Knickpoints Research Articles

A Fluorescent Biosensor for Streptavidin Detection Based on Double-Hairpin DNA-Templated Copper Nanoparticles

In this paper, we developed a sensitive, label-free and facile fluorescent strategy for detecting streptavidin (SA) based on double-hairpin DNA-templated copper nanoparticles (CuNPs) and terminal protection of small molecule-linked DNA. Herein, a special DNA hairpin probe was designed and synthesized, which contained two poly T single-stranded loops and a nick point in the middle of the stem. Inspired by the concept of the terminal protection interaction, the specific binding of SA to the biotinylated DNA probe can prevent the exonuclease degradation and keep the integrity of DNA probe, which can be used for synthesizing fluorescent CuNPs as a template. Conversely, the DNA probe would be digested by exonucleases and therefore, would fail to form CuNPs without SA. After systematic optimization, the detection range of SA concentration is from 0.5 to 150 nM with a low detection limit of 0.09 nM. Additionally, the proposed method was also successfully applied in the biological samples. Finally, the proposed method is sensitive, effective and simple, and can be potentially applied for predicting diseases and discovering new drugs.

Segmentation and fault–monocline relationships in the Lapstone Structural Complex, Sydney Basin, New South Wales

The 95 km-long Lapstone Structural Complex is a segmented structural association consisting of north-trending faults and monoclines in the western Sydney Basin between the Cumberland Basin to the east and lower Blue Mountains to the west. It has developed in a compressional regime. At depth, the Lapstone Structural Complex is most likely a deeply penetrating, west-dipping thrust fault that is seismogenic in the brittle middle crust. This structure has propagated upwards into the overlying Sydney Basin in the top ∼3 km of the crust and formed a suite of distinct fault and fault–monocline structures, including: (a) in the north, inferred imbricate faults at depth in the lower Sydney Basin dying out upwards into a well-displayed, major east-facing monocline (central limb has an overall consistent <20°E dip); (b) in the middle part of the complex, an east-facing monocline with dips increasing from west to east formed as a fault-propagation fold; and (c) as found in the south, a single thrust fault (Bargo and Nepean faults). The complex has a probable late Cenozoic age and has played a role in landscape development as shown by topography, uplifted river gravels and knick points along lower order streams. Therefore, it has formed late in the uplift history of the southeastern Australian highlands postdating uplift in the Cretaceous and uplift associated with basaltic eruptions in the Cenozoic. KEY POINTS The Lapstone Structural Complex is an association of segmented faults and monoclines formed at the tip of a deep-seated thrust fault. The largest structure in the complex is a gently east-dipping monocline formed above an inferred imbricate fault system in the lower Sydney Basin succession. Much of the middle and southern parts of the complex are single faults and a fault-propagation monocline related to a thrust fault at depth. The Lapstone Structural Complex is of late Cenozoic age and is most likely seismogenic.

Structural geometry, kinematics and paleostress of the Main Boundary Thrust: New constraints from the Hazara-Kashmir syntaxis, Northwest Himalayas, Pakistan

• The two separate faulting phases are preserved along the shear zone of the Main Boundary Thrust. • These fault zone fabrics help in relative time reconstruction of tectonic events based on displaced relationships, cross-cutting, and overprinting. • The stress regime changes along the Main Boundary Thrust (MBT) compressional in the east and transpressional in the west. • The variation in fold axis trendings, axial planes, and inclined to steep plunges of folds results from deformation and cross folding. The Himalayan fold and thrust belt in Kashmir is investigated for structural geometry, kinematics, and Paleostress analysis of Main Boundary Thrust along the eastern limb of the Hazara Kashmir syntaxis, Northwest Himalayas , Pakistan. The Precambrian to Cenozoic cover stratigraphic unit of the Indian plate is imbricated and faulted along the Main Boundary Thrust (MBT). The Main Boundary Thrust separates the Late Proterozoic Dogra Formation and Permo-Triassic Panjal Group of rocks from the Murree Formation molasses of Early Miocene . The faults and folds along Main Boundary Thrust are developed due to the Tertiary Himalayan collision. The regional strike of the area is northwest-southeast, and dip changes from northeast to southwest. The brittle lineations found at the surface of faulted rocks are deformed and displaced. Slickensides are mainly calcite and quartz coated. The coated surfaces of slickenside with the calcite fiber crystal growth or quartz reveal earlier origin prior to the slickenside surfaces, uncoated or fresh polished. These older slickensides show older thrust movement along the Main Boundary Thrust Fault , and uncoated fresh slickensides horizontal to sub-horizontal in trend shows strike-slip movement. The features like offset streams (Neelum River), displaced drainages (Panjkot nalla), triangular facets, displaced ridges, uplifted terraces, nick points, and seismicity associated with Main Boundary Thrust show that fault is an active fault. In the footwall of the Main Boundary Thrust, the Z-type drag folds developed as a result of extreme deformation at various localities. These Z-type folds along fault indicate pure thrust movement subordinate strike-slip sense of shear. The paleostress analysis and shear indicators yield the detailed kinematics history of the Main Boundary Thrust. Due to stress in this region, the movement's characteristics, together with outcrop structures, indicate clearly that brittle deformation exists along the Main Boundary Thrust. The present analysis of kinematics indicators fault-related slickensides, conjugate fractures, folding, dragging, faulting, shearing, and paleo stress analysis shows that pure thrust with subordinate strike-slip movements present in the eastern limb of Hazara Kashmir Syntaxis along the Main Boundary Thrust.

Extractions Morphotectonic Features Using Satellite Data Processing and DEM-Derived Spatial Models

Morphotectonic features were investigated in the Shireen anticline, which is located in the Kurdistan region of northern Iraq to get more insight into the effect of the tectonic activity on this anticline. For deducing and illustrating the morphotectonic features of the anticline, some digital processing methods have been applied to the part of the image of Landsat in which this anticline appears, and using the Digital Elevation Model. The results explained the identification of such morphotectonic features such as faults, joints, and flat irons topography, and then updated the structural style of the anticline by identifying and drawing the inferred morphotectonic features. The tectonic activity was evaluated in terms of applying longitudinal profiles analysis to some selected valleys in both limbs of the anticline. Consequently, the prominence of knick points in the bottoms of the selected valleys reflects the existence of sudden slopes. Therefore, the southwestern limb of the anticline was suffered more tectonic uplifting activity, and this is clear from the appearance of the triangular shapes in the central part of this limb towards the southeastern plunge of the anticline.

Discussion on Hundru fall as a knick point, Iharkhand, India

Subarnarekha River lies in the vicinity to the Ranchi mega lineament zone of Jharkhand State. This river links the Tamar Porapahar shear zone and North Singhbhum shear zone. The Hundru falls is the sudden and abrupt drop of elevation (longitudinal profile) of upstream of river Subarnarekha. The basic aim of this paper is to assess the Hundru falls as a perfect citation of an upstream knick point in Indian context. This paper covers the knick point formation of upstream of the Subarnarekha river. This upper catchment is more diversified in the terms of metamorphic and igneous rocks. This zone has crossed a long path with diversified lithospheric adjustment with epirogenic upliftment.

Tributary fans of the Middle Teesta Basin in Sikkim‐Darjeeling Himalaya, NE India: Their contribution to valley‐filling processes

Tributary fan deposits in the Sikkim Himalaya are well preserved in the Teesta Valley in the tectonic zone bounded by the Main Central Thrust and the Main Boundary Thrust. The lithofacies characteristics and assemblage patterns of these deposits bear imprints of the linked effects of tectonic and climatic factors on the sedimentation processes in the river valley. Two tributary streams, namely Turung Khola and Bembung Khola have been studied in detail. Three major fanlobes are preserved at Turung Khola and two fanlobes are preserved at the Bembung Khola. Terraces, floodplains, channel bars, and chute bars are associated with geomorphic features in this part of the Teesta Basin. Longitudinal profiles of the tributaries and that of the trunk river indicate a relationship between the knick points and high SL‐Index values, where fault/thrust intersections are present. Sediment characteristics of these fan deposits indicate that four types of flows viz. debris flows (DF), hyperconcentrated flows (HF), sheet flows (SF), and channel flows (CF) deposited these sequences. The CF deposits are dominant in the fan sequence of the Turung Khola followed by SF deposits, HF deposits, and debris flow deposits respectively. HF deposits are dominant in the F1 fanlobe sequence, whereas the active channel fanlobe is dominated by the CF deposits. The rest of the active channel sequence is composed of SF deposits. On the other hand, the F1 fanlobe of Bembung Khola is made up of DF deposits and F0 fanlobe is composed of channel flow deposits and flood sediment. Interactions between the tributary fans and the main Teesta River are studied using lithofacies and the associated morphological context. From the above analysis, an evolutionary model for depositional and incision processes at the tributary stream fan confluence allows the reconstruction of five phases of incision and aggradation through the last ~45 ka.

Lithostructural controls in Douala-Buea Region landscape (SW Cameroon margin): Insights from morphometric analysis

The Douala-Buea Region (DBR; 4°–5°N, 9°–10°30′E), a portion of the southern Cameroon passive margin, developed on the Proterozoic granito-gneissic basement and the Cretaceous to Recent volcano-sedimentary cover, was explored in order to evaluate the lithology and tectonics controls on its landscape using the qualitative and quantitative geomorphological analyses based on 30 m resolution Digital Elevation Models (DEM) and field evidences. This area displays an uneven and complex landscape differentiated into four morphological units: Douala, Nkondjock, Kumba and Buea Units. The Douala Unit corresponds to the Coastal Plain and is extended on the Douala-Kribi/Campo sedimentary basin. The Nkondjock Unit represents a middle plateau developed on a Proterozoic granito-gneissic basement. The Kumba Unit matches with the southernmost volcanic Western Cameroon High Plateau. The Buea Unit corresponds to the Mount Cameroon stratovolcano. The relief analysis through mountain-front sinuosity (Smf, 1.19–1.43) and relative relief ratio (Rr, 0.10–2.31) vary from one unit to another. The drainage network analysis including drainage patterns, stepped longitudinal river profiles, the associated morphometric indexes, notably the concavity index (IC, 0.56–0.88), deviation (D, 267–2912 m), basin asymmetry factor (A f, 6.37–42.12), hypsometric integral (HI, 0.10–0.29), valley floor width to valley height ratio (Vf, 0.36–2.75), elongation ratio (Re, 0.30–0.50), watershed slope (S, 6.88–88.88) and stream length gradient index (SL, 0–3332) vary from one basin to another too. These results also show the heterogeneous and uneven DBR landscape controlled by its lithology and active tectonics. The drainage system reveals concave to concavo-convex longitudinal river profile shapes with knick points, asymmetric basins, and fault reactivations, and highlights the tectonics activity that used to occur through the time and their control on the morphology. Together, they document the lithostructural controls on the DBR landscape evolution, extendable in the whole SW Cameroon margin.

Active tectonics influences in the Satluj river basin in and around Rampur, Himachal Himalaya, India

The detailed investigation of surface dynamics plays a vital role in the identification of regions experiencing recent tectonic activity. The analytical capabilities of geographic information system (GIS) in association with digital elevation model (DEM) are utilized to extract the morphometric and morphotectonic parameters of Satluj basin around a socio-economically important area (the Rampur zone). The drainage network of Strahler order 5 has been extracted from DEM and further analysed qualitatively and quantitatively in order to delineate areas of active deformation and the influence of neotectonic activities on the basin evolution. Further, the responses of the fluvial drainage patterns and other basinal geomorphic indices against the tectonic disturbances have been assessed. The results of morphometric and morphotectonic parameters affirm the neotectonic activities in the basin which is further verified in the field investigations by the presence of active faults, triangular facets, knick points, sharp truncation of the channel, offset channel etc. In addition, an attempt has been made to associate the landslide occurrences with morphometric features. The results of the morphometric study supported by the data of repeated occurrence of earthquake swarms and landslides in the region suggest high neotectonic activity along an active fault in the basin.

Evidences of neotectonic activity along Goriganga River, Higher Central Kumaun Himalaya, India

This paper focuses on the analysis of geomorphic landform development, particularly between the Trans Himadri Fault and the Main Central Thrust including Berinag Thrust and other major NNE–SSW and NW–SE striking faults/thrusts in the Higher Central Kumaun Himalaya. Digital analysis of remote sensing data, field investigations including drainage analysis, and development of landforms have been carried out to understand the morphotectonic evolution and, thereby, the neotectonics in this region. A number of morphometric indices [(stream length‐gradient index (SL), steepness index (ks), Chi (χ)] were computed together with knick point analysis. Offsetting of the major river and tributaries was observed along a NNW–SSE direction. Other tectonic landforms, including truncated saddles and disturbed terrace patterns, show that the area is presently undergoing active deformation. The valley floor morphology in the vicinity of the major thrusts provides evidence for aggradation of recent fluvial activity. Developments of various neotectonic features, such as starth terraces, off‐streams, truncated saddles, disrupted terraces, and palaeolake deposits, are evidences for recent tectonic activities associated with the major thrusts/faults. Cut‐and‐fill terraces with thick alluvial cover, debris‐flow terraces, and alluvial fan terraces are significant aggradational landforms observed within the valley that provide signatures of past climatic records. Our study reveals that the fluvially modified debris‐flow terraces were formed between 5 and 20 ka. We infer that the major phase of valley‐fill happened between 5 and 12 ka, whereas the youngest phase of aggradation may have responded to the Holocene tectonic activity that took place around 5–6 ka. The study is significant to understand the recent geomorphic development and tectonic deformation in the study area and may be helpful for future infrastructural development in the region.

Formation of Potholes Associated with Bedrock Gorges on Mesozoic Sandstone of Khari River, Kachchh Mainland, Western India

The potholes are perceptible erosional features associated with bedrock channels. They play an essential role in bedrock incision studies, but little work has been published on the development of potholes, especially in Bedrock Rivers in India. The present site-specific study aims to analyze the role of physical properties of bedrock and associated structures in the process of development of potholes and to classify the potholes based on their dimensions. The Khari River gorge formed over Mesozoic Sandstone with six bedrock terraces exposed along a confined segment of the river. The site is manifested by strath terraces, grooves, potholes, and knick points. Three stretches of Khari Gorge have been studied in detail for this purpose. The pothole dimensions, joint orientations, rock mass strength, physical properties of rock, and placing of potholes to present active channels were measured. The analysis shows the inverse relationship between the size of pothole and rock properties. The distance of potholes and active channels govern the essential factor and manifest the role of flow hydraulics. The high density of matured potholes near active channels over immature potholes supports primary control of hydraulics of flow over rock properties.

Late Quaternary sedimentological history of a submerged gravel barrier beach complex, southern Namibia

Through comprehensive seismic, stratigraphic, and sedimentological analysis, this paper describes the stratigraphic architecture of the late Quaternary sediments and depositional dynamics in a region ~ 3.5 km offshore of the current south-west Namibian coastline. The landscape evolution model of this area is based on 2D seismic reflection profiles calibrated to approximately 500 boreholes, which yielded sedimentary and seismic facies data of exceptionally high resolution. The data permitted the characterization of four sedimentary facies units and the reconstruction of the submerged landscape dominated by a barrier complex. We compare this barrier complex with the sediment bodies preserved along the adjacent coastline, and account for their geological evolution in response to late Quaternary relative sea-level fluctuations along the West Coast. The most noteworthy depositional units in the study area are the normal regressive coarse gravel beaches trending shore parallel, with the primary gravel barrier and its preserved coeval back-barrier deposits that exceed 7 km in length along the coast. Based on the radiocarbon dates from the rarely preserved early flooding facies (14.0 and 13.3 ka BP), the primary barrier complex formed during a stage of slowing rising relative sea-level subsequent to Meltwater Pulse 1A. Moreover, the barrier beach complex formed on a low-gradient palaeo-bathymetry slope that is punctuated by a break on its landward side (i.e., a regional knick point), which promoted the local accommodation of sediments. The preservation of the barrier beach complex and back-barrier deposits is attributed to rapid relative sea-level rise, linked to the early Holocene Meltwater Pulse 1B between ~ 11.5 and 11.2 ka BP, and an increase in back-barrier accommodation facilitated by the antecedent topography.

Modelling and interpretation of channel profile anomalies through stream length gradient (SL) indexes and GIS: A case study from the Vamanapuram River, Kerala, India

Longitudinal profile of the Vamanapuram River and its five major tributaries was characterized to detect anomalies in terms of knick points through the calculation of stream length gradient (SL) indexes. Longitudinal profiles show presence of knick points in different reaches, indicating changes from the graded smooth concave profile to ungraded convex profile. The ungraded profile segments were confirmed by high SL indexes having sudden changes in values than the adjacent segments and those exactly fitted with the ungraded profile segments. The SL anomaly index is capable of expressing the stream profile anomalies in terms of its severity and to classify the river segments into different orders of anomalies. Higher order SL anomalies are mostly in the midland and lower regions than the headwaters region and are in uniform lithology and are unrelated to the map-scale structural features present in the river basin. The present study points to differential effect of geological process in the middle and lower reaches of the watershed in which the tributaries responded more than the major river. Past seismic events in the region confirm the role of neotectonic processes, which might have influenced the streams by changing the graded base level. Detailed field investigations of the anomalous stream segments can help to identify and understand the imprints caused due to neotectonic activity.

Sorptivity, swelling, shrinkage, compression and durability of quarry dust treated soft soils for moisture bound pavement geotechnics

The failure of pavement foundation materials as hydraulically bound materials is a worrisome condition facing pavement infrastructures in the developing world. Capillary action leads to swelling and shrinkage, compressive strength and durability problems, which result from sorptivity as a function of hydraulic exposure conditions. Pavement infrastructures a constantly interfaced with rise and fall of ground water level and capillary action hence a study on the sorptivity behaviour of quarry dust (QD) treated soft clay soils was carried out. Preliminary tests were conducted on the test materials for the purpose of characterization. The basic test results show that the test soils S1, S2 and S3 were classified as A-2-7, A-2-6 and A-7 soil groups respectively according to AASHTO classification system. Also, they were classified as poorly graded soils but test soils S1 and S2 were observed to be of high clay content (CH) according to USCS. The test soils were equally observed to be of highly plasticity and contains high free swell index properties, hence are expansive. Sorptivity, swelling, shrinkage, compressive strength and durabikity tests were conducted on the test soils treated with varying proportions of quarry dust in accordance with the appropriate standards. Tests results show that QD addition improved consistently the swelling potential, shrinkage limits, compression and durability of the treated test soils. While the improvement on the sorptivity were in two phases, a nick point divided the early age and late age of the sorptivity behaviour curves. However, QD has proven to be a good additive in the treatment of test soils used as pavement foundation materials in a moisture bound environment.

Pothole: a unique geomorphological feature from the bedrocks of Ghaghghar River, Son valley, India

ABSTRACTIn this study, we report for the first time, the occurrence of pothole features and the processes of their development on the bedrocks of Ghaghghar River, Son valley, India. Pothole geometries were identified and measured from the middle reaches of Ghaghghar River, where it is flowing exclusively over the Rohtas limestone (a Meso-Proterozoic age) of Vindhyan Supergroup, near to the Gurma village. On the basis of field survey and remote sensing study, it has been ascertained that potholes developed in the river bed were only related to local geological and geomorphological conditions of a stream. They are mainly developed due to abrupt slope change along the river course and usually associated with intersect fractures, joints, and veins in the bedrock. The knick point of the river profile also confirms the abrupt slope change of the river in Gurma region. The river changes its course from E-W to N-S due to Markundi fault (ENE-WSW) occurring in the study area and causes the tectonic disturbances to support the development of potholes. The formations of potholes on bedrock of Ghaghghar River were generally governed by abrasion of rock fragments during high-flow regime. The geometrical dimensions of the potholes are controlled by the joints, fractures, and veins developed in bedrock of the river. The veins are typically calcitic in nature and the orientations of long axis of potholes are analogous to the trend direction of the vein. The collapse bedrocks suggest that a pothole can be formed within a short period, but cannot be fully developed and maintained for a long time in a strong incision of riverbed.

Morphotectonic analysis of Sheer Khadd River basin using geo-spatial tools

In the present study, a quantitative morphotectonic analysis of Sheer Khadd River basin has been carried out based on geomorphic and morphometric indices such as hypsometric integral, drainage basin asymmetry, mountain front sinuosity, basin elongation ratio, valley floor width to valley height ratio, river sinuosity and stream length gradient index using ASTER digital elevation model (DEM) and Google Earth images to understand the morphotectonics of the basin. The results indicate that Sheer Khadd River basin is tilting towards east and is elongated in shape due to active faulting and folding activity in the terrain. A moderate hypsometric integral value indicates that the basin is still under mature stage of erosion and reflecting a complexity in topography. Fluctuations in stream length gradient index over fault zones indicate irregularities in the drainage course due to the presence of fluvial knick points. The results of morphotectonic and morphometric analysis using DEM data is useful tool for morphotectonic evaluation of any complex terrain.

Morphology and channel characteristics of an equatorial tropical river in Malaysian Borneo: a detailed evaluation through spatially explicit geomorphometric modelling

Geomorphic and morphodynamic characteristics of Akah River in Sarawak, Malaysia in north-western Borneo were modelled using geographical information system assisted techniques and geomorphometric indices. Stream properties such as longitudinal profile, stream length gradient index (SL), channel slope, hypsometric curve, hypsometric integral, sinuosity index and channel cross profiles were analyzed. Morphological features such as meander and channel bar characteristics were evaluated and compared to classify the river and to identify the processes responsible for its present nature. The longitudinal profile, SL index and channel slope indicate the presence of multiple knick points in the channel, which may be indicative of changes in the base level characteristics of the river or lithological differences. The characteristic convex shape of hypsometric toe indicates late stage of deposition due to diffusive processes and the hypsometric integral identifies the geomorphic evolution as in the advanced stage i.e. erosion is significant. The sinuosity index classifies the entire river as meandering and some segments as tortuously meandering with varied stream valleys. Numerous channel bars of various dimensions are found in different reaches of the stream indicating varying channel bottom characteristics and flow mechanism due to the influence of geological process. The information generated from spatial modelling of different geomorphic indices (different terrain variables) and channel characteristics classifies the Akah subwatershed with slope (diffusive) and fluvial dominated geomorphic process having highly meandering channel and showing anomalous characteristics in some segments. These findings will serve as baseline information, while considering the region for hydrological development activities which include check dams, mini hydroelectric projects.

Tectonic Geomorphology in Parts of Koyna Region, Maharashtra

ABSTRACT Geomorphic signatures in parts of Koyna region were analysed using satellite images and morphometric indices (stream length gradient index and valley width to height ratio) with limited field checks in key areas for understanding the role of tectonics in this seismically active zone. The Koyna River zone, particularly downstream of Koyna dam wall up to Kajali Nadi, is characterised by incised narrow valleys, steep escarpments and structurally controlled drainage. Presence of knick points at consistent elevations between 825 m to 675 m, steep gradients in an otherwise gradual longitudinal profile and valley width to height ratio less than 1.0 suggest readjustment of the streams along NW-SE and N-S directions. The escarpment slopes in general have en echelon arcuate ridge pattern ∼ N45°-N 225° in the western part, and then becomes ∼N 10°-N 190° near Donachiwadi, almost orthogonal to the E-W Koyna River. The Donachiwadi fault runs parallel to the escarpment slopes observed near Kodoli. The fluvial system in Koyna thus indicates rejuvenation controlled by basement propagated structures.

Road-stream crossing an in-stream intervention to alter channel morphology of headwater streams: case study

ABSTRACTBasin-scale hydrological response on the geomorphology of lowland headwater streams is often neglected during the in-stream engineering works in rural India. Standard protocols to construct road-stream crossing (RSC) reveals that crossing structures at headwater streams of the Kunur River Basin in eastern India are inadequate to maintain longitudinal continuity in channel hydraulics as well as morphology. The role of crossing type (pipe, box, and small bridge) and catchment land cover are also considered for site-wise variation in channel deformation. The detailed geomorphic survey with 10 cross-sections (5 in the upstream and 5 in the downstream of crossing structure) and 1 longitudinal profile from each of the 10 sample sites were used to run one-dimensional flow modelling in Hydrologic Engineering Center’s River Analysis System, statistical analysis of channel morphometry, manning and rational methods for discharge estimation, and hydroengineering equations. Result shows that in comparison with the extreme upstream (50 m upward from RSC), a significant increase in channel width (30%), depth (17%), and cross-section area (54%) has been observed at the immediate upstream and downstream of RSC. Longitudinal profiles of channel bed, water surface, and energy gradient are also showing the development of knick points, deep scours, and supercritical conditions below the crossing structure. The morphological deformation is more prominent at pipe culvert followed by box and bridges, whereas forested catchment has reduced the effect with less runoff than agricultural. Structural enhancement and regular monitoring might be effective in reducing the problems and constructional cost at RSCs.

Water Absorption in Cementitious Materials at Different Temperatures

Abstract This paper presents results from an experimental investigation that assessed water absorption in cementitious materials at different temperatures. This work aims to determine whether the absorption behavior may be explained by considering only temperature related variations in the fluid properties (surface tension, viscosity, and density). The calculated water absorption curves at 5°C and 40°C (based on adjusting the absorption that was measured at 23°C using the temperature dependent fluid properties) exhibit agreement with the experimental data for the secondary sorption. This indicates that the change of fluid properties as a function of temperature is the primary reason for the difference in behavior. As a result, it appears possible to predict the rate of secondary absorption of cementitious materials at various temperatures with a simple correction. The initial sorptivity also showed a temperature dependency; however, the dependency of the mortars with water-to-cement ratios of 0.30 and 0.50 was 50 % and 64 % greater than that obtained using only the temperature dependent fluid properties. This indicates that, in addition to variations in the properties of the fluid, the interaction between the fluid and cementitious materials may also have a temperature dependence that influences the initial sorptivity. The transition between initial and secondary sorption (i.e., nick point) occurs at an earlier time with increasing temperature due to the increased rate of fluid absorption.

Identifying active structures in the Chitwan Dun, Central Nepal, using longitudinal river profiles and SL index analysis

Previous studies have identified a seismic gap that has not witnessed any surface rupture earthquakes in the last 200–500 years located in the central sub-Himalaya (i.e., area around Chitwan intermontane valley). A higher rate of convergence in these parts poses a great threat of a surface rupturing earthquake in future. Recent analysis of the 2015 Gorkha earthquake to the north of this region suggests that it failed to rupture the surface; moreover, the stress is suggested to have transferred towards south. Therefore, the Chitwan intermontane valley - located in the sub-Himalaya of the central Himalayan seismic gap - is investigated in this study to identify the active structures. The longitudinal profile of a river considered to be one of the important geomorphic markers is used in this study for the identification of the active structures. The Hack profile and Stream-Length gradient index (SL index) is used to identify the anomalous segments of the rivers; these anomalous reaches are verified in the field for the presence of structures. Geomorphology of the region also supports the presence of active reverse faults in the valley. Abrupt break in the continuity of the geomorphic units and its correlation with the knick points and high SL index values indicate presence of around nine active structures in the Chitwan intermontane valley. Six new structures viz., Jharahi Thrust (JHT). Belani Thrust (BT), West Chitwan Thrust (WCT), Danda Thrust (DT), Central Churia Thrust 2 (CCT 2) and Shaktikhor Thrust (ST) have been identified in this study; whereas, three previously mapped structures viz., Main Boundary Thrust (MBT), Barakot Fault (BKF) and Central Churia Thrust (CCT) are also found to be active during the Quaternary/Holocene. Most of the newly identified structures appear to be splays of either the MBT or the CCT. These structures have displaced Quaternary landforms within the valley and are potentially active. The structures can get re-activated during large magnitude earthquake events in future.