Assessment of rare earth elements variations in five water systems in Beijing: Distribution, geochemical features, and fractionation patterns.

This study investigates the distribution of rare earth elements (REEs) within the Beijing water system, specifically examining the Yongding, Chaobai, Beiyun, Jiyun, and Daqing rivers. Results indicate that the Beiyun River exhibits the highest REE concentrations, ranging from 35.95 to 59.78 µg/mL, while the Daqing River shows the lowest concentrations, ranging from 15.79 to 17.48 µg/mL. LREEs (La to Nd) predominate with a total concentration of 23.501 µg/mL, leading to a notable LREE/HREE ratio of 7.901. Positive Ce anomalies (0.70-1.11) and strong positive Eu anomalies (1.38-2.49) were observed. The study suggests that the Beijing water system's REEs may originate from geological and anthropogenic sources, such as mining and industrial activities in neighboring regions, including Inner Mongolia. These findings underscore the importance of ongoing monitoring and effective water management strategies to address REE-related environmental concerns.

Research progress on the content and distribution of rare earth elements in rivers and lakes in China.

This study reviewed the content and distribution of rare earth elements (REE) in rivers and lakes in China based on the online literature. The sequence distribution of REE presented the decreasing trends in the order: of Ce > La > Nd > Pr > Sm > Gb > Dy>Er > Yb > Eu > Lu > Ho > Tb > Tm in rivers water. Pearl River and the Jiulong River constitute a significant sediments REE reservoir with an average value mean of 229.6 mg/kg and 266.86 mg/kg, respectively; both have higher concentrations than the global river average (174.8 mg/kg) and higher than the local soil background (Chinese soil background). The Liaohe River is one of China's most polluted rivers, with REE distribution ranging from 106.61 to 174.71 g/L (average 144.59 g/L in water). The total concentrations of dissolved REE in rivers near REE mining areas in China are higher than in other rivers. Increasing anthropogenic inputs to natural systems may permanently alter the natural signatures of REE. The distribution characteristics of REE in Chinese lakes (sediments) varied greatly, and the mean enrichment factor (EF) was sorted as follows: Ce > La > Nd > Pr > Sm > Gd > Dy>Er > Yb > Eu > Ho > Tb > Tm > Lu, where Ce was the most abundant followed by La, Nd, and Pr, and these four elements account for 85.39 % of the total concentration of REE. The REE in the sediments obtained from Poyang Lake and Dongting Lake had an average concentration respectively of 254.0 µg/g and 197.95 µg/g; both are considerably higher than the average upper continental crust (146.4 µg/g) and higher than in other lakes in China and around the world. The distribution and accumulation of LREE in most lake sediments result from the joint action of human activities and natural processes. It concluded that mining tailings were the primary cause of REE pollution in sediments, and industrial and agricultural activities are mainly responsible for water contamination.

Preparation of pyrrolidinyl diglycolamide bonded silica particles and its rare earth separation properties.

The separation of rare earth elements by solid phase containing diglycolamide-type ligands is a hot topic. In this study, 2-[2-oxo-2-(1-pyrrolidinyl)ethoxy]acetic acid (PYRDGA) was synthesized and attached to the silica. The binding strength of SiO2@PYRDGA for rare earths showed a single increasing trend with the radius of rare earth atoms. IR and XPS spectra demonstrated that carbonyl oxygen and ether bond oxygen are binding sites for rare earth ions. SiO2@PYRDGA was used for the chromatographic separation of REEs, and the primary separation of 16 REEs was achieved at pH = 2.0 using HNO3 solution as the eluent, and La, Ce, Pr, Nd, Sm, and Eu reached the baseline separation level.

The stroke mechanism, clinical presentation, and radiological feature of bilateral medial medullary infarction.

BACKGROUND: Bilateral medial medullary infarction (BMMI) is a rare type of posterior circulation stroke. The aim of this study is to characterize its stroke mechanisms, clinical manifestations, neuroradiological features, and prognosis. METHODS: From January 2015 to June 2021, a retrospective review of 15 patients diagnosed with BMMI was conducted. The clinical and neuroradiological features were summarized by our experienced neurologists. RESULTS: Fifteen patients (12 male, 3 female), ranging in age from 48 to 72 years, satisfied the inclusion criteria. The common clinical presentations included motor weakness (100%), deep sensory disturbance (93.3%), vertigo/dizziness (80%), dysarthria (93.3%), and dysphagia (66.7%). Vertically, infarct lesions in the rostral medulla were observed in all included patients. Horizontally, "heart appearance," "Y appearance," and "fan appearance" infarcts occurred in 9 cases (60%), 5 cases (33.3%), and 1 (6.7%) case, respectively. Patients (53.3%) had severe stenosis or occlusion in unilateral vertebral artery (VA), and 33.3% had normal findings in the vertebrobasilar artery. Patients (93.3%) achieved poor prognosis. CONCLUSION: BMMI is more frequently located in the rostral medulla and comprises three forms of infarction. The two main stroke etiologies of BMMI are large-artery atherosclerosis (LAA) and small vessel disease (SVD). BMMI is always associated with bad clinical outcome.

Low temperature magnetic behavior and thermal expansion anomaly of cubic CeTiO3.

Lanthanum-based LnBO3 perovskite oxides have demonstrated fascinating magnetic properties and spin-lattice coupling. In this work, we report an unusual thermal expansion anomaly coupled with the magnetic ordering in the cubic CeTiO3 with the vacancy of Ce ions. The magnetic behaviors and lattice thermal expansion at low temperature were systematically investigated using the temperature dependence of the magnetization measurements and low temperature X-ray powder diffraction. It is clearly revealed that there are two magnetic transitions in the cubic CeTiO3 from 5 to 350 K: one is a magnetic ordering-disordering transition at 300 K and the other one might be a change of the magnetic component near 32 K. Both the magnetization and hysteresis change correspondingly upon cooling. Intriguingly, a lattice thermal expansion anomaly is found below the magnetic ordering temperature, which indicates a strong coupling of spin and lattice, i.e., a magnetovolume effect (MVE). Our findings provide the possibility of adjusting thermal expansion behavior and magnetic properties by introducing a vacancy of Ln atoms in lanthanum-based perovskite oxides.

Structure, thermostability and magnetic properties of cubic Ce2-x Ti2O7 pyrochlore obtained via sol-gel preparation.

Lanthanum-based titanates have been attracting considerable interest by virtue of their structural operability and hence diverse physical properties. The preparation of lanthanum-based titanates with novel crystal structure is a fascinating task. In this work, we report the preparation of a cubic Ce2-x Ti2O7 pyrochlore using the sol-gel method. The crystal structure, thermostability and magnetism were studied via the temperature dependence of X-ray powder diffraction, X-ray photoelectron spectroscopy and magnetization measurements. It has been revealed that the as-prepared Ce2-x Ti2O7 pyrochlore possesses a cubic symmetry (space group: Fd3̄m), however there is an 18(1)% vacancy of Ce ions in the as-prepared samples. No distinct phase transition and thermal expansion anomaly were observed in the investigated temperature range from 300 K to 700 K. Intriguingly, lattice defects may favor the transformation of Ce valence from +3 to +4 and an unusual weak magnetic ordering state emerged up to 400 K. The persistence of magnetism at such high temperatures is rare and mysterious for cerium titanates. Our findings provide the possibility of adjusting the crystal structure and magnetic properties of cerium titanates, anticipated to the development of lanthanum-based oxides.

Global Stability of a Mumps Transmission Model with Quarantine Measure.

In this paper, a model of mumps transmission with quarantine measure is proposed and then the control reproduction number ℛ c of the model is obtained. This model admits a unique endemic equilibrium P* if and only if R c > 1, while the disease-free equilibrium P 0 always exists. By using the technique of constructing Lyapunov functions and the generalized Lyapunov-LaSalle theorem, we first show that the equilibrium P 0 is globally asymptotically stable (GAS) if R c ≤ 1; second, we prove that the equilibrium P* is GAS if R c > 1. Our results reveal that mumps can be eliminated from the community for ℛ c ≤ 1 and it will be persistent for ℛ c > 1 , and quarantine measure can also effectively control the mumps transmission.

Selective extraction and column separation for 16 kinds of rare earth element ions by using N, N-dioctyl diglycolacid grafted silica gel particles as the stationary phase.

The selective extraction and column separation rear earth elements (REEs) were investigated in the present work. Herein, the functional ligand of N, N-dioctyldiglycolic acid (DODGA) was synthesized and chemically grafted on the silica gel (SG) particles to give the novel material SG@DODGA. The obtained SG@DODGA was fully characterized by NMR, BET (Brunauer-Emmett-Teller) N2 physisorption analysis, atom force microscopy (AFM), scanning electronic microscopy (SEM), Fourier transform infrared (FT-IR), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA). After investigating the adsorption capability of the SG@DODGA towards 16 kinds of REEs (La, Ce, Pr, Nd, Sm, Eu, Gd, Td, Dy, Ho, Er, Tm, Yb, Lu, Y and Sc), the results showed that the adsorption kinetic data was better fitted with pseudo-second-order model and Elovich model, the adsorption isotherms data was suitable for Freundlich model. The above result also indicated that the adsorption mechanism between the SG@DODGA and REEs was chemical ion exchange. Moreover, choose SG@DODGA as the column chromatography stationary phase and packed in a glass column for the column studies to obtain breakthroughs profile of each REEs. Furthermore, the column was used to try to separate the mixed 16 kinds of REEs. The first attempt to preliminary separate REEs result showed that this column could be applied for simply separating REEs. The light REEs La, Ce, Pr, Nd exhibited better separation effect than the other REEs.

Cell changes and differential proteomic analysis during biodegradation of decabromodiphenyl ether (BDE-209) by Pseudomonas aeruginosa.

Decabromodiphenyl ether (BDE-209) is a brominated flame retardant widely used in the world which, being an emerging persistent organic pollutant, poses a great potential hazard to both human health and the ecological environment. Microbial biodegradation has been considered as an effective and environment-friendly technique to remediate BDE-209. Pseudomonas aeruginosa, a Gram-negative bacterium capable of degrading BDE-209, was isolated from PBDEs-contaminated soil. To promote microbial biodegradation of BDE-209 and gain further insight into its mechanism, cell changes and differential proteomic analysis of P. aeruginosa during biodegradation were studied. The results showed that high cell surface hydrophobicity of P. aeruginosa make the bacteria absorb BDE-209 more easily. The increase in cell membrane permeability was caused by the P. aeruginosa responding to BDE-209 stress. IR spectra showed that hydroxyl, amide and CH2 groups in the P. aeruginosa cell surface were involved in the interactions between BDE-209 with P. aeruginosa. The apoptotic-like cell changes and cell surface morphology changes were observed by flow cytometry (FCM) and field emission scanning electron microscopy (FESEM), respectively. Differentially expressed protein was analysed by two-dimensional electrophoresis (2-DE) and 40 protein spots were identified to be different after 5 days biodegradation.

Differential study of DCE-MRI parameters in spinal metastatic tumors, brucellar spondylitis and spinal tuberculosis.

OBJECTIVE: In the present study, spinal metastatic tumors, brucellar spondylitis and spinal tuberculosis were quantitatively analyzed using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) to assess the value of DCE-MRI in the differential diagnosis of these diseases. METHODS: Patients with brucellar spondylitis, spinal tuberculosis or a spinal metastatic tumor (30 cases of each) received conventional MRI and DCE-MRI examination. The volume transfer constant (Ktrans), rate constant (Kep), extravascular extracellular volume fraction (Ve) and plasma volume fraction (Vp) of the diseased vertebral bodies were measured on the perfusion parameter map, and the differences in these parameters between the patients were compared. RESULTS: For pathological vertebrae in cases of spinal metastatic tumor, brucellar spondylitis and spinal tuberculosis, respectively, the Ktrans values (median ± quartile pitch) were 0.989±0.014, 0.720±0.011 and 0.317±0.005 min-1; the Kep values were 2.898±0.055, 1.327±0.017 and 0.748±0.006 min-1; the Ve values were 0.339±0.008, 0.542±0.013 and 0.428±0.018; the Vp values were 0.048±0.008, 0.035±0.004 and 0.028±0.009; the corresponding H values were 50.25 (for Ktrans), 52.47 (for Kep), 48.33 (for Ve) and 46.56 (for Vp), and all differences were statistically significant (two-sided P<0.05). CONCLUSIONS: The quantitative analysis of DCE-MRI has a certain value in the differential diagnosis of spinal metastatic tumor, brucellar spondylitis and spinal tuberculosis.