Surface Acoustic Wave Delay Line and Its Potential Applications for Corrosion Monitoring

Surface acoustic wave (SAW) devices has been used as sensors for temperature, pressure, traces of vapor and gases as well as filters and resonators in communication systems. It has also been demonstrated as a corrosion sensor designed to monitor atmospheric corrosion of copper. In this work, ruggedness of SAW sensor will be further explored and applied to sense and monitor corrosion. As a deliverable, a novel technique to extract corrosion rate of iron using SAW sensor is demonstrated. SAW is typically generated and detected with inter-digital transducers (IDT) on a piezoelectric substrate. For sensing application, sensing elements are placed in between the IDTs. Any physical changes in the sensing elements, alter the frequency or phase of the detected SAW. The SAW is designed to be generated at pre-designed central frequency using impulse response (IR) model. The modulated SAW due to the changes to sensing element is then investigated using coupling of mode (COM) model. As expected, the thinning of sensing element showed a significant phase shift in SAW. Based on the design, SAW device is fabricated using typical lithography process. Its transfer characteristics i.e. transmission S21 and reflection S11 coefficients are then measured using vector network analyzer (VNA). In dry condition, the transfer characteristics are similar to the simulated ones. In partially wet condition i.e. a small corrosive droplet on the sensing element, the transfer characteristics are modulated and later saturated after a certain time. The modulation is believed to be due to the mass unloading effect i.e. thinning of metallic sensing element and evaporation of droplet. Analyzing the phase of S21 reveals that the unwrapped phase of S21 can be correlated with the thinning of metallic sensing element. From the correlation, a corrosion rate is determined. The corrosion rate obtained from this technique agrees reasonably well with the corrosion rate obtained from linear polarization resistance (LPR) technique

Association of HbA1c and total cholesterol levels in child bearing age using injectable contraceptives.

Introduction: Injectables contraceptives are convenient and highly effective methods for fertility regulation, being simple to administer and long acting, but affect lipids by increasing total cholesterol and triglycerides1 , the major health risk of injectables contraceptives are cardiovascular diseases (CVS), particularly heart attacks (myocardial infarction), stroke and venous thromboembolism2 Hormonal contraceptives have traditionally being thought to adversely affect carbohydrate metabolism by increasing insulin resistance and decreasing glucose tolerance.3 Objective: To determine and compare the values of HbA1c and total cholesterol levels in child bearing age using Depot Medroxy Progesterone Acetate (DMPA). Methodology: This comparative cross-sectional study was conducted at Department of Pharmacology, Basic Medical Sciences Institute, Jinnah Postgraduate Medical Centre, Karachi, from January 2016 to December 2016. Total 200 fertile females in their child bearing age were selected. They were divided into two groups, Group 1 (controls) and Group 2 (DMPA users).  Total cholesterol levels were measured before starting therapy, in the middle and the end of the therapy by using standard procedures on semi- automatic clinical chemistry analyser (Microlab 400). HbA1c levels were measured by using semiautomatic clinical chemistry HbA1c analyser (Microlab 300). Results were analyzed by using Statistical Package for Social Sciences (SPSS) version 21. Results:  DMPA causes significant increase (p < 0.05) in total cholesterol, but insignificant changes (p > 0.05) in HbA1c levels. Conclusion: It is suggested that total cholesterol and HbS1c levels should be measured before starting and during the course of injectable contraceptives to the subjects. As deranged cholesterol levels can increase the risk of cardio- vascular disease outcomes.4 Also injectable contraceptives may cause pre- diabetes (increased in levels of HbA1c 5.7-6.4)5. Key Words:  Depot medroxyprogesterone Acetate (DMPA), Glycated hemoglobin (HbA1c), Total Cholesterol, Statistical Package for Social Sciences (SPSS)

Spiral Computed Tomographic Evaluation and Endodontic Management of a Mandibular Second Molar with Four Roots. A Case Report and Literature Review

The vast majority of mandibular second molars have two roots with three root canals; however, variations in molar root canal anatomy are not uncommon. To the best of our knowledge, four rooted mandibular second molar with three mesial roots and one distal root has never been reported. Herein, we present the endodontic management of a four rooted mandibular second molar tooth, diagnosed with the assistance of spiral computed tomography (SCT) with a brief review of literature

Atypical Facio-Scapulo-Humeral Dystrophy with Facial Sparing: A Case Report

ABSTRACT Facio-Scapulo-Humeral Dystrophy (FSHD) is an autosomal dominant and third most common inherited muscular dystrophy. Typical phenotype of FSHD initially affects the muscles of the face and upper arm. Atypical FSHD refers to genetically confirmed FSHD with phenotypic variations. Scapulo-Humeral Dystrophy (SHD) is the most common atypical form of FSDH characterized by no facial muscle weakness on clinical examination, while other signs remain consistent with FSHD. We report a 31-year-old male who presented with foot drop and had an unexpected presentation as SHD. Provisional diagnosis of SHD was based on careful medical history, physical examination findings, modest rise in muscle enzymes, and needle electromyography findings of myopathy. Muscle biopsy suggested dystrophic changes which supported the diagnosis of FSHD with facial sparing. Rehabilitation plan included patient and family counseling/education, lifestyle modifications, energy conservation strategies, right ankle foot orthosis, and therapeutic exercises with regular follow-up for monitoring of the disease

Methane and n-hexane ignition in a newly developed diaphragmless shock tube

Shock tubes have been routinely used to generate reliable chemical kinetic data for gas-phase chemistry. The conventional diaphragm-rupture mode for shock tube operation presents many challenges that may ultimately affect the quality of chemical kinetics data. Numerous diaphragmless concepts have been developed to overcome the drawbacks of using diaphragms. Most of these diaphragmless designs require significant alterations in the driver section of the shock tube and, in some cases, fail to match the performance of the diaphragm-mode of operation. In the present work, an existing diaphragm-type shock tube is retrofitted with a fast-acting valve, and the performance of the diaphragmless shock tube is evaluated for investigating the ignition of methane and n-hexane. The diaphragmless shock tube reported here presents many advantages, such as eliminating the use of diaphragms, avoiding substantial manual effort during experiments, automating the shock tube facility, having good control over driver conditions, and obtaining good repeatability for reliable gas-phase chemical kinetic studies. Ignition delay time measurements have been performed in the diaphragmless shock tube for three methane mixtures and two n-hexane mixtures at $P_5$ = 10 - 20 bar and $T_5$ = 738 - 1537 K. The results obtained for fuel-rich, fuel-lean, and oxygen-rich (undiluted) mixtures show very good agreement with previously reported experimental data and literature kinetic models (AramcoMech 3.0 [1] for methane and Zhang et al. mechanism [2] for n-hexane). The study presents an easy and simple method to upgrade conventional shock tubes to a diaphragmless mode of operation and opens new possibilities for reliable chemical kinetics investigations.Comment: 22 pages, 9 figure

Clinical Accuracy of Inflammatory Markers Combined with Ultrasound in Acute Appendicitis

Objective: To determine the clinical accuracy of inflammatory markers combined with ultrasound, in acute appendicitis keeping histopathology as gold standard.Study design: Cross Sectional (validation) study.Study setting: Surgical B ward, Department of Surgery Khyber teaching hospital Peshawar.Duration of Study: 07 months i.e from 1st September 2014 to 31st of Mar, 2015Methodology: All patients having acute appendicitis were subjected to blood sampling for CRP, TLC and neutrophil%. After that all these patients were subjected to ultrasonography to detect the presence or absence of appendicitis. All removed appendices were sent for histopathology which was taken as the gold standard.Results In the present study, TLC had the highest sensitivity (77.68%) followed by neutrophil% (69.96%), CRP (67.10%) and U/Sound (62.96%) respectively. While U/Sound had the highest specificity (70.59%) followed by CRP and TLC (64.71% each) and neutrophil% (58.82%) respectively. When all the four tests were combined   the sensitivity, specificity, (99.17% and 98.45%) increased significantly. It was seen that when all the four tests were negative, appendicitis could be safely ruled out and surgery could be deferred in these patients.It would reduce the rate of negative appendicectomies.Conclusion: TLC  contains  important  diagnostic   information  and  hence  should  always  be included in  the diagnostic  workup of  acute appendicitis.  The sensitivity of   CRP and Neut. % is low individually, but when combined with TLC and u/sound the sensitivity and specificity increases significantly. But it is stressed that history and clinical examination by a skilled surgeon still remain important in diagnosing acute appendicitis, and its importance cannot be denied. The investigations can be used as an adjuvant to a surgeon’s clinical diagnosis

Factors Affecting Decision Making Process on Spine Surgery: Patients’ Perspective

Objective:  To determine the factors that affects the decision making process of the spine surgery from a patient’s perspective. Material and Methods:  The study was carried on 264 patients admitted for spine surgery in the Department of Neurosurgery, Khyber Teaching Hospital, Peshawar, Pakistan. Data was collected from patients on questionnaire using a Likert scale. Reliability was ensured by Cronbach alpha. Results:  The results for regression analysis revealed that there is a significant negative relationship between previous experiences and decision for spine surgery in patients (β = -0.156, p = 0.001 < 0.05). There is a significant positive influence of emotional and social state (β = 0.193, p = 0.002), information & counselling (β = 0.097, p = 0.011), socioeconomic status (β = 0.131, p = 0.004), severity of disability (β = 0.602, p = 0.000), ineffective conservative treatment (β9 = 0.082, p = 0.013) and intensity of pain (β = 0.527, p = 0.000) on decision for spine surgery in patients. The independent variables, including physical health, gender role and age were found to have an insignificant effect on the decision for spine surgery (p > 0.05). Conclusion:  It is concluded that the factors affecting the decision of patients on spine surgery included previous experience, emotional & social state, information & counselling, socioeconomic status, severity of disability, ineffectiveness of previously taken conservative treatment and intensity of pain

Dual-camera high-speed imaging of n-hexane oxidation in a high-pressure shock tube

Shock tubes are widely used in the study of chemical kinetics. Its benefits rely on the almost ideal shock-heating process that provides high temperatures and pressures to a chemical system for a limited test time. Just like any reactor, shock tubes are not immune to non-ideal effects. The study of conditions that might deviate experiments from ideal conditions is thus of the utmost importance. High-speed imaging has been proven to be a powerful bytool to analyze non-ideal / non-homogenous combustion in shock tubes. In this work, dual-camera high-speed imaging experiments were performed at 10, 15 and 20 bar in a high-pressure shock tube (HPST). An optical section was designed as an extension of the HPST which enabled simultaneous visualization from the endwall and the sidewall of the driven section of the shock tube. n-Hexane, a fuel with a negative temperature coefficient (NTC) behavior that has been identified as prone to non-homogenous ignition, is used as a test fuel. Reactive mixtures and thermodynamic conditions were selected to visually analyze ignition processes at the high-temperature, NTC and low-temperature regimes. Non-homogeneous ignition was observed mostly at the local maximum of the IDT, which is comprised by the high-temperature and NTC regions. Stoichiometric n-hexane mixture with high fuel loading (5% n-hexane) presented the highest deviation from constant volume chemical kinetic simulations. The inclusion of helium as a bath gas to mitigate preignition was tested and it showed to improve the susceptibility of the mixtures to develop reaction fronts. The modified Sankaran criterion for the identification of ignition regimes in shock tubes was tested and it showed an overall good agreement against the experimental observations.Comment: 23 pages, 11 figures, 1 tabl

DIAMOnDS - DIstributed Agents for MObile & Dynamic Services

Distributed Services Architecture with support for mobile agents between services, offer significantly improved communication and computational flexibility. The uses of agents allow execution of complex operations that involve large amounts of data to be processed effectively using distributed resources. The prototype system Distributed Agents for Mobile and Dynamic Services (DIAMOnDS), allows a service to send agents on its behalf, to other services, to perform data manipulation and processing. Agents have been implemented as mobile services that are discovered using the Jini Lookup mechanism and used by other services for task management and communication. Agents provide proxies for interaction with other services as well as specific GUI to monitor and control the agent activity. Thus agents acting on behalf of one service cooperate with other services to carry out a job, providing inter-operation of loosely coupled services in a semi-autonomous way. Remote file system access functionality has been incorporated by the agent framework and allows services to dynamically share and browse the file system resources of hosts, running the services. Generic database access functionality has been implemented in the mobile agent framework that allows performing complex data mining and processing operations efficiently in distributed system. A basic data searching agent is also implemented that performs a query based search in a file system. The testing of the framework was carried out on WAN by moving Connectivity Test agents between AgentStations in CERN, Switzerland and NUST, Pakistan.Comment: 7 pages, 4 figures, CHEP03, La Jolla, California, March 24-28, 200