Detailed Surface Morphology Research Articles

Development of the sustainable green nanosensor using corn silk extract for nitrate detection in leafy vegetables

Nitrate is prevalent in environment and present in foods of plant origin as part of nitrogen cycle. It is now one of the most pervasive and persistent contaminants in animal food chain. Present work is focussed on development of a novel green nanosensor using corn silk extract for nitrate detection in leafy vegetables (Spinacia oleracea, Amaranthus viridis and Amaranthus cruentus). The green reduced graphene oxide (rGO) and a nanocomposite (G-Fe3O4@rGO) was synthesized for the first-time using corn silk extract and used for fabrication of the nanosensor. Various characterization techniques were used to expose the optical, crystallographic and surface morphology details of the nanosubstrates. Electrochemical studies of the fabricated nanosensor were conducted using the electrochemical impedance spectroscopy (EIS) technique. The performance of NiR/G-Fe3O4@rGO/ITO green nanosensor was the best, in terms of the electrochemical performance parameters among different fabricated nanosensors in the study. The developed green nanosensor demonstrated high sensitivity of 122.1 Ohm/log(mg/L)/cm2 and lower limit of detection 0.076 mg/L for detection of nitrate in leafy vegetables. The green nanosensor exhibited higher recovery rates (>86%) and high precision in nitrate detection in leafy vegetables (RSD <5.2%). Validation studies were conducted with HPLC technique also. The results of green nanosensor were found in good agreement with HPLC studies (p < 0.05) highlighting the market acceptability with usefulness and effectiveness of the nanosensor for food quality and safety evaluation.

Synergistic integration of Ni-metal organic framework/SnS2 nanocomposite and nickel foam electrode for ultrasensitive and selective electrochemical detection of albumin in simulated human blood serum

Albumin is a vital blood protein responsible for transporting metabolites and drugs throughout the body and serves as a potential biomarker for various medical conditions, including inflammatory, cardiovascular, and renal issues. This report details the fabrication of Ni-metal organic framework/SnS2 nanocomposite modified nickel foam electrochemical sensor for highly sensitive and selective non enzymatic detection of albumin in simulated human blood serum samples. Ni-metal organic framework/SnS2 nanocomposite was synthesized using solvothermal technique by combining Ni-metal–organic framework (MOF) with conductive SnS2 leading to the formation of a highly porous material with reduced toxicity and excellent electrical conductivity. Detailed surface morphology and chemical bonding of the Ni-MOF/SnS2 nanocomposite was studied using scanning electron microscopy, transmission electron microscopy, Fourier transform infra-red, and Raman analysis. The Ni-MOF/SnS2 nanocomposite coated on Ni foam electrode demonstrated outstanding electrochemical performance, with a low limit of detection (0.44 μM) and high sensitivity (1.3 μA/pM/cm2) throughout a broad linear range (100 pM–10 mM). The remarkable sensor performance is achieved through the synthesis of a Ni-MOF/SnS2 nanocomposite, enhancing electrocatalytic activity for efficient albumin redox reactions. The enhanced performance can be attributed due to the structural porosity of nickel foam and Ni-metal organic framework, which favours increased surface area for albumin interaction. The presence of SnS2 shows stability in acidic and neutral solutions due to high surface to volume ratio which in turn improves sensitivity of the sensing material. The sensor exhibited commendable selectivity, maintaining its performance even when exposed to potential interfering substances like glucose, ascorbic acid, K+, Na+, uric acid, and urea. The sensor effectively demonstrates its accuracy in detecting albumin in real samples, showcasing substantial recovery percentages of 105.1%, 110.28%, and 91.16%.

Structural, optical, and luminescence properties of Dy3+ -activated potassium calcium silicate phosphor for white light-emitting diodes.

A dysprosium (Dy3+ )-activated potassium calcium silicate (K4 CaSi3 O9 ) phosphor was prepared using a solid-state synthesis route. The phosphor had a cubic structure with the space group Pa as confirmed using X-ray diffraction (XRD) measurements. Details of surface morphology and elemental composition of the as-synthesized undoped KCS phosphor was obtained using scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) spectroscopy. The chemical structure as well as the vibrational modes present in the as-prepared KCS phosphor was analyzed using Fourier transform infrared (FT-IR)spectroscopy. Diffuse reflectance spectra (DRS) were used to determine the optical bandgap of the phosphors and were found to be in the optical range 3.52-3.71 eV. Photoluminescence (PL) spectra showed intense yellow emission corresponding to the 4 F9/2 →6 H13/2 transition under 350 nm excitation. Commission International de l'Eclairage colour chromaticity coordinates were evaluated using the PL spectral data lie within the white region. Dexter theory and the Inokuti-Hirayama (I-H) model were applied to study the nature of the energy transfer mechanism in the as-prepared phosphors. The relatively high activation energy of the phosphors was evaluated using temperature-dependent PL (TDPL) data and confirmed the high thermal stability of the titled phosphor. The abovementioned results indicated that the as-prepared KCS:Dy3+ phosphor was a promising candidate for n-UV-based white light-emitting diodes.

Biopolymer and its nanoparticles for surface coating enhancement of epoxy primer on zinc: electrochemical and surface studies

ABSTRACT The purpose of the current work is to develop an eco-friendly formulation which can be successfully utilised to mitigate zinc corrosion in marine environments. Biopolymer amylopectin and its nanoparticles were used to improve the coating characteristics of epoxy primer on zinc. Amylopectin nanoparticles (AMP-Np) were prepared by the microwave-assisted nanoprecipitation method and characterised using XRD, ATR-FTIR, and TEM studies. Inhibition studies were performed to achieve the optimum inhibitor concentration required for corrosion inhibition of zinc in 3.5% NaCl. Detailed surface morphology was studied using scanning electron microscopy and atomic force microscopic techniques. The overall efficiency of the coating after incorporating AMP (0.02 gL−1) was found to be 99.5%. With the addition of AMP-Np (0.005 gL−1), 99.9% coating efficiency was attained by reducing the concentration to 1/4th of AMP. The epoxy-coated metal coupons, along with micro and nano AMP, were dipped in 3.5% NaCl for 15 days to mitigate corrosion of zinc.

Prediction of surface morphology and reflection spectrum of laser-induced periodic surface structures using deep learning

Laser-induced periodic surface structures have been extensively explored as an enabling tool for fabricating various optical surfaces because the resulting surface ripples can effectively modify surface reflectance. Here, we propose a deep-learning-based model for predicting high-quality surface scanning electron microscopy (SEM) images with detailed surface morphology corresponding to unexplored process conditions. In addition, the reflectance value at 550 nm and reflection spectra from the generated (or original) SEM images were predicted. To obtain training data, stainless steel 304 specimens were processed with femtosecond laser pulses on a large process window consisting of 32 process conditions to obtain SEM images with various surface morphologies and corresponding reflection spectra. The image prediction model is based on a conditional generative adversarial network, which generates a surface SEM image from the laser fluence and scanning speed values. The reflectance prediction model was developed based on ResNet152 and Long-Short Term Memory network. The average accuracies for the pattern period and ripple width were 98.2 and 94.6 %, respectively, and the L2 norm error for the reflection spectra was less than 4 %. It was demonstrated that the reflection spectra can be accurately predicted using only surface images, which can also be accurately generated from process parameters.

Mitigation of corrosion of zinc with amylopectin: Electrochemical, adsorption, and surface studies

AbstractCarbohydrate polymers are proven to be potential green corrosion inhibitors because of their outstanding structural features and eco‐friendliness. Work undertaken reflects the effectiveness of biopolymer amylopectin (AMP) as an eco‐friendly green inhibitor to mitigate the deterioration of zinc in 0.1 M sulphamic acid (NH2SO3H). Electrochemical studies like potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) were applied for corrosion rate measurement in the absence and presence of AMP. Thermodynamic and kinetic parameters were calculated and described in detail. The results were fitted into a suitable adsorption isotherm model, and an appropriate mechanism was proposed for the corrosion inhibition process. A detailed surface morphology study was done using scanning electron microscopy (SEM), electron‐dispersive X‐ray (EDX), and atomic force microscopy (AFM) techniques. The inhibition efficacy of AMP increased with an increase in its concentration and temperature. Upon the addition of the inhibitor, corrosion potential shifted more towards the positive side, indicating more control of the anodic process. The adsorption of AMP over zinc conformed to the Freundlich adsorption isotherm. For the concentration of 0.1 gL−1, maximum corrosion inhibition efficiency of 74% could be accomplished. Surface studies reaffirmed the adsorption of AMP on the surface of the metal. Thus, AMP turned out to be an effective green inhibitor with economic benefits.

The influence of zinc ions concentration on β-lactoglobulin structure – physicochemical properties of Zn–β-lactoglobulin complexes

The study of metal-ions binding to whey proteins is the first step for their application in nutraceuticals. This study is focused on the investigation of the zinc ions concentration (6, 60 and 600 mg/L) effect on the metallocomplexes formation (ZnβLG3, ZnβLG30, ZnβLG300) with the β-lactoglobulin and their characterization by a series of instrumental and computational techniques. Detailed surface morphology of the metallocomplexes was investigated by transmission and scanning electron microscopy combined with energy dispersive X-ray analysis, and X-ray diffraction. Moreover, metallocomplex formation was monitored by attenuated total reflectance infrared spectroscopy and Raman spectroscopy. Experimental results were complemented by molecular dynamics (MD) studies indicating the precise binding sites of βLG to Zn2+(aq) ions and quantum mechanics (QM) simulation combined with density functional theory (DFT). Electron microscopy studies indicated that with increasing concentrations of Zn2+(aq) ions, the surface morphology of βLG changes, and the formed metallocomplexes exhibit higher porosity. Meanwhile, spectroscopic studies indicated the formation of metallocomplexes through the binding of Zn2+(aq) ions to amino acids (AAs) such as glutamic acid (Glu), aspartic acid (Asp), tryptophan (Trp), tyrosine (Tyr), and phenylalanine (Phe). Strong positive correlations between the increasing concentration of Zn2+(aq) ions and the number of binding sites were determined based on the MD results. DFT calculations confirm the strong binding affinity of Asp− and Glu− to Zn2+(aq) ions.

Enhanced anticorrosion performance of epoxy primer coating on zinc in 3.5% NaCl by micro and nano particulates of biopolymers

Anticorrosive coatings are extensively used to protect metals and alloys, especially in the marine environment. This study reports the enhancement of coating performance of epoxy primer coating on zinc in 3.5% NaCl at 303 K by impregnating the epoxy primer with micro and nano particulates of biopolymers. Initially, conditions were standardized to achieve optimum efficiency of Maltodextrin (MLD) and Glycogen (GLY) for corrosion of zinc in 3.5% NaCl. The optimum concentration of inhibitors was then added to the epoxy primer coating a applied on zinc. Anti-corrosion performance of epoxy primer with biopolymer was compared with that of standard coating, which was devoid of biopolymers. The coating characteristics were further enhanced by incorporating nanoparticles of MLD and GLY into the epoxy primer matrix. Potentiodynamic polarization measurement (PDP) and Electrochemical impedance spectroscopy (EIS) were employed to study corrosion rate measurement. Detailed surface morphology was studied using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) techniques. Electrochemical and surface studies clearly demonstrated the capability of micro and nanosized biopolymers in improving the anti-corrosion performance of the coating. The average efficiency of epoxy primer coating improved to a considerable extent by studying biopolymers. The overall efficiency of the coating formulation was found to be 99.5%. Surface morphology studies showed that coating thickness increased to 32.1 µm from 27.2 µm after incorporating biopolymers. In addition to this, there was a remarkable change in the surface roughness of epoxy primer coating in contact with 3.5% NaCl after the addition of biopolymers into it. The coating formulation developed turned out to be eco-friendly with significant environmental benefits.

Undetection of Australasian microtektites in the Chinese Loess Plateau

Australasian strewn field of tektites and microtektites, formed by a large impact event at ~0.788 Ma, is the youngest and largest known strewn field on Earth. The location of its source crater is still unconfirmed after nearly 60 years of exploration. The geographic boundary and the spatial density of tektites and microtektites within this strewn field are the most important information for the search of the potential parent crater. It has been noticed that the northern boundary of this strewn field may be extended further than currently sketched, as possible microtektites have been reported, but not confirmed in the Chinese Loess Plateau (i.e., CLP). The potential microtektites reported in CLP were used as a stratigraphic marker for Quaternary Science, and their existence may indicate a larger impact event that formed this strewn field, redirecting the search area for the source crater. In the past four years, we systematically searched for Australasian microtektites in the Chinese Loess Plateau, and this study is a final report for this project. Referring to the magnetic susceptibility and local deposition rates of loess materials, we sampled nineteen loess sections that cover deposition ages of ~0.788 Ma. The sections are distributed at eight different locations across CLP, and potential Australasian microtektites were reported in some of these sections. At each section, we performed continuous sampling with depths, and each sample was ~1500 g in weight. The total section area of the sampled sections is much larger than that of deep ocean drill cores where Australasian microtektites were searched. We processed over four hundred kilograms of samples and discovered twenty glass microspherules that have spherical and rotational shapes. These microspherules are scattered at different depths of the sections, and their water content is as low as that of typical microtektites. However, both the content of major elements and detailed surface morphology of the microspherules are different from those of Australasian microtektites, but consistent with those of manmade soda-lime glasses and coal fly ashes. This project concludes no discovery of Australasian microtektites, suggesting that microtektites are not widespread stratigraphic markers in CLP. The result further concurs that microtektites in this strewn field were preferentially deposited at the downrange of the impactor trajectory. While microtektites may have temporarily escaped the atmosphere during this impact event, subsequent atmospheric reentry and lateral transportation in the upper atmosphere did not deposit microtektites towards the uprange.

Application of Floating TiO2 Photocatalyst for Methylene Blue Decomposition and Salmonella typhimurium Inactivation

The growing level of wastewater as well as pollution of freshwater by various bacteria are essential worldwide issues which have to be solved. In this contribution, nanocrystalline anatase TiO2 films deposited by magnetron sputtering on high-density polystyrene (HDPE) beads were applied as floating photocatalysts for Salmonella typhimurium bacterial inactivation in water for the first time. Additionally, the photocatalytic degradation of methylene blue dye in the presence of HDPE beads with TiO2 film under UV-B irradiation was investigated. The suitability to adopt such floating photocatalyst structures for practical applications was tested in cycling experiments. The detailed surface morphology, crystal structure, elemental mapping, surface chemical composition and bond analysis of deposited TiO2 films were investigated by scanning electron microscope, X-ray diffractometer and X-ray photoelectron spectroscope techniques. The bacterial viability as well as MB decomposition experiments showed promising results by demonstrating that 6% of bacterial colonies were formed after the first run and only about 1% after the next four runs, which is an appropriate outcome for practical applications. NPN uptake results showed that the permeability of the outer membrane was significantly increased as well.

Tribological and mechanical investigation of coir-silk reinforced polypropylene based matrix composites.

Silane treated natural fibers such as silk, coconut coir is reinforced into the polypropylene (PP) with a varying weight fraction of fibers and matrixes are developed in twin screw extruder at a constant temperature followed by the hot compression molding. Totally three different weight percentage of the polymer composites are developed. Such as silk fiber reinforced composites (S-PP), coir fiber reinforced composites (C-PP) and silk along with coir fiber reinforced composites (S-C-PP). The developed composites are then subjected to various tests. The water absorption capabilities of the all three composites are investigated. The composites are tending to abrasive wear test as per the ASTM standards. Design of experiments L-9 orthogonal array was introduced to identify the optimal wear condition of the composites developed. From the results it is observed that the tricholo vinyl silane chemical treatment to the coir and silk fibers enhances the tribo-mechanical properties of the fiber reinforced polymer composites. Also, the wear life of the composites was increased by 35% and water absorption capability increased by 42%. The scanning electron microscopy helped in identifying the impact of wear test over the surface of the composites at higher magnifications. The detailed surface morphology was executed in order to identify the behavior of the composites upon application of load.

Effect of coating on the mechanical properties of electrospun poly(3-hydroxybutyrate) materials with targeted fibers alignment

Understanding the mechanical behavior of electrospun materials and how to control it is important and valuable in terms of their future applications. That is why, in this study, materials with controlled fibers alignment and desired mechanical properties were fabricated by electrospinning of poly(3-hydroxybutyrate) (PHB) onto three types of rotating collectors – drum (smooth), blade and grid (patterned). In addition, by controlling the collector rotation speed and by coating of the PHB mats with chitosan or cellulose acetate, purposely tailored fibers alignment and targeted design of the materials were achieved. Further, the detailed surface morphology, thermal behavior and crystallinity of the PHB materials were characterized by SEM, DSC and XRD. It was demonstrated that patterned collectors had a significant impact on fibers alignment only at lower rotation speed, whereas with the increase in the collector speed the fibers alignment increased in the direction of collector rotation. The materials strength was evaluated by tensile tests and indicated that PHB materials fabricated at lower collector rotation speed exhibited isotropic mechanical properties, whereas those at higher collector rotation speed – anisotropic. In addition, coating of PHB materials with chitosan or cellulose acetate enhanced their mechanical properties. Hence, this study demonstrates the possibilities for fabrication of electrospun materials with desired fibers alignment and thus, with targeted mechanical properties.

Role of Coupling Divalent Metal Ion of Tin on Structural and Magnetic Properties of NiFe2O4 Nanoparticles

In this research article, we report the role of coupling divalent metal ion tin (Sn) on the structural and magnetic properties of NiFe2O4 nanoparticles (NPs). A series of nanocrystalline nickel ferrites [Ni( $1-x$ )Sn( $x$ )Fe2O4] with composition $x = 0.0$ , 0.2, 0.4, 0.6, and 0.8 are synthesized by coprecipitation method. The synthesized title product is subjected to a variety of analytical techniques such as powder X-ray diffractometer (PXRD), scanning electron microscopy (SEM), and vibrating sample magnetometer (VSM), to understand the structural and magnetic properties. PXRD patterns confirm the single-phase formation of NiFe2O4 NPs as well as Sn concentration. SEM images showed the surface morphology details and size of the particles. VSM studies reveal that the saturation magnetization ( $M_{\mathrm {s}}$ ) of soft superparamagnetic nature reduces with the variation of Sn concentration.

Machining and Characterization of Micro-Channels Generated on Phosphor Bronze Using μ-EDM

Micro-Electro Discharge Machining ([Formula: see text]-EDM) is one of the nonconventional micro-machining processes in which electrical discharges are produced between the micro-sized electrodes — tool and workpiece immersed in dielectric fluid. The electrical discharges thus produced remove the workpiece material through melting and vaporization process and results in the creation of micro-craters. This paper focuses on machining of micro-channels on copper alloy — phosphor bronze plate using [Formula: see text]-EDM. Various micro-channels have been machined on phosphor bronze with input parameters: voltage, capacitance and pulse on-time varied at four levels. The experimental layout plans were designed with robust design technique — Taguchi-based L[Formula: see text] orthogonal array and the process parameters were optimized using optimization technique — Grey Relational Analysis (GRA). The dimensional aspects — depth, width, profile and surface roughness of machined channels were selected as output responses. The experimental results show that the parameters have individual and combined effect on responses. Analysis of Variance (ANOVA) technique has been used to explore the effect of parameters on responses. Detailed surface morphology of the machined features has also been analyzed using scanning electron microscope (SEM) and noncontact optical profiler images. As an extension of machining channels, Y-shaped channel has been machined on copper alloy which can be used for micro-fluidic applications.

Synthesis and evaluation of reduced graphene oxide for supercapacitor application

The paper reports synthesis of graphene oxide (GO) using modified Hummer’s method and its hydrothermal assisted reduction to produce reduced graphene oxide (rGO) for supercapacitor applications. Synthesized GO and rGO were characterized using Raman spectroscopy and their Id/Ig ratio was found to be 0.94 and 0.87, respectively. Scanning Electron Microscopy (SEM) was also performed on samples for detailed surface morphology information. UV-Vis spectroscopy was employed to investigate optical properties. FT-IR spectroscopy was utilized to get the information of attached functional groups and electrochemical characterization (cyclic voltammetry) was used to test the charging discharging behavior of the material. The specific capacitance of synthesized rGO was found to be 105F/g.

SnO2-ZnO-Fe2O3 tri-composite based room temperature operated dual behavior ammonia and ethanol sensor for ppb level detection.

In this paper, we present a novel room temperature (RT) operated SnO2-ZnO-Fe2O3 based tri-composite analyte sensor with dual behavior having detection ability of up to ∼1 ppb with a substantial % response (R) to detect ammonia and ethanol vapors. The tri-composite is synthesized via a sol-gel spin coating technique and characterized using X-ray diffraction (XRD) for structural analysis. Fourier transform infrared spectroscopy (FTIR) and Raman results are used to confirm tri-composite formation. Further, field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM) and atomic force microscopy (AFM) results are used for examining the detailed surface morphology and structural and topographical characteristics of the tri-composite. The sensing characteristics are monitored from 1 ppb to 50 ppm for ammonia detection and 1 ppb to 25 ppm for ethanol detection at RT (∼27 °C) under ∼45% relative humidity (RH) conditions. This dual sensing behavior (based on change in resistance under ammonia and ethanol exposure) of the sensor is used to differentiate and detect the presence of ammonia (resistance decreases) and ethanol (resistance increases) with high %R within a few seconds. In addition, the sensor showed excellent sensing characteristics under moist conditions (up to 85% RH) and outstanding reproducibility, and was found to be highly stable, selective and specific towards the target analytes. This work not only reports a RT operated ppb level ammonia and ethanol sensor, but also explores the novel SnO2-ZnO-Fe2O3 tri-composite along with a scientific approach towards multi-composite nanostructures to develop analyte sensors.

Mechanical and biological properties of chitin/polylactide (PLA)/hydroxyapatite (HAP) composites cast using ionic liquid solutions

This research investigates the potential development of lobster shell waste-derived chitin reinforced with poly(lactic acid) (PLA) and nano-hydroxyapatite (nHAP) into new materials with potentially superior mechanical and thermal properties for biomedical applications. The ionic liquid 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]) was used as a solvent to prepare chitin/PLA/nHAP composites. The effect of variation of the polymer concentrations on the conduct of the resulting composite was explored. The detailed physico-mechanical, thermal and surface morphology properties were evaluated with different thermal and optical characterization techniques. When the concentration of PLA in the composite was increased from 20 to 80 wt%, the tensile strength improved by ~77% while the elongation at break and the toughness of the material decreased significantly. The addition of hydroxyapatite was observed to improve strength of the composites up to 140% with an increase in elongation at break up to 465%. Cell growth study show that the composite materials support the growth and proliferation of Ocy 454 osteocyte cells. The materials were shown to have no effect on osteocyte gene expression, as well as minimal cytotoxicity and biodegradability. These results reveal that the biocomposites would be suitable candidates for use in bone regeneration that are not exposed to excessive forces.

Landslide features identification and morphology investigation using high-resolution DEM derivatives

In the last decade, development in remote sensing techniques has opened new avenues for studying the evolution of landscapes dominated by mass wasting processes. Conventional methods including field reconnaissance are time-consuming and resource-intensive. Thus, it is worth taking advantage of the high-resolution digital elevation model (HRDEM) to identify landslide features remotely and investigate landslide morphology. This research proposes a new technique of landslide feature identification and morphology mapping using computer-aided methods to enhance the visual interpretation of HRDEM. These computer-aided methods involve deep exploration of topographic information provided by HRDEM. In addition to the HRDEM, nine diverse HRDEM derivatives were used to maximise the morphological information captured by HRDEM. To compact and to better understand the morphological information, original HRDEM derivatives were transformed into the principal component (PC) domain. Based on PC composition provided by three initial PCs, it was possible to identify morphological signatures of landslides and represent them as the detailed landslide surface morphology maps. The presented methodology serves as an alternative means of landslide characterisation. It permitted the evaluation of slope morphology and the ability to reassess recent and future landslide activity on a comparative basis.

Preparation of Chitin-PLA laminated composite for implantable application

The present study explores the possibilities of using locally available inexpensive waste prawn shell derived chitin reinforced and bioabsorbable polylactic acid (PLA) laminated composites to develop new materials with excellent mechanical and thermal properties for implantable application such as in bone or dental implant. Chitin at different concentration (1–20% of PLA) reinforced PLA films (CTP) were fabricated by solvent casting process and laminated chitin-PLA composites (LCTP) were prepared by laminating PLA film (obtained by hot press method) with CTP also by hot press method at 160 °C. The effect of variation of chitin concentration on the resulting laminated composite's behavior was investigated. The detailed physico-mechanical, surface morphology and thermal were assessed with different characterization technique such as FT-IR, XRD, SEM and TGA. The FTIR spectra showed the characteristic peaks for chitin and PLA in the composites. SEM images showed an excellent dispersion of chitin in the films and composites. Thermogravimetric analysis (TGA) showed that the complete degradation of chitin, PLA film, 5% chitin reinforced PLA film (CTP2) and LCTP are 98%, 95%, 87% and 98% respectively at temperature of 500 °C. The tensile strength of the LCTP was found 25.09 MPa which is significantly higher than pure PLA film (18.55 MPa) and CTP2 film (8.83 MPa). After lamination of pure PLA and CTP2 film, the composite (LCTP) yielded 0.265–1.061% water absorption from 30 min to 24 h immerse in water that is much lower than PLA and CTP. The increased mechanical properties of the laminated films with the increase of chitin content indicated good dispersion of chitin into PLA and strong interfacial actions between the polymer and chitin. The improvement of mechanical properties and the results of antimicrobial and cytotoxicity of the composites also evaluated and revealed the composite would be a suitable candidate for implant application in biomedical sector.

Forensic analysis of rockfall scars

We characterise and analyse the detachment (scar) surfaces of rockfalls to understand the mechanisms that underpin their failure. Rockfall scars are variously weathered and comprised of both discontinuity release surfaces and surfaces indicative of fracturing through zones of previously intact rock, known as rock bridges. The presence of rock bridges and pre-existing discontinuities is challenging to quantify due to the difficulty in determining discontinuity persistence below the surface of a rock slope. Rock bridges form an important control in holding blocks onto rockslopes, with their frequency, extent and location commonly modelled from the surface exposure of daylighting discontinuities. We explore an alternative approach to assessing their role, by characterising failure scars. We analyse a database of multiple rockfall scar surfaces detailing the areal extent, shape, and location of broken rock bridges and weathered surfaces. Terrestrial laser scanning and gigapixel imagery were combined to record the detailed texture and surface morphology. From this, scar surfaces were mapped via automated classification based on RGB pixel values.Our analysis of the resulting data from scars on the North Yorkshire coast (UK) indicates a wide variation in both weathering and rock bridge properties, controlled by lithology and associated rock mass structure. Importantly, the proportion of rock bridges in a rockfall failure surface does not increase with failure size. Rather larger failures display fracturing through multiple rock bridges, and in contrast smaller failures fracture occurs only through a single critical rock bridge. This holds implications for how failure mechanisms change with rockfall size and shape. Additionally, the location of rock bridges with respect to the geometry of an incipient rockfall is shown to determine failure mode. Weathering can occur both along discontinuity surfaces and previously broken rock bridges, indicating the sequential stages of progressively detaching rockfall. Our findings have wider implications for hazard assessment where rock slope stability is dependent on the nature of rock bridges, how this is accounted for in slope stability modelling, and the implications of rock bridges on long-term rock slope evolution.