Defect interactions in a two-dimensional sheared lamellar mesophase.

The interaction between two edge dislocations in a sheared lyotropic lamellar liquid-crystalline medium is examined. The model is a mesoscale hydrodynamic model based on a free-energy functional that is minimised for a sinusoidal concentration modulation coupled with concentration and momentum equations. The defect dynamics are analysed as a function of the system size and the Ericksen number, the ratio of the shear stress and the characteristic free-energy density for deformation. Three different regimes are observed as the Ericksen number is increased when the edge dislocations are sheared towards each other, such that there is compression of layers between the defects: (a) defect motion that reduces the cross-stream separation till there is a steady spacing with plug flow between the defects, (b) defect attraction and cancellation resulting in a well-aligned state, and (c) defect creation due to a compressional instability between the defects resulting in an increase in the disorder. When the edge dislocations are sheared away from each other, such that there is extension of the layers between the defects, two distinct regimes are observed as the Ericksen number is increased: (a) bending of layers and a plug flow between the defects at their initial separation, and (b) buckling of the layers leading to creation of more defects and a dynamical steady state between defect creation and cancellation. These regimes are found to be robust for different values of the system size, from 32 to 128 layers, and for different values of the dimensionless groups that characterise the ratio of mass/momentum convection and diffusion.

Knowledge, attitude and practices of indigenous people towards non-communicable disease in Bera, Malaysia: A community-based study.

INTRODUCTION: With the current trend of increasing noncommunicable diseases (NCD), like hypertension, diabetes and dyslipidaemia worldwide and in Malaysia, a comprehensive study is essential to find the local population's knowledge, attitude and practice towards NCD. Little is known about the indigenous people of Orang Asli's health conditions and health-seeking behaviours towards these chronic diseases. The study aimed to assess knowledge, attitudes and practices (KAP) status towards non-communicable disease and its association with demographic background among Orang Asli adults of the Semelai subgroup in central Pahang, Malaysia. MATERIALS AND METHODS: A cross-sectional study was conducted among 251 adult Semelai people in Bera district, Pahang. Data was collected through face-to-face interviews to obtain socio-demographic data, KAP towards NCD. Bivariate analysis was performed to test the association between the socio-demographic factor and the KAP score. RESULTS: Among respondents, 57.4% were female, 82.5% were married, and 46.2% completed primary school. The majority were animism believers (83.3%), self-employed (75.3%) and earning less than RM1000 (87.6%). The respondents' ages ranged from 18 to 77, with a mean age of 41.1 (S.D ± 13.9). The prevalence of known type-2 diabetes mellitus (T2DM), hypertension, and dyslipidaemia was 9.6%, 20.7%, and 8.8%, respectively. About 23.1% of respondents have a family history of chronic disease. Regarding KAP parameters, only 12.7% have good knowledge, and 35.5% have good practice in prevention and treatment. However, more than half (59.8%) have a positive attitude towards chronic diseases. This study also showed that higher household income and education levels were positively associated with higher scores of KAP (p < 0.001). CONCLUSION: This study presented a low-to-moderate percentage of Orang Asli who have good KAP towards NCD. KAP levels were significantly associated with education levels and household income. Hence, improving education and poverty in the Orang Asli community may successively increase the knowledge level, impart a positive attitude towards NCDs, and improve the practice level toward treatment and prevention.

The relationship between structure and rheology in a three-dimensional sheared lamellar mesophase.

The evolution of a lamellar mesophase from an initially disordered state under shear is examined using simulations of a mesoscale model based on a concentration field ψ that distinguishes the hydrophilic and hydrophobic components. The Landau-Ginzburg free-energy functional is augmented by a term that is minimised for sinusoidal modulations in the concentration field with wavelength λ = (2π/k), and the dynamical equations are the model H equations. The structure and rheology are determined by the relative magnitudes of the diffusion time for coarsening, (λ2/D) and the inverse of the strain rate -1, and the Ericksen number, which is the ratio of the shear stress and the layer stiffness. When the diffusion time is small compared with the inverse of the strain rate, there is a local formation of misaligned layers, which are deformed by the imposed flow. There is near-perfect ordering with isolated defects at low values of the Ericksen number, but the defects result in a significant increase in viscosity due to the high layer stiffness. At high values of the Ericksen number, the concentration field is deformed by the mean shear before layers form via diffusion. Cylindrical structures aligned along the flow direction form after about 8-10 strain units, and these evolve into layers with disorder through diffusion perpendicular to the flow. The layers are not perfectly ordered, even after hundreds of strain units, due to the creation and destruction of defects via shear. The excess viscosity is low because the layer stiffness is small compared with the applied shear at a high Ericksen number. This study provides guidance on how the material parameters and imposed flow can be tailored to achieve the desired rheological behaviour.

Magnetorheological fluids containing rod-shaped lithium-zinc ferrite particles: the steady-state shear response.

We report the magnetic field and particle-concentration dependent steady-state shear-responses of rod shaped Li-Zn ferrite particle based magnetorheological fluids (MRFs). Rod-shaped soft ferrimagnetic Li-Zn ferrite (Li0.4Zn0.2Fe2.4O4) particles were synthesized using the combustion synthesis method. MRFs of three different particle-concentrations (φ = 0.1, 0.2 and 0.4, in weight fraction) were prepared using silicone oil. Their yield strength and dynamic viscosity were studied at different applied magnetic fields (B). With an increase in B and φ, the yield strength (τY) of the MRFs increases. This behaviour is assigned to the formation of stronger columnar structures of the magnetically interacting particles which resist the flow (shear) of the MRF. For the MRF with φ = 0.4 and B = 1.2 T, we observed a maximum τY value of ∼1.25 kPa. Furthermore, we observed that, based on the on-state to off-state viscosity ratio (ηon/ηoff) at a particular operating B value, the optimum particle concentration required for energy- and cost-efficient operation of the MRFs can be chosen. The absence of a stabilizing-agent or de-agglomerating-coating, the low density, and the excellent oxidation- and corrosion-resistance of the soft ferrimagnetic rod-shaped Li-Zn ferrite particles make this MRF-system highly versatile and economical for many magneto-mechanical applications.

Magnetic field dependent steady-state shear response of Fe3O4 micro-octahedron based magnetorheological fluids.

We report the synthesis of single crystalline octahedron-shaped magnetite microcrystals, the preparation of magnetorheological fluids (MRFs) and their magnetorheological properties under steady-state shear conditions. The magnetite microcrystals were synthesized via the template-free hydrothermal route. MRFs with three different particle concentrations (10, 20 and 40 weight%) were prepared and were subjected to steady shear conditions at various externally applied magnetic fields of strength up to 1.2 T. The shear rates were chosen up to high enough values to observe the yield behaviour of the MRFs. The dynamic yield strengths of MRFs, estimated using the Bingham plastic model fit to the steady-state shear response curves, showed that they scale-up with the applied magnetic field strength and amount of magnetic particles in the fluid. The origin of the mechanical strength in the MRFs due to the inter-particle interaction is explained using a simple dipolar model. The observed high yield strengths of the MRFs were explained on the basis of the particle shape (octahedrons) and magnetic nature (saturation magnetization). By comparing the values of the yield strength with the on-state to off-state viscosity ratio for the MRFs (for each particle concentration), an optimum content of particles in the carrier fluid to obtain high efficiency is suggested. Because the particles are single crystalline, the off-state viscosity of the MRFs even at the highest studied (40 wt%) particle concentration was very low, which is ideal for their application as quickly responding MRFs.

Fabrication of electrodes with ultralow platinum loading by RF plasma processing of self-assembled arrays of Au@Pt nanoparticles.

Conductive, carbon-free, electrocatalytically active, nanostructured electrodes with ultra-low platinum loading were fabricated using self-assembly of octadecanethiol-coated Au@Pt nanoparticles followed by RF plasma treatment. Bilayer arrays of Au@Pt nanoparticles with platinum loadings of 0.50, 1.04, 1.44, and 1.75 µg cm(-2) (corresponding to 0.5, 1, 1.5 and 2 atomic layer coverage of platinum on nominally 5 nm gold core) were subjected to RF argon plasma treatment for various durations and their electrical conductivity, morphological evolution, and electrocatalytic activity characterized. Samples with monolayer and above platinum coverages exhibit maximum electrochemically active surface areas values of ∼100 m(2)/gpt and specific activities that are ∼4× to 6× of a reference platinum nanoparticle bilayer array. The underlying gold core influences the structural evolution of the samples upon RF plasma treatment and leads to the formation of highly active Pt(110) facets on the surface at an optimal plasma treatment duration, which also corresponds to the onset of a sharp decline in lateral sheet resistance. The sample having a two atom thick platinum coating has the highest total mass activity of 48 ± 3 m(2)/g(pt+au), corresponding to 44% Pt atom utilization, while also exhibiting enhanced CO tolerance as well as high methanol oxidation reaction and oxygen reduction reaction activity.

System size dependence of the structure and rheology in a sheared lamellar liquid crystalline medium.

The structural and rheological evolution of an initially disordered lamellar phase system under a shear flow is examined using a mesoscale model based on a free energy functional for the concentration field, which is the scaled difference in the concentration between the hydrophilic and hydrophobic components. The dimensionless numbers which affect the shear evolution are the Reynolds number (γ˙¯L2/ν), the Schmidt number (ν/D), a dimensionless parameter Σ=(Aλ2/ρν2), a parameter µr which represents the viscosity contrast between the hydrophilic and hydrophobic components, and (L/λ), the ratio of system size and layer spacing. Here, ρ, ν, and D are the density, kinematic viscosity (ratio of viscosity and density), and the mass diffusivity, and A is the energy density in the free energy functional which is proportional to the compression modulus. Two distinct modes of structural evolution are observed for moderate values of the parameter Σ depending only on the combination ScΣ and independent of system size. For ScΣ less than about 10, the layers tend to form before they are deformed by the mean shear, and layered but misaligned domains are initially formed, and these are deformed and rotated by the flow. In this case, the excess viscosity (difference between the viscosity and that for an aligned state) does not decrease to zero even after 1000 strain units, but appears to plateau to a steady state value. For ScΣ greater than about 10, layers are deformed by the mean shear before they are fully formed, and a well aligned lamellar phase with edge dislocation orders completely due to the cancellation of dislocations. The excess viscosity scales as t-1 in the long time limit. The maximum macroscopic viscosity (ratio of total stress and average strain rate over the entire sample) during the alignment process increases with the system size proportional to (L/λ)3/2. For large values of Σ, there is localisation of shear at the walls, and the bulk of the sample moves as a block. The thickness of the shearing region appears to be invariant with the system size, leading to an increase of viscosity proportional to L. The time for structural evolution is found to be the inverse of the strain rate γ˙-1. In the case of a significant viscosity contrast between the hydrophilic and hydrophobic parts, the average viscosity increases by 1-2 orders of magnitude due to the defect pinning mechanism, where the regions between defects move as a block, and shear localisation at the wall.

Laterally structured ripple and square phases with one and two dimensional thickness modulations in a model bilayer system.

Molecular dynamics simulations of bilayers in a surfactant/co-surfactant/water system with explicit solvent molecules show formation of topologically distinct gel phases depending upon the bilayer composition. At low temperatures, the bilayers transform from the tilted gel phase, Lß', to the one dimensional (1D) rippled, Pß' phase as the surfactant concentration is increased. More interestingly, we observe a two dimensional (2D) square phase at higher surfactant concentration which, upon heating, transforms to the gel Lß' phase. The thickness modulations in the 1D rippled and square phases are asymmetric in two surfactant leaflets and the bilayer thickness varies by a factor of ∼2 between maximum and minimum. The 1D ripple consists of a thinner interdigitated region of smaller extent alternating with a thicker non-interdigitated region. The 2D ripple phase is made up of two superimposed square lattices of maximum and minimum thicknesses with molecules of high tilt forming a square lattice translated from the lattice formed with the thickness minima. Using Voronoi diagrams we analyze the intricate interplay between the area-per-head-group, height modulations and chain tilt for the different ripple symmetries. Our simulations indicate that composition plays an important role in controlling the formation of low temperature gel phase symmetries and rippling accommodates the increased area-per-head-group of the surfactant molecules.

Microfluidic mixing by magnetic particles: Progress and prospects.

Microfluidic systems have enormous potential for enabling point-of-care diagnostics due to a number of advantages, such as low sample volumes, small footprint, low energy requirements, uncomplicated setup, high surface-to-volume ratios, cost-effectiveness, etc. However, fluid mixing operations are constrained by molecular diffusion since the flow is usually in the laminar regime. The slow nature of molecular diffusion is a technological barrier to implementing fluid transformations in a reasonable time. In this context, magnetically actuated micro-mixers of different sizes, shapes, materials, and actuation techniques provide a way to enhance fluid mixing in microfluidic devices. In this paper, we review the currently existing micro-mixing technologies. From a fundamental perspective, the different magnetization models for permanent and induced dipoles are discussed. The single-particle dynamics in steady and oscillating magnetic fields is studied in order to determine the flow generated and the torque exerted on the fluid due to the magnetic particles. The effect of particle interactions, both magnetic and hydrodynamic, is examined.

A note on the unimodality and log-concavity of the exponentiated Teissier distribution.

Recently, Sharma et al. (Exponentiated Teissier distribution with increasing, decreasing and bathtub hazard functions, J. Appl. Stat. 49 (2022), pp. 371-393) introduced the exponentiated Teissier distribution. Unfortunately, the proof given for the log-concavity of the probability density function and log-concave for α ≥ 1 only, are incorrect. Also, the information related to the unimodality of the distribution is incomplete. In this note, numerically, graphically and analytically, the necessary corrections have been made.

Perceptiveness and Attitude on the use of Artificial Intelligence (AI) in Dentistry among Dentists and Non-Dentists - A Regional Survey.

Artificial intelligence (AI) is an emerging tool in modern medicine and the digital world. AI can help dentists diagnose oral diseases, design treatment plans, monitor patient progress and automate administrative tasks. The aim of this study is to evaluate the perception and attitude on use of artificial intelligence in dentistry for diagnosis and treatment planning among dentists and non-dentists' population of south Tamil Nadu region in India. Materials and Methods: A cross sectional online survey conducted using 20 close ended questionnaire google forms which were circulated among the dentists and non -dentists population of south Tamil Nadu region in India. The data collected from 264 participants (dentists -158, non-dentists -106) within a limited time frame were subjected to descriptive statistical analysis. Results: 70.9% of dentists are aware of artificial intelligence in dentistry. 40.5% participants were not aware of AI in caries detection but aware of its use in interpretation of radiographs (43.9%) and in planning of orthognathic surgery (42.4%) which are statistically significant P < 0.05.44.7% support clinical experience of a human doctor better than AI diagnosis. Dentists of 54.4% agree to support AI use in dentistry. Conclusion: The study concluded AI use in dentistry knowledge is more with dentists and perception of AI in dentistry is optimistic among dentists than non -dentists, majority of participants support AI in dentistry as an adjunct tool to diagnosis and treatment planning.

On the origin of the biological effects of time varying magnetic fields: quantitative insights.

In a number of recently published experimental studies from our research group, the positive impact of magnetic stimuli (static/pulsed) on cell functionality modulation or bactericidal effects, in vitro, has been established. In order to develop a theoretical understanding of such magnetobiological effects, the present study aimed to present two quantitative models to determine magnetic Maxwell stresses as well as pressure acting on the cell membrane, under the influence of a time varying magnetic field. The model predicts that magnetic field-induced stress on the cell/bacteria is dependent on the conductivity properties of the extracellular region, which is determined to be too low to cause any significant effect. However, the force on the cell/bacteria due to the induced electric field is more influential than that of the magnetic field, which has been used to determine the membrane tension that can cause membrane poration. With a known critical membrane tension for cells, the field parameters necessary to cause membrane rupture have been estimated. Based on the experimental results and theoretically predicted values, the field parameters can be classified into three regimes, wherein the magnetic fields cause no effect or result in biophysical stimulation or induce cell death due to membrane damage. Taken together, this work provides some quantitative insights into the impact of magnetic fields on biological systems.

Dynamics of edge dislocations in a sheared lamellar mesophase.

The dynamics and interactions of edge dislocations in a nearly aligned sheared lamellar mesophase is analysed to provide insights into the relationship between disorder and rheology. First, the mesoscale permeation and momentum equations for the displacement field in the presence of external forces are derived from the model H equations for the concentration and momentum field. The secondary flow generated due to the mean shear around an isolated defect is calculated, and the excess viscosity due to the presence of the defect is determined from the excess energy dissipation due to the secondary flow. The excess viscosity for an isolated defect is found to increase with system size in the cross-stream direction as L(3/2) for an isolated defect, though this divergence is cut-off due to interactions in a defect suspension. As the defects are sheared past each other due to the mean flow, the Peach-Koehler force due to elastic interaction between pairs of defects is found to cause no net displacement relative to each other as they approach from large separation to the distance of closest approach. The equivalent force due to viscous interactions is found to increase the separation for defects of opposite sign, and decrease the separation for defects of same sign. During defect interactions, we find that there is no buckling instability due to dilation of layers for systems of realistic size. However, there is another mechanism, which is the velocity difference generated across a slightly deformed bilayer due to the mean shear, which could result in the creation of new defects.

Efficient data transmission on wireless communication through a privacy-enhanced blockchain process.

In the medical era, wearables often manage and find the specific data points to check important data like resting heart rate, ECG voltage, SPO2, sleep patterns like length, interruptions, and intensity, and physical activity like kind, duration, and levels. These digital biomarkers are created mainly through passive data collection from various sensors. The critical issues with this method are time and sensitivity. We reviewed the newest wireless communication trends employed in hospitals using wearable technology and privacy and Block chain to solve this problem. Based on sensors, this wireless technology controls the data gathered from numerous locations. In this study, the wearable sensor contains data from the various departments of the system. The gradient boosting method and the hybrid microwave transmission method have been proposed to find the location and convince people. The patient health decision has been submitted to hybrid microwave transmission using gradient boosting. This will help to trace the mobile phones using the calls from the threatening person, and the data is gathered from the database while tracing. From this concern, the data analysis process is based on decision-making. They adapted the data encountered by the detailed data in the statistical modeling of the system to produce exploratory data analysis for satisfying the data from the database. Complete data is classified with a 97% outcome by removing unwanted data and making it a 98% successful data classification.

Diabetes self-care activities: a community-based survey in urban southern India.

BACKGROUND: Diabetes is a lifestyle disease and can be successfully managed by good self-care activities such as diet, exercise, monitoring and drug adherence. Adequate baseline information about the prevalence of good self-care activities is not available from India. We aimed to estimate the existing self-care behaviours and factors influencing these behaviours among adult patients with type 2 diabetes in urban southern India. METHODS: A cross-sectional survey was conducted using a cluster design in an urban community in southern India. The Summary Diabetes Self-Care Activities questionnaire was used to collect information on diet, exercise, monitoring of blood sugars and adherence to drugs. Risk factors such as marital status, socioeconomic status, depression, benefit-finding and duration of illness, which are likely to influence self-care behaviour, were assessed. RESULTS: Good dietary behaviour was present in 29% (95% CI 20.8%-37.2%), good exercise behaviour in 19.5% (95% CI 17.4%-21.6%), regular blood sugar monitoring in 70% (95% CI 62.2%-77.8%) and drug adherence in 79.8% (95% CI 75.1%-84.5%). Being male (OR 3.38; 95% CI 1.541-7.407) and married (OR 5.60; 95% CI 1.242-25.212) significantly favoured good exercise behaviour. Being married (OR 2.322; 95% CI 1.104-4.883) and belonging to the higher socioeconomic status (OR 2.713; 95% CI 1.419-5.190) were significantly associated with monitoring of blood sugars. CONCLUSIONS: Self-care activities with respect to diet and exercise are poor in the population studied. The self-care activities relating to blood sugar monitoring and drug adherence are good. Improving self-care behaviour among patients with diabetes in India should start with adequate targeted health education.

Influence of early rising on performance in tasks requiring attention and memory.

Rising early in the morning has been a prescribed discipline of ancient Indian tradition. While there are no scientific studies comparing early rising volitionally versus circumstantially, selected studies on the latter (rising forcefully) have shown negative impact on an individual's peroformance. Hence the present study was undertaken to assess the influence of early rising (during Brahma-muhurtha) on tasks requiring attention and the ability to recall. Fifty four normal healthy male volunteers, with ages ranging from 16-22 years from a residential school were selected. They were randomly allocated to two groups (Brahma-muhurtha and control). They were assessed on day 1, day 10 and day 20 of the intervention, using a digit letter substitution task and verbal and spatial memory task. The Brahma-muhurtha group were asked to rise before 4:30 am in the morning based on the traditional Indian astrological calculations, while the control group were allowed to wake up just before 7 am which was their regular timing for waking. Brahma-muhurtha group after 20 days showed a significant improvement in the net scores for digit letter substitution task as well as scores for verbal and spatial memory tasks. The control group also showed an improvement in the memory task but not in the task requiring attentional processes. The present study suggests that rising early in the morning as described in ancient Indian tradition influences the process of attention and can improve the ability to recall.

Moving efficiently through a crowd: A nature-inspired traffic rule.

In this article, we propose a traffic rule inspired from nature that instructs how a crowd made up of inert agents should respond to an elite agent to facilitate its motion through the crowd. When an object swims in a fluid medium or an intruder is forced through granular matter, characteristic flow fields are created around them. We show that if inert agents made small movements based on a traffic rule derived from these characteristic flow fields, then they efficiently reorganize and transport enough space for the elite to pass through. The traffic rule used in the article is a dipole field which satisfactorily captures the features of the flow fields around a moving intruder. We study the effectiveness of this dipole traffic rule using numerical simulations in a two-dimensional periodic domain, where one self-propelled elite agent tries to move through a crowd of inert agents that prefer to stay in a state of rest. Simulations are carried out for a wide range of strengths of the traffic rule and packing densities of the crowd. We characterize and analyze four regions in the parameter space-free-flow, motion due to cooperation and frozen and collective drift regions-and discuss the consequence of the traffic rule in light of the collective behavior observed. We believe that the proposed method can be of use in a swarm of robots working in constrained environments.

Author Correction: A cartridge based Point-of-Care device for complete blood count.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

The influence of bilayer composition on the gel to liquid crystalline transition.

We report molecular dynamics simulations of bilayers using a united atom model with explicit solvent molecules. The bilayer consists of the single tail cationic surfactant behenyl trimethyl ammonium chloride (BTMAC) with stearyl alcohol (SA) as the cosurfactant. We study the gel to liquid crystalline transitions in the bilayer by varying the amount of water at fixed BTMAC to SA ratio as well as by varying the BTMAC to SA ratio at fixed water content. The bilayer is found to exist in the tilted, L(beta') phase at low temperatures, and for the compositions investigated in this study, the L(beta') to L(alpha) melting transition occurred in the temperature range 330-338 K. For the highest BTMAC to SA composition (2:3 molar ratio), a diffuse headgroup-water interface is observed at lower temperatures, and an increase in the d-spacing occurs prior to the melting transition. This pretransition swelling is accompanied by a sharpening in the water density variation across the headgroup region of the bilayer. Signatures of this swelling effect which can be observed in the alkane density distributions, area per headgroup, and membrane thickness are attributed to the hydrophobic effect. At a fixed bilayer composition, the transition temperature (>338 K) from the L(beta') to L(alpha) transition obtained for the high water content bilayer (80 wt %) is similar to that obtained with low water content (54.3 wt %), confirming that the melting transition at these water contents is dominated by chain melting.

Mesoscale description of an asymmetric lamellar phase.

The relationship between the parameters in a description based on a mesoscale free energy functional for the concentration field and the macroscopic properties, such as the bending and compression moduli and the permeation constant, are examined for an asymmetric lamellar phase where the mass fractions of the hydrophobic and hydrophilic parts are not equal. The difference in the mass fractions is incorporated using a cubic term in the free energy functional, in addition to the usual quadratic and quartic terms in the Landau-Ginsburg formulation. The relationship between the coefficient of the cubic term and the difference in the mass fractions of the hydrophilic and hydrophobic parts is obtained. For a lamellar phase, it is important to ensure that the surface tension is zero due to symmetry considerations. The relationship between the parameters in the free energy functional for zero surface tension is derived. When the interface between the hydrophilic and hydrophobic parts is diffuse, it is found that the bending and compression moduli, scaled by the parameters in the free energy functional, do increase as the asymmetry in the bilayer increases. When the interface between the hydrophilic and hydrophobic parts is sharp, the scaled bending and compression moduli show no dependence on the asymmetry in the bilayer. The ratio of the permeation constant in between the water and bilayer in a molecular description and the Onsager coefficient in the mesoscale description is O(1) for both sharp and diffuse interfaces and it increases as the difference in the mass fractions is increased.