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1.
Nature ; 610(7930): 74-80, 2022 10.
Artículo en Inglés | MEDLINE | ID: mdl-36163287

RESUMEN

The adverse impact of particulate air pollution on human health1,2 has prompted the development of purification systems that filter particulates out of air3-5. To maintain performance, the filter units must inevitably be replaced at some point, which requires maintenance, involves costs and generates solid waste6,7. Here we show that an ion-doped conjugated polymer-coated matrix infiltrated with a selected functional liquid enables efficient, continuous and maintenance-free air purification. As the air to be purified moves through the system in the form of bubbles, the functional fluid provides interfaces for filtration and for removal of particulate matter and pollutant molecules from air. Theoretical modelling and experimental results demonstrate that the system exhibits high efficiency and robustness: its one-time air purification efficiency can reach 99.6%, and its dust-holding capacity can reach 950 g m-2. The system is durable and resistant to fouling and corrosion, and the liquid acting as filter can be reused and adjusted to also enable removal of bacteria or odours. We anticipate that our purification approach will be useful for the development of specialist air purifiers that might prove useful in a settings such as hospitals, factories and mines.


Asunto(s)
Absorción Fisicoquímica , Contaminantes Atmosféricos , Filtración , Material Particulado , Contaminantes Atmosféricos/química , Contaminantes Atmosféricos/aislamiento & purificación , Bacterias/aislamiento & purificación , Polvo/prevención & control , Filtración/instrumentación , Filtración/métodos , Humanos , Odorantes/prevención & control , Material Particulado/química , Material Particulado/aislamiento & purificación , Polímeros/química , Residuos Sólidos
2.
Proc Natl Acad Sci U S A ; 119(29): e2206462119, 2022 Jul 19.
Artículo en Inglés | MEDLINE | ID: mdl-35858305

RESUMEN

Emulsification is a crucial technique for mixing immiscible liquids into droplets in numerous areas ranging from food to medicine to chemical synthesis. Commercial emulsification methods are promising for high production, but suffer from high energy input. Here, we report a very simple and scalable emulsification method that employs the drag-reducing liquid gating structure to create a smooth liquid-liquid interface for the reduction of resistance and tunable generation of droplets with good uniformity. Theoretical modeling and experimental results demonstrate that our method exhibits ultrahigh efficiency, which can reach up to more than 4 orders of magnitude greater energy-saving compared to commercial methods. For temperature-sensitive biological components, such as enzymes, proteins, and bacteria, it can offer a comfortable environment to avoid exposure to high temperatures during emulsifying, and the interface also enables the suppression of fouling. This unique drag-reducing liquid gating interfacial emulsification mechanism promotes the efficiency of droplet generation and provides fresh insight into the innovation of emulsifications that can be applied in many fields, including the food industry, the daily chemical industry, biomedicine, material fabrication, the petrochemical industry, and beyond.

3.
Nano Lett ; 24(12): 3661-3669, 2024 Mar 27.
Artículo en Inglés | MEDLINE | ID: mdl-38408021

RESUMEN

The lack of stability of red perovskite nanocrystals (PeNCs) remains the main problem that restricts their patterning application. In this work, the dual-ligand passivation strategy was introduced to stabilize PeNCs and inhibit their halogen ion migration during high-voltage electrohydrodynamic (EHD) inkjet printing. The as-printed red arrays exhibit the highest emisson intensity and least blue shift compared with samples with other passivation strategies under a high electric field during EHD inkjet printing. Combining with blue and green PeNC inks, single-color and tricolor color conversion layer arrays were successfully printed, with minimum pixel size of 5 µm and the highest spatial resolution of 2540 dpi. The color coordinate of CsPbBrI2 NCs arrays are located close to the red point, with a color gumat of 97.28% of Rec. 2020 standard. All of these show great potential in the application of color conversion layers in a near-eye micro-LED display.

4.
Pediatr Res ; 2024 Jan 23.
Artículo en Inglés | MEDLINE | ID: mdl-38263452

RESUMEN

BACKGROUND: Exhaled nitric oxide concentration (FENO) is a marker of airway inflammation. This study aimed to evaluate the association of air pollution exposure with FENO levels and asthma prevalence with respiratory symptoms in school children. METHODS: We analyzed 4736 school children who reside in six townships near industrial areas in central Taiwan. We evaluated asthmatic symptoms, FENO, and conducted the environmental questionnaire. The personal exposure of PM2.5, NO, and SO2 was estimated using land-use regression models data on children's school and home addresses. RESULTS: Annual exposure to PM2.5 was associated with increased odds of physician-diagnosed asthma (OR = 1.595), exercise-induced wheezing (OR = 1.726), itchy eyes (OR = 1.417), and current nasal problems (OR = 1.334) (P < 0.05). FENO levels in the absence of infection were positively correlated with age, previous wheezing, allergic rhinitis, atopic eczema, near the road, and for children with high exposure to PM2.5 (P < 0.05). An increase of 1 µg/m3 PM2.5 exposure was significantly associated with a 1.0% increase in FENO levels for children after adjusting for potential confounding variables, including exposures to NO and SO2. CONCLUSIONS: Long-term exposures to PM2.5 posed a significant risk of asthma prevalence and airway inflammation in a community-based population of children. IMPACT: Annual exposure to PM2.5 was associated with increased odds of physician-diagnosed asthma and nasal problems and itchy eyes. Long-term exposures to PM2.5 were significantly associated with FENO levels after adjusting for potential confounding variables. This is first study to assess the association between FENO levels and long-term air pollution exposures in children near coal-based power plants. An increase of 1 µg/m3 annual PM2.5 exposure was significantly associated with a 1.0% increase in FENO levels. Long-term exposures to PM2.5 posed a significant risk of asthma prevalence and airway inflammation in a community-based population of children.

5.
Ecotoxicol Environ Saf ; 262: 115162, 2023 Jun 20.
Artículo en Inglés | MEDLINE | ID: mdl-37352583

RESUMEN

Phthalates have become a matter of public health concern due to their extensive use worldwide and negative health effects. The evaluation of potential sources of phthalate exposure is crucial to design prevention strategies, especially for vulnerable populations. This study included 528 mother-child pairs in the Taiwan Mother Infant Cohort Study who were followed up at ages 3-6 years between 2016 and 2020. Each mother was interviewed by using a structured questionnaire containing questions on demographic characteristics and household environment factors, such as the use of plastic food packaging, residential visible mold, insecticide sprays, and electric mosquito repellents. Eleven phthalate metabolites were analyzed in urine samples simultaneously collected from the mother-child pairs. The phthalate metabolite urinary concentrations were higher among the children than among their mothers, except those of mono-ethyl phthalate (MEP) and mono-2-ethylhexyl phthalate (MEHP). Multiple linear regression analyses showed that urine samples collected during the summer showed higher concentrations of phthalate metabolites than those collected during the winter. Family income levels had negative associations with the concentrations of MnBP and metabolites of di-2-ethylhexyl phthalate (DEHP) in children. The use of plastic food packaging was positively associated with mono-n-butyl phthalate (MnBP) and metabolites of DEHP in mothers. Residential visible mold or mold stains were significantly associated with higher MnBP and DEHP metabolite concentrations in children. The use of insecticide sprays was positively associated with MnBP concentrations in children. Significant associations between household environmental factors and phthalate exposure were mostly found in children, potentially indicating different exposure pathways between mothers and their children. Findings from this study provide additional information for the design of prevention strategies to protect the health of children and women.

6.
BMC Med Inform Decis Mak ; 23(1): 159, 2023 08 14.
Artículo en Inglés | MEDLINE | ID: mdl-37580719

RESUMEN

BACKGROUND: Current healthcare trends emphasize the use of shared decision-making (SDM) for renal replacement treatment (RRT) in patients with chronic kidney disease (CKD). This is crucial to understand the relationship between SDM and illness perception of CKD patients. Few studies have focused on SDM and illness perception status of CKD patients and the impact of illness perception on RRT after SDM. METHODS: In this cross-sectional study, we used a questionnaire with purposive sampling from March 2019 to February 2020 at the nephrology outpatient department of a medical center in southern Taiwan. The nephrology medical team in this study used the SHARE five-step model of SDM to communicate with the patients about RRT and Brief Illness Perception Questionnaire (BIPQ) was applied to evaluate illness perception of these patients at the beginning of SDM. According to the SDM decision time, the study participants were classified general and delayed SDM groups. The distribution between SDM groups was estimated using independent two sample t-test, chi-squared test or Fisher's exact test. The correlation between illness perception and SDM decision time were illustrated and evaluated using Spearman's correlation test. A p-value less than 0.05 is statistically significant. RESULTS: A total of 75 patients were enrolled in this study. The average time to make a dialysis decision after initiating SDM was 166.2 ± 178.1 days. 51 patients were classified as general group, and 24 patients were classified as delayed group. The median SDM decision time of delayed group were significantly longer than general group (56 vs. 361 days, P < 0.001). Our findings revealed that delayed group was significantly characterized with not created early surgical assess (delayed vs. general: 66.7% vs. 27.5%, p = 0.001) compared to general group. The average BIPQ score was 54.0 ± 8.1 in our study. We classified the patients into high and low illness perception group according to the median score of BIPQ. The total score of BIPQ in overall participants might increase by the SDM decision time (rho = 0.83, p = 0.830) and the linear regression line also showed consistent trends between BIPQ and SDM decision time in correspond cohorts. However, no statistically significant findings were found. CONCLUSIONS: The patients with advanced chronic kidney disease took an average of five and a half months to make a RRT decision after undergoing SDM. Although there is no statistical significance, the trend of illness perception seems correlated with decision-making time. The stronger the illness perception, the longer the decision-making time. Furthermore, shorter decision times may be associated with earlier establishment of surgical access. We need more research exploring the relationship between illness perception and SDM for RRT in CKD patients.


Asunto(s)
Insuficiencia Renal Crónica , Humanos , Estudios Transversales , Insuficiencia Renal Crónica/terapia , Toma de Decisiones Conjunta , Diálisis Renal , Percepción , Participación del Paciente , Toma de Decisiones
7.
Nano Lett ; 22(17): 7011-7019, 2022 Sep 14.
Artículo en Inglés | MEDLINE | ID: mdl-36036573

RESUMEN

The optimized exploitation of perovskite nanocrystals and nanoplatelets as highly efficient light sources requires a detailed understanding of the energy spacing within the exciton manifold. Dark exciton states are particularly relevant because they represent a channel that reduces radiative efficiency. Here, we apply large in-plane magnetic fields to brighten optically inactive states of CsPbBr3-based nanoplatelets for the first time. This approach allows us to access the dark states and directly determine the dark-bright splitting, which reaches 22 meV for the thinnest nanoplatelets. The splitting is significantly less for thicker nanoplatelets due to reduced exciton confinement. Additionally, the form of the magneto-PL spectrum suggests that dark and bright state populations are nonthermalized, which is indicative of a phonon bottleneck in the exciton relaxation process.

8.
Angew Chem Int Ed Engl ; 62(41): e202311075, 2023 Oct 09.
Artículo en Inglés | MEDLINE | ID: mdl-37602487

RESUMEN

The limited active sites and poor acid-alkaline solution stability of metal-organic frameworks (MOFs), significantly limit their wider application. In this study, the acid property of tannic acid (TA) was used as an etchant to etch the surface-active sites. Subsequently, the further chelation of the protonated TA with the exposed metal active site can effectively protect the metal ions. Meanwhile, the TA provided a large amount of phenolic hydroxyl groups, which can greatly improve the stability of imidazolate-coordinated MOFs. The electrochemical test results indicated that the MOFs composite materials synthesized using this scheme had high specific capacitance and stability. And the mechanism of its electrochemical reaction process was explored through in situ X-ray diffraction (XRD) and theoretical calculations. In addition, the same treatment was carried out through a series of carboxyl-coordinated MOFs, which further confirmed the principle of this scheme to obtain a higher active site and stability. This paper explains the mechanism of functionalization of nano-MOFs by polyphenolic compounds, providing new ideas for the research of nano-MOFs.

9.
Bioconjug Chem ; 33(11): 2088-2096, 2022 11 16.
Artículo en Inglés | MEDLINE | ID: mdl-36342263

RESUMEN

An efficient modular strategy for rapid assembly of positron emission tomography (PET) agents has been developed. The use of a sequential, rapid, and selective double-click reaction allows for a combinatorial approach to the cross-linking of positron emitter-bearing prosthetic groups with various ligands. The strain-promoted azide alkyne cyclization (SPAAC) coupling of 18F-labeled azide synthon with MC-DIBOD, a cyclooctadiyne with one of the triple bonds caged as a cyclopropenone moiety, produces a stable intermediate. A brief exposure of the latter to 350-420 nm light removes protection of the second triple bond allowing for the addition of an azide-tagged biomolecule. The utility of this strategy has been demonstrated by the construction of several PET agents. The value of modularity was demonstrated in the preparation of PSMA PET agents, where the hydrophilicity was easily modified to improve tumor to background contrast.


Asunto(s)
Azidas , Química Clic , Azidas/química , Química Clic/métodos , Tomografía de Emisión de Positrones , Alquinos/química , Radiofármacos
10.
Microb Pathog ; 168: 105557, 2022 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-35623565

RESUMEN

ArsR-family transcriptional factors regulates diverse physiological functions necessary for Brucella adaptation to environmental changes. However, whether the ArsR-family transcriptional regulator are related to virulence, and the precise determination of ArsR direct targets in Brucella are still unknown. Therefore, we created a 2308ΔArsR6 mutant of B. abortus 2308 (S2308). Virulence assay was performed using a murine macrophage cell line (RAW 264.7). We performed chromatin immunoprecipitation of ArsR6 followed by next-generation sequencing (ChIP-seq). We also selected the target gene pobA (BAB2_0600), and created the mutant (2308ΔpobA). The survival capability of 2308ΔpobA strain in RAW 264.7 was detected and the levels of tumor necrosis factor-α (TNF-α), interferon-gamma (IFN-γ), interleukin-12 (IL-12) and interleukin-18 (IL-18) were also measured. The results showed that 2308ΔArsR6 reduced survival capability in RAW 264.7. We detected 40 intergenic ChIP-seq peaks of ArsR6 binding distributed across the Brucella genome. 2308ΔpobA was significantly reduced survival capability in RAW 264.7. After the macrophages were infected with 2308ΔpobA, the levels of TNF-α, IFN-γ, IL-12 and IL-18 were decreased and were significantly lower than that for the S2308-infected group, indicating that the 2308ΔpobA could reduce the secretion of inflammatory cytokines. Taken together, the research provided new insights into the functionality of ArsR6 and great significance to clarify the function of ArsR6.


Asunto(s)
Brucella abortus , Brucelosis , Animales , Brucelosis/patología , Interferón gamma/metabolismo , Interleucina-12/metabolismo , Interleucina-18/metabolismo , Ratones , Factor de Necrosis Tumoral alfa/metabolismo , Virulencia
11.
Chemistry ; 28(6): e202103495, 2022 Jan 27.
Artículo en Inglés | MEDLINE | ID: mdl-34859914

RESUMEN

The Z-scheme overall solar water splitting is a mimic of natural photosynthesis to convert solar energy into chemical energy. Since the energy levels of most organic semiconductors match well with the hydrogen evolution potential, they have great application prospects as photocathodes in Z-scheme photoelectrochemical systems. However, due to the weak light absorption and difficult carrier separation, the photocurrent density and onset potential of organic photocathodes are still low. To solve these problems, we introduced a copper nanosheets array (Cu NSA) framework under organic layers to increase the surface reaction sites, improve the light absorption and enhance the distribution range of built-in electric field simultaneously. As a result, the photocurrent density and onset potential of poly(3-hexylthiophene) : [6,6]-phenyl-C61 -butyric acid (P3HT : PCBM) photocathode were enhanced significantly. The onset potential increased by 50 mV to 0.65 V vs. RHE, and the photocurrent density reached -1 mA cm-2 at 0 V vs. RHE, which was 18 times that of the sample without Cu NSA. The optimized photocathode was connected with titanium dioxide nanorods array photoanode in a tandem manner to realize the spontaneous overall water splitting. Without bias and co-catalyst, the photocurrent density was maintained at 110 µA cm-2 and the solar-to-fuel conversion efficiency was 0.14 % in neutral solution. These results provide a feasible method for optimizing the performance of organic photocathodes.

12.
Inorg Chem ; 61(45): 18318-18324, 2022 Nov 14.
Artículo en Inglés | MEDLINE | ID: mdl-36322933

RESUMEN

The microenvironment tuning of Ni species, a promising non-precious catalyst, is significant in the energy and environmentally relevant urea electro-oxidation reaction (UOR). Herein, we found that the high-valent Ni species induced by the inactive MoO2 in mixed nanocrystals of NiO/MoO2 were effective for urea oxidation. The redox interaction of MoO2 and NiO revealed by the spectroscopic analysis well supported the formation of high-valent Ni species and the changes in the surface chemical state. High catalytic activity and stability for urea oxidation were observed by a series of electrochemical measures compared to the counterpart catalysts of MoO2 and NiO. The optimal NiO/MoO2 hybrid catalyst showed a UOR activity of 73.1 mA cm-2 at 1.50 V, which was about 12-fold that of the NiO catalyst. In addition, largely improved catalytic kinetics and catalytic stability for UOR were also demonstrated. Because of the inactive activity of MoO2 and the low performance of NiO, the largely improved preference can be affirmatively attributed to the efficient catalytic synergism of NiO/MoO2 in the mixed nanocrystals. The current finding clarifies the catalytic promotion effect of the inactive Mo species on Ni-based catalysts for urea oxidation, which would be instructive for Ni/Mo-relevant catalyst development.


Asunto(s)
Níquel , Urea , Urea/análisis , Urea/química , Níquel/química , Catálisis , Oxidación-Reducción
13.
J Pediatr Hematol Oncol ; 44(6): e939-e944, 2022 08 01.
Artículo en Inglés | MEDLINE | ID: mdl-35622991

RESUMEN

OBJECTIVES: In this study, immature dendritic cells (imDCs) were transfected with the Bacillé Calmette-Guérin (BCG) heat shock protein 70 (HSP70) gene to investigate the impact on the maturity and function of imDCs from the bone marrow of pediatric patients with acute leukemia. MATERIALS AND METHODS: Bone marrow mononuclear cells were isolated from pediatric patients with acute lymphoblastic leukemia who had achieved complete remission at least 6 months prior. The recombinant vector pDisplay-HSP70 was transfected into imDCs. The test groups included 5 subgroups: imDCs (imDCs without special processing), imDC-neos (imDCs transfected with the pDisplay vector), HSP70 (imDCs transfected with the pDisplay-HSP70 vector), tumor necrosis factor α (TNF-α) (imDCs induced with rhTNF-α), and HSP70+TNF-α. Mature dendritic cells (mDCs) from different groups (HSP70, TNF-α, and HSP70+TNF-α) and T cells were cultured. An equal number of lymphocytes and mDCs were used as controls. The proliferation indices of T cells and the cytokine contents (interleukin-12 and interferon-γ) were determined. RESULTS: The HSP70 group and the TNF-α group expressed higher levels of HLA-DR, CD80, and CD86 but lower levels than the HSP70+TNF-α group; there was no significant difference between the HSP70 group and the TNF-α group. The combination of HSP70 and TNF-α induced the highest levels of interleukin-12 and interferon-γ. CONCLUSIONS: The outcomes of this study indicated that gene transfection with BCG HSP70 evidently promoted imDC maturity and the antitumor effects of mDC-mediated T cells. It could serve as a candidate gene-modified cell vaccine for tumor immunotherapy.


Asunto(s)
Células Dendríticas , Proteínas HSP70 de Choque Térmico , Leucemia , Vacuna BCG , Médula Ósea , Células de la Médula Ósea , Niño , Proteínas HSP70 de Choque Térmico/genética , Humanos , Interferón gamma , Interleucina-12 , Transfección , Factor de Necrosis Tumoral alfa/genética
14.
Environ Res ; 215(Pt 1): 114187, 2022 12.
Artículo en Inglés | MEDLINE | ID: mdl-36037918

RESUMEN

Environmental exposures to mixtures of toxic chemicals have potential interaction effects that may lead to hazard index values exceeding one. However, current regulation levels, such as tolerable daily intake (TDI), are mostly based on experimental studies conducted with a single chemical compound. In this study, we assessed the relationships between melamine and di-(2-ethylhexyl) phthalate (DEHP) exposure and their coexposure with the early renal injury markers N-acetyl -D-glucosaminidase (NAG), albumin/creatinine ratio (ACR), and microalbuminuria in 1236 pregnant women. Various generalized linear models with interaction terms and Bayesian kernel machine regression models were used for the (co-)exposure response associations. We derived the benchmark dose (BMD) and the corresponding one-sided 95% confidence bound BMDL based on the estimated (covariate-adjusted) average daily intake of melamine and DEHP metabolites measured in spot urine of the women collected during the third trimester. Given a benchmark response of 0.1, the BMDL level of melamine (DEHP) exposure on NAG (ACR, microalbuminuria) was 2.67 (11.20, 4.45) µg/kg_bw/day, and it decreased to as low as 1.46 (3.83, 2.73) µg/kg_bw/day when considering coexposure to DEHP (melamine) up to the 90th percentile. Both the exposure threshold levels of melamine and DEHP for early renal injuries in pregnant women were several-fold to one order lower than the current recommended TDIs by the WHO and the US FDA and EPA and were even lower considering coexposure. Because of concurrent exposures in real-world environments, more stringent regulation levels are recommended in susceptible populations, such as pregnant women, due to potential synergistic mixture effects.


Asunto(s)
Dietilhexil Ftalato , Contaminantes Ambientales , Ácidos Ftálicos , Albúminas , Albuminuria/inducido químicamente , Teorema de Bayes , Benchmarking , Biomarcadores/orina , Creatinina , Dietilhexil Ftalato/toxicidad , Exposición a Riesgos Ambientales/análisis , Contaminantes Ambientales/orina , Femenino , Hexosaminidasas , Humanos , Riñón/metabolismo , Ácidos Ftálicos/orina , Embarazo , Mujeres Embarazadas , Triazinas
15.
J Adv Nurs ; 78(3): 645-665, 2022 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-34633112

RESUMEN

AIMS: To evaluate the different types of virtual reality (VR) therapy received by adult patients undergoing surgical procedures in acute care settings and the outcome measures, as well as to highlight the acceptability and feasibility of VR approaches among patients and healthcare workers. DESIGN: Whittemore and Knafl's integrative review method guided the analysis. DATA SOURCES: Searches were conducted in ScienceDirect, ProQuest, Wiley Online Library, Medline, PsycINFO and PubMed and Google Scholar from 2000 to June 2021. REVIEW METHODS: A systematic search on articles published in English was carried out with electronic databases and hand search references. Keywords searched included primary qualitative and quantitative studies that utilized VR therapy in surgical care settings. RESULTS: Eighteen articles were reviewed, which reported the use of two main strategies: guided and interactive imagery therapy. The findings identified: (i) patient-clinical outcome measures including the use of analgesics, vital signs, functional capacity and length of hospital stay; and (ii) patient-reported experience measures including pain, anxiety and satisfaction level. Comfort, age, knowledge and attitude were key factors influencing the acceptability of VR among the patients, whereas cost-effectiveness and infection control were two main factors affecting the feasibility of use among the health care workers. CONCLUSION: VR therapy demonstrated potential improvements in both the patient-clinical outcomes and patient-reported experiences of those undergoing surgical procedures. However, the findings were inconsistent, which required further research to explore and establish the effectiveness of using VR in the context of acute care settings. IMPACT: VR distraction has been increasingly used as a non-pharmacological method in managing pain, easing anxiety and optimizing other associated outcomes in patients undergoing surgical procedures. It is essential to examine the effectiveness of VR therapy on the adult patients' outcomes in acute care settings with surgical procedures, as well as its acceptability and feasibility of use.


Asunto(s)
Terapia de Exposición Mediante Realidad Virtual , Realidad Virtual , Adulto , Trastornos de Ansiedad , Humanos , Evaluación de Resultado en la Atención de Salud , Manejo del Dolor
16.
Altern Ther Health Med ; 27(1): 18-27, 2021 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-33245706

RESUMEN

Cultural competence and skills are the major part of professionalism a nurse should achieve to provide the best quality health care without hurting the culturally sensitive issues in all aspects. This review focused on the assessment of cultural competence and skills among nursing professionals. Assessment of these skills is very much necessary for accountability as well as improving the capability among the nurses or nursing professionals. Many tools are developed across the world including many region-specific. These tools can be employed for the self-assessment to know the self-competency and to assess the effectiveness of training programs among the professionals.


Asunto(s)
Competencia Cultural , Atención a la Salud , Humanos
17.
Entropy (Basel) ; 23(7)2021 Jul 18.
Artículo en Inglés | MEDLINE | ID: mdl-34356454

RESUMEN

The development of oil and gas resources is gradually transferring to the deep sea, and the hydrate plugging of submarine pipelines at high pressures and low temperatures is becoming an important problem to ensure the safety of pipeline operations. The swirl flow is a new method to expand the boundary of hydrate safe flow. Numerical simulation of the hydrate slurry flow characteristics in a horizontal pipeline by twisted band has been carried out, and the flow of CO2 hydrate slurry in low concentration has been simulated by the RSM and DPM models. The results show that the heat transfer efficiency is also related to Re and particle concentration. The velocity distribution has the form of symmetrical double peaks, and the peaks finally merge at the center of the pipeline. Vortexes firstly appear on both sides of the edge of the twisted band, and then move to the middle part of the twisted band. Finally, the vortex center almost coincides with the velocity center. The rotation direction of hydrate particles is the same as the twisted direction of the twisted band, twist rate (Y) is smaller, Re is larger, and the symmetric vortex lines merge farther away. The initial swirl number is mainly related to Y, but not Re. The swirl flow attenuates exponentially, and its attenuation rate is mainly related to Re, but not Y. Compared with ordinary pipelines, the swirl flow can obviously improve the transportation distance of hydrate slurry.

18.
Entropy (Basel) ; 23(4)2021 Apr 20.
Artículo en Inglés | MEDLINE | ID: mdl-33924044

RESUMEN

The natural gas hydrate plugging problems in the mixed pipeline are becoming more and more serious. The hydrate plugging has gradually become an important problem to ensure the safety of pipeline operation. The deposition and heat transfer characteristics of natural gas hydrate particles in the spiral flow pipeline have been studied. The DPM model (discrete phase model) was used to simulate the motion of solid particles, which was used to simulate the complex spiral flow characteristics of hydrate in the pipeline with a long twisted band. The deposition and heat transfer characteristics of gas hydrate particles in the spiral flow pipeline were studied. The velocity distribution, pressure drop distribution, heat transfer characteristics, and particle settling characteristics in the pipeline were investigated. The numerical results showed that compared with the straight flow without a long twisted band, two obvious eddies are formed in the flow field with a long twisted band, and the velocities are maximum at the center of the vortices. Along the direction of the pipeline, the two vortices move toward the pipe wall from near the twisted band, which can effectively carry the hydrate particles deposited on the wall. With the same Reynolds number, the twisted rate was greater, the spiral strength was weaker, the tangential velocity was smaller, and the pressure drop was smaller. Therefore, the pressure loss can be reduced as much as possible with effect of the spiral flow. In a straight light flow, the Nusselt number is in a parabolic shape with the opening downwards. At the center of the pipe, the Nusselt number gradually decreased toward the pipe wall at the maximum, and at the near wall, the attenuation gradient of the Nu number was large. For spiral flow, the curve presented by the Nusselt number was a trough at the center of the pipe and a peak at 1/2 of the pipe diameter. With the reduction of twist rate, the Nusselt number becomes larger. Therefore, the spiral flow can make the temperature distribution more even and prevent the large temperature difference, resulting in the mass formation of hydrate particles in the pipeline wall. Spiral flow has a good carrying effect. Under the same condition, the spiral flow carried hydrate particles at a distance about 3-4 times farther than that of the straight flow.

19.
Small ; 16(9): e1905318, 2020 03.
Artículo en Inglés | MEDLINE | ID: mdl-31793747

RESUMEN

Fluidic flow behaviors in microfluidics are dominated by the interfaces created between the fluids and the inner surface walls of microchannels. Microchannel inner surface designs, including the surface chemical modification, and the construction of micro-/nanostructures, are good examples of manipulating those interfaces between liquids and surfaces through tuning the chemical and physical properties of the inner walls of the microchannel. Therefore, the microchannel inner surface design plays critical roles in regulating microflows to enhance the capabilities of microfluidic systems for various applications. Most recently, the rapid progresses in micro-/nanofabrication technologies and fundamental materials have also made it possible to integrate increasingly complex chemical and physical surface modification strategies with the preparation of microchannels in microfluidics. Besides, a wave of researches focusing on the ideas of using liquids as dynamic surface materials is identified, and the unique characteristics endowed with liquid-liquid interfaces have revealed that the interesting phenomena can extend the scope of interfacial interactions determining microflow behaviors. This review extensively discusses the microchannel inner surface designs for microflow control, especially evaluates them from the perspectives of the interfaces resulting from the inner surface designs. In addition, prospective opportunities for the development of surface designs of microchannels, and their applications are provided with the potential to attract scientific interest in areas related to the rapid development and applications of various microchannel systems.


Asunto(s)
Microfluídica , Microfluídica/instrumentación , Microfluídica/tendencias , Nanoestructuras/química , Fenómenos Físicos
20.
Eur Radiol ; 30(2): 712-725, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31696294

RESUMEN

OBJECTIVES: A method named computed tomography angiography-derived fractional flow reserve (FFRCT) is an alternative method for detecting hemodynamically significant coronary stenosis. We carried out a meta-analysis to derive reliable assessment of the diagnostic performances of FFRCT and compare the diagnostic accuracy with CCTA using FFR as reference. METHODS: We searched PubMed, EMBASE, The Cochrane Library, and Web of science for relevant articles published from January 2008 until May 2019 using the following search terms: FFRCT, noninvasive FFR, non-invasive FFR, noninvasive fractional flow reserve, non-invasive fractional flow reserve, and CCTA. Pooled estimates of sensitivity and specificity with the corresponding 95% confidence intervals (CIs) and the summary receiver operating characteristic curve (sROC) were determined. RESULTS: Sixteen studies published between 2011 and 2019 were included with a total of 1852 patients and 2731 vessels. The pooled sensitivity and specificity for FFRCT at the per-patient level was 89% (95% CI, 85-92%) and 71% (95% CI, 61-80%), respectively, while on the per-vessel basis was 85% (95% CI, 82-88%) and 82% (95% CI, 75-87%), respectively. No apparent difference in the sensitivity at per-patient and per-vessel level between FFRCT and CCTA was observed (0.89 versus 0.93 at per-patient; 0.85 versus 0.88 at per-vessel). However, the specificity of FFRCT was higher than CCTA (0.71 versus 0.32 at per-patient analysis; 0.82 versus 0.46 at per-vessel analysis). CONCLUSIONS: FFRCT obtained a high diagnostic performance and is a viable alternative to FFR for detecting coronary ischemic lesions. KEY POINTS: • Noninvasive FFRCThas higher specificity for anatomical and physiological assessment of coronary artery stenosis compared with CCTA. • Noninvasive FFRCTis a viable alternative to invasive FFR for the detection and exclusion of coronary lesions that cause ischemia.


Asunto(s)
Angiografía por Tomografía Computarizada/métodos , Angiografía Coronaria/métodos , Reserva del Flujo Fraccional Miocárdico/fisiología , Isquemia Miocárdica/diagnóstico por imagen , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Isquemia Miocárdica/fisiopatología , Curva ROC , Sensibilidad y Especificidad
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