Influence of process variables and formulation composition on sphericity and diameter of Ca-alginate-chitosan liquid core capsule prepared by extrusion dripping method

ABSTRACT

The influence of process variables and formulation composition on the sphericity and diameter of the alginate capsules which contained dual cations (Ca-and-chitosan) are characterized in this study. Capsule sphericty was not influenced by needle diameter but instead, capsule diameter increased proportionally with the needle diameter. The combined effects of the liquid core solution and alginate solution on the sphericity of the capsules are tabulated. Spherical capsules can be produced when the following criteria were fulfilled: stirring speed is in the range of 240–300 rpm; calcium chloride concentration is >5 g/L; viscosity of liquid core solution is >203 mPa.s; as well as viscosity of alginate solution is in between 47 and 386 mPa.s. The capsule diameter was predicted using a modified Tate’s law equation and an error analysis was conducted to evaluate the equation. The predicted diameter was well correlated with the experimental data with an average absolute deviation <3.6%.     

“Time-to-failure” prediction for a polymer-polymer swivelling joint

The growing competition in the market demands a better performance from any product in terms of availability, reliability, maintainability and failure free life. However there a number of engineering as well as environmental factor that influence the performance of a product. Wear is one of the critical factors, which influences the reliability and useful life of mechanical components. Therefore, the ability to predict wear at the development stage enables the designers to come up with a better design, longer useful life and more reliable products. Moreover, the prediction of time-to-failure for a component will lead to better maintenance helping to avoid catastrophic effects of unexpected failures. This paper presents a methodical approach for predicting sliding wear and hence the remaining useful life for a polymer-polymer sliding joint. The major stages of the approach are: tribo-system examination, experimentation, experimental wear coefficient determination and model formation.     

Nanostructured diamond-like carbon on digital versatile disc as a matrix-free target for laser desorption/ionization mass spectrometry

A nanostructured diamond-like carbon (DLC) coated digital versatile disk (DVD) target is presented as a matrix-free sample support for application in laser desorption/ionization mass spectrometry (LDI-MS). A large number of vacancies, defects, relative sp(2) carbon content, and nanogrooves of DLC films support the LDI phenomenon. The observed absorptivity of DLC is in the range of 305-330 nm (nitrogen laser, 337 nm). The universal applicability is demonstrated through different analytes like amino acids, carbohydrates, lipids, peptides, and other metabolites. Carbohydrates and amino acids are analyzed as sodium and potassium adducts. Peptides are detectable in their protonated forms, which avoid the extra need of additives for ionization. A bovine serum albumin (BSA) digest is analyzed to demonstrate the performance for peptide mixtures, coupled with the material-enhanced laser desorption/ionization (MELDI) approach. The detection limit of the described matrix-free target is investigated to be 10 fmol/microL for [Glu(1)]-fibrinopeptide B (m/z 1570.6) and 1 fmol/microL for L-sorbose (Na(+) adduct). The device does not require any chemical functionalization in contrast to other matrix-free systems. The inertness of DLC provides longer lifetimes without any deterioration in the detection sensitivity. Broad applicability allows high performance analysis in metabolomics and peptidomics. Furthermore the DLC coated DVD (1.4 GB) sample support is used as a storage device for measured and processed data together with sampling on a single device.     

Carbon nanotubes based strain sensors

This paper presents the design, fabrication and experimental results of carbon nanotubes (CNTs) based strain sensors. The sensors were fabricated by pressed CNTs tablets and elastic polymer beam. The diameter of multiwalled nanotubes (MWNTs) varied between 10 and 30 nm. The tablets of multiwalled CNTs having nominal thickness of 1.0 mm were pressed at a pressure of 200 and 300 MPa. The inter-electrodes distance (length) and width of the surface-type samples were in the range of 10–12 mm and 5–6 mm respectively. The DC resistance of the sensors having the strain sensitivity in the range of 50–80 in average increased under tension and decreased under compression.     

Acute Oral Toxicity Evaluations of Some Zinc(II) Complexes Derived from 1-(2-Salicylaldiminoethyl)piperazine Schiff Bases in Rats

The current study described the synthesis and the in vivo acute oral toxicity evaluations in Sprague Dawley rats. The compounds were characterized by elemental analyses, LC-MS, FTIR, (1)H NMR, (13)C NMR and UV-visible spectroscopy. In the acute toxicity study, a single administration of the compounds was performed orally to the rats at the single doses of 2000 mg/kg and they were then monitored for possible side effects, mortality or behavioral changes up to 14 days. The serum level of aspartate (AST), alanine aminotransferases (ALT), alkaline phosphate (ALP), triglyceride, high density lipoprotein (HDL), immunoglobulins (GAM) and the C-reactive proteins did not significantly change. The hematological indices white blood cells (WBC), haematocrit (HCT), red blood cells (RBC), mean corpuscular volume (MCV), mean corpuscular haemoglobin concentration (MCHC), and mean corpuscular hemoglobin (MCH) were within the normal range. The renal function indices examined were also within the reference range. Generally, the compounds exhibited low toxic effects as required for further in vivo therapeutic studies.     

Novel magnetically induced membrane vibration (MMV) for fouling control in membrane bioreactors

Conventional submerged membrane bioreactors (MBRs) rely on the coarse bubbles aeration to generate shear at the liquid-membrane interface to limit membrane fouling. Unfortunately, it is a very energy consuming method, still often resulting in a rapid decrease of membrane permeability and consequently in higher expenses. In this paper, the feasibility of a novel magnetically induced membrane vibration (MMV) system was studied in a lab-scale MBR treating synthetic wastewater. The effects on membrane fouling of applied electrical power of different operation strategies, of membrane flux and of the presence of multiple membranes on one vibrating engine on membrane fouling were investigated. The filtration performance was evaluated by determining the filtration resistance profiles and critical flux. The results showed clear advantages of the vibrating system over conventional MBR processes by ensuring higher fluxes at lower fouling rates. Intermittent vibration was found a promising strategy for both efficient fouling control and significant energy saving. The optimised MMV system is presumed to lead to significant energy and cost reduction in up-scaled MBR operations.     

The potential of electrospraying for hydrophobic film coating on foods

There is a continuous need for thinner edible coatings with excellent barrier properties, and this requires new application methods. Electrospraying is known to yield fine droplets of size down to 20 μm, giving the potential of very thin and even coatings. A single electrospraying nozzle was used to characterise droplet formation and investigate the formation of thin films on well-defined surfaces. The experimental droplet size was successfully described as a function of operational parameters and liquid properties using scaling relations. The influence of operating parameters as nozzle height and electrostatic potential were evaluated as well.Thin film deposition was experimentally investigated for sunflower oil electro-sprayed on a highly conductive (aluminium) and insulating target surface (Parafilm). For both aluminium foil and Parafilm the droplet deposition was found to be random. For aluminium foil, being a conductive target, this was expected as repellence between droplets on the surface and new droplets is low, due to charge leakage to the ground. For Parafilm, droplet repellence appeared so large that droplets deposited on larger empty spots or were even pushed away from the surface. To evaluate the film formation performance, Monte Carlo simulations were carried out, and it was found that the method is a useful tool to characterise droplet deposition and film formation characteristics.     

Pinch based approach to estimate CO2 capture and storage retrofit and compensatory renewable power for South Korean electricity sector

A pinch-based approach has been used to calculate optimum values of CO₂ capture and storage (CCS) retrofit and compensatory renewable power for the Korean electricity sector. Three cases are proposed. In the first case, KEPCO 2020 power generation forecast data were used to calculate CO₂ emissions and a 30% emission reduction target applied. For the second case, nuclear-free KEPCO 2020 forecast was used to calculate emissions along with 30% emissions reduction. In the third case, the emissions reduction target increased from 30% to 54.50% for case-2 scenario, in order to achieve 2005 emissions level. Results show that CCS retrofit and compensatory renewable power for case 3 is 2.6 times higher than case 1 and 1.8 times higher than case 2. According to sensitivity analysis results, CCS retrofit and compensatory renewable power for case 3 is more sensitive to CO₂ removal ratio and parasitic energy loss ratio, respectively, as compared to case 1 and case 2.     

Improved analysis of the intermodulation performance of ferroelectric thin-film and bulk-based varactors

In this paper, Fourier cosine series are proposed for representing the hard nonlinear dependence of the permittivity and conductance of a ferroelectric material on the DC bias voltage. Using these Fourier series representations closed-form expressions are obtained for the amplitudes of the fundamental and third-order intermodulation products generated when a exposing ferroelectric-based varactor to a DC bias voltage plus an equal-amplitude two-sinusoids signal. The results clearly show the strong and complicated dependence of the third-order intermodulation performance on the DC bias voltage, the temperature and the amplitude of the sinusoid. The results obtained suggest that the DC bias voltage and/or the temperature play an important role in deciding the nonlinear performance of the ferroelectric-based varactors.