Landslide Susceptibility Assessment of a Part of the Western Ghats (India) Employing the AHP and F-AHP Models and Comparison with Existing Susceptibility Maps

Landslides are prevalent in the Western Ghats, and the incidences that happened in 2021 in the Koottickal area of the Kottayam district (Western Ghats) resulted in the loss of 10 lives. The objectives of this study are to assess the landslide susceptibility of the high-range local self-governments (LSGs) in the Kottayam district using the analytical hierarchy process (AHP) and fuzzy-AHP (F-AHP) models and to compare the performance of existing landslide susceptible maps. This area never witnessed any massive landslides of this dimension, which warrants the necessity of relooking into the existing landslide-susceptible models. For AHP and F-AHP modeling, ten conditioning factors were selected: slope, soil texture, land use/land cover (LULC), geomorphology, road buffer, lithology, and satellite image-derived indices such as the normalized difference road landslide index (NDRLI), the normalized difference water index (NDWI), the normalized burn ratio (NBR), and the soil-adjusted vegetation index (SAVI). The landslide-susceptible zones were categorized into three: low, moderate, and high. The validation of the maps created using the receiver operating characteristic (ROC) technique ascertained the performances of the AHP, F-AHP, and TISSA maps as excellent, with an area under the ROC curve (AUC) value above 0.80, and the NCESS map as acceptable, with an AUC value above 0.70. Though the difference is negligible, the map prepared using the TISSA model has better performance (AUC = 0.889) than the F-AHP (AUC = 0.872), AHP (AUC = 0.867), and NCESS (AUC = 0.789) models. The validation of maps employing other matrices such as accuracy, mean absolute error (MAE), and root mean square error (RMSE) also confirmed that the TISSA model (0.869, 0.226, and 0.122, respectively) has better performance, followed by the F-AHP (0.856, 0.243, and 0.147, respectively), AHP (0.855, 0.249, and 0.159, respectively), and NCESS (0.770, 0.309, and 0.177, respectively) models. The most landslide-inducing factors in this area that were identified through this study are slope, soil texture, LULC, geomorphology, and NDRLI. Koottickal, Poonjar-Thekkekara, Moonnilavu, Thalanad, and Koruthodu are the LSGs that are highly susceptible to landslides. The identification of landslide-susceptible areas using diversified techniques will aid decision-makers in identifying critical infrastructure at risk and alternate routes for emergency evacuation of people to safer terrain during an exigency

Analysis of cellulose nanocrystal rod lengths by dynamic light scattering and electron microscopy

A method to characterize the length (L) of rod-like cellulose nanocrystal (CNC) particles is described. It is based on dynamic light scattering (DLS) and electron microscopy. Measurement of translational diffusion coefficient from DLS along with diameter measurements from electron microscopy is used in Broersma translational diffusion coefficient equation to calculate the CNC particle L. For wood based CNC rods, diameter of 15 nm measured by scanning electron microscopy (SEM) and translational diffusion coefficient of 5.21 7 10 -12 m2/s measured by DLS give particle L of 271 nm from Broersma's relation. This one and other calculated L values for various rod-like particles are in good agreement with the L of the particles measured either by transmission or SEM. \ua9 2013 Springer Science+Business Media Dordrecht.Peer reviewed: YesNRC publication: Ye

Flocculation of cellulose nanocrystals by adsorbing and non-adsorbing polymers

Peer reviewed: YesNRC publication: Ye

Surface modification and dispersion of nanocrystalline cellulose in organic media

Peer reviewed: YesNRC publication: Ye

Nanocomposites of nanocrystalline cellulose for enzyme immobilization

We describe the synthesis, characterization and use of a composite material made of a renewable source and metallic nanoparticles for biosensing applications. Nanocrystalline cellulose (NCC) is a product isolated from natural cellulose fibers, which is of approximately 100 nm long and 10 nm wide in size. We augmented the surface area and tailored the chemical affinity of NCC by optimally dressing it with gold nanoparticles (AuNPs). The deposition of AuNPs on NCC was controlled by using cationic polyethylenimine (PEI) at different pHs. AuNPs were thiol-functionalized using different linkers prior to enzyme immobilization. The enzyme (glucose oxidase or GOx) was conjugated on the composite by carbodiimide coupling, and subsequent activation of linker-carboxylic acid group. Our results showed that GOx was attached to the surface of the NCC nanocomposite. Moreover, the amount of GOx loaded onto the support depended on the length of the thiol-linker used. The lower value (20. 3 mg/mg of support) was obtained with the longer thiol-linker (11 carbon chain) compared to 25. 2 mg/mg of support for the smaller thiol-linker (3 carbon chain). \ua9 2012 Springer Science+Business Media Dordrecht.Peer reviewed: YesNRC publication: Ye

Nanocomposites of nanocrystalline cellulose for biosensor applications

In this work, we describe the use of a composite material made of a renewable source and metallic nanoparticles for biosensing applications. NCC is a product isolated from natural cellulose fibers, which is of approx. 100 nm long and 10 nm wide in size. We augmented the surface area and chemical affinity of NCC by optimally dressing it with gold nanoparticles (AuNP). The deposition of AuNP on NCC was controlled by using cationic Polyethylenimine (PEI). AuNPs were thio-funtionalized prior to enzyme immobilization and the enzyme (glucose oxidase) was conjugated on the composite by carbodiimide (EDC)/NHS coupling. Using UV-visible and fluorescence spectroscopy in the presence of a specific substrate we monitored the activity of the immobilized enzymes, and its efficiency was compared with that of the enzyme in free form. Our results using FT-IR and SEM show that thiol-AuNPs were attached to the surface of NCC. The enzymes activity were measured and quantified using different kit assays and proved that the enzymes were attached to the support and maintained their activity.Peer reviewed: YesNRC publication: Ye

Graphitic carbon nanoparticles from asphaltenes

We report preliminary studies on the preparation of carbon nanoparticles (CNPs) of 3c20 nm in diameter derived from asphaltenes under mild conditions. This transformation occurred upon heating a thin film of asphaltenes cast on a carbon coated copper grid under both nitrogen and oxygen atmosphere. The resulting CNPs were characterized by thermogravimetric analysis (TGA), scanning/transmission electron microscopy (SEM/STEM), transmission electron microscopy (TEM), elemental analysis (EA) and Auger electron spectroscopy (AES). The findings point towards asphaltenes, a crude oil by-product, as a potential source for carbon nanomaterials. \ua9 2011 Materials Research Society.Peer reviewed: YesNRC publication: Ye

Flocculation of bacteria by depletion interactions due to rod-shaped cellulose nanocrystals

We report depletion induced flocculation and phase separation of bacteria due to the presence of rod-shaped nanoparticles by using confocal laser microscopy and turbidity measurements. To investigate the depletion effect of rod shaped nanoparticles in bacteria systems, cellulose nanocrystals with length, L= 90 ± 10. nm, diameter, D= 8 ± 1. nm and zeta potential of 51.5 ± 0.8. mV was used. The flocculation of the Gram-negative bacterium Pseudomanas aeruginosa (average length = 1.2 μm, width = 0.2 μm) was tested. The zeta potential of P. aeruginosa suspended in 10. mM NaCl was -29.84 ± 0.6. mV. Bacterial flocculation was observed at the CNC concentration of less than 0.1% due to the depletion effect. We conclude from our results that rod shaped nanoparticles are very effective for the depletion flocculation of colloidal size bacteria and that phase separation of bacteria can occur at very low concentrations of rodlike CNC particles.</p