Multi-response optimization of process parameters in nitrogen-containing gray cast iron milling process based on application of non-dominated ranking genetic algorithm.

As a new, high-strength and clean cast iron material, nitrogen-containing gray cast iron has excellent properties and a wide range of application prospects. However, the excellent material properties of the material not only make the machinability challenging, but also the high efficiency and quality of the machining process is a pressing issue. Therefore, it is necessary to study the machining characteristics of nitrogen-containing gray cast iron to obtain the optimal machining parameters to enrich the research work on nitrogen-containing gray cast iron. In this paper, the machining characteristics of nitrogen-containing gray cast iron are systematically studied, and the effects of cutting parameters on milling force, milling temperature, and surface roughness are analyzed. And, based on the machinability assessment, the objective function weights under different production requirements are determined by using hierarchical analysis trade-offs, and an integrated optimization model based on non-dominated ranking genetic algorithm and hierarchical analysis (AHP) is proposed. The model outputs the optimal combination of milling parameters by inputting the cutting speed (vc), feed rate per tooth (fz) and cutting depth (ap), surface roughness and cutting efficiency as the objective functions. The experimental results show that cutting depth has the greatest effect on the cutting force and cutting speed has the greatest effect on the cutting temperature and the surface roughness. The passivation effect of nitrogen on the graphite tip resulted in an increase in both cutting force and cutting temperature. The parameter optimization results indicated that the optimized roughing parameters significantly improve the surface quality while machining efficiently; the optimized finishing parameters improve Ra by 23.53% while ensuring higher MRR, which can achieve efficient and high-quality machining under different production requirements and provide an experimental basis for practical engineering applications of nitrogen-containing gray cast iron.

Ultralow-threshold green fluorescent protein laser based on high Q microbubble resonators.

Biological lasers have attracted vast attention because of their potential medical application prospects, especially the low threshold biological laser that can be used for ultrasensitive biological detection while leaving the luminous gain medium undamaged by the pump light. By coupling the low concentration green fluorescent protein (GFP) solution with a high Q whispering gallery mode microbubble resonator, we managed to fabricate a miniature GFP laser with the lowest threshold and highest Q value compared to any known type of the GFP laser. The threshold energy is as low as 380 fJ, two orders of magnitude lower than any type of GFP laser at present. The Q value of the optical cavity in this biological laser is 5.3 × 107, two orders higher than the highest Q value of GFP lasers. We further confirmed the long-term stability of the working characteristics of GFP laser. It can work well nearly a month in temperature 3-4°C. Finally, we measured the effects of different concentrations of fluorescent protein on laser threshold. The data show that this biological laser can be used for highly sensitive detection of GFP concentration, which is particularly useful when the GFP is used as tracers.

Enhanced anti-corrosion and biocompatibility of a functionalized layer formed on ZK60 Mg alloy via hydroxyl (OH-) ion implantation.

Magnesium and its alloys have piqued the interest of researchers due to their promising mechanical properties and biocompatibility. Moreover, the excessively fast corrosion rate of Mg alloys impedes their development in biomedical fields. Inspired by conventional ion implantation, a less-toxic functional group (hydroxyl) is used as the ion source to bombard the ZK60 Mg alloy surface to form a functionalized oxide layer. The surface characterization, corrosion resistance, and biocompatibility are systematically investigated before and after hydroxyl ion implantation. A smoother surface mainly constituted of hydroxide/oxide is formed for the treated samples. The formed functionalized layer significantly improves the corrosion resistance of the ZK60 Mg alloy substrate and the proliferation of MC3T3-E1 cells, as demonstrated by electrochemical, immersion, and in vitro cytocompatibility tests. In summary, less-toxic functional ion implantation can be an effective strategy for preventing corrosion of Mg alloy implants and promoting their biocompatibility.

Ultrastructure of Diophrys appendiculata and new systematic consideration of the euplotid family Uronychiidae (Protista, Ciliophora).

The ultrastructure of ciliates carries important cytological, taxonomical, and evolutionary signals for these single-celled eukaryotic organisms. However, little ultrastructural data have been accumulated for most ciliate groups with systematic problems. In the present work, a well-known marine uronychiid, Diophrys appendiculata, was investigated using electron microscopy and a comparison with, and a discussion considering, phylogenetic analyses were made. The new findings primarily show that: (i) this species lacks the typical alveolar plate, bears cortical ampule-like extrusomes, and has microtubular triads in the dorsal pellicle, and thus exhibits some ultrastructural features in common with most of its previously studied congeners; (ii) each adoral membranelle before the level of frontal cirrus II/2 contains three rows of kinetosomes and each membranelle after the level of frontal cirrus II/2 contains four rows, which might be related with morphogenesis and could be considered as a distinctive character of Diophrys; (iii) some structural details of the buccal field, such as the extra-pellicular fibrils, pellicle, pharyngeal disks and microtubular sheet, were documented. In addition, based on the ultrastructural comparison of representatives, we discuss the differentiation between the subfamilies Diophryinae and Uronychiinae. A hypothetical systematic relationship of members in the order Euplotida based on a wide range of data is also provided.

New Contributions to the Diversity of Hypotrichous Ciliates: Description of a New Genus and Two New Species (Protozoa, Ciliophora).

Ciliated protists (ciliates) are extremely diverse and play important ecological roles in almost all kinds of habitats. In this study, two new hypotrichs, Wilbertophrya sinica n. g. and n. sp. and Bakuella xianensis n. sp., from China are investigated. Wilbertophrya n. g. can be separated from related genera mainly by the combination of lacking a buccal cirrus, pretransverse cirri, and caudal cirri, while possessing frontoterminal cirri. Analyses based on morphological and molecular data confirm the validity of the species, W. sinica n. sp., which is characterized as follows: body 50-115 µm × 15-35 µm in vivo; midventral complex comprises four or five cirral pairs only and terminates above mid-body; three frontal, two frontoterminal cirri, and two to four transverse cirri; about 15 macronuclear nodules; colorless cortical granules sparsely distributed. Another new species, B. xianensis n. sp., was isolated from a freshwater wetland and is defined as follows: body 115-150 µm × 40-65 µm in vivo; about 70 macronuclear nodules; dark-brownish cortical granules in groups; midventral complex comprises 8-12 cirral pairs forming a row that terminates posteriorly in mid-body region and two or three short midventral rows that are continuous with the row of midventral pairs; three frontal, four to six frontoterminal, and three to five fine transverse cirri; three bipolar dorsal kineties. Phylogenetic analyses based on small subunit ribosomal DNA (SSU rDNA) sequence data suggest that the new genus Wilbertophrya n. g. belongs to an isolated clade, which might represent an undescribed taxon at the family level, whereas B. xianensis n. sp. groups with several congeners and members of other related genera are within the core urostylids.

Morphology, ontogenesis and molecular phylogeny of a new saline soil ciliate, Uroleptoides salina nov. spec. (Ciliophora, Hypotrichia).

The morphology, morphogenesis and molecular phylogeny of a new saline soil hypotrich ciliate, Uroleptoides salina nov. spec., discovered from China, was investigated. The new species is characterized as follows: body 150-215 × 40-50 µm in vivo, slender and highly flexible; usually four ellipsoidal macronuclear nodules; contractile vacuole absent; cortical granules absent; endosymbiotic algae present; amphisiellid median cirral row consists of 14-25 cirri and terminates about 47% down length of body; usually three buccal cirri and 3-13 cirri left of anterior portion of amphisiellid median cirral row; 3-5 transverse cirri. Morphogenesis during binary fission is characterized by: (1) the parental adoral zone of membranelles is retained completely, parental paroral contributes to the formation of the undulating membranes anlage for the proter; (2) the oral primordium of the opisthe is formed apokinetally; and (3) the amphisiellid median cirral row is formed from two anlagen. Phylogenetic analyses based on SSU rDNA sequence data show that Uroleptoides salina nov. spec. has a close relationship with its morphologically similar species, U. longiseries, U. magnigranulosus, Orthamphisiella breviseries, and Parabistichella variabilis.

Cell-division pattern and phylogenetic analyses of a new ciliate genus Parasincirra n. g. (Protista, Ciliophora, Hypotrichia), with a report of a new soil species, P. sinica n. sp. from northwest China.

BACKGROUND: Ciliated protists, a huge assemblage of unicellular eukaryotes, are extremely diverse and play important ecological roles in most habitats where there is sufficient moisture for their survivals. Even though there is a growing recognition that these organisms are associated with many ecological or environmental processes, their biodiversity is poorly understood and many biotopes (e.g. soils in desert areas of Asia) remain largely unknown. Here we document an undescribed form found in sludge soil in a halt-desert inland of China. Investigations of its morphology, morphogenesis and molecular phylogeny indicate that it represents a new genus and new species, Parasincirra sinica n. g., n. sp. RESULTS: The new, monotypic genus Parasincirra n. g. is defined by having three frontal cirri, an amphisiellid median cirral row about the same length as the adoral zone, one short frontoventral cirral row, cirrus III/2 and transverse cirri present, buccal and caudal cirri absent, one right and one left marginal row and three dorsal kineties. The main morphogenetic features of the new taxon are: (1) frontoventral-transverse cirral anlagen II to VI are formed in a primary mode; (2) the amphisiellid median cirral row is formed by anlagen V and VI, while the frontoventral row is generated from anlage IV; (3) cirral streaks IV to VI generate one transverse cirrus each; (4) frontoventral-transverse cirral anlage II generates one or two cirri, although the posterior one (when formed) will be absorbed in late stages, that is, no buccal cirrus is formed; (5) the posterior part of the parental adoral zone of membranelles is renewed; (6) dorsal morphogenesis follows a typical Gonostomum-pattern; and (7) the macronuclear nodules fuse to form a single mass. The investigation of its molecular phylogeny inferred from Bayesian inference and Maximum likelihood analyses based on small subunit ribosomal DNA (SSU rDNA) sequence data, failed to reveal its exact systematic position, although species of related genera are generally assigned to the family Amphisiellidae Jankowski, 1979. Morphological and morphogenetic differences between the new taxon and Uroleptoides Wenzel, 1953, Parabistichella Jiang et al., 2013, and other amphisiellids clearly support the validity of Parasincirra as a new genus. The monophyly of the family Amphisiellidae is rejected by the AU test in this study. CONCLUSIONS: The critical character of the family Amphisiellidae, i.e., the amphisiellid median cirral row, might result from convergent evolution in different taxa. Amphisiellidae are not monophyletic.

Morphology, morphogenesis and molecular phylogeny of a new soil ciliate Paragonostomoides xianicum n. sp. (Ciliophora, Hypotrichia, Gonostomatidae).

A hypotrichous ciliate, Paragonostomoides xianicum n. sp., was discovered in soil on the surface of the Xi'an Circumvallation, Xi'an, China. Its morphology and some major ontogenetic stages were studied and the phylogenetic position was estimated using standard methods Paragonostomoides xianicum n. sp. is characterized as follows: body size about 75-90×15-25µm in vivo, elliptical and flexible; colourless mitochondrion-like cortical granules scattered throughout cell surface, about 0.8×0.6µm in size; contractile vacuole positioned at mid-body; frontoventral row IV extends beyond buccal vertex and frontoventral row VI extends to about body end; frontoventral cirri not in pairs; transverse cirri absent; three caudal cirri; two macronuclear nodules and one to four micronuclei. The ontogenetic process in P. xianicum n. sp. is basically similar to that in Metagonostomum gonostomoidum and Gonostomum-species and featured by: frontoventral-transverse cirri develop in five-anlage pattern, the rearmost cirri generated in the two rightmost FV anlagen are not set off posteriorly (like an ordinary TC), as well as FVT-anlagen n and n-1 form in secondary mode in P. xianicum. Phylogenetic analyses based on small subunit ribosomal DNA sequence data reveal a close relationship of P. xianicum n. sp. with Cotterillia bromelicola and two Gonostomum-species.