Synthesis and Characterization of AgCl Nanoparticles Under Various Solvents by Ultrasound Method

Nano-structures of AgCl have been prepared by reaction between AgNO₃ and KCl under ultrasound irradiation. Particle sizes and morphology of nanoparticle are depending on temperature and reaction time. The effects of these parameters in growth and morphology of the nano-structures have been studied. The solvents have noticeable influences on the morphology of the silver chloride particles. With an increase in the temperature and reaction time, growth toke place on more nuclei. As a result, an increase in temperature and reaction time led to increase of particle size. The physicochemical properties of the nanoparticles were determined by X-ray diffraction and scanning electron microscopy.     

Poly(vinyl alcohol) membranes in wound-dressing application: microstructure,physical properties,and drug release behavior

Poly(vinyl alcohol) (PVA) hydrogel membranes were prepared through three different preparation methods including freeze-thawing (FT), solution casting (SC) followed by thermal annealing, and phase separation (PS). The prepared hydrogels were characterized by Fourier transform-infrared spectroscopy, X-ray diffractometry, and scanning electron microscopy. Nitrofurazone (NFZ) was then loaded in the hydrogels. FT and SC methods led to obtaining dense membranes, while PS method resulted in an asymmetric one. The effects of hydrogel preparation method on water absorption, gel fraction, water vapor and oxygen permeabilities, bacterial barrier, tensile properties, and drug release profiles were investigated. The water vapor permeability of the hydrogel prepared through PS method was about 1.5 times higher than those obtained through FT and SC methods. Gel formation in PS method is probably responsible for the highest degree of crystallinity, and consequently the maximum gel fraction for the corresponded membrane. The elongation-at-break for this membrane in wet state was 41% higher than that made by FT method and 18% greater than that of SC method. Membranes prepared by all three methods showed excellent barrier property against bacterial penetration during 1 week. The results showed that PS membrane could control the release of NFZ more effectively as compared with the other two samples.     

Delivery of cisplatin by folic acid-targeted liposomal nanoparticles into liver cancer cell line

This study aimed to prepare cisplatin-loaded PEGylated liposomal nanoparticles targeted with folic acid and evaluate their efficacy on liver cancer cell line PLC/PRF/5 (Alexander hepatoma cell line). Nanoparticles were prepared by reverse phase evaporation technique and characterized by dynamic light scattering, scanning electron microscopy, transmission electron microscopy, inductively coupled plasma optical emission spectrometry, Fourier transform infrared spectroscopy, and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide techniques. Nanoscale particles with appropriate drug encapsulation efficiency (13%) were prepared. Cytotoxicity results indicated that the superior potency of targeted cisplatin-loaded nanoparticles compared to the nontargeted counterpart with 23% more cytotoxicity. Findings of this study confirmed the potency of targeted PEGylated liposomal nanoparticles.     

Characterization of zirconia specimens fabricated by ceramic on-demand extrusion

The Ceramic On-Demand Extrusion (CODE) process is a novel additive manufacturing method for fabricating dense (~99% of theoretical density) ceramic components from aqueous, high solids loading pastes (>50?vol%). In this study, 3?mol% Y₂O₃ stabilized zirconia (3YSZ) specimens were fabricated using the CODE process. The specimens were then dried in a humidity-controlled environmental chamber and afterwards sintered under atmospheric conditions. Mechanical properties of the sintered specimens were examined using ASTM standard test techniques, including density, Young’s modulus, flexural strength, Weibull modulus, fracture toughness, and Vickers hardness. The microstructure was analyzed and grain size measured using scanning electron microscopy. The results were compared with those from Direct Inkjet Printing, Selective Laser Sintering, Lithography-based Ceramic Manufacturing (LCM), and other extrusion-based processes, and indicated that zirconia specimens produced by CODE exhibit superior mechanical properties among the additive manufacturing processes. Several sample components were produced to demonstrate CODE’s capability for fabricating geometrically complex ceramic components. The surface roughness of these components was also examined.     

Impact of non‐solvent on regeneration of cellulose dissolved in 1‐(carboxymethyl)pyridinium chloride ionic liquid

Cellulose dissolved in ionic liquid (1‐(carboxymethyl)pyridinium chloride)/water (60/40 w/w) mixture is regenerated in various non‐solvents, namely water, ethanol, methanol and acetone, to gain more insight into the contribution of non‐solvent medium to the morphology of regenerated cellulose. To this end, the initial and regenerated celluloses were characterized with respect to crystallinity, thermal stability, chemical structure and surface morphology using wide‐angle X‐ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy and scanning electron microscopy. According to the results, regardless of non‐solvent type, all regenerated samples have the same chemical structure and lower crystallinity in comparison to the initial cellulose, making them a promising candidate for efficient biofuel production based on enzymatic hydrolysis of cellulose. The reduction in crystallinity of regenerated samples is explained based on the potential of the non‐solvent to break the hydrogen bonds between cellulose chains and ionic liquid molecules as well as the affinity of water and non‐solvent which can be evaluated based on Hansen solubility parameter. The latter also determines the phase‐separation mechanism during the regeneration process, which in turn affects surface morphology of the regenerated cellulose. The pivotal effect of regenerated cellulose crystallinity on its thermal stability is also demonstrated. Regenerated cellulose with lower crystallinity is more susceptible to molecular rearrangement during heating and hence exhibits enhanced thermal stability. © 2019 Society of Chemical Industry     

Synthesis of Vanadium Pentoxide Nanoparticles as Catalysts for the Ozonation of Palm Oil

Vanadium pentoxide nanoparticles were synthesized using a solvo-thermal method and were characterized via X-ray powder diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). The ozonation of palm oil was performed by using vanadium pentoxide nanoparticles as catalysts to synthesize ethyl malonate. This procedure presented several advantages, such as simple operation for a precise ozonation, excellent yield, short reaction times and reusability because of the recyclability of palm oil. Ethyl malonate was synthesized via the one-step ozonolysis of palm oil and was spectroscopically characterized using gas chromatography-mass spectroscopy (GC-MS).     

Design and implementation of tuned viscoelastic dampers for vibration control in milling

Passive means of vibration attenuation have been employed successfully and efficiently in machining systems such as turning and milling. Traditional approach to controlling vibration in a milling system is to develop control mechanisms for cutting tools or machine spindles. However, due to the nature of milling operations where the cutting tools rotate at high speed, the passive vibration control methods find very limited application with the traditional approach. In order to utilise the potential of the passive vibration control methodology in milling applications, the milling operation should be viewed as a system comprising an elastic structure and operation parameters. Dynamics of this closed-loop system should improve with improvement in dynamics of any of the system components, especially within the elastic structure that comprises the cutting tool, the machine tool, the workholding system and the workpiece. Although the level of improvement will vary depending on which component of the elastic chain is targeted for this purpose. This paper presents the development and testing of tuned viscoelastic dampers (TVDs) for vibration control through their application on a workpiece in milling operations. This work targets workpiece held on a palletised workholding system for the control of unwanted vibration and thus deviates from the traditional approach where cutting tool and/or machine spindles are targeted for vibration control strategies. Palletised workholding systems, due to their compact design, offer an opportunity to design passive damping mechanisms that are easier to implement in the case of a milling system. The TVD developed through this research is based on a commercially available viscoelastic damping polymer. Advantage of such materials is their high damping performance over a wide range of excitation frequencies. The TVD design process has used a unique combination of analytical modelling with experimental FRF data. Modal impact testing showed that the application of the TVD reduced the amplitude of vibration acceleration by 20 dB for the target mode. Since the target mode corresponded to torsional vibration, the TVD was effective in two planar coordinates, i.e. X and Y. In addition, the TVD also significantly reduced the amplitude of a vibration mode far from the mode it was designed for. The system has been tested experimentally to demonstrate significant reduction in vibration amplitudes during a milling process. The milling tests with different combinations of cutting parameters show that multi-TVD approach is always valid regardless of the parameters being used. The only requirement for TVDs to function effectively is that the natural frequency of the system, for which the TVDs are designed, is excited during the milling process.     

NSOM the fourth dimension: Integrating nanometric spatial and femtosecond time resolution

Photonic devices are becoming the cornerstone of next generation systems for computing and information processing. This paper reports on the first steps in the development of methods to understand these devices with nanometric (10^?7 cm) spatial and femtosecond (10^?15 s) time resolution. The basis of this achievement is the dramatic developments that have occurred in the past few years in a new area of optics called near-field optics. Near-field optics is a form of lensless optics with a resolution that is subwavelength and which is independent of the wavelength of the light being employed. We report in this paper the transmission of pulses with tens of femtosecond duration through subwavelength, near-field optical elements. We also report on a femtosecond near-field optical light source with cross-correlating capabilities and on the growth of GaAs in the tip of micropipettes for use as an ultra-fast electro-optical switch which can cross-correlate optical, electrical, and electro-optical effects. These developments are especially relevant in the investigation of photonic devices since such devices can alter their characteristics as a function of size in the mesoscopic regime from just below lens-based optical resolutions to dimensions that approach atomic scales of ～1 nm (10^?7 cm). In view of the fact that these devices and the processes that govern them also exhibit ultrafast speeds, the combination of state of the art femtosecond laser spectroscopy with the unique features of near-field optics is a critical step in advancing our next generation understandings of such materials and structures so that their full potential in information processing can be achieved.