Sayed Asaduzzaman

DESIGN AND CHARACTERIZATION OF PHOTONIC CRYSTAL FIBER FOR SENSING APPLICATIONS

Purpose: this study aimed to analyze the epidemiological aspects and evaluate the impact of late diagnosis on prognosis of gastrointestinal surgical emergencies at the National Hospital of Zinder (Niger). Patients and method: this is a prospective study from 1 January to 31 December 2013. All patients underwent surgery for digestive emergency were included. Results: We collected 302 patients. Emergencies digestive surgery accounted for 22% of 1358 cases of surgical emergencies recorded over the period of the study period. The sex ratio is 3/1 in favor of men. The average age of patients was 23 years. Digestive surgical emergencies affect more children (45%) and young adults (43%). The majority (70%) of our patients did not attend school and 49% were from rural areas. The diagnosis delay rule, 171 patients (57%) arrived to emergency department more than 48 hours after onset of symptoms. Abdominal pain with or without other signs was the main reason for consultation (92% of patients). 182 patients had a poor general status. The etiologies were dominated by peritonitis (52%) followed by intestinal obstruction (28%), and abdominal trauma with 10% of cases. The parietal suppuration isolated or associated with other morbidities was the main postoperative (28%). The average length of hospital stay was 9 days. 36 patients (12%) had died. Almost half of the deaths (47%) occurred within the first 48 hours of admission. The delay of admission and the surgical management was statistically significant effect on the prognosis (P<0.006, p< 0.0001). Conclusion: The prognosis of gastrointestinal surgical emergencies is highly correlated with the speed of diagnosis leading to appropriate treatment as soon as possible. This promptness is the only guarantee of a decline in the high morbidity and mortality which is often linked to dysfunction of our hospitals and/or accessibility problems faced by patients.

Proposal of simple gas sensor based on micro structure optical fiber

This paper presents a simple structure of photonic crystal fiber (PCF) based gas sensors. Gas sensors can be used in gas production facilities for safe measurement. The index guiding properties of two rings circular PCF have been analysed for different wavelength with the variation of the diameters of air holes in core and cladding. Finite-element method has been applied for numerical analysis. At the wavelength λ=1.66μm obtained maximum sensitivity is 13.94% and at the same time the confinement loss of the fiber is 2.74×10-4 dB/m. The proposed structure is more flexible for its high sensitivity, low confinement loss and simple structure compare to early proposed high sensitivity chemical sensor PCFs with a hollow high index ring defect at the centre.

Highly sensitive simple structure circular photonic crystal fiber based chemical sensor

A circular photonic crystal fiber (C-PCF) structure is presented in this paper as a chemical sensor where both core and cladding are micro structured. Finite element method (FEM) has been applied to investigate the propagation characteristics of proposed C-PCF structure. Relative sensitivity and Confinement loss are numerically examined and optimized by varying the different parameters of the proposed structure. Finally, it is found that the simple 3 rings C-PCF structure shows higher sensitivity as well as lower confinement loss at the wavelength 1.33μm.

Application of microarray-core based modified photonic crystal fiber in chemical sensing

This study presents a simple type of modified PCF (M-PCF) as a chemical sensor where both core and cladding are micro-structured. Different guiding properties of proposed M-PCF have been investigated for a wide range of wavelength using full vectorial finite element method (FEM). By varying pitch and hole diameter both of inner and outer layers, the relative sensitivity, refractive index and confinement loss are numerically examined and compared. At the wavelength 1.33μm it is observed that the relative sensitivity is improved 1.45 times and confinement loss is also reduced than prior work. Fabrication process and cost will be low of proposed M-PCF because of its structural simplicity.

Slotted-core photonic crystal fiber in gas-sensing application

Combustible or harmful gasses noticeable all around are adequate to decimating a geographical region of bringing about a flame, explosion, and venomous exposure. In this paper, a highly sensitive gas sensor based on slotted-core photonic crystal fiber has been presented which can be used as a gas sensor. The guiding properties of the proposed PCF are numerically investigated by employing finite element method (FEM). The Proposed PCF contains slotted core and a hexagonal cladding where the geometrical parameters are varied to optimized. Simulation result reveals that the proposed PCF shows a high relative sensitivity of 48.26%, the high birefringence of 2.17×10-2 and a lower confinement loss of 1.26×10 -5 dB/m. Effective area, Beat length, Splice loss, V-parameter are also reported in this paper.

Ultrahigh birefringence, ultralow material loss porous core single-mode fiber for terahertz wave guidance

In this paper, a novel polarization-maintaining single-mode photonic crystal fiber (PCF) has been suggested for terahertz (THz) transmission applications. The reported PCF has five layers of hexagonal cladding with two layers of porous core. The cladding and core territory of the PCF are constituted by circular and elliptical air cavities, accordingly acting as a dielectric medium. Different geometrical parameters of the proposed PCF including pitches and diameters of circular air holes with the major and minor axes of elliptical air cavities being varied with the optimized structure. Various effects on the proposed PCF such as eccentricity and porosity effects are also carefully investigated. The numerical process is investigated by one of the most popular methods, the finite element method (FEM). All numerical computational results have revealed the ultrahigh birefringence in the order of 1.19×10-02 as well as the ultralow bulk absorption material loss of 0.0689  cm-1 at the 1 THz activation frequency. Besides, the V-parameter is also investigated for checking the proposed fiber modality. The proposed single-mode porous core hexagonal PCF is expected to be useful for convenient broadband transmission and numerous applications in the areas of THz technology.

A comparative analysis of two different PCF structures for gas sensing application

Toxic or Flammable gases and leakage of the gas lines can be detected by photonic crystal fibers for avoiding pollution, explosion or fire. Two different structures of hollow core based Photonic crystal fiber (HC-PCF) has been presented in this paper. The sensitivity of the proposed structures was numerically investigated by finite element method (FEM) varying the optical and geometrical properties. The numerical results show that the proposed PCF with six air holes shows 2.22 times higher sensitivity than the PCF with eight air holes in the first layer. Both of the PCFs exhibit reduced confinement loss also. The proposed PCFs can sense the lower refractive index based gases (toxic/ flammable) at a wide range of wavelength 0.8 μm to 2μm.

Simulation based analysis of formalin detection through photonic crystal fiber

Formalin is a dangerous organic chemical substance in todays life. It is the solution of two substances; Formaldehyde and Water. Formalin is used forlong time preservation for various types of foods and other things from rotting. It affects human life to environmental ecology. Formalin detection is a challenging task. Without chemical experts, it is hard to detect and it is also a time consuming task. In this regard, a smart, reliable but simple detection technique is on demand. To detect it efficiently, the optical characteristic of Formalin such as refractive index is chosen for analysing. This paper presents a Photonic Crystal Fiber (PCF) based Formalin sensing technique. A simple PCF structure has been proposed to sense Formalin. The structure follows all the optical properties for the propagation of light energy. An intensive simulation has been done. The simulation results show that the proposed simple PCF structure is handy to detect Formalin with a remarkable sensitivity.

Numerical analysis of O-PCF structure for sensing applications with high relative sensitivity

In this study, micro structured core and cladding based O-PCF has been analyzed by its propagation characteristics. The effects of pitch variation, total power consumption and effective refractive index are investigated on O-PCF. The analyzing process takes place by the full vectorial finite element method (FEM). The analysis O-PCF contains five layers of the air holes in octagonal shape which increases relative sensitivity significantly and decreases confinement loss than the prior structures. Beyond that, the analysis O-PCF can sense the three chemicals water, Ethanol and Benzene at a wide range of wavelength.

Association Assessment among Risk Factors and Breast Cancer in a Low Income Country: Bangladesh

BACKGROUND In the low incoming country Bangladesh, breast cancer is second most common neoplasm and is increasing at an alarming rate among females. Lack of awareness and illiteracy are contributory factors for late presentation and therefore mortality. PURPOSE To examine associations of different factors with breast cancer mortality and to raise awareness among the women of society in Bangladesh. MATERIALS AND METHODS This descriptive case-control study was conducted on 160 participants from April 2011 till July 2014. Through a valid questionnaire covering personal and family history, data were collected by face to face interview. For analyzing correlations among factors with breast cancer data, binary logistic regression, Pearsons χ2- value, odd ratios and p-value tests were conducted with SPSS version 20. RESULTS The mean age of the patients was 43.0 (SD= ± 11.12). In ascending order the leading significant factors were hormone therapy (p<0.0000, OR=4.897), abortion (p<0.0001, OR=3.452), early start menarche (p<0.0002, OR=3.500), family history (p<0.0022, OR=3.235), and late menopause (p<0.0093, OR=3.674) with both χ2 test and logistic regression analyses. Non-significant factors were cancer experience, fatty food habits, marital status and taking alcohol. CONCLUSIONS Regarding the investigation of this study, significant and insignificant factors correlation visualization with breast cancer will be helpful to increase awareness among Bangladeshi women as well as all over the world.