Calibration of filter paper for measuring total soil suction

Geotechnical designs and analyses of earth structures and foundations exclusively involve the assessment and consideration of unsaturated soil shear strength. The laboratory testing equipment and methods for predicting the unsaturated soil shear strength are complicated and more expensive. The experimental program attempted to involve undrained triaxial and filter paper for evaluating the unsaturated soil shear strength of identically compacted clayey soil. This study undertakes a comparison of shear strength in clayey soil under undrained loads, examining both saturated and unsaturated conditions. A 60 kPa air entry suction value is the key point at which linearity between the unsaturated shear strength parameter Øb and effective friction Ø′ with 15° linear slopes turns to non-linearity. Unsaturated shear strength increased by 22.76% in optimally wet conditions, 52.68% in optimum conditions, and 77.81% in optimally dry conditions as compared to saturated shear strength. This study utilizes an artificial neural network (ANN) to predict clayey soil’s unsaturated shear strength, finding that the optimal ANN configuration (2-5-1 topology, Levenberg–Marquard optimization, and logsig transfer function) achieved high reliability with a correlation coefficient (R) of 0.9289 and mean square error values of 2.22, 7.12, and 3.012 for training, testing, and validation, respectively. This experimental investigation improves our understanding of clayey soil shear strength and emphasizes the importance of saturation and moisture content in geotechnical assessments under undrained loading conditions.

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Development and validation of a novel tool to measure tear volume in volumetric unit (microlitre) per minute “the standard international unit (SI) tear strip”

Balamurugan,

Bhattacharyya,

Sarma

2024

Indian Journal of Ophthalmology

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The Schirmer strip measures tear volume in millimeters. A major limitation of the Schirmer strip is that it does not measure tear volume in a volumetric unit. Furthermore, the linearity range, lower limit of detection (LLOD), and lower limit of quantification (LLOQ) are not established. In this context, we developed a new filter paper based tear volume strip, which measures tear volume in microlitres (a volumetric unit), with a defined linearity range, LLOD, LLOQ, as well as inter-day and intra-day variability. We used standard Whatman filter paper no. 41, measuring 40 × 5 mm. Balanced salt solution (BSS) was used as a tear surrogate. By placing a specific volume of BSS at one marked end of the paper, we measured the distance travelled by the BSS after one minute. Different volumes of BSS (0.5, 1, 2, 4, 8, and 16 μl) were used, and the distance travelled by the BSS drop was recorded. Linearity was evaluated, and the LLOQ and LLOD were determined. Scale data were generated within the linearity range (10 replicates for each). Percentage recovery was calculated, and inter-day and intra-day variation as well as intra examiner and inter examiner coefficients of variation (CV%) were evaluated. High linearity (r2 = 0.976) was observed across all the tested volumes (0.5–16 μl), However, linearity improved within the tested volume range of 1–8 μl (r2 = 0.996). With an LLOD of 0.538 μl and an LLOQ of 1.63 μl, data for the scale were generated from 2–8 μl. Overall, volumetric recovery ranged from 97.34%–104%. The intra-day CV% ranged from 4.576% (for 2 μl) to 1.911% (for 5 μl) and 1.71% (for 7 μl). The inter-day CV% ranged from 1.715 (7 μl) to 4.36% (for 2 μl). The intra examiner CV% ranged from 0.422% (for 7 μl) to 2.66% (for 2 μl). The inter examiner CV% ranged from 1.93% (7 μl) to 3.69% (for 2 μl). This new tear volume measuring tool (named SI tear strip) represents a valuable tool for the measurement of tear volume (in μl) per unit time. This tool may be very helpful for the quantitative evaluation of dry eye patients and functional assessment of lacrimal glands.

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Calibration of filter paper for measuring total soil suction

Cited by 3 publications

References 20 publications

Filter Paper Calibration Using Osmotic Coefficients to Measure Total Soil Suction

Filter Paper Calibration Using Osmotic Coefficients to Measure Total Soil Suction

Comparative analysis of saturated–unsaturated shear strength under undrained loading: Experimental validation and ANN prediction of clayey soils

Development and validation of a novel tool to measure tear volume in volumetric unit (microlitre) per minute “the standard international unit (SI) tear strip”

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