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1.
Artículo en Inglés | MEDLINE | ID: mdl-39017866

RESUMEN

Ribavirin (RBV), which is extensively used to treat viral diseases such as COVID-19, is considered one of the major emerging contaminants due to its long-term existence and health risk in the aqueous environmental system. However, research on effective removal of RBV still remains insufficient. In this study, we investigated the RBV degradation kinetics and mechanism in UV/chlorine/Fe(II) process. The degradation rate constant kobs-RBV of RBV was 2.52 × 10-4 s-1 in UV/chlorine/Fe(II) process, which increased by 1.6 times and 1.3 times than that in chlorine alone and UV/chlorine process, respectively. Notably, trace amount Fe(II) promoted RBV degradation in UV/chlorine system through Fe2+/Fe3+ cycles, enhancing the yield of reactive species such as HO· and certain species reactive chlorine radicals (RCS). The contributions of HO· and RCS toward RBV degradation were 53.91% and 16.11%, respectively. Specifically, Cl·, ClO·, and Cl2·- were responsible for 8.59%, 2.69%, and 4.83% of RBV removal. The RBV degradation pathway indicated that the reactive species preferentially attacked the amide moiety of RBV, which cleaved the ether bond and the hydroxyl group. The toxicity evaluation of RBV degradation products elucidated that UV/chlorine/Fe(II) process was beneficial for RBV detoxification.

2.
Open Life Sci ; 19(1): 20220882, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38911928

RESUMEN

A pot experiment was conducted to investigate the combined effects of different nitrogen fertilizer levels (5, 25, and 45 kg of pure nitrogen per 667 m²) and biochar concentrations (0, 0.7, 1.4, and 2.1%) on the growth, yield, and fruit quality of pepper. The findings indicated that a combination of 25 kg/667 m2 of nitrogen and either 0.7% or 1.4% biochar significantly enhanced plant growth, yield, and fruit quality. Specifically, the N2 treatment (25 kg of pure nitrogen per 667 m²) increased substrate porosity, alkali-hydrolyzed nitrogen content, and available phosphorus content. It also boosted root activity and superoxide dismutase activity in pepper leaves, resulting in increased yield and better fruit quality. Furthermore, the proper addition of biochar (0.7-1.4% by weight) enhanced the physical and chemical properties of the substrate, including increased chlorophyll content and enzyme activity in plants, thereby leading to improved overall plant growth, yield, and fruit quality.

3.
Biomater Sci ; 2024 Jun 20.
Artículo en Inglés | MEDLINE | ID: mdl-38899957

RESUMEN

Non-healing diabetic wounds often culminate in amputation and mortality. The main pathophysiological features in diabetic wounds involve the accumulation of M1-type macrophages and excessive oxidative stress. In this study, we engineered a nano-enzyme functionalized hydrogel by incorporating a magnesium ion-doped molybdenum-based polymetallic oxide (Mg-POM), a novel bioactive nano-enzyme, into a GelMA hydrogel, to obtain the GelMA@Mg-POM system to enhance diabetic wound healing. GelMA@Mg-POM was crosslinked using UV light, yielding a hydrogel with a uniformly porous three-dimensional mesh structure. In vitro experiments showed that GelMA@Mg-POM extraction significantly enhanced human umbilical vein endothelial cell (HUVEC) migration, scavenged ROS, improved the inflammatory microenvironment, induced macrophage reprogramming towards M2, and promoted HUVEC regeneration of CD31 and fibroblast regeneration of type I collagen. In in vivo experiments, diabetic rat wounds treated with GelMA@Mg-POM displayed enhanced granulation tissue genesis and collagen production, as evidenced by HE and Masson staining. Immunohistochemistry demonstrated the ability of GelMA@Mg-POM to mitigate macrophage-associated inflammatory responses and promote angiogenesis. Overall, these findings suggest that GelMA@Mg-POM holds significant promise as a biomaterial for treating diabetic wounds.

4.
Water Res ; 256: 121611, 2024 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-38640567

RESUMEN

Natural small molecular organic matter (NSOM), ubiquitous in natural waters and distinct from humic acid or fulvic acid, is a special type of dissolved organic matter (DOM) which is characterized as strong photosensitivity and simple molecular structure. However, little study had been directed on the role of NSOM in eliminating emerging contaminants in advanced reduction process (ARP). This study took three small molecular isomeric organic acids (p-hydroxybenzoic acid, pHBA; salicylic acid, SA; m-hydroxybenzoic acid, mHBA) as the representative substances of NSOM to explore these mechanisms on promoting Ribavirin (RBV, an anti COVID-19 medicine) degradation in ultraviolet activated sulfite (UV/Sulfite) process. The results demonstrated that the observed degradation rate constant of RBV (kobs-RBV) was 7.56 × 10-6 s-1 in UV/Sulfite process, indicating that hydrated electron (eaq-) from UV/Sulfite process could not effectively degrade RBV, while it increased by 178 and 38 times when pHBA and SA were introduced into UV/Sulfite process respectively, suggesting that pHBA and SA strongly promoted RBV degradation while mHBA had no promotion on RBV abatement in UV/Sulfite process. Transient absorption spectra and reactive intermediates scavenging experiment indicated that the triplet excited state pHBA and SA (3pHBA* and 3SA*) contributed to the degradation of RBV through non-radical process. Notably, eaq- played the role of key initiator in transforming pHBA and SA into their triplet states. The difference of kobs-RBV in UV/Sulfite/pHBA and UV/Sulfite/SA process was attributed to different generation pathways of 3pHBA* and 3SA* (high molar absorptivity at the wavelength of 254 nm and photosensitive cycle, respectively) and their second order rate constants towards RBV (kRBV-3pHBA* = 8.60 × 108 M-1 s-1 and kRBV-3SA* = 6.81 × 107 M-1 s-1). mHBA could not degrade RBV for its lack of intramolecular hydrogen bond and low molar absorptivity at 254 nm to abundantly transform into its triplet state. kobs-RBV increased as pH increased from 5.0 to 11.0 in UV/Sulfite/SA process, due to the high yield of eaq- in alkaline condition which promoted the generation of 3SA* and the stable of the absorbance of SA at 254 nm. By contrast, kobs-RBV underwent a process of first increasing and then decreasing in UV/Sulfite/pHBA process as the increase of pH, and its highest value achieved in a neutral condition. This lied in the exposure of eaq- increased as the increase of pH which promoted the generation of 3pHBA*, while the molar absorptivity of pHBA at 254 nm decreased as the increase of pH in an alkaline condition which inhibited the yield of 3pHBA*. The RBV degradation pathways and products toxicity assessment indicated that UV/Sulfite/pHBA had better detoxification performance on RBV than UV/Sulfite/SA process. This study disclosed a novel mechanism of emerging contaminants abatement through non-radical process in NSOM mediated ARP, and provide a wide insight into positive profile of DOM in water treatment process, instead of only taking DOM as a quencher of reactive intermediates.


Asunto(s)
Antivirales , Antivirales/química , Rayos Ultravioleta , Sulfitos/química
5.
Micromachines (Basel) ; 15(3)2024 Feb 28.
Artículo en Inglés | MEDLINE | ID: mdl-38542585

RESUMEN

Technological advancements across various sectors are driving a growing demand for large-scale three-degree-of-freedom micro-nano positioning platforms, with substantial pressure to reduce footprints while enhancing motion range and accuracy. This study proposes a three-prismatic-revolute-revolute (3-PRR) parallel mechanism based on biomimetic variable-diameter helical flexible hinges. The resulting platform achieves high-precision planar motion along the X- and Y-axes, a centimeter-level translation range, and a rotational range of 35° around the Z-axis by integrating six variable-diameter flexible helical hinges that serve as rotational joints when actuated by three miniature linear servo drives. The drives are directly connected to the moving platform, thereby enhancing the compactness of the system. A kinematic model of the motion platform was established, and the accuracy and effectiveness of the forward and inverse kinematic solutions were validated using finite element analysis. Finally, a prototype of the 3-PRR parallel platform was fabricated, and its kinematic performance was experimentally verified visually for improved endpoint displacement detection. The assessment results revealed a maximum displacement error of 9.5% and confirmed that, judging by its favorable workspace-to-footprint ratio, the final system is significantly more compact than those reported in the literature.

6.
Acta Trop ; 254: 107188, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38531428

RESUMEN

Cryptosporidium spp. and G. duodenalis often infect humans, cats, and other mammals, causing diarrhea and being responsible for numerous outbreaks of waterborne and foodborne infections worldwide. The rapid increase in the number of pet cats poses a substantial public health risk. However, there were few reports about the infection of Cryptosporidium spp. and G. duodenalis infections in pet cats in Henan Province, central China. Thus, to understand the prevalence and genetic distribution of Cryptosporidium spp. and G. duodenalis in pet cats, and to evaluate the zoonotic potential, possible transmission routes and public health implications of isolates, fecal samples (n = 898) were randomly collected from pet cats in 11 cities in Henan Province, central China. Nested PCR based on the SSU rRNA gene and bg gene was used to the prevalence of Cryptosporidium spp. and G. duodenalis, respectively. The prevalence was 0.8 % (7/898) and 2.0 % (18/898) for Cryptosporidium spp. and G. duodenalis respectively. Additionally, the Cryptosporidium spp. positive isolates were identified as C. parvum subtype IIdA19G1 by gp60 gene. In the present study, the IIdA19G1 subtype was discovered in pet cats for the first time in China, enriching the information on the host type and geographical distribution of Cryptosporidium spp. in China. For G. duodenalis, a total of 18 G. duodenalis positive samples were identified, belonging to four assemblages: a zoonotic assemblage A1 (4/898), three host-specific assemblages C (8/898), D (5/898), and F (1/898). Interestingly, we found that pet cats infected with Cryptosporidium spp. and G. duodenalis are more likely to experience emaciation symptoms compared to the negative group. More importantly, the prevalence of Cryptosporidium spp. and G. duodenalis detected in the present study were low, but the subtype IIdA19G1 of Cryptosporidium spp. and the assemblages A1, C, D, and F of G. duodenalis have the potential for zoonotic transmission. Thus, we should focus on preventing and controlling the risk of cross-species transmission that may occur in pet cats in Henan Province.


Asunto(s)
Enfermedades de los Gatos , Criptosporidiosis , Cryptosporidium , Heces , Giardia lamblia , Giardiasis , Mascotas , Animales , Gatos , China/epidemiología , Criptosporidiosis/epidemiología , Criptosporidiosis/parasitología , Criptosporidiosis/transmisión , Enfermedades de los Gatos/parasitología , Enfermedades de los Gatos/epidemiología , Cryptosporidium/genética , Cryptosporidium/aislamiento & purificación , Cryptosporidium/clasificación , Heces/parasitología , Giardia lamblia/genética , Giardia lamblia/aislamiento & purificación , Giardia lamblia/clasificación , Mascotas/parasitología , Prevalencia , Giardiasis/epidemiología , Giardiasis/veterinaria , Giardiasis/parasitología , Giardiasis/transmisión , ADN Protozoario/genética , Filogenia , Reacción en Cadena de la Polimerasa , Genotipo , Zoonosis/parasitología , Zoonosis/epidemiología , Zoonosis/transmisión
7.
Clin Nutr ; 43(2): 453-467, 2024 02.
Artículo en Inglés | MEDLINE | ID: mdl-38181523

RESUMEN

BACKGROUND & AIMS: Short-term intensive fasting (STIF), known as beego in Chinese phonetic articulation, has been practiced for more than two thousand years. However, the potential risk of STIF and the body's response to the risk have not been adequately evaluated. This study aims to address this issue, focusing on the STIF-triggered metabolic response of the liver and kidney. METHODS: The STIF procedure in the clinical trial includes a 7-day water-only intensive fasting phase and a 7-day gradual refeeding phase followed by a regular diet. The intensive fasting in humans was assisted with psychological induction. To gain insights not available in the clinical trial, we designed a STIF program for mice that resulted in similar phenotypes seen in humans. Plasma metabolic profiling and examination of gene expression as well as liver and kidney function were performed by omics, molecular, biochemical and flow cytometric analyses. A human cell line model was also used for mechanistic study. RESULTS: Clinically significant metabolites of fat and protein were found to accumulate during the fasting phase, but they were relieved after gradual refeeding. Metabolomics profiling revealed a universal pattern in the consumption of metabolic intermediates, in which pyruvate and succinate are the two key metabolites during STIF. In the STIF mouse model, the accumulation of metabolites was mostly counteracted by the upregulation of catabolic enzymes in the liver, which was validated in a human cell model. Kidney filtration function was partially affected by STIF but could be recovered by refeeding. STIF also reduced oxidative and inflammatory levels in the liver and kidney. Moreover, STIF improved lipid metabolism in mice with fatty liver without causing accumulation of metabolites after STIF. CONCLUSIONS: The accumulation of metabolites induced by STIF can be relieved by spontaneous upregulation of catabolic enzymes, suggesting an adaptive and protective metabolic response to STIF stress in the mammalian body.


Asunto(s)
Dieta , Ayuno , Ratones , Humanos , Animales , Hígado/metabolismo , Metabolismo de los Lípidos , Mamíferos
8.
Head Face Med ; 19(1): 25, 2023 Jun 29.
Artículo en Inglés | MEDLINE | ID: mdl-37386479

RESUMEN

PURPOSE: This study compares the observation efficiency of brain gray matter nuclei of patients with early-stage Parkinson's disease among various Magnetic Resonance Imaging techniques, which include susceptibility weighted imaging (SWI), quantitative susceptibility imaging (QSM), diffusion tensor imaging (DTI) and diffusion kurtosis imaging (DKI). Based on the findings, this study suggests an efficient combination of scanning techniques for brain gray matter nuclei observation, aiming to provide an opportunity to advance the understanding of clinical diagnosis of early-stage Parkinson's disease. METHODS: Forty examinees, including twenty patients who were clinically diagnosed with early Parkinson's disease with a course of 0.5-6 years (PD group) and twenty healthy controls (HC group), underwent head MRI examination. Philips 3.0T (tesla) MR machine was used to measure the imaging indexes of gray matter nuclei in patients with early Parkinson's disease. SWI, QSM, DTI and DKI were used for diagnosis. SPSS (Statistical Product and Service Solutions) 21.0 was used for data analysis. RESULTS: When SWI was used, fifteen PD patients and six healthy volunteers were diagnosed correctly. The sensitivity, specificity, positive predictive value, negative predictive value and diagnostic coincidence rate about the diagnosis of nigrosome-1 on imaging were 75.0%, 30.0%, 51.7%, 54.5% and 52.5% respectively. By contrast, when QSM was used, 19 PD patients and 11 healthy volunteers were diagnosed correctly. The sensitivity, specificity, positive predictive value, negative predictive value and diagnostic coincidence rate about the diagnosis of Nigrosome-one on imaging were 95.0%, 55.0%, 67.9%, 91.7% and 75.0% respectively. The mean kurtosis (MK) value within both the substantia nigra and thalamus, together with the mean diffusivity (MD) within both the substantia nigra and the head of caudate nucleus in PD group was greater than that of HC group. The susceptibility values within the substantia nigra, red nucleus, head of caudate nucleus and putamen of PD group was greater than that of HC group. The MD value in substantia nigra reveals the optimal diagnostic efficiency to distinguish the HC group and the PD group, followed by the MK value in substantia nigra. Specifically, the maximum area under ROC curve (AUC) of the MD value was 0.823, the sensitivity 70.0%, the specificity 85.0%, and the diagnostic threshold 0.414. The area under ROC curve (AUC) of the MK value was 0.695, the sensitivity 95.0%, the specificity 50.0%, and the diagnostic threshold was 0.667. Both of them were statistically significant. CONCLUSIONS: In the early diagnosis of Parkinson's disease, QSM is more efficient than SWI in observing nigrosome-1 in substantia nigra. In the early diagnosis of Parkinson's disease, MD and MK values of substantia nigra in DKI parameters have higher diagnostic efficiency. The combined scanning of DKI and QSM has the highest diagnostic efficiency and provides imaging basis for clinical diagnosis of early Parkinson's disease.


Asunto(s)
Imagen de Difusión Tensora , Enfermedad de Parkinson , Humanos , Sustancia Gris/diagnóstico por imagen , Enfermedad de Parkinson/diagnóstico por imagen , Imagen por Resonancia Magnética , Voluntarios Sanos
9.
Front Public Health ; 11: 1110893, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-36935704

RESUMEN

Objective: The aim of this study was to investigate the knowledge, attitude, and practice (KAP) of medical workers in the radiology department toward the prevention and diagnosis of COVID-19. Methods: This multicenter cross-sectional study was conducted among medical workers in the radiology department of 17 hospitals between March and June 2022. Results: A total of 324 medical workers were enrolled. The mean knowledge scores were 15.3 ± 3.4 (out of 23), attitude scores were 31.1 ± 5.6 (range 8-40), and practice scores were 35.1 ± 4.4 (range 8-40). Positive attitudes (OR = 1.235, 95% CI: 1.162-1.311, P < 0.001) and aged 41-50 years were independently associated with higher practice scores. Those with the better practice were more likely to be older (OR = 2.603, 95% CI: 1.242-5.452, P = 0.011), nurses (OR = 2.274, 95% CI: 1.210-4.272, P = 0.011) and with junior/intermediary/vice-senior title (OR = 2.326, 95% CI: 1.030-5.255, P = 0.042; OR = 2.847, 95% CI: 1.226-6.606, P = 0.015; OR = 4.547, 95% CI: 1.806-11.452, P = 0.001, respectively). Subgroup analysis revealed significant differences in knowledge between technicians and physicians and nurses and between staff working in tertiary hospitals and non-tertiary hospitals. Knowledge is positively correlated with attitude (ß = 0.54, P < 0.001), and attitude is positively correlated with practice (ß = 0.37, P < 0.001). Attitudes significantly mediated the association between knowledge and practice (ß = 0.119, P < 0.001). Conclusion: The radiology medical workers showed moderate knowledge but good attitudes and practices of prevention and diagnosis of COVID-19. Attitudes were found to be positively associated with better practices of prevention and diagnosis of COVID-19. Attitudes significantly mediated the association between knowledge and practice.


Asunto(s)
COVID-19 , Humanos , COVID-19/diagnóstico , COVID-19/prevención & control , Estudios Transversales , Conocimientos, Actitudes y Práctica en Salud , Encuestas y Cuestionarios , China , Prueba de COVID-19
10.
Environ Sci Pollut Res Int ; 30(18): 54149-54159, 2023 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-36869175

RESUMEN

In this study, the sludge-based biochar (BC) was prepared by dewatered sludge from a membrane bioreactor to treat the membrane concentrate. Then, the adsorbed and saturated BC was regenerated (RBC) by pyrolysis and deashing treatment to further treat the membrane concentrate. Afterward, the composition of membrane concentrate before and after BC or RBC treatment was detected, and the biochars' surface characteristics were characterized. The results showed that RBC outperformed BC in the abatement of chemical oxygen demand (CODCr), ammonia nitrogen (NH3-N), and total nitrogen (TN), with their removal rates of 60.07%, 51.55%, and 66.00%, respectively, an improvement of 9.49%, 9.00% and 16.50% of the removal rate compare to BC. The specific surface area of BC and RBC was about 109 times as much as the original dewatered sludge, and the pore size of BC and RBC belonged to mesopore which was a benefit for removing small and mediate size pollutants. The increase of the oxygen-containing functional group in RBC and the ash abatement contributed much to the improvement of RBC adsorption performance. In addition, cost analysis showed that BC+RBC had a cost of 0.76$/kg for COD removal, which was a lower cost than other common membrane concentrate treatment technologies.


Asunto(s)
Aguas del Alcantarillado , Contaminantes Químicos del Agua , Contaminantes Químicos del Agua/análisis , Adsorción , Carbón Orgánico/química , Nitrógeno/análisis
11.
J Environ Chem Eng ; 10(6): 108641, 2022 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-36186959

RESUMEN

Chloroquine Phosphate (CP) is an antiviral drug used for treatment of COVID-19. It is released into wastewater and eventually contaminates natural water. This study reports an effective homogeneous catalysis way for CP degradation by the 2,2,6,6-Tetramethylpiperidine-N-oxyl (TEMPO) enhanced persulfate (PDS) activation under UVB-LEDs irradiation at 305 nm. TEMPO at a low concentration (0.1 µM) enhanced CP degradation in UV305/PDS process in deionized water at different pHs, in different anions and different molecular weight dissolved organic matter solutions and in real surface water. The enhancement was verified to be attributed to the electron shuttle role of TEMPO, which promoted the yield of SO4 •- by enhancing electron donating capacity of the reacting system. The degradation products of CP and their acute toxicities suggested that UV305/PDS/TEMPO process has better performance on CP detoxification than UV305/PDS process. This study provides a new way to tackle the challenge of pharmaceutical pollutions in homogeneous photocatalysis process for natural water and sewage restoration.

12.
Appl Catal B ; 317: 121709, 2022 Nov 15.
Artículo en Inglés | MEDLINE | ID: mdl-35812172

RESUMEN

Ribavirin (RBV) is an antiviral drug used for treating COVID-19 infection. Its release into natural waters would threaten the health of aquatic ecosystem. This study reports an effective approach to degrade RBV by the trace N-oxyl compounds (2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) and N-Hydroxyphthalimide (NHPI)) enhanced UV activated free chlorine (UV/Chlorine) process. The results indicated that TEMPO and NHPI at low concentrations (0.1 µM and 1 µM, respectively) could strongly enhance RBV degradation in both deionized water with different pHs and practical surface water. The enhancement was verified to be attributed to the transformation of TEMPO and NHPI into their reactive forms (i.e., TEMPO+ and PINO), which generations deeply relied on radicals. The two N-oxyl compounds inhibit ClO• yield by hindering the reaction of free chlorine vs. HO• and Cl•. The analyses on acute toxicities of RBV degradation products indicate that UV/Chlorine/N-oxyl compounds process can detoxify RBV more efficiently than UV/Chlorine process.

13.
Chemosphere ; 292: 133425, 2022 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-34954195

RESUMEN

Microplastics (MPs) are emerging pollutants that have gained much attention due to their potential harm to aquatic ecosystems and organisms. In particular, MP conjugates are loaded with chemical contaminants (e.g., atrazine pesticide), which may be ingested by organisms and can pose higher risks. However, the combined pollution effects and interaction mechanisms remain poorly understood. In this study, we systematically explored the adsorption behaviors and mechanisms of atrazine (ATZ) on pristine and aged MPs using kinetics, isotherms, and thermodynamic models. The target MPs included polystyrene (PS), polyethylene (PE), and polypropylene (PP) as well as the corresponding aged types. Moreover, the effects of pH, humic acid (HA), ionic strength, and ion species (Cl-, SO42-, HCO3-, Mg2+, and Ca2+) of aqueous factors were evaluated. The adsorption capacities of MPs under kinetic equilibrium conditions were as follows: aged PE (0.940 mg g-1) > aged PP (0.677 mg g-1) > aged PS (0.663 mg g-1) > PS (0.565 mg g-1) > PE (0.535 mg g-1) > PP (0.410 mg g-1). The adsorption kinetics and isotherm model results suggested a combination of physisorption and chemisorption. The aging process and pH significantly affected the intrinsic charge on the surface of the MPs and their adsorption capacities. Moreover, the presence of water medium parameters might enhance or inhibit adsorption of different MPs. Hydrophobic and electrostatic attraction mainly contributed to the adsorption of ATZ on pristine MPs, whereas complex surface diffusion and hydrogen bonding dominated the ATZ adsorption on aged MPs with more oxygen-containing groups. In addition, we examined the desorption performance of ATZ from MPs under simulated gastric and intestinal conditions of warm-blooded animals, and found that the ATZ desorption ratio of aged PE (35.3%) showed the most significant effects among the six target types of MPs. This study provides in-depth insights into the co-existence and complex behaviors of MPs and the pesticide pollutant ATZ, to attract further attention to their ecological risks in freshwater environments.


Asunto(s)
Atrazina , Contaminantes Químicos del Agua , Adsorción , Ecosistema , Cinética , Microplásticos , Plásticos , Termodinámica , Contaminantes Químicos del Agua/análisis
14.
Opt Lett ; 46(18): 4462-4465, 2021 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-34525022

RESUMEN

We theoretically demonstrate a novel, to the best of our knowledge, mechanism for dark pulse excitation in normal dispersion microresonators exploiting free carrier dispersion and free carrier absorption effects due to multi-photon absorption. Dark pulses can be generated in the three- and four-photon absorption regimes in the presence or absence of external reverse bias to control the lifetime of free carriers, respectively. Direct generation of dark pulses is proven to be feasible in both regimes with a frequency fixed laser. The dynamics of their temporal and spectral evolution have also been investigated. Our findings establish a reliable path for dark pulse and Kerr microcomb generation in related platforms with simplified controlling and tuning techniques.

15.
Water Res ; 193: 116893, 2021 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-33582494

RESUMEN

Microcystin-LR (MC-LR), a polypeptide toxin generated by cyanobacteria, threatens the safety of drinking water supplies. In this study, fulvic acid (FA) was separated into two molecular weight (MW) ranges to evaluate the effects of FA size on MC-LR degradation in the chlorine/UV process. The rates of MC-LR degradation were significantly reduced in FA-containing water (3.7 × 10-3 s-1 for small MW FA; 4.3 × 10-3 s-1 for large MW FA) as compared with FA free water (4.9 × 10-3 s-1). The contributions of ClO• to MC-LR degradation were dramatically lower in small MW FA water (0.4%) than large MW FA (13.9%) and FA free water (17.4%), suggesting inhibition by lignin-like substances in FA in the transformation of Cl• to ClO• and scavenging ClO•. Monochlorination and hydroxylation occurred in the first step of the MC-LR degradation process. The accumulation of intermediate products in the chlorine/UV process indicated that small MW FA inhibited further degradation of MC-LR. Small MW FA, rather than MC-LR degradation, was the dominant factor in minimizing MC-LR cytotoxicity toward a human intestinal epithelial cell line.


Asunto(s)
Cloro , Microcistinas , Benzopiranos , Humanos , Toxinas Marinas , Fotólisis
16.
Environ Sci Pollut Res Int ; 28(13): 16816-16829, 2021 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-33394393

RESUMEN

Tourism activities have brought overexploitation of natural ecotourism resources and ecological pressure challenge though it exactly contributes to the economic prosperity of a region. Research on tourism ecological safety is of great importance for tourist destinations to balance the relationship between environmental protection and tourism development. Qilian Mountains National Park (QMNP) has a prominent ecological status and is a vital ecological barrier in the northwest of China, which attracts large numbers of tourists every year for its rich tourism resources in the Zhangye (ZY) region. However, there is still a lack of systematic research on the environmental impact of tourism activities and on achieving sustainable development of ecotourism in national parks. We took QMNP-ZY as the study object, establishing the system of indicators based on the PSR model for the comprehensive evaluation of tourism ecological safety and the diagnosis of the main obstacles. Moreover, the autoregressive integrated moving average (ARIMA) model was introduced to forecast the evolutionary trends of tourism ecological security in QMNP-ZY. The results showed that (1) The tourism ecological security composite values of the QMNP-ZY exhibited a "U"-type evolution of "first fall-then rise" feature, and the pressure layer gradually became the dominant factor. (2) For the main barrier factors, there had been a shift from response factors. (3)The output of the ARIMA model demonstrated that the level of tourism ecological security would rise in a short period and then decline a few years later. Especially, the contribution degree of economic to the tourism eco-security development will weaken with the region's economy growing.


Asunto(s)
Parques Recreativos , Turismo , China , Conservación de los Recursos Naturales , Ecosistema , Recursos Naturales
17.
Chemosphere ; 209: 96-103, 2018 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-29913404

RESUMEN

Microcystins (MCs), produced by cyanobacterial blooms in eutrophic water, are common toxic metabolites and a potential threat to human health. However, the mechanism of MC photodegradation by photosensitizers in raw water remains unclear. In photodegradation and quenching experiments, this study investigates the photosensitized degradation of microcystin-LR (MC-LR) by fulvic acid (FA, a kind of dissolved organic matter with natural photosensitizing properties) under ultraviolet (UV) light irradiation. The photodegradation mechanisms of FA are also explored. The photodegradation process of MC-LR by FA was consistent with second-order reaction kinetics. The degradation rate of MC-LR in FA decreased from 80% to 55% as the pH increased from 3 to 9, because the binding ability of FA to MC-LR reduces as the pH increases. Given that FA can both inhibit and promote MC-LR degradation depending on its concentration, the optimum initial FA concentration for degrading MC-LR was determined as 9.86 mgC·L-1. The excited triplet state of FA (3FA∗) accounted for 50.12% of the MC-LR loss; the remaining loss (49.88%) was contributed by reactive oxygen species and direct photolysis. This implies that the main pathway of MC-LR degradation is reaction with 3FA∗. The MC-LR degradation rate is 36% higher under UV irradiation than that under simulated sunlight irradiation.


Asunto(s)
Benzopiranos/farmacología , Microcistinas/efectos de la radiación , Fármacos Fotosensibilizantes/farmacología , Rayos Ultravioleta , Agua/química , Cinética , Toxinas Marinas , Fotólisis , Contaminantes Químicos del Agua/química , Contaminantes Químicos del Agua/efectos de la radiación , Purificación del Agua/métodos
18.
Bioresour Technol ; 247: 1107-1118, 2018 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-29017812

RESUMEN

Recently, an increasing level of attention has focused on the emerging technology of anaerobic dynamic membrane bioreactors (AnDMBRs), owing to its merits such as low membrane module cost, easy control of membrane fouling, low energy consumption and sludge production, as well as biogas production. As research on AnDMBRs is still in the nascent stage, an introduction of bioreactor configurations, dynamic membrane (DM) module, and DM layer formation and cleaning is firstly presented. The process performance of the AnDMBR for wastewater treatment is then reviewed with regard to pollutant removal, DM filterability, biogas production, and potential advantages over the conventional anaerobic membrane bioreactor (AnMBR). In addition, the important parameters affecting process performance are briefly discussed. Lastly, the challenges encountered and perspectives regarding the future development of the AnDMBR process to promote its practical applications are presented.


Asunto(s)
Reactores Biológicos , Aguas Residuales , Anaerobiosis , Membranas Artificiales , Aguas del Alcantarillado , Eliminación de Residuos Líquidos , Purificación del Agua
19.
Int J Comput Assist Radiol Surg ; 12(11): 1985-1993, 2017 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-28643024

RESUMEN

PURPOSE: Postimplant validation is an indispensable part in the brachytherapy technique. It provides the necessary feedback to ensure the quality of operation. The ability to pick implanted seed relates directly to the accuracy of validation. To address it, an automatic approach is proposed for picking implanted brachytherapy seeds in 3D CT images. METHODS: In order to pick seed configuration (location and orientation) efficiently, the approach starts with the segmentation of seed from CT images using a thresholding filter which based on gray-level histogram. Through the process of filtering and denoising, the touching seed and single seed are classified. The true novelty of this approach is found in the application of the canny edge detection and improved concave points matching algorithm to separate touching seeds. Through the computation of image moments, the seed configuration can be determined efficiently. Finally, two different experiments are designed to verify the performance of the proposed approach: (1) physical phantom with 60 model seeds, and (2) patient data with 16 cases. RESULTS: Through assessment of validated results by a medical physicist, the proposed method exhibited promising results. Experiment on phantom demonstrates that the error of seed location and orientation is within ([Formula: see text]) mm and ([Formula: see text])[Formula: see text], respectively. In addition, the most seed location and orientation error is controlled within 0.8 mm and 3.5[Formula: see text] in all cases, respectively. The average process time of seed picking is 8.7 s per 100 seeds. CONCLUSIONS: In this paper, an automatic, efficient and robust approach, performed on CT images, is proposed to determine the implanted seed location as well as orientation in a 3D workspace. Through the experiments with phantom and patient data, this approach also successfully exhibits good performance.


Asunto(s)
Braquiterapia/métodos , Procesamiento de Imagen Asistido por Computador/métodos , Imagenología Tridimensional/métodos , Neoplasias Pulmonares/radioterapia , Tomografía Computarizada por Rayos X/métodos , Algoritmos , Humanos , Neoplasias Pulmonares/diagnóstico por imagen , Fantasmas de Imagen , Prótesis e Implantes , Reproducibilidad de los Resultados
20.
Environ Sci Pollut Res Int ; 24(21): 17805-17815, 2017 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-28602005

RESUMEN

The distribution variation in chromophoric dissolved organic matter (CDOM) content in mid-latitude subtropical drinking water source reservoirs (MDWSRs) has great significance in the security of aquatic environments and human health. CDOM distribution is heavily influenced by biogeochemical processes and anthropogenic activity. However, little is known regarding the impact of component variation and phytoplankton growth on CDOM distribution variation in MDWSR. Therefore, samples were collected from a representative MDWSR (the Shanzai Reservoir) for analysis. CDOM absorption and fluorescence coupling with parallel factor analysis were measured and calculated. The results indicated that only two CDOM components were found in the surface water of Shanzai Reservoir, fulvic acid, and high-excitation tryptophan, originating from terrestrial and autochthonous sources, respectively. The types of components did not change with the season. The average molecular weight of CDOM increased in proportion to its fulvic acid content. The distribution variation in CDOM content mainly resulted from the variation in two CDOM components in summer and from high-excitation tryptophan in winter. Phytoplankton growth strongly influenced the distribution variation of CDOM content in summer; the metabolic processes of Cyanobacteria and Bacillariophyta consumed fulvic acid, while that of Cryptophyta produced high-excitation tryptophan.


Asunto(s)
Agua Potable , Fitoplancton/crecimiento & desarrollo , Agua Dulce , Estaciones del Año , Espectrometría de Fluorescencia
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