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1.
Nanotechnology ; 34(50)2023 Oct 11.
Artículo en Inglés | MEDLINE | ID: mdl-37722365

RESUMEN

An electrothermal coupling model of resistive random access memory (RRAM) was established based on the oxygen vacancy conduction mechanism. By resolving the partial differential equation for the coefficients, the variation process of the device resistance was simulated. In our studies, a device model was proposed which can accurately simulate the whole process of RRAM forming, reset, and set. Based on the established model, a new high dielectric constant (high-k) material (La2O3) is introduced as the sidewall material. The La2O3sidewall material can concentrate the electric field and helps to speed up the formation of conductive filaments. The La2O3sidewall can effectively reduce the forming voltage increase during the miniaturization process. Then, the influence of sidewall thermal conductivity on forming voltage is studied, and it is discovered that low thermal conductivity helps to reduce the model's forming voltage and increase the temperature concentration. These findings serve as a foundation for more studies on the choice of sidewall materials.

2.
Herz ; 48(6): 470-473, 2023 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-37566118

RESUMEN

A 71 year old male patient who experienced acute myocardial infarction (AMI) 4 years ago and had a history of polycythemia vera and thrombocythemia was admitted because acute attack of chronic heart failure. Coronary angiography revealed an unusual filling defect in the middle segment of the left anterior descending (LAD) coronary artery and IVUS showed it is a HLS which is different from dissection or woven coronary artery. We review the recent literature of HLS in this article and further investigations are warranted for the optimal management of HLS.


Asunto(s)
Policitemia Vera , Trombocitosis , Trombosis , Masculino , Humanos , Anciano , Vasos Coronarios/diagnóstico por imagen , Policitemia Vera/complicaciones , Policitemia Vera/diagnóstico por imagen , Angiografía Coronaria , Ultrasonografía Intervencional
3.
Appl Opt ; 61(35): 10439-10445, 2022 Dec 10.
Artículo en Inglés | MEDLINE | ID: mdl-36607103

RESUMEN

An optical fiber Fabry-Perot (FP) interferometric humidity sensor based on black phosphorus quantum dots (BPQDs) and polyvinyl alcohol (PVA) is proposed for the first time, to the best of our knowledge, and experimentally verified. The sensor is constructed by splicing a brief hollow core fiber (HCF) with a single-mode fiber (SMF) and filling the BPQDs-PVA compound into the HCF. When the proposed humidity sensor is placed in a humidity environment, BPQDs-PVA adsorbs water molecules in the air with increasing humidity, which changes the length of the FP cavity, as well as the refractive index of BPQDs-PVA, resulting in a spectral blueshift. The influence of the mixing ratio on humidity response properties has been experimentally investigated. A linear enhanced sensitivity of -0.7525n m/% R H within the humidity range of 45-75 %RH has been achieved. The maximum instability is 0.07 %RH in a long-term stability test, whereas the response and recovery times are 1.44 and 1.48 s, respectively.

4.
Eur J Public Health ; 31(5): 1042-1047, 2021 10 26.
Artículo en Inglés | MEDLINE | ID: mdl-34410370

RESUMEN

BACKGROUND: The joint effects of sex, age, body mass index (BMI) and race on hypertension have not been fully addressed. Herein, we carried out this study aiming to investigate the possible effects of the interaction of sex, age, BMI and race on risk of hypertension. METHODS: By using the data of a sample-adjusted 2656 women and 2515 men in American National Health and Nutrition Examination Survey 2015-16, we analyzed the interaction of sex, age, BMI and race by logistic regression models, followed by strata-specific analyses. Hypertension was defined as a systolic blood pressure ≥130 mmHg/diastolic blood pressure ≥80 mmHg or taking anti-hypertensive medication. RESULTS: A total of 5171 participants were included in analysis, and the prevalence of hypertension was 53.68%. The interactive effect of sex and age, BMI and age, race and age were statistically significant on hypertension. Strata-specific analyses showed that female at 40 years and above were positively associated with hypertension than those at 20-39 years. The associations also persistence in male. The risk estimates for age ≥40 on hypertension were consistently positive across all overweight/obesity and race groups. The effect was most prominent among overweight populations aged 60-80 years and Other Hispanic aged 40 years and above. CONCLUSION: There exists interactive effect of sex and age, BMI and age, race and age on hypertension in American population. The effect of age on hypertension was more prominent in female, overweight populations and Other Hispanic populations. Differences in age, BMI and race should be considered when providing corresponding antihypertensive measures.


Asunto(s)
Hipertensión , Presión Sanguínea , Índice de Masa Corporal , Estudios Transversales , Femenino , Humanos , Hipertensión/epidemiología , Masculino , Encuestas Nutricionales , Estados Unidos/epidemiología
5.
Environ Res ; 183: 109250, 2020 04.
Artículo en Inglés | MEDLINE | ID: mdl-32088608

RESUMEN

In this study, physicochemical analysis, thermogravimetric analysis, and kinetic analysis were used to investigate the effects of ultrasonic treatment on waste activated sludge (WAS), with emphasis on its kinetic parameters and pyrolysis behaviors. Thermogravimetric analysis results indicated that the pyrolysis of ultrasonic WAS might be divided into three stages. The main pyrolysis behavior occurred in the second stage (180-540 °C), and its pyrolysis behavior and activation energy were similar to the thermal decomposition of lignocellulosic biomass. Moreover, the physicochemical analysis indicated that ultrasonic treatment reduced the content of lignocellulose and ash, thus changing the pyrolysis characteristics of WAS. Ultrasonic WAS exhibited a higher residual weight (54.93 wt%), a larger average activation energy (140.09 kJ/mol), a lower maximum weight loss rate (-5.71%/min), and a change in the weight loss peak to a higher temperature (304.7 °C), reflecting the decrease of the pyrolysis reaction rate. In addition, the kinetic parameters were calculated using the Starink method and Coats-Redfern method.


Asunto(s)
Pirólisis , Aguas del Alcantarillado , Biomasa , Cinética , Termogravimetría , Ultrasonido
6.
Aviat Space Environ Med ; 85(9): 925-9, 2014 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-25197891

RESUMEN

INTRODUCTION: The objective of this study was to observe the differences in the biodynamic responses of male and female crewmembers during a simulated Soyuz spacecraft (short-duration flights) impact landing. METHODS: There were 16 volunteers (8 men and 8 women) recruited to sit in a pseudo-supine position and be exposed to several impact acceleration pulses. The acceleration peaks ranged from 7.7 to 11.8 g with a duration of around 50 ms. Acceleration responses from the drop platform and seat, and at the volunteers' head, shoulder, chest, and ilium were measured. RESULTS: Results indicated that there were significant gender-based differences in the peak acceleration measured from volunteers' shoulders and iliums. The peak decelerations measured at the head and ilium were relatively higher than those measured at other levels on the seat. DISCUSSION: It was recommended that more attention be focused on the sex differences of biodynamic responses of crews in the study of new protective designs for space capsule and personal life support equipment.


Asunto(s)
Aceleración , Factores Sexuales , Vuelo Espacial , Adulto , Fenómenos Biomecánicos , China , Femenino , Humanos , Ilion , Masculino , Seguridad , Hombro , Posición Supina
7.
Nanoscale ; 16(13): 6729-6738, 2024 Mar 28.
Artículo en Inglés | MEDLINE | ID: mdl-38497145

RESUMEN

The electrothermal coupling model of Pt/CoFe2O4/TiO2/TiN devices was established to study their resistive switching characteristics and basic biological synaptic properties in our research. The processes of set and reset are simulated, and the distribution of the temperature, the electric field and the concentration of oxygen vacancies in the dielectric layer are obtained. The switching performance of the TiO2-based device is significantly improved after the CoFe2O4 layer is inserted, with the switching voltage, working current and power consumption being reduced, while the switching ratio is increased. By changing the thermal conductivity of the top electrode, the rupture position of the conductive filament can be controlled. The I-V characteristics of the Pt/CoFe2O4/TiO2/TiN device during the reset and set processes are fitted linearly in logarithmic coordinates, and the ohmic conduction mechanism or the space-limited charge conduction mechanism is mainly satisfied in the high and low resistance states. Finally, the application of dual-layer devices on biological synapses is studied, and the basic biological characteristics of enhancement, inhibition and paired pulse promotion are simulated successfully. In addition, the redox reaction induced by oxygen vacancy migration also promotes the formation and rupture of the conductive filament. Results of the study show this ferrite material as an insertion layer in a resistive random-access memory structure that offers potential for future information storage and bioneuromorphic computation devices.

8.
Chemosphere ; 354: 141742, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38513951

RESUMEN

The accumulation of agricultural chemicals in the environment has become a global concern, of which sulfonylurea herbicides (SUHs) constitute a significant category. Solar-driven photocatalysis is favored for removing organic pollutants due to its high efficiency and environmental friendliness. Graphite carbon nitride (g-C3N4)-based materials with superior catalytic activities and physicochemical stabilities are promising photocatalysts. This review describes the g-C3N4-based materials and their uses in the photocatalytic degradation of SUHs or other organic pollutants with similar structures. First, the fundamentals of g-C3N4-based materials and photocatalytic SUHs degradation are discussed to provide an in-depth understanding of the mechanism for the photocatalytic activity. The ability of different g-C3N4-based materials to photocatalytically degrade SUH-like structures is then discussed and summarized based on different modification strategies (morphology modulation, elemental doping, defect engineering, and heterojunction formations). Meanwhile, the effects of different environmental factors on the photocatalytic performance of g-C3N4-based materials are described. Finally, the major challenges and opportunities of g-C3N4-based materials for the photocatalytic degradation of SUHs are proposed. It is hoped that this review will show the feasibility of photocatalytic degradation of SUHs with g-C3N4-based materials.


Asunto(s)
Contaminantes Ambientales , Catálisis
9.
J Hazard Mater ; 474: 134799, 2024 Aug 05.
Artículo en Inglés | MEDLINE | ID: mdl-38838527

RESUMEN

Estuaries and coasts are located at the land-sea interface, where sediment liquefaction due to strong wave action results in significant material exchange at the sediment-seawater system. Polycyclic aromatic hydrocarbons (PAHs), as organic pollutants, are distributed across various media. Herein, the impact of wave was studied on the release of PAHs through indoor microcosmic experiments combined with a level IV fugacity model. Comparison revealed that the release amount and rate of PAHs during static consolidation stage were minimal, whereas wave action substantially enhanced the release. Particularly the sediments in a liquefied state, the PAHs release in Stage III was 1.55-1.86 times that in Stage II, reaching 84.73 µg/L. The loss of soil strength and strong hydrodynamic effects resulted in a substantial release of PAHs into seawater along with suspended solids. Due to volatility of 2-ring PAHs and difficult desorption of 6-ring PAHs, 3-5-ring PAHs are the main contributors to releases into seawater. The model results also indicated that the three PAHs had different fates in the sediment-seawater system, with sediment serving as an important "reservoir" for benzo[a]pyrene entering seawater, while functioning as both a "sink" and a "source" for pyrene.

10.
Environ Pollut ; 349: 123933, 2024 May 15.
Artículo en Inglés | MEDLINE | ID: mdl-38583795

RESUMEN

The effects of two benthonic species, Perinereis aibuhitensis and Matuta planipes Fabricius, on the release of polycyclic aromatic hydrocarbons (PAHs) from sediments were investigated using a sediment-seawater microcosm. A Level IV fugacity model was used to simulate the behavior and fate of PAHs in the environment. This study revealed that both benthos significantly influenced the release of PAHs, and Matuta planipes Fabricius had a stronger disturbance effect than another. The final concentrations of Matuta planipes Fabricius group, Perinereis aibuhitensis group and the control group in the seawater phase reached 10.8, 9.94 and 7.90 µg/L, respectively. There were certain differences in the behaviour of the two benthonic species. Matuta planipes Fabricius caused more sediment resuspension, while Perinereis aibuhitensis increased the total organic carbon (TOC) content in the environment. The vertical concentration distribution of sediment indicated that vertical mixing was slightly stronger in the Matuta planipes Fabricius group than that in the Perinereis aibuhitensis group. The fugacity model effectively simulated the release behavior of PAHs, providing insight into PAH transport and distribution. The results demonstrated that bioturbation could promote the release of PAHs from seawater. The amount of PAHs released was significantly correlated with the biological habits of the benthos.


Asunto(s)
Sedimentos Geológicos , Hidrocarburos Policíclicos Aromáticos , Agua de Mar , Contaminantes Químicos del Agua , Hidrocarburos Policíclicos Aromáticos/análisis , Hidrocarburos Policíclicos Aromáticos/química , Sedimentos Geológicos/química , Contaminantes Químicos del Agua/análisis , Contaminantes Químicos del Agua/química , Agua de Mar/química , Monitoreo del Ambiente , Animales
11.
Sci Total Environ ; 879: 163057, 2023 Jun 25.
Artículo en Inglés | MEDLINE | ID: mdl-36966832

RESUMEN

The tremendous potential of hybrid technologies for the elimination of quinolone antibiotics has recently attracted considerable attention. This current work prepared a magnetically modified biochar (MBC) immobilized laccase product named LC-MBC through response surface methodology (RSM), and LC-MBC showed an excellent capacity in the removal of norfloxacin (NOR), enrofloxacin (ENR) and moxifloxacin (MFX) from aqueous solution. The superior pH, thermal, storage and operational stability demonstrated by LC-MBC revealed its potential for sustainable application. The removal efficiencies of LC-MBC in the presence of 1 mM 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) for NOR, ENR and MFX were 93.7 %, 65.4 % and 77.0 % at pH 4 and 40 °C after 48 h reaction, respectively, which were 1.2, 1.3 and 1.3 times higher than those of MBC under the same conditions. The synergistic effect of adsorption by MBC and degradation by laccase dominated the removal of quinolone antibiotics by LC-MBC. Pore-filling, electrostatic, hydrophobic, π-π interactions, surface complexation and hydrogen bonding contributed in the adsorption process. The attacks on the quinolone core and piperazine moiety were involved in the degradation process. This study underscored the possibility of immobilization of laccase on biochar for enhanced remediation of quinolone antibiotics-contaminated wastewater. The proposed physical adsorption-biodegradation system (LC-MBC-ABTS) provided a novel perspective for the efficient and sustainable removal of antibiotics in actual wastewater through combined multi-methods.


Asunto(s)
Quinolonas , Contaminantes Químicos del Agua , Lacasa/química , Aguas Residuales , Adsorción , Antibacterianos/química , Carbón Orgánico/química , Cinética , Contaminantes Químicos del Agua/química
12.
Sci Total Environ ; 891: 164340, 2023 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-37236473

RESUMEN

Estuarine sediments are key storage sites for persistent organic pollutants (POPs), and estuaries are strongly influenced by tides throughout the year. Although much work has been done concerning on POPs release, related questions on tidal action have not been considered in the release process. Herein, polycyclic aromatic hydrocarbons (PAHs) release from sediment to seawater was investigated under tidal action by combining a tidal microcosm with level IV fugacity model. The results showed that PAHs release with tidal action was 2.0-3.5 times the accumulation of that without tidal action. Tidal action was confirmed to influence strongly PAHs release from sediment to seawater. We also quantified suspended substance (SS) in the overlying water, and an obvious positive correlation between the PAHs concentration and SS content was found. In addition, an increase in seawater depth enhanced the intensity of tidal action, and more PAHs were released, especially dissolved PAHs. Moreover, the fugacity model results showed a good fit with the experimental results. The simulated values demonstrated that the PAHs release was accomplished via two processes, "rapid release" and "slow release". And the sediment played a key role in the fate of PAHs and was a major sink in the sediment-seawater system.

13.
J Hazard Mater ; 460: 132351, 2023 10 15.
Artículo en Inglés | MEDLINE | ID: mdl-37625296

RESUMEN

To understand the pollution status and risk levels in the Laizhou Bay, the spatiotemporal distribution, source, and ecological risk of 16 polycyclic aromatic hydrocarbons (PAHs) and 20 substituted PAHs (SPAHs) were studied in surface sediments in 2022. The findings indicated significant seasonal differences in the concentrations of PAHs and SPAHs under the influences of precipitation, temperature, light, and human activities, with higher storage levels in summer than in spring, and there was also a spatial distribution trend of estuary > coast > offshore. 2-Nitrofluorene (2-NF) and 2-methylnaphthalene (2-MN) were the most abundant components of SPAHs in both spring and summer, with levels of 21.44 ng/g and 17.89 ng/g in spring, 43.22 ng/g and 25.51 ng/g in summer, respectively. The results of the diagnostic ratio and principal component analysis - multiple linear regression identified sources of PAHs and SPAHs as combustion sources, including petroleum, coal, and biomass. The risk level of PAHs was low-to-moderate according to the toxicity equivalent quotient (TEQ) and risk quotient. A novel calculation method based on TEQ was proposed to assess the ecological risk of SPAHs, and the results indicated that the risk level of SPAHs was moderate-to-high.


Asunto(s)
Hidrocarburos Policíclicos Aromáticos , Humanos , Bahías , Biomasa , China , Medición de Riesgo
14.
Bioengineered ; 13(2): 4385-4396, 2022 02.
Artículo en Inglés | MEDLINE | ID: mdl-35139776

RESUMEN

As one of the most frequently prescribed antidiabetic drugs, metformin can lower glucose levels, improve insulin resistance manage body weight. However, the effect of metformin on islet microcirculation remains unclear. In the present study, to explore the effect of metformin on islet endothelial cells and investigated the underlying mechanism, we assessed the effects of metformin on islet endothelial cell survival, proliferation, oxidative stress and apoptosis. Our results suggest that metformin stimulates the proliferation of pancreatic islet endothelial cells and inhibits the apoptosis and oxidative stress caused by high glucose levels. By activating farnesoid X receptor (FXR), metformin increases the expression of vascular endothelial growth factor-A (VEGF-A) and endothelial nitric oxide synthase (eNOS), improves the production of nitric oxide (NO) and decreases the production of ROS. After the inhibition of FXR or VEGF-A, all of the effects disappeared. Thus, metformin appears to regulate islet microvascular endothelial cell (IMEC) proliferation, apoptosis and oxidative stress by activating the FXR/VEGF-A/eNOS pathway. These findings provide a new mechanism underlying the islet-protective effect of metformin.


Asunto(s)
Glucosa/efectos adversos , Islotes Pancreáticos , Metformina/farmacología , Animales , Apoptosis/efectos de los fármacos , Línea Celular , Proliferación Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Endotelio Vascular/citología , Islotes Pancreáticos/irrigación sanguínea , Islotes Pancreáticos/citología , Islotes Pancreáticos/efectos de los fármacos , Ratones , Microvasos/citología , Estrés Oxidativo/efectos de los fármacos
15.
Environ Technol ; 43(19): 2990-2999, 2022 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-33820487

RESUMEN

A new type of photocatalysts, nanocrystalline titanium dioxide (TiO2) doped with Co and I, were synthesized and modified via the sol-gel method to enhance the utilization of visible light. Herein, mono- and co-doped TiO2 (i.e. Co-TiO2, I-TiO2, Co-I-TiO2) were employed as the photocatalysts to investigate the photocatalytic performance on gaseous benzene removal. The prepared photocatalysts were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET)-specific surface areas, Raman spectroscopy, UV-visible diffuse reflectance spectroscopy (UV-vis-DRS), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL), and electrochemical impedance spectroscopy (EIS). Results indicated that both particle sizes and band gaps of TiO2 were significantly reduced by doping with Co/I. Also, the lattice defects and the specific surface areas of TiO2 were substantially augmented by adding Co/I because of the increase of oxygen vacancies, especially for Co-I-TiO2. Meanwhile, Co and I were distributed on the titanium base with the existence of multivalent states. The benzene treatment capacity of Co-I-TiO2, Co-TiO2, I-TiO2 and Pure TiO2 is 441.46, 424.36, 388.06, and 51.25 µgC6H6/(g·h), respectively. To sum up, photocatalytic degradation of gaseous benzene could be improved by doping with Co/I because of the extension of catalyst lifetime and light response range covering visible light.

16.
J Hazard Mater ; 413: 125318, 2021 07 05.
Artículo en Inglés | MEDLINE | ID: mdl-33578094

RESUMEN

High efficiency photocatalysts capable of disinfecting a broad-spectrum microorganisms are needed for the practical application of photodisinfection technology. Herein, we synthesized a highly efficient photodisinfection catalyst composed of Ti3+ self-doped TiO2 decorated with carbon dots (CDs) and palladium nano-photocatalyst, designated as Pd/CDs/Ti3+-TiO2, via a facile hydrothermal-calcination approach. XPS and ESR analyses were performed to verify that the composite contained Ti3+, while TEM imaging and FTIR confirmed that the samples contained CDs. The as synthesized photocatalysts, particularly the 1% Pd/CDs/Ti3+-TiO2 sample, exhibited superior photocatalyzed antibacterial activity to pure TiO2 against E. coli (~6.5 orders of magnitude increase at 30 min). The 1% Pd/CDs/Ti3+-TiO2 photocatalyst also exhibited efficient photodisinfection of five pathogenic agricultural fungi. The dark cytotoxicity of the 1% Pd/CDs/Ti3+-TiO2 nanocomposites was evaluated on HepG2 and Chinese hamster lung (V79) cells via Cell Counting Kit-8 (CCK-8) and found to be minimal. Lastly, the recycling capacity for the photodisinfective activity of the nanocomposites was evaluated and found to be unchanged after five cycles. Four active species were identified as contributing to the photoinduced antimicrobial activity of the catalyst: h+, •O2-, •OH, and e-. Together, our results indicate that Pd/CDs/Ti3+-TiO2 nanocomposites have great potential in agricultural plant pathogen disinfection.


Asunto(s)
Nanocompuestos , Titanio , Carbono , Desinfección , Escherichia coli , Hongos , Luz , Paladio
17.
Sheng Wu Yi Xue Gong Cheng Xue Za Zhi ; 27(2): 444-7, 2010 Apr.
Artículo en Zh | MEDLINE | ID: mdl-20481336

RESUMEN

Impact acceleration is one of the factors to which human body is exposed in aerospace exploring. When the impact level is greater than human tolerance, it usually results in human injuries which may be fatal. Therefore, in order to reduce or avert the risk of serious injury from crash impact, human tolerance to impact acceleration is a crucial consideration in aircraft since the beginning of aviation. The study on human tolerance to impact acceleration has become a cynosure in the realm of modern biomechanics. So this paper reviews the progress of the researches.


Asunto(s)
Aceleración/efectos adversos , Accidentes de Aviación , Adaptación Fisiológica , Medicina Aeroespacial , Fenómenos Biomecánicos , Simulación por Computador , Humanos
18.
Mater Sci Eng C Mater Biol Appl ; 107: 110344, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31761200

RESUMEN

TiO2/Cu2(OH)2CO3 nanocomposite were synthesized via a simple in-situ precipitation process, which was applied as efficient antimicrobials for the inactivation of Escherichia coli (E. coli) and Fusarium graminearum (F. graminearum) under simulated solar light. With optimum Cu2(OH)2CO3 amount of 1.8 mol%, the TiO2/Cu2(OH)2CO3 nanocomposite presented the highest antimicrobial activities against E. coli and F. graminearum, and achieved complete inactivation in 80 min, which was far better than that of bare TiO2. The boosted photocatalytic disinfection efficiency was ascribed to the increased light harvesting and efficient charge transfer and separation in the TiO2/Cu2(OH)2CO3 nanocomposite, which resulted in more efficient generation of •OH and •O2- that played important role in the photocatalytic inactivation process. Our work revealed that TiO2/Cu2(OH)2CO3 composite was a promising antimicrobial agent for prevention of pathogenic fungal or bacterial infections in crop protection.


Asunto(s)
Agroquímicos/química , Agroquímicos/farmacología , Carbonatos/química , Cobre/química , Productos Agrícolas/química , Nanocompuestos/química , Titanio/química , Antibacterianos/química , Antibacterianos/farmacología , Precipitación Química , Escherichia coli/efectos de los fármacos , Fungicidas Industriales/química , Fungicidas Industriales/farmacología , Fusarium/efectos de los fármacos , Luz , Procesos Fotoquímicos , Espectrofotometría Ultravioleta , Difracción de Rayos X
19.
Materials (Basel) ; 12(10)2019 May 27.
Artículo en Inglés | MEDLINE | ID: mdl-31137812

RESUMEN

The thread and spline synchronous rolling (TSSR) process is a new developed rolling process, which can form the different profiles simultaneously in the process and can ensure the consistency of the relative position of different profiles of parts. However, the multi-meshing motions are intercoupling and the multi-deformation characteristics are intercoupling during the forming process. It can easily result in dimension overshoot, and even does not make the synchronous rolling process go smoothly. Exploring the influence of controllable processing parameters on the synchronous rolling process, especially the geometric parameters of rolled parts, is helpful to determine the parameters and control the size error for a smooth rolling process. Thus, in this paper, the effects of controllable geometric parameters and motion parameters such as billet diameter, radial feed-in speed, and rotational speed of synchronous rolling die on the TSSR process have been studied. The synchronous rolling experimental scheme was determined using an orthogonal experimental design method, and the geometric parameters of different tooth profiles of rolled parts were measured and analyzed. The experimental results indicated that: the uncoordinated meshing movement between different tooth profiles is more likely to cause tooth error of the splined section of the part; variations of the processing parameters are more likely to cause fluctuations in the size of the splined section of the part, and change of the billet diameter mainly affects the outside diameter of the threaded and splined sections, and the threaded and splined pitches are mainly affected by the motion parameters of the synchronous rolling die; the motion parameters of the rolling die should be matched and the lower rotational speed needs to match the lower radial feed-in amount per revolution; the ideal dimensional accuracy can be obtained by using an appropriate processing parameter combination, for example, the pitch error of the splined section of the part is less than 0.5 µm under one set of experimental conditions in this paper.

20.
ACS Nano ; 13(2): 2004-2014, 2019 02 26.
Artículo en Inglés | MEDLINE | ID: mdl-30721027

RESUMEN

Bacterial cells can be inactivated by external reactive oxygen species (ROS) produced by semiconductor photocatalysis. However, little is known about cellular responses to photocatalysis. For a better understanding of this issue, one strain of Escherichia coli ( E. coli, hereafter named as MT), which has an increased ability to metabolize carbon sources, was screened out from the wild-type (WT) E. coli K12 by repeated exposure to photocatalysis with palladium oxide modified nitrogen-doped titanium dioxide. In this study, transcriptome sequencing of the WT and MT strains that were exposed or unexposed to photocatalysis were carried out. Cellular responses to photocatalysis were inferred from the functions of genes whose transcripts were either increased or decreased. Upregulation of expression of bacterial flagellar assembly genes used for chemotaxis was detected in cells exposed to semilethal photocatalytic conditions of the WT E. coli. Increased capability to degrade superoxide radicals and decreased bacterial flagellar assembly and chemotaxis were observed in MT E. coli compared to WT cells. We conclude that the differences in motility and intracellular ROS between MT and WT are directly related to survivability of E. coli during exposure to photodisinfection.


Asunto(s)
Escherichia coli/metabolismo , Catálisis , Escherichia coli/citología , Tamaño de la Partícula , Procesos Fotoquímicos , Especies Reactivas de Oxígeno/metabolismo , Semiconductores
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