Search results for: nutrient film technique (NFT)

Authors: Mariana Gomez Gomez, Maria Elena Sanchez Vergara

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Many sustainable approaches to generate electric energy have emerged in the last few decades; one of them is through solar cells. Yet, this also has the disadvantage of highly polluting inorganic semiconductor manufacturing processes. Therefore, the use of molecular semiconductors must be considered. In this work, allene compounds C24H26O4 and C24H26O5 were used as dopants to manufacture semiconductors films based on PbPc by high-vacuum evaporation technique. IR spectroscopy was carried out to determine the phase and any significant chemical changes which may occur during the thermal evaporation. According to UV-visible spectroscopy and Tauc’s model, the deposition process generated thin films with an activation energy range of 1.47 to 1.55 eV for direct transitions and 1.29 to 1.33 eV for indirect transitions. These values place the manufactured films within the range of low bandgap semiconductors. The flexible devices were manufactured: polyethylene terephthalate (PET), Indium tin oxide (ITO)/organic semiconductor/ Cubic Close Packed (CCP). The characterization of the devices was carried out by evaluating electrical conductivity using the four-probe collinear method. I-V curves were obtained under different lighting conditions at room temperature. OS1 (PbPc/C24H26O4) showed an Ohmic behavior, while OS2 (PbPc/C24H26O5) reached higher current values ​​at lower voltages. The results obtained show that the semiconductors devices doped with allene compounds can be used in the manufacture of optoelectronic devices.

Keywords: electrical properties, optical gap, phthalocyanine, thin film.

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Authors: Waleed Maqableh, Ahmad Al-Hamad, Manjit Sidhu

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Augmented reality (AR) technology has the capability to provide many benefits in the field of education as a modern technology which aided learning and improved the learning experience. This paper evaluates AR based application with multiple markers interaction technique (touch-to-print) which is designed for analyzing the kinematics of 4BL mechanism in mechanical engineering. The application is termed as AR-4BL-MAST and it allows the users to touch the symbols on a paper in natural way of interaction. The evaluation of this application was performed with mechanical engineering students and human–computer interaction (HCI) experts to test its effectiveness as a tangible user interface application where the statistical results show its ability as an interaction technique, and it gives the users more freedom in interaction with the virtual mechanical objects.

Keywords: augmented reality, multimedia, user interface, engineering, education technology

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Authors: Tanmaya Kumar Dash, Tarun Karamshetty, Soumitra Paul

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The Barkhausen Noise Analysis (BNA) technique has been utilized to assess surface integrity of steels. But the BNA technique is not very successful in evaluating surface integrity of ground steels that exhibit poor micro-magnetic response. A new approach has been proposed for the processing of BN signal with Fast Fourier transforms while Wavelet transforms has been used to remove noise from the BN signal, with judicious choice of the ‘threshold’ value, when the micro-magnetic response of the work material is poor. In the present study, the effect of down feed induced upon conventional plunge surface grinding of hardened bearing steel has been investigated along with an ultrasonically cleaned, wet polished and a sample ground with spark out technique for benchmarking. Moreover, the FFT analysis has been established, at different sets of applied voltages and applied frequency and the pattern of the BN signal in the frequency domain is analyzed. The study also depicts the wavelet transforms technique with different levels of decomposition and different mother wavelets, which has been used to reduce the noise value in BN signal of materials with poor micro-magnetic response, in order to standardize the procedure for all BN signals depending on the frequency of the applied voltage.

Keywords: barkhausen noise analysis, grinding, magnetic properties, signal processing, micro-magnetic response

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Authors: F. Sevim, E. Sevimli, F. Demir, T. Çalban

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For the first time, nanofibers of PVA /nickel nitrate/silica/alumina izopropoxide/boric acid composite were prepared by using sol-gel processing and electrospinning technique. By high temperature calcinations of the above precursor fibers, nanofibers of NiO/Al2O3/B2O3/SiO2 composite with diameters of 500 nm could be successfully obtained. The fibers were characterized by TG/DTA, FT-IR, XRD and SEM analyses.

Keywords: nano fibers, NiO/Al2O3/B2O3/SiO2 composite, sol-gel processing, electro spinning

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Authors: Ivan Maguire, Ciprian Briciu, Alan Barrett, Dara Kervick, Jens Ducrèe, Fiona Regan

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With the ever-increasing myriad of applications of which microfluidic devices are capable, reliable fluidic actuation development has remained fundamental to the success of these microfluidic platforms. There are a number of approaches which can be taken in order to integrate liquid actuation on microfluidic platforms, which can usually be split into two primary categories; active microvalves and passive microvalves. Active microvalves are microfluidic valves which require a physical parameter change by external, or separate interaction, for actuation to occur. Passive microvalves are microfluidic valves which don’t require external interaction for actuation due to the valve’s natural physical parameters, which can be overcome through sample interaction. The purpose of this paper is to illustrate how further improvements to past microvalve solutions can largely enhance systematic reliability and performance, with both novel active and passive microvalves demonstrated. Covered within this scope will be two alternative and novel microvalve solutions for centrifugal microfluidic platforms; a revamped pneumatic-dissolvable film active microvalve (PAM) strategy and a spray-on Sol-Gel based hydrophobic passive microvalve (HPM) approach. Both the PAM and the HPM mechanisms were demonstrated on a centrifugal microfluidic platform consisting of alternating layers of 1.5 mm poly(methyl methacrylate) (PMMA) (for reagent storage) sheets and ~150 μm pressure sensitive adhesive (PSA) (for microchannel fabrication) sheets. The PAM approach differs from previous SOLUBON™ dissolvable film methods by introducing a more reliable and predictable liquid delivery mechanism to microvalve site, thus significantly reducing premature activation. This approach has also shown excellent synchronicity when performed in a multiplexed form. The HPM method utilises a new spray-on and low curing temperature (70°C) sol-gel material. The resultant double layer coating comprises a PMMA adherent sol-gel as the bottom layer and an ultra hydrophobic silica nano-particles (SNPs) film as the top layer. The optimal coating was integrated to microfluidic channels with varying cross-sectional area for assessing microvalve burst frequencies consistency. It is hoped that these microvalving solutions, which can be easily added to centrifugal microfluidic platforms, will significantly improve automation reliability.

Keywords: centrifugal microfluidics, hydrophobic microvalves, lab-on-a-disc, pneumatic microvalves

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Authors: Yunha Ryu, Kyoungsik Kim

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Raman spectroscopy is one of the most powerful techniques for chemical detection, but the low sensitivity originated from the extremely small cross-section of the Raman scattering limits the practical use of Raman spectroscopy. To overcome this problem, Surface Enhanced Raman Scattering (SERS) has been intensively studied for several decades. Because the SERS effect is mainly induced from strong electromagnetic near-field enhancement as a result of localized surface plasmon resonance of metallic nanostructures, it is important to design the plasmonic structures with high density of electromagnetic hot spots for SERS substrate. One of the useful fabrication methods is using porous nanomaterial as a template for metallic structure. Internal pores on a scale of tens of nanometers can be strong EM hotspots by confining the incident light. Also, porous structures can capture more target molecules than non-porous structures in a same detection spot thanks to the large surface area. Herein we report the facile fabrication method of porous SERS substrate by integrating solvent-assisted nanoimprint lithography and selective etching of block copolymer. We obtained nanostructures with high porosity via simple selective etching of the one microdomain of the diblock copolymer. Furthermore, we imprinted of the nanocone patterns into the spin-coated flat block copolymer film to make three-dimensional SERS substrate for the high density of SERS hot spots as well as large surface area. We used solvent-assisted nanoimprint lithography (SAIL) to reduce the fabrication time and cost for patterning BCP film by taking advantage of a solvent which dissolves both polystyrenre and poly(methyl methacrylate) domain of the block copolymer, and thus block copolymer film was molded under the low temperature and atmospheric pressure in a short time. After Ag deposition, we measured Raman intensity of dye molecules adsorbed on the fabricated structure. Compared to the Raman signals of Ag coated solid nanocone, porous nanocone showed 10 times higher Raman intensity at 1510 cm(-1) band. In conclusion, we fabricated porous metallic nanocone arrays with high density electromagnetic hotspots by templating nanoimprinted diblock copolymer with selective etching and demonstrated its capability as an effective SERS substrate.

Keywords: block copolymer, porous nanostructure, solvent-assisted nanoimprint, surface-enhanced Raman spectroscopy

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Authors: Sadaf Sahar, Usman Qamar, Sadaf Ayaz

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In the software development lifecycle, the quality prediction techniques hold a prime importance in order to minimize future design errors and expensive maintenance. There are many techniques proposed by various researchers, but with the increasing complexity of the software lifecycle model, it is crucial to develop a flexible system which can cater for the factors which in result have an impact on the quality of the end product. These factors include properties of the software development process and the product along with its operation conditions. In this paper, a neural network (perceptron) based software quality prediction technique is proposed. Using this technique, the stakeholders can predict the quality of the resulting software during the early phases of the lifecycle saving time and resources on future elimination of design errors and costly maintenance. This technique can be brought into practical use using successful training.

Keywords: software quality, fuzzy logic, perception, prediction

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Authors: A. H. Dikko, D. N Tsado, M. S. T. Rita, D. S. Umar

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This study was conducted on eighteen (18) New Zealand and chinchilla breeds of rabbits were used. The rabbits were allotted to 3 treatments with each treatment having six (6) animals with two (2) replicates. T1 were castrated, which both testes was removed (Bilateral); T2 were castrated, which only one testes was removed (unilateral) and T3 were not castrated (control). In nutrient digestibility, T1 and T2 (p>0.05) has a higher rate than T3. There was no significant (p<0.05) difference in live weight and dressing weight among the treatment groups. There is a significant (p > 0.05) difference in visceral organs in the treatment groups.

Keywords: New Zealand, chinchilla, castration, bilateral, unilateral

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Authors: Nur Ashida Salim, Muhammad Murtadha Othman, Ismail Musirin, Mohd Salleh Serwan

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Over the past few decades, the power system industry in many developing and developed countries has gone through a restructuring process of the industry where they are moving towards a deregulated power industry. This situation will lead to competition among the generation and distribution companies to achieve a certain objective which is to provide quality and efficient production of electric energy, which will reduce the price of electricity. Therefore it is important to obtain an accurate value of the Available Transfer Capability (ATC) and Transmission Reliability Margin (TRM) in order to ensure the effective power transfer between areas during the occurrence of uncertainties in the system. In this paper, the TRM and ATC is determined by taking into consideration the uncertainties of the system operating condition and system cascading collapse by applying the bootstrap technique. A case study of the IEEE RTS-79 is employed to verify the robustness of the technique proposed in the determination of TRM and ATC.

Keywords: available transfer capability, bootstrap technique, cascading collapse, transmission reliability margin

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Authors: Susan Cardillo

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This research will consider ways to bridge the gap between Computer Science and Media Communications and while doing so create Social Entrepreneurship for student success. New Media, as it has been referred to, is considered content available on-demand through Internet, a digital device, usually containing some kind of interactivity and creative participation. It is the interplay between technology, images, media and communications. The next generation of the newspaper, radio, television, and film students need to have a working knowledge of the technologies that are available for the creation of their work and taught to use this knowledge to create a voice. The work is interdisciplinary; in communications, we understand the necessity of reporting and disseminating information. In documentary film we understand the instructional and historic aspects of media and technology and in the non-profit sector, we see the need for expanding outlets for good. So, the true necessity is to utilize ‘new media’ technologies to advance social causes while reporting information, teaching and creating art. Goals: The goal of this research is to give communications students a better understanding of the technology that is both, currently at their disposal, and on the horizon, so that they can use it in their media, communications and art endeavors to be a voice for their generation. There is no longer a need to be a computer scientist to have a working knowledge of communication technologies and how they will benefit our work. There are many free and easy to use applications available for the creation of interactive communications. Methodology: This is Qualitative-Case Study that puts these ideas into action. There is a survey at the end of the experiment that is qualitative in nature and allows for the participants to share ideas and feelings about the technology and approach.

Keywords: interactive storytelling, web documentary, mass communications, teaching

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Authors: Andrey A. Tyuftin, David Clarke, Malco C. Cruz-Romero, Declan Bolton, Seamus Fanning, Shashi K. Pankaj, Carmen Bueno-Ferrer, Patrick J. Cullen, Joe P. Kerry

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Prolonging of shelf-life is essential in order to address issues such as; supplier demands across continents, economical profit, customer satisfaction, and reduction of food wastage. Smart packaging solutions presented in the form of naturally occurred antimicrobially-active packaging may be a solution to these and other issues. Gelatin film forming solution with adding of natural sourced antimicrobials is a promising tool for the active smart packaging. The objective of this study was to coat conventional plastic hydrophobic packaging material with hydrophilic antimicrobial active beef gelatin coating and conduct shelf life trials on beef sub-primal cuts. Minimal inhibition concentration (MIC) of Caprylic acid sodium salt (SO) and commercially available Auranta FV (AFV) (bitter oranges extract with mixture of nutritive organic acids) were found of 1 and 1.5 % respectively against bacterial strains Bacillus cereus, Pseudomonas fluorescens, Escherichia coli, Staphylococcus aureus and aerobic and anaerobic beef microflora. Therefore SO or AFV were incorporated in beef gelatin film forming solution in concentration of two times of MIC which was coated on a conventional plastic LDPE/PA film on the inner cold plasma treated polyethylene surface. Beef samples were vacuum packed in this material and stored under chilling conditions, sampled at weekly intervals during 42 days shelf life study. No significant differences (p < 0.05) in the cook loss was observed among the different treatments compared to control samples until the day 29. Only for AFV coated beef sample it was 3% higher (37.3%) than the control (34.4 %) on the day 36. It was found antimicrobial films did not protect beef against discoloration. SO containing packages significantly (p < 0.05) reduced Total viable bacterial counts (TVC) compared to the control and AFV samples until the day 35. No significant reduction in TVC was observed between SO and AFV films on the day 42 but a significant difference was observed compared to control samples with a 1.40 log of bacteria reduction on the day 42. AFV films significantly (p < 0.05) reduced TVC compared to control samples from the day 14 until the day 42. Control samples reached the set value of 7 log CFU/g on day 27 of testing, AFV films did not reach this set limit until day 35 and SO films until day 42 of testing. The antimicrobial AFV and SO coated films significantly prolonged the shelf-life of beef steaks by 33 or 55% (on 7 and 14 days respectively) compared to control film samples. It is concluded antimicrobial coated films were successfully developed by coating the inner polyethylene layer of conventional LDPE/PA laminated films after plasma surface treatment. The results indicated that the use of antimicrobial active packaging coated with SO or AFV increased significantly (p < 0.05) the shelf life of the beef sub-primal. Overall, AFV or SO containing gelatin coatings have the potential of being used as effective antimicrobials for active packaging applications for muscle-based food products.

Keywords: active packaging, antimicrobials, edible coatings, food packaging, gelatin films, meat science

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Authors: N. H. S. Mustafa, N. M. Yatim

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Thermoelectric materials arrange in segmented design could increase the conversion of heat to electricity performance. This is due to the properties of materials that perform peak at narrow temperature range. Performance of the materials determines by dimensionless figure-of-merit, ZT which consist of thermoelectric properties namely Seebeck coefficient, electrical resistivity, and thermal conductivity. Since different materials were arrange in segmented, determination of ZT cannot be measured using the conventional approach. Therefore, this research used 'open-short circuit' technique to measure the segmented performance. Segmented thermoelectric materials consist of bismuth telluride, and lead telluride was segmented together under cold press technique. The results show thermoelectric properties measured is comparable with calculated based on commercially available of individual material. Performances of segmented sample under different polarity also indicate dependability of material with position and temperature. Segmented materials successfully measured under real condition and optimization of the segmented can be designed from the study of polarity change.

Keywords: thermoelectric, segmented, ZT, polarity, performance

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Authors: Saeed Ahmed, Tamoor Abbas, M. Amir, M. S. Iqbal, D. Hussain

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This study was conducted to evaluate the effect of supplementation of different levels of yeast culture (Saccharomyces cerevisiae) in Beetal male goats diets on growth performance, digestibility of nutrients and selected blood metabolites. Another objective was to determine the inclusion level of yeast culture for optimal growth performance of Beetal male goats. Eighteen (n=18) Beetal male goats were randomly assigned to three total mixed ration treatments (n=6 goats/treatment): T1, T2 and T3 containing 0gm, 3gm and 6gm/day yeast culture (YC) mixed with total mixed ration (TMR). The diets were iso-nitrogenous and iso-caloric having crude protein 15.2% and ME 2.6Mcal/kg. The total duration of the experiment was 8 weeks. Beetal bucks were fed on TMR diets (T1, T2 and T3) having blend of oat silage, Lucerne hay and concentrate mixed with yeast culture (YC). Bucks were housed individually and feed was offered @ 4% of body weight on dry matter basis. Samples of fresh feed and refusal were collected twice weekly of moisture percentage using hot air oven. Data for daily dry matter intake, body weight gain, nutrient digestibility and selected blood metabolites were analyzed through one-way ANOVA technique under Complete randomised design (SAS Institute Inc, 2002-03). Results were declared significant at P≤0.05. Overall, DMI was not affected (P≥0.05) by dietary treatments. Body weight gain, digestibility of crude protein and crude fibre were improved. Blood glucose concentration was detected higher in the group having supplementation of yeast culture (YC) 6gm/day compared to other two dietary treatments. This study suggested the positive impact of inclusion of yeast culture (YC) up to 6gm/day in the TMR diet for optimal growth performance and digestibility of nutrients in Beetal male goats.

Keywords: yeast culture, growth performance, digestibility, beetle goat

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Authors: A. Ritcey, J. R. Mcdermid, S. Ziada

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Wall shear stress was experimentally measured under a planar impinging air jet as a function of jet Reynolds number (Rejet = 5000, 8000, 11000) and different normalized impingement distances (H/D = 4, 6, 8, 10, 12) using the razor blade technique to complete a parametric study. The wall pressure, wall pressure gradient, and wall shear stress information were obtained.

Keywords: experimental fluid mechanics, impinging planar jets, skin friction factor, wall shear stress

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Authors: Sk Shamim Hasan Abir, Karen Lozano, Mohammed Jasim Uddin

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Over the last few years, nanofiber-based triboelectric nanogenerator (TENG) has caught great attention among researchers all over the world due to its inherent capability of converting mechanical energy to usable electrical energy. In this study, poly(vinylidene fluoride) (PVDF) and thermoplastic polyurethane (TPU) nanofiber prepared by Forcespinning® (FS) technique were used to fabricate TENG for self-charging energy storage device and biomechanical body motion sensor. The surface of the TPU nanofiber was modified by uniform deposition of thin gold film to enhance the frictional properties; yielded 254 V open-circuit voltage (Voc) and 86 µA short circuit current (Isc), which were 2.12 and 1.87 times greater in contrast to bare PVDF-TPU TENG. Moreover, the as-fabricated PVDF-TPU/Au TENG was tested against variable capacitors and resistive load, and the results showed that with a 3.2 x 2.5 cm2 active contact area, it can quick charge up to 7.64 V within 30 seconds using a 1.0 µF capacitor and generate significant 2.54 mW power, enough to light 75 commercial LEDs (1.5 V each) by the hand tapping motion at 4 Hz (240 beats per minutes (bpm)) load frequency. Furthermore, the TENG was attached to different body parts to capture distinctive electrical signals for various body movements, elucidated the prospective usability of our prepared nanofiber-based TENG in wearable body motion sensor application.

Keywords: biomotion sensor, forcespinning, nanofibers, triboelectric nanogenerator

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Authors: Shivaji M. Sonawane, N. B. Chaure

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ZnTe is direct band gap, the P-type semiconductor with the high absorption coefficient of the order of 104cm-1 is suitable for solar cell development. It can be used as a low resistive ohmic contact to CdS/CdTe or tandem solar cell application. ZnTe and Cu-ZnTe thin film have been electrochemically synthesized on to fluorine-doped tin oxide coated glass substrates using three electrode systems containing Ag/AgCl, graphite and FTO as reference, counter and working electrode respectively were used to deposit the thin films. The aqueous electrolytic solution consist of 0.5M TeO2, 0.2M ZnSO4, and 0.1M Na3C6H5O7:2H2O, 0.1MC6H8O7:H2O and 0.1mMCuSO4 with PH 2.5 at room temperature was used. The reaction mechanism is studied in the cyclic voltammetry to identify the deposition potentials of ZnTe and Cu-ZnTe.The potential was optimized in the range -0,9 to -1,1 V. Vs Ag/AgCl reference electrode. The effect of deposition potential on the structural properties was studied by using X-ray diffraction. The X-ray diffraction result reveled cubic crystal structure of ZnTe with preferential (111) orientation with cubic structure. The surface morphology and film composition were analyzed by means of Scanning electron microscopy (SEM) and Energy Dispersive Analysis of X- Rays (EDAX). The optical absorption measurement has been analyzed for the band gap determination of deposited layers about 2.26 eV by UV-Visible spectroscopy. The drastic change in resistivity has been observed due to incorporation of copper probably due to the diffusion of Cu into grain boundaries.

Keywords: ohmic back contact, zinc telluride, electrodeposition, photovoltaic devices

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Authors: M. P. Casiraghi, C. M. Quintella, P. Almeida

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Paraffinic oils were submitted to microbial action. The microorganisms consisted of bacteria of the genera Pseudomonas sp and Bacillus lincheniforms. The alterations in interfacial tension were determined using a tensometer and applying the hanging drop technique at room temperature (299 K ±275 K). The alteration in the constitution of the paraffins was evaluated by means of gas chromatography. The microbial activity was observed to reduce interfacial tension by 54 to 78%, as well as consuming the paraffins C19 to C29 and producing paraffins C36 to C44. The LIFirr technique made it possible to determine the microbial action quickly.

Keywords: paraffins, biosurfactants, LIFirr, microbial activity

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Authors: A. Ferasat, S. Rostampour Yasouri

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Seasonal flu is a highly contagious infection caused by influenza viruses. These viruses undergo genetic changes that result in new epidemics across the globe. Medical attention is crucial in severe cases, particularly for the elderly, frail, and those with chronic illnesses, as their immune systems are often weaker. The purpose of this study was to detect new subtypes of the influenza A virus rapidly using a specific RT-PCR method based on the HA gene (hemagglutinin). In the winter and spring of 2022_2023, 120 embryonated egg samples were cultured, suspected of seasonal influenza. RNA synthesis, followed by cDNA synthesis, was performed. Finally, the PCR technique was applied using a pair of specific primers designed based on the HA gene. The PCR product was identified after purification, and the nucleotide sequence of purified PCR products was compared with the sequences in the gene bank. The results showed a high similarity between the sequence of the positive samples isolated from the patients and the sequence of the new strains isolated in recent years. This RT-PCR technique is entirely specific in this study, enabling the detection and multiplication of influenza and its subspecies from clinical samples. The RT-PCR technique based on the HA gene, along with sequencing, is a fast, specific, and sensitive diagnostic method for those infected with influenza viruses and its new subtypes. Rapid molecular diagnosis of influenza is essential for suspected people to control and prevent the spread of the disease to others. It also prevents the occurrence of secondary (sometimes fatal) pneumonia that results from influenza and pathogenic bacteria. The critical role of rapid diagnosis of new strains of influenza is to prepare a drug vaccine against the latest viruses that did not exist in the community last year and are entirely new viruses.

Keywords: influenza, molecular diagnosis, patients, RT-PCR technique

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Authors: Guijie Sang, Geo Davis, Momchil Terziev

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Geological CO2 storage has been regarded as a promising strategy to mitigate the emission of greenhouse gas generated from traditional power stations and energy-intensive industry. Caprocks with very low permeability and ultra-fine pores create viscous and capillary barriers to guarantee CO2 sealing efficiency. However, caprock fractures, either naturally existing or artificially induced due to injection, could provide preferential paths for CO₂ escaping. Seeking an efficient technique to seal and strengthen caprock fractures is crucial. We apply microbial-induced-calcite-precipitation (MICP) technique for sealing and strengthening caprock fractures in the laboratory scale. The MICP bio-grouting technique has several advantages over conventional cement grouting methods, including its low viscosity, micron-size microbes (accessible to fine apertures), and low carbon footprint, among others. Different injection strategies are tested to achieve relatively homogenous calcite precipitation along the fractures, which is monitored dynamically based on laser ultrasonic technique. The MICP process in caprock fractures, which integrates the coupled flow and bio-chemical precipitation, is also modeled and validated through the experiment. The study could provide an effective bio-mediated grouting strategy for caprock sealing and thus ensuring a long-term safe geological CO2 storage.

Keywords: caprock sealing, geological CO2 storage, grouting strategy, microbial induced calcite precipitation

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Authors: Lamia Bourdache, Amar Djema

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The effect of non-Newtonian property (power law index n) on traveling waves of thin layer of power law fluid flowing over an inclined plane is investigated. For this, a simplified second-order two-equation model (SM) is used. The complete model is second-order four-equation (CM). It is derived by combining the weighted residual integral method and the lubrication theory. This is due to the fact that at the beginning of the instability waves, a very small number of waves is observed. Using a suitable set of test functions, second order terms are eliminated from the calculus so that the model is still accurate to the second order approximation. Linear, spatial, and temporal stabilities are studied. For travelling waves, a particular type of wave form that is steady in a moving frame, i.e., that travels at a constant celerity without changing its shape is studied. This type of solutions which are characterized by their celerity exists under suitable conditions, when the widening due to dispersion is balanced exactly by the narrowing effect due to the nonlinearity. Changing the parameter of celerity in some range allows exploring the entire spectrum of asymptotic behavior of these traveling waves. The (SM) model is converted into a three dimensional dynamical system. The result is that the model exhibits bifurcation scenarios such as heteroclinic, homoclinic, Hopf, and period-doubling bifurcations for different values of the power law index n. The influence of the non-Newtonian parameter on the nonlinear development of these travelling waves is discussed. It is found at the end that the qualitative characters of bifurcation scenarios are insensitive to the variation of the power law index.

Keywords: inclined plane, nonlinear stability, non-Newtonian, thin film

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Authors: Lise Paule Labéjof, Raíza Sales Pereira Bizerra, Galileu Barbosa Costa, Thaísa Barros dos Santos

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Since the beginning of the microscopy, improving the image quality has always been a concern of its users. Especially for transmission electron microscopy (TEM), the problem is even more important due to the complexity of the sample preparation technique and the many variables that can affect the conservation of structures, proper operation of the equipment used and then the quality of the images obtained. Animal tissues being transparent it is necessary to apply a contrast agent in order to identify the elements of their ultrastructural morphology. Several methods of contrastation of tissues for TEM imaging have already been developed. The most used are the “in block” contrastation and “in situ” contrastation. This report presents an alternative technique of application of contrast agent in vivo, i.e. before sampling. By this new method the electromicrographies of the tissue sections have better contrast compared to that in situ and present no artefact of precipitation of contrast agent. Another advantage is that a small amount of contrast is needed to get a good result given that most of them are expensive and extremely toxic.

Keywords: image quality, microscopy research, staining technique, ultra thin section

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Authors: Riya Thomas, Denis Music, Tautgirdas Ruzgas

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The detection of tyrosinase holds considerable interest in the domains of food nutrition and human health due to its significant role in causing a detrimental effect on the colour, flavour, and nutritional value of food as well as in the synthesis of melanin causing skin melanoma. Compared to other conventional analytical techniques, electrochemical (EC) sensors are highly promising owing to their quick response, great sensitivity, ease of use, and low cost. Particularly, titania nanoparticle-based electrochemical sensors have drawn special attention in identifying several biomolecules including enzymes, antibodies, and receptors, owing to their enhanced electrocatalytic activity and electron-accepting properties. In this study, Ti-O film-modified electrode is fabricated using reactive magnetron sputtering, and its affinity towards tyrosinase is examined via electrochemical methods. To comprehend the physiochemical and surface properties-governed electrocatalytic activity of modified electrodes, Ti-O films are grown under various compositional ranges and deposition temperature, and their corresponding electrochemical activity towards tyrosinase is studied. Further, to understand the underlying atomistic mechanisms and electronic-scale electrochemical characteristics, density functional theory (DFT) is employed. The main goal of the current work is to determine the correlation between macroscopic measurements and the underlying atomic properties to improve the tyrosinase activity on Ti-O surfaces. Moreover, this work offers an intriguing new perspective on the use of Ti-O-modified electrodes to detect tyrosinase in the areas of clinical diagnosis, skincare, and food science.

Keywords: density functional theory, electrochemical sensor, Ti-O film, tyrosinase

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Authors: Yang Xiao-Jun, Yu Tian-Hao, Hu Ying-Qi

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Breathing in foreign objects during the operation of the aircraft engine, impurities in the aircraft fuel and products of incomplete combustion can produce deposits on the surface of the turbine blades. These deposits reduce not only the turbine's operating efficiency but also the life of the turbine blades. Based on the small open wind tunnel, the simulation of deposits on the leading edge of the turbine has been carried out in this work. The effect of film cooling on particulate deposition was investigated. Based on the analysis, the adhesive mechanism for the molten pollutants’ reaching to the turbine surface was simulated by matching the Stokes number, TSP (a dimensionless number characterizing particle phase transition) and Biot number of the test facility and that of the real engine. The thickness distribution and growth trend of the deposits have been observed by high power microscope and infrared camera under different temperature of the main flow, the solidification temperature of the particulate objects, and the blowing ratio. The experimental results from the leading edge particulate deposition demonstrate that the thickness of the deposition increases with time until a quasi-stable thickness is reached, showing a striking effect of the blowing ratio on the deposition. Under different blowing ratios, there exists a large difference in the thickness distribution of the deposition, and the deposition is minimal at the specific blow ratio. In addition, the temperature of main flow and the solidification temperature of the particulate have a great influence on the deposition.

Keywords: deposition, experiment, film cooling, leading edge, paraffin particles

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Authors: Nuur Ezaini Akmar Ismail, Norbazilah Rahim, Norul Huda Md Rasdi, Maslina Daud

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A web application is the most targeted by the attacker because the web application is accessible by the end users. It has become more advantageous to the attacker since not all the end users aware of what kind of sensitive data already leaked by them through the Internet especially via social network in shake on ‘sharing’. The attacker can use this information such as personal details, a favourite of artists, a favourite of actors or actress, music, politics, and medical records to customize phishing attack thus trick the user to click on malware-laced attachments. The Phishing attack is one of the most popular attacks for social engineering technique against web applications. There are several methods to detect phishing websites such as Blacklist/Whitelist based detection, heuristic-based, and visual similarity-based detection. This paper illustrated a comparison between the heuristic-based technique using features of a uniform resource locator (URL) and visual similarity-based detection techniques that compares the content of a suspected phishing page with the legitimate one in order to detect new phishing sites based on the paper reviewed from the past few years. The comparison focuses on three indicators which are false positive and negative, accuracy of the method, and time consumed to detect phishing website.

Keywords: heuristic-based technique, phishing detection, social engineering and visual similarity-based technique

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Authors: Kaito Sugane, Mitsuhiro Shibata

Abstract:

Self-healing polymers have attracted attention because their physical damage and cracks can be effectively repaired, thereby extending the lifetime of the materials. Self-healing polymers using host-guest interaction have the advantage that they are quickly repaired under mild temperature conditions when compared with self-healing polymer using dynamic covalent bonds such as Diels-Alder (DA)/retro-DA and disulfide metathesis reactions. Especially, it is known that hydrogels utilizing the host-guest interaction between cyclodextrin and various guest molecules are repeatedly self-repaired at room temperature. However, most of the works deal with hydrogels, and little attention has been paid for thermosetting resins as polyurethane, epoxy and unsaturated polyester resins. In this study, polyetherurethane networks (PUN-CD-Ads) incorporating cyclodextrin and adamantane moieties were prepared by the crosslinking reactions of β-cyclodextrin (CD), 1-adamantanol (AdOH), glycerol ethoxylate (GCE) and hexamethylene diisocyanate (HDI), and thermal, mechanical and self-healing properties of the polymer network films were investigated. Our attention was focused on the influences of molar ratio of CD/AdOH, GCE/CD and OH/NCO on the properties. The FT-IR, and gel fraction analysis revealed that the urethanization reaction smoothly progress to form polyurethane networks. When two cut pieces of the films were contacted at the cross-section at room temperature for 30 seconds, the two pieces adhered to produce a self-healed film. Especially, the PUN-CD-Ad prepared at GCE/CD = 5/1, CD/AdOH = 1/1, and OH/NCO = 1/1 film exhibited the highest healing efficiency for tensile strength. Most of the PUN-CD-Ads were successfully self-healed at room temperature.

Keywords: host-guest interaction, network polymer, polyurethane, self-healing

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Authors: Ki-Ho Nam, Haksoo Han

Abstract:

Tetrapod zinc oxide whiskers (TZnO-Ws) were successfully synthesized by a thermal oxidation method. A series of transparent polyimide (PI)/TZnO-W composites were successfully synthesized via a solution-blending method. The structural and morphological features of TZnO-Ws and PI/TZnO-W composites were characterized by Fourier transform infrared spectroscopy (FT-IR), wide-angle X-Ray diffraction (WAXD), and field emission scanning electron microscope (FE-SEM). Dynamic stress behaviors were investigated in-situ during thermal imidization of the soft-baked PI/TZnO-W composite precursor and thermally cured composite films using a thin film stress analyzer (TFSA) by wafer bending technique. The PI/TZnO-W composite films exhibited an optical transparency greater than 80% at 550 nm (≤ 0.5 wt% TZnO-W content), a low coefficient of thermal expansion (CTE), and enhanced glass transition temperature. However, the thermal decomposition temperature decreased as the TZnO-W content increased. The water diffusion coefficient and water uptake of the PI/TZNO-W composite films were obtained by best fits to a Fickian diffusion model. The water resistance capacity of PI was greatly enhanced and moisture diffusion in the pure PI was retarded by incorporating the TZnO-W. The PI composite films based on TZNO-W resultantly may have potential applications in optoelectronic manufacturing processes as a flexible transparent substrate.

Keywords: polyimide (PI), tetrapod ZnO whisker (TZnO-W), transparent, dynamic stress behavior, water resistance

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Authors: Averalda van Graan, Joelaine Chetty, Malory Links, Agness Mwangwela, Sitilitha Masangwi, Dalitso Chimwala, Shiban Ghosh, Elizabeth Marino-Costello

Abstract:

Food composition data is becoming increasingly important as dealing with food insecurity and malnutrition in its persistent form of under-nutrition is now coupled with increasing over-nutrition and its related ailments in the developing world, of which Malawi is not spared. In the absence of a food composition database (FCDB) inherent to our dietary patterns, efforts were made to develop a country-specific FCDB for nutrition practice, research, and programming. The main objective was to develop a multi-user, country-specific food composition database, and table from existing published and unpublished scientific literature. A multi-phased approach guided by the project framework was employed. Phase 1 comprised a scoping mission to assess the nutrition landscape for compilation activities. Phase 2 involved training of a compiler and data collection from various sources, primarily; institutional libraries, online databases, and food industry nutrient data. Phase 3 subsumed evaluation and compilation of data using FAO and IN FOODS standards and guidelines. Phase 4 concluded the process with quality assurance. 316 Malawian food items categorized into eight food groups for 42 components were captured. The majority were from the baby food group (27%), followed by a staple (22%) and animal (22%) food group. Fats and oils consisted the least number of food items (2%), followed by fruits (6%). Proximate values are well represented; however, the percent missing data is huge for some components, including Se 68%, I 75%, Vitamin A 42%, and lipid profile; saturated fat 53%, mono-saturated fat 59%, poly-saturated fat 59% and cholesterol 56%. A multi-phased approach following the project framework led to the development of the first Malawian FCDB and table. The table reflects inherent Malawian dietary patterns and nutritional concerns. The FCDB can be used by various professionals in nutrition and health. Rising over-nutrition, NCD, and changing diets challenge us for nutrient profiles of processed foods and complete lipid profiles.

Keywords: analytical data, dietary pattern, food composition data, multi-phased approach

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Authors: Vasanth C. Shunmugasamy, Bilal Mansoor

Abstract:

Magnesium alloys are increasingly being considered for structural systems across different industrial sectors, including precision components of biomedical devices, owing to their high specific strength, stiffness and biodegradability. However, Mg alloys exhibit a high corrosion rate that restricts their application as a biomaterial. For safe use as biomaterial, it is essential to control their corrosion rates. Mg alloy corrosion is influenced by several factors, such as grain size, precipitates and texture. In Mg alloys, microgalvanic coupling between the α-Mg matrix and secondary precipitates can exist, which results in an increased corrosion rate. The present research addresses this challenge by engineering the microstructure of a biodegradable Mg–Zn–RE–Zr alloy by friction stir processing (FSP), a severe plastic deformation process. The FSP-processed Mg alloys showed improved corrosion resistance and mechanical properties. FSPed Mg alloy showed refined grains, a strong basal texture and broken and uniformly distributed secondary precipitates in the stir zone. Mg, alloy base material, exposed to In vitro corrosion medium showed micro galvanic coupling between precipitate and matrix, resulting in the unstable passive layer. However, FS processed alloy showed uniform corrosion owing to stable surface film formation. The stable surface film is attributed to refined grains, preferred texture and distribution of precipitates. The research results show promising potential for Mg alloy to be developed as a biomaterial.

Keywords: biomaterials, severe plastic deformation, magnesium alloys, corrosion

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Authors: Young Jae Choung, Seoung Bum Kim

Abstract:

Statistical Process Control (SPC) is a popular technique for process monitoring. A widely used tool in SPC is a control chart, which is used to detect the abnormal status of a process and maintain the controlled status of the process. Traditional control charts, such as Hotelling’s T2 control chart, are effective techniques to detect abnormal observations and monitor processes. However, many complicated manufacturing systems exhibit nonlinearity because of the different demands of the market. In this case, the unregulated use of a traditional linear modeling approach may not be effective. In reality, many industrial processes contain the nonlinear and time-varying properties because of the fluctuation of process raw materials, slowing shift of the set points, aging of the main process components, seasoning effects, and catalyst deactivation. The use of traditional SPC techniques with time-varying data will degrade the performance of the monitoring scheme. To address these issues, in the present study, we propose a parameterless self-organizing map (PLSOM)-based control chart. The PLSOM-based control chart not only can manage a situation where the distribution or parameter of the target observations changes, but also address the nonlinearity of modern manufacturing systems. The control limits of the proposed PLSOM chart are established by estimating the empirical level of significance on the percentile using a bootstrap method. Experimental results with simulated data and actual process data from a thin-film transistor-liquid crystal display process demonstrated the effectiveness and usefulness of the proposed chart.

Keywords: control chart, parameter-less self-organizing map, self-organizing map, time-varying property

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Authors: J. Desbrieres, M. Popa, C. Peptu, S. Bacaita

Abstract:

Because of their favorable properties (non-toxicity, biodegradability, mucoadhesivity etc.), polysaccharides were studied as biomaterials and as pharmaceutical excipients in drug formulations. These formulations may be produced in a wide variety of forms including hydrogels, hydrogel based particles (or capsules), films etc. In these formulations, the polysaccharide based materials are able to provide local delivery of loaded therapeutic agents but their delivery can be rapid and not easily time-controllable due to, particularly, the burst effect. This leads to a loss in drug efficiency and lifetime. To overcome the consequences of burst effect, systems involving liposomes incorporated into polysaccharide hydrogels may appear as a promising material in tissue engineering, regenerative medicine and drug loading systems. Liposomes are spherical self-closed structures, composed of curved lipid bilayers, which enclose part of the surrounding solvent into their structure. The simplicity of production, their biocompatibility, the size and similar composition of cells, the possibility of size adjustment for specific applications, the ability of hydrophilic or/and hydrophobic drug loading make them a revolutionary tool in nanomedicine and biomedical domain. Drug delivery systems were developed as hydrogels containing chitosan or carboxymethylcellulose (CMC) as polysaccharides and gelatin (GEL) as polypeptide, and phosphatidylcholine or phosphatidylcholine/cholesterol liposomes able to accurately control this delivery, without any burst effect. Hydrogels based on CMC were covalently crosslinked using glutaraldehyde, whereas chitosan based hydrogels were double crosslinked (ionically using sodium tripolyphosphate or sodium sulphate and covalently using glutaraldehyde). It has been proven that the liposome integrity is highly protected during the crosslinking procedure for the formation of the film network. Calcein was used as model active matter for delivery experiments. Multi-Lamellar vesicles (MLV) and Small Uni-Lamellar Vesicles (SUV) were prepared and compared. The liposomes are well distributed throughout the whole area of the film, and the vesicle distribution is equivalent (for both types of liposomes evaluated) on the film surface as well as deeper (100 microns) in the film matrix. An obvious decrease of the burst effect was observed in presence of liposomes as well as a uniform increase of calcein release that continues even at large time scales. Liposomes act as an extra barrier for calcein release. Systems containing MLVs release higher amounts of calcein compared to systems containing SUVs, although these liposomes are more stable in the matrix and diffuse with difficulty. This difference comes from the higher quantity of calcein present within the MLV in relation with their size. Modeling of release kinetics curves was performed and the release of hydrophilic drugs may be described by a multi-scale mechanism characterized by four distinct phases, each of them being characterized by a different kinetics model (Higuchi equation, Korsmeyer-Peppas model etc.). Knowledge of such models will be a very interesting tool for designing new formulations for tissue engineering, regenerative medicine and drug delivery systems.

Keywords: controlled and delayed release, hydrogels, liposomes, polysaccharides

Procedia PDF Downloads 220