Design of Microstrip Bandpass Filter with Defected Microstrip Structure (DMS)

This paper presents a novel design of Chebyshev wideband bandpass filter (BPF) realized using microstrip with Defected Microstrip Structure (DMS) to produce bandpass and band reject characteristics simultaneously. This new class of filter is designed based upon λ_g0/4 short-circuited stubs structure of 7th degree. The filter exhibits wide bandwidth response from 3 to 6 GHz with a return loss, S11, better than - 20 dB and insertion loss, S21, of around -0.1 dB respectively. While, the DMS exhibit a band reject response better than -20 dB at a frequency of 5.2 GHz with a narrow bandwidth. Therefore, the integrated BPF and DMS produce wideband bandpass and band reject response simultaneously in order to remove any undesired signals in the passband of the bandpass response. This design is simulated on a Roger Duroid RO4350 with a dielectric constant,ε_r of 3.48 and a thickness of 0.508 mm. The simulation results show a promising performance that could be further examined during fabrication and experimental works in a laboratory. This type of filter is useful in any RF/ microwave communication systems particularly to eliminate any undesired signals in wideband applications. The reduction of overall physical volume and weight as well as cost and maintaining its excellent performance can also be achieved using this technique

Ultrastructural observation of nasal and pulmonary intracellular Pasteurella multocida A:3 in rabbits

Sixteen 8- to 9-week-old Pasteurella multocida-free rabbits were divided into two equal groups. Eight rabbits in one group were inoculated intranasally with P. multocida type A:3. The other eight were inoculated intranasally with phosphate-buffered saline and used as controls. Nasal swabs taken before and after inoculation were cultured for bacterial isolation. Post-mortem nasal swabs and lung samples were cultured for bacteriological isolation. Nasal mucosa and lung samples were collected and processed for transmission electron microscopy. Pasteurella multocida was isolated from the nasal cavity of all infected rabbits and from the lungs of four infected rabbits. Degenerative ultrastructural changes in epithelial cells and endothelial cells were seen in the infected rabbits. Deciliation of the cilated epithelium and hyperplasia of the goblet cells in the nasal mucosa were noted. Thickening of the alveolar septa due to hyperplasia of type II pneumocytes, swelling of the endothelial lining of capillaries and infiltration of inflammatory cells were also observed. Intracellular invasion of the nasal epithelial cells and of type II pneumocytes by the organism was observed. Coccobacilli were observed in membrane-bound vacuoles in the cytoplasm of these cells. The vacuoles were adjacent to the host-cell mitochondria and some of these vacuoles appeared to be fused to the mitochondrial membrane. Some type I pneumocytes with intracellular membrane-bound vacuoles containing bacterial cells showed protrusions, which appeared to detach into the alveolar lumina. These results indicated that P. multocida serotype A:3 in rabbits can invade the epithelial cell and cause structural changes in the interstitium, epithelium and endothelium. Heterophils and macrophages appear to play important roles in tissue injury

Ultrastructural pathology of nasal and tracheal mucosa of rabbits experimentally infected with Pasteurella multocida serotype D:1

Sixteen 8- to 9-week-old Pasteurella multocida-free New Zealand White rabbits were dividec into two equal groups. The first group was inoculated intranasally with P multocida serotype D:1 strain and the second group that was inoculated with phosphate-buffered saline (PBS) only was used as a control group. Pasteurella multocida was isolated from the nasal cavity of all infected rabbits in group 1 and from tracheal swabs of seven rabbits in this group. Four rabbits in group 1 died with clinical signs of septicaemia, two rabbits had mucopurulent nasal discharge and pneumonic lesions and the other two did not show any clinical signs or gross lesions. The ultrastructural changes detected were deciliation or clumping of cilia of ciliated epithelium, cellular swelling, vacuolation and sloughing. The subepithelial capillaries showed congestion, intravascular fibrin deposition, platelets aggregation and endothelial injury. Pasteurella multocida was observed attached to the injured endothelial cells. Heterophils, mast cells, vacuolated monocytes and macrophages infiltrated the lamina propria and between the degenerated epithelial cells. ©2001 Harcourt Publishers Ltd

Determination of predominate Leptospira serovars circulating among rat populations in Kuala Lumpur

Leptospirosis is re-emerging in Malaysia and many other tropical countries. Its infection of human and animal’s worldwide. The study was carried out to identify predominate Leptospira serovars within rat populations in Kuala Lumpur (KL) by microscopic agglutination test (MAT). As well to investigate the frequency of infection by polymerase chain reaction assays (PCR). The isolated cultures that obtained from culturing kidney tissue of 112 trapped rats from four sites in KL, were identified by MAT using panel of 16 standard hyper immune anti-sera. Besides, identification of Leptospira strains by PCR amplification with G1/G2 and ompL1 Borgpetersenii genes. Results from typing by MAT revealed that 8/57 (7.1%) of cultured isolates reacted against; hyper-immune antisera of serogroup Javanica and 13/57 (22.8%) against serogroup Bataviae. Whereas, the rest of isolates recorded across reactivity 1/20 against serogroups; Icterohaemorrhagiae 2/57, Canicola 1/57, Australis 2/57. From PCR-G1/G2; 50/112 (50.9%) cultures were positive included (40/57 cultures positive to isolation and 10/55 cultures negative to isolation). While, from PCR-ompL1 Borgpetersenii gene; 21/112 (18.7%) cultures positive included (17/57 cultures positive to isolation and 4/55 cultures were negative to isolation). It is obvious from this study that serogroups Javanica and Bataviae were the predominant among rat populations in KL. Also it revealed the high frequency of pathogenic strains among rat populations and their potential risk of humans and animals contracting infection