Tech Science Press
Not a member yet
3972 research outputs found
Sort by
Paracetamol Sensitive Cellulose-Based Electrochemical Sensors
Get PDFElectrochemical determination of paracetamol (PCT) was successfully performed using carbon paste electrodes (CPEs) modified with treated coffee husks (CHt) or cellulose powder (Ce). Scanning electron microscopy was used to characterize unmodified or modified CPEs prior to their use. The electrochemical oxidation of PCT was investigated using square wave voltammetry (SWV) and cyclic voltammetry (CV). The oxidation current density of PCT was two-fold higher with the CPE-CHt sensor and 30% higher with CPE-Ce in comparison with the unmodified CPE, and this correlated with the higher hydrophilicity of the modified electrodes. Using SWV for the electrochemical analysis of PCT, carbon paste electrode modified with raw coffee husks (CPE-CHr) showed the presence of impurities at +0.27 V/SCE, showing the interest in using pure cellulose for the present analytical application. Furthermore, CPE-Ce presented a higher real area compared to CPE-CHr, which explains the increase in the limit of saturation from 400 mg/L to 950 mg/L. The better saturation limit exhibited by CPE-Ce justifies its choice for electroanalysis of PCT in commercialized tablets. The proposed method was successfully applied in the determination of PCT in commercialized tablets (Doliprane® 500) with a recovery rate close to 100%, and no interference with the excipients contained in the tablets analyzed was observed. This novel sensor opens the way for sustainable development of electroanalytical control of drugs sold individually in developing countries
Elaboration of Materials with Functionality Gradients by Assembly of Chitosan-Collagen Microspheres Produced by Microfluidics
Get PDFBiopolymers extracted from renewable resources like chitosan and collagen exhibit interesting properties for the elaboration of materials designed for tissue engineering applications, among which are their hydrophilicity, biocompatibility and biodegradability. In many cases, functional recovery of an injured tissue or organ requires oriented cell outgrowth, which is particularly critical for nerve regeneration. Therefore, there is a growing interest for the elaboration of materials exhibiting functionalization gradients able to guide cells. Here, we explore an original way of elaborating such gradients by assembling particles from a library of functionalized microspheres. We propose a simple process to prepare chitosan-collagen hybrid microspheres by micro- and milli-fluidics, with adaptable dimensions and narrow size distributions. The adhesion and survival rate of PC12 cells on hybrid microspheres were compared to those on pure chitosan ones. Finally, functionalized microspheres were assembled into membranes exhibiting a functionalization gradient
Suitability of Blends from Virgin and Reprocessed Polylactide: Performance and Energy Valorization Kinetics
Get PDFA blending strategy of virgin and reprocessed polylactide may be postulated as an alternative to reduce the material cost at industrial level, and as a valorization route to plastic waste management of production scraps. The performance of blends prepared from virgin polylactide and polylactide mechanically reprocessed up to two cycles (PLA-V/R) was assessed in terms of thermo-oxidative stability, morphology, viscoelasticity and thermal kinetics for energetic valorization. PLA-V/R blends showed appropriate thermo-oxidative stability. The amorphous nature of polylactide was preserved after blending. The viscoelastic properties showed an increment of the mechanical blend effectiveness, which suggested the feasibility of using PLA-V/R blends under similar mechanical conditions to those of virgin PLA goods. Finally, it was shown that the energetic valorization of PLA-V/R blends would result in a more feasible process, due to the lower required activation energy, thus highlighting the advantages of the energetic demand for the process. In conclusion, PLA-V/R blends showed similar processability, service performance and valorization routes as virgin PLA and therefore could be relevant in the sustainable circular industry of bioplastics
Ultrathin Wood Laminae–Thermoplastic Starch Biodegradable Composites
Get PDFNovel fully biodegradable thermoplastic composite laminates reinforced with ultrathin wood laminae were prepared through a hot-pressing process by using two different thermoplastic starch (TPS) matrices. The microstructure and physical properties of the resulting unidirectional and bidirectional laminates were studied. The investigated materials presented a complex microstructure, in which the porosity of the wood laminae was almost entirely occluded by the polymer matrix. The mechanical behavior of the laminates was strongly affected by the obtained microstructure, and matrix penetration in wood pores led to biodegradable composites with elastic modulus and tensile strength higher than those of their constituents. Finally, thermal welding and thermoformability tests proved how these materials possess features typical of thermoplastic materials
Biobased Aromatic-Aliphatic Polyols by Thiol-Ene Reactions of Propoxylated Mercaptanized Cardanol
No full textAromatic-aliphatic polyols were obtained previously from the thiol-ene reactions of propoxylated cardanol with hydroxyalkyl mercaptans; these aromatic-aliphatic polyols were then utilized in the preparation of rigid polyurethane foams with excellent properties. The current work describes a variant of cardanol polyol synthesis by thiol-ene reactions in three steps. The first step is propoxylation of cardanol by reacting cardanol with propylene oxide; the second step is mercaptanization of propoxylated cardanol by reacting double bonds with hydrogen sulfide; and the third step involves the addition of the thiol groups of mercaptanized propoxylated cardanol to the double bonds of allyl alcohol, glycerol-1-allyl ether, and trimethylolpropane allyl ether. Thus, obtained polyols were characterized by standard analytical methods. Rigid polyurethane foams prepared from these polyols show promising physical-mechanical properties. The rigid polyurethane foams can be used for various applications such as thermo-insulation of freezers, storage tanks and pipes for food and chemical industries, wood substitutes and flotation materials
Bus Encoded LUT Multiplier for Portable Biomedical Therapeutic Devices
Get PDFDSP operation in a Biomedical related therapeutic hardware need to be performed with high accuracy and with high speed. Portable DSP hardware’s like pulse/heart beat detectors must perform with reduced operational power due to lack of conventional power sources. This work proposes a hybrid biomedical hardware chip in which the speed and power utilization factors are greatly improved. Multipliers are the core operational unit of any DSP SoC. This work proposes a LUT based unsigned multiplication which is proven to be efficient in terms of high operating speed. For n bit input multiplication n*n memory array of 2n bit size is required to memorize all the possible input and output combination. Various literature works claims to be achieve high speed multiplication with reduced LUT size by integrating a barrel shifter mechanism. This paper work address this problem, by reworking the multiplier architecture with a parallel operating pre-processing unit which used to change the multiplier and multiplicand order with respect to the number of computational addition and subtraction stages required. Along with LUT multiplier a low power bus encoding scheme is integrated to limit the power constraint of the on chip DSP unit. This paper address both the speed and power optimization techniques and tested with various FPGA device families
A Machine Learning Approach for MRI Brain Tumor Classification
Get PDFA new method for the denoising, extraction and tumor detection on MRI images is presented in this paper. MRI images help physicians study and diagnose diseases or tumors present in the brain. This work is focused towards helping the radiologist and physician to have a second opinion on the diagnosis. The ambiguity of Magnetic Resonance (MR) image features is solved in a simpler manner. The MRI image acquired from the machine is subjected to analysis in the work. The real-time data is used for the analysis. Basic preprocessing is performed using various filters for noise removal. The de-noised image is segmented, and the feature extractions are performed. Features are extracted using the wavelet transform. When compared to other methods, the wavelet transform is more suitable for MRI image feature extraction. The features are given to the classifier which uses binary tree support vectors for classification. The classification process is compared with conventional methods
Optimizing the Design of PV Solar Reverse Osmosis Unit (RO/PV) by using Genetic Algorithms for Abu Dhabi Climate
Get PDFThe economic progress in the United Arab Emirates (UAE) induces to a significant increase in the demand for agricultural development. In Emirates the majority of the farms are irrigated by underground water, characterized by a high level of salinity. Liwa, Al Ain and Al Khatem areas are suffering from high water well salinity that exceeds 20,000 ppm. This work focuses on this problem and suggests a suitable solution allowing the use of renewable energy (Solar Photovoltaic) to drive RO desalination units. An optimal design of RO/PV unit adapted to a typical farm in Abu Dhabi was suggested using a model developed by using the software ROSA and HOMER. One of the main important results given by ROSA, besides the characteristics of the RO plant, is the required power to drive the plant. This data is the main input in the second part of the present work which is the design of the PV solar system. Finally, an economic and environmental study was carried to estimate the total cost of the project
A Study on the Far Wake of Elliptic Cylinders
Get PDFThe evolution of far wake of stationary elliptic cylinders with angle of attack is investigated for the unsteady flow at Re = 200 using a stabilized finite- element method. The Reynolds number, Re, is based on the major axis of cylinder and free-stream speed. Cylinder aspect ratios, AR considered are 0.2, 0.5 and 0.8 while the angle of attack, α varies from 0◦ to 90◦. With increasing α, the Karman or primary shedding frequency of each cylinder decreases monotonically while the primary wavelength and time-averaged as well as r.m.s. drag increase monoton- ically. The time-averaged lift and moment coefficients initially increase with α and then decrease. The power spectrum analysis of unsteady treansverse velocity signal at various stations along the wake centerline is used to study the associated frequencies. The Karman or primary shedding frequency exists for each α. For the AR = 0.2 cylinder, the secondary and subsequently, low magnitude tertiary fre-quencies appear in the wake as α continues to increase from 30◦. In contrast to the decaying nature of primary frequency with α, secondary frequency exhibits a non- monotonic variation. The secondary frequency in general is not a sub-harmonic of the primary. This suggests that the secondary structures do not form due to merg- ing of primary vortices. With increasing α, the location of formation of secondary structures advances upstream. For a given orientation, the upstream advancement is more dominant with decreasing AR. Power spectrum analysis indicates that the wake state for confined flow is characterized by the primary frequency alone, i.e. the imposition of blockage suppresses the formation of secondary structures
Devanagari Handwriting Grading System Based on Curvature Features
Get PDFGrading of writers in perspective of their handwriting is a challenging task owing to various writing styles of different individuals. This paper presents a framework for grading of Devanagari writers in perspective of their handwriting. This framework of grading can be useful in conducting the handwriting competitions and then deciding the winners on the basis of an automated process. Selecting the set of features is a challenging task for implementing a handwriting grading system of particular language. In this paper, curvature features, namely, parabola curve fitting and power curve fitting have been considered for extracting the vital information of writers, which can be helpful in grading the writers. For obtaining the classification score, k-NN classifier has been considered in the present work. Four printed Devanagari font styles, namely, Devlys, Krishna, Krutidev, and Utsaah have been considered for train the proposed model of handwriting evaluation. For evaluating the effectiveness of the proposed framework, we have conducted a mock test of 75 Devanagari writers (Left handed and Right handed) and noticed that the proposed framework performing well suitable for conducting the handwriting competition of Devanagari text writers. This work is also newly in the ground of Devanagari text recognition