Recent progress in anodic oxidation of TiO2 nanotubes and enhanced photocatalytic performance: a short review

© 2021 World Scientific Publishing Company. This is the accepted version of the final published version found at https://doi.org/10.1142/S1793292021300024By adjusting the oxidation voltage, electrolyte, anodizing time and other parameters, TiO2 nanotubes with high aspect ratio can be prepared by oxidation in organic system because anodic oxidation method has the advantage of simple preparation process, low material cost and controllable morphology. Low material cost and controllable morphology by anodizing. This review focuses on the influence of anodizing parameters on the morphology of TiO2 nanotube arrays prepared by anodizing. In order to improve the photocatalytic activity of TiO2 nanotubes under visible light and prolong the life of photo-generated carriers, the research status of improving the photocatalytic activity of TiO2 nanotubes in recent years is reviewed. This review focuses on the preparation and modification of TiO2 nanotubes by anodic oxidation, which is helpful to understand the best structure of TiO2 nanotubes and the appropriate modification methods, thus guiding the application of TiO2 nanotubes in practical photocatalysis. Finally, the development of TiO2 nanotubes is prospected.Peer reviewe

Heat stress affects tassel development and reduces the kernel number of summer maize

Maize grain yield is drastically reduced by heat stress (HTS) during anthesis and early grain filling. However, the mechanism of HTS in reproductive organs and kernel numbers remains poorly understood. From 2018 to 2020, two maize varieties (ND372, heat tolerant; and XY335, heat sensitive) and two temperature regimens (HTS, heat stress; and CK, natural control) were evaluated, resulting in four treatments (372CK, 372HTS, 335CK, and 335HTS). HTS was applied from the nine-leaf stage (V9) to the anthesis stage. Various morphological traits and physiological activities of the tassels, anthers, and pollen from the two varieties were evaluated to determine their correlation with kernel count. The results showed that HTS reduced the number of florets, tassel volume, and tassel length, but increased the number of tassel branches. HTS accelerates tassel degradation and reduces pollen weight, quantity, and viability. Deformation and reduction in length and volume due to HTS were observed in both the Nongda 372 (ND372) and Xianyu 335 (XY335) varieties, with the average reductions being 22.9% and 35.2%, respectively. The morphology of the anthers changed more conspicuously in XY335 maize. The number of kernels per spike was reduced in the HTS group compared with the CK group, with the ND372 and XY335 varieties showing reductions of 47.3% and 59.3%, respectively. The main factors underlying the decrease in yield caused by HTS were reductions in pollen quantity and weight, tassel rachis, and branch length. HTS had a greater effect on the anther shape, pollen viability, and phenotype of XY335 than on those of ND372. HTS had a greater impact on anther morphology, pollen viability, and the phenotype of XY335 but had no influence on the appearance or dissemination of pollen from tassel

An in-situ method for assessing soil aggregate stability in burned landscapes

Due to soil repellency in burned areas, slope runoff and soil erodibility escalates following forest fires, increasing the vulnerability to post-fire debris flows. Soil aggregate stability is a critical determinant of soil infiltration capacity and erosion susceptibility. The prevalent method of assessing soil aggregate stability in burned areas, the counting the number of water drop impacts (CND) method, is time-intensive and impractical for in-situ measurements. In response, this study introduces a novel technique based on the shock and vibration damage (SVD) effect for evaluating soil aggregate stability in burned areas. Thirteen distinct soil aggregate types were meticulously prepared for indoor simulated fire testing, with due consideration to factors such as bulk weight, organic matter content, and water repellency, which influence stability of soil aggregates. Employing a custom-built test apparatus, the mass loss rate (MLR) of soil aggregates was determined through orthogonal experiments using the SVD method and compared against the standard CND technique's quantification of water droplet-induced aggregate destruction. The findings demonstrated that SVD method, employing Test Scheme 6 (testing 20 aggregates, 1-meter impact height, 40% water content, and five impacts), exhibits excellent agreement (Kendall coefficient = 0.797) and correlation (R2 = 0.634) with CND method outcomes. This testing scheme, characterized by rapid determination and effective discrimination, is identified as the optimal testing approach. The SVD testing apparatus is straightforward, portable, and easily disassembled, rendering it suitable for on-site use. It can be used to distinguish the stability level of soil aggregates swiftly and quantitatively under various fire intensities in burned areas in situ, which is an important guiding significance for the study of soil erosion, erosion control, and post-fire debris flow initiation mechanism in burned areas

Coherent control of a high-orbital hole in a semiconductor quantum dot

Coherently driven semiconductor quantum dots are one of the most promising platforms for non-classical light sources and quantum logic gates which form the foundation of photonic quantum technologies. However, to date, coherent manipulation of single charge carriers in quantum dots is limited mainly to their lowest orbital states. Ultrafast coherent control of high-orbital states is obstructed by the demand for tunable terahertz pulses. To break this constraint, we demonstrate an all-optical method to control high-orbital states of a hole via stimulated Auger process. The coherent nature of the Auger process is proved by Rabi oscillation and Ramsey interference. Harnessing this coherence further enables the investigation of single-hole relaxation mechanism. A hole relaxation time of 161 ps is observed and attributed to the phonon bottleneck effect. Our work opens new possibilities for understanding the fundamental properties of high-orbital states in quantum emitters and developing new types of orbital-based quantum photonic devices.Comment: Manuscript with 14 pages and 6 figures plus supplementary Information comprising 15 pages and 14 figure

Radiomic Features From Multi-Parameter MRI Combined With Clinical Parameters Predict Molecular Subgroups in Patients With Medulloblastoma

The 2016 WHO classification of central nervous system tumors has included four molecular subgroups under medulloblastoma (MB) as sonic hedgehog (SHH), wingless (WNT), Grade 3, and Group 4. We aimed to develop machine learning models for predicting MB molecular subgroups based on multi-parameter magnetic resonance imaging (MRI) radiomics, tumor locations, and clinical factors. A total of 122 MB patients were enrolled retrospectively. After selecting robust, non-redundant, and relevant features from 5,529 extracted radiomics features, a random forest model was constructed based on a training cohort (n= 92) and evaluated on a testing cohort (n= 30). By combining radiographic features and clinical parameters, two combined prediction models were also built. The subgroup can be classified using an 11-feature radiomics model with a high area under the curve (AUC) of 0.8264 for WNT and modest AUCs of 0.6683, 0.6004, and 0.6979 for SHH, Group 3, and Group 4 in the testing cohort, respectively. Incorporating location and hydrocephalus into the radiomics model resulted in improved AUCs of 0.8403 and 0.8317 for WNT and SHH, respectively. After adding gender and age, the AUCs for WNT and SHH were further improved to 0.9097 and 0.8654, while the accuracies were 70 and 86.67% for Group 3 and Group 4, respectively. Prediction performance was excellent for WNT and SHH, while that for Group 3 and Group 4 needs further improvements. Machine learning algorithms offer potentials to non-invasively predict the molecular subgroups of MB.</p

Improving the corrosion resistance of MgZn1.2GdxZr0.18 (x =0, 0.8, 1.4, 2.0) alloys via Gd additions

Funding Information: This research was financially supported by the National Key Research and Development Program of China (Grant No. 2016YFB0301101 ), the National Natural Science Foundation of China (Grant No. 51971054 ) and the Fundamental Research Funds for the Central Universities (Grant Nos. N180904006 and N2009006 ). Publisher Copyright: © 2020 Elsevier LtdEffects of Gd addition on microstructure, corrosion behavior and mechanism of cast and extruded MgZn1.2GdxZr0.18 alloys are investigated through microstructure observation, weight loss and electrochemical tests. Increasing Gd from 0 to 2.0 at.%, grains are refined, MgZn2 phase, W-phase and X-phase are formed successively, and basal texture intensity is decreased. The significantly decreased grain size by extrusion and Gd addition induces formation of protective Gd2O3 and MgO layer. The extruded MgZn1.2Gd2.0Zr0.18 alloy shows decreased corrosion rate of 3.72 ± 0.36 mm/year, owing to fine and homogeneous microstructure, dual-role (micro-anode and barrier) of X-phase, compact oxidation layer and basal crystallographic texture.Peer reviewe

Metal nanoparticle carbon nanocomposites to produce electrochemical devices for environmental water monitoring

Aquesta tesi se centra en el desenvolupament de sensors electroquímics miniaturitzats de baix cost i fàcils d'utilitzar per a l'anàlisi de la matèria orgànica, compostos halogenats i metalls pesants en aigües. Amb aquesta finalitat, s'adapten diversos materials funcionals, sintetitzats i processats per fabricar sensors de pel·lícula gruixuda i de pel·lícula prima mitjançant processos industrials com son ara la serigrafia i litografia. Es preparen tres materials compostos d'elèctrodes que comprenen una matriu de carboni porosa i nanopartícules metàl·liques o d'òxid metàl·lic. S'estudien diversos processos de síntesi química sol-gel per produir un material nanocomposite de nanopartícules de coure i una matriu de carboni. Amb l'objectiu de contribuir a l'economia circular i buscar una alternativa més sostenible per produir aquests materials, es prepara una matriu de carboni porosa dopada amb nanopartícules de plata utilitzant residus de pa impregnats amb un precursor de nanopartícules de plata. A més, materials de carboni porós es preparen a partir de subproductes de la fusta i es modifiquen amb nanopartícules de bismut. Els materials desenvolupats s'avaluen electroquímicament mitjançant elèctrodes de pasta per després produir lots d'elèctrodes d'un sol ús serigrafiats que s'apliquen a la detecció dels analits diana ja esmentats. Els elèctrodes de carboni de pel·lícula prima també es produeixen sobre substrats de Si/SiO2 mitjançant una síntesi de material sol-gel combinada i un procés de fotolitografia/gravat en sec a nivell de oblia. Les cèl·lules electroquímiques convencionals de tres elèctrodes de configuració plana es produeixen i es desenvolupen com a dispositius sensors per detectar la càrrega orgànica mitjançant l'electrodeposició de nanopartícules de coure (Cu NPs) a l'elèctrode de treball en condicions potenciostàtiques controlades. A més, es fabrica una plataforma fluídica senzilla que inclou una cèl·lula de flux per integrar els elèctrodes de carboni de pel·lícula prima i dur a terme l'electrodeposició de Cu NPs i la detecció de càrrega orgànica de manera automàtica.Esta tesis se centra en el desarrollo de sensores electroquímicos miniaturizados de bajo coste y fácil manejo para el análisis de materia orgánica, compuestos halogenados y metales pesados en aguas. Con este este propósito, varios materiales funcionales se sintetizan y procesan a medida para fabricar sensores de película gruesa y película delgada mediante procesos industriales disponibles de serigrafía y litografía. Se preparan tres materiales compuestos para la fabricación de electrodos que comprenden una matriz porosa de carbono y nanopartículas metálicas o de óxidos metálicos. Se estudian procesos de síntesis química sol-gel para producir un material nanocompuesto de nanopartículas a base de cobre y una matriz carbono. Con el objetivo de contribuir a la economía circular y buscar una alternativa más sostenible para la producción de estos materiales, se prepara una matriz de carbono poroso dopada con nanopartículas de plata a partir de residuos de pan impregnados con un precursor de nanopartículas de plata. Además, materiales compuestos de carbono poroso se preparan a partir de subproductos de la madera y se modifican con nanopartículas de bismuto. Los materiales desarrollados se evalúan electroquímicamente utilizando electrodos de pasta para después producir lotes de electrodos de un solo uso serigrafiados que se aplican a la detección de los analitos diana ya mencionados. Los electrodos de carbono de película delgada también se producen en sustratos de Si/SiO2 mediante una síntesis combinada de material sol-gel y un proceso de fotolitografía/grabado en seco a nivel de oblea. Las celdas electroquímicas convencionales con una configuración de tres electrodos y de geometría planar se producen y desarrollan como dispositivos sensores para detectar carga orgánica mediante la electrodeposición de nanopartículas de cobre (Cu NP) en el electrodo de trabajo en condiciones potenciostáticas controladas. Además, se fabrica una plataforma fluídica sencilla que incluye una celda de flujo para integrar los electrodos de carbono de película delgada y realizar la electrodeposición de Cu NP y la detección de carga orgánica de forma automática.This thesis focuses on developing low-cost and easy-to-use miniaturized electrochemical sensors for the analysis of the organic matter, halogenated compounds and heavy metals in waters. For this purpose, several functional materials are tailored synthesized and processed to fabricate thick-film and thin-film sensors by screen-printing and lithography available industrial processes. Three electrode composite materials are prepared that comprise a porous carbon matrix and metal or metal oxide nanoparticles. Several sol-gel chemical synthesis approaches are studied to produce a carbon copper-based nanoparticle nanocomposite material. With the aim of contributing to the circular economy and looking at a more sustainable alternative for producing these materials, a silver nanoparticle-doped porous carbon matrix is prepared using bread waste impregnated with a silver nanoparticle precursor. Also, porous carbon composites are prepared from wood by-products and further modified with bismuth nanoparticles. The developed materials are electrochemically evaluated using paste electrodes before producing large batches of commercial-like screen-printed single-use electrodes that are applied to the detection of the already mentioned target analytes. Thin-film carbon electrodes are also produced on Si/SiO2 substrates by a combined sol-gel material synthesis and photolithography/dry etching process at the wafer level. Conventional three-electrode electrochemical cells of planar configuration are produced and developed as sensor devices for detecting organic load by electrodepositing copper nanoparticles (Cu NPs) on the working electrode under controlled potentiostatic conditions. In addition, a simple fluidic platform is fabricated that includes a flow cell to integrate the thin-film carbon electrodes and carry out the Cu NPs electrodeposition and organic load detection in an automatic fashion.

Influence of Electric Current and Magnetic Flow on Firing Patterns of Pre-Bötzinger Complex Model

The dynamics of neuronal firing activity is vital for understanding the pathological respiratory rhythm. Studies on electrophysiology show that the magnetic flow is an essential factor that modulates the firing activities of neurons. By adding the magnetic flow to Butera’s neuron model, we investigate how the electric current and magnetic flow influence neuronal activities under certain parametric restrictions. Using fast-slow decomposition and bifurcation analysis, we show that the variation of external electric current and magnetic flow leads to the change of the bistable structure of the system and hence results in the switch of neuronal firing pattern from one type to another