Potential of CLSM in studying some modern and fossil palynological objects

We have tested possibilities and limitations of confocal laser scanning microscopy to study the morphology of pollen and spores and inner structure of sporoderms. As test objects, we used pollen grains of the modern angiosperm Ribes niveum (Grossulariaceae) and Datura metel (Solanaceae), fossil angiosperm pollen grains of Pseudointegricorpus clarireticulatum and Wodehouseia spinata dated to the Late Cretaceous, fossil gymnosperm pollen grains of Cycadopites‐type dated to the Middle Jurassic, and fossil megaspores Maexisporites rugulaeferus, M. grosstriletus, and Trileites sp. dated to the Early Triassic. For comparative purpose, we studied the same objects with application of conventional light, scanning electron (to entire pollen grains and spores or to semithin sections of their walls), or transmission electron microscopy. The resolution of confocal microscope is much lower than that of electron microscopes, as are its abilities to reconstruct the surface patterns and inner structure. On the other hand, it can provide information that is unreachable by other microscopical methods. Thus, the structure of endoapertures in angiosperm pollen grains can be directly observed. It is also helpful in studies of asymmetrical pollen and pollen grains bearing various appendages and having complicated exine structure, because rotation of 3‐D reconstructions allows one to examine all sides and structures of the pollen grain. The exact location of all visible and concealed structures in the sporoderm can be detected; this information helps to describe the morphology and inner structure of pollen grains and to choose necessary directions of further ultrathin sectioning for a transmission electron microscopical study. In studies of fossil pollen grains that are preserved in clumps and stuck to cuticles, confocal microscope is useful in determining the number of apertures in individual pollen grains. This can be done by means of virtual sections through 3‐D reconstructions of pollen grains. Fossil megaspores are too large and too thick‐walled objects for a confocal study; however, confocal microscope was able to reveal a degree of compression of fossil megaspores, the presence of a cavity between the outer and inner sporoderm layers, and to get some information about sporoderm inner structure.     

A novel and effective multistage classification system for microscopic starch grain images

This article presents a novel and effective multistage system for classifying Chinese Materia Medica microscopic starch grain images. The proposed classification system is constructed based on the Gaussian mixture model‐based clustering, the feature assignment algorithm, and the similarity measurement. Several features for each starch grain image are extracted and every class of drug is represented by a set of characteristic features. For each stage of the system, only one feature is chosen and assigned to that stage via the feature assignment algorithm, and the corresponding characteristic features are subdivided into smaller subsets based on clustering techniques. At the final stage, each subset contains a certain class of drugs (with corresponding characteristic features) and similarity measurement is carried out for starch grain classification. Three sets of the current state‐of‐the‐art starch grain features including the granulometric size distribution, the chord length distribution, and the wavelet signature are used to construct the system. Experimental results on a database of 240 images of 24 classes of drugs reveal the superior performance of the multistage system. Comparison with the traditional starch grain classification approaches indicates that our proposed multistage method produces a marked improvement in classification performance. Microsc. Res. Tech. 2009. © 2009 Wiley‐Liss, Inc.     

Pollen morphology of Chinese Pseudostellaria (Caryophyllaceae) and its systematic significance

Using light and scanning electron microscopy, we studied the pollen morphology of six species (one of which are endemic) of Chinese Pseudostellaria. All species were studied for the first time. Results of this study indicated that pollen grains of Pseudostellaria are spheroidal or spheroidal‐polyhedral in shape and small or medium in size and pantoporate. Each pollen grain has 12–16 round pores. These pores are apart from each other by 5.77–7.73 μm and each has 7–13 granules in the operculum region. These features have important taxonomic significance. In addition, their pollen grains have thin exine with microechinate‐punctate‐perforate surface ornamentation. Pollen features do not support the traditional infrageneric classification of Pseudostellaria into two sections, but support that Pseudostellaria is closely related to other species of the Odontostemma clade.     

Comparative authentication of three “snow lotus” herbs by macroscopic and microscopic features

“Snow lotus” is a famous Chinese Materia Medica derived from species of the genus Saussurea (Compositae). To differentiate three representative easily‐confused snow lotus herbs, namely, Saussurea involucrata (Kar. et Kir.) Sch.‐Bip, Saussurea laniceps Hand.‐Mazz., and Saussurea medusa Maxim., macroscopic features of the three herbs were systemically observed, and microscopic features were compared by using ordinary light microscopy, polarized light microscopy and scanning electron microscopy (SEM). The results indicate that, as for macroscopic identification, capitula situation and arrangement, and as for microscopic identification, pollen grains, nonglandular hairs, glandular hairs, and cells of inner surface of the microdiodange can be used to authenticate the three snow lotus herbs. Comprehensive table comparing the characteristics were presented in this study. SEM has been found to provide a number of unique characteristics of pollen grains. Based on the observation of pollen grains, evolution sequence of the three species was speculated. The present method was proven to be efficient, convenient, simple, and reliable, which was successfully applied to the authentication of three snow lotus herbs. Microsc. Res. Tech.1 77:631–641, 2014. © 2014 Wiley Periodicals, Inc.     

Pollen micromorphological analysis of tribe Acacieae (Mimosaceae) with LM and SEM techniques

The morphology of pollen grains of the 06 species of tribe Acacieae (Mimosaceae) belonging to one genus were investigated using scanning electron microscopic (SEM) and light microscopic (LM) approach. Lactic acid acetolysis method was used for (LM) while non‐acetolysis for (SEM). The species were examined for the both qualitative and quantitative palynological features. Qualitatively the pollen was studied for the shape, exine sculpturing, pollen shape, and pollen type. Oblate spheroidal shape of pollen was observed in Accacia modesta. Subprolate shape in Accaca nilotica. In Accacia farnesiana, prolate pollen was examined while prolate spheroidal in Acacia tortilis and spheroidal pollen grains were studied in Acacia catechu, respectively. Pollen exine sculpturing of the studied tribe possesses novel variation. Foveolate, reticulate, foveolate‐psilate, faint reticulate, fossulate, perforate, and scrabate exine sculpturing were noticed. Colpi were absent in all species. Excessive variation was observed in both qualitative and quantitative character of pollen. SPSS software was use for the quantitative measurement of the pollen grains. The current study will be helpful for the identification of the problematic species and phylogenetic studies of family Mimosaceae.     

Morpho‐palynological study of Cyperaceae from wetlands of Azad Jammu and Kashmir using SEM and LM

In this study 12 species of Cyperaceae have been studied for quantitative and qualitative observation of pollen grains through Light and scanning electron microscopy. Pollens of 12 species of Cyperaceae from different wetlands of Azad Jammu and Kashmir were collected. Morphological characters of pollen grains were then investigated under the Light and Scanning electron microscope. Two pollen types have been observed apolar and heteropolar. Shape of pollens was prolate (4 spp), sub‐spheroidal (7 spp), and oblate (1 spp). Variation observed in exine sculpturing granular (4 spp), reticulate (1 spp), areolate‐punctate (3 spp), and psilate (2 spp). Polar to equatorial ratio and fertility percentage of the pollens were also studied. Based on these micromorphlogical characters of pollens taxonomic keys have been made for the accurate identification of the members of Cyperaceae. The characteristics studied in present research work are very much valuable taxonomically and phytochemically for the identification of species of family Cyperaceae. Light microscope (LM) and Scanning electron microscope (SEM) were used for pollen observation, which play vital role in the taxonomical identification of species and provide sufficient information for taxonomist.     

Palyno‐morphological investigations of halophytic taxa of Amaranthaceae through SEM from Salt range of Northern Punjab,Pakistan

The pollen morphology of 11 salt tolerant plant species of family Amaranthaceae from the salt range of Northern Punjab, Pakistan has been studied. The palyno‐morphological characters were examined using light and scanning electron microscope. The examined all salt tolerant species have a slight difference in size but have similarity in shape, pore ornamentation, and polarity. The observed morphological characters of pollen grains were pollen symmetry, size, shape, pore ornamentation, pore size, number of pores, exine thickness, polar and equatorial diameter and, P/E ratio. Apolar type of pollens has been observed in all species. Shape of pollens was spheroidal. Exine sculpturing of pollen grains was scabrate (six spp), microechinate (four spp), and microechinate‐scabrate (one spp). Different pori numbers were observed in different species. The pantoporate aperturate and sunken pore ornamentation have been reported in all species. A pollen taxonomic key was developed using examined morphological characters for the accurate identification of halophytic taxa. The high fertility and low sterility of pollens confirmed that the selected halophytes are well‐established in the salt region. The findings highlight the taxonomic significance of pollen morphology in correct identification and differentiation of salt tolerant plant species.     

Multi‐label classification for colon cancer using histopathological images

Colon cancer classification has a significant guidance value in clinical diagnoses and medical prognoses. The classification of colon cancers with high accuracy is the premise of efficient treatment. Our task is to build a system for colon cancer detection and classification based on slide histopathological images. Some former researches focus on single label classification. Through analyzing large amount of colon cancer images, we found that one image may contain cancer regions of multiple types. Therefore, we reformulated the task as multi‐label problem. Four kinds of features (Color Histogram, Gray‐Level Co‐occurrence Matrix, Histogram of Oriented Gradients and Euler number) were introduced to compose our discriminative feature set, extracted from our dataset that includes six single categories and four multi‐label categories. In order to evaluate the performance and make comparison with our multi‐label model, three commonly used multi‐classification methods were designed in our experiment including one‐against‐all SVM (OAA), one‐against‐one SVM (OAO) and multi‐structure SVM. Four indicators (Precision, Recall, F‐measure, and Accuracy) under 3‐fold cross‐validation were used to validate the performance of our approach. Experiment results show that the precision, recall and F‐measure of multi‐label method as 73.7%, 68.2%, and 70.8% with all features, which are higher than the other three classifiers. These results demonstrate the effectiveness and efficiency of our method on colon histopathological images analysis. Microsc. Res. Tech. 76:1266–1277, 2013. © 2013 Wiley Periodicals, Inc.     

Evidence of multimicrometric coherent γ′ precipitates in a hot‐forged γ–γ′ nickel‐based superalloy

This paper demonstrates the existence of large γ’ precipitates (several micrometres in diameter) that are coherent with their surrounding matrix grain in a commercial γ–γ’ nickel‐based superalloy. The use of combined energy dispersive X‐ray spectrometry and electron backscattered diffraction (EBSD) analyses allowed for revealing that surprising feature, which was then confirmed by transmission electron microscopy (TEM). Coherency for such large second‐phase particles is supported by a very low crystal lattice misfit between the two phases, which was confirmed thanks to X‐ray diffractograms and TEM selected area electron diffraction patterns. Dynamic recrystallization of polycrystalline γ–γ’ nickel‐based superalloys has been extensively studied in terms of mechanisms and kinetics. As in many materials with low stacking fault energy, under forging conditions, the main softening mechanism is discontinuous dynamic recrystallization. This mechanism occurs with preferential nucleation on the grain boundaries of the deformed matrix. The latter is then being consumed by the growth of the newly formed grains of low energy and by nucleation that keeps generating new grains. In the case of sub‐solvus forging, large γ’ particles usually pin the migrating boundaries and thus limit grain growth to a size which is determined by the distribution of second‐phase particles, in good agreement with the Smith–Zener model. Under particular circumstances, the driving force associated with the difference in stored energy between the growing grains and the matrix can be large enough that the pinning forces can be overcome, and some grains can then reach much larger grain sizes. In the latter exceptional case, some intragranular primary γ’ particles can be observed, although they are almost exclusively located on grain boundaries and triple junctions otherwise. In both cases, primary precipitates have no special orientation relationship with the surrounding matrix grain(s). This paper demonstrates the existence of high fractions of large γ’ precipitate (several micrometres in diameter) that are coherent with their surrounding matrix grain, in a commercial γ–γ’ nickel‐based superalloy. Such a configuration is very surprising, because there is apparently no reason for the coherency of such particles.     

Microscopic investigation of pollen morphology of Brassicaceae from Central Punjab‐Pakistan

The intention of the current study is to provide an account on the palynological features of Brassicaceae from Central Punjab‐Pakistan as a basis for future studies. Different morpho‐palynological characteristics both qualitative and quantitative were analyzed during this research which includes shape of pollen, diameter of pollen, P/E ratio, exine sculpturing, thickness of exine, type of pollen, shape and size of lumens, and thickness of murus. Taxonomic keys were also constructed based on pollen morphological characters for correct identification of species. This study aims to provide detailed information of pollen diversity and their exine structure based on both qualitative and quantitative characters by using Light microscopy and Scanning electron microscopy. Shape of pollen is mostly prolate, but some species also have sub‐prolate to spheroidal prolate types. Exine ornamentation in most species was reticulate, whereas micro reticulate (one species) and coarsely reticulate (one species) exine also observed in some pollen. All the pollen mentioned in this study have tricolpate apertures. Variation found in thickness of exine and other characters proved to be helpful at generic and specific level. The results reinforced the significance of pollen morphological features of family Brassicaceae and aid for valuable taxonomic tool in plant systematics.     

Palyno‐morphological characteristics of gymnosperm flora of pakistan and its taxonomic implications with LM and SEM methods

The present study is intended to assess gymnosperms pollen flora of Pakistan using Light Microscope (LM) and Scanning Electron Microscopy (SEM) for its taxonomic significance in identification of gymnosperms. Pollens of 35 gymnosperm species (12 genera and five families) were collected from its various distributional sites of gymnosperms in Pakistan. LM and SEM were used to investigate different palyno‐morphological characteristics. Five pollen types (i.e., Inaperturate, Monolete, Monoporate, Vesiculate‐bisaccate and Polyplicate) were observed. Six In equatorial view seven types of pollens were observed, in which ten species were sub‐angular, nine species were Traingular, six species were Perprolate, three species were Rhomboidal, three species were semi‐angular, two species were rectangular and two species were prolate. While five types of pollen were observed in polar view, in which ten species were Spheroidal, nine species were Angular, eight were Interlobate, six species were Circular, two species were Elliptic. Eighteen species has rugulate and 17 species has faveolate ornamentation. Eighteen species has verrucate and 17 have gemmate type sculpturing. The data was analysed through cluster analysis. The study showed that these palyno‐morphological features have significance value in classification and identification of gymnosperms. Based on these different palyno‐morphological features, a taxonomic key was proposed for the accurate and fast identifications of gymnosperms from Pakistan.     

3D reconstruction of prior β grains in friction stir–processed Ti–6Al–4V

The prior β grain structure and orientations in the central stir zone of friction stir–processed Ti–6Al–4V were reconstructed from measured α phase orientations obtained by three‐dimensional serial sectioning in a dual‐beam focused ion beam scanning electron microscope. The data were processed to obtain the α colony and β grain size distributions in the volume. Several β grains were individually analysed to determine the total number of unique α variants and the respective volume fractions of each. The analysis revealed that some grains experienced overwhelming variant selection (i.e. one variant dominated) whereas other β grains contained a more evenly distributed mixture of all 12 variants.     

蜂花粉多糖生物活性研究进展

蜂花粉含有丰富的营养成分与多种生物活性物质。多糖是蜂花粉的主要活性成分之一。不同来源的蜂花粉多糖具有提高机体免疫力、调节血糖、降血脂、抗氧化、抗肿瘤、抑菌等多种作用,蜂花粉多糖已成为医药与食品行业的重要资源。本文对近几年蜂花粉多糖的上述生物活性研究进展进行综述。     

Microscopic investigation of palyno‐morphological features of melliferous flora of Lakki Marwat district,Khyber Pakhtunkhwa,Pakistan

The present study was carried out to investigate the polliniferous bee flora of Lakki Marwat district, Khyber Pakhtunkhwa, Pakistan. A total of 18 species, belonging to 13 different families were identified for the foraging activities of honeybees, namely, Cenchrus biflorus, Cestrum nocturnum, Citrus limon, Combretum indicum, Datura innoxia, Duranta erecta, Hamelia patens, Helianthus annuus, Ipomoea cairica, Luffa aegyptiaca, Nerium oleander, Ocimum basilicum, Parthenium hysterophorus, Pennisetum typhoides, Prosopis cineraria, Prosopis juliflora, Saccharum spontaneum, and Ziziphus jujuba. The identified melliferous flora was collected for the morpho‐palynological investigation. Pollen were acetolyzed, measured, and described qualitatively using light microscopy. The pollen types varied from psilate to echinate and colpi from tricolpate to hexacolpate. Quantitative characteristics including polar diameter, equatorial diameter, polar to equatorial ratio, colpi length, colpi width, spine length, spine width, and exine thickness of the pollen were determined and analyzed statistically using software IBM SPSS Statistics 20. The results of the present study highlighted the significance of pollen morphology of the bee flora of the area which may lead to the identification of the potential and useful botanical sources for beekeepers and to check the honey quality marketed from the study area.     

Time‐lapse lab‐based x‐ray nano‐CT study of corrosion damage

An experimental protocol (workflow) has been developed for time‐lapse x‐ray nanotomography (nano‐CT) imaging of environmentally driven morphological changes to materials. Two case studies are presented. First, the leaching of nanoparticle corrosion inhibitor pigment from a polymer coating was followed over 14 days, while in the second case the corrosion damage to an AA2099 aluminium alloy was imaged over 12 hours. The protocol includes several novel aspects relevant to nano‐CT with the use of a combination of x‐ray absorption and phase contrast data to provide enhanced morphological and composition information, and hence reveal the best information to provide new insights into the changes of different phases over time. For the pigmented polymer coating containing nominally strontium aluminium polyphosphate, the strontium‐rich components within the materials are observed to leach extensively whereas the aluminium‐rich components are more resistant to dissolution. In the case of AA2099 it is found that the initial grain boundary corrosion is driven by the presence of copper‐rich phases and is then followed by the corrosion of grains of specific orientation.     

Pollen morphology of Aletris L. (Nartheciaceae) and its systematic significance

In this paper, we studied pollen morphologies of seven species in genus Aletris in detail by light microscopy and scanning electron microscopy. Of these, six species were reported for the first time. The palynological characteristics do not support the infrageneric classification into two clades. The results indicated that pollen grains of Aletris are small or medium with the P/E ratio of 0.36–0.59. They are elliptic or long‐elliptic in the polar view with blunt, round or acute ends and bilateral symmetric with a monosulcate, narrow or wide, deep colpus that has length extending to the ends of pollen grains, obvious or absent colpus membranes. The pollen ornamentation is gemmate, perforated, or reticulate. The sexine is slightly or quite thicker than the nexine.     

A new tool for industrial tribology filling the gap between macro‐ and nano‐ tribology

The aim of this paper is to illustrate the similarities and variations between friction and wear data acquired with two different types of laboratory tribological test equipment that not only operate in the gap between macro‐ and nano‐testing, but also provide test parameters that allow an overlap across the whole scale from macro‐ to nanoscale friction and wear tests. Comparative wear tests were conducted under identical test conditions in the overlap region between macro‐ and micro‐regions using an existing piece of laboratory fretting test equipment and a novel one. The experimental test data obtained with these two experimental set‐ups are discussed.     

Three-dimensional EBSD study on the relationship between triple junctions and columnar grains in electrodeposited Co–Ni films

Electrodeposited nanocrystalline materials are expected to have a homogeneous grain size and a narrow grain size distribution. In Co–Ni electrodeposited films, however, under certain conditions an undesired columnar grain structure is formed. Fully automated three‐dimensional (3D) orientation microscopy, consisting of a combination of precise material removal by focussed ion beam and subsequent electron backscatter diffraction (EBSD) analysis, was applied to fully characterize the grain boundaries of these columnar grains in order to gain further understanding on their formation mechanisms. Two‐dimensional orientation microscopy on these films indicated that the development of columnar grains could be related to the formation of low‐energy triple junctions. 3D EBSD allowed us to verify this suggestion and to determine the boundary planes of these triples. The triplets are formed by grain boundaries of different quality, a coherent twin on the {} plane, an incoherent twin and a large‐angle grain boundary. These three boundaries are related to each other by a rotation about the 〈〉 direction. A second particularity of the columnar grains is the occurrence of characteristic orientation gradients created by regular defects in the grain. Transmission electron microscopy was applied to investigate the character of the defects. For this purpose, a sample was prepared with the focussed ion beam from the last slice of the 3D EBSD investigation. From the TEM and 3D EBSD observations, a growth mechanism of the columnar grains is proposed.