Search results for: absorption kinetics

Authors: Md. Maksudur Rahman Khan, M. Rahim Uddin, Hamidah Abdullah, Kaykobad Md. Rezaul Karim, Abu Yousuf, Chin Kui Cheng, Huei Ruey Ong

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A systematic study was conducted to explore the photocatalytic reduction of carbon dioxide (CO₂) into methanol on TiO₂ loaded copper ferrite (CuFe₂O₄) photocatalyst under visible light irradiation. The phases and crystallite size of the photocatalysts were characterized by X-ray diffraction (XRD) and it indicates CuFe₂O₄ as tetragonal phase incorporation with anatase TiO₂ in CuFe₂O₄/TiO₂ hetero-structure. The XRD results confirmed the formation of spinel type tetragonal CuFe₂O₄ phases along with predominantly anatase phase of TiO₂ in the CuFe₂O₄/TiO₂ hetero-structure. UV-Vis absorption spectrum suggested the formation of the hetero-junction with relatively lower band gap than that of TiO₂. Photoluminescence (PL) technique was used to study the electron–hole (e⁻/h⁺) recombination process. PL spectra analysis confirmed the slow-down of the recombination of electron–hole (e⁻/h⁺) pairs in the CuFe₂O₄/TiO₂ hetero-structure. The photocatalytic performance of CuFe₂O₄/TiO₂ was evaluated based on the methanol yield with varying amount of TiO₂ over CuFe₂O₄ (0.5:1, 1:1, and 2:1) and changing light intensity. The mechanism of the photocatalysis was proposed based on the fact that the predominant species of CO₂ in aqueous phase were dissolved CO₂ and HCO₃^- at pH ~5.9. It was evident that the CuFe₂O₄ could harvest the electrons under visible light irradiation, which could further be injected to the conduction band of TiO₂ to increase the life time of the electron and facilitating the reactions of CO₂ to methanol. The developed catalyst showed good recycle ability up to four cycles where the loss of activity was ~25%. Methanol was observed as the main product over CuFe₂O₄, but loading with TiO₂ remarkably increased the methanol yield. Methanol yield over CuFe₂O₄/TiO₂ was found to be about three times higher (651 μmol/g_cat L) than that of CuFe₂O₄ photocatalyst. This occurs because the energy of the band excited electrons lies above the redox potentials of the reaction products CO₂/CH₃OH.

Keywords: photocatalysis, CuFe2O4/TiO2, band-gap energy, methanol

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Authors: Petros Gkotsis, Giorgos Stratidis, Manassis Mitrakas, Anastasios Zouboulis

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This study investigates the use of original and pre-polymerized iron (Fe) reagents compared to the commonly applied polyaluminum chloride (PACl) coagulant for surface water treatment. Applicable coagulants included both ferric chloride (FeCl₃) and ferric sulfate (Fe₂(SO₄)₃) and their pre-polymerized Fe reagents, such as polyferric sulfate (PFS) and polyferric chloride (PFCl). The efficiency of coagulants was evaluated by the removal of natural organic matter (NOM) and suspended solids (SS), which were determined in terms of reducing the UV absorption at 254 nm and turbidity, respectively. The residual metal concentration (Fe and Al) was also measured. Coagulants were added at five concentrations (1, 2, 3, 4 and 5 mg/L) and three pH values (7.0, 7.3 and 7.6). Experiments were conducted in a jar-test device, with two types of synthetic surface water (i.e., of high and low organic strength) which consisted of humic acid (HA) and kaolin at different concentrations (5 mg/L and 50 mg/L). After the coagulation/flocculation process, clean water was separated with filters of pore size 0.45 μm. Filtration was also conducted before the addition of coagulants in order to compare the ‘net’ effect of the coagulation/flocculation process on the examined parameters (UV at 254 nm, turbidity, and residual metal concentration). Results showed that the use of PACl resulted in the highest removal of humics for both types of surface water. For the surface water of high organic strength (humic acid-kaolin, 50 mg/L-50 mg/L), the highest removal of humics was observed at the highest coagulant dosage of 5 mg/L and at pH=7. On the contrary, turbidity was not significantly affected by the coagulant dosage. However, the use of PACl decreased turbidity the most, especially when the surface water of high organic strength was employed. As expected, the application of coagulation/flocculation prior to filtration improved NOM removal but slightly affected turbidity. Finally, the residual Fe concentration (0.01-0.1 mg/L) was much lower than the residual Al concentration (0.1-0.25 mg/L).

Keywords: coagulation/flocculation, iron and aluminum coagulants, metal salts, pre-polymerized coagulants, surface water treatment

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Authors: Rabindranath Jana, Biswajit Maity, Keka Rana

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The most promising clean energy source is the fuel cell, since it does not generate toxic gases and other hazardous compounds. Again the direct methanol fuel cell (DMFC) is more user-friendly as it is easy to be miniaturized and suited as energy source for automobiles as well as domestic applications and portable devices. And unlike the hydrogen used for some fuel cells, methanol is a liquid that is easy to store and transport in conventional tanks. The most important part of a fuel cell is its membrane. Till now, an overall efficiency for a methanol fuel cell is reported to be about 20 ~ 25%. The lower efficiency of the cell may be due to the critical factors, e.g. slow reaction kinetics at the anode and methanol crossover. The oxidation of methanol is composed of a series of successive reactions creating formaldehyde and formic acid as intermediates that contribute to slow reaction rates and decreased cell voltage. Currently, the investigation of new anode catalysts to improve oxidation reaction rates is an active area of research as it applies to the methanol fuel cell. Surprisingly, there are very limited reports on nanostructured membranes, which are rather simple to manufacture with different tuneable compositions and are expected to allow only the proton permeation but not the methanol due to their molecular sizing effects and affinity to the membrane surface. We have developed a nanostructured fuel cell membrane from polydimethyl siloxane rubber (PDMS), ethylene methyl co-acrylate (EMA) and multi-walled carbon nanotubes (MWNTs). The effect of incorporating different proportions of f-MWNTs in polymer membrane has been studied. The introduction of f-MWNTs in polymer matrix modified the polymer structure, and therefore the properties of the device. The proton conductivity, measured by an AC impedance technique using open-frame and two-electrode cell and methanol permeability of the membranes was found to be dependent on the f-MWNTs loading. The proton conductivity of the membranes increases with increase in concentration of f-MWNTs concentration due to increased content of conductive materials. Measured methanol permeabilities at 60oC were found to be dependant on loading of f-MWNTs. The methanol permeability decreased from 1.5 x 10-6 cm²/s for pure film to 0.8 x 10-7 cm²/s for a membrane containing 0.5wt % f-MWNTs. This is due to increasing proportion of f-MWNTs, the matrix becomes more compact. From DSC melting curves it is clear that the polymer matrix with f-MWNTs is thermally stable. FT-IR studies show good interaction between EMA and f-MWNTs. XRD analysis shows good crystalline behavior of the prepared membranes. Significant cost savings can be achieved when using the blended films which contain less expensive polymers.

Keywords: fuel cell membrane, polydimethyl siloxane rubber, carbon nanotubes, proton conductivity, methanol permeability

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Authors: Augustus K. Lebechi, Kenneth I. Ozoemena

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Rechargeable zinc-air batteries (RZABs) have been described as one of the most viable next-generation ‘beyond-the-lithium-ion’ battery technologies with great potential for renewable energy storage. It is safe, with a high specific energy density (1086 Wh/kg), environmentally benign, and low-cost, especially in resource-limited African countries. For widespread commercialization, the sluggish oxygen reaction kinetics pose a major challenge that impedes the reversibility of the system. Hence, there is a need for low-cost and highly active bifunctional electrocatalysts. Manganese oxide catalysts on carbon conducting additives remain the best couple for the realization of such low-cost RZABs. In this work, hausmannite Mn₃O₄ nanoparticles were synthesized through the annealing method from commercial electrolytic manganese dioxide (EMD), multi-walled carbon nanotubes (MWCNTs) were synthesized via the chemical vapor deposition (CVD) method and carbon nanofibers (CNFs) were synthesized via the electrospinning process with subsequent carbonization. Both Mn₃O₄ catalysts and the carbon conducting additives (MWCNT and CNF) were thoroughly characterized using X-ray powder diffraction spectroscopy (XRD), scanning electron microscopy (SEM), thermogravimetry analysis (TGA) and X-ray photoelectron spectroscopy (XPS). Composite electrocatalysts (Mn₃O₄/CNT and Mn₃O₄/CNF) were investigated for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) in an alkaline medium. Using the established electrocatalytic modalities for evaluating the electrocatalytic performance of materials (including double layer, electrochemical active surface area, roughness factor, specific current density, and catalytic stability), CNFs proved to be the most efficient conducting additive material for the Mn₃O₄ catalyst. From the DFT calculations, the higher performance of the CNFs over the MWCNTs is related to the ability of the CNFs to allow for a more favorable distribution of the d-electrons of the manganese (Mn) and enhanced synergistic effect with Mn₃O₄ for weaker adsorption energies of the oxygen intermediates (O*, OH* and OOH*). In a proof-of-concept, Mn₃O₄/CNF was investigated as the air cathode for rechargeable zinc-air battery (RZAB) in a micro-3D-printed cell configuration. The RZAB showed good performance in terms of open circuit voltage (1.77 V), maximum power density (177.5 mW cm-2), areal-discharge energy and cycling stability comparable to Pt/C (20 wt%) + IrO2. The findings here provide fresh physicochemical perspectives on the future design and utility of CNFs for developing manganese-based RZABs.

Keywords: bifunctional electrocatalyst, oxygen evolution reaction, oxygen reduction reactions, rechargeable zinc-air batteries.

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Authors: P. Joshna, Souvik Kundu

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Detection of ultraviolet (UV) radiation is very important as it has exhibited a profound influence on humankind and other existences, including military equipment. In this work, a self-powered UV photodetector was reported based on oxides heterojunctions. The thin films of p-type nickel oxide (NiO) and n-type reduced graphene oxide (rGO) were used for the formation of p-n heterojunction. Low-Cost and low-temperature chemical synthesis was utilized to prepare the oxides, and the spin coating technique was employed to deposit those onto indium doped tin oxide (ITO) coated glass substrates. The top electrode platinum was deposited utilizing physical vapor evaporation technique. NiO offers strong UV absorption with high hole mobility, and rGO prevents the recombination rate by separating electrons out from the photogenerated carriers. Several structural characterizations such as x-ray diffraction, atomic force microscope, scanning electron microscope were used to study the materials crystallinity, microstructures, and surface roughness. On one side, the oxides were found to be polycrystalline in nature, and no secondary phases were present. On the other side, surface roughness was found to be low with no pit holes, which depicts the formation of high-quality oxides thin films. Whereas, x-ray photoelectron spectroscopy was employed to study the chemical compositions and oxidation structures. The electrical characterizations such as current-voltage and current response were also performed on the device to determine the responsivity, detectivity, and external quantum efficiency under dark and UV illumination. This p-n heterojunction device offered faster photoresponse and high on-off ratio under 365 nm UV light illumination of zero bias. The device based on the proposed architecture shows the efficacy of the oxides heterojunction for efficient UV photodetection under zero bias, which opens up a new path towards the development of self-powered photodetector for environment and health monitoring sector.

Keywords: chemical synthesis, oxides, photodetectors, spin coating

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Authors: Ghada Ben Hamad, Zohir Younsi, Hassane Naji, Noureddine Lebaz, Naoual Belouaggadia

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This study deals with a bifunctional micro-encapsulated phase change (MCP) material, capric-stearic acid/graphene oxide-TiO2, which has been successfully developed by in situ hydrolysis and polycondensation of tetrabutyl titanate and modification of graphene oxide (GO) on the TiO2 doped shell. The use of graphene and doped TiO2 is a promising approach to provide photocatalytic activity under visible light and improve the microcapsules physicochemical properties. The morphology and chemical structure of the resulting microcapsule samples were determined by using Fourier transform infrared (FT-IR) spectroscopy, scanning electronic microscope (SEM), and X-ray diffractometer (XRD) methods. The ultraviolet, visible spectrophotometer (UV–vis), the differential scanning calorimeter (DSC) and the thermogravimetric analyzer (TGA) were used to investigate the absorption of visible and ultraviolet (UV), the thermal properties, and thermal stabilities of the microcapsules. Note that, the visible light photocatalytic activity was assessed for the toluene and benzene gaseous removal in a suitable test room. The microcapsules exhibit an interesting spherical morphology and an average diameter of 15 to 25 μm. The addition of graphene can enhance the rigidity of the shell and improve the microcapsules thermal reliability. At the same time, the thermal analysis tests showed that the synthesized microcapsules had a high solar thermal energy-storage and better thermal stability. In addition, the capric-stearic acid microcapsules exhibited high solar photocatalytic activity with respect to atmospheric pollutants under natural sunlight. The fatty acid samples obtained with the GO/TiO2 shell showed great potential for applications of solar energy storage, solar photocatalytic degradation of air pollutants and buildings energy conservation.

Keywords: thermal energy storage, microencapsulation, titanium dioxide, photocatalysis, graphene oxide

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Authors: Lorenzo Cocola, Massimo Fedel, Dragiša Savić, Bojana Danilović, Luca Poletto

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An instrument for the detection and evaluation of gaseous carbon dioxide in the headspace of closed containers has been developed in the context of Packsensor Italian-Serbian joint project. The device is based on Tunable Diode Laser Absorption Spectroscopy (TDLAS) with a Wavelength Modulation Spectroscopy (WMS) technique in order to accomplish a non-invasive measurement inside closed containers of fermented dairy products (yogurts and fermented cheese in cups and bottles). The purpose of this instrument is the continuous monitoring of carbon dioxide concentration during incubation and storage of products over a time span of the whole shelf life of the product, in the presence of different microorganisms. The instrument’s optical front end has been designed to be integrated in a thermally stabilized incubator. An embedded computer provides processing of spectral artifacts and storage of an arbitrary set of calibration data allowing a properly calibrated measurement on many samples (cups and bottles) of different shapes and sizes commonly found in the retail distribution. A calibration protocol has been developed in order to be able to calibrate the instrument on the field also on containers which are notoriously difficult to seal properly. This calibration protocol is described and evaluated against reference measurements obtained through an industry standard (sampling) carbon dioxide metering technique. Some sets of validation test measurements on different containers are reported. Two test recordings of carbon dioxide concentration evolution are shown as an example of instrument operation. The first demonstrates the ability to monitor a rapid yeast growth in a contaminated sample through the increase of headspace carbon dioxide. Another experiment shows the dissolution transient with a non-saturated liquid medium in presence of a carbon dioxide rich headspace atmosphere.

Keywords: TDLAS, carbon dioxide, cups, headspace, measurement

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Authors: Mouna Baassi, Mohamed Moussaoui, Sanchaita Rajkhowa, Hatim Soufi, Said Belaaouad

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The objective of this paper is to address the challenging task of targeting Human Immunodeficiency Virus type 1 Reverse Transcriptase (HIV-1 RT) in the treatment of AIDS. Reverse Transcriptase inhibitors (RTIs) have limitations due to the development of Reverse Transcriptase mutations that lead to treatment resistance. In this study, a combination of statistical analysis and bioinformatics tools was adopted to develop a mathematical model that relates the structure of compounds to their inhibitory activities against HIV-1 Reverse Transcriptase. Our approach was based on a series of compounds recognized for their HIV-1 RT enzymatic inhibitory activities. These compounds were designed via software, with their descriptors computed using multiple tools. The most statistically promising model was chosen, and its domain of application was ascertained. Furthermore, compounds exhibiting comparable biological activity to existing drugs were identified as potential inhibitors of HIV-1 RT. The compounds underwent evaluation based on their chemical absorption, distribution, metabolism, excretion, toxicity properties, and adherence to Lipinski's rule. Molecular docking techniques were employed to examine the interaction between the Reverse Transcriptase (Wild Type and Mutant Type) and the ligands, including a known drug available in the market. Molecular dynamics simulations were also conducted to assess the stability of the RT-ligand complexes. Our results reveal some of the new compounds as promising candidates for effectively inhibiting HIV-1 Reverse Transcriptase, matching the potency of the established drug. This necessitates further experimental validation. This study, beyond its immediate results, provides a methodological foundation for future endeavors aiming to discover and design new inhibitors targeting HIV-1 Reverse Transcriptase.

Keywords: QSAR, ADMET properties, molecular docking, molecular dynamics simulation, reverse transcriptase inhibitors, HIV type 1

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Authors: Suman Som, Abhijit Maity, Sunil B. Daschakraborty, Sujit Chaudhuri, Manik Pradhan

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Background: Helicobacter pylori is a common and important human pathogen and the primary cause of peptic ulcer disease and gastric cancer. Currently H. pylori infection is detected by both invasive and non-invasive way but the diagnostic accuracy is not up to the mark. Aim: To set up an optimal diagnostic cut-off value of 13C-Urea Breath Test to detect H. pylori infection and evaluate a novel c-PDR methodology to overcome of inconclusive grey zone. Materials and Methods: All 83 subjects first underwent upper-gastrointestinal endoscopy followed by rapid urease test and histopathology and depending on these results; we classified 49 subjects as H. pylori positive and 34 negative. After an overnight, fast patients are taken 4 gm of citric acid in 200 ml water solution and 10 minute after ingestion of the test meal, a baseline exhaled breath sample was collected. Thereafter an oral dose of 75 mg 13C-Urea dissolved in 50 ml water was given and breath samples were collected upto 90 minute for 15 minute intervals and analysed by laser based high precisional cavity enhanced spectroscopy. Results: We studied the excretion kinetics of 13C isotope enrichment (expressed as δDOB13C ‰) of exhaled breath samples and found maximum enrichment around 30 minute of H. pylori positive patients, it is due to the acid mediated stimulated urease enzyme activity and maximum acidification happened within 30 minute but no such significant isotopic enrichment observed for H. pylori negative individuals. Using Receiver Operating Characteristic (ROC) curve an optimal diagnostic cut-off value, δDOB13C ‰ = 3.14 was determined at 30 minute exhibiting 89.16% accuracy. Now to overcome grey zone problem we explore percentage dose of 13C recovered per hour, i.e. 13C-PDR (%/hr) and cumulative percentage dose of 13C recovered, i.e. c-PDR (%) in exhaled breath samples for the present 13C-UBT. We further explored the diagnostic accuracy of 13C-UBT by constructing ROC curve using c-PDR (%) values and an optimal cut-off value was estimated to be c-PDR = 1.47 (%) at 60 minute, exhibiting 100 % diagnostic sensitivity , 100 % specificity and 100 % accuracy of 13C-UBT for detection of H. pylori infection. We also elucidate the gastric emptying process of present 13C-UBT for H. pylori positive patients. The maximal emptying rate found at 36 minute and half empting time of present 13C-UBT was found at 45 minute. Conclusions: The present study exhibiting the importance of c-PDR methodology to overcome of grey zone problem in 13C-UBT for accurate determination of infection without any risk of diagnostic errors and making it sufficiently robust and novel method for an accurate and fast non-invasive diagnosis of H. pylori infection for large scale screening purposes.

Keywords: 13C-Urea breath test, c-PDR methodology, grey zone, Helicobacter pylori

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Authors: A. Alzahrani, G. Arnold, W. Wang

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Background: Stroke commonly occurs in middle-aged and elderly populations, and the diagnosis of early stroke is still difficult. Patients who have suffered a stroke have different balance and gait patterns from healthy people. Advanced techniques of motion analysis have been routinely used in the clinical assessment of cerebral palsy. However, so far, little research has been done on the direct diagnosis of early stroke patients using motion analysis. Objectives: The aim of this study was to investigate whether patients with stroke have different balance and gait from healthy people and which biomechanical parameters could be used to predict and diagnose potential patients who are at a potential risk to stroke. Methods: Thirteen patients with stroke were recruited as subjects whose gait and balance was analysed. Twenty normal subjects at the matched age participated in this study as a control group. All subjects’ gait and balance were collected using Vicon Nexus® to obtain the gait parameters, kinetic, and kinematic parameters of the hip, knee, and ankle joints in three planes of both limbs. Participants stood on force platforms to perform a single leg balance test. Then, they were asked to walk along a 10 m walkway at their comfortable speed. Participants performed 6 trials of single-leg balance for each side and 10 trials of walking. From the recorded trials, three good ones were analysed using the Vicon Plug-in-Gait model to obtain gait parameters, e.g., walking speed, cadence, stride length, and joint parameters, e.g., joint angle, force, moments, etc. Result: The temporal-spatial variables of Stroke subjects were compared with the healthy subjects; it was found that there was a significant difference (p < 0.05) between the groups. The step length, speed, cadence were lower in stroke subjects as compared to the healthy groups. The stroke patients group showed significantly decreased in gait speed (mean and SD: 0.85 ± 0.33 m/s), cadence ( 96.71 ± 16.14 step/min), and step length (0.509 ± 017 m) in compared to healthy people group whereas the gait speed was 1.2 ± 0.11 m/s, cadence 112 ± 8.33 step/min, and step length 0.648 ± 0.43 m. Moreover, it was observed that patients with stroke have significant differences in the ankle, hip, and knee joints’ kinematics in the sagittal and coronal planes. Also, the result showed that there was a significant difference between groups in the single-leg balance test, e.g., maintaining single-leg stance time in the stroke patients showed shorter duration (5.97 ± 6.36 s) in compared to healthy people group (14.36 ± 10.20 s). Conclusion: Our result showed that there are significantly differences between stroke patients and healthy subjects in the various aspects of gait analysis and balance test, as a consequences of these findings some of the biomechanical parameters such as joints kinematics, gait parameters, and single-leg stance balance test could be used in clinical practice to predict and diagnose potential patients who are at a high risk of further stroke.

Keywords: gait analysis, kinetics, kinematics, single-leg stance, Stroke

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Authors: Sayed M. Ahmed, Sawsan S. Darwish, Mahmoud A. Adam, Nagib A. Elmarzugi, Mohammad A. Al-Dosari, Nadia A. Al-Mouallimi

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Historical stone surfaces and architectural heritage especially which located in open areas may undergo unwanted changes due to the exposure to many physical and chemical deterioration factors, air pollution, soluble salts, Rh/temperature, and biodeterioration are the main causes of decay of stone building materials. The development and application of self-cleaning treatments on historical and architectural stone surfaces could be a significant improvement in conservation, protection, and maintenance of cultural heritage. In this paper, nanometric titanium dioxide has become a promising photocatalytic material owing to its ability to catalyze the complete degradation of many organic contaminants and represent an appealing way to create self-cleaning surfaces, thus limiting maintenance costs, and to promote the degradation of polluting agents. The obtained nano-TiO2 coatings were applied on travertine (Marble and limestone often used in historical and monumental buildings). The efficacy of the treatments has been evaluated after coating and artificial thermal aging, through capillary water absorption, Ultraviolet-light exposure to evaluate photo-induced and the hydrophobic effects of the coated surface, while the surface morphology before and after treatment was examined by scanning electron microscopy (SEM). The changes of molecular structure occurring in treated samples were spectroscopy studied by FTIR-ATR, and Colorimetric measurements have been performed to evaluate the optical appearance. All the results get together with the apparent effect that coated TiO2 nanoparticles is an innovative method, which enhanced the durability of stone surfaces toward UV aging, improved their resistance to relative humidity and temperature, self-cleaning photo-induced effects are well evident, and no alteration of the original features.

Keywords: architectural calcareous stone monuments, coating, photocatalysis TiO2, self-cleaning, thermal aging

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Authors: Thilini Kananke

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Culinary herbs have long been considered as significant dietary sources of many potential health-promoting compounds. The present research focused on analysis of antimicrobial, antioxidant and physicochemical properties in selected four culinary herbs namely Murraya koenigii (Curry leaves), Pandanus amaryllifolius (Pandan leaves), Cymbopogon citrates (Lemon grass leaves), and Mentha Piperita (Minchi leaves) obtained from several market sites in Ratnapura District, Sri Lanka. The antimicrobial activity of ethanolic, chloroform and distilled water extracts of culinary herbs were evaluated against the strains of Staphylococcus aureus, Salmonella typhi and Shigella spp. Total phenolic content and the radical scavenging activity (using DPPH assay) of culinary herbs were determined. Four heavy metals (Cu, Cd, Pb and Fe) were analyzed in the selected culinary herbs using the atomic absorption spectroscopy (AAS). Proximate compositions of the selected herbs were analyzed using AOAC official methods. Antimicrobial activity of all selected culinary herbs showed relativity high inhibition zones against S. aureus. Pandan leaves showed the least antimicrobial activity against selected bacterial strains compared with other culinary herbs. Both the highest radical scavenging activity (lower IC50 value) and the total phenolic content (25.57 ±3.54µg GAE/100g) were reported in Mentha piperita extract. The highest concentrations of Cu, Fe and Cd were reported in Curry leaves (29.15 mg/kg), Lemon grass leaves (257.98 mg/kg) and Pandan leaves (6.05 mg/kg) respectively. The heavy metal contents detected in all culinary herbs were below the permitted limits set by WHO/FAO, except Cd. The highest moisture (85.00±0.00%) and fiber (10.66± 2.00%) contents were found in Pandan leaves, while the highest protein (8.94±0.29%), fat (12.3± 2.52%) and ash (3.50± 0.17%) contents were reported in curry leaves. The information obtained from this study highlights the importance of further investigation of other antioxidant, antimicrobial and health promoting compounds of culinary herbs available in Sri Lanka for a detailed comparison.

Keywords: antimicrobial, antioxidant, culinary herbs, proximate analysis

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Authors: Sharmin Akhter, M. Salahuddin, Sukalyan Kumar Kundu, Mohammad Fahim Kadir

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Relatively insoluble candidate drug like carbamazepine (CBZ) often exhibit incomplete or erratic absorption; and hence wide consideration is given to improve aqueous solubility of such compound. Solid dispersions were formulated with an aim of improving aqueous solubility, oral bioavailability and the rate of dissolution of Carbamazepine using different hydrophyllic polymer like Polyethylene Glycol (PEG) 6000, Polyethylene Glycol (PEG) 4000, kollidon 30, HPMC 6 cps, poloxamer 407 and povidone k 30. Solid dispersions were prepared with different drug to polymer weight ratio by the solvent evaporation method where methanol was used as solvent. Drug-polymer physical mixtures were also prepared to compare the rate of dissolution. Effects of different polymer were studied for solid dispersion formulation as well as physical mixtures. These formulations were characterized in the solid state by Fourier Transform Infrared (FTIR) spectroscopy and Scanning Electron Microscopy (SEM). Solid state characterization indicated CBZ was present as fine particles and entrapped in carrier matrix of PEG 6000 and PVP K30 solid dispersions. Fourier Transform Infrared (FTIR) spectroscopic studies showed the stability of CBZ and absence of well-defined drug-polymer interactions. In contrast to the very slow dissolution rate of pure CBZ, dispersions of drug in polymers considerably improved the dissolution rate. This can be attributed to increased wettability and dispersibility, as well as decreased crystallinity and increase in amorphous fraction of drug. Solid dispersion formulations containing PEG 6000 and Povidone K 30 showed maximum drug release within one hour at the ratio of 1:1:1. Even physical mixtures of CBZ prepared with both carriers also showed better dissolution profiles than those of pure CBZ. In conclusions, solid dispersions could be a promising delivery of CBZ with improved oral bioavailability and immediate release profiles.

Keywords: carbamazepine, FTIR, kollidon 30, HPMC 6 CPS, PEG 6000, PEG 4000, poloxamer 407, water solubility, povidone k 30, SEM, solid dispersion

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Authors: Akbar Esmaeili, Mahnoosh Aliahmadi

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This study synthesized a modified imaging of gallium@deferoxamine/folic acid/chitosan/polyaniline/polyvinyl alcohol (Ga@DFA/FA/CS/PANI/PVA). It contains Morus nigra extract by selenium nanoparticles prepared from Lactobacillus acidophilus. Using the impregnation method, Se nanoparticles were then deposited on (Ga@DFA/FA/ CS/PANI/PVA). The modified contrast agents were mixed with M. nigra extract, and investigated their antibacterial activities by applying to L929 cell lines. The influence of variable factors, including 1. surfactant, 2. solvent, 3. aqueous phase, 4. pH, 5. buffer, 6. minimum Inhibitory concentration (MIC), 7. minimum bactericidal concentration (MBC), 8. cytotoxicity on cancer cells., 9. antibiotic, 10. antibiogram, 11. release and loading, 12. the emotional effect, 13. the concentration of nanoparticles, 14. olive oil, and 15. they have investigated thermotical methods. The structure and morphology of the synthesized contrast agents were characterized by zeta potential sizer analysis (ZPS), X-Ray diffraction (XRD), Fourier-transform infrared (FT-IR), energy dispersive X-ray (EDX), ultraviolet–visible (UV–Vis) spectra, and scanning electron microscope (SEM). The experimental section was conducted and monitored by response surface methods (RSM), MTT, MIC, MBC, and cancer cytotoxic conversion assay. Antibiogram testing of NCs on Pseudomonas aeruginosa bacteria was successful and obtained MIC = 2 factors with less harmful effect. All experimental sections confirmed that our synthesized particles have potent antioxidant properties. Antibiogram testing revealed that NPS could kill P. aeruginosa and P. aeruginosa. A variety of synthetic conditions were done by diffusion emulsion method by varying parameters, the optimum state of DFA release Ga@DFA/FA/CS/PANI/PVA NPs (6 ml) with pH = 5.5, time = 3 h, NCs and DFA (3 mg), and achieved buffer (20 ml). DFA in Ga@DFA/FA/ CS/PANI/PVA was released and showed an absorption peak at 378 nm by applying a 300-rpm magnetic rate. In this report, Ga decreased the harmful effect on the human body.

Keywords: nanocapsules, technolgy, biology, nano

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Authors: D. A. Bruzon, G. Tapang, I. S. Martinez

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Global warming and climate change are significant environmental concerns, which require immediate global action in carbon emission mitigation. The capture, sequestration, and conversion of carbon dioxide to other products such as methane or ethanol are ways to control excessive emissions. Ionic liquids have shown great potential among the materials studied as carbon capture solvents and catalysts in the reduction of CO2. In this study, ionic liquids comprising of a methoxy (-OCH3) and cyano (-CN) functionalized imidazolium cation, [MOBMIM] and [CNBMIM] respectively, paired with tris(pentafluoroethyl)trifluorophosphate [FAP] anion were evaluated as effective capture solvents, and organocatalysts in the reduction of CO2. An in-situ electrochemical set-up, which can measure controlled amounts of CO2 both in the gas and in the ionic liquid phase, was used. Initially, reduction potentials of CO2 in the CO2-saturated ionic liquids containing the internal standard cobaltocene were determined using cyclic voltammetry. Chronoamperometric transients were obtained at potentials slightly less negative than the reduction potentials of CO2 in each ionic liquid. The time-dependent current response was measured under a controlled atmosphere. Reduction potentials of CO2 in methoxy and cyano-functionalized [FAP] ionic liquids were observed to occur at ca. -1.0 V (vs. Cc+/Cc), which was significantly lower compared to the non-functionalized analog [PMIM][FAP], with an observed reduction potential of CO2 at -1.6 V (vs. Cc+/Cc). This decrease in the potential required for CO2 reduction in the functionalized ionic liquids shows that the functional groups methoxy and cyano effectively decreased the free energy of formation of the radical anion CO2●⁻, suggesting that these electrolytes may be used as organocatalysts in the reduction of the greenhouse gas. However, upon analyzing the solubility of the gas in each ionic liquid, [PMIM][FAP] showed the highest absorption capacity, at 4.81 mM under saturated conditions, compared to [MOBMIM][FAP] at 1.86 mM, and [CNBMIM][FAP] at 0.76 mM. Also, calculated Henry’s constant determined from the concentration-pressure graph of each functionalized ionic liquid shows that the groups -OCH3 and -CN attached terminal to a C4 alkyl chain do not significantly improve CO2 solubility.

Keywords: carbon capture, CO2 reduction, electrochemistry, ionic liquids

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Authors: Mohsin Ejaz, Shiao-Wei Kuo

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The growing production and exploitation of fossil fuels have placed human society in serious environmental issues. As a result, it's critical to design efficient and eco-friendly energy production and storage techniques. Porous organic polymers (POPs) are multi-dimensional porous network materials developed through the formation of covalent bonds between different organic building blocks that possess distinct geometries and topologies. POPs have tunable porosities and high surface area making them a good candidate for an effective electrode material in energy storage applications. Herein, we prepared a fully benzoxazine-based porous organic polymers (TPA–DHTP–BZ POP) through sonogashira coupling of dihydroxyterephthalaldehyde (DHPT) and triphenylamine (TPA) containing benzoxazine (BZ) monomers. Firstly, both BZ monomers (TPA-BZ-Br and DHTP-BZ-Ea) were synthesized by three steps, including Schiff base, reduction, and mannich condensation reaction. Finally, the TPA–DHTP–BZ POP was prepared through the sonogashira coupling reaction of brominated monomer (TPA-BZ-Br) and ethynyl monomer (DHTP-BZ-Ea). Fourier transform infrared (FTIR) and solid-state nuclear magnetic resonance (NMR) spectroscopy confirmed the successful synthesis of monomers as well as POP. The porosity of TPA–DHTP–BZ POP was investigated by the N₂ absorption technique and showed a Brunauer–Emmett–Teller (BET) surface area of 196 m² g−¹, pore size 2.13 nm and pore volume of 0.54 cm³ g−¹, respectively. The TPA–DHTP–BZ POP experienced thermal ring-opening polymerization, resulting in poly (TPA–DHTP–BZ) POP having strong inter and intramolecular hydrogen bonds formed by phenolic groups and Mannich bridges, thereby enhancing CO₂ capture and supercapacitive performance. The poly(TPA–DHTP–BZ) POP demonstrated a remarkable CO₂ capture of 3.28 mmol g−¹ and a specific capacitance of 67 F g−¹ at 0.5 A g−¹. Thus, poly(TPA–DHTP–BZ) POP could potentially be used for energy storage and CO₂ capture applications.

Keywords: porous organic polymer, benzoxazine, sonogashira coupling, CO₂, supercapacitor

Procedia PDF Downloads 42

Authors: Laïd Boukraâ

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Complementary and Alternative Medicine is an inclusive term that describes treatments, therapies, and modalities that are not accepted as components of mainstream education or practice, but that are performed on patients by some practitioners. While these treatments and therapies often form part of post-graduate education, study and writing, they are generally viewed as alternatives or complementary to more universally accepted treatments. Ancient civilizations used bee products and medicinal plants, but modern civilization and ‘education’ have seriously lessened our natural instinctive ability and capability. Despite the fact that the modern Western establishment appears to like to relegate apitherapy and aromatherapy to the status of 'folklore' or 'old wives' tales', they contain a vast spread of pharmacologically-active ingredients and each one has its own unique combination and properties. They are classified in modern herbal medicine according to their spheres of action. Bee products and medicinal plants are well-known natural product for their healing properties and their increasing popularity recently as they are widely used in wound healing. Honey not only has antibacterial properties which can help as an antibacterial agent but also has chemical properties which may further help in the wound healing process. A formulation with honey as its main component was produced into a honey gel. This new formulation has enhanced texture and is more user friendly for usage as well. This new formulation would be better than other formulas as it is hundred percent consisting of natural products and has been made into a better formulation. In vitro assay, animal model study and clinical trials have shown the effectiveness of LEADERMAX for the treatment of diabetic foot, burns, leg ulcer and bed sores. This one hundred percent natural product could be the best alternative to conventional products for wound and burn management. The advantages of the formulation are: 100% natural, affordable, easy to use, strong power of absorption, dry surface on the wound making a film, will not stick to the wound bed; helps relieve wound pain, inflammation, edema and bruising while improving comfort.

Keywords: bed sore bee products, burns, diabetic foot, medicinal plants, leg ulcer, wounds

Procedia PDF Downloads 321

Authors: Sumira Jan, Javid Iqbal Mir, Desh Beer Singh, Anil Sharma, Shafia Zaffar Faktoo

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Background and Aims: Climatic and edaphic factors immensely influence crop quality and proper development. Regardless of economic potential, Himalayan Oregano has not subjected to phytonutrient and chemometric evaluation and its relationship with environmental conditions are scarce. The central objective of this research was to investigate microclimatic variation among wild and cultivated populations located in a microclimatic gradient in north-western Himalaya, Kashmir and analyse if such disparity was related with diverse climatic and edaphic conditions. Methods: Micrometeorological, Atomic absorption spectroscopy for micro elemental analysis was carried for soil. HPLC was carried out to estimate variation in phytonutrients and phytochemicals. Results: Geographic variation in phytonutrient was observed among cultivated and wild populations and among populations diverse within regions. Cultivated populations exhibited comparatively lesser phytonutrient value than wild populations. Moreover, our results observed higher vegetative growth of O. vulgare L. with higher pH (6-7), elevated organic carbon (2.42%), high nitrogen (97.41Kg/ha) and manganese (10-12ppm) and zinc contents (0.39-0.50) produce higher phytonutrients. HPLC data of phytonutrients like quercetin, betacarotene, ascorbic acid, arbutin and catechin revealed direct relationship with UV-B flux (r2=0.82), potassium (r2=0.97) displaying parallel relationship with phytonutrient value. Conclusions: Catechin was found as predominant phytonutrient among all populations with maximum accumulation of 163.8 ppm while as quercetin exhibited lesser value. Maximum arbutin (53.42ppm) and quercetin (2.87ppm) accumulated in plants thriving under intense and high UV-B flux. Minimum variation was demonstrated by beta carotene and ascorbic acid.

Keywords: phytonutrient, ascorbic acid, beta carotene, quercetin, catechin

Procedia PDF Downloads 247

Authors: Ariba Siddiqui, Amber Khan

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The need for bio-implantable devices in the field of medical sciences has been increasing day by day; however, the charging of these devices is a major issue. Batteries, a very common method of powering the implants, have a limited lifetime and bulky nature. Therefore, as a replacement of batteries, acoustic power transfer (APT) technology is being accepted as the most suitable technique to wirelessly power the medical implants in the present scenario. The basic model of APT consists of piezoelectric transducers that work on the principle of converse piezoelectric effect at the transmitting end and direct piezoelectric effect at the receiving end. This paper provides mechanistic insight into the parameters affecting the design and efficient working of acoustic power transfer systems. The optimum design considerations have been presented that will help to compress the size of the device and augment the intensity of the pressure wave. A COMSOL model of the PZT (Lead Zirconate Titanate) transducer was developed. The model was simulated and analyzed on a frequency spectrum. The simulation results displayed that the efficiency of these devices is strongly dependent on the frequency of operation, and a wrong choice of the operating frequency leads to the high absorption of acoustic field inside the tissue (medium), poor power strength, and heavy transducers, which in effect influence the overall configuration of the acoustic systems. Considering all the tradeoffs, the simulations were performed again by determining an optimum frequency (900 kHz) that resulted in the reduction of the transducer's thickness to 1.96 mm and augmented the power strength with an intensity of 432 W/m². Thus, the results obtained after the second simulation contribute to lesser attenuation, lightweight systems, high power intensity, and also comply with safety limits provided by the U.S Food and Drug Administration (FDA). It was also found that the chosen operating frequency enhances the directivity of the acoustic wave at the receiver side.

Keywords: acoustic power, bio-implantable, COMSOL, Lead Zirconate Titanate, piezoelectric, transducer

Procedia PDF Downloads 157

Authors: K. Almi, S. Lakel, A. Benchabane, A. Kriker

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The fiber–matrix compatibility can be improved if suitable enforcements are chosen. Whenever the reinforcements have more thermal stability, they can resist to the main processes for wood–thermoplastic composites. Several researches are focused on natural resources for the production of biomaterials intended for technical applications. Date palm wood present one of the world’s most important natural resource. Its use as insulating materials will help to solve the severe environmental and recycling problems which other artificial insulating materials caused. This paper reports the results of an experimental investigation on the thermal proprieties of date palm wood from Algeria. A study of physical, chemical and mechanical properties is also carried out. The goal is to use this natural material in the manufacture of thermal insulation materials for buildings. The local natural resources used in this study are the date palm fibers from Biskra oasis in Algeria. The results have shown that there is no significant difference in the morphological proprieties of the four types of residues. Their chemical composition differed slightly; with the lowest amounts of cellulose and lignin content belong to Petiole. Water absorption study proved that Rachis has a low value of sorption whereas Petiole and Fibrillium have a high value of sorption what influenced their mechanical properties. It is seen that the Rachis and leaflets exhibit a high tensile strength values compared to the other residue. On the other hand the low value of bulk density of Petiole and Fibrillium leads to high value of specific tensile strength and young modulus. It was found that the specific young modulus of Petiole and Fibrillium was higher than that of Rachis and Leaflets and that of other natural fibers or even artificial fibers. Compared to the other materials date palm wood provide a good thermal proprieties thus, date palm wood will be a good candidate for the manufacturing efficient and safe insulating materials.

Keywords: composite materials, date palm fiber, natural fibers, tensile tests, thermal proprieties

Procedia PDF Downloads 623

Authors: Gagik Ayvazyan, Levon Hakhoyan, Surik Khudaverdyan, Laura Lakhoyan

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Black Si (b-Si) is a nano-structured Si surface formed by a self-organized, maskless process with needle-like surfaces discernible by their black color. The combination of low reflectivity and the semi-conductive properties of Si found in b-Si make it a prime candidate for application in solar cells as an antireflection surface. However, surface recombination losses significantly reduce the efficiency of b-Si solar cells. Surface passivation using suitable dielectric films can minimize these losses. Nowadays some works have demonstrated that excellent passivation of b-Si nanostructures can be reached using Al₂O₃ films. However, the negative fixed charge present in Al₂O₃ films should provide good field effect passivation only for p- and p+-type Si surfaces. HfO2 thin films have not been practically tested for passivation of b-Si. HfO₂ could provide an alternative for n- and n+- type Si surface passivation since it has been shown to exhibit positive fixed charge. Using optical simulation by Finite-Difference Time Domain (FDTD) method, the possibility of b-Si passivation by HfO2 films has been analyzed. The FDTD modeling revealed that b-Si layers with HfO₂ films effectively suppress reflection in the wavelength range 400–1000 nm and across a wide range of incidence angles. The light-trapping performance primarily depends on geometry of the needles and film thickness. With the decrease of periodicity and increase of height of the needles, the reflectance decrease significantly, and the absorption increases significantly. Increase in thickness results in an even greater decrease in the calculated reflection coefficient of model structures and, consequently, to an improvement in the antireflection characteristics in the visible range. The excellent surface passivation and low reflectance results prove the potential of using the combination of the b-Si surface and the HfO₂ film for solar cells applications.

Keywords: antireflection, black silicon, HfO₂, passivation, simulation, solar cell

Procedia PDF Downloads 126

Authors: Jie Ren, Siyao Guo

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Laden with phosphates at a low pH value, sewage wastewater aggressive environments constitute a great threat to concrete-based pipes which is made of alkaline cementitious materials such as ordinary Portland cement (OPC). As a promising alternative for OPC-based binders, alkali-activated slag/fly ash (AASF) cementitious binders are generally believed to gain similar or better properties compared to OPC-based counterparts, especially durability. However, there is limited research on the performance of AASF binders in phosphoric acid solution. Moreover, the behavior of AASF binders composited with epoxy resin/TiO₂ when exposed to acidic media has been rarely explored. In this study, the performance of AASF paste with the precursor slag:fly ash (50:50 in mass ratio) enhanced with epoxy resin/TiO₂ composite in phosphoric acid solution (pH = 3.0-4.0) was investigated. The exposure towards acid attack lasted for 90 days. The same AASF mixture without resin/TiO₂ composite was used as a reference. The compressive strength and porous-related properties prior to acidic immersion were tested. The mass variations and degradation depth of the two mixtures of binders were also monitored which is based on phenolphthalein-videomicroscope method. The results show that the binder with epoxy resin/TiO₂ addition gained a higher compressive strength and lower water absorption than the reference. In addition, it also displayed a higher resistance towards acid attack indicated by a less mass loss and less degradation depth compared to the control sample. This improvement can be attributed to a dense microstructure evidenced by the higher compressive strength and related porous structures. It can be concluded that the microstructure can be improved by adding epoxy resin/TiO₂ composite in order to enhance the resistance of AASF binder towards acid attacks.

Keywords: alkali-activated paste, epoxy resin/TiO₂, composites, mechanical properties, phosphoric acid

Procedia PDF Downloads 103

Authors: Sonam Chorol, Sharvan Kumar, Pritam Mukhopadhyay

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In biology, supramolecular systems require the use of chemical fuels to stay in sustained nonequilibrium steady states termed dissipative self-assembly in contrast to synthetic self-assembly. Biomimicking these natural dynamic systems, some studies have demonstrated artificial self-assembly under nonequilibrium utilizing various forms of energies (fuel) such as chemical, redox, and pH. Naphthalene diimides (NDIs) are well-known organic molecules in supramolecular architectures with high electron affinity and have applications in controlled electron transfer (ET) reactions, etc. Herein, we report the endergonic ET from tetraphenylborate to highly electron-deficient phosphonium NDI²+ dication to generate NDI•+ radical. The formation of radicals was confirmed by UV-Vis-NIR absorption spectroscopy. Electron-donor and electron-acceptor energy levels were calculated from experimental electrochemistry and theoretical DFT analysis. The HOMO of the electron donor locates below the LUMO of the electro-acceptor. This indicates that electron transfer is endergonic (ΔE°ET = negative). The endergonic ET from NaBPh₄ to NDI²+ dication was achieved thermodynamically by the formation of coupled biphenyl product confirmed by GC-MS analysis. NDI molecule bearing octyl phosphonium at the core and H-bond forming imide moieties at the axial position forms a gel. The rheological properties of purified radical ion NDI⦁+ gels were evaluated. The atomic force microscopy studies reveal the formation of large branching-type networks with a maximum height of 70-80 nm. The endergonic ET from NaBPh₄ to NDI²+ dication was used to design the assembly and disassembly redox reaction cycle using reducing (NaBPh₄) and oxidizing agents (Br₂) as chemical fuels. A part of NaBPh₄ is used to drive assembly, while a fraction of the NaBPh₄ is dissipated by forming a useful product. The system goes back to the disassembled NDI²+ dication state with the addition of Br₂. We think bioinspired dissipative self-assembly is the best approach to developing future lifelike materials with autonomous behavior.

Keywords: Ionic-gel, redox-cycle, self-assembly, useful product

Procedia PDF Downloads 60

Authors: Merfat Algethami, Anton Blencowe, Bryce Feltis, Stephen Best, Moshi Geso

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Nano-materials with high atomic number atoms have been demonstrated to enhance the effective radiation dose and thus potentially could improve therapeutic efficacy in radiotherapy. The optimal nanoparticulate agents require high X-ray absorption coefficients, low toxicity, and should be cost effective. The focus of our research is the development of a nanoparticle therapeutic agent that can be used in radiotherapy to provide optimal enhancement of the radiation effects on the target. In this study, we used bismuth (Bi) nanoparticles coated with starch and bismuth sulphide nanoparticles (Bi2S3) coated with polyvinylpyrrolidone (PVP). These NPs are of low toxicity and are one of the least expensive heavy metal-based nanoparticles. The aims of this study were to synthesise Bi2S3 and Bi NPs, and examine their cytotoxicity to human lung adenocarcinoma epithelial cells (A549). The dose enhancing effects of NPs on A549 cells were examined at both KV and MV energies. The preliminary results revealed that bismuth based nanoparticles show increased radio-sensitisation of cells, displaying dose enhancement with KV X-ray energies and to a lesser degree for the MV energies. We also observed that Bi NPs generated a greater dose enhancement effect than Bi2S3 NPs in irradiated A549 cells. The maximum Dose Enhancement Factor (DEF) was obtained at lower energy KV range when cells treated with Bi NPs (1.5) compared to the DEF of 1.2 when cells treated with Bi2S3NPs. Less radiation dose enhancement was observed when using high energy MV beam with higher DEF value of Bi NPs treatment (1.26) as compared to 1.06 DEF value with Bi2S3 NPs. The greater dose enhancement was achieved at KV energy range, due the effect of the photoelectric effect which is the dominant process of interaction of X-ray. The cytotoxic effect of Bi NPs on enhancing the X-ray dose was higher due to the higher amount of elemental Bismuth present in Bi NPs compared to Bi2S3 NPs. The results suggest that Bismuth based NPs can be considered as valuable dose enhancing agents when used in clinical applications.

Keywords: A549 lung cancer cells, Bi2S3 nanoparticles, dose enhancement effect, radio-sensitising agents

Procedia PDF Downloads 258

Authors: Kumaran Letchmanan, Shou-Cang Shen, Wai Kiong Ng

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Postoperative implant-associated infections in soft tissues and bones remain a serious complication in orthopaedic surgery, which leads to impaired healing, re-implantation, prolong hospital stay and increase cost. Drug-loaded implants with sustained release of antibiotics at the local site are current research interest to reduce the risk of post-operative infections and osteomyelitis, thus, minimize the need for follow-up care and increase patient comfort. However, the improved drug release of the drug-loaded bone cements is usually accompanied by a loss in mechanical strength, which is critical for weight-bearing bone cement. Recently, more attempts have been undertaken to develop techniques to enhance the antibiotic elution as well as preserve the mechanical properties of the bone cements. The present study investigates the potential influence of addition of mesoporous silica nanoparticles (MSN) on the in vitro drug release kinetics of gentamicin (GTMC), along with the mechanical properties of bone cements. Simplex P was formulated with MSN and loaded with GTMC by direct impregnation. Meanwhile, Simplex P with water soluble poragen (xylitol) and high loading of GTMC as well as commercial bone cement CMW Smartset GHV were used as controls. MSN-formulated bone cements are able to increase the drug release of GTMC by 3-fold with a cumulative release of more than 46% as compared with other control groups. Furthermore, a sustained release could be achieved for two months. The loaded nano-sized MSN with uniform pore channels significantly build up an effective nano-network path in the bone cement facilitates the diffusion and extended release of GTMC. Compared with formulations using xylitol and high GTMC loading, incorporation of MSN shows no detrimental effect on biomechanical properties of the bone cements as no significant changes in the mechanical properties as compared with original bone cement. After drug release for two months, the bending modulus of MSN-formulated bone cements is 4.49 ± 0.75 GPa and the compression strength is 92.7 ± 2.1 MPa (similar to the compression strength of Simplex-P: 93.0 ± 1.2 MPa). The unaffected mechanical properties of MSN-formulated bone cements was due to the unchanged microstructures of bone cement, whereby more than 98% of MSN remains in the matrix and supports the bone cement structures. In contrast, the large portions of extra voids can be observed for the formulations using xylitol and high drug loading after the drug release study, thus caused compressive strength below the ASTM F541 and ISO 5833 minimum of 70 MPa. These results demonstrate the potential applicability of MSN-functionalized poly(methyl methacrylate)-based bone cement as a highly efficient, sustained and local drug delivery system with good mechanical properties.

Keywords: antibiotics, biomechanical properties, bone cement, sustained release

Procedia PDF Downloads 240

Authors: Cahya Wimar Wicaksono, Reynara Davin Chen, Alvian Kristianto Santoso

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Grasberg Cu-Au ore deposit as one of the biggest porphyry deposits located in Papua Province, Indonesia produced by several intrusion that restricted by Heavy Sulphide Zone (HSZ) in peripheral. HSZ is the rock that becomes the contact between Grassberg Igneous Complex (GIC) with sedimentary and igneous rock outside, which is rich in sulphide minerals such as pyrite ± pyrrhotite. This research is to obtain the characteristic of HSZ based on geotechnical, geochemical and mineralogy aspect and those implication for daily mining operational activities. Method used in this research are geological and alteration mapping, core logging, FAA (Fire Assay Analysis), AAS (Atomic absorption spectroscopy), RQD (Rock Quality Designation) and rock water content. Data generated from methods among RQD data, mineral composition and grade, lithological and structural geology distribution in research area. The mapping data show that HSZ material characteristics divided into three type based on rocks association, there are near igneous rocks, sedimentary rocks and on HSZ area. And also divided based on its location, north and south part of research area. HSZ material characteristic consist of rock which rich of pyrite ± pyrrhotite, and RQD range valued about 25%-100%. Pyrite ± pyrrhotite which outcropped will react with H₂O and O₂ resulting acid that generates corrosive effect on steel wire and rockbolt. Whereas, pyrite precipitation proses in HSZ forming combustible H₂S gas which is harmful during blasting activities. Furthermore, the impact of H₂S gas in blasting activities is forming poison gas SO₂. Although HSZ high grade Cu-Au, however those high grade Cu-Au rich in sulphide components which is affected in flotation milling process. Pyrite ± pyrrhotite in HSZ will chemically react with Cu-Au that will settle in milling process instead of floating.

Keywords: combustible, corrosive, heavy sulphide zone, pyrite ± pyrrhotite

Procedia PDF Downloads 309

Authors: Ranadhir Roy

Abstract:

Inverse problems arise in medical (molecular) imaging. These problems are characterized by large in three dimensions, and by the diffusion equation which models the physical phenomena within the media. The inverse problems are posed as a nonlinear optimization where the unknown parameters are found by minimizing the difference between the predicted data and the measured data. To obtain a unique and stable solution to an ill-posed inverse problem, a priori information must be used. Mathematical conditions to obtain stable solutions are established in Tikhonov’s regularization method, where the a priori information is introduced via a stabilizing functional, which may be designed to incorporate some relevant information of an inverse problem. Effective determination of the Tikhonov regularization parameter requires knowledge of the true solution, or in the case of optical imaging, the true image. Yet, in, clinically-based imaging, true image is not known. To alleviate these difficulties we have applied the penalty/modified barrier function (PMBF) method instead of Tikhonov regularization technique to make the inverse problems well-posed. Unlike the Tikhonov regularization method, the constrained optimization technique, which is based on simple bounds of the optical parameter properties of the tissue, can easily be implemented in the PMBF method. Imposing the constraints on the optical properties of the tissue explicitly restricts solution sets and can restore uniqueness. Like the Tikhonov regularization method, the PMBF method limits the size of the condition number of the Hessian matrix of the given objective function. The accuracy and the rapid convergence of the PMBF method require a good initial guess of the Lagrange multipliers. To obtain the initial guess of the multipliers, we use a least square unconstrained minimization problem. Three-dimensional images of fluorescence absorption coefficients and lifetimes were reconstructed from contact and noncontact experimentally measured data.

Keywords: constrained minimization, ill-conditioned inverse problems, Tikhonov regularization method, penalty modified barrier function method

Procedia PDF Downloads 256

Authors: Feiyu Yang, Chunfang Ni, Rong Wang, Yun Zou, Wenbin Liu, Chenggong Zhang, Fenjin Sun, Chun Wang

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Cocaine is the most frequently used illegal drug globally, with the global annual prevalence of cocaine used ranging from 0.3% to 0.4 % of the adult population aged 15–64 years. Growing consumption trend of abused cocaine and drug crimes are a great concern, therefore urine sample testing has become an important noninvasive sampling whereas cocaine and its metabolites (COCs) are usually present in high concentrations and relatively long detection windows. However, direct analysis of urine samples is not feasible because urine complex medium often causes low sensitivity and selectivity of the determination. On the other hand, presence of low doses of analytes in urine makes an extraction and pretreatment step important before determination. Especially, in gathered taking drug cases, the pretreatment step becomes more tedious and time-consuming. So developing a sensitive, rapid and high-throughput method for detection of COCs in human body is indispensable for law enforcement officers, treatment specialists and health officials. In this work, a new automated magnetic dispersive solid-phase extraction (MDSPE) sampling method followed by high performance liquid chromatography-mass spectrometry (HPLC-MS) was developed for quantitative enrichment of COCs from human urine, using prepared magnetic nanoparticles as absorbants. The nanoparticles were prepared by silanizing magnetic Fe3O4 nanoparticles and modifying them with divinyl benzene and vinyl pyrrolidone, which possesses the ability for specific adsorption of COCs. And this kind of magnetic particle facilitated the pretreatment steps by electromagnetically controlled extraction to achieve full automation. The proposed device significantly improved the sampling preparation efficiency with 32 samples in one batch within 40mins. Optimization of the preparation procedure for the magnetic nanoparticles was explored and the performances of magnetic nanoparticles were characterized by scanning electron microscopy, vibrating sample magnetometer and infrared spectra measurements. Several analytical experimental parameters were studied, including amount of particles, adsorption time, elution solvent, extraction and desorption kinetics, and the verification of the proposed method was accomplished. The limits of detection for the cocaine and cocaine metabolites were 0.09-1.1 ng·mL-1 with recoveries ranging from 75.1 to 105.7%. Compared to traditional sampling method, this method is time-saving and environmentally friendly. It was confirmed that the proposed automated method was a kind of highly effective way for the trace cocaine and cocaine metabolites analyses in human urine.

Keywords: automatic magnetic dispersive solid-phase extraction, cocaine detection, magnetic nanoparticles, urine sample testing

Procedia PDF Downloads 184

Authors: Sanjay Kumar, Dinesh Pathak, Sudhir Saralch

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Copper oxide is a semiconductor that has been studied for several reasons such as the natural abundance of starting material copper (Cu); the easiness of production by Cu oxidation; their non-toxic nature and the reasonably good electrical and optical properties. Copper oxide is well-known as cuprite oxide. The cuprite is p-type semiconductors having band gap energy of 1.21 to 1.51 eV. As a p-type semiconductor, conduction arises from the presence of holes in the valence band (VB) due to doping/annealing. CuO is attractive as a selective solar absorber since it has high solar absorbency and a low thermal emittance. CuO is very promising candidate for solar cell applications as it is a suitable material for photovoltaic energy conversion. It has been demonstrated that the dip technique can be used to deposit CuO films in a simple manner using metallic chlorides (CuCl₂.2H₂O) as a starting material. Copper oxide films are prepared using a methanolic solution of cupric chloride (CuCl₂.2H₂O) at three baking temperatures. We made three samples, after heating which converts to black colour. XRD data confirm that the films are of CuO phases at a particular temperature. The optical band gap of the CuO films calculated from optical absorption measurements is 1.90 eV which is quite comparable to the reported value. Dip technique is a very simple and low-cost method, which requires no sophisticated specialized setup. Coating of the substrate with a large surface area can be easily obtained by this technique compared to that in physical evaporation techniques and spray pyrolysis. Another advantage of the dip technique is that it is very easy to coat both sides of the substrate instead of only one and to deposit otherwise inaccessible surfaces. This method is well suited for applying coating on the inner and outer surfaces of tubes of various diameters and shapes. The main advantage of the dip coating method lies in the fact that it is possible to deposit a variety of layers having good homogeneity and mechanical and chemical stability with a very simple setup. In this paper, the CuO thin films preparation by dip coating method and their characterization will be presented.

Keywords: absorber material, cupric oxide, dip coating, thin film

Procedia PDF Downloads 294

Authors: Manisha Bal, Remya Chinnamma Jose, B.C. Meikap

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Dust particles suspended in air are a major source of air pollution. A self-priming submerged venturi scrubber proven very effective in cases of handling nuclear power plant accidents is an efficient device to remove dust particles from the air and thus aids in pollution control. Venturi scrubbers are compact, have a simple mode of operation, no moving parts, easy to install and maintain when compared to other pollution control devices and can handle high temperatures and corrosive and flammable gases and dust particles. In the present paper, fly ash particles recognized as a high air pollutant substance emitted mostly from thermal power plants is considered as the dust particle. Its exposure through skin contact, inhalation and indigestion can lead to health risks and in severe cases can even root to lung cancer. The main focus of this study is on the removal of fly ash particles from polluted air using a self-priming venturi scrubber in submerged conditions using water as the scrubbing liquid. The venturi scrubber comprising of three sections: converging section, throat and diverging section is submerged inside a water tank. The liquid enters the throat due to the pressure difference composed of the hydrostatic pressure of the liquid and static pressure of the gas. The high velocity dust particles atomize the liquid droplets at the throat and this interaction leads to its absorption into water and thus removal of fly ash from the air. Detailed investigation on the scrubbing of fly ash has been done in this literature. Experiments were conducted at different throat gas velocities, water levels and fly ash inlet concentrations to study the fly ash removal efficiency. From the experimental results, the highest fly ash removal efficiency of 99.78% is achieved at the throat gas velocity of 58 m/s, water level of height 0.77m with fly ash inlet concentration of 0.3 x10⁻³ kg/Nm³ in the submerged condition. The effect of throat gas velocity, water level and fly ash inlet concentration on the removal efficiency has also been evaluated. Furthermore, experimental results of removal efficiency are validated with the developed empirical model.

Keywords: dust particles, fly ash, pollution control, self-priming venturi scrubber

Procedia PDF Downloads 148