Polymer reinforced aerogels and composites A. Polyimide crosslinked aerogels B. Silica-polymethylmethacrylate composites

Crosslinking of aerogels is a promising approach to combine the advantages of inorganic and polymeric materials. In the present study, two types of polyimide-silica hybrid aerogels, APTES-BTDA-MDA (mol ratio: 2:2:1) and APTES-BTDA-MDA (mol ratio: 2:3:2), were synthesized using a sol-gel process followed by heating in order to imidize the polyamic acid that is formed quickly and is covalently bonded to silica. The hybrid aerogels were made using 3-aminopropyltriethoxysilane (APTES) endcapped polyamic acids and tetramethoxysilane (TMOS) as precursors. Polyimide crosslinked aerogels were characterized by TGA, SEM, FT-IR, BET, solid state NMR and gas pycnometry. These hybrid aerogels exhibit high thermal stability and have potential applications in thermal insulation. Silica-polymethylmethacrylate (PMMA) composites have been synthesized by in situ polymerization of methylmethacrylate (MMA) in the microstructure of silica gels by using an alkoxy derivative of 2,2 \u27-azo-bis (isobutyronitrile) already bonded to silica. Composites with three different silica contents were synthesized and their thermal and mechanical properties were compared to neat PMMA and a composite prepared via mechanical dispersion of sol-gel silica nanoparticles in PMMA. Silica-PMMA composites were characterized by TGA, FT-IR, compression testing and solid state NMR. The PMMA composites exhibited considerable rise in thermal decomposition temperatures as compared to neat PMMA --Abstract, page iv

Influence of Material Properties of Reinforced Concrete Element on Acoustic Emission due to Corrosion

The material properties of reinforce concrete (RC) influence the corrosion process of steel rebar and subsequent cracking of concrete. This paper investigates the influence of material properties on acoustic emission (AE) due to corrosion of rebar in concrete. RC cylinders with various cover thickness to rebar diameter ratios (C/D), cement types and steel types were studied to identify their influence on cumulative signal strength (CSS) of AE technique. The result of analysis of variance (ANOVA) indicated significant effect of steel type on CSS values due to corrosion followed by cement type, whereas C/D has no significant effect

A novel FRET probe for determination of fluorescein sodium in aqueous solution: Analytical application for ophthalmic sample

1187-1193Fluorescent pyrene nanoparticles (PyNPs) have been prepared by a reprecipitation method in the presence of sodium dodecyl sulphate (SDS) as a stabilizer. The formation of PyNPs has been confirmed by dynamic light scattering (DLS), UV-visible absorption spectroscopy, fluorescence spectroscopy and excited state lifetime measurements. DLS results of PyNPs shows a narrow size distribution with average particle size of 77.4 nm and negative zeta potential. The systematic FRET experiments performed by measuring fluorescence quenching of PyNPs with successive addition of FL-Na analyte exploited the use of PyNPs as nanoprobe for detection of FL-Na in aqueous solution. The fluorescence of PyNPs has been quenched by Fl-Na and quenching has been in accordance with the Stern-Volmer relation. The distance r between the donor (PyNPs) and acceptor (FL-Na) molecules has been obtained according to the fluorescence resonance energy transfer. The fluorescence quenching results have been used further to develop an analytical method for estimation of fluorescein sodium from ophthalmic samples available commercially in the market

Grapes Quality Prediction Using Iot & Machine Learning Based on Pre Harvesting

Minimizing pesticide use, preserving water, as well as enhancing soil health are just a few of the sustainable farming techniques that must be carefully considered while growing grapes of a high calibre. These practices can help preserve the environment and ensure the longevity of the vineyard. However, it is difficult for the farmers to find the suitability of the soil and its environment to cultivate grapes with high quality. Thus this research aims to evaluate the fitness of the soil for the fitness of growing quality grapes with the aid of machine learning algorithm. The research was done on Nasik region which is called as the “Grape Capital of India” situated in Maharashtra. Total of 154 villages were considered for the examination and soil specimens were collected and sent to the government testing lab in Maharashtra. The soil characteristics by considering both micro and macro nutrients, and the water characteristics were obtained from the lab. Also the climatic features, quality of the petiole and fruit characteristics were included for creating the dataset. These data was given to six different machine learning algorithm to classify the soil by defining whether the soil is fit for grapes or not. Moreover, this research proposed to analyze the correlation between the nutrients by which the relationship and dependency between the different nutrients and features were considered for defining the grapes quality. Also both the micro and macro nutrients were given equal importance in defining the soil quality suitable for obtaining high quality grapes. Based on the results obtained, Pimpalas Ramche contains more nutrients for the grape to grow more successfully based on samples gathered from different vine yards and the decision tree classifier scores better than any other classifiers among the machine learning algorithms employed in terms of accuracy

A novel FRET probe for determination of fluorescein sodium in aqueous solution: Analytical application for ophthalmic sample

Fluorescent pyrene nanoparticles (PyNPs) were prepared by a reprecipitation method in the presence of sodium dodecyl sulphate (SDS) as a stabilizer. The formation of PyNPs was confirmed by dynamic light scattering (DLS), UV-visible absorption spectroscopy, fluorescence spectroscopy and excited state lifetime measurements. DLS results of PyNPs shows a narrow size distribution with average particle size of 77.4 nm and negative zeta potential. The systematic FRET experiments performed by measuring fluorescence quenching of PyNPs with successive addition of FL-Na analyte exploited the use of PyNPs as nanoprobe for detection of FL-Na in aqueous solution. The fluorescence of PyNPs was quenched by Fl-Na and quenching is in accordance with the Stern-Volmer relation. The distance r between the donor (PyNPs) and acceptor (FL-Na) molecules was obtained according to the fluorescence resonance energy transfer. The fluorescence quenching results were used further to develop an analytical method for estimation of fluorescein sodium from ophthalmic samples available commercially in the market

Fluorescence resonance energy transfer from pyrene nanoparticles to riboflavin: Spectroscopic insights and analytical application

The aqueous suspension of fluorescent pyrene nanoparticles (PyNPs) were prepared by a reprecipitation method in the presence of sodium dodecyl sulphate (SDS) as a stabilizer. The PyNPs shows bathochromically shifted aggregation induced enhanced emission (AIEE) in the spectral region 400 nm to 600 nm peaking at 466 nm where Riboflavin (RF) absorbs strongly. The systematic FRET experiments performed by measuring fluorescence quenching of PyNPs with successive addition of RF analyte exploited the use of PyNPs as nano probe for detection of RF in aqueous solution with lower limit of detection 10.163 × 10-5 mol.L-1. The fluorescence of PyNPs was quenched by RF and quenching is in accordance with the Stern-Volmer relation. The distance r between the donor (PyNPs) and acceptor (RF) molecules was obtained according to the fluorescence resonance energy transfer. The evaluation of photo kinetic and thermodynamic parameters such as quenching rate constant (kq), enthalpy change (ΔH), Gibbs free energy change (ΔG) and entropy change (ΔS) was calculated by quenching results obtained at different constant temperatures. The proposed FRET method based on fluorescence quenching of PyNPs was used further to develop an analytical relation for estimation of RF from pharmaceutical samples available commercially in the market

Self-learning mechanical circuits

Computation, mechanics and materials merge in biological systems, which can continually self-optimize through internal adaptivity across length scales, from cytoplasm and biofilms to animal herds. Recent interest in such material-based computation uses the principles of energy minimization, inertia and dissipation to solve optimization problems. Although specific computations can be performed using dynamical systems, current implementations of material computation lack the ability to self-learn. In particular, the inverse problem of designing self-learning mechanical systems which can use physical computations to continuously self-optimize remains poorly understood. Here we introduce the concept of self-learning mechanical circuits, capable of taking mechanical inputs from changing environments and constantly updating their internal state in response, thus representing an entirely mechanical information processing unit. Our circuits are composed of a new mechanical construct: an adaptive directed spring (ADS), which changes its stiffness in a directional manner, enabling neural network-like computations. We provide both a theoretical foundation and experimental realization of these elastic learning units and demonstrate their ability to autonomously uncover patterns hidden in environmental inputs. By implementing computations in an embodied physical manner, the system directly interfaces with its environment, thus broadening the scope of its learning behavior. Our results pave the way towards the construction of energy-harvesting, adaptive materials which can autonomously and continuously sense and self-optimize to gain function in different environments

Application of infrared thermography for temperature measurement in microscale internal and external flows

Infrared (IR) thermography is applied to estimate heat transfer rates in external and internal microscale convective flows. The technique and analysis are developed in the context of external jet impingement flow and internal single-phase liquid flows. A heated-thin-foil thermography technique is applied to perform surface temperature visualization on a submerged 125-[mu]m circular microscale jet impingement. Microscale jets flows are associated with low exit Reynolds number (Re) due to the small characteristic length of the nozzle, but correspondingly high exit velocities, and hence, a high subsonic Mach number. Detailed distributions of heated and adiabatic wall temperature, and local and average Nusselt number (Nu) variations are presented for a single 125-[mu]m diameter air jet impingement for five laminar exit Re in the range of 690 to 1770 at three nozzle-to-surface spacing of 2, 4, and 6 times the nozzle diameter. The corresponding jet exit Mach numbers vary between 0.26 and 0.63. Lateral heat conduction along the impingement surface is significant and warrants inclusion in the calculation of heat transfer coefficient. Results indicate that the adiabatic surface temperature distribution is relatively insensitive to nozzle-to-surface spacing within the parameter range studied. With an increase in Re, the adiabatic surface temperature decreases significantly near the stagnation point. The average Nu is higher compared to the turbulent macroscale Martin's correlation for large Re. A technique for quantitative temperature visualization of single-phase liquid flows in silicon (Si) microchannels using infrared thermography is presented. This technique offers a new way to measure, non-intrusively, local variations in wall temperature, or fluid temperature at the fluid-wall interface, in a microchannel fabricated entirely of silicon. The experimental setup and measurement procedure required to obtain high signal-to-noise ratio is elaborated. A single 13-mm long, 50 [mu]m wide by 135 [mu]m deep Si microchannel was used in this study. Experiments were performed with a constant electrical heat input rate to the heat sink surface for four fluid flow rates between 0.6 g/min and 1.2 g/min, corresponding to a Re range from 200 to 300. The estimated experimental fully developed Nu compares reasonably well with the solution provided in literature for laminar flows. Results indicate that axial non-uniformity can be significant for the large Peclet number flows

Comparative study of the efficacy of herbal antioxdants oxitard and aloe vera in the treatment of oral submucous fibrosis

Objectives: Oral submucous fibrosis (OSMF) is a potentially malignant disorder predominantly seen in the Indian subcontinent due to areca nut, tobacco and their products. The aim of the present study was to compare the efficacy of oxitard and aloe vera in the management of OSMF. Material and Methods: 120 subjects with OSMF were included in the study. The patients were clinico-pathologi - cally diagnosed and divided equally in 2 groups, Group A (oxitard group) and Group B (aloe vera group). Group A was administered 2 oxitard capsules twice daily and Group B was given 5 mg aloe vera gel to be applied topically thrice daily for 3 months. Different clinical parameters were evaluated at regular intervals. Data was analyzed using the Student's paired t test and Chi-square test. P-value <0.001 was considered to be statistically significant. Results: Clinical improvements in mouth opening and tongue protrusion was significant in the oxitard group (p=0.0005). Subjective symptoms of pain associated with the lesion (p=0.0003), difficulty in swallowing (p=0.0000) and speech (p=0.0001) also significantly improved in the Group A. The improvement in burning sensation was not statistically significant between the 2 groups (p=0.002). There was a mild to moderate decrease in the size of the lesion. Conclusions: Though there is no definitive treatment for the condition however, overall assessment of symptoms like mouth opening, tongue protrusion, difficulty in swallowing and speech and pain associated with the lesion showed that oxitard capsules can bring about significant clinical improvements than aloe vera gel in the treatment of OSMF

OVERVIEW ON METHODS OF SYNTHESIS OF NANOPARTICLES

In recent years, interest in the development of novel drug delivery systems using nanoparticles has gained more attention. The nanoparticles offer several advantages over other conventional drug delivery systems. Nanoparticles have gained importance in technological advancements due to their modifiable physical, chemical and biological properties with improved performance over their bulk foils. Nanoparticles can simply move in the body due to their small size and reach very complex organs through diverse routes.&nbsp;The high stability, controlled drug release makes nanoparticles the most suitable drug delivery system. Along with all these advantages, they offer variety in routes of administration. Both hydrophilic, as well as hydrophobic drugs, can be delivered in the form of nanoparticles. Nanoparticles have been used as a physical approach to modify and advance the pharmacokinetics and pharmacodynamics possessions of various types of drug molecules. Thesol-gel technique&nbsp;is a stress-free and very inexpensive process to formulate metal oxides and permits control over the doping process or adding of transition metals, as related to other research techniques. The study of different methods of synthesis of nanoparticles is essential to obtain desired nanoparticles with specific sizes and shapes. They are suitable candidates for various marketable and local applications, which include imaging, catalysis medical applications and environmental applications. This review mainly focuses on approaches used for the production of nanoparticles and different methods of synthesis of nanoparticles such as physical, chemical and biological method