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The agricultural sector plays a pivotal role in driving the economy of many developing countries. Any dent in this economical structure may have a severe impact on a country's population. With rising climate change and increasing pollution, the agricultural sector is experiencing significant damage. Over time this cumulative damage will affect the integrity of food crops and create food security issues around the world. Therefore, an early warning system is needed to detect possible stress on food crops. Here we present a review of the recent developments in nanomaterial-based Surface Enhanced Raman Spectroscopy (SERS) substrates which could be utilized to monitor agricultural crop responses to natural and anthropogenic stress. Initially, our review delves into diverse and cost-effective strategies for fabricating SERS substrates, emphasizing their intelligent utilization across various agricultural scenarios. In the second phase of our review, we spotlight the specific application of SERS in addressing critical food security issues. By detecting nutrients, hormones, and effector molecules in plants, SERS provides valuable insights into plant health. Furthermore, our exploration extends to the detection of contaminants, chemicals, and foodborne pathogens within plants, showcasing the versatility of SERS in ensuring food safety. The cumulative knowledge derived from these discussions illustrates the transformative potential of SERS in bolstering the agricultural economy. By enhancing precision in nutrient management, monitoring plant health, and enabling rapid detection of harmful substances, SERS emerges as a pivotal tool in promoting sustainable and secure agricultural practices. Its integration into agricultural processes not only augments productivity but also establishes a robust defence against potential threats to crop yield and food quality. As SERS continues to evolve, its role in shaping the future of agriculture becomes increasingly pronounced, promising a paradigm shift in how we approach and address challenges in food production and safety.
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Both cell migration and osteogenic differentiation are critical for successful bone regeneration. Therefore, understanding the mechanobiological aspects that govern these two processes is essential in designing effective scaffolds that promote faster bone regeneration. Studying these two factors at different locations is necessary to manage bone regeneration in various sections of a scaffold. Hence, a multiscale computational model was used to observe the mechanical responses of osteoblasts placed in different positions of the trabecular bone and gyroid scaffold. Fluid shear stresses in scaffolds at cell seeded locations (representing osteogenic differentiation) and strain energy densities in cells at cell substrate interface (representing cell migration) were observed as mechanical response parameters in this study. Comparison of these responses, as two critical factors for bone regeneration, between the trabecular bone and gyroid scaffold at different locations, is the overall goal of the study. This study reveals that the gyroid scaffold exhibits higher osteogenic differentiation and cell migration potential compared to the trabecular bone. However, the responses in the gyroid only mimic the trabecular bone in two out of nine positions. These findings can guide us in predicting the ideal cell seeded sites within a scaffold for better bone regeneration and in replicating a replaced bone condition by altering the physical parameters of a scaffold.
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Regeneração Óssea , Osso Esponjoso , Diferenciação Celular , Movimento Celular , Osteoblastos , Osteogênese , Alicerces Teciduais , Regeneração Óssea/fisiologia , Osteoblastos/fisiologia , Osteoblastos/citologia , Diferenciação Celular/fisiologia , Alicerces Teciduais/química , Movimento Celular/fisiologia , Osso Esponjoso/fisiologia , Osteogênese/fisiologia , Humanos , Porosidade , Modelos Biológicos , Estresse MecânicoRESUMO
Opioid use, particularly morphine, is linked to CNS-related disorders, comorbidities, and premature death. Morphine, a widely abused opioid, poses a significant global health threat and serves as a key metabolite in various opioids. Here, we present a turn-off fluorescent sensor capable of detecting morphine with exceptional sensitivity and speed in various samples. The fluorescent sensor was developed through the dimerization process of 7-methoxy-1-tetralone and subsequent demethylation to produce the final product. Despite morphine possessing inherent fluorophoric properties and emitting light in an approximately similar wavelength as the sensor's fluorescent blue light, the introduction of the target molecule (morphine) in the presence of the sensor caused a reduction in the sensor's fluorescence intensity, which is attributable to the formation of the sensor-morphine complex. By utilizing this fluorescence quenching sensor, the chemo-selective detection of morphine becomes highly feasible, encompassing a linear range from 0.008 to 40 ppm with an impressive limit of detection of 8 ppb. Consequently, this molecular probe demonstrates a successful application in determining trace amounts of morphine within urine, yielding satisfactory analytical results. The study also explores the effect of several variables on the sensor's response and optimizes the detection of morphine in urine using a response surface methodology with a central composite design.
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Líquidos Corporais , Morfina , Morfina/urina , Analgésicos Opioides , Corantes Fluorescentes , Espectrometria de Fluorescência , Líquidos Corporais/químicaRESUMO
Objective: Loosening of dental implants due to resorption of the surrounding bone is one of the challenging clinical complications in prosthetic dentistry. Generally, stiffness mismatch between an implant and its surrounding bone is one of the major factors. In order to prevent such clinical consequences, it is essential to develop implants with customized stiffness. The present study investigates the computational and experimental biomechanical responses together with cytocompatibility studies of three-dimensional (3D)-printed Ti-6Al-4V-based porous dental implants with varied stiffness properties. Methods: Additive manufacturing (direct metal laser sintering, DMLS) was utilized to create Ti-6Al-4V implants having distinct porosities and pore sizes (650 and 1000 µm), along with a nonporous (solid) implant. To validate the compression testing of the constructed implants and to probe their biomechanical response, finite element models were employed. The cytocompatibility of the implants was assessed using MG-63 cells, in vitro. Results: Both X-ray microcomputed tomography (µ-CT) and scanning electron microscopy (SEM) studies illustrated the ability of DMLS to produce implants with the designed porosities. Biomechanical analysis results revealed that the porous implants had less stiffness and were suitable for providing the appropriate peri-implant bone strain. Although all of the manufactured implants demonstrated cell adhesion and proliferation, the porous implants in particular supported better bone cell growth and extracellular matrix deposition. Conclusions: 3D-printed porous implants showed tunable stiffness properties with clinical translational potential.
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Loading configuration of hip joint creates resultant bending effect on femoral implants. So, the lateral side of femoral implant which is under tension retracts from periimplant bone due to positive Poisson's ratio. This retraction of implant leads to load shielding and gap opening in proximal-lateral region, thereby allowing entry of wear particle to implant-bone interface. Retraction of femoral implant can be avoided by introducing auxetic metamaterial to the retracting side. This allows the implant to push periimplant bone under tensile condition by virtue of their auxetic (negative Poisson's ratio) nature. To develop such implants, a patient-specific conventional solid implant was first designed based on computed-tomography scan of a patient's femur. Two types of metamaterials (2D: type-1) and (3D: type-2) were employed to design femoral meta-implants. Type-1 and type-2 meta-implants were fabricated using metallic 3D printing method and mechanical compression testing was conducted. Three finite element (FE) models of the femur implanted with solid implant, type-1 meta-implant and type-2 meta-implant were developed and analysed under compression loading. Significant correlation (R2 = 0.9821 and R2 = 0.9977) was found between the experimental and FE predicted strains of the two meta-implants. In proximal-lateral region of the femur, an increase of 7.1% and 44.1% von-Mises strain was observed when implanted with type-1 and type-2 meta-implant over the solid implant. In this region, bone remodelling analysis revealed 2.5% bone resorption in case of solid implant. While bone apposition of 0.5% and 7.7% was observed in case of type-1 and type-2 meta-implants, respectively. The results of this study indicates that concept of introduction of metamaterial to the lateral side of femoral implant can prove to provide higher osseointegration-friendly environment in the proximal-lateral region of femur.
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Fêmur , Próteses e Implantes , Humanos , Fêmur/cirurgia , Osseointegração , Remodelação Óssea , Extremidade Inferior , Análise de Elementos FinitosRESUMO
Inappropriate e-waste processing in the informal sector is a serious issue in developing countries. Field investigations in microscale informal recycling sites have been performed to study the impact of hazardous metal(loid)s (released from e-waste dismantling) on the environment (water and soil). Eight hazardous metal(loid)s (Pb, Cd, Cu, Zn, As, Hg, Ni, and Cr) were primarily found in the monitored water and soil samples (Sangrampur, West Bengal) because of widespread informal e-waste handling and primitive processing. Elevated concentrations of Cd, Pb, As, Cu, and Cr were observed in pond water samples (0.04, 1.62, 0.03, 1.40, 1.74 mg/L respectively). These ponds, which are regularly used for e-waste handling/dismantling, are usually flooded during the monsoon season mixing with further larger water resources - posing a serious threat to public health. Enriched levels of Pb, Cd, Cu, and Zn were detected in collected soil samples, both top surface soil (Pb up to 2042.27 ± 206.80, Cd up to 25.90 ± 9.53, Cu up to 6967.30 ± 711.70, and Zn up to 657.10 ± 67.05 mg/Kg) and deeper subsurface soil (Pb, 419.70 ± 44.70; Cd, 18.34 ± 3.81; Cu, 3928.60 ± 356.40; and Zn, 134.40 ± 33.40 mg/Kg), compared to the levels of As, Hg, Ni, and Cr. Seasonal variation of soil metal(loid) content indicated that higher levels of most of the metal(loids) were detected in the pre-monsoon (Nov-May) season, possibly due to the monsoonal dilution effect, except for Pb and Cd. The results highlighted that the composition and the handling of e-waste were important factors affecting the metal(loid) concentrations. E-waste policy and legislation have great influence on the handling and disposal procedures. An improved e-waste management practice has been proposed to encourage eco-friendly and safe e-waste disposal. It is recommended that regulatory agencies and manufacturers should create a road map to convince the informal sector to develop a systematic approach towards a more standardized formal e-waste management practices at the microscale field level.
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Resíduo Eletrônico , Mercúrio , Metais Pesados , Poluentes do Solo , Metais Pesados/análise , Cádmio , Setor Informal , Chumbo , Poluentes do Solo/análise , Monitoramento Ambiental/métodos , Solo , Medição de Risco , ChinaRESUMO
This study aimed to perform quantitative biomechanical analysis for probing the effect of varying thread shapes in an implant for improved primary stability in prosthodontics surgery. Dental implants were designed with square (SQR), buttress (BUT), and triangular (TRI) thread shapes or their combinations. Cone-beam computed tomography images of mandible molar zones in human subjects belonging to three age groups were used for virtual implantation of the designed implants, to quantify patient-specific peri-implant bone microstrain, using finite element analyses. The in silico analyses were carried out considering frictional contact to simulate immediate loading with a static masticatory force of 200 N. To validate computational biomechanics results, compression tests were performed on three-dimensional printed implants having the investigated thread architectures. Bone/implant contact areas were also quantitatively assessed. It was observed that, bone/implant contact was maximum for SQR implants followed by BUT and TRI implants. For all the cases, peak microstrain was recorded in the cervical cortical bone. The combination of different thread shapes in the middle or in the apical part (or both) was demonstrated to improve peri-implant microstrain, particularly for BUT and TRI. Considering 1500-2000 microstrain generates in the peri-implant bone during regular physiological functioning, BUT-SQR, BUT-TRI-SQR, TRI-SQR-BUT, SQR, and SQR-BUT-TRI design concepts were suitable for younger; BUT-TRI-SQR, BUT-SQR-TRI, TRI-SQR-BUT, SQR-BUT, SQR-TRI for middle-aged, and BUT-TRI-SQR, BUT-SQR-TRI, TRI-BUT-SQR, SQR, and SQR-TRI for the older group of human patients.
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Implantes Dentários , Fenômenos Biomecânicos , Força de Mordida , Simulação por Computador , Análise do Estresse Dentário , Análise de Elementos Finitos , Humanos , Pessoa de Meia-Idade , Estresse MecânicoRESUMO
The bone conditions of mandibular bone vary from patient to patient, and as a result, a patient-specific dental implant needs to be designed. The basal dental implant is implanted in the cortical region of the bone since the top surface of the bone narrows down because of aging. Taguchi designs of experiments technique are used in which 25 optimum solid models of basal dental implants are modeled with variable geometrical parameters, viz. thread length, diameter, and pitch. In the solid models the implants are placed in the cortical part of the 3D models of cadaveric mandibles, that are prepared from CT data using image processing software. Patient-specific bone conditions are varied according to the strong, weak, and normal basal bone. A compressive force of 200 N is applied on the top surface of these implants and using finite element analysis software, the microstrain on the peri-implant bone ranges from 1000 to 4000 depending on the various bone conditions. According to the finite element data, it can be concluded that weak bone microstrain is comparatively high compared with normal and strong bone conditions. A surrogate artificial neural network model is prepared from the finite element analysis data. Surrogate model assisted genetic algorithm is used to find the optimum patient-specific basal dental implant for a better osseointegration-friendly mechanical environment.
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Implantes Dentários , Fenômenos Biomecânicos , Simulação por Computador , Planejamento de Prótese Dentária , Análise do Estresse Dentário , Análise de Elementos Finitos , Humanos , Mandíbula/diagnóstico por imagem , Mandíbula/cirurgia , Redes Neurais de Computação , Estresse MecânicoRESUMO
This study aimed to understand the effect of physiological and dental implant-related parameter variations on the osseointegration for an implant-supported fixed prosthesis. Eight design factors were considered (implant shape, diameter, and length; thread pitch, depth, and profile; cantilever [CL] length and implant-loading protocol). Total 36 implantation scenarios were simulated using finite element method based on Taguchi L36 orthogonal array. Three patient-specific bone conditions were also simulated by scaling the density and Young's modulus of a mandible sample to mimic weak, normal, and strong bones. Taguchi method was employed to determine the significance of each design factor in controlling the peri-implant cortical bone microstrain. For normal bone condition, CL length had the maximum contribution (28%) followed by implant diameter (18%), thread pitch (14%), implant length (8%), and thread profile (5%). For strong bone condition, CL and implant diameter had equal contribution (32%) followed by thread pitch (7%) and implant length (5%). For weak bone condition, implant diameter had the highest contribution (31%) followed by CL length (30%), thread pitch (11%) and implant length (8%). The presence of distal CL in dental framework was found to be the most influential design factor, which can cause high strain in the cervical cortical bone. It was seen that implant diameter had more effect compared to implant length toward peri-implant bone biomechanical response. Implant-loading time had no significant effect towards peri-implant bone biomechanical response, signifying immediate loading is possible with sufficient mechanical retention.
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Implantes Dentários , Fenômenos Biomecânicos , Planejamento de Prótese Dentária , Análise do Estresse Dentário , Módulo de Elasticidade , Análise de Elementos Finitos , Humanos , Mandíbula , Osseointegração , Estresse MecânicoRESUMO
The COVID-19 pandemic has affected daily lives of people around the world. People have already started to live wearing masks, keeping a safe distance from others, and maintaining a high level of hygiene. This paper deals with an in-depth analysis of riskness associated with COVID-19 infections in Kolkata Municipal Corporation (KMC) at the subcity (ward) level. Attempts have been made to identify the areas with high or low risk of infections using GIS-based geostatistical approach. Cosine Similarity Index has been used to rank different wards of KMC according to the degree of riskness. Four indices were computed to address intervention objectives and to determine "Optimized Prevention Rank" of wards for future policy decisions. The highest risk areas were located in the eastern and western part of the city, to a great extent overlapped with wards containing larger share of population living in slums and/or below poverty level. On the other hand, highly infected areas lie in central Kolkata and in several wards at the eastern and northeastern periphery of the KMC. The "Optimized Prevention Rank" have indicated that the lack of social awareness along with lack of social distancing have contributed to the increasing number of containments of COVID-19 cases. The rankings of the wards would no doubt provide the policy makers a basis to control further spread of the disease. Since effective antiviral drugs are already in the market, the best application of our research would be in the ensuing vaccination drive against further COVID-19 infections.
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The present study depicts the geospatial relation between basinal geomorphology and heterogeneous arsenic (As) distribution in the Bengal Delta Plain (BDP). The distribution pattern largely varies throughout the study area (higher: Karimpur-II AsT average 214.73 µgL-1; lower: Tehatta AsT average 27.84 µgL-1). Both safe (low As) and unsafe (high As) areas are identified within the single shallow aquifer (<50 m), where they are in close vicinity. Statistical analysis shows that Padma river basin is the most contaminated (AsT avg. 214.7 ± 160 µgL-1) and Churni-Ichhamati river basin (AsT avg. 108.54 ± 89.43 µgL-1) is the least contaminated with groundwater As. Moreover, the role of geomorphological features influencing the geospatial distribution of As has been studied and meandering features are found to correlate with high As wells (r2 = 0.52), whereas, natural levees are correlated with safer wells (r2 = 0.57). In the meandering features, the deposition of sedimentary organic matter (SOM) facilitates the reduction of As bearing Fe(III) oxy-hydroxides and subsequent higher As mobilization. In natural levees, surface derived labile organic matter (DOC and FOM, Fresh Organic Matter) from different land-use patterns (Habitation, degraded waterbodies, cattle dwelling, sanitation, etc.) is transported to shallow aquifers (notably protein rich leakage sewage). The fresh organic carbon transported to the shallow aquifers, thereby triggering As release by microbe-mediated reductive dissolution of hydrated Fe(III)-oxides (HFO). Iron reduction (mostly amorphous) is playing an important role in the release of As depending on basin-wise sedimentation pattern, local recharge, accumulation of silt/clay/micas at the top with corresponding reactive oxidation of organic carbon. These are important components and often helping the cyclic water-rock interaction of As causing such heterogeneous geospatial distribution. The delineation of aquifer with regard to safer and unsafe areas would immensely help to supply safe drinking water to the rural community.
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Arsênio , Água Subterrânea , Poluentes Químicos da Água , Animais , Arsênio/análise , Bovinos , Monitoramento Ambiental , Compostos Férricos , Sedimentos Geológicos , Poluentes Químicos da Água/análiseRESUMO
This study identifies causes of rising arsenic (As) concentrations over 17 years in an inter-montane aquifer system located just north of the Trans-Mexican-Volcanic-Belt in the Mesa central physiographic region that is extensively developed by long-screened production wells. Arsenic concentrations increased by more than 10 µg/L in 14% (3/22) of re-sampled wells. Similarly, in a larger scale analysis wherein As concentrations measured in 137 wells in 2016 were compared to interpolated, baseline concentrations from 246 wells in 1999, As concentrations rose more than 10 µg/L in 30% of wells. Between 1999 and 2016, the percentage of all wells sampled in each basin-wide sampling campaign exceeding the World Health Organization's 10 µg/L drinking water limit increased from 38 to 64%. Principal Components Analysis (PCA), step-wise multiple regression, and Random Forest modeling (RF) revealed that high As concentrations are closely associated with high pH and temperature, and high concentrations of fluoride (F), molybdenum (Mo), lithium (Li), sodium (Na) and silica (Si), but low calcium (Ca) and nitrate (NO3) concentrations. Pumping-induced mixing with hot, geothermally impacted groundwater generates alkaline water through hydrolysis of silicate minerals. The rising pH converts oxyanion sorption sites from positive to negative releasing As (and Mo) to pore waters. The negative correlation between nitrate and As concentrations can be explained by conservative mixing of shallow, young groundwater with geothermally influenced groundwater. Therefore water carrying an anthropogenic contaminant dilutes water carrying geogenic contaminants. This process is enabled by long well screens. Over-exploitation of aquifers in geothermal regions for agriculture can drive As concentrations in water from production wells to toxic levels even as the total dissolved solids remain low.
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Arsênio , Água Subterrânea , Poluentes Químicos da Água , Arsênio/análise , Monitoramento Ambiental , México , Poluentes Químicos da Água/análiseRESUMO
BACKGROUND: Differences in patients' bone conditions lead to variations in the bio-mechanical environment at the peri-implant bone after implantation. It is therefore imperative to design patient-specific dental implants with customized stiffness to minimize stress shielding and better osseointegration. METHOD: Nine Ti-6Al-4V implants with pore sizes of 500, 700, 900 µm and 10, 20, 30% porosity each and one non-porous (solid) implant were modelled for experimental and finite element (FE) analysis. Using computed tomography (CT) data of the mandible, five different bone conditions were considered by varying bone density. Implants were fabricated using additive manufacturing, and micro-CT analysis was performed for assessing accuracy of fabricated implants and further modelling for FE analyses. The FE results were also compared with experimental results. RESULTS: Under a 200 N static load, the average difference between the experimental and FE observations of deformation was 9.7%. The peri-implant bone micro-strain revealed statistically significant interactions between percentage porosity (%porosity) and bone condition, as well as between pore size and %porosity (p < 0.05). In contrast, no statistically significant interaction between pore size and bone condition (p > 0.05) was observed. Together, %porosity and bone conditions contributed about 45.22% of the overall peri-implant bone micro-strain. CONCLUSIONS: Considering 1500-2000 as the maximum generated peri-implant bone micro-strain during regular physiological functioning, implants with 700 and 900 µm pore size and 10% porosity were deemed suitable for a 'very weak' bone condition. Contrarily, implants with 900 µm pore size and 30% porosity generated the highest peri-implant bone micro-strain for a 'normal' bone condition. Overall, the study establishes the necessity for considering the patient's bone condition as an important factor for the design of dental implants.
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Implantes Dentários , Mandíbula , Osseointegração , Análise de Elementos Finitos , Humanos , Mandíbula/diagnóstico por imagem , Mandíbula/cirurgia , Porosidade , Estresse Mecânico , TitânioRESUMO
In the present study, we investigated the possibilities and drawbacks of hollow fiber liquid phase microextraction (HF-LPME) combined with total reflection X-ray fluorescence (TXRF) spectrometry for the determination of low amounts of inorganic arsenic (As) species in water samples. The obtained results showed that a three-phase HF-LPME system was more suitable to be used in combination with TXRF than the two phase configuration, since lower detection limit and better precision for As determination can be attained. Relevant experimental parameters affecting As extraction (i.e. types of extractant, organic solvent, agitation speed, pH and extraction time) and TXRF analysis (deposition volume and drying mode) were systematically evaluated. It was found that As(III) was more efficiently extracted at pH 13, whereas, optimum pH for As(V) extraction was at pH 8.5. Limits of detection (LOD) achieved using the best analytical conditions meet the requirements of current legislation and allow the determination of inorganic As(V) and As(III) in water. The proposed method was also applied to different spiked environmental water samples for the preconcentration and subsequent determination of trace inorganic As species.
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Stress shielding due to difference in stiffness of bone and implant material is one among the foremost causes of loosening and failure of load-bearing implants. Thus far, femoral geometry has been given priority for the customization of total hip joint replacement (THR) implant design. This study, for the first time, demonstrates the key role of bone condition and subject-weight on the customization of stiffness and design of the femoral stem. In particular, internal hollowness was incorporated to reduce the implant stiffness and such designed structure has been customized based on subject parameters, including bone condition and bodyweight. The primary aim was to tailor these parameters to achieve close to natural strain distribution at periprosthetic bone and to reduce interfacial bone loss over time. The maintenance of interfacial bone density over time has been studied here through analysis of bone remodeling (BR). For normal bodyweight, the highest hollowness exhibited clinically relevant biomechanical response, for all bone conditions. However, for heavier subjects, consideration of bone quality was found to be essential as higher hollowness induced bone failure in weaker bones and implant failure in stronger bones. Moreover, for stronger bone, thinner medial wall was found to reduce bone resorption over time on the proximo-lateral zone of stress shielding, while lateral thinning was found advantageous for weaker bones. The findings of this study are likely to facilitate designing of femoral stems for achieving better physiological outcomes and enhancement of the quality of life of patients undergoing THR surgery.
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Prótese de Quadril , Artroplastia de Quadril , Fenômenos Biomecânicos , Fêmur , Qualidade de VidaRESUMO
PURPOSE: In this paper, the mechanical response of generic dental implants having calculated porosities with varying pore-sizes has been evaluated. The purpose of this study was to compare the developed stress-strain of designed porous implants (i.e., stress at the implant and strain at the peri-implant bone) with that of the non-porous implant. METHODS: 3D model of a mandible was prepared from CT scan data and nine generic dental implant models have been designed having 10%, 20%, and 30% porosity with 500, 700, and 900 micron pore size along with a non-porous model for carrying out FE analyses. First, failure analyses of implants, under a biting force of 250 N have been performed. Next, the remaining implants have been further evaluated under average compressive chewing load of 100 N, for mechanical responses at bone-implant interface. RESULTS: Von Mises strain at the peri-implant mandibular bone increases with the increase in percentage porosity of the implant material and maximum implant stress remained much below the yield stress level. CONCLUSION: Implant stiffness and compressive strength vary as a function of porosity and pore size. Strain obtained on the peri-implant bone is sufficient enough to facilitate better bone growth with the 700 micron pore size and 30% porosity, thus reducing the effect of stress shielding.
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Implantes Dentários , Análise de Elementos Finitos , Mandíbula/cirurgia , Fenômenos Biomecânicos , Humanos , Porosidade , Estresse MecânicoRESUMO
The objective is to make the strain deviation before and after implantation adjacent to the femoral implant as close as possible to zero. Genetic algorithm is applied for this optimization of strain deviation, measured in eight separate positions. The concept of composite desirability is introduced in such a way that if the microstrain deviation values for all eight cases are 0, then the composite desirability is 1. Artificial neural network (ANN) models are developed to capture the correlation of the microstrain in femur implants using the data generated through finite element simulation. Then, the ANN model is used as the surrogate model, which in combination with the desirability function serves as the objective function for optimization. The optimum achievable deviation was found to vary with the bone condition. The optimum implant geometry varied for different bone condition, and the findings act as guideline for designing patient-specific implant.
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Fêmur/anatomia & histologia , Prótese de Quadril , Desenho de Prótese , Algoritmos , Feminino , Análise de Elementos Finitos , Humanos , Pessoa de Meia-Idade , Redes Neurais de ComputaçãoRESUMO
Currently, intervertebral disc prostheses that are designed to restore mobility to a vertebral segment are possible for the lumbar spine. The ball-and-socket joint is a constrained design, wherein the rotational axis of the intervertebral joint is forced to pass through the center of the spherical surfaces that form the joint. One advantage of ball-and-socket joints versus unconstrained designs includes better shear stability, which results in sufficient flexibility. In this study, finite element analyses were performed in preimplanted and implanted (intervertebral disc replacement [IDR]) lumbar spine (L1-S) models to examine range of motion (ROM) and the resulting mechanical responses in the implant and the adjacent bones. Four physiological loading conditions including flexion, extension, and left and right lateral bending were analyzed to observe the effect on ROM under a 10-Newton meter moment. In terms of mechanical response, this study shows that disc replacement is an viable alternative to fusion surgery. The added advantage of IDR over fusion for degenerative discs is the reduced chance of disc degeneration at the adjacent segment of spinal vertebral column; with fusion surgery, chances of degeneration are increased.
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Degeneração do Disco Intervertebral/cirurgia , Disco Intervertebral , Vértebras Lombares/fisiopatologia , Vértebras Lombares/cirurgia , Próteses e Implantes , Fenômenos Biomecânicos , Simulação por Computador , Análise de Elementos Finitos , Humanos , Imageamento Tridimensional , Degeneração do Disco Intervertebral/diagnóstico por imagem , Vértebras Lombares/diagnóstico por imagem , Amplitude de Movimento Articular , Tomografia Computadorizada por Raios XRESUMO
The goal of this finite element study is to reduce the stress shielding effect in tibial fracture fixation. Five different plates with modified geometry have been modeled. The fracture gap is assumed to be filled with callus, which is new born healing tissue. The effect of different plate modifications in four different healing stages has been compared to the nonmodified plate. It has been observed that all the modified models have higher callus stress than the nonmodified model, and the best modified plate has reduced the stress shielding effect by 117% for the first healing stage. It has also been observed that the effect of different plate modification is prominent during only the first and second healing stages.
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Placas Ósseas , Fixação Interna de Fraturas/instrumentação , Consolidação da Fratura , Desenho de Prótese , Fraturas da Tíbia/cirurgia , Módulo de Elasticidade , Análise de Elementos Finitos , Humanos , Modelos Anatômicos , Suporte de CargaRESUMO
The biogeochemical cycling of phosphorus (P) in South and Southeast Asian floodplain and delta aquifers has received insufficient attention in research studies, even though dissolved orthophosphate (PO43-) in this region is closely linked with the widespread contamination of groundwater with toxic arsenic (As). The overarching aim of this study was to characterize the enrichment of P in anoxic groundwater and to provide insight into the biogeochemical mechanisms underlying its mobilization, subsurface transport, and microbial cycling. Detailed groundwater analyses and in situ experiments were conducted that focused on three representative field sites located in the Red River Delta (RRD) of Vietnam and the Bengal Delta Plain (BDP) in West Bengal, India. The results showed that the total concentrations of dissolved P (TDP) ranged from 0.03 to 1.50â¯mgâ¯L-1 in groundwater, with PO43- being the dominant P species. The highest concentrations occurred in anoxic sandy Holocene aquifers where PO43- was released into groundwater through the microbial degradation of organic carbon and the concomitant reductive dissolution of Fe(III)-(hydr)oxides. The mobilization of PO43- may still constitute an active process within shallow Holocene sediments. Furthermore, a sudden supply of organic carbon may rapidly decrease the redox potential, which causes an increase in TDP concentrations in groundwater, as demonstrated by a field experiment. Considering the subsurface transport of PO43-, Pleistocene aquifer sediments represented effective sinks; however, the enduring contact between oxic Pleistocene sediments and anoxic groundwater also changed the sediments PO43--sorption capacity over time. A stable isotope analysis of PO43--bound oxygen indicated the influences of intracellular microbial cycling as well as a specific PO43- source with a distinct isotopically heavy signal. Consequently, porous aquifers in Asian floodplain and delta regions proved to be ideal natural laboratories to study the biogeochemical cycling of P and its behavior in groundwater environments.