Slope Factor Research Articles

Vertical distribution differences of the understory herbs and their driving factors on shady and sunny slopes in high altitude mountainous areas

The vertical distribution understanding of undergrowth herbaceous plants in high altitude mountain areas is of great significance to reveal the environmental gradient change law of plant diversity. However, the species composition of herbaceous plants at different altitude gradients and the relationship between diversity and environmental factors is still vague. This study takes the Sejila Mountain in southeast Tibet at an altitude of 2,000–3,300 m as the study area to analyze the vertical distribution differences of the understory herbs and their driving factors on shady and sunny slopes. The results showed that: (1) The number of families, genera and species of herbaceous plants on sunny slope is greater than that on shady slope. Asteraceae on shady and sunny slopes has the largest number of species; (2) The α diversity index of the herbs on shady slope shows a U-shaped trend. The Cody heterogeneity index (βC) is negatively correlated with the β diversity index. The herb richness index (R) on sunny slope is unimodal. The β diversity index displays the same as that of shady slope; (3) Different environmental factors have different effects on herb diversity. The correlation between environmental factors and diversity indicators indicates that there is a certain degree of clustering among samples. The environmental factors of shady slope and sunny slope are separated; and (4) The difference of water and heat conditions caused by altitude and slope aspect is an important driving factor for the diversity of herbage species, followed by soil clay content, silt content and slope gradient. This study will help to understand the species diversity and ecosystem characteristics of the region, and provide a reference for the study of plant community structure and function and rational utilization of understory plant resources in high-altitude mountain areas.

Characterization of two pathological gating-charge substitutions in Cav1.4 L-type calcium channels

ABSTRACT Cav1.4 L-type calcium channels are predominantly expressed at the photoreceptor terminals and in bipolar cells, mediating neurotransmitter release. Mutations in its gene, CACNA1F, can cause congenital stationary night-blindness type 2 (CSNB2). Due to phenotypic variability in CSNB2, characterization of pathological variants is necessary to better determine pathological mechanism at the site of action. A set of known mutations affects conserved gating charges in the S4 voltage sensor, two of which have been found in male CSNB2 patients. Here, we describe two disease-causing Cav1.4 mutations with gating charge neutralization, exchanging an arginine 964 with glycine (RG) or arginine 1288 with leucine (RL). In both, charge neutralization was associated with a reduction channel expression also reflected in smaller ON gating currents. In RL channels, the strong decrease in whole-cell current densities might additionally be explained by a reduction of single-channel currents. We further identified alterations in their biophysical properties, such as a hyperpolarizing shift of the activation threshold and an increase in slope factor of activation and inactivation. Molecular dynamic simulations in RL substituted channels indicated water wires in both, resting and active, channel states, suggesting the development of omega (ω)currents as a new pathological mechanism in CSNB2. This sum of the respective channel property alterations might add to the differential symptoms in patients beside other factors, such as genomic and environmental deviations.

Study on Soil Erosion Driving Forces by Using (R)USLE Framework and Machine Learning: A Case Study in Southwest China

Soil erosion often leads to land degradation, agricultural production reduction, and environmental deterioration, which seriously restricts the sustainable development of regions. Clarifying the driving factors of soil erosion is the premise of preventing soil erosion. Given the lack of current research on the driving factors/force changes of soil erosion in different regions or under different erosion intensity grades, this paper pioneered to use machine learning methods to address this problem. Firstly, the widely used (Revised) Universal Soil Loss Equation ((R)USLE) framework was applied to simulate the spatial distribution of soil erosion. Then, the K-fold algorithm was used to evaluate the accuracy and stability of five machine learning algorithms for fitting soil erosion. The random forest (RF) method performed best, with average accuracy reaching 86.35%. Then, the Permutation Importance (PI) and the Partial Dependence Plot (PDP) methods based on RF were introduced to quantitatively analyze the main driving factors under different geological conditions and the driving force changes of each factor under different erosion intensity grades, respectively. Results showed that the main drivers of soil erosion in Chongqing and Guizhou were cover management factors (PI: 0.4672, 0.4788), while that in Sichuan was slope length and slope factor (PI: 0.6165). Under different erosion intensity grades, the driving force of each factor shows nonlinear and complex inhibitory or promoting effects with factor value changing. These findings can provide scientific guidance for the refined management of soil erosion, which is significant for halting or reversing land degradation and achieving sustainable use of land resources.

The deformation evolution law and stability evaluation of the high-filled slope in the cutting hills to backfill ditches project

The cutting hills to back ditches (CHBD) project has been widely implemented since urbanization in hilly areas is steadily rising. The stability of the high-filled slope and the problem of foundation settlement deformation has become one of the vital issues for safe construction. This paper focused on the deformation evolution law and stability assessment of the high-filled deposit slope composed of the soil-rock mixture (S-RM) in the CHBD project, in Shiyan City, Hubei Province as examples. First, large-scale direct shear tests of S-RM with different rock block proportions (RBPs) under different various normal stresses were carried out, and its mechanical properties were analyzed. Next, the finite element method was used to simulate the processes of the step-by-step filling, and the deformation evolution law was analyzed. Then, the limited equilibrium method (LEM) was used to obtain the potential sliding surfaces and the corresponding safety factors of the high-filled slope, and the safety of the construction was assessed. Finally, automated monitoring of the step-by-step settlement and deep soil deformation was computerized for the typical locations, and the long-term stability of the high-filled slope was studied. The results demonstrate that the first layer of backfill in the F area contains the largest incremental settlement displacement in the y-direction, whereas the value in the G area occurs at the site of the fill layer close to the slope surface at each filling timestep. The displacement response value steadily declines with the increasing filling depth and horizontal displacement, presenting a clear spatial influence range, with the site of maximum incremental displacement as the center. After filling, the safety factors of the potential sliding surface in the F and G areas are 2.531 and 1.118, respectively, and the slope is in a stable state. The monitoring data show that the deformation mostly takes place within 10 m of the surface. The study’s findings are thought to offer technical and practical knowledge for the slope risks.

Gambier (Uncaria gambir Roxb.) Plant Productivity Relation Based On Growing Altitude In Lima Puluh Kota Regency

Gambier cultivation location is usually carried out on sloping land which results in decreased land carrying capacity due to soil erosion. This research was to determine whether the factors of altitude and slope are related to the production of gambier plants and other factors related to gambier production. This research was conducted in Lima Puluh Kota Regency, West Sumatra in September 2020. The data collection methods is to use the interview method, observation and document study. Interview and observation methods were used to obtained gambier production data, gambier harvesting, gambier processing, general conditions of the research location, visual appearance of soil erosion, height of the gambier growing area, topography and soil type. Indirect data were collected using the document study method. The selection of informants was carried out by purposive sampling with a total of 10 people. Data analysis used qualitative descriptive analysis by linking the informants 'answers with document studies, then doing a description in the form of gambier production as outlined in the informants' responses. Altitude has no relation to the production of gambier, but the factors of price, treatment process, soil type and the choice of mixed plant species are factors related to gambier production in Lima Puluh Kota Regency. The slope factor has no relation to the production of gambier in Lima Puluh Kota Regency. Land owners still observe the principles of soil and water conservation by applying mulch (ground cover) from the dregs of gambier and conducting mixed planting with seasonal and annual plant types.

State of human tiger conflict around Gunung Leuser National Park in Langkat Landscape, North Sumatra, Indonesia

Abstract. Patana P, Alikodra HS, Mawengkang H, Harahap RH. 2023. State of human tiger conflict around Gunung Leuser National Park in Langkat Landscape, North Sumatra, Indonesia. Biodiversitas 24: 837-846. The Sumatran tiger (Panthera tigris sumatrae) is one of the key species which is considered an endangered species by the IUCN (2008). There has also been a recent threat to their population due to conflict with humans. Information about landscape characteristics and livelihood related to human-tiger conflict (HTC) is needed for a proper mitigation strategy based on local parameters. Therefore, this study was carried out around Gunung Leuser National Park (GLNP) using quantitative and qualitative methods. Principal component analysis (PCA) was used to analyze and map the risk of HTC using landscape characteristics. The physical factors, including land cover, slope, elevation, distance from rivers, and settlement, were analyzed. The livelihood aspect related to land use change was described descriptively and became a major analysis. The study area is located in the buffer zone of GLNP in Langkat District. The results showed that the Eigen weight value for the slope, elevation, and land cover factor was greater than the distance to the river and settlement. The spatial analysis also revealed that Langkat Landscape was in the medium risk of HTC by covering 60% area, while 40% was in the interval of high to very high risk. Furthermore, the high dependence on land for agriculture and the activity of livestock has become a trigger for more massive HTC in the last three years. It is a challenge in human-tiger conflict mitigation to involve the resolution of people’s livelihoods surrounding the national park. The livelihood approach could be a future solution that bridges human and tiger aspects, in addition to habitat management and protecting conservation areas.

Impact of Solidified Municipal Sludge as Temporary Covering Soil on the Stability of Landfill Slope

Solidified municipal sludge is widely used as temporary covering soil in landfill. Due to the complex leachate of landfill, solidified municipal sludge has the problems of stagnant water and strength degradation. In order to investigate the influence of solidified municipal sludge on the stability of landfills, a landfill slope model with SEEP/W and SLPOE/W was established, using the actual infiltration as the boundary condition. Based on the changes in permeability and strength of the intermediate overburden layer, the migration law of leachate in a landfill under the condition of an intermediate overburden layer was analyzed. The relationship between landfill slope safety, climatic conditions and deterioration of the intermediate overburden layer was further explored. The results show that the permeability of the intermediate overburden layer affects the distribution of leachate and the height of stagnant water. During the rainstorm period, the safety factor of the landfill slope decreased rapidly from 1.4 to 1.0 or even lower. With the decrease in the shear strength of the intermediate overburden, the safety factor of the landfill slope was reduced to less than 1.0. Therefore, maintaining the permeability and strength of solidified municipal sludge at a certain level is required to ensure the safety and stability of landfill slopes.

N-nitrosamines in Qingdao dried aquatic products and dietary risk assessment

ABSTRACT N-nitrosamines are human carcinogens commonly present in dried aquatic products. A method of gas chromatography – mass spectrometry combined with steam distillation was developed for the determination of 9 N-nitrosamines in dried aquatic products in Qingdao, China, with which 300 samples of fish, squid, shrimp and sea cucumber collected from Qingdao were analysed. A health risk assessment was conducted based on determined levels of N-nitrosamines by using estimated daily intake and slope factors. Results showed that fish products was the category with the highest content of N-nitrosamines, whereas squid and shrimp products were the categories with the highest frequency of presence of N-nitrosamines. The average estimated cancer risk of N-nitrosamines in dried aquatic products in Qingdao ranged from 3.57 × 10−8 to 3.53 × 10−5. Nitrosodimethylamine, N-Nitrosodiethylamine and N-Nitrosodibutylamine could be considered to pose a potential cancer risk to residents in Qingdao.

Shape from spectra

We introduce a new unified atmospheric–topographic correction approach that estimates surface geometry directly from the radiance measurement. Surface topography influences the at-sensor radiance measurement, making precise topography modeling critical in applications like vegetation or snow studies in mountainous terrain. Currently, elevation maps are used to derive topographic variables such as the slope and sky-view factor. This process is error-prone since static global digital elevation models do not generally achieve the accuracy required, and even minor mismatches in spatial resolution can introduce significant artifacts in downstream processing. Here we demonstrate that it is possible to estimate topographic parameters directly from spectral data, ensuring perfect physical consistency, temporal coincidence, and spatial alignment. We present experiments estimating topographic slope in two scenes in Southern California, with data from NASA’s Next Generation Airborne Visible/Near Infrared Imaging Spectrometer (AVIRIS-NG). We compared our radiance-based estimates against high-resolution lidar datasets. Our initial validation result showed a correlation of R2=0.864 (n=160) over the homogeneous surface of Beckman Auditorium’s cone-shaped roof on the Caltech campus in Pasadena, California. We then validate the model over a larger study site near Santa Clarita, California, finding R2=0.923 (n=40,000) in a 350×350 m area. The accuracy of our model estimates, combined with its systematic advantages over the alternative, show the potential of the approach for use in both airborne campaigns and orbital missions.

Scale Effect of Sloping Landscape Characteristics on River Water Quality in the Upper Reaches of the Si River in East-Central China

Landscape composition and configuration determine the source of pollutants. They also determine the interception and pollution-holding potential of the surface landscape. Using the upper reaches of the Si River Basin, a major grain-producing region in Shandong province in east-central China, as a case study, this study analyzed the influence of landscape characteristics on river water quality (RWQ) after superimposing topographic slope factors for 2017, and investigated which spatial scale had the strongest influence on RWQ. The landscape indices of three spatial scales (riparian zone, river reach and sub-catchment) and three slope scales (general land, flat ground and steep slope) were extracted. Correlation analysis and redundancy analysis were used to reveal the effects of landscape characteristics on RWQ at different scales. The results indicate that the landscape types were dominated by arable land and construction land in 2017. Landscape indices at different scales were significantly different. The RWQ generally met Class II or III surface water quality standard. Arable land and construction land had a negative impact on RWQ, both of which were “source” landscapes, while forest was a “sink” landscape that can effectively alleviate the deterioration of RWQ. The eight landscape indices which indicated heterogeneity, fragmentation level, landscape diversity, and shape information had different degrees of correlation with NO3−-N, NH4+-N, CODMn and BOD5. Different scales of landscape features had different correlations with RWQ, with the strongest correlation in the riparian zone, followed by the river reach, and the weakest in the sub-catchment. The influence of steep slope land was higher than that of flat ground land. The study confirmed that landscape structure and configuration had a scale effect on RWQ. It thus has great significance for water resources protection and land use management in the study area.

Assessment of Soil Erosion Hazards in Kambiti Subcatchment, Murang’a County, Kenya

Erosion is a global problem that destroys soil and adversely affects ecosystem productivity. Soil erosion generally involves many processes but the major activities involve particles being transported and deposited to another location. With an increasing population, soil erosion, water availability, energy production, and biodiversity loss are some of the most pressing environmental problems around the world. Erosion is a hazard associated with agriculture in tropical and semi-arid areas. Kambiti sub catchment is part of the upper Tana catchment. The upper Tana catchment includes 25% of Kenya gazette forest. A large area of land has been degraded, resulting in a drastic reduction in surface water availability during the dry season and poor-quality water during the wet season caused by high silt levels. The main objective of the study is to assess erosion hazards using RUSLE model in Kambiti sub catchment area, Murang’a County. The specific objectives of the study were to determine the effect of rainfall erosivity and soil erodibility factor in Kambiti Sub catchment area in Murang’a County, to determine effect of slope factor to soil loss in Kambiti Sub-catchment area in Murang’a County, to determine the effect of crop protection and management factor in Kambiti Sub catchment area in Murang’a County to soil loss and to determine the strategies for management of soil and water in Kambiti Sub catchment area in Murang’a County. Data was collected from the catchment and analyzed using arc Geographical Information System to obtain the specific parameters in the revised universal soil loss equation model. Interpolation method was used to determine the mean annual precipitation. The k factor is a function of soil texture. Shape file for geological structure for Kenya was obtained from Kenya Agriculture and livestock Research Organisation and analyzed by use of arc GIS to obtain soil erodibility factor. The slope factor was analyzed using digital elevation model from arc view. Digital elevation model was gotten from STRM download. The C factor was derived from Landsat imagery from sentinel of 30metres by 30 metres. It was further analysed by unsupervised classification from Arc GIS. The sentinel clip of Kambiti sub-catchment was joined with ground trothing observations. The results were useful in estimation of soil loss therefore profiling the areas prone to soil loss. Study findings indicated rain drop impact and runoff were primarily responsible for causing erosion in Kambiti sub catchment. Anthropogenic factors played an important role in amplifying the severity of the damage, such as persistent vegetative degradation and destruction of soil structure due to organic matter depletion and routine shallow tillage. In recent years, erosion control has been hampered by the occurrence of gaps in knowledge regarding the integrated nature of erosion processes, leading to land damage caused by rill and inter-rill erosion going unaddressed. Poor people and those lacking capital to invest in reclaiming land are the main causes of abandoning degraded land. Through strategic awareness campaigns and education, soil erosion will be assessed and the knowledge gap will be closed. Participation of farmers in land use decisions is inevitable as it ensures that people who utilize land resources are recognized as equal partners in identifying problems and designing solutions. It was also recommended that Identification and operationalization of alternative off-farm income.

Stand and tree characteristics influence damage severity after a catastrophic hurricane disturbance

Catastrophic wind disturbances can greatly impact the economic and ecological values of working forests worldwide. For example, Hurricane Michael caused severe economic damage in 2018 to commercial loblolly (Pinus taeda L.) and slash (Pinus elliotti Engelm.) planted pine stands in the southeastern U.S. This project examined the relative importance of prior management activities, stand characteristics, and soil and terrain attributes in predicting stand damage from a catastrophic hurricane event. We assembled data from land managers in coastal Alabama, the Florida panhandle, and South Georgia, on percent loss of trees after Hurricane Michael in over 400 stands, along with stand management history, and stand characteristics. Digital elevation models were utilized to determine terrain and hydrological characteristics of the landscape including aspect, channel distance, elevation, LS factor (slope and length steepness factor), slope angle, slope position, terrain ruggedness index, topographic wetness index, and wind exposition index. Random forest models were used to determine the relative accuracy of windspeed, management history, stand characteristics, and soil and terrain attributes in predicting stand damage. From the variables evaluated, stand density (as described by trees per acre), and tree height (as described by the average height of dominant and co-dominant trees) were among the most influential characteristics in predicting damage severity along with windspeed and linear distance from the coast. Stands with dominant heights > 14 m, trees per acre < 600 (trees per hectare < 1,483), and within 50 km of the coast were the most likely to experience severe damage. Topographic wetness index was the most influential terrain characteristic, with sands in wetter soils more likely to experience more severe damage. Recently thinned stands were slightly more vulnerable to severe damage. Results from this study can be used to develop vulnerability profiles for commercial pine stands in the coastal plain region in the southern U.S. region.

Suitability Assessment of Small Dams’ Location as Nature-Based Solutions to Reduce Flood Risk in Mataniko Catchment, Honiara, Solomon Islands

As global temperatures rise, flooding and storm surges caused by extreme weather threaten people’s safety and nations’ development. Nature-based Solutions (NBS) are practical actions to support resilience to reduce flood risk and are applied in many countries. As the NBS approach mentions, small check dams made of gabion and wood can retain runoff and temporarily create detention basins to reduce the magnitude of floods and provide additional water resources. However, previous dam suitability research emphasized the criteria selection and decision method evolution, which costs time on the complex calculation and does not fit the NBS small dams. This research aims to optimize the site selection workflow of small dams in vulnerable informal settlements by utilizing Remote Sensing (RS), Geographic Information Systems (GIS), and Multi-Criteria Evaluation (MCE). Several thematic layers, such as land use, river density, building distance, vegetation cover index, slope, and elevation factors, were chosen to identify the suitable area in Mataniko catchment, Honiara. More importantly, it provides a more efficient model builder that can be replicated in ArcGIS 10.8, which contributes to visualizing scenarios of the inundation area of small dams at different heights. As a result, this study tested up to 35 potential small dams with 2.5 and 5 m wall height in the flood-prone Vara Creek and selected nine small dams with 5 m height and 15 small dams at 2.5 m as the best locations according to the volume and area. Overall, it is an efficient tool for designers to communicate with different stakeholders and applies to other developing countries facing frequent floods. Moreover, it provides a prototype and evidence of NBS action to address the flood issue.

Investigating the Slope Stability and Factor of Safety Properties of Soil Reinforced with Natural Jute Fibers under Different Rainfall Conditions

Heavy rainfall is often responsible for embankment failures. During intense rainfall, the embankment slope inclination is vital for slope stability. Some failures occur in the slope due to heavy rainfall and sudden change in the matric suction. Jute fiber is a reinforcing material that is added to improve soil strength. In this research, in order to explore the effects of slope inclination on soil stability, soil samples were collected and exposed to artificial rainfalls. This study presented various tests performed on the soil samples. Different tests like sieve analysis, permeability test, Direct Shear Test (DST), liquid limit, plasticity limit, and numerical modeling were conducted in the laboratory. The study's findings revealed that the failure is caused by a soil suction loss when the inclination of the slope is higher than the soil friction angle and the collapse is caused by the positive water pressure at the slope's toe when it is lower than the soil's friction angle. Furthermore, when the slope angle increases, the slopes are becoming increasingly vulnerable to rapid collapse. After that, jute fibers were combined with the soil to improve its performance. Samples of 2, 3, and 4 rows of jute fibers were tested. These jute fiber samples performed better than the ones without fibers under different rainfall conditions. The distribution of jute fibers had a favorable influence on both strength measurements and safety aspects. Utilizing the factor of safety and matric suction, the performance of jute fiber samples is superior to those without jute fibers. Consequently, by adding jute fibers the stabilization of the soil is significantly improved along with its factor of safety.

An improved subthreshold swing expression accounting for back-gate bias in FDSOI FETs

In a MOSFET transistor, the subthreshold swing defines the switching efficiency, and the associated slope factor, or so-called body factor, is a critical parameter in charge-based models. However, in an advanced Fully-Depleted Silicon-On-Insulator (FDSOI) process, the slope factor is influenced by a strong back gate coupling due to a thin buried oxide (BOX). A conventional constant expression cannot describe the slope factor at various back-gate voltages. Therefore, this paper proposes a general slope factor expression for front- and back-gate transfer characteristics of long-channel FDSOI MOSFETs in a strong gate coupling. The proposed expression is a continuous function of the surface potential difference between the front and back sides, which explains the slope factor behavior versus the back-gate voltage. Besides, the systematic study is presented for the front/back interface states. The proposed model is applied to evaluate the down-scaling of FDSOI technologies in terms of the gate-coupled slope factor. The scaling in the buried oxide layer degrades the front slope factor, which a thinner channel or a reverse body bias can compensate for at the cost of a higher vertical electric field. Compared to the SiO2, the application of high-κ dielectric for the buried oxide layer shows a better stand to the degraded slope factor by the interface states.

Does the Cochrane-Piazzesi Factor Predict? An International Resampling Perspective

We employ the state-of-the-art resampling procedure designed by Crump and Gospodinov (2019) to assess the predictive ability of the benchmark Cochrane-Piazzesi return-predicting factor in four important Treasury markets. We find that i) it accounts for excess returns better than the slope; ii) it has a better economic performance than the slope factor and the unconditional “long-always” strategy; iii) its outperformance is not due to overfitting; and iv) it retains its greater predictive abilities out of sample.

Altered voltage-dependence revealed in an inactivation-deficient mutant of Nav1.4 via optogenetic PI(4,5)P2 dephosphorylation.

Voltage-gated sodium (NaV) channels are a key membrane protein of most excitable cells that activate upon depolarization, which initiates an action potential by rapid influx of Na+ ions. Voltage-dependent activation is followed by fast inactivation, which confers the refractory period for excitable tissues. Because the gating processes of NaV channels are mechanically coupled, changes in the fast inactivation process also alter their voltage-dependent activation properties. Most ion channels are regulated by membrane phospholipid phosphatidylinositol (4,5) bisphosphate (PI(4,5)P2), however the PI(4,5)P2 modulation of NaV channels has not been determined. The mutant channel NaV1.4-L435W-L437C-A438W (WCW) presents significantly attenuated fast-inactivation and expresses robustly in Xenopus oocytes. To study the effects of PI(4,5)P2 dephosphorylation on NaV1.4 activation in channels with attenuated fast inactivation, we expressed NaV1.4-WCW in Xenopus oocytes and recorded currents using two-electrode voltage-clamp (TEVC). To dephosphorylate PI(4,5)P2, we co-expressed 4’ or 5’ phospholipid phosphatases that are recruited to the cell membrane upon exposure to blue light (λ=470 nm). 4’ dephosphorylation of PI(4,5)P2 produced an 8 ± 2% increase in peak NaV1.4 WCW channel currents at a depolarizing pulse to −20 mV. Significantly greater channel currents at −15 mV and −25 mV were also observed. Similarly, 5’ dephosphorylation of PI(4,5)P2 resulted in a 15 ± 2% increase in Nav1.4 WCW peak channel currents. Significantly greater channel currents were observed in the voltage range from −20 mV to +20 mV. Although the peak currents were augmented, the half-maximal activation voltage (V1/2) and slope factor (Kact) of the WCW mutant were both unaffected by either dephosphorylation, suggesting that the altered voltage-dependence of this channel mutant is at least partially due to the effect of PI(4,5)P2 dephosphorylation on fast inactivation.

Analytical Stability Analysis of Rainfall-Infiltrated Slopes Based on the Green–Ampt Model

Rainfall infiltration can alter the pore-water pressure and decrease matric suction, which can lead to slope instability and landslides. Most of the previous numerical studies conducted on rain infiltration have assumed a two-dimensional (2D) failure mechanism, which neglects the three-dimensional (3D) characteristics of slopes. An analytical assessment framework was developed using the upper-bound theorem of limit analysis to determine the factor of safety and failure pattern in the case of a 3D vertical cut slope under diverse rainfall situations combined with the unsaturated soil mechanics. The Green–Ampt model was adopted to depict the infiltration process and the progression of the wetting front into the soil. The slope factor of safety was determined using the energy balance equation by adopting the strength reduction approach. The validity of the framework was verified using the numerical simulation method. The effects of duration, intensity, and patterns of rainfall and the 3D traits of slope on the slope failure pattern and stability were determined. A set of design charts was included for the preliminary design. The present study quantitatively determines the stability of slopes susceptible to rainfall infiltration.

Health risk assessment and metal contamination in fish, water and soil sediments in the East Kolkata Wetlands, India, Ramsar site

East Kolkata Wetlands (EKW) is an important site for fish culture in sewage-fed areas, which are major receivers of pollutants and wastages from Kolkata. EKW is internationally important as the Ramsar site was declared on Aug 2002 with an area of 125 km2. EKW is a natural water body where wastewater-fed natural aquaculture has been practiced for more than 70 years. It is ecologically vulnerable due to the discharge of toxic waste through sewage canals from cities. Assessing the EKW to understand the inflow and load of the toxic metal (s) in fish, water, and sediments samples is essential. The field (samples collection from 13 sites) and lab (determination of toxic level of metals) based research were carried out to assess metal toxicity and health risk assessment in EKW. The levels of eighteen metals (18), namely Chromium, Vanadium, Cobalt, Manganese, Copper, Nickel, Zinc, Silver, Molybdenum, Arsenic, Selenium, Tin, Gallium, Germanium, Strontium, Cadmium, Mercury, and Lead, were determined using Inductively coupled plasma mass spectrometry (ICP-MS) in five fish tissues viz. muscle, liver, kidney, gill and brain, along with the water samples and soil sediments in 13 sampling sites. The bioaccumulation and concentration of metals in fish tissues, soil sediments, and water samples were well within the safe level concerning the recommendation of different national and international agencies except for a few metals in a few sampling sites like Cd, As, and Pb. The geoaccumulation index (Igeo) was also determined in the soil sediments, indicating moderate arsenic, selenium, and mercury contamination in a few sites. The contamination index in water was also determined in 13 sampling sites. The estimated daily intake (EDI), reference dose (RfD), target hazard quotient (THQ), slope factor and cancer risk of Cr, Mn, Co, Ni, Cu, Zn, As, Se, Cd, Pb and Hg from fish muscle were determined. Based on the results of the present investigation, it is concluded that fish consumption in the East Kolkata Wetland (EKW) is safe. The effects of bioaccumulation of metals in muscle tissue were well within the safe level for consumption as recommended by WHO/FAO.

Development of a unified gradient theory for ion-pair chromatography using oligonucleotide separations as a model case

Ion-pair chromatography is the de facto standard for separating oligonucleotides and related impurities, particularly for analysis but also often for small-scale purification. Currently, there is limited understanding of the quantitative modeling of both analytical and overloaded elution profiles obtained during gradient elution in ion-pair chromatography. Here we will investigate a recently introduced gradient mode, the so-called ion-pairing reagent gradient mode, for both analytical and overloaded separations of oligonucleotides. The first part of the study demonstrates how the electrostatic theory of ion-pair chromatography can be applied for modeling gradient elution of oligonucleotides. When the ion-pair gradient mode is used in a region where the electrostatic surface potential can be linearized, a closed-form expression of retention time can be derived. A unified retention model was then derived, applicable for both ion-pair reagent gradient mode as well as co-solvent gradient mode. The model was verified for two different experimental systems and homo- and heteromeric oligonucleotides of different lengths. Quantitative modeling of overloaded chromatography using the ion-pairing reagent gradient mode was also investigated. Firstly, a unified adsorption isotherm model was developed for both gradient modes. Then, adsorption isotherms parameter of a model oligonucleotide and two major synthetic impurities were estimated using the inverse method. Secondly, the parameters of the adsorption isotherm were then used to investigate how the productivity of oligonucleotide varies with injection volume, gradient slope, and initial retention factor. Here, the productivity increased when using a shallow gradient slope combined with a low initial retention factor. Finally, experiments were conducted to confirming some of the model predictions. Comparison with the conventional co-solvent gradient mode showed that the ion-pairing reagent gradient leads to both higher yield and productivity while consuming less co-solvent.