Micromorphological Investigations Research Articles

Effect of dentinal surface preparation on the bonding of self-adhesive luting cements

The purpose of the present study was to evaluate the bond strength and the interaction morphology of self-adhesive resin luting cements (SLCs) to dentin prepared with different methods. Four SLCs were used: RelyX U100®, RelyX U200®, Clearfil SA Luting®, and SmartCem2®. A flat dentin surface of 40 human molars was exposed and each tooth was sectioned in four tooth-quarters, which were distributed into four groups according to the SLC used to cement indirect resin composite restorations. The tooth-quarters of each group were then distributed in four subgroups according to the method used for dentin preparation: flat-ended cylindrical fine-grit diamond, flat-ended cylindrical median-grit diamond, flat-ended cylindrical plain-cut tungsten carbide, or abraded with #600-grit SiC paper (control). The restored tooth-quarters were sectioned to obtain beams (0.8 mm2) and submitted to the microtensile bond strength test (n = 10). The results were analyzed using two-way ANOVA/Tukey (α = 0.05). Forty-four additional teeth were used for micromorphological investigation of the SLC/dentin interface and of the topographic aspect of the dentin surfaces after application of the SLCs. Only the bond strength of RelyX U200 was significantly influenced by the surface preparation. No interference was identified on the micromorphological aspect of the bonding interfaces. The topographic investigation of the dentinal surfaces showed that the SLCs were not able to effectively remove the smear layer and etch the underlying dentin, irrespective of the preparation method. So, the interference of the dentin preparation on the bond strength of SLCs is material dependent, but don’t influence the micromorphologic aspect of the interaction zone.

Systematic cultivation of the Swifterbant wetlands (The Netherlands). Evidence from Neolithic tillage marks (c. 4300–4000 cal. BC)

The Middle Neolithic (4300–4000 cal. yr BC) archaeological sites in the Swifterbant area were typically regarded to represent a transitional phase between a hunter-gatherer and agricultural subsistence. The discovery of a tilled layer on one of the sites (S4) site in 2007 during a renewed excavation campaign (2004–2007) was made possible by a close cooperation between archaeologists, diatom specialists and micromorphologists. Intensive sampling and micromorphological investigation revealed that the Swifterbant cultural layers typically consists of micro-laminated deposits of phytoliths and charred plant remains with waste. This led to the reinterpretation of the sites as middens rather than settlements. At least five levels could be identified that had been tilled with some kind of hand-tool. These levels were separated by natural clay deposits and midden layers. These results, and reinterpretation of observations from two other sites in the Swifterbant area (S2 and S3) indicate that tillage and crop production formed a regular part of the subsistence of the inhabitants during the Middle Neolithic. Rather than a transitional phase, the sites investigated probably should be regarded as traces of a fully agricultural society.

Paleoenvironmental Reconstruction from Palaeolake Sediments in the Area of Ouargla (Northern Sahara of Algeria)

The hyper-arid climate of Ouargla area (Northern Sahara of Algeria) is important in the field of the paleoenvironmental reconstitution. This paper investigates the importance of palaeolake sediments as significant terrestrial archives for studying Quaternary climate changes. Through morphological and mainly micromorphological investigations of the studied sites (Sabkha of Ouargla and palaeolake of Mellala), we noted the fluctuation of climate between arid and more humid conditions during Quaternary. Some pedofeatures have recorded these environmental changes. The studied calcareous crusting has a lacustrine origin when precipitations were more important. The clay coatings around the quartz grains indicate an old origin and different geochemical conditions that led to their dissolution. Lenticular gypsum crystals were formed from groundwater saturated with Ca2+ and ions. Calcite pseudomorphs after lenticular gypsum crystals indicate changes in local climatic parameters. Gypsum crusts can be explained by formation under wet climatic conditions in a lagoonal environment. Black and gray layers indicate evolution of organic matter at a wetter period. This paper highlights an unknown palaeolake which can be useful for the comprehension of the ecological past of the Sahara. The comparison between this palaeolake and other Saharan palaeolakes has allowed us to assign it to a probable active period between 10000 and 4000 years B.P.

Micromorphological investigations on two paleosol horizons of the loess/paleosol sequence of Madaras, Hungary

The loess/paleosol sequence near the village of Madaras is an outstanding record of Late Quaternary paleoenvironmental and paleoclimatic changes in Hungary and the entire Carpathian Basin. The present study highlights the results of preliminary micromorphological investigations implemented on 24 samples taken from two pre-selected pedogenized horizons of the sequence. Our work yielded interesting results regarding the evolutionary history and modes of pedogenesis in the studied section.

Manufacturing technical differences employing raw earth at the protohistoric site of Sant Jaume (Alcanar, Tarragona, Spain): Construction and furniture elements

This paper presents the results of an ongoing micromorphological investigation that aims at identifying the use of raw earth during the protohistoric period in the NE region of the Iberian Peninsula at the Early Iron Age site of Sant Jaume (Alcanar, Tarragona, Spain). The current manufactured raw earth elements (mainly composed of sun-dried mixed clays, sands, gravels and vegetal components) have been analyzed. This preliminary research has been integrated into a typological classification that could improve understanding of the manufacturing methods, use and postdepositional processes that might have taken place in Sant Jaume. The emerging patterns suggest that two different techniques were used in manufacture: 1) furniture elements (e.g. boxes and containers) and 2) construction elements (those inherent to the structure of the building: e.g. ceilings, shelves).

Aperture evolution in Nymphaeaceae: insights from a micromorphological and ultrastructural investigation

The evolution of the apertural type in the ANITA-grade family Nymphaeaceae, despite the importance of pollen characters for both palaeobotanical and neobotanical investigations, has not been yet totally understood. To elucidate some unclear aspects regarding the homologies of the apertural condition in basal and core Nymphaeaceae, we examined the pollen grains from five species of this family. We offer for the first time some evidence about the presence of a proper operculum in the pollen grain of Nuphar and for the ring-like status of the aperture of Nymphaea caerulea and Victoria cruziana. Our findings clarify and reinforce the hypothesis of an opercular origin of the distal part of the pollen grain in the core Nymphaeaceae and support the paraphyly of the genus Nymphaea as emerged from recent molecular studies. The diversity and specialisation of this ‘basal’ family is underlined even by its pollen characters.

A comparison of residual smear layer and erosion following different endodontic irrigation protocols tested under clinical and laboratory conditions

Objective. To compare the smear layer removal efficacy and erosive effects of different irrigation protocols under clinical and laboratory conditions. Materials and methods. Mandibular third molars (n = 32) of 30–45 year-old patients were instrumented with rotary files and were randomly assigned to one of the following groups for final irrigation: (1) 5.25% NaOCl; (2) 17% EDTA; and (3) BioPure MTAD. Thereafter, the teeth were immediately extracted and processed for micromorphological investigation. In vitro specimen pairs were prepared by repeating the clinical experiments on freshly-extracted mandibular third molars. To compare open and closed systems, laboratory experiments were repeated on 32 additional teeth with enlarged apical foramen. The cleanliness of the root canals and the extent of erosion were assessed by environmental scanning electron microscopy. Results. Specimens prepared under clinical and laboratory conditions had similar cleanliness and erosion scores (p > 0.05). Under both conditions, the tested solutions were more effective in removing the smear layer in the coronal and middle regions than in the apical one. Comparison of closed and open systems showed similar levels of cleanliness and erosion in all regions (p > 0.05), with the exception of 17% EDTA showing significantly higher levels of cleanliness and erosion in the apical third of open-end specimens. Conclusions. Based on clinical correlates of in vitro root canal cleanliness and erosion, laboratory testing of root canal irrigants on extracted teeth with closed apices can serve as a reliable method to simulate the clinical condition. EDTA was the most effective final irrigation solution in removing the smear layer at the expense of yielding the greatest erosive effect.

Malus ×oxysepala (M. domestica Borkh. × M. sylvestris Mill.) – a new spontaneous apple hybrid

<p>A study of the three <em>Malus</em> species (<em>M. domestica</em>, <em>M. sylvestris</em>, and a hybrid species, <em>M. domestica</em> × <em>M. sylvestris</em>, which was named <em>M.</em> ×<em>oxysepala</em>) was carried out based on the morphological and micromorphological features and molecular investigation. Observations performed for 47 quantitative traits showed that this hybrid species exhibits intermediate values between <em>M. domestica</em> and <em>M. sylvestris</em>, or are similar to traits of one of the parents. Sepals proved to be the best diagnostic feature because they were acuminate and much longer than sepals in <em>M. domestica</em> and <em>M. sylvestris</em>. Seed testa cells are distinct, rimmed with straight anticlinal walls and strongly bulged periclinal walls. Simultaneous genetic analyses based on PCR RAPD reactions fully confirmed earlier morphological observations. Genetic profiles of the hybrid obtained with the use of 30 primers, next to species-specific amplification products, contain common products with each of the parents. However, both the profile analysis and the dendrogram constructed on its basis showed that the hybrid is genetically closer to <em>M. sylvestris</em>.</p>

Micromorphological and microchemical indicators of pedogenesis in Ornithogenic Cryosols (Gelisols) of Hope Bay, Antarctic Peninsula

Micromorphological investigations of Antarctic soils are comparatively scarce, however, they could help understand the genesis of cryogenic soils under extreme polar conditions and different biotic factors. In most areas of Maritime Antarctica, the soil structure is apparently influenced by the local lithology, cryoturbation, guano deposition and reaction of guano solutions. The present study was carried out in Hope Bay, in the northern part of the Antarctic Peninsula, possibly one of the oldest sites of penguin occupation in the region. We describe and analyze the most important micro and sub-microscopic features of selected Ornithogenic Cryosols (Gelisols) from this part of Antarctic Peninsula, representing a transitional climatic zone between the wetter South Shetlands and the much drier Weddell Sea sector. Nine pedons representing the main ornithogenic soils found in ice-free areas of Hope Bay were selected for the micromorphological study. Undisturbed soil blocks were sampled at different depths, ranging between 0 and 30cm. The microstructure and sub-microstructure were further investigated using a JEOL 8200 and a Zeiss scanning electron microscopes, both coupled with an microprobe (SEM/WDS). These pedons have a very limited surface accumulation of organic matter formed by mosses and lichens, changing abruptly to a mineral phosphatic horizon of bleached colours, and usually hardcemented by ice. A small to medium-sized granular structure is generally observed, with ovoidal, subrounded forms, including several well-defined ornithogenic materials, such as P-rich organic remains, nodular phosphates forms and minute fragments of bone apatite. The chemical composition of ornithogenic materials and phosphatic coatings indicates the presence of discrete forms of taranakite, minyulite, leucophosphite, struvite and fluorapatite, typical of phosphatization process in these soils. Phosphatization and enhanced chemical alteration of the substrate and is one of the main soil-forming process in ornithogenic soils, resulting in P-rich ovoidal aggregates formation. P-rich solutions penetrate desiccation fractures and cleavage planes in large clasts and react preferably with plagioclases. P reacts with Al and Fe to form various amorphous and crystalline P phases. Present day permafrost cementation of deeper phosphate layers indicate that warmer/wetter conditions occurred in the past, during which P was leached downwards and reacted with the rock substrates, developing stable ovoidal aggregates, now incorporated in ice-cemented subsurface horizon.

Assessing geochemical indicators of weathering and sorting in last interglacial palaeosols in the Chinese Loess Plateau and its implications for palaeoclimatic reconstruction

Based on a W–E transect through the northern loess regions of Austria, palaeoenvironmental studies were carried out in three loess–palaeosol sequences (Gunderding, Krems-Wachtberg and Stillfried B locus typicus) to complement available results in the context of a multi-methodological approach. On the base of previously published datings, our study concentrates on the MIS 3/2 transition. The results of detailed micromorphological investigations prove that palaeopedogenesis, frost processes, and sedimentation rates differ in their spatial occurrence in the loess belt of Austria. All three sequences are in line with the general trend of a reduced intensity of pedogenic and cryogenic features from western to (south-)eastern Europe, which can be explained by lower Atlantic moisture influence towards the east. Interstadial cambic horizons are well developed in the MIS 3 sequence of western Austria, whereas the eastern loess profiles only show weak pedogenesis. In all studied sequences frost processes were active during the upper MIS 3 and MIS 2. The studied MIS 2 records are characterised by tundra soils with reductaquic horizons, which is a clear sign for prolonged phases of permafrost. On the spatial scale, the sedimentation rate increases in the eastern loess regions and particularly the Krems-Wachtberg sequence in the centre of the transect experienced an exceptionally high sedimentation rate and can thus be seen as one of the most important high resolution records for the MIS 3/2 transition in European loess regions.

Biological Soil Crusts in the Mojave Desert, USA: Micromorphology and Pedogenesis

Biological soil crusts (BSCs) are bio-sedimentary complexes that play critical ecological roles in arid landscapes; however, the interactions between component biota and sediments are poorly understood. A detailed micromorphological investigation of BSC development and crust microstructure in the Muddy Mountains Wilderness Area, Nevada, examined features in thin section using petrographic microscopy, light microscopy, scanning electron microscopy, and energy dispersive x-ray spectroscopy. The >1800 microscopic observations were linked to crust macroscale features and soil geomorphology. Complex bio-sedimentary structures of BSCs reflect a dynamic genetic history and diverse formative processes, including: (i) stabilization and authigenic mineral precipitation; (ii) wetting–drying and expansion–contraction; (iii) dust capture; (iv) microscale mass wasting; and (v) vesicular (Av) horizon formation. A new conceptual model for hot deserts illustrates how these processes co-develop with BSC succession, during countless wet–dry cycles, to build up pinnacle microtopography while simultaneously forming Av horizons in the bio-rich and bio-poor zones. Complex surficial and internal bio-sedimentary structures, which vary as a function of crust morphology, trap surface water for uptake by crust organisms, while dust influx provides a source of nutrients. These phenomena influence landscape-scale water dynamics and biogeochemical cycling, increasing the availability of soil resources during times of biotic stress. Biological soil crusts uniquely facilitate the accumulation, morphology, and ecosystem function of dust and should, therefore, be considered critical agents in arid pedogenesis and landscape development.

Micro-morphology of Achillea clypeolata: contribution to the pharmacognostical profile

Achillea clypeolata Sibth. & Sm. is Balkan endemic species, commonly known as yellow yarrow and traditionally used in Bulgarian folk medicine. The purpose of this study was to establish pharmacognostical profile of A. clypeolata, including macroscopic and microscopic morphological characteristics. The study also aims to propose a method for micromorphological investigation and pharmacognostical identification. As a result were established morphological characters necessary for identification of Achilleae clypeolatae flos and Achilleae clypeolatae herba – morphology of stem leaves (lanceolate in shape, pinnately lobed-margin, acute-apex with lamina), ligule petals (2.7-3 mm), involucre bracts (4.5x2 mm) and achenes (1.5-1.7 mm); micromorphology of lamina (110-130 µm), epidermal cells, stomata, glandular, non-glandular trichomes and 3-colporate, echinate pollen grains (20.5-20.8 µm). This study presents new micromorphological data. The used staining method dyed various tissues; makes visible the outlines of structures, tissues and some inclusions; allows by one procedure to visualize important diagnostic features; unlike many other methods, allowing pollen to be used as a characteristic of herbal substances. The results are useful for quality control methods for medicinal plant materials and contributes to the implementation of good practices for plant identification for the herbal industry, food, nutrient supplements and other plant based products.

Micromorphological investigation of pedogenic barite in Mormon Mesa petrocalcic horizons, Nevada USA: Implication for genesis

Barite crystals are identified in stage VI petrocalcic horizons at Mormon Mesa, Nevada. Their presence is significant because barite is not typically associated with arid soil processes. Barite is identified through backscatter SEM/EDS as bright white crystals with EDS peaks of high Ba, S, and O. Barite crystals are euhedral, tabular to acicular crystals ranging in size from 1 to 50μm in length and 1–20μm in diameter, and as small (2–4μm) tabular-ovoid crystals. Forty-one percent of the barite in SEM images is associated with fibers of palygorskite and/or sepiolite. Barite crystals are also associated with linear voids, circular pores, and within micropores between fibers of silicate clays. The formation of barite at Mormon Mesa is attributed to: (i) The dissolution of Ba and SO4 ions from detrital minerals and dust that are flushed into the soil profile and precipitate as barite; and/or (ii) Biomineralization of barite in micro-environments suitable for bacteria or other organisms within the petrocalcic horizon.

An experimental micromorphological investigation of bedding construction in the Middle Stone Age of Sibudu, South Africa

We conducted experiments to compare the micromorphological signatures of modern burnt sedge and grass bedding to laminated layers of carbonized material and phytoliths in Middle Stone Age deposits at the shelter, Sibudu. The experiments were designed to clarify the formation processes associated with the laminated layers and to investigate whether these previously identified layers of bedding were deliberately burned or not. The results indicate that the laminated layers were most likely produced by human activity related to the construction, maintenance and burning of bedding. Furthermore, our experiments demonstrate that large volumes of vegetal material could have produced the relatively thin, archaeological deposits of burnt bedding.

Microscopic investigation of trichomes of wild-growing Satureja montana L.

Considering the importance of S. montana L. as a medicinal plant, due to the essential oils produced in its glandular trichomes, and the lack of data about the leaf ultrastructure and micromorphology, we have carried out a comprehensive study of trichomes distributed in the vegetative and reproductive organs. Micromorphological and ultrastructural investigations of the glandular trichomes of Satureja montana L. and autofluorescence analyses of their secreted products were carried out using scanning electron microscopy (SEM), transmission electron microscopy (TEM), confocal laser scanning electron microscopy (CLSM) and light fluorescence microscope. The leaves, stem and calyx bear numerous nonglandular, unbranched trichomes and two types of glandular trichomes - peltate and capitate. Ultrastructural analyses showed the presence of mitochondria, plastids and proliferations of the granular endoplasmatic reticulum in secretory phases of the heads of glandular trichomes. Strong red autofluorescence of the lipophilic and hydrophilic secreted material was observed with CLSM. Green-yellow autofluorescence of secreted material were noticed in peltate and capitate trichomes observed with a fluorescence microscope.

Structure of the floral parts of Crocus vernus (L.) Hill.

In the climatic conditions of Lublin, <i>Crocus vernus</i> blooms from the third decade of March until the third decade of April. The flowers live for 3-4 days. Micromorphological investigations of the tepals and perianth tube as well as of the stamens and pistil were carried out using scanning electron microscopy. The anatomical features of the perianth segments and flower stem were examined with the use of light and fluorescence microscopy. Pollen grains were observed under a light microscope. It was found that the adaxial and abaxial epidermal cells formed papillae in the middle and lower part of the tepals. Much smaller papillae are formed in the upper region of the perianth tube. Elongated non-glandular and glandular trichomes, with spherical protrusions at the tip, are found at the base of the filaments. The filaments are distinguished by epidermal cells with a longitudinally striated cuticle and by the presence of papillae of varying number and size. The cylindrical papillae on the stigma of the pistil are covered by a wrinkled cuticle. The style is surrounded by the perianth tube along a significant length. A narrow space is formed between these organs, and it is filled by the nectar. Stylar channels are found in the style. We observed calcium oxalate crystals and numerous plastids in the parenchymal cells surrounding these channels. Inaperturate, spherical pollen grains are covered by numerous tryphine (or pollenkitt) droplets. This paper also discusses the functions of the papillae found in the epidermis of the perianth and filaments.

Livestock and people in a Middle Chalcolithic settlement: a micromorphological investigation from Tel Tsaf, Israel

Round and rectangular buildings with grain silos at a Copper Age site in Israel suggested social stratification to the excavators. Using micromorphology, the author demonstrates that while the rectangular building was occupied by people, the round ones had contained animals, perhaps as providers of milk, and dung for fuel. While this removes the direct indication of social variance, it strengthens the argument that animals, as well as grain, formed the basis for the creation of surplus.

Red soils developed from Quaternary deposits on the Linkuo terrace, northern Taiwan

AbstractThe Linkuo terrace, situated to the west of the Taipei Basin in NW Taiwan, has thick red soils that have been little studied. This paper aims to interpret the development of these soils through chemical and micromorphological investigations, and relate the soils to their palaeo-environments. The soil samples were air dried, crushed and passed through a 2 mm sieve, and then subjected to conventional soil chemical and physical analyses, together with clay mineralogical and morphological characterization. Pedons I and II were clay with low base saturation (BS), cation-exchange capacity (CEC), and exchangeable cations. The pH of pedons I and II ranged from 3.80 to 5.26. The low magnetic susceptibility of these soils indicates that no magnetite (Fe3O4) or maghemite (γ-Fe2O3) are present. X-ray diffraction patterns of the magnetic clay fraction showed lepidocrocite, goethite and hematite, the amounts of which may relate to water fluctuation in the soil environments. Illite, kaolinite and quartz are major clay minerals in the red soil clay fractions. The micromorphology of all horizons showed a great accumulation of Fe-oxides. The upper horizon showed darkened isotropic Fe-oxide materials, and lower horizon showed a black to reddish dense plasma with soil matrix. The groundmass of the oxic horizon is generally characterized by a homogeneous distribution of the different coarse and fine constituents. The thick (4 m depth) and homogeneous red soils of the Linkuo terrace were developed from fine sediments after the gradual subsidence of the Taipei Basin. Alarge amount of gravel was flushed from the Xindian River before the Taipei Basin subsided. The Linkuo red soils can be classified as mesic, Typic Kandiudox. From the chemical compositions of clay fractions and the red soil features, these red soils can be considered as lateritic red earths or red earths that do not reach the criteria for laterite.

Micromorphology of an Early Holocene Loess-Paleosol Sequence, Central Alaska, U.S.A

This paper describes a micromorphological investigation of an early Holocene loess-paleosol sequence at the Chena Hot Springs Road site, a highway road cut exposure near Fairbanks, Alaska, U.S.A. The procedure identified and described soil microstructure, basic mineral components and their related distributions, organic inclusions, and pedogenic features. Micromorphology confirmed the presence of a number of thin, discontinuous, weakly expressed soils that evince disturbance by diagenetic, graviturbative, and cryoturbative processes. Well-preserved organic remains indicate the presence of a boreal forest that would have acted as a highly effective sediment trap. The frequent observation of detrital iron-oxide grains is consistent with other studies of area loess that reveal high concentrations of magnetite and ilmenite, resulting in significant increases in magnetic susceptibility. Increases in wind strength are likely responsible for the increased clay content in the buried paleosols. Loess deposition, which would inhibit pedogenesis, is probably related to greater wind strength, while pedogenesis, indicative of stability and minimal deposition, suggests periods of reduced wind.

Role of deforestation and hillslope position on soil quality attributes of loess-derived soils in Golestan province, Iran

Conversion of natural land resources into croplands, which is triggered by the rapid population growth, causes serious soil degradation. A loess hillslope located in eastern Golestan province of Iran was selected to study the role of deforestation and slope position on soil quality attributes. Surface (0–30 cm) and subsurface (30–60 cm) soil samples were taken from five slope positions (summit, SU, shoulder, SH, backslope, BS, footslope, FS and toeslope, TS) of forest (FO) and adjacent deforested cultivated land (DEF) in a factorial trial with completely randomized design. Ten pedons were also investigated and undisturbed soil samples were taken from different horizons for micromorphological studies. The texture of the original loess is silt loam. The soil textural class varies from silty clay loam in FO to silt loam in DEF, mainly due to the loss of finer particles as a result of soil erosion followed by deforestation and long-term cultivation. Mean weight diameter (MWD) of aggregates decreased following deforestation (0.88 mm compared to 1.49 mm in FO), as a result of considerable losses of organic carbon (OC) and breakdown of aggregates. Bulk density (BD) increased and soil infiltration rate decreased by about 50% in DEF. Reduction of annual organic matter input to soil as a result of deforestation and also rapid oxidation of organic matter in DEF were responsible for a significant decrease (>70%) in OC and total nitrogen (TN). Soil microbial respiration (SMR) also decreased significantly, following deforestation. Carbon, and N contents and population of fungi were significantly higher in all hillslope positions of the FO than the DEF. Changes in soil quality attributes were not significant in different slope positions of FO, which might be related to the stability of forest landscape. Effect of different slope positions on soil quality attributes was more pronounced in the DEF. The SH and BS were found as the most susceptible positions to erosion in DEF. Soils of the FO were mainly classified as Alfisols and Mollisols with evidences for clay illuviation compared to the weakly developed Inceptisols formed in the DEF. Micromorphological investigations revealed that the FO soils had strong granular and crumb microstructure with a high porosity indicating the presence of high amount of organic matter. The high microbial and faunal activity was confirmed through the presence of excremental pedofeatures in the topsoil of the FO. Lower organic matter and consequently microbial activity in the topsoil of the DEF have resulted in the massive microstructure with little porosity.