Small Hollows Research Articles

Three-Dimensional Simulations of Strong Ground Motion in the Shidian Basin

Seismic response of the Shidian basin to moderate scenario earthquake is investigated considering 3D basin model incorporated with real topography by using the spectral-element method and parallel computing technique. The wave propagation process, the generation of surface wave, and the impact of soil deposits velocity to the basin-induced surface wave are studied in this paper. The results show that the amplification behavior of the basin is the interactions of basin geometry and low velocity soil deposits. First, locally small hollows in the basin are apt to trap seismic waves and produce much stronger ground motion, basin edge and areas with deep sediments are also characterized with large amplification. Then, basin with softer soil deposits produces stronger surface waves with lower propagation velocity and higher mode.

Experimental Investigation of the Shrinkage Performance of Small Blocks Made by Rock Chips Concrete

A new type of small concrete blocks with high strength performance was generated in this study, and the main component of this kind of small blocks were made by the MU15.0 that was extracted from the waste rock chips. The effect of content of stone powder and the different curing methods on the shrinkage of the proposed concrete blocks, was investigated by using the experimental method. The results showed that (i) with the increase of the amount of stone power, the drying shrinkage of rock chips concrete went up at first, and then the opposite change was generated; (ii) The small hollow blocks made by the rock chips concrete after steam curing kiln, under the condition of enough water curing and seal environment, had higher compressive strength and smaller shrinkage comparing with other curing methods.

Small hollows in the Baikal Rift Zone

Large grabens, or rift valleys, are of the utmost significance in the neotectonic structure of the Baikal Rift Zone. It is also the home for numerous small hollows which are distinguished by their morphological diversity, structural positions and special features of neogeodynamics. The distribution and types of small hollows are considered, and their structural-morphological classification is suggested.

Holocene fire frequency variability in Vesijako, Strict Nature Reserve, Finland, and its application to conservation and management

Fire disturbance is considered paramount for regeneration and biodiversity in the boreal forest with prescribed burning widely advocated in present day forest management. Palaeoecological knowledge is beneficial in understanding the role of fire as a driver of past vegetation dynamics. We use a sedimentary pollen and charcoal record to reconstruct 5000years of fire and vegetation history from a small forest hollow (approximate area 12m2) in the Vesijako Strict Nature Reserve, currently one of the few remaining old-growth forest stands in southern Finland. Results indicate three distinct periods in the environmental history (1) 5000–2000cal. yrs. BP; semi-natural low frequency (430year return period), low intensity fires in a diverse mixed stand with little evidence of anthropogenic disturbance and an expanding Picea abies (Norway spruce) population (2) 2000–750cal. yrs. BP; anthropogenic-driven high frequency (180year return period), high intensity stand-replacing fires in a low diversity stand with evidence of slash and burn cultivation and a decline of Picea population, (3) 750cal. yrs. BP to present day; fire absence through a reduction in human-induced fire or active fire suppression and the expansion of the currently dominant Picea forest. The changing fire frequency has had a major influence on the forest composition during the last 5000years. The loss of floristic diversity is associated with an increase in the human use of fire and without this human interference the previously high biodiversity in the stand may have remained up until the present day. If fire remains absent in Vesijako then it is likely that the Picea population will continue to dominate in the stand supporting a negative feedback mechanism that will result in lower frequency, higher intensity fires in the future.

Electrospun activated carbon nanofibers with hollow core/highly mesoporous shell structure as counter electrodes for dye-sensitized solar cells

Activated carbon nanofibers with hollow core/highly mesoporous shell structure (Meso-HACNF) are prepared by concentric electrospinning using poly(methyl methacrylate) (PMMA) as a pyrolytic core precursor with either polyacrylonitrile (PAN) or PAN/PMMA blended polymer as a carbon shell precursor, subsequently proceeded to the process of stabilization, carbonization, and activation. Meso-HACNFs with two different PMMA concentrations, 10 wt.% and 20 wt.%, are composed of a highly mesoporous shell and hollow core while HACNF without PMMA is composed of a relatively small mesoporous shell and hollow core. Highly mesoporous Meso-HACNF1 has a large surface area of 1191 m2 g−1 with a mesoporous surface area of 151 m2 g−1. Meso-HACNF1 with 10 wt.% PMMA has a high efficiency of 7.21%, and is comparable to Pt CE because of its novel characteristics, which promote the electron and ion transfer, decrease the resistance of charge transfer, and increase the contact area between liquid electrolyte and Meso-HACNF1.

A revision of the genus Notothylas (Notothyladaceae, Anthocerotophyta) in China

The genus Notothylas in China contains four species. One new species, Notothylas yunnanensis, is described and illustrated. The new species is characterized by each proximal spore surface with a small central hollow, irregularly arranged, rectangular to quadrate epidermal cells of the capsule, and absence of a special dehiscence line in the capsule. A key to the species of Notothylas in China is provided.

Anatomy of the floral nectaries of 9 species from subf. Pomoideae (Rosaceae)

The nectaries anatomical features of nine species of <em>Pomoideae</em> subfamily <em>Aronia melanocarpa</em> Ell., <em>Cotoneaster horizontalis</em> Decne, <em>C. praecox</em> Vilm.-Andr., <em>C. lucida</em> Schlecht., <em>Crataegus monogyna</em> Jacq., <em>C. coccinea</em> L., <em>C. crus-galli</em> L., <em>Sorbus aucuparia</em> L., <em>Sorbus intermedia</em> Pers. were compared. The flower longitudinal sections by means of vibratome and semithin slides by use of ultramicrotome were made. The thickness of nectary epidermis, glandular layer and the structure of subglandular layer as well as the n,n of vascular bundles were studied. It was stated that the height of epidermis cells and the thickness of their wall were approximate in the most investigated taxons. Stomata occurred in the nectaries of all species. They were located on a level with the epidermis cells in <em>Aronia</em> and <em>Sorbus</em> genera, in small hollows in Cotoneaster and considerably below the level of epidermis cells in <em>Crataegus</em>. The thickness of glandular layer was approximate for each genera. Sorbus intermedia and the species of <em>Crataegus</em> genus wer distinguishable by the thickest nectaries. The concentration of brachysclereids occurred in subglandular tissue of <em>Crataegus crus-galli</em> and of <em>Sorbus</em> both species. Vascular bundles, stocking the nectary, mostly consisted of phloem and xylem, but in <em>Aronia, Cotoneaster praecox</em> and <em>C. lucida</em> only phloem was noticed. The dependence between thickness of glandular layer, studied anatomical features and the volume of secreted nectar is discussed.

Quantitative vegetation reconstruction from pollen analysis and historical inventory data around a Danish small forest hollow

AbstractQuestionsCan the model performance of the landscape reconstruction algorithm (LRA) for small forest hollows be validated through comparison to inventory‐based vegetation reconstructions from the last 150 yrs? Does the application of LRA and the comparison to historical data enhance interpretation of the pollen record?LocationDenmark. The Gribskov‐Ostrup small forest hollow (56°N, 12°20′ E, 44 m a.s.l.) in the forest of Gribskov, eastern Denmark.MethodsPollen analysis was carried out on a small forest hollow, and LRA used to derive pollen‐based quantitative estimates of past vegetation. Historical forest inventory data and maps were used to reconstruct the vegetation within three different circles around the hollow (20, 50 and 200 m ring widths) for five time periods during the last 150 yrs. The results of the two approaches were compared in order to evaluate model performance, and the LRA‐based reconstruction used to describe how the model changes interpretation of vegetation development during the last ca. 6500 yrs compared to the use of pollen percentages alone.ResultsDistance‐weighted inventory‐based reconstructions within 200 m of the hollow's edge provide the best match with the LRA‐modelled vegetation. Precise validation of the model is not possible due to insufficient historical data, but the comparison indicates that the LRA reconstruction for Gribskov tends to (1) underestimate tree cover and overestimate open areas, (2) give a too high representation of on‐site pollen types, (3) give an underestimation of Fagus and (4) a small overestimation of Quercus and Corylus. Despite these uncertainties, application of the LRA model shows a higher degree of openness than would be apparent from the uncorrected pollen diagram, and makes it possible to attempt to distinguish changes at the local scale from regional vegetation changes, thus giving a clearer picture of the vegetation changes at the site.ConclusionsWe demonstrate that the estimates of the LRA model applied to pollen data from small forest hollows can be compared with small‐scale historical data to evaluate model performance.

The Holocene boreal forest dynamics in the western range limit of the Siberian Larch (Larix sibirica): evidence from stomata, pollen and charcoal records from small hollows

The development of research into the history of tree growth and inferred summer temperature changes in Yamalia spanning the last 2000 years is reviewed. One focus is the evolving production of tree-ring width (TRW) and tree-ring maximum-latewood density (MXD) larch (Larix sibirica) chronologies, incorporating different applications of Regional Curve Standardisation (RCS). Another focus is the comparison of independent data representing past tree growth in adjacent Yamalia areas: Yamal and Polar Urals, and the examination of the evidence for common growth behaviour at different timescales. The sample data we use are far more numerous and cover a longer time-span at Yamal compared to the Polar Urals, but Yamal has only TRW, while there are both TRW and MXD for the Polar Urals. We use more data (sub-fossil and from living trees) than in previous dendroclimatic studies in this region. We develop a new TRW chronology for Yamal, more than 2000 years long and running up to 2005. For the Polar Urals we develop new TRW and MXD chronologies that show good agreement at short (<15 years) and medium (15–100 years) timescales demonstrating the validity of attempts to reconcile the evidence of longer-timescale information that they provide. We use a “conservative” application of the RCS approach (two-curve signal-free RCS), guarding against the possibility of “modern sample bias”: a possible inflation of recent chronology values arising out of inadvertent selection of mostly relatively fast-growing trees in recent centuries. We also transform tree indices to have a normal distribution to remove the positive chronology skew often apparent in RCS TRW chronologies. This also reduces the apparent magnitude of 20th century tree-growth levels.There is generally good agreement between all chronologies as regards the major features of the decadal to centennial variability. Low tree-growth periods for which the inferred summer temperatures are approximately 2.5 °C below the 1961–90 reference are apparent in the 15-year smoothed reconstructions, centred around 1005, 1300, 1455, 1530, particularly the 1810s where the inferred cooling reaches −4 °C or even −6 °C for individual years, and the 1880s. These are superimposed on generally cool pre-20th century conditions: the long-term means of the pre-1900 reconstructed temperature anomalies range from −0.6 to −0.9 °C in our alternative reconstructions. There are numerous periods of one or two decades with relatively high growth (and inferred summer temperatures close to the 1961–1990 level) but at longer timescales only the 40-year period centred at 250 CE appears comparable with 20th century warmth. Although the central temperature estimate for this period is below that for the recent period, when we take into account the uncertainties we cannot be highly confident that recent warmth has exceeded the temperature of this earlier warm period. While there are clear warm decades either side of 1000 CE, neither TRW nor MXD data support the conclusion that temperatures were exceptionally high during medieval times. One previous version of the Polar Urals TRW chronology is shown here to be in error due to an injudicious application of RCS to non-homogeneous sample data, partly derived from root-collar samples that produce spuriously high chronology values in the 11th and 15th centuries. This biased chronology has been used in a number of recent studies aimed at reconstructing wider scale temperature histories. All of the chronologies we have produced here clearly show a generally high level of growth throughout their most recent 80 years. Allowing for chronology and reconstruction uncertainty, the mean of the last 100 years of the reconstruction is likely warmer than any century in the last 2000 years in this region.

Lystrup Østergård – En værkstedsplads fra yngre stenalder

Lystrup Østergård – En værkstedsplads fra yngre stenalder

Modern pollen studies from coppiced woodlands and their implications for the detection of woodland management in Holocene pollen records

Investigations of pollen production, modern pollen–vegetation relationships and pollen‐stratigraphic changes have been undertaken from three woodlands under coppice management to establish the impact that woodland management techniques (the periodic cutting of broadleaved trees and shrubs for wood and fodder) have on pollen representation. The number of inflorescences (catkins/flowers) produced over the length of a coppice rotation has been quantified for three species; Corylus avellana, Alnus glutinosa and Tilia cordata. For C. avellana the number inflorescences produced is significantly higher in the early years after coppicing. For A. glutinosa and particularly T. cordata flowering is suppressed after coppicing and only recovers slowly. In the later years the number of inflorescences produced by all three species is related to the height of the regrowths and therefore competition for light. However, the number of pollen grains produced per inflorescence appears not to be related to age in the coppice rotation. The modern pollen rain within the coppiced woodlands largely reflects differences in the vegetation of the coppiced areas rather than variations resulting from their age in the coppice rotation. High resolution pollen-stratigraphic records from small ponds record long-term vegetation trends, while the coppicing of adjacent areas is difficult to detect. Nevertheless, the results from these studies are broadly consistent with the pollen production investigations and together show that coppicing results in a shift in pollen production from canopy to under-storey species and may render some taxa (notably T. cordata) palynologically invisible. Model simulations, with corrections for differences in pollen production through the coppice rotation, have been produced for three types of basin; small ponds/hollows, small lakes and wet woodlands with A. glutinosa. These explore the impact of changes in the intensity and scale of coppicing on pollen assemblages from mixed deciduous woodland. The simulated assemblages are compared with mid–late Holocene pollen records from temperate regions of north-west Europe where archaeological/historical evidence suggests that woodland management is likely to have been practiced. Some changes in the representation of trees and shrubs recorded in pollen diagrams from small hollows within wooded landscapes in southern Scandinavia and from A. glutinosa woodland in southern England are consistent with woodlands being managed. Notably pollen diagrams from the northern Alpine Forelands and East Anglia are compatible with long-standing ideas that woodland was managed on a landscape scale during the Neolithic. Further studies are required to determine whether a number of related woodland management practices produce distinct pollen signatures and the impact of these processes on a wider range of species.

Long-term forest dynamics at Gribskov, eastern Denmark with early-Holocene evidence for thermophilous broadleaved tree species

We report on a full-Holocene pollen, charcoal and macrofossil record from a small forest hollow in Gribskov, eastern Denmark. The Fagus sylvatica pollen record suggests the establishment of a small Fagus population at Gribskov in the early Holocene together with early establishment of other thermophilous broadleaved trees, including Quercus sp., Tilia sp. and Ulmus sp. The macrofossils contribute to the vegetation reconstruction with evidence for local presence of species with low pollen productivity or easily degraded pollen types such as Populus. The charcoal record shows frequent burning during two periods of the early Holocene and from c. 3000 cal. BP to present. The early-Holocene part of the record indicates a highly disturbed forest ecosystem with frequent fires and abundant macrofossils of particularly Betula sp. and Populus sp. The sediment stratigraphy and age–depth relationships give no clear indication of post-depositional disturbance, although a possible short-lived hiatus occurs around 6500 cal. BP. The early pollen record from thermophilous trees could indicate that there may have been some downwash following sediment desiccation through wood peat layers deposited between c. 6500 and 10,000 cal. BP, but the overall biostratigraphy is consistent with other Danish small hollow records.

The Fagus sylvatica forests in the Larvik region, south-eastern Norway: their origin and history

The origin and developmental history of Fagus sylvatica forests in south-eastern Norway have been studied through pollen analysis and AMS radiocarbon-dating of peat from two small forest hollows. In this area F. sylvatica appears to have a long history, from the first occurrence of F. sylvatica pollen at ca. 9100 cal. b.p. to its local expansion ca. 1300–1200 cal. b.p. At this time a shift from a diverse landscape mosaic with many plant taxa present, including broad-leaved trees, to a less diverse landscape mosaic with Picea abies and F. sylvatica trees is interpreted from the pollen data. The long history of F. sylvatica suggests that the existing forests are not recent plantations, but implies that these forests are native. The presence of pollen indicative of anthropogenic activity combined with charcoal before the expansion of F. sylvatica, as well as comparison with data from nearby sites, suggest that the forest development was likely to be a result of human activity and climatic changes, particularly changes in moisture conditions.

High Strength Concrete Small Hollow Blocks Made with Rock Chips as Aggregates

It is more and more general of using industrial solid waste as the aggregates in construction materials for non-structural applications. But because of the developments and applications of reinforced blocks masonry structure in the modern masonry structure, especially in the mid-high and high storey buildings, there will be a growing interest of using industrial solid waste to produce high strength concrete small hollow blocks for structural applications. This experiment by mixing the different proportions of rock chips within the range of 30-70% as the replacement for sand prepared high strength concrete small hollow blocks which the compressive grade is MU 15.0, the influence of aggregates grading on the compressive strength of high strength concrete small hollow blocks was investigated at the same water/cement (w/c) ratio (0.45). In addition, the influence of the different curing methods on the compressive strength and shrinkage of high strength concrete small hollow blocks were also investigated, test results showed that high strength concrete small hollow blocks under the curing method which is the one-time pouring the ample amount of water, covered and sealed with plastic sheeting, the compressive strength had a better development, and the total shrinkage was larger than others.

Development and Technical Points of the Small Fly Ash Hollow Block

The small fly ash hollow block, compared with other traditional wall materials, has many advantages. If the block is put into production, it will bring huge environmental, economical and social benefits. This paper describes the technical points about the mix ratio test of the small fly ash hollow block.

Micromorphology of Sorbus intermedia Pers. nectary surface in different phases of blooming

The structure of floral nectary surface of &lt;i&gt;Sorbus intermedia&lt;/i&gt; in different phases of flower development was examined using scanning electron microscopy. Nectaries in &lt;i&gt;S. intermedia&lt;/i&gt; flowers represent a receptacle type. The sculpture of cuticule on nectary epidermis and overlaying cells was described. The differences in the size of striaes on the outer cell wall of epidermis during the flower development were stated. Nectarostomata were situated in small hollows. In the buds, they were closed and not fully developed. During pollen release phase, the outer ledges of the guard cells were better developed than at the beginning of blooming. Depressions on nectary epidermis cell walls were observed in the final phase of blooming.

Glycosaminoglycans Improves Early Development of Zona-free 8-cell Rat Embryos to Blastocysts in a Chemically Defined Medium, but Not the Pregnancy Rate Following Transfer of the Blastocysts

The objective of the present study was to clarify the possible role of the zona pellucida (ZP) in early development of rat embryos and to determine the effect of glycosaminoglycans on the development of ZP-free 8-cell embryos before or after embryo transfer at the blastocyst stage. Eight-cell embryos were divided into three groups comprised of, 1) intact controls, 2) embryos with the ZP was removed with acidic solution and 3) pairs of ZP-free 8-cell embryos aggregated in a small hollow. These embryos were cultured in a chemically defined mR1ECM for 24 h. Developmental ability to the blastocyst stage and mean cell number in the blastocyst was lower in ZP-free embryos than in intact controls. When these blastocysts were transferred, the farrowing rate and efficiency of embryos developed to term were also lower in ZP-free embryos, but not in the aggregated ones. Supplementation with hyaluronan (HA; 63-250 µg/ml) or heparan sulfate proteoglycan (HS; 15 µg/ml) significantly improved blastocyst formation of ZP-free embryos and the cell number in the blastocyst by reducing the incidence of apoptosis. However, there were no beneficial effects of HA or HS on farrowing and newborn rates after transfer of the blastocysts. In conclusion, the ZP plays roles in maintaining successful development of early rat embryos at least from the 8-cell stage not only to the blastocyst stage but also to posttransfer stages. Glycosaminoglycans, such as HA or HS, appear to contribute to successful cleavage during early development to the blastocyst stage but may be insufficient to maintain the posttransfer survival of ZP-free embryos.

PH-responsive liposome-templated polyelectrolyte nanocapsules

Hollow nanocapsules made of polyelectrolytes, extensively useful for biomedical and biotechnological applications, are produced with a simple Layer-by-Layer approach using liposomes as template. The biocompatible polymers, alginate and chitosan, are alternatively adsorbed onto liposomes allowing the achievement of small size hollow nanocapsules with an average diameter of ∼280 nm. Hollow nanocapsules, positively as well as negatively charged, depending on the number of layers, can be produced in a reproducible way. The produced nanocapsules are demonstrated to be sensitive to pH changes of the environment because of the behaviour of the polyelectrolytes composing the multishell walls; in fact they exhibit major variations in size depending on the bulk solution pH. Measurements of dynamic light scattering (DLS) and of ζ-potentials as well as scanning electron microscopy (SEM) observations demonstrate a correlation between the pH and the shrinking/swelling of the nanocapsules. While nanocapsules having chitosan as outer layer are stable only at acidic pH, nanocapsules having alginate as outer layer remain stable at all the pHs used in this study (pH 4.6 to 8). The pH-optimum for the shrinking event is in the acidic range. The role of both the polymers in the shrinking/swelling event is demonstrated by comparing nanocapsule populations with alginate (7 layers) or chitosan (8 layers) as the outer layer.

Effect of Slag Content on Physical and Mechanical Properties of Lightweight Aggregate Concrete Small Hollow Blocks

This paper introduced a method of saving materials and energy through making small hollow blocks with the slag admixture in the lightweight aggregate concrete. Through orthogonal design, this paper took slag content, water binder ratio and admixture dosage into consideration and focused on influence of slag content on the physical and mechanical properties of lightweight aggregate concrete small hollow blocks. The results show that: when water binder ratio ，admixture dosage and curing system keep a fixed level, during the range of slag content 30%-40%, with the increase in slag content, the compressive and bending strength of small hollow block increased first and then decreased; water content and absorption and relative water moisture content decreased first and then increased; frost resistance increased then decreased; softening coefficient first increased and then decreased. When the slag content is 35%, the physical and mechanical properties of lightweight aggregate concrete small hollow block are the best, and all the indexes of physical and mechanical properties can meet the standard requirements non-bearing lightweight aggregate concrete hollow block. The curing system significantly affected the strength of the lightweight aggregate concrete small hollow block, and the block strength cured under the standard condition was higher than those under natural condition.

Thermal Decomposition of Dolomite Containing Phosphorus

In this paper,DTA-TG and TEM are used to investigate dolomite containing phosphorus. The investigations suggest that the thermal decomposition of dolomite containing a little bit of phosphorus powder has only one reaction while that of dolomite has two reactions, and the final temperature of the reaction reduces by about 18°C. The oxidation reaction of the phosphorus in dolomite begins at about 500°C, which is 140°C higher than that of the oxidation reaction of phosphorus in standard atmosphere condition. Round-bubble-shape structure gradually appears on the surface of the dolomite sample when observed using TEM. Furthermore, the number and size of this structure increased with the rising of the temperature. Finally, the round-bubble-shape structure breaks to small hollows, showing as teared-shape, and forms a series of protruding and intensive larger hollows and spherical shape. Therefore, the temperature of thermal decomposition of thermal decomposition of dolomite is decreased and the components of thermal decomposition products of dolomite containing phosphorus are almost the same as that of dolomite.