采用水基前驱溶液喷墨印刷制备光催化活性TiO2薄膜

摘译 近年来,作为一种高能量带隙半导体,二氧化钛(TiO2)由于在紫外光照射下具有良好的光催化活性,已引起科研人员的广泛关注.由于TiO2无色透明,具有广泛的应用前景,如薄的TiO2涂层可用于创建自清洁、防雾、超亲水表面.同时,也能用于太阳能电池等光电子行业. 化学溶液沉积法因具有相对简单的大面积生产工艺,且较低的制膜成本和高可用性,成为TiO2薄膜制备常用的方法之一.针对另一种TiO2制备方法,即溶胶凝胶法,大量研究文献主要关注乙醇的水解控制.然而,工业需求鼓励开发水基前驱设计.其难度在于钛醇盐与水的高反应性.在有机介质中,加入少量的水往往导致水解.因此,需要采用络合剂作为稳定剂,阻止纯水中的水解反应和避免由此产生的产物沉淀.     

Release of reduced inorganic selenium species into waters by the green fresh water algae Chlorella vulgaris

The common green fresh water algae Chlorella vulgaris was exposed to starting concentrations of 10 μg/L selenium in the form of selenate, selenite, or selenocyanate (SeCN(-)) for nine days in 10% Bold's basal medium. Uptake of selenate was more pronounced than that of selenite, and there was very little uptake of selenocyanate. Upon uptake of selenate, significant quantities of selenite and selenocyanate were produced by the algae and released back into the growth medium; no selenocyanate was released after selenite uptake. Release of the reduced metabolites after selenate exposure appeared to coincide with increasing esterase activity in solution, indicating that cell death (lysis) was the primary emission pathway. This is the first observation of biotic formation of selenocyanate and its release into waters from a nonindustrial source. The potential environmental implications of this laboratory observation are discussed with respect to the fate of selenium in impacted aquatic systems, the ecotoxicology of selenium bioaccumulation, and the interpretation of environmental selenium speciation data generated, using methods incapable of positively identifying reduced inorganic selenium species, such as selenocyanate.     

Is there a future for antioxidants in atherogenesis?

Antioxidants, preferentially those of dietary origin, have for a long time been considered to help against diseases that are presumably aggravated by oxidative stress, such as cardiovascular diseases, cancer, and neurodegenerative disorders. The outcome of clinical trials undertaken to corroborate this hypothesis, however, remained largely inconclusive. Evidence is now emerging that some dietary "antioxidants" influence signaling pathways and the expression of genes relevant in atherosclerosis by mechanisms other than antioxidative ones. By concrete examples we show that (1) vitamin E has gene regulatory functions which might be more important than acting as an antioxidant in vivo, (2) selenium itself is not an antioxidant at all, and even not in general when incorporated into glutathione peroxidases, and (3) a moderate oxidative stress is beneficial rather than detrimental since it can induce defense mechanisms counteracting xenobiotic and oxidative stress. Thus, there is only a future for antioxidants in the prevention of any disease if their real mechanism of action is considered and suitable read-outs and biomarkers are established.     

‘Why Can’t the Future be More Like the Past?’ Planning History Track,Association of European Schools of Planning (AESOP), Annual Congress,Department of Civic Design,University of Liverpool, 15–18 July 2009

AESOP’s 2009 Congress was hosted by the University of Liverpool as part of the centenary celebration of its Department of Civic Design, the world’s oldest university planning school. ‘Why Can’t the Future be More Like the Past?’ was the conference title on all the banners and conference bags – an oddly querulous question, nevertheless it did the trick in getting participants to think historically throughout AESOP 2009. Michael Hebbert and Dirk Schubert ran a planning history track for six of the conference’s seven parallel session slots. Their call for papers elicited 30 abstracts which reduced to 17 papers, a comfortable quantity allowing good time for presentation and discussion. The track had the fortune to be allocated a wood‐panelled Architecture lecture theatre with superb projection facilities – more than one speaker gasped at the glory of their own PowerPoint images.     

Pre-adolescent children exhibit lower aerosol particle volume emissions than adults for breathing,speaking, singing and shouting

Speaking and singing are activities linked to increased aerosol particle emissions from the respiratory system, dependent on the utilized vocal intensity. As a result, these activities have experienced considerable restrictions in enclosed spaces since the onset of the COVID-19 pandemic due to the risk of infection from the SARS-CoV-2 virus, transmitted by virus-carrying aerosols. These constraints have affected public education and extracurricular activities for children as well, from in-person music instruction to children’s choirs. However, existing risk assessments for children have been based on emission measurements of adults. To address this, we measured the particle emission rates of 15 pre-adolescent children, all eight to ten years old, with a laser particle counter for the test conditions: breathing at rest, speaking, singing and shouting. Compared with values taken from 15 adults, emission rates for breathing, speaking and singing were significantly lower for children. Particle emission rates were reduced by a factor of 4.3 across all conditions, whereas emitted particle volume rates were reduced by a factor of 4.8. These data can supplement SARS-CoV-2 risk management scenarios for various school and extracurricular settings.     

Photochemie von Acylaziden. VIII [1]. Reagieren Acylnitrene wie 1,3-Dipole??

Photochemistry of Acylazides. VIII. Do Acylnitrenes React like 1,3-Dipoles? The formation of three- ore five-membered heterocyclic rings by the reaction of acylnitrenes with olefins depends on the electron density at the double bond. The generally expected formation of aziridines by a cheletropic reaction was observed by photolysis of aroylazides 1 in the presence of 2,5-dihydrofuran 2 . But with enolethers 3 and 4 oxazolines were directly formed. This [3 + 2] cycloaddition is regiospecific. The cycloaddition is modestly stereoselective by steric hindrance within the cyclic enolether 3b . Very small de-values were found with chiral substituents in the acylazide 13 . The azide decomposition was also achieved by photoinduced electron transfer. The same cycloaddition products as obtained by direct photolysis of the azides were obtained via radical anions of the acylazide. Using Michler's ketone as electron donor in the triplet state the formation of isocyanate which diminishes the yield of cycloadducts can be avoided.     

SMART-Reactors: Tailoring Gas Holdup Distribution by Additively Manufactured Lattice Structures

In chemical process engineering, fast gas-liquid reactions often suffer from an inefficient distribution of gas and therefore mixing and mass transfer performance. This study deals with the possibility of influencing the local gas holdup and bubble size distribution in a gas-liquid process using additively manufactured lattice structures (AMLS). The used measuring technique to study bubble size, velocity, and the local gas holdup is a photo-optical needle probe. By using AMLS, a significant radial homogenization of the local gas holdup and the mean bubble size is achieved. Furthermore, it can be demonstrated that the bubble size can be tailored by the geometry of the inserted structure. It is illustrated that the mean bubble velocities are lowered within the lattice resulting in a higher residence time of the dispersed phase with an impact on the mass transfer performance within the AMLS.     

Direct Observation of Worm‐Like Nanochannels and Emergent Magnon Motifs in Artificial Ferromagnetic Quasicrystals

Quasicrystalline structures and aperiodic metamaterials find applications ranging from established consumer gadgets to potential high‐tech photonic components owing to both complex arrangements of constituents and exotic rotational symmetries. Magnonics is an evolving branch of magnetism research where information is transported via magnetization oscillations (magnons). Their control and manipulation are so far best accomplished in periodic metamaterials which exhibit properties artificially modulated on the nanoscale. They give rise to functional components, such as band stop filters, magnonic transistors and nanograting couplers. Here, spin‐wave excitations in artificial ferromagnetic quasicrystals created via aperiodic arrangement of nanoholes are studied experimentally. Their ten‐fold rotational symmetry results in multiplexed magnonic nanochannels, suggesting a width down to 50 nm inside a so‐called Conway worm. Key elements of design are emergent magnon motifs and the worm‐like features which are scale‐invariant and not present in the periodic metamaterials. By imaging wavefronts in quasicrystals, insight is gained into how the discovered features materialize as a dense wavelength division multiplexer.     

13C-NMR Spectroscopic Detection of Malto-oligosaccharide Complexes

Fragments of amylose were enzymatically synthesized and purified to α-(a→4)-glucans of well defined degress of polymerization by preparative size exclusion chromatography. Maltooligosaccharides from DP 3 to 12 were subjected to ¹³C-NMR-spectroscopy. The addition of iodine as a complexing agent selectively affected the carbon atoms involved in the glycosidic bond. Resonances of C-1 and C-4 experienced a dramatic downfield shift. This is interpreted as a change of conformation of the amylose helix. The shift differences can be measured conveniently and be used for calculations of complex stability constants. Maltohexaose and higher saccharides gave strong effects upon complexation, indicating that one helical turn brings about a gain in helical stability. No lower chain-length limit for the complex-forming capacity was observed. Even the smallest fragments of amylose showed complexing behaviour.