Economics of Education: An Idea for a Poor Nation

Bangladesh has been beset with manifold everyday problems even after becoming a lower middle-income country in 2015. This paper argues that the huge population is a key problem in this country and the existing higher education at general universities and colleges is generally unproductive. Against this backdrop, this study suggests that the country's population problem can be transformed into human resources by introducing a purposeful higher education system. The purposeful education will have three broad-based impacts on the society. First, wastage of education will be minimised and efficiency will go up as people will get a job matching their skills they gain from their study. Second, there will be less possibility of unemployment as students will be provided with skills related to the demands of local and foreign job markets, and the governmental will help them secure jobs. Third, the existing size of the population will go down significantly in line with the students moving abroad with jobs in a revolutionary way, which could revolutionise the country's socioeconomic condition

Resonant Terahertz Transmission of Plasmonic Subwavelength Hole Arrays

The purpose of this study was to examine the extraordinary terahertz (THz) transmission through subwavelength hole arrays structured on metals, highly doped and photo-doped silicon. Conventional photolithography process was used to structure subwavelength hole arrays on good and poor metallic conductors as well as on thin, doped silicon wafers. The transmission properties of the THz radiation through these hole arrays were investigated using terahertz time-domain spectroscopy (THz-TDS) and optical pump-THz probe techniques. The frequency-dependent transmission spectra through hole arrays show extraordinary transmission at resonance peaks. This phenomenon is attributed to the resonance excitation of surface plasmon polaritos (SPPs) which might find applications in THz photonic devices. The incident THz radiation excites SPPs on the incidence surface of the array; the SPPs then tunnel through the subwavelength holes and reradiate as THz radiation from the other surface. This study demonstrated the effect of hole shape, dielectric properties of the metallic and surrounding media, polarization dependence, and the metal thickness on the enhanced THz transmission. Rectangular and elliptical hole shapes show higher peak transmission when the polarization of incident THz beam is perpendicular to the longer axis of the holes. Amplitude of the peak resonance decreases and shifts toward the lower frequencies when the dielectric constant of the surrounding medium increases. Efficiently enhanced transmission has been realized with the metallic arrays having thickness of one-third of the skin depth. For similar array, transmission is higher for the array made from metals having higher electrical conductivity. Furthermore, the transmission properties of a lightly doped silicon hole array can be dynamically tuned from two-dimensional photonic crystal features to SPPs resonance with increased photo-doping density by varying external optical excitation power.School of Electrical & Computer Engineerin

Transmission properties of terahertz pulses through an ultrathin subwavelength silicon hole array

We demonstrate extraordinary THz transmission of an array of subwavelength apertures patterned on ultrathin highly doped silicon by reactive ion etching. The zero-order transmission spectra exhibit well-defined maxima and minima which are attributed to the excitation of surface-plasmon polaritons and Wood's anomaly. The transmission anisotropy is investigated with respect to the orientation of the elliptical hole array in the frequency range from 0.2 to 3.5 THz, and we notice that the transmission increases significantly when the major axis of the elliptical hole is perpendicular to the polarization of THz beam. In addition, redshift and reduction in transmission amplitude are observed when the surrounding dielectric permittivity is increased.Peer reviewedElectrical and Computer Engineerin

Metronidazole induced neurotoxicity: a case report

Metronidazole is a well-known antimicrobial agent, used for the treatment of anaerobic bacterial and protozoal infections. It is generally well tolerated with common side effects like nausea, dizziness, headache and metallic taste in the mouth. But prolonged use of metronidazole can cause neurotoxicity like ataxic gait, dysarthria, seizures and encephalopathy. Here, we are reporting a case of a 60 years old male patient who was a chronic alcoholic with liver abscess and he developed acute ataxia and dysarthria after four weeks use of metronidazole. The causality of metronidazole in this case was “probable” with score 7 as per Naranjo scale. The patient was managed by discontinuing the metronidazole and there was considerable improvement in his gait and speech after that. The case was recorded properly in adverse drug reaction reporting form and was sent to nearby adverse drug reaction (ADR) monitoring centre

Terahertz studies of carrier dynamics and dielectric response of n-type, freestanding epitaxial GaN

We report the characterization of the complex conductivity and dielectric function of GaN by terahertz time-domain spectroscopy. Transmission measurements are performed on an n-type, 180-um-thick, freestanding GaN crystal. Frequency dependent electron dynamics, power absorption and optical dispersion are observed over the frequency range from 0.1 to 4.0 THz. The measured conductivity is well fit by Drude theory.Peer reviewedElectrical and Computer Engineerin

Solid Oxide Fuel Cell (SOFC); A New Approach of Energy Generation during the Pandemic COVID-19

The new coronavirus (COVID-19) has started spreading all over the world. Every infected is fighting to recover a little and every health worker is fighting to save a single life in this pandemic. There is no place for patients to stay in the hospital, health workers are given all possible services to save their lives. In this situation, uninterrupted power system is needed, which can be supplied by solid oxide fuel cells (SOFCs). Therefore, solid oxide fuel cells (SOFCs) are becoming attractive day by day with competing environmental friendly energy sources due to high energy efficiency, low emission rate and comparatively low operating cost. The purpose of this work is to investigate how copper-doped perovskite electrode materials impact the performance of solid oxide fuel cells (SOFCs) to overcome such crucial times successfully. Different synthesis process of Cu-based electrodes and analyzing electrochemical properties were investigated in this work. The evaluation were performed in terms of synthesis process, sintering temperature, lattice type and parameters, electrical conductivity, thermal expansion coefficients (TEC), polarization resistance, activation energy, and power density. In order to provide additional energy during this pandemic COVID-19, low-cost, highly performed, and durable materials are needed to make SOFC

Vibrational Signatures in the THz Spectrum of 1,3-DNB: A First-Principles and Experimental Study

Understanding the fundamental processes of light-matter interaction is important for detection of explosives and other energetic materials, which are active in the infrared and terahertz (THz) region. We report a comprehensive study on electronic and vibrational lattice properties of structurally similar 1,3-dinitrobenzene (1,3- DNB) crystals through first-principles electronic structure calculations and THz spectroscopy measurements on polycrystalline samples. Starting from reported x-ray crystal structures, we use density-functional theory (DFT) with periodic boundary conditions to optimize the structures and perform linear response calculations of the vibrational properties at zero phonon momentum. The theoretically identified normal modes agree qualitatively with those obtained experimentally in a frequency range up to 2.5 THz and quantitatively at much higher frequencies. The latter frequencies are set by intra-molecular forces. Our results suggest that van der Waals dispersion forces need to be included to improve the agreement between theory and experiment in the THz region, which is dominated by intermolecular modes and sensitive to details in the DFT calculation. An improved comparison is needed to assess and distinguish between intra- and intermolecular vibrational modes characteristic of energetic materials.Comment: 5 pages, 5 figure