Direct Test Method Research Articles

Direct testing by VITEK® 2: A dependable method to reduce turnaround time in Gram-negative bloodstream infections.

CONTEXT:Bloodstream infections pose a major health-care burden worldwide. Routine microbiological methods are time-consuming, thereby delaying appropriate treatment.AIMS:The aim of this study is to evaluate the method of direct testing of identification (ID) and antimicrobial susceptibility testing (AST) of positive blood culture bottles by VITEK®2.SETTINGS AND DESIGN:This was a prospective study at a tertiary level hospital.SUBJECTS AND METHODS:One hundred positive BACTEC blood culture bottles with monomicrobial Gram-negative organisms on microscopy were tested in parallel by direct ID/AST as well as conventional method. Results obtained by two methods were compared in terms of ID/AST and turnaround time (TAT).RESULTS:Of the 100 isolates tested, only one was misidentified by the direct method and there was no unidentified isolate. The AST results demonstrated 99.74% categorical and 99.65% essential agreement. Of 1144 organism-antibiotic combinations, there were 0.44% major error, no very major error, or minor error observed.CONCLUSIONS:While conventional method is the gold standard, the direct ID/AST methods have demonstrated that it can be successfully utilized to decrease TAT to the final results by 18–24 h, without sacrificing test accuracy. This technique will help to tailor antimicrobial therapy, thereby reducing patient morbidity, mortality, and antibiotic resistance, as well.

Comparative analysis of methods of pile-bearing capacity evaluation using CPT logs from tropical soils

This study presents the results of a comparative analysis of the performance of eight direct cone penetration test (CPT) methods in predicting the ultimate load-carrying capacity of a 300 mm diameter end-bearing pile, evaluated at defined soil depths using CPT logs obtained for various locations in the south-east and south-south regions of Nigeria. The methods used are the Schmertmann (1978), LCPC (Bustamante & Gianeselli 1982 - Laboratoire Central des Ponts et Chausees), De Ruiter and Beringen (1979), Tumay and Fakhroo (1982), Price and Wardle (1982), Philipponnat (1980), Aoki and De Alencar (1975), and the Penpile methods (Clisby et al 1978). The results of univariate analysis of variance indicated that the interactions between location and treatment (methods of pile capacity prediction), depth and treatment, and location and depth were statistically significant for cohesionless soils, but that the interaction between depth and treatment was not statistically significant for cohesive soils. Also, post-hoc tests (Least square difference and Bonferroni methods) showed that the LCPC and Philipponnat methods are best suited for cohesionless soils, while the LCPC, Tumay and Fakhroo (1982) and De Ruiter and Beringen (1979) methods are recommended for cohesive soils.

Experimental investigation of interface treatment technique on interface shear bond fatigue behavior of Ultra-Thin Whitetopping

The bonded concrete overlays on existing asphalt pavements are classified into three subcategories namely whitetopping, thin-whitetopping and Ultra-Thin Whitetopping (UTW). The design service life of UTW overlays depends on several factors such as interface bond strength, slab thickness, slab size, material strength and underlying material condition. The quality of the interface bond depends on both surface preparation and the UTW placement procedure. The interface bond between two layers helps in the monolithic action of the pavement section by shifting the neutral axis from the middle of the UTW slab to the bottom of UTW slab. The composite action had a direct impact on the long-term performance of the UTW overlays. To assure good bonding, milling method is usually applied at the interfaces during UTW overlay construction. The interface bond strength due to milling technique can be measured with the help of several devices arranged by different laboratories. This paper investigates the interface shear bond strength and shear fatigue behavior of UTW pavement for different interface treatment techniques. For this experimental purpose, a laboratory direct shear testing method and procedure was used. Two interface treatment technique like groove and piercing method have been analyzed. Interface treatment with piercing technique had shown highest shear bond strength and k-modulus values. Incorporating groove interface technique with an inclination of 0–45 degrees and piercing interface treatment has been proposed. The interface shear bond fatigue behavior of piercing treatment technique with different debonding conditions are discussed. As expected the increase in debonding leads to decrease in interface shear stress and fatigue performance.

Numerical modeling and analysis for axial compressive crushing of randomly oriented thermoplastic composite tubes based on the out-of-plane damage mechanism

The structural beams with a uniform cross section of hat-shape were manufactured through a high-cycle compression molding technique, by using randomly oriented chopped thermoplastic composites. The crash tubes were obtained by vibration welding of those two hat-section beams at their flanges. And the axial compressive impact tests were carried out for them. It followed that the compressive failure was progressive crushing caused by the delamination and local buckling of walls and welded flange while the specific energy absorption was so high. The finite element model was constructed to predict the axial progressive crushing and energy absorption. The important key concept for designing the numerical model was to incorporate some hypothetical inter-layers even in randomly oriented composites and assign them with the failure model as cohesive zone elements, which can perform non-linear characteristics with failure criterion. The material parameters for the model tried to be obtained by direct measurement test methods. The reproducibility of the numerical modeling was validated against the results from axial compressive crushing. The progressive damage mode and energy absorption prediction agreed well with the experimental results. It was also clarified that the out-of-plane failure influenced the energy absorption performance of the crash tubes.

Influencing Factors on Sensitivity of Pressure Decay Test for Membrane Damage Assessment

Pressurized membrane module systems, including hollow fiber type of Microfiltration (MF) and Ultrafiltration (UF) membranes are being increasingly used in drinking water treatment due to their high removal efficiency of pathogen. However, when fibers are damaged in pressurized membrane system, the pathogen will be able to penetrate the membrane. Therefore, it is essential to guarantee the regulatory requirements for water quality by an effective on-line or off-line condition integrity monitoring methods. Recently, pressure decay test (PDT) which is one of membrane integrity tests has been reflected to drinking water treatment plants using pressurized membrane module. In this paper, three different method were used to perform PDT and three different sensitivity values were analyzed through experiments. Three types of direct integrity test methods were applied to pressure feed side, filtrate side and bidirectional pressure decay test. The results of these experiments show that the sensitivity was increasing when the volume of pressurized gas was decreasing. The sensitivity is inversely proportional to the gas volume. Furthermore, it is desirable to increase pressure difference between feed side and permeate side in order to achieve higher sensitivity in the PDT by membrane damage.

Measurement and correlation of isobaric vapour-liquid equilibria for binary systems of 1-(methoxymethoxy)-2-methyl-propane with 1-butanol and isobutanol at 101.33 kPa

Isobaric vapour-liquid equilibria (VLE) experimental results for binary systems of 1-(methoxymethoxy)-2-methyl-propane with 1-butanol and isobutanol at 101.33kPa were determined. Each binary mixture shows a minimum boiling azeotrope at 101.33kPa, in which the azeotropic temperature and composition are 381.19K and 26.72mol% (1-butanol) and 377.55K and 53.34mol% (isobutanol), respectively. The VLE measurements were correlated by the van Laar, Wilson and NRTL models for which the binary interaction parameters are reported. The results show that the measurements of two binary systems provide a good agreement with the calculated values acquired by the Wilson and NRTL models, respectively. The thermodynamic consistency of the VLE measurements was checked using the traditional area test and the direct test methods.

Measurement and Correlation of Isobaric Vapor–Liquid Equilibrium for Binary Systems of 1-(Ethoxymethoxy)-2-methyl-propane with Isobutyl Alcohol or 1-Butanol at 101.33 kPa

Experimental vapor–liquid equilibrium (VLE) data for binary systems of 1-(ethoxymethoxy)-2-methyl-propane (EMMP) with isobutyl alcohol and 1-butanol at 101.33 kPa was measured. The measurements of saturated vapor pressure for EMMP were also measured. The experiment was performed by an improved Rose still. A minimum boiling azeotrope was found about the binary system containing 1-butanol for which the azeotropic temperature and composition are 389.64 K and 75.92 mol% (1-butanol) at 101.33 kPa. The VLE measurements were correlated by the Wilson, nonrandom two-liquid, and universal quasichemical models for which the results showed that the measurements had a good correlation by using three models about two binary systems, respectively. The thermodynamic consistency of the VLE measurements was checked by the traditional area test and the direct test methods.

Evaluation of direct antifungal susceptibility testing methods of Candida spp. from positive blood culture bottles.

Blood culture is the gold standard diagnostic method in candidemia in spite of long result time and low sensitivity rate. Early diagnosis is crucial for management of candidemia because a delay in treatment is related with increased mortality. We aimed to evaluate the direct applicability of antifungal susceptibility testing methods from positive blood culture bottles to save at least 24hours. Blood culture bottles were inoculated with 62 Candida isolates. Etest and broth microdilution (BMD) methods for six antifungals, disk diffusion (DD) method for two antifungals were performed, both directly from bottles and standardly. Essential agreements between direct and standard Etest methods were 87.1% for caspofungin and >90% for other antifungals, but the agreements of them with reference BMD were relatively low. Essential agreement between direct and standard BMD was >93%. Correlation between direct and standard DD methods was very high, negative correlations were observed between reference BMD and DD methods. BMD is a reference method to evaluate the antifungal susceptibility, direct application of BMD might provide reliable results at least 24hours earlier. Direct DD method may be a qualitative alternative. Direct susceptibility testing methods may be very useful to initiating the appropriate treatment on time.

Landslide characterization and distribution in northern Ethiopia: a case study from the Adishu area

Landslides have resulted in large numbers of casualties and huge economic losses in the hilly and mountainous areas of the Ethiopian highlands. Adishu (Adi-Quchi and Quilet villages in particular) is one of the areas most highly affected by rainfall-driven landslides. Field investigations of this area have revealed displacement of 204 people, destruction of 56 rural houses and 5 km of rural roads, and effects on 58 ha of agricultural land due to landslides. In addition, a significant proportion of the population still lives in a terrain potentially endangered by landslides. The geology of the study area consists of Antalo limestone, Agula shale, Amba-Aradom sandstone, basalt flows, and unconsolidated sediments. Thirteen major landslides with clear downthrown head scarps and downspread toes were identified. Inventory of landslides was based on the interpretation of aerial photographs, topographic maps, satellite images, and field identifications, with the aim to assess the cause and type of landslides in the study area. The different methods applied to soils and rocks included the direct shear test, Schmidt hammer, and inverse auger hole methods. The results revealed that soil materials in the area have a low permeability (1.22 × 10−6–3.13 × 10−6 m/s), a high plasticity index (17.2–29.4), and cohesion values ranging between 10 and 26 kN/m2. Soil samples from the stable in situ layers showed relatively high cohesion and relatively small internal angle of friction compared to the residual layer. The common types of landslides in the study area were rock falls, rock topples, debris/earth flows, and debris/earth slides accompanied by translational and rotational sliding mechanisms. These landslides could be classified into three zones based on location, type of failure, mode of failure, and direction of failure. The upper layers of basalt and limestone rocks showed significant percolation and recharge to the downslope layer (marl-shale). We therefore concluded that the marl-shale layer is mainly responsible for sliding, whereby percolated and recharged water cause saturation and the development of pore water pressure in this layer due to its imperious nature. The Qulate (landslide zone one and zone two) and Adi-Quchi (landslide zone three) localities are highly affected areas where there are unconsolidated soil deposits underlain by marl-shale along the streams due to removal of underlying and lateral support by gully erosion.

Reinforcement of sandy soil using plastic fibres made from waste plastic bottles

Today waste plastic bottles are spread widely throughout our world especially in Kurdistan, an autonomous region in Iraq. These waste products cause many environmental problems and at the same time some soils are weak and need reinforcement using cheap materials such as Polyethylene terephthalate (PET) waste plastic bottle. Use of waste plastic bottles as a reinforcement of soil is highly recommended to reduce the amounts of plastic waste, which creates a disposal problem. In this study an attempt was made to use plastic fibres produced from waste bottles to reinforce sandy soil. This can solve both environmental and geotechnical problems. In the research, the effect of plastic fibres content as well as fibre length on shear strength parameters (cohesion and internal friction) were experimentally predicted using the direct shear test method so as to improve bearing capacity of weak soils. The results showed that under low normal stress the inclusion of plastic fibres increased both angle of internal friction and cohesion; however, under high normal stress (greater than 100 kPa) the cohesion increased and the internal friction was roughly unchanged. Also, it was concluded in this study that the suitable amount of fibers that can be added to weak soils is 1% of dry weight of sand.

Prevalence of Sarcocystis Species (Sarcocystis ovicanis and Sarcocystis capricanis) in Tongue Muscle of Sheep and Goats in Duhok Province, Kurdistan Region, North Iraq

Sarcocystis species are coccidian protozoan parasites of the phylum apicomplexa. The prevalence of Sarcocystis species ( Sarcocystis ovicanis and Sarcocystis capricanis) in tongue muscle of sheep and goats that collected from abattoir and outside of abattoir (at Butchers Markets) in Duhok province was determined for the first time during the period of 4 months from September 01, 2014, to January 03, 2015. Three techniques were applied for this purpose. Direct scotch cellophane adhesive tape test, muscle mincing and squash method, and pepsin digestion technique. The overall prevalence was 97% in sheep and 100% in goats. No significant difference (p>0.05) was obtained between male and female of both species. Histopathological analysis revealed different size and shape of microcysts with thick cyst wall, in addition to mild histological changes.

Uncertainty-Based Analysis for Agreement of Tensile-Strength Measurement Procedures

Abstract Rocks fail because of compression, shear, tensile and/or a combination of these stresses. Rocks are more vulnerable to tensile stresses as they can stably accommodate only a fraction of compressive stresses in tensional loading. Therefore, reliable determination of tensile strength of rocks is important. Tensile strength of rocks that can be determined by both direct and indirect tensile testing methods have great importance in rock mechanics. Although these methods have different procedures and quite a change in results, an agreement between the methods is necessary. In addition, properly appraising the data provided by direct and indirect measurements has critical importance for applying the knowledge thereby acquired. From this point, based on the conventional measurement uncertainty framework, two weighting methods are suggested to combine the tensile-strength methods. Thus, an uncertainty-based agreement between the direct and indirect tensile-strength measurements has been made. The results showed that the weighted uncertainties of the proposed methods are lower than the best single measurement uncertainties. In addition, the weighted averages and corresponding uncertainties provide additional information and unique outcomes for the users. A reliable correlation between indirect and direct tensile-strength results is certainly useful for assessing tensile strength of rocks.

Performance Evaluation of Irrigation System in Cikeusik Irrigation Area, Cirebon Regency West Java Province

West Java Province is known as an area that plays an important role in agricultural production in Indonesia. Cirebon is a district in West Java which is in the eastern part bordering Central Java. Many areas of irrigation or Irrigation Network who experience a decrease in performance, one of whom who experience decreased performance is Cikeusik Irrigation Area. This time, the Irrigation Cikeusik Management implemented by Balai Besar Wilayah Sungai (BBWS) Cimanuk Cisanggarung, Directorate General of Water Resources, Ministry of Public Works and Public Housing. The Irrigation Cikeusik receive water supplies from Dam Cikeusik in the Cisanggarung river with the area in 6899 Ha. The purpose of this research is to analyze and calculate what percentage in the performance of the Sub Regional Irrigation Maneunteung West and Sub Regional Irrigation Maneunteung East on irrigation area Cikuesik using the Regulation of the Minister of Public Works No. 32 / PRT / M / 2007 on Guidelines for Operation and Maintenance of Irrigation. Some aspects of the irrigation system set out in the Regulation of the Minister of Public Works No. 32 / PRT / M / 2007 are physical infrastructure, plant productivity, supporting facilities Maintenance Operation, Maintenance Organization Operations personnel, documentation and water user associations (P3A). The research method is by direct observation, questionnaire and test methods research is done by Structural Equation Modeling (SEM). The performance evaluation of irrigation systems shows the percentage of different figures. Assessment is based on a survey conducted in West Sub Maneunteung irrigation area is 75.95% and 71.70% based on the respondent data. A difference of 4.26%, thus the performance of the irrigation system is ranged between 71.70% up to 75.95% or an average of 73.82%. Assessment is based on a survey conducted in Sub irigation area East Maneunteung is 76.10%, while 72.41% of respondents based on the data.The difference of 3.69%, thus the performance of the irrigation system is ranged between 72.41% up to 76.10% or an average of 74.26%. Based on the percentage of those with regulation of the Minister Public Works No. 32/PRT/M/2007 condition Sub irrigation area West Maneunteng and East Maneunteung have good performance.

Effects of Mix Vegetation and Root Shear Strength Grown on Carbonaceous Shale

Background: Carbonaceous shale is one of the common rock types in Malaysia. The most common types of landslides in Malaysia were happened on the cut slope before the construction of highway. Brachiaria ruziziensis and Colopogonium mucunoides were used as the mix vegetation to investigate the effect of chemical amendments on plant growth and root shear strength relationship. Objective: The objective of this study: (1) To investigate the effect of compound fertilizer nitrogen, phosphorus, potassium (NPK), NPK+Ground Magnesium Limestone (GML) (NGL), NPK+GML+foliar fertilizer (Vita-Grow™) (NGF) and control (Ctrl) and (2) To determine the soil shear strength, biomass and root growth. Materials and Methods: The soil samples were analyzed for pH, Total Nitrogen (TN), Soil Organic Carbon (SOC), available phosphorus, exchangeable Al, Ca, Mg and K and trace nutrients (Fe, Mn, Cu and Zn). Results: The carbonaceous shale was low in pH, total N, soil organic carbon, extractable P, basic cations (Ca, Mg and K) and micronutrients (Fe, Cu and Zn). Both P and Ca/Mg were low indicating inherent infertility and chemical constraints for root developments. The dry matter yield, root length and root weight of Brachiaria ruziziensis and Colopogonium mucunoides were increased significantly against NGF treatment. The increased of plant top and root dry weight treated with NGF were 26 and 38%, respectively, compared to the other treatments. The significant root shear strength relationship indicates that root enhanced shear strength by reducing the cohesion and increased the angle of internal friction component. The shear strength analysis from the direct shear test method is to determine the shear strength from the plotted graph. The shear strength analysis showed that NGF treatment was having high shear strength in 5.4, 10.9 and 16.3 and normal stress in 54, 109 and 163 kN m–2. Rapid vegetation growth observed within a 5 months period demonstrated that nutrient and lime application effectively ameliorated chemical constraints to plant growth. Conclusion: The plant mix species treated with NPK+GML+foliar fertilizer (NGF) indicated higher shear strength, dry matter yield and root densities in all layers.

Measurement and correlation of (vapour–liquid) equilibrium for binary mixtures composed of 1-(ethoxymethoxy)-propane with ethanol and 1-propanol at 101.33 kPa

Experimental vapour–liquid equilibrium (VLE) for binary mixtures composed of 1-(ethoxymethoxy)-propane with ethanol and 1-propanol at 101.33kPa was measured. The experimental data of saturated vapour pressure for 1-(ethoxymethoxy)-propane was measured. The measurements were performed using an improved Rose equilibrium still. Two binary systems present a minimum boiling azeotropes at 101.33kPa, in which the azeotropic temperature and composition are 351.45K and 95.98mol% (ethanol) and 369.44K and 81.30mol% (1-propanol), respectively. The VLE experimental values were correlated with the help of the NRTL, Wilson, and van Laar models for which the binary interaction parameters are reported. The results showed that the measurements have a good correlation under the NRTL and Wilson models about two binary systems, respectively. The thermodynamic consistency of the VLE experimental data was checked using the traditional area test and the direct test methods.

Measurement of Average Tensile Force for Individual Steel Fiber Using New Direct Tension Test

Abstract The use of steel-fiber reinforcement as an alternative to conventional reinforcement of various concrete structures has been limited in the construction industry. This is because of the fact that, unlike traditional reinforcement, the performance characterization of steel-fiber concrete is not standardized, because the fibers are distributed throughout the concrete section. Whereas direct tensile resistance is the performance measurement required for design, the steel-fiber industry has yet to actively employ direct tensile testing of steel fibers. The tensile response of steel-fiber-reinforced concrete has been investigated. The primary purpose of this paper is to present a robust new direct tension test method. This method is able to determine the uniaxial tensile response of steel-fiber-reinforced concrete. The method uses a three-dimensional “hourglass”-shaped tapered specimen. This paper also focuses on developing a practical method to determine the average tensile force per fiber.

Isothermal vapour-liquid equilibrium data for the binary systems 2-propanone + (2-butanol or propanoic acid)

Isothermal vapour-liquid equilibrium (VLE) data were measured for 2-propanone + 2-butanol at (333.15 and 353.15) K and 2-propanone + propanoic acid at (333.15, 353.15, and 373.15) K. For the sub-atmospheric pressure measurements, a dynamic recirculating VLE glass still operated isothermally was used, whilst a novel recirculating stainless steel of similar architecture, capable of operating at pressures up to 750 kPa was used for measurements above atmospheric pressures. The experimental VLE data for the 2-propanone + 2-butanol system at (333.15 and 353.15) K were correlated to the Wilson and NRTL models using the gamma-phi approach with the Hayden and O'Connell correlation employed for calculating the second virial coefficients. For the 2-propanone + propanoic acid system, the considerably more complex iterative procedure of Prausnitz et al. [J.M. Prausnitz, T.F. Anderson, E.A. Grens, C.A. Eckert, R. Hsieh, J.P. O'Connell, Computer Calculations for Multicomponent Vapour-Liquid and Liquid-Liquid Equilibrium, Prentice- Hall, New Jersey, 1980] was utilized to account for acid dimerization in the vapour phase. In the computational procedure for finding liquid phase activity coefficients, true species vapour phase mole fractions (ηi) are solved for, with the equilibrium association constant, Ki emerging from the computations. The thermodynamic consistency of the data was verified through the point and direct test methods of Van Ness.

Fiber orientation distribution and tensile mechanical response in UHPFRC

In this study, the crucial effect of the fiber orientation distribution on the tensile mechanical response of ultra high performance fiber reinforced concretes (UHPFRC) is discussed. A direct tension test method was used to characterize the tensile response of a UHPFRC material as well as to assess the actual tensile response along the principal directions in a real-scale UHPFRC structural element. Moreover, the actual fiber orientation distribution was evaluated in representative sections through an image analysis technique. The experimental results validated the anisotropy in the fiber orientation distribution and, consequently, in the tensile mechanical properties as a consequence of the casting process and the flow pattern. The concept of the fiber orientation factor was discussed as well as the approaches currently adopted to implement robust and reliable safety factors accounting for the fiber orientation distribution impact on the design methodologies for UHPFRC. Finally, the need of a comprehensive design framework for UHPFRC structures was highlighted in order to allow for fully exploitation of the material properties.

Frictional and Interface Frictional Characteristics of Multi-layer Cover System Materials and Its Impact on Overall Stability

The municipal and hazardous landfills nearing its design capacity need to be isolated from the atmosphere using multi-layered cover system (MLCS). These MLCS constitutes different layers of soil and geosynthetics with widely varying properties. Each of these layers fulfil specific requirements by acting as a surface protection, drainage, separation, filtration and hydraulic barrier layers of MLCS. Failure of these MLCS leads to waste–atmosphere interaction and results in extremely hazardous situation to biosphere. The stability of MLCS significantly depends on the shear strength characteristics of materials used viz., the internal frictional characteristics of individual soil materials and interface frictional characteristics of soil–soil or soil–geotextile combination. In view of this, frictional characteristics of four type of soils, four soil–geotextile interfaces and one soil–soil interface was determined using direct shear and modified direct shear testing methods. The modification of geomembrane used in barrier layer was also attempted, for improving its interface shear characteristics. The usefulness of the above parameters and the influence of its variability on the slope stability of MLCS of a near surface low level radio-active waste disposal facility (NSDF) is demonstrated in this study.

Shear Properties of the Strain Hardening Cementitious Composite Material

AbstractRecently, strain hardening cementitious composite (SHCC) material has been used for the shear strengthening and the structural rehabilitation of reinforced concrete structures. However, the shear behavior of this material has not been yet fully understood due to lack of an appropriate and accurate direct shear test method. This paper aims to investigate the shear properties of the SHCC material. For this purpose, Iosipescu shear test was selected, where loads are applied in antisymmetric four-point bending, assuring a pure shear section at the center of the specimen. A special geometry for the specimen was adopted in order to assure a uniform shear stress distribution in the pure shear section. This experimental test can characterize the shear behavior of SHCC material. The experimental test was simulated by the finite element method (FEM)-based computer program, FEMIX. To predict the average shear stress–sliding response, the shear crack softening diagram, available in the multidirectional fixed ...