Surface Stone Research Articles

Exploring the use of zwitterionic liquids for hydrogen desorption and release from calcite rock oil reservoirs. A theoretical study

A theoretical model is presented to describe the processes of release and desorption of molecular hydrogen from the depths of calcite rock oil fields via surfactants such as zwitterionic liquids. This model is based on molecular mechanics and dynamics, for which we built a supercell with a calcite crystalline unit cell in order to model the {1,0,4} surface and volume of the calcite rock; 42 H2 molecules adsorbed and interacting strongly with the calcite surface stone were analyzed in this work; the effect of crude oil is simulated with an asphaltene macromolecule model. Finally, a branched geminal zwitterionic liquid (ZL) molecule is applied to initiate the process of hydrogen desorption and release. The aqueous medium of the oil field is simulated by the dielectric constant of water. The most stable molecules were obtained using forcite computational code. While the interaction energies were calculated by classical molecular mechanics using Dreiding force field. The dynamics of the H2 desorption and release process from calcite rock of oil well is studied using the classical molecular dynamics. The purpose of the work is to theoretically demonstrate that ZL substances are capable of releasing and desorb hydrogen from the calcite surface in the depths of oil fields. The results indicate that ZL polar groups form cation-π interactions with the asphaltene benzene rings structure, and that, the carbonated chains of the former trap the latter to release molecular hydrogen. Finally, the aqueous medium desorbs hydrogen from the calcite surface and transports it to the surface of the oil field.

A new approach to pedestal differentiation for soil loss estimation—a case study from a burnt area in north-central Portugal

Soil pedestals have long been used as qualitative indicators of soil splash erosion. In rangelands, plant-capped pedestals, generally grass tussocks, have also been used to quantitatively estimate soil loss since the first half of the twentieth century. In agricultural lands, forests, and badlands, stone-capped pedestals have been used as qualitative and semi-quantitative indicators of active, ‘extreme’ erosion. Little work has been reported on using capstone pedestal data for quantifying soil loss. We postulate that three distinct capstone pedestal types may be present in any given location and that a detailed analysis of a pedestal height histogram may be used to recognize their populations. This analysis can subsequently inform if soil loss can be reliably estimated and if so, which of the existing methods using pedestal height data will provide more accurate results. The three proposed capstone pedestal types are: (1) neo-pedestals formed underneath surface stones exposed by (partial) removal of the soil surface cover; (2) endo-pedestals formed underneath stones that were buried in the soil but have been exposed by erosion; and (3) phoenix-pedestals formed underneath stones from collapsed pedestals. In the pedestal height histogram of any given location, a skew to smaller heights may indicate the existence of endo- and/or phoenix-pedestals, which may be revealed as a bi-(or tri) modal distribution when using a smaller bin size. This concept was applied to a case study where soil loss had been monitored for control plots and mulched plots during a 5-year period following wildfire in a eucalypt plantation. We measured pedestal heights and used methods to quantitatively assess soil loss from soil pedestal data in the available literature. Soil pedestal data at the end of the 5-year period under or overestimated soil loss in the control treatment, with results ranging from 60 to 115% of measured soil loss, depending on the method. It is postulated that phoenix- and endo-pedestals may be a driving factor behind the observed discrepancies. We discuss how future research may provide more insight into dominant processes, and how frequency distributions may be used to select the best methods for estimating soil loss from pedestals.

Main characteristics of burial complexes of Central Kazakhstan in the Late Bronze Age

The main factual basis of the research comprised the materials of 25 necropoleis of the Late Bronze Age examined in the Karaganda and Ulytau regions of Central Kazakhstan. The total number of the investigated burials amounts to 167 individual structures. There were 190 burials recorded. Since the 2000s, nine cemeteries belonging to the Late Bronze Age have been investigated. There were 72 burial structures studied, including one of the eight largest mausoleums in the region — Karazhar-tas, excavated in 2016–2017. All known burial structures were divided into three groups: surface stone boxes, boxes imbedded in the bedrock, and ground graves, which, according to the characteristic above-ground structures, were divided into ten types of burial structures. It has been noted that for the first group of the burials, the most characteristic are quadrangular funeral structures erected using the masonry technique. The second group is dominated by quadrangular fences built from vertically set slabs, less often from stone laid on flat. The third group is clearly dominated by a ring-shaped layout in the form of the stones selected according to their dimensions, laid in a circle. The most numerous appeared to be the first group, for which the charac-teristic feature is the arrangement of the burial chambers in the form of stone boxes raised above the ground. The less repre-sentative was the second group with subsurface burials, including those that had a form of composite stone boxes. The third group comprised the burials in ground graves. It is assumed that in the first two groups, the westward orientation of the interred is predominant, with a certain role of the northeastern sector. The third group is characterised by the invariable orientation of the deceased in a southward direction with the sleeping position of the skeleton laid on the right side.

Predictors of clinical and surgical characteristics of giant stones of the urinary bladder: a retrospective study

BackgroundGiant stones of the urinary bladder (GSBs) are rare and usually presented as case reports. We aimed to assess the clinical and surgical characteristics of GSBs and identify their predictors.MethodsA retrospective study of 74 patients with GSBs who presented between July, 2005 and June, 2020 was performed. Patients’ demographics, clinical presentations, and surgical peculiarities were studied.ResultsOlder age and male gender were risk factors for the occurrence of GSBs. The irritative lower urinary tract symptoms (iLUTS) were the main presenting symptoms (97.3%). Most patients were treated with cystolithotomy (90.1%). Univariate analyses showed that solitary (p < 0.001) and rough surface (P = 0.009) stones were significant factors for occurrence of iLUTS as the presenting symptoms. Also, the severity of symptoms (p = 0.021), rough surface (p = 0.010) and size (p < 0.001) of stones, and farmer occupation (p = 0.009) were significantly associated with adherence of the stone to the bladder mucosa at surgery. In multivariate analysis, the rough surface (p = 0.014) and solitary (p = 0.006) stones, and concomitant ureteral stones (p = 0.020) were independently associated with iLUTS as the main presentation. However, the stone size and severity of iLUTS were the independently associated factors for adherence of GSBs to the bladder mucosa.ConclusionsSolitary GSB, rough surface and the association with ureteral stones are independent risk factors for the occurrence of long-standing iLUTS. The stone size and severity of iLUTS were the independent predictors of adherence of GSBs to the bladder mucosa. Cystolithotomy is the main treatment, but it may be more difficult when there is bladder mucosa adherence.

Evaluation of database and some soil characteristic of Kumkale Agricultural Enterprise soils in GIS

General Directorate of Agricultural Enterprises (GDAE), which has been operating since 1994, is a state institution whose aim is to protect the gene resources as well as the production of seeds, breeding and raw materials for agriculture and agriculture-based industry. There are more than 30 agricultural enterprises established for similar purposes in Türkiye. One of these enterprises is Kumkale Agricultural Enterprise (KAE) located within the borders of Çanakkale province. The aim of this study is to reveal the current potentials of KAE lands, for which detailed studies have been made before, to create a database in Geographic Information System (GIS) and to produce various thematic maps. In this study, important soil characteristics such as slope, soil depth, surface stones, drainage, as well as soil series and physiographic units included in the survey report were mapped and the areas covered were calculated in GIS. With the digitization has determined that the agricultural enterprises lands in question are spread over an area of 7309 decares in total. In terms of soil series, the highest distribution area belongs to Karabatak series (948.2 da), while Alluvial soils (3094.8 da) have the highest distribution area in terms of physiographic units. In addition, most of the lands consist of 0-2% slope (4478.9 da), deeper than 120 cm (5936.8 da), stone-free (5677.2 da) and without drainage problems. As a result, it will be useful to examine both the temporal and spatial changes of the lands of GDAE, which has a significant production capacity in Türkiye, to make new field studies and compare them with the old survey studies in terms of guiding future studies.

Stones hounsfield unit value and predictors of urinary leakage after PCNL

BackgroundTo evaluate the predictive factors of urinary leakage (UL) following percutaneous nephrolithotomy (PNL) and to investigate the relationship between Hounsfield unit (HU) of stone and UL.MethodsWe retrospectively reviewed the data of 728 patients who underwent PNL between January 2012 and January 2017. In total, 396 patients were eligible for the study. Patient demographics, renal factors, stone properties and operative details were collected. The association between UL and these variables were assessed by univariate and multivariate analysis.ResultsThere was no statistically significant correlation considering age, body mass index and the presence of hypertension. The presence of diabetes mellitus (DM) was significantly correlated with UL (p < 0.001). Kidney related factors such as parenchymal thickness, hydronephrosis grade (HN), previous stone treatment, and stone related factors, such as stone surface area, stone burden, stone localization and HU value of stone, were found to affect UL status significantly (p < 0.001). Operation time, fluoroscopy time, treatment outcome, j stent use, percutenous nephrostomy (PCN) catheter stay time and the hospitalization time also had significant effect on UL (p < 0.001). Multivariable logistic analysis showed that presence of DM, parenchymal thickness, HU values, HN, operation time, j stent use, and PCN catheter stay time are independently related with UL following PCNL. Moreover, we determined a HU cut-off value of 933 with ROC analysis, which demostrated 84.9% sensitivity and 67.1% specificity for predicting UL.ConclusionThis study has shown that we are more likely to encounter postoperative UL in stones with higher HU values. Therefore, we suggest clinicians to inform patients with this type of kidney stones about the probable complication of UL.

Area Noise Assessment at Surface Stone, Sand, and Gravel Mines: Application for Reducing Worker Noise Exposure.

Repeated noise exposure and occupational hearing loss are common health problems across industries and especially within the mining industry. Large mechanized processes, blasting, grinding, drilling, and work that is often in close quarters put many miners at an increased risk of noise overexposure. In stone, sand, and gravel mining, noise is generated from a variety of sources, depending on the type of ore being mined as well as the final consumer product provided by that mine. Depending on the source of noise generation, different strategies to reduce and avoid that noise should be implemented. The National Institute for Occupational Safety and Health (NIOSH) has evaluated the noise profile at three operational surface stone, sand, and gravel mines. A-weighted sound level meter data as well as phase array beamforming data were collected throughout the mines in areas with high noise exposure or high personnel foot or vehicle traffic. Sound level meter data collected on a grid pattern was used to develop sound profiles of the working areas. These sound contour maps as well as phase array beamforming plots were provided to the mines as well as guidance to modify work areas or personnel traffic to reduce noise exposure.

Floristic composition and potential invasiveness of alien herbaceous plant in Western Mexico

Introduction: Numbers of alien plant species are rising around the globe, but not all of them become invasive. Whereas introductions have been documented for several decades in some regions of the world, knowledge on alien species in Western Mexico is limited. Here, we study roadside vegetation along an elevational gradient, which includes a protected area. Objective: We analysed the floristic composition of herbaceous alien species, their distribution patterns, and their relationship with various environmental factors. A relative importance value index (IVI) identified the most important and, therefore, probably invasive taxa. Methods: During 2017 and 2018, roadside vegetation was documented with 4-6 transects every 300 altitudinal meters, from 0 to 2 100 m, for a total of 37 transects. Each transect consisted of five 1 m² plots. All herbaceous species were registered and alien taxa identified. A cluster analysis distinguished grouping of species based on elevation. The potentially invasive species were identified by their IVI, based on the sum of relative frequency and density values. The influence of environmental variables was analysed with a canonical correspondence analysis. Results: Most alien species were grasses; other families were represented by one or two species. The species were grouped into three main clusters. The first group included rare species, the second consisted of species restricted to higher altitudes, and the third group were tropical taxa with a distribution from sea level to medium altitudes. The most important potentially invasive species were: Urochloa maxima, Melinis repens, Eragrostis ciliaris and Cynodon dactylon, all African grasses introduced for grazing. The IVI of the species was related to tree cover, leaf litter depth and surface stone cover for some species and, for others, to soil compaction, distance to major roads and elevation. Conclusions: The alien ruderal species clustered according to the general climate (temperate vs. tropical). Grasses of African origin are of highest concern as invasive species. Although most introductions are related to human disturbance, each species becomes dominant under certain environmental conditions. Thus, management programs must be specifically adjusted to each individual invasive alien.

Landscape-scale perspectives on Stone Age behavioural change from the Tankwa Karoo, South Africa

ABSTRACT Southern Africa is an ecologically highly varied region, yet many generalisations about past human behaviour are drawn from rock shelter sites in coastal and montane Fynbos Biome environments. The Tankwa Karoo region offers the opportunity to extend our archaeological knowledge from the well-researched Western Cape into the arid interior Karoo in order to better capture behavioural variability and identify specific adaptations to more marginal conditions. This research presents the results of off-site surveys in the Tankwa Karoo, which spans the Cape to Karoo transition, mapping surface stone artefacts from the Earlier and Middle Stone Ages. The observed patterns in landscape use and lithic technology for each time-period were tested against a set of expectations based on previous research in the Western Cape and the Upper Karoo. The results indicate that in the Earlier Stone Age the most arid parts of the Tankwa Karoo saw only ephemeral use, with the better-watered mountain fringes preferred. In contrast, various strategies in the Middle Stone Age allowed groups to occupy these marginal parts of the landscape, including new kinds of technological behaviour suggestive of specific adaptations to this environment.

Behavioral safety compliance in an interdependent mining environment: supervisor communication, procedural justice and the mediating role of coworker communication

Objectives. Although a focus on safety communication between managers and employees has been prevalent, research around coworker influence in this communication has been fragmented in the literature. Methods. To examine these issues, researchers gathered survey data from 1955 mine employees from surface stone, sand and gravel (SSG) and industrial mineral operations across the USA between 2016 and 2018, and studied the effects of relationships between justice perceptions, supervisor communication and coworker communication on behavioral safety compliance. Results. Using structural equation modeling, coworker communication partially mediated the direct effects of supervisor communication and justice perceptions on behavioral safety compliance – where the indirect effects were greater for justice perceptions. Conclusion. The results demonstrate the value in formal and informal communication paths to facilitate employee safety compliance; and that enhanced perceptions of job fairness and adaptability enhances coworker communication, further improving compliance in an interdependent environment.

Competencies for the Competent Person: Defining Workplace Examiner Competencies from the Health and Safety Leader’s Perspective

The ability to identify hazards during a workplace examination is a critical skill for mineworkers to have in order to maintain a safe workplace. While research suggests that being able to successfully recognize hazards requires a complex set of competencies, it is unclear which competencies are most critical to adequately perform a workplace examination. This paper presents a hazard recognition competencies framework as an explanation of the competencies that affect mineworker hazard recognition. To better understand how the industry is selecting and preparing workplace examiners, researchers from the National Institute for Occupational Safety and Health (NIOSH) interviewed nine health and safety (H&S) professionals at surface stone, sand, and gravel mine sites throughout the USA. A primary purpose of these interviews was to verify the competencies included in the hazard recognition competencies framework and to understand why these competencies are critical. Finally, the results of this study are presented within the context of current NIOSH research findings related to hazard recognition.

The new assessment of soil erodibility in Greece

Erodibility designates soils' vulnerability to the abrading effect of erosion's climatic drivers i.e. precipitation and overland flow. This parameter is represented in the Universal Soil Loss Equation (USLE) and its successor (RUSLE), by the respective component (K-factor). Its accurate quantification is critical for modelling soil erosion. Yet, in many countries – Greece included – the process is hindered by the lack of high-quality field observations, evenly distributed in time and space. In light of the above, the study aims to develop the new soil erodibility map of Greece. The K-factor was calculated using the algebraic expression of the Wischmeier and Smith (1978) nomograph. The latter considers basic soil properties like granulometry, soil organic matter content, structure and permeability. Approximately 2800 soil samples were utilized, deriving from the European Land Use/Cover Area frame Survey (LUCAS) and the Greek National Agricultural Research Foundation (NAGREF) databases. Of them, 577 corresponded to croplands and 2113 to forests/rangeland. Erodibility was spatially interpolated utilizing the ordinary cokriging methodology. The mean nationwide value was estimated at 0.024 t ha h ha−1 MJ−1 mm−1, ranging from 0.013−0.044 t ha h ha−1 MJ−1 mm−1. After incorporating the surface stone cover effect, given the country's extensive coverage, mean K-factor value was reduced by 22 %, at 0.018 t ha h ha–1 MJ–1 mm–1. The new maps (500 m resolution) improve the accuracy of the available K-factor delineation, developed by the EU at pan-European level. The sample network is denser (1 sample per 48 km2) and more evenly distributed throughout the Greek territory. Also, the geostatistical model was fitted focusing entirely on the specific attributes of Greece. The results were proportional to those yielded by national and international studies of local and national interest.

A photoacoustic pulse-echo probe for monitoring surface stone mechanical properties: validation tests in consolidation of Carrara marble

A photoacoustic pulse-echo probe for monitoring surface stone mechanical properties: validation tests in consolidation of Carrara marble

Why Slips, Trips, and Falls Are Still A Problem: A Hazard Assessment At Surface Mines

Slips, trips, and falls (STF) contribute significantly to nonfatal incidents at surface mines. Although fall fatalities and STF from mobile equipment have been investigated, nonfatal incidents and STF hazards encountered at mines are not well documented. This paper aims to identify occupations and activities associated with nonfatal STF incidents at surface stone, sand, and gravel mines, document through a systematic observation the STF hazards encountered, and corroborate the findings of the hazard assessment using an analysis of nonfatal injury narratives reported in the Mine Safety and Health Administration (MSHA) injury database. Mobile equipment operators, laborers/utility men, and mechanics were most often involved in nonfatal STF incidents. Walking/running, getting on/off equipment, machine maintenance and repair, and handling supplies and materials accounted for over 80% of the activities being performed at the time of the incident. Solid debris, in the form of rocks and stones on unpaved surfaces and material accumulation on paved surfaces, and liquid contaminants, primarily pooled water, were common hazards identified during the systematic observation. Stair tread issues and transitions to and from ladders were also identified as hazards. These findings were in line with injury data where rocks, ice/snow, uneven ground, water, hoses, mud, and loose/unstable material were the most common contaminants and hazards encountered at the time of the incident. In addition, several recommendations are provided to help eliminate or remediate the identified hazards.

A new approach for measuring surface hydrological connectivity

AbstractThe development of surface hydrological connectivity is a key determinant of flood magnitude in drylands. Thresholds in runoff response may be reached when isolated runoff‐generating areas connect with each other to form continuous links to river channels, enabling these areas to contribute to flood hydrographs. Such threshold behaviour explains observed nonlinearities and scale dependencies of dryland rainfall–runoff relationships and complicates attempts at flood prediction. However, field methods for measuring the propensity of a surface to transmit water downslope are lacking, and conventional techniques of infiltration measurement are often inappropriate for use on non‐agricultural drylands. Here, we argue for a reconceptualization of the dryland surface runoff process, suggesting that the downslope transfer of water should be considered alongside surface infiltration; that is, there is a need for the “aggregated” measurement of infiltration and overland flow hydraulics. Surface application of a set volume of water at a standardized rate generates runoff that travels downslope; the distance it travels downslope is determined by infiltration along the flow, integration of flow paths, and flow resistance. We demonstrate the potential of such a combined measurement system coupled with structure‐from‐motion photogrammetry to identify surface controls on runoff generation and transfer on dryland hillslopes, with vegetation, slope, surface stone cover, and surface roughness all having a significant effect. The measurement system has been used on slopes up to 37° compared with the flat surface typically required for infiltration methods. On average, the field workflow takes ~10–15 min, considerably quicker than rainfall simulation. A wider variety of surfaces can be sampled with relative ease, as the method is not restricted to stone and vegetation‐free land. We argue that this aggregated measurement represents surface connectivity and dryland runoff response better than standard hydrological approaches and can be applied on a much greater variety of dryland surfaces.

Finding a Relatively Flat Archaeological Site with Minimal Ceramics: A Case Study from Iraqi Kurdistan

ABSTRACTWe present a new technique to detect flat archaeological sites with minimal ceramics using an unmanned aerial vehicle that maps surface stone concentrations. Methods deployed include point pattern analysis of stone concentrations and a machine-learning technique using unsupervised classification of visible stone signature qualities, which are used in simple linear regressions to compare with geophysical and ceramic surface survey results of a site in Iraqi Kurdistan. There is a stronger fit (r2 = 0.77) between surface stone concentrations and architecture identified by geophysical measurement, while surveyed ceramics show a weaker fit to defined architecture (r2 = 0.31). Surface stone concentrations are potentially a better proxy than ceramics for determining the presence of past settlement in regions where stone was commonly used, sites are relatively flat, and ceramics are found in low concentrations. The methods advanced here can be scaled to wider areas, particularly in mountainous regions, where surface stone features are present.

Burden associated with nonfatal slip and fall injuries in the surface stone, sand, and gravel mining industry

Slips, trips, and falls (STFs) pose a significant financial burden to employers and account for over 33% of the total nonfatal workers’ compensation cost in the United States. Previous analyses documenting the burden of STF incidents in the mining industry have focused on occupational fatalities or STFs during equipment ingress, egress. There is limited information on the burden of nonfatal STF incidents in the mining industry and most of it is outdated. Hence, to increase awareness and highlight the importance of STFs in the mining industry, this analysis documents the burden associated with nonfatal STF incidents at surface stone, sand, and gravel (SSG) mines from 2008 through 2017. In this time frame, nonfatal STF incidents occurred at a rate of 62 per 10,000 full-time equivalent (FTE) employees per year. Pits had a higher prevalence of injuries, but plants had a higher incidence rate. In addition, nonfatal STF incidents at surface SSG mines led to approximately 23,800 total days lost per year with an estimated cost to the mining industry of $17.5 million per year. Assessed violations that are not related to reported injuries but are related to STF hazards identified during Mine Safety and Health Administration (MSHA) inspections cost the mining industry approximately $3 million per year from 2013 through 2017. Based on the data analyzed in this study, falls to the lower level pose a higher burden in terms of cost; however, falls to the same level have a higher number of incidents and incidence rate.

Influence of Polyfunctional Additive on Hardening Process and Properties of Cement Concrete

The paper presents results of research aimed at developing a new semi-functional concrete additive that provides an increase in rate and level of its strength growth while reducing energy costs to accelerate hardening process, as a basis for reducing energy intensity in manufacturing of concrete and reinforced concrete products and structures. Experimentally a rational ratio of components for a polyfunctional additive has been found of mass cement: a superplasticizer based on polycarboxylate resins (for example, “Stachement 2000” or “Relamiks PC”) – 0.5 %, ultradispersed microsilica (SiO2) – 1.0 %, sodium sulfate (Na2SO4), hardening accelerator – 0.5 %, aluminum sulfate (Al2(SO4)3), sealing additive structure ‒ 0.25 %. The mentioned components ensure the largest increase in strength of cement stone and structural heavy concrete. Results of derivatographic and X-ray phase analyses have shown that strength growth is based on formation of a fine-crystalline form of low-base crystalline silicates of CSH-silicate group, which complements traditionally formed C2SH by the reaction of threeand two-calcium silicate cement with water, as well as it is based on an increase in the number of neoplasms due to the reaction of Ca(OH)2 with amorphous SiO2 and ettringite 3CaO × Al2O3 × 3CaSO4 × 32H2O, being formed due to reactions with cement aluminates these are accelerating-compacting additive components, that in total provides an increase in density and strength of cement stone. While having the case with concrete, the effect is complemented by hardening the zone of contact between aggregate surface and cement stone due to the reaction between Ca(OH)2 and SiO2. These effects have been confirmed by growth (up to 38 %) of water which is chemically bound with cement in presence of a multifunctional additive in samples of cement stone, which is characterized by the largest strength. While using standardized testing methods, effectiveness of a multifunctional additive has been experimentally confirmed and it has been expressed in growth of quality characteristics and properties of structural heavy concrete: compressive strength – up to 40–60 %, flexural strength – up to 15 %, reduction of shrinkage – up to 50 % and water absorption – by 1.5–2 times, increase in frost resistance from brand F250 to F500, water resistance – from W6–W8 to W20.

Surface Stone Artifact Scatters, Settlement Patterns, and New Methods for Stone Artifact Analysis

Movement and mobility are key properties in understanding what makes us human and so have been foci for archeological studies. Stone artifacts survive in many contexts, providing the potential for understanding landscape use in the past through studies of mobility and settlement pattern. We review the inferential basis for these studies based on archeological practice and anthropological understanding of hunter-gatherer bands. Rather than structured relationships among band size, composition, and mobility, anthropological studies suggest variability in how hunter-gatherer groups were organized. We consider how stone artifact studies may be used to investigate this variability by outlining a geometric approach to stone artifact analysis based on the Cortex Ratio. An archeological case study from Holocene semi-arid Australia allows consideration of the potential of this approach for understanding past landscape use from stone artifact assemblage composition more generally.

The predictive value of ureteral wall thickness for impacted ureteral stones

Objective To determine the predictive parameters of impacted ureteral stones and evaluate the predictive value of ureteral wall thickness for impacted ureteral stones. Methods A total of 93 patients with proximal ureteral stones from January 2017 to December 2017 were included in the study [71 males and 22 females, aged 30-80 years, and body mass index (23.7±2.7)kg/m2 ]. Both clinical and computed tomography urography (CTU) data were compared between patients with or without impacted ureteral stone, including sex, age, body mass index, renal pelvic diameter, longitudinal size of stone, transverse size of stone, stone surface area, stone volume, hounsfield units of stone, diameter of the ureter proximal to the stone, and ureteral wall thickness at the impacted ureteral stone site. The receiver operating characteristic curve (ROC) was used to analyze the performance of each of the above-mentioned parameters for predicting the impacted ureteral stones. Multivariate logistic regression analysis was used to select the independent risk factors of impacted ureteral stones. Results Among 93 patients, 38 (40.8%) patients were with impacted stones and 55(59.1%) without impacted stones. Univariate analysis showed significant difference in ureteral wall thickness (t=6.344, P<0.001), diameter of the ureter proximal to the stone(U=607.5, P=0.001), longitudinal size of stone(U=580.5, P<0.001), transverse size of stone(t=4.172, P<0.001), stone surface area(U=508.5, P<0.001), stone volume(U=508.5, P<0.001) and hounsfield units of stone(t=6.344, P=0.006) between patients with or without impacted stones. Ureteral wall thickness(UWT) showed the largest area under curve(AUC) among those parameters(AUC=0.825, P<0.001), followed by stone surface area and stone volume. The optimal cut-off value of ureteral wall thickness was 3.16 mm, with sensitivity of 71.1% and specificity of 85.5%. Multivariate analysis showed that ureteral wall thickness (Wald=18.709, P<0.001) and stone volume(Wald=8.391, P=0.004) were independent predictors of impacted stones. Conclusion Ureteral wall thickness was related to the presence of impacted ureteral stones and could be used for predicting impacted ureteral stones. Key words: Impacted; Ureteral stone; Prediction; Ureteral wall thickness