Screening the UV‐blocking and antimicrobial properties of herbal nanoparticles prepared from Aloe vera leaves for textile applications

Nanomaterials play a vital role in textile industries due to their unique properties and applications. There is an increase in the use of nanoscale phyto products in textiles to control the bacterial infection in fabrics. Here, natural herbal nanoparticles of different sizes were prepared from shade‐dried Aloe vera plant leaves using ball milling technique without any additives. The amorphous herbal A. vera nanoparticles possess an average particle size of 40 ± 2 nm and UV‐absorption maximum at 269 nm. A. vera nanopowders–chitosan nanocomposites were prepared and coated on cotton fabrics using pad‐dry cure method. The evaluation of antibacterial activity against Escherichia coli (22.05 ± 0.06 mm) and Staphylococcus aureus (27.17 ± 0.02 mm), UV‐protection properties (UV‐protection factor = 57.2 ± 0.1), and superhydrophobic nature (155 ± 3°) of the prepared herbal nanoparticles and their composites were analysed by disc diffusion, UV–visible spectral analysis, and contact angle analysis. Understanding the functional properties of herbal nanoparticles, coated particles on fabrics highlights their potential applications in protective clothing with better antimicrobial properties, hydrophobicity, and UV‐protection properties. This study of using A. vera herbal nanoparticles in textiles significantly enhances the fabric performance to develop protective textile fabrics in defence and biomedical fields.Inspec keywords: nanoparticles, particle size, nanofabrication, nanomedicine, antibacterial activity, biomedical materials, hydrophobicity, ultraviolet spectra, visible spectra, radiation protection, textile fibres, cotton fabrics, ball milling, X‐ray diffraction, light scattering, scanning electron microscopy, X‐ray fluorescence analysis, fluorescence, amorphous state, nanocomposites, filled polymers, protective coatings, curing, microorganisms, biodiffusion, contact angle, surface morphology, protective clothingOther keywords: UV‐blocking, antimicrobial properties, disc diffusion, UV‐visible spectral analysis, contact angle analysis, morphological characteristics, protective clothing, protective textile fabrics, biomedical fields, superhydrophobic nature, UV‐protection factor, UV‐protection properties, Staphylococcus aureus, Escherichia coli, pad‐dry cure method, cotton fabrics, A. vera nanopowders‐chitosan nanocomposites, UV‐absorption maximum, average particle size, amorphous herbal A. vera nanoparticles, X‐ray fluorescence spectrometry, scanning electron microscopy, dynamic light scattering, UV‐visible spectrophotometry, X‐ray diffraction, ball milling, shade‐dried Aloe vera plant leaves, natural herbal nanoparticle size, bacterial infection, nanoscale phyto products, textile industries, nanomaterials, textile applications     

Efficient trace and revoke schemes

Our goal is to design encryption schemes for mass distribution of data , which enable to (1) deter users from leaking their personal keys, (2) trace the identities of users whose keys were used to construct illegal decryption devices, and (3) revoke these keys as to render the devices dysfunctional. We start by designing an efficient revocation scheme, based on secret sharing. It can remove up to t parties, is secure against coalitions of up to t users, and is more efficient than previous schemes with the same properties. We then show how to enhance the revocation scheme with traitor tracing and self-enforcement properties. More precisely, how to construct schemes such that (1) each user’s personal key contains some sensitive information of that user (e.g., the user’s credit card number), in order to make users reluctant to disclose their keys. (2) An illegal decryption device discloses the identity of users that contributed keys to construct the device. And, (3) it is possible to revoke the keys of corrupt users. For the last point, it is important to be able to do so without publicly disclosing the sensitive information.     

F-SIFT and FUZZY-RVM based efficient multi-temporal image segmentation approach for remote sensing applications

Image segmentation plays a most important role in the remote sensing applications, for the efficient detection of the Earth surface. The main objective of the segmentation process is to modify and simplify the representation of an image into an easier form for efficient analysis. The performance of the image segmentation process reduces due to the occurrence of noise and disturbances in the image. Existing segmentation approaches suffer from the performance degradation in the segmentation accuracy owing to the quality of the acquired satellite image. To overcome these drawbacks, this paper proposes an efficient image segmentation process for the clear view of the multi-temporal satellite image. Gaussian Filter (GF) is used for filtering the image to remove the noises present in the image. PSO-Affine based image registration is applied for the extraction of the pixel points and registration of the multi-temporal image. Removal of cloud from the image is performed to get a clear view of the image. Feature extraction is performed by using the Fast-Scale Invariant Feature Transform (F-SIFT) approach. The feature points of the image are extracted to form the cluster including six different classes such as building area, road area, vegetation area, tree area, water area and land area. The classes of the cluster are recognized by using the Fuzzy-Relevance Vector Machine (F-RVM) algorithm. The proposed approach achieves better performance in the cloud removal and efficient image segmentation.     

Simulation of cavity formation in underground coal gasification using bore hole combustion experiments

Studies on the growth of three-dimensional cavity geometries in underground coal gasification (UCG) are important in exploiting the large fraction of coal that is present in underground coal seams. In the present study, the cavity formation in UCG has been simulated using experiments carried out in three configurations: (i) sublimation experiments in camphor simulating primarily the heat transfer aspects, (ii) bore hole combustion in Acacia nilotica wood bringing in chemical reaction into play, and (iii) bore hole combustion a coal block bringing into consideration the effect of ash on the cavity formation. In all the three cases, the time-evolution of the cavity shape has been monitored under constant oxygen flow rate conditions by measuring the cavity shape and size at periodic intervals. Results show that the cavity formation rates as well as the shape of the cavity are significantly affected by the oxidant flow rate. The importance of the ash present in the coal on the cavity growth has also been brought out. A fair amount of gasification leading to the formation of H₂, CO and CH₄ was observed; this is shown to depend both on the inherent moisture as well as on the reaction zone temperature.     

Static buckling analysis of thin cylindrical shell with centrally located dent under uniform lateral pressure

One of the common failure modes of thin cylindrical shell subjected to external pressure is buckling. The buckling pressure of these shell structures are dominantly affected by the geometrical imperfections present in the cylindrical shell which are very difficult to alleviate during manufacturing process. Dent is one of the common geometrical imperfections present in thin shell structures which may be formed due to mechanical damage caused by accidental loading or impact. In this work, influence of various dent parameters (dent length, dent width, dent depth and angle of orientation of the dent) on the critical buckling pressure of thin cylindrical shells with a centrally located dent is studied using non-linear static finite-element analysis of ANSYS under external pressure with simply supported boundary conditions at the top and bottom edges of the thin cylindrical shell.     

On the time and space complexity of computation using write-once memory or is pen really much worse than pencil?

We introduce a model of computation based on the use of write-once memory. Write-once memory has the property that bits may be set but not reset. Our model consists of a RAM with a small amount of regular memory (such as logarithmic orn ^α for α<1, wheren is the size of the problem) and a polynomial amount of write-once memory. Bounds are given on the time required to simulate on write-once memory algorithms which originally run on a RAM with a polynomial amount of regular memory. We attempt to characterize algorithms that can be simulated on our write-once memory model with very little slow-down. A persistent computation is one in which, at all times, the memory state of the computation at any previous point in time can be reconstructed. We show that any data structure or computation implemented on this write-once memory model can be made persistent without sacrificing much in the way of running time or space. The space requirements of algorithms running on the write-once model are studied. We show that general simulations of algorithms originally running on a RAM with regular memory by algorithms running on our write-once memory model require space proportional to the number of steps simulated. In order to study the space complexity further, we define an analogue of the pebbling game, called the pebble-sticker game. A sticker is different from a pebble in that it cannot be removed once placed on a node of the computation graph. As placing pebbles correspond to writes to regular memory, placing stickers correspond to writes to the write-once memory. Bounds are shown on pebble-sticker tradeoffs required to evaluate trees and planar graphs. Finally, we define the complexity class WO-PSPACE as the class of problems which can be solved with a polynomial amount of write-once memory, and show that it is equal toP. The research of S. Irani was supported by NSF Grant No. DCF-85-13926, and a Tandem Corporation Fellowship. R. Rubinfeld's research was supported by NSF Grant No. CCR 88-13632 and an IBM Graduate Fellowship.     

Diimidazo[1,2-c:4'',5''-e]pyrimidines: adenosine agonist activity demonstrated by microphysiometry

Vertigo and dizziness are not common in childhood, but are probably present more often than was formerly thought. These symptoms caused mainly by o700is media and middle ear effusion, two of the most common diseases in children, have been neglected for a long time, both in the literature and in practice, until recently. The purpose of this study was to determine objectively the incidence of balance-related symptoms in children with long-lasting middle ear effusion and to discover whether these symptoms resolve after the insertion of ventilation tubes. One hundred thirty-six children, ages 4 to 9 years, were given electronystagmographic tests and the Bruininks-Oseretsky tests for motor proficiency before and after tube ventilation of the middle ear. The results were compared with those in 74 healthy children with no history of middle ear diseases. Pathologic findings were found in 58% of the children with chronic middle ear effusion, as compared with only 4% of the control group. The symptoms and signs of balance disturbances resolved in 96% of the children after ventilation tube insertion. The results of this study indicate that balance-related symptoms often encountered in young children may result from chronic middle ear effusion and that these symptoms will resolve after evacuation of the effusion and ventilation of the middle ear.     

Metallurgical Characteristics of TiAlN/AlCrN Coating Synthesized by the PVD Process on a Cutting Insert

TiAlN/AlCrN coating was deposited on a tungsten carbide insert, using the plasma-enhanced physical vapor deposition (PEPVD) process. The microstructure of the coating was examined and it was found that the TiAlN/AlCrN coating was uniform, highly dense, and less porous. The different phases formed in the coating were analyzed using the x-ray diffraction. The hardness and scratch resistance were measured using the nanoindentation tester and scratch tester, respectively. TiAlN/AlCrN exhibited higher hardness, higher Young’s modulus, and superior scratch resistance when compared to the conventional coatings, such as TiAlN, AlCrN, and TiN. The surface morphology of the coating was characterized using the atomic force microscope (AFM). The surface roughness was found to be lesser in the TiAlN/AlCrN coating. The TiAlN/AlCrN coating has proved to have better corrosion resistance, compared to the uncoated carbide substrate.     

Ferroelectric studies and impedance analysis of PLZT (10/52/48) electroceramics

Perovskite Pb_0.90La_0.10(Zr_0.52Ti_0.48)O₃ ceramic material was prepared through sol–gel process. Structural, phase formation and thermal properties were confirmed by X-ray diffraction, thermogravimetry and differential thermal analysis; size and microstructural study was carried out using particle size analyser and scanning electron microscope. The electrical properties of the ceramics were investigated as a function of both temperature (from room temperature to 500 °C) and frequency (from 100 Hz to 1 MHz) using complex impedance spectroscopy (CIS). The impedance spectrum results indicate the decrease in dielectric constant with increase in frequency while the dielectric loss increases with frequency. The activation energy of the sample was calculated from the slope of the Arrhenius plot as 0.129 eV from the Arrhenius’s plot of dc conductivity versus inverse of absolute temperature. The dc conductivity was obtained from CIS measurements and the activation energy. The remnant polarization (P_r) and coercive electric fields (E_c) are found out as 6.52 μC/cm² and 2.55 kV/cm from the ferroelectric loop measured at room temperature.