Evaluation of rock mass units using a non-invasive geophysical approach.

Thorough and accurate assessment of rock mass units is important for development of engineering infrastructures and groundwater resources assessments. Rock mass units are widely evaluated by reliable geomechanical parameters namely rock quality designation (RQD) and rock core index (RCI). Conventionally, these parameters are acquired via an extensive number of geotechnical tests. Such tests, however, suffer efficiency for data coverage, cost, equipment and topographic constrictions, and hence cause ambiguity in geological models for a detailed evaluation of rock mass integrity. Conversely, geophysical surveys offer fast, more user-friendly, less invasive, more cost-effective and less time-consuming approach for geological investigations. The past research confirms a useful link between geophysical and geotechnical parameters. But, none of the past studies provides a suitable and generalized relation between these parameters which can reduce geotechnical model uncertainty mostly caused by inadequate data and subsurface heterogeneity. This paper proposes a meaningful and feasible method to obtain geomechanical parameters using a certain number of drillings and geophysical data of four different sites. Based on electrical resistivity obtained from electrical resistivity tomography (ERT) and controlled-source audio-frequency magneto telluric (CSAMT), this research provides the general and adaptable formulas for geotechnical parameter estimation and reduces geological model uncertainty for more detailed 2D/3D imaging of RQD and RCI covering the whole sites where even no drilling data exists. Thus, the investigated sites are assessed laterally and vertically along each geophysical profile via distinct value ranges of geological parameters for a thorough and reliable evaluation of rock mass units in highly heterogeneous setting. Our research reduces the ambiguity caused by structural heterogeneities and scarce data, fills the gap between inadequate well tests and the true geological models, and gives new insights into the rock mass units for proper engineering design and groundwater exploitation.

Application of electrical resistivity tomography (ERT) for rock mass quality evaluation.

Rock mass quality evaluation is a challenging task in geotechnical investigations given the natural heterogeneity and the limited data. These investigations mainly depend on the traditional drilling tests. However, such tests are expensive and time consuming, provide point measurements, and cannot be conducted in steep topographic areas, and thus cause uncertainties in the geological model. Conversely, geophysical methods such as electrical resistivity tomography (ERT) are non-invasive, user-friendly, and fast. In this work, we establish empirical correlation between ERT and limited drilling data to obtain rock mass integrity coefficient (Kv). The estimated Kv provides 2D/3D imaging of the rock mass quality evaluation via weathered/unweathered rock and faults detection in order to cover the entire area even where no drilling test exists. Compared with the past geotechnical investigations, our work reduce the ambiguities caused by the inadequate well tests and provide more accurate geological model for infrastructures design. Our work proposes that, in case of sparse borehole data, the established empirical equations can be used to determine Kv along different geophysical profiles via 2D/3D insight of the subsurface. Our approach is applicable in any hard rock setting, and the established correlations can be used in areas even where no well test exists.

Joint geophysical prospecting for groundwater exploration in weathered terrains of South Guangdong, China.

Groundwater occurrence in a hard rock terrain is strongly controlled by the weathered/fractured zones. However, delineation of such zones is a challenging task given their structural heterogeneity. Traditionally, large numbers of well tests are conducted to assess the subsurface formation. But, such tests suffer from efficiency in terms of cost, time, and data coverage. Non-invasive geophysical methods can be the best alternative of expensive drilling methods. However, a geophysical method alone is ambiguous to interpret the highly heterogeneous subsurface formation. In this study, joint application of electrical resistivity tomography (ERT), magnetic method, and joint profile method (JPM) was conducted for groundwater exploitation in a weathered terrain of South Guangdong, China. ERT, magnetic, and JPM data were acquired along different geophysical profiles via a variety of survey parameters. The interpreted 2D models of electrical resistivity and magnetic data coupled with the local accessible boreholes and hydrogeological information constrain the subsurface geologic formation into four discrete layers with specific electrical resistivity range, i.e., topsoil cover, highly weathered saturated layer, semi-weathered saturated layer, and un-weathered substratum. Incorporation of JPM (ER, SP, and IP methods) with ERT and magnetic models reveal three faults (F1, F2, and F3) and several saturated intense fractures/discontinuities. The groundwater reserves associated with the weathered/fractured rock were estimated via hydraulic parameters, namely hydraulic conductivity and transmissivity. The results suggest that high-yield groundwater resources are found within the weathered/fractured zones. Geophysical results of this joint application fit pretty well to the local hydrogeological data of the study area. Our novel approach reduces any ambiguity caused in the geophysical interpretation and provides clearer insight of the subsurface formation with more confident solutions to the most challenging problems of the hard rock sites. This hydrogeophysical study provides important contributions to groundwater exploration in areas where weathering has significant effects on the hard rock aquifer system. Compared with traditional methods, this approach is more advantageous for assessment of groundwater resources in hard rock terrains.

Delineation of contaminated aquifers using integrated geophysical methods in Northeast Punjab, Pakistan.

A decline in surface water sources in Pakistan is continuously causing the over-extraction of groundwater resources which is in turn costing the saltwater intrusion in many areas of the country. The saltwater intrusion is a major problem in sustainable groundwater development. The application of electrical resistivity methods is one of the best known geophysical approaches in groundwater study. Considering the accuracy in extraction of freshwater resources, the use of resistivity methods is highly successful to delineate the fresh-saline aquifer boundary. An integrated geophysical study of VES and ERI methods was carried out through the analysis and interpretation of resistivity data using Schlumberger array. The main purpose of this investigation was to delineate the fresh/saline aquifer zones for exploitation and management of fresh water resources in the Upper Bari Doab, northeast Punjab, Pakistan. The results suggest that sudden drop in resistivity values caused by the solute salts indicates the saline aquifer, whereas high resistivity values above a specific range reveal the fresh water. However, the overlapping of fresh/saline aquifers caused by the formation resistivity was delineated through confident solutions of the D-Z parameters computed from the VES data. A four-layered unified model of the subsurface geologic formation was constrained by the calibration between formation resistivity and borehole lithologs. i.e., sand and gravel-sand containing fresh water, clay-sand with brackish water, and clay having saline water. The aquifer yield contained within the fresh/saline aquifers was measured by the hydraulic parameters. The fresh-saline interface demarcated by the resistivity methods was confirmed by the geochemical method and the local hydrogeological data. The proposed geophysical approach can delineate the fresh-saline boundary with 90% confidence in any homogeneous or heterogeneous aquifer system.

Geophysical Assessment of Groundwater Potential: A Case Study from Mian Channu Area, Pakistan.

An integrated study using geophysical method in combination with pumping tests and geochemical method was carried out to delineate groundwater potential zones in Mian Channu area of Pakistan. Vertical electrical soundings (VES) using Schlumberger configuration with maximum current electrode spacing (AB/2 = 200 m) were conducted at 50 stations and 10 pumping tests at borehole sites were performed in close proximity to 10 of the VES stations. The aim of this study is to establish a correlation between the hydraulic parameters obtained from geophysical method and pumping tests so that the aquifer potential can be estimated from the geoelectrical surface measurements where no pumping tests exist. The aquifer parameters, namely, transmissivity and hydraulic conductivity were estimated from Dar Zarrouyk parameters by interpreting the layer parameters such as true resistivities and thicknesses. Geoelectrical succession of five-layer strata (i.e., topsoil, clay, clay sand, sand, and sand gravel) with sand as a dominant lithology was found in the study area. Physicochemical parameters interpreted by World Health Organization and Food and Agriculture Organization were well correlated with the aquifer parameters obtained by geoelectrical method and pumping tests. The aquifer potential zones identified by modeled resistivity, Dar Zarrouk parameters, pumped aquifer parameters, and physicochemical parameters reveal that sand and gravel sand with high values of transmissivity and hydraulic conductivity are highly promising water bearing layers in northwest of the study area. Strong correlation between estimated and pumped aquifer parameters suggest that, in case of sparse well data, geophysical technique is useful to estimate the hydraulic potential of the aquifer with varying lithology.

Geophysical Investigation of Fresh-Saline Water Interface: A Case Study from South Punjab, Pakistan.

The importance of the study of fresh-saline water incursion cannot be over-emphasized. Borehole techniques have been widely used, but they are quite expensive, intrusive, and time consuming. The electrical resistivity method has proved very successful in groundwater assessment. This advanced technique uses the calculation of Dar-Zarrouk (D-Z) parameters, namely longitudinal unit conductance, transverse unit resistance, and longitudinal resistivity has been employed by using 50 vertical electrical sounding points to assess the groundwater and delineate the fresh-saline water interface over 1045 km2 area of Khanewal in Southern Punjab of Pakistan. The x-y plots and maps of D-Z parameters were produced to establish a decipherable vision for the occurrence and distribution of different water-bearing formations of fresh-saline water aquifers through a complicated situation of intermixing of different resistivity ranges for fresh-saline water bodies. This technique is useful to reduce the ambiguity produced by the process of equivalence and suppression which cause intermixing in differentiating fresh, brackish, and saline aquifers during interpretation. The fresh-saline water interface is correlated very well with the previous studies of water quality analysis carried out in Khanewal area. The results suggest that the D-Z parameters are useful for demarcating different aquifer zones. The behavior and pattern of D-Z parameters with respect to occurrence and distribution of different water-bearing formations were effectively identified and delineated in the study area.

The accuracy of glial fibrillary acidic protein in acute stroke differential diagnosis: A meta-analysis.

We performed a systematic review of English-language studies published during the past three decades to investigate the diagnostic performance of serum glial fibrillary acidic protein (GFAP) for the differential diagnosis of acute stroke, including intracerebral hemorrhage (ICH) and cerebral ischemia (CI). QUADAS tools were used to evaluate the quality of the study. Performance characteristics (diagnostic sensitivity, specificity, and other measures of accuracy) were pooled and examined using fixed-effects models. Four studies met the inclusion criteria, and included 109 patients with ICH and 381 patients with CI. The summary estimates for GFAP in the ICH diagnoses had a diagnostic sensitivity of 0.80 (95% confidence interval 0.71-0.88), a specificity of 0.97 (95% confidence interval, 0.94-0.98), and a diagnostic odds ratio (DOR) of 119.55 (95% confidence interval: 51.75-276.19). The area under curve (AUC) and Q value for the sROC curves were 0.97 and 0.92, respectively. Therefore, GFAP showed high diagnostic accuracy for acute stroke differential diagnosis.

Systematic review and meta-analysis of flow cytometry in urinary tract infection screening.

BACKGROUND: Automated urine sediment analysis of white blood cells (WBCs) and bacteria is a promising approach for urinary tract infections (UTIs) screening. However, available data on their screening efficacy is inconsistent. METHODS: English articles from Pubmed, EMBASE, and Web of Science published before December 1, 2012 were analyzed. The Quality Assessment for Studies of Diagnostic Accuracy (QUADAS) tool was used to evaluate the quality of eligible studies. Performance characteristics of WBCs and bacteria (sensitivity, specificity, and other measures of accuracy) were pooled and examined by random-effects models. RESULTS: Nineteen studies containing 22,305 samples were included. Pooled sensitivities were 0.87 (95% confidence interval [CI], 0.86-0.89) for WBCs and 0.92 (95% CI, 0.91-0.93) for bacteria. Corresponding pooled specificities were 0.67 (95% CI, 0.66-0.68) for WBCs and 0.60 (95% CI, 0.59-0.61) for bacteria. Areas under the summary receiver operating characteristics curves were 0.87 and 0.93 for WBCs and bacteria, respectively. The major limitation of eligible studies was that enrolled subjects were often not representative of clinical patient populations in which UTI would be suspected. CONCLUSIONS: WBC and bacterial measurements by the UF-100 and UF-1000i are useful indicators in UTI screening; however, the performances of these systems should be rigorously evaluated by additional studies.

Superoxide radicals scavenging and xanthine oxidase inhibitory activity of magnesium lithospermate B from Salvia miltiorrhiza.

In this study we investigated the superoxide radicals scavenging effect and xanthine oxidase inhibitory activity by magnesium lithospermate B, which was originally isolated from the roots of Salvia miltiorrhiza (also named Danshen or Dansham), an important herb in Oriental medicine. Superoxide radicals were generated both in beta-NADH/PMS system and xanthine/ xanthine oxidase system. Magnesium lithospermate B significantly inhibited the reduction of NBT induced by superoxide radicals with an IC(50) of 29.8 microg/mL and 4.06 microg/mL respectively in the two systems. Further study suggested that magnesium lithospermate B can directly inhibit xanthine oxidase and exhibits competitive inhibition. Magnesium lithospermate B was also found to have the hypouricemic activity in vivo against potassium oxonate-induced hyperuricaemia in mice. After oral administration of magnesium lithospermate B at doses of 10, 20 and 30 mg/kg, there was a significant decrease in the serum urate level when compared to the hyperuricemia control. In addition, magnesium lithospermate B significantly protected HL-60 cells from superoxide radicals-induced apoptosis in the xanthine/ xanthine oxidase reactions. This study provided evidence that magnesium lithospermate B exhibits direct superoxide radicals scavenging and xanthine oxidase inhibitory activity.

Lithospermic acid as a novel xanthine oxidase inhibitor has anti-inflammatory and hypouricemic effects in rats.

Lithospermic acid (LSA) was originally isolated from the roots of Salvia mitiorrhiza, a common herb of oriental medicine. Previous studies demonstrated that LSA has antioxidant effects. In this study, we investigated the in vitro xanthine oxidase (XO) inhibitory activity, and in vivo hypouricemic and anti-inflammatory effects of rats. XO activity was detected by measuring the formation of uric acid or superoxide radicals in the xanthine/xanthine oxidase system. The results showed that LSA inhibited the formation of uric acid and superoxide radicals significantly with an IC50 5.2 and 1.08 microg/ml, respectively, and exhibited competitive inhibition. It was also found that LSA scavenged superoxide radicals directly in the system beta-NADH/PMS and inhibited the production of superoxide in human neutrophils stimulated by PMA and fMLP. LSA was also found to have hypouricemic activity on oxonate-pretreated rats in vivo and have anti-inflammatory effects in a model of gouty arthritis. These results suggested that LSA is a competitive inhibitor of XO, able to directly scavenge superoxide and inhibit superoxide production in vitro, and presents hypouricemic and anti-inflammatory actions in vivo.

Renierol from marine sponge Haliclona.SP.: a natural inhibitor of xanthine oxidase with hypouricemic effects.

The purpose of this study was to evaluate the inhibitory effect of renierol, extracted from marine sponge Halicdona.SP., on xanthine oxidase (XO) and its hypouricemic effect in vivo. Renierol and a positive control, allopurinol, were tested for their effects on XO activity by measuring the formation of uric acid and superoxide radical from xanthine. Renierol inhibited XO in a concentration-dependent and competitive manner. IC(50) value was 1.85 microg.ml(-1) through the measuring of uric acid and was 1.36 microg.ml(- 1) through the measuring of superoxide radical. Renierol was found to have an in vivo hypouricemic activity against potassium oxonate-induced hyperuricaemia in mice. After oral administration of renierol at doses of 10, 20 and 30 mg.kg(- 1), there was a significant decrease in the serum urate level (4.08 +/- 0.09 mg.dl(- 1), P < 0.01), (3.47 +/- 0.11 mg.dl(- 1), P < 0.01) and (3.12 +/- 0.08 mg.dl(- 1), P < 0.01), when compared to the hyperuricaemic control (6.74 +/- 0.23 mg.dl(- 1)). Renierol was a potent XO inhibitor with hypouricemic activity in mice.