Production and analysis of electrospun PA 6,6 and PVA nanofibrous surfaces for filtration

Electrospun nanofibrous surfaces were produced by using two different polymers (PA 6,6 and PVA) at three different levels of polymer feeding rate (0.2, 0.6 and 1.0 ml/h, respectively) and three different levels of production time in electrospinning (5, 10 and 15 minutes, respectively) and the effect of polymer type, polymer feeding rate and production time was determined by analyzing unit weight and thickness of the nanofibrous membranes as well as fibre fineness and pore size distributions. The results showed that much finer fibres were produced by PA 6,6 polymer compare to PVA. The minimum average fibre fineness was 150.96 nm (by PA 6,6 polymer; 0.2 ml/h; 5 min.) while maximum fibre fineness was 243.43 nm (by PVA polymer; 0.6 ml/h; 15 min.). Similarly, the pore sizes of nanofibrous surfaces produced by PA 6,6 were smaller compare to the ones produced by PVA polymer. The results also indicated that coarser fibres were produced as the polymer feed rate and electrospinning time increased. In the second part of the work, composite structures were obtained by combining nanofibrous surfaces with PP non-woven material and their air permeability and filtration efficiency by using an aerosol having 0.2–0.33 mm diameter range were analyzed. The air permeability of PA 6,6 nanofibrous surfaces were much higher compare to the ones produced by PVA and quite high filtration efficiency (99.901 %) was obtained with PA 6,6 nanofibrous surfaces. Also, potential of these nanofibrous surfaces was evaluated by analysing chemical groups eliminated following their exposure to cigarette smoke which was chosen as a specific case study.

EMULSION ELECTROSPINNING OF POLYVINYLPYRROLIDONE (PVP)/PARACETAMOL NANOFIBERS

This study aimed to achieve Polyvinylpyrrolidone (PVP) nanofiber production including paracetamol (PCT) by oil-in-water emulsion electrospinning. At first, emulsions were prepared at 14 wt % PVP with various PCT concentrations (0, 0.1, 0.3, 0.5, 0.7, 0.9 wt %). Then, solution properties such as viscosity, conductivity, and surface tension were determined. The production of nanofiber samples was carried out by emulsion electrospinning under the optimum process parameters (voltage, distance between electrodes, feed rate, and atmospheric conditions). Finally, the morphological and structural characterization of the nanofiber surface was carried out with SEM and FT-IR. According to the results of emulsion properties, although the change is not remarkable, it tends to increase the viscosity with an increase in PCT concentration. On the other hand, it was observed that surface tension did not change significantly with PCT concentration increasement and while the conductivity of emulsions decreased slightly. When the fibre structure was investigated, average fibre diameter and fibre diameter uniformity were not affected prominently by PCT concentration. From the SEM images, it is possible to say that generally fine, uniform and bead-free drug-loaded nanofibers were obtained. The finest (326 nm) and most uniform (1.03) nanofibers were achieved from the sample N4 which included 0.5 wt % PCT. Also, the FT-IR results verified that PVP and PCT exist in the nanofiber structure.

Evaluation of a new portable device that measures diameter of animal fibres

Increasing production of animal fibres has increased the need for a portable instrument that measures fibre diameter and associated characteristics with precision and accuracy. This research evaluated a new portable fibre tester (PFT) by measuring the diameter and related characteristics of tops and scoured fibres of wool, alpaca, and vicuña. The PFT was constructed with integrated mechanical, optical, electronic, and informatic components. Textile tops of sheep wool, alpaca fibres, and mohair goat fibres were used as standard references to calibrate the PFT and determine its accuracy and precision. The results were compared with those from a wool industry standard instrument (OFDA2000) that uses similar technology. The PFT had high accuracy (-0.01, -0.12, and -0.01 μm) for average fibre diameter (AFD) of wool, alpaca, and mohair fibres, respectively. Deviations of standard tops (ST) were within industry-accepted tolerance ranges. Standard errors, indicating precision, were low, ranging from 0.07 to 0.25 μm, 0.02 to 0.44 μm, and 0.09 to 0.024 μm, for wool, alpaca, and mohair fibre tops, respectively. The correlations of measurements of AFD from the two instruments were 0.99 for wool, alpaca, and mohair fibres, but lower for vicuña fibres (0.82). No evidence of bias was observed. Therefore, the PFT may be used as an alternative instrument for measuring fibre diameter and quantifying variation in diameter of wool, mohair, and alpaca fibres. The PFT has appeal for use in the field for practical animal selection and fleece classification based on fibre characteristics. Keywords: alpaca, fibre diameter, mohair, vicuña, wool

Screening of Phytochemical, Antioxidant and Fiber Levels of Sweet Potato (Ipomoea batatas), Cassava (Manihot esculenta), and Binahong (Anredera cordifolia (Ten) Steenis) Leaves Extract

Generally, vegetables contain various vitamins, minerals, and pigments that have antioxidant activity and can neutralise free radicals before causing damage to body cells. The research aimed to analyse phytochemical, antioxidant contents, and fibre levels of leaves extract of sweet potato, cassava, and binahong. The study was experimental research utilising leaves of sweet potato, cassava, and binahong. The leaves were removed and analysed for contents of phytochemicals, antioxidant and fibre levels. Flavonoid compounds were obtained positively on the 5-blades leaves extract of Cassavas. Polyphenol and tannin were undoubtedly discovered on the single, and 3-blades leaves extract of Sweet Potatoes and also on the five, and 7-blades leaves extract of Cassavas. Interestingly, alkaloids and steroids were identified on leaves extract of binahong, the single and 3-blades leaves extract of Sweet Potatoes and also on the five and 7-blades leaves extract of Cassavas. Consequently, 7-blades leaves extract of Cassavas contains the highest level of antioxidants (IC50), which was 44.46% (90 ppm). Nonetheless, 3-blades leaves extract of Sweet Potatoes contains the lowest. The leaves extract of binahong had an average fibre content of 28.45%, followed by 5-blades cassava leaves at 26.59%, and cassava leaves at 25%. The extract of sweet potato leaves was able to be developed as a source of antioxidants. Moreover, it contained high fibres.

Constructing a Human Atrial Fibre Atlas

Atrial anisotropy affects electrical propagation patterns, anchor locations of atrial reentrant drivers, and atrial mechanics. However, patient-specific atrial fibre fields and anisotropy measurements are not currently available, and consequently assigning fibre fields to atrial models is challenging. We aimed to construct an atrial fibre atlas from a high-resolution DTMRI dataset that optimally reproduces electrophysiology simulation predictions corresponding to patient-specific fibre fields, and to develop a methodology for automatically assigning fibres to patient-specific anatomies. We extended an atrial coordinate system to map the pulmonary veins, vena cava and appendages to standardised positions in the coordinate system corresponding to the average location across the anatomies. We then expressed each fibre field in this atrial coordinate system and calculated an average fibre field. To assess the effects of fibre field on patient-specific modelling predictions, we calculated paced activation time maps and electrical driver locations during AF. In total, 756 activation time maps were calculated (7 anatomies with 9 fibre maps and 2 pacing locations, for the endocardial, epicardial and bilayer surface models of the LA and RA). Patient-specific fibre fields had a relatively small effect on average paced activation maps (range of mean local activation time difference for LA fields: 2.67–3.60 ms, and for RA fields: 2.29–3.44 ms), but had a larger effect on maximum LAT differences (range for LA 12.7–16.6%; range for RA 11.9–15.0%). A total of 126 phase singularity density maps were calculated (7 anatomies with 9 fibre maps for the LA and RA bilayer models). The fibre field corresponding to anatomy 1 had the highest median PS density map correlation coefficient for LA bilayer simulations (0.44 compared to the other correlations, ranging from 0.14 to 0.39), while the average fibre field had the highest correlation for the RA bilayer simulations (0.61 compared to the other correlations, ranging from 0.37 to 0.56). For sinus rhythm simulations, average activation time is robust to fibre field direction; however, maximum differences can still be significant. Patient specific fibres are more important for arrhythmia simulations, particularly in the left atrium. We propose using the fibre field corresponding to DTMRI dataset 1 for LA simulations, and the average fibre field for RA simulations as these optimally predicted arrhythmia properties.

Effect of the Solvent System on the Morphology and Performance of Nylon 6 Nanofibre Membranes

Nylon 6 nanofibre membranes were prepared by electrospinning of nylon 6 solutions with various volume ratios of trifluoroethyl alcohol (TFE) and formic acid (FA). The effect of the solvent type on the morphology of nylon 6 nanofibre membranes was investigated. Results showed that all membranes studied showed uniform, defect-free structures with very thin nanofibre diameters. The addition of formic acid led to a significant decrease in average fibre diameters. The average fibre diameters were 660, 186, 87, 62 and 30 nm for nylon 6 nonofibre prepared using the binary solution system and trifluoroethyl alcohol/formic acid (100:0), (75:25), (50:50), (25:75) & (0:100) respectively. In addition, the nylon 6 nanofibre membranes prepared using formic acid showed the highest strength with the highest porosity and the lowest average fibre diameters.

Theoretical analysis of LC-refining – pressure screening systems in TMP

LC refining of mechanical pulps has proven to save energy in the production of TMP pulps. However, the specific role of LC refining as part of a TMP system has not been thoroughly studied since it is difficult to conceive any particular system at industrial-scales and impractical at pilot-scales. In this study, pressure screening and LC refining models that describe fibre length distributions, together with correlations to predict refining power were used to model three basic refining systems. From the simulation results, the impact of important variables such as reject ratio, refiner gap and refining net-power was studied. Performance curves of length-weighed average fibre length were generated from simulation results and were used to assess each system behaviour and also to make comparisons between systems. Data from an industrial scale TMP mill sub-system was gathered and compared to simulation results showing relative errors between 0–18 % on the predicted variables.

Wool Textiles from the Roman Period at the Site of Grudna, Poland

In October 2012, the Conservation Laboratory of the Institute of Archaeology at the NCU in Toruń received soil samples excavated from a kurgan in Grudna, Złotów commune, dated to the Roman period. No human remains were reported inside the grave chamber apart from some elements of grave goods: a glass bead, a clay spindle whorl, three iron nails, fragments of a bone pin, bronze and iron chest fittings, and a bronze vessel with a stamp of Pubius Cipius Polybius, who was active around the first half of the 1st century AD. In result of a cleaning treatment removing all soil impurities, tiny textile fragments were obtained, which were, interestingly, made of woollen fibres in sprang technique, while some of them imitated gauze (known in later periods) but were manufactured in a plain 1/1 weave. Technological analysis of the fibres revealed their high quality with average fibre thickness ranging from 8 to 18 μm. Insufficient material base for these textiles in Poland does not give a convincing answer to a basic question of whether it was an import or local production. Studies on the subject performed by European researchers, most notably J. Maik, indicate local or North European production. Hopefully, more light will be shed on this problem by further comparative studies.

Average fibre length as a measure of the amount of long fibres in mechanical pulps – ranking of pulps may shift

The purpose of this study was to investigate the applicability of different ways of calculating the average fibre length based on length measurements of individual particles of mechanical pulps. We have found that the commonly used average length-weighted fibre length, which is based on the assumption that coarseness is constant for all particles, as well as the arithmetic average, may lead to erroneous conclusions in real life as well as in simulations when used as a measure of the amount of long fibres. The average length-length-weighted fibre length or a weighting close to that, which to a larger extent suppresses the influence of shorter particles, is a relevant parameter of the “length” factor, i. e. amount of long fibres. Our findings are based on three studies: refining of different assortments of wood raw material in a mill; data from LC refining in mill of TMP, including Bauer McNett fractionation; mixing of pulps with different fibre length distributions. If the acceptable average fibre length for different products can be lowered, the possibility of reducing the specific energy input in refining will increase. Therefore, we need a reliable and appropriate way to assess the “length” factor.

The effect of graphene–poly(methyl methacrylate) fibres on microbial growth

A novel class of ultra-thin fibres, which affect microbial growth, were explored. The microbial properties of poly(methyl methacrylate) fibres containing 2, 4 and 8 wt% of graphene nanoplatelets (GNPs) were studied. GNPs were dispersed in a polymeric solution and processed using pressurized gyration. Electron microscopy was used to characterize GNP and fibre morphology. Scanning electron microscopy revealed the formation of beaded porous fibres. GNP concentration was found to dictate fibre morphology. As the GNP concentration increased, the average fibre diameter increased from 0.75 to 2.71 µm, while fibre porosity decreased. Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa were used to investigate the properties of 2, 4 and 8 wt% GNP-loaded fibres. GNP-loaded fibres (0 wt%) were used as the negative control. The fibres were incubated for 24 h with the bacteria; bacterial colony-forming units were enumerated by adopting the colony-counting method. The presence of 2 and 4 wt% GNP-loaded fibres promoted microbial growth, while 8 wt% GNP-loaded fibres showed antimicrobial activity. These results indicate that the minimum inhibitory concentration of GNPs required within a fibre is 8 wt%.