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Recent development of natural fibre for nanocellulose extraction and application
No full textNatural fibers garnered fame amongst researchers and scientists due to their potential as an alternative material in countless sectors, including automotive, packaging, construction, and medicine. This work began with the classification of natural fibers and an overview of their chemical compositions. Then, the retting process, which is a process separating the fiber from the woody core, was discussed. The latest technology has attracted researchers’ attention in the alteration of natural fibers to form nanostructures. Hence, this paper will also discuss the extraction method for nanocellulose. Following that, the methods for the preparation of these cellulose nanofibers, which are nanocrystalline cellulose (CNC), nano-fibrillated cellulose (CNF), and bacterial nanocellulose (BNC), are summarized. Finally, the application of this nanomaterial in advanced applications was explored, and a way forward of this nanocellulose technology was also scrutinized
Removal of aspirin from aqueous solution using phosphoric acid modified coffee waste adsorbent
No full textRemoval of pharmaceutical waste, aspirin (ASA) in an aqueous solution was investigated using activated carbon derived from coffee waste (CW). Activated carbon was prepared by using phosphoric acid as a chemical activating agent. Fourier Transform Infrared Spectroscopy (FTIR) was used to characterize the functional groups on the surface of the adsorbents. The BET technique measured the surface area of the adsorbent. The activated carbon derived from coffee waste modified by H3PO4 (AC-HCW) was observed to have a larger surface area than AC-CW. The states of the adsorption operations are controlled by the effect of initial ASA concentration, adsorbent dose, contact time, temperature, and pH adjacent to the adsorption procedure. In the batch adsorption test, the highest removal efficiency found was 98.02% in 30 min and 95% in 60 min when used AC-HCW and AC-CW, respectively. The optimum conditions for removing aspirin from aqueous solution were 1000 mg/L of initial concentration ASA, pH 4 and a temperature of 30 °C and 0.5 g of AC-HCW and 0.6 g AC-CW adsorbents. The experimental data for adsorption of aspirin were well fitted into the Langmuir isotherm model and obeyed the pseudo-second-order kinetics model. The adsorption of aspirin onto AC-HCW and AC-CW was exothermic, with enthalpy change ΔH°= −0.182 kJ/mol and −0.216 kJ/mol, ΔS° was 0.072 J/mol −0.004 J/mol, which indicates a decrease in randomness at the adsorbent surface/aspirin solution interface, respectively. In addition, a negative Gibbs free energy ΔG° was obtained, indicating the feasibility and spontaneity of the adsorption process. For this study, the coffee waste modified by H3PO4 is considered a promising adsorbent, and It could be employed as a low-cost alternative to commercial activated carbon in removing aspirin in aqueous solutions
Removals of atenolol, gliclazide and prazosin using sequencing batch reactor
Get PDFEmergence of organic micropollutants, specifically pharmaceutical compounds (PhCs) in receiving water bodies possess a great threat towards our ecosystem presently and in future. By that, evaluating and monitoring the removal of PhCs, specifically those highly consumed in a certain area, is considerably critical in attempt to minimize discharge of PhCs in our waters. Therefore, this study assessed the removal mechanisms of three highly consumed PhCs in Malaysia, namely atenolol, gliclazide and prazosin, by considering the hydrolysis, adsorption and biodegradation mechanisms of the selected compounds. Moreover, the removal of these compounds was demonstrated in an aerobic sequencing batch reactor (SBR) system treating actual domestic wastewater added with the selected compounds. The detection of PhCs was conducted using using Ultra-High Performance Liquid Chromatography Quadrupole-Time-Of-Flight Mass Spectrometry (UHPLC/QTOF-MS), followed by investigation of microbial community in the sludge sample by next generation sequencing (NGS). The results highlighted that atenolol was highly biodegradable with 83% efficiency in SBR system. Meanwhile, both gliclazide and prazosin show moderate biodegradation efficiency at 41%. The results also demonstrated that gliclazide and prazosin exhibited recalcitrant behavior towards the biological treatment. In addition, prazosin was presumed to be hydrolyzed and exist as different chemical structure in the aqueous phase during treatment process. The microbial community analysis revealed Mycobacterium as one of the potential microbes in biodegradation of PhCs
Assessment of heart rate variability response in children with autism spectrum disorder using machine learning
No full textAutism spectrum disorder (ASD) is a developmental disability that involves persistent challenges in social interaction, communication and behaviour. The purpose of this study is to apply a machine learning approach to differentiate between autistic and normal children and to evaluate the performance of different classifiers in the detection of autism disorder. Heart Rate Variability (HRV) analysis is one of the strategies used for ASD detection by assessing the autonomic nervous system (ANS), which serves as a biomarker for the autism phenotype. HRV can be derived from the photoplethysmogram (PPG). Logistic Regression, Linear Discriminant Analysis and a Cubic Support Vector Machine (SVM) were chosen to evaluate the performance of HRV features in differentiating between normal and autistic children. Three different combinations of features were selected out of 19 features in total. From the results, Logistic Regression was the best classifier to differentiate between autistic and normal children in a colour stimulus test with 100% accuracy, while Linear Discriminant Analysis was best suited in the baseline test with 90% accuracy. In conclusion, the machine learning approach could be an alternative method of making an early diagnosis of ASD in the near future
Biochemical and physical characterization of immobilized Candida rugosa lipase on metal oxide hybrid support
Get PDFEnzyme immobilization on inorganic materials is gaining more attention with the potential characteristics of high-surface-area-to-volume ratios, increasing the efficiency of enzyme loading on the support. Metal oxide hybrid support was prepared by a wetness impregnation of five metal precursors, including CaO, CuO, MgO, NiO, and ZnO, on Al2O3 and used as a support for the immobilization of Candida rugosa lipase (CRL) by adsorption. Maximum activity recovery (70.6%) and immobilization efficiency (63.2%) were obtained after optimization of five parameters using response surface methodology (RSM) by Box–Behnken design (BBD). The biochemical properties of immobilized CRL showed high thermostability up to 70 °C and a wide range in pH stability (pH 4–10). TGA-DTA and FTIR analysis were conducted, verifying thermo-decomposition of lipase and the presence of an amide bond. FESEM-EDX showed the homogeneous distribution and high dispersion of magnesium and CRL on MgO-Al2O3, while a nitrogen adsorption–desorption study confirmed MgO-Al2O3 as a mesoporous material. CRL/MgO-Al2O3 can be reused for up to 12 cycles and it demonstrated high tolerance in solvents (ethanol, isopropanol, methanol, and tert-butanol) compared to free CRL
Physical properties of cullet-clay glass ceramic containing titanium nitride
No full textRecycle glass as a major component in ceramic fabrication has received tremendous attention due to multi advantages as a starting material. A series of glass ceramics based on recycled glass cullet-kaolin clay containing titanium nitride has successfully been made. The X-ray diffraction technique has been used to characterized the ceramic. Meanwhile, the physical properties such as density have been determined using the Archimedes Principle and their mechanical characteristic such as Vickers hardness and Young's Modulus has been determined in a usual manner. It is found that the ceramic is characterized by the occurrence of major crystalline peaks of Quartz and Tridymite while alumina and titania coexist as the minor phases. The density is observed to vary depending upon the cullet content while the hardness and elasticity are very much dependent on the concentration of titanium nitride. The SEM image indicates that for higher TiN content, the pores on the microstructural surface seem to be dispersed thus producing a smoother surface
Convolutional neural network model based on 2d fingerprint for bioactivity prediction
Get PDFDetermining and modeling the possible behaviour and actions of molecules requires investigating the basic structural features and physicochemical properties that determine their behaviour during chemical, physical, biological, and environmental processes. Computational approaches such as machine learning methods are alternatives to predicting the physiochemical properties of molecules based on their structures. However, the limited accuracy and high error rates of such predictions restrict their use. In this paper, a novel technique based on a deep learning convolutional neural network (CNN) for the prediction of chemical compounds’ bioactivity is proposed and developed. The molecules are represented in the new matrix format Mol2mat, a molecular matrix representation adapted from the well-known 2D-fingerprint descriptors. To evaluate the performance of the proposed methods, a series of experiments were conducted using two standard datasets, namely the MDL Drug Data Report (MDDR) and Sutherland, datasets comprising 10 homogeneous and 14 heterogeneous activity classes. After analysing the eight fingerprints, all the probable combinations were investigated using the five best descriptors. The results showed that a combination of three fingerprints, ECFP4, EPFP4, and ECFC4, along with a CNN activity prediction process, achieved the highest performance of 98% AUC when compared to the state-of-the-art ML algorithms NaiveB, LSVM, and RBFN
LCL-filter design and analysis for PWM recuperating system used in DC traction power substation
Get PDFVoltage source inverter (VSI) had been used in dc traction power substation to deliver the trains braking energy back to the utility grid. To mitigate low order harmonics components, pulse-width-modulation (PWM) technique is commonly used in VSI controlled. As a result, the ac voltage and current waveforms may contain high frequency ripples. This paper proposes to mitigate the high frequency harmonics using LCL-filter with series R-damper. This filter offers good attenuation on harmonics with smaller size compare to other passive filter topologies. Theoretical analysis and simulation verification are conducted in designing the proposed filter. System level simulation had also been carried out. Sinusoidal grid current and voltage waveforms are recorded (THD<2%). This paper also includes damping losses analysis in conjunction with resonance peak suppression in designing the R-damper
Circularly polarized and reconfigurable frequency selective surface based transmit array antenna for x-band applications
Get PDFTransmitarray (TA) antennas have attracted much attention in recent years due to their number of applications. These include the 5G/6G mobile networks and satellite communication systems for the microwave frequency range. The various satellite applications require high-gain antennas with polarization agility. Also, the state-ofthe- art smart communication systems require reconfigurable antennas allowing the frequency and beam switching according to the application requirements. In this research, three different TA antennas have been studied and designed for X-band applications which are high gain and wideband TA antenna, circularly polarized TA antenna, frequency and beam reconfigurable TA antenna. For the first design, two Frequency-Selective Surface (FSS) unit cells which include Double Square Ring with Center Patch (DSR-CP) and Split Ring Resonator (SRR), have been applied to increase the antenna gain and bandwidth. The optimized unit cell structure shows that a fourlayer configuration could provide maximum phase range with low insertion losses. The complete DSR-CP TA consisting of 121 elements has produced an impedance bandwidth of 33.3% with a peak gain value of 20.4 dBi and 1-dB gain for bandwidth of 10%. SRR-based TA achieved the impedance bandwidth of 35% with a peak gain value of 21.9 dBi and 11.6% 1-dB gain bandwidth. A circularly polarized TA using a Meander Line Polarizer (MLP) superstrate has been studied and presented. The MLP unit cell was simulated and optimized at 12 GHz, having 900 phase difference between the two orthogonal E-field components, Ex and Ey. The final prototype measurement results show that a low axial ratio of 1.89 and 20.17 dBi gain at 11.2 GHz has been obtained. Finally, the last part of the research focused on the frequency and beam reconfigurable TA antenna. A U-shape superstrate layer has been added to introduce frequency selectivity in front of the horn antenna that acts as a bandpass filter. Then, by varying the strip length of the U-shape unit cell, the antenna frequency can be reconfigured from 8.5 GHz to 11.2 GHz. On the other hand, a new active TA unit cell equipped with four switchable strips using Positive Intrinsic Negative (PIN) diodes has been employed to achieve beam reconfigurable TA antenna. Thus, the antenna beam can be tilted by controlling the PIN diodes ON and OFF switching states. Results show that a full-beam switching range of 43.20 has been obtained. In conclusion, this research has successfully presented three new TA antenna designs, which are highly potential for the X-band applications
Synthesis, characterization and catalytic activity of copper thiosemicarbazone complexes and their oxides in the reduction of nitroaromatic compounds
Get PDFThis study involves the synthesis, characterization and evaluation of the catalytic activity of copper thiosemicarbazone complexes and their copper oxides derivatives in the reduction of nitroaromatic compounds. A series of copper complexes of thiosemicarbazone ligands have successfully been synthesized, in which six of them are copper(I) complexes; 2- acetylpyridine-N(4)-(R)-thiosemicarbazone-tris- (triphenylphosphine)copper(I) nitrate {R = methoxyphenyl (19), R = methylphenyl (20), R = phenyl (21) and pyrrole-2-carboxaldehyde- N(4)-(R)-thiosemicarbazonebis( triphenylphosphine)copper(I) nitrate {where R = phenyl (22), R= methoxyphenyl (23), R = methylphenyl (24)} and another six copper(II) complexes; 2- acetylpyridine- N(4)-(R)-thiosemicarbazone-triphenylphosphine-copper(II) chloride; {R = methoxyphenyl (25), R = methylphenyl (26), R = phenyl (27)} and pyrrole-2- carboxaldehyde- N(4)-(R)-thiosemicarbazone-triphenylphosphine-copper(II) chloride (R = phenyl (28), R = methoxyphenyl (29), R = methylphenyl (30)}. These complexes were characterized using Fourier transform infrared (FTIR), UV-visible (UV-Vis) and proton nuclear magnetic resonance (1H-NMR) spectroscopic techniques. Single crystal X-ray diffraction analysis on complex 23 showed that the complex adopted a distorted tetrahedral geometry, where the central copper(I) ion is bonded to nitrogen and sulphur atoms of thiosemicarbazone bidentate ligand and two phosphorus atoms from two triphenylphosphine monodentate ligands while a nitrate ion acted as the counter ion. Molar conductivity value of the complex indicated a 1:1 electrolytic nature which supported the single crystal X-ray diffraction data. The copper complex 23 was converted into copper oxide by means of thermal decomposition. Evaluation of the catalytic performance of the copper(I) complex and copper oxide in the reduction of 4- nitrophenol (4-NP) to 4-aminophenol (4-AP) shows that copper oxide has a higher catalytic activity (98.7%) compared to the copper(I) complex (78.2%). Optimization of the catalyst loading revealed that 1.0 mol% of the catalyst was the most optimized amount with the highest conversion (98.7%). Reproducibility and recyclability tests of the copper oxide catalyst proved that the catalyst exhibits consistent catalytic performances and could be reused four times without a significant decrease. On the other hand, the copper(I) complex required a more prolonged reduction time and a higher amount of catalyst loading due to its insolubility in an aqueous solution. The product from the catalytic reduction, 4-AP was isolated, purified and characterized using FTIR and 1H-NMR spectroscopic techniques. The catalytic activity of the copper oxide catalyst was also evaluated in the reduction of other nitroaromatic compounds with various substituent groups. In these reactions, the copper oxide maintained its excellent catalytic activity and showed consistent results