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Teaching aids like chalkboard and power point (PPT) have commonly been used in medical teaching. With an increasing number of medical seats and introduction of competency-based curriculum, PPT is being preferred. Chalk board talk lecture is the oldest and most commonly used teaching method. After introduction of digitalized teaching in medical colleges Power point presentation Lecture method is commonly used. This study was to evaluate the feedback from MBBS students regarding opinion and preferences of chalk board and PPT lecture delivery aids. The present study was well planned, prospective and cross-sectional questionnaire-based study conducted on MBBS UG medical students in India. 200 students were selected from all years of MBBS. Google form Questionnaire was used to know advantages and drawbacks of Chalk Board and PPT lecture teaching method. In present study 52 % students preffered PPT lecture teaching, 26 % students preffered chalk board lecture teaching. 22% students preffered both PPT and Chalk board teaching methods. The results of the present study suggest that both the tools of teaching (PowerPoint or chalkboard) have some strengths and limitations. Therefore, integrated (PowerPoint and chalkboard) method of teaching is more suitable tool of teaching and learning at undergraduate medical schools. [ABSTRACT FROM AUTHOR]

Successful management of chalk reservoirs for various subsurface applications as well as construction in chalk/limestone formations rely on descriptions of compaction behaviour commonly predicted from laboratory experiments. This study aims to understand and describe better the compaction behaviour that oil and water-saturated chalk undergo. Seven North Sea Lower Cretaceous chalk samples with initial porosity ranging from 31 to 45% were compacted hydrostatically in the laboratory. The traditionally named elastic, transitional, elastoplastic and strain hardening phases were identified from stress–strain curves. The observed compaction behaviour is described in phenomenological terms based on the interpretation of Biot's coefficient as a measure of grain-to-grain contact area within the chalk frame. Biot's coefficient was derived from elastic wave velocities and bulk density via Gassmann fluid substitution by first approximations assuming a simple calcite-bearing rock frame. Biot's coefficient identifies both elastoplastic and elastic phases in the initial compaction phase traditionally denoted as the elastic phase. The plastic component of the elastoplastic phase presumably originates from closure of micro-crack introduced by unloading and equilibration from core recovery. Biot's coefficient is a reliable indicator of pore collapse, and a specific constant magnitude of purely elastic strain controls the onset of pore collapse. In situ reservoirs presumably only experience the elastic strain during effective stress changes, not the elastoplastic behaviour seen in experiments. Yet, as laboratory experiments often form a calibration background for large-scale models, quantifying the plastic component of elastoplastic phases and pore collapse from pure elastic strain provides new insight to improve models and avoid the unphysical use of porosity as a controlling physical parameter. Highlights: During initial compaction, both elastoplastic and elastic phases exit and are identified from Biot's coefficient. During compaction, a local minimum Biot's coefficient derive from ultrasonic velocities is a reliable indicator of pore collapse. A critical and purely elastic strain derived from applied stress and dynamic moduli is the controlling mechanism of pore collapse. Identification of subphases and a critical pore collapse elastic strain provides new insight into calibration of reservoir model from experiments. [ABSTRACT FROM AUTHOR]

High-temperature insulation materials are used extensively in civil engineering as flame retardant materials, as well as in numerous industrial sectors. The raw materials used in the production of these materials include rocks and industrial waste. The article substantiates the feasibility of using ceramovermiculite and ceramoperlite materials containing a wollastonite binder as high-temperature insulation. The materials were obtained through the firing of a charge containing chalk, diatomite, and a heat-resistant filler (expanded perlite or expanded vermiculite). The material of the fired samples with expanded vermiculite is primarily composed of the crystalline phase of wollastonite and biotite, with a minor amount of quartz and akermanite-gehlenite. The use of expanded perlite as a heat-resistant filler results in the presence of a low amount of plagioclases in addition to the crystalline phase of wollastonite in fired samples, along with an amorphous phase. The physicomechanical properties of the charge and the fired samples were determined, and the effect of the apparent density and phase composition of the developed materials on the variation in their thermal insulation properties at high temperatures was studied. The thermal insulation properties of the materials were determined by supplying heat flow from the heating chamber of the muffle furnace to one side of the sample. The samples from the developed materials exhibited apparent densities ranging from 375 to 630 kg/m3 and compressive strengths between 0.95 and 3.25 MPa. The developed ceramoperlite materials containing wollastonite binder can be used as high-temperature thermal insulation up to +900°C, while ceramovermiculite can be used up to +1050°C. According to a range of physicomechanical and thermophysical properties, the materials obtained are comparable to or exceed the performance of known analogs. [ABSTRACT FROM AUTHOR]

Neutron and X-ray computed tomography (NCT and XCT, respectively) are imaging techniques that are increasingly applied in geomechanics research. They are used to non-destructively reveal different microstructural aspects of geomaterials: XCT is often used to observe/quantify differences in density or porosity, while NCT reveals the presence and distribution of hydrogenous materials such as water. The correlated use of NCT and XCT for geomechanics and geotechnics research is in its infancy. To this date, very few experiments have been carried out that combine both techniques, and none has been used to investigate geomaterial–structure interaction. This paper presents the first correlative NCT–XCT imaging study of pile installation. A scaled model pile was installed in an unsaturated intact chalk cylinder and in situ NCT and ex-situ XCT synchrotron-based imaging was applied consecutively. Chalk was used because the behaviour of displacement piles installed in this material is still subject to considerable uncertainty. Results reveal for the first time the interaction between installation-induced changes in chalk density and water distribution variations, with evidence of water displacement into the densified material in the vicinity of the installed pile. A straightforward method for correlative bulk density–moisture content determination from NCT–XCT images of geomaterials is presented and their limitations are discussed. [ABSTRACT FROM AUTHOR]

Subduction zones serve as carbon recycling centers, where vast amassments of geologic carbon accrete or subduct through thermogenic gas windows over millions of years. We focus on New Zealand's Chatham Rise, a fossilized accretionary wedge remnant of the ∼400 Myr‐active East Gondwanan margin. We undertake an amplitude‐variation‐with‐offset (AVO)‐based seismic analysis of the abiogenic Mesozoic sedimentary sequence (MES) and overlying Sequence Y chalk interval, which span the Chatham Rise's northwestern slope. Two‐term AVO attribute analysis resulted in the interpretation of distinct AVO Class III–IV reflection anomalies, which demarcate the siliciclastic MES from overlying Sequence Y chalks. Unified through their strong negative intercept amplitudes, Class III anomalies increase in absolute amplitude with angle, while Class IV anomalies decrease in absolute amplitude with angle of incidence. Simultaneous AVO inversion of seismic data highlighted the presence of P‐impedance anomalies, which directly underlie the regionally occurring Sequence Y chalk interval. Class III anomalies are modeled and interpreted as the result of a previously undefined coarse‐grained lithofacies, bearing low saturations (2%–10%) of free gas. Co‐occurring ClassIV AVO anomalies are modeled to provide evidence for a fine‐grained upper MES, bearing similarly low saturations of free‐gas in pore space. We speculate on the gas' origin, which could be from the Hikurangi subduction margin, in situ ancient microbial activity, or a new undetermined source related to the ancient East Gondwanan subduction margin and accretionary wedge. Plain Language Summary: Active subduction zones (aka subduction margins) are globally occurring zones of geologic interest, defined by the subduction of one tectonic plate under another. Subduction margins host vast amassments of geologically bound carbon, which eventually subducts or accretes to the overriding plate. Carbon amassment and subsequent gaseous carbon‐escape (e.g., methane escape) from subduction zones into the Earth's exosphere necessitate an understanding of the dominant sources of gas generation within a subduction zone. Here, we present a seismic reflection‐based study of the northwestern Chatham Rise, which is a fossil remnant of the ancient East Gondwanan subduction zone. We provide seismic evidence for a previously undetected deep accumulation of carbon‐bearing free gas over a large area ∼50 km east of the active Hikurangi subduction margin. This gas appears trapped beneath a known sealing sediment layer consisting of chalk and mudstone, which is being subducted further to the west. We speculate on the locus of these gases and how they may be related to ancient East Gondwanan subduction or active Hikurangi subduction processes. Key Points: Amplitude versus offset analysis highlights a deep free‐gas accumulation on the northwestern Chatham Rise, east of the Hikurangi marginFree‐gas accumulation occurs within host strata, which are modeled to be spatially variable in lithologyFree‐gas is speculated to have multiple potential sources, from ancient microbial activity to beneath the ancient Gondwanan accretionary wedge [ABSTRACT FROM AUTHOR]

Abstract—The possibility of synthesizing inorganic thermofoam silicate vitrified materials from technogenic and natural raw materials has been studied and substantiated. Compositions and modes for obtaining quality products have been selected. On the basis of microsilica and nepheline concentrate with the addition of chalk and gypsum, thermofoam silicates with a density of 0.49–0.52 g/cm3, a strength of 2.7–3.10 MPa, a reduced thermal conductivity of 0.059–0.062 W/(m K), and a water absorption of 12–18% have been synthesized. [ABSTRACT FROM AUTHOR]

The continuous rise in hydrocarbon demand, the production decline in conventional oilfields, and the remarkable improvement in extraction methods have allowed the hydrocarbon industry and subsequently, geoscientists, to turn to studies on both unconventional and mature fields with untapped potential. In such reservoirs, the application of advanced drilling, completion, and production techniques must be preceded by the identification of permeable stratigraphic intervals that favour commercial exploitation. Accordingly, bioturbated deposits can play a key role in providing permeable pathways for enhanced production. Herein, we analyse the effects of bioturbation on the porosity and permeability of the Buda Formation, a highly bioturbated, tight (low-porosity matrix) Upper Cretaceous chalk reservoir from the Texas Gulf Coast Basin, which has been commercially exploited because of the occurrence of natural fractures. Our results show that (in addition to the natural fractures) burrows (and borings) substantially increased the porosity and permeability of this formation, thus, potentially contributing to enhanced hydrocarbon (or groundwater) storage and production. These biogenic structures might also have favoured the development of natural fractures and stylolites in the Buda Formation. However, further studies are required to prove this hypothesis. [ABSTRACT FROM AUTHOR]

Oxygen concentration in the ocean is vital for sustaining marine ecosystems. While the potential impacts of deoxygenation on modern oceans are hard to predict, lessons can be learned from better characterizing past geological intervals formed under a greenhouse climate. The greenhouse Cretaceous containing several oceanic anoxic events characterized by widespread oxygen‐deficient water is ideal in this regard. The Austin Chalk Group in south Texas (USA) shows organic‐rich intervals that can be linked to oxygen depletion in the ocean, but the exact bottom water oxygenation conditions have not been estimated. This study aims to reconstruct both sediment interstitial and bottom water oxygenation history during Austin Chalk Group deposition by integrating detailed ichnological, sedimentological and geochemical (X‐ray fluorescence and X‐ray diffraction) analyses, thereby providing a consistent model that may be applicable across a range of marine shelf settings. The 141.12 m Gise #1 core contains a continuous record of the Austin Chalk Group, providing an opportunity for unravelling oxygenation and deoxygenation events. Whereas the anaerobic–exaerobic deposits are essentially nonbioturbated, four oxygen‐related ichnocoenoses are defined, further refining the transition of aerobic to dysaerobic conditions in the sediment interstitial water. Omission surfaces and glauconitic grains, products of current‐induced scouring and condensation, suggest sporadic high‐energy events in the Austin Chalk Group ramp that drove elevated terrestrial inputs. Geochemical data further help to identify anoxic bottom water conditions within the anaerobic facies. Additionally, the lowermost part of the Austin Chalk Group illustrates redox cycles, whereas dilution events characterized by elevated terrestrial input are identified throughout the rest of the Austin Chalk Group. The evolution of oxygenation levels in sediment interstitial water and bottom water disputes the existence of a long‐lasting oxygen‐deficient sea in south Texas. The refined depositional model may be applicable to coeval shelfal settings. Moreover, the results provide insights into variable, evolving palaeoclimatic and palaeoceanographic conditions of the greenhouse Late Cretaceous. [ABSTRACT FROM AUTHOR]

Spontaneous water imbibition into matrix blocks can be a significant oil recovery mechanism in fractured reservoirs. Many enhanced oil recovery methods, such as injection of modified salinity brine, are proposed for improving spontaneous imbibition efficacy. Many scaling equations are developed in the literature to predict spontaneous imbibition oil recovery. However, almost none of them included the impact of the diversity in ionic composition of injected and connate brines and the blending/interaction of a low salinity imbibing brine with a higher salinity connate brine. In this research, these two issues are included to propose new scaling equations for the scaling of spontaneous imbibition oil recovery by modified salinity imbibing brines. This study uses experimental data of the spontaneous imbibition of modified salinity brines into oil-saturated rock samples with different lithologies containing an irreducible high salinity connate brine. The collected tests from the literature were performed at high temperatures and on aged altered wettability cores. The results of 110 available spontaneous imbibition laboratory experiments (85, 12 and 13 tests on chalks, dolomites and sandstones, respectively) are gathered. This research initially shows the poor ability of three selected convenient scaling equations from the literature to scale imbibition recovery by modified salinity brine. Then, our newly proposed technique to find the scaling equation for spontaneous imbibition recovery by modified salinity brine, during the abovementioned conditions in limestones (Bassir et al. in J Pet Explor Prod Technol 13(1): 79–99, 2023. https://doi.org/10.1007/s13202-022-01537-7) is used in chalks, dolomites and sandstones to develop the three new scaling equations. Finally, a new general equation to scale imbibition recovery by modified salinity brine for all four lithologies is presented. Moreover, for each of the four datasets (chalk, dolomite, sandstone and all the four lithologies), the scaled data by the new equations is matched by two mathematical expressions based on the Aronofsky et al. model and the Fries and Dreyer model. These mathematical expressions can be used to develop transfer functions in reservoir simulators for a more accurate prediction of oil recovery by spontaneous imbibition of modified salinity brine in fractured reservoirs. [ABSTRACT FROM AUTHOR]

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The results of studies on the effect of fillers—calcium carbonate of the MTD-2 and Omyakarb 3T brands—on the physical and mechanical properties as well as viscosity of uncured sealants based on low-molecular-weight polyethylene are presented. The optimum composition of the sealing composition is found. The composition of the sealing material is safe upon contact with human skin, which makes it possible to manually apply it when assembling structures. Sealants of such a type are applied for temporary sealing upon assembling structures in mechanical engineering and in the production of chilling equipment. [ABSTRACT FROM AUTHOR]

This paper reports the cyclic behaviour of chalk, which has yet to be studied comprehensively. Multiple undrained high-resolution cyclic triaxial experiments on low- to medium-density intact chalk, along with index and monotonic reference tests, define the conditions under which either thousands of cycles could be applied without any deleterious effect, or failure could be provoked under specified numbers of cycles. Intact chalk's response is shown to differ from that of most saturated soils tested under comparable conditions. While chalk can be reduced to putty by severe two-way displacement-controlled cycling, its behaviour proved stable and nearly linear visco-elastic over much of the one-way, stress-controlled loading space examined, with stiffness improving over thousands of cycles, without loss of undrained shear strength. However, in cases where cyclic failure occurred, the specimens showed little sign of cyclic damage before cracking and movements on discontinuities led to sharp pore pressure reductions, non-uniform displacements and the onset of brittle collapse. Chalk's behaviour resembles the fatigue response of metals, concretes and rocks, where micro-shearing or cracking initiates on imperfections that generate stress concentrations; the experiments identify the key features that must be captured in any representative cyclic loading model. [ABSTRACT FROM AUTHOR]

Comprehensive field investigations into the axial cyclic loading behaviour of open steel pipe piles driven and aged in low-to-medium-density chalk identify the conditions under which behaviour is stable, unstable or metastable. Post-cycling monotonic tests confirmed that stable cycling enhanced pile capacity marginally, while unstable cases suffered potentially large losses of shaft capacity. Metastable conditions led to intermediate outcomes. The patterns by which axial deflections grew under cyclic loading varied systematically with the normalised loading parameters and could be captured by simple fitting expressions. Cyclic stiffnesses also varied with loading conditions, with the highest operational shear stiffnesses falling far below the in situ seismic test values. The monotonic and cyclic axial responses of the test piles were controlled by the behaviour of, and conditions within, the reconsolidated, de-structured, chalk putty annuli formed around pile shafts during driving. Fibre-optic strain gauges identified progressive failure from the pile tip upwards. Large factors of safety were required for piles to survive repetitive loading under high-level, two-way conditions involving low mean loads, while low-amplitude one-way cycling had little impact. A simple 'global' prediction procedure employing interface shear and cyclic triaxial tests is shown to provide broadly representative predictions for field behaviour. [ABSTRACT FROM AUTHOR]

This paper describes research into the poorly understood axial behaviour of piles driven in chalk. Comprehensive dynamic and monotonic axial testing on 27, mostly instrumented, piles undertaken for the ALPACA joint industry projects is reported and interpreted covering: diameters between 139 mm and 1·8 m; lengths from 3 to 18 m; different pile material types; tip and groundwater conditions; and ages after driving. The experiments show the factors that influence resistance most strongly are: (a) pile end conditions; (b) slenderness ratio and flexibility; (c) shaft material; (d) age after driving; (e) relative water table depth; and (f) whether loading is compressive or tensile. Varying the factors systematically identified a remarkable average long-term shaft resistance range from below 11 kPa to more than 200 kPa for piles driven at the same low- to medium-density chalk test site in Kent (UK). Dynamic and static analyses demonstrate that soil resistances to driving were generally well predicted by the Chalk ICP-18 short-term formulation. Considering the piles' long-term behaviour, the Chalk ICP-18 approach over-predicted capacity, while the widely used CIRIA approach proved over-conservative for most cases. The research enabled the development of a revised 'ALPACA-SNW' long-term capacity assessment method that matches the test outcomes far more faithfully. [ABSTRACT FROM AUTHOR]

Low-to-medium-density chalk can be destructured to soft putty by high-pressure compression, dynamic impact or large-strain repetitive shearing. These process all occur during pile driving and affect subsequent static and cyclic load-carrying capacities. This paper reports undrained triaxial experiments on destructured chalk, which show distinctly time-dependent behaviour as well as highly non-linear stiffness, well-defined phase transformation and stable ultimate critical states under monotonic loading. The chalk's response to high-level undrained cyclic loading invokes both contractive and dilative phases that lead to pore pressure build-up, leftward effective stress path drift, permanent strain accumulation, cyclic stiffness losses and increasing damping ratios that resemble those of silts. These outcomes are relatively insensitive to consolidation pressures and are distinctly different to those of the parent intact chalk. The maximum number of cycles that can be sustained under given combinations of mean and cyclic stresses are expressed in an interactive stress diagram which also identifies conditions under which cycling has no deleterious effect. Empirical correlations are proposed to predict the number of cycles to failure and mean effective stress drift trends under the most critical cyclic conditions. Specimens that survive long-term cycling present higher post-cyclic stiffnesses and shear strengths than equivalent 'virgin' specimens. [ABSTRACT FROM AUTHOR]

Low- to medium-density chalk at St Nicholas at Wade, UK, is characterised by intensive testing to inform the interpretation of axial and lateral tests on driven piles. The chalk destructures when taken to large strains, especially under dynamic loading, leading to remarkably high pore pressures beneath penetrating cone penetration testing and driven pile tips, weak putty annuli around their shafts and degraded responses in full-displacement pressure-meter tests. Laboratory tests on carefully formed specimens explore the chalk's unstable structure and markedly time- and rate-dependent mechanical behaviour. A clear hierarchy is found between profiles of peak strength with depth of Brazilian tension, drained and undrained triaxial and direct simple shear tests conducted from in situ stress conditions. Highly instrumented triaxial tests reveal the chalk's unusual effective stress paths, markedly brittle failure behaviour from small strains and the effects of consolidating to higher than in situ stresses. The chalk's mainly sub-vertical jointing and micro-fissuring lead to properties depending on specimen scale, with in situ mass stiffnesses falling significantly below high-quality laboratory measurements and vertical Young's moduli exceeding horizontal stiffnesses. While compressive strength and stiffness appear relatively insensitive to effective stress levels, consolidation to higher pressures closes micro-fissures, increases stiffness and reduces anisotropy. [ABSTRACT FROM AUTHOR]

Raw earth bricks made from the soil of the Chalky Champagne region (France) have been used for at least two millennia in construction, a promising heritage in the context of reducing the carbon emissions of buildings. The present experimental study aims to measure the physical, mechanical, thermal, and hydric properties of adobes collected from a local village barn. The results show a high chalk content, estimated at 71%, and a clay content, acting as a binder, of 14%. Despite limited load-bearing capacity, these lightweight adobes are suitable for current single-story constructions, while their hydrothermal properties classify them as excellent moisture regulators for occupants. In association with other bio-sourced materials such as starch–beet pulp bricks, Chalky Champagne adobes yield promising insulating properties, and meet the criteria defined by current energy standards. [ABSTRACT FROM AUTHOR]

Elevated fine sediment accumulation in a river system's gravel bed is known to cause detrimental ecological impacts. Current sediment targets and approaches to mitigation have failed due to the oversimplification of geomorphological processes controlling fine sediment accumulation and the lack of relevant scientific knowledge underpinning them. This is particularly apparent in chalk streams (groundwater‐dominated systems) which regularly exhibit high rates of sediment accumulation despite low suspended sediment yields. A necessary first step is to better characterise their sedimentology; thus, the novelty of this study was to determine the sedimentological characteristics of chalk stream gravel beds, specifically the quantity and distribution of fine sediment with depth. We collated published and unpublished freeze‐core data, encompassing 90 sites across 11 UK chalk streams. Results showed average quantities of fine sediment (<2 mm) in chalk stream gravel beds were 25% by weight, with >75% of beds exceeding thresholds for ecological degradation. Quantities of fine sediment increased with increasing depth into the bed, with an average increase between surface and subsurface layers of 54%, and 89% of the gravel bed over‐saturated with fine sediment. Regional differences were attributed to differences in stream power and local sediment sources, including surficial geology and catchment land use. Additionally, a major contrast was identified between experimental conditions in flume studies used to establish models describing interactions/mechanisms of fine sediment infiltration into immobile gravel beds and the natural conditions observed in chalk streams. As such, the use of such models as a basis to explore sediment management scenarios is unlikely to predict the outcome of such management techniques correctly in a real‐world situation. [ABSTRACT FROM AUTHOR]

A plume-scale mass balance is developed to assess the natural attenuation (NA) of dissolved organic contaminants in fractured, dual-porosity aquifers. This methodology can be used to evaluate contaminant distribution within the aquifer, plume source term, contaminant biodegradation and plume status. The approach is illustrated for a site on the UK Upper Chalk aquifer impacted by petroleum fuel containing methyl tert-butyl ether (MTBE) and tert-amyl methyl ether (TAME). Variability in site investigation data and uncertainty in the mass balance were assessed using probabilistic analysis. The analysis shows that benzene, toluene, m/p-xylene and o-xylene (BTEX) compounds are biodegraded primarily by denitrification and sulfate reduction in the aquifer, with an equivalent plume-scale first-order biodegradation rate of 0.49 a−1. Other biodegradation processes are less important. Sorption contributes to hydrocarbon attenuation in the aquifer but is less important for MTBE and TAME. Uncertainty in the plume source term and site hydrogeological parameters had the greatest effect on the mass balance. The probabilistic analysis enabled the most likely long-term composition of the plume source term to be deduced and provided a site-specific estimate of contaminant mass flux for the prediction of plume development. The mass balance methodology provides a novel approach to improve NA assessments for petroleum hydrocarbons and other organic contaminants in these aquifer settings. Supplementary material: Plume organic chemistry, aquifer hydraulic conductivity and probability distribution functions used for mass balance inputs are available at https://doi.org/10.6084/m9.figshare.c.7016429 Thematic collection: This article is part of the Monitoring the aquifers collection available at: https://www.lyellcollection.org/topic/collections/monitoring-the-aquifers [ABSTRACT FROM AUTHOR]

Abnormal and excessive desire to smell certain odors or objects (desiderosmia) is reported to be seen with iron deficiency anemia. We present here four cases of desiderosmia in diagnosed patients of major depressive disorder without iron deficiency, where treatment of depression was associated with improvement in abnormal craving.

Abstract Spontaneous water imbibition into matrix blocks can be a significant oil recovery mechanism in fractured reservoirs. Many enhanced oil recovery methods, such as injection of modified salinity brine, are proposed for improving spontaneous imbibition efficacy. Many scaling equations are developed in the literature to predict spontaneous imbibition oil recovery. However, almost none of them included the impact of the diversity in ionic composition of injected and connate brines and the blending/interaction of a low salinity imbibing brine with a higher salinity connate brine. In this research, these two issues are included to propose new scaling equations for the scaling of spontaneous imbibition oil recovery by modified salinity imbibing brines. This study uses experimental data of the spontaneous imbibition of modified salinity brines into oil-saturated rock samples with different lithologies containing an irreducible high salinity connate brine. The collected tests from the literature were performed at high temperatures and on aged altered wettability cores. The results of 110 available spontaneous imbibition laboratory experiments (85, 12 and 13 tests on chalks, dolomites and sandstones, respectively) are gathered. This research initially shows the poor ability of three selected convenient scaling equations from the literature to scale imbibition recovery by modified salinity brine. Then, our newly proposed technique to find the scaling equation for spontaneous imbibition recovery by modified salinity brine, during the abovementioned conditions in limestones (Bassir et al. in J Pet Explor Prod Technol 13(1): 79–99, 2023. https://doi.org/10.1007/s13202-022-01537-7 ) is used in chalks, dolomites and sandstones to develop the three new scaling equations. Finally, a new general equation to scale imbibition recovery by modified salinity brine for all four lithologies is presented. Moreover, for each of the four datasets (chalk, dolomite, sandstone and all the four lithologies), the scaled data by the new equations is matched by two mathematical expressions based on the Aronofsky et al. model and the Fries and Dreyer model. These mathematical expressions can be used to develop transfer functions in reservoir simulators for a more accurate prediction of oil recovery by spontaneous imbibition of modified salinity brine in fractured reservoirs.

Abstract Diammonium phosphate (DAP) has been proven effective in improving the stiffness of weak or acid-damaged carbonates, thereby preserving hydraulic fracture conductivity. The reaction between DAP and calcite in chalk formations primarily produces hydroxyapatite (HAP), which is stiffer than calcite. However, the optimal reaction outcomes vary greatly with factors such as DAP concentration and reaction conditions. This study investigated the DAP-calcite reaction duration, pressure, and temperature effects on the stiffness magnitude of soft Austin chalk. Also, the catalyst effect and depth of HAP formation were examined. The study involved the assessment of stiffness non-destructively (impulse hammering), mineralogy (XRD, SEM), and elemental composition (XRF). The study tested 15 different DAP-chalk reaction variations, where the pressure, temperature, aging time and catalyst addition were modified in each case. The samples' elastic stiffness distributions were then collected and compared to the pre-reaction ones. The results showed that the elastic stiffness increased in all treated samples, with an 181% maximum increase achieved after 72 h at 6.9 MPa and 75 °C. However, the pressure effect was minor compared to the temperature. The SEM images revealed different HAP morphology corresponding to different treatment conditions. Although the treated samples showed an increased intensity of phosphorus throughout the entire sample, the near-surface zone (4–6 mm) was the most affected, as inferred from the XRF elemental analysis. The study's findings can help optimize hydraulic fracturing operations in weak carbonate reservoirs, improving production rates and overall well performance.

In the production of compound feeds, it is necessary to follow the recipe at the time of introducing all the necessary components, for which various types of dispensers are used. Currently, automatic dosing systems are widely used, providing increased dosing accuracy. However, individual settings of such systems are required for each component, which makes the work of operators harder. The article describes the design of a technical device containing a main and an additional screw and allowing components with different physical and mechanical properties to be weighed at the same tuning parameters. A brief description of the dispenser's workflow is given, the research factors and criteria for evaluating its work are listed. The influence of five factors was determined: the frequency setpoint of the dispensers n1, the pre-filling setpoint m, the setpoint for switching on the filling speed t, the frequency setpoint of the dispensers n2, the set weight of the suspension MZ on the dosing accuracy. At the first stage, the influence of the studied factors on grain dosing was determined. To do this, the Box-Benkin plan was implemented for five factors. As a result of the analysis of the data obtained, a regression model was built, on the basis of which three combinations of factor values were determined, in which the grain dosing error by an additional dispenser screw was 0. At the next stage of the research, the accuracy of dosing chalk and salt was determined at the established combinations. It was revealed that salt dosing was carried out according to a pattern close to the grain curve, and the dosing error was within the permissible limits of 5%. As a result of the conducted studies, the best combination of factors was determined, in which the dosing error did not exceed the permissible value when weighing grain, salt and chalk: n1 = 30.3 Hz, t = 11.9 %; n2 = 40.9 % of n1 (12.42 Hz), MZ = 202.8 g. With these values of the studied parameters, it is possible to dose components with the permissible error of the weight of the suspension is over 200 g.

PVC items (38% carbon atoms w/w) are environmentally friendly as, unlike polyolefins (86% carbon atoms w/w), they are mainly based on chlorine, one of the most abundant elements on Earth and, so, less based on fossil resources. However, in the eco-design context, articles' durability plays a crucial role, contributing to the enhancement of their sustainability. In this framework, the research on additives capable of increasing the weatherability of outdoor articles is essential. The theory section of the paper reviews the mechanisms of weathering that lead to PVC degradation and undermine the durability of items such as window frames or roller shutters. The weathering of PVC items is a complex phenomenon, involving photo-chemical and secondary chemical reactions, that yields the formation of conjugated polyene sequences underskin in the absence of oxygen and carbonyls in the surface. Here, the chain scission of the polymer backbone occurs, bringing about the disintegration of the surface of the item and causing the typical discoloration called chalking, especially evident in dark-colored articles. In the experimental section of the paper, the effect of different acid scavengers on item weathering has been studied using a natural outdoor and two accelerated exposures with xenon-arc and Q-UV testing devices. Results confirm that some acid scavengers are efficient in preventing chalking, but some are ineffective or even detrimental. Thus, the PVC formulations of durable articles upon weathering still depend on a complex choice of the appropriate ingredients, and several outdoor and indoor accelerated-weathering tests are needed to predict the articles' lifetime. [ABSTRACT FROM AUTHOR]

Bottom current activity has been responsible for the formation of a multitude of erosional and depositional features recorded in chalk. Advanced knowledge on the mobility and transport of unlithified calcareous nannofossil ooze by bottom currents is increasingly important not only for understanding the deposition of ancient chalk, but also for modelling the behaviour of modern pelagic carbonate sediments. Whereas the erosional behaviour of very pure calcareous nannofossil ooze has recently been investigated, the effect of organic matter and clay minerals on the erosional behaviour of calcareous nannofossil ooze is as yet unquantified. The results of the present study are based on laboratory flume studies utilizing chalk ooze with varying concentrations of smectite clay (1 to 30 wt.%), two types of organic matter and bed porosity. Phytoplankton (Pavlova lutheri) was used as a proxy for particulate marine organic matter, and xanthan gum as a proxy for extracellular polymeric substances. The results show a significant decrease in nannofossil ooze mobility with increasing content of clay or marine organic matter. Organic matter is found to reduce erodibility at much lower concentrations than clay minerals at porosities equivalent to those of the seafloor. At lower porosities, corresponding to some depth below the seafloor, organic matter and clay minerals are less effective in bed stabilization. This suggests that clay minerals and especially organic matter will affect the likelihood of initiation of severe erosion on the seafloor, whereas their inhibiting effect will decrease as erosion scours progressively deeper into the sediment column. The effect of extracellular polymeric substances is more complex than marine organic matter, probably due to detachment of large aggregates from the bed and resulting increase in bed roughness. The choice of organic matter in sedimentological experiments may lead to significant differences in sediment behaviour and should therefore involve careful consideration. [ABSTRACT FROM AUTHOR]

We explored the impact of the emotions of nonnative English-language teachers on their pedagogical practices, accounting for the mediating role of emotional intelligence. We used a quantitative research method and collected data from 134 nonnative English-language teachers working at 16 educational institutes in China. The hypotheses were tested by analyzing all data using SmartPLS software. The results indicated that nonnative English-language teachers' emotions had a significant impact on their pedagogical practices, with emotional intelligence mediating this relationship. The study findings have implications for teacher education programs, which should focus on developing emotional intelligence skills among teachers to enhance their pedagogical practices. Further, targeted professional development programs will help teachers to manage their emotions and improve their teaching effectiveness. [ABSTRACT FROM AUTHOR]

This study uses data from the sixth national quinquennial survey on teaching and assessment methods in economics, also known as the "chalk and talk" survey, to examine, for the first time, how instructor, departmental, and institutional characteristics may contribute to the use of references to diversity, inclusion, and gender issues in undergraduate economics courses. Findings suggest that undergraduate students are differently exposed to these issues depending on the characteristics of the instructors, departments, and institutions. Our work provides a baseline for supporting targeted interventions to increase the use of issues related to diversity, inclusion, and gender in the economics classroom. [ABSTRACT FROM AUTHOR]

The correlation of the Coniacian and Santonian chalks of the Anglo-Paris Basin is described on the basis of detailed lithological logs and extensive records of macrofossils and microcrinoids. In the almost complete absence of ammonites, inoceramid bivalves afford the highest resolution correlation of these stages in chalks, but their value here is limited by the absence of key genera and species, most notably in the Upper Coniacian and middle and Upper Santonian. Echinoids and other macrofossils (brachiopods, stalked crinoids, belemnites) have proved useful, but many are long-ranging or uncommon. Some marker beds, including flints and marl seams, provide useful correlations across the basin, but are locally absent. For the Upper Santonian, the stemless benthonic crinoids Uintacrinus and Marsupites provide high-resolution correlation, both within the basin and to other regions. The successions on the basin margins, in the far north of France (Nord, Pas de Calais) and the southwest (Touraine) are condensed and yield ammonites in association with important inoceramid species. The controls on sedimentation caused by sea-level changes are evaluated on a basinal and global scale, most especially for the Upper Santonian. [ABSTRACT FROM AUTHOR]

Copyright of Revue Française de Géotechnique is the property of EDP Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Elastic wave velocities of compressional and shear waves propagating through sedimentary rocks are often coupled with information of bulk density to derive the rock stiffness. Acquiring the transit time of compressional and shear waves often involves manual picking of wave arrival times from wave trains recorded in the laboratory or by well‐logging tools. Picking the compressional wave arrival time is commonly accepted as straightforward. Oppositely, detecting the shear wave arrival and picking its arrival time is often troublesome because the transmitted shear wave partly converts to compressional waves and back to a secondary shear wave, concealing the transmitted shear wave arrival in the wave train. In laboratory settings, we illustrate the difficulty of shear wave detection in wave trains recorded on highly porous chalk plug samples from the Danish North Sea Basin. Wave trains were recorded on plugs dry, Tap‐water or Isopar‐L saturated during uniaxial strain compaction. The recorded shear wave trains showed two distinct features, which could be interpreted as the transmitted shear wave first arrival; we denoted them as early and late arrivals. However, as only one feature can mark the arrival of the transmitted shear wave, we propose a semi‐empirical disclosure strategy combining a graphical representation of stacked wave trains with rock physical modelling. By stacking recorded wave trains in a graphical strain–time–amplitude domain, we demonstrate that an early shear wave feature marks a converted shear to compressional to shear wave and not the transmitted shear wave. We used physical modelling to identify early shear wave features and illustrate the consequences of adopting a falsely interpreted shear wave on stiffness properties. [ABSTRACT FROM AUTHOR]

The understanding of silicate weathering and its role as a sink for atmospheric CO2 is important to get a better insight into how the Earth shifts from warm to cool climates. The lithium isotope composition (δ7Li) of marine carbonates can be used as a proxy to track the past chemical weathering of silicates. A high‐resolution δ7Li record would be helpful to evaluate the role of silicate weathering during the late Cretaceous climate cooling. Here, we assess chalk as a potential archive for reconstructing Late Cretaceous seawater Li isotope composition by comparing Maastrichtian chalk from Northern Germany (Hemmoor, Kronsmoor) to a Quaternary coccolith ooze from the Manihiki Plateau (Pacific Ocean) as a lithological analog to modern conditions. We observe a negative offset of 3.9 ± 0.6‰ for the coccolith ooze relative to the modern seawater Li isotope composition (+31.1 ± 0.3‰; 2SE; n = 54), a value that falls in the range of published offsets for modern core‐top samples and for brachiopod calcite. Further, the negative offset between the Li isotope compositions of Manihiki coccolith ooze and modern planktonic foraminifera is 2.3 ± 0.6‰. Although chalk represents a diagenetically altered modification of pelagic nannofossil ooze, manifested by changes in the composition of trace elements, we observe a consistent offset of Li isotope data between Maastrichtian chalk and Maastrichtian planktonic foraminiferal data (−1.4 ± 0. 5‰) that lies within the uncertainty of modern values. We therefore suggest that chalk can be used as a reliable archive for δ7Li reconstructions. Key Points: Chalk is a reliable archive for the Li isotope composition of seawaterCoccolith ooze has a negative offset of 3.9 ± 0.6‰ from modern seawater for Li isotope ratiosThe estimated mean value for the late Maastrichtian seawater Li isotope composition is +27.5 ± 1.0‰ [ABSTRACT FROM AUTHOR]

Improving low flows in Chalk streams by relocating groundwater abstraction further downstream is an idea that has become popular in the UK in recent years. Simulations using the Environment Agency's Hertfordshire Chalk Groundwater Model predict that reducing groundwater abstraction close to ephemeral or intermittent Chalk streams is more likely to increase river flows during high-flow conditions than during low flows. This finding helps to explain the apparent lack of observed benefit to river flows during drought periods in catchments where abstractions have been reduced. If abstraction reductions are predicted to result in more of an increase to high river flows than to low flows, they may risk contributing to increased flood likelihood downstream, without providing significant habitat protection during low flows. Conversely, it has also been found that, under certain circumstances, preferential benefits can be predicted for low flows. Simulations show that such benefits are most likely to manifest by relocating abstraction to downstream locations where groundwater levels are already below the base of the riverbed (e.g. due to existing abstraction or artificial channel modifications). Here, the varying degree of hydraulic connection between groundwater and river can result in preferential benefits to downstream low flows and reduced downstream flood risk. Thematic collection: This article is part of the Karst: Characterization, Hazards & Hydrogeology collection available at: https://www.lyellcollection.org/topic/collections/karst [ABSTRACT FROM AUTHOR]

Copyright of Revista de Ensino em Artes, Moda e Design is the property of Universidade do Estado de Santa Catarina and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Groundwater flow and contaminant migration tracing is a vital method of identifying and characterising pollutant source-pathway-receptor linkages in karst aquifers. Bacteriophages are an attractive alternative tracer to non-reactive fluorescent dye tracers, as high titres (>1012 pfu mL−1) can be safely released into the aquifer, offering improved tracer detectability. However, the interpretation of bacteriophage tracer breakthrough curves is complicated as their fate and transport are impacted by aquifer physicochemical conditions. A comparative tracer migration experiment was conducted in a peri-urban catchment in southeast England to characterise the behaviour of MS2 bacteriophage relative to sodium fluorescein dye in a karstic chalk aquifer. Tracers were released into a stream sink and detected at two abstraction boreholes located 3 km and 10 km away. At both sites, the loss of MS2 phage greatly exceeded that of the solute tracer. In contrast, the qualitative shape of the dye and phage breakthrough curves were visually very similar, suggesting that the bacteriophage arriving at each site was governed by comparable transport parameters to the non-reactive dye tracer. The colloid filtration theory was applied to explain the apparent contradiction of comparable tracer breakthrough patterns despite massive phage losses in the subsurface. One-dimensional transport models were also fitted to each breakthrough curve to facilitate a quantitative comparison of the transport parameter values. The model results suggest that the bacteriophage migrates through the conduit system slightly faster than the fluorescent dye, but that the former is significantly less dispersed. These results suggest that whilst the bacteriophage tracer cannot be used to predict receptor concentrations from transport via karstic flow paths, it can provide estimates for groundwater flow and solute contaminant transit times. This study also provides insight into the attenuation and transport of pathogenic viruses in karstic chalk aquifers. [ABSTRACT FROM AUTHOR]

Abnormal and excessive desire to smell certain odors or objects (desiderosmia) is reported to be seen with iron deficiency anemia. We present here four cases of desiderosmia in diagnosed patients of major depressive disorder without iron deficiency, where treatment of depression was associated with improvement in abnormal craving. [ABSTRACT FROM AUTHOR]

Source-to-sink sedimentary systems associated with volcanic rifted margins serve as important archives for basin development by recording lithospheric changes affecting the depositional systems. Distinguishing between sediment transport processes and their sediment source(s) can guide the interpretation of a basin's history, and thereby inform regional paleogeographic reconstructions. In this contribution, we integrate and utilize wireline geophysical logs, detailed petrographic observations from side-wall cores, and seismic analysis to describe and decipher a Maastrichtian to Danian-aged basin-floor depositional system in the deep outer Møre Basin, mid-Norwegian margin. Well 6302/6-1 (Tulipan) is a spatially isolated borehole drilled in 2001 that penetrates Maastrichtian and younger strata. A succession of hitherto undescribed carbonates and sandstones in the outer Møre Basin was discovered. It is investigated for sediment transport, provenance, and depositional processes on the basin floor surrounded by structural highs and ridges. The strata from the lower parts form a basin-floor apron consisting of redeposited carbonate sourced from a westerly sub-aerial high. The apron transitions vertically from mixed siliciclastic and carbonate into a purely siliciclastic fan with intercalated sandstone and mudstone, providing a rare high-resolution record of how depositional environments experience a complete shift in dominant processes. The development coincides with similar latest Cretaceous-earliest Palaeocene sequences recorded south of this region (e.g., well 219/20-1) and may have been influenced by regional uplift associated with the onset of magmatism in the Northeast Atlantic. This study improves our understanding of a late, pre-breakup source-to-sink sedimentary system developed near the breakup axis of an infant ocean, and documents what is possibly the northernmost chalk deposit in the Chalk Group. [ABSTRACT FROM AUTHOR]

Unique soils of the chalk polygons in the steppe zone of Obshchii Syrt and the Sub-Ural Plateau have been studied. They are characterized by a combination of uneven-aged features formed in contrasting environments. Modern features are the result of biogenic-accumulative processes, structuring, salinization, and crust formation. Relict features are associated with paleocryogenesis and include paleo-permafrost block–pseudomorph complexes, cryoturbations, paleo-permafrost wedges, accumulations and sorting of coarse fraction, etc. The good conservation of relict cryogenic features and modern cryogenic processes determine the uniqueness of these steppe soils. Such horizons and profile formula are not found in the existing diagnostic scheme for the classification and diagnostics of soils in Russia (CDSR). In order to represent the features, modern image, and genesis of these soils in the terminology of CDSR, a new diagnostic BCM cryostructural-metamorphic horizon was proposed. The soils were diagnosed as cryostructural-metamorphic on microhighs, protohumic and light-humus cryostructural-metamorphic on microslopes, and light-humus and light-humus cryometamorphic in microdepressions of the chalk polygons. Relict cryogenic features are proposed to be taken into account in the classification of these soils at the level of soil genus with the prefix 'paleo'. According to the WRB, soils were classified as Rendzic Endoleptic Calcaric Phaeozems (Relictiturbic, Tonguic) in microdepressions, Skeletic Calcaric Regosols (Relictiturbic, Ruptic, Nudiyermic) on microhighs, and (Relictiturbuc, Raptic, Ochric) on microslopes. [ABSTRACT FROM AUTHOR]

During primary succession, the abundance of different species and their associated plant traits change over time. Understanding how plant traits linked to colonising and competitive abilities change through succession is important for determining whether community assembly can be predicted. Examining this across more than one taxon group can reveal if these patterns are generalisable.Here, we investigated primary succession on bare chalk for a chronosequence spanning 33 years for two different taxa, vascular plants and bryophytes. We examined how abundance changed through succession, and how this related to species' colonising and competitive abilities, using relevant plant traits for each taxa. A zero‐inflated beta regression model was used to investigate the effects of traits on both presence/absence and abundance‐when‐present of vascular plants and bryophytes.Vascular plants with a larger specific leaf area were more likely to occur later in succession. Vascular plants, which were hemicryptophytes, wind dispersing and had a lower canopy height, were more likely to increase in abundance‐when‐present during succession.Bryophytes with a larger spore diameter were more likely to occur later in succession. Shorter bryophytes with a greater frequency of sporophyte production had a higher abundance early in succession, representing their high colonising abilities. Whereas later in succession larger bryophytes, with a mat or weft life form and low sporophyte frequency were more abundant, indicating a shift towards greater competitive abilities.Synthesis. This study has revealed different patterns for vascular plants and bryophytes regarding colonisation and changes in abundance through succession, and the associated traits linked to colonising and competitive abilities. Although some traits were found to influence abundance through succession for vascular plants, these were often contrary to the expected pattern representing the change from colonising to competitive abilities, whereas for bryophytes, there was more evidence for this shift with successional age. This suggests that general theories on succession‐linked plant traits should not be relied upon in isolation for the prediction of community assembly. Context, particularly successional age in relation to the available species pool is also key. [ABSTRACT FROM AUTHOR]

Stimulating carbonate reservoirs by injecting acids results in channels within the rock called wormholes. This study reveals the stability of wormholed chalk and limestone samples under high confining pressure using a triaxial cell. The experiments were conducted on four Austin chalk (AC) and four Indiana limestone (IL) core samples (1.5 inches × 3 inches). The samples were characterized by their petrophysical (i.e., porosity and permeability) and elastic properties (i.e., Young's modulus). Two of each rock type were acidized to generate wormholes using a core flooding setup. Then the samples were subjected to a high confining pressure of up to 88 MPa using a triaxial/acoustic cell. In addition, the permeability of the samples under increasing confining pressure was reported. Medical CT scan images were taken for the wormholed samples before and after subjecting them to high confining pressures. The CT scan images and rock properties were imported to COMSOL finite element to simulate the deformation under high stresses. The results revealed that wormholes closed under confining in the chalk samples while it was mechanically stable in the IL samples. This was attributed to the rigidity of limestone as compared to weak chalk samples. Fractures were observed in one of the chalk samples, while no fractures were noticed in the limestone. The finite element simulations confirmed the experimental outcomes and showed that the wormhole branches were more susceptible to deformation and closure. Highlights: Wormholes in weak carbonate rocks are subject to closure under high confining pressures Wormhole branches tend to close faster due to the higher stress concentration Permeability of the wormhole is a strong function of the confining pressure [ABSTRACT FROM AUTHOR]

This paper presents the freshwater limestones, from tenelija and (Mostar) miljevina, which are intercalated in the Mukoba deposit near Mostar, and their "stone cousins," Posušje miljevina and Tomislavgrad muljika. In the process of diagenesis they acquired a specific orientation and structure (especially tenelija), which gave them specific physical properties (small bulk density, high porosity and permeability), which "classic" limestones used in construction do not have, and which were decisive for the choice of this stone for construction of the Old Bridge and other buildings in the wider area of Mostar and in the area of Posubje municipality, but also in other karst poljes of Herzegovina and southwestern Bosnia, in parts of Central Bosnia, and Miljevina near Foča. The second part of the paper presents the so-called built-in (internal) factors that the builders try to avoid in order for freshwater limestones that are built into numerous stone buildings and/or monuments to avoid complex processes of stone changes, or weathering (decay) of stone due to its interaction with various environmental conditions (external factors). It covers the problems and significance of the choice of stone, the method and (often too small) depth of its extraction from the deposit for the construction of significant buildings, insufficiently long aging (storage) after extraction, incorrect installation (stacking) of the stone in relation to its position in the deposit, as well as various errors in stone processing and execution, along with inadequate maintenance. [ABSTRACT FROM AUTHOR]

The Buda Formation is a coccolith-rich carbonate unit deposited in lagoonal waters of the Comanche Shelf during the early Cenomanian. This unit constitutes a long-lived hydrocarbon reservoir and an important regional marker in the Texas Gulf Coast Basin. Several sedimentological and stratigraphic studies have been carried out on this formation but debates regarding its depositional conditions persist. The Buda Formation is characterized by a high degree of bioturbation intensity; however, comprehensive ichnological analyses focused on elucidating its depositional conditions have not been performed yet. Here, we report the Buda Formation ichnofauna comprising twenty ichnotaxa and widely dominated by Thalassinoides isp. and Chondrites isp. The ichnological analysis allowed us to recognize nine ichnofabrics, which reflect changing palaeoecological and palaeoenvironmental conditions during the deposition of this unit. In general, the different ichnofabric expressions throughout this formation reflect fluctuating levels of exchange of waters between the Buda lagoon and the open sea, based on the inherent changes in physicochemical parameters, such as oxygenation levels and salinity. In addition, the concept of taphonomic pathways is underscored for accuracy in palaeoecological reconstructions, as well as the need for integrating diagenetic processes, particularly when applying this concept to carbonate rocks. [ABSTRACT FROM AUTHOR]

A surrogate model of the human calvarium can be used to assess skull-fracture-related head injuries without continuously requiring post-mortem human skulls. Skull simulants developed in the literature often require sophisticated manufacturing procedures and/or materials not always practical when factoring in time or expense considerations. This study's objective was to fabricate three exploratory surrogate models (1. pure epoxy prototype, 2. epoxy-chalk mix prototype, and 3. epoxy-chalk three-layered prototype) of the calvarium to mimic the calvarium's mechanical response at fracture using readily available and cost-effective materials, specifically epoxy and chalk. The surrogates and calvaria were subject to quasi-static and dynamic impact 4-point bending and their mechanical responses were compared statistically. Under quasi-static loading, all three surrogates showed a considerable number of differences in mechanical response variables to calvaria that was deemed significant (p < 0.05). Under dynamic impact loading, there was no sufficient evidence to reject that the average mechanical response variables were equal between the epoxy-chalk three-layered prototype and calvaria (p > 0.05). This included force and bending moment at fracture, tensile strain at fracture, tensile and compressive stress at fracture, tensile modulus, and tensile strain rate. Overall, our study illustrates two main remarks: (1) the three exploratory surrogate models are potential candidates for mimicking the mechanical response of the calvarium at fracture during impact loading and (2) employing epoxy and chalk, which are readily available and cost-effective has the potential to mimic the mechanical response of calvaria in impact loading. [ABSTRACT FROM AUTHOR]

During the war active, a huge number of residential and public buildings were destroyed not only in Kharkiv and the region, but throughout Ukraine. For the restoration of destroyed buildings, new types of cement will be needed to look for and will be created decorated concretes based on them that would provide high operational and technological properties of constrictions and will be focused on local materials. Carbonate additive such as highly dispersed calcite (chalk) can be used for as local additive for concrete due to significant reserves are located in Kharkiv region. In the article research on the impact of joint action additive of highly dispersed calcite (chalk) and natural pigment (ocher) is presented by physical and mechanical properties such as density, strength, water resistance, and frost resistance. It has been established that, depending on the percentage of highly dispersed calcite (chalk), the physical and mechanical properties are changed irregularly. On the basis of the conducted researches it was established that the optimal amount of the addition of high‐fossil chalk, which provides increased frost resistance and corrosion resistance of concrete in an aggressive environment, containing chlorides, sulfates and magnesium ions, is from 10 % to 30 %. In addition, it increases density, compressive strength, stretching strength at bending. At the same time, it should be noted at an increased amount of fine chalk to 40% leads to a decrease in physical and mechanical characteristics. But the introduction of plasticizer in the amount of 0.5% leads to increased compressive strength and, accordingly, increases the positive qualities of chalk. The concrete compositions that getting with high decorative and operational properties are allowed to use them for the restoration of the city and increase in urban space. [ABSTRACT FROM AUTHOR]

Copyright of Hydrogeology Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revue Française de Géotechnique is the property of EDP Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Ceramic-vermiculite thermal insulation with a wollastonite binder was prepared from chalk, diatomite, and expanded vermiculite by means of solid-phase synthesis of the components. The influence of the granulometric composition of expanded vermiculite and the influence of the composition of the batch on the phase composition and the physicomechanical and thermophysical properties of ceramic materials were studied. The main crystalline phase of the ceramic samples is biotite and wollastonite. The developed ceramic-vermiculite thermal insulation has an apparent density 310 – 510 kg/m3 and can be operated at temperatures up to 1050°C inclusively. The developed materials can be used as fire-resistant thermal insulation for industrial furnaces, equipment, and so on. [ABSTRACT FROM AUTHOR]