Room temperature and pH of 1.5 showed the highest Sc adsorption. The dynamic tests established the full saturation of the resin at 450 BV of the raffinate solution flow. Using sodium carbonate for elution, desorption of Sc, Y and Ce from the resin during static elution tests at constant duration was higher than that of Fe, Al and Cu. The results from the dynamic tests followed similar trends for the priority and the extent of the elution process. Desorption results from specimens of dynamic tests show a 60:1 concentration ratio leading to a 186 mg/L Sc-rich solution.     

A molecular model for ion dehydration in confined water

Although ion dehydration in confined water is ubiquitous in many important processes concerning ion adsorption, transport and separation, and so forth, few theoretical models have been developed to unravel the mechanism of dehydration in confined space. Herein, a molecular model is proposed by weighing the molecular orientation of surrounding water within the first hydration shell, and then this model is applied to predict the hydration numbers and hydrated radii of simple ions with the help of molecular density functional theory. The predictions are rationalized not only with parallel simulations but also with relevant experimental measurements. We find that the ion hydration in confined water is depressed owing to the confinement, and thus the multilayer hydration shell is disturbed, which results in the decline of hydration number and hydrated radius, favoring the ion dehydration. This work provides an insightful route toward the quantitative understanding and prediction of ion dehydration in confined water.