Vietnam Academy of Science and Technology: Journals Online
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The effect of silver nanoparticles on the limitation of ethylene gas and hydrolytic enzymatic activity in micropropagation of rose (Rosa hybrida L. 'Baby love')
No full textMicropropagation of rose (Rosa hybrida L. ‘Baby Love’) often encounter some abnormal phenomena such as yellow and abscission leaf, hyperhydricity, etc. These phenomena effect on the quality of shoots cultured in vitro as well as the survival rate of plantlets after transferred to greenhouse. This is due to the accumulation of ethylene in culture vessel, which leads to an increase in enzyme activity of cellulase and pectinase resulted in disrupting the cell wall binding and inducing organ abscission. In this study, the effect of silver nanoparticles (AgNPs) to overcome these abnormal phenomena as well as its effect on the growth and development of shoots and plantlets in rose cultured in vitro were evaluated. The results showed that after 6 weeks of shoot culture, the medium supplemented with 2 ppm AgNPs was the most suitable for in vitro shoot multiplication with the highest number of shoots/explant (6.67 shoots), shoot height (3.06 cm), fresh weight (451.00 mg), dry weight (58.33 mg), SPAD (32.28) and dry mass ratio(12.33%). Adding 3 ppm AgNPs into in vitro rooting medium may improve the growth and develop involve in plant height (3.06 cm), number of leaves (6.33), leaf length (1.50 cm), leaf width (1.50 cm), fresh weight (137.67 mg), dry weight (13.00 mg), number of roots (4.33), SPAD (39.37), dry mass ratio (9.40%) of rose plantlet after 4 weeks of culture. After treatment with AgNPs, the abnormal phenomena including ethylene gas accumulation (0.30 ppm), cellulase enzyme activity (0.14 UI/mL) and pectinase enzyme activity (0.40 UI/mL) was reduced compare with the other treatments and the control. In addition, the high survival rate (93.33%) of plantlets was also observed after 4 weeks transferred to greenhouse. On the other hand, the treatment with 5 ppm AgNPs also induced early rose in vitro flowering; however, when using AgNPs at high concentrations (7 ppm) inhibited growth, development, toxicity and even death of explants
Labeling efficiency of Tb3+ conjugated CD133 monoclonal antibody nanocomplex targeting in vitro metastatic cancer cells
No full textEfficient cancer treatment remains a huge challenge worldwide. As reported by the World HealthOrganization, the number of cancer patients is estimated to be 24 million in 2035, which is a 70% increasecompared to 14.1 million in 2012. The severity of cancer is due to the presence of cancer stem cells (CSCs),which are directly related to drug resistance, metastasis, and tumor relapse. Because of the unknown location ofthe primary tumor and/or the residency of CSCs, standard therapies deliver a high dose of drugs to the whole body,which can have negative effects and deadly consequences for patients undergoing treatment. Therefore, efficientluminescent materials for labeling and tracking CSCs are urgently needed to determine their distribution andtarget treatment. Herein, a fluorescent Tb3+ nano-ion and CD133 monoclonal antibody (mAb) were conjugatedinto a nano probe-complex (ET2). Tb3+ nano-ion is a rare-earth element and the CD133 mAb targets CD133,which is a CSC surface marker. The Tb3+ nanorods were surface treated with silica and activated with -NH2 forfunctioning before being coupled with CD133 mAb. Strong fluorescent Tb3+ nanorods were used to decrease thetoxicity of high-dose medicines, and the purpose of the CD133 mAb was to increase the specific binding capacityof CSCs to the ET2 nanocomplex. The luminescent properties of this coupled ET2 complex were determinedand its ability to target and label CSCs was determined using the pluripotent human embryonic carcinoma cellline, NTERA-2. Fluorescence microscopy showed strong luminescent signals from ET2-exposed NTERA-2cells. It was also demonstrated that the ET2 nanocomplex effectively labeled up to 97.74% of the tested NTERA-2 cells, but only 2.35% of CCD-18Co human colon normal cells. Therefore, these results show that the ET2luminescent nanocomplex specifically targeted and labeled CSCs, and may be used for further applications infundamental and clinical research
A simple size-dependent isogeometric approach for bending analysis of functionally graded microplates using the modified strain gradient elasticity theory
No full textIn this study, a simple size-dependent isogeometric approach for bending analysis of functionally graded (FG) microplates using the modified strain gradient theory (MSGT), simple first-order shear deformation theory (sFSDT) and isogeometric analysis is presented for the first time. The present approach reduces one variable when comparing with the original first-order shear deformation theory (FSDT) within five variables and only considers three material length scale parameters (MLSPs) to capture size effects. Effective material properties as Young’s modulus, Poisson’s ratio and density mass are computed by a rule of mixture. Thanks to the principle of virtual work, the essential equations which are solved by the isogeometric analysis method, are derived. Rectangular and circular FG microplates with different boundary conditions, volume fraction and material length scale parameter are exampled to evaluate the deflections of FG microplates
Note on extension of the Young’s formula to inhomogeneous columns
No full textIn this Note the generalization of the celebrated formula by Young, applicable to homogeneous columns, is provided for inhomogeneous columns
Design Analysis, Installation and Performance Evaluation of a Hydraulic Ram Pump System with a Modified Waste Valve
Get PDFHydraulic ram pump is one of the oldest mechanical devices used for water lifting. A hydraulic ram pump has two moving parts which are the waste valve and delivery valve. As a lot of studies had been carried out investigating parameters possibly affecting the performance of a hydraulic ram pump, this study aimed to design and fabricate a modified waste valve for a hydraulic ram pump with parts made from locally available off-the-shelf materials. Results revealed that varying the height of the waste valve’s stroke significantly affected the relivery flow rate thus affecting its overall all efficiency.
Integrated Cross Sections of the Photo-Neutron Reactions Induced on Au with 60 Bremsstrahlung
Get PDFAbstract. Seven photo-neutron reactions 197Au(γ,xn)197-xAu (with x=1-7) produced by the bremsstrahlung end-point energy of 60 MeV were identified. In this work, we focus on the measurement of integrated sections. Experiments were carried out based on the activation method in combination with off-line gamma-ray spectrometric technique. The integrated cross sections of the investigated reactions were determined relative to that of the monitoring reaction 197Au(γ,n)196Au. To validate the experimental results, theoretical predictions were also made using the computer code TALYS 1.9. The current integrated cross-sections of the 197Au(γ,xn)197-xAu reactions with 60 MeV bremsstrahlung end point energy are measured for the first time
Observation of High Doppler Velocity Wings in the Nascent Wind of R Doradus
Get PDFWe study the morpho-kinematics in the nascent wind of AGB star R Doradus in the light of high Doppler velocity wings observed in the spectral lines of several species. We probe distances from the star between ∼10 and ∼100 au using ALMA observations of the emission of five different molecular lines. High Doppler velocity enhancements of the line emission are observed in the vicinity of the line of sight crossing the star, reminiscent of those recently interpreted as gas streams in the nascent wind of a similar AGB star, EP Aqr. They are present in both blue-shifted and red- shifted hemispheres but are not exactly back-to-back. They are accelerated at a typical rate of 0.7 km s au up to some 20 km s. Important differences are observed between the emissions of different molecules. We exclude an effect of improper continuum subtraction. However, in contrast to EP Aqr, the line of sight plays no particular role in the R Dor morpho-kinematics, shedding doubt on the validity of a gas stream interpretation. We discuss possible interpretations in terms of stellar pulsations or of rotation of the gas in the environment of the star. We conclude that, in the state of current knowledge, no fully convincing picture of the physics governing the production of such high velocities, typically twice as large as the terminal velocity, can be reliably drawn. New high resolution analyses of observations of the nascent wind of oxygen-rich AGB stars are needed to clarify the issue
NO2 GAS SENSOR BASED ON QCM COATED WITH IRON OXIDE NANORODS
No full textIron oxide nanorods were synthesized by chemical co-precipitation method. The structural and morphological characteristics of the as-synthesized nanorods were analyzed by X-ray diffraction (XRD) and scanning electron microscopy. The results show that the iron oxide nanorods include the mixture of Fe3O4, γ-Fe2O3 and FeOOH with the diameter and the length of iron oxide nanorods to be 30 nm and 100 nm, respectively. The iron oxide nanorods were then dispersed and deposited on the gold electrode of quartz crystal microbalance (QCM) for the gas sensing application. The iron oxide nanorods based QCM sensor was tested with various concentrations of numerous toxic gases at room temperature, including nitrogen dioxide (NO2), sulfur dioxide (SO2), ammonia (NH3), and carbon monoxide (CO). The testing results indicate that fabricated sensor exhibits high performance to NO2 in the concentration range from 5 ppm to 20 ppm
Large displacements of FGSW beams in thermal environment using a finite element formulation
Get PDFThe large displacements of functionally graded sandwich (FGSW) beams in thermal environment are studied using a finite element formulation. The beams are composed of three layers, a homogeneous core and two functionally graded face sheets with volume fraction of constituents following a power gradation law. The material properties of the beams are considered to be temperature-dependent. Based on Antman beam model and the total Lagrange formulation, a two-node nonlinear beam element taking the effect of temperature rise into account is formulated and employed in the study. The element with explicit expressions for the internal force vector and tangent stiffness matrix is derived using linear interpolations and reduced integration technique to avoid the shear locking. Newton-Raphson based iterative algorithm is employed in combination with the arc-length control method to compute the large displacement response of a cantilever FGSW beam subjected to end forces. The accuracy of the formulated element is confirmed through a comparison study. The effects of the material inhomogeneity, temperature rise and layer thickness ratio on the large deflection response of the beam are examined and highlighted