Search results for: signal synthesis

Authors: Cigdem Karaaslan, Yalcin Duydu, Aylin Ustundag, Can Ozgur Yalcın, Hakan Goker

Abstract:

Benzazole nucleus is found in the structure of many compounds as anticancer agents. Bendamustine (Alkylating agent), Nocodazole (Mitotic inhibitor), Veliparib (PARP inhibitor), Glasdegib (SMO inhibitor) are clinically used as anticancer therapeutics which bearing benzimidazole moiety. Based on the principle of bioisosterism in the present work, 23 compounds belonging to 2-(3,4-dimethoxy-phenyl) benzazoles and imidazopyridine series were synthesized and evaluated for their anticancer activities. N-(5-Chloro-2-hydroxyphenyl)-3,4-dimethoxybenzamide, was obtained by the amidation of 2-hydroxy-5-chloroaniline with 3,4-dimethoxybenzoic acid by using 1,1'-carbonyldiimidazole. Cyclization of benzamide derivative to benzoxazole, was achieved by p-toluenesulfonic acid. Other 1H-benz (or pyrido) azoles were prepared by the reaction between 2-aminothiophenol, o-phenylenediamine, o-pyridinediamine with sodium metabisulfite adduct of 3,4-dimethoxybenzaldehyde. The NMR assignments of the dimethoxy groups were established by the Nuclear Overhauser Effect Spectroscopy. A compound named, 5(4),7(6)-Dichloro-2-(3,4-dimethoxy) phenyl-1H-benzimidazole, bearing two chlorine atoms at the 5(4) and 7(6) positions of the benzene moiety of benzimidazole was found the most potent analogue, against A549 cells with the GI50 value of 1.5 µg/mL. In addition, 2-(3,4-Dimethoxyphenyl)-5,6-dimethyl-1H-benzimi-dazole showed remarkable cell growth inhibition against MCF-7 and HeLa cells with the GI₅₀ values of 7 and 5.5 µg/mL, respectively. It could be concluded that introduction of di-chloro atoms at the phenyl ring of 2-(3,4-dimethoxyphenyl)-1H-benzimidazoles increase significant cytotoxicity to selected human tumor cell lines in comparison to other all benzazoles synthesized in this study. Unsubstituted 2-(3,4-dimethoxyphenyl) imidazopyridines also gave the good inhibitory profile against A549 and HeLa cells.

Keywords: 3, 4-Dimethoxyphenyl, 1H-benzimidazole, benzazole, imidazopyridine

Procedia PDF Downloads 122

Authors: Sylvain Caillol, Maxence Fache, Bernard Boutevin

Abstract:

Recent years have witnessed an increasing demand on renewable resource-derived polymers owing to increasing environmental concern and restricted availability of petrochemical resources. Thus, a great deal of attention was paid to renewable resources-derived polymers and to thermosetting materials especially, since they are crosslinked polymers and thus cannot be recycled. Also, most of thermosetting materials contain aromatic monomers, able to confer high mechanical and thermal properties to the network. Therefore, the access to biobased, non-harmful, and available aromatic monomers is one of the main challenges of the years to come. Starting from phenols available in large volumes from renewable resources, our team designed platforms of chemicals usable for the synthesis of various polymers. One of these phenols, vanillin, which is readily available from lignin, was more specifically studied. Various aromatic building blocks bearing polymerizable functions were synthesized: epoxy, amine, acid, carbonate, alcohol etc. These vanillin-based monomers can potentially lead to numerous polymers. The example of epoxy thermosets was taken, as there is also the problematic of bisphenol A substitution for these polymers. Materials were prepared from the biobased epoxy monomers obtained from vanillin. Their thermo-mechanical properties were investigated and the effect of the monomer structure was discussed. The properties of the materials prepared were found to be comparable to the current industrial reference, indicating a potential replacement of petrosourced, bisphenol A-based epoxy thermosets by biosourced, vanillin-based ones. The tunability of the final properties was achieved through the choice of monomer and through a well-controlled oligomerization reaction of these monomers. This follows the same strategy than the one currently used in industry, which supports the potential of these vanillin-derived epoxy thermosets as substitutes of their petro-based counterparts.

Keywords: lignin, vanillin, epoxy, amine, carbonate

Procedia PDF Downloads 237

Authors: Jungkyun Im

Abstract:

Nonsteroidal anti-inflammatory drugs (NSAIDs) are effective for relieving pain and reducing inflammation. They are nonselective inhibitors of two isoforms of COX, cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2), and thereby inhibiting the production of hormone-like lipid compounds such as, prostaglandins and thromboxanes which cause inflammation, pain, fever, platelet aggregation, etc. In addition, recently there are many research articles reporting the neuroprotective effect of NSAIDs in neurodegenerative diseases, such as Alzheimer’s disease (AD) and Parkinson’s disease (PD). However, the clinical use of NSAIDs in these diseases is limited by low brain distribution. Therefore, in order to assist the in-depth investigation on the pharmaceutical mechanism of flurbiprofen in neuroprotection and to make flurbiprofen a more potent drug to prevent or alleviate neurodegenerative diseases, delivery of flurbiprofen to brain should be effective and sufficient amount of flurbiprofen must penetrate the BBB thus gaining access into the patient’s brain. We have recently developed several types of guanidine-rich molecular carriers with high molecular weights and good water solubility that readily cross the blood-brain barrier (BBB) and display efficient distributions in the mouse brain. The G8 (having eight guanidine groups) molecular carrier based on D-sorbitol was found to be very effective in delivering anticancer drugs to a mouse brain. In the present study, employing the same molecular carrier, we prepared the flurbiprofen conjugate and studied its BBB permeation by mouse tissue distribution study. Flurbiprofen was attached to a molecular carrier with a fluorescein probe and multiple terminal guanidiniums. The conjugate was found to internalize into live cells and readily cross the BBB to enter the mouse brain. Our novel synthetic flurbiprofen conjugate will hopefully delivery NSAIDs into brain, and is therefore applicable to the neurodegenerative diseases treatment or prevention.

Keywords: flurbiprofen, drug delivery, molecular carrier, organic synthesis

Procedia PDF Downloads 235

Authors: Shuofen Hsu, Ya-Yi Chao, Chao-Wei Li

Abstract:

This paper investigates the factors of whether firms’ quarterly consolidated financial statements to be voluntary reviewed by auditor. To promote the information transparency, the Financial Supervisory Commission of Executive Yuan in Taiwan ruled the Taiwanese listed companies should announce the first and third quarterly consolidated financial statements since 2008 to 2012, while the Commission didn’t require the consolidated financial statements should be reviewed by auditors. This is a very special practice in emerging market, especially in Taiwan. The valuable data of this period is suitable for us to research the determinants of firms’ voluntary review decision in emerging markets. We collected the auditors' report of each company and each year of Taiwanese listed companies since 2008 to 2012 for our research samples. We use probit model to test and analyze the determinants of voluntary review decision of the first and third quarterly consolidated financial statements. Our empirical result shows that the firms whose first and third quarterly consolidated financial statements are voluntary to be reviewed by auditors have better ranking of information transparency, higher audit quality, and better corporate governance, suggesting that voluntary review is a good signal to firms’ better information and corporate governance quality.

Keywords: voluntary review, information transparency, audit quality, quarterly consolidated financial statements

Procedia PDF Downloads 256

Authors: Yilin Ma, Zhaomiao Liu, Xiang Wang, Yan Pang

Abstract:

Microscale droplets play an increasingly important role in various applications, including medical diagnostics, material synthesis, chemical engineering, and cell research due to features of high surface-to-volume ratio and tiny scale, which can significantly improve reaction rates, enhance heat transfer efficiency, enable high-throughput parallel studies as well as reduce reagent usage. As a mature technique to manipulate small amounts of liquids, droplet microfluidics could achieve the precise control of droplet parameters such as size, uniformity, structure, and thus has been widely adopted in the engineering and scientific research of multiple fields. Necking processes of the droplet in the cross junction microchannels are experimentally and theoretically investigated and dynamic mechanisms of the neck thinning in two different regimes are revealed. According to evolutions of the minimum neck width and the thinning rate, the necking process is further divided into different stages and the main driving force during each stage is confirmed. Effects of the flow rates and the cross-sectional aspect ratio on the necking process as well as the neck profile at different stages are provided in detail. The distinct features of the two regimes in the squeezing stage are well captured by the theoretical estimations of the effective flow rate and the variations of the actual flow rates in different channels are reasonably reflected by the channel width ratio. In the collapsing stage, the quantitative relation between the minimum neck width and the remaining time is constructed to identify the physical mechanism.

Keywords: cross junction, neck thinning, force analysis, inertial mechanism

Procedia PDF Downloads 114

Authors: C. Rajalakshmi, Vibin Ipe Thomas

Abstract:

Sonogashira coupling reactions are widely employed in the synthesis of molecules of biological and pharmaceutical importance. Copper catalyzed Sonogashira coupling reactions are gaining importance owing to the low cost and less toxicity of copper as compared to the palladium catalyst. In the present work, a detailed computational study has been carried out on the Sonogashira coupling reaction between aryl halides and terminal alkynes catalyzed by Copper (I) species with trans-1, 2 Diaminocyclohexane as ligand. All calculations are performed at Density Functional Theory (DFT) level, using the hybrid Becke3LYP functional. Cu and I atoms are described using an effective core potential (LANL2DZ) for the inner electrons and its associated double-ζ basis set for the outer electrons. For all other atoms, 6-311G+* basis set is used. We have identified that the active catalyst species is a neutral 3-coordinate trans-1,2 diaminocyclohexane ligated Cu (I) alkyne complex and found that the oxidative addition and reductive elimination occurs in a single step proceeding through one transition state. This is owing to the ease of reductive elimination involving coupling of Csp2-Csp carbon atoms and the less stable Cu (III) intermediate. This shows the mechanism of copper catalyzed Sonogashira coupling reactions are quite different from those catalyzed by palladium. To gain further insights into the mechanism, substrates containing various functional groups are considered in our study to traverse their effect on the feasibility of the reaction. We have also explored the effect of ligand on the catalytic cycle of the coupling reaction. The theoretical results obtained are in good agreement with the experimental observation. This shows the relevance of a combined theoretical and experimental approach for rationally improving the cross-coupling reaction mechanisms.

Keywords: copper catalysed, density functional theory, reaction mechanism, Sonogashira coupling

Procedia PDF Downloads 120

Authors: Majid Farsadrouh Rashti, Parisa Jahani, Amir Shafiee, Mehrdad Mofidi

Abstract:

The dihydroxybenzene isomers, hydroquinone (HQ), catechol (CC) and resorcinol (RS) have been widely recognized as important environmental pollutants due to their toxicity and low degradability in the ecological environment. Speciation of HQ, CC and RS is very important for environmental analysis because they co-exist of these isomers in environmental samples and are too difficult to degrade as an environmental contaminant with high toxicity. There are many analytical methods have been reported for detecting these isomers, such as spectrophotometry, fluorescence, High-performance liquid chromatography (HPLC) and electrochemical methods. These methods have attractive advantages such as simple and fast response, low maintenance costs, wide linear analysis range, high efficiency, excellent selectivity and high sensitivity. A novel modified glassy carbon electrode (GCE) with Pd@ Cu/CNTs core−shell nanowires for the simultaneous determination of hydroquinone (HQ), catechol (CC) and resorcinol (RS) is described. A detailed investigation by field emission scanning electron microscopy and electrochemistry was performed in order to elucidate the preparation process and properties of the GCE/ Pd/CuNWs-CNTs. The electrochemical response characteristic of the modified GPE/LFOR toward HQ, CC and RS were investigated by cyclic voltammetry, differential pulse voltammetry (DPV) and Chronoamperometry. Under optimum conditions, the calibrations curves were linear up to 228 µM for each with detection limits of 0.4, 0.6 and 0.8 µM for HQ, CC and RS, respectively. The diffusion coefficient for the oxidation of HQ, CC and RS at the modified electrode was calculated as 6.5×10⁻⁵, 1.6 ×10⁻⁵ and 8.5 ×10⁻⁵ cm² s⁻¹, respectively. DPV was used for the simultaneous determination of HQ, CC and RS at the modified electrode and the relative standard deviations were 2.1%, 1.9% and 1.7% for HQ, CC and RS, respectively. Moreover, GCE/Pd/CuNWs-CNTs was successfully used for determination of HQ, CC and RS in real samples.

Keywords: dihydroxybenzene isomers, galvanized copper nanowires, electrochemical sensor, Palladium, speciation

Procedia PDF Downloads 131

Authors: Lingxia Li, Frédéric Schnell, Shuzhe Ding, Solène Le Douairon Lahaye

Abstract:

Background: The risk of sudden cardiac arret/death (SCA/D) in athletes is controversial. There is a lack of meta-analyses assessing the sex differences in the risk of SCA/D in competitive athletes. Purpose: The aim of the present study was to evaluate sex differences in the incidence of SCA/D in competitive athletes using meta-analyses. Methods: The systematic review was registered in the PROSPERO database (registration ID: CRD42023432022) and was conducted according to the PRISMA guidelines. PubMed, Embase, Scopus, SPORT Discus and Cochrane Library were searched up to July 2023. To avoid systematic bias in data pooling, only studies with data for both sexes were included. Results: From the 18 included studies, 2028 cases of SCA/D were observed (males 1821 (89.79%), females 207 (10.21%)). The age ranges from the adolescents (<26 years) to the elderly (>45 years). The incidence in male athletes was 1.32/100,000 AY (95% CI: [0.90, 1.93]) and in females was 0.26/100,000 AY (95% CI: [0.16, 0.43]), the incidence rate ratio (IRR) was 6.43 (95% CI: [4.22, 9.79]). The subgroup synthesis showed a higher incidence in males than in females in both age groups <25 years and ≤35 years, the IRR was 5.86 (95% CI: [4.69, 7.32]) and 5.79 (95% CI: [4.73, 7.09]), respectively. When considering the events, the IRR was 6.73 (95%CI: [3.06, 14.78]) among studies involving both SCA/D events and 7.16 (95% CI: [4.93, 10.40]) among studies including only cases of SCD. The available clinical evidence showed that cardiac events were most frequently seen in long-distance running races (26, 35.1%), marathon (16, 21.6%) and soccer (10, 13.5%). Coronary artery disease (14, 18.9%), hypertrophic cardiomyopathy (8, 10.8%), and arrhythmogenic right ventricular cardiomyopathy (7, 9.5%) are the most common causes of SCA/D in competitive athletes. Conclusion: The meta-analysis provides evidence of sex differences in the incidence of SCA/D in competitive athletes. The incidence of SCA/D in male athletes was 6 to 7 times higher than in females. Identifying the reasons for this difference may have implications for targeted the prevention of fatal evets in athletes.

Keywords: incidence, sudden cardiac arrest, sudden cardiac death, sex difference, athletes

Procedia PDF Downloads 70

Authors: Samuel K. Degife, Kamal K. Pant, Sapna Jain

Abstract:

The world´s population and industrialization of countries continued to grow in an alarming rate irrespective of the security for food, energy supply, and pure water availability. As a result, the global energy consumption is observed to increase significantly. Fossil energy resources that mainly comprised of crude oil, coal, and natural gas have been used by mankind as the main energy source for almost two centuries. However, sufficient evidences are revealing that the consumption of fossil resource as transportation fuel emits environmental pollutants such as CO2, NOx, and SOx. These resources are dwindling rapidly besides enormous amount of problems associated such as fluctuation of oil price and instability of oil-rich regions. Biomass is a promising renewable energy candidate to replace fossil-based transportation fuel and chemical production. The present study aims at valorization of hexose sugars (glucose and fructose) using zeolite based catalysts in imidazolium based ionic liquid (1-butyl-3-methylimidazolium chloride, [BMIM] Cl) reaction media. The catalytic effect chromium impregnated H-ZSM-5 (Cr/H-ZSM-5) was studied for dehydration of hexose sugars. The wet impregnation method was used to prepare Cr/H-ZSM-5 catalyst. The characterization of the prepared catalyst was performed using techniques such as Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction analysis (XRD), Temperature-programmed desorption of ammonia (NH3-TPD) and BET-surface area analysis. The dehydration product, 5-hydroxymethylfurfural (5-HMF), was analyzed using high-performance liquid chromatography (HPLC). Cr/H-ZSM-5 was effective in dehydrating fructose with 87% conversion and 55% yield 5-HMF at 180 oC for 30 min of reaction time compared with H-ZSM-5 catalyst which yielded only 31% of 5-HMF at identical reaction condition.

Keywords: chromium, hexose, ionic liquid, , zeolite

Procedia PDF Downloads 179

Authors: Mandeep Kaur, Jitendra K. Bera

Abstract:

The search for atom-economical and green synthetic methods for the synthesis of functionalized molecules has attracted much attention. Metal ligand cooperation (MLC) plays a pivotal role in organometallic catalysis to activate C−H, H−H, O−H, N−H and B−H bonds through reversible bond breaking and bond making process. Towards this goal, a bifunctional N─heterocyclic carbene (NHC) based pyridyl-functionalized amide ligand precursor, and corresponding dearomatized iridium complex was synthesized. The NMR and UV/Vis acid titration study have been done to prove the proton response nature of the iridium complex. Further, the dearomatized iridium complex explored as a catalyst on the platform of MLC via dearomatzation/aromatization mode of action towards atom economical α and β─alkylation of ketones and secondary alcohols by using primary alcohols through hydrogen borrowing methodology. The key features of the catalysis are high turnover frequency (TOF) values, low catalyst loading, low base loading and no waste product. The greener syntheses of quinoline, lactone derivatives and selective alkylation of drug molecules like pregnenolone and testosterone were also achieved successfully. Another structurally similar iridium complex was also synthesized with modified ligand precursor where a pendant amide unit was absent. The inactivity of this analogue iridium complex towards catalysis authenticated the participation of proton responsive imido sidearm of the ligand to accelerate the catalytic reaction. The mechanistic investigation through control experiments, NMR and deuterated labeling study, authenticate the borrowing hydrogen strategy.

Keywords: C-C bond formation, hydrogen borrowing, metal ligand cooperation (MLC), n-heterocyclic carbene

Procedia PDF Downloads 184

Authors: Marcela de Oliveira, Guilherme Giacomini, Allan Felipe Fattori Alves, Ana Luiza Menegatti Pavan, Maria Eugenia Dela Rosa, Fernando Antonio Bacchim Neto, Diana Rodrigues de Pina

Abstract:

It is estimated that each year one death every 10 seconds (about 2 million deaths) in the world is attributed to tuberculosis (TB). Even after effective treatment, TB leaves sequelae such as, for example, pulmonary fibrosis, compromising the quality of life of patients. Evaluations of the aforementioned sequel are usually performed subjectively by radiology specialists. Subjective evaluation may indicate variations inter and intra observers. The examination of x-rays is the diagnostic imaging method most accomplished in the monitoring of patients diagnosed with TB and of least cost to the institution. The application of computational algorithms is of utmost importance to make a more objective quantification of pulmonary impairment in individuals with tuberculosis. The purpose of this research is the use of computer algorithms to quantify the pulmonary impairment pre and post-treatment of patients with pulmonary TB. The x-ray images of 10 patients with TB diagnosis confirmed by examination of sputum smears were studied. Initially the segmentation of the total lung area was performed (posteroanterior and lateral views) then targeted to the compromised region by pulmonary sequel. Through morphological operators and the application of signal noise tool, it was possible to determine the compromised lung volume. The largest difference found pre- and post-treatment was 85.85% and the smallest was 54.08%.

Keywords: algorithm, radiology, tuberculosis, x-rays exam

Procedia PDF Downloads 423

Authors: Hazel Ann Gianelli Cu, Stephanie Co, Radcliff Cobankiat

Abstract:

Objectives: TRC101/Veverimer is an orally administered, non absorbed, sodium- and counterion-free hydrochloric acid binder for the treatment of metabolic acidosis associated with chronic kidney disease. The main objective of this study is to determine the efficacy of TRC 101/ Veverimer 6g/day in increasing serum bicarbonate levels of chronic kidney disease patients with metabolic acidosis. In this meta analysis, we also aim to look at safety outcomes, adverse effects and if the level of serum bicarbonate reached metabolic alkalosis when given TRC101/Veverimer. Methodology: Pubmed, Cochrane, Google Scholar and Science direct were used to search for randomized controlled trials about TRC101/Veverimer use in Chronic kidney disease patients with metabolic acidosis. Search strategy according to the Prisma checklist was done with evaluation of biases and synthesis of results using the Cochrane Review Manager software 5.4. Results: Two randomized controlled trials involving 371 chronic kidney disease patients were included in this study. Results show there was a significant increase in the serum bicarbonate level when given TRC101/Veverimer compared to the placebo. Both studies had a significant number of participants who completed the studies until the end. P value of <0.00001 was used in both studies with a confidence interval of 95%. Conclusion: TRC101/Veverimer 6g/day was shown to effectively and safely increase serum bicarbonate or achieve normalization in chronic kidney disease patients with metabolic acidosis as compared with a placebo. This was associated with delayed progression of kidney disease with improvement of physical functioning, however longer duration of future studies is ideal in order to assess further the long advantages and consequences of TRC 101/Veverimer.

Keywords: chronic kidney disease, metabolic acidosis, Veverimer, TRC101

Procedia PDF Downloads 200

Authors: E. A. Alshaafi, A. Prakash

Abstract:

Oil-water emulsions are commonly encountered in various industrial operations and at different stages of crude oil production and processing. Emulsions are often difficult to track and treat and can cause a number of costly problems which need to be avoided. The characteristics of the emulsion phase can vary with crude composition and types of impurities present in oil. The objectives of this study are the development of ultrasonic techniques to track and characterize emulsion phase generated during production and cleaning of crude oil. The position of emulsion layer is monitored with the help of ultrasonic probes suitably placed in the vessel. The sensitivity of the technique and its potential has been demonstrated based on extensive testing with different oil samples. The technique is also being developed to monitor emulsion phase characteristics such as stability, composition, and droplet size distribution. The ultrasonic parameters recorded are changes in acoustic velocity, signal attenuation and its frequency spectrum. Emulsion has been prepared with light mineral oil sample and the effects of various factors including mixing speed, temperature, surfactant, and solid particles concentrations have been investigated. The applied frequency for ultrasonic waves has been varied from 1 to 5 MHz to carry out a sensitivity analysis. Emulsion droplet structure is observed with optical microscopy and stability is examined by tracking the changes in ultrasonic parameters with time. A model based on ultrasonic attenuation spectroscopy is being developed and tested to track changes in droplet size distribution with time.

Keywords: ultrasonic techniques, emulsion, characterization, droplet size

Procedia PDF Downloads 178

Authors: Chetna Tyagi. G. B. V. S. Lakshmi, Ambuj Tripathi, D. K. Avasthi

Abstract:

Graphene oxide provides a good host matrix for preparing nanocomposites due to the different functional groups attached to its edges and planes. Being biocompatible, it is used in therapeutic applications. As enzyme-based biosensor requires complicated enzyme purification procedure, high fabrication cost and special storage conditions, we need enzyme-less biosensors for use even in a harsh environment like high temperature, varying pH, etc. In this work, we have prepared both enzyme-based and enzyme-less graphene oxide-based biosensors for glucose detection using glucose-oxidase as enzyme and gold nanoparticles, respectively. These samples were characterized using X-ray diffraction, UV-visible spectroscopy, scanning electron microscopy, and transmission electron microscopy to confirm the successful synthesis of the working electrodes. Electrochemical measurements were performed for both the working electrodes using a 3-electrode electrochemical cell. Cyclic voltammetry curves showed the homogeneous transfer of electron on the electrodes in the scan range between -0.2V to 0.6V. The sensing measurements were performed using differential pulse voltammetry for the glucose concentration varying from 0.01 mM to 20 mM, and sensing was improved towards glucose in the presence of gold nanoparticles. Gold nanoparticles in graphene oxide nanocomposite played an important role in sensing glucose in the absence of enzyme, glucose oxidase, as evident from these measurements. The selectivity was tested by measuring the current response of the working electrode towards glucose in the presence of the other common interfering agents like cholesterol, ascorbic acid, citric acid, and urea. The enzyme-less working electrode also showed storage stability for up to 15 weeks, making it a suitable glucose biosensor.

Keywords: electrochemical, enzyme-less, glucose, gold nanoparticles, graphene oxide, nanocomposite

Procedia PDF Downloads 146

Authors: C. Babu Rao, Pandian Chelliah

Abstract:

Owing to their reliability, a number of fluorescent spectra based fiber optic sensors have been developed for detection and identification of hazardous chemicals such as explosives, narcotics etc. In High security regions, such as airports, it is important to monitor simultaneously multiple locations. This calls for deployment of a portable sensor at each location. However, the selectivity and sensitivity of these techniques depends on the spectral resolution of the spectral analyzer. The better the resolution the larger the repertoire of chemicals that can be detected. A portable unit will have limitations in meeting these requirements. Optical fibers can be employed for collecting and transmitting spectral signal from the portable sensor head to a sensitive central spectral analyzer (CSA). For multipoint sensing, optical multiplexing of multiple sensor heads with CSA has to be adopted. However with multiplexing, when one sensor head is connected to CSA, the rest may remain unconnected for the turn-around period. The larger the number of sensor heads the larger this turn-around time will be. To circumvent this imitation, we propose in this paper, an optical encoding methodology to use multiple portable sensor heads connected to a single CSA. Each portable sensor head is assigned an unique address. Spectra of every chemical detected through this sensor head, are encoded by its unique address and can be identified at the CSA end. The methodology proposed is demonstrated through a simulation using Matlab SIMULINK.

Keywords: optical encoding, fluorescence, multipoint sensing

Procedia PDF Downloads 713

Authors: Nuray Yilmaz Baran, Mehmet Saçak

Abstract:

Schiff base polymers are one class of conjugated polymers, also called as poly(azomethines). They have drawn the attention of researchers in recent years due to their some properties such as, optoelectronic, semiconductive, and photovoltaic, antimicrobial activities and high thermal stability. In this study, Poly(2-[[4-(dimethylamino)benzylidene]amino] phenol) P(2-DBAP), which is a Schiff base polymer, was synthesized by an oxidative polycondensation reaction of -[[4-(dimethylamino)benzylidene]amino]phenol (2-DBAP) with oxidants NaOCl, H₂O₂ and O₂ in various organic medium. At the end of the polymerizations carried out at various temperatures and time, maximum conversion of the monomer to the polymer could be obtained as around 93.7 %. The structures of the monomer and polymer were characterized by UV-Vis, FTIR and ¹HNMR techniques. Thermal analysis of the polymer was identified by TG-DTG and DTA techniques, and the thermal degradation behavior was supported by Thermo-IR spectra recorded in the temperature range of 25-800 °C. The number average molecular weight (Mn), weight average molecular weight (Mw) and polydispersity index (PDI) of the polymer were found to be 26337, 9860 g/mol 2.67, respectively. The change of electrical conductivity value of the P(2-DBAP) doped with iodine vapor at different temperatures and time was investigated its maximum was measured by increasing 10¹⁰ fold as 2 x10⁻⁴ Scm⁻¹ after doping for 48 h at 60 °C. Antibacterial and antifungal activities of P(2-DBAP) Schiff base and its polymer were also investigated against Sarcina lutea, Enterobacter aerogenes, Escherichia coli, Enterococcus Faecalis, Klebsiella pneumoniae, Bacillus subtilis, and Candida albicans, Saccharomyces cerevisiae, respectively.

Keywords: conductive properties, polyazomethines, polycondensation reaction, Schiff base polymers, thermal stability

Procedia PDF Downloads 290

Authors: H. Sakamoto, J. Tochimoto, S. Kurosawa, M. Suzuki, S. Oguri

Abstract:

Salt stress adversely affects plant growth at various stages of development including seed germination, seedling establishment, vegetative growth and finally reproduction. Because of their immobile nature, plants have evolved mechanisms to sense and respond to salt stress. Seed dormancy is an adaptive trait that enables seed germination to coincide with favorable environmental conditions. We identified a novel locus of Arabidopsis, designated SHG1 (salt hypersensitive germination 1), whose disruption leads to reduced germination rate under moderate salt stress conditions. SHG1 encodes a transmembrane protein with an ankyrin repeat motif that has been implicated in diverse cellular processes such as signal transduction. The SGH1-disrupted Arabidopsis mutant died at the cotyledon stage when sown on salt-containing medium, although wild type plants could form true leaves under the same conditions. On the other hand, this mutant showed similar phenotypes to wild type plants when sown on medium without salt and transferred to salt-containing medium at the vegetative stage. These results suggested that SHG1 played indispensable role in the seed germination and seedling establishment under moderate salt stress conditions. SHG1 may be involved in the release of seed dormancy.

Keywords: germination, ankyrin repeat, arabidopsis, salt tolerance

Procedia PDF Downloads 403

Authors: Yu Zhao, Rainer Gruenheid, Gerhard Bauch

Abstract:

In the microwave and millimeter-wave transmission region, substrate-integrated waveguide (SIW) is a very promising candidate for the development of circuits and components. It facilitates the transmission at the data rates in excess of 200 Gbit/s. An SIW mimics a rectangular waveguide by approximating the closed sidewalls with a via fence. This structure suppresses the low frequency components and makes the channel of the SIW a bandpass or high pass filter. This channel characteristic impedes the conventional baseband transmission using non-return-to-zero (NRZ) pulse shaping scheme. Therefore, mixers are commonly proposed to be used as carrier modulator and demodulator in order to facilitate a passband transmission. However, carrier modulation is not an energy efficient solution, because modulation and demodulation at high frequencies consume a lot of energy. For the first time to our knowledge, this paper proposes a spectrum shaping scheme of low complexity for the channel of SIW, namely spread reshaping code. It aims at matching the spectrum of the transmit signal to the channel frequency response. It facilitates the transmission through the SIW channel while it avoids using carrier modulation. In some cases, it even does not need equalization. Simulations reveal a good performance of this scheme, such that, as a result, eye opening is achieved without any equalization or modulation for the respective transmission channels.

Keywords: bandpass channel, eye-opening, switching frequency, substrate-integrated waveguide, spectrum shaping scheme, spread reshaping code

Procedia PDF Downloads 163

Authors: Monu Verma, Hyunook Kim

Abstract:

Heavy metals and organic dyes are the major sources of water pollution. Herein, a trifunctional β−cyclodextrin−ethylenediaminetetraacetic acid−chitosan (β−CD−EDTA−CS) polymer was synthesized using an easy and simple chemical route by the reaction of activated β−CD with CS through EDTA as a cross-linker (amidation reaction) for the removal of inorganic and organic pollutants from aqueous solution under different parameters such as pH, time effect, initial concentration, reusability, etc. The synthesized adsorbent was characterized using powder X-ray diffraction, Fourier transform infrared spectroscopy, field scanning electron microscopy, energy dispersive spectroscopy, Brunauer-Emmett-Teller (BET), thermogravimetric analyzer techniques to investigate their structural, functional, morphological, elemental compositions, surface area, and thermal properties, respectively. Two types of heavy metals, i.e., mercury (Hg²⁺) and cadmium (Cd²⁺), and three organic dyes, i.e., methylene blue (MB), crystal violet (CV), and safranin O (SO), were chosen as inorganic and organic pollutants, respectively, to study the adsorption capacity of β-CD-EDTA-CS in aqueous solution. The β-CD-EDTA-CS shows a monolayer adsorption capacity of 346.30 ± 14.0 and 202.90 ± 13.90 mg g−¹ for Hg²⁺ and Cd²⁺, respectively, and a heterogeneous adsorption capacity of 107.20 ± 5.70, 77.40 ± 5.30 and 55.30 ± 3.60 mg g−¹ for MB, CV and SO, respectively. Kinetics results followed pseudo-second order (PSO) kinetics behavior for both metal ions and dyes, and higher rate constants values (0.00161–0.00368 g mg−¹ min−¹) for dyes confirmed the cavitation of organic dyes (physisorption). In addition, we have also demonstrated the performance of β-CD-EDTA-CS for the four heavy metals, Hg²⁺, Cd²⁺, Ni²⁺, and Cu²⁺, and three dyes MB, CV, and SO in secondary treated wastewater. The findings of this study indicate that β-CD-EDTA-CS is simple and easy to synthesize and can be used in wastewater treatment.

Keywords: adsorption isotherms, adsorption mechanism, amino-β-cyclodextrin, heavy metal ions, organic dyes

Procedia PDF Downloads 113

Authors: Yeidy Sorani Montenegro Camacho, Samir Bensaid, Nunzio Russo, Debora Fino

Abstract:

LiFeO2 nano-powders were prepared via solution combustion synthesis (SCS) method and were used as carbon gasification catalyst in a reduced atmosphere. The gasification of soot with CO2 and H2O in the presence of CO and H2 (syngas atmosphere) were also investigated under atmospheric conditions using a fixed-bed micro-reactor placed in an electric, PID-regulated oven. The catalytic bed was composed of 150 mg of inert silica, 45 mg of carbon (Printex-U) and 5 mg of catalyst. The bed was prepared by ball milling the mixture at 240 rpm for 15 min to get an intimate contact between the catalyst and soot. A Gas Hourly Space Velocity (GHSV) of 38.000 h-1 was used for the tests campaign. The furnace was heated up to the desired temperature, a flow of 120 mL/min was sent into the system and at the same time the concentrations of CO, CO2 and H2 were recorded at the reactor outlet using an EMERSON X-STREAM XEGP analyzer. Catalytic and non-catalytic soot gasification reactions were studied in a temperature range of 120°C – 850°C with a heating rate of 5 °C/min (non-isothermal case) and at 650°C for 40 minutes (isothermal case). Experimental results show that the gasification of soot with H2O and CO2 are inhibited by the H2 and CO, respectively. The soot conversion at 650°C decreases from 70.2% to 31.6% when the CO is present in the feed. Besides, the soot conversion was 73.1% and 48.6% for H2O-soot and H2O-H2-soot gasification reactions, respectively. Also, it was observed that the carbon gasification in mixed atmosphere, i.e., when simultaneous carbon gasification with CO2 and steam take place, with H2 and CO as co-reagents; the gasification reaction is strongly inhibited by CO and H2, as well has been observed in single atmospheres for the isothermal and non-isothermal reactions. Further, it has been observed that when CO2 and H2O react with carbon at the same time, there is a passive cooperation of steam and carbon dioxide in the gasification reaction, this means that the two gases operate on separate active sites without influencing each other. Finally, despite the extreme reduced operating conditions, it has been demonstrated that the 32.9% of the initial carbon was gasified using LiFeO2-catalyst, while in the non-catalytic case only 8% of the soot was gasified at 650°C.

Keywords: soot gasification, nanostructured catalyst, reducing environment, syngas

Procedia PDF Downloads 264

Authors: E. Gil, A. Zepeda, J. Rivera, C. Ben-Youssef, S. Rincón

Abstract:

Water pollution has become one of the most serious environmental problems. Multiple methods have been proposed for the removal of Pb(II) from contaminated water. Among these, adsorption processes have shown to be more efficient, cheaper and easier to handle with respect to other treatment methods. However, research for adsorbents with high adsorption capacities is still necessary. For this purpose, we proposed in this work the study of metal-organic Framework [Co2(btec)(bipy)(DMF)2]n (MOF-Co) as adsorbent material of Pb (II) in aqueous media. MOF-Co was synthesized by a simple method. Firstly 4, 4’ dipyridyl, 1,2,4,5 benzenetetracarboxylic acid, cobalt (II) and nitrate hexahydrate were first mixed each one in N,N dimethylformamide (DMF) and then, mixed in a reactor altogether. The obtained solution was heated at 363 K in a muffle during 68 h to complete the synthesis. It was washed and dried, obtaining MOF-Co as the final product. MOF-Co was characterized before and after the adsorption process by Fourier transforms infrared spectra (FTIR) and X-ray photoelectron spectroscopy (XPS). The Pb(II) in aqueous media was detected by Absorption Atomic Spectroscopy (AA). In order to evaluate the adsorption process in the presence of Pb(II) in aqueous media, the experiments were realized in flask of 100 ml the work volume at 200 rpm, with different MOF-Co quantities (0.0125 and 0.025 g), pH (2-6), contact time (0.5-6 h) and temperature (298,308 and 318 K). The kinetic adsorption was represented by pseudo-second order model, which suggests that the adsorption took place through chemisorption or chemical adsorption. The best adsorption results were obtained at pH 5. Langmuir, Freundlich and BET equilibrium isotherms models were used to study the adsorption of Pb(II) with 0.0125 g of MOF-Co, in the presence of different concentration of Pb(II) (20-200 mg/L, 100 mL, pH 5) with 4 h of reaction. The correlation coefficients (R2) of the different models show that the Langmuir model is better than Freundlich and BET model with R2=0.97 and a maximum adsorption capacity of 833 mg/g. Therefore, the Langmuir model can be used to best describe the Pb(II) adsorption in monolayer behavior on the MOF-Co. This value is the highest when compared to other materials such as the graphene/activated carbon composite (217 mg/g), biomass fly ashes (96.8 mg/g), PVA/PAA gel (194.99 mg/g) and MOF with Ag12 nanoparticles (120 mg/g).

Keywords: adsorption, heavy metals, metal-organic frameworks, Pb(II)

Procedia PDF Downloads 216

Authors: Mashaal Hooda

Abstract:

The rationale for conducting this action research was to increase students' Academic Achievement (AA) contexts of studying/researching by employing the Goal Setting intervention (GS). The purposive sample consisted of 10 female undergraduate students at a university in Dubai. The intervention was introduced through workshop classes conducted online. The pre-intervention consisted of discussions concentrating on participants' research contexts amidst a pandemic. The GS moderators were implemented in the class, followed by scaffolding and mentoring interactions and self-reflective accounts of students' actions and feelings of using the intervention to better plan and structure their dissertation tasks. The research incorporated a Mixed Methods Methodology (MMM). Quantitative data collection took place through surveys, while qualitative data were collected using semi-structured interviews. Triangulation of the emergent themes showed a positive increase in students achievable GS, self-regulatory study skills, feedback-seeking behaviours, research organisation and synthesis, self-reflection and Academic Resilient (AR) attitudes amalgamate to enhance students' AA outcomes. Though, students' intrinsic motivational levels to study and research observed minor changes only. Nonetheless, the pebble in the shoe was removed as students AA contexts improved in undertaking better actionable steps for their research. Therefore, the GS intervention enabled students to set, balance, and achieve academic goals while catering to their academic anxieties, mental health concerns, and adaptability to the e-learning platforms amidst the COVID-19 pandemic. Despite the wide-scale changes the pandemic brought to the teaching and learning communities, the GS intervention served as a targeted intervention to help students maintain their achievement contexts in a goal-oriented way.

Keywords: academic achievement, acadeic resilience, COVID-19, goal setting

Procedia PDF Downloads 148

Authors: Chowon Kim, Yoo-Kyung Kim, Kyeong Yeon Park, Hyun-Shik Lee

Abstract:

Perfluoroalkyl compounds (PFCs) are globally distributed synthetic compounds that are known to adversely affect human health. Developmental toxicity assessment of PFCs is important to facilitate the evaluation of their environmental impact. In the present study, we assessed the developmental toxicity and teratogenicity of PFCs with different numbers of carbon atoms on Xenopus embryogenesis. An initial frog embryo teratogenicity assay-Xenopus (FETAX) assay was performed that identified perfluorohexanoic (PFHxA) and perfluoroheptanoic (PFHpA) acids as potential teratogens and developmental toxicants. The mechanism underlying this teratogenicity was also investigated by measuring the expression of tissue-specific biomarkers such as phosphotyrosine‑binding protein, xPTB (liver); NKX2.5 (heart); and Cyl18 (intestine). Whole‑mount in situ hybridization, reverse transcriptase‑polymerase chain reaction (RT-PCR), and histologic analyses detected severe defects in the liver and heart following exposure to PFHxA or PFHpA. In addition, immunoblotting revealed that PFHpA significantly increased the phosphorylation of extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK), while PFHxA slightly increased these, as compared with the control. These results suggest that PFHxA and PFHpA are developmental toxicants and teratogens, with PFHpA producing more severe effects on liver and heart development through the induction of ERK and JNK phosphorylation.

Keywords: PFCs, ERK, JNK, xenopus

Procedia PDF Downloads 296

Authors: Pamir Gogoi, Ratree Wayland

Abstract:

This study investigates the acoustic measures of breathiness when coarticulated with nasality. The acoustic correlates of breathiness and nasality that has already been well established after years of empirical research. Some of these acoustic parameters - like low frequency peaks and wider bandwidths- are common for both nasal and breathy voice. Therefore, it is likely that these parameters interact when a sound is coarticulated with breathiness and nasality. This leads to the hypothesis that the acoustic parameters, which usually act as robust cues in differentiating between breathy and modal voice, might not be reliable cues for differentiating between breathy and modal voice when breathiness is coarticulated with nasality. The effect of nasality on the perception of breathiness has been explored in earlier studies using synthesized speech. The results showed that perceptually, nasality and breathiness do interact. The current study investigates if a similar pattern is observed in natural speech. The study is conducted on Marathi, an Indo-Aryan language which has a three-way contrast between nasality and breathiness. That is, there is a phonemic distinction between nasals, breathy voice and breathy-nasals. Voice quality parameters like – H1-H2 (Difference between the amplitude of first and second harmonic), H1-A3 (Difference between the amplitude of first harmonic and third formant, CPP (Cepstral Peak Prominence), HNR (Harmonics to Noise ratio) and B1 (Bandwidth of first formant) were extracted. Statistical models like linear mixed effects regression and Random Forest classifiers show that measures that capture the noise component in the signal- like CPP and HNR- can classify breathy voice from modal voice better than spectral measures when breathy voice is coarticulated with nasality.

Keywords: breathiness, marathi, nasality, voice quality

Procedia PDF Downloads 99

Authors: Pachari Chuenta, Suwat Nanan

Abstract:

ZnO nanostructures have been synthesized successfully in high yield via catalyst-free chemical precipitation technique by varying zinc source (either zinc nitrate or zinc acetate) and oxygen source (either oxalic acid or urea) without using any surfactant, organic solvent or capping agent. The ZnO nanostructures were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffractometry (XRD), scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), UV-vis diffuse reflection spectroscopy (UV-vis DRS), and photoluminescence spectroscopy (PL). The FTIR peak in the range of 450-470 cm-1 corresponded to Zn-O stretching in ZnO structure. The synthesized ZnO samples showed well crystalized hexagonal wurtzite structure. SEM micrographs displayed spherical droplet of about 50-100 nm. The band gap of prepared ZnO was found to be 3.4-3.5 eV. The presence of PL peak at 468 nm was attributed to surface defect state. The photocatalytic activity of ZnO was studied by monitoring the photodegradation of reactive red (RR141) azo dye under ultraviolet (UV) light irradiation. Blank experiment was also separately carried out by irradiating the aqueous solution of the dye in absence of the photocatalyst. The initial concentration of the dye was fixed at 10 mgL-1. About 50 mg of ZnO photocatalyst was dispersed in 200 mL dye solution. The sample was collected at a regular time interval during the irradiation and then was analyzed after centrifugation. The concentration of the dye was determined by monitoring the absorbance at its maximum wavelength (λₘₐₓ) of 544 nm using UV-vis spectroscopic analysis technique. The sources of Zn and O played an important role on photocatalytic performance of the ZnO photocatalyst. ZnO nanoparticles which prepared by zinc acetate and oxalic acid at molar ratio of 1:1 showed high photocatalytic performance of about 97% toward photodegradation of reactive red azo dye (RR141) under UV light irradiation for only 60 min. This work demonstrates the promising potential of ZnO nanomaterials as photocatalysts for environmental remediation.

Keywords: azo dye, chemical precipitation, photocatalytic, ZnO

Procedia PDF Downloads 147

Authors: Mazita Mohd Diah, Anton V. Dolzhenko, Tin Wui Wong

Abstract:

Nanoparticles, being small with a large specific surface area, increase solubility, enhance bioavailability, improve controlled release and enable precision targeting of the entrapped compounds. In this study, chitosan as polymeric permeation enhancer was conjugated to a polar pro-drug, carboxymethyl-5-fluorouracil (CMFU) to increase the skin drug permeation. Chitosan-CMFU conjugate was synthesized using chemical conjugation process through succinate linker. It was then transformed into nanoparticles via spray drying method. The conjugation was elucidated using Fourier Transform Infrared and Proton Nuclear Magnetic Resonance techniques. The nanoparticle size, size distribution, zeta potential, drug content, skin permeation and retention profiles were characterized. The conjugation was denoted using 1H NMR by new peaks at signal δ = 4.184 ppm (singlet, 2H for CH2) and 7.676-7.688 ppm (doublet, 1H for C6) attributed to CMFU in chitosan-CMFU NMR spectrum. The nanoparticles had profiles of particle size: 93.97 ±35.11 nm, polydispersity index: 0.40 ± 0.14, zeta potential: +18.25 ±2.95 mV and drug content: 6.20 ± 1.98 % w/w. Almost 80 % w/w CMFU in the form of nanoparticles permeated through the skin in 24 hours and close to 50 % w/w permeation occurred in first 1-2 hours. Without conjugation to chitosan and nanoparticulation, less than 40 % w/w CMFU permeated through the skin in 24 hours. The skin drug retention likewise was higher with chitosan-CMFU nanoparticles (15.34 ± 5.82 % w/w) than CMFU (2.24 ± 0.57 % w/w). CMFU, through conjugation with chitosan permeation enhancer and processed in nanogeometry, had its skin permeation and retention degree promoted.

Keywords: carboxymethyl-5-fluorouracil, chitosan, conjugate, skin permeation, skin retention

Procedia PDF Downloads 368

Authors: Sara Arafeh, Kovriguine Evguine

Abstract:

Cytochromes P450 are enzymes that require a supply of electrons to catalyze the synthesis of steroid hormones, fatty acids, and prostaglandin hormone. Cytochrome P450 Oxidoreductase (CYPOR), a membrane bound enzyme, provides these electrons in its open conformation. CYPOR has two cytosolic domains (FAD domain and FMN domain) and an N-terminal in the membrane. In its open conformation, electrons flow from NADPH, FAD, and finally to FMN where cytochrome P450 picks up these electrons. In the closed conformation, cytochrome P450 does not bind to the FMN domain to take the electrons. It was found that when the cytosolic domains are isolated, CYPOR could not bind to cytochrome P450. This suggested that the membrane environment is important for CYPOR function. This project takes the initiative to better understand the dynamics of CYPOR in its full length. Here, we determine the distance between specific sites in the FAD and FMN binding domains in CYPOR by Forster Resonance Energy Transfer (FRET) and Ultrafast TA spectroscopy with and without NADPH. The approach to determine these distances will rely on labeling these sites with red and infrared fluorophores. Mimic membrane attachment is done by inserting CYPOR in lipid nanodiscs. By determining the distances between the donor-acceptor sites in these domains, we can observe the open/closed conformations upon reducing CYPOR in the presence and absence of cytochrome P450. Such study is important to better understand CYPOR mechanism of action in various endosomal membranes including hepatic CYPOR which is vital in plasma cholesterol homeostasis. By investigating the conformational cycles of CYPOR, we can synthesize drugs that would be more efficient in affecting the steroid hormonal levels and metabolism of toxins catalyzed by Cytochrome P450.

Keywords: conformational cycle of CYPOR, cytochrome P450, cytochrome P450 oxidoreductase, FAD domain, FMN domain, FRET, Ultrafast TA Spectroscopy

Procedia PDF Downloads 282

Authors: Usama Mohamed, Sam Booth, Aliysn J. Nedoma

Abstract:

As part of the transition to electric vehicles, there has been a recent increase in demand for battery manufacturing. Cathodes typically account for approximately 50% of the total lithium-ion battery cell cost and are a pivotal factor in determining the viability of new industrial infrastructure. Cathodes which offer lower costs whilst maintaining or increasing performance, such as nickel-rich layered cathodes, have a significant competitive advantage when scaling up the manufacturing process. This project evaluates the techno-economic value proposition of an integrated industrial scale cathode active material (CAM) production process, closing the mass and energy balances, and optimizing the operation conditions using a sensitivity analysis. This is done by developing a process model of a co-precipitation synthesis route using Aspen Plus software and validated based on experimental data. The mechanism chemistry and equilibrium conditions were established based on previous literature and HSC-Chemistry software. This is then followed by integrating the energy streams, adding waste recovery and treatment processes, as well as testing the effect of key parameters (temperature, pH, reaction time, etc.) on CAM production yield and emissions. Finally, an economic analysis estimating the fixed and variable costs (including capital expenditure, labor costs, raw materials, etc.) to calculate the cost of CAM ($/kg and $/kWh), total plant cost ($) and net present value (NPV). This work sets the foundational blueprint for future research into sustainable industrial scale processes for CAM manufacturing.

Keywords: cathodes, industrial production, nickel-rich layered cathodes, process modelling, techno-economic analysis

Procedia PDF Downloads 102

Authors: Habtamu Fufa, Yemane Berhane

Abstract:

Child under nutrition has long-term consequences for intellectual ability, economic productivity, reproductive performance and susceptibility to metabolic and cardiovascular disease. The unacceptably high prevalence of malnutrition in young children of the region has not changed much over the last decades, which could make the achievement of the corresponding Millennium Development Goals very unlikely. Despite the well-documented problems of child malnutrition in Sub-Saharan Africa, there is few systematic review of evidences on determinants of child malnutrition in the region. The current available evidence on determinants of child under nutrition in Sub-Saharan Africa is systematically reviewed. The method used in searching relevant literature was using bio medical databases PUBMED, Google scholar and the website of the World Health Organization on nutrition using the following key words: "Determinants “, "Child Malnutrition", and "Sub- Saharan Africa". The search was limited to articles published in and after 1995 up to date. In all the reviewed articles, the data were analyzed using multivariate regression analysis and or odds ratios for significance of determinants in child malnutrition. Synthesis of 40 published articles from various countries of the region is done and noted that household economic status, maternal education, disease, breastfeeding practices, age and sex of a child, birth interval and residential areas were found to be determinants of child under nutrition. Poverty remains the main factor of malnutrition in Sub-Saharan Africa and poor education of parents aggravates the malnutrition through perpetuation of poor nutrition practices. Male children under five years are the most affected ones. Understanding of these determinants of poor nutritional attainment would provide insights in designing interventions for reducing the high levels of child malnutrition in this region. Large-scale multi-sectoral community-based interventions are urgently needed for a sustainable improvement of child nutritional & health status in Sub-Saharan Africa.

Keywords: child malnutrition, determinants, Sub-Saharan Africa, health status

Procedia PDF Downloads 485

Authors: Willian L. G. Silva, Fabio R. M. Batista, Matthieu Tubino

Abstract:

Microalgae can be considered a potential source of oil for biodiesel synthesis since this microorganism can grow rapidly in either fresh or salty water, not competing with food production. There are several favorable conditions in Brazil for this type of culture due to the country’s great amount of water. Another very positive aspect of this type of culture is its ability to fix atmospheric CO2, contributing to the reduction of greenhouse gases and their effects on global warming. Despite this biodiesel environmental advantages it degrades resulting in changes in its physical and chemical properties. In this work, the methyl and ethyl microalgae biodiesel oxidative stability was studied in the absence and presence of a synthetic antioxidant. The synthetic antioxidants used were propyl gallate (PG) and tert-butylhydroquinone (TBHQ), at a 0,12% (w/w) concentration. The biodiesel mixture was kept in a sealed glass flask, sheltered from light, and at room temperature (about 25 ºC) for 180 days. During this period, aliquots from this biodiesel were subjected to induced degradation by the Rancimat method, which determines an important quality parameter, provided in the current methods, and is used to monitor the degradation processes that occur in the biodiesel over time. The induction period (IP) expresses the biodiesel oxidative stability. It was stablished that the minimum accepted IP value for biodiesel is 8 hours. The results show that ethylic biodiesel increased its IP value from 7,6 hours to 31 hours when using PG, and to 67 hours when using TBHQ, exceeding the minimum accepted IP value. When the antioxidants were added to the methylic biodiesel samples, the IP was raised to 28 hours when using PG, and to 62 hours when using TBHQ. These values were maintained throughout the entire period of study (180 days). On the other hand, the biodiesel samples without additives maintained an IP above the allowed value for only 30 days. Therefore, in order to preserve microalgae biodiesel for longer periods of time, it is necessary to add antioxidants to both derivatives, i.e., the ethylic and methylic.

Keywords: biodiesel, microalgae, oxidative stability, storage, synthetic antioxidants

Procedia PDF Downloads 466