Langmuir monolayer is a unique tool to characterize the interface which describes the properties of insoluble monolayer on the sub-phase. Langmuir monolayers have demonstrated the characteristics of many macromolecules as well as amphiphilic molecules at the air-water interface. We evaluated physiochemical characteristics of monoolein lipid Langmuir monolayers on different sub-phases. Interfacial behaviour of monoolein lipid was investigated using Wilhelmy plate pressure sensor technique to generate Langmuir isotherms to explore the effects of interactions with different sub-phases. Various salts alter the surface pressure of the Langmuir monolayer isotherms without the alteration of monolayer phase transitions. The finding of the present work can be effectively used for development of suitable biomedical formulations to offer sufficient strength of coating film with controlled topology and thickness using Langmuir-Blodgett film deposition technique. Addition of the suitable biocompatible ions in to the sub-phase is very crucial for their favourable interfacial interaction with the lipid molecules.
In recent years, synthesis and characterization of Ag-based materials has become an active area of research due to its application in medical area for having antimicrobial properties useful for prosthetic replacement. Pure HydroxyAPatite (HAP) and 1.5wt% Ag-doped HydroxyAPatite (AgHAP) were prepared by sol-gel process and characterized. Ca(NO3)2.4H2O was used as source of Ca precursor, P2O5 was used as a source of P precursor, and AgNO3 has been used as a source of Ag precursor. Pellets of HAP and AgHAP were made after precipitates were consolidated, dried in oven, grounded and sintered in a muffle furnace. Functional groups were determined using FTIR, and compound formations were investigated using XRD. Microstructural analysis was done using SEM and AFM. Wettability was studied using OCA in distilled water, and corrosion resistance and impedance analyses were carried out using ECA in Ringer solution. It was observed from AFM and XRD that grain size decreased from 7.05 ?m to 1.25 ?m. Improvement in corrosion resistance was observed in AgHAP. Wettability studies showed that AgHAP is more hydrophilic in comparison with pure HAP. A correlation between microstructures and properties of hydroxyapetites are discussed in this paper.
DNA ionogels prepared by adding 1-ethyl-3-methylimidazolium chloride on low energy gamma irradiated DNA solution samples reveal non-trivial self-assembly. Variations in secondary structure and low-frequency gel rigidity modulus G0 captured this unique hitherto unexplored features of these gels. Interestingly, at higher radiation dose (0 to 100 Gy) samples could partially lose their initial rigidity. Dynamic light scattering revels dose dependent relaxation dynamics corresponding to ergodicity breaking time. In particular, viscosity and rheology showed that the time of gelation tgel, temperature of gelation Tgel and strength of gelation G0 are gamma ray dose dependent. DNA Ionogel melting with temperature shows self-assembled characteristics of this biomaterial. Gelation kinetics of ionizing radiation treated DNA strands have been studied in literature.
Bent Core Mesogens are remarkably interesting achiral Liquid Crystals. These grab attention for their utility. The compound, taken for investigation, is a Schiff base addition product, composed of 2-(4β-aminophenyl)-5-(4?β-butyloxyphenyl)-1,3,4- thiadiazole and 4-n-hexadecyloxy salicylaldehyde. The property of this imine derivative is in accordance with liquid crystal and is a Bent Core Mesogen (BCM). The thin layers were prepared with the help of Langmuir-Blodgett apparatus. The morphology and photo-physical characteristics of thin films were examined in comparison to similar BCM derivative of 1,3,4-Oxadiazole. The expectation was the formation of monolayer of molecules on the substrate. Practically there were layer of clusters on the substrate. Both molecules form nano clusters. The typically different aggregates by the thiadiazole moiety in comparison to oxadiazole moiety are revealed. Cluster formation is also supported by the Atomic Force Microscopic (AFM) images.
Aluminium (Al) and its alloys are attractive for a variety of applications due to its advantages like light weight, ease of processing and high thermal/electrical conductivities. However, it suffers from shortcomings in terms of strength, wear resistance and corrosion resistance. Anodising is commonly used to improve the surface modification of Al alloys. This paper presents a review of anodising and related processes and updates the current status in this area. The chemical structure and the size of the oxide film are influenced by factors like temperature, type of electrolyte and current density/ applied voltage. Depending on the process parameters, the oxide film formed in this process can be thin, non-porous, thick, and porous. The hardness of the coating in anodizing is influenced by the parameters like coating thickness, voltage, current density, and temperature. Further, it is required to regulate the metal/oxide or film/solution interface at which the barrier film grows. In Plasma Electrolytic Oxidation (PEO), the modified version of anodising, and the selection of operating conditions influence coating morphology, structure and composition which in turn affect the wear resistance and corrosion properties. The properties of the coating in case of PEO process are influenced by the nature/structure of the base material, type/composition of electrolyte, temperature of the electrolyte during the process, oxidation time, and electrical parameter (current density and voltage). Understanding of the effect of these parameters on coating properties opens new vista for better application prospects.
Herein, we have investigated the mixed micellar behavior of carboxylate anionic dimeric surfactants (CAD12 and CAD16) with commercial surfactants; anionic type i.e., sodium dodecyl sulfate, cationic i.e., cetyltrimethylammonium bromide and nonionic i.e., polyethylene glycol p-(1,1,3,3-tetramethylbutyl)-phenyl ether. The CMC values of mixed surfactants obtained from conductivity data decrease with a mole fraction of dimeric surfactants. The micellar characteristics (ideal CMC) and mutual interaction parameters (β) have been computed with the aid of theoretical models proposed by Clint, and Rubingh. In addition to this, thermodynamic parameters of micellization like 0 ΔG0mic, ΔH0mic, and ΔS0mic were evaluated and discussed.
Magnesium based metal - organic Framework (MOF) was synthesized by using Benzene Di-Carboxylic acid (BDC), MgSO4.7H2O and a flower extract of Clitoria ternatea. The prepared MOF was characterized by FTIR spectrum, SEM-EDS, XRD, DLS and PL Spectrum. The crystalline nature of the synthesized MOF was revealed in XRD patterns. The nano particle nature of the MOF was confirmed from the SEM pictures. FT-IR spectra showed a peak at 520cm-1 designated characteristic absorption bands of synthesized Mg-MOF nano particles. The zeta potential value showed that the surface charge of the synthesized MOF is neutral and hence disperse in solution without having any tendency for agglomeration and coagulation on standing. The photoluminescence spectra indicated luminescent nature and hence this nano crystalline MOF finds very good application as luminescent material and as sensing material.
TX-100 molecular hydrogels exhibited re-entrant melt-gel-sol phase transition driven solely by dilution, which sequentially altered the self-assembly of the micellar formations and their population was investigated through the monitoring of the physical parameters namely, solution viscosity, particle size histogram, ergodicity, and gel rigidity modulus. This phenomenon was noticed at 20°C in the TX-100 concentration region of 0.2 to 1.2 M much above the critical micellar concentration of 0.22 mM. The particle size histograms revealed the presence of spherical micelles (size »3 nm) in the solution ([TX-100] < 0.5 M) which formed entangled wormlike cylindrical micelles (apparent hydrodynamic radius » 50 nm) when (0.5 M< [TX-100] < 0.9 M) giving rise to a gel-like structure. Further increase in the TX-100 concentration increased the propensity of these wormlike cylindrical micelles that got randomly distributed creating a dense melt phase. Interestingly, we observed transition solely driven by dilution which defined complete re-entrant behavior at room temperature. These molecular gels could be created by dilution of the melt or concentration of the sol unlike in the polymer gels. Remarkably, this hitherto little known unique phenomenon was exhibited by a simple system of non-ionic surfactant solution. Thus, we have a hydration reversible gel at our disposal which has a special place in soft matter arena.
Poly-Vinyl Alcohol (PVA) capped Cadmium Selenide (CdSe) and Cadmium Selenide/Zinc Oxide (CdSe/ZnO) core/shell semiconductor/semiconductor nanoparticles have been synthesized using wet chemical precipitation method. The pH of each solution was varied ranging from 9.5 to 11.5. Particle size of the CdSe nanoparticles was estimated using Brus Equation. The results of UV-Visible spectroscopy of core CdSe samples show blue shifting of absorption edges in a range of 342-377 nm compared to that of the bulk CdSe 712 nm and red shifting of the absorption edges of the core /shell samples in a range (346-357) nm in comparison to the core sample, over which the shell is deposited. For CdSe core nanoparticles, the band gap values were found to be in the range of 3.70–3.90 eV, which is larger than the bulk CdSe of 1.74 eV. Also the band gap values for the core/shell nanoparticles were in the range of 3.75-3.80 eV. The positions of excitonic emission peak obtained from photoluminescence spectra for the core is around 323 nm and for the core/shell samples is around 324nm. The average crystallite size of the core/shell CdSe/ZnO sample was obtained from XRD spectra in the range of 62-69 nm and for the core CdSe sample it was of 11-31 nm. The core and the core/shell samples were more or less spherical as obtained from the SEM analysis. Some of the core nanoparticles were 3-8 nm in size whereas the core/shell nanoparticles were 20-50 nm in size as obtained from HRTEM analysis.
Boronic acid based amphiphiles are new generation green surfactant materials because they degrade to produce environmentally friendly boric acid. This study describes the interfacial property as well as aggregation behaviour of two pyridine based boronic acid amphiphiles containing amide linkage in hydrocarbon chain named sodium salt of 2-amidodecyl pyridine-5-boronic acid (SADPB) and sodium salt of 2-amidododecyl pyridine-5-boronic acid (SADDPB). Tensiometry study was executed for investigation of interfacial properties of pyiridine based boronic acid derivatives. Polarity and viscosity of the microenvironment of aggregates was investigated using fluorescence technique. DLS measurement suggested size of the assemblies of SADDPB is larger than SADPB in solutions. XRD technique was employed to examine arrangement of the hydrophobic tails in the bilayer aggregates. TEM technique was utilised to scrutinize aggregate morphology in solutions. The findings showed prospect of these amphiphiles to be applicable as drug carrier in pharmaceutical industries.
Dielectric relaxation studies of acetate buffer solutions of Sodium Dodecyl Sulphate (SDS- anionic), Cetyl Trimethyl Ammonium Bromide (CTAB- cationic), Tween 80 (TW-80-non-ionic), Betaine Anhydrous (BA- zwitterionic) surfactants have been examined in the frequency region between 1GHz and 25GHz for various concentrations of surfactants at the temperatures of 283, 288, 293 and 298K using time domain dielectric spectroscopy. The obtained corrected loss spectra of all the amphiphiles except betaine anhydrous in acetate buffer solution depicted peaks near 1-2GHz and 15GHz, respectively. For betaine anhydrous, expected peak was not observed in the 1-2GHz frequency region. The peak ascertained near 15GHz, and another peak about 1-2GHz was accorded to free water relaxation and bound water reorientation of the surfactant micelles, and has acquired the reliance of temperature with concentration in detail. Single Debye and Cole-Cole function was employed to compute the relaxation times of free water and bound water, respectively. The Arrhenius plot was used to calculate the enthalpy and entropy for the micelle forming surfactants.
Three novel ester-amidoamine linked cationic surfactants bearing a double tail were synthesized. Their chemical structures were interpreted with FTIR, 1H and 13C NMR spectroscopy. These surfactants consist of hydrophobes that may be obtained from sustainable resources. The objective was to synthesize a double tailed amidoamine having two functional groups in the structure and to investigate the effect of these groups on the interfacial as well as physical properties of the surfactants. The interfacial properties of the surfactants were determined using tensiometry, conductometry measurements and dye solubilization techniques. The synthesized surfactants have been found to exhibit quite low CMC in comparison with conventional surfactants of similar structure. The effect of sodium chloride on their surface properties was also studied. They were found to possess good and stable foaming ability and wettability. All the synthesized surfactants delivered appreciable antimicrobial activity against three tested microorganisms, Staphylococcus aureus and Escherichia coli.
This article provides a summary of some of the most current research on the delivery of drugs to the lungs, as well as a discussion of some of the limitations of these studies. Nebulizers have been in use for more than a century to deliver aerosolized drugs to patients suffering from respiratory disorders. Aerosol devices such as these are the best option for people who have trouble managing their inhalation. Because of the actuation required, pressurised Metered-Dose Inhalers (pMDI) and Dry Powder Inhalers (DPI) are unable to generate the necessary inspiratory flow required for successful aerosol drug delivery. Currently, we are looking into how the working mechanism of different nebulizers interacts with the physicochemical features of the formulations. We are looking into a wide range of devices, such as jet, ultrasonic, and vibrating-mesh nebulizers. In this study, the researchers hope to describe the many different types of nebulizers that are currently available on the market, evaluate their performance in aerosol drug delivery, and recommend treatment approaches for patients with chronic obstructive pulmonary disease.
In the present work, the effect of Graphene nanoPlatelets (GnP) content on the flexural, surface roughness, and water absorption behavior of a GnP reinforced epoxy composite was investigated. Different wt.% of GnP (0.25, 0.5, 0.75, and 1 wt.%) was added into the epoxy matrix through the sonication method followed by the ball milling. The results indicate a significant enhancement in the flexural properties of the epoxy nanocomposite with the addition of GnP in the epoxy matrix. The optimum enhancement in the properties was obtained at 0.25 wt.% GnP incorporated epoxy composites. The increase in flexural strength and flexural modulus results were noticed as 42.7% and 49.2% when compared with neat epoxy. The surface roughness value for the loading of 0.25 wt.% of GnP into the epoxy showed a drop of 48.7% when compared with that of the neat epoxy sample. The loading of 0.25 wt.% of GnP into the epoxy also reduces the water absorption from 0.125% for the neat epoxy sample to 0.067% for the composite sample. The Scanning Electron Microscope (SEM) images of the fractured surface (flexural samples) of the GnP embedded epoxy composites show the river like pattern, which is the result of the better dispersion of the GnP in the epoxy matrix and thus shows improvement in flexural behaviour of such composite materials.
The graphite rods of used batteries have been utilized as source for Graphene Oxide (GO). The Acid Modified Graphene Oxide (AMGO) is loaded with Schiff base obtained from salicylaldehyde and 3-amino phenol. Glassy Carbon Electrode (GCE) surface when modified with the Schiff base loaded AMGO acts as electrochemical sensor for Dopamine (DA) in presence of Uric Acid (UA) and Ascorbic Acid (AA). Cyclic Voltammetry (CV), Square Wave Voltammetry (SWV) and Differential Pulse Voltammetry (DPV) shows well separated peaks for DA from UA and AA. The DA peak intensity increases in the three techniques with DA concentration. The linear range for the detection of dopamine is observed from 9.09 × 10-4 M to 1.70 × 10-3 M in presence of 1.00 × 10-1 M Ascorbic Acid and 1.00 × 10-2 M uric acid. The detection limit is estimated to be 9.38 × 10-10 M.
Water absorption behavior of annealed Nanodiamond (ND) particle filled epoxy composite, has been studied. Removal of impurity present in the pristine ND and its surface modifications, were carried out by heat treatment. Different weight percent of ND (0.1, 0.3 and .05 wt. %) were incorporated in a commercial grade epoxy resin (L-12) in a controlled manner. A good and homogeneous distribution of ND in the composite, was observed. This resulted in reduction of mobility of the epoxy chain due to formation of highly immobile mono-layers around ND as well as formation of hydrogen bond between the ND and the epoxy. The water absorption and the contact angle properties of the resulting composites are measured. The results indicate that the water absorption as well as contact angle of the composite decrease with the increase of incorporated ND. It is observed that incorporation of ND into epoxy matrix, enhances the water resistance property of the composite.
The current study offers a comprehensive understanding on the adsorption study employing the cost-effective biomass as an effective substitute against high-cost treatment options. The present work put forth the adsorption of hazardous cationic dye: Crystal Violet (CV) from aqueous solution using Rice Husk (RH) and surfactant Modified Rice Husk (MRH). Effect of the adsorbents: RH and MRH onto CV removal is determined considering various experimental parameters viz., mass, volume, dye concentration, contact-time, equilibrium temperature, and pH where maximum CV adsorption was achieved at pH = 8. Results obtained are attributed to the favorable ion-pair formation between CV and anionic surfactant: Sodium Dodecyl Sulfate (SDS) which is validated further using quantum chemical calculations. To counterpart the sorption process onto the adsorbent, the adsorption study was validated employing several kinetic models and isotherms. The thermodynamic conduct concluded the CV adsorption to be spontaneous (negative ?G) and endothermic (positive ?H) in characteristic at ambient temperature i.e., adsorption increases with temperature.
Tungsten Carbide-20 weight % Cobalt (WC-20 wt% Co) coatings were extensively used material to achieve a combination of extreme hardness and excellent strength. Hence, an effort has been made to improve the toughening properties of WC-Co coatings through reinforcement of Carbon Nano-Tubes (CNTs) using High-Velocity Oxy-Fuel (HVOF) spraying process. In this work, 2 wt%, 4 wt%, and 6 wt% of CNTs were blended by the ball milling process with WC-Co powders. These composed powders were deposited by HVOF process on to the plain mild steel substrates. The scratch test analysis on as-sprayed coatings showed that due to the addition of CNTs on WC-Co coatings, the resistance to penetrate the coating surface increased. Also, by varying the percentage of CNTs in the coating system, the pores were reduced. This phenomenon is attributed to the toughening mechanism by forming a CNT bridge which avoids the formation of internal cracks.
In this work, we studied the elimination of phenol compounds from phenolic solutions and Oil Mill Waste Water (OMWW) by adsorption method. The adsorbents used are natural phosphate rock coming from Khouribga phosphate mine (Morocco) and an Apatite synthesized from this phosphate by a dissolution–precipitation reactions. Results obtained showed that the structure of natural phosphate and synthesized apatite are respectively Ca9.55(PO4)4.96F1.96 (CO3)1.283 and (Ca10(OH)2(PO4)6). Synthesized apatite has a higher specific surface than natural phosphate (193.62m2/g). The adsorption study showed that the synthesized apatite can be used as an adsorbent to remove phenol from water with very fast reaction kinetics (about 10 min) and an adsorption capacity equal to 15mg/g. The optimal adsorption capacity was found in low values of temperature and in neutral pH. Adsorption kinetics of phenol solution on the two adsorbents can be described by an equation corresponding to a pseudo second order. Freundlich model fitted well with the adsorption isotherms more than the Langmuir model. Characterization of olive mill wastewater shows that, phenol index equal to 0.39 g/l and chemical oxygen demand COD equal to 158 g/l. The treatment of OMWW by adsorption method on the two adsorbents shows that the use of natural phosphate as adsorbent reduced phenol index by 23% and (COD) by 35% while using synthesized apatite reduced phenol index by 30% and COD by 38%.
Pasteurized cow milk (whole milk) was used in the present study and also fat was removed from the whole milk to obtain skimmed milk. Whey is the liquid remaining after milk has been curded and strained during the manufacture of cheese. The sample was filtered using a Whatman filter paper to separate the precipitate. The filtrate thus obtained is called whey (devoid of casein and fat). The micrographs of whole milk, skimmed milk and whey were obtained using an inverted phase contrast microscopy. The hydrodynamic size and zeta potential of the samples were obtained using Dynamic light scattering technique. Atomic force microscopy was also performed to understand the surface morphology of whole milk, skimmed milk and whey on mica substrate.
