A new small-celled diatom from Brazil - Luticola minutissima sp. nov., with comparison to the type of the Antarctic L. neglecta Zidarova, Levkov & Van de Vijv

The samples for this study were collected from terrestrial mosses and lichens growing on palm tree trunks and concrete walls in the city of Rio de Janeiro, south-eastern Brazil. During the investigation on diatom diversity, a new species from the genus Luticola was found. The new species occurred individually at all sampling sites. The aim of this paper is to provide a morphological and ecological description of Luticola minutissima sp. nov. from an aerophytic environment. The species is characterized by a small valve size (5.2–16.8 μm length and 3.7–4.4 wide) and abruptly hooked proximal raphe endings (ca. 90-degree angle). Additionally for comparison, type material of the most similar species, Luticola neglecta Zidarova, Levkov & Van de Vijver, was studied and new information for the ultrastructure of the latter species is provided as well.

Analysis of the advanced oxygenate water level control scheme of the engineering supercritical unit

The oxygenate water level is an important adjustment parameter in the operation of the fire generator set, and the water level may result in the safety of the water pump. The high water level will not only affect the oxygen effect, but it is also possible to cause the water shot to the steam turbine to cause a water shot or give the water tank full water, oxygenate vibration, drain and vapor with water. When the load is low (generally 35% rated load), the oxygenate water level is controlled by large and small valve, condensate pump variable frequency control condensed water drum pressure. When the unit load is high (greater than 35 rated load), the oxygenate water level is controlled by the condensed water pump, the large valve and small valve controls condensed water drum pressure.

Study on the eccentric jet-flow characteristics induced by the opening regulation with a gate valve

Valve-induced flow characteristics were often concerned in many fluid transportation and control industries. In this paper, the eccentric jet-flow characteristics induced by a gate valve have been studied by considering the influence of valve opening regulation. The experimental setup of monitoring the downstream pressures along the pipeline was developed, and corresponding numerical simulation was employed. The downstream-monitoring pressure distribution caused by valve opening regulation was investigated to verify the flow simulation. The generation mechanism of eccentric jet-flow was revealed as a strong pressure gradient caused by the throttling effect at the valve throat. It was found that the eccentric jet-flow evolved in the pipeline was accompanied by shearing vortices, extremely under a small valve opening. The pressure and axial velocity distributions at various downstream cross-sections of the eccentric jet-flow evolving in the pipeline were analyzed. The axial velocities on four monitoring lines in downstream cross-sections were extracted, and the radial location of the maximum axial velocity was derived to assess the eccentric characteristics of jet-flow. A dimensionless parameter of velocity eccentric ratio was introduced to quantify the eccentric intensity of the evolving jet-flow in the downstream pipeline, and its correlation with the pipeline length could be adequately expressed by a natural decreasing exponential curve via fitting analysis. By virtue of that correlation, the critical pipeline length was proposed that can be used as the judgment to the terminal of the eccentric jet-flow evolving in the downstream pipeline. This study was helpful to characterize the valve-induced flow characteristics in scientific research and provide useful insight into fluid and mechanical engineering.

A new species of Basilaphelenchus Pedram, Kanzaki, Giblin-Davis & Pourjam, 2018 (Aphelenchoidea: Tylaphelenchinae), from natural forests of Golestan province, Iran

Summary Two populations of an aphelenchoidid nematode were recovered from natural forests in Golestan province, Iran. Both populations resembled each other morphologically. The females of the first population, from rotten wood of Fagus orientalis in Golestan National Park, measured 294-338 μm long, and females of the second population, from forests of Ramian county, measured 365-464 μm long. A reverse taxonomic approach, based upon SSU and LSU phylogenies using a maximal number of Aphelenchoididae genera, revealed the two isolates to be conspecific and representatives of a new species of Basilaphelenchus. Basilaphelenchus magnabulbus n. sp. is described and illustrated herein and is mainly characterised by the unique form of the metacorpus, this being elongate and filling the corresponding body region similar to the common form in other aphelenchoidids (vs smaller with well posteriorly located small valve in previously described species of the genus). The new species has an elevated lip region, fine stylet with three elongate posteriorly directed knobs, female tail elongate conoid and ventrally bent, and male tail short conical with three pairs of caudal papillae. It was morphologically compared with four previously known species of the genus, viz., B. persicus, B. brevicaudatus, B. gorganensis and B. grosmannae, and three species of Aphelenchoides having a broadly similar morphology.

NEW METHOD OF ESTIMATION OF THE RELATIVE AREA OF PERFORATIONS ON VALVES OF CENTRIC DIATOMS USING SEM IMAGES ON THE EXAMPLE OF MINIDISUS VODYANITSKIYI LYAKH ET BEDOSHVILI

The diatoms interact with the environment through the siliceous frustule. The total area of frustule perforations determines the ability of diatom to exchange nutrients, gases and other matters. The aim of the present study was to estimate the area of perforations on the valve surface of a centric diatom. In the paper we describe a method for the estimation of the area of perforations on a diatom valve using SEM images. The method is tested on valves of centric diatom Minidiscus vodyanitskiyi Lyakh et Bedoshvili. The results show that the total area of cribral pores is less than 5% of the total valve area. This value is consistent with the relative perforation of land plants leaves, which is less than 3%. We hypothesize that such small valve area occupied by perforations is usual for many other centric diatom species. To verify this hypothesis additional researches are necessary.

Two new diatom species (Bacillariophyceae) from Brazilian floodplain: Actinella hermes-moreirae sp. nov. and Gomphonema mutunensis sp. nov.

Floodplains are heterogeneous ecosystems that occupy a large area in the neotropic regions, which show great diatom diversity. During a floristic survey of periphytic and sedimentary samples in a swamp from the Upper Paraná River Floodplain in Brazil, a new species of Actinella Lewis and Gomphonema Ehrenberg (Bacillariophyceae) were found. We detailed their morphology using light and scanning electron microscopy. Actinella hermes-moreirae sp. nov. is distinguished by its small valve lengths, low length to width ratio, moderately arched valves, absence of spines and the slightly arched termination of the raphe. Gomphonema mutunensis sp. nov. differs by the rostrate and sub-rostrate headpole, attenuated-rounded footpole and differently-shaped areolae.

The genus Colura section Gamolepis (Lejeuneaceae, Marchantiophyta) in Malesian region, with the description of Colura sigmoidea

The taxonomic account of the genus Colura sect. Gamolepis in the Malesian region is presented based on fresh materials from field surveys and herbarium specimens. Five species are recognised including: C. cristata, C. meijeri, C. valida, C. verdoornii, and one new species, C. sigmoidea, described and illustrated. The new species is similar to C. cristata, but differs in having dioicous sexuality, ovate to lanceolate lobule sac ending with a small apical crest (consisting of 3–5 cells), small valve consisting of 30–40 cells and basal median cells of valve adnate with hinge cells forming a sigmoid curve in outline. A key to species, taxonomic descriptions and illustrations are provided; ecology and geographical distribution of the species are noted.

Tiny diatoms Minidiscus vodyanitskiyi sp. nov. (Bacillariophyta) from the Sea of Azov and consideration of polygonal areolae pattern

A new tiny species of Minidiscus, M. vodyanitskiyi, was found in the water column collected from the central part of the Sea of Azov. Its morphology was examined by scanning electron microscopy, described and illustrated. This centric diatom is characterized by: 1) small valve diameter of less than 10 µm; 2) one central fultoportula surrounded by two satellite pores located opposite each other; 3) one rimoportula located one areola away from the central fultoportula which internally appears similar to a slit surrounded by a plan elliptic rim oriented radially or slightly tangentially; 4) 4–6 (10) marginal fultoportulae that are equally spaced on a border between the valve surface and valve mantle; 5) three satellite pores that surround every marginal fultoportula, where a central satellite pore is directed towards the valve margin; 6) hexa- or heptagonal pattern of valve areolae; and 7) a hyaline conical flange connects the cingulum with the valve. The new species is compared with similar ones. A new term ‘polygonal areolae pattern’ is proposed instead of ‘eccentric pattern’. The term emphasizes that the pattern comprises concentric polygons formed by tangential areolae rows. Its qualitative characteristic, ‘polygonality’, has been described which allows more precise differentiation of the geometry of the valve pattern and describing areolae size variability.

Investigation of the unsteady-flow characteristics in the control valve of a diesel engine unit pump fuel system

The control valve determines the fuel offloading process of the high-pressure fuel system in diesel engines. During the fuel offloading process, when the control valve instantaneously opens, the inlet pressures and the outlet pressures of the valve change quickly, and the inner flow of the control valve is transient and unsteady. This study presents an investigation into the flow characteristics in the control valve region during the fuel-offloaded process of a diesel unit pump fuel system, studies the reasons for unsteady-flow conditions and further analyses the effects on the flow capacity of the valve based on the computational fluid dynamics method. The results reveal that the key reason for unsteady flow in the control valve is the dynamic movement of the valve needle, which induces changes in the inlet pressure and the outlet pressure so that the fluid in the conical region accelerates. In comparison with steady flow, unsteady flow in the control valve has different pressures in the conical region and at the conical outlet, different cavitation intensities and different locations of the bubbles. Moreover, the differences between unsteady flow and steady flow become greater, particularly for small valve needle openings. Unsteady flow in the control valve greatly influences the fuel offloading process of the unit pump fuel system.