Pollution revealed by stable lead isotopes in recent snow from the northern and central Tibetan Plateau.

Lead (Pb) isotopes are less fractionated than those from different sources, and thus were used to trace the sources of Pb in the environment. To investigate the sources of Pb in the atmosphere of the Tibetan Plateau, stable Pb isotopes (206Pb, 207Pb and 208Pb) in acidified snow pit samples collected from five glaciers (i.e., Qiyi-QY, Meikuang-MK, Yuzhufeng-YZF, Hariqin-HRQ and Xiaodongkemadi-XDKMD) in May 2016 of the northern and central Tibetan Plateau were measured. The results showed narrow ranges of 1.158-1.187 for 206Pb/207Pb and 2.450-2.489 for 208Pb/207Pb respectively. The 206Pb/207Pb ratios in all samples were obviously lower than the environmental background value of 1.196, indicating the primary contributions of anthropogenic sources. At least 60% of Pb was contributed by various human activities, which was supported by the Pb isotopes in the snow pit samples from the QY, MK, YZF, HRQ and XDKMD glaciers. By comparing Pb isotope data, we found that the primary anthropogenic sources are coal combustion, mining and smelting activities in northwestern China and mixed emissions from cities located in western China and close to the glaciers. These sources contributed to the Pb in the northern glaciers (QY and MK) in particular. Coal combustion in India probably contributes to the central glaciers (HRQ and XDKMD). Another potential source could be parts of central Asia (e.g., Kyrgyzstan and Uzbekistan) through long range transport. The above potential source areas of contaminants were traced further by the air mass back-trajectory tracing method.

Whole body hypoxic preconditioning-mediated multiorgan protection in db/db mice via nitric oxide-BDNF-GSK-3ß-Nrf2 signaling pathway.

The beneficial effects of hypoxic preconditioning are abolished in the diabetes. The present study was designed to investigate the protective effects and mechanisms of repeated episodes of whole body hypoxic preconditioning (WBHP) in db/db mice. The protective effects of preconditioning were explored on diabetesinduced vascular dysfunction, cognitive impairment and ischemia-reperfusion (IR)-induced increase in myocardial injury. Sixteen-week old db/db (diabetic) and C57BL/6 (non-diabetic) mice were employed. There was a significant impairment in cognitive function (Morris Water Maze test), endothelial function (acetylcholineinduced relaxation in aortic rings) and a significant increase in IR-induced heart injury (Langendorff apparatus) in db/db mice. WBHP stimulus was given by exposing mice to four alternate cycles of low (8%) and normal air O2 for 10 min each. A single episode of WBHP failed to produce protection; however, two and three episodes of WBHP significantly produced beneficial effects on the heart, brain and blood vessels. There was a significant increase in the levels of brain-derived neurotrophic factor (BDNF) and nitric oxide (NO) in response to 3 episodes of WBHP. Moreover, pretreatment with the BDNF receptor, TrkB antagonist (ANA-12) and NO synthase inhibitor (LNAME) attenuated the protective effects imparted by three episodes of WBHP. These pharmacological agents abolished WBHP-induced restoration of p-GSK-3ß/GSK-3ß ratio and Nrf2 levels in IR-subjected hearts. It is concluded that repeated episodes of WHBP attenuate cognitive impairment, vascular dysfunction and enhancement in IRinduced myocardial injury in diabetic mice be due to increase in NO and BDNF levels that may eventually activate GSK-3ß and Nrf2 signaling pathway to confer protection.

Salmonella Typhimurium and Salmonella Enteritidis Infections in Sporadic Diarrhea in Children: Source Tracing and Resistance to Third-Generation Cephalosporins and Ciprofloxacin.

OBJECTIVES: This study aimed to trace the transmission source of Salmonella enterica serovar Typhimurium and Salmonella enterica serovar Enteritidis strains associated with enteric infections in Shanghainese children, and understand the molecular mechanism of resistance to third-generation cephalosporins and ciprofloxacin. MATERIALS AND METHODS: The profiles of pulsed-field gel electrophoresis (PFGE) were compared among the isolates from children, animal, and environment. Antimicrobial susceptibility was determined using the minimal inhibitory concentrations and Kirby-Bauer disk diffusion method. Extended-spectrum ß-lactamase (ESBL) producing isolates mediated by resistance genes were identified using polymerase chain reaction and sequencing. RESULTS: Based on PFGE patterns, 49 (33.1%) of 148 human Salmonella Typhimurium isolates located in the dominant PFGE clusters were genetically related to the isolates from poultry source, environment water, aquatic products, and reptiles, whereas 97 (97.0%) of 100 human Salmonella Enteritidis isolates were genetically related to isolates from poultry and water. The rates of resistance to ceftriaxone among clinical Salmonella Typhimurium and Salmonella Enteritidis isolates were 42.0% and 14.2%, respectively. Besides, 35.1% of Salmonella Typhimurium isolates displayed resistance to ciprofloxacin; 64.9% of Salmonella Typhimurium isolates and 97.0% of Salmonella Enteritidis isolates displayed reduced susceptibility to ciprofloxacin. Of 64 ESBL/AmpC-producing strains, CTX-M, TEM, DHA, and CMY were detected at frequencies of 86.0%, 62.5%, 7.8%, 3.1%, and 3.1%, respectively. CONCLUSIONS: The transmission sources of Salmonella Typhimurium and Salmonella Enteritidis infections in Shanghainese children were diverse. The high prevalence of resistance to third-generation cephalosporins and ciprofloxacin mediated by multiple molecular mechanisms needs continuous monitoring and intervention.

The p38-interacting protein (p38IP) regulates G2/M progression by promoting α-tubulin acetylation via inhibiting ubiquitination-induced degradation of the acetyltransferase GCN5.

p38-interacting protein (p38IP) is a component of the GCN5 histone acetyltransferase-containing coactivator complex (GCN5-SAGA complex). It remains unclear whether p38IP or GCN5-SAGA is involved in cell cycle regulation. Using RNA interference to knock down p38IP, we observed that cells were arrested at the G2/M phase, exhibiting accumulation of cyclins, shrunken spindles, and hypoacetylation of α-tubulin. Further analysis revealed that knockdown of p38IP led to proteasome-dependent degradation of GCN5. GCN5 associated with and acetylated α-tubulin, and recovering GCN5 protein levels in p38IP knockdown cells by ectopic expression of GCN5 efficiently reversed α-tubulin hypoacetylation and G2/M arrest. During the G2/M transition, the association of α-tubulin with GCN5 increased, and the acetylation of α-tubulin reached a peak. Biochemical analyses demonstrated that the interaction between p38IP and GCN5 depended on the p38IP N terminus (1-381 amino acids) and GCN5 histone acetyltransferase domain and bromodomain. The p38IP N terminus could effectively reverse p38IP depletion-induced GCN5 degradation, thus recovering α-tubulin acetylation and G2/M progression. p38IP-mediated suppression of GCN5 ubiquitination most likely occurs via nuclear sequestration of GCN5. Our data indicate that the GCN5-SAGA complex is required for G2/M progression, mainly because p38IP promotes the acetylation of α-tubulin by preventing the degradation of GCN5, in turn facilitating the formation of the mitotic spindle.

Nontyphoidal salmonella infection in children with acute gastroenteritis: prevalence, serotypes, and antimicrobial resistance in Shanghai, China.

Information about nontyphoidal Salmonella (NTS) infection in children is limited in mainland China. The objective of this study was to investigate the prevalence, serotypes, and antibiotic resistance patterns of NTS infection in children in Shanghai. All cases with probable bacterial diarrhea were enrolled from the enteric clinic of a tertiary pediatric hospital between July 2010 and December 2011. Salmonella isolation, serotyping, and antimicrobial susceptibility testing were conducted by the microbiological laboratory. NTS were recovered from 316 (17.2%) of 1833 cases with isolation rate exceeding Campylobacter (7.1%) and Shigella (5.7%). NTS infection was prevalent year-round with a seasonal peak during summer and autumn. The median age of children with NTS gastroenteritis was 18 months. Fever and blood-in-stool were reported in 52.5% and 42.7% of cases, respectively. Salmonella Enteritidis (38.9%) and Salmonella Typhimurium (29.7%) were the most common serovars. Antimicrobial susceptibility showed 60.5% of isolates resistant to ≥1 clinically important antibiotics. Resistance to ciprofloxacin and the third-generation cephalosporins was detected in 5.5% and 7.1%-11.7% of isolates, respectively. NTS is a major enteropathogen responsible for bacterial gastroenteritis in children in Shanghai. Resistance to the current first-line antibiotics is of concern. Ongoing surveillance for NTS infection and antibiotic resistance is needed to control this pathogen in Shanghai.

Repetitive transcranial magnetic stimulation impacts the executive function of patients with vascular cognitive impairment: a systematic review and meta-analysis.

Objective: Executive dysfunction is a core symptom of vascular cognitive impairment (VCI), which seriously affects patients' prognosis. This paper aims to investigate the effectiveness of rTMS on executive function in VCI. Methods: The databases selected for this study included Pubmed, Embase, Cochrane Library, China National Knowledge Infrastructure (CNKI), Wanfang, China Science and Technology Journal Database (VIP), and China Biology Medicine Disc (CBM). The screening times were conducted from the time of library construction until August 23, 2023. The inclusion criteria for this meta-analysis were randomized controlled trials (RCTs) on rTMS for VCI, which include executive function scores. The primary metrics were executive subscale scores of the Cognitive Comprehensive Scale and total scores of the Executive Specificity Scale. The secondary metrics were subscale scores of the Executive Specificity Scale. The quality of each eligible study was assessed using the Cochrane Risk of Bias tool. Meta-analysis and bias analysis were performed using Stata (version 16.0) and RevMan (version 5.3). Results: A total of 20 high-quality clinical RCTs with 1,049 samples were included in this paper. The findings from the primary outcomes revealed that within the rTMS group, there were significantly higher scores observed for the executive sub-item on the cognitive composite scale (SMD = 0.93, 95% CI = 0.77-1.08, p < 0.00001, I 2 = 14%) and the total score on the executive specific scale (SMD = 0.69, 95% CI = 0.44-0.94, p < 0.00001, I 2 = 0%) compared to the control group. As for the secondary outcome measures, as shown by the Trail Making Test-A (time) (MD = -35.75, 95% CI = -68.37 to -3.12, p = 0.03, I 2 = 55%), the Stroop-C card (time) (SMD = -0.46, 95% CI = -0.86 to -0.06, p = 0.02, I 2 = 0%) and the Stroop-C card (correct number) (SMD = 0.49, 95% CI = 0.04-0.94, p = 0.03, I 2 = 0%), the experimental group shorts time and enhances accuracy of executive task in comparison to the control group. Subgroup analysis of the main outcome demonstrated that intermittent theta burst stimulation (iTBS), higher frequency, lower intensity, longer duration, and combined comprehensive therapy exhibited superior efficacy. Conclusion: rTMS is effective in the treatment of the executive function of VCI. The present study has some limitations, so multi-center, large-sample, objective indicators and parameters are needed to further explore in the future.Systematic review registration:https://www.crd.york.ac.uk/prospero/, CRD42023459669.

Characterization of Potting Epoxy Resins Performance Parameters Based on a Viscoelastic Constitutive Model.

To describe the evolution of residual stresses in epoxy resin during the curing process, a more detailed characterization of its viscoelastic properties is necessary. In this study, we have devised a simplified apparatus for assessing the viscoelastic properties of epoxy resin. This apparatus employs a confining cylinder to restrict the circumferential and radial deformations of the material. Following the application of load by the testing machine, the epoxy resin sample gradually reduces the gap between its surface and the inner wall of the confining cylinder, ultimately achieving full contact and establishing a continuous interface. By recording the circumferential stress-strain on the outer surface of the confining cylinder, we can deduce the variations in material bulk and shear moduli with time. This characterization spans eight temperature points surrounding the glass transition temperature, revealing the bulk and shear relaxation moduli of the epoxy resin. Throughout the experiments, the epoxy resin's viscoelastic response demonstrated a pronounced time-temperature dependency. Below the glass transition temperature, the stress relaxation response progressively accelerated with increasing temperature, while beyond the glass transition temperature, the stress relaxation time underwent a substantial reduction. By applying the time-temperature superposition principle, it is possible to construct the relaxation master curves for the bulk and shear moduli of the epoxy resin. By fitting the data, we can obtain expressions for the constitutive model describing the viscoelastic behavior of the epoxy resin. In order to validate the reliability of the test results, a uniaxial tensile relaxation test was conducted on the epoxy resin casting body. The results show good agreement between the obtained uniaxial relaxation modulus curves and those derived from the bulk and shear relaxation modulus equations, confirming the validity of both the device design and the testing methodology.

The varying clinical effectiveness of single, three and five intraarticular injections of platelet-rich plasma in knee osteoarthritis.

OBJECTIVE: To investigate the variations in clinical effectiveness among patients diagnosed with knee osteoarthritis who underwent intra-articular administration of platelet-rich plasma using single, triple, or quintuple injections. METHODS: One hundred twenty patients with grade I-III knee osteoarthritis were randomly assigned to three groups: PRP1 group, who received a single injection of platelet-rich plasma; PRP3 group, who received three PRP injections one week apart; PRP5 group, who received five PRP injections one week apart. The patients' conditions were evaluated using the Visual Analogue Scale (VAS) and the Western Ontario and McMaster Universities Arthritis Index-VA3.1 version (WOMAC-VA3.1) at baseline and 6, 12, 24, and 52 weeks 52 weeks follow up. RESULTS: Out of the total participants, 106 patients (30 males and 76 females) completed the study. The primary outcome measure, WOMAC pain score, registered significant improvements across all groups when compared to pre-treatment levels. However, the application of 3 and 5 injections of platelet-rich plasma was substantially more effective than that of a single injection in reducing knee pain and stiffness, as well as enhancing physical function in patients with knee osteoarthritis. No statistically discernable difference was observed between PRP3 and PRP5 at all follow-up intervals, and there was no discernable difference between 3 and 5 PRP injections either. Mild side effects occurred in all three groups. CONCLUSIONS: The administration of three or five injections of platelet-rich plasma is safe, substantially more effective than single injections, and leads to remarkable clinical improvement by significantly reducing knee pain, improving joint stiffness, and enhancing physical function in patients with grade I-III knee osteoarthritis. Furthermore, no significant difference was observed in the efficacy of three or five injections. Therefore, we recommend using three injections of PRP in the treatment of patients with knee osteoarthritis of grade I-III.

A microreactor and imaging platform for studying chemical oscillators.

We present a laser scanning confocal microscopy (LSCM) and continuous flow microreactor (CFMR)-based platform to study the Belousov-Zhabotinsky (BZ) oscillators. We demonstrated that the scanning laser light below a certain power had no detectable influence on the BZ reaction. The CFMR consisted of the poly(methyl methacrylate) (PMMA) microwell and the polydimethylsiloxane (PDMS) microchannel and maintained the oscillation with a continuous supply of the catalyst-free BZ mixture. The synchronization of the two nonidentical oscillators was studied by the platform. The coupling intensity was controlled by changing the distance between the two oscillators. Results showed that the synchronization occurred as the oscillators were closer than a critical distance. The transition from desynchronization to synchronization was observed when the distance between the oscillators was near a critical value. The results of the numerical simulation by COMSOL agreed qualitatively with the experimental observation.

Dust source tracing and their transport mechanisms before monsoon season from three glaciers at the Tibetan Plateau: revelations from REE analysis and an indirect tracing approach.

Understanding the origins of Tibetan Plateau (TP) glacier dust is vital for glacier dynamics and regional climate understanding. In May 2016, snow pit samples were collected from glaciers on the TP: Qiyi (QY) in the north, Yuzhufeng (YZF) in the center, and Xiaodongkemadi (XDK) in the south. Rare earth element (REE) concentrations were analyzed using inductively coupled plasma mass spectrometry (ICP-MS), and near-surface PM10 concentrations were extracted from a dataset of Chinese near-surface PM10. Two tracing approaches were used: direct REE tracing and an indirect approach combining potential source contribution function (PSCF) and concentration-weighted trajectory (CWT). Both methods yielded consistent results. Pre-monsoon, TP surface soils, Taklimakan Desert, and Qaidam Basin contributed to glacier dust. Notably, central and southern glaciers showed Thar Desert influence, unlike the northern ones. Taklimakan and Thar Deserts were major contributors due to their substantial contribution and high dust concentration. Taklimakan dust, influenced by terrain and westerly winds, affected central and southern glaciers more than northern ones. Westerlies carried Thar Desert dust to the TP after it was uplifted by updrafts in northwest India, significantly affecting southern glaciers. Furthermore, comparing the two tracer methods, the indirect approach combining PSCF and CWT proved more effective for short-term dust source tracing.

Application of vagus nerve stimulation on the rehabilitation of upper limb dysfunction after stroke: a systematic review and meta-analysis.

Objective: This study aimed to elucidate the efficacy, safety, and long-term implications of vagus nerve stimulation (VNS) as a viable therapeutic option for patients with upper limb dysfunction following a stroke. Methods: Data from the following libraries were searched from inception to December 2022: PubMed, Wanfang, Scopus, China Science and Technology Journal Database, Embase, Web of Science, China Biology Medicine Disc, Cochrane Library, and China National Knowledge Infrastructure. Outcomes included indicators of upper limb motor function, indicators of prognosis, and indicators of safety (incidence of adverse events [AEs] and serious AEs [SAEs]). Two of the authors extracted the data independently. A third researcher arbitrated when disputes occurred. The quality of each eligible study was evaluated using the Cochrane Risk of Bias tool. Meta-analysis and bias analysis were performed using Stata (version 16.0) and RevMan (version 5.3). Results: Ten trials (VNS combined with rehabilitation group vs. no or sham VNS combined with rehabilitation group) with 335 patients were included in the meta-analysis. Regarding upper extremity motor function, based on Fugl-Meyer assessment scores, VNS combined with other treatment options had immediate (mean difference [MD] = 2.82, 95% confidence interval [CI] = 1.78-3.91, I2 = 62%, p < 0.00001) and long-term (day-30 MD = 4.20, 95% CI = 2.90-5.50, p < 0.00001; day-90 MD = 3.27, 95% CI = 1.67-4.87, p < 0.00001) beneficial effects compared with that of the control treatment. Subgroup analyses showed that transcutaneous VNS (MD = 2.87, 95% CI = 1.78-3.91, I2 = 62%, p < 0.00001) may be superior to invasive VNS (MD = 3.56, 95% CI = 1.99-5.13, I2 = 77%, p < 0.0001) and that VNS combined with integrated treatment (MD = 2.87, 95% CI = 1.78-3.91, I2 = 62%, p < 0.00001) is superior to VNS combined with upper extremity training alone (MD = 2.24, 95% CI = 0.55-3.93, I2 = 48%, p = 0.009). Moreover, lower frequency VNS (20 Hz) (MD = 3.39, 95% CI = 2.06-4.73, I2 = 65%, p < 0.00001) may be superior to higher frequency VNS (25 Hz or 30 Hz) (MD = 2.29, 95% CI = 0.27-4.32, I2 = 58%, p = 0,03). Regarding prognosis, the VNS group outperformed the control group in the activities of daily living (standardized MD = 1.50, 95% CI = 1.10-1.90, I2 = 0%, p < 0.00001) and depression reduction. In contrast, quality of life did not improve (p = 0.51). Safety was not significantly different between the experimental and control groups (AE p = 0.25; SAE p = 0.26). Conclusion: VNS is an effective and safe treatment for upper extremity motor dysfunction after a stroke. For the functional restoration of the upper extremities, noninvasive integrated therapy and lower-frequency VNS may be more effective. In the future, further high-quality studies with larger study populations, more comprehensive indicators, and thorough data are required to advance the clinical application of VNS. Systematic review registration: https://www.crd.york.ac.uk/prospero/, identifier: CRD42023399820.

Impact of autologous platelet-rich plasma therapy vs. hyaluronic acid on synovial fluid biomarkers in knee osteoarthritis: a randomized controlled clinical trial.

Objective: Observe the effects of platelet-rich plasma (PRP) therapy on inflammatory cytokines in the synovial fluid of the knee joint of patients with KOA, and explore the effects of PRP intra-articular injection on the inflammation of the knee joint environment and the possible mechanism of action. Methods: Seventy patients were randomized to undergo three blinded weekly intra-articular injections of PRP or hyaluronic acid (HA). The concentrations of inflammatory cytokines, including interleukin (IL)-6, IL-1ß, tumor necrosis factor (TNF)-α, IL-8, IL-17A, IL-17F, IL-4, IL-5, and IL-10, in the synovial fluid were evaluated before the intervention and 1 month after the third injection. The Western Ontario and McMaster University (WOMAC) and visual analog scale (VAS) scores were used to assess pain and functional status of the knee joints in both groups before the intervention, immediately post-intervention, and 1, 3, 6, and 12 months after the intervention. Results: Baseline characteristics were similar in both groups with no statistical difference. The IL-6, IL-1ß, TNF-α, IL-17A, and IL-10 levels in the synovial fluid of the observation group decreased significantly after, vs. before, the intervention (p < 0.05), whereas the IL-8, IL-17F, and IL-4 levels decreased (p > 0.05) and IL-5 levels increased (p > 0.05). There was no statistically significant difference between inflammatory cytokine levels in the synovial fluid of the samples from the control group before and after the intervention (p > 0.05). There were no statistically significant differences between the two groups immediately after intervention (p > 0.05). At 1, 3, 6, and 12 months after intervention, the WOMAC and VAS scores were significantly better in the observation group than in the control group (p < 0.05). Conclusion: Platelet plasma therapy can reduce the concentrations of inflammatory cytokines IL-6, IL-1ß, TNF-α, IL-17A, and IL-10 in the synovial fluid of KOA patients, reduce the expression levels of IL-8, IL-17F, and IL-4, clear the pro-inflammatory factors, improve the inflammatory environment of the affected knee joint, and alleviate pain caused by inflammation. Thus, alleviating pain and improving knee function in patients with KOA.

Association between short-term exposure to ambient air pollution and number of outpatient Helicobacter pylori infection visits.

Helicobacter pylori infection (HPI) is an important risk factor of gastrointestinal diseases, but factors leading to it are still not fully understood. To investigate the association between short-term exposure to air pollution and HPI during outpatient visits, we collected daily data for HPI outpatient visits and air pollutant concentrations during 2014-2021 in Hefei, Anhui Province, China. A time-stratified case-crossover design was performed to analyze the acute impacts of air pollution on HPI outpatient visits. We also explored potential effect modifiers. A total of 9072 outpatient visits were recorded. We found positive and statistically significant associations of acute exposure to nitrogen dioxide (NO2), sulfur dioxide (SO2), and carbon monoxide (CO) with HPI outpatient visits. Threshold concentrations of the three pollutants with same-day exposure (lag 0 day) for outpatient visits were 37 µg/m3 for NO2, 8 µg/m3 for SO2, and 0.8 mg/m3 for CO. The odds ratios for HPI outpatient visits at the 95th percentile of NO2, SO2, and CO against the thresholds were 1.207 (1.120-1.302), 1.175 (1.052-1.312), and 1.110 (1.019-1.209), respectively. The associations were more evident in patients older than 45 years, females, with health insurance, and in cold seasons. Null associations of exposure to either ozone (O3) or particulate matter (PM) were observed. In summary, short-term exposure to NO2, SO2, and CO above certain concentrations, but not PM or O3, may trigger the increased risk of outpatient visits due to HP infection in Chinese population.

Food safety assessment of planting patterns of four vegetable-type crops grown in soil contaminated by electronic waste activities.

A field experiment was conducted to assess the effect of crop and planting pattern on levels of cadmium (Cd), lead (Pb), and copper (Cu) in crops grown in soil contaminated by electronic waste. The crops were maize (Zea mays L. var. Shentian-1), tomato (Solanum lycopersicum L. var. Zhongshu-4), cabbage (Brassica oleracea L. var. Jingfeng-1), and pakchoi (Brassica chinensis (L.) Makino. var. Youdonger-Hangzhou). The planting patterns were crop monoculture, crop co-planted with a legume, and crop co-planted with another crop. Metal concentrations in the edible parts of the crops varied with types of metals and crops. Pb concentration was higher in leafy vegetables (cabbage and pakchoi) than in maize or tomato, Cd concentration was higher in tomato and pakchoi than in maize or cabbage, and Cu concentration was higher in maize and pakchoi than in tomato or cabbage. Metal concentrations in the edible part were also influenced by planting pattern. Relative to monoculture, co-planting and especially co-planting with Japanese clover tended to decrease Pb accumulation and increase Cd accumulation. According to the maximum permissible concentration (MPC) standard of the National Standard Agency in China, only maize (under all planting patterns) could be safely consumed. Because co-planting tended to increase Cd accumulation even in maize, however, the results suggest that maize monoculture is the optimal crop and planting pattern for this kind of contaminated soil.

Plant coexistence can enhance phytoextraction of cadmium by tobacco (Nicotiana tabacum L.) in contaminated soil.

A mesocosm experiment was conducted to investigate whether plant coexistence affects cadmium (Cd) uptake by plant in contaminated soil. Tobacco (Nicotiana tabacum L. var. K326) and Japanese clover (Kummerowia striata (Thunb.) Schindl.) were used. Cadmium was applied as 3CdSO4 x 8H2O in solution at three levels (0, 1, and 3 mg/kg soil) to simulate an unpolluted soil and soils that were slightly and moderately polluted with Cd. Tobacco (crop), Japanese clover (non-crop), and their combination were grown under each Cd treatment. Compared to monoculture and under all Cd treatments, co-planting with Japanese clover did not affect tobacco biomass but significantly increased Cd concentration in all tobacco tissues and enhanced Cd accumulation in tobacco shoots and roots. Compared to monoculture, co-planting reduced soil pH and increased Cd bioavailability. For tobacco, co-planting with Japanese clover increased the Cd bioconcentration factor (BCF) in Cd contaminated soil. Japanese clover also accumulated substantial quantities of Cd in shoots and roots. Thus, total Cd uptake by the plants was much greater with co-planting than with monoculture. The results suggested that phytoextraction can be effectively increased through tobacco co-planting with Japanese clover in mildly Cd-contaminated soil.

Provenance tracing of dust using rare earth elements in recent snow deposited during the pre-monsoon season from mountain glaciers in the central to northern Tibetan Plateau.

To provide insight into dust sources in snow deposited during the non-monsoon period on the Tibetan Plateau, detailed post-Archean Australian shale (PAAS)-normalized rare earth element (REE) distribution patterns and variations in REE tracers, such as La/Yb, La/Er, and Gd/Yb with depth, as well as the distribution of samples in the plots of REE ratio pairs, such as La/Yb vs. Y/ΣREE, La/Er vs. Gd/Er, and Y/La vs. Nd/Er, were compared in seven potential dust source areas in Asia. Snow samples from five glaciers, i.e., Qiumianleike (QMLK), Meikuang (MK), Yuzhufeng (YZF), Xiaodongkemadi (XDKMD), and Gurenhekou (GRHK), were collected from April 26 to May 13 before the onset of monsoon activity. The results show that dust trapped in snow pits from the studied glaciers, i.e., QMLK, MK, XDKMD, and GRHK, has varying degrees of contribution from the Taklimakan Desert, Qaidam Basin, and the surface soil of the Tibetan Plateau. There are signals of the Tengger and Badain Jaran Desert and Chinese Loess in the MK and XDKMD snow pit samples or in the QMLK and GRHK surface samples from the REE tracers; however, from the point of view of the land location, the three dust sources should not be the major contributors. Signals of dust from the Indian Thar Desert were occasionally detected from the MK, YZF, and XDKMD snow pit samples and GRHK surface snow samples, implying the intrusion of early Indian monsoon activities to the sites. The dust signal from the Thar Desert in India from the YZF glacier is significantly greater than that from the XDKMD and MK glaciers. These findings were also supported by the tracer of dust transmitted to the three snow pits through the air mass backward trajectories. The new finding of this study is that dust from the Indian Desert can even reach the Kunlun Mountains in the northern region of the Tibetan Plateau. The conclusions are helpful in interpreting the sources of dust and the pollutants absorbed by dust particles, as well as the extent of the impact of Indian monsoon activities at the end of the non-monsoon season on the plateau.

Iron in the NEEM ice core relative to Asian loess records over the last glacial-interglacial cycle.

Mineral dust can indirectly affect the climate by supplying bioavailable iron (Fe) to the ocean. Here, we present the records of dissolved Fe (DFe) and total Fe (TDFe) in North Greenland Eemian Ice Drilling (NEEM) ice core over the past 110 kyr BP. The Fe records are significantly negatively correlated with the carbon-dioxide (CO2) concentrations during cold periods. The results suggest that the changes in Fe fluxes over the past 110 kyr BP in the NEEM ice core are consistent with those in Chinese loess records because the mineral-dust distribution is controlled by the East Asian deserts. Furthermore, the variations in the dust input on a global scale are most likely driven by changes in solar radiation during the last glacial-interglacial cycle in response to Earth's orbital cycles. In the last glacial-interglacial cycle, the DFe/TDFe ratios were higher during the warm periods (following the post-Industrial Revolution and during the Holocene and last interglacial period) than during the main cold period (i.e. the last glacial maximum (LGM)), indicating that the aeolian input of iron and the iron fertilization effect on the oceans have a non-linear relationship during different periods. Although the burning of biomass aerosols has released large amounts of DFe since the Industrial Revolution, no significant responses are observed in the DFe and TDFe variations during this period, indicating that severe anthropogenic contamination has no significant effect on the DFe (TDFe) release in the NEEM ice core.

Atmospheric pollution revealed by trace elements in recent snow from the central to the northern Tibetan Plateau.

In order to determine the current levels, spatial distribution patterns, and potential pollution of trace elements (TEs) in the atmosphere of the Tibetan Plateau (TP), snow pit samples were collected in May 2016 from five TP glaciers: Qiyi (QY), Hariqin (HRQ), Meikuang (MK), Yuzhufeng (YZF), and Xiaodongkemadi (XDKMD). Concentrations of 13 TEs (Al, Ba, Cd, Co, Cr, Cu, Fe, Li, Pb, Sb, Sr, U, and Zn) in the snow were measured. The spatial distribution patterns and depth profiles of TEs from the studies sites revealed that the influence of dust on TEs was more significant on the MK and YZF glaciers than on the QY, HRQ, and XDKMD glaciers. The spatial distributions of TE EFFe values differed from their concentrations, however. The enrichment factor (EF) values and concentrations of some TEs in the YZF, QY, and XDKMD glaciers revealed that the pollution levels of these elements were significantly lower than those found in previous research. Examination based on EFs, principal component analysis, as well as the calculated non-dust contributions of TEs, revealed that dust was the principal source for most TEs in all five glaciers, while biomass burning was another potential natural source for TEs in some glaciers, such as QY. In contrast, Cd, Ba, Sr, Cu, Pb, Zn, and Sb were occasionally affected by anthropogenic sources such as road traffic emissions, fossil fuel combustion, and mining and smelting of nonferrous metals in and beyond the TP. Air mass backward trajectories revealed that potential pollutants were transported not only from local sources but also from Xinjiang Province in northwestern China, as well as South Asia, Central Asia, the Middle East, and Europe.

Increase of emm1 isolates among group A Streptococcus strains causing scarlet fever in Shanghai, China.

OBJECTIVE: Scarlet fever epidemics caused by group A Streptococcus (GAS) have been ongoing in China since 2011. However, limited data are available on the dynamic molecular characterizations of the epidemic strains. METHOD: Epidemiological data of scarlet fever in Shanghai were obtained from the National Notifiable Infectious Disease Surveillance System. Throat swabs of patients with scarlet fever and asymptomatic school-age children were cultured. Illumina sequencing was performed on 39emm1 isolates. RESULTS: The annual incidence of scarlet fever was 7.5-19.4/100,000 persons in Shanghai during 2011-2015, with an average GAS carriage rate being 7.6% in school-age children. The proportion ofemm1 GAS strains increased from 3.8% in 2011 to 48.6% in 2014; they harbored a superantigen profile similar to emm12 isolates, except for the speA gene. Two predominant clones, SH001-emm12, and SH002-emm1, circulated in 66.9% of scarlet fever cases and 44.8% of carriers. Genomic analysis showed emm1 isolates throughout China constituted distinct clades, enriched by the presence of mobile genetic elements carrying the multidrug-resistant determinants ermB and tetM and virulence genes speA, speC, and spd1. CONCLUSION: A significant increase in the proportion ofemm1 strains occurred in the GAS population, causing scarlet fever in China. Ongoing surveillance is warranted to monitor the dynamic changes of GAS clones.

Spatial variations and sources of trace elements in recent snow from glaciers at the Tibetan Plateau.

Trace elements (TEs) could pose a potential threat to the environment and human health and hence they have been paid attention increasingly at present. This study presents the acid-leached concentrations of TEs (e.g., Al, As, Ba, Co, Cr, Cs, Cu, Fe, Li, Mn, Mo, Pb, Rb, Sb, Sr, Ti, Tl, U, V) and dust content sampled from Qiumianleike (QMLK), Meikuang (MK), Yuzhufeng (YZF), Xiaodongkemadi (XDKMD), Gurenhekou (GRHK) glaciers on the Tibetan Plateau (TP) from April to May in 2013. A nonparametric Jonckheere-Terpstra Method was used to test the trend of spatial distribution of TEs. The statistical analysis indicates that TEs were the highest in the QMLK glacier, lowest in the YZF glacier, and comparable in the other three glaciers. Comparison with other glaciers of the plateau, the statistical analysis on As, Cu, Mo, Pb, and Sb shows that their concentrations had, in general, a decreasing distribution characteristic from the north to the south of TP, which indicates that the northern TP is loading more atmospheric-polluted impurity than central and southern TP. Enrichment factor (EF) analysis indicates that Rb, V, U, Cr, Ba, Cs, Li, As, Co, Mn, Tl, Sr, and Cu originated mainly from crustal dust, while anthropogenic inputs such as nonferrous metals melting, coal combustion, and traffic emission made an important contribution to the Mo, Pb, and Sb. Evidences from air mass back trajectories show that TEs in the five studied glaciers might not only come from surrounding areas of glaciers but also might be long-range transported by atmosphere from the Central Asia and South Asia and deposited on these glaciers.