Macro Morphology Research Articles

Influence of talc morphology on the mechanical properties of talc filled polypropylene

Injected polypropylene (PP)/talc composites were studied to evaluate the influence of different talc morphologies on their final mechanical properties. Talc genesis is responsible for type and content of associated minerals, crystalline degree, particle size distribution, and specially, morphology. Consequently, when talc is incorporated into PP, differences in the genesis mean differences in particle morphology and may influence the composite properties. Two talc samples having predominant macro and microcrystalline morphologies were used to prepare two composite sets to be tested. Thermal and mechanical properties of each PP/talc composites set were measured, analyzed and discussed comparatively. The results reveal that the main influences of talc morphology are given on modulus, yield strength and elongation at break of PP/talc composites. Macrocrystalline morphology of talc induces better composite mechanical properties than microcrystalline one. This behavior could be explained by talc characteristics as lamellarity, crystalline character and crystallinity degree.

Study on the SiC-Al Co-Continuous Phase Composites

SiC/Al co-continuous phase composites were fabricated by pressureless infiltration technology with reticulated silicon carbide porous ceramics as matrix and aluminum or magnesium as reinforcement phase. The effect of magnesium addition and holding time on the relative density, mechanical properties and macro morphology of the composites was investigated. The results showed that the porosity of SiC/Al co-continuous phase composites decreased with the increase of the holding time. The wettability of SiC and Al was improved with the addition of Mg. The hardness of SiC/Al co-continuous phase composites increased with the increase of the holding time. SiC and Al combined closely at longer holding time.

Corrosion Behavior of Low-Alloy Steel in COT Upper Deck O<sub>2</sub>-CO<sub>2</sub>-SO<sub>2</sub>-H<sub>2</sub>S Moisture Environment

This paper focus on the development of low-alloy anti-corrosion steel for the upper deck of COT(cargo oil tank), and the corrosion behavior of Cr-containing low-alloy steels in O2-CO2-SO2-H2S moisture were studied using homemade COT corrosion simulation device. After the corrosion experiment, related corrosion data was measured, and macro morphology and structure of corrosion scale were observed by SEM(Scanning Electron Microscope). The phase and chemical composition of corrosion product film were analyzed by XRD(X-ray diffraction) and EDS(energy dispersive spectroscopy). The effect of misorientation distribution on anti-corrosion property of steel was investigated by EBSD(electron backscattered diffraction). Based on the results, corrosion scale of COT on the upper deck consist of α-FeOOH, γ-FeOOH, FeS2, S and Fe1-xS, and the type of corrosion is mainly general corrosion. Cr enrichment was found on the inner corrosion product film, the addition of Cr leads to the increasing of low-angle grain boundaries and sub-grain structure which is conducive to the improvement of corrosion resistance.

Kerion caused by Microsporum audouinii in a child

Kerion celsi is rarely associated with Microsporum audouinii infection. We report the case of a 3-year-old girl with a kerion celsi caused by M. audouinii and successfully treated with oral terbinafine. Fungi identification was made by macro and microscopical colony morphology analyses and molecular (genotypic) studies.

Experimental Research on Energy Absorption Characteristic of PVB Laminated Windshield Subjected to Headform Low-speed Impact

Parametric dynamic experiments on various impact velocities(6.6-11.2 m/s), angles(60°-90°), directions are performed to obtain the energy characteristics of windshield under headform impact. Dynamic response of headform is systematically analyzed via the acceleration-time curve obtained by acceleration sensor. High-speed camera is employed to capture and analyze the crack propagation process. Macro damage morphology of windshield is discussed, and compared with it in real accident. With the definition of maximum contact force, maximum plastic hollow, head injury criteria, loss of headform kinetic energy and kinetic absorption ratio, the energy absorption characteristics of windshield under above mentioned parametric experiments are investigated. Experiment results may provide fundamental data and theoretical base for future research.

Research on the Morphology and Mechanical Properties of 304 Stainless Steels of Intergranular Corrosion

In the paper, the steel intergranular corrosion of 304 stainless steels was studied in detail with the method of copper sulfate. The macro morphology, mechanical property and metallurgical structure were also discussed by contrast of before and after corrosion. The results indicated that many trans-crystalline cracks and micro cracks were found on the surface of stainless steel. The max bending force was decreased from 7.225KN to 4.926KN; the deposited carbide was seen on corroded grain boundary with the dropping of grain. The conclusions are important to analysis of surface corrosion of stainless steel.

The Microstructure and Performance Analysis of HRB400 Rebar Manual Arc Welding Joints with Rebar Materials in Civil Engineering

Manual arc welding is widely used in all kinds of welding material in the civil engineering because of their stable performance characteristics. Based on the analysis of the incision morphology, microstructure and hardness distribution of different kinds of welding joints by manual arc welding methods, how the different welding method of hot rolling ribbed rebar influenced on the performance of the organization has been emphatically discussed to further optimize its performance and provides theoretical basis for the process. The experimental results show that due to the different welding methods and the different heat input, the macro morphology of each welding joints are not identical. The microstructure of welding joints are mainly formed by proeutectoid ferrite, low carbon martensite, tempered sorbite, fine grain ferrite and pearlite. Different welding method, the vickers hardness values along the axis direction of the welded joint and along the direction of cross section are also not identical, and all these lead to the different performance of the different welding joints.

Species complexes in Hericium (Russulales, Agaricomycota) and a new species - Hericium rajchenbergii - from southern South America

Species of the genus Hericium are generally recognized by macro morphology of their basidiomes, while they are very similar in the microscope. As a result, species boundaries are not always clear, and many collections are subsumed under incorrect names. We report on a thorough phylogenetic analysis based on ITS sequences to clarify the application of the most common names in the genus. H. alpestre, H. americanum, and H. erinaceus cannot readily be distinguished by their ITS sequences alone, while they are kept separate by characters from substrate preferences, geographical distribution, and macro morphology. A neotype is selected for H. alpestre. A well supported clade includes H. coralloides together with other, unnamed taxa. One of these, H. rajchenbergii from Argentina, is here described as new to science.

Urban particulate pollution reduction by four species of green roof vegetation in a UK city

Urban particulate pollution in the UK remains at levels which have the potential to cause negative impacts on human health. There is a need, therefore, for mitigation strategies within cities, especially with regards to vehicular sources. The use of vegetation as a passive filter of urban air has been previously investigated, however green roof vegetation has not been specifically considered. The present study aims to quantify the effectiveness of four green roof species – creeping bentgrass (Agrostis stolonifera), red fescue (Festuca rubra), ribwort plantain (Plantago lanceolata) and sedum (Sedum album) – at capturing particulate matter smaller than 10 μm (PM10). Plants were grown in a location away from major road sources of PM10 and transplanted onto two roofs in Manchester city centre. One roof is adjacent to a major traffic source and one roof is characterised more by urban background inputs. Significant differences in metal containing PM10 capture were found between sites and between species. Site differences were explained by proximity to major sources. Species differences arise from differences in macro and micro morphology of the above surface biomass. The study finds that the grasses, A. stolonifera and F. rubra, are more effective than P. lanceolata and S. album at PM10 capture. Quantification of the annual PM10 removal potential was calculated under a maximum sedum green roof installation scenario for an area of the city centre, which totals 325 ha. Remediation of 2.3% (±0.1%) of 9.18 tonnes PM10 inputs for this area could be achieved under this scenario.

Epiphytism and generic endemism in the Hypnodendrales: Cyrtopodendron, Franciella and macro–morphological plasticity

AbstractThe Hypnodendrales are an order of generally very robust pleurocarpous mosses in which most taxa have one of three distinct growth forms. The group includes four monotypic genera, two of which, Cyrtopodendron and Franciella, are endemic to New Caledonia. We investigate the phylogenetic relationships of these two taxa and of Pterobryella rigida, also a New Caledonian endemic, and demonstrate that Cyrtopodendron and Franciella should be recognised within Pterobryella and Spiridens respectively as P. vieillardii and S. spiridentoides. We further use Bayesian methods to reconstruct ancestral character states for macro–morphological type and substrate preference within the order, to evaluate hypotheses of correlated evolution of these morphological and ecological characters, and to test for directionality in their evolution. The results suggest that macro–morphology evolves in conjunction with shifts between epiphytic and non–epiphytic substrates, with the dendroid architecture strongly associated with non–epiphytic substrates and the morphologies we term “stipitate–frondose” and “spiri–dentoid” associated with epiphytism. Ancestral character state reconstruction challenges previous hypotheses that the strictly dendroid form is plesiomorphic within the Hypnodendrales and suggests that the stipitate–frondose architecture may have arisen very early within the evolution of the group, although states for the earliest nodes remain ambiguous. The spiridentoid growth form characteristic of Spiridens, Cyrtopus and Bescherellia may be inherited from a shared common ancestor, with the dendroid morphology of Hypnodendron s.str. being derived, while within Pterobryella the balance of evidence favours an epiphytic, stipitate–frondose common ancestor from which the lithophytic species found on New Caledonia and Lord Howe are descended. Transitions between the major growth forms found within the order are highly homoplastic, facilitating adaptive shifts between epiphytic and non–epiphytic substrates and explaining the paraphyly of some previously recognised genera and families.The Hypnodendrales are an order of generally very robust pleurocarpous mosses in which most taxa have one of three distinct growth forms. The group includes four monotypic genera, two of which, Cyrtopodendron and Franciella, are endemic to New Caledonia. We investigate the phylogenetic relationships of these two taxa and of Pterobryella rigida, also a New Caledonian endemic, and demonstrate that Cyrtopodendron and Franciella should be recognised within Pterobryella and Spiridens respectively as P. vieillardii and S. spiridentoides. We further use Bayesian methods to reconstruct ancestral character states for macro–morphological type and substrate preference within the order, to evaluate hypotheses of correlated evolution of these morphological and ecological characters, and to test for directionality in their evolution. The results suggest that macro–morphology evolves in conjunction with shifts between epiphytic and non–epiphytic substrates, with the dendroid architecture strongly associated with non–epiphytic substrates and the morphologies we term “stipitate–frondose” and “spiri–dentoid” associated with epiphytism. Ancestral character state reconstruction challenges previous hypotheses that the strictly dendroid form is plesiomorphic within the Hypnodendrales and suggests that the stipitate–frondose architecture may have arisen very early within the evolution of the group, although states for the earliest nodes remain ambiguous. The spiridentoid growth form characteristic of Spiridens, Cyrtopus and Bescherellia may be inherited from a shared common ancestor, with the dendroid morphology of Hypnodendron s.str. being derived, while within Pterobryella the balance of evidence favours an epiphytic, stipitate–frondose common ancestor from which the lithophytic species found on New Caledonia and Lord Howe are descended. Transitions between the major growth forms found within the order are highly homoplastic, facilitating adaptive shifts between epiphytic and non–epiphytic substrates and explaining the paraphyly of some previously recognised genera and families.

Customization of <em>Aspergillus niger</em> Morphology Through Addition of Talc Micro Particles

The filamentous fungus A. niger is a widely used strain in a broad range of industrial processes from food to pharmaceutical industry. One of the most intriguing and often uncontrollable characteristics of this filamentous organism is its complex morphology. It ranges from dense spherical pellets to viscous mycelia (Figure 1). Various process parameters and ingredients are known to influence fungal morphology 1. Since optimal productivity correlates strongly with a specific morphological form, the fungal morphology often represents the bottleneck of productivity in industrial production. A straight forward and elegant approach to precisely control morphological shape is the addition of inorganic insoluble micro particles (like hydrous magnesium silicate, aluminum oxide or titanium silicate oxide) to the culture medium contributing to increased enzyme production 2-6. Since there is an obvious correlation between micro particle dependent morphology and enzyme production it is desirable to mathematically link productivity and morphological appearance. Therefore a quantitative precise and holistic morphological description is targeted. Thus, we present a method to generate and characterize micro particle dependent morphological structures and to correlate fungal morphology with productivity (Figure 1) which possibly contributes to a better understanding of the morphogenesis of filamentous microorganisms. The recombinant strain A. niger SKAn1015 is cultivated for 72 h in a 3 L stirred tank bioreactor. By addition of talc micro particles in concentrations of 1 g/L, 3 g/L and 10 g/L prior to inoculation a variety of morphological structures is reproducibly generated. Sterile samples are taken after 24, 48 and 72 hours for determination of growth progress and activity of the produced enzyme. The formed product is the high-value enzyme β-fructofuranosidase, an important biocatalyst for neo-sugar formation in food or pharmaceutical industry, which catalyzes among others the reaction of sucrose to glucose 7-9. Therefore, the quantification of glucose after adding sucrose implies the amount of produced β-fructofuranosidase. Glucose quantification is made by a GOD/POD-Assay 10, which is modified for high-throughput analysis in 96-well micro titer plates. Fungal morphology after 72 hours is examined by microscope and characterized by digital image analysis. In doing so, particle shape factors for fungal macro morphology like Feret's diameter, projected area, perimeter, circularity, aspect ratio, roundness und solidity are calculated with the open source image processing program ImageJ. Relevant parameters are combined to a dimensionless Morphology number (Mn) 11, which enables a comprehensive characterization of fungal morphology. The close correlation of the Morphology number and productivity are highlighted by mathematical regression.

Customization of <em>Aspergillus niger</em> Morphology Through Addition of Talc Micro Particles

The filamentous fungus A. niger is a widely used strain in a broad range of industrial processes from food to pharmaceutical industry. One of the most intriguing and often uncontrollable characteristics of this filamentous organism is its complex morphology. It ranges from dense spherical pellets to viscous mycelia (Figure 1). Various process parameters and ingredients are known to influence fungal morphology 1. Since optimal productivity correlates strongly with a specific morphological form, the fungal morphology often represents the bottleneck of productivity in industrial production.A straight forward and elegant approach to precisely control morphological shape is the addition of inorganic insoluble micro particles (like hydrous magnesium silicate, aluminum oxide or titanium silicate oxide) to the culture medium contributing to increased enzyme production 2-6. Since there is an obvious correlation between micro particle dependent morphology and enzyme production it is desirable to mathematically link productivity and morphological appearance. Therefore a quantitative precise and holistic morphological description is targeted.Thus, we present a method to generate and characterize micro particle dependent morphological structures and to correlate fungal morphology with productivity (Figure 1) which possibly contributes to a better understanding of the morphogenesis of filamentous microorganisms.The recombinant strain A. niger SKAn1015 is cultivated for 72 h in a 3 L stirred tank bioreactor. By addition of talc micro particles in concentrations of 1 g/L, 3 g/L and 10 g/L prior to inoculation a variety of morphological structures is reproducibly generated. Sterile samples are taken after 24, 48 and 72 hours for determination of growth progress and activity of the produced enzyme. The formed product is the high-value enzyme β-fructofuranosidase, an important biocatalyst for neo-sugar formation in food or pharmaceutical industry, which catalyzes among others the reaction of sucrose to glucose 7-9. Therefore, the quantification of glucose after adding sucrose implies the amount of produced β-fructofuranosidase. Glucose quantification is made by a GOD/POD-Assay 10, which is modified for high-throughput analysis in 96-well micro titer plates.Fungal morphology after 72 hours is examined by microscope and characterized by digital image analysis. In doing so, particle shape factors for fungal macro morphology like Feret's diameter, projected area, perimeter, circularity, aspect ratio, roundness und solidity are calculated with the open source image processing program ImageJ. Relevant parameters are combined to a dimensionless Morphology number (Mn) 11, which enables a comprehensive characterization of fungal morphology. The close correlation of the Morphology number and productivity are highlighted by mathematical regression.

Effect of Ti–Si–Mg-Al wire on microstructure and mechanical properties of plasma arc in-situ welded joint of SiCp/Al composites

The influence of Ti–Si–Mg–Al wire on microstructure and mechanical properties of SiCp/Al metal matrix composite joints produced by plasma arc in-situ weld-alloying was investigated. Argon-nitrogen mixture was used as plasma gas and Ti–Si–Mg–Al flux-cored wires as filled composites. Weldments were submitted to tensile test. Meanwhile, the macro morphology and microstructure of the joints were examined. The result shows that the formation of needle-like harmful phase Al4C3 is effectively inhibited and the wettability of molten pool is improved by adding Ti–Si–Mg–Al flux-cored wires. With 15Ti-5Si-5Mg-Al flux-cored wire as filled composite, the maximum tensile strength of the welded joint is 267 MPa, which is up to 83% that of the matrix composites under annealed condition.

The effects and interactions of fabrication parameters on the properties of selective laser sintered hydroxyapatite polyamide composite biomaterials

PurposeHydroxyapatite‐polymer composite materials are being researched for the development of low‐load bearing implants because of their bioactive and osteoconductive properties, while avoiding modulus mismatch found in homogenous materials. For the direct production of hydroxyapatite‐polymer composite implants, selective laser sintering (SLS) has been used and various parameters and their effects on the physical properties (micro and macro morphologies) have been investigated. The purpose of this paper is to identify the most influential parameters on the micro and macro pore morphologies of sintered hydroxyapatite‐polymer composites.Design/methodology/approachA two‐level full factorial experiment was designed to evaluate the effects of the various processing parameters and their effects on the physical properties, including open porosity, average pore width and the percentage of pores which could enable potential bone regeneration and ingrowth of the sintered parts. The density of the sintered parts was measured by weight and volume; optical microscopy combined with the interception method was used to determine the average pore size and proportion of pores suitable to enable bone regeneration.FindingsIt was found that the effect of build layer thickness was the most influential parameter with respect to physical and pore morphology features. Consequently, it is found that the energy density equation with the layer thickness parameter provides a better estimation of part porosity of composite structures than the energy density equation without the layer thickness parameter. However, further work needs to be conducted to overcome the existing error of variance.Originality/valueThis work is the first step in identifying the most significant SLS parameters and their effects on the porosity, micro and macro pore morphologies of the fabricated parts. This is an important step in the further development of implants which may be required.

交变磁场对激光熔覆铁基复合涂层宏观形貌的影响及其微观组织演变

A alternative magnetic field generator is prepared by special circuits and active coils and the effects of different magnetic field intensities on the macro morphologies and microstructures of Fe-based composite coatings are studied by laser cladding process.Based on the electromagnetic principle and liquid metal solidification theory,it describes the solidification process of laser cladding coatings and reveals the main mechanism that magnetic field induced columnar dendrites transform into equiaxed crystals.The results show that the skin effect of liquid metal molten pool surface and alternating electromagnetic force allow the solidified cladding layer surface morphology to the wave form.The height of cladding layer and cross-section area decrease with the increase of magnetic field current,but the cladding layer width changes a little.The electromagnetic force in molten pool interior drives the dendrite ablation and mechanical break,and the free broken dendrites become a new nuclei to increase the nucleation rate,by which the top microstructure of cladding layer transforms from dendrite crystals to equiaxed crystals.Furthermore,the equiaxed crystal zone becomes wider with the increase of magnetic field current,but the bottom microstructure has a little change.

Evaluation of crystal structure of porous Si nanowires prepared by metal assisted etching

ABSTRACTThe macro and micro morphology of the Si surface, depending on noble metal ion concentration in etching solution, prepared by metal assisted etching were investigated. We defined the morphology of etched Si in four types, and developed the phase diagram of Si morphology. Mixture of silver nitrate (AgNO3) and hydrofluoric acid (HF) was used as an electroless-plating bath of Ag, as well as etching solution of Si. The morphology of the etched Si surface as function of concentration of AgNO3 in etching solution was observed by SEM. With increasing concentration of the AgNO3 in the etching solution, the surface of etched Si tended to be porous structure with very fine pores of a few nm (porous Si). When concentration of AgNO3is low, single crystal Si nanowires with a smooth surface without pores were observed.

A Surface Melting Infiltration Study on Cast Magnesium Alloy

A new technique has been developed by infiltration during casting process to AZ91D magnesium alloy part. Through a melting process a alloyed surface layer was formed on the surface of the part in casting process, and the surface layer helps improve the corrosion resistance. The macro morphology, thickness, microstructure and properties of the layer were analyzed by digital, scanning electron microscopy, spectroscopy and corrosion measurement system. The results show that a uniform and dense infiltration layer on the surface of AZ91D part was obtained. This technique can fundamentally change the physical and chemical properties of magnesium alloy parts. More importantly, it is low-cost, green and environmental protection.

Isolation, characterization and long term preservation of mutant strains of Xanthophyllomyces dendrorhous

The yeast Xanthophyllomyces dendrorhous is biotechnologically important due to its ability to produce the pigment astaxanthin, but is poorly understood at the genetic level. This is mainly because its preservation is difficult and many of the mutants obtained are unstable. The objectives of the present work were (i) the mutagenesis X. dendrorhous and, (ii) isolation of mutants with auxotrophic markers suitable for genetic studies of the carotenogenesis pathway and sexual cycle. Additionally, two kinds of preservation methods at the laboratory level were tested for the storage of strains. A collection of X. dendrorhous mutants affected in the production of carotenoid pigments or development of sexual structures and auxotrophic requirements were isolated by treatment with N-methyl-N'-nitro-N-nitrosoguanidine and the antibiotic nystatin. From a detailed analysis about the requirements of auxotrophic mutants the ARG7, ARG3 and PRO3 loci can be defined in this yeast. Among the methods assayed for the long-term preservation of X. dendrorhous strains, the dehydrated gelatin drop method showed the highest recovery of viable yeast after storage for 65 months. No changes in auxotrophic properties and in macro or micro morphology were observed after applying the latter method.

Seed macro and micro morphology of the selected Nigella (Ranunculaceae) taxa from Turkey and their systematic significance

Macro and micromorphological properties of intact and mature seeds of 12 taxa (species and varieties) belonging to Nigella L. (Ranunculaceae) was investigated using light and scanning electron microscopy. Material studied covers 11 species of 15 Turkish Nigella. Studied taxa were divided into two types. Type I has ovate to orbicular seeds that includes four species. Type II has triquedrous seeds and includes seven species. Type II was subdivided into two. Type IIa has triquedrous to subpyramidal seeds (five species) and Type IIb has triquedrous to subglobose seeds (two species). Further segregation was performed micromorphologically and an identification key of studied Nigella taxa was given. Studied Nigella taxa have a diverse macro and micromorphological characters that utilize to separate them from each other to assess the systematics of Nigella.

A combined chemo-mechanical approach for aesthetic management of superficial enamel defects

The aim of this article is to describe an easy technique for managing small superficial defects in light to medium fluorosis. The proposed technique is based on a selective abrasion of the superficial enamel and a recreation of the superficial macro and micro morphology. The aesthetic appearance can be enhanced by power or home bleaching. The presented technique can manage enamel defects which are confined in the most external enamel surface with satisfying aesthetic results. This conservative approach may be considered an interesting alternative to more invasive prosthetic techniques based on composite reconstructions or ceramic veneers, minimising invasivity, chairside time and costs for patients.