Md. Anwar Hossain

Health Risk Assessment of Pesticide Residues via Dietary Intake of Market Vegetables from Dhaka, Bangladesh

The present study was designed to assess the health risk of pesticide residues via dietary intake of vegetables collected from four top agro-based markets of Dhaka, Bangladesh. High performance liquid chromatography with a photo diode array detector (HPLC-PDA) was used to determine six organophosphorus (chlorpyrifos, fenitrothion, parathion, ethion, acephate, fenthion), two carbamate (carbaryl and carbofuran) and one pyrethroid (cypermethrin) pesticide residues in twelve samples of three common vegetables (tomato, lady’s finger and brinjal). Pesticide residues ranged from below detectable limit (<0.01) to 0.36 mg/kg. Acephate, chlorpyrifos, ethion, carbaryl and cypermethrin were detected in only one sample, while co-occurrence occurred twice for fenitrothion and parathion. Apart from chlorpyrifos in tomato and cypermethrin in brinjal, all pesticide residues exceeded the maximum residue limit (MRL). Hazard risk index (HRI) for ethion (10.12) and carbaryl (1.09) was found in lady’s finger and tomato, respectively. Rest of the pesticide residues were classified as not a health risk. A continuous monitoring and strict regulation should be enforced regarding control of pesticide residues in vegetables and other food commodities.

Effect of multipath fading and multiple access interference on broadband code division multiple access systems

In this paper, the performance of uncoded uplink transmissions in a broadband code division multiple access (CDMA) system using tapped delay line (TDL) antenna array under multipath conditions is investigated. An expression for broadband CDMA system is derived to calculate the optimal weights of TDL antenna array. Using the derived broadband expression, the performance of TDL antenna array is investigated and compared with that of the already existing narrowband systems. Simulation results show that TDL antenna array can reduce multipath fading and multiple access interference (MAI). It is shown that if the signal-to-noise ratio (SNR) level is maintained at 20 dB and two-ray channel model is used, two antennas with four taps each can support 30 users with a BER of 10−3. If three-ray channel model is used, the same antenna arrangement is not enough to support 30 users. To support these 30 users with BER of 10−3, the number of taps needs to be increased to eight. Finally, the number of taps needs to be further increased to 16 if four-ray channel model is used. Not only that, the SNR should also be increased to 25 dB to achieve the same BER. Copyright

Design of highly birefringent holey fibers with near-zero ultra-flattened chromatic dispersion and ultralow confinement loss

We present a holey fiber (HF) with elliptical air-holes located in the center core area that ensures high birefringence, near-zero ultra-flattened chromatic dispersion and very low confinement losses in a wide wavelength range. The finite element method with perfectly matched boundary layer is used to investigate the guiding properties. It is demonstrated that it is possible to design a low-loss dispersion-flattened HF with a high birefringence of 0.0033 at a 1.55 µm wavelength. According to simulation, near-zero ultra-flattened dispersion of 0 ± 0.5 ps/nm/km is obtained in a 1.25 to 1.65 µm wavelength range with low confinement losses of 0.0008 dB/km in the entire band of interest.

Effect of Chemical Modification of Jute Fabrics on the Performance of Urethane Acrylate-based Composites

Jute fabric-reinforced urethane acrylate-based composites were prepared using urethane acrylate oligomer (M-1200) in methanol solvent along with photoinitiator (Darocur-1173) followed by ultraviolet (UV) radiation. Different formulations were prepared by varying oligomer in the solvent by 50—90% (by weight). Jute fabrics treated with 70% oligomer, 28% methanol, and 2% photoinitiator followed by UV radiation showed the best mechanical properties of the resulting composites. For further improvement of the mechanical properties of the composites, jute fabrics were first treated with different percentages of methylmethacrylate (MMA) in methanol with photoinitiator and cured under UV radiation and then again the composites were fabricated by the oligomer. Urea was incorporated into the MMA formulation and was found to have the potential to improve the mechanical properties of the composites.

Center Wavelength Adoption Techniques for Supercontinuum Generating Highly Nonlinear Noncircular Core Photonic Crystal Fiber

A supercontinuum (SC) light source is designed using a highly nonlinear noncircular core photonic crystal fiber (HNL-NcPCF) with all-normal group velocity dispersion (GVD) to demonstrate how simply an SC can be generated at different center wavelengths in a normal GVD regime. Using the finite element method (FEM) with a perfectly matched layer (PML), the design of two or more PCF-based light sources at different neighboring center wavelengths is demonstrated numerically. Moreover, SC generations are demonstrated numerically at 1.06, 1.31, and 1.55 µm in a normal dispersion regime using picosecond optical pulses.

ANTIDIARRHEAL AND CYTOTOXIC ACTIVITIES OF ALSTONIA SCHOLARIS BARK

Alstonia scholaris (Apoc ynaceae) is an evergreen and tropical tree native to the Indian subcontinent and South - east Asia . It is a well known medicinal plant and commonly known as ‘ Chhatim ’ in Bangladesh . Traditionally the bark is used to treat anemia , menstrual disorders, colic, diarrhea , dysentery and acute arthritis. In the present study, the ethanolic extract of bark was investigated for phytochemical properties as well as anti diarrh eal and cytotoxic activities. In antidiarrheal activity test (castor oil induced diarrhea), the extra ct was taken as a dose of 250mg /kg body w eigh t orally in Swiss albino mice and t he standard drug l operamide, at a dose of 50mg/kg. The cytotoxic test was performed on brine shrimp ( Artemia salina ) . T he ethanolic extract contains alkaloid, reducing sug ar, saponin and t annin . It significantly increased mean latent period (1.09 hr) and decreased the frequency of defecation , which w ere comparable to the standard drug ( P <0.0 1) . In case of c ytotoxic test , the LC 50 & LC 90 were found as 22. 25 & 95.28 µg/ml , res pectively . The findings suggest that Alstonia scholaris possesses antidiarrh eal and cytotoxic activities.

Cost Effective Proposal to Produce Clinical Engineering Professional to Sustain the Health Care Services of Developing Countries Such as Bangladesh

In the recent years, health care services come under spotlight of the Clinical Engineering Professional. Hence developed countries produce skilled clinical engineers to sustain their health care management since past about 35 years as well as most developing countries. However, economically fluctuating developing countries such as Bangladesh could not produce skilled clinical engineers due to lack of awareness and high cost. As the results, most of the developed countries such as Bangladesh could sustain the standard health care services. This paper illustrates an economical approach to produce the skilled clinical engineers to improve the present health care services which faces lots of problems. Our proposal will be more cost effective to produce skilled clinical engineers for the benefit of health care services. The clinical engineers are the costly potential resources for the health care technology to sustain the health care services among the health care technology personnel. We firmly believe that the current ideas of the health care planers, health policy makers and health stakeholders about clinical engineers will be clear. Public and private hospitals will be encouraged to produce and introduce skilled clinical engineers.

Effects of Shadowing on the Performances of Mobile Ad Hoc Networks

Free-space model and two-ray ground reflection model have been widely used in the literatures as the propagation models to investigate the performance of an ad hoc network. But these two models are too simple to represent a real world scenario. A more realistic model namely shadowing propagation model has been used in this paper to investigate the performances of ad hoc network. In shadowing propagation model a mobile node may receive a packet at a signal level that is below a required threshold level. This low signal level affects the routing protocol as well as the medium access control scheme of a network. In this paper, the effects of shadowing on the performance of an ad hoc network have been investigated. Two solutions have also been suggested in this paper to overcome the effects of shadowing.

Performance comparison of Selection Combining diversity receivers for different modulation schemes in OFDM system

This paper deals with the performance analysis (i.e., Symbol Error Rate) of M-ary Phase-shift-keying (M-PSK) and M-ary Quadrature Amplitude Modulation (M-QAM) to transmit information using Selection Combining (SC) diversity technique over flat Rayleigh communication channel with Orthogonal Frequency Division Multiplexing (OFDM). It is well known that the multipath fading phenomenon is an inherent characteristic of wireless channel. In this paper, it is shown how selection combining diversity scheme enhances reliability in wireless communication by minimizing the channel fluctuations due to fading. The simulation results show that the Signal-to-Noise Ration (SNR) varies between M-PSK and M-QAM but better SNR gain achieved as the number of receiving antenna increases like for two, three and four receiving antennas around 20–27 dB, 22–30 dB, 23–31 dB diversity gains are found respectively.

Scientific Opinion on the Standards and Regulations of Irradiated Food

Our markets and economies become more global and it is very much essential that food products must fulfill high standards of quality and safety to trade across borders. Food irradiation is one of them and it is a powerful food processing technology for controlling spoilage and reducing food-borne pathogens. International standards and regulations for food irradiation covering food safety and quality, labeling, plant protection and environment, packaging issue, dosimetry, facility management, nuclear safety and security, consumer behavior and so on established by the national and international organization in the world. International trade in irradiated foods increasing with wider acceptance of this technology by the consumer. Nowadays, more than 60 countries accepting and trading irradiated foods or food ingredients or food products. This paper focusing on irradiated food with consumer acceptance and standards and regulation of irradiated food as well as international trade issues.