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Induction of Apoptosis and Autophagy Using Ectopic DSCR1 Expression in Breast Cancer Cells
Get PDFDown syndrome critical region 1 gene (DSCR1) is an anti-angiogenesis gene that inhibits the growth of tumor cells. In this study, the role of autophagy and apoptosis in DSCR1-induced cytotoxicity were investigated in MDA-MB-468 breast cancer cells. Lentivirus vector harboring DSCR1 (LV-DSCR1+) was constructed in HEK 293 cells and the optimal dosage of lentivirus vector for infection was determined by the MTT assay. After infection of cells using LV-DSCR1+, acridine orange and ethidium bromide staining was performed to investigation of apoptosis and autophagy. Expression of DSCR1 and marker genes for angiogenesis (VEGF), apoptosis (Bax and Bcl2) and autophagy (LC3 and Beclin) were determined by Real time PCR. The cellular morphological changes related to apoptosis and autophagy was happened after 48 hours of viral infection. Fragmented bright orange nucleuses and vacuoles were observed due to the cell apoptosis and autophagy after acridine orange and ethidium bromide staining. Upregulation of Bax, Lc3, DSCR1 and Beclin1 and downregulation of Bcl2 and VEGF was detected due to treatment with LV-DSCR1+. These results demonstrated that LV-DSCR1+ can induce apoptosis and autophagy, therefore suggesting that it may serves as an efficient tool to breast cancer treatment
Potentials of an Eco-Friendly Composite in Hot-Dry Climate
Get PDFThis study aims to show the aptitude of a locally made composite for providing thermal comfort and mechanical resistance in buildings in hot-dry climates. The thermal characterization reveals that the thermal diffusivity of the studied material is lower than that of commonly used materials such as agglomerated and full cinderblocks and laterite blocks and therefore is a better insulating material. In addition, its thermal inertia is the highest compared to commonly used materials of agglomerated and full cinderblocks, laterite blocks and compressed earth blocks, which implies a longer time lag. On the basis of mechanical resistance, with a compression resistance of 3.61 MPa, the studied material meets the requirement of CRATerre and NBF 02-003 (2009) as a material for construction of single-storey buildings. Therefore, this material, containing 1% Hibiscus sabdariffafibers and compacted by vibration, is a suitable material for the walls of standing buildings and for thermal comfort in hot dry climates
Selective Adsorption of Ag(I) from Electronic Waste Leachate Using Modified Silk Sericin
Get PDFA novel biosorbent was synthesized by grafting bisthiourea (BTU) on a silk sericin (SS) matrix. This biosorbent was denoted as BTU-SS and characterized by Fourier transform infrared spectroscopy (FTIR), zeta potential measurements, elemental analysis, and X-ray photoelectron spectroscopy (XPS). As revealed by the adsorption experiments, both BTU-SS and SS showed low affinity towards coexisting base metallic ions in Ag(I)-Cu(II)-Zn(II)-Ni(II)-Pb(II) electronic waste leachate mixtures, while their adsorption capacities towards Ag(I) reached 30.5 and 10.4 mg·g–1 at a pH of 5.0, respectively. BTU-SS showed higher selectivity towards Ag(I) than SS, as revealed by the Ag(I) partition coefficients between the biosorbents and the leachate (16634.6 and 403.3, respectively). As further demonstrated by column experiments, BTU-SS allowed the separation of Ag(I) from an electronic waste leachate. Thermodynamic studies showed that the adsorption of Ag(I) was exothermic and spontaneous, while adsorption kinetic experiments revealed that chemisorption dominated the adsorption process with activation energies of 47.67 and 53.27 kJ·mol–1 for BTU-SS and SS, respectively. FTIR and XPS analyses of fresh and Ag(I)-loaded BTU-SS further revealed an adsorption mechanism mainly involving electrostatic and coordination interactions
Vapor and Pressure Sensors Based on Cellulose Nanofibers and Carbon Nanotubes Aerogel with Thermoelectric Properties
Get PDFIn this work, thermally insulating and electrically conductive aerogels were prepared from cellulose nanofibers (CNF) and carbon nanotubes (CNTs) by environmentally friendly freeze-drying process. The thermal conductivity of neat CNF aerogel is 24 mW/(m·K) with a density of 0.025 g/cm3. With the addition of CNTs into CNF aerogel, the electrical conductivity was significantly increased while the thermal conductivity was increased to 38 mW/(m·K). Due to these interesting properties, the Seebeck coefficient and the figure of merit (ZT) of the CNF/CNTs aerogels were measured and showed that CNF/CNTs aerogel thermoelectric properties can be improved. The compressibility and electrical resistance of the CNF/CNTs aerogel highlighted its pressure-responsive property. A set of volatile organic compounds (VOCs) were exposed to aerogels to monitor the resistance change. The CNF/CNTs aerogel showed high sensitivity and good response to both nonpolar and polar vapors due to the absorption by both CNF and CNTs networks. The prepared CNF/CNTs aerogel is therefore a good candidate for thermal insulation, thermoelectric material, VOCs sensing, and pressure-sensing applications
Structure-Thermal Conductivity Tentative Correlation for Hybrid Aerogels Based on Nanofibrillated Cellulose-Mesoporous Silica Nanocomposite
Get PDFHybrid aerogels have been prepared by freeze-drying technique after mixing water dispersions of cellulose microfibers or cellulose nanofibers and silica (SiO2) of type SBA-15 (2D-hexagonal). The prepared composites were characterized by different analysis techniques such as SEM, hot-filament, DMA, etc. These composites are compared to those previously prepared using nanozeolites (NZs) as mineral charge. The morphology studied by SEM indicated that both systems have different structures, i.e., individual fibers for cellulose microfibers WP-based aerogels and films for nanofibrillated cellulose NFC-based ones.... These differences seem to be driven by the charge of the particles, their aspect ratio and concentrations. These hybrid materials exhibit tunable thermal conductivity and mechanical properties. The thermal conductivity values range between ~18 to 28 mW. m–1. K–1and confirm the superinsulation ability of these fibrous aerogels. Synergism on the thermal insulation properties and mechanical properties was shown by adjunction of mineral particles to both cellulose-based aerogels by reaching pore size lower than 100 nm. It significantly reduces the thermal conductivity of the hybrid aerogels as predicted by Knudsen et al. Furthermore, the addition of mineral fillers to aerogels based on cellulose microfibers induced a significant increase in stiffness
Isolation and Characterization of Nanocellulose Obtained from Industrial Crop Waste Resources by Using Mild Acid Hydrolysis
Get PDFCellulose, microcrystalline cellulose and nanocellulose were prepared from three agricultural waste resources: pineapple leaf (PALF), banana rachis (BR), and sugarcane bagasse (SCB). Each waste resource was first converted into microcrystalline cellulose which was subsequently converted into cellulose nanoparticles by using mild (30% w/v) and strong (60% w/v) sulfuric acid concentrations for extraction. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA) were used to characterize each waste resource and extracted cellulosic materials. Furthermore, nanocelluloses were studied by zeta potential, size analysis, and transmission electron microscopy (TEM). Cellulose nanowhiskers were successfully obtained and isolated with a 33% average yield by applying a mild acid treatment. Substrates BR and SCB proved to be more promising agricultural waste resources in terms of their crystalline cellulosic content and properties
Polyurethane Composites Synthesized Using Natural Oil-Based Polyols and Sisal Fibers
Get PDFElastomeric polyurethanes were prepared from a reference polyurethane system modified with biobased polyols synthesized using rapeseed or palm oils. The reference material was modified by replacement of the commercial polyol by 10% of biopolyols and also by addition of sisal fibers up to 5 wt%. The higher functionality of the biopolyols increased the crosslinking density of the networks and this was reflected by an increase in hardness and a decrease in water absorption. The effect of the sisal fibers mainly improved the mechanical and thermomechanical properties of the system with rapeseed oil because of good dispersion and strong fiber-matrix interaction. The system containing palm oil polyol corresponded to an initial formulation of high viscosity and, consequently, the resulting composites presented lower densities than the theoretically expected ones. These results are associated with fiber dispersion problems in the initial reactive mixture
Cardanol-Based Polyurethane Coatings via Click Chemistry: An Eco-friendly Approach
Get PDFThis research work discloses the preparation of polyurethane coatings from cardanol modified using thiolene chemistry, wherein unsaturated long alkyl chain of cardanol was successfully utilized via thiol-ene click reaction to synthesize polyol. For this purpose, cardanol and thioglycerol was reacted in the presence of Irgacure 184 (photoinitiator) and 1,8-Diazabicyclo[5.4.0]undec-7-ene (catalyst) and exposed to UV light for 12 h at 80 °C. One mole of thioglycerol was successfully added across the double bond of fatty chain of cardanol and confirmed by chemical and spectroscopic analysis. Further, the polyol thus prepared was cured with various polyisocyanates, viz., N-75 (HDI based), L-67/BA (TDI based), Z-4470 (IPDI based) and corresponding polyurethane coatings were developed. The coatings were then analyzed for mechanical, chemical, optical, thermal and anticorrosive properties. It was observed that cardanol-based PU coatings exhibited excellent mechanical, chemical and thermal and anticorrosive properties as compared to that of commercial acrylic-PU coatings
Preliminary Study on Tensile and Impact Properties of Kenaf/Bamboo Fiber Reinforced Epoxy Composites
Get PDFThe application of natural fibers as reinforcement in composite material has increased due to environmental concerns, low cost, degradability and health concerns. The purpose of this study is to identify the best type of bamboo fibers to be used as reinforcement for kenaf (K)/bamboo hybrid composite. There were three types of bamboo fibers evaluated in this study which include bamboo mat (B), bamboo fabric (BF) and bamboo powder (BP). Chemical composition of B, BF, BP and K fibers were analyzed in this study. The effect of different types of bamboo fibers on tensile, impact, and morphological properties were investigated. The B/epoxy composites displayed the highest tensile strength (53.03 MPa) while K/epoxy composite had the highest tensile modulus (4.71 GPa). Scanning electron micrographs of B/epoxy composites displayed better fiber/matrix interfacial bonding in comparison to other studied composites. Results showed that impact strength of BF-based composite was highest (45.70 J/m). In conclusion, the tensile strength of B/epoxy composite is superior to the other bamboo reinforced composites and will be further evaluated in the next study
Novel Bio-based Flame Retardant Systems Derived from Tannic Acid
Get PDFIn this study, tannic acid (TA) was investigated as flame retardant agent for PLA. Different strategies to modify its thermal degradation pathway have been explored in order to improve its charring effect. The first one consists in combining TA with organomodified montmorillonite (oMMT), and enables limiting the thermo-oxidative degradation of TA and promoting the formation of an effective char layer. Flame-retardant (FR) behavior of PLA-based composition has been found to be positively impacted by this combination since a reduction of the peak of Heat Release Rate (PHRR), more important than the value recorded when oMMT and tannic acid are used separately, has been obtained. The second strategy, in which tannic acid was associated with a biosourced phosphorous-based compounds, i.e. metallic phytate salt, evidenced another alternative allowing enhancing TA flame retardant effect at 30 wt% loading content. The third and last strategy explored aims to chemically modify TA via a chemical grafting of phosphoric acid groups. This phosphorylated TA was shown to present the most effective flame-retardant (FR) effect. However, an important reduction of PLA molecular weight was observed