Calcium Carbonate Mineralization in a Surface-Tension-Confined Droplets Array

Calcium carbonate biomimetic crystallization remains a topic of interest with respect to biomineralization areas in recent research. It is not easy to conduct high-throughput experiments with only a few macromolecule reagents using conventional experimental methods. However, the emergence of microdroplet array technology provides the possibility to solve these issues efficiently. In this article, surface-tension-confined droplet arrays were used to fabricate calcium carbonate. It was found that calcium carbonate crystallization can be conducted in surface-tension-confined droplets. Defects were found on the surface of some crystals, which were caused by liquid flow inside the droplet and the rapid drop in droplet height during the evaporation. The diameter and number of crystals were related to the droplet diameter. Polyacrylic acid (PAA), added as a modified organic molecule control, changed the CaCO3 morphology from calcite to vaterite. The material products of the above experiments were compared with bulk-synthesized calcium carbonate by scanning electron microscopy (SEM), Raman spectroscopy and other characterization methods. Our work proves the possibility of performing biomimetic crystallization and biomineralization experiments on surface-tension-confined microdroplet arrays.

Evaluation and identification of dynamic strain on a blast door subjected to blast loading using fibre Bragg grating sensors

Tunnels and subway blast doors are effective barriers to terrorist attacks and emergencies, and research into the mechanical properties of blast doors under explosive dynamic loads can improve and enhance the performance thereof. In this article, surface strain measurements on subway blast door models under dynamic load are carried out using quasi-distributed fibre Bragg grating sensors. The principle underpinning fibre Bragg grating sensing is introduced before the experiment. In the experiment, a model of an explosion-proof door was designed, and the experimental foundation pit was designed to be used to fix the explosion-proof door. Then, eight fibre Bragg grating sensors are placed at different positions on the surface of the explosion door to measure the strain at the time of explosion. Through the experiment we found that the optical fibre grating sensing system can be used under explosive loading surface strain: the strain distribution on the surface of the protective door is revealed under large dynamic strain. At the same time, the rebound effect of the protective door in the explosion was found through the strain phenomenon in double peak phenomenon. The strain distribution and rebound effect in the test results can provide a useful reference for the mechanical design of the blasting door and the strain monitoring of reinforced concrete structures under dynamic load.

Article selection and anaphora in the German relative clause

German definite articles are able to contract with prepositions under certain conditions. When a noun phrase is discourse anaphoric, contraction is blocked. In the current paper we present a puzzle: restrictive relative clauses require the use of the non-contracted (strong) article form, despite their apparent lack of anaphoricity; both the determiner of the head noun and the relative pronoun (which is, in most cases, syncretic with the definite article) surface with the strong form. We provide a uniform analysis of discourse anaphoric and relative clause uses that makes use of contexts, as defined in the dynamic framework of de Groote (2006). We argue that a lexical item, which we call “anaph”, whose purpose is to make reference to an individual provided by the context, intervenes between the noun and the article in the strong form. anaph makes reference to an individual provided by the global context in cases of anaphora, and to an individual provided by an updated local context in the case of relative clauses.

Experimental Validation of an Innovative Metallic Tile Holder System for a Ceramic Combustor Liner

In gas turbine, the enhancement of durability and the increase of reliability represent essential requirements. These issues become even more critical for components subjected to high thermal loads, as the combustion chamber, and go in parallel with the desire for higher efficiency, which resulted in a reduced amount of air that the cooling systems designers have available for the combustor liner. This work presents the results of an experimental campaign aimed to evaluate the performance on a portion of the combustion chamber liner of the latest Ansaldo Energia AE64.3A+ gas turbine. In this configuration ceramic tiles replace the previous metallic heat shields, reducing coolant consumption up to 40%. The designed test article is made up of two ceramic bricks, held on the shells by means of air cooled metallic tile holders, and is installed in a dedicated plenum chamber where is run over by an air flow from several angles of incidence in order to simulate some realistic turbine conditions. A preliminary numerical study is conducted to estimate the test article surface pressure distributions in order to evaluate the mainstream flow impact on the tile holder cooling system behaviour. A novel application of Pressure Sensitive Paint (PSP) technique is applied to evaluate the air seal cooling of the brick holder system, essential to prevent hot gas ingestion. Furthermore, infrared (IR) thermography measurements on the liner are performed using an hot mainstream flow and reproducing typical cooling flow conditions. During the tests, several thermocouples, allocated on most critic brick holder components, continuously check the metal temperature.

Fruit as diagnostic characteristic to recognize Brazilian species of Zornia (Leguminosae, Papilionoideae)

Articles of the lomentaceous fruits encountered in the thirty-six species of Brazilian Zornia species are described, illustrated and compared using scanning electron microscopy and stereomicroscopy. Macro-and micro-morphological characters of the fruit articles provide excellent diagnostic taxonomic characters (including fruit shape, fruit article surface, presence/absence of glands, presence/absence of bristles, and presence/absence of hairs) to distinguish among the Brazilian taxa. Results generally support the species recognised for Brazil although the micro-morphological characters have limited taxonomic value within some species complexes, in which taxa can be better differentiated using other morphological characteristics. The results of macro-morphological analyses show that the morphology of fruit articles is related to the geographical distribution pattern of each species and is a good source of morphological character to distinguish the species of Zornia. We present here an inedit identification key, based on the loment morphology, to distinguish the Brazilian species of Zornia.

On the Vibrational Behavior of Piezoelectric Nano-Beams

In this article surface effects are considered to study the electromechanical coupling behavior of piezoelectric nanobeams with the non-local Euler-Bernoulli beam theory. The equation of motion for piezoelectric nanobeams with considering both surface effect and nonlocal effect is achieved and exact term for natural frequencies is derived for simply supported conditions. In the following the axial load effect on the natural frequencies piezoelectric nanobeams has been studied.