Analysis of glass-reinforced epoxy material for radio frequency resonator.

A radio frequency (RF) resonator using glass-reinforced epoxy material for C and X band is proposed in this paper. Microstrip line technology for RF over glass-reinforced epoxy material is analyzed. Coupling mechanism over RF material and parasitic coupling performance is explained utilizing even and odd mode impedance with relevant equivalent circuit. Babinet's principle is deployed to explicate the circular slot ground plane of the proposed resonator. The resonator is designed over four materials from different backgrounds which are glass-reinforced epoxy, polyester, gallium arsenide (GaAs), and rogers RO 4350B. Parametric studies and optimization algorithm are applied over the geometry of the microstrip resonator to achieve dual band response for C and X band. Resonator behaviors for different materials are concluded and compared for the same structure. The final design is fabricated over glass-reinforced epoxy material. The fabricated resonator shows a maximum directivity of 5.65 dBi and 6.62 dBi at 5.84 GHz and 8.16 GHz, respectively. The lowest resonance response is less than -20 dB for C band and -34 dB for X band. The resonator is prototyped using LPKF (S63) drilling machine to study the material behavior.

Analysis of resonance response performance of C-band antenna using parasitic element.

Analysis of the resonance response improvement of a planar C-band (4-8 GHz) antenna is proposed using parasitic element method. This parasitic element based method is validated for change in the active and parasitic antenna elements. A novel dual-band antenna for C-band application covering 5.7 GHz and 7.6 GHz is designed and fabricated. The antenna is composed of circular parasitic element with unequal microstrip lines at both sides and a rectangular partial ground plane. A fractional bandwidth of 13.5% has been achieved from 5.5 GHz to 6.3 GHz (WLAN band) for the lower band. The upper band covers from 7.1 GHz to 8 GHz with a fractional bandwidth of 12%. A gain of 6.4 dBi is achieved at the lower frequency and 4 dBi is achieved at the upper frequency. The VSWR of the antenna is less than 2 at the resonance frequency.

Evaluation of possible health risks of heavy metals by consumption of foodstuffs available in the central market of Rajshahi City, Bangladesh.

Considering the human health risk due to the consumption of foodstuffs, the concentrations of heavy metals (lead, manganese, chromium, cadmium, and arsenic) are investigated in vegetables, fruits, and fish species collected from the central market (called Shaheb Bazar) of Rajshahi City, Bangladesh. The foodstuffs examined for metal constituents are the basis of human nutrition in the study area. The highest concentrations of Mn and As in vegetables (onion and pointed gourd, respectively), Cr and Cd in fruits (black berry and mango, respectively), and Pb in fish (catla) are recorded. Health risks associated with these heavy metals are evaluated due to dietary intake. Target hazard quotient (THQ) and hazard index (HI) are calculated to evaluate the non-carcinogenic health risk from individual and combined heavy metals. The THQ values for individual heavy metals are below 1, suggesting that people would not experience significant health risks if they ingest a single heavy metal from one kind of foodstuff (e.g., vegetables). However, consumption of several of the foodstuffs could lead a potential health risk to human population since HI value is higher than 1. The relative contributions of vegetables, fishes, and fruits to HI are 49.44, 39.07, and 11.53 %, respectively. Also, the relative contributions of Pb, Cd, As, Mn, and Cr to HI are 51.81, 35.55, 11.73, 0.85, and 0.02 %, respectively. The estimation shows that the carcinogenic risk of arsenic exceeds the accepted risk level of 1 × 10(-6). Thus, the carcinogenic risk of arsenic for consumers is a matter of concern.

Depression and its association with socio-demographic characteristics among type 2 diabetes mellitus patients of Bangladesh.

Diabetes mellitus is being increasingly recognized as a serious global health problem and is frequently associated with co-morbid depression. A cross sectional study was conducted among 178 adult type 2 diabetes mellitus patients attending Institute of Research and Rehabilitation in Diabetes, Endocrine and Metabolic Disorders (BIRDEM), Dhaka, Bangladesh to find out influence of socio-demographic characteristics for occurrence of depression among them. Data were collected through face-to-face interview. Depressive symptoms were measured using Centre for Epidemiological Studies Depression Scale. Proportion of depression was found 34.8% which included 20.2% with severe depression and 14.6% with mild to moderate depression. Both mild to moderate and severe depression were significantly more common in female, odds ratios were 2.72 (95% CI=1.13-6.53) and 5.94 (95% CI=2.49-14.20), respectively. Currently not married respondents were also suffered from higher depressive symptoms. For mild to moderate depression odds ratio was 4.38 (95% CI=1.46-13.18) and for severe depression odds ratio was 9.51 (95% CI=3.69-24.50). Among socio-demographic characteristics marital status was identified as the best predictor of depression, which was followed by education upto secondary level, female sex and primary education. Depression was identified as a significant health problem among adult type 2 diabetes mellitus patients. Its association with socio-demographic characteristics should be considered while planning therapeutic approaches for diabetic patients.

An Am/Be neutron source and its use in integral tests of differential neutron reaction cross-section data.

An Am/Be neutron source, installed recently at the Rajshahi University, is described. Neutron flux mapping was done using the nuclear reactions (197)Au(n,gamma)(198)Au, (113)In(n,gamma)(114m)In, (115)In(n,n'gamma)(115m)In and (58)Ni(n,p)(58)Co. An approximate validation of the neutron spectral shape was done using five neutron threshold detectors and the iterative unfolding code SULSA. Integral cross sections of the reactions (54)Fe(n,p)(54)Mn, (59)Co(n,p)(59)Fe and (92)Mo(n,p)(92m)Nb were measured with fast neutrons (E(n)>1.5MeV) and compared with data calculated using the neutron spectral distribution and the excitation function of each reaction given in data libraries: an agreement within +/-6% was found.

Paratuberculosis in cattle and free-living exotic deer.

Paratuberculosis was studied among dairy cows and exotic deer that shared grazing areas at Point Reyes National Seashore, California. Of the 10 dairy herds tested, 5 (50%) were infected with Mycobacterium paratuberculosis (based on results of fecal culture). Mycobacterium paratuberculosis was cultured from 9 (8.7%) of the 103 bovine fecal samples and from 4 (3.9%) of the 103 bovine rectal mucosa scapings tested. Of 89 fecal samples from 52 axis deer (Axis axis) and 37 fallow deer (Dama dama), 5 (9.6%) and 3 (8.1%), respectively, contained M paratuberculosis. Culture of intestinal necropsy samples from the same deer indicated that 3 (5.8%) of the axis deer and 2 (5.4%) of the fallow deer were infected with M paratuberculosis. The cows were tested for serum antibodies by the complement-fixation test and by radioimmunoassay. Of 95 sera tested by complement fixation, 15 (15.8%) were positive, as were 15 (14.7%) of 102 sera tested by radioimmunoassay. Culture results and serologic test results were compared on a herd basis.