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Amplification-free and direct fluorometric determination of telomerase activity in cell lysates using chimeric DNA-templated silver nanoclusters
No full textA fluorogenic probe has been developed for determination of telomerase activity using chimeric DNA-templated silver nanoclusters (AgNCs). The formation of AgNCs was investigated before (route A) and after (route B) telomerase elongation reaction. Both routes caused selective quenching of the yellow emission of the AgNCs (best measured at excitation/emission wavelength of 470/557 nm) in telomerase-positive samples. The quenching mechanism was studied using synthetically elongated DNA to mimic the telomerase-catalyzed elongation. The findings show that quenching is due to the formation of parallel G-quadruplexes with a -TTA- loop in the telomerase elongated products. The assay was validated using different cancer cell extracts, with intra- and interassay coefficients of variations of <9.8%. The limits of detection for MCF7, RPMI 2650 and HT29 cell lines are 15, 22 and 39 cells/μL. This represents a distinct improvement over the existing telomeric repeat amplification protocol (TRAP) assay in terms of time, sensitivity and cost. Graphical Abstract A method was developed using chimeric DNA-templated silver nanoclusters to detect telomerase activity directly in cell extracts. The sensitivity of this new method outperforms the traditional TRAP assay, and without the need for amplification
Structural and bone marrow stem cell biocompatibility studies of hydrogel synthesized via chemo-enzymatic route
No full textNatural biopolymers have many attractive medical applications; however, complications due to fibrosis caused a reduction in diffusion and dispersal of nutrients and waste products. Consequently, severe immunocompatibility problems and poor mechanical and degradation properties in synthetic polymers ensue. Hence, the present study investigates a novel hydrogel material synthesized from caprolactone, ethylene glycol, ethylenediamine, polyethylene glycol, ammonium persulfate, and tetramethylethylenediamine via chemo-enzymatic route. Spectroscopic analyses indicated the formation of polyurea and polyhydroxyurethane as the primary building block of the hydrogel starting material. Biocompatibility studies showed positive observation in biosafety test using direct contact cytotoxicity assay in addition to active cellular growth on the hydrogel scaffold based on fluorescence observation. The synthesized hydrogel also exhibited (self)fluorescence properties under specific wavelength excitation. Hence, synthesized hydrogel could be a potential candidate for medical imaging as well as tissue engineering applications as a tissue expander, coating material, biosensor, and drug delivery system
Raman spectroscopy and FTIR spectroscopy studies of Mn-doped CdSe QDs at different particles size
No full textIn this paper, we exclusively report on raman spectroscopy and fourier-transform infrared (FTIR) spectroscopy results and analysis of zinc blende manganese-doped cadmium selenide quantum dots (Mn-doped CdSe QDs) that synthesized using inverse Micelle technique with physical size ranging from 3 to 14 nm. Two significant peaks were observed correspond to the raman scattering by longitudinal optical (LO) of phonon and its first overtone (2LO) which located near ∼ 200 and 400 cm−1 under an exposure of 532 nm incident laser The role of oleic acid acid as a surfactant and capping agent shows in FTIR spectra
Pyrolysis characteristics and kinetic studies of horse manure using thermogravimetric analysis
No full textHorse manure is a biowaste with bioenergy recovery potential for heat and power generation. However, there is no kinetics data in literature to date. In this work, a kinetic study of the pyrolysis process of horse manure is investigated through the use of thermogravimetric analyses. The samples were heated over a range of temperature from 298 to 927 K with four different heating rates of 1, 2, 5 and 10 K/min. The weight loss was measured by a thermogravimetric analyser in an inert atmosphere. The differential thermal gravimetric (DTG) thermogram shows that the highest reaction rate occurred at between 290.2 and 329.6 °C where the devolatilisation process was initiated to overcome the activation energy barrier of the manure. The activation energy and pre-exponential factor obtained by the Kissinger method, assumed to be constant throughout the whole pyrolysis process are 149 kJ/mol and 3.3 × 1012 s−1, respectively. The activation energy calculated from the non-isothermal Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS) and Friedman methods are 199.3, 200.2 and 194.6 kJ/mol, whereas the pre-exponential values are 9.3 × 1018, 1.8 × 1019 and 3.6 × 1020 s−1, respectively. The kinetic parameters determined based on interval conversional fraction shows good agreement. The high volatile and low ash content in horse manure indicates the potential for bioenergy recovery. The results of the kinetic study can be used for modelling devolatilisation and designing thermochemical conversion processes
Magnetic poly(β-cyclodextrin-ionic liquid) nanocomposites for micro-solid phase extraction of selected polycyclic aromatic hydrocarbons in rice samples prior to GC-FID analysis
No full textPoly(β-cyclodextrin functionalized ionic liquid) immobilized magnetic nanoparticles (Fe3O4@βCD-Vinyl-TDI) as sorbent in magnetic µ-SPE was developed for the determination of selected polycyclic aromatic hydrocarbons (PAHs) in rice samples coupled with gas chromatographic-flame ionization detector (GC-FID). The nanocomposite was characterized by various tools and significant parameters that affected the extraction efficiency of PAHs were investigated. The calibration curves were linear for the concentration ranging between 0.1 and 500 μg kg−1 with correlation determinations (R2) from 0.9970 to 0.9982 for all analytes. Detection limits ranged at 0.01–0.18 μg kg−1 in real matrix. The RSD values ranged at 2.95%–5.34% (intra-day) and 4.37%–7.05% (inter-day) precision for six varied days. The sorbents showed satisfactory reproducibility in 2.9% to 9.9% range and acceptable recovery values at 80.4%–112.4% were obtained for the real sample analysis. The optimized method was successfully applied to access content safety of selected PAHs for 24 kinds of commercial rice available in Malaysia
Parental Scaffolding in Mathematics Homework Among Malaysian Private Preschoolers: a Case Study
No full textThe study aims to have a better understanding on the parental scaffolding in mathematics homework among preschoolers in the Malaysian context. This is achieved by exploring to what extent Malaysian parents provide scaffolding to their preschoolers in mathematics homework interactions. Investigations about the strategies employed by the parents during scaffolding and non-scaffolding interactions were carried out. Three mothers, with different parenting styles and education levels, and their preschoolers were observed and interviewed. In general, the occurrences of contingency, fading and transfer of responsibility were found to be scarce. Diagnostic and intervention strategies were also analysed and discussed
Support for Gender Stereotypes: Does Madrasah Education Matter?
No full textThis paper examines the influence of the institutional nature of schools on gender stereotyping by exploring contrasts between non-religious and Islamic faith (that is madrasah) schools among secondary school-going adolescents in rural Bangladesh. In particular, differences in gender attitudes across school types are explored to elucidate what about schools matters. Using a uniquely designed survey to assess the influence of school type on student characteristics, we find large differences in stereotypical gender attitudes by school type and student gender. Madrasah students in general, and unrecognised madrasah students in particular, show unfavourable attitudes about women and their abilities compared to their peers in non-religious schools. However, these differences are diminished considerably in ordered probit models suggesting that school-level differences are explained by teacher characteristics such as the nature of teacher training and average family size of teachers. These estimated effects are robust to conditioning on a rich set of family characteristics
Silicon microring resonator waveguide-based graphene photodetector
No full textHere we study and analyze the performance of a graphene-based photodetector integrated onto a silicon-on-insulator microring using optical and electrical simulations. The electrical simulation reveals the role of material interface losses and allows one to extract key behavioral parameters such as dark current, responsivity and bandwidth
Adaptive multi-parent crossover GA for feature optimization in epileptic seizure identification
No full textEEG signal analysis involves multi-frequency non-stationary brain waves from multiple channels. Segmenting these signals, extracting features to obtain the important properties of the signal and classification are key aspects of detecting epileptic seizures. Despite the introduction of several techniques, it is very challenging when multiple EEG channels are involved. When many channels exist, a spatial filter is required to eliminate noise and extract relevant information. This adds a new dimension of complexity to the frequency feature space. In order to stabilize the classifier of the channels, feature selection is very important. Furthermore, and to improve the performance of a classifier, more data is required from EEG channels for complex problems. The increase of such data poses some challenges as it becomes difficult to identify the subject dependent bands when the channels increase. Hence, an automated process is required for such identification. The proposed approach in this work tends to tackle the multiple EEG channels problem by segmenting the EEG signals in the frequency domain based on changing spikes rather than the traditional time based windowing approach. While to reduce the overall dimensionality and preserve the class-dependent features an optimization approach is used. This process of selecting an optimal feature subset is an optimization problem. Thus, we propose an adaptive multi-parent crossover Genetic Algorithm (GA) for optimizing the features used in classifying epileptic seizures. The GA-based approach is used to optimize the various features obtained. It encodes the temporal and spatial filter estimates and optimize the feature selection with respect to the classification error. The classification was done using a Support Vector Machine (SVM). The proposed technique was evaluated using the publicly available epileptic seizure data from the machine learning repository of the UCI center for machine learning and intelligent systems. The proposed approach outperforms other ones and achieved a high level of accuracy. These results, indicate the ability of a multi-parent crossover GA in optimizing the feature selection process in EEG classification
Comparative Study of Indoor Propagation Model Below and Above 6 GHz for 5G Wireless Networks
No full textIt has been widely speculated that the performance of the next generation based wireless network should meet a transmission speed on the order of 1000 times more than the current cellular communication systems. The frequency bands above 6 GHz have received significant attention lately as a prospective band for next generation 5G systems. The propagation characteristics for 5G networks need to be fully understood for the 5G system design. This paper presents the channel propagation characteristics for a 5G system in line of sight (LOS) and non-LOS (NLOS) scenarios. The diffraction loss (DL) and frequency drop (FD) are investigated based on collected measurement data. Indoor measurement results obtained using a high-resolution channel sounder equipped with directional horn antennas at 3.5 GHz and 28 GHz as a comparative study of the two bands below and above 6 GHz. The parameters for path loss using different path loss models of single and multi-frequencies have been estimated. The excess delay, root mean square (RMS) delay spread and the power delay profile of received paths are analyzed. The results of the path loss models show that the path loss exponent (PLE) in this indoor environment is less than the free space path loss exponent for LOS scenario at both frequencies. Moreover, the PLE is not frequency dependent. The 3GPP path loss models for single and multi-frequency in LOS scenarios have good performance in terms of PLE that is as reliable as the physically-based models. Based on the proposed models, the diffraction loss at 28 GHz is approximately twice the diffraction loss at 3.5 GHz. The findings of the power delay profile and RMS delay spread indicate that these parameters are comparable for frequency bands below and above 6 GHz