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1.
Opt Lett ; 46(19): 5027-5030, 2021 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-34598261

RESUMO

Waveguide taper, a key component in the photonic integrated circuit (PIC), enables on-chip mode conversion, but large-footprint tapers are detrimental to the PIC, which desires compact and efficient devices. Polarization sensitivity also limits the tapers in the applications involving orthogonal modes. In this work, we design an efficient polarization-insensitive ultra-short MMI-based waveguide taper, through the mode spreading principle and the self-image principle. The proposed taper is 26.3 µm long, one order of magnitude shorter than the standard linear taper. We fabricate the taper, and experimentally demonstrate that it exhibits a high transmission efficiency of ∼70% and a wide 1 dB bandwidth of >54nm, for both TE and TM polarizations.

2.
Front Cell Infect Microbiol ; 11: 657807, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34568080

RESUMO

It is known that the microbiome affects human physiology, emotion, disease, growth, and development. Most humans exhibit reduced appetites under high temperature and high humidity (HTHH) conditions, and HTHH environments favor fungal growth. Therefore, we hypothesized that the colonic mycobiota may affect the host's appetite under HTHH conditions. Changes in humidity are also associated with autoimmune diseases. In the current study mice were fed in an HTHH environment (32°C ± 2°C, relative humidity 95%) maintained via an artificial climate box for 8 hours per day for 21 days. Food intake, the colonic fungal microbiome, the feces metabolome, and appetite regulators were monitored. Components of the interleukin 17 pathway were also examined. In the experimental groups food intake and body weight were reduced, and the colonic mycobiota and fecal metabolome were substantially altered compared to control groups maintained at 25°C ± 2°C and relative humidity 65%. The appetite-related proteins LEPT and POMC were upregulated in the hypothalamus (p < 0.05), and NYP gene expression was downregulated (p < 0.05). The expression levels of PYY and O-linked ß-N-acetylglucosamine were altered in colonic tissues (p < 0.05), and interleukin 17 expression was upregulated in the colon. There was a strong correlation between colonic fungus and sugar metabolism. In fimo some metabolites of cholesterol, tromethamine, and cadaverine were significantly increased. There was significant elevation of the characteristic fungi Solicoccozyma aeria, and associated appetite suppression and interleukin 17 receptor signaling activation in some susceptible hosts, and disturbance of gut bacteria and fungi. The results indicate that the gut mycobiota plays an important role in the hypothalamus endocrine system with respect to appetite regulation via the gut-brain axis, and also plays an indispensable role in the stability of the gut microbiome and immunity. The mechanisms involved in these associations require extensive further studies.


Assuntos
Disbiose , Receptores de Interleucina-17 , Animais , Apetite , Regulação do Apetite , Basidiomycota , Colo , Umidade , Camundongos , Temperatura
3.
Nanotechnology ; 2021 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-34352737

RESUMO

Recently, when we sorting through published articles, we find a mistake: the transmission electron microscope (TEM) of PbSe QDs figure 1(d)from Nanotechnology 27 (2016) 405201 is incorrectly used as a TEM image of PbS QDs in the inset of figure 1(a) in my paper (Nanotechnology 28 (2017) 145201). We provide a corrected TEM image and replace the original TEM image of figure 1(a) in our paper (Nanotechnology 28 (2017) 145201). The corrigendum of our paper here is provided. The corrigendum does not affect the conclusions of that paper. The ACKNOWLEDGMENTS section should be added. The authors apologize for any inconvenience that this may have caused.

4.
Nanomaterials (Basel) ; 11(5)2021 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-33946878

RESUMO

Borophene, a new member of the two-dimensional material family, has been found to support surface plasmon polaritons in visible and infrared regimes, which can be integrated into various optoelectronic and nanophotonic devices. To further explore the potential plasmonic applications of borophene, we propose an infrared plasmonic sensor based on the borophene ribbon array. The nanostructured borophene can support localized surface plasmon resonances, which can sense the local refractive index of the environment via spectral response. By analytical and numerical calculation, we investigate the influences of geometric as well as material parameters on the sensing performance of the proposed sensor in detail. The results show how to tune and optimize the sensitivity and figure of merit of the proposed structure and reveal that the borophene sensor possesses comparable sensing performance with conventional plasmonic sensors. This work provides the route to design a borophene plasmonic sensor with high performance and can be applied in next-generation point-of-care diagnostic devices.

5.
Aging (Albany NY) ; 13(7): 10240-10274, 2021 03 26.
Artigo em Inglês | MEDLINE | ID: mdl-33819195

RESUMO

A recent study showed that a gestational high fat diet protects 3xTg-AD offspring from memory impairments, synaptic dysfunction, and brain pathology. However, it is unknown whether this diet exerts the same effects on normal mice or on other functions, and if so, how. In the present study, mother mice were pre-fed a high sugar and high fat (HSHF) diet for 1 month and then fertilized; the HSHF diet was continued until birth and then mother mice were returned to a standard diet. The gut microbiota, and intestinal and brain functions of the offspring were dynamically monitored at 7, 14, 28, and 56 days old until 16 months of age. Results showed that the HSHF diet significantly affected the gut microbiota structure of the offspring, especially during the early life stage. In addition, in the HSHF diet offspring, there were influenced on various types of neurons, including cholinergic and GABAergic neurons, on autophagy levels in the brain, and on inflammation levels in the intestinal tract. When the offspring grew older (16 months), we found that some genes of benefit against nervous system disease were activated, such as Lhx8, GPR88, RGS9, CD4, DRD2, RXRG, and Syt6, and the expression of cholinergic and GABAergic neurons biomarker protein increased. Although the inflammation levels in the nervous and peripheral systems showed no obvious differences, the AFP level of individuals on the HSHF diet was much higher than those on the standard diet, suggesting that more accurate and/or personalized nutrition is needed. Taken together, the results show that a maternal HSHF diet benefits the offspring by reducing the risk of nervous diseases, which might depend on LHX8 activation to modulate cholinergic and GABAergic neurons via the gut-brain axis, but still need much more deep studies.


Assuntos
Encéfalo/fisiologia , Dieta Hiperlipídica , Açúcares da Dieta , Microbioma Gastrointestinal/fisiologia , Fenômenos Fisiológicos da Nutrição Materna/fisiologia , Efeitos Tardios da Exposição Pré-Natal/metabolismo , Animais , Autofagia/fisiologia , Feminino , Regulação da Expressão Gênica , Camundongos , Gravidez
6.
J Agric Food Chem ; 69(18): 5428-5434, 2021 May 12.
Artigo em Inglês | MEDLINE | ID: mdl-33926188

RESUMO

Emerging and fugitive contaminants (EFCs) can be introduced into the food chain through plants, particularly crop plants, and have threatened food safety and human health. The method for determination of volatile EFCs in plant tissues remains challenging. A new rapid, simple, precise, and accurate freeze-thaw-equilibration followed by head space (HS)-solid-phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS) analytical method was developed in this study for high-throughput analysis of 1,4-dioxane and 1,2,3-trichloropropane (TCP) in tissues of three representative crop plants, corn, wheat, and tomato. The samples were treated by a freeze-thaw procedure, then equilibrated in a saturated sodium sulfate solution, and analyzed by HS-SPME-GC-MS method. Method detection limits ranged from 0.6 to 16 ng/g. The calibration showed good linearity (R2 > 0.9). Recoveries of spiked analytes in the three plant species ranged from 82.69 to 106.3%. The ability of plant uptake of the compounds from soil has been investigated. As demonstrated in this study, this method is used to measure the concentrations of volatile contaminants in the stems of crop plants. This method should also be applicable for other plant tissues and therefore will contribute significantly to the sight of EFC transport in plants and to assess the potential risks EFCs pose to food safety and human health.


Assuntos
Lycopersicon esculentum , Compostos Orgânicos Voláteis , Congelamento , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Microextração em Fase Sólida , Triticum , Compostos Orgânicos Voláteis/análise
8.
J Am Soc Mass Spectrom ; 31(10): 2180-2190, 2020 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-32881526

RESUMO

The increasing use of engineered nanoparticles (ENPs) in many industries has generated significant research interest regarding their impact on the environment and human health. The major routes of ENPs to enter the human body are inhalation, skin contact, and ingestion. Following ingestion, ENPs have a long contact time in the human stomach. Hence, it is essential to know the fate of the ENPs under gastric conditions. This study aims to investigate the fate of the widely used nanoparticles Ag-NP, Au-NP, CeO2-NP, and ZnO-NP in simulated gastric fluid (SGF) under different conditions through the application of single-particle inductively coupled plasma-mass spectrometry (SP-ICP-MS). The resulting analytical methods have size detection limits for Ag-NP, Au-NP, ZnO-NP, and CeO2-NP from 15 to 35 nm, and the particle concentration detection limit is 135 particles/mL. Metal ions corresponding to the ENPs of interest were detected simultaneously with detection limits from 0.02 to 0.1 µg/L. The results showed that ZnO-NPs dissolved completely and rapidly in SGF, whereas Au-NPs and CeO2-NPs showed apparent aggregation and did not dissolve significantly. Both aggregation and dissolution were observed in Ag-NP samples following exposure to SGF. The size distributions and concentrations of ENPs were affected by the original ENP concentration, ENP size, the contact time in SGF, and temperature. This work represents a significant advancement in the understanding of ENP characteristics under gastric conditions.


Assuntos
Cério/análise , Suco Gástrico/química , Ouro/análise , Nanopartículas/análise , Prata/análise , Óxido de Zinco/análise , Humanos , Espectrometria de Massas/métodos , Tamanho da Partícula , Solubilidade
9.
Opt Express ; 28(15): 22064-22075, 2020 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-32752474

RESUMO

Perfect state transfer of the bus topological system enables the sharing of information or excitation between nodes. Herein we report groundbreaking research on the transfer of the graphene-bridged bus topological network structure to an electromagnetic metamaterial setting, named "bus topological network metamaterials (TNMMs)." Correspondingly, the electromagnetic response imprints onto the topological excitation. We find that the bus-TNMMs display a perfect modulation of the terahertz response. The blue-shift of resonance frequency could increase to as large as 1075 GHz. The modulation sensitivity of the bus-TNMMs reaches 1027 GHz/Fermi level unit (FLU). Meanwhile, with the enhancement of modulation, the line shape of the reflection keeps underformed. Parabola, ExpDec1, and Asymptotic models are used to estimate the modulation of the resonance frequency. Besides, the bus-TNMMs system provides a fascinating platform for dynamic cloaking. By governing the Fermi level of graphene, the bus-TNMMs can decide whether it is cloaking or not in a bandwidth of 500 GHz. Also, the bus-TNMMs exhibit the immense potential for dynamically detecting the vibrational fingerprinting of an analyte. These results give a far-reaching outlook for steering dynamically the terahertz response with the bus-TNMMs. Therefore, we believe that the discovery of bus-TNMMs will revolutionize our understanding of the modulation of the electromagnetic response.

10.
Opt Express ; 28(8): 11933-11945, 2020 Apr 13.
Artigo em Inglês | MEDLINE | ID: mdl-32403694

RESUMO

Position-guided Fano resonance is observed in hybrid graphene-silicon metamaterials. An outstanding application of such resonance is slow-light metadevices. The maximum group delay is 9.73 ps, which corresponds to a group delay in free-space propagation of 2.92 mm. We employ a coupled oscillator model to illustrate anomalous transmission, where the intensity of the Fano peak increases with the Fermi level. Furthermore, we amend the GaussAmp model to serve as a suitable control equation for the group delay. The coefficient of correlation (R2) is as high as 0.99998, while the lowest values of the root-mean-square error and sum of squared errors are respectively 0.00421 and 0.00156. These results indicate that the amended GaussAmp model accurately controls the trend of the group delay. This work not only clarifies the mechanism of Fano resonance generation but also provides a promising platform for dynamically adjustable optical switches and multidimensional information sensors.

11.
Nanoscale ; 12(3): 1719-1727, 2020 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-31894802

RESUMO

A multiple mode integrated biosensor based on higher order Fano metamaterials (FRMMs) is proposed. The frequency shifts (Δf) of x-polarized quadrupolar (Qx), octupolar (Ox), hexadecapolar (Hx), y-polarized quadrupolar (Qy) and octupolar (Oy) Fano resonance modes are integrated to detect the concentration of lung cancer cells. In experiments, the concentrations of lung cancer cells can be distinguished by the shape and distribution of integrated graphics. In addition, an anomalous response in Δf in resonant mode is surprisingly observed. As the cell concentration increases, the Δf at the Qx-dip, Qy-dip and Oy-dip successively experiences an increasing frequency shift stage (IFSS), decreasing frequency shift stage (DFSS) and re-increasing frequency shift stage (RIFSS). The extraordinary DFSS confirmed by single-factor analysis of variance (ANOVA) means an unusual physical phenomenon in metamaterial biosensors. By introducing a new dielectric constant εf, we amend perturbation theory to explain the unusual phenomenon in Δf. With the change of the mode order from Qx to Hx, the εf increases from -2.78 to 0.75, which implies that the negative εf leads to the appearance of the DFSS. As a platform for biosensing, this study opens a new window from the perspective of multiple mode integration.


Assuntos
Técnicas Biossensoriais
12.
J Agric Food Chem ; 67(46): 12927-12935, 2019 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-31657558

RESUMO

Emerging and fugitive contaminants (EFCs) released to our biosphere have caused a legacy and continuing threat to human and ecological health, contaminating air, water, and soil. Polluted media are closely linked to food security through plants, especially agricultural crops. However, measuring EFCs in plant tissues remains difficult, and high-throughput screening is a greater challenge. A novel rapid freeze-thaw/centrifugation extraction followed by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) analysis was developed for high-throughput quantification of 11 EFCs with diverse chemical properties, including estriol, codeine, oxazepam, 2,4-dinitrotoluene, 1,3,5-trinitroperhydro-1,3,5-triazine, bisphenol A, triclosan, caffeine, carbamazepine, lincomycin, and DEET, in three representative crops, corn, tomato, and wheat. The internal aqueous solution, i.e., sap, is liberated via a freeze/thaw cycle, and separated from macromolecules utilizing molecular weight cutoff membrane centrifugal filtration. Detection limits ranged from 0.01 µg L-1 to 2.0 µg L-1. Recoveries of spiked analytes in three species ranged from 83.7% to 109%. Developed methods can rapidly screen EFCs in agriculture crops and can assess pollutant distribution at contaminated sites and gain insight on EFCs transport in plants to assess transmembrane migration in vascular organisms. The findings contribute significantly to environmental research, food security, and human health, as it assesses the first step of potential entry into the food chain, that being transmembrane migration and plant uptake, the primary barrier between polluted waters or soils and our food.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Poluentes Ambientais/química , Lycopersicon esculentum/química , Extratos Vegetais/química , Espectrometria de Massas em Tandem/métodos , Triticum/química , Zea mays/química , Centrifugação , Poluentes Ambientais/isolamento & purificação , Filtração , Contaminação de Alimentos/análise , Química Verde/métodos , Ensaios de Triagem em Larga Escala/métodos , Extratos Vegetais/isolamento & purificação
13.
Opt Express ; 27(14): 19520-19529, 2019 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-31503709

RESUMO

A biosensor based on electromagnetically induced transparent (EIT) metamaterials (MMs) is proposed owing to the low loss and high Q-factor. The theoretical sensitivity of the biosensor based on EIT-like MMs were evaluated up to 248.8 GHz/RIU (RIU, Refractive Index Unit). In experiments, the cancer cells A549, as an analyte, are cultured on EIT-like MMs surface. The results show that when the cell concentration increases from 0.5 × 105 to 5 × 105 cells/ml, the frequency shift Δf could change from 24 to 50 GHz. Moreover, the coupled oscillators model is applied to explain the effect of the refractive index of analyte in simulations and the cell concentration in experiments on the EIT-like MMs. The fitting results exhibit that the refractive index of analyte and cell concentration significantly affect the radiative damping of the bright mode resonator γ1. The proposed EIT-like MMs biosensors show great potentials for cell measurement because any change that results in the lineshape variation in EIT-like MMs can only be attributed to the change of external dielectric environment due to the suppression of radiative losses.


Assuntos
Neoplasias Pulmonares/patologia , Técnicas Biossensoriais , Linhagem Celular Tumoral , Eletricidade , Campos Eletromagnéticos , Humanos , Refratometria
14.
Appl Opt ; 58(23): 6268-6273, 2019 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-31503769

RESUMO

In this paper, we have cultured normal epithelial cells (HaCaT) as analytes to detect the sensitivity of a biosensor based on Fano resonance metamaterials (FRMMs). The frequency shift Δf of the transmission spectrum was experimentally measured at three different concentrations (0.2×105, 0.5×105, and 5×105 cell/ml) of HaCaT cells. By employing the FRMMs-based biosensor, the detection concentration of HaCaT cells can approximately arrive at 0.2×105 cell/ml; further, the corresponding Δf is 25 GHz, which reaches the measurement limit of the THz-TDS system. Additionally, the increase of HaCaT cell concentration causes a different redshift of Δf from 24-50 GHz, and the maximum of Δf can reach 50 GHz when the HaCaT cell concentration is at 5×105 cell/ml. Similarly, the simulated results show that the Δf depends on the numbers of analytes with a semiball shape and the refractive index of analytes. The theoretical sensitivity was calculated to be 481 GHz/RIU. The proposed FRMMs-based biosensor paves a fascinating platform for biological and biomedical applications and may become a valuable complementary reference for traditional biological research.


Assuntos
Técnicas Biossensoriais , Células Epiteliais/citologia , Fenômenos Ópticos , Simulação por Computador , Humanos
15.
Anal Bioanal Chem ; 411(21): 5531-5543, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31201458

RESUMO

Single cell-inductively coupled plasma-mass spectrometry (SC-ICP-MS) is an emerging technology. In this work, we have developed a novel SC-ICP-MS method to quantify metal ions in individual cells of a toxic cyanobacterial species, Microcystis aeruginosa (M. aeruginosa), without complicated post-dosing sample preparation, and applied this method to study the treatment effectiveness of copper-based algaecides (cupric sulfate and EarthTec®) on the toxic algae M. aeruginosa. The developed SC-ICP-MS method uses new intrinsic metal element magnesium to determine real transport efficiency and cell concentration. The cell viability and microcystin-LR release by algaecide treatment were studied by flow cytometry and ultra-fast liquid chromatography-tandem mass spectrometry, respectively. The results showed that this novel method was very rapid, highly sensitive (detection limits of intracellular copper and magnesium were 65 ag/cell and 98 ag/cell, respectively), and reproducible (relative standard deviation within 12%). The algaecide effectiveness study further demonstrated that copper in the forms of cupric sulfate and copper-based algaecide EarthTec® successfully diminished M. aeruginosa populations. The higher the copper concentration used to treat the cells, the faster the speeds of copper uptake and cell lysis in the copper concentrations ranged from 0 to 200 µg/L of copper-based algaecide. The cells exhibit obvious heterogeneity in copper uptake. The result suggests that M. aeruginosa cells uptake and cumulate copper followed by cellular lysis and microcystin-LR release. These novel results indicated that though the copper-based algaecides could control this type of harmful algal bloom, further treatment to remove the released algal toxin from the treated water would be needed. Graphical abstract.


Assuntos
Cobre/química , Herbicidas/farmacologia , Microcystis/efeitos dos fármacos , Espectrometria de Massas em Tandem/métodos , Cromatografia Líquida/métodos , Cobre/análise , Cobre/metabolismo , Citometria de Fluxo , Herbicidas/análise , Herbicidas/química , Limite de Detecção , Reprodutibilidade dos Testes
16.
J Environ Sci (China) ; 64: 82-91, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29478664

RESUMO

When adding sufficient chlorine to achieve breakpoint chlorination to source water containing high concentration of ammonia during drinking water treatment, high concentrations of disinfection by-products (DBPs) may form. If N-nitrosamine precursors are present, highly toxic N-nitrosamines, primarily N-nitrosodimethylamine (NDMA), may also form. Removing their precursors before disinfection should be a more effective way to minimize these DBPs formation. In this study, zeolites and activated carbon were examined for ammonia and N-nitrosamine precursor removal when incorporated into drinking water treatment processes. The test results indicate that Mordenite zeolite can remove ammonia and five of seven N-nitrosamine precursors efficiently by single step adsorption test. The practical applicability was evaluated by simulation of typical drinking water treatment processes using six-gang stirring system. The Mordenite zeolite was applied at the steps of lime softening, alum coagulation, and alum coagulation with powdered activated carbon (PAC) sorption. While the lime softening process resulted in poor zeolite performance, alum coagulation did not impact ammonia and N-nitrosamine precursor removal. During alum coagulation, more than 67% ammonia and 70%-100% N-nitrosamine precursors were removed by Mordenite zeolite (except 3-(dimethylaminomethyl)indole (DMAI) and 4-dimethylaminoantipyrine (DMAP)). PAC effectively removed DMAI and DMAP when added during alum coagulation. A combination of the zeolite and PAC selected efficiently removed ammonia and all tested seven N-nitrosamine precursors (dimethylamine (DMA), ethylmethylamine (EMA), diethylamine (DEA), dipropylamine (DPA), trimethylamine (TMA), DMAP, and DMAI) during the alum coagulation process.


Assuntos
Amônia/análise , Nitrosaminas/análise , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Adsorção , Compostos de Alúmen , Amônia/química , Carvão Vegetal/química , Dimetilnitrosamina , Desinfecção , Água Potável , Nitrosaminas/química , Poluentes Químicos da Água/química , Zeolitas/química
17.
ACS Appl Mater Interfaces ; 9(37): 32001-32007, 2017 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-28853277

RESUMO

A strategy to fabricate an ambipolar near-infrared vertical photodetector (VPD) by sandwiching a photoactive material as a channel film between the bottom graphene and top metal electrodes was developed. The channel length in the vertical architecture was determined by the channel layer thickness, which can provide an ultrashort channel length without the need for a high-precision manufacturing process. The performance of VPDs with two types of semiconductor layers, a graphene-PbS quantum dot hybrid (GQDH) and PbS quantum dots (QDs), was measured. The GQDH VPD showed better photoelectric properties than the QD VPD because of the high mobility of graphene doped in the channel. The GQDH VPD exhibited excellent photoresponse properties with a responsivity of 1.6 × 104 A/W in the p-type regime and a fast response speed with a rise time of 8 ms. The simple manufacture and the promising photoresponse of the GQDH VPDs reveal that an easy and effective way to fabricate high-performance ambipolar photodetectors was developed.

18.
Chemosphere ; 181: 562-568, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28463731

RESUMO

In this research, the release and degradation of intracellular microcystin-LR (MC-LR) due to oxidation of Microcystis aeruginosa (M. aeruginosa) was examined kinetically. Brief exposure to free chlorine with no measureable oxidant exposure was demonstrated to be sufficient to induce rapid release of intracellular MC-LR from M. aeruginosa. Thus, in a water treatment plant, there is currently no level of prechlorination that can be assumed to be safe, since very low preoxidation prior to filtration and no measureable free chlorine residual may still observe the release and buildup of extracellular MC-LR. Higher chlorine dosages resulting in a measureable exposure or CT (concentration times contact time) cause more rapid release and oxidation of the intracellular toxins. Further, the rate of release of MC-LR with intermediate oxidant dosages were shown to be initially rapid, but then slowed to a lower release rate due to an as yet undetermined mechanism. While free chlorine was reactive with the extracellular MC-LR, the monochloramine resulting from the consumption of the free chlorine by ammonia was not. Consideration of the ammonia concentration and the chlorine dosage relative to the chlorination breakpoint dosages is important for utilities assessing the impact of prechlorination of water containing cyanobacteria. MC-LR, once released, was rapidly oxidized by permanganate resulting in only negligible buildup of extracellular toxins.


Assuntos
Microcistinas/metabolismo , Microcystis/metabolismo , Oxidantes/metabolismo , Cloro/farmacologia , Cianobactérias , Halogenação , Compostos de Manganês/farmacologia , Toxinas Marinhas , Oxidantes/farmacologia , Oxirredução , Óxidos/farmacologia , Microbiologia da Água , Purificação da Água/métodos
19.
Nanotechnology ; 28(24): 245202, 2017 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-28319039

RESUMO

Graphene quantum dots (GQDs) have received much research attention, because of their useful structure and optical absorption/emission. We report the tunable amplified spontaneous emission (ASE) in GQD-doped cholesteric liquid crystal (CLC), which to the best of our knowledge has not been previously observed. The GQDs are uniformly dispersed with a weight ratio of 0.5 wt.% in CLC. Under optical excitation, typical ASE is triggered in the system at pump energies greater than 1.25 mJ cm-2. The emission peak at the long wavelength edge of the photonic bandgap shifts from 662 to 669 nm, as the working temperature is increased from 50 to 90 °C. The preparation of the combined GQDs and CLC is simple and low-cost, and the resulting material is photostable and non-toxic. Combining the GQD gain material with the self-assembled CLC resonator has potential in the fabrication of ASE source and laser devices.

20.
Nanotechnology ; 28(14): 145201, 2017 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-28184032

RESUMO

A field-effect phototransistor based on a graphene and lead sulfide quantum dot (PbS QD) hybrid in which PbS QDs are embedded in a graphene matrix has been fabricated with a vertical architecture through a solution process. The n-type Si/SiO2 substrate (gate), Au/Ag nanowire transparent source electrode, active layer and Au drain electrode are vertically stacked in the device, which has a downscaled channel length of 250 nm. Photoinduced electrons in the PbS QDs leap into the conduction band and fill in the trap states, while the photoinduced holes left in the valence band transfer to the graphene and form the photocurrent under biases from which the photoconductive gain is evaluated. The graphene/QD-based vertical phototransistor shows a photoresponsivity of 2 × 103 A W-1, and specific detectivity up to 7 × 1012 Jones under 808 nm laser illumination with a light irradiance of 12 mW cm-2. The solution-processed vertical phototransistor provides a new facile method for optoelectronic device applications.

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