Search results for: surface modification of fiber

Authors: Sreetama Ghosh, Sundara Ramaprabhu

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Carbon dioxide gas has been a major cause for the worldwide increase in green house effect, which leads to climate change and global warming. So CO₂ capture & sequestration has become an effective way to reduce the concentration of CO₂ in the environment. One such way to capture CO₂ in porous materials is by adsorption process. A potential material in this aspect is porous hexagonal boron nitride or 'white graphene' which is a well-known two-dimensional layered material with very high thermal stability. It had been investigated that the sample with hierarchical pore structure and high specific surface area shows excellent performance in capturing carbon dioxide gas and thereby mitigating the problem of environmental pollution to the certain extent. Besides, the presence of sulfur as well as nitrogen in the sample synergistically helps in the increase in adsorption capacity. In this work, a cost effective single step synthesis of highly porous boron nitride nanosheets doped with sulfur had been demonstrated. Besides, the CO₂ adsorption-desorption studies were carried on using a pressure reduction technique. The studies show that the nanosheets exhibit excellent cyclic stability in storage performance. Thermodynamic studies suggest that the adsorption takes place mainly through physisorption. The studies show that the nanosheets exhibit excellent cyclic stability in storage performance. Further, the surface modification of the highly porous nano sheets carried out by incorporating ionic liquids had further enhanced the capturing capability of CO₂ gas in the nanocomposite, revealing that this particular material has the potential to be an excellent adsorbent of carbon dioxide gas.

Keywords: CO₂ capture, hexagonal boron nitride nanosheets, porous network, sulfur doping

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Authors: Shin-Pin Tseng

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Nowadays, numerous spectral amplitude coding (SAC) fiber-optic code-division-multiple-access (FO-CDMA) techniques were appealing due to their capable of providing moderate security and relieving the effects of multiuser interference (MUI). Nonetheless, the performance of the previous network is degraded due to fixed in-phase cross-correlation (IPCC) value. Based on the above problems, a new SAC FO-CDMA network using partial M-sequence (PMS) code is presented in this study. Because the proposed PMS code is originated from M-sequence code, the system using the PMS code could effectively suppress the effects of MUI. In addition, two-code keying (TCK) scheme can applied in the proposed SAC FO-CDMA network and enhance the whole network performance. According to the consideration of system flexibility, simple optical encoders/decoders (codecs) using fiber Bragg gratings (FBGs) were also developed. First, we constructed a diagram of the SAC FO-CDMA network, including (N/2-1) optical transmitters, (N/2-1) optical receivers, and one N×N star coupler for broadcasting transmitted optical signals to arrive at the input port of each optical receiver. Note that the parameter N for the PMS code was the code length. In addition, the proposed SAC network was using superluminescent diodes (SLDs) as light sources, which then can save a lot of system cost compared with the other FO-CDMA methods. For the design of each optical transmitter, it is composed of an SLD, one optical switch, and two optical encoders according to assigned PMS codewords. On the other hand, each optical receivers includes a 1 × 2 splitter, two optical decoders, and one balanced photodiode for mitigating the effect of MUI. In order to simplify the next analysis, the some assumptions were used. First, the unipolarized SLD has flat power spectral density (PSD). Second, the received optical power at the input port of each optical receiver is the same. Third, all photodiodes in the proposed network have the same electrical properties. Fourth, transmitting '1' and '0' has an equal probability. Subsequently, by taking the factors of phase‐induced intensity noise (PIIN) and thermal noise, the corresponding performance was displayed and compared with the performance of the previous SAC FO-CDMA networks. From the numerical result, it shows that the proposed network improved about 25% performance than that using other codes at BER=10-9. This is because the effect of PIIN was effectively mitigated and the received power was enhanced by two times. As a result, the SAC FO-CDMA network using PMS codes has an opportunity to apply in applications of the next-generation optical network.

Keywords: spectral amplitude coding, SAC, fiber-optic code-division multiple-access, FO-CDMA, partial M-sequence, PMS code, fiber Bragg grating, FBG

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Authors: Michael P. Mannino, Gerald W. Hart

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The majority of glucose metabolism proceeds through glycolytic pathways such as glycolysis or pentose phosphate pathway, however, about 5% is shunted through the hexosamine biosynthetic pathway, producing uridine diphosphate N-acetyl glucosamine (UDP-GlcNAc). This precursor can then be incorporated into complex oligosaccharides decorating the cell surface or remain as an intracellular post-translational-modification (PTM) of serine/threonine residues (O-GlcNAcylation, OGN), which has been identified on over 4,000 cytosolic or nuclear proteins. Intracellular OGN has major implications on cellularprocesses, typically by modulating protein localization, protein-protein interactions, protein degradation, and gene expression. Additionally, OGN is known to have an extensive cross-talk with phosphorylation, be in a competitive or cooperative manner. Unlike other PTMs there are only two cycling enzymes that are capable of adding or removing the GlcNAc moiety, O-linked N-aceytl glucosamine Transferase (OGT) and O-linked N-acetyl glucoamidase (OGA), respectively. The activity of OGT has been shown to be sensitive to cellular UDP-GlcNAc levels, even changing substrate affinity. Owing to this and that the concentration of UDP-GlcNAc is related to the metabolisms of glucose, amino acid, fatty acid, and nucleotides, O-GlcNAc is often referred to as a nutrient sensing rheostat. Indeed OGN is known to regulate several signaling pathways as a result of nutrient levels, such as insulin signaling. Dysregulation of OGN is associated with several disease states such as cancer, diabetes, and neurodegeneration. Improvements in glycomics over the past 10-15 years has significantly increased the OGT substrate pool, suggesting O-GlcNAc’s involvement in a wide variety of signaling pathways. However, O-GlcNAc’s role at the receptor level has only been identified in a case-by-case basis of known pathways. Examining the OGN of the plasma membrane (PM) may better focus our understanding of O-GlcNAc-effected signaling pathways. In this current study, PM fractions were isolated from several cell types via ultracentrifugation, followed by purification and MS/MS analysis in several cell lines. This process was repeated with or without OGT/OGA inhibitors or with increased/decreased glucose levels in media to ascertain the importance of OGN. Various pathways are followed up on in more detailed studies employing methods to localize OGN at the PM specifically.

Keywords: GlcNAc, nutrient sensitive, post-translational-modification, receptor

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Authors: Martin Cvek, Miroslav Mrlik, Michal Sedlacik, Tomas Plachy

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Magnetorheological elastomers (MREs) are multi-phase composite materials containing micron-sized ferromagnetic particles dispersed in an elastomeric matrix. Their properties such as modulus, damping, magneto-striction, and electrical conductivity can be controlled by an external magnetic field and/or pressure. These features of the MREs are used in the development of damping devices, shock attenuators, artificial muscles, sensors or active elements of electric circuits. However, imperfections on the particle/matrix interfaces result in the lower performance of the MREs when compared with theoretical values. Moreover, magnetic particles are susceptible to corrosion agents such as acid rains or sea humidity. Therefore, the modification of particles is an effective tool for the improvement of MRE performance due to enhanced compatibility between particles and matrix as well as improvements of their thermo-oxidation and chemical stability. In this study, the carbonyl iron (CI) particles were controllably modified with poly(trimethylsilyloxyethyl methacrylate) (PHEMATMS) nano-grafts to develop magnetic core–shell structures exhibiting proper wetting with various elastomeric matrices resulting in improved performance within a frame of rheological, magneto-piezoresistance, pressure-piezoresistance, or radio-absorbing properties. The desired molecular weight of PHEMATMS nano-grafts was precisely tailored using surface-initiated atom transfer radical polymerization (ATRP). The CI particles were firstly functionalized using a 3-aminopropyltriethoxysilane agent, followed by esterification reaction with α-bromoisobutyryl bromide. The ATRP was performed in the anisole medium using ethyl α-bromoisobutyrate as a macroinitiator, N, N´, N´´, N´´-pentamethyldiethylenetriamine as a ligand, and copper bromide as an initiator. To explore the effect PHEMATMS molecular weights on final properties, two variants of core-shell structures with different nano-graft lengths were synthesized, while the reaction kinetics were designed through proper reactant feed ratios and polymerization times. The PHEMATMS nano-grafts were characterized by nuclear magnetic resonance and gel permeation chromatography proving information to their monomer conversions, molecular chain lengths, and low polydispersity indexes (1.28 and 1.35) as the results of the executed ATRP. The successful modifications were confirmed via Fourier transform infrared- and energy-dispersive spectroscopies while expected wavenumber outputs and element presences, respectively, of constituted PHEMATMS nano-grafts, were occurring in the spectra. The surface morphology of bare CI and their PHEMATMS-grafted analogues was further studied by scanning electron microscopy, and the thicknesses of grafted polymeric layers were directly observed by transmission electron microscopy. The contact angles as a measure of particle/matrix compatibility were investigated employing the static sessile drop method. The PHEMATMS nano-grafts enhanced compatibility of hydrophilic CI with low-surface-energy hydrophobic polymer matrix in terms of their wettability and dispersibility in an elastomeric matrix. Thus, the presence of possible defects at the particle/matrix interface is reduced, and higher performance of modified MREs is expected.

Keywords: atom transfer radical polymerization, core-shell, particle modification, wettability

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Authors: M.Ayazi, N. Golshan Ebrahimi

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The development of antibacterial surface has devoted extensive researches and important field due to the growing antimicrobial resistance strains. The superhydrophobic surface has raised attention because of reducing bacteria adhesion in the absence of antibiotic agents. Evaluating the current development antibacterial surface has to be investigating to consider the potential of applying superhydrophobic surface to reduce bacterial adhesion or role of patterned surfaces on it. In this study, we present different samples with bio-inspired hierarchical and microstructures to consider their ability in reducing bacterial adhesion. The structures have inspired from rice-like pattern and lotus-leaf that developed on the polydimethylsiloxane (PDMS) and polypropylene (PP). The results of the attachment behaviors have considered on two bacteria strains of gram-negative Escherichia coli (E. coli) bacteria and gram-positive Staphylococcus aureus (S. aureus). The reduction of bacteria adhesion on these roughness surfaces demonstrated the effectiveness of rinsing ability on removing bacterial cells on structured plastic surfaces. Results have also offered the important role of bacterial species, material chemistry and hierarchical structure to prevent bacterial adhesion.

Keywords: hierarchical structure, self-cleaning, lotus-effect, bactericidal

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Authors: Abdallah M. Abdelkawy, Tarek M. El Hossainya, I. El Mahallawib

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Recently, significant achievements have been made in development and manufacturing of nano-dispersed metal matrix nanocomposites (MMNCs). They gain their importance due to their high strength to weight ratio. The machining problems of these new materials are less widely investigated, thus this work focuses on machining of them. Aluminum-Silicon (A356)/ MMNC dispersed with alumina (Al2O3) is important in many applications include engine blocks. The final finish process of this application depends heavily on machining. The most important machining parameter studied includes: cutting force and surface roughness. Experimental trails are performed on the number of special samples of MMNC (with different Al2O3%) where the relation between Al2O3% and cutting speed, feed rate and cutting depth with cutting force and surface roughness were studied. The data obtained were statistically analyzed using Analysis of variance (ANOVA) to define the significant factors on both cutting force and surface roughness and their level of confident. Response Surface Methodology (RSM) is used to build a model relating cutting conditions and Al2O3% to the cutting force and surface roughness. The results have shown that feed and depth of cut have the major contribution on the cutting force and the surface roughness followed by cutting speed and nano-percent in MMNCs.

Keywords: machinability, cutting force, surface roughness, Ra, RSM, ANOVA, MMNCs

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Authors: Narek Margaryan, Zhozef Panosyan

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Due to their unique properties, carbon nanofilms have become the object of general attention and intensive research. In this case it plays a very important role to study surface properties of these films. It is also important to study processes of forming of this films, which is accompanied by a process of self-organization at the nano and micro levels. For more detailed investigation, we examined diamond-like carbon (DLC) layers deposited by chemical vapor deposition (CVD) method on Ge substrate and hydro-generated grapheme layers obtained on surface of colloidal solution using grouping method. In this report surface transformation of these CVD nanolayers is studied by atomic force microscopy (AFM) upon deposition time. Also, it can be successfully used to study surface properties of self-assembled grapheme layers. In turn, it is possible to sketch out their boundary line, which enables one to draw an idea of peculiarities of formation of these layers. Images obtained by AFM are investigated as a mathematical set of numbers and fractal and roughness analysis were done. Fractal dimension, Regne’s fractal coefficient, histogram, Fast Fourier transformation, etc. were obtained. The dependence of fractal parameters on the deposition duration for CVD films and on temperature of solution tribolayers was revealed. As an important surface parameter for our carbon films, surface energy was calculated as function of Regne’s fractal coefficient. Surface potential was also measured with Kelvin probe method using semi-contacting AFM. The dependence of surface potential on the deposition duration for CVD films and on temperature of solution for hydro-generated graphene was found as well. Results obtained by fractal analysis method was related with purly esperimental results for number of samples.

Keywords: nanostructured films, self-assembled grapheme, diamond-like carbon, surface potential, Kelvin probe method, fractal analysis

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Authors: Jeet Vijay Sah, Alphonsa Joseph, Pravin Kumari Dwivedi, Ghanshyam Jhala, Subroto Mukherjee

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AISI 304 is known for its corrosion resistance which comes from Cr that forms passive Cr₂O₃ on the surface. But its poor hardness makes it unsuitable for applications where the steel also requires high wear resistance. This can be improved by surface hardening using nitrocarburizing processes, which form ε-Fe2-3N, γ’-Fe4N, nitrides, and carbides of Cr and Fe on the surface and subsurface. These formed phases give the surface greater hardness, but the corrosion resistance drops because of the lack of Cr2O3 passivation as a result. To overcome this problem, plasma nitrocarburizing processes are being developed where the process temperatures are kept below 723 K to avoid Cr-N precipitation. In the presented work, low-temperature pulsed-DC plasma nitrocarburizing utilizing a discharge of N₂-H₂-C₂H₂ at 500 Pa with varying N₂:H₂ ratios was conducted on AISI 304 samples at 673 K. The process durations were also varied, and the samples were characterized by microindentation using Vicker’s hardness tester, corrosion resistances were established from electrochemical impedance studies, and corrosion potentials and corrosion currents were obtained by potentiodynamic polarization testing. XRD revealed S-phase, which is a supersaturated solid solution of N and C in the γ phase. The S-phase was observed to be composed of the expanded phases of γ; γN, γC, and γ’N and ε’N phases. Significant improvement in surface hardness was achieved after every process, which is attributed to the S-phase. Corrosion resistance was also found to improve after the processes. The samples were also characterized by XPS, SEM, and GDOES.

Keywords: AISI 304, surface engineering, nitrocarburizing, S-phase

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Authors: Okafor E. Ijeoma, Isimi C. Yetunde, Okoh E. Judith, Kunle O. Olobayo, Emeje O. Martins

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Starch has gained interest as a renewable and environmentally compatible polymer due to the increase in its use. However, starch by itself could not be satisfactorily applied in industrial processes due to some inherent disadvantages such as its hydrophilic character, poor mechanical properties, its inability to withstand processing conditions such as extreme temperatures, diverse pH, high shear rate, freeze-thaw variation and dimensional stability. The range of physical properties of parent starch can be enlarged by chemical modification which invariably enhances their use in a number of applications found in industrial processes and food manufacture. In this study, Manihot esculentus starch was subjected to modification by oxidation. Fourier Transmittance Infra- Red (FTIR) and Raman spectroscopies were used to confirm the synthesis while Scanning Electron Microscopy (SEM) and X- Ray Diffraction (XRD) were used to characterize the new polymer. DPPH (2, 2-diphenyl-1-picryl-hydrazyl-hydrate) free radical assay was used to determine the antioxidant property of the oxidized starch. Our results show that the modification had no significant effect on the foaming capacity as well as on the emulsion capacity. Scanning electron microscopy revealed that oxidation did not alter the predominantly circular-shaped starch granules, while the X-ray pattern of both starch, native and modified were similar. FTIR results revealed a new band at 3007 and 3283cm-1. Differential scanning calorimetry returned two new endothermic peaks in the oxidized starch with an improved gelation capacity and increased enthalpy of gelatinization. The IC50 of oxidized starch was notably higher than that of the reference standard, ascorbic acid.

Keywords: antioxidant activity, DPPH, M. esculentus, oxidation, starch

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Authors: Ng Mei Han, Nu'man Abdul Hadi

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Extraction of ferulic acid from palm pressed fiber using deep eutectic solvent (DES) of choline chloride-acetic acid (ChCl-AA) and choline chloride-citric acid (ChCl-CA) are reported. Influence of water content in DES on the extraction efficiency was investigated. ChCl-AA and ChCl-CA experienced a drop in viscosity from 9.678 to 1.429 and 22.658 ± 1.655 mm2/s, respectively as the water content in the DES increased from 0 to 50 wt% which contributed to higher extraction efficiency for the ferulic acid. Between 41,155 ± 940 mg/kg ferulic acid was obtained after 6 h reflux when ChCl-AA with 30 wt% water was used for the extraction compared to 30,940 ± 621 mg/kg when neat ChCl-AA was used. Although viscosity of the DES could be improved with the addition of water, there is a threshold where the DES could tolerate the presence of water without changing its solvent behavior. The optimum condition for extraction of ferulic acid from palm pressed fiber was heating for 6 h with DES containing 30 wt% water.

Keywords: deep eutectic solvent, extraction, ferulic acid, palm fibre

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Authors: Radhiyatul Hikmah Binti Abu, Zukhairi Bin Md Rahim, Siti Ujila Binti Masuri, Nur Ismarrubie Binti Zahari, Mohd Zobir Hussein

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This paper describes the synthesis of Calcium Diethylenetriamine-penta (Ca-DTPMP) Scale Inhibitor (SI) and the effect of temperature on its adsorption onto the mineral surfaces. Nanosized particles of Ca-DTPMP SI were synthesized and TEM result shows that the sizes of the synthesized particles are ranged from 10 nm to 30 nm. This synthesized nano SI was then used in static adsorption/precipitation test with various temperatures (37°C, 60°C and 100°C) to determine the effect of temperature on its adsorption ability. The performance of the SI was measured by their diffusion capability, which can be inferred by weighing the metal-SI that successfully adsorbed onto the kaolinite (mineral) surface. The kaolinite samples were analyzed using Scanning Electron Microscope (SEM) and the results show the reduction of pores on kaolinite surface as temperature increases. This indicates higher adsorption of the SI particles onto the mineral surface. Furthermore, EDX analysis shows the presence of Phosphorus (P) and Magnesium (Mg2+) on kaolinite particle surface, hence reaffirming the fact that adsorption took place on the kaolinite surface.

Keywords: adsorption, diffusivity, scale, scale inhibitor

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Authors: Nurcan Cetinkaya

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The aim of this paper is to bring about the utilization of Juncus acutus as an alternative roughage resource in ruminant nutrition. In Turkey, JA is prevailing plant of the natural grassland in Kizilirmak Delta, Samsun. Crude nutrient values such as crude protein (CP), ether extract (EE), organic matter (OM), neutral detergent fiber (NDF), acid detergent fiber (ADF), and acid detergent lignin(ADL) including antioxidant activity, total phenolic and flavonoid compounds, total organic matter digestibility (OMD) and metabolisable energy (ME) values of Juncus acutus stem, seed, and also its mixture with maize silage were estimated. and published. Furthermore, the effects of JA over rumen cellulolitic bacteria were studied. The obtained results from different studies conducted on JA by our team show that Juncus acutus may be a new roughage source in ruminant nutrition.

Keywords: antioxidant activity, cellulolytic bacteria, Juncus acutus, organic matter digestibility

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Authors: Bradley Fevrier

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Background: Type 2 diabetes mellitus, a non-communicable metabolic disorder, is a fast-growing problem for health, as it presents numerous complications and death worldwide. St. Lucia, much like most other emerging nation in the Caribbean, struggles with the management of type 2 diabetes mellitus (T2DM) among its populace. Good knowledge, attitude, and practices [KAP] of T2DM are essential in the prevention and management of this disease.Lifestyle adaptation, including increased knowledge, positive attitude, and efficient practice towards lifestyle modifications, can avert the advancement of difficulties associated with diabetes. Methods: An institutional-based cross-sectional study was conducted during the period June 15, 2022, to July15 2022. Data were collected by using the self-administered questionnaire designed to collect the required information from participants, and the data wasanalyzed using the statistical package for social science (SPSS) version 26. Knowledge, attitude, and practice of lifestyle modification among participants were determined using descriptive statistics. Results: A total of 402 participants completed the study, fully yielding an 84% response rate. Overall, the assessed levels of KAP relating to the life-threatening complications of T2DM were moderate. Results further indicated that women outnumbered men 68.4% to 31.6%, respectively. Significant positive correlation (r= 0.244, p<0.001) and (r=.203, p<0.001) were found between the knowledge level as well as the attitude level of study respondents. Conclusion: The overall study findings regarding the level of knowledge and attitude concerning lifestyle modifications among study participants were interpreted as generally high. However, the practice of healthy lifestyle modification habits was poor. The current findings suggest a need for structured educational campaigns prioritizing the importance of lifestyle modifications (weight loss, smoking cessation, physical exercise) to the general population.

Keywords: Diabetes, knowledge, lifestyle, survey

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Authors: S. M. A. Al Qawabah, A. I. O. Zaid

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Al-4%Cu alloys are now widely used in many engineering applications especially in robotic, aerospace and vibration control area. The main problem arises from the weakness of their mechanical characteristics. Therefore, this study is directed towards enhancing the mechanical properties through severe plastic deformation. In this work, the hot direct extrusion process was chosen to provide the required hot work for this purpose. A direct extrusion die was designed and manufactured to be used in this investigation. The general microstructure, microhardness, surface roughness, and compression tests were performed on specimens from the produced Al-4%Cu alloy both in the as cast and after extrusion conditions. It was found that a pronounced enhancement in the mechanical characteristics of the produced Al-4%Cu after extrusion was achieved. The microhardness increased by 89.3%, the flow stress was decreased by 10% at 0.2 strain and finally the surface roughness was reduced by 81.6%.

Keywords: aluminum, copper, surface roughness, hot extrusion

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Authors: Pheiroijam Pooja, P. Chinnamuthu

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A novel vertical 1D In2O3/TiO2 nanocolumn (NC) axial heterostructure has been successfully synthesized using Glancing Angle Deposition (GLAD) technique inside E-Beam Evaporator chamber. Field emission scanning electron microscope (FESEM) has been used to evaluate the morphology of the structure grown. The estimated length of In2O3/TiO2 NC is ~250 nm and ~300nm for In2O3 and TiO2 respectively with diameter ~60-90 nm. The surface of the heterostructure is porous in nature which can affect the interfacial wettability properties. The grown structure has been further characterized using X-ray Diffraction (XRD) and UV-Visible absorption measurement. The polycrystalline nature of the sample has been examined using XRD with prominent peaks obtained with phase (101) for anatase TiO2 and (211) for In2O3. Here, 1D axial heterostructure NC thus favors efficient segregation of photo-excited carriers due to their type II band alignment between the constituent materials. Moreover, the 1D nanostructure is known for their large surface area and excellent ionic charge transport property. On exposure to UV light illumination, the surface properties of In2O3/TiO2 NC changes whereby the hydrophobic nature of the heterostructure changes to hydrophilic. As a result, the reversible surface wettability of heterostructure on interaction with UV light can give potential applications as antifogging and self-cleaning surfaces.

Keywords: GLAD, heterostructure, In2O3/TiO2 NC, surface wettability

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Authors: Rashid Farooq, Abdul Razzaq Ghumman, Hashim Nisar Hashmi

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Bridge piers often fail all over the world and the whole structure may be endangered due to scouring phenomena. Scouring has been linked to catastrophic failures that lead into the loss of human lives. Various techniques have been employed to extenuate the scouring process in order to assist the bridge designs. Pier modifications plays vital role to control scouring at the vicinity of the pier. This experimental study aims at monitoring the effectiveness of pier modification and temporal development of scour depth around a bridge pier by providing a collar, a cable or openings under the same flow conditions. Provision of a collar around the octagonal pier reduced more scour depth than that for other two configurations. Providing a collar around the octagonal pier found to be the best in reducing scour. The scour depth in front of pier was found to be 19.5% less than that at the octagonal pier without any modifications. Similarly, the scour depth around the octagonal pier having provision of a cable was less than that at pier with provision of openings. The scour depth around an octagonal pier was also compared with a plain circular pier and found to be 9.1% less.

Keywords: Scour, octagonal pier, collar, cable

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Authors: Chih-Hua Wu, Bang-Fuh Chen, Keryea Soong

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Midges can move on the surface of the water at speeds of approximately 340 body-lengths/s and can move continuously for >90 min. Their wings periodically scull the sea surface to push water backward and thus generate thrust; their other body parts, including their three pairs of legs, touch the water only occasionally. The aim of this study was to investigate the locomotion mechanism of marine midges with a size of 2 mm and living in shallow reefs in Wanliton, southern Taiwan. We assumed that midges generate lift through two mechanisms: by sculling the surface of seawater to leverage the generated tension for thrust and by retracting their wings to generate aerodynamic lift at a suitable angle of attack. We performed computational fluid dynamic simulations to determine the mechanism of midge locomotion above the surface of the water. The simulations indicated that ground effects are essential and that both the midge trunk and wing tips must be very close to the water surface to produce sufficient lift to keep the midge airborne. Furthermore, a high wing-beat frequency is crucial for the midge to produce sufficient lift during wing retraction. Accordingly, ground effects, forward speed, and high wing-beat frequency are major factors influencing the ability of midges to generate sufficient lift and remain airborne above the water surface.

Keywords: ground effect, water locomotion, CFD, aerodynamic lift

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Authors: Somnath Bhattacharyya

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The mobile adsorbed surface charge on hydrophobic surfaces can modify the velocity slip condition as well as create a Marangoni stress at the interface. The functionalized hydrophobic walls of micro/nanopores, e.g., graphene nanochannels, may possess physio-sorbed ions. The lateral mobility of the physisorbed absorbed ions creates a friction force as well as an electric force, leading to a modification in the velocity slip condition at the hydrophobic surface. In addition, the non-uniform distribution of these surface ions creates a surface tension gradient, leading to a Marangoni stress. The impact of the mobile surface charge on streaming potential and electrochemical energy conversion efficiency in a pressure-driven flow of ionized liquid through the nanopore is addressed. Also, enhanced electro-osmotic flow through the hydrophobic nanochannel is also analyzed. The mean-filed electrokinetic model is modified to take into account the short-range non-electrostatic steric interactions and the long-range Coulomb correlations. The steric interaction is modeled by considering the ions as charged hard spheres of finite radius suspended in the electrolyte medium. The electrochemical potential is modified by including the volume exclusion effect, which is modeled based on the BMCSL equation of state. The electrostatic correlation is accounted for in the ionic self-energy. The extremal of the self-energy leads to a fourth-order Poisson equation for the electric field. The ion transport is governed by the modified Nernst-Planck equation, which includes the ion steric interactions; born force arises due to the spatial variation of the dielectric permittivity and the dielectrophoretic force on the hydrated ions. This ion transport equation is coupled with the Navier-Stokes equation describing the flow of the ionized fluid and the 3fourth-order Poisson equation for the electric field. We numerically solve the coupled set of nonlinear governing equations along with the prescribed boundary conditions by adopting a control volume approach over a staggered grid arrangement. In the staggered grid arrangements, velocity components are stored on the midpoint of the cell faces to which they are normal, whereas the remaining scalar variables are stored at the center of each cell. The convection and electromigration terms are discretized at each interface of the control volumes using the total variation diminishing (TVD) approach to capture the strong convection resulting from the highly enhanced fluid flow due to the modified model. In order to link pressure to the continuity equation, we adopt a pressure correction-based iterative SIMPLE (Semi-Implicit Method for Pressure-Linked Equations) algorithm, in which the discretized continuity equation is converted to a Poisson equation involving pressure correction terms. Our results show that the physisorbed ions on a hydrophobic surface create an enhanced slip velocity when streaming potential, which enhances the convection current. However, the electroosmotic flow attenuates due to the mobile surface ions.

Keywords: microfluidics, electroosmosis, streaming potential, electrostatic correlation, finite sized ions

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Authors: Said M. AL-Mashaikhi, El-Said I. El-Shafey, Fakhreldin O. Suliman, Saleh Al-Busafi

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Activated carbon (AC) was prepared from date palm leaflets via NaOH activation. AC was oxidized using nitric acid, producing oxidized activated carbon (OAC). OAC was surface functionalized using different amine surfactants, including methylamine (ONM), ethylamine (ONE), and diethylamine (ONDE) using the amide coupling process. Produced carbons were surface characterized for surface area and porosity, X-ray diffraction, SEM, FTIR, and TGA. AC surface area (580 m²/g) has shown a decrease in oxidation to 260 m²/g for OAC. On amine functionalization, the surface area has further decreased to 218, 108, and 20 m²/g on functionalization with methylamine, ethylamine, and diethylamine, respectively. FTIR and TGA showed that the nature of amine functionalization of AC is chemical. Methylene blue sorption was tested on these carbons in terms of kinetics and equilibrium. Sorption was found faster on amine-functionalized carbons than both AC and OAC, and this is due to hydrophobic interaction with the alkyl groups immobilized with data following pseudo second-order reaction. On the other hand, AC showed the slowest adsorption kinetic process due to the diffusion in the porous structure of AC. Sorption equilibrium data was found to follow the Langmuir sorption isotherm with maximum sorption found on ONE. Regardless of its lower surface area than activated carbon, ethylamine functionalized AC showed better performance than AC in terms of kinetics and equilibrium for dye removal.

Keywords: activated carbon, dye removal, functionalization, hydrophobic interaction, water treatment

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Authors: Wei Chen

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3D concrete printing technology is a novel and highly efficient construction method that holds significant promise for advancing low-carbon initiatives within the construction industry. In contrast to traditional construction practices, 3D printing offers a manual and formwork-free approach, resulting in a transformative shift in labor requirements and fabrication techniques. This transition yields substantial reductions in carbon emissions during the construction phase, as well as decreased on-site waste generation. Furthermore, when compared to conventionally printed concrete, 3D concrete exhibits mechanical anisotropy due to its layer-by-layer construction methodology. Therefore, it becomes imperative to investigate the influence of the printing process on the mechanical properties of 3D printed strips and to optimize the mechanical characteristics of these coagulated strips. In this study, we conducted three-dimensional reconstructions of printed blocks using both circular and directional print heads, incorporating various overlap distances between strips, and employed CT scanning for comprehensive analysis. Our research focused on assessing mechanical properties and micro-pore characteristics under different loading orientations.Our findings reveal that increasing the overlap degree between strips leads to enhanced mechanical properties of the strips. However, it's noteworthy that once full overlap is achieved, further increases in the degree of coincidence do not lead to a decrease in porosity between strips. Additionally, due to its superior printing cross-sectional area, the square printing head exhibited the most favorable impact on mechanical properties.This paper aims to improve the tensile strength, tensile ductility, and bending toughness of a recently developed ‘one-part’ geopolymer for 3D concrete printing (3DCP) applications, in order to address the insufficient tensile strength and brittle fracture characteristics of geopolymer materials in 3D printing scenarios where materials are subjected to tensile stress. The effects of steel fiber content, and aspect ratio, on mechanical properties, were systematically discussed, including compressive strength, flexure strength, splitting tensile strength, uniaxial tensile strength, bending toughness, and the anisotropy of 3DP-OPGFRC, respectively. The fiber distribution in the printed samples was obtained through x-ray computed tomography (X-CT) testing. In addition, the underlying mechanisms were discussed to provide a deep understanding of the role steel fiber played in the reinforcement. The experimental results showed that the flexural strength increased by 282% to 26.1MP, and the compressive strength also reached 104.5Mpa. A high tensile ductility, appreciable bending toughness, and strain-hardening behavior can be achieved with steel fiber incorporation. In addition, it has an advantage over the OPC-based steel fiber-reinforced 3D printing materials given in the existing literature (flexural strength 15 Mpa); It is also superior to the tensile strength (<6Mpa) of current geopolymer fiber reinforcements used for 3D printing. It is anticipated that the development of this 3D printable steel fiber reinforced ‘one-part’ geopolymer will be used to meet high tensile strength requirements for printing scenarios.

Keywords: 3D printing concrete, mechanical anisotropy, micro-pore structure, printing technology

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Authors: Nisrin R. Abdelal, Steven L. Donaldson

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Composite materials are widely used in aviation industry due to their superior properties; however, they are susceptible to delamination. Through-thickness stitching is one of the techniques to alleviate delamination. Kevlar is one of the most common stitching materials; in contrast, it is expensive and presents stitching fabrication challenges. Therefore, this study compares the performance of Kevlar with an inexpensive and easy-to-use nylon fiber in stitching to alleviate delamination. Three laminates of unidirectional carbon fiber-epoxy composites were manufactured using vacuum assisted resin transfer molding process. One panel was stitched with Kevlar, one with nylon, and one unstitched. Mode I interlaminar fracture tests were carried out on specimens from the three composite laminates, and the results were compared. Fractographic analysis using optical and scanning electron microscope were conducted to reveal the differences between stitching with Kevlar and nylon on the internal microstructure of the composite with respect to the interlaminar fracture toughness values.

Keywords: carbon, delamination, Kevlar, mode I, nylon, stitching

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Authors: Yeng Min Yi, Rosli Md Illias, Salehhuddin Hamdan

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Industrial biocatalysis is mainly based on the use of cell free or intracellular enzyme systems. However, the expensive cost and relatively lower operational stability of free enzymes limit practical use in industries. Cell surface display system can be used as a cost-efficient alternative to overcome the laborious purification and substrate transport limitation. In this research, TibA autotransporter from E. coli was used to display Aspergillus fumigatus xylanase (xyn). The amplified xyn was fused in between N-terminal signal peptide and C-terminal β-barrel of TibA. The cloned was transformed and expressed in E. coli BL21 (DE3). Outer membrane localization of TibA-xyn fusion protein was confirmed by SDS PAGE and western blot with expected size of 62.5 kDa. Functional display of xyn was examined by activity assay. Cell surface displayed xyn exhibited the highest activity at 37 °c, 0.3 mM IPTG. As a summary, TibA displaying system has the potential for further industrial applications. Moreover, this is the first report of the display of xylanase using TibA on the surface of E. coli.

Keywords: biocatalysis, cell surface display, Escherichia coli, TibA autotransporter

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Authors: Suman Kumar Adhikary, Zymantus Rudzionis, Arvind Balakrishnan

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This paper deals with the behavior of concrete’s workability in a fresh state and compressive and flexural strength in a hardened state with the addition of polyolefin macro fibers. Four different amounts (3kg/m3, 4.5kg/m3, 6kg/m3 and 9kg/m3) of polyolefin macro fibers mixed in concrete mixture to observe the workability and strength properties difference between the concrete specimens. 20% class C type fly ash added is the concrete as replacement of cement. The water-cement ratio(W/C) of those concrete mix was 0.35. Masterglenium SKY 700 superplasticizer was added to the concrete mixture for better results. Slump test was carried out for determining the flowability. On 7th, 14th and 28th day of curing process compression strength tests were done and on 28th day flexural strength test and CMOD test were carried to differentiate the strength properties and post-cracking behavior of concrete samples.

Keywords: self-compacting concrete, polyolefin fibers, fiber reinforced concrete, CMOD test of concrete

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Authors: Erwan Negre, Ewan J. O'Connor, Juha Toivonen

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The need for CO2 monitoring technologies grows simultaneously with the worldwide concerns regarding environmental challenges. To that purpose, we developed a compact coherent all-fiber ranged-resolved Differential Absorption Lidar (RR-DIAL). It has been designed along a tunable 2x1fiber optic switch set to a frequency of 1 Hz between two Distributed FeedBack (DFB) lasers emitting in the continuous-wave mode at 1571.41 nm (absorption line of CO2) and 1571.25 nm (CO2 absorption-free line), with linewidth and tuning range of respectively 1 MHz and 3 nm over operating wavelength. A three stages amplification through Erbium and Erbium-Ytterbium doped fibers coupled to a Radio Frequency (RF) driven Acousto-Optic Modulator (AOM) generates 100 ns pulses at a repetition rate from 10 to 30 kHz with a peak power up to 2.5 kW and a spatial resolution of 15 m, allowing fast and highly resolved CO2 profiles. The same afocal collection system is used for the output of the laser source and the backscattered light which is then directed to a circulator before being mixed with the local oscillator for heterodyne detection. Packaged in an easily transportable box which also includes a server and a Field Programmable Gate Array (FPGA) card for on-line data processing and storing, our setup allows an effective and quick deployment for versatile in-situ analysis, whether it be vertical atmospheric monitoring, large field mapping or sequestration site continuous oversight. Setup operation and results from initial field measurements will be discussed.

Keywords: CO2 profiles, coherent DIAL, in-situ atmospheric sensing, near infrared fiber source

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Authors: S. Dey, P. Sibanda, S. Gupta, A. Chakraborty

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The occurrence of high nocturnal surface ozone over a tropical urban area (23̊ 32′16.99″ N and 87̊ 17′ 38.95″ E) is analyzed in this paper. Five incidences of nocturnal ozone maxima are recorded during the observational span of two years (June, 2013 to May, 2015). The maximum and minimum values of the surface ozone during these five occasions are 337.630 μg/m³ and 13.034 μg/m³ respectively. HYSPLIT backward trajectory analyses and wind rose diagrams support the horizontal transport of ozone from distant polluted places. Planetary boundary layer characteristics, concentration of precursor (NO₂) and meteorology are found to play important role in the horizontal and vertical transport of surface ozone during nighttime.

Keywords: nocturnal ozone, planetary boundary layer, horizontal transport, meteorology, urban area

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Authors: L. Szymanski, Z. Kolacinski, Z. Kamiński, G. Raniszewski, J. Fraczyk, L. Pietrzak

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In the article the development and demonstration of method and the model device for hyperthermic selective destruction of cancer cells are presented. This method was based on the synthesis and functionalization of carbon nanotubes serving as ferromagnetic material nano containers. Methodology of the production carbon - ferromagnetic nanocontainers includes: the synthesis of carbon nanotubes, chemical and physical characterization, increasing the content of ferromagnetic material and biochemical functionalization involving the attachment of the key addresses. Biochemical functionalization of ferromagnetic nanocontainers is necessary in order to increase the binding selectively with receptors presented on the surface of tumour cells. Multi-step modification procedure was finally used to attach folic acid on the surface of ferromagnetic nanocontainers. Folic acid is ligand of folate receptors which is overexpresion in tumor cells. The presence of ligand should ensure the specificity of the interaction between ferromagnetic nanocontainers and tumor cells. The chemical functionalization contains several step: oxidation reaction, transformation of carboxyl groups into more reactive ester or amide groups, incorporation of spacer molecule (linker), attaching folic acid. Activation of carboxylic groups was prepared with triazine coupling reagent (preparation of superactive ester attached on the nanocontainers). The spacer molecules were designed and synthesized. In order to ensure biocompatibillity of linkers they were built from amino acids or peptides. Spacer molecules were synthesized using the SPPS method. Synthesis was performed on 2-Chlorotrityl resin. The linker important feature is its length. Due to that fact synthesis of peptide linkers containing from 2 to 4 -Ala- residues was carried out. Independent synthesis of the conjugate of foilic acid with 6-aminocaproic acid was made. Final step of synthesis was connecting conjugat with spacer molecules and attaching it on the ferromagnetic nanocontainer surface. This article contains also information about special CVD and microvave plasma system to produce nanotubes and ferromagnetic nanocontainers. The first tests in the device for hyperthermal RF generator will be presented. The frequency of RF generator was in the ranges from 10 to 14Mhz and from 265 to 621kHz.

Keywords: synthesis of carbon nanotubes, hyperthermia, ligands, carbon nanotubes

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Authors: Guram Adamashvili

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Surface plasmon polariton is a surface optical wave which undergoes a strong enhancement and spatial confinement of its wave amplitude near an interface of two-dimensional layered structures. Phosphorene (single-layer black phosphorus) and other two-dimensional anisotropic phosphorene-like materials are recognized as promising materials for potential future applications of surface plasmon polariton. A theory of an optical breather of self-induced transparency for surface plasmon polariton propagating in monolayer or few-layer phosphorene is developed. A theory of an optical soliton of self-induced transparency for surface plasmon polariton propagating in monolayer or few-layer phosphorene have been investigated earlier Starting from the optical nonlinear wave equation for surface TM-modes interacting with a two-dimensional layer of atomic systems or semiconductor quantum dots and a phosphorene monolayer (or other two-dimensional anisotropic material), we have obtained the evolution equations for the electric field of the breather. In this case, one finds that the evolution of these pulses become described by the damped Bloch-Maxwell equations. For surface plasmon polariton fields, breathers are found to occur. Explicit relations of the dependence of breathers on the local media, phosphorene anisotropic conductivity, transition layer properties and transverse structures of the SPP, are obtained and will be given. It is shown that the phosphorene conductivity reduces exponentially the amplitude of the surface breather of SIT in the process of propagation. The direction of propagation corresponding to the maximum and minimum damping of the amplitude are assigned along the armchair and zigzag directions of black phosphorus nano-film, respectively. The most rapid damping of the intensity occurs when the polarization of breather is along the armchair direction.

Keywords: breathers, nonlinear waves, solitons, surface plasmon polaritons

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Authors: Hamed Khosravi, Reza Eslami-Farsani

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Increased interest in lightweight and efficient structural components has created the need for selecting materials with improved mechanical properties. To do so, composite materials are being widely used in many applications, due to durability, high strength and modulus, and low weight. Among the various composite structures, grid-stiffened structures are extensively considered in various aerospace and aircraft applications, because of higher specific strength and stiffness, higher impact resistance, superior load-bearing capacity, easy to repair, and excellent energy absorption capability. Although there are a good number of publications on the design aspects and fabrication of grid structures, little systematic work has been reported on their material modification to improve their properties, to our knowledge. Therefore, the aim of this research is to study the reinforcing effect of silica nanoparticles on the flexural properties of epoxy/E-glass isogrid panels under three-point bending test. Samples containing 0, 1, 3, and 5 wt.% of the silica nanoparticles, with 44 and 48 vol.% of the glass fibers in the ribs and skin components respectively, were fabricated by using a manual filament winding method. Ultrasonic and mechanical routes were employed to disperse the nanoparticles within the epoxy resin. To fabricate the ribs, the unidirectional fiber rovings were impregnated with the matrix mixture (epoxy + nanoparticles) and then laid up into the grooves of a silicone mold layer-by-layer. At once, four plies of woven fabrics, after impregnating into the same matrix mixture, were layered on the top of the ribs to produce the skin part. In order to conduct the ultimate curing and to achieve the maximum strength, the samples were tested after 7 days of holding at room temperature. According to load-displacement graphs, the bellow trend was observed for all of the samples when loaded from the skin side; following an initial linear region and reaching a load peak, the curve was abruptly dropped and then showed a typical absorbed energy region. It would be worth mentioning that in these structures, a considerable energy absorption was observed after the primary failure related to the load peak. The results showed that the flexural properties of the nanocomposite samples were always higher than those of the nanoparticle-free sample. The maximum enhancement in flexural maximum load and energy absorption was found to be for the incorporation of 3 wt.% of the nanoparticles. Furthermore, the flexural stiffness was continually increased by increasing the silica loading. In conclusion, this study suggested that the addition of nanoparticles is a promising method to improve the flexural properties of grid-stiffened fibrous composite structures.

Keywords: grid-stiffened composite structures, nanocomposite, three point flexural test , energy absorption

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Authors: Andrzej Szewczak

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Study of the effect of high temperatures on polymer coatings represents an important field of research of their properties. Polymers, as materials with numerous features (chemical resistance, ease of processing and recycling, corrosion resistance, low density and weight) are currently the most widely used modern building materials, among others in the resin concrete, plastic parts, and hydrophobic coatings. Unfortunately, the polymers have also disadvantages, one of which decides about their usage - low resistance to high temperatures and brittleness. This applies in particular thin and flexible polymeric coatings applied to other materials, such a steel and concrete, which degrade under varying thermal conditions. Research about improvement of this state includes methods of modification of the polymer composition, structure, conditioning conditions, and the polymerization reaction. At present, ways are sought to reflect the actual environmental conditions, in which the coating will be operating after it has been applied to other material. These studies are difficult because of the need for adopting a proper model of the polymer operation and the determination of phenomena occurring at the time of temperature fluctuations. For this reason, alternative methods are being developed, taking into account the rapid modeling and the simulation of the actual operating conditions of polymeric coating’s materials in real conditions. The nature of a duration is typical for the temperature influence in the environment. Studies typically involve the measurement of variation one or more physical and mechanical properties of such coating in time. Based on these results it is possible to determine the effects of temperature loading and develop methods affecting in the improvement of coatings’ properties. This paper contains a description of the stability studies of silicone coatings deposited on the surface of a ceramic brick. The brick’s surface was hydrophobized by two types of inorganic polymers: nano-polymer preparation based on dialkyl siloxanes (Series 1 - 5) and an aqueous solution of the silicon (series 6 - 10). In order to enhance the stability of the film formed on the brick’s surface and immunize it to variable temperature and humidity loading, the nano silica was added to the polymer. The right combination of the polymer liquid phase and the solid phase of nano silica was obtained by disintegration of the mixture by the sonification. The changes of viscosity and surface tension of polymers were defined, which are the basic rheological parameters affecting the state and the durability of the polymer coating. The coatings created on the brick’s surfaces were then subjected to a temperature loading of 100° C and moisture by total immersion in water, in order to determine any water absorption changes caused by damages and the degradation of the polymer film. The effect of moisture and temperature was determined by measurement (at specified number of cycles) of changes in the surface hardness (using a Vickers’ method) and the absorption of individual samples. As a result, on the basis of the obtained results, the degradation process of polymer coatings related to their durability changes in time was determined.

Keywords: silicones, siloxanes, surface hardness, temperature, water absorption

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Authors: S. A. Kondratyev, O. I. Ibragimova

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The authors discuss the collecting abilities of desorbable species (DS) of saturated fatty acids. The DS species of the reagent are understood as species capable of moving from the surface of the mineral particle to the bubble at the moment of the rupture of the interlayer of liquid separating these objects of interaction. DS species of carboxylic acids (molecules and ionic-molecular complexes) have the ability to spread over the surface of the bubble. The rate of their spreading at pH 7 and 10 over the water surface is determined. The collectibility criterion of saturated fatty acids is proposed. The values of forces exerted by the spreading DS species of reagents on liquid in the interlayer and the liquid flow rate from the interlayer are determined.

Keywords: criterion of action of physically adsorbed reagent, flotation, saturated fatty acids, surface pressure

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