Content Of Fragments Research Articles

The influence of soil pollution by heavy metals on the land suitability for irrigated wheat farming in Zanjan region, northwest Iran

The main objective of this study was to assess the land suitability for irrigated wheat farming, surrounding the Zinc Specialized Industrial Town (briefly, Zinc Town), northwestern Iran, with soils polluted by zinc (Zn), lead (Pb), and cadmium (Cd). The concentrations of heavy metals (HMs) were measured in 110 topsoil samples (0–20 cm), as well as in 65 samples of wheat grains. The limitation scores for the climatic factors, soil properties, and HMs were calculated based on their limitation for wheat cropping. Afterwards, the accumulated limitation scores were used for calculation of the land suitability membership scores using an exponential function, and then the maps were produced. The results showed that there were optimal climatic conditions for irrigated wheat, whereas due to the youthfulness of studied soils, the content of coarse fragments (CF), as the most limiting soil property, made moderate to very severe limitations in more than half of sampling points. Regarding the Iranian threshold values of 500, 75, and 5 mg kg−1 as the MPC for Zn, Pb, and Cd, respectively, 7.27, 30.0, and 20.0% of soil samples were classified as the polluted soil to these pollutants. On the other hand, Pb and Cd concentrations in 24.6 (16 samples) and 29.2 (19 samples) % of cultivated wheat in the studied area exceeded the threshold value of 0.2 mg kg−1, respectively, whereas Zn concentration in none of the sampled plants was higher than the threshold value of 50.0 mg kg−1. Land suitability for wheat farming significantly decreased near the Zinc Town due to the HMs transferring from polluted soils to wheat grains. Therefore, potential threat of metallic pollutants for secure and safe food production should be considered as an important environmental factor to accurate assessment of land suitability for a given crop.

Analyzing and Projecting Soil Moisture and Cone Penetrability Variations in Forest Soils

This article details how forest soil moisture content (MC) and subsequent resistances to cone penetration (referred below as Cone Index, CI) vary by daily weather, season, topography, site and soil properties across eleven harvest blocks in northwestern New Brunswick. The MC- and CI-affecting soil variables refer to density, texture, organic matter content, coarse fragment content, and topographic position (i.e., elevation, and the seasonally affected cartographic depth-to-water (DTW) pattern). The harvest blocks were transect-sampled inside and outside their wood-forwarding tracks at varying times throughout the year. In detail, 61% of the pore-filled moisture content (MCPS) determinations inside and outside the tracks could be related to topographic position, coarse fragments, bulk density, and forest cover type specifications. In addition, 40% of the CI variations could be related to soil depth, MCPS, and block-specific cover type. Actual versus model-projected uncertainties amounted to ΔMCPS ≤ ± 15% and ΔCI ≤ ± 0.5 MPa, 8 times out of 10. Block-centered MC and CI projections were obtained through: 1) daily hydrological modelling using daily precipitation and air temperature weather-station records nearest each block, and 2) digitally mapped variations in soil properties, elevation, DTW and forest cover type, done at 10 m resolution.

The nacency of jurisdictio voluntaria from the letter and the spirit of Roman law

The article is devoted to the history of the emergence of an idea of indisputable/voluntary jurisdiction in ancient Rome. As a research base, Digesti Justiniana was analyzed as the main monument of Roman law. There was no holistic conception of the division of jurisdiction into contested and indisputable/voluntary in ancient Rome. The terms “contested jurisdiction” and “indisputable/ voluntary jurisdiction” were not themselves used in Digest. The Digest text itself can also be considered to be only a partly authentic Latin text: first, the original has been changed by glossators and post-glossators, and secondly, the translation of such a complex text will also make its corrections to the content of the ascending text. There is no translation into Ukrainian of this monument, and the content of many fragments can be understood only in the context of specific historical and political events. However, it is evident that in ancient Rome, special procedures and proceedings, other than judicial proceedings, have begun to emerge. They were aimed at preventing violations, protecting and protecting rights through their consolidation, confirmation, and sanction, carried out on a voluntary basis and with the help of special state tools by the efforts of authorized persons. However, these processes have not received proper theoretical consolidation and substantiation. At least this is not reflected in the Digest text. In a later period, apparently thanks to the efforts of glossators and post-glossators, such procedures and proceedings were called “indisputable/voluntary” jurisdiction, and jurisdictions were divided into indisputable/ voluntary jurisdiction and contested jurisdiction. The very term “voluntariа” (“volumtarium”) is polysemantic and can be translated as voluntary, indisputable and consensual and can be interpreted as the absence of coercion by the other party, the absence of a dispute about the right or lack of duty on the part of the official persons to satisfy the requirements of those persons who turned to them for confirmation of facts or solving a difficult situation. The idea of indisputable/voluntary jurisdiction was born not so much from the “letter” of Roman law, but from its “spirit”. Article received 05.11.2018

Effect of rock fragment content on erosion processes of disturbed soil accumulation under field scouring conditions

Soil and water erosion from high rock fragment content disturbed soil accumulation severely threatens ecological security. Evaluation of the quantitative influence of rock fragment content on soil erosion processes was the basic research for soil and water conservation. Field simulation scouring experiments were conducted on the disturbed soil accumulation experimental plot. A 10 × 1-m2 plot with 28 gradients was established on Changwu Experimental Station in the Loess Plateau, China. Tap water was applied at the top of the plot with the four different flow discharge rates of 1.3 × 10−4, 1.7 × 10−4, 2.1 × 10−4 and 2.5 × 10−4 m3 s−1 to simulate surface runoff processes. The experimental plots underlying surfaces were filled with different rock fragment content of 20%, 40% and 0%. The soil used in these experimental plots was a silty loam from the disturbed soil accumulation formed by expressway construction in the loess plateau areas. The disturbed soil accumulation site was located near the G70 Fujian–Yinchuan expressway and the vegetation cover was very low. The mean diameter of rock fragments was 22 mm in these experiments, and the rock fragments were unsmooth, angular crushed stone taken from the quarry in the Changwu County. The results showed that rock fragment content of 20% and 40% could significantly decreased runoff and sediment (P < 0.05), although there was no significantly different between 20 and 40%. The rock fragments decreased mean flow velocity by 43 to 55% in mean flow velocity compared to the pure soil. Furthermore, the flow was laminar flow in the rock fragments slope. The rock fragments significantly decreased flow shear stress (52–89%), stream power (63–89%), unit stream power (41–59%), runoff kinetic energy (67–88%) and unit energy of the water-carrying section (81–89%) compared with the pure soil. With increased rock fragment content, the rill erodibility decreased. The rill erodibility was estimated to be 1.4 × 10−3 s m−1, 0.7 × 10−3 s m−1 and 0.5 × 10−3 s m−1, under the condition of pure soil, rock fragment content of 20% and 40%, respectively. Low rock fragment content (< 40%) in disturbed soil accumulation significantly decreased runoff and sediment. With the rock fragment content increased, the rill erodibility was decreased. Appropriate rock fragment content could be used to control soil erosion on disturbed soil accumulation in practice. The important parameters from this study will be helpful for disturbed soil accumulation erosion prediction model establishment.

Characterization of Humic Acids in Mountainous Meadow Soils and Burozems of the Crimea Using 13C-NMR

A comparative analysis of organic matter in the mountainous soils under the main plant communities of the Crimea was performed. The humus state of burozems and mountainous meadow soils under natural meadow vegetation and planted forests was studied using traditional methods and 13C-NMR spectroscopy for the determination of the contents of total organic carbon, carbon of humic acids and optical density of humic acid solutions. The highest humus content in the A horizon was found in the dark burozem under the beech–hornbeam forest on the Chatyr-Dag Plateau. The meadow soils of the Ai-Petri Plateau were significantly inferior in terms of humus content than the dark burozem and meadow soils of other Crimean plateaus due to the intensive anthropogenic impact on these lands until the 1970s. The lowest humus content was found in the meadow soils of the forested Ai-Petri areas because of the strong degradation of the grass cover after planting trees. The investigation of humic acids using the 13C-NMR method showed that humic acids of Crimean mountainous soils were characterized by the elevated hydrogen content, which well agreed with the content of alkyl fragments. The structural molecular composition of humic acids was dominated by aliphatic components, aromatic components being weakly expressed. At the same time, the aromaticity was somewhat higher in the cases when the soil was formed in the meadow ecosystem; it was lower in the upper soil horizons of the forest ecosystems. The degree of aromaticity of humic acids is intermediate between that of podzolic and chernozem soils, which is typical for soils of semihumid regions. The substitution of herbaceous vegetation in the course of natural overgrowing or afforestation of areas with meadow soils has led to an increase in their acidity, but it had no noticeable effect on the elemental and structural composition of humic acids.

Assessment of genetic diversity among different sugarcane genotypes using internal transcribed spacer (ITS) region of the ribosomal DNA (rDNA)

Internal transcribed spacer or ITS region of nuclear ribosomal DNA (rDNA) has been used to evaluate genetic assortment and phylogenetic relationship in nine sugarcane genotypes including Saccharum species and another related genus as Erianthus, Narenga and hybrid. DNA was extracted from selected genotypes and ITS (ITS-1 and ITS-2) regions were amplified using specific primers. The sequence lengths ITS-1 showed 205- 207 bp, while ITS2 was ranged from 211- 218 bp. However, G+C content (%) 65.2% - 67% in ITS-1 and in ITS-2 68.4% - 99.7%. The sequence lengths of fragment and GC content of ITS-1 and ITS-2 regions showed variable. To evaluate the phylogenetic association of both the region of ITS (ITS-1 and ITS-2) neighbor-joining (NJ) method was employed. The cluster A of ITS-1 and cluster B for ITS-2 and cluster C combined between ITS1+ ITS2 sequences gave two distinct groups A and B. The group A represented the ITS1 sequences which showed two subgroups I and II. The A-I subgroup consisted of wild species of sugarcane; Erianthus, Narenga and S. robustum, whereas the A-II subgroup consisted of the Saccharum species and hybrid. The ITS2 sequences in the group B showed better correlation amongst each other. The sequences ITS-1 & ITS-2 combined and compared with some selected sequences from NCBI database using NJ method. The results have confirmed that ITS region can be used for evaluating the genetic assortment in Saccharum and its closely related genes.

The effects of rock fragment content on the erosion processes of spoil heaps: a laboratory scouring experiment with two soils

Spoil heaps on newly engineered landforms create extensive artificially accelerated erosion, especially when there are catchment areas above spoil heaps, erosion caused by runoff will be much greater than that induced by rainfall. This study investigated the erosional characteristics of clay loam and sandy loam spoil heaps and proposed an appropriate hydraulic parameter to simulate the variation in erosion rate. A laboratory scouring experiment was conducted using a soil pan (dimensions 5 m × 1 m × 0.5 m deep) with a discharging arrangement to test four samples of clay loam and sandy loam containing rock fragments (0%, 10%, 20%, and 30%) by mass. The slope of simulated spoil heaps was 53.2% with a discharging inflow rate of 15 L min−1. The rock fragments used were those commonly used in construction works, having a diameter of 2–3 cm and irregular shape. Twenty-four scouring tests for eight treatments with duplication were accomplished in total. Average erosion rates showed a negative linear correlation with rock fragment content in clay spoil heaps (R2 = 0.94) and a positive linear correlation in sandy loam spoil heaps (R2 = 0.92). Rill width evolution of clay loam spoil heaps mainly developed at the early scouring stage (0–15 min), and rills developed even more rapidly during later scouring times (30–60 min) in sandy loam spoil heaps. Grey relational analysis showed that sheer stress and stream power both had higher Grey relational degrees with erosion rate for both soils, regression analysis showed that stream power can efficiently describe the erosional process of clay loam and sandy loam for each rock fragment content, but sheer stress only did well in sandy loam heaps. Adding rock fragments to spoil heaps resulted in significantly opposite effects in the different soils; great attention should be paid to sandy loam spoil heaps due to their more severe erosion with increasing rock fragment content; stream power is an appropriate hydraulic parameter to simulate the soil erosion process of spoil heaps for both soil types.

Determining hot moments/spots of hillslope soil moisture variations based on high-resolution spatiotemporal soil moisture data

Characterizing soil moisture variation has critical implications for various ecosystem processes and the hydrological cycle. In this study, we identified the hot moments (times with high temporal variation rates) and hot spots (areas with high temporal variation rates) of the soil moisture variation and investigated their controlling factors on a tea garden hillslope in Taihu Lake Basin, China. Daily soil moisture data were calculated for 39 sites, and then, daily soil moisture maps were generated from March 1, 2014 to February 28, 2015. The soil moisture temporal variation rates (VR) at different locations and during different time periods were calculated based on these maps. We found that because soil water content at the subsurface was more spatially varied than that at the surface on this hillslope, spatial heterogeneity of VR was also greater at 0.3-m depth than that at 0.1-m depth. Elevation, sand content and rock fragment content were positively correlated (p < 0.05) with this spatial heterogeneity, while slope and clay content were negatively correlated (p < 0.05) with it. June and July 2014 were the hot moments with high VR at both depths of 0.1- and 0.3-m, while December 2014 was the cold moment with the lowest VR at both depths on this study hillslope. Meteorological factors (precipitation and temperature) explained 59.9% and 56.9% of the total variance in the time series of spatial mean VR at the depths of 0.1- and 0.3-m, respectively. Stronger variations in spatial mean VR were found during representative medium and large rainfall events than during representative small rainfall events. In addition, the response of spatial mean VR to rainfall at 0.3-m depth was delayed compared to that at 0.1-m depth. The findings and methodologies of this study can be useful in determining the hot spots and hot moments of soil moisture variations, which could be potentially useful for investigating various hydrological, ecological, environmental, and agronomic processes.

Urbanization Leads to Increases in pH, Carbonate, and Soil Organic Matter Stocks of Arable Soils of Kumasi, Ghana (West Africa)

Tropical soils typically have low cation exchange capacity and nutrient contents. Both are enhanced by soil organic matter (SOM), which is thus particularly important for the fertility of these soils. In this study, we assessed the influence of urbanization on SOM, carbonate contents and pH of arable soils of Kumasi (Ghana, West Africa), since rapid urban sprawl is widespread in West Africa, whereby in many West African cities urban farming is pivotal to the food security of their population. Based on satellite imagery for the year 1986, we distinguished long-term and short-term urban arable soils, whereby long-term urban soils were urban already in 1986 (thus  30 years, as soil sampling took place in 2016), and short-term urban soils became urban afterwards (< 30 years). We took 618 undisturbed topsoil samples (0-10 cm) from 206 urban arable fields. The factors land-use (maize fields) and soil (Ferric Acrisols) were kept largely constant. The fine-earth was analysed for pH (water), carbonate contents, loss on ignition (LOI), total C (TC) and N (TN). SOM contents were obtained from LOI (SOMLOI). All element contents were transformed to bulk soil element stocks per m2. Differences between short-term and long-term urban soils were identified by a set of linear mixed models. Coarse fragments were more abundant in the long-term (16%) compared to the short-term (10%) urban soils, because of solid municipal waste that accumulates over time in urban soils. TC and SOMLOI concentrations of the fine earth, pH and C/N ratios were all significantly higher in the long-term urban soils. SOC concentrations in the fine earth, as well as bulk soil stocks of TC, SOC and SOMLOI were also higher in the long-term urban soils, but at a lower degree of confidence, due to variable bulk densities and contents of coarse fragments. We conclude that dumping of organic and inorganic waste (including ash, bones, egg shells, concrete and mortar) increases SOM stocks and soil pH, but also leads to accumulation of non-degradable solid materials (including plastic, metals etc.). These findings point to the need of an improved urban waste management system, separating degradable and non-degradable waste.

Pyrogenic organic matter from palaeo-fires during the Holocene: A case study in a sequence of buried soils at the Central Ebro Basin (NE Spain)

We studied the fire record and its environmental consequences during the Holocene in the Central Ebro Basin. This region is very sensitive to environmental changes due to its semiarid conditions, lithological features and a continuous human presence during the past 6000 years. The study area is a 6 m buried sequence of polycyclic soils developed approximately 9500 years ago that is exceptionally well preserved and encompasses four sedimentary units. The content and size distribution of macroscopic charcoal fragments were determined throughout the soil sequence and the analysis of the composition of charcoal, litter and sediments via analytical pyrolysis (Py-GC/MS). The high amount of charcoal fragments recovered in most horizons highlights the fire frequencies since the beginning of the Neolithic, most of which were probably of anthropogenic origin. In some soil horizons where charcoal was not found, we detected a distribution pattern of lipid compounds that could be related to biomass burning. On the other hand, the low number of pyrolysates in the charcoal could be attributed to high-intensity fires. No clear pattern was found in the composition of pyrolysates related to the age of sediments or vegetation type. The most ancient soil (Unit 1) was the richest in charcoal content and contains a higher proportion of larger fragments (>4 mm), which is consistent with the burning of a relatively dense vegetation cover. This buried soil has been preserved in situ, probably due to the accumulation of sedimentary materials because of a high-intensity fire. In addition, the pyrogenic C in this soil has some plant markers that could indicate a low degree of transformation. In Units 2–4, both the amount of charcoals and the proportions of macrofragments >4 mm are lower than those in Unit 1, which coincides with a more open forest and the presence of shrubs and herbs. The preservation of this site is key to continuing with studies that contribute to a better assessment of the consequences of future disturbances, such as landscape transformation and climate change.

Influence of Chemical Modification on the Structure, Composition, and Properties of Lignite Humic Acids

The influence of chemical modification on the functional–group composition of humic acids derived from Tisul’sk lignite (Kansko-Achinsk Basin) is studied. The structural changes of the humic acids as a result of destructive alkylation of n-butanol and oxidation of hydrogen peroxide are compared, by means of IR, Raman, ESR, and NMR spectroscopy. Alkylation of the humic acids changes the composition and content of the aliphatic fragments in their structure. Oxidation by hydrogen peroxide increases the content of acid-bearing groups.

High‐Frequency Sequence Stratigraphy and Fine‐Scale Reservoir Characterization of the Devonian Sandstone, Donghe Formation, North Uplift of the Tarim Basin

AbstractThe Devonian Donghe Sandstone complex in North Uplift of the Tarim Basin comprises of a series of diachronous sandy intervals deposited from the Late Devonian to Early Mississippian. They are constrained by a Late Devonian to Early Pennsylvanian 2nd‐order supersequence and can be subdivided into five 3rd‐order sequences, namely, S1, S2, S3, S4, and S5, from the oldest to youngest. Cores from four wells, 40 wireline logs, 410 thin sections, and porosity and permeability data from 639 spots from four wells were used to study the sediment provenance, build up the sequence‐stratigraphic model of S5, and characterize the reservoirs at a feet scale. Detrital modes of sandstone from point counting indicate that Donghe Sandstone is directly sourced from recycled orogeny. The low content of feldspar and volcanic rock fragments suggests that Donghe Sandstone is recycled from sediment with a cratonic ultimate source. 1D and 2D chronostratigraphic correlation shows that at least 12 4th‐order high‐frequency sequences (HFSs), from the oldest HFS1 to the youngest HFS12, can be recognized in S5. Each HFS is characterized by a general trend of shallowing‐upward facies assemblage. Sequence boundaries were defined at where regionally correlatable deep‐water facies overlaying shallow‐water facies. There is a general shallowing‐upward trend in the S5 3rd‐order sequence, characterized by a systematically increasing proportion of shallow‐water facies (foreshore and upper shoreface), and a decreasing proportion of deep facies (offshore transition and lower shoreface). The shallowing‐upward trend within both 3rd‐ and 4th‐order sequences is resulted from a combined effect of eustatic sea‐level change, tectonic activity, and sediment supply. The sequence‐stratigraphic model of Donghe Sandstone S5 is similar to the rift‐basin sequence‐stratigraphic model. Sweet spots were defined as porosity &gt;15% and permeability &gt;100md intervals, and their distribution and lateral continuity were investigated. HFS is one of the primary controls on the distribution of sweet spots distribution and can be used to guide hydrocarbon exploration.

Effects of rock fragment content, size and cover on soil erosion dynamics of spoil heaps through multiple rainfall events

Spoil heaps are the main sources of soil erosion on disturbed land surfaces as an artificial accelerated erosion form, and rock fragments are an important component of spoil heaps. This study examined different fragment contents (0, 20, 40, 60 mass percentage) and sizes (1–4, 4–7, 7–10 cm) on hydrological processes, sediment yielding processes and rock fragment cover evolution through three sequential simulated rainfalls with a constant intensity of 1.5 mm min−1. The rock fragments in spoil heaps were found to reduce the soil loss amount by 35.23–76.84% through effects on runoff production and rock fragment cover. Runoff rates decreased with increasing rock fragment content, and size class 4–7 cm had the strongest reduction effect, but for a definite treatment runoff rates have little change in three rainfall events. The expanding rock fragment cover with cumulative rainfall in the multiple rainfall events, which increased fastest during the first rainfall period led to a significant decreasing soil detachment rate. Multiple regression analysis shows that the average detachment rate under each rainfall event could be estimated using a power function of average runoff rate and median rock fragment cover. These findings indicated that the presence of rock fragments in spoil heaps has an obvious mitigating effect on soil erosion, with the rock fragment content making a larger percentage contribution than rock fragment size.

Segmenting discourse: Incorporating interpretation into segmentation?

AbstractDiscourse segmentation is an important step in the process of annotating coherence relations. Ideally, implementing segmentation rules results in text segments that correspond to the units of thought related to each other. This paper demonstrates that accurate segmentation is in part dependent on the propositional content of text fragments, and that completely separating segmentation and annotation does not always yield text segments that correspond to the text units between which a conceptual relationship holds. In addition, it argues that elements belonging to the propositional content of the discourse should necessarily be included in the segmentation, but that inclusion of other text elements, for instance stance markers, should be optional.

Rock fabric and pore structure of the Shahejie sandy conglomerates from the Dongying depression in the Bohai Bay Basin, East China

The pore structure of sandy conglomerates, which is primarily controlled by the rock fabric, is a key topic in the microscopic physical study of reservoirs and is also of great significance for sandy conglomerate reservoir evaluation. This study focuses on the rock fabric and pore structure characteristics of sandy conglomerates of the upper submember of the fourth member of the Eocene Shahejie Formation (Es4U) in the Dongying depression, Bohai Bay Basin, East China. This study incorporates integrated approaches of casting thin-sections, scanning electron microscopy (SEM), X-ray diffraction, high-resolution core scanning image acquisition, grain size analysis, physical property tests and mercury injection. The sandy conglomerates mainly consist of pebbly sandstone and gravel sandstone; feldspar and rock fragments are dominant rock components, followed by quartz, with ranging from 25.8% to 37.7% (averaged 31.8%), 21.8% to 46.9% (averaged 31.1%) and 17.0% to 34.4% (averaged 28.0%), respectively. The pore types mainly include primary pores, secondary interparticle (interP) pores and secondary intraparticle (intraP) pores, in addition to some microcracks and intercrystalline pores. Rock textures are divided into two types according to sorting features and roundness: uniform and uneven. Porosity values are between 2.2% and 16.5% and exhibit positive correlations with quartz content and grain size and negative correlations with the content of rock fragments, interstitial material, gravel distribution uniformity, sorting coefficient and maximum particle size. In contrast, the relationships between displacement pressure and these rock fabric parameters show very different trends. The different relationships suggest that rock fabric is closely related to pore structure. In particular, sandy conglomerate samples have a relatively high compositional maturity and uniform rock texture and exhibit a better pore structure. Four typical samples were chosen to verify the relationship between rock fabric and pore structure in the logging profile of Well YN22-22. The results strongly suggest that the rock fabric can be used to indicate the effectiveness of the reservoir in the study area.

Rock fragment and spatial variation of soil hydraulic parameters are necessary on soil water simulation on the stony-soil hillslope

Whether the spatial variation and influence of rock fragment contents (RFCs) on soil hydraulic parameters (SHPs) should be jointly considered in the soil water simulation have been less investigated in previous studies. In this study, we tested whether considering these factors were necessary in the soil water simulation on a representative stony-soil hillslope located in Taihu Lake Basin, China. Five schemes of SHPs in HYDRUS-3D model were established. They were (i) MultiRFHet: spatially varied SHPs extracted from Durner’s multimodal retention function based on the observed soil water retention data; (ii) RosHom: spatially uniformed SHPs derived from ROSETTA; (iii) RosHet: spatially varied SHPs derived from ROSETTA; (iv) RosRFCHom: spatially uniformed SHPs derived from ROSETTA and adjusted by RFCs; (v) RosRFCHet: spatially varied SHPs derived from ROSETTA and adjusted by RFCs. Results indicated when the spatial variation and influence of RFCs on SHPs were both considered (MultiRFHet and RosRFCHet), acceptable accuracies (Nash-Sutcliffe efficiency or NSE ≥ 0.58 for MultiRFHet and > 0.17 for RosRFCHet) were achieved in simulating the soil water storage (SWS) variation. Since the MultiRFHet required the calibration by the observed soil water retention data, RosRFCHet was a good alternative in the simulation. On the contrary, the SHPs acquired without considering neither the RFCs nor the spatial variation yielded unacceptable simulation results (NSE general < 0). This demonstrated that spatial variation and influence of RFCs on SHPs should be included in the SWS simulation on this stony-soil hillslope, although it had limited effect in subsurface flow simulation.

Permeability evolution in natural fractures and their potential influence on loss of productivity in ultra-deep gas reservoirs of the Tarim Basin, China

This article examines the influence of working fluids on stress-induced permeability alteration in an ultra-deep tight sandstone gas reservoir. Permeability alteration during hydrostatic compression and infiltration of oil-based drilling fluids and acidizing fluids was investigated in a laboratory setting. The laboratory results indicated that the permeability of fractures in the tight sandstone was influenced by both the alterations in the stress state and type of fluid treatment. In general, the permeability alterations in the fractures are irreversible and cannot be completely eliminated. The stress sensitivity coefficient of the rock samples that were untreated, treated with drilling fluids or treated with acidizing fluids were, on average, 0.45, 0.58 and 0.67, respectively. The high lithic fragment content, multi-scale natural fractures and the rock property changes induced by the working fluids are thought to be the factors controlling the permeability stress sensitivity. A computational procedure was used to assess the influence of various fracture permeability evolution models on the well performance. Simulation results show that the deeper the invasion depth of working fluids and unsuitable drawdown pressures have a significant negative influence on the cumulative production. Finally, a control strategy for addressing stress-sensitivity damage and the influence of production fluids in ultra-deep tight sandstone gas reservoirs is proposed.

Case Study: Intra-Patient Heterogeneity of Aneurysmal Tissue Properties

Introduction: Current recommendations for surgical treatment of abdominal aortic aneurysms (AAAs) rely on the assessment of aortic diameter as a marker for risk of rupture. The use of aortic size alone may overlook the role that vessel heterogeneity plays in aneurysmal progression and rupture risk. The aim of the current study was to investigate intra-patient heterogeneity of mechanical and fluid mechanical stresses on the aortic wall and wall tissue histopathology from tissue collected at the time of surgical repair.Methods: Finite element analysis (FEA) and computational fluid dynamics (CFD) simulations were used to predict the mechanical wall stress and the wall shear stress fields for a non-ruptured aneurysm 2 weeks prior to scheduled surgery. During open repair surgery one specimen partitioned into different regions was collected from the patient's diseased aorta according to a pre-operative map. Histological analysis and mechanical testing were performed on the aortic samples and the results were compared with the predicted stresses.Results: The preoperative simulations highlighted the presence of altered local hemodynamics particularly at the proximal segment of the left anterior area of the aneurysm. Results from the post-operative assessment on the surgical samples revealed a considerable heterogeneity throughout the aortic wall. There was a positive correlation between elastin fragmentation and collagen content in the media. The tensile tests demonstrated a good prediction of the locally varying constitutive model properties predicted using geometrical variables, i.e., wall thickness and thrombus thickness.Conclusions: The observed large regional differences highlight the local response of the tissue to both mechanical and biological factors. Aortic size alone appears to be insufficient to characterize the large degree of heterogeneity in the aneurysmal wall. Local assessment of wall vulnerability may provide better risk of rupture predictions.

Synthesis of Hydrocarbon Resins by Thermal Polymerization of Unsaturated Compounds of Pyrolysis Fractions

Hydrocarbon resins were synthesized by thermal polymerization of the olefinic compounds of liquid pyrolysis products (the C9+ fraction, heavy tar). The hydrocarbon resins were characterized by 1H NMR spectroscopy, MALDI spectroscopy, and gel permeation chromatography. The effect of temperature, reaction time, feed composition, and solvent content on the yield, molecular weight, color, and molecular structure of the hydrocarbon resins was investigated. It was shown that addition of the C9+ fraction to heavy tar increases the polymer yield while reducing the content of aromatic fragments in its structure.

흥전리사지 출토 고승비편의 내용과 흥전리사지의 역사적 성격

흥전리사지 출토 고승비편의 내용과 흥전리사지의 역사적 성격