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1.
Environ Pollut ; 278: 116824, 2021 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-33689948

RESUMO

While the influence of climate change on the fate of persistent organic pollutants (POPs) is becoming a topic of global concern, it has yet to be demonstrated how POPs and their transformation products in soil respond to a changing climate at the local scale. We conducted a year-long field experiment with spiked soils to investigate the impact of climate on the dissipation of γ-hexachlorocyclohexane (γ-HCH) and p,p'-dichlorodiphenyltrichloroethane (p,p'-DDT) as well as the formation of their products. Four sites along an elevational gradient on the eastern Tibetan Plateau were selected to represent four scenarios ranging from a dry and cold to a warm and humid climate. Based on the measured concentrations of the two pesticides and their transformation products, we calculated the dissipation rates of γ-HCH and p,p'-DDT in soil using two biphasic kinetic models, and the formation rates of transformation products using a mid-point rectangular approximation method. The spiked γ-HCH generally showed the expected decrease in dissipation from soils with increasing altitudes, and therefore decreasing temperature and precipitation, whereas dissipation of p,p'-DDT was influenced more by photolysis and sequestration in soil. The formation rates of the primary products of γ-HCH (i.e. γ-HCH→PeCCH and γ-HCH→TeCCH) and p,p'-DDT (i.e. p,p'-DDT→p,p'-DDE and p,p'-DDT→p,p'-DDD) indicate that a warmer and wetter climate favors dechloroelimination (anaerobic biodegradation) over dehydrochlorination (aerobic biodegradation). The significantly longer dissipation half-lives of γ-HCH at the coldest site suggests that the fate of POPs in frozen regions (e.g. polar regions) needs more attention. Overall, the fate of more volatile chemicals (e.g. γ-HCH) might be more responsive to the climate change.

2.
Artigo em Inglês | MEDLINE | ID: mdl-33733538

RESUMO

AIM: Inflammatory bowel disease (IBD), irritable bowel syndrome (IBS), and celiac disease (CeD) more commonly affect women of reproductive age. The aim of our study is to evaluate the association between ectopic pregnancy (EP) in women with IBD, IBS, and CeD. METHODS: We searched MEDLINE, Web of Science, and CINAHL from the database inception date through December 31, 2020. Peer-reviewed publications and abstracts written in English, regarding the association between EP and IBD, IBS, and CeD with controls were included. Quality assessment was conducted based on GRADE criteria. Analyses included odds ratios (ORs) with 95% confidence intervals (CIs). Heterogeneity between studies was presented with I2 . RESULTS: We included five population-based cohort studies. The odds of EP significantly increased in Crohn's disease (CD), but not ulcerative colitis (UC) as compared to IBD-free controls. The odds of EP significantly increased in IBS as compared to women without IBS. No significant difference was observed for odds of EP in women with and without CeD. CONCLUSIONS: Possible evidence of associations between EP and CD as well as IBS were observed; however, not with UC and CeD. Pregnant women with chronic inflammatory bowel pathologies may warrant cautious monitoring.

3.
Chem Soc Rev ; 2021 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-33734247

RESUMO

Stimulus-cleavable nanoscale drug delivery systems are receiving significant attention owing to their capability of achieving exquisite control over drug release via the exposure to specific stimuli. Central to the construction of such systems is the integration of cleavable linkers showing susceptibility to one stimulus or several stimuli with drugs, prodrugs or fluorogenic probes on the one hand, and nanocarriers on the other hand. This review summarises recent advances in stimulus-cleavable linkers from various research areas and the corresponding mechanisms of linker cleavage and biological applications. The feasibility of extending their applications to the majority of nanoscale drug carriers including nanomaterials, polymers and antibodies are further highlighted and discussed. This review also provides general design guidelines to incorporate stimulus-cleavable linkers into nanocarrier-based drug delivery systems, which will hopefully spark new ideas and applications.

4.
Artigo em Inglês | MEDLINE | ID: mdl-33644970

RESUMO

α-aryl α,ß-unsaturated carbonyls represent an important class of derivatizable synthetic intermediates, however, the synthesis of such compounds still remains a challenge. Recently, we showcased a novel Z -selective α-arylation of α,ß-unsaturated nitriles with aryl sulfoxides via [3,3]-rearrangement involving an Morita-Baylis-Hillman (MBH) process. In this Article, we demonstrate the feasibility of reversing the stereoselectivity of such MBH-type [3,3]-rearrangement by switching to a new pair of rearrangement partners consisting of aryl iodanes and α,ß-unsaturated oxazolines. As a result, the two protocols complement each other in approaching E- or Z- α-aryl α,ß-unsaturated carbonyl derivatives. Mechanistic studies reveal a possible reaction pathway and provide an explanation for the opposite stereoselectivities.

5.
J Vis Exp ; (168)2021 02 25.
Artigo em Inglês | MEDLINE | ID: mdl-33720125

RESUMO

Microglia are the mononuclear phagocytes in the central nervous system (CNS), which play key roles in maintaining homeostasis and regulating the inflammatory process in the CNS. To study the microglial biology in vitro, primary microglia show great advantages compared to immortalized microglial cell lines. However, microglia isolation from the postnatal mouse brain is relatively less efficient and time-consuming. In this protocol, we provide a quick and easy-to-follow method to isolate primary microglia from the neonatal mouse brain. The overall steps of this protocol include brain dissection, primary brain cell culture, and microglia isolation. Using this approach, researchers can obtain primary microglia with high purity. In addition, the harvested primary microglia were able to respond to the lipopolysaccharides challenge, indicating they retained their immune function. Collectively, we developed a simplified approach to efficiently isolate primary microglia with high purity, which facilitates a wide range of microglial biology investigations in vitro.

6.
Chem Rev ; 2021 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-33788546

RESUMO

Since the advent of the first computers, chemists have been at the forefront of using computers to understand and solve complex chemical problems. As the hardware and software have evolved, so have the theoretical and computational chemistry methods and algorithms. Parallel computers clearly changed the common computing paradigm in the late 1970s and 80s, and the field has again seen a paradigm shift with the advent of graphical processing units. This review explores the challenges and some of the solutions in transforming software from the terascale to the petascale and now to the upcoming exascale computers. While discussing the field in general, NWChem and its redesign, NWChemEx, will be highlighted as one of the early codesign projects to take advantage of massively parallel computers and emerging software standards to enable large scientific challenges to be tackled.

7.
Artigo em Inglês | MEDLINE | ID: mdl-33724399

RESUMO

OBJECTIVES: The aim of this study was to assess the impact of individual operator experience on outcomes after complete repair for tetralogy of Fallot. METHODS: This is a retrospective cohort study. Consecutive patients who underwent TOF repair at a single institution were included and compared according to whether the primary operator was an experienced, high-volume operator (defined as an operator who performed at least 20 surgical procedures for congenital heart disease defined as complex by the Risk Adjustment for Congenital Heart Surgery classification per year for at least 3 consecutive years). The primary outcome was defined as a composite of death, or reintervention, or significant annular peak gradient, or significant pulmonary regurgitation. Multivariable logistic regression and Cox proportional-hazards model analyses were used to assess the relationships between operator experience and outcomes. RESULTS: From January 2012 to December 2017, a total of 1760 patients with primary diagnosis of TOF underwent TOF repair by 37 operators. Of these, 5 operators (13.5%) were considered experienced, and 32 (86.5%) were considered less experienced. Complete follow-up data were available for 1728 complete repair for TOF patients with a median follow-up duration of 49 months; in 611 patients (35.4%), the surgery was performed by experienced operators, and in 1117 patients (64.6%), the surgery was performed by less experienced operators. Adjusted risks for the primary outcome and significant pulmonary regurgitation were lower for patients who were treated by experienced operators, both at discharge [adjusted odds ratio 0.67, 95% confidence interval (CI) 0.50-0.90; adjusted odds ratio 0.54, 95% CI 0.37-0.78, respectively] and at follow-up (adjusted hazard ratio 0.82, 95% CI 0.68-0.97; adjusted hazard ratio 0.70, 95% CI 0.56-0.87, respectively). The trend for the primary outcome during follow-up remained unchanged, even in most subgroups. CONCLUSIONS: Increased surgeon experience is associated with improved risk-adjusted outcomes. These results have potentially important implications for individual training, quality improvement and hospital programmes in the context of complete repair for TOF. REGISTRATION NUMBER: http://www.chictr.org.cn number, ChiCTR2000033234.

8.
Cancer Med ; 2021 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-33724697

RESUMO

OBJECTIVE: We aimed to evaluate the role of tumor size in predicting tumor risk for localized prostate cancer (PCa) patients undergoing radical prostatectomy (RP). METHODS: Twenty-five thousand, one hundred twenty-seven men with PCa receiving RP from 2010 to 2015 were extracted from the Surveillance, Epidemiology, and End Results database. Kaplan-Meier plots and multivariable Cox regression analyses were used to illustrate overall survival (OS) according to the tumor size. The tumor size was confirmed by postoperative pathology after RP. RESULTS: Among overall localized PCa, 84.6% were high-risk PCa, 9.2% were intermediate-risk PCa, and 6.2% were low-risk PCa. Multivariate analyses demonstrated that tumor size ≥21 mm was an independent risk predict factor of low-risk PCa (odds ratio [OR]: 11.940; 95% CI, 9.404-15.161; p < 0.001) and intermediate-risk PCa (OR: 1.887; 95% CI, 1.586-2.245; p < 0.001). Tumor sizes ≤5 mm significantly correlated with high-risk PCa (p < 0.001). Tumor size ≤5 mm had the worst OS in overall localized PCa and high-risk PCa (p < 0.001). CONCLUSIONS: In localized PCa, tumor sizes ≥21 mm may help predict low or intermediate-risk PCa, while tumor sizes ≤5 mm might help predict high-risk PCa. In clinical practice, we should be on high alert for patients with tumors size ≤5 mm due to its poor prognosis after RP.

9.
Biomed Res Int ; 2021: 6530298, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33748270

RESUMO

DUOX2 has been reported to highly express in several types of cancers. However, the prognostic significance and the biological function of DUOX2 expression with pancreatic cancer (PC) still remain unclear. The present study is aimed at investigating whether DUOX2 could act as a novel biomarker of prognosis and evaluating its effect on PC cell progression. The mRNA and protein expression of DUOX2 in PC cells and tissues were assessed by quantitative real-time PCR (RT-qPCR) and immunohistochemistry. The effect of DUOX2 expression on PC cell motility and proliferation was evaluated in vitro. The correlation between DUOX2 mRNA expression and clinicopathological features and its prognostic significance were analyzed according to the Gene Expression Profiling Interactive Analysis (GEPIA) website based on The Cancer Genome Atlas (TCGA) and the GTEx databases combined with our clinical information. According to bioinformatics analysis, we forecasted the upstream transcription factors (TFs) and microRNA (miRNA) regulatory mechanism of DUOX2 in PC. The expression of DUOX2 at transcriptional and protein level was dramatically increased in PC specimens when compared to adjacent nontumor specimens. Functionally, DUOX2 knockdown inhibited cell motility and proliferation activities. Our clinical data revealed that the patients had better postoperative overall survival (OS) with lower expression of DUOX2, which is consistent with GEPIA data. Multivariate analysis revealed that high DUOX2 expression was considered as an independent prognostic indicator for OS (P = 0.031). Based on Cistrome database, the top 5 TFs of each positively and negatively association with DUOX2 were predicted. hsa-miR-5193 and hsa-miR-1343-3p targeting DUOX2 were forecasted from TargetScan, miRDB, and DIANA-TarBase databases, which were negatively correlated with OS (P = 0.043 and P = 0.0088, respectively) and DUOX2 expression (P = 0.0093 and P = 0.0032, respectively) in PC from TCGA data. These findings suggest that DUOX2 acts as a promising predictive biomarker and an oncogene in PC, which could be a therapeutic target for PC.

10.
Life Sci ; 271: 119181, 2021 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-33581128

RESUMO

AIMS: To investigate the roles and mechanisms of C. trachomatis glycogen synthase (GlgA) in regulating the inflammatory response in THP-1 cells. MAIN METHODS: In this work, after THP-1 cells were stimulated with GlgA, transcript and protein expression levels were measured by qRT-PCR and ELISA, respectively. Western blotting and immunofluorescence were used to determine the signaling pathway involved in the inflammatory mechanism. KEY FINDINGS: GlgA elicited the expression of interleukin-8 (IL-8), interleukin-1beta (IL-1ß) and tumor necrosis factor alpha (TNF-α) in THP-1 cells, and the blockade of TLR2 and TLR4 signaling abrogated the induction of IL-8, TNF-α and IL-1ß expression. Similarly, IL-8, IL-1ß and TNF-α secretion was reduced by transfection with a dominant negative plasmid (pDeNyhMyD88). Moreover, Western blotting and immunofluorescence experiments further validated that MAPKs and NF-кB signaling are involved in the transcription and translation of these cytokines. Treatment of the cells with ERK and JNK inhibitors dramatically attenuated the induction of IL-8, IL-1ß and TNF-α. SIGNIFICANCE: These results suggest that GlgA contributes to inflammation during C. trachomatis infection via the TLR2, TLR4 and MAPK/NF-кB pathways, which may enhance our understanding of the pathogenesis of C. trachomatis.


Assuntos
Chlamydia trachomatis/enzimologia , Citocinas/metabolismo , Glicogênio Sintase/farmacologia , Sistema de Sinalização das MAP Quinases/fisiologia , Receptor 2 Toll-Like/metabolismo , Receptor 4 Toll-Like/metabolismo , Relação Dose-Resposta a Droga , Humanos , Mediadores da Inflamação/metabolismo , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Células THP-1
11.
Nat Neurosci ; 24(4): 516-528, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33526942

RESUMO

Anxiety is a negative emotional state that is overly displayed in anxiety disorders and depression. Although anxiety is known to be controlled by distributed brain networks, key components for its initiation, maintenance and coordination with behavioral state remain poorly understood. Here, we report that anxiogenic stressors elicit acute and prolonged responses in glutamatergic neurons of the mouse medial preoptic area (mPOA). These neurons encode extremely negative valence and mediate the induction and expression of anxiety-like behaviors. Conversely, mPOA GABA-containing neurons encode positive valence and produce anxiolytic effects. Such opposing roles are mediated by competing local interactions and long-range projections of neurons to the periaqueductal gray. The two neuronal populations antagonistically regulate anxiety-like and parental behaviors: anxiety is reduced, while parenting is enhanced and vice versa. Thus, by evaluating negative and positive valences through distinct but interacting circuits, the mPOA coordinates emotional state and social behavior.

12.
Biomed Eng Online ; 20(1): 20, 2021 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-33579302

RESUMO

BACKGROUND: Self-esteem is the individual evaluation of oneself. People with high self-esteem grade have mental health and can bravely cope with the threats from the environment. With the development of neuroimaging techniques, researches on cognitive neural mechanisms of self-esteem are increased. Existing methods based on brain morphometry and single-layer brain network cannot characterize the subtle structural differences related to self-esteem. METHOD: To solve this issue, we proposed a multiple anatomical brain network based on multi-resolution region of interest (ROI) template to study the brain structural connections of self-esteem. The multiple anatomical brain network consists of ROI features and hierarchal brain network features that are extracted from structural MRI. For each layer, we calculated the correlation relationship between pairs of ROIs. In order to solve the high-dimensional problem caused by the large amount of network features, feature selection methods (t-test, mRMR, and SVM-RFE) are adopted to reduce the number of features while retaining discriminative information to the maximum extent. Multi-kernel SVM is employed to integrate the various types of features by appropriate weight coefficient. RESULT: The experimental results show that the proposed method can improve classification accuracy to 97.26% compared with single-layer brain network. CONCLUSIONS: The proposed method provides a new perspective for the analysis of brain structural differences of self-esteem, which also has potential guiding significance in other researches involved brain cognitive activity and brain disease diagnosis.

13.
Hematology ; 26(1): 179-185, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33594943

RESUMO

BACKGROUND: Intermediate-risk acute myeloid leukemia (IR-AML) without FLT3-ITD, NPM1 and biallelic CEBPA mutations (here referred to as NPM1mut-negCEBPAdm-negFLT3-ITDneg AML) is a clinically heterogeneous disease. The optimal post-remission therapy (PRT) is unclear for patients with NPM1mut-negCEBPAdm-negFLT3-ITDneg AML who achieved first complete response (CR1). This study aims to explore clinical and molecular factors that can help determine the prognosis of those patients and their choice of PRT. METHODS: We retrospectively analyzed 28 patients with NPM1mut-negCEBPAdm-negFLT3-ITDneg AML who received induction chemotherapy and achieved CR1. For PRT, 17 patients received post-remission chemotherapy (PR-CT) and 11 patients received allogeneic hematopoietic stem cell transplantation (allo-HSCT). RESULTS: For patients with NPM1mut-negCEBPAdm-negFLT3-ITDneg AML, multivariate analysis indicated that allo-HSCT and negative minimal residual disease (MRDneg) before PRT were favorable prognostic factors of overall survival (OS) (allo-HSCT, P = 0.002; MRDneg, P = 0.018); whereas relapse was an adverse prognostic factor of OS (P = 0.003). Log-rank analysis showed that allo-HSCT significantly improved their OS and RFS compared with PR-CT (OS, P < 0.001; RFS, P = 001). Otherwise, allo-HSCT improved the OS and RFS of patients with NPM1mut-negCEBPAdm-negFLT3-ITDneg AML, whether they obtained MRDpos or MRDneg before PRT (OS: MRDneg, P = 0.036; MRDpos, P = 0.012; RFS: MRDneg, P = 0.047; MRDpos, P = 0.030). CONCLUSION: For patients with NPM1mut-negCEBPAdm-negFLT3-ITDneg AML, MRDneg before PRT and allo-HSCT were favorable prognostic factors of OS. Whether they obtain MRDneg or not, allo-HSCT is the preferred PRT.

14.
Brief Bioinform ; 22(2): 1466-1475, 2021 03 22.
Artigo em Inglês | MEDLINE | ID: mdl-33620066

RESUMO

Coronavirus disease 2019 (COVID-19) has spread rapidly worldwide, causing significant mortality. There is a mechanistic relationship between intracellular coronavirus replication and deregulated autophagosome-lysosome system. We performed transcriptome analysis of peripheral blood mononuclear cells (PBMCs) from COVID-19 patients and identified the aberrant upregulation of genes in the lysosome pathway. We further determined the capability of two circulating markers, namely microtubule-associated proteins 1A/1B light chain 3B (LC3B) and (p62/SQSTM1) p62, both of which depend on lysosome for degradation, in predicting the emergence of moderate-to-severe disease in COVID-19 patients requiring hospitalization for supplemental oxygen therapy. Logistic regression analyses showed that LC3B was associated with moderate-to-severe COVID-19, independent of age, sex and clinical risk score. A decrease in LC3B concentration <5.5 ng/ml increased the risk of oxygen and ventilatory requirement (adjusted odds ratio: 4.6; 95% CI: 1.1-22.0; P = 0.04). Serum concentrations of p62 in the moderate-to-severe group were significantly lower in patients aged 50 or below. In conclusion, lysosome function is deregulated in PBMCs isolated from COVID-19 patients, and the related biomarker LC3B may serve as a novel tool for stratifying patients with moderate-to-severe COVID-19 from those with asymptomatic or mild disease. COVID-19 patients with a decrease in LC3B concentration <5.5 ng/ml will require early hospital admission for supplemental oxygen therapy and other respiratory support.

15.
Kardiol Pol ; 2021 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-33506659

RESUMO

BACKGROUND: Transcatheter closure has become an effective and safe method to repair ventricular septal defects (VSDs). However, the VSD closure device frequently used in the past led to serious complications, such as complete atrioventricular block. The second-generation device Amplatzer Duct Occluder (ADO II) was originally designed to block small- and medium-sized patent ductus arteriosus. Interestingly, there are some reports of the use of ADO II to close VSD because of its fewer complications. AIMS: A meta-analysis of the existing literature was performed to systematically investigate the efficacy and safety of ADO II for VSD closure. METHODS: The Embase, PubMed, Cochrane and Web of Science databases were searched for original studies on VSD closure with ADO II up to March 15, 2020. The random-effects model and summary rate were employed to estimate the success and complications of VSD closure with ADO II. RESULTS: A total of 13 articles comprising 478 patients with VSD were included. The age of the patients ranged from 0.5 to 55.7 years. The overall estimated device-implantation success rate was 99% [95% confidence interval (CI): 98-100%]. Residual shunts (4%, 95% CI: 1-7%) and postoperative aortic valve regurgitation (0%, 95% CI: 0-1%) were common complications. Only three patients developed device embolism. CONCLUSIONS: ADO II may be a safer and more effective transcatheter closure device for patients with VSD, with a higher success rate and lower complication rate than other devices.

16.
Med Biol Eng Comput ; 59(2): 315-326, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33438109

RESUMO

A dynamic L-cube polynomial is proposed to analyze dynamic three-dimensional pulse images (d3DPIs), as an extension of the previous static L-cube polynomial. In this paper, a weighted least squares (WLS) method is proposed to fit the amplitude C(t) of d3DPI at four physiological key points in addition to the best fit of L-cube polynomials to the measured normal and cold-pressor-test (CPT)-induced taut 3DPIs. Compared with other two fitting functions, C(t) of a dynamic L-cube polynomial can be well matched by the proposed WLS method with the least relative error at four physiological key points in one beat with statistical significance, in addition to the best fit of the measured 3DPIs. Therefore, a dynamic L-cube polynomial can reflect dynamic time characteristics of normal and CPT-induced hypertensive taut 3DPIs, which can be used as an evidence of hypertension diagnosis.

17.
PLoS One ; 16(1): e0245207, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33411807

RESUMO

In the present study, we evaluated adjuvant potential of Poria cocos polysaccharide (PCP) on the Th1-type immune responses of C57/BL6 mice against ovalbumin (OVA). We first determined the effect of PCP on maturation of murine bone marrow derived dendritic cells (BMDCs), PCP significantly upregulated surface expression of MHCII, CD40, CD80, CD86 and enhanced production of IL-6 and IL-12p40. In addition, PCP affected receptor-mediated endocytosis, but not pinocytosis in BMDCs. Furthermore, OVA + PCP immunization induced specific cytotoxic CD8+ T cell killing of OVA (257-264) peptide pulsed cell. When mice were immunized subcutaneously in a week interval with OVA + PCP. Serum were collected for measuring OVA-specific antibody and splenocytes were harvested for analyzing CD69, IFN-γ ELISpot and cytokines production. The result indicated that OVA-specific IgG, IgG2a and IgG1 antibody levels in serum were significantly elevated by PCP compared with control. PCP increased OVA-specific IFN-γ-secreting CD8+, CD4+ T cells, promoted CD8+ T cell proliferation and up-regulated Th-1 type (IFN-γ, IL-2) cytokine production. In conclusion, data suggest that PCP enhanced cellular immune response and possess potential as a vaccine adjuvant for Th1 immune response.

18.
Artigo em Inglês | MEDLINE | ID: mdl-33512684

RESUMO

The concentrations of major and trace elements in the sediments from the Four River inlets of Dongting Lake were analysed. The results show that the element compositions of the Four River inlet sediments are different, among which higher amounts of Al2O3, Fe2O3, MnO, Cs, Rb, Th, U, Y, and REE are found, while MgO, CaO, Na2O, and Sr are more depleted in the sediments from the Xiangjiang and Zijiang inlets than in the sediments from the Yuanjiang and Lishui inlets. The Xiangjiang inlet sediments are distinctly higher enriched (EF > 5.0) in heavy metals Bi, Cd, Mn, Cu, Pb, and Zn, while the other river sediments are moderately enriched (EF > 2.0) in these heavy metals. These geochemical differences are resulted from the source lithology, chemical weathering, hydrological sorting, and anthropogenic processes taking place in the watersheds. The principal component analysis and the geochemical vertical profiles suggest that the trace metals Ba, Mo, V, Cr, Co, Ni, Cs, Rb, Sc, Th, U, Ga, Ge, Zr, Hf, Ta, Nb, and REE are of terrigenous sources. The heavy metals including Bi, Cd, Mn, Cu, Pb, and Zn in the sediments can include those contributed by anthropogenic processes, such as mining and smelting of Pb-Zn ores. Therefore, presenting a scheme for the geochemical backgrounds of the watershed is recommended here for future assessment of the heavy metal contamination in sediments of the watershed.

19.
Opt Lett ; 46(2): 400-403, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-33449039

RESUMO

A cost-efficient and low-complexity optical input/output (I/O) packaging solution is a substantial challenge for volume production of photonic integrated circuits. To address this, metamaterial fiber couplers are an attractive solution for integrated photonic devices especially for optical I/O, interfacing standard optical fibers to photonic chips. They offer the advantages of refractive index engineering to achieve better mode match as well as higher fabrication tolerances. Metamaterial waveguides, as a fundamental building block of these fiber couplers, have attracted tremendous attention in recent years. Here, we report on effective optical return loss control in Si metamaterial waveguide designs to achieve ultra-low reflection loss in CMOS-compatible silicon photonics implemented in a 300 mm production line. Low backscattering is a substantial consideration for a range of applications. Here, a return loss of better than -30dB is achieved.

20.
Soft Matter ; 2021 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-33496306

RESUMO

Photo-catalytically active crystalline TiO2 has attracted special attention due to its relevance for renewable energy and is typically obtained by the calcination of amorphous TiO2. However, stabilising hollow colloidal TiO2 particles against aggregation during calcination without compromising their photocatalytic activity poses two conflicting demands: to be stable their surface needs to be coated, while efficient photocatalysis requires an exposed TiO2 surface. Here, this incompatibility is resolved by partially coating TiO2 shells with evenly distributed 3-trimethoxysilyl propyl methacrylate (TPM) lobes. These lobes act both as steric barriers and surface charge enhancers that efficiently stabilise the TiO2 shells against aggregation during calcination. The morphology of the TPM lobes and their coverage, and the associated particle stability during the calcination-induced TiO2 crystallization, can be controlled by the pH and the contact angle between TPM and TiO2. The crystal structure and the grain size of the coated TiO2 shells are controlled by varying the calcination temperature, which allows tuning their photocatalytic activity. Finally, the durable photocatalytic activity over many usage cycles of the coated TiO2 compared to uncoated shells is demonstrated in a simple way by measuring the photo-degradation of a fluorescent dye. Our approach offers a general strategy for stabilising colloidal materials, without compromising access to their active surfaces.

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