The ion-adsorption rare earth element (REE) deposit, a valuable type of REE deposit, has been thought to be derived from the release and enrichment of REE during granite weathering. Understanding the REE occurrence in regolith-hosted deposits is crucial for more eficient extraction. We investigated a weathering granite profile of a regolith-hosted REE deposit located in South China. X-ray difraction (XRD) and X-ray absorption near edge structure (XANES) analysis of the clay fractions reveal that the highest Ce(IV) content located in intensely weathered layers and cerianite nanoparticles (CeNPs) can be observed, besides invisible adsorbed REEs. Interestingly, most of the CeNPs scatter on halloysite basal surface and exhibit preferred orientation. Detailed analysis demonstrates that the diagonal plane of cerianite matches with the exposed basal surfaces (Si-O tetrahedron) of halloysite. Such a lattice match may contribute to the nucleation and growth of CeNPs after oxidation of the adsorbed Ce(III), which results in great REE enrichment by clays. The findings provide new insight into the mechanism of Ce precipitation and REE mineralization during granite weathering.

SUBJECTS:To assess whether anxiety is associated with a higher rise of blood pressure induced by cuff inflation.METHODS:At first, intro-aortic blood pressure was continuously record before cuff inflation as baseline value in 234 patients underwent coronary angiography, then the cuff was inflated to 200 mmHg and the intro-aortic blood pressure was record again as cuff inflation blood pressure. According to anxiety score, the patients were divided into anxiety group, subanxiety group, and nonanxiety group. The difference between the baseline blood pressure and the cuff inflation blood pressure was calculated as cuff inflation-induced blood pressure elevation. When the difference ≥10 mmHg, cuff inflation-induced blood pressure elevation was diagnosed.RESULTS:The cuff inflation systolic blood pressure (134.9 ± 22.4 versus 131.6 ± 22.3  mmHg, P < 0.01) and diastolic blood pressure (80.5 ± 11.9 versus 78.4 ± 11.6 mmHg, P < 0.01) were significantly higher than the baseline values, thus the mean cuff inflation-induced blood pressure elevation on systolic blood pressure was 3.3 ± 4.7 mmHg and that on diastolic blood pressure was 2.1 ± 4.9 mmHg. The anxiety subgroup had significantly higher percentage increase-systolic blood pressure and percentage increase-diastolic blood pressure levels (4.5 ± 3.1% and 5.6 ± 6.3%) than the nonanxiety subgroup (1.9 ± 3.3% and 2.0 ± 6.5%), meanwhile these values in the subanxiety subgroup were higher (3.2 ± 4.1% and 3.4 ± 5.7%) than the nonanxiety subgroup.CONCLUSION:Cuff inflation can induce a transient rise of intro-aortic blood pressure. Anxiety is associated with higher cuff inflation-induced blood pressure elevation.

Abstract Hydroxyapatite (HAp) has been widely used to remove cadmium (Cd) in contaminated water and soils via Cd-Ca substitution. The Cd incorporation into HAp afects its structure; however, the detailed mechanism remains unclear. In this study, a series of Cd-substituted hydroxyapatites were synthesized and characterized with various techniques. Cd incorporation causes a decrease in a- and c-lattice parameters due to the radius of Cd2+ being slightly smaller than that of Ca2+. As the Cd content increases, the particle sizes of the synthesized samples decrease and their specific surface areas increase. Raman bands shift linearly and the ν1(PO4) peak at 961 cm−1 becomes broadened with increasing Cd content. Change in X‑ray absorption near edge structure (XANES) spectra of the P K-edge indicates distortion of phosphate with Cd incorporation. Total electron yield (TEY) spectra of the Ca L2,3-edge show a decrease in the octahedral symmetry, suggesting preferential occupancy of Cd over the Ca2 site. Extended X‑ray absorption fine structure (EXAFS) analysis of the Ca K-edge reveals no obvious change in the local environment of Ca induced by Cd incorporation. However, EXAFS analysis of the Cd K-edge indicates that the substituted Cd occupies one Ca2 site in hexagonal Ca2 positions at low-Cd contents [<10 mol% of Cd/(Cd+Ca)], while both Ca1 and Ca2 sites are occupied at higher Cd contents. This study provides atomistic insight into the mechanism for Cd incorporation in HAp, which will help develop an approach for effective Cd removal using HAp for environmental remediation.

Abstract Goethite and modified goethites have been found as good photocatalysts because their conduction band can mediate electron transfer in various redox processes. Many kinds of metal elements can be incorporated into the structure of goethite to form solid solutions in nature, but their optoelectronic properties have not been well disclosed. Mn-substituted goethite is one of the potential photocatalysts, which can exhibit high-photocatalytic activity in many Earth’s surface processes. Based on the first-principles calculation, pairwise interaction energies and static lattice energies of goethitegroutite solid solution were computed, and the most thermodynamically stable configurations of Mn-substituted goethite were determined. The results indicate that Mn3+ ion tends to distribute within the cation layer parallel to the (001) plane. Phase relations of goethite-groutite solid solution were derived by subsequent configurational statistics with energies of all 232 configurations of a 2 × 1 × 4 supercell with 32 exchangeable cations. The phase diagram shows that no more than 3 mol% Fe of goethite can be substituted by Mn ions. Therefore, Mn-substituted goethite is thermodynamically metastable or bears groutite-like clusters/lamellae. Furthermore, the effects of Mn substitutions on the band gap were experimentally and theoretically investigated. It is found that a small amount of Mn-substitution can reduce the band gap of goethite significantly, and the decrease ceases when the Mn content is higher than 3–4 mol%. Such a decrease in band gap causes red-shift to the photo response wavelength of goethite and improves the responding capability. This improvement was confirmed in the experiments of photocatalytic degradation of methylene blue (MB). Such kind of photocatalytic reaction probably can happen widely in natural environments. Therefore, the contribution of photocatalysis of natural goethites to geochemical processes on Earth’s surface should be considered.

A growing body of research showed that diet management, such as promoting protein and vitamin intake and food restriction play a crucial role in extending time to morbidity and mortality in patients undergoing hemodialysis. However, the current dietary recommendations in nutrition guidelines lack examination of cultural factors. The study aimed to understand the diet influenced by culture in Chinese patients undergoing hemodialysis. Semi-structured interviews were conducted for 23 patients, aged 23-75 years, undergoing hemodialysis in a local tertiary hospital. Interview questions mainly focused on patients' real experience about diet, and their perceptions and attitudes toward diet. Each interview was digitally recorded, and conventional content analysis was used to attain information. The majority of patients reserved Chinese traditional dietary habits about salt and calcium intake. Although Chinese herbal medicine was not consumed, dietary therapy including brown sugar and dates was included in the participants' diet. Eggs, broth, and seafood were three prominent preferences and taboos profoundly impacted by culture. Additionally, Chinese social culture influenced patients' dietary behavior of eating at home and knowledge attainment. Diet in Chinese patients undergoing hemodialysis was still strongly influenced by culture. Culturally sensitive interventions regarding the improvement of diet intake are urgently needed.

目的 探索机器学习算法在预测大学生是否存在自杀意念中的效果,并分析大学生自杀意念的危险因素.方法 选取某高校2021年21 224名在校本科生心理数据.以37项人口学和内外在心理因素为自变量,以大学生是否存在自杀意念为因变量,使用支持向量机、随机森林和LightGBM算法分别建立预测模型.将模型应用于测试集上,以检出率、F1分数和准确率评价预测效果.基于较优模型分析大学生自杀意念的高风险因素.结果 支持向量机、随机森林和LightGBM模型的检出率依次为0.61,0.64,0.69;F1分数依次为0.63,0.63,0.64;准确率依次为0.73,0.73,0.72.基于较优的LightGBM模型分析大学生自杀意念高风险因素,按照重要性排序依次为抑郁、年级、性别、绝望、生源地、拥有意义感、对自杀的态度、依赖、家庭经济情况、幻觉妄想症状、焦虑、网络成瘾和人际关系困扰.结论 LightGBM模型预测大学生是否存在自杀意念相较于支持向量机和随机森林模型有较好的预测效果.

Accumulation of arsenic (As) and cadmium (Cd) in wheat grain is a serious threat to human health. Sulfur (S) can simultaneously decrease wheat grain As and Cd concentrations by decreasing their translocation in wheat; however, the mechanisms are unclear. We conducted hydroponic experiments to explore the mechanisms by which S modulates As and Cd translocation and their toxicity in wheat. Wheat seedlings were grown in deficient sulfate (2.5 µM) or sufficient sulfate (1.0 mM) nutrient solutions for 6 days and then exposed to zero (control), low As+Cd (1 µM As plus 0.5 µM Cd), or high As+Cd (50 µM As plus 30 µM Cd) for another 6 days. Compared with the control, plant growth was not affected by low As+Cd, but was significantly inhibited by high As+Cd. In the low As+Cd treatment, S supply had no significant effect on plant growth or root-to-shoot As and Cd translocation. In the high As+Cd treatment, sufficient S supply significantly alleviated As and Cd toxicity and their translocation by increasing phytochelatin (PC) synthesis and the subsequent vacuolar sequestration of As and Cd in roots, compared with deficient S supply. The use of L-buthionine sulfoximine (a specific inhibitor of γ-glutamylcysteine synthetase) confirmed that the alleviation of As and Cd translocation and toxicity in wheat by S is mediated by increased PC production. Also, TaHMA3 gene expression in wheat root was not affected by the As+Cd and S treatments, but the expression of TaABCC1 was upregulated by the high As+Cd treatment and further increased by sufficient S supply and high As+Cd treatment. These results indicate that S-induced As and Cd subcellular changes affect As and Cd translocation mainly by regulating thiol metabolism and ABCC1 expression in wheat under As and Cd stress.

近年来,体裁理论和体裁教学在英语写作教学中愈发受到关注.本文基于Swales和Bhatia的体裁理论,考察了体裁教学法在研究生学术英语写作课堂中的具体实施方式,聚焦于其对研究生体裁能力培养的促进作用,以期为学术英语写作教学提供借鉴.研究发现:在学术写作教学中对学术语篇进行体裁分析,一方面有助于学生掌握学术论文微观语言形式表征,提高学生遣词造句的能力;另一方面能揭示学术论文惯例和规约以及隐藏在其背后的建构理据,培养学生的体裁能力.

Recent studies have shown that surfaces rich in functional groups can facilitate nucleation of low-temperature (low-T) dolomite. However, to date few experiments have investigated the details of the nucleation mechanisms nor determined how naturally occurring substances influence crystallization pathways of low-T dolomite. In this study we isolated and characterized extracellular polymers (EPS) from a hypersaline sabkha, as well as clay standards and performed mineralization experiments with these surfaces as seed material. Mineralization experiments were carried out in batch reactors in a solution supersaturated with respect to dolomite. Our results showed that over a five-month period the rate of low-t dolomite formation in samples seeded with EPS was significantly higher compared to those seeded with clay. The observed rates were also shorter than previously published experiments using bacterial cultures (e.g., Kenward et al., 2013, Deng et al., 2019). Precipitates from samples seeded with EPS show crystallization of dolomite pre-cursors after several days and assemblages of dolomite crystals from 10-days forward [Figure 1]. Measurements from EPS seeded samples showed significant depletion of Ca and Mg in solution within one week as well as elevated alkalinity that coincided with dolomite crystallization. Samples seeded with clay and control samples without seed materials showed little and no dolomite crystallization, respectively, during the same time-frame. Overall, the results of this work shows that EPS isolated from microbial mats are preferential nucleation surfaces for carbonate precipitation when compared to clays. Additionally, the findings reveal that the properties of nucleation surfaces such as functional group type and concentration are a key factor driving low-T dolomite precipitation. Figure 1: Dolomite like phases and representative EDS spectra from a solution seeded with EPS. References: Kenward PA, Fowle DA, Goldstein RH, Ueshima M, González LA, Roberts JA. Ordered low-temperature dolomite mediated by carboxyl-group density of microbial cell walls. AAPG bulletin. 2013 Nov 1;97(11):2113-25. Liu D, Xu Y, Papineau D, Yu N, Fan Q, Qiu X, Wang H. Experimental evidence for abiotic formation of low-temperature proto-dolomite facilitated by clay minerals. Geochimica et Cosmochimica Acta. 2019 Feb 15;247:83-95.

基于黄原胶/溶菌酶纳米凝胶(XG/Ly NPs)颗粒稳定剂,考察其稳定的乳液(Pickering乳液)对结晶紫的吸附行为,并建立吸附机理模型.结果表明:不同能量输入制备的Pickering乳液下层水相的透明度不尽相同,涡旋法制备Pickering乳液的透光率与XG/Ly NPs透光率规律一致,即pH越低透光率越低;但均质法制备乳液下相透光率较高,说明能量输入改变了XG/Ly NPs在界面的组装行为,涡旋制备的乳液结晶紫吸附量随着其浓度的提高逐渐提高,当结晶紫浓度为2.5～20 mg/L时,在10 mg/L时达到饱和吸附量,对结晶紫吸附率可达到90％;均质制备的Pickering乳液吸附能力均高于涡旋制备的乳液,在试验浓度范围内吸附率可达到105％.

“行为经济学之父”Richard Thaler因在行为经济学领域的突出贡献而获2017年诺贝尔经济学奖.Thaler利用行为经济学原理提出了“明日多储蓄”项目,助推美国养老金储蓄率的提高.在初涉养老金储蓄领域时,Thaler提出采取“自动加入”的方式提高员工养老储蓄参与率;接着提出采取“自动升级”的方式提高员工的储蓄率,最终形成了“明日多储蓄”项目.“明日多储蓄”项目具有自由家长主义性质,不仅能提高员工养老储蓄参与率、储蓄率,还能优化资产投资配置.该项目产生了深远的影响:在应用层面上,英国、新西兰等国家跟进推出了类似的养老储蓄政策;在研究层面上,一批后继研究者受此启发展开了个体养老金储蓄行为背后心理学机制的探索.结合中国养老储蓄三大支柱发展不平衡的现状,我们提出可利用框架效应、心理账户、默认选项、将损失程数由双程变为单程等行为经济学手段助推中国养老储蓄的发展.国家可以考虑通过制度设计和政策制定助推全社会养老金参与率和缴纳水平的提高.

为探讨东北地区(黑龙江省、吉林省和辽宁省)稻田养殖河蟹的微量元素含量水平和食用安全性,于2017年9月在东北主要养殖区采集稻田养殖河蟹56份,利用电感耦合等离子体质谱法(ICP-MS)检测了河蟹体内18种微量元素的含量,并采用单因子污染指数(Pi)和每周可耐受摄入量(PTWI)、目标危害商值(THQ)法分别评价了其污染程度和食用安全性.结果表明:河蟹中检出的大多数微量元素含量远高于该地区池塘养殖的淡水鱼类;吉林省河蟹体内的Cr、Cd、U等10种微量元素含量与其他两省份相比存在显著性差异(P＜0.05);所有样品的Cu、Pb、Cd和Cr含量均未超出国家食品安全标准;5种重金属(Cu、Zn、Pb、Cd和Cr)的成人每周实际摄入量(AWI)低于食品添加剂联合专家委员会(JECFA)推荐的每周可耐受摄入量;5种重金属和其他4种有害微量元素(Ba、U、Ag和Be)的人体每日摄入量(EDI)低于美国环保署(USEPA)推荐的参考剂量(RfD).研究表明食用东北稻田养殖河蟹摄人的微量元素对食用人群没有明显的健康风险.在检测的18种微量元素中,Ba、Pb和Cd对复合污染物风险指数(HI)贡献率较高,是主要的风险元素.

Preferential enrichment of arsenic in iron oxides relative to manganese oxides has been well documented. In this study, however, a distinct arsenic enrichment is revealed in natural ferromanganese duricrusts, which are commonly found in natural weathering profiles of manganese-bearing carbonate rocks. In the studied ferromanganese duricrust covering Carboniferous carbonates at Qixia Mountain in eastern China, stromotalite-like structures composed by hematite, goethite, pyrolusite and hetaerolite have been observed. Electron microprobe analysis (EMPA) mapping and synchrotron-based microscanning X-ray fluorescence (m-XRF) analyses reveal that the arsenic content in manganese oxides is elevated with respect to iron oxide phases. For example, the arsenic content of pyrolusite is approximately 5 times as much as that of hematite or hetaerolite. However, the highest arsenic content (0.58 wt % As2O5) occurs in 2.75 (+/- 0.96, +/-sigma) mm micro-bands of hematite ((FexMn1-xIII)(2)O-3, 0.75 < x < 0.83). Although arsenic contents in the Mn-rich hematite micro-bands are extraordinarily high, the amount of hematite with a high Mn content is very low in the duricrust. Hence manganese oxides are suggested to be the major arsenic sink in the ferromanganese duricrust. Extended X-ray absorption fine structure spectra (EXAFS) further shows that all arsenic is present as oxidized As(V) and are bound to Fe/Mn oxides in bidentate binuclear bridging complexes with As-Fe and As-Mn bond distances of 3.24 angstrom and 3.23 angstrom, respectively. In addition, it is found that zinc is also more enriched in Mn oxides (besides hetaerolite) than in Fe oxides. The fine hematite crust with low contents of heavy metals could act as a protective seal to separate Mn oxides core with high Zn and As from environmental fluids. This separation could reduce the interaction between them and decrease the release of Zn and As from this ferromanganese duricrusts, which ensures long-term sequestration of heavy metals. The unique structural and mineralogical constraints on the distribution of heavy metals can provide insights into novel strategies for environmental remediation of heavy metals contaminations. (C) 2016 Elsevier Ltd. All rights reserved.

A nanoscale Fe(ii)-bipyridinedicarboxylate based MOF material was used as heterogeneous Fenton catalyst with high activity, stability and H2O2 utilization efficiency.

The formation and dissolution of arsenic minerals commonly controls the mobility of As in sulfide mines. Here, we present the results of research based on X-ray powder diffraction (XRD), Raman microprobe spectrum, scanning electron microscope (SEM), and transmission electron microscope (TEM) analyses, Scanning transmission X-ray microscope (STXM) and X-ray absorption fine structure (XAFS) analyses to further understand the weathering of orpiment- and realgar-bearing tailings from the Shimen realgar deposit, the largest realgar deposit in Asia. These analyses indicate that four different types of As-bearing secondary minerals are present in the tailings, including arsenic oxides, arsenates, As-gypsum, and As–Fe minerals, and that arsenic in the tailings is present in +3 and +5 valence states. The precipitation of arsenates is attributed to the interaction between As-enriched run-off waters and carbonate minerals. The Ca-arsenates in the tailings are dominantly weilite and pharmacolite, both of which have Ca/As atomic ratios of 1. In addition, SO 4 2− /HAsO 4 2− substitution in gypsum is another important mechanism of arsenic precipitation.

Jarosite is a common mineral in a variety of environments formed by the oxidation of iron sulfide normally accompanying with the generation of acid mine drainage (AMD) in mining areas or acid rock drainages (ARD) in many localities. Decomposition of jarosite by dissimilatory iron reducing bacteria (DIRB) influences the mobility of many heavy metals generally accommodated in natural jarosite. This study examined the anaerobic reduction of synthesized jarosite by Shewanella oneidensis strain MR-1, a typical facultative bacteria. The release of ferrous and ferric ion, as well as sulfate and potassium, in the inoculated experimental group lasting 80 days is much higher than that in abiotic control groups. The detection of bicarbonate and acetate in experimental solution further confirms the mechanism of microbial reduction of jarosite, in which lactate acts as the electron donor. The produced ferrous iron stimulates the subsequent secondary mineralization, leading to precipitation and transformation of various iron-containing minerals. Green rust and goethite are the intermediate minerals of the microbial reduction process under anoxic conditions, and the end products include magnetite and siderite. In aerobic environments, goethite, magnetite and siderite were also detected, but the contents were relatively lower. While in abiotic experiments, only goethite has been detected as a product. Thus, the microbial reduction and subsequent mineral transformation can remarkably influence the geochemical cycling of iron and sulfur in supergene environments, as well as the mobility of heavy metals commonly accommodated in jarosite. (C) 2013 Elsevier Ltd. All rights reserved.

In supergene environments, microbial activities significantly enhance sulfide oxidation and result in the release of heavy metals, causing serious contamination of soils and waters. As the most commonly encountered arsenic mineral in nature, arsenopyrite (FeAsS) accounts for arsenic contaminants in various environments. In order to investigate the geochemical behavior of arsenic during microbial oxidation of arsenopyrite, (230) surfaces of arsenopyrite slices were characterized after acidic (pH 2.00) and oxidative decomposition with or without an acidophilic microorganism Acidithiobacillus ferrooxidans. The morphology as well as chemical and elemental depth profiles of the oxidized arsenopyrite surface were investigated by scanning electron microscopy and X-ray photoelectron spectroscopy. With the mediation of bacteria, cell-shaped and acicular pits were observed on the reacted arsenopyrite surface, and the concentration of released arsenic species in solution was 50 times as high as that of the abiotic reaction after 10 days reaction. Fine-scale XPS depth profiles of the reacted arsenopyrite surfaces after both microbial and abiotic oxidation provided insights into the changes in chemical states of the elements in arsenopyrite surface layers. Within the 450 nm surface layer of abiotically oxidized arsenopyrite, Fe(III)-oxides appeared and gradually increased towards the surface, and detectable sulfite and monovalent arsenic appeared above 50 nm. In comparison, higher contents of ferric sulfate, sulfite, and arsenite were found in the surface layer of approximately 3 mu m of the microbially oxidized arsenopyrite. Intermediates, such as Fe(III)-AsS and S-0, were detectable in the presence of bacteria. Changes of oxidative species derived from XPS depth profiles show the oxidation sequence is Fe > As = S in abiotic oxidation, and Fe > S > As in microbial oxidation. Based on these results, a possible reaction path of microbial oxidation was proposed in a concept model. (C) 2013 Elsevier Ltd. All rights reserved.

Schwertmannite is a common micro-nano-sized mineral in the supergene environment.This mineral as an important environmental indicator has a potential remediation of heavy metal contamination.Some products from treating with dialyzing and ageing process of schwertmannite synthesized from the system of FeCl3 6H2O and Na2SO4 were analyzed.The results reveal that dialyzing improves the structural stability,and has a positive effect on the micro-morphology.The specific surface area increased during the dialyzing process.In the ageing process,schwertmannite was transformed to natrojarosite progressively.In the Fourier transform infrared spectra,two peaks at 1 010 and 1 025 cm–1 appeared due to the vibration of δ(OH),and Na+ was captured into the crystal lattice,resulting in a little drift of ν3(SO42–).