Fadhlina Ros | The University of Sheffield (original) (raw)

Papers by Fadhlina Ros

Materials Science Forum, Mar 1, 2017

Crystal structures of CaTa4-xNbxO11 solid solutions (x = 0, 1 and 2) in space group P6322, have b... more Crystal structures of CaTa4-xNbxO11 solid solutions (x = 0, 1 and 2) in space group P6322, have been refined by application of the Rietveld method X-ray powder diffraction profile. Refinement were carried out using GSAS software and EXPGUI interface. The unit cell parameters and cell volume increase with increasing Nb content; all samples contain random distribution of Ta/Nb. Strategy and procedures for CaTa4-xNbxO11 solid solutions refinement are reported. The structure consists of layers of tantalum-oxygen bipyramids sharing-edges alternating with layers of octahedra.

Journal of the Australian Ceramic Society, Sep 24, 2018

Eight new phases with the general formula of ABC 3 O 11 with different rare earth, (Zr, Hf), (Nb,... more Eight new phases with the general formula of ABC 3 O 11 with different rare earth, (Zr, Hf), (Nb, Ta) combinations, have been prepared by solid-state reactions at a temperature range of 1200-1500°C. The new phases-LaHfTa, LaHfNb, LaZrNb, PrHfTa, NdHfTa, NdHfNb, SmHfTa and GdHfTa-are characterised by X-ray and neutron diffraction data at room temperature and variable frequency impedance measurements. They are isostructural with LaZrTa 3 O 11 which consist of alternating single layers of UO 7 pentagonal bipyramids and octahedra as shown by Rietveld refinement of X-ray and neutron powder diffraction data. Lattice parameters decrease with decreasing size of rare earth element substitution at A-site, and of all, Gd is the smallest rare earth that formed LaZrTa 3 O 11 analogues. Detailed attempts of attained and unattainable LaZrTa 3 O 11 analogues with different temperatures are included in this paper. All phases are highly insulating with temperature-independent bulk permittivities in the range 17 to 50; LaHfNb demonstrates the highest permittivity. Arrhenius plot shows that the activation energies are in the range 0.8 to 1.94 eV.

There has been a considerable interest in non-ferroelectric perovskite oxide CaCu 3 Ti 4 O 12 (CC... more There has been a considerable interest in non-ferroelectric perovskite oxide CaCu 3 Ti 4 O 12 (CCTO). This material was discovered to possess one of the largest static dielectric constants, reaching nearly ε ~ 80, 000 for single-crystal samples at room temperature. This compound has centrosymmetric structure at room temperature with cubic space group Im3. Because of such incredibly high dielectric constant, the structure, dielectric and electrical properties of CaCu 3 Ti 4 O 12 substituted at Ca-site with other alkaline earth metals i.e. Ba and Sr as substitution elements were studied. An extensive studies were carried out on the dielectric properties of the Ca 1-x Ba x Cu 3 Ti 4 O 12 and Ca 1-x Sr x Cu 3 Ti 4 O 12 where x = 0.5, 0.52, 0.56 and 0.6 at various temperatures. The substitutions were based on ionic radius (r Ca < r Sr < r Ba) and the dielectric studies of Ca 1-x M x Cu 3 Ti 4 O 12 (where M = Sr, Ba) have not been reported so far.

Jurnal teknologi, Feb 23, 2023

Arthropod-borne viruses have become a major threat to human health worldwide. The implementation ... more Arthropod-borne viruses have become a major threat to human health worldwide. The implementation of personal protection through clothing is necessary to avoid insect bites, especially for military operations and public health emergencies. Development of synthetic repellents in clothing impregnation has been wellestablished whilst, numerous studies regarding the application of essential oils on textile substrates have been carried out to develop their use as an alternative to synthetic repellents. The present review attempts to give a general overview and summarize the current technology used in treated clothing, as well as the advantages, challenges, limitations, and factors that may affect the performance of synthetic repellents and essential oils in textiles. Current research trends in developing more effective repellents from essential oils are also summarized.

Advanced Science Letters, Nov 1, 2018

E-journal of Surface Science and Nanotechnology, May 4, 2023

Exposure and misuse of organophosphate (OP) compounds originated from insecticides, drugs and che... more Exposure and misuse of organophosphate (OP) compounds originated from insecticides, drugs and chemical warfare agents are potential hazard to health and environment. OP detection is one of the four strategies (deter, detect, delay, and defend) to protect vulnerable from this chemical threat. Among many methods to detect OP, electrical-based detection and graphene nanomaterials deliver higher sensitivity performance, technological compatibility, and versatility. The magic of graphene originates from its large surface area and excellent electrical conductivity, while electrical methods offer low cost, rapid, and easy handling. This article provides an overview of selected electrical and electrochemical methods employing graphene, reduced graphene oxide, graphene oxide, and other graphene forms reported for OP detection in the recent years. Strategies in using graphene, experimental challenges and fundamental material interactions including advantages using biomaterials as receptors in achieving better detection limit, specificity, and selectivity of OP compounds are the highlights of the paper. Every transformation of graphene has its merits in term of ease of processing, device functionality and sustainability. Since contemporary graphene had successfully reached low detection limit possible in OP sensing, graphene sensor device should be focused on developing rapid and in-situ OP monitoring in water and food resources to alert authorities on possible contamination in the community.

Modern Applied Science, 2015

Adsorption of Zn(II) ions from aqueous solutions by thermally treated rice husk was investigated ... more Adsorption of Zn(II) ions from aqueous solutions by thermally treated rice husk was investigated using factorial experimental design to study effects of heating temperature and period of rice husk, pH, initial Zn(II) ion concentration, adsorption temperature and contact time, and adsorbent dosage. Main and interaction effects of these factors were analyzed using statistical techniques and the results were analyzed statistically using the Student's t-analysis and analysis of variance which were used to determine significant factors that affect the percentage removal of Zn(II). These significant factors were heating temperature of rice husk, pH, initial metal concentration, contact time, and adsorbent dosage. The interaction between two different effects also affects the percentage removal of Zn(II) ions. These include the interactions between heating temperature of rice husk and initial metal concentration, pH and initial metal concentration, and pH and the adsorbent dosage.

Journal of Defence Science, Engineering & Technology

This paper reports on the newly found ferroelectric material, Ag2Nb4O11 ceramics synthesised usin... more This paper reports on the newly found ferroelectric material, Ag2Nb4O11 ceramics synthesised using solid state reaction and characterised its properties using X-ray powder diffraction, ferroelectric test and impedance spectroscopy. However, the synthesis of phase-pure Ag2Nb4O11 ceramics was unsuccessful due the presence of other phases such as AgNbO3, Ag metal and un-reacted Nb2O5 raw material. The inhomogeneity of the sample was clearly seen in impedance measurement which showed electrical inhomogeneity of bulk and grain boundary capacitances. Difficulties in obtaining phase-pure Ag2Nb4O11 ceramics has motivated an investigation on the purity and thermal stability of Ag2O raw material. X-ray diffraction patterns showed that Ag2Nb4O11 consist of Ag2Nb4O11, AgNbO3, Ag metal and un-reacted raw material. Studies on Ag2O raw material was carried out by heating and weighing it after each different temperature. Weight loss observed at temperatures 120oC, 270oC and 400oC correspond to the ...

e-Journal of Surface Science and Nanotechnology

Exposure and misuse of organophosphate (OP) compounds originated from insecticides, drugs and che... more Exposure and misuse of organophosphate (OP) compounds originated from insecticides, drugs and chemical warfare agents are potential hazard to health and environment. OP detection is one of the four strategies (deter, detect, delay, and defend) to protect vulnerable from this chemical threat. Among many methods to detect OP, electrical-based detection and graphene nanomaterials deliver higher sensitivity performance, technological compatibility, and versatility. The magic of graphene originates from its large surface area and excellent electrical conductivity, while electrical methods offer low cost, rapid, and easy handling. This article provides an overview of selected electrical and electrochemical methods employing graphene, reduced graphene oxide, graphene oxide, and other graphene forms reported for OP detection in the recent years. Strategies in using graphene, experimental challenges and fundamental material interactions including advantages using biomaterials as receptors in achieving better detection limit, specificity, and selectivity of OP compounds are the highlights of the paper. Every transformation of graphene has its merits in term of ease of processing, device functionality and sustainability. Since contemporary graphene had successfully reached low detection limit possible in OP sensing, graphene sensor device should be focused on developing rapid and in-situ OP monitoring in water and food resources to alert authorities on possible contamination in the community.

Jurnal Teknologi

Arthropod-borne viruses have become a major threat to human health worldwide. The implementation ... more Arthropod-borne viruses have become a major threat to human health worldwide. The implementation of personal protection through clothing is necessary to avoid insect bites, especially for military operations and public health emergencies. Development of synthetic repellents in clothing impregnation has been well-established whilst, numerous studies regarding the application of essential oils on textile substrates have been carried out to develop their use as an alternative to synthetic repellents. The present review attempts to give a general overview and summarize the current technology used in treated clothing, as well as the advantages, challenges, limitations, and factors that may affect the performance of synthetic repellents and essential oils in textiles. Current research trends in developing more effective repellents from essential oils are also summarized.

Heliyon

The effect of layering structures on mechanical and thermal hybrid bacterial cellulose (BC) sheet... more The effect of layering structures on mechanical and thermal hybrid bacterial cellulose (BC) sheet/Kevlar reinforced epoxy composites was investigated. The BC sheet was extracted from Nata de Coco and used as green reinforcement material hybrid with Kevlar reinforced epoxy composites. The BC/Kevlar reinforced epoxy composite was fabricated by using hand lay-up technique equipped with vacuum bagging system and the BC sheets and Kevlar layers were laminated into different layered structures. The performance of the hybrid BC/Kevlar reinforced epoxy composites was characterized through tensile test and low velocity impact according to ASTM D3039 and ASTM D7136, respectively. The thermal performance of the hybrid composites was characterized by using dynamic mechanical analysis (DMA) test. Tensile test on BC sheet composites with Kevlar and epoxy demonstrated that the addition of BC sheet in BC/Kevlar could not withstand the tensor stress by reducing the tensile stress and Young's modulus. The one layer of Kevlar which was replaced with three to six BC sheets had increased the ability to absorb impact force. The storage modulus (E 0) and Tan δ were significantly dependent on the number of BC sheets and its layering structure. The highest value of E 0 was observed when BC sheets were arranged alternately with the Kevlar layers. Different damage mechanisms associated with the number of BC sheets and its layered-structure suggested that the BC sheet was functioning as an impact energy absorber as well as strengthening fibers. This study will upsurge interest in BC reinforced composites and the development of new ideas in automotive, marine and bullet applications.

Archives of Metallurgy and Materials, 2011

In the present study Bi 1−x Nd x FeO 3 (x=0.1-0.4) ceramic powders were synthesized by the conven... more In the present study Bi 1−x Nd x FeO 3 (x=0.1-0.4) ceramic powders were synthesized by the conventional mixed oxide method. Stoichiometric mixture of the powders was thermally analysed with Netzsch STA-409 system so parameters of the thermal treatment were determined. Morphology of the ceramic material was observed by scanning electron microscopy, whereas the crystalline structure was studied by X-ray diffraction method. It was found that chemical composition of the ceramic samples corresponds well to the initial stoichiometry of the ceramic powders. An increase in neodymium content caused a decrease in the average size of the ceramic grains. Crystalline structure of Bi 1−x Nd x FeO 3 ceramics for x 0.2 was decribed by rhombohedral symmetry whereas for x 0.3 by orthorhombic symmetry. Dielectric properties were studied within a range of frequency ν=20Hz-1MHz at room temperature by impedance spectroscopy. The Kramers-Kronig data validation test was employed in the present impedance data analysis. Impedance data were fitted to the corresponding equivalent circuit using the CNLS fitting method.

Polimery

This paper presents a structural analysis of various methods to produce bacterial cellulose (BC) ... more This paper presents a structural analysis of various methods to produce bacterial cellulose (BC) from Nata de Coco (Acetobacter xyllinum). BC sheet, BC chem and BC mech powder were successfully prepared using oven drying, chemical and mechanical treatment. The X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and field emission scanning electron microscopy (FESEM) were used to analyze the structure of prepared BC. The structure of bacterial cellulose was compared with the structure of commercial microcrystalline cellulose (MCC) and cotton fabric. The XRD results showed that the BC sheet sample had the highest degree of crystallinity (81.76%) compared to cotton cellulose (75.73%). The crystallite size of cotton was larger than the BC sheet, with the value of 6.83 ηm and 4.55 ηm, respectively. The peaks in the FTIR spectra of all BC were comparable to the commercial MCC and cotton fabrics. FESEM images showed that the prepared BC sheet, BC mech, and BC chem had ...

Palladium nanoparticles (PdNP) supported onto the anatase phase of TiO2 were successfully synthes... more Palladium nanoparticles (PdNP) supported onto the anatase phase of TiO2 were successfully synthesised using a colloidal method. This synthesis method involved the reduction of K2PdCl4 solution by NaBH4 at different temperatures (1, 25, 50, 75 oC) and stabilised with PVA ligand. Transmission electron microscope (TEM) was used to determine the particle size of PdNP on the TiO2. Colloidal synthesis at 1 oC and 25 oC produced PdNP with less than a 3 nm diameter, whereas when the synthesis temperatures were higher than 25 oC, PdNP were produced with a size larger than 4 nm. The catalytic activity of Pd/TiO2 was significantly improved when palladium (Pd) was produced at 1 oC with high selectivity towards the hydrogenation of cinnamaldehyde to hydrocinnamaldehyde. The conversion and selectivity trends from the cinnamaldehyde hydrogenation reaction demonstrated the influence of Pd nanoparticle size to provide active sites for the reduction of C=C and C=O bonds. Pd with a diameter of 2.58 nm...

Journal of Physics: Conference Series, 2018

Asian Journal of Chemistry, 2017

Cost effective, easy to use and regenerate could be the desired properties of an adsorbent. Reusi... more Cost effective, easy to use and regenerate could be the desired properties of an adsorbent. Reusing of waste material as CO2 adsorbent can be a good alternative for solving the problem of waste disposal as well. Thus, in this study, aluminium-based drinking water treatment plant sludge as carbon dioxide adsorbent was reused. The sludge collected from a local drinking water treatment plant. It was dried and characterized using scanning electron microscope-energy disperse X-ray (SEM-EDX), Fourier transform infrared spectrometer (FTIR) and thermogravimetric analysis (TGA). Investigations of the effects of temperature, flow rate, concentration of CO2 and adsorbent dosage on CO2 adsorption capacity were performed using a fixed bed column at a pressure of 1 bar. The maximum capacity of 32.56 mg/g was found which was higher than that of some reported adsorbents.

Solid State Phenomena, 2021

Pure nickel nanoparticles with some paired grain shaped has been successfully synthesized using g... more Pure nickel nanoparticles with some paired grain shaped has been successfully synthesized using gamma radiation technique in aqueous system at ambient temperature without using reducing agent. Cetyl trimethylammonium bromide was used to prevent oxidation during radiolysis process and help to shape the nickel nanoparticles into spheroid. Synthesized nanoparticles were characterized using X-ray diffraction, tunnelling electron microscopy and vibrating sample magnetometer. The particles formed are crystallized with fcc phase without any oxidation state. The particle size ranging from 20 – 50 nm which consists of unique morphology of paired spheroid. Vibrating sample magnetometer analysis shows that sample has ferromagnetic properties with value of magnetic remanence smaller that bulk due to its size.

There has been a considerable interest in non-ferroelectric perovskite oxide CaCu3Ti4O12 (CCTO). ... more There has been a considerable interest in non-ferroelectric perovskite oxide CaCu3Ti4O12 (CCTO). This material was discovered to possess one of the largest static dielectric constants, reaching nearly e ~ 80, 000 for single-crystal samples at room temperature. This compound has centrosymmetric structure at room temperature with cubic space group Im3. Because of such incredibly high dielectric constant, the structure, dielectric and electrical properties of CaCu3Ti4O12 substituted at Ca-site with other alkaline earth metals i.e. Ba and Sr as substitution elements were studied. An extensive studies were carried out on the dielectric properties of the Ca1-xBaxCu3Ti4O12 and Ca1-xSrxCu3Ti4O12 where x = 0.5, 0.52, 0.56 and 0.6 at various temperatures. The substitutions were based on ionic radius (rCa < rSr < rBa) and the dielectric studies of Ca1-xMxCu3Ti4O12 (where M = Sr, Ba) have not been reported so far. There are two categories in the experimental investigation. First, is the X...

Materials Science Forum, Mar 1, 2017

Crystal structures of CaTa4-xNbxO11 solid solutions (x = 0, 1 and 2) in space group P6322, have b... more Crystal structures of CaTa4-xNbxO11 solid solutions (x = 0, 1 and 2) in space group P6322, have been refined by application of the Rietveld method X-ray powder diffraction profile. Refinement were carried out using GSAS software and EXPGUI interface. The unit cell parameters and cell volume increase with increasing Nb content; all samples contain random distribution of Ta/Nb. Strategy and procedures for CaTa4-xNbxO11 solid solutions refinement are reported. The structure consists of layers of tantalum-oxygen bipyramids sharing-edges alternating with layers of octahedra.

Journal of the Australian Ceramic Society, Sep 24, 2018

Eight new phases with the general formula of ABC 3 O 11 with different rare earth, (Zr, Hf), (Nb,... more Eight new phases with the general formula of ABC 3 O 11 with different rare earth, (Zr, Hf), (Nb, Ta) combinations, have been prepared by solid-state reactions at a temperature range of 1200-1500°C. The new phases-LaHfTa, LaHfNb, LaZrNb, PrHfTa, NdHfTa, NdHfNb, SmHfTa and GdHfTa-are characterised by X-ray and neutron diffraction data at room temperature and variable frequency impedance measurements. They are isostructural with LaZrTa 3 O 11 which consist of alternating single layers of UO 7 pentagonal bipyramids and octahedra as shown by Rietveld refinement of X-ray and neutron powder diffraction data. Lattice parameters decrease with decreasing size of rare earth element substitution at A-site, and of all, Gd is the smallest rare earth that formed LaZrTa 3 O 11 analogues. Detailed attempts of attained and unattainable LaZrTa 3 O 11 analogues with different temperatures are included in this paper. All phases are highly insulating with temperature-independent bulk permittivities in the range 17 to 50; LaHfNb demonstrates the highest permittivity. Arrhenius plot shows that the activation energies are in the range 0.8 to 1.94 eV.

There has been a considerable interest in non-ferroelectric perovskite oxide CaCu 3 Ti 4 O 12 (CC... more There has been a considerable interest in non-ferroelectric perovskite oxide CaCu 3 Ti 4 O 12 (CCTO). This material was discovered to possess one of the largest static dielectric constants, reaching nearly ε ~ 80, 000 for single-crystal samples at room temperature. This compound has centrosymmetric structure at room temperature with cubic space group Im3. Because of such incredibly high dielectric constant, the structure, dielectric and electrical properties of CaCu 3 Ti 4 O 12 substituted at Ca-site with other alkaline earth metals i.e. Ba and Sr as substitution elements were studied. An extensive studies were carried out on the dielectric properties of the Ca 1-x Ba x Cu 3 Ti 4 O 12 and Ca 1-x Sr x Cu 3 Ti 4 O 12 where x = 0.5, 0.52, 0.56 and 0.6 at various temperatures. The substitutions were based on ionic radius (r Ca < r Sr < r Ba) and the dielectric studies of Ca 1-x M x Cu 3 Ti 4 O 12 (where M = Sr, Ba) have not been reported so far.

Jurnal teknologi, Feb 23, 2023

Arthropod-borne viruses have become a major threat to human health worldwide. The implementation ... more Arthropod-borne viruses have become a major threat to human health worldwide. The implementation of personal protection through clothing is necessary to avoid insect bites, especially for military operations and public health emergencies. Development of synthetic repellents in clothing impregnation has been wellestablished whilst, numerous studies regarding the application of essential oils on textile substrates have been carried out to develop their use as an alternative to synthetic repellents. The present review attempts to give a general overview and summarize the current technology used in treated clothing, as well as the advantages, challenges, limitations, and factors that may affect the performance of synthetic repellents and essential oils in textiles. Current research trends in developing more effective repellents from essential oils are also summarized.

Advanced Science Letters, Nov 1, 2018

E-journal of Surface Science and Nanotechnology, May 4, 2023

Exposure and misuse of organophosphate (OP) compounds originated from insecticides, drugs and che... more Exposure and misuse of organophosphate (OP) compounds originated from insecticides, drugs and chemical warfare agents are potential hazard to health and environment. OP detection is one of the four strategies (deter, detect, delay, and defend) to protect vulnerable from this chemical threat. Among many methods to detect OP, electrical-based detection and graphene nanomaterials deliver higher sensitivity performance, technological compatibility, and versatility. The magic of graphene originates from its large surface area and excellent electrical conductivity, while electrical methods offer low cost, rapid, and easy handling. This article provides an overview of selected electrical and electrochemical methods employing graphene, reduced graphene oxide, graphene oxide, and other graphene forms reported for OP detection in the recent years. Strategies in using graphene, experimental challenges and fundamental material interactions including advantages using biomaterials as receptors in achieving better detection limit, specificity, and selectivity of OP compounds are the highlights of the paper. Every transformation of graphene has its merits in term of ease of processing, device functionality and sustainability. Since contemporary graphene had successfully reached low detection limit possible in OP sensing, graphene sensor device should be focused on developing rapid and in-situ OP monitoring in water and food resources to alert authorities on possible contamination in the community.

Modern Applied Science, 2015

Adsorption of Zn(II) ions from aqueous solutions by thermally treated rice husk was investigated ... more Adsorption of Zn(II) ions from aqueous solutions by thermally treated rice husk was investigated using factorial experimental design to study effects of heating temperature and period of rice husk, pH, initial Zn(II) ion concentration, adsorption temperature and contact time, and adsorbent dosage. Main and interaction effects of these factors were analyzed using statistical techniques and the results were analyzed statistically using the Student's t-analysis and analysis of variance which were used to determine significant factors that affect the percentage removal of Zn(II). These significant factors were heating temperature of rice husk, pH, initial metal concentration, contact time, and adsorbent dosage. The interaction between two different effects also affects the percentage removal of Zn(II) ions. These include the interactions between heating temperature of rice husk and initial metal concentration, pH and initial metal concentration, and pH and the adsorbent dosage.

Journal of Defence Science, Engineering & Technology

This paper reports on the newly found ferroelectric material, Ag2Nb4O11 ceramics synthesised usin... more This paper reports on the newly found ferroelectric material, Ag2Nb4O11 ceramics synthesised using solid state reaction and characterised its properties using X-ray powder diffraction, ferroelectric test and impedance spectroscopy. However, the synthesis of phase-pure Ag2Nb4O11 ceramics was unsuccessful due the presence of other phases such as AgNbO3, Ag metal and un-reacted Nb2O5 raw material. The inhomogeneity of the sample was clearly seen in impedance measurement which showed electrical inhomogeneity of bulk and grain boundary capacitances. Difficulties in obtaining phase-pure Ag2Nb4O11 ceramics has motivated an investigation on the purity and thermal stability of Ag2O raw material. X-ray diffraction patterns showed that Ag2Nb4O11 consist of Ag2Nb4O11, AgNbO3, Ag metal and un-reacted raw material. Studies on Ag2O raw material was carried out by heating and weighing it after each different temperature. Weight loss observed at temperatures 120oC, 270oC and 400oC correspond to the ...

e-Journal of Surface Science and Nanotechnology

Exposure and misuse of organophosphate (OP) compounds originated from insecticides, drugs and che... more Exposure and misuse of organophosphate (OP) compounds originated from insecticides, drugs and chemical warfare agents are potential hazard to health and environment. OP detection is one of the four strategies (deter, detect, delay, and defend) to protect vulnerable from this chemical threat. Among many methods to detect OP, electrical-based detection and graphene nanomaterials deliver higher sensitivity performance, technological compatibility, and versatility. The magic of graphene originates from its large surface area and excellent electrical conductivity, while electrical methods offer low cost, rapid, and easy handling. This article provides an overview of selected electrical and electrochemical methods employing graphene, reduced graphene oxide, graphene oxide, and other graphene forms reported for OP detection in the recent years. Strategies in using graphene, experimental challenges and fundamental material interactions including advantages using biomaterials as receptors in achieving better detection limit, specificity, and selectivity of OP compounds are the highlights of the paper. Every transformation of graphene has its merits in term of ease of processing, device functionality and sustainability. Since contemporary graphene had successfully reached low detection limit possible in OP sensing, graphene sensor device should be focused on developing rapid and in-situ OP monitoring in water and food resources to alert authorities on possible contamination in the community.

Jurnal Teknologi

Arthropod-borne viruses have become a major threat to human health worldwide. The implementation ... more Arthropod-borne viruses have become a major threat to human health worldwide. The implementation of personal protection through clothing is necessary to avoid insect bites, especially for military operations and public health emergencies. Development of synthetic repellents in clothing impregnation has been well-established whilst, numerous studies regarding the application of essential oils on textile substrates have been carried out to develop their use as an alternative to synthetic repellents. The present review attempts to give a general overview and summarize the current technology used in treated clothing, as well as the advantages, challenges, limitations, and factors that may affect the performance of synthetic repellents and essential oils in textiles. Current research trends in developing more effective repellents from essential oils are also summarized.

Heliyon

The effect of layering structures on mechanical and thermal hybrid bacterial cellulose (BC) sheet... more The effect of layering structures on mechanical and thermal hybrid bacterial cellulose (BC) sheet/Kevlar reinforced epoxy composites was investigated. The BC sheet was extracted from Nata de Coco and used as green reinforcement material hybrid with Kevlar reinforced epoxy composites. The BC/Kevlar reinforced epoxy composite was fabricated by using hand lay-up technique equipped with vacuum bagging system and the BC sheets and Kevlar layers were laminated into different layered structures. The performance of the hybrid BC/Kevlar reinforced epoxy composites was characterized through tensile test and low velocity impact according to ASTM D3039 and ASTM D7136, respectively. The thermal performance of the hybrid composites was characterized by using dynamic mechanical analysis (DMA) test. Tensile test on BC sheet composites with Kevlar and epoxy demonstrated that the addition of BC sheet in BC/Kevlar could not withstand the tensor stress by reducing the tensile stress and Young's modulus. The one layer of Kevlar which was replaced with three to six BC sheets had increased the ability to absorb impact force. The storage modulus (E 0) and Tan δ were significantly dependent on the number of BC sheets and its layering structure. The highest value of E 0 was observed when BC sheets were arranged alternately with the Kevlar layers. Different damage mechanisms associated with the number of BC sheets and its layered-structure suggested that the BC sheet was functioning as an impact energy absorber as well as strengthening fibers. This study will upsurge interest in BC reinforced composites and the development of new ideas in automotive, marine and bullet applications.

Archives of Metallurgy and Materials, 2011

In the present study Bi 1−x Nd x FeO 3 (x=0.1-0.4) ceramic powders were synthesized by the conven... more In the present study Bi 1−x Nd x FeO 3 (x=0.1-0.4) ceramic powders were synthesized by the conventional mixed oxide method. Stoichiometric mixture of the powders was thermally analysed with Netzsch STA-409 system so parameters of the thermal treatment were determined. Morphology of the ceramic material was observed by scanning electron microscopy, whereas the crystalline structure was studied by X-ray diffraction method. It was found that chemical composition of the ceramic samples corresponds well to the initial stoichiometry of the ceramic powders. An increase in neodymium content caused a decrease in the average size of the ceramic grains. Crystalline structure of Bi 1−x Nd x FeO 3 ceramics for x 0.2 was decribed by rhombohedral symmetry whereas for x 0.3 by orthorhombic symmetry. Dielectric properties were studied within a range of frequency ν=20Hz-1MHz at room temperature by impedance spectroscopy. The Kramers-Kronig data validation test was employed in the present impedance data analysis. Impedance data were fitted to the corresponding equivalent circuit using the CNLS fitting method.

Polimery

This paper presents a structural analysis of various methods to produce bacterial cellulose (BC) ... more This paper presents a structural analysis of various methods to produce bacterial cellulose (BC) from Nata de Coco (Acetobacter xyllinum). BC sheet, BC chem and BC mech powder were successfully prepared using oven drying, chemical and mechanical treatment. The X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and field emission scanning electron microscopy (FESEM) were used to analyze the structure of prepared BC. The structure of bacterial cellulose was compared with the structure of commercial microcrystalline cellulose (MCC) and cotton fabric. The XRD results showed that the BC sheet sample had the highest degree of crystallinity (81.76%) compared to cotton cellulose (75.73%). The crystallite size of cotton was larger than the BC sheet, with the value of 6.83 ηm and 4.55 ηm, respectively. The peaks in the FTIR spectra of all BC were comparable to the commercial MCC and cotton fabrics. FESEM images showed that the prepared BC sheet, BC mech, and BC chem had ...

Palladium nanoparticles (PdNP) supported onto the anatase phase of TiO2 were successfully synthes... more Palladium nanoparticles (PdNP) supported onto the anatase phase of TiO2 were successfully synthesised using a colloidal method. This synthesis method involved the reduction of K2PdCl4 solution by NaBH4 at different temperatures (1, 25, 50, 75 oC) and stabilised with PVA ligand. Transmission electron microscope (TEM) was used to determine the particle size of PdNP on the TiO2. Colloidal synthesis at 1 oC and 25 oC produced PdNP with less than a 3 nm diameter, whereas when the synthesis temperatures were higher than 25 oC, PdNP were produced with a size larger than 4 nm. The catalytic activity of Pd/TiO2 was significantly improved when palladium (Pd) was produced at 1 oC with high selectivity towards the hydrogenation of cinnamaldehyde to hydrocinnamaldehyde. The conversion and selectivity trends from the cinnamaldehyde hydrogenation reaction demonstrated the influence of Pd nanoparticle size to provide active sites for the reduction of C=C and C=O bonds. Pd with a diameter of 2.58 nm...

Journal of Physics: Conference Series, 2018

Asian Journal of Chemistry, 2017

Cost effective, easy to use and regenerate could be the desired properties of an adsorbent. Reusi... more Cost effective, easy to use and regenerate could be the desired properties of an adsorbent. Reusing of waste material as CO2 adsorbent can be a good alternative for solving the problem of waste disposal as well. Thus, in this study, aluminium-based drinking water treatment plant sludge as carbon dioxide adsorbent was reused. The sludge collected from a local drinking water treatment plant. It was dried and characterized using scanning electron microscope-energy disperse X-ray (SEM-EDX), Fourier transform infrared spectrometer (FTIR) and thermogravimetric analysis (TGA). Investigations of the effects of temperature, flow rate, concentration of CO2 and adsorbent dosage on CO2 adsorption capacity were performed using a fixed bed column at a pressure of 1 bar. The maximum capacity of 32.56 mg/g was found which was higher than that of some reported adsorbents.

Solid State Phenomena, 2021

Pure nickel nanoparticles with some paired grain shaped has been successfully synthesized using g... more Pure nickel nanoparticles with some paired grain shaped has been successfully synthesized using gamma radiation technique in aqueous system at ambient temperature without using reducing agent. Cetyl trimethylammonium bromide was used to prevent oxidation during radiolysis process and help to shape the nickel nanoparticles into spheroid. Synthesized nanoparticles were characterized using X-ray diffraction, tunnelling electron microscopy and vibrating sample magnetometer. The particles formed are crystallized with fcc phase without any oxidation state. The particle size ranging from 20 – 50 nm which consists of unique morphology of paired spheroid. Vibrating sample magnetometer analysis shows that sample has ferromagnetic properties with value of magnetic remanence smaller that bulk due to its size.

There has been a considerable interest in non-ferroelectric perovskite oxide CaCu3Ti4O12 (CCTO). ... more There has been a considerable interest in non-ferroelectric perovskite oxide CaCu3Ti4O12 (CCTO). This material was discovered to possess one of the largest static dielectric constants, reaching nearly e ~ 80, 000 for single-crystal samples at room temperature. This compound has centrosymmetric structure at room temperature with cubic space group Im3. Because of such incredibly high dielectric constant, the structure, dielectric and electrical properties of CaCu3Ti4O12 substituted at Ca-site with other alkaline earth metals i.e. Ba and Sr as substitution elements were studied. An extensive studies were carried out on the dielectric properties of the Ca1-xBaxCu3Ti4O12 and Ca1-xSrxCu3Ti4O12 where x = 0.5, 0.52, 0.56 and 0.6 at various temperatures. The substitutions were based on ionic radius (rCa < rSr < rBa) and the dielectric studies of Ca1-xMxCu3Ti4O12 (where M = Sr, Ba) have not been reported so far. There are two categories in the experimental investigation. First, is the X...